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-rw-r--r--kernel/cgroup/Makefile9
-rw-r--r--kernel/cgroup/cgroup-internal.h296
-rw-r--r--kernel/cgroup/cgroup-v1.c1308
-rw-r--r--kernel/cgroup/cgroup.c7062
-rw-r--r--kernel/cgroup/cpuset.c4321
-rw-r--r--kernel/cgroup/debug.c381
-rw-r--r--kernel/cgroup/freezer.c323
-rw-r--r--kernel/cgroup/legacy_freezer.c487
-rw-r--r--kernel/cgroup/misc.c422
-rw-r--r--kernel/cgroup/namespace.c151
-rw-r--r--kernel/cgroup/pids.c387
-rw-r--r--kernel/cgroup/rdma.c612
-rw-r--r--kernel/cgroup/rstat.c541
13 files changed, 16300 insertions, 0 deletions
diff --git a/kernel/cgroup/Makefile b/kernel/cgroup/Makefile
new file mode 100644
index 0000000000..12f8457ad1
--- /dev/null
+++ b/kernel/cgroup/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-y := cgroup.o rstat.o namespace.o cgroup-v1.o freezer.o
+
+obj-$(CONFIG_CGROUP_FREEZER) += legacy_freezer.o
+obj-$(CONFIG_CGROUP_PIDS) += pids.o
+obj-$(CONFIG_CGROUP_RDMA) += rdma.o
+obj-$(CONFIG_CPUSETS) += cpuset.o
+obj-$(CONFIG_CGROUP_MISC) += misc.o
+obj-$(CONFIG_CGROUP_DEBUG) += debug.o
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
new file mode 100644
index 0000000000..c56071f150
--- /dev/null
+++ b/kernel/cgroup/cgroup-internal.h
@@ -0,0 +1,296 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __CGROUP_INTERNAL_H
+#define __CGROUP_INTERNAL_H
+
+#include <linux/cgroup.h>
+#include <linux/kernfs.h>
+#include <linux/workqueue.h>
+#include <linux/list.h>
+#include <linux/refcount.h>
+#include <linux/fs_parser.h>
+
+#define TRACE_CGROUP_PATH_LEN 1024
+extern spinlock_t trace_cgroup_path_lock;
+extern char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
+extern void __init enable_debug_cgroup(void);
+
+/*
+ * cgroup_path() takes a spin lock. It is good practice not to take
+ * spin locks within trace point handlers, as they are mostly hidden
+ * from normal view. As cgroup_path() can take the kernfs_rename_lock
+ * spin lock, it is best to not call that function from the trace event
+ * handler.
+ *
+ * Note: trace_cgroup_##type##_enabled() is a static branch that will only
+ * be set when the trace event is enabled.
+ */
+#define TRACE_CGROUP_PATH(type, cgrp, ...) \
+ do { \
+ if (trace_cgroup_##type##_enabled()) { \
+ unsigned long flags; \
+ spin_lock_irqsave(&trace_cgroup_path_lock, \
+ flags); \
+ cgroup_path(cgrp, trace_cgroup_path, \
+ TRACE_CGROUP_PATH_LEN); \
+ trace_cgroup_##type(cgrp, trace_cgroup_path, \
+ ##__VA_ARGS__); \
+ spin_unlock_irqrestore(&trace_cgroup_path_lock, \
+ flags); \
+ } \
+ } while (0)
+
+/*
+ * The cgroup filesystem superblock creation/mount context.
+ */
+struct cgroup_fs_context {
+ struct kernfs_fs_context kfc;
+ struct cgroup_root *root;
+ struct cgroup_namespace *ns;
+ unsigned int flags; /* CGRP_ROOT_* flags */
+
+ /* cgroup1 bits */
+ bool cpuset_clone_children;
+ bool none; /* User explicitly requested empty subsystem */
+ bool all_ss; /* Seen 'all' option */
+ u16 subsys_mask; /* Selected subsystems */
+ char *name; /* Hierarchy name */
+ char *release_agent; /* Path for release notifications */
+};
+
+static inline struct cgroup_fs_context *cgroup_fc2context(struct fs_context *fc)
+{
+ struct kernfs_fs_context *kfc = fc->fs_private;
+
+ return container_of(kfc, struct cgroup_fs_context, kfc);
+}
+
+struct cgroup_pidlist;
+
+struct cgroup_file_ctx {
+ struct cgroup_namespace *ns;
+
+ struct {
+ void *trigger;
+ } psi;
+
+ struct {
+ bool started;
+ struct css_task_iter iter;
+ } procs;
+
+ struct {
+ struct cgroup_pidlist *pidlist;
+ } procs1;
+};
+
+/*
+ * A cgroup can be associated with multiple css_sets as different tasks may
+ * belong to different cgroups on different hierarchies. In the other
+ * direction, a css_set is naturally associated with multiple cgroups.
+ * This M:N relationship is represented by the following link structure
+ * which exists for each association and allows traversing the associations
+ * from both sides.
+ */
+struct cgrp_cset_link {
+ /* the cgroup and css_set this link associates */
+ struct cgroup *cgrp;
+ struct css_set *cset;
+
+ /* list of cgrp_cset_links anchored at cgrp->cset_links */
+ struct list_head cset_link;
+
+ /* list of cgrp_cset_links anchored at css_set->cgrp_links */
+ struct list_head cgrp_link;
+};
+
+/* used to track tasks and csets during migration */
+struct cgroup_taskset {
+ /* the src and dst cset list running through cset->mg_node */
+ struct list_head src_csets;
+ struct list_head dst_csets;
+
+ /* the number of tasks in the set */
+ int nr_tasks;
+
+ /* the subsys currently being processed */
+ int ssid;
+
+ /*
+ * Fields for cgroup_taskset_*() iteration.
+ *
+ * Before migration is committed, the target migration tasks are on
+ * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of
+ * the csets on ->dst_csets. ->csets point to either ->src_csets
+ * or ->dst_csets depending on whether migration is committed.
+ *
+ * ->cur_csets and ->cur_task point to the current task position
+ * during iteration.
+ */
+ struct list_head *csets;
+ struct css_set *cur_cset;
+ struct task_struct *cur_task;
+};
+
+/* migration context also tracks preloading */
+struct cgroup_mgctx {
+ /*
+ * Preloaded source and destination csets. Used to guarantee
+ * atomic success or failure on actual migration.
+ */
+ struct list_head preloaded_src_csets;
+ struct list_head preloaded_dst_csets;
+
+ /* tasks and csets to migrate */
+ struct cgroup_taskset tset;
+
+ /* subsystems affected by migration */
+ u16 ss_mask;
+};
+
+#define CGROUP_TASKSET_INIT(tset) \
+{ \
+ .src_csets = LIST_HEAD_INIT(tset.src_csets), \
+ .dst_csets = LIST_HEAD_INIT(tset.dst_csets), \
+ .csets = &tset.src_csets, \
+}
+
+#define CGROUP_MGCTX_INIT(name) \
+{ \
+ LIST_HEAD_INIT(name.preloaded_src_csets), \
+ LIST_HEAD_INIT(name.preloaded_dst_csets), \
+ CGROUP_TASKSET_INIT(name.tset), \
+}
+
+#define DEFINE_CGROUP_MGCTX(name) \
+ struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name)
+
+extern spinlock_t css_set_lock;
+extern struct cgroup_subsys *cgroup_subsys[];
+extern struct list_head cgroup_roots;
+
+/* iterate across the hierarchies */
+#define for_each_root(root) \
+ list_for_each_entry((root), &cgroup_roots, root_list)
+
+/**
+ * for_each_subsys - iterate all enabled cgroup subsystems
+ * @ss: the iteration cursor
+ * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
+ */
+#define for_each_subsys(ss, ssid) \
+ for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
+ (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
+
+static inline bool cgroup_is_dead(const struct cgroup *cgrp)
+{
+ return !(cgrp->self.flags & CSS_ONLINE);
+}
+
+static inline bool notify_on_release(const struct cgroup *cgrp)
+{
+ return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
+}
+
+void put_css_set_locked(struct css_set *cset);
+
+static inline void put_css_set(struct css_set *cset)
+{
+ unsigned long flags;
+
+ /*
+ * Ensure that the refcount doesn't hit zero while any readers
+ * can see it. Similar to atomic_dec_and_lock(), but for an
+ * rwlock
+ */
+ if (refcount_dec_not_one(&cset->refcount))
+ return;
+
+ spin_lock_irqsave(&css_set_lock, flags);
+ put_css_set_locked(cset);
+ spin_unlock_irqrestore(&css_set_lock, flags);
+}
+
+/*
+ * refcounted get/put for css_set objects
+ */
+static inline void get_css_set(struct css_set *cset)
+{
+ refcount_inc(&cset->refcount);
+}
+
+bool cgroup_ssid_enabled(int ssid);
+bool cgroup_on_dfl(const struct cgroup *cgrp);
+
+struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
+struct cgroup *task_cgroup_from_root(struct task_struct *task,
+ struct cgroup_root *root);
+struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
+void cgroup_kn_unlock(struct kernfs_node *kn);
+int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
+ struct cgroup_namespace *ns);
+
+void cgroup_favor_dynmods(struct cgroup_root *root, bool favor);
+void cgroup_free_root(struct cgroup_root *root);
+void init_cgroup_root(struct cgroup_fs_context *ctx);
+int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask);
+int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
+int cgroup_do_get_tree(struct fs_context *fc);
+
+int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp);
+void cgroup_migrate_finish(struct cgroup_mgctx *mgctx);
+void cgroup_migrate_add_src(struct css_set *src_cset, struct cgroup *dst_cgrp,
+ struct cgroup_mgctx *mgctx);
+int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx);
+int cgroup_migrate(struct task_struct *leader, bool threadgroup,
+ struct cgroup_mgctx *mgctx);
+
+int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
+ bool threadgroup);
+void cgroup_attach_lock(bool lock_threadgroup);
+void cgroup_attach_unlock(bool lock_threadgroup);
+struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup,
+ bool *locked)
+ __acquires(&cgroup_threadgroup_rwsem);
+void cgroup_procs_write_finish(struct task_struct *task, bool locked)
+ __releases(&cgroup_threadgroup_rwsem);
+
+void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
+
+int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
+int cgroup_rmdir(struct kernfs_node *kn);
+int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
+ struct kernfs_root *kf_root);
+
+int __cgroup_task_count(const struct cgroup *cgrp);
+int cgroup_task_count(const struct cgroup *cgrp);
+
+/*
+ * rstat.c
+ */
+int cgroup_rstat_init(struct cgroup *cgrp);
+void cgroup_rstat_exit(struct cgroup *cgrp);
+void cgroup_rstat_boot(void);
+void cgroup_base_stat_cputime_show(struct seq_file *seq);
+
+/*
+ * namespace.c
+ */
+extern const struct proc_ns_operations cgroupns_operations;
+
+/*
+ * cgroup-v1.c
+ */
+extern struct cftype cgroup1_base_files[];
+extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
+extern const struct fs_parameter_spec cgroup1_fs_parameters[];
+
+int proc_cgroupstats_show(struct seq_file *m, void *v);
+bool cgroup1_ssid_disabled(int ssid);
+void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
+void cgroup1_release_agent(struct work_struct *work);
+void cgroup1_check_for_release(struct cgroup *cgrp);
+int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param);
+int cgroup1_get_tree(struct fs_context *fc);
+int cgroup1_reconfigure(struct fs_context *ctx);
+
+#endif /* __CGROUP_INTERNAL_H */
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
new file mode 100644
index 0000000000..76db6c67e3
--- /dev/null
+++ b/kernel/cgroup/cgroup-v1.c
@@ -0,0 +1,1308 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include "cgroup-internal.h"
+
+#include <linux/ctype.h>
+#include <linux/kmod.h>
+#include <linux/sort.h>
+#include <linux/delay.h>
+#include <linux/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task.h>
+#include <linux/magic.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/delayacct.h>
+#include <linux/pid_namespace.h>
+#include <linux/cgroupstats.h>
+#include <linux/fs_parser.h>
+
+#include <trace/events/cgroup.h>
+
+/*
+ * pidlists linger the following amount before being destroyed. The goal
+ * is avoiding frequent destruction in the middle of consecutive read calls
+ * Expiring in the middle is a performance problem not a correctness one.
+ * 1 sec should be enough.
+ */
+#define CGROUP_PIDLIST_DESTROY_DELAY HZ
+
+/* Controllers blocked by the commandline in v1 */
+static u16 cgroup_no_v1_mask;
+
+/* disable named v1 mounts */
+static bool cgroup_no_v1_named;
+
+/*
+ * pidlist destructions need to be flushed on cgroup destruction. Use a
+ * separate workqueue as flush domain.
+ */
+static struct workqueue_struct *cgroup_pidlist_destroy_wq;
+
+/* protects cgroup_subsys->release_agent_path */
+static DEFINE_SPINLOCK(release_agent_path_lock);
+
+bool cgroup1_ssid_disabled(int ssid)
+{
+ return cgroup_no_v1_mask & (1 << ssid);
+}
+
+/**
+ * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
+ * @from: attach to all cgroups of a given task
+ * @tsk: the task to be attached
+ *
+ * Return: %0 on success or a negative errno code on failure
+ */
+int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
+{
+ struct cgroup_root *root;
+ int retval = 0;
+
+ cgroup_lock();
+ cgroup_attach_lock(true);
+ for_each_root(root) {
+ struct cgroup *from_cgrp;
+
+ spin_lock_irq(&css_set_lock);
+ from_cgrp = task_cgroup_from_root(from, root);
+ spin_unlock_irq(&css_set_lock);
+
+ retval = cgroup_attach_task(from_cgrp, tsk, false);
+ if (retval)
+ break;
+ }
+ cgroup_attach_unlock(true);
+ cgroup_unlock();
+
+ return retval;
+}
+EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
+
+/**
+ * cgroup_transfer_tasks - move tasks from one cgroup to another
+ * @to: cgroup to which the tasks will be moved
+ * @from: cgroup in which the tasks currently reside
+ *
+ * Locking rules between cgroup_post_fork() and the migration path
+ * guarantee that, if a task is forking while being migrated, the new child
+ * is guaranteed to be either visible in the source cgroup after the
+ * parent's migration is complete or put into the target cgroup. No task
+ * can slip out of migration through forking.
+ *
+ * Return: %0 on success or a negative errno code on failure
+ */
+int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
+{
+ DEFINE_CGROUP_MGCTX(mgctx);
+ struct cgrp_cset_link *link;
+ struct css_task_iter it;
+ struct task_struct *task;
+ int ret;
+
+ if (cgroup_on_dfl(to))
+ return -EINVAL;
+
+ ret = cgroup_migrate_vet_dst(to);
+ if (ret)
+ return ret;
+
+ cgroup_lock();
+
+ cgroup_attach_lock(true);
+
+ /* all tasks in @from are being moved, all csets are source */
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry(link, &from->cset_links, cset_link)
+ cgroup_migrate_add_src(link->cset, to, &mgctx);
+ spin_unlock_irq(&css_set_lock);
+
+ ret = cgroup_migrate_prepare_dst(&mgctx);
+ if (ret)
+ goto out_err;
+
+ /*
+ * Migrate tasks one-by-one until @from is empty. This fails iff
+ * ->can_attach() fails.
+ */
+ do {
+ css_task_iter_start(&from->self, 0, &it);
+
+ do {
+ task = css_task_iter_next(&it);
+ } while (task && (task->flags & PF_EXITING));
+
+ if (task)
+ get_task_struct(task);
+ css_task_iter_end(&it);
+
+ if (task) {
+ ret = cgroup_migrate(task, false, &mgctx);
+ if (!ret)
+ TRACE_CGROUP_PATH(transfer_tasks, to, task, false);
+ put_task_struct(task);
+ }
+ } while (task && !ret);
+out_err:
+ cgroup_migrate_finish(&mgctx);
+ cgroup_attach_unlock(true);
+ cgroup_unlock();
+ return ret;
+}
+
+/*
+ * Stuff for reading the 'tasks'/'procs' files.
+ *
+ * Reading this file can return large amounts of data if a cgroup has
+ * *lots* of attached tasks. So it may need several calls to read(),
+ * but we cannot guarantee that the information we produce is correct
+ * unless we produce it entirely atomically.
+ *
+ */
+
+/* which pidlist file are we talking about? */
+enum cgroup_filetype {
+ CGROUP_FILE_PROCS,
+ CGROUP_FILE_TASKS,
+};
+
+/*
+ * A pidlist is a list of pids that virtually represents the contents of one
+ * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
+ * a pair (one each for procs, tasks) for each pid namespace that's relevant
+ * to the cgroup.
+ */
+struct cgroup_pidlist {
+ /*
+ * used to find which pidlist is wanted. doesn't change as long as
+ * this particular list stays in the list.
+ */
+ struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
+ /* array of xids */
+ pid_t *list;
+ /* how many elements the above list has */
+ int length;
+ /* each of these stored in a list by its cgroup */
+ struct list_head links;
+ /* pointer to the cgroup we belong to, for list removal purposes */
+ struct cgroup *owner;
+ /* for delayed destruction */
+ struct delayed_work destroy_dwork;
+};
+
+/*
+ * Used to destroy all pidlists lingering waiting for destroy timer. None
+ * should be left afterwards.
+ */
+void cgroup1_pidlist_destroy_all(struct cgroup *cgrp)
+{
+ struct cgroup_pidlist *l, *tmp_l;
+
+ mutex_lock(&cgrp->pidlist_mutex);
+ list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
+ mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
+ mutex_unlock(&cgrp->pidlist_mutex);
+
+ flush_workqueue(cgroup_pidlist_destroy_wq);
+ BUG_ON(!list_empty(&cgrp->pidlists));
+}
+
+static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
+{
+ struct delayed_work *dwork = to_delayed_work(work);
+ struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
+ destroy_dwork);
+ struct cgroup_pidlist *tofree = NULL;
+
+ mutex_lock(&l->owner->pidlist_mutex);
+
+ /*
+ * Destroy iff we didn't get queued again. The state won't change
+ * as destroy_dwork can only be queued while locked.
+ */
+ if (!delayed_work_pending(dwork)) {
+ list_del(&l->links);
+ kvfree(l->list);
+ put_pid_ns(l->key.ns);
+ tofree = l;
+ }
+
+ mutex_unlock(&l->owner->pidlist_mutex);
+ kfree(tofree);
+}
+
+/*
+ * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
+ * Returns the number of unique elements.
+ */
+static int pidlist_uniq(pid_t *list, int length)
+{
+ int src, dest = 1;
+
+ /*
+ * we presume the 0th element is unique, so i starts at 1. trivial
+ * edge cases first; no work needs to be done for either
+ */
+ if (length == 0 || length == 1)
+ return length;
+ /* src and dest walk down the list; dest counts unique elements */
+ for (src = 1; src < length; src++) {
+ /* find next unique element */
+ while (list[src] == list[src-1]) {
+ src++;
+ if (src == length)
+ goto after;
+ }
+ /* dest always points to where the next unique element goes */
+ list[dest] = list[src];
+ dest++;
+ }
+after:
+ return dest;
+}
+
+/*
+ * The two pid files - task and cgroup.procs - guaranteed that the result
+ * is sorted, which forced this whole pidlist fiasco. As pid order is
+ * different per namespace, each namespace needs differently sorted list,
+ * making it impossible to use, for example, single rbtree of member tasks
+ * sorted by task pointer. As pidlists can be fairly large, allocating one
+ * per open file is dangerous, so cgroup had to implement shared pool of
+ * pidlists keyed by cgroup and namespace.
+ */
+static int cmppid(const void *a, const void *b)
+{
+ return *(pid_t *)a - *(pid_t *)b;
+}
+
+static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
+ enum cgroup_filetype type)
+{
+ struct cgroup_pidlist *l;
+ /* don't need task_nsproxy() if we're looking at ourself */
+ struct pid_namespace *ns = task_active_pid_ns(current);
+
+ lockdep_assert_held(&cgrp->pidlist_mutex);
+
+ list_for_each_entry(l, &cgrp->pidlists, links)
+ if (l->key.type == type && l->key.ns == ns)
+ return l;
+ return NULL;
+}
+
+/*
+ * find the appropriate pidlist for our purpose (given procs vs tasks)
+ * returns with the lock on that pidlist already held, and takes care
+ * of the use count, or returns NULL with no locks held if we're out of
+ * memory.
+ */
+static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
+ enum cgroup_filetype type)
+{
+ struct cgroup_pidlist *l;
+
+ lockdep_assert_held(&cgrp->pidlist_mutex);
+
+ l = cgroup_pidlist_find(cgrp, type);
+ if (l)
+ return l;
+
+ /* entry not found; create a new one */
+ l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
+ if (!l)
+ return l;
+
+ INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
+ l->key.type = type;
+ /* don't need task_nsproxy() if we're looking at ourself */
+ l->key.ns = get_pid_ns(task_active_pid_ns(current));
+ l->owner = cgrp;
+ list_add(&l->links, &cgrp->pidlists);
+ return l;
+}
+
+/*
+ * Load a cgroup's pidarray with either procs' tgids or tasks' pids
+ */
+static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
+ struct cgroup_pidlist **lp)
+{
+ pid_t *array;
+ int length;
+ int pid, n = 0; /* used for populating the array */
+ struct css_task_iter it;
+ struct task_struct *tsk;
+ struct cgroup_pidlist *l;
+
+ lockdep_assert_held(&cgrp->pidlist_mutex);
+
+ /*
+ * If cgroup gets more users after we read count, we won't have
+ * enough space - tough. This race is indistinguishable to the
+ * caller from the case that the additional cgroup users didn't
+ * show up until sometime later on.
+ */
+ length = cgroup_task_count(cgrp);
+ array = kvmalloc_array(length, sizeof(pid_t), GFP_KERNEL);
+ if (!array)
+ return -ENOMEM;
+ /* now, populate the array */
+ css_task_iter_start(&cgrp->self, 0, &it);
+ while ((tsk = css_task_iter_next(&it))) {
+ if (unlikely(n == length))
+ break;
+ /* get tgid or pid for procs or tasks file respectively */
+ if (type == CGROUP_FILE_PROCS)
+ pid = task_tgid_vnr(tsk);
+ else
+ pid = task_pid_vnr(tsk);
+ if (pid > 0) /* make sure to only use valid results */
+ array[n++] = pid;
+ }
+ css_task_iter_end(&it);
+ length = n;
+ /* now sort & strip out duplicates (tgids or recycled thread PIDs) */
+ sort(array, length, sizeof(pid_t), cmppid, NULL);
+ length = pidlist_uniq(array, length);
+
+ l = cgroup_pidlist_find_create(cgrp, type);
+ if (!l) {
+ kvfree(array);
+ return -ENOMEM;
+ }
+
+ /* store array, freeing old if necessary */
+ kvfree(l->list);
+ l->list = array;
+ l->length = length;
+ *lp = l;
+ return 0;
+}
+
+/*
+ * seq_file methods for the tasks/procs files. The seq_file position is the
+ * next pid to display; the seq_file iterator is a pointer to the pid
+ * in the cgroup->l->list array.
+ */
+
+static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
+{
+ /*
+ * Initially we receive a position value that corresponds to
+ * one more than the last pid shown (or 0 on the first call or
+ * after a seek to the start). Use a binary-search to find the
+ * next pid to display, if any
+ */
+ struct kernfs_open_file *of = s->private;
+ struct cgroup_file_ctx *ctx = of->priv;
+ struct cgroup *cgrp = seq_css(s)->cgroup;
+ struct cgroup_pidlist *l;
+ enum cgroup_filetype type = seq_cft(s)->private;
+ int index = 0, pid = *pos;
+ int *iter, ret;
+
+ mutex_lock(&cgrp->pidlist_mutex);
+
+ /*
+ * !NULL @ctx->procs1.pidlist indicates that this isn't the first
+ * start() after open. If the matching pidlist is around, we can use
+ * that. Look for it. Note that @ctx->procs1.pidlist can't be used
+ * directly. It could already have been destroyed.
+ */
+ if (ctx->procs1.pidlist)
+ ctx->procs1.pidlist = cgroup_pidlist_find(cgrp, type);
+
+ /*
+ * Either this is the first start() after open or the matching
+ * pidlist has been destroyed inbetween. Create a new one.
+ */
+ if (!ctx->procs1.pidlist) {
+ ret = pidlist_array_load(cgrp, type, &ctx->procs1.pidlist);
+ if (ret)
+ return ERR_PTR(ret);
+ }
+ l = ctx->procs1.pidlist;
+
+ if (pid) {
+ int end = l->length;
+
+ while (index < end) {
+ int mid = (index + end) / 2;
+ if (l->list[mid] == pid) {
+ index = mid;
+ break;
+ } else if (l->list[mid] < pid)
+ index = mid + 1;
+ else
+ end = mid;
+ }
+ }
+ /* If we're off the end of the array, we're done */
+ if (index >= l->length)
+ return NULL;
+ /* Update the abstract position to be the actual pid that we found */
+ iter = l->list + index;
+ *pos = *iter;
+ return iter;
+}
+
+static void cgroup_pidlist_stop(struct seq_file *s, void *v)
+{
+ struct kernfs_open_file *of = s->private;
+ struct cgroup_file_ctx *ctx = of->priv;
+ struct cgroup_pidlist *l = ctx->procs1.pidlist;
+
+ if (l)
+ mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
+ CGROUP_PIDLIST_DESTROY_DELAY);
+ mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
+}
+
+static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
+{
+ struct kernfs_open_file *of = s->private;
+ struct cgroup_file_ctx *ctx = of->priv;
+ struct cgroup_pidlist *l = ctx->procs1.pidlist;
+ pid_t *p = v;
+ pid_t *end = l->list + l->length;
+ /*
+ * Advance to the next pid in the array. If this goes off the
+ * end, we're done
+ */
+ p++;
+ if (p >= end) {
+ (*pos)++;
+ return NULL;
+ } else {
+ *pos = *p;
+ return p;
+ }
+}
+
+static int cgroup_pidlist_show(struct seq_file *s, void *v)
+{
+ seq_printf(s, "%d\n", *(int *)v);
+
+ return 0;
+}
+
+static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off,
+ bool threadgroup)
+{
+ struct cgroup *cgrp;
+ struct task_struct *task;
+ const struct cred *cred, *tcred;
+ ssize_t ret;
+ bool locked;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENODEV;
+
+ task = cgroup_procs_write_start(buf, threadgroup, &locked);
+ ret = PTR_ERR_OR_ZERO(task);
+ if (ret)
+ goto out_unlock;
+
+ /*
+ * Even if we're attaching all tasks in the thread group, we only need
+ * to check permissions on one of them. Check permissions using the
+ * credentials from file open to protect against inherited fd attacks.
+ */
+ cred = of->file->f_cred;
+ tcred = get_task_cred(task);
+ if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
+ !uid_eq(cred->euid, tcred->uid) &&
+ !uid_eq(cred->euid, tcred->suid))
+ ret = -EACCES;
+ put_cred(tcred);
+ if (ret)
+ goto out_finish;
+
+ ret = cgroup_attach_task(cgrp, task, threadgroup);
+
+out_finish:
+ cgroup_procs_write_finish(task, locked);
+out_unlock:
+ cgroup_kn_unlock(of->kn);
+
+ return ret ?: nbytes;
+}
+
+static ssize_t cgroup1_procs_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ return __cgroup1_procs_write(of, buf, nbytes, off, true);
+}
+
+static ssize_t cgroup1_tasks_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ return __cgroup1_procs_write(of, buf, nbytes, off, false);
+}
+
+static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cgroup *cgrp;
+ struct cgroup_file_ctx *ctx;
+
+ BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
+
+ /*
+ * Release agent gets called with all capabilities,
+ * require capabilities to set release agent.
+ */
+ ctx = of->priv;
+ if ((ctx->ns->user_ns != &init_user_ns) ||
+ !file_ns_capable(of->file, &init_user_ns, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENODEV;
+ spin_lock(&release_agent_path_lock);
+ strscpy(cgrp->root->release_agent_path, strstrip(buf),
+ sizeof(cgrp->root->release_agent_path));
+ spin_unlock(&release_agent_path_lock);
+ cgroup_kn_unlock(of->kn);
+ return nbytes;
+}
+
+static int cgroup_release_agent_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+ spin_lock(&release_agent_path_lock);
+ seq_puts(seq, cgrp->root->release_agent_path);
+ spin_unlock(&release_agent_path_lock);
+ seq_putc(seq, '\n');
+ return 0;
+}
+
+static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
+{
+ seq_puts(seq, "0\n");
+ return 0;
+}
+
+static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ return notify_on_release(css->cgroup);
+}
+
+static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
+{
+ if (val)
+ set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
+ else
+ clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
+ return 0;
+}
+
+static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+}
+
+static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
+{
+ if (val)
+ set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+ else
+ clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+ return 0;
+}
+
+/* cgroup core interface files for the legacy hierarchies */
+struct cftype cgroup1_base_files[] = {
+ {
+ .name = "cgroup.procs",
+ .seq_start = cgroup_pidlist_start,
+ .seq_next = cgroup_pidlist_next,
+ .seq_stop = cgroup_pidlist_stop,
+ .seq_show = cgroup_pidlist_show,
+ .private = CGROUP_FILE_PROCS,
+ .write = cgroup1_procs_write,
+ },
+ {
+ .name = "cgroup.clone_children",
+ .read_u64 = cgroup_clone_children_read,
+ .write_u64 = cgroup_clone_children_write,
+ },
+ {
+ .name = "cgroup.sane_behavior",
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ .seq_show = cgroup_sane_behavior_show,
+ },
+ {
+ .name = "tasks",
+ .seq_start = cgroup_pidlist_start,
+ .seq_next = cgroup_pidlist_next,
+ .seq_stop = cgroup_pidlist_stop,
+ .seq_show = cgroup_pidlist_show,
+ .private = CGROUP_FILE_TASKS,
+ .write = cgroup1_tasks_write,
+ },
+ {
+ .name = "notify_on_release",
+ .read_u64 = cgroup_read_notify_on_release,
+ .write_u64 = cgroup_write_notify_on_release,
+ },
+ {
+ .name = "release_agent",
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ .seq_show = cgroup_release_agent_show,
+ .write = cgroup_release_agent_write,
+ .max_write_len = PATH_MAX - 1,
+ },
+ { } /* terminate */
+};
+
+/* Display information about each subsystem and each hierarchy */
+int proc_cgroupstats_show(struct seq_file *m, void *v)
+{
+ struct cgroup_subsys *ss;
+ int i;
+
+ seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
+ /*
+ * Grab the subsystems state racily. No need to add avenue to
+ * cgroup_mutex contention.
+ */
+
+ for_each_subsys(ss, i)
+ seq_printf(m, "%s\t%d\t%d\t%d\n",
+ ss->legacy_name, ss->root->hierarchy_id,
+ atomic_read(&ss->root->nr_cgrps),
+ cgroup_ssid_enabled(i));
+
+ return 0;
+}
+
+/**
+ * cgroupstats_build - build and fill cgroupstats
+ * @stats: cgroupstats to fill information into
+ * @dentry: A dentry entry belonging to the cgroup for which stats have
+ * been requested.
+ *
+ * Build and fill cgroupstats so that taskstats can export it to user
+ * space.
+ *
+ * Return: %0 on success or a negative errno code on failure
+ */
+int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
+{
+ struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
+ struct cgroup *cgrp;
+ struct css_task_iter it;
+ struct task_struct *tsk;
+
+ /* it should be kernfs_node belonging to cgroupfs and is a directory */
+ if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
+ kernfs_type(kn) != KERNFS_DIR)
+ return -EINVAL;
+
+ /*
+ * We aren't being called from kernfs and there's no guarantee on
+ * @kn->priv's validity. For this and css_tryget_online_from_dir(),
+ * @kn->priv is RCU safe. Let's do the RCU dancing.
+ */
+ rcu_read_lock();
+ cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
+ if (!cgrp || !cgroup_tryget(cgrp)) {
+ rcu_read_unlock();
+ return -ENOENT;
+ }
+ rcu_read_unlock();
+
+ css_task_iter_start(&cgrp->self, 0, &it);
+ while ((tsk = css_task_iter_next(&it))) {
+ switch (READ_ONCE(tsk->__state)) {
+ case TASK_RUNNING:
+ stats->nr_running++;
+ break;
+ case TASK_INTERRUPTIBLE:
+ stats->nr_sleeping++;
+ break;
+ case TASK_UNINTERRUPTIBLE:
+ stats->nr_uninterruptible++;
+ break;
+ case TASK_STOPPED:
+ stats->nr_stopped++;
+ break;
+ default:
+ if (tsk->in_iowait)
+ stats->nr_io_wait++;
+ break;
+ }
+ }
+ css_task_iter_end(&it);
+
+ cgroup_put(cgrp);
+ return 0;
+}
+
+void cgroup1_check_for_release(struct cgroup *cgrp)
+{
+ if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
+ !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
+ schedule_work(&cgrp->release_agent_work);
+}
+
+/*
+ * Notify userspace when a cgroup is released, by running the
+ * configured release agent with the name of the cgroup (path
+ * relative to the root of cgroup file system) as the argument.
+ *
+ * Most likely, this user command will try to rmdir this cgroup.
+ *
+ * This races with the possibility that some other task will be
+ * attached to this cgroup before it is removed, or that some other
+ * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
+ * The presumed 'rmdir' will fail quietly if this cgroup is no longer
+ * unused, and this cgroup will be reprieved from its death sentence,
+ * to continue to serve a useful existence. Next time it's released,
+ * we will get notified again, if it still has 'notify_on_release' set.
+ *
+ * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
+ * means only wait until the task is successfully execve()'d. The
+ * separate release agent task is forked by call_usermodehelper(),
+ * then control in this thread returns here, without waiting for the
+ * release agent task. We don't bother to wait because the caller of
+ * this routine has no use for the exit status of the release agent
+ * task, so no sense holding our caller up for that.
+ */
+void cgroup1_release_agent(struct work_struct *work)
+{
+ struct cgroup *cgrp =
+ container_of(work, struct cgroup, release_agent_work);
+ char *pathbuf, *agentbuf;
+ char *argv[3], *envp[3];
+ int ret;
+
+ /* snoop agent path and exit early if empty */
+ if (!cgrp->root->release_agent_path[0])
+ return;
+
+ /* prepare argument buffers */
+ pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
+ agentbuf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!pathbuf || !agentbuf)
+ goto out_free;
+
+ spin_lock(&release_agent_path_lock);
+ strscpy(agentbuf, cgrp->root->release_agent_path, PATH_MAX);
+ spin_unlock(&release_agent_path_lock);
+ if (!agentbuf[0])
+ goto out_free;
+
+ ret = cgroup_path_ns(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
+ if (ret < 0 || ret >= PATH_MAX)
+ goto out_free;
+
+ argv[0] = agentbuf;
+ argv[1] = pathbuf;
+ argv[2] = NULL;
+
+ /* minimal command environment */
+ envp[0] = "HOME=/";
+ envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+ envp[2] = NULL;
+
+ call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
+out_free:
+ kfree(agentbuf);
+ kfree(pathbuf);
+}
+
+/*
+ * cgroup_rename - Only allow simple rename of directories in place.
+ */
+static int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+ const char *new_name_str)
+{
+ struct cgroup *cgrp = kn->priv;
+ int ret;
+
+ /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */
+ if (strchr(new_name_str, '\n'))
+ return -EINVAL;
+
+ if (kernfs_type(kn) != KERNFS_DIR)
+ return -ENOTDIR;
+ if (kn->parent != new_parent)
+ return -EIO;
+
+ /*
+ * We're gonna grab cgroup_mutex which nests outside kernfs
+ * active_ref. kernfs_rename() doesn't require active_ref
+ * protection. Break them before grabbing cgroup_mutex.
+ */
+ kernfs_break_active_protection(new_parent);
+ kernfs_break_active_protection(kn);
+
+ cgroup_lock();
+
+ ret = kernfs_rename(kn, new_parent, new_name_str);
+ if (!ret)
+ TRACE_CGROUP_PATH(rename, cgrp);
+
+ cgroup_unlock();
+
+ kernfs_unbreak_active_protection(kn);
+ kernfs_unbreak_active_protection(new_parent);
+ return ret;
+}
+
+static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
+{
+ struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ for_each_subsys(ss, ssid)
+ if (root->subsys_mask & (1 << ssid))
+ seq_show_option(seq, ss->legacy_name, NULL);
+ if (root->flags & CGRP_ROOT_NOPREFIX)
+ seq_puts(seq, ",noprefix");
+ if (root->flags & CGRP_ROOT_XATTR)
+ seq_puts(seq, ",xattr");
+ if (root->flags & CGRP_ROOT_CPUSET_V2_MODE)
+ seq_puts(seq, ",cpuset_v2_mode");
+ if (root->flags & CGRP_ROOT_FAVOR_DYNMODS)
+ seq_puts(seq, ",favordynmods");
+
+ spin_lock(&release_agent_path_lock);
+ if (strlen(root->release_agent_path))
+ seq_show_option(seq, "release_agent",
+ root->release_agent_path);
+ spin_unlock(&release_agent_path_lock);
+
+ if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
+ seq_puts(seq, ",clone_children");
+ if (strlen(root->name))
+ seq_show_option(seq, "name", root->name);
+ return 0;
+}
+
+enum cgroup1_param {
+ Opt_all,
+ Opt_clone_children,
+ Opt_cpuset_v2_mode,
+ Opt_name,
+ Opt_none,
+ Opt_noprefix,
+ Opt_release_agent,
+ Opt_xattr,
+ Opt_favordynmods,
+ Opt_nofavordynmods,
+};
+
+const struct fs_parameter_spec cgroup1_fs_parameters[] = {
+ fsparam_flag ("all", Opt_all),
+ fsparam_flag ("clone_children", Opt_clone_children),
+ fsparam_flag ("cpuset_v2_mode", Opt_cpuset_v2_mode),
+ fsparam_string("name", Opt_name),
+ fsparam_flag ("none", Opt_none),
+ fsparam_flag ("noprefix", Opt_noprefix),
+ fsparam_string("release_agent", Opt_release_agent),
+ fsparam_flag ("xattr", Opt_xattr),
+ fsparam_flag ("favordynmods", Opt_favordynmods),
+ fsparam_flag ("nofavordynmods", Opt_nofavordynmods),
+ {}
+};
+
+int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+ struct cgroup_subsys *ss;
+ struct fs_parse_result result;
+ int opt, i;
+
+ opt = fs_parse(fc, cgroup1_fs_parameters, param, &result);
+ if (opt == -ENOPARAM) {
+ int ret;
+
+ ret = vfs_parse_fs_param_source(fc, param);
+ if (ret != -ENOPARAM)
+ return ret;
+ for_each_subsys(ss, i) {
+ if (strcmp(param->key, ss->legacy_name))
+ continue;
+ if (!cgroup_ssid_enabled(i) || cgroup1_ssid_disabled(i))
+ return invalfc(fc, "Disabled controller '%s'",
+ param->key);
+ ctx->subsys_mask |= (1 << i);
+ return 0;
+ }
+ return invalfc(fc, "Unknown subsys name '%s'", param->key);
+ }
+ if (opt < 0)
+ return opt;
+
+ switch (opt) {
+ case Opt_none:
+ /* Explicitly have no subsystems */
+ ctx->none = true;
+ break;
+ case Opt_all:
+ ctx->all_ss = true;
+ break;
+ case Opt_noprefix:
+ ctx->flags |= CGRP_ROOT_NOPREFIX;
+ break;
+ case Opt_clone_children:
+ ctx->cpuset_clone_children = true;
+ break;
+ case Opt_cpuset_v2_mode:
+ ctx->flags |= CGRP_ROOT_CPUSET_V2_MODE;
+ break;
+ case Opt_xattr:
+ ctx->flags |= CGRP_ROOT_XATTR;
+ break;
+ case Opt_favordynmods:
+ ctx->flags |= CGRP_ROOT_FAVOR_DYNMODS;
+ break;
+ case Opt_nofavordynmods:
+ ctx->flags &= ~CGRP_ROOT_FAVOR_DYNMODS;
+ break;
+ case Opt_release_agent:
+ /* Specifying two release agents is forbidden */
+ if (ctx->release_agent)
+ return invalfc(fc, "release_agent respecified");
+ /*
+ * Release agent gets called with all capabilities,
+ * require capabilities to set release agent.
+ */
+ if ((fc->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN))
+ return invalfc(fc, "Setting release_agent not allowed");
+ ctx->release_agent = param->string;
+ param->string = NULL;
+ break;
+ case Opt_name:
+ /* blocked by boot param? */
+ if (cgroup_no_v1_named)
+ return -ENOENT;
+ /* Can't specify an empty name */
+ if (!param->size)
+ return invalfc(fc, "Empty name");
+ if (param->size > MAX_CGROUP_ROOT_NAMELEN - 1)
+ return invalfc(fc, "Name too long");
+ /* Must match [\w.-]+ */
+ for (i = 0; i < param->size; i++) {
+ char c = param->string[i];
+ if (isalnum(c))
+ continue;
+ if ((c == '.') || (c == '-') || (c == '_'))
+ continue;
+ return invalfc(fc, "Invalid name");
+ }
+ /* Specifying two names is forbidden */
+ if (ctx->name)
+ return invalfc(fc, "name respecified");
+ ctx->name = param->string;
+ param->string = NULL;
+ break;
+ }
+ return 0;
+}
+
+static int check_cgroupfs_options(struct fs_context *fc)
+{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+ u16 mask = U16_MAX;
+ u16 enabled = 0;
+ struct cgroup_subsys *ss;
+ int i;
+
+#ifdef CONFIG_CPUSETS
+ mask = ~((u16)1 << cpuset_cgrp_id);
+#endif
+ for_each_subsys(ss, i)
+ if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i))
+ enabled |= 1 << i;
+
+ ctx->subsys_mask &= enabled;
+
+ /*
+ * In absence of 'none', 'name=' and subsystem name options,
+ * let's default to 'all'.
+ */
+ if (!ctx->subsys_mask && !ctx->none && !ctx->name)
+ ctx->all_ss = true;
+
+ if (ctx->all_ss) {
+ /* Mutually exclusive option 'all' + subsystem name */
+ if (ctx->subsys_mask)
+ return invalfc(fc, "subsys name conflicts with all");
+ /* 'all' => select all the subsystems */
+ ctx->subsys_mask = enabled;
+ }
+
+ /*
+ * We either have to specify by name or by subsystems. (So all
+ * empty hierarchies must have a name).
+ */
+ if (!ctx->subsys_mask && !ctx->name)
+ return invalfc(fc, "Need name or subsystem set");
+
+ /*
+ * Option noprefix was introduced just for backward compatibility
+ * with the old cpuset, so we allow noprefix only if mounting just
+ * the cpuset subsystem.
+ */
+ if ((ctx->flags & CGRP_ROOT_NOPREFIX) && (ctx->subsys_mask & mask))
+ return invalfc(fc, "noprefix used incorrectly");
+
+ /* Can't specify "none" and some subsystems */
+ if (ctx->subsys_mask && ctx->none)
+ return invalfc(fc, "none used incorrectly");
+
+ return 0;
+}
+
+int cgroup1_reconfigure(struct fs_context *fc)
+{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+ struct kernfs_root *kf_root = kernfs_root_from_sb(fc->root->d_sb);
+ struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+ int ret = 0;
+ u16 added_mask, removed_mask;
+
+ cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
+
+ /* See what subsystems are wanted */
+ ret = check_cgroupfs_options(fc);
+ if (ret)
+ goto out_unlock;
+
+ if (ctx->subsys_mask != root->subsys_mask || ctx->release_agent)
+ pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
+ task_tgid_nr(current), current->comm);
+
+ added_mask = ctx->subsys_mask & ~root->subsys_mask;
+ removed_mask = root->subsys_mask & ~ctx->subsys_mask;
+
+ /* Don't allow flags or name to change at remount */
+ if ((ctx->flags ^ root->flags) ||
+ (ctx->name && strcmp(ctx->name, root->name))) {
+ errorfc(fc, "option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"",
+ ctx->flags, ctx->name ?: "", root->flags, root->name);
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ /* remounting is not allowed for populated hierarchies */
+ if (!list_empty(&root->cgrp.self.children)) {
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
+ ret = rebind_subsystems(root, added_mask);
+ if (ret)
+ goto out_unlock;
+
+ WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
+
+ if (ctx->release_agent) {
+ spin_lock(&release_agent_path_lock);
+ strcpy(root->release_agent_path, ctx->release_agent);
+ spin_unlock(&release_agent_path_lock);
+ }
+
+ trace_cgroup_remount(root);
+
+ out_unlock:
+ cgroup_unlock();
+ return ret;
+}
+
+struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
+ .rename = cgroup1_rename,
+ .show_options = cgroup1_show_options,
+ .mkdir = cgroup_mkdir,
+ .rmdir = cgroup_rmdir,
+ .show_path = cgroup_show_path,
+};
+
+/*
+ * The guts of cgroup1 mount - find or create cgroup_root to use.
+ * Called with cgroup_mutex held; returns 0 on success, -E... on
+ * error and positive - in case when the candidate is busy dying.
+ * On success it stashes a reference to cgroup_root into given
+ * cgroup_fs_context; that reference is *NOT* counting towards the
+ * cgroup_root refcount.
+ */
+static int cgroup1_root_to_use(struct fs_context *fc)
+{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+ struct cgroup_root *root;
+ struct cgroup_subsys *ss;
+ int i, ret;
+
+ /* First find the desired set of subsystems */
+ ret = check_cgroupfs_options(fc);
+ if (ret)
+ return ret;
+
+ /*
+ * Destruction of cgroup root is asynchronous, so subsystems may
+ * still be dying after the previous unmount. Let's drain the
+ * dying subsystems. We just need to ensure that the ones
+ * unmounted previously finish dying and don't care about new ones
+ * starting. Testing ref liveliness is good enough.
+ */
+ for_each_subsys(ss, i) {
+ if (!(ctx->subsys_mask & (1 << i)) ||
+ ss->root == &cgrp_dfl_root)
+ continue;
+
+ if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt))
+ return 1; /* restart */
+ cgroup_put(&ss->root->cgrp);
+ }
+
+ for_each_root(root) {
+ bool name_match = false;
+
+ if (root == &cgrp_dfl_root)
+ continue;
+
+ /*
+ * If we asked for a name then it must match. Also, if
+ * name matches but sybsys_mask doesn't, we should fail.
+ * Remember whether name matched.
+ */
+ if (ctx->name) {
+ if (strcmp(ctx->name, root->name))
+ continue;
+ name_match = true;
+ }
+
+ /*
+ * If we asked for subsystems (or explicitly for no
+ * subsystems) then they must match.
+ */
+ if ((ctx->subsys_mask || ctx->none) &&
+ (ctx->subsys_mask != root->subsys_mask)) {
+ if (!name_match)
+ continue;
+ return -EBUSY;
+ }
+
+ if (root->flags ^ ctx->flags)
+ pr_warn("new mount options do not match the existing superblock, will be ignored\n");
+
+ ctx->root = root;
+ return 0;
+ }
+
+ /*
+ * No such thing, create a new one. name= matching without subsys
+ * specification is allowed for already existing hierarchies but we
+ * can't create new one without subsys specification.
+ */
+ if (!ctx->subsys_mask && !ctx->none)
+ return invalfc(fc, "No subsys list or none specified");
+
+ /* Hierarchies may only be created in the initial cgroup namespace. */
+ if (ctx->ns != &init_cgroup_ns)
+ return -EPERM;
+
+ root = kzalloc(sizeof(*root), GFP_KERNEL);
+ if (!root)
+ return -ENOMEM;
+
+ ctx->root = root;
+ init_cgroup_root(ctx);
+
+ ret = cgroup_setup_root(root, ctx->subsys_mask);
+ if (!ret)
+ cgroup_favor_dynmods(root, ctx->flags & CGRP_ROOT_FAVOR_DYNMODS);
+ else
+ cgroup_free_root(root);
+
+ return ret;
+}
+
+int cgroup1_get_tree(struct fs_context *fc)
+{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+ int ret;
+
+ /* Check if the caller has permission to mount. */
+ if (!ns_capable(ctx->ns->user_ns, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
+
+ ret = cgroup1_root_to_use(fc);
+ if (!ret && !percpu_ref_tryget_live(&ctx->root->cgrp.self.refcnt))
+ ret = 1; /* restart */
+
+ cgroup_unlock();
+
+ if (!ret)
+ ret = cgroup_do_get_tree(fc);
+
+ if (!ret && percpu_ref_is_dying(&ctx->root->cgrp.self.refcnt)) {
+ fc_drop_locked(fc);
+ ret = 1;
+ }
+
+ if (unlikely(ret > 0)) {
+ msleep(10);
+ return restart_syscall();
+ }
+ return ret;
+}
+
+static int __init cgroup1_wq_init(void)
+{
+ /*
+ * Used to destroy pidlists and separate to serve as flush domain.
+ * Cap @max_active to 1 too.
+ */
+ cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
+ 0, 1);
+ BUG_ON(!cgroup_pidlist_destroy_wq);
+ return 0;
+}
+core_initcall(cgroup1_wq_init);
+
+static int __init cgroup_no_v1(char *str)
+{
+ struct cgroup_subsys *ss;
+ char *token;
+ int i;
+
+ while ((token = strsep(&str, ",")) != NULL) {
+ if (!*token)
+ continue;
+
+ if (!strcmp(token, "all")) {
+ cgroup_no_v1_mask = U16_MAX;
+ continue;
+ }
+
+ if (!strcmp(token, "named")) {
+ cgroup_no_v1_named = true;
+ continue;
+ }
+
+ for_each_subsys(ss, i) {
+ if (strcmp(token, ss->name) &&
+ strcmp(token, ss->legacy_name))
+ continue;
+
+ cgroup_no_v1_mask |= 1 << i;
+ }
+ }
+ return 1;
+}
+__setup("cgroup_no_v1=", cgroup_no_v1);
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
new file mode 100644
index 0000000000..518725b572
--- /dev/null
+++ b/kernel/cgroup/cgroup.c
@@ -0,0 +1,7062 @@
+/*
+ * Generic process-grouping system.
+ *
+ * Based originally on the cpuset system, extracted by Paul Menage
+ * Copyright (C) 2006 Google, Inc
+ *
+ * Notifications support
+ * Copyright (C) 2009 Nokia Corporation
+ * Author: Kirill A. Shutemov
+ *
+ * Copyright notices from the original cpuset code:
+ * --------------------------------------------------
+ * Copyright (C) 2003 BULL SA.
+ * Copyright (C) 2004-2006 Silicon Graphics, Inc.
+ *
+ * Portions derived from Patrick Mochel's sysfs code.
+ * sysfs is Copyright (c) 2001-3 Patrick Mochel
+ *
+ * 2003-10-10 Written by Simon Derr.
+ * 2003-10-22 Updates by Stephen Hemminger.
+ * 2004 May-July Rework by Paul Jackson.
+ * ---------------------------------------------------
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include "cgroup-internal.h"
+
+#include <linux/bpf-cgroup.h>
+#include <linux/cred.h>
+#include <linux/errno.h>
+#include <linux/init_task.h>
+#include <linux/kernel.h>
+#include <linux/magic.h>
+#include <linux/mutex.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+#include <linux/proc_fs.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+#include <linux/sched/task.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/percpu-rwsem.h>
+#include <linux/string.h>
+#include <linux/hashtable.h>
+#include <linux/idr.h>
+#include <linux/kthread.h>
+#include <linux/atomic.h>
+#include <linux/cpuset.h>
+#include <linux/proc_ns.h>
+#include <linux/nsproxy.h>
+#include <linux/file.h>
+#include <linux/fs_parser.h>
+#include <linux/sched/cputime.h>
+#include <linux/sched/deadline.h>
+#include <linux/psi.h>
+#include <net/sock.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/cgroup.h>
+
+#define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
+ MAX_CFTYPE_NAME + 2)
+/* let's not notify more than 100 times per second */
+#define CGROUP_FILE_NOTIFY_MIN_INTV DIV_ROUND_UP(HZ, 100)
+
+/*
+ * To avoid confusing the compiler (and generating warnings) with code
+ * that attempts to access what would be a 0-element array (i.e. sized
+ * to a potentially empty array when CGROUP_SUBSYS_COUNT == 0), this
+ * constant expression can be added.
+ */
+#define CGROUP_HAS_SUBSYS_CONFIG (CGROUP_SUBSYS_COUNT > 0)
+
+/*
+ * cgroup_mutex is the master lock. Any modification to cgroup or its
+ * hierarchy must be performed while holding it.
+ *
+ * css_set_lock protects task->cgroups pointer, the list of css_set
+ * objects, and the chain of tasks off each css_set.
+ *
+ * These locks are exported if CONFIG_PROVE_RCU so that accessors in
+ * cgroup.h can use them for lockdep annotations.
+ */
+DEFINE_MUTEX(cgroup_mutex);
+DEFINE_SPINLOCK(css_set_lock);
+
+#ifdef CONFIG_PROVE_RCU
+EXPORT_SYMBOL_GPL(cgroup_mutex);
+EXPORT_SYMBOL_GPL(css_set_lock);
+#endif
+
+DEFINE_SPINLOCK(trace_cgroup_path_lock);
+char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
+static bool cgroup_debug __read_mostly;
+
+/*
+ * Protects cgroup_idr and css_idr so that IDs can be released without
+ * grabbing cgroup_mutex.
+ */
+static DEFINE_SPINLOCK(cgroup_idr_lock);
+
+/*
+ * Protects cgroup_file->kn for !self csses. It synchronizes notifications
+ * against file removal/re-creation across css hiding.
+ */
+static DEFINE_SPINLOCK(cgroup_file_kn_lock);
+
+DEFINE_PERCPU_RWSEM(cgroup_threadgroup_rwsem);
+
+#define cgroup_assert_mutex_or_rcu_locked() \
+ RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
+ !lockdep_is_held(&cgroup_mutex), \
+ "cgroup_mutex or RCU read lock required");
+
+/*
+ * cgroup destruction makes heavy use of work items and there can be a lot
+ * of concurrent destructions. Use a separate workqueue so that cgroup
+ * destruction work items don't end up filling up max_active of system_wq
+ * which may lead to deadlock.
+ */
+static struct workqueue_struct *cgroup_destroy_wq;
+
+/* generate an array of cgroup subsystem pointers */
+#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
+struct cgroup_subsys *cgroup_subsys[] = {
+#include <linux/cgroup_subsys.h>
+};
+#undef SUBSYS
+
+/* array of cgroup subsystem names */
+#define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
+static const char *cgroup_subsys_name[] = {
+#include <linux/cgroup_subsys.h>
+};
+#undef SUBSYS
+
+/* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */
+#define SUBSYS(_x) \
+ DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \
+ DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \
+ EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \
+ EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key);
+#include <linux/cgroup_subsys.h>
+#undef SUBSYS
+
+#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key,
+static struct static_key_true *cgroup_subsys_enabled_key[] = {
+#include <linux/cgroup_subsys.h>
+};
+#undef SUBSYS
+
+#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key,
+static struct static_key_true *cgroup_subsys_on_dfl_key[] = {
+#include <linux/cgroup_subsys.h>
+};
+#undef SUBSYS
+
+static DEFINE_PER_CPU(struct cgroup_rstat_cpu, cgrp_dfl_root_rstat_cpu);
+
+/* the default hierarchy */
+struct cgroup_root cgrp_dfl_root = { .cgrp.rstat_cpu = &cgrp_dfl_root_rstat_cpu };
+EXPORT_SYMBOL_GPL(cgrp_dfl_root);
+
+/*
+ * The default hierarchy always exists but is hidden until mounted for the
+ * first time. This is for backward compatibility.
+ */
+static bool cgrp_dfl_visible;
+
+/* some controllers are not supported in the default hierarchy */
+static u16 cgrp_dfl_inhibit_ss_mask;
+
+/* some controllers are implicitly enabled on the default hierarchy */
+static u16 cgrp_dfl_implicit_ss_mask;
+
+/* some controllers can be threaded on the default hierarchy */
+static u16 cgrp_dfl_threaded_ss_mask;
+
+/* The list of hierarchy roots */
+LIST_HEAD(cgroup_roots);
+static int cgroup_root_count;
+
+/* hierarchy ID allocation and mapping, protected by cgroup_mutex */
+static DEFINE_IDR(cgroup_hierarchy_idr);
+
+/*
+ * Assign a monotonically increasing serial number to csses. It guarantees
+ * cgroups with bigger numbers are newer than those with smaller numbers.
+ * Also, as csses are always appended to the parent's ->children list, it
+ * guarantees that sibling csses are always sorted in the ascending serial
+ * number order on the list. Protected by cgroup_mutex.
+ */
+static u64 css_serial_nr_next = 1;
+
+/*
+ * These bitmasks identify subsystems with specific features to avoid
+ * having to do iterative checks repeatedly.
+ */
+static u16 have_fork_callback __read_mostly;
+static u16 have_exit_callback __read_mostly;
+static u16 have_release_callback __read_mostly;
+static u16 have_canfork_callback __read_mostly;
+
+/* cgroup namespace for init task */
+struct cgroup_namespace init_cgroup_ns = {
+ .ns.count = REFCOUNT_INIT(2),
+ .user_ns = &init_user_ns,
+ .ns.ops = &cgroupns_operations,
+ .ns.inum = PROC_CGROUP_INIT_INO,
+ .root_cset = &init_css_set,
+};
+
+static struct file_system_type cgroup2_fs_type;
+static struct cftype cgroup_base_files[];
+static struct cftype cgroup_psi_files[];
+
+/* cgroup optional features */
+enum cgroup_opt_features {
+#ifdef CONFIG_PSI
+ OPT_FEATURE_PRESSURE,
+#endif
+ OPT_FEATURE_COUNT
+};
+
+static const char *cgroup_opt_feature_names[OPT_FEATURE_COUNT] = {
+#ifdef CONFIG_PSI
+ "pressure",
+#endif
+};
+
+static u16 cgroup_feature_disable_mask __read_mostly;
+
+static int cgroup_apply_control(struct cgroup *cgrp);
+static void cgroup_finalize_control(struct cgroup *cgrp, int ret);
+static void css_task_iter_skip(struct css_task_iter *it,
+ struct task_struct *task);
+static int cgroup_destroy_locked(struct cgroup *cgrp);
+static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
+ struct cgroup_subsys *ss);
+static void css_release(struct percpu_ref *ref);
+static void kill_css(struct cgroup_subsys_state *css);
+static int cgroup_addrm_files(struct cgroup_subsys_state *css,
+ struct cgroup *cgrp, struct cftype cfts[],
+ bool is_add);
+
+#ifdef CONFIG_DEBUG_CGROUP_REF
+#define CGROUP_REF_FN_ATTRS noinline
+#define CGROUP_REF_EXPORT(fn) EXPORT_SYMBOL_GPL(fn);
+#include <linux/cgroup_refcnt.h>
+#endif
+
+/**
+ * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID
+ * @ssid: subsys ID of interest
+ *
+ * cgroup_subsys_enabled() can only be used with literal subsys names which
+ * is fine for individual subsystems but unsuitable for cgroup core. This
+ * is slower static_key_enabled() based test indexed by @ssid.
+ */
+bool cgroup_ssid_enabled(int ssid)
+{
+ if (!CGROUP_HAS_SUBSYS_CONFIG)
+ return false;
+
+ return static_key_enabled(cgroup_subsys_enabled_key[ssid]);
+}
+
+/**
+ * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
+ * @cgrp: the cgroup of interest
+ *
+ * The default hierarchy is the v2 interface of cgroup and this function
+ * can be used to test whether a cgroup is on the default hierarchy for
+ * cases where a subsystem should behave differently depending on the
+ * interface version.
+ *
+ * List of changed behaviors:
+ *
+ * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
+ * and "name" are disallowed.
+ *
+ * - When mounting an existing superblock, mount options should match.
+ *
+ * - rename(2) is disallowed.
+ *
+ * - "tasks" is removed. Everything should be at process granularity. Use
+ * "cgroup.procs" instead.
+ *
+ * - "cgroup.procs" is not sorted. pids will be unique unless they got
+ * recycled in-between reads.
+ *
+ * - "release_agent" and "notify_on_release" are removed. Replacement
+ * notification mechanism will be implemented.
+ *
+ * - "cgroup.clone_children" is removed.
+ *
+ * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
+ * and its descendants contain no task; otherwise, 1. The file also
+ * generates kernfs notification which can be monitored through poll and
+ * [di]notify when the value of the file changes.
+ *
+ * - cpuset: tasks will be kept in empty cpusets when hotplug happens and
+ * take masks of ancestors with non-empty cpus/mems, instead of being
+ * moved to an ancestor.
+ *
+ * - cpuset: a task can be moved into an empty cpuset, and again it takes
+ * masks of ancestors.
+ *
+ * - blkcg: blk-throttle becomes properly hierarchical.
+ */
+bool cgroup_on_dfl(const struct cgroup *cgrp)
+{
+ return cgrp->root == &cgrp_dfl_root;
+}
+
+/* IDR wrappers which synchronize using cgroup_idr_lock */
+static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end,
+ gfp_t gfp_mask)
+{
+ int ret;
+
+ idr_preload(gfp_mask);
+ spin_lock_bh(&cgroup_idr_lock);
+ ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM);
+ spin_unlock_bh(&cgroup_idr_lock);
+ idr_preload_end();
+ return ret;
+}
+
+static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id)
+{
+ void *ret;
+
+ spin_lock_bh(&cgroup_idr_lock);
+ ret = idr_replace(idr, ptr, id);
+ spin_unlock_bh(&cgroup_idr_lock);
+ return ret;
+}
+
+static void cgroup_idr_remove(struct idr *idr, int id)
+{
+ spin_lock_bh(&cgroup_idr_lock);
+ idr_remove(idr, id);
+ spin_unlock_bh(&cgroup_idr_lock);
+}
+
+static bool cgroup_has_tasks(struct cgroup *cgrp)
+{
+ return cgrp->nr_populated_csets;
+}
+
+static bool cgroup_is_threaded(struct cgroup *cgrp)
+{
+ return cgrp->dom_cgrp != cgrp;
+}
+
+/* can @cgrp host both domain and threaded children? */
+static bool cgroup_is_mixable(struct cgroup *cgrp)
+{
+ /*
+ * Root isn't under domain level resource control exempting it from
+ * the no-internal-process constraint, so it can serve as a thread
+ * root and a parent of resource domains at the same time.
+ */
+ return !cgroup_parent(cgrp);
+}
+
+/* can @cgrp become a thread root? Should always be true for a thread root */
+static bool cgroup_can_be_thread_root(struct cgroup *cgrp)
+{
+ /* mixables don't care */
+ if (cgroup_is_mixable(cgrp))
+ return true;
+
+ /* domain roots can't be nested under threaded */
+ if (cgroup_is_threaded(cgrp))
+ return false;
+
+ /* can only have either domain or threaded children */
+ if (cgrp->nr_populated_domain_children)
+ return false;
+
+ /* and no domain controllers can be enabled */
+ if (cgrp->subtree_control & ~cgrp_dfl_threaded_ss_mask)
+ return false;
+
+ return true;
+}
+
+/* is @cgrp root of a threaded subtree? */
+static bool cgroup_is_thread_root(struct cgroup *cgrp)
+{
+ /* thread root should be a domain */
+ if (cgroup_is_threaded(cgrp))
+ return false;
+
+ /* a domain w/ threaded children is a thread root */
+ if (cgrp->nr_threaded_children)
+ return true;
+
+ /*
+ * A domain which has tasks and explicit threaded controllers
+ * enabled is a thread root.
+ */
+ if (cgroup_has_tasks(cgrp) &&
+ (cgrp->subtree_control & cgrp_dfl_threaded_ss_mask))
+ return true;
+
+ return false;
+}
+
+/* a domain which isn't connected to the root w/o brekage can't be used */
+static bool cgroup_is_valid_domain(struct cgroup *cgrp)
+{
+ /* the cgroup itself can be a thread root */
+ if (cgroup_is_threaded(cgrp))
+ return false;
+
+ /* but the ancestors can't be unless mixable */
+ while ((cgrp = cgroup_parent(cgrp))) {
+ if (!cgroup_is_mixable(cgrp) && cgroup_is_thread_root(cgrp))
+ return false;
+ if (cgroup_is_threaded(cgrp))
+ return false;
+ }
+
+ return true;
+}
+
+/* subsystems visibly enabled on a cgroup */
+static u16 cgroup_control(struct cgroup *cgrp)
+{
+ struct cgroup *parent = cgroup_parent(cgrp);
+ u16 root_ss_mask = cgrp->root->subsys_mask;
+
+ if (parent) {
+ u16 ss_mask = parent->subtree_control;
+
+ /* threaded cgroups can only have threaded controllers */
+ if (cgroup_is_threaded(cgrp))
+ ss_mask &= cgrp_dfl_threaded_ss_mask;
+ return ss_mask;
+ }
+
+ if (cgroup_on_dfl(cgrp))
+ root_ss_mask &= ~(cgrp_dfl_inhibit_ss_mask |
+ cgrp_dfl_implicit_ss_mask);
+ return root_ss_mask;
+}
+
+/* subsystems enabled on a cgroup */
+static u16 cgroup_ss_mask(struct cgroup *cgrp)
+{
+ struct cgroup *parent = cgroup_parent(cgrp);
+
+ if (parent) {
+ u16 ss_mask = parent->subtree_ss_mask;
+
+ /* threaded cgroups can only have threaded controllers */
+ if (cgroup_is_threaded(cgrp))
+ ss_mask &= cgrp_dfl_threaded_ss_mask;
+ return ss_mask;
+ }
+
+ return cgrp->root->subsys_mask;
+}
+
+/**
+ * cgroup_css - obtain a cgroup's css for the specified subsystem
+ * @cgrp: the cgroup of interest
+ * @ss: the subsystem of interest (%NULL returns @cgrp->self)
+ *
+ * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
+ * function must be called either under cgroup_mutex or rcu_read_lock() and
+ * the caller is responsible for pinning the returned css if it wants to
+ * keep accessing it outside the said locks. This function may return
+ * %NULL if @cgrp doesn't have @subsys_id enabled.
+ */
+static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
+{
+ if (CGROUP_HAS_SUBSYS_CONFIG && ss)
+ return rcu_dereference_check(cgrp->subsys[ss->id],
+ lockdep_is_held(&cgroup_mutex));
+ else
+ return &cgrp->self;
+}
+
+/**
+ * cgroup_e_css_by_mask - obtain a cgroup's effective css for the specified ss
+ * @cgrp: the cgroup of interest
+ * @ss: the subsystem of interest (%NULL returns @cgrp->self)
+ *
+ * Similar to cgroup_css() but returns the effective css, which is defined
+ * as the matching css of the nearest ancestor including self which has @ss
+ * enabled. If @ss is associated with the hierarchy @cgrp is on, this
+ * function is guaranteed to return non-NULL css.
+ */
+static struct cgroup_subsys_state *cgroup_e_css_by_mask(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
+{
+ lockdep_assert_held(&cgroup_mutex);
+
+ if (!ss)
+ return &cgrp->self;
+
+ /*
+ * This function is used while updating css associations and thus
+ * can't test the csses directly. Test ss_mask.
+ */
+ while (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) {
+ cgrp = cgroup_parent(cgrp);
+ if (!cgrp)
+ return NULL;
+ }
+
+ return cgroup_css(cgrp, ss);
+}
+
+/**
+ * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
+ * @cgrp: the cgroup of interest
+ * @ss: the subsystem of interest
+ *
+ * Find and get the effective css of @cgrp for @ss. The effective css is
+ * defined as the matching css of the nearest ancestor including self which
+ * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
+ * the root css is returned, so this function always returns a valid css.
+ *
+ * The returned css is not guaranteed to be online, and therefore it is the
+ * callers responsibility to try get a reference for it.
+ */
+struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
+{
+ struct cgroup_subsys_state *css;
+
+ if (!CGROUP_HAS_SUBSYS_CONFIG)
+ return NULL;
+
+ do {
+ css = cgroup_css(cgrp, ss);
+
+ if (css)
+ return css;
+ cgrp = cgroup_parent(cgrp);
+ } while (cgrp);
+
+ return init_css_set.subsys[ss->id];
+}
+
+/**
+ * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
+ * @cgrp: the cgroup of interest
+ * @ss: the subsystem of interest
+ *
+ * Find and get the effective css of @cgrp for @ss. The effective css is
+ * defined as the matching css of the nearest ancestor including self which
+ * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
+ * the root css is returned, so this function always returns a valid css.
+ * The returned css must be put using css_put().
+ */
+struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
+{
+ struct cgroup_subsys_state *css;
+
+ if (!CGROUP_HAS_SUBSYS_CONFIG)
+ return NULL;
+
+ rcu_read_lock();
+
+ do {
+ css = cgroup_css(cgrp, ss);
+
+ if (css && css_tryget_online(css))
+ goto out_unlock;
+ cgrp = cgroup_parent(cgrp);
+ } while (cgrp);
+
+ css = init_css_set.subsys[ss->id];
+ css_get(css);
+out_unlock:
+ rcu_read_unlock();
+ return css;
+}
+EXPORT_SYMBOL_GPL(cgroup_get_e_css);
+
+static void cgroup_get_live(struct cgroup *cgrp)
+{
+ WARN_ON_ONCE(cgroup_is_dead(cgrp));
+ cgroup_get(cgrp);
+}
+
+/**
+ * __cgroup_task_count - count the number of tasks in a cgroup. The caller
+ * is responsible for taking the css_set_lock.
+ * @cgrp: the cgroup in question
+ */
+int __cgroup_task_count(const struct cgroup *cgrp)
+{
+ int count = 0;
+ struct cgrp_cset_link *link;
+
+ lockdep_assert_held(&css_set_lock);
+
+ list_for_each_entry(link, &cgrp->cset_links, cset_link)
+ count += link->cset->nr_tasks;
+
+ return count;
+}
+
+/**
+ * cgroup_task_count - count the number of tasks in a cgroup.
+ * @cgrp: the cgroup in question
+ */
+int cgroup_task_count(const struct cgroup *cgrp)
+{
+ int count;
+
+ spin_lock_irq(&css_set_lock);
+ count = __cgroup_task_count(cgrp);
+ spin_unlock_irq(&css_set_lock);
+
+ return count;
+}
+
+struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
+{
+ struct cgroup *cgrp = of->kn->parent->priv;
+ struct cftype *cft = of_cft(of);
+
+ /*
+ * This is open and unprotected implementation of cgroup_css().
+ * seq_css() is only called from a kernfs file operation which has
+ * an active reference on the file. Because all the subsystem
+ * files are drained before a css is disassociated with a cgroup,
+ * the matching css from the cgroup's subsys table is guaranteed to
+ * be and stay valid until the enclosing operation is complete.
+ */
+ if (CGROUP_HAS_SUBSYS_CONFIG && cft->ss)
+ return rcu_dereference_raw(cgrp->subsys[cft->ss->id]);
+ else
+ return &cgrp->self;
+}
+EXPORT_SYMBOL_GPL(of_css);
+
+/**
+ * for_each_css - iterate all css's of a cgroup
+ * @css: the iteration cursor
+ * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
+ * @cgrp: the target cgroup to iterate css's of
+ *
+ * Should be called under cgroup_mutex.
+ */
+#define for_each_css(css, ssid, cgrp) \
+ for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
+ if (!((css) = rcu_dereference_check( \
+ (cgrp)->subsys[(ssid)], \
+ lockdep_is_held(&cgroup_mutex)))) { } \
+ else
+
+/**
+ * do_each_subsys_mask - filter for_each_subsys with a bitmask
+ * @ss: the iteration cursor
+ * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
+ * @ss_mask: the bitmask
+ *
+ * The block will only run for cases where the ssid-th bit (1 << ssid) of
+ * @ss_mask is set.
+ */
+#define do_each_subsys_mask(ss, ssid, ss_mask) do { \
+ unsigned long __ss_mask = (ss_mask); \
+ if (!CGROUP_HAS_SUBSYS_CONFIG) { \
+ (ssid) = 0; \
+ break; \
+ } \
+ for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \
+ (ss) = cgroup_subsys[ssid]; \
+ {
+
+#define while_each_subsys_mask() \
+ } \
+ } \
+} while (false)
+
+/* iterate over child cgrps, lock should be held throughout iteration */
+#define cgroup_for_each_live_child(child, cgrp) \
+ list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
+ if (({ lockdep_assert_held(&cgroup_mutex); \
+ cgroup_is_dead(child); })) \
+ ; \
+ else
+
+/* walk live descendants in pre order */
+#define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) \
+ css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL)) \
+ if (({ lockdep_assert_held(&cgroup_mutex); \
+ (dsct) = (d_css)->cgroup; \
+ cgroup_is_dead(dsct); })) \
+ ; \
+ else
+
+/* walk live descendants in postorder */
+#define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) \
+ css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL)) \
+ if (({ lockdep_assert_held(&cgroup_mutex); \
+ (dsct) = (d_css)->cgroup; \
+ cgroup_is_dead(dsct); })) \
+ ; \
+ else
+
+/*
+ * The default css_set - used by init and its children prior to any
+ * hierarchies being mounted. It contains a pointer to the root state
+ * for each subsystem. Also used to anchor the list of css_sets. Not
+ * reference-counted, to improve performance when child cgroups
+ * haven't been created.
+ */
+struct css_set init_css_set = {
+ .refcount = REFCOUNT_INIT(1),
+ .dom_cset = &init_css_set,
+ .tasks = LIST_HEAD_INIT(init_css_set.tasks),
+ .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks),
+ .dying_tasks = LIST_HEAD_INIT(init_css_set.dying_tasks),
+ .task_iters = LIST_HEAD_INIT(init_css_set.task_iters),
+ .threaded_csets = LIST_HEAD_INIT(init_css_set.threaded_csets),
+ .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links),
+ .mg_src_preload_node = LIST_HEAD_INIT(init_css_set.mg_src_preload_node),
+ .mg_dst_preload_node = LIST_HEAD_INIT(init_css_set.mg_dst_preload_node),
+ .mg_node = LIST_HEAD_INIT(init_css_set.mg_node),
+
+ /*
+ * The following field is re-initialized when this cset gets linked
+ * in cgroup_init(). However, let's initialize the field
+ * statically too so that the default cgroup can be accessed safely
+ * early during boot.
+ */
+ .dfl_cgrp = &cgrp_dfl_root.cgrp,
+};
+
+static int css_set_count = 1; /* 1 for init_css_set */
+
+static bool css_set_threaded(struct css_set *cset)
+{
+ return cset->dom_cset != cset;
+}
+
+/**
+ * css_set_populated - does a css_set contain any tasks?
+ * @cset: target css_set
+ *
+ * css_set_populated() should be the same as !!cset->nr_tasks at steady
+ * state. However, css_set_populated() can be called while a task is being
+ * added to or removed from the linked list before the nr_tasks is
+ * properly updated. Hence, we can't just look at ->nr_tasks here.
+ */
+static bool css_set_populated(struct css_set *cset)
+{
+ lockdep_assert_held(&css_set_lock);
+
+ return !list_empty(&cset->tasks) || !list_empty(&cset->mg_tasks);
+}
+
+/**
+ * cgroup_update_populated - update the populated count of a cgroup
+ * @cgrp: the target cgroup
+ * @populated: inc or dec populated count
+ *
+ * One of the css_sets associated with @cgrp is either getting its first
+ * task or losing the last. Update @cgrp->nr_populated_* accordingly. The
+ * count is propagated towards root so that a given cgroup's
+ * nr_populated_children is zero iff none of its descendants contain any
+ * tasks.
+ *
+ * @cgrp's interface file "cgroup.populated" is zero if both
+ * @cgrp->nr_populated_csets and @cgrp->nr_populated_children are zero and
+ * 1 otherwise. When the sum changes from or to zero, userland is notified
+ * that the content of the interface file has changed. This can be used to
+ * detect when @cgrp and its descendants become populated or empty.
+ */
+static void cgroup_update_populated(struct cgroup *cgrp, bool populated)
+{
+ struct cgroup *child = NULL;
+ int adj = populated ? 1 : -1;
+
+ lockdep_assert_held(&css_set_lock);
+
+ do {
+ bool was_populated = cgroup_is_populated(cgrp);
+
+ if (!child) {
+ cgrp->nr_populated_csets += adj;
+ } else {
+ if (cgroup_is_threaded(child))
+ cgrp->nr_populated_threaded_children += adj;
+ else
+ cgrp->nr_populated_domain_children += adj;
+ }
+
+ if (was_populated == cgroup_is_populated(cgrp))
+ break;
+
+ cgroup1_check_for_release(cgrp);
+ TRACE_CGROUP_PATH(notify_populated, cgrp,
+ cgroup_is_populated(cgrp));
+ cgroup_file_notify(&cgrp->events_file);
+
+ child = cgrp;
+ cgrp = cgroup_parent(cgrp);
+ } while (cgrp);
+}
+
+/**
+ * css_set_update_populated - update populated state of a css_set
+ * @cset: target css_set
+ * @populated: whether @cset is populated or depopulated
+ *
+ * @cset is either getting the first task or losing the last. Update the
+ * populated counters of all associated cgroups accordingly.
+ */
+static void css_set_update_populated(struct css_set *cset, bool populated)
+{
+ struct cgrp_cset_link *link;
+
+ lockdep_assert_held(&css_set_lock);
+
+ list_for_each_entry(link, &cset->cgrp_links, cgrp_link)
+ cgroup_update_populated(link->cgrp, populated);
+}
+
+/*
+ * @task is leaving, advance task iterators which are pointing to it so
+ * that they can resume at the next position. Advancing an iterator might
+ * remove it from the list, use safe walk. See css_task_iter_skip() for
+ * details.
+ */
+static void css_set_skip_task_iters(struct css_set *cset,
+ struct task_struct *task)
+{
+ struct css_task_iter *it, *pos;
+
+ list_for_each_entry_safe(it, pos, &cset->task_iters, iters_node)
+ css_task_iter_skip(it, task);
+}
+
+/**
+ * css_set_move_task - move a task from one css_set to another
+ * @task: task being moved
+ * @from_cset: css_set @task currently belongs to (may be NULL)
+ * @to_cset: new css_set @task is being moved to (may be NULL)
+ * @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks
+ *
+ * Move @task from @from_cset to @to_cset. If @task didn't belong to any
+ * css_set, @from_cset can be NULL. If @task is being disassociated
+ * instead of moved, @to_cset can be NULL.
+ *
+ * This function automatically handles populated counter updates and
+ * css_task_iter adjustments but the caller is responsible for managing
+ * @from_cset and @to_cset's reference counts.
+ */
+static void css_set_move_task(struct task_struct *task,
+ struct css_set *from_cset, struct css_set *to_cset,
+ bool use_mg_tasks)
+{
+ lockdep_assert_held(&css_set_lock);
+
+ if (to_cset && !css_set_populated(to_cset))
+ css_set_update_populated(to_cset, true);
+
+ if (from_cset) {
+ WARN_ON_ONCE(list_empty(&task->cg_list));
+
+ css_set_skip_task_iters(from_cset, task);
+ list_del_init(&task->cg_list);
+ if (!css_set_populated(from_cset))
+ css_set_update_populated(from_cset, false);
+ } else {
+ WARN_ON_ONCE(!list_empty(&task->cg_list));
+ }
+
+ if (to_cset) {
+ /*
+ * We are synchronized through cgroup_threadgroup_rwsem
+ * against PF_EXITING setting such that we can't race
+ * against cgroup_exit()/cgroup_free() dropping the css_set.
+ */
+ WARN_ON_ONCE(task->flags & PF_EXITING);
+
+ cgroup_move_task(task, to_cset);
+ list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks :
+ &to_cset->tasks);
+ }
+}
+
+/*
+ * hash table for cgroup groups. This improves the performance to find
+ * an existing css_set. This hash doesn't (currently) take into
+ * account cgroups in empty hierarchies.
+ */
+#define CSS_SET_HASH_BITS 7
+static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
+
+static unsigned long css_set_hash(struct cgroup_subsys_state **css)
+{
+ unsigned long key = 0UL;
+ struct cgroup_subsys *ss;
+ int i;
+
+ for_each_subsys(ss, i)
+ key += (unsigned long)css[i];
+ key = (key >> 16) ^ key;
+
+ return key;
+}
+
+void put_css_set_locked(struct css_set *cset)
+{
+ struct cgrp_cset_link *link, *tmp_link;
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ lockdep_assert_held(&css_set_lock);
+
+ if (!refcount_dec_and_test(&cset->refcount))
+ return;
+
+ WARN_ON_ONCE(!list_empty(&cset->threaded_csets));
+
+ /* This css_set is dead. Unlink it and release cgroup and css refs */
+ for_each_subsys(ss, ssid) {
+ list_del(&cset->e_cset_node[ssid]);
+ css_put(cset->subsys[ssid]);
+ }
+ hash_del(&cset->hlist);
+ css_set_count--;
+
+ list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) {
+ list_del(&link->cset_link);
+ list_del(&link->cgrp_link);
+ if (cgroup_parent(link->cgrp))
+ cgroup_put(link->cgrp);
+ kfree(link);
+ }
+
+ if (css_set_threaded(cset)) {
+ list_del(&cset->threaded_csets_node);
+ put_css_set_locked(cset->dom_cset);
+ }
+
+ kfree_rcu(cset, rcu_head);
+}
+
+/**
+ * compare_css_sets - helper function for find_existing_css_set().
+ * @cset: candidate css_set being tested
+ * @old_cset: existing css_set for a task
+ * @new_cgrp: cgroup that's being entered by the task
+ * @template: desired set of css pointers in css_set (pre-calculated)
+ *
+ * Returns true if "cset" matches "old_cset" except for the hierarchy
+ * which "new_cgrp" belongs to, for which it should match "new_cgrp".
+ */
+static bool compare_css_sets(struct css_set *cset,
+ struct css_set *old_cset,
+ struct cgroup *new_cgrp,
+ struct cgroup_subsys_state *template[])
+{
+ struct cgroup *new_dfl_cgrp;
+ struct list_head *l1, *l2;
+
+ /*
+ * On the default hierarchy, there can be csets which are
+ * associated with the same set of cgroups but different csses.
+ * Let's first ensure that csses match.
+ */
+ if (memcmp(template, cset->subsys, sizeof(cset->subsys)))
+ return false;
+
+
+ /* @cset's domain should match the default cgroup's */
+ if (cgroup_on_dfl(new_cgrp))
+ new_dfl_cgrp = new_cgrp;
+ else
+ new_dfl_cgrp = old_cset->dfl_cgrp;
+
+ if (new_dfl_cgrp->dom_cgrp != cset->dom_cset->dfl_cgrp)
+ return false;
+
+ /*
+ * Compare cgroup pointers in order to distinguish between
+ * different cgroups in hierarchies. As different cgroups may
+ * share the same effective css, this comparison is always
+ * necessary.
+ */
+ l1 = &cset->cgrp_links;
+ l2 = &old_cset->cgrp_links;
+ while (1) {
+ struct cgrp_cset_link *link1, *link2;
+ struct cgroup *cgrp1, *cgrp2;
+
+ l1 = l1->next;
+ l2 = l2->next;
+ /* See if we reached the end - both lists are equal length. */
+ if (l1 == &cset->cgrp_links) {
+ BUG_ON(l2 != &old_cset->cgrp_links);
+ break;
+ } else {
+ BUG_ON(l2 == &old_cset->cgrp_links);
+ }
+ /* Locate the cgroups associated with these links. */
+ link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link);
+ link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link);
+ cgrp1 = link1->cgrp;
+ cgrp2 = link2->cgrp;
+ /* Hierarchies should be linked in the same order. */
+ BUG_ON(cgrp1->root != cgrp2->root);
+
+ /*
+ * If this hierarchy is the hierarchy of the cgroup
+ * that's changing, then we need to check that this
+ * css_set points to the new cgroup; if it's any other
+ * hierarchy, then this css_set should point to the
+ * same cgroup as the old css_set.
+ */
+ if (cgrp1->root == new_cgrp->root) {
+ if (cgrp1 != new_cgrp)
+ return false;
+ } else {
+ if (cgrp1 != cgrp2)
+ return false;
+ }
+ }
+ return true;
+}
+
+/**
+ * find_existing_css_set - init css array and find the matching css_set
+ * @old_cset: the css_set that we're using before the cgroup transition
+ * @cgrp: the cgroup that we're moving into
+ * @template: out param for the new set of csses, should be clear on entry
+ */
+static struct css_set *find_existing_css_set(struct css_set *old_cset,
+ struct cgroup *cgrp,
+ struct cgroup_subsys_state **template)
+{
+ struct cgroup_root *root = cgrp->root;
+ struct cgroup_subsys *ss;
+ struct css_set *cset;
+ unsigned long key;
+ int i;
+
+ /*
+ * Build the set of subsystem state objects that we want to see in the
+ * new css_set. While subsystems can change globally, the entries here
+ * won't change, so no need for locking.
+ */
+ for_each_subsys(ss, i) {
+ if (root->subsys_mask & (1UL << i)) {
+ /*
+ * @ss is in this hierarchy, so we want the
+ * effective css from @cgrp.
+ */
+ template[i] = cgroup_e_css_by_mask(cgrp, ss);
+ } else {
+ /*
+ * @ss is not in this hierarchy, so we don't want
+ * to change the css.
+ */
+ template[i] = old_cset->subsys[i];
+ }
+ }
+
+ key = css_set_hash(template);
+ hash_for_each_possible(css_set_table, cset, hlist, key) {
+ if (!compare_css_sets(cset, old_cset, cgrp, template))
+ continue;
+
+ /* This css_set matches what we need */
+ return cset;
+ }
+
+ /* No existing cgroup group matched */
+ return NULL;
+}
+
+static void free_cgrp_cset_links(struct list_head *links_to_free)
+{
+ struct cgrp_cset_link *link, *tmp_link;
+
+ list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) {
+ list_del(&link->cset_link);
+ kfree(link);
+ }
+}
+
+/**
+ * allocate_cgrp_cset_links - allocate cgrp_cset_links
+ * @count: the number of links to allocate
+ * @tmp_links: list_head the allocated links are put on
+ *
+ * Allocate @count cgrp_cset_link structures and chain them on @tmp_links
+ * through ->cset_link. Returns 0 on success or -errno.
+ */
+static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links)
+{
+ struct cgrp_cset_link *link;
+ int i;
+
+ INIT_LIST_HEAD(tmp_links);
+
+ for (i = 0; i < count; i++) {
+ link = kzalloc(sizeof(*link), GFP_KERNEL);
+ if (!link) {
+ free_cgrp_cset_links(tmp_links);
+ return -ENOMEM;
+ }
+ list_add(&link->cset_link, tmp_links);
+ }
+ return 0;
+}
+
+/**
+ * link_css_set - a helper function to link a css_set to a cgroup
+ * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
+ * @cset: the css_set to be linked
+ * @cgrp: the destination cgroup
+ */
+static void link_css_set(struct list_head *tmp_links, struct css_set *cset,
+ struct cgroup *cgrp)
+{
+ struct cgrp_cset_link *link;
+
+ BUG_ON(list_empty(tmp_links));
+
+ if (cgroup_on_dfl(cgrp))
+ cset->dfl_cgrp = cgrp;
+
+ link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link);
+ link->cset = cset;
+ link->cgrp = cgrp;
+
+ /*
+ * Always add links to the tail of the lists so that the lists are
+ * in chronological order.
+ */
+ list_move_tail(&link->cset_link, &cgrp->cset_links);
+ list_add_tail(&link->cgrp_link, &cset->cgrp_links);
+
+ if (cgroup_parent(cgrp))
+ cgroup_get_live(cgrp);
+}
+
+/**
+ * find_css_set - return a new css_set with one cgroup updated
+ * @old_cset: the baseline css_set
+ * @cgrp: the cgroup to be updated
+ *
+ * Return a new css_set that's equivalent to @old_cset, but with @cgrp
+ * substituted into the appropriate hierarchy.
+ */
+static struct css_set *find_css_set(struct css_set *old_cset,
+ struct cgroup *cgrp)
+{
+ struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { };
+ struct css_set *cset;
+ struct list_head tmp_links;
+ struct cgrp_cset_link *link;
+ struct cgroup_subsys *ss;
+ unsigned long key;
+ int ssid;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* First see if we already have a cgroup group that matches
+ * the desired set */
+ spin_lock_irq(&css_set_lock);
+ cset = find_existing_css_set(old_cset, cgrp, template);
+ if (cset)
+ get_css_set(cset);
+ spin_unlock_irq(&css_set_lock);
+
+ if (cset)
+ return cset;
+
+ cset = kzalloc(sizeof(*cset), GFP_KERNEL);
+ if (!cset)
+ return NULL;
+
+ /* Allocate all the cgrp_cset_link objects that we'll need */
+ if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) {
+ kfree(cset);
+ return NULL;
+ }
+
+ refcount_set(&cset->refcount, 1);
+ cset->dom_cset = cset;
+ INIT_LIST_HEAD(&cset->tasks);
+ INIT_LIST_HEAD(&cset->mg_tasks);
+ INIT_LIST_HEAD(&cset->dying_tasks);
+ INIT_LIST_HEAD(&cset->task_iters);
+ INIT_LIST_HEAD(&cset->threaded_csets);
+ INIT_HLIST_NODE(&cset->hlist);
+ INIT_LIST_HEAD(&cset->cgrp_links);
+ INIT_LIST_HEAD(&cset->mg_src_preload_node);
+ INIT_LIST_HEAD(&cset->mg_dst_preload_node);
+ INIT_LIST_HEAD(&cset->mg_node);
+
+ /* Copy the set of subsystem state objects generated in
+ * find_existing_css_set() */
+ memcpy(cset->subsys, template, sizeof(cset->subsys));
+
+ spin_lock_irq(&css_set_lock);
+ /* Add reference counts and links from the new css_set. */
+ list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) {
+ struct cgroup *c = link->cgrp;
+
+ if (c->root == cgrp->root)
+ c = cgrp;
+ link_css_set(&tmp_links, cset, c);
+ }
+
+ BUG_ON(!list_empty(&tmp_links));
+
+ css_set_count++;
+
+ /* Add @cset to the hash table */
+ key = css_set_hash(cset->subsys);
+ hash_add(css_set_table, &cset->hlist, key);
+
+ for_each_subsys(ss, ssid) {
+ struct cgroup_subsys_state *css = cset->subsys[ssid];
+
+ list_add_tail(&cset->e_cset_node[ssid],
+ &css->cgroup->e_csets[ssid]);
+ css_get(css);
+ }
+
+ spin_unlock_irq(&css_set_lock);
+
+ /*
+ * If @cset should be threaded, look up the matching dom_cset and
+ * link them up. We first fully initialize @cset then look for the
+ * dom_cset. It's simpler this way and safe as @cset is guaranteed
+ * to stay empty until we return.
+ */
+ if (cgroup_is_threaded(cset->dfl_cgrp)) {
+ struct css_set *dcset;
+
+ dcset = find_css_set(cset, cset->dfl_cgrp->dom_cgrp);
+ if (!dcset) {
+ put_css_set(cset);
+ return NULL;
+ }
+
+ spin_lock_irq(&css_set_lock);
+ cset->dom_cset = dcset;
+ list_add_tail(&cset->threaded_csets_node,
+ &dcset->threaded_csets);
+ spin_unlock_irq(&css_set_lock);
+ }
+
+ return cset;
+}
+
+struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
+{
+ struct cgroup *root_cgrp = kernfs_root_to_node(kf_root)->priv;
+
+ return root_cgrp->root;
+}
+
+void cgroup_favor_dynmods(struct cgroup_root *root, bool favor)
+{
+ bool favoring = root->flags & CGRP_ROOT_FAVOR_DYNMODS;
+
+ /* see the comment above CGRP_ROOT_FAVOR_DYNMODS definition */
+ if (favor && !favoring) {
+ rcu_sync_enter(&cgroup_threadgroup_rwsem.rss);
+ root->flags |= CGRP_ROOT_FAVOR_DYNMODS;
+ } else if (!favor && favoring) {
+ rcu_sync_exit(&cgroup_threadgroup_rwsem.rss);
+ root->flags &= ~CGRP_ROOT_FAVOR_DYNMODS;
+ }
+}
+
+static int cgroup_init_root_id(struct cgroup_root *root)
+{
+ int id;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL);
+ if (id < 0)
+ return id;
+
+ root->hierarchy_id = id;
+ return 0;
+}
+
+static void cgroup_exit_root_id(struct cgroup_root *root)
+{
+ lockdep_assert_held(&cgroup_mutex);
+
+ idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
+}
+
+void cgroup_free_root(struct cgroup_root *root)
+{
+ kfree(root);
+}
+
+static void cgroup_destroy_root(struct cgroup_root *root)
+{
+ struct cgroup *cgrp = &root->cgrp;
+ struct cgrp_cset_link *link, *tmp_link;
+
+ trace_cgroup_destroy_root(root);
+
+ cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
+
+ BUG_ON(atomic_read(&root->nr_cgrps));
+ BUG_ON(!list_empty(&cgrp->self.children));
+
+ /* Rebind all subsystems back to the default hierarchy */
+ WARN_ON(rebind_subsystems(&cgrp_dfl_root, root->subsys_mask));
+
+ /*
+ * Release all the links from cset_links to this hierarchy's
+ * root cgroup
+ */
+ spin_lock_irq(&css_set_lock);
+
+ list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
+ list_del(&link->cset_link);
+ list_del(&link->cgrp_link);
+ kfree(link);
+ }
+
+ spin_unlock_irq(&css_set_lock);
+
+ if (!list_empty(&root->root_list)) {
+ list_del(&root->root_list);
+ cgroup_root_count--;
+ }
+
+ cgroup_favor_dynmods(root, false);
+ cgroup_exit_root_id(root);
+
+ cgroup_unlock();
+
+ cgroup_rstat_exit(cgrp);
+ kernfs_destroy_root(root->kf_root);
+ cgroup_free_root(root);
+}
+
+/*
+ * Returned cgroup is without refcount but it's valid as long as cset pins it.
+ */
+static inline struct cgroup *__cset_cgroup_from_root(struct css_set *cset,
+ struct cgroup_root *root)
+{
+ struct cgroup *res_cgroup = NULL;
+
+ if (cset == &init_css_set) {
+ res_cgroup = &root->cgrp;
+ } else if (root == &cgrp_dfl_root) {
+ res_cgroup = cset->dfl_cgrp;
+ } else {
+ struct cgrp_cset_link *link;
+ lockdep_assert_held(&css_set_lock);
+
+ list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
+ struct cgroup *c = link->cgrp;
+
+ if (c->root == root) {
+ res_cgroup = c;
+ break;
+ }
+ }
+ }
+
+ BUG_ON(!res_cgroup);
+ return res_cgroup;
+}
+
+/*
+ * look up cgroup associated with current task's cgroup namespace on the
+ * specified hierarchy
+ */
+static struct cgroup *
+current_cgns_cgroup_from_root(struct cgroup_root *root)
+{
+ struct cgroup *res = NULL;
+ struct css_set *cset;
+
+ lockdep_assert_held(&css_set_lock);
+
+ rcu_read_lock();
+
+ cset = current->nsproxy->cgroup_ns->root_cset;
+ res = __cset_cgroup_from_root(cset, root);
+
+ rcu_read_unlock();
+
+ return res;
+}
+
+/*
+ * Look up cgroup associated with current task's cgroup namespace on the default
+ * hierarchy.
+ *
+ * Unlike current_cgns_cgroup_from_root(), this doesn't need locks:
+ * - Internal rcu_read_lock is unnecessary because we don't dereference any rcu
+ * pointers.
+ * - css_set_lock is not needed because we just read cset->dfl_cgrp.
+ * - As a bonus returned cgrp is pinned with the current because it cannot
+ * switch cgroup_ns asynchronously.
+ */
+static struct cgroup *current_cgns_cgroup_dfl(void)
+{
+ struct css_set *cset;
+
+ if (current->nsproxy) {
+ cset = current->nsproxy->cgroup_ns->root_cset;
+ return __cset_cgroup_from_root(cset, &cgrp_dfl_root);
+ } else {
+ /*
+ * NOTE: This function may be called from bpf_cgroup_from_id()
+ * on a task which has already passed exit_task_namespaces() and
+ * nsproxy == NULL. Fall back to cgrp_dfl_root which will make all
+ * cgroups visible for lookups.
+ */
+ return &cgrp_dfl_root.cgrp;
+ }
+}
+
+/* look up cgroup associated with given css_set on the specified hierarchy */
+static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
+ struct cgroup_root *root)
+{
+ lockdep_assert_held(&cgroup_mutex);
+ lockdep_assert_held(&css_set_lock);
+
+ return __cset_cgroup_from_root(cset, root);
+}
+
+/*
+ * Return the cgroup for "task" from the given hierarchy. Must be
+ * called with cgroup_mutex and css_set_lock held.
+ */
+struct cgroup *task_cgroup_from_root(struct task_struct *task,
+ struct cgroup_root *root)
+{
+ /*
+ * No need to lock the task - since we hold css_set_lock the
+ * task can't change groups.
+ */
+ return cset_cgroup_from_root(task_css_set(task), root);
+}
+
+/*
+ * A task must hold cgroup_mutex to modify cgroups.
+ *
+ * Any task can increment and decrement the count field without lock.
+ * So in general, code holding cgroup_mutex can't rely on the count
+ * field not changing. However, if the count goes to zero, then only
+ * cgroup_attach_task() can increment it again. Because a count of zero
+ * means that no tasks are currently attached, therefore there is no
+ * way a task attached to that cgroup can fork (the other way to
+ * increment the count). So code holding cgroup_mutex can safely
+ * assume that if the count is zero, it will stay zero. Similarly, if
+ * a task holds cgroup_mutex on a cgroup with zero count, it
+ * knows that the cgroup won't be removed, as cgroup_rmdir()
+ * needs that mutex.
+ *
+ * A cgroup can only be deleted if both its 'count' of using tasks
+ * is zero, and its list of 'children' cgroups is empty. Since all
+ * tasks in the system use _some_ cgroup, and since there is always at
+ * least one task in the system (init, pid == 1), therefore, root cgroup
+ * always has either children cgroups and/or using tasks. So we don't
+ * need a special hack to ensure that root cgroup cannot be deleted.
+ *
+ * P.S. One more locking exception. RCU is used to guard the
+ * update of a tasks cgroup pointer by cgroup_attach_task()
+ */
+
+static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
+
+static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
+ char *buf)
+{
+ struct cgroup_subsys *ss = cft->ss;
+
+ if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
+ !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) {
+ const char *dbg = (cft->flags & CFTYPE_DEBUG) ? ".__DEBUG__." : "";
+
+ snprintf(buf, CGROUP_FILE_NAME_MAX, "%s%s.%s",
+ dbg, cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name,
+ cft->name);
+ } else {
+ strscpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
+ }
+ return buf;
+}
+
+/**
+ * cgroup_file_mode - deduce file mode of a control file
+ * @cft: the control file in question
+ *
+ * S_IRUGO for read, S_IWUSR for write.
+ */
+static umode_t cgroup_file_mode(const struct cftype *cft)
+{
+ umode_t mode = 0;
+
+ if (cft->read_u64 || cft->read_s64 || cft->seq_show)
+ mode |= S_IRUGO;
+
+ if (cft->write_u64 || cft->write_s64 || cft->write) {
+ if (cft->flags & CFTYPE_WORLD_WRITABLE)
+ mode |= S_IWUGO;
+ else
+ mode |= S_IWUSR;
+ }
+
+ return mode;
+}
+
+/**
+ * cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask
+ * @subtree_control: the new subtree_control mask to consider
+ * @this_ss_mask: available subsystems
+ *
+ * On the default hierarchy, a subsystem may request other subsystems to be
+ * enabled together through its ->depends_on mask. In such cases, more
+ * subsystems than specified in "cgroup.subtree_control" may be enabled.
+ *
+ * This function calculates which subsystems need to be enabled if
+ * @subtree_control is to be applied while restricted to @this_ss_mask.
+ */
+static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask)
+{
+ u16 cur_ss_mask = subtree_control;
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ cur_ss_mask |= cgrp_dfl_implicit_ss_mask;
+
+ while (true) {
+ u16 new_ss_mask = cur_ss_mask;
+
+ do_each_subsys_mask(ss, ssid, cur_ss_mask) {
+ new_ss_mask |= ss->depends_on;
+ } while_each_subsys_mask();
+
+ /*
+ * Mask out subsystems which aren't available. This can
+ * happen only if some depended-upon subsystems were bound
+ * to non-default hierarchies.
+ */
+ new_ss_mask &= this_ss_mask;
+
+ if (new_ss_mask == cur_ss_mask)
+ break;
+ cur_ss_mask = new_ss_mask;
+ }
+
+ return cur_ss_mask;
+}
+
+/**
+ * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
+ * @kn: the kernfs_node being serviced
+ *
+ * This helper undoes cgroup_kn_lock_live() and should be invoked before
+ * the method finishes if locking succeeded. Note that once this function
+ * returns the cgroup returned by cgroup_kn_lock_live() may become
+ * inaccessible any time. If the caller intends to continue to access the
+ * cgroup, it should pin it before invoking this function.
+ */
+void cgroup_kn_unlock(struct kernfs_node *kn)
+{
+ struct cgroup *cgrp;
+
+ if (kernfs_type(kn) == KERNFS_DIR)
+ cgrp = kn->priv;
+ else
+ cgrp = kn->parent->priv;
+
+ cgroup_unlock();
+
+ kernfs_unbreak_active_protection(kn);
+ cgroup_put(cgrp);
+}
+
+/**
+ * cgroup_kn_lock_live - locking helper for cgroup kernfs methods
+ * @kn: the kernfs_node being serviced
+ * @drain_offline: perform offline draining on the cgroup
+ *
+ * This helper is to be used by a cgroup kernfs method currently servicing
+ * @kn. It breaks the active protection, performs cgroup locking and
+ * verifies that the associated cgroup is alive. Returns the cgroup if
+ * alive; otherwise, %NULL. A successful return should be undone by a
+ * matching cgroup_kn_unlock() invocation. If @drain_offline is %true, the
+ * cgroup is drained of offlining csses before return.
+ *
+ * Any cgroup kernfs method implementation which requires locking the
+ * associated cgroup should use this helper. It avoids nesting cgroup
+ * locking under kernfs active protection and allows all kernfs operations
+ * including self-removal.
+ */
+struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline)
+{
+ struct cgroup *cgrp;
+
+ if (kernfs_type(kn) == KERNFS_DIR)
+ cgrp = kn->priv;
+ else
+ cgrp = kn->parent->priv;
+
+ /*
+ * We're gonna grab cgroup_mutex which nests outside kernfs
+ * active_ref. cgroup liveliness check alone provides enough
+ * protection against removal. Ensure @cgrp stays accessible and
+ * break the active_ref protection.
+ */
+ if (!cgroup_tryget(cgrp))
+ return NULL;
+ kernfs_break_active_protection(kn);
+
+ if (drain_offline)
+ cgroup_lock_and_drain_offline(cgrp);
+ else
+ cgroup_lock();
+
+ if (!cgroup_is_dead(cgrp))
+ return cgrp;
+
+ cgroup_kn_unlock(kn);
+ return NULL;
+}
+
+static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
+{
+ char name[CGROUP_FILE_NAME_MAX];
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ if (cft->file_offset) {
+ struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss);
+ struct cgroup_file *cfile = (void *)css + cft->file_offset;
+
+ spin_lock_irq(&cgroup_file_kn_lock);
+ cfile->kn = NULL;
+ spin_unlock_irq(&cgroup_file_kn_lock);
+
+ del_timer_sync(&cfile->notify_timer);
+ }
+
+ kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
+}
+
+/**
+ * css_clear_dir - remove subsys files in a cgroup directory
+ * @css: target css
+ */
+static void css_clear_dir(struct cgroup_subsys_state *css)
+{
+ struct cgroup *cgrp = css->cgroup;
+ struct cftype *cfts;
+
+ if (!(css->flags & CSS_VISIBLE))
+ return;
+
+ css->flags &= ~CSS_VISIBLE;
+
+ if (!css->ss) {
+ if (cgroup_on_dfl(cgrp)) {
+ cgroup_addrm_files(css, cgrp,
+ cgroup_base_files, false);
+ if (cgroup_psi_enabled())
+ cgroup_addrm_files(css, cgrp,
+ cgroup_psi_files, false);
+ } else {
+ cgroup_addrm_files(css, cgrp,
+ cgroup1_base_files, false);
+ }
+ } else {
+ list_for_each_entry(cfts, &css->ss->cfts, node)
+ cgroup_addrm_files(css, cgrp, cfts, false);
+ }
+}
+
+/**
+ * css_populate_dir - create subsys files in a cgroup directory
+ * @css: target css
+ *
+ * On failure, no file is added.
+ */
+static int css_populate_dir(struct cgroup_subsys_state *css)
+{
+ struct cgroup *cgrp = css->cgroup;
+ struct cftype *cfts, *failed_cfts;
+ int ret;
+
+ if (css->flags & CSS_VISIBLE)
+ return 0;
+
+ if (!css->ss) {
+ if (cgroup_on_dfl(cgrp)) {
+ ret = cgroup_addrm_files(&cgrp->self, cgrp,
+ cgroup_base_files, true);
+ if (ret < 0)
+ return ret;
+
+ if (cgroup_psi_enabled()) {
+ ret = cgroup_addrm_files(&cgrp->self, cgrp,
+ cgroup_psi_files, true);
+ if (ret < 0)
+ return ret;
+ }
+ } else {
+ cgroup_addrm_files(css, cgrp,
+ cgroup1_base_files, true);
+ }
+ } else {
+ list_for_each_entry(cfts, &css->ss->cfts, node) {
+ ret = cgroup_addrm_files(css, cgrp, cfts, true);
+ if (ret < 0) {
+ failed_cfts = cfts;
+ goto err;
+ }
+ }
+ }
+
+ css->flags |= CSS_VISIBLE;
+
+ return 0;
+err:
+ list_for_each_entry(cfts, &css->ss->cfts, node) {
+ if (cfts == failed_cfts)
+ break;
+ cgroup_addrm_files(css, cgrp, cfts, false);
+ }
+ return ret;
+}
+
+int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
+{
+ struct cgroup *dcgrp = &dst_root->cgrp;
+ struct cgroup_subsys *ss;
+ int ssid, ret;
+ u16 dfl_disable_ss_mask = 0;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ do_each_subsys_mask(ss, ssid, ss_mask) {
+ /*
+ * If @ss has non-root csses attached to it, can't move.
+ * If @ss is an implicit controller, it is exempt from this
+ * rule and can be stolen.
+ */
+ if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss)) &&
+ !ss->implicit_on_dfl)
+ return -EBUSY;
+
+ /* can't move between two non-dummy roots either */
+ if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root)
+ return -EBUSY;
+
+ /*
+ * Collect ssid's that need to be disabled from default
+ * hierarchy.
+ */
+ if (ss->root == &cgrp_dfl_root)
+ dfl_disable_ss_mask |= 1 << ssid;
+
+ } while_each_subsys_mask();
+
+ if (dfl_disable_ss_mask) {
+ struct cgroup *scgrp = &cgrp_dfl_root.cgrp;
+
+ /*
+ * Controllers from default hierarchy that need to be rebound
+ * are all disabled together in one go.
+ */
+ cgrp_dfl_root.subsys_mask &= ~dfl_disable_ss_mask;
+ WARN_ON(cgroup_apply_control(scgrp));
+ cgroup_finalize_control(scgrp, 0);
+ }
+
+ do_each_subsys_mask(ss, ssid, ss_mask) {
+ struct cgroup_root *src_root = ss->root;
+ struct cgroup *scgrp = &src_root->cgrp;
+ struct cgroup_subsys_state *css = cgroup_css(scgrp, ss);
+ struct css_set *cset, *cset_pos;
+ struct css_task_iter *it;
+
+ WARN_ON(!css || cgroup_css(dcgrp, ss));
+
+ if (src_root != &cgrp_dfl_root) {
+ /* disable from the source */
+ src_root->subsys_mask &= ~(1 << ssid);
+ WARN_ON(cgroup_apply_control(scgrp));
+ cgroup_finalize_control(scgrp, 0);
+ }
+
+ /* rebind */
+ RCU_INIT_POINTER(scgrp->subsys[ssid], NULL);
+ rcu_assign_pointer(dcgrp->subsys[ssid], css);
+ ss->root = dst_root;
+ css->cgroup = dcgrp;
+
+ spin_lock_irq(&css_set_lock);
+ WARN_ON(!list_empty(&dcgrp->e_csets[ss->id]));
+ list_for_each_entry_safe(cset, cset_pos, &scgrp->e_csets[ss->id],
+ e_cset_node[ss->id]) {
+ list_move_tail(&cset->e_cset_node[ss->id],
+ &dcgrp->e_csets[ss->id]);
+ /*
+ * all css_sets of scgrp together in same order to dcgrp,
+ * patch in-flight iterators to preserve correct iteration.
+ * since the iterator is always advanced right away and
+ * finished when it->cset_pos meets it->cset_head, so only
+ * update it->cset_head is enough here.
+ */
+ list_for_each_entry(it, &cset->task_iters, iters_node)
+ if (it->cset_head == &scgrp->e_csets[ss->id])
+ it->cset_head = &dcgrp->e_csets[ss->id];
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ if (ss->css_rstat_flush) {
+ list_del_rcu(&css->rstat_css_node);
+ synchronize_rcu();
+ list_add_rcu(&css->rstat_css_node,
+ &dcgrp->rstat_css_list);
+ }
+
+ /* default hierarchy doesn't enable controllers by default */
+ dst_root->subsys_mask |= 1 << ssid;
+ if (dst_root == &cgrp_dfl_root) {
+ static_branch_enable(cgroup_subsys_on_dfl_key[ssid]);
+ } else {
+ dcgrp->subtree_control |= 1 << ssid;
+ static_branch_disable(cgroup_subsys_on_dfl_key[ssid]);
+ }
+
+ ret = cgroup_apply_control(dcgrp);
+ if (ret)
+ pr_warn("partial failure to rebind %s controller (err=%d)\n",
+ ss->name, ret);
+
+ if (ss->bind)
+ ss->bind(css);
+ } while_each_subsys_mask();
+
+ kernfs_activate(dcgrp->kn);
+ return 0;
+}
+
+int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
+ struct kernfs_root *kf_root)
+{
+ int len = 0;
+ char *buf = NULL;
+ struct cgroup_root *kf_cgroot = cgroup_root_from_kf(kf_root);
+ struct cgroup *ns_cgroup;
+
+ buf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ spin_lock_irq(&css_set_lock);
+ ns_cgroup = current_cgns_cgroup_from_root(kf_cgroot);
+ len = kernfs_path_from_node(kf_node, ns_cgroup->kn, buf, PATH_MAX);
+ spin_unlock_irq(&css_set_lock);
+
+ if (len >= PATH_MAX)
+ len = -ERANGE;
+ else if (len > 0) {
+ seq_escape(sf, buf, " \t\n\\");
+ len = 0;
+ }
+ kfree(buf);
+ return len;
+}
+
+enum cgroup2_param {
+ Opt_nsdelegate,
+ Opt_favordynmods,
+ Opt_memory_localevents,
+ Opt_memory_recursiveprot,
+ nr__cgroup2_params
+};
+
+static const struct fs_parameter_spec cgroup2_fs_parameters[] = {
+ fsparam_flag("nsdelegate", Opt_nsdelegate),
+ fsparam_flag("favordynmods", Opt_favordynmods),
+ fsparam_flag("memory_localevents", Opt_memory_localevents),
+ fsparam_flag("memory_recursiveprot", Opt_memory_recursiveprot),
+ {}
+};
+
+static int cgroup2_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+ struct fs_parse_result result;
+ int opt;
+
+ opt = fs_parse(fc, cgroup2_fs_parameters, param, &result);
+ if (opt < 0)
+ return opt;
+
+ switch (opt) {
+ case Opt_nsdelegate:
+ ctx->flags |= CGRP_ROOT_NS_DELEGATE;
+ return 0;
+ case Opt_favordynmods:
+ ctx->flags |= CGRP_ROOT_FAVOR_DYNMODS;
+ return 0;
+ case Opt_memory_localevents:
+ ctx->flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS;
+ return 0;
+ case Opt_memory_recursiveprot:
+ ctx->flags |= CGRP_ROOT_MEMORY_RECURSIVE_PROT;
+ return 0;
+ }
+ return -EINVAL;
+}
+
+static void apply_cgroup_root_flags(unsigned int root_flags)
+{
+ if (current->nsproxy->cgroup_ns == &init_cgroup_ns) {
+ if (root_flags & CGRP_ROOT_NS_DELEGATE)
+ cgrp_dfl_root.flags |= CGRP_ROOT_NS_DELEGATE;
+ else
+ cgrp_dfl_root.flags &= ~CGRP_ROOT_NS_DELEGATE;
+
+ cgroup_favor_dynmods(&cgrp_dfl_root,
+ root_flags & CGRP_ROOT_FAVOR_DYNMODS);
+
+ if (root_flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
+ cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS;
+ else
+ cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_LOCAL_EVENTS;
+
+ if (root_flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT)
+ cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_RECURSIVE_PROT;
+ else
+ cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_RECURSIVE_PROT;
+ }
+}
+
+static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
+{
+ if (cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE)
+ seq_puts(seq, ",nsdelegate");
+ if (cgrp_dfl_root.flags & CGRP_ROOT_FAVOR_DYNMODS)
+ seq_puts(seq, ",favordynmods");
+ if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
+ seq_puts(seq, ",memory_localevents");
+ if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT)
+ seq_puts(seq, ",memory_recursiveprot");
+ return 0;
+}
+
+static int cgroup_reconfigure(struct fs_context *fc)
+{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+
+ apply_cgroup_root_flags(ctx->flags);
+ return 0;
+}
+
+static void init_cgroup_housekeeping(struct cgroup *cgrp)
+{
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ INIT_LIST_HEAD(&cgrp->self.sibling);
+ INIT_LIST_HEAD(&cgrp->self.children);
+ INIT_LIST_HEAD(&cgrp->cset_links);
+ INIT_LIST_HEAD(&cgrp->pidlists);
+ mutex_init(&cgrp->pidlist_mutex);
+ cgrp->self.cgroup = cgrp;
+ cgrp->self.flags |= CSS_ONLINE;
+ cgrp->dom_cgrp = cgrp;
+ cgrp->max_descendants = INT_MAX;
+ cgrp->max_depth = INT_MAX;
+ INIT_LIST_HEAD(&cgrp->rstat_css_list);
+ prev_cputime_init(&cgrp->prev_cputime);
+
+ for_each_subsys(ss, ssid)
+ INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
+
+ init_waitqueue_head(&cgrp->offline_waitq);
+ INIT_WORK(&cgrp->release_agent_work, cgroup1_release_agent);
+}
+
+void init_cgroup_root(struct cgroup_fs_context *ctx)
+{
+ struct cgroup_root *root = ctx->root;
+ struct cgroup *cgrp = &root->cgrp;
+
+ INIT_LIST_HEAD(&root->root_list);
+ atomic_set(&root->nr_cgrps, 1);
+ cgrp->root = root;
+ init_cgroup_housekeeping(cgrp);
+
+ /* DYNMODS must be modified through cgroup_favor_dynmods() */
+ root->flags = ctx->flags & ~CGRP_ROOT_FAVOR_DYNMODS;
+ if (ctx->release_agent)
+ strscpy(root->release_agent_path, ctx->release_agent, PATH_MAX);
+ if (ctx->name)
+ strscpy(root->name, ctx->name, MAX_CGROUP_ROOT_NAMELEN);
+ if (ctx->cpuset_clone_children)
+ set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
+}
+
+int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
+{
+ LIST_HEAD(tmp_links);
+ struct cgroup *root_cgrp = &root->cgrp;
+ struct kernfs_syscall_ops *kf_sops;
+ struct css_set *cset;
+ int i, ret;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release,
+ 0, GFP_KERNEL);
+ if (ret)
+ goto out;
+
+ /*
+ * We're accessing css_set_count without locking css_set_lock here,
+ * but that's OK - it can only be increased by someone holding
+ * cgroup_lock, and that's us. Later rebinding may disable
+ * controllers on the default hierarchy and thus create new csets,
+ * which can't be more than the existing ones. Allocate 2x.
+ */
+ ret = allocate_cgrp_cset_links(2 * css_set_count, &tmp_links);
+ if (ret)
+ goto cancel_ref;
+
+ ret = cgroup_init_root_id(root);
+ if (ret)
+ goto cancel_ref;
+
+ kf_sops = root == &cgrp_dfl_root ?
+ &cgroup_kf_syscall_ops : &cgroup1_kf_syscall_ops;
+
+ root->kf_root = kernfs_create_root(kf_sops,
+ KERNFS_ROOT_CREATE_DEACTIVATED |
+ KERNFS_ROOT_SUPPORT_EXPORTOP |
+ KERNFS_ROOT_SUPPORT_USER_XATTR,
+ root_cgrp);
+ if (IS_ERR(root->kf_root)) {
+ ret = PTR_ERR(root->kf_root);
+ goto exit_root_id;
+ }
+ root_cgrp->kn = kernfs_root_to_node(root->kf_root);
+ WARN_ON_ONCE(cgroup_ino(root_cgrp) != 1);
+ root_cgrp->ancestors[0] = root_cgrp;
+
+ ret = css_populate_dir(&root_cgrp->self);
+ if (ret)
+ goto destroy_root;
+
+ ret = cgroup_rstat_init(root_cgrp);
+ if (ret)
+ goto destroy_root;
+
+ ret = rebind_subsystems(root, ss_mask);
+ if (ret)
+ goto exit_stats;
+
+ ret = cgroup_bpf_inherit(root_cgrp);
+ WARN_ON_ONCE(ret);
+
+ trace_cgroup_setup_root(root);
+
+ /*
+ * There must be no failure case after here, since rebinding takes
+ * care of subsystems' refcounts, which are explicitly dropped in
+ * the failure exit path.
+ */
+ list_add(&root->root_list, &cgroup_roots);
+ cgroup_root_count++;
+
+ /*
+ * Link the root cgroup in this hierarchy into all the css_set
+ * objects.
+ */
+ spin_lock_irq(&css_set_lock);
+ hash_for_each(css_set_table, i, cset, hlist) {
+ link_css_set(&tmp_links, cset, root_cgrp);
+ if (css_set_populated(cset))
+ cgroup_update_populated(root_cgrp, true);
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ BUG_ON(!list_empty(&root_cgrp->self.children));
+ BUG_ON(atomic_read(&root->nr_cgrps) != 1);
+
+ ret = 0;
+ goto out;
+
+exit_stats:
+ cgroup_rstat_exit(root_cgrp);
+destroy_root:
+ kernfs_destroy_root(root->kf_root);
+ root->kf_root = NULL;
+exit_root_id:
+ cgroup_exit_root_id(root);
+cancel_ref:
+ percpu_ref_exit(&root_cgrp->self.refcnt);
+out:
+ free_cgrp_cset_links(&tmp_links);
+ return ret;
+}
+
+int cgroup_do_get_tree(struct fs_context *fc)
+{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+ int ret;
+
+ ctx->kfc.root = ctx->root->kf_root;
+ if (fc->fs_type == &cgroup2_fs_type)
+ ctx->kfc.magic = CGROUP2_SUPER_MAGIC;
+ else
+ ctx->kfc.magic = CGROUP_SUPER_MAGIC;
+ ret = kernfs_get_tree(fc);
+
+ /*
+ * In non-init cgroup namespace, instead of root cgroup's dentry,
+ * we return the dentry corresponding to the cgroupns->root_cgrp.
+ */
+ if (!ret && ctx->ns != &init_cgroup_ns) {
+ struct dentry *nsdentry;
+ struct super_block *sb = fc->root->d_sb;
+ struct cgroup *cgrp;
+
+ cgroup_lock();
+ spin_lock_irq(&css_set_lock);
+
+ cgrp = cset_cgroup_from_root(ctx->ns->root_cset, ctx->root);
+
+ spin_unlock_irq(&css_set_lock);
+ cgroup_unlock();
+
+ nsdentry = kernfs_node_dentry(cgrp->kn, sb);
+ dput(fc->root);
+ if (IS_ERR(nsdentry)) {
+ deactivate_locked_super(sb);
+ ret = PTR_ERR(nsdentry);
+ nsdentry = NULL;
+ }
+ fc->root = nsdentry;
+ }
+
+ if (!ctx->kfc.new_sb_created)
+ cgroup_put(&ctx->root->cgrp);
+
+ return ret;
+}
+
+/*
+ * Destroy a cgroup filesystem context.
+ */
+static void cgroup_fs_context_free(struct fs_context *fc)
+{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+
+ kfree(ctx->name);
+ kfree(ctx->release_agent);
+ put_cgroup_ns(ctx->ns);
+ kernfs_free_fs_context(fc);
+ kfree(ctx);
+}
+
+static int cgroup_get_tree(struct fs_context *fc)
+{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+ int ret;
+
+ WRITE_ONCE(cgrp_dfl_visible, true);
+ cgroup_get_live(&cgrp_dfl_root.cgrp);
+ ctx->root = &cgrp_dfl_root;
+
+ ret = cgroup_do_get_tree(fc);
+ if (!ret)
+ apply_cgroup_root_flags(ctx->flags);
+ return ret;
+}
+
+static const struct fs_context_operations cgroup_fs_context_ops = {
+ .free = cgroup_fs_context_free,
+ .parse_param = cgroup2_parse_param,
+ .get_tree = cgroup_get_tree,
+ .reconfigure = cgroup_reconfigure,
+};
+
+static const struct fs_context_operations cgroup1_fs_context_ops = {
+ .free = cgroup_fs_context_free,
+ .parse_param = cgroup1_parse_param,
+ .get_tree = cgroup1_get_tree,
+ .reconfigure = cgroup1_reconfigure,
+};
+
+/*
+ * Initialise the cgroup filesystem creation/reconfiguration context. Notably,
+ * we select the namespace we're going to use.
+ */
+static int cgroup_init_fs_context(struct fs_context *fc)
+{
+ struct cgroup_fs_context *ctx;
+
+ ctx = kzalloc(sizeof(struct cgroup_fs_context), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+
+ ctx->ns = current->nsproxy->cgroup_ns;
+ get_cgroup_ns(ctx->ns);
+ fc->fs_private = &ctx->kfc;
+ if (fc->fs_type == &cgroup2_fs_type)
+ fc->ops = &cgroup_fs_context_ops;
+ else
+ fc->ops = &cgroup1_fs_context_ops;
+ put_user_ns(fc->user_ns);
+ fc->user_ns = get_user_ns(ctx->ns->user_ns);
+ fc->global = true;
+
+#ifdef CONFIG_CGROUP_FAVOR_DYNMODS
+ ctx->flags |= CGRP_ROOT_FAVOR_DYNMODS;
+#endif
+ return 0;
+}
+
+static void cgroup_kill_sb(struct super_block *sb)
+{
+ struct kernfs_root *kf_root = kernfs_root_from_sb(sb);
+ struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+
+ /*
+ * If @root doesn't have any children, start killing it.
+ * This prevents new mounts by disabling percpu_ref_tryget_live().
+ *
+ * And don't kill the default root.
+ */
+ if (list_empty(&root->cgrp.self.children) && root != &cgrp_dfl_root &&
+ !percpu_ref_is_dying(&root->cgrp.self.refcnt)) {
+ cgroup_bpf_offline(&root->cgrp);
+ percpu_ref_kill(&root->cgrp.self.refcnt);
+ }
+ cgroup_put(&root->cgrp);
+ kernfs_kill_sb(sb);
+}
+
+struct file_system_type cgroup_fs_type = {
+ .name = "cgroup",
+ .init_fs_context = cgroup_init_fs_context,
+ .parameters = cgroup1_fs_parameters,
+ .kill_sb = cgroup_kill_sb,
+ .fs_flags = FS_USERNS_MOUNT,
+};
+
+static struct file_system_type cgroup2_fs_type = {
+ .name = "cgroup2",
+ .init_fs_context = cgroup_init_fs_context,
+ .parameters = cgroup2_fs_parameters,
+ .kill_sb = cgroup_kill_sb,
+ .fs_flags = FS_USERNS_MOUNT,
+};
+
+#ifdef CONFIG_CPUSETS
+static const struct fs_context_operations cpuset_fs_context_ops = {
+ .get_tree = cgroup1_get_tree,
+ .free = cgroup_fs_context_free,
+};
+
+/*
+ * This is ugly, but preserves the userspace API for existing cpuset
+ * users. If someone tries to mount the "cpuset" filesystem, we
+ * silently switch it to mount "cgroup" instead
+ */
+static int cpuset_init_fs_context(struct fs_context *fc)
+{
+ char *agent = kstrdup("/sbin/cpuset_release_agent", GFP_USER);
+ struct cgroup_fs_context *ctx;
+ int err;
+
+ err = cgroup_init_fs_context(fc);
+ if (err) {
+ kfree(agent);
+ return err;
+ }
+
+ fc->ops = &cpuset_fs_context_ops;
+
+ ctx = cgroup_fc2context(fc);
+ ctx->subsys_mask = 1 << cpuset_cgrp_id;
+ ctx->flags |= CGRP_ROOT_NOPREFIX;
+ ctx->release_agent = agent;
+
+ get_filesystem(&cgroup_fs_type);
+ put_filesystem(fc->fs_type);
+ fc->fs_type = &cgroup_fs_type;
+
+ return 0;
+}
+
+static struct file_system_type cpuset_fs_type = {
+ .name = "cpuset",
+ .init_fs_context = cpuset_init_fs_context,
+ .fs_flags = FS_USERNS_MOUNT,
+};
+#endif
+
+int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
+ struct cgroup_namespace *ns)
+{
+ struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root);
+
+ return kernfs_path_from_node(cgrp->kn, root->kn, buf, buflen);
+}
+
+int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
+ struct cgroup_namespace *ns)
+{
+ int ret;
+
+ cgroup_lock();
+ spin_lock_irq(&css_set_lock);
+
+ ret = cgroup_path_ns_locked(cgrp, buf, buflen, ns);
+
+ spin_unlock_irq(&css_set_lock);
+ cgroup_unlock();
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(cgroup_path_ns);
+
+/**
+ * cgroup_attach_lock - Lock for ->attach()
+ * @lock_threadgroup: whether to down_write cgroup_threadgroup_rwsem
+ *
+ * cgroup migration sometimes needs to stabilize threadgroups against forks and
+ * exits by write-locking cgroup_threadgroup_rwsem. However, some ->attach()
+ * implementations (e.g. cpuset), also need to disable CPU hotplug.
+ * Unfortunately, letting ->attach() operations acquire cpus_read_lock() can
+ * lead to deadlocks.
+ *
+ * Bringing up a CPU may involve creating and destroying tasks which requires
+ * read-locking threadgroup_rwsem, so threadgroup_rwsem nests inside
+ * cpus_read_lock(). If we call an ->attach() which acquires the cpus lock while
+ * write-locking threadgroup_rwsem, the locking order is reversed and we end up
+ * waiting for an on-going CPU hotplug operation which in turn is waiting for
+ * the threadgroup_rwsem to be released to create new tasks. For more details:
+ *
+ * http://lkml.kernel.org/r/20220711174629.uehfmqegcwn2lqzu@wubuntu
+ *
+ * Resolve the situation by always acquiring cpus_read_lock() before optionally
+ * write-locking cgroup_threadgroup_rwsem. This allows ->attach() to assume that
+ * CPU hotplug is disabled on entry.
+ */
+void cgroup_attach_lock(bool lock_threadgroup)
+{
+ cpus_read_lock();
+ if (lock_threadgroup)
+ percpu_down_write(&cgroup_threadgroup_rwsem);
+}
+
+/**
+ * cgroup_attach_unlock - Undo cgroup_attach_lock()
+ * @lock_threadgroup: whether to up_write cgroup_threadgroup_rwsem
+ */
+void cgroup_attach_unlock(bool lock_threadgroup)
+{
+ if (lock_threadgroup)
+ percpu_up_write(&cgroup_threadgroup_rwsem);
+ cpus_read_unlock();
+}
+
+/**
+ * cgroup_migrate_add_task - add a migration target task to a migration context
+ * @task: target task
+ * @mgctx: target migration context
+ *
+ * Add @task, which is a migration target, to @mgctx->tset. This function
+ * becomes noop if @task doesn't need to be migrated. @task's css_set
+ * should have been added as a migration source and @task->cg_list will be
+ * moved from the css_set's tasks list to mg_tasks one.
+ */
+static void cgroup_migrate_add_task(struct task_struct *task,
+ struct cgroup_mgctx *mgctx)
+{
+ struct css_set *cset;
+
+ lockdep_assert_held(&css_set_lock);
+
+ /* @task either already exited or can't exit until the end */
+ if (task->flags & PF_EXITING)
+ return;
+
+ /* cgroup_threadgroup_rwsem protects racing against forks */
+ WARN_ON_ONCE(list_empty(&task->cg_list));
+
+ cset = task_css_set(task);
+ if (!cset->mg_src_cgrp)
+ return;
+
+ mgctx->tset.nr_tasks++;
+
+ list_move_tail(&task->cg_list, &cset->mg_tasks);
+ if (list_empty(&cset->mg_node))
+ list_add_tail(&cset->mg_node,
+ &mgctx->tset.src_csets);
+ if (list_empty(&cset->mg_dst_cset->mg_node))
+ list_add_tail(&cset->mg_dst_cset->mg_node,
+ &mgctx->tset.dst_csets);
+}
+
+/**
+ * cgroup_taskset_first - reset taskset and return the first task
+ * @tset: taskset of interest
+ * @dst_cssp: output variable for the destination css
+ *
+ * @tset iteration is initialized and the first task is returned.
+ */
+struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset,
+ struct cgroup_subsys_state **dst_cssp)
+{
+ tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node);
+ tset->cur_task = NULL;
+
+ return cgroup_taskset_next(tset, dst_cssp);
+}
+
+/**
+ * cgroup_taskset_next - iterate to the next task in taskset
+ * @tset: taskset of interest
+ * @dst_cssp: output variable for the destination css
+ *
+ * Return the next task in @tset. Iteration must have been initialized
+ * with cgroup_taskset_first().
+ */
+struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
+ struct cgroup_subsys_state **dst_cssp)
+{
+ struct css_set *cset = tset->cur_cset;
+ struct task_struct *task = tset->cur_task;
+
+ while (CGROUP_HAS_SUBSYS_CONFIG && &cset->mg_node != tset->csets) {
+ if (!task)
+ task = list_first_entry(&cset->mg_tasks,
+ struct task_struct, cg_list);
+ else
+ task = list_next_entry(task, cg_list);
+
+ if (&task->cg_list != &cset->mg_tasks) {
+ tset->cur_cset = cset;
+ tset->cur_task = task;
+
+ /*
+ * This function may be called both before and
+ * after cgroup_migrate_execute(). The two cases
+ * can be distinguished by looking at whether @cset
+ * has its ->mg_dst_cset set.
+ */
+ if (cset->mg_dst_cset)
+ *dst_cssp = cset->mg_dst_cset->subsys[tset->ssid];
+ else
+ *dst_cssp = cset->subsys[tset->ssid];
+
+ return task;
+ }
+
+ cset = list_next_entry(cset, mg_node);
+ task = NULL;
+ }
+
+ return NULL;
+}
+
+/**
+ * cgroup_migrate_execute - migrate a taskset
+ * @mgctx: migration context
+ *
+ * Migrate tasks in @mgctx as setup by migration preparation functions.
+ * This function fails iff one of the ->can_attach callbacks fails and
+ * guarantees that either all or none of the tasks in @mgctx are migrated.
+ * @mgctx is consumed regardless of success.
+ */
+static int cgroup_migrate_execute(struct cgroup_mgctx *mgctx)
+{
+ struct cgroup_taskset *tset = &mgctx->tset;
+ struct cgroup_subsys *ss;
+ struct task_struct *task, *tmp_task;
+ struct css_set *cset, *tmp_cset;
+ int ssid, failed_ssid, ret;
+
+ /* check that we can legitimately attach to the cgroup */
+ if (tset->nr_tasks) {
+ do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
+ if (ss->can_attach) {
+ tset->ssid = ssid;
+ ret = ss->can_attach(tset);
+ if (ret) {
+ failed_ssid = ssid;
+ goto out_cancel_attach;
+ }
+ }
+ } while_each_subsys_mask();
+ }
+
+ /*
+ * Now that we're guaranteed success, proceed to move all tasks to
+ * the new cgroup. There are no failure cases after here, so this
+ * is the commit point.
+ */
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry(cset, &tset->src_csets, mg_node) {
+ list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) {
+ struct css_set *from_cset = task_css_set(task);
+ struct css_set *to_cset = cset->mg_dst_cset;
+
+ get_css_set(to_cset);
+ to_cset->nr_tasks++;
+ css_set_move_task(task, from_cset, to_cset, true);
+ from_cset->nr_tasks--;
+ /*
+ * If the source or destination cgroup is frozen,
+ * the task might require to change its state.
+ */
+ cgroup_freezer_migrate_task(task, from_cset->dfl_cgrp,
+ to_cset->dfl_cgrp);
+ put_css_set_locked(from_cset);
+
+ }
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ /*
+ * Migration is committed, all target tasks are now on dst_csets.
+ * Nothing is sensitive to fork() after this point. Notify
+ * controllers that migration is complete.
+ */
+ tset->csets = &tset->dst_csets;
+
+ if (tset->nr_tasks) {
+ do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
+ if (ss->attach) {
+ tset->ssid = ssid;
+ ss->attach(tset);
+ }
+ } while_each_subsys_mask();
+ }
+
+ ret = 0;
+ goto out_release_tset;
+
+out_cancel_attach:
+ if (tset->nr_tasks) {
+ do_each_subsys_mask(ss, ssid, mgctx->ss_mask) {
+ if (ssid == failed_ssid)
+ break;
+ if (ss->cancel_attach) {
+ tset->ssid = ssid;
+ ss->cancel_attach(tset);
+ }
+ } while_each_subsys_mask();
+ }
+out_release_tset:
+ spin_lock_irq(&css_set_lock);
+ list_splice_init(&tset->dst_csets, &tset->src_csets);
+ list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) {
+ list_splice_tail_init(&cset->mg_tasks, &cset->tasks);
+ list_del_init(&cset->mg_node);
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ /*
+ * Re-initialize the cgroup_taskset structure in case it is reused
+ * again in another cgroup_migrate_add_task()/cgroup_migrate_execute()
+ * iteration.
+ */
+ tset->nr_tasks = 0;
+ tset->csets = &tset->src_csets;
+ return ret;
+}
+
+/**
+ * cgroup_migrate_vet_dst - verify whether a cgroup can be migration destination
+ * @dst_cgrp: destination cgroup to test
+ *
+ * On the default hierarchy, except for the mixable, (possible) thread root
+ * and threaded cgroups, subtree_control must be zero for migration
+ * destination cgroups with tasks so that child cgroups don't compete
+ * against tasks.
+ */
+int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp)
+{
+ /* v1 doesn't have any restriction */
+ if (!cgroup_on_dfl(dst_cgrp))
+ return 0;
+
+ /* verify @dst_cgrp can host resources */
+ if (!cgroup_is_valid_domain(dst_cgrp->dom_cgrp))
+ return -EOPNOTSUPP;
+
+ /*
+ * If @dst_cgrp is already or can become a thread root or is
+ * threaded, it doesn't matter.
+ */
+ if (cgroup_can_be_thread_root(dst_cgrp) || cgroup_is_threaded(dst_cgrp))
+ return 0;
+
+ /* apply no-internal-process constraint */
+ if (dst_cgrp->subtree_control)
+ return -EBUSY;
+
+ return 0;
+}
+
+/**
+ * cgroup_migrate_finish - cleanup after attach
+ * @mgctx: migration context
+ *
+ * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
+ * those functions for details.
+ */
+void cgroup_migrate_finish(struct cgroup_mgctx *mgctx)
+{
+ struct css_set *cset, *tmp_cset;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ spin_lock_irq(&css_set_lock);
+
+ list_for_each_entry_safe(cset, tmp_cset, &mgctx->preloaded_src_csets,
+ mg_src_preload_node) {
+ cset->mg_src_cgrp = NULL;
+ cset->mg_dst_cgrp = NULL;
+ cset->mg_dst_cset = NULL;
+ list_del_init(&cset->mg_src_preload_node);
+ put_css_set_locked(cset);
+ }
+
+ list_for_each_entry_safe(cset, tmp_cset, &mgctx->preloaded_dst_csets,
+ mg_dst_preload_node) {
+ cset->mg_src_cgrp = NULL;
+ cset->mg_dst_cgrp = NULL;
+ cset->mg_dst_cset = NULL;
+ list_del_init(&cset->mg_dst_preload_node);
+ put_css_set_locked(cset);
+ }
+
+ spin_unlock_irq(&css_set_lock);
+}
+
+/**
+ * cgroup_migrate_add_src - add a migration source css_set
+ * @src_cset: the source css_set to add
+ * @dst_cgrp: the destination cgroup
+ * @mgctx: migration context
+ *
+ * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
+ * @src_cset and add it to @mgctx->src_csets, which should later be cleaned
+ * up by cgroup_migrate_finish().
+ *
+ * This function may be called without holding cgroup_threadgroup_rwsem
+ * even if the target is a process. Threads may be created and destroyed
+ * but as long as cgroup_mutex is not dropped, no new css_set can be put
+ * into play and the preloaded css_sets are guaranteed to cover all
+ * migrations.
+ */
+void cgroup_migrate_add_src(struct css_set *src_cset,
+ struct cgroup *dst_cgrp,
+ struct cgroup_mgctx *mgctx)
+{
+ struct cgroup *src_cgrp;
+
+ lockdep_assert_held(&cgroup_mutex);
+ lockdep_assert_held(&css_set_lock);
+
+ /*
+ * If ->dead, @src_set is associated with one or more dead cgroups
+ * and doesn't contain any migratable tasks. Ignore it early so
+ * that the rest of migration path doesn't get confused by it.
+ */
+ if (src_cset->dead)
+ return;
+
+ if (!list_empty(&src_cset->mg_src_preload_node))
+ return;
+
+ src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
+
+ WARN_ON(src_cset->mg_src_cgrp);
+ WARN_ON(src_cset->mg_dst_cgrp);
+ WARN_ON(!list_empty(&src_cset->mg_tasks));
+ WARN_ON(!list_empty(&src_cset->mg_node));
+
+ src_cset->mg_src_cgrp = src_cgrp;
+ src_cset->mg_dst_cgrp = dst_cgrp;
+ get_css_set(src_cset);
+ list_add_tail(&src_cset->mg_src_preload_node, &mgctx->preloaded_src_csets);
+}
+
+/**
+ * cgroup_migrate_prepare_dst - prepare destination css_sets for migration
+ * @mgctx: migration context
+ *
+ * Tasks are about to be moved and all the source css_sets have been
+ * preloaded to @mgctx->preloaded_src_csets. This function looks up and
+ * pins all destination css_sets, links each to its source, and append them
+ * to @mgctx->preloaded_dst_csets.
+ *
+ * This function must be called after cgroup_migrate_add_src() has been
+ * called on each migration source css_set. After migration is performed
+ * using cgroup_migrate(), cgroup_migrate_finish() must be called on
+ * @mgctx.
+ */
+int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx)
+{
+ struct css_set *src_cset, *tmp_cset;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* look up the dst cset for each src cset and link it to src */
+ list_for_each_entry_safe(src_cset, tmp_cset, &mgctx->preloaded_src_csets,
+ mg_src_preload_node) {
+ struct css_set *dst_cset;
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ dst_cset = find_css_set(src_cset, src_cset->mg_dst_cgrp);
+ if (!dst_cset)
+ return -ENOMEM;
+
+ WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset);
+
+ /*
+ * If src cset equals dst, it's noop. Drop the src.
+ * cgroup_migrate() will skip the cset too. Note that we
+ * can't handle src == dst as some nodes are used by both.
+ */
+ if (src_cset == dst_cset) {
+ src_cset->mg_src_cgrp = NULL;
+ src_cset->mg_dst_cgrp = NULL;
+ list_del_init(&src_cset->mg_src_preload_node);
+ put_css_set(src_cset);
+ put_css_set(dst_cset);
+ continue;
+ }
+
+ src_cset->mg_dst_cset = dst_cset;
+
+ if (list_empty(&dst_cset->mg_dst_preload_node))
+ list_add_tail(&dst_cset->mg_dst_preload_node,
+ &mgctx->preloaded_dst_csets);
+ else
+ put_css_set(dst_cset);
+
+ for_each_subsys(ss, ssid)
+ if (src_cset->subsys[ssid] != dst_cset->subsys[ssid])
+ mgctx->ss_mask |= 1 << ssid;
+ }
+
+ return 0;
+}
+
+/**
+ * cgroup_migrate - migrate a process or task to a cgroup
+ * @leader: the leader of the process or the task to migrate
+ * @threadgroup: whether @leader points to the whole process or a single task
+ * @mgctx: migration context
+ *
+ * Migrate a process or task denoted by @leader. If migrating a process,
+ * the caller must be holding cgroup_threadgroup_rwsem. The caller is also
+ * responsible for invoking cgroup_migrate_add_src() and
+ * cgroup_migrate_prepare_dst() on the targets before invoking this
+ * function and following up with cgroup_migrate_finish().
+ *
+ * As long as a controller's ->can_attach() doesn't fail, this function is
+ * guaranteed to succeed. This means that, excluding ->can_attach()
+ * failure, when migrating multiple targets, the success or failure can be
+ * decided for all targets by invoking group_migrate_prepare_dst() before
+ * actually starting migrating.
+ */
+int cgroup_migrate(struct task_struct *leader, bool threadgroup,
+ struct cgroup_mgctx *mgctx)
+{
+ struct task_struct *task;
+
+ /*
+ * The following thread iteration should be inside an RCU critical
+ * section to prevent tasks from being freed while taking the snapshot.
+ * spin_lock_irq() implies RCU critical section here.
+ */
+ spin_lock_irq(&css_set_lock);
+ task = leader;
+ do {
+ cgroup_migrate_add_task(task, mgctx);
+ if (!threadgroup)
+ break;
+ } while_each_thread(leader, task);
+ spin_unlock_irq(&css_set_lock);
+
+ return cgroup_migrate_execute(mgctx);
+}
+
+/**
+ * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
+ * @dst_cgrp: the cgroup to attach to
+ * @leader: the task or the leader of the threadgroup to be attached
+ * @threadgroup: attach the whole threadgroup?
+ *
+ * Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
+ */
+int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
+ bool threadgroup)
+{
+ DEFINE_CGROUP_MGCTX(mgctx);
+ struct task_struct *task;
+ int ret = 0;
+
+ /* look up all src csets */
+ spin_lock_irq(&css_set_lock);
+ rcu_read_lock();
+ task = leader;
+ do {
+ cgroup_migrate_add_src(task_css_set(task), dst_cgrp, &mgctx);
+ if (!threadgroup)
+ break;
+ } while_each_thread(leader, task);
+ rcu_read_unlock();
+ spin_unlock_irq(&css_set_lock);
+
+ /* prepare dst csets and commit */
+ ret = cgroup_migrate_prepare_dst(&mgctx);
+ if (!ret)
+ ret = cgroup_migrate(leader, threadgroup, &mgctx);
+
+ cgroup_migrate_finish(&mgctx);
+
+ if (!ret)
+ TRACE_CGROUP_PATH(attach_task, dst_cgrp, leader, threadgroup);
+
+ return ret;
+}
+
+struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup,
+ bool *threadgroup_locked)
+{
+ struct task_struct *tsk;
+ pid_t pid;
+
+ if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
+ return ERR_PTR(-EINVAL);
+
+ /*
+ * If we migrate a single thread, we don't care about threadgroup
+ * stability. If the thread is `current`, it won't exit(2) under our
+ * hands or change PID through exec(2). We exclude
+ * cgroup_update_dfl_csses and other cgroup_{proc,thread}s_write
+ * callers by cgroup_mutex.
+ * Therefore, we can skip the global lock.
+ */
+ lockdep_assert_held(&cgroup_mutex);
+ *threadgroup_locked = pid || threadgroup;
+ cgroup_attach_lock(*threadgroup_locked);
+
+ rcu_read_lock();
+ if (pid) {
+ tsk = find_task_by_vpid(pid);
+ if (!tsk) {
+ tsk = ERR_PTR(-ESRCH);
+ goto out_unlock_threadgroup;
+ }
+ } else {
+ tsk = current;
+ }
+
+ if (threadgroup)
+ tsk = tsk->group_leader;
+
+ /*
+ * kthreads may acquire PF_NO_SETAFFINITY during initialization.
+ * If userland migrates such a kthread to a non-root cgroup, it can
+ * become trapped in a cpuset, or RT kthread may be born in a
+ * cgroup with no rt_runtime allocated. Just say no.
+ */
+ if (tsk->no_cgroup_migration || (tsk->flags & PF_NO_SETAFFINITY)) {
+ tsk = ERR_PTR(-EINVAL);
+ goto out_unlock_threadgroup;
+ }
+
+ get_task_struct(tsk);
+ goto out_unlock_rcu;
+
+out_unlock_threadgroup:
+ cgroup_attach_unlock(*threadgroup_locked);
+ *threadgroup_locked = false;
+out_unlock_rcu:
+ rcu_read_unlock();
+ return tsk;
+}
+
+void cgroup_procs_write_finish(struct task_struct *task, bool threadgroup_locked)
+{
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ /* release reference from cgroup_procs_write_start() */
+ put_task_struct(task);
+
+ cgroup_attach_unlock(threadgroup_locked);
+
+ for_each_subsys(ss, ssid)
+ if (ss->post_attach)
+ ss->post_attach();
+}
+
+static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask)
+{
+ struct cgroup_subsys *ss;
+ bool printed = false;
+ int ssid;
+
+ do_each_subsys_mask(ss, ssid, ss_mask) {
+ if (printed)
+ seq_putc(seq, ' ');
+ seq_puts(seq, ss->name);
+ printed = true;
+ } while_each_subsys_mask();
+ if (printed)
+ seq_putc(seq, '\n');
+}
+
+/* show controllers which are enabled from the parent */
+static int cgroup_controllers_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+ cgroup_print_ss_mask(seq, cgroup_control(cgrp));
+ return 0;
+}
+
+/* show controllers which are enabled for a given cgroup's children */
+static int cgroup_subtree_control_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+ cgroup_print_ss_mask(seq, cgrp->subtree_control);
+ return 0;
+}
+
+/**
+ * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy
+ * @cgrp: root of the subtree to update csses for
+ *
+ * @cgrp's control masks have changed and its subtree's css associations
+ * need to be updated accordingly. This function looks up all css_sets
+ * which are attached to the subtree, creates the matching updated css_sets
+ * and migrates the tasks to the new ones.
+ */
+static int cgroup_update_dfl_csses(struct cgroup *cgrp)
+{
+ DEFINE_CGROUP_MGCTX(mgctx);
+ struct cgroup_subsys_state *d_css;
+ struct cgroup *dsct;
+ struct css_set *src_cset;
+ bool has_tasks;
+ int ret;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* look up all csses currently attached to @cgrp's subtree */
+ spin_lock_irq(&css_set_lock);
+ cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
+ struct cgrp_cset_link *link;
+
+ /*
+ * As cgroup_update_dfl_csses() is only called by
+ * cgroup_apply_control(). The csses associated with the
+ * given cgrp will not be affected by changes made to
+ * its subtree_control file. We can skip them.
+ */
+ if (dsct == cgrp)
+ continue;
+
+ list_for_each_entry(link, &dsct->cset_links, cset_link)
+ cgroup_migrate_add_src(link->cset, dsct, &mgctx);
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ /*
+ * We need to write-lock threadgroup_rwsem while migrating tasks.
+ * However, if there are no source csets for @cgrp, changing its
+ * controllers isn't gonna produce any task migrations and the
+ * write-locking can be skipped safely.
+ */
+ has_tasks = !list_empty(&mgctx.preloaded_src_csets);
+ cgroup_attach_lock(has_tasks);
+
+ /* NULL dst indicates self on default hierarchy */
+ ret = cgroup_migrate_prepare_dst(&mgctx);
+ if (ret)
+ goto out_finish;
+
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry(src_cset, &mgctx.preloaded_src_csets,
+ mg_src_preload_node) {
+ struct task_struct *task, *ntask;
+
+ /* all tasks in src_csets need to be migrated */
+ list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list)
+ cgroup_migrate_add_task(task, &mgctx);
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ ret = cgroup_migrate_execute(&mgctx);
+out_finish:
+ cgroup_migrate_finish(&mgctx);
+ cgroup_attach_unlock(has_tasks);
+ return ret;
+}
+
+/**
+ * cgroup_lock_and_drain_offline - lock cgroup_mutex and drain offlined csses
+ * @cgrp: root of the target subtree
+ *
+ * Because css offlining is asynchronous, userland may try to re-enable a
+ * controller while the previous css is still around. This function grabs
+ * cgroup_mutex and drains the previous css instances of @cgrp's subtree.
+ */
+void cgroup_lock_and_drain_offline(struct cgroup *cgrp)
+ __acquires(&cgroup_mutex)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+ struct cgroup_subsys *ss;
+ int ssid;
+
+restart:
+ cgroup_lock();
+
+ cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
+ for_each_subsys(ss, ssid) {
+ struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
+ DEFINE_WAIT(wait);
+
+ if (!css || !percpu_ref_is_dying(&css->refcnt))
+ continue;
+
+ cgroup_get_live(dsct);
+ prepare_to_wait(&dsct->offline_waitq, &wait,
+ TASK_UNINTERRUPTIBLE);
+
+ cgroup_unlock();
+ schedule();
+ finish_wait(&dsct->offline_waitq, &wait);
+
+ cgroup_put(dsct);
+ goto restart;
+ }
+ }
+}
+
+/**
+ * cgroup_save_control - save control masks and dom_cgrp of a subtree
+ * @cgrp: root of the target subtree
+ *
+ * Save ->subtree_control, ->subtree_ss_mask and ->dom_cgrp to the
+ * respective old_ prefixed fields for @cgrp's subtree including @cgrp
+ * itself.
+ */
+static void cgroup_save_control(struct cgroup *cgrp)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+
+ cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
+ dsct->old_subtree_control = dsct->subtree_control;
+ dsct->old_subtree_ss_mask = dsct->subtree_ss_mask;
+ dsct->old_dom_cgrp = dsct->dom_cgrp;
+ }
+}
+
+/**
+ * cgroup_propagate_control - refresh control masks of a subtree
+ * @cgrp: root of the target subtree
+ *
+ * For @cgrp and its subtree, ensure ->subtree_ss_mask matches
+ * ->subtree_control and propagate controller availability through the
+ * subtree so that descendants don't have unavailable controllers enabled.
+ */
+static void cgroup_propagate_control(struct cgroup *cgrp)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+
+ cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
+ dsct->subtree_control &= cgroup_control(dsct);
+ dsct->subtree_ss_mask =
+ cgroup_calc_subtree_ss_mask(dsct->subtree_control,
+ cgroup_ss_mask(dsct));
+ }
+}
+
+/**
+ * cgroup_restore_control - restore control masks and dom_cgrp of a subtree
+ * @cgrp: root of the target subtree
+ *
+ * Restore ->subtree_control, ->subtree_ss_mask and ->dom_cgrp from the
+ * respective old_ prefixed fields for @cgrp's subtree including @cgrp
+ * itself.
+ */
+static void cgroup_restore_control(struct cgroup *cgrp)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+
+ cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
+ dsct->subtree_control = dsct->old_subtree_control;
+ dsct->subtree_ss_mask = dsct->old_subtree_ss_mask;
+ dsct->dom_cgrp = dsct->old_dom_cgrp;
+ }
+}
+
+static bool css_visible(struct cgroup_subsys_state *css)
+{
+ struct cgroup_subsys *ss = css->ss;
+ struct cgroup *cgrp = css->cgroup;
+
+ if (cgroup_control(cgrp) & (1 << ss->id))
+ return true;
+ if (!(cgroup_ss_mask(cgrp) & (1 << ss->id)))
+ return false;
+ return cgroup_on_dfl(cgrp) && ss->implicit_on_dfl;
+}
+
+/**
+ * cgroup_apply_control_enable - enable or show csses according to control
+ * @cgrp: root of the target subtree
+ *
+ * Walk @cgrp's subtree and create new csses or make the existing ones
+ * visible. A css is created invisible if it's being implicitly enabled
+ * through dependency. An invisible css is made visible when the userland
+ * explicitly enables it.
+ *
+ * Returns 0 on success, -errno on failure. On failure, csses which have
+ * been processed already aren't cleaned up. The caller is responsible for
+ * cleaning up with cgroup_apply_control_disable().
+ */
+static int cgroup_apply_control_enable(struct cgroup *cgrp)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+ struct cgroup_subsys *ss;
+ int ssid, ret;
+
+ cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
+ for_each_subsys(ss, ssid) {
+ struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
+
+ if (!(cgroup_ss_mask(dsct) & (1 << ss->id)))
+ continue;
+
+ if (!css) {
+ css = css_create(dsct, ss);
+ if (IS_ERR(css))
+ return PTR_ERR(css);
+ }
+
+ WARN_ON_ONCE(percpu_ref_is_dying(&css->refcnt));
+
+ if (css_visible(css)) {
+ ret = css_populate_dir(css);
+ if (ret)
+ return ret;
+ }
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * cgroup_apply_control_disable - kill or hide csses according to control
+ * @cgrp: root of the target subtree
+ *
+ * Walk @cgrp's subtree and kill and hide csses so that they match
+ * cgroup_ss_mask() and cgroup_visible_mask().
+ *
+ * A css is hidden when the userland requests it to be disabled while other
+ * subsystems are still depending on it. The css must not actively control
+ * resources and be in the vanilla state if it's made visible again later.
+ * Controllers which may be depended upon should provide ->css_reset() for
+ * this purpose.
+ */
+static void cgroup_apply_control_disable(struct cgroup *cgrp)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
+ for_each_subsys(ss, ssid) {
+ struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
+
+ if (!css)
+ continue;
+
+ WARN_ON_ONCE(percpu_ref_is_dying(&css->refcnt));
+
+ if (css->parent &&
+ !(cgroup_ss_mask(dsct) & (1 << ss->id))) {
+ kill_css(css);
+ } else if (!css_visible(css)) {
+ css_clear_dir(css);
+ if (ss->css_reset)
+ ss->css_reset(css);
+ }
+ }
+ }
+}
+
+/**
+ * cgroup_apply_control - apply control mask updates to the subtree
+ * @cgrp: root of the target subtree
+ *
+ * subsystems can be enabled and disabled in a subtree using the following
+ * steps.
+ *
+ * 1. Call cgroup_save_control() to stash the current state.
+ * 2. Update ->subtree_control masks in the subtree as desired.
+ * 3. Call cgroup_apply_control() to apply the changes.
+ * 4. Optionally perform other related operations.
+ * 5. Call cgroup_finalize_control() to finish up.
+ *
+ * This function implements step 3 and propagates the mask changes
+ * throughout @cgrp's subtree, updates csses accordingly and perform
+ * process migrations.
+ */
+static int cgroup_apply_control(struct cgroup *cgrp)
+{
+ int ret;
+
+ cgroup_propagate_control(cgrp);
+
+ ret = cgroup_apply_control_enable(cgrp);
+ if (ret)
+ return ret;
+
+ /*
+ * At this point, cgroup_e_css_by_mask() results reflect the new csses
+ * making the following cgroup_update_dfl_csses() properly update
+ * css associations of all tasks in the subtree.
+ */
+ return cgroup_update_dfl_csses(cgrp);
+}
+
+/**
+ * cgroup_finalize_control - finalize control mask update
+ * @cgrp: root of the target subtree
+ * @ret: the result of the update
+ *
+ * Finalize control mask update. See cgroup_apply_control() for more info.
+ */
+static void cgroup_finalize_control(struct cgroup *cgrp, int ret)
+{
+ if (ret) {
+ cgroup_restore_control(cgrp);
+ cgroup_propagate_control(cgrp);
+ }
+
+ cgroup_apply_control_disable(cgrp);
+}
+
+static int cgroup_vet_subtree_control_enable(struct cgroup *cgrp, u16 enable)
+{
+ u16 domain_enable = enable & ~cgrp_dfl_threaded_ss_mask;
+
+ /* if nothing is getting enabled, nothing to worry about */
+ if (!enable)
+ return 0;
+
+ /* can @cgrp host any resources? */
+ if (!cgroup_is_valid_domain(cgrp->dom_cgrp))
+ return -EOPNOTSUPP;
+
+ /* mixables don't care */
+ if (cgroup_is_mixable(cgrp))
+ return 0;
+
+ if (domain_enable) {
+ /* can't enable domain controllers inside a thread subtree */
+ if (cgroup_is_thread_root(cgrp) || cgroup_is_threaded(cgrp))
+ return -EOPNOTSUPP;
+ } else {
+ /*
+ * Threaded controllers can handle internal competitions
+ * and are always allowed inside a (prospective) thread
+ * subtree.
+ */
+ if (cgroup_can_be_thread_root(cgrp) || cgroup_is_threaded(cgrp))
+ return 0;
+ }
+
+ /*
+ * Controllers can't be enabled for a cgroup with tasks to avoid
+ * child cgroups competing against tasks.
+ */
+ if (cgroup_has_tasks(cgrp))
+ return -EBUSY;
+
+ return 0;
+}
+
+/* change the enabled child controllers for a cgroup in the default hierarchy */
+static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ u16 enable = 0, disable = 0;
+ struct cgroup *cgrp, *child;
+ struct cgroup_subsys *ss;
+ char *tok;
+ int ssid, ret;
+
+ /*
+ * Parse input - space separated list of subsystem names prefixed
+ * with either + or -.
+ */
+ buf = strstrip(buf);
+ while ((tok = strsep(&buf, " "))) {
+ if (tok[0] == '\0')
+ continue;
+ do_each_subsys_mask(ss, ssid, ~cgrp_dfl_inhibit_ss_mask) {
+ if (!cgroup_ssid_enabled(ssid) ||
+ strcmp(tok + 1, ss->name))
+ continue;
+
+ if (*tok == '+') {
+ enable |= 1 << ssid;
+ disable &= ~(1 << ssid);
+ } else if (*tok == '-') {
+ disable |= 1 << ssid;
+ enable &= ~(1 << ssid);
+ } else {
+ return -EINVAL;
+ }
+ break;
+ } while_each_subsys_mask();
+ if (ssid == CGROUP_SUBSYS_COUNT)
+ return -EINVAL;
+ }
+
+ cgrp = cgroup_kn_lock_live(of->kn, true);
+ if (!cgrp)
+ return -ENODEV;
+
+ for_each_subsys(ss, ssid) {
+ if (enable & (1 << ssid)) {
+ if (cgrp->subtree_control & (1 << ssid)) {
+ enable &= ~(1 << ssid);
+ continue;
+ }
+
+ if (!(cgroup_control(cgrp) & (1 << ssid))) {
+ ret = -ENOENT;
+ goto out_unlock;
+ }
+ } else if (disable & (1 << ssid)) {
+ if (!(cgrp->subtree_control & (1 << ssid))) {
+ disable &= ~(1 << ssid);
+ continue;
+ }
+
+ /* a child has it enabled? */
+ cgroup_for_each_live_child(child, cgrp) {
+ if (child->subtree_control & (1 << ssid)) {
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+ }
+ }
+ }
+
+ if (!enable && !disable) {
+ ret = 0;
+ goto out_unlock;
+ }
+
+ ret = cgroup_vet_subtree_control_enable(cgrp, enable);
+ if (ret)
+ goto out_unlock;
+
+ /* save and update control masks and prepare csses */
+ cgroup_save_control(cgrp);
+
+ cgrp->subtree_control |= enable;
+ cgrp->subtree_control &= ~disable;
+
+ ret = cgroup_apply_control(cgrp);
+ cgroup_finalize_control(cgrp, ret);
+ if (ret)
+ goto out_unlock;
+
+ kernfs_activate(cgrp->kn);
+out_unlock:
+ cgroup_kn_unlock(of->kn);
+ return ret ?: nbytes;
+}
+
+/**
+ * cgroup_enable_threaded - make @cgrp threaded
+ * @cgrp: the target cgroup
+ *
+ * Called when "threaded" is written to the cgroup.type interface file and
+ * tries to make @cgrp threaded and join the parent's resource domain.
+ * This function is never called on the root cgroup as cgroup.type doesn't
+ * exist on it.
+ */
+static int cgroup_enable_threaded(struct cgroup *cgrp)
+{
+ struct cgroup *parent = cgroup_parent(cgrp);
+ struct cgroup *dom_cgrp = parent->dom_cgrp;
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+ int ret;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* noop if already threaded */
+ if (cgroup_is_threaded(cgrp))
+ return 0;
+
+ /*
+ * If @cgroup is populated or has domain controllers enabled, it
+ * can't be switched. While the below cgroup_can_be_thread_root()
+ * test can catch the same conditions, that's only when @parent is
+ * not mixable, so let's check it explicitly.
+ */
+ if (cgroup_is_populated(cgrp) ||
+ cgrp->subtree_control & ~cgrp_dfl_threaded_ss_mask)
+ return -EOPNOTSUPP;
+
+ /* we're joining the parent's domain, ensure its validity */
+ if (!cgroup_is_valid_domain(dom_cgrp) ||
+ !cgroup_can_be_thread_root(dom_cgrp))
+ return -EOPNOTSUPP;
+
+ /*
+ * The following shouldn't cause actual migrations and should
+ * always succeed.
+ */
+ cgroup_save_control(cgrp);
+
+ cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp)
+ if (dsct == cgrp || cgroup_is_threaded(dsct))
+ dsct->dom_cgrp = dom_cgrp;
+
+ ret = cgroup_apply_control(cgrp);
+ if (!ret)
+ parent->nr_threaded_children++;
+
+ cgroup_finalize_control(cgrp, ret);
+ return ret;
+}
+
+static int cgroup_type_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+ if (cgroup_is_threaded(cgrp))
+ seq_puts(seq, "threaded\n");
+ else if (!cgroup_is_valid_domain(cgrp))
+ seq_puts(seq, "domain invalid\n");
+ else if (cgroup_is_thread_root(cgrp))
+ seq_puts(seq, "domain threaded\n");
+ else
+ seq_puts(seq, "domain\n");
+
+ return 0;
+}
+
+static ssize_t cgroup_type_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct cgroup *cgrp;
+ int ret;
+
+ /* only switching to threaded mode is supported */
+ if (strcmp(strstrip(buf), "threaded"))
+ return -EINVAL;
+
+ /* drain dying csses before we re-apply (threaded) subtree control */
+ cgrp = cgroup_kn_lock_live(of->kn, true);
+ if (!cgrp)
+ return -ENOENT;
+
+ /* threaded can only be enabled */
+ ret = cgroup_enable_threaded(cgrp);
+
+ cgroup_kn_unlock(of->kn);
+ return ret ?: nbytes;
+}
+
+static int cgroup_max_descendants_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+ int descendants = READ_ONCE(cgrp->max_descendants);
+
+ if (descendants == INT_MAX)
+ seq_puts(seq, "max\n");
+ else
+ seq_printf(seq, "%d\n", descendants);
+
+ return 0;
+}
+
+static ssize_t cgroup_max_descendants_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cgroup *cgrp;
+ int descendants;
+ ssize_t ret;
+
+ buf = strstrip(buf);
+ if (!strcmp(buf, "max")) {
+ descendants = INT_MAX;
+ } else {
+ ret = kstrtoint(buf, 0, &descendants);
+ if (ret)
+ return ret;
+ }
+
+ if (descendants < 0)
+ return -ERANGE;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENOENT;
+
+ cgrp->max_descendants = descendants;
+
+ cgroup_kn_unlock(of->kn);
+
+ return nbytes;
+}
+
+static int cgroup_max_depth_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+ int depth = READ_ONCE(cgrp->max_depth);
+
+ if (depth == INT_MAX)
+ seq_puts(seq, "max\n");
+ else
+ seq_printf(seq, "%d\n", depth);
+
+ return 0;
+}
+
+static ssize_t cgroup_max_depth_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cgroup *cgrp;
+ ssize_t ret;
+ int depth;
+
+ buf = strstrip(buf);
+ if (!strcmp(buf, "max")) {
+ depth = INT_MAX;
+ } else {
+ ret = kstrtoint(buf, 0, &depth);
+ if (ret)
+ return ret;
+ }
+
+ if (depth < 0)
+ return -ERANGE;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENOENT;
+
+ cgrp->max_depth = depth;
+
+ cgroup_kn_unlock(of->kn);
+
+ return nbytes;
+}
+
+static int cgroup_events_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+ seq_printf(seq, "populated %d\n", cgroup_is_populated(cgrp));
+ seq_printf(seq, "frozen %d\n", test_bit(CGRP_FROZEN, &cgrp->flags));
+
+ return 0;
+}
+
+static int cgroup_stat_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgroup = seq_css(seq)->cgroup;
+
+ seq_printf(seq, "nr_descendants %d\n",
+ cgroup->nr_descendants);
+ seq_printf(seq, "nr_dying_descendants %d\n",
+ cgroup->nr_dying_descendants);
+
+ return 0;
+}
+
+#ifdef CONFIG_CGROUP_SCHED
+/**
+ * cgroup_tryget_css - try to get a cgroup's css for the specified subsystem
+ * @cgrp: the cgroup of interest
+ * @ss: the subsystem of interest
+ *
+ * Find and get @cgrp's css associated with @ss. If the css doesn't exist
+ * or is offline, %NULL is returned.
+ */
+static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
+{
+ struct cgroup_subsys_state *css;
+
+ rcu_read_lock();
+ css = cgroup_css(cgrp, ss);
+ if (css && !css_tryget_online(css))
+ css = NULL;
+ rcu_read_unlock();
+
+ return css;
+}
+
+static int cgroup_extra_stat_show(struct seq_file *seq, int ssid)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+ struct cgroup_subsys *ss = cgroup_subsys[ssid];
+ struct cgroup_subsys_state *css;
+ int ret;
+
+ if (!ss->css_extra_stat_show)
+ return 0;
+
+ css = cgroup_tryget_css(cgrp, ss);
+ if (!css)
+ return 0;
+
+ ret = ss->css_extra_stat_show(seq, css);
+ css_put(css);
+ return ret;
+}
+
+static int cgroup_local_stat_show(struct seq_file *seq,
+ struct cgroup *cgrp, int ssid)
+{
+ struct cgroup_subsys *ss = cgroup_subsys[ssid];
+ struct cgroup_subsys_state *css;
+ int ret;
+
+ if (!ss->css_local_stat_show)
+ return 0;
+
+ css = cgroup_tryget_css(cgrp, ss);
+ if (!css)
+ return 0;
+
+ ret = ss->css_local_stat_show(seq, css);
+ css_put(css);
+ return ret;
+}
+#endif
+
+static int cpu_stat_show(struct seq_file *seq, void *v)
+{
+ int ret = 0;
+
+ cgroup_base_stat_cputime_show(seq);
+#ifdef CONFIG_CGROUP_SCHED
+ ret = cgroup_extra_stat_show(seq, cpu_cgrp_id);
+#endif
+ return ret;
+}
+
+static int cpu_local_stat_show(struct seq_file *seq, void *v)
+{
+ struct cgroup __maybe_unused *cgrp = seq_css(seq)->cgroup;
+ int ret = 0;
+
+#ifdef CONFIG_CGROUP_SCHED
+ ret = cgroup_local_stat_show(seq, cgrp, cpu_cgrp_id);
+#endif
+ return ret;
+}
+
+#ifdef CONFIG_PSI
+static int cgroup_io_pressure_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+ struct psi_group *psi = cgroup_psi(cgrp);
+
+ return psi_show(seq, psi, PSI_IO);
+}
+static int cgroup_memory_pressure_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+ struct psi_group *psi = cgroup_psi(cgrp);
+
+ return psi_show(seq, psi, PSI_MEM);
+}
+static int cgroup_cpu_pressure_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+ struct psi_group *psi = cgroup_psi(cgrp);
+
+ return psi_show(seq, psi, PSI_CPU);
+}
+
+static ssize_t pressure_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, enum psi_res res)
+{
+ struct cgroup_file_ctx *ctx = of->priv;
+ struct psi_trigger *new;
+ struct cgroup *cgrp;
+ struct psi_group *psi;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENODEV;
+
+ cgroup_get(cgrp);
+ cgroup_kn_unlock(of->kn);
+
+ /* Allow only one trigger per file descriptor */
+ if (ctx->psi.trigger) {
+ cgroup_put(cgrp);
+ return -EBUSY;
+ }
+
+ psi = cgroup_psi(cgrp);
+ new = psi_trigger_create(psi, buf, res, of->file, of);
+ if (IS_ERR(new)) {
+ cgroup_put(cgrp);
+ return PTR_ERR(new);
+ }
+
+ smp_store_release(&ctx->psi.trigger, new);
+ cgroup_put(cgrp);
+
+ return nbytes;
+}
+
+static ssize_t cgroup_io_pressure_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ return pressure_write(of, buf, nbytes, PSI_IO);
+}
+
+static ssize_t cgroup_memory_pressure_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ return pressure_write(of, buf, nbytes, PSI_MEM);
+}
+
+static ssize_t cgroup_cpu_pressure_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ return pressure_write(of, buf, nbytes, PSI_CPU);
+}
+
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+static int cgroup_irq_pressure_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+ struct psi_group *psi = cgroup_psi(cgrp);
+
+ return psi_show(seq, psi, PSI_IRQ);
+}
+
+static ssize_t cgroup_irq_pressure_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ return pressure_write(of, buf, nbytes, PSI_IRQ);
+}
+#endif
+
+static int cgroup_pressure_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+ struct psi_group *psi = cgroup_psi(cgrp);
+
+ seq_printf(seq, "%d\n", psi->enabled);
+
+ return 0;
+}
+
+static ssize_t cgroup_pressure_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ ssize_t ret;
+ int enable;
+ struct cgroup *cgrp;
+ struct psi_group *psi;
+
+ ret = kstrtoint(strstrip(buf), 0, &enable);
+ if (ret)
+ return ret;
+
+ if (enable < 0 || enable > 1)
+ return -ERANGE;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENOENT;
+
+ psi = cgroup_psi(cgrp);
+ if (psi->enabled != enable) {
+ int i;
+
+ /* show or hide {cpu,memory,io,irq}.pressure files */
+ for (i = 0; i < NR_PSI_RESOURCES; i++)
+ cgroup_file_show(&cgrp->psi_files[i], enable);
+
+ psi->enabled = enable;
+ if (enable)
+ psi_cgroup_restart(psi);
+ }
+
+ cgroup_kn_unlock(of->kn);
+
+ return nbytes;
+}
+
+static __poll_t cgroup_pressure_poll(struct kernfs_open_file *of,
+ poll_table *pt)
+{
+ struct cgroup_file_ctx *ctx = of->priv;
+
+ return psi_trigger_poll(&ctx->psi.trigger, of->file, pt);
+}
+
+static void cgroup_pressure_release(struct kernfs_open_file *of)
+{
+ struct cgroup_file_ctx *ctx = of->priv;
+
+ psi_trigger_destroy(ctx->psi.trigger);
+}
+
+bool cgroup_psi_enabled(void)
+{
+ if (static_branch_likely(&psi_disabled))
+ return false;
+
+ return (cgroup_feature_disable_mask & (1 << OPT_FEATURE_PRESSURE)) == 0;
+}
+
+#else /* CONFIG_PSI */
+bool cgroup_psi_enabled(void)
+{
+ return false;
+}
+
+#endif /* CONFIG_PSI */
+
+static int cgroup_freeze_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+ seq_printf(seq, "%d\n", cgrp->freezer.freeze);
+
+ return 0;
+}
+
+static ssize_t cgroup_freeze_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cgroup *cgrp;
+ ssize_t ret;
+ int freeze;
+
+ ret = kstrtoint(strstrip(buf), 0, &freeze);
+ if (ret)
+ return ret;
+
+ if (freeze < 0 || freeze > 1)
+ return -ERANGE;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENOENT;
+
+ cgroup_freeze(cgrp, freeze);
+
+ cgroup_kn_unlock(of->kn);
+
+ return nbytes;
+}
+
+static void __cgroup_kill(struct cgroup *cgrp)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ spin_lock_irq(&css_set_lock);
+ set_bit(CGRP_KILL, &cgrp->flags);
+ spin_unlock_irq(&css_set_lock);
+
+ css_task_iter_start(&cgrp->self, CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED, &it);
+ while ((task = css_task_iter_next(&it))) {
+ /* Ignore kernel threads here. */
+ if (task->flags & PF_KTHREAD)
+ continue;
+
+ /* Skip tasks that are already dying. */
+ if (__fatal_signal_pending(task))
+ continue;
+
+ send_sig(SIGKILL, task, 0);
+ }
+ css_task_iter_end(&it);
+
+ spin_lock_irq(&css_set_lock);
+ clear_bit(CGRP_KILL, &cgrp->flags);
+ spin_unlock_irq(&css_set_lock);
+}
+
+static void cgroup_kill(struct cgroup *cgrp)
+{
+ struct cgroup_subsys_state *css;
+ struct cgroup *dsct;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ cgroup_for_each_live_descendant_pre(dsct, css, cgrp)
+ __cgroup_kill(dsct);
+}
+
+static ssize_t cgroup_kill_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ ssize_t ret = 0;
+ int kill;
+ struct cgroup *cgrp;
+
+ ret = kstrtoint(strstrip(buf), 0, &kill);
+ if (ret)
+ return ret;
+
+ if (kill != 1)
+ return -ERANGE;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENOENT;
+
+ /*
+ * Killing is a process directed operation, i.e. the whole thread-group
+ * is taken down so act like we do for cgroup.procs and only make this
+ * writable in non-threaded cgroups.
+ */
+ if (cgroup_is_threaded(cgrp))
+ ret = -EOPNOTSUPP;
+ else
+ cgroup_kill(cgrp);
+
+ cgroup_kn_unlock(of->kn);
+
+ return ret ?: nbytes;
+}
+
+static int cgroup_file_open(struct kernfs_open_file *of)
+{
+ struct cftype *cft = of_cft(of);
+ struct cgroup_file_ctx *ctx;
+ int ret;
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+
+ ctx->ns = current->nsproxy->cgroup_ns;
+ get_cgroup_ns(ctx->ns);
+ of->priv = ctx;
+
+ if (!cft->open)
+ return 0;
+
+ ret = cft->open(of);
+ if (ret) {
+ put_cgroup_ns(ctx->ns);
+ kfree(ctx);
+ }
+ return ret;
+}
+
+static void cgroup_file_release(struct kernfs_open_file *of)
+{
+ struct cftype *cft = of_cft(of);
+ struct cgroup_file_ctx *ctx = of->priv;
+
+ if (cft->release)
+ cft->release(of);
+ put_cgroup_ns(ctx->ns);
+ kfree(ctx);
+}
+
+static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct cgroup_file_ctx *ctx = of->priv;
+ struct cgroup *cgrp = of->kn->parent->priv;
+ struct cftype *cft = of_cft(of);
+ struct cgroup_subsys_state *css;
+ int ret;
+
+ if (!nbytes)
+ return 0;
+
+ /*
+ * If namespaces are delegation boundaries, disallow writes to
+ * files in an non-init namespace root from inside the namespace
+ * except for the files explicitly marked delegatable -
+ * cgroup.procs and cgroup.subtree_control.
+ */
+ if ((cgrp->root->flags & CGRP_ROOT_NS_DELEGATE) &&
+ !(cft->flags & CFTYPE_NS_DELEGATABLE) &&
+ ctx->ns != &init_cgroup_ns && ctx->ns->root_cset->dfl_cgrp == cgrp)
+ return -EPERM;
+
+ if (cft->write)
+ return cft->write(of, buf, nbytes, off);
+
+ /*
+ * kernfs guarantees that a file isn't deleted with operations in
+ * flight, which means that the matching css is and stays alive and
+ * doesn't need to be pinned. The RCU locking is not necessary
+ * either. It's just for the convenience of using cgroup_css().
+ */
+ rcu_read_lock();
+ css = cgroup_css(cgrp, cft->ss);
+ rcu_read_unlock();
+
+ if (cft->write_u64) {
+ unsigned long long v;
+ ret = kstrtoull(buf, 0, &v);
+ if (!ret)
+ ret = cft->write_u64(css, cft, v);
+ } else if (cft->write_s64) {
+ long long v;
+ ret = kstrtoll(buf, 0, &v);
+ if (!ret)
+ ret = cft->write_s64(css, cft, v);
+ } else {
+ ret = -EINVAL;
+ }
+
+ return ret ?: nbytes;
+}
+
+static __poll_t cgroup_file_poll(struct kernfs_open_file *of, poll_table *pt)
+{
+ struct cftype *cft = of_cft(of);
+
+ if (cft->poll)
+ return cft->poll(of, pt);
+
+ return kernfs_generic_poll(of, pt);
+}
+
+static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos)
+{
+ return seq_cft(seq)->seq_start(seq, ppos);
+}
+
+static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos)
+{
+ return seq_cft(seq)->seq_next(seq, v, ppos);
+}
+
+static void cgroup_seqfile_stop(struct seq_file *seq, void *v)
+{
+ if (seq_cft(seq)->seq_stop)
+ seq_cft(seq)->seq_stop(seq, v);
+}
+
+static int cgroup_seqfile_show(struct seq_file *m, void *arg)
+{
+ struct cftype *cft = seq_cft(m);
+ struct cgroup_subsys_state *css = seq_css(m);
+
+ if (cft->seq_show)
+ return cft->seq_show(m, arg);
+
+ if (cft->read_u64)
+ seq_printf(m, "%llu\n", cft->read_u64(css, cft));
+ else if (cft->read_s64)
+ seq_printf(m, "%lld\n", cft->read_s64(css, cft));
+ else
+ return -EINVAL;
+ return 0;
+}
+
+static struct kernfs_ops cgroup_kf_single_ops = {
+ .atomic_write_len = PAGE_SIZE,
+ .open = cgroup_file_open,
+ .release = cgroup_file_release,
+ .write = cgroup_file_write,
+ .poll = cgroup_file_poll,
+ .seq_show = cgroup_seqfile_show,
+};
+
+static struct kernfs_ops cgroup_kf_ops = {
+ .atomic_write_len = PAGE_SIZE,
+ .open = cgroup_file_open,
+ .release = cgroup_file_release,
+ .write = cgroup_file_write,
+ .poll = cgroup_file_poll,
+ .seq_start = cgroup_seqfile_start,
+ .seq_next = cgroup_seqfile_next,
+ .seq_stop = cgroup_seqfile_stop,
+ .seq_show = cgroup_seqfile_show,
+};
+
+/* set uid and gid of cgroup dirs and files to that of the creator */
+static int cgroup_kn_set_ugid(struct kernfs_node *kn)
+{
+ struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
+ .ia_uid = current_fsuid(),
+ .ia_gid = current_fsgid(), };
+
+ if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
+ gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
+ return 0;
+
+ return kernfs_setattr(kn, &iattr);
+}
+
+static void cgroup_file_notify_timer(struct timer_list *timer)
+{
+ cgroup_file_notify(container_of(timer, struct cgroup_file,
+ notify_timer));
+}
+
+static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
+ struct cftype *cft)
+{
+ char name[CGROUP_FILE_NAME_MAX];
+ struct kernfs_node *kn;
+ struct lock_class_key *key = NULL;
+ int ret;
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ key = &cft->lockdep_key;
+#endif
+ kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
+ cgroup_file_mode(cft),
+ GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
+ 0, cft->kf_ops, cft,
+ NULL, key);
+ if (IS_ERR(kn))
+ return PTR_ERR(kn);
+
+ ret = cgroup_kn_set_ugid(kn);
+ if (ret) {
+ kernfs_remove(kn);
+ return ret;
+ }
+
+ if (cft->file_offset) {
+ struct cgroup_file *cfile = (void *)css + cft->file_offset;
+
+ timer_setup(&cfile->notify_timer, cgroup_file_notify_timer, 0);
+
+ spin_lock_irq(&cgroup_file_kn_lock);
+ cfile->kn = kn;
+ spin_unlock_irq(&cgroup_file_kn_lock);
+ }
+
+ return 0;
+}
+
+/**
+ * cgroup_addrm_files - add or remove files to a cgroup directory
+ * @css: the target css
+ * @cgrp: the target cgroup (usually css->cgroup)
+ * @cfts: array of cftypes to be added
+ * @is_add: whether to add or remove
+ *
+ * Depending on @is_add, add or remove files defined by @cfts on @cgrp.
+ * For removals, this function never fails.
+ */
+static int cgroup_addrm_files(struct cgroup_subsys_state *css,
+ struct cgroup *cgrp, struct cftype cfts[],
+ bool is_add)
+{
+ struct cftype *cft, *cft_end = NULL;
+ int ret = 0;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+restart:
+ for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) {
+ /* does cft->flags tell us to skip this file on @cgrp? */
+ if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
+ continue;
+ if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp))
+ continue;
+ if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp))
+ continue;
+ if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp))
+ continue;
+ if ((cft->flags & CFTYPE_DEBUG) && !cgroup_debug)
+ continue;
+ if (is_add) {
+ ret = cgroup_add_file(css, cgrp, cft);
+ if (ret) {
+ pr_warn("%s: failed to add %s, err=%d\n",
+ __func__, cft->name, ret);
+ cft_end = cft;
+ is_add = false;
+ goto restart;
+ }
+ } else {
+ cgroup_rm_file(cgrp, cft);
+ }
+ }
+ return ret;
+}
+
+static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add)
+{
+ struct cgroup_subsys *ss = cfts[0].ss;
+ struct cgroup *root = &ss->root->cgrp;
+ struct cgroup_subsys_state *css;
+ int ret = 0;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* add/rm files for all cgroups created before */
+ css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
+ struct cgroup *cgrp = css->cgroup;
+
+ if (!(css->flags & CSS_VISIBLE))
+ continue;
+
+ ret = cgroup_addrm_files(css, cgrp, cfts, is_add);
+ if (ret)
+ break;
+ }
+
+ if (is_add && !ret)
+ kernfs_activate(root->kn);
+ return ret;
+}
+
+static void cgroup_exit_cftypes(struct cftype *cfts)
+{
+ struct cftype *cft;
+
+ for (cft = cfts; cft->name[0] != '\0'; cft++) {
+ /* free copy for custom atomic_write_len, see init_cftypes() */
+ if (cft->max_write_len && cft->max_write_len != PAGE_SIZE)
+ kfree(cft->kf_ops);
+ cft->kf_ops = NULL;
+ cft->ss = NULL;
+
+ /* revert flags set by cgroup core while adding @cfts */
+ cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL |
+ __CFTYPE_ADDED);
+ }
+}
+
+static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+{
+ struct cftype *cft;
+ int ret = 0;
+
+ for (cft = cfts; cft->name[0] != '\0'; cft++) {
+ struct kernfs_ops *kf_ops;
+
+ WARN_ON(cft->ss || cft->kf_ops);
+
+ if (cft->flags & __CFTYPE_ADDED) {
+ ret = -EBUSY;
+ break;
+ }
+
+ if (cft->seq_start)
+ kf_ops = &cgroup_kf_ops;
+ else
+ kf_ops = &cgroup_kf_single_ops;
+
+ /*
+ * Ugh... if @cft wants a custom max_write_len, we need to
+ * make a copy of kf_ops to set its atomic_write_len.
+ */
+ if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) {
+ kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL);
+ if (!kf_ops) {
+ ret = -ENOMEM;
+ break;
+ }
+ kf_ops->atomic_write_len = cft->max_write_len;
+ }
+
+ cft->kf_ops = kf_ops;
+ cft->ss = ss;
+ cft->flags |= __CFTYPE_ADDED;
+ }
+
+ if (ret)
+ cgroup_exit_cftypes(cfts);
+ return ret;
+}
+
+static void cgroup_rm_cftypes_locked(struct cftype *cfts)
+{
+ lockdep_assert_held(&cgroup_mutex);
+
+ list_del(&cfts->node);
+ cgroup_apply_cftypes(cfts, false);
+ cgroup_exit_cftypes(cfts);
+}
+
+/**
+ * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Unregister @cfts. Files described by @cfts are removed from all
+ * existing cgroups and all future cgroups won't have them either. This
+ * function can be called anytime whether @cfts' subsys is attached or not.
+ *
+ * Returns 0 on successful unregistration, -ENOENT if @cfts is not
+ * registered.
+ */
+int cgroup_rm_cftypes(struct cftype *cfts)
+{
+ if (!cfts || cfts[0].name[0] == '\0')
+ return 0;
+
+ if (!(cfts[0].flags & __CFTYPE_ADDED))
+ return -ENOENT;
+
+ cgroup_lock();
+ cgroup_rm_cftypes_locked(cfts);
+ cgroup_unlock();
+ return 0;
+}
+
+/**
+ * cgroup_add_cftypes - add an array of cftypes to a subsystem
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Register @cfts to @ss. Files described by @cfts are created for all
+ * existing cgroups to which @ss is attached and all future cgroups will
+ * have them too. This function can be called anytime whether @ss is
+ * attached or not.
+ *
+ * Returns 0 on successful registration, -errno on failure. Note that this
+ * function currently returns 0 as long as @cfts registration is successful
+ * even if some file creation attempts on existing cgroups fail.
+ */
+static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+{
+ int ret;
+
+ if (!cgroup_ssid_enabled(ss->id))
+ return 0;
+
+ if (!cfts || cfts[0].name[0] == '\0')
+ return 0;
+
+ ret = cgroup_init_cftypes(ss, cfts);
+ if (ret)
+ return ret;
+
+ cgroup_lock();
+
+ list_add_tail(&cfts->node, &ss->cfts);
+ ret = cgroup_apply_cftypes(cfts, true);
+ if (ret)
+ cgroup_rm_cftypes_locked(cfts);
+
+ cgroup_unlock();
+ return ret;
+}
+
+/**
+ * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Similar to cgroup_add_cftypes() but the added files are only used for
+ * the default hierarchy.
+ */
+int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+{
+ struct cftype *cft;
+
+ for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
+ cft->flags |= __CFTYPE_ONLY_ON_DFL;
+ return cgroup_add_cftypes(ss, cfts);
+}
+
+/**
+ * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Similar to cgroup_add_cftypes() but the added files are only used for
+ * the legacy hierarchies.
+ */
+int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+{
+ struct cftype *cft;
+
+ for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
+ cft->flags |= __CFTYPE_NOT_ON_DFL;
+ return cgroup_add_cftypes(ss, cfts);
+}
+
+/**
+ * cgroup_file_notify - generate a file modified event for a cgroup_file
+ * @cfile: target cgroup_file
+ *
+ * @cfile must have been obtained by setting cftype->file_offset.
+ */
+void cgroup_file_notify(struct cgroup_file *cfile)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&cgroup_file_kn_lock, flags);
+ if (cfile->kn) {
+ unsigned long last = cfile->notified_at;
+ unsigned long next = last + CGROUP_FILE_NOTIFY_MIN_INTV;
+
+ if (time_in_range(jiffies, last, next)) {
+ timer_reduce(&cfile->notify_timer, next);
+ } else {
+ kernfs_notify(cfile->kn);
+ cfile->notified_at = jiffies;
+ }
+ }
+ spin_unlock_irqrestore(&cgroup_file_kn_lock, flags);
+}
+
+/**
+ * cgroup_file_show - show or hide a hidden cgroup file
+ * @cfile: target cgroup_file obtained by setting cftype->file_offset
+ * @show: whether to show or hide
+ */
+void cgroup_file_show(struct cgroup_file *cfile, bool show)
+{
+ struct kernfs_node *kn;
+
+ spin_lock_irq(&cgroup_file_kn_lock);
+ kn = cfile->kn;
+ kernfs_get(kn);
+ spin_unlock_irq(&cgroup_file_kn_lock);
+
+ if (kn)
+ kernfs_show(kn, show);
+
+ kernfs_put(kn);
+}
+
+/**
+ * css_next_child - find the next child of a given css
+ * @pos: the current position (%NULL to initiate traversal)
+ * @parent: css whose children to walk
+ *
+ * This function returns the next child of @parent and should be called
+ * under either cgroup_mutex or RCU read lock. The only requirement is
+ * that @parent and @pos are accessible. The next sibling is guaranteed to
+ * be returned regardless of their states.
+ *
+ * If a subsystem synchronizes ->css_online() and the start of iteration, a
+ * css which finished ->css_online() is guaranteed to be visible in the
+ * future iterations and will stay visible until the last reference is put.
+ * A css which hasn't finished ->css_online() or already finished
+ * ->css_offline() may show up during traversal. It's each subsystem's
+ * responsibility to synchronize against on/offlining.
+ */
+struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
+ struct cgroup_subsys_state *parent)
+{
+ struct cgroup_subsys_state *next;
+
+ cgroup_assert_mutex_or_rcu_locked();
+
+ /*
+ * @pos could already have been unlinked from the sibling list.
+ * Once a cgroup is removed, its ->sibling.next is no longer
+ * updated when its next sibling changes. CSS_RELEASED is set when
+ * @pos is taken off list, at which time its next pointer is valid,
+ * and, as releases are serialized, the one pointed to by the next
+ * pointer is guaranteed to not have started release yet. This
+ * implies that if we observe !CSS_RELEASED on @pos in this RCU
+ * critical section, the one pointed to by its next pointer is
+ * guaranteed to not have finished its RCU grace period even if we
+ * have dropped rcu_read_lock() in-between iterations.
+ *
+ * If @pos has CSS_RELEASED set, its next pointer can't be
+ * dereferenced; however, as each css is given a monotonically
+ * increasing unique serial number and always appended to the
+ * sibling list, the next one can be found by walking the parent's
+ * children until the first css with higher serial number than
+ * @pos's. While this path can be slower, it happens iff iteration
+ * races against release and the race window is very small.
+ */
+ if (!pos) {
+ next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling);
+ } else if (likely(!(pos->flags & CSS_RELEASED))) {
+ next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling);
+ } else {
+ list_for_each_entry_rcu(next, &parent->children, sibling,
+ lockdep_is_held(&cgroup_mutex))
+ if (next->serial_nr > pos->serial_nr)
+ break;
+ }
+
+ /*
+ * @next, if not pointing to the head, can be dereferenced and is
+ * the next sibling.
+ */
+ if (&next->sibling != &parent->children)
+ return next;
+ return NULL;
+}
+
+/**
+ * css_next_descendant_pre - find the next descendant for pre-order walk
+ * @pos: the current position (%NULL to initiate traversal)
+ * @root: css whose descendants to walk
+ *
+ * To be used by css_for_each_descendant_pre(). Find the next descendant
+ * to visit for pre-order traversal of @root's descendants. @root is
+ * included in the iteration and the first node to be visited.
+ *
+ * While this function requires cgroup_mutex or RCU read locking, it
+ * doesn't require the whole traversal to be contained in a single critical
+ * section. This function will return the correct next descendant as long
+ * as both @pos and @root are accessible and @pos is a descendant of @root.
+ *
+ * If a subsystem synchronizes ->css_online() and the start of iteration, a
+ * css which finished ->css_online() is guaranteed to be visible in the
+ * future iterations and will stay visible until the last reference is put.
+ * A css which hasn't finished ->css_online() or already finished
+ * ->css_offline() may show up during traversal. It's each subsystem's
+ * responsibility to synchronize against on/offlining.
+ */
+struct cgroup_subsys_state *
+css_next_descendant_pre(struct cgroup_subsys_state *pos,
+ struct cgroup_subsys_state *root)
+{
+ struct cgroup_subsys_state *next;
+
+ cgroup_assert_mutex_or_rcu_locked();
+
+ /* if first iteration, visit @root */
+ if (!pos)
+ return root;
+
+ /* visit the first child if exists */
+ next = css_next_child(NULL, pos);
+ if (next)
+ return next;
+
+ /* no child, visit my or the closest ancestor's next sibling */
+ while (pos != root) {
+ next = css_next_child(pos, pos->parent);
+ if (next)
+ return next;
+ pos = pos->parent;
+ }
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(css_next_descendant_pre);
+
+/**
+ * css_rightmost_descendant - return the rightmost descendant of a css
+ * @pos: css of interest
+ *
+ * Return the rightmost descendant of @pos. If there's no descendant, @pos
+ * is returned. This can be used during pre-order traversal to skip
+ * subtree of @pos.
+ *
+ * While this function requires cgroup_mutex or RCU read locking, it
+ * doesn't require the whole traversal to be contained in a single critical
+ * section. This function will return the correct rightmost descendant as
+ * long as @pos is accessible.
+ */
+struct cgroup_subsys_state *
+css_rightmost_descendant(struct cgroup_subsys_state *pos)
+{
+ struct cgroup_subsys_state *last, *tmp;
+
+ cgroup_assert_mutex_or_rcu_locked();
+
+ do {
+ last = pos;
+ /* ->prev isn't RCU safe, walk ->next till the end */
+ pos = NULL;
+ css_for_each_child(tmp, last)
+ pos = tmp;
+ } while (pos);
+
+ return last;
+}
+
+static struct cgroup_subsys_state *
+css_leftmost_descendant(struct cgroup_subsys_state *pos)
+{
+ struct cgroup_subsys_state *last;
+
+ do {
+ last = pos;
+ pos = css_next_child(NULL, pos);
+ } while (pos);
+
+ return last;
+}
+
+/**
+ * css_next_descendant_post - find the next descendant for post-order walk
+ * @pos: the current position (%NULL to initiate traversal)
+ * @root: css whose descendants to walk
+ *
+ * To be used by css_for_each_descendant_post(). Find the next descendant
+ * to visit for post-order traversal of @root's descendants. @root is
+ * included in the iteration and the last node to be visited.
+ *
+ * While this function requires cgroup_mutex or RCU read locking, it
+ * doesn't require the whole traversal to be contained in a single critical
+ * section. This function will return the correct next descendant as long
+ * as both @pos and @cgroup are accessible and @pos is a descendant of
+ * @cgroup.
+ *
+ * If a subsystem synchronizes ->css_online() and the start of iteration, a
+ * css which finished ->css_online() is guaranteed to be visible in the
+ * future iterations and will stay visible until the last reference is put.
+ * A css which hasn't finished ->css_online() or already finished
+ * ->css_offline() may show up during traversal. It's each subsystem's
+ * responsibility to synchronize against on/offlining.
+ */
+struct cgroup_subsys_state *
+css_next_descendant_post(struct cgroup_subsys_state *pos,
+ struct cgroup_subsys_state *root)
+{
+ struct cgroup_subsys_state *next;
+
+ cgroup_assert_mutex_or_rcu_locked();
+
+ /* if first iteration, visit leftmost descendant which may be @root */
+ if (!pos)
+ return css_leftmost_descendant(root);
+
+ /* if we visited @root, we're done */
+ if (pos == root)
+ return NULL;
+
+ /* if there's an unvisited sibling, visit its leftmost descendant */
+ next = css_next_child(pos, pos->parent);
+ if (next)
+ return css_leftmost_descendant(next);
+
+ /* no sibling left, visit parent */
+ return pos->parent;
+}
+
+/**
+ * css_has_online_children - does a css have online children
+ * @css: the target css
+ *
+ * Returns %true if @css has any online children; otherwise, %false. This
+ * function can be called from any context but the caller is responsible
+ * for synchronizing against on/offlining as necessary.
+ */
+bool css_has_online_children(struct cgroup_subsys_state *css)
+{
+ struct cgroup_subsys_state *child;
+ bool ret = false;
+
+ rcu_read_lock();
+ css_for_each_child(child, css) {
+ if (child->flags & CSS_ONLINE) {
+ ret = true;
+ break;
+ }
+ }
+ rcu_read_unlock();
+ return ret;
+}
+
+static struct css_set *css_task_iter_next_css_set(struct css_task_iter *it)
+{
+ struct list_head *l;
+ struct cgrp_cset_link *link;
+ struct css_set *cset;
+
+ lockdep_assert_held(&css_set_lock);
+
+ /* find the next threaded cset */
+ if (it->tcset_pos) {
+ l = it->tcset_pos->next;
+
+ if (l != it->tcset_head) {
+ it->tcset_pos = l;
+ return container_of(l, struct css_set,
+ threaded_csets_node);
+ }
+
+ it->tcset_pos = NULL;
+ }
+
+ /* find the next cset */
+ l = it->cset_pos;
+ l = l->next;
+ if (l == it->cset_head) {
+ it->cset_pos = NULL;
+ return NULL;
+ }
+
+ if (it->ss) {
+ cset = container_of(l, struct css_set, e_cset_node[it->ss->id]);
+ } else {
+ link = list_entry(l, struct cgrp_cset_link, cset_link);
+ cset = link->cset;
+ }
+
+ it->cset_pos = l;
+
+ /* initialize threaded css_set walking */
+ if (it->flags & CSS_TASK_ITER_THREADED) {
+ if (it->cur_dcset)
+ put_css_set_locked(it->cur_dcset);
+ it->cur_dcset = cset;
+ get_css_set(cset);
+
+ it->tcset_head = &cset->threaded_csets;
+ it->tcset_pos = &cset->threaded_csets;
+ }
+
+ return cset;
+}
+
+/**
+ * css_task_iter_advance_css_set - advance a task iterator to the next css_set
+ * @it: the iterator to advance
+ *
+ * Advance @it to the next css_set to walk.
+ */
+static void css_task_iter_advance_css_set(struct css_task_iter *it)
+{
+ struct css_set *cset;
+
+ lockdep_assert_held(&css_set_lock);
+
+ /* Advance to the next non-empty css_set and find first non-empty tasks list*/
+ while ((cset = css_task_iter_next_css_set(it))) {
+ if (!list_empty(&cset->tasks)) {
+ it->cur_tasks_head = &cset->tasks;
+ break;
+ } else if (!list_empty(&cset->mg_tasks)) {
+ it->cur_tasks_head = &cset->mg_tasks;
+ break;
+ } else if (!list_empty(&cset->dying_tasks)) {
+ it->cur_tasks_head = &cset->dying_tasks;
+ break;
+ }
+ }
+ if (!cset) {
+ it->task_pos = NULL;
+ return;
+ }
+ it->task_pos = it->cur_tasks_head->next;
+
+ /*
+ * We don't keep css_sets locked across iteration steps and thus
+ * need to take steps to ensure that iteration can be resumed after
+ * the lock is re-acquired. Iteration is performed at two levels -
+ * css_sets and tasks in them.
+ *
+ * Once created, a css_set never leaves its cgroup lists, so a
+ * pinned css_set is guaranteed to stay put and we can resume
+ * iteration afterwards.
+ *
+ * Tasks may leave @cset across iteration steps. This is resolved
+ * by registering each iterator with the css_set currently being
+ * walked and making css_set_move_task() advance iterators whose
+ * next task is leaving.
+ */
+ if (it->cur_cset) {
+ list_del(&it->iters_node);
+ put_css_set_locked(it->cur_cset);
+ }
+ get_css_set(cset);
+ it->cur_cset = cset;
+ list_add(&it->iters_node, &cset->task_iters);
+}
+
+static void css_task_iter_skip(struct css_task_iter *it,
+ struct task_struct *task)
+{
+ lockdep_assert_held(&css_set_lock);
+
+ if (it->task_pos == &task->cg_list) {
+ it->task_pos = it->task_pos->next;
+ it->flags |= CSS_TASK_ITER_SKIPPED;
+ }
+}
+
+static void css_task_iter_advance(struct css_task_iter *it)
+{
+ struct task_struct *task;
+
+ lockdep_assert_held(&css_set_lock);
+repeat:
+ if (it->task_pos) {
+ /*
+ * Advance iterator to find next entry. We go through cset
+ * tasks, mg_tasks and dying_tasks, when consumed we move onto
+ * the next cset.
+ */
+ if (it->flags & CSS_TASK_ITER_SKIPPED)
+ it->flags &= ~CSS_TASK_ITER_SKIPPED;
+ else
+ it->task_pos = it->task_pos->next;
+
+ if (it->task_pos == &it->cur_cset->tasks) {
+ it->cur_tasks_head = &it->cur_cset->mg_tasks;
+ it->task_pos = it->cur_tasks_head->next;
+ }
+ if (it->task_pos == &it->cur_cset->mg_tasks) {
+ it->cur_tasks_head = &it->cur_cset->dying_tasks;
+ it->task_pos = it->cur_tasks_head->next;
+ }
+ if (it->task_pos == &it->cur_cset->dying_tasks)
+ css_task_iter_advance_css_set(it);
+ } else {
+ /* called from start, proceed to the first cset */
+ css_task_iter_advance_css_set(it);
+ }
+
+ if (!it->task_pos)
+ return;
+
+ task = list_entry(it->task_pos, struct task_struct, cg_list);
+
+ if (it->flags & CSS_TASK_ITER_PROCS) {
+ /* if PROCS, skip over tasks which aren't group leaders */
+ if (!thread_group_leader(task))
+ goto repeat;
+
+ /* and dying leaders w/o live member threads */
+ if (it->cur_tasks_head == &it->cur_cset->dying_tasks &&
+ !atomic_read(&task->signal->live))
+ goto repeat;
+ } else {
+ /* skip all dying ones */
+ if (it->cur_tasks_head == &it->cur_cset->dying_tasks)
+ goto repeat;
+ }
+}
+
+/**
+ * css_task_iter_start - initiate task iteration
+ * @css: the css to walk tasks of
+ * @flags: CSS_TASK_ITER_* flags
+ * @it: the task iterator to use
+ *
+ * Initiate iteration through the tasks of @css. The caller can call
+ * css_task_iter_next() to walk through the tasks until the function
+ * returns NULL. On completion of iteration, css_task_iter_end() must be
+ * called.
+ */
+void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
+ struct css_task_iter *it)
+{
+ memset(it, 0, sizeof(*it));
+
+ spin_lock_irq(&css_set_lock);
+
+ it->ss = css->ss;
+ it->flags = flags;
+
+ if (CGROUP_HAS_SUBSYS_CONFIG && it->ss)
+ it->cset_pos = &css->cgroup->e_csets[css->ss->id];
+ else
+ it->cset_pos = &css->cgroup->cset_links;
+
+ it->cset_head = it->cset_pos;
+
+ css_task_iter_advance(it);
+
+ spin_unlock_irq(&css_set_lock);
+}
+
+/**
+ * css_task_iter_next - return the next task for the iterator
+ * @it: the task iterator being iterated
+ *
+ * The "next" function for task iteration. @it should have been
+ * initialized via css_task_iter_start(). Returns NULL when the iteration
+ * reaches the end.
+ */
+struct task_struct *css_task_iter_next(struct css_task_iter *it)
+{
+ if (it->cur_task) {
+ put_task_struct(it->cur_task);
+ it->cur_task = NULL;
+ }
+
+ spin_lock_irq(&css_set_lock);
+
+ /* @it may be half-advanced by skips, finish advancing */
+ if (it->flags & CSS_TASK_ITER_SKIPPED)
+ css_task_iter_advance(it);
+
+ if (it->task_pos) {
+ it->cur_task = list_entry(it->task_pos, struct task_struct,
+ cg_list);
+ get_task_struct(it->cur_task);
+ css_task_iter_advance(it);
+ }
+
+ spin_unlock_irq(&css_set_lock);
+
+ return it->cur_task;
+}
+
+/**
+ * css_task_iter_end - finish task iteration
+ * @it: the task iterator to finish
+ *
+ * Finish task iteration started by css_task_iter_start().
+ */
+void css_task_iter_end(struct css_task_iter *it)
+{
+ if (it->cur_cset) {
+ spin_lock_irq(&css_set_lock);
+ list_del(&it->iters_node);
+ put_css_set_locked(it->cur_cset);
+ spin_unlock_irq(&css_set_lock);
+ }
+
+ if (it->cur_dcset)
+ put_css_set(it->cur_dcset);
+
+ if (it->cur_task)
+ put_task_struct(it->cur_task);
+}
+
+static void cgroup_procs_release(struct kernfs_open_file *of)
+{
+ struct cgroup_file_ctx *ctx = of->priv;
+
+ if (ctx->procs.started)
+ css_task_iter_end(&ctx->procs.iter);
+}
+
+static void *cgroup_procs_next(struct seq_file *s, void *v, loff_t *pos)
+{
+ struct kernfs_open_file *of = s->private;
+ struct cgroup_file_ctx *ctx = of->priv;
+
+ if (pos)
+ (*pos)++;
+
+ return css_task_iter_next(&ctx->procs.iter);
+}
+
+static void *__cgroup_procs_start(struct seq_file *s, loff_t *pos,
+ unsigned int iter_flags)
+{
+ struct kernfs_open_file *of = s->private;
+ struct cgroup *cgrp = seq_css(s)->cgroup;
+ struct cgroup_file_ctx *ctx = of->priv;
+ struct css_task_iter *it = &ctx->procs.iter;
+
+ /*
+ * When a seq_file is seeked, it's always traversed sequentially
+ * from position 0, so we can simply keep iterating on !0 *pos.
+ */
+ if (!ctx->procs.started) {
+ if (WARN_ON_ONCE((*pos)))
+ return ERR_PTR(-EINVAL);
+ css_task_iter_start(&cgrp->self, iter_flags, it);
+ ctx->procs.started = true;
+ } else if (!(*pos)) {
+ css_task_iter_end(it);
+ css_task_iter_start(&cgrp->self, iter_flags, it);
+ } else
+ return it->cur_task;
+
+ return cgroup_procs_next(s, NULL, NULL);
+}
+
+static void *cgroup_procs_start(struct seq_file *s, loff_t *pos)
+{
+ struct cgroup *cgrp = seq_css(s)->cgroup;
+
+ /*
+ * All processes of a threaded subtree belong to the domain cgroup
+ * of the subtree. Only threads can be distributed across the
+ * subtree. Reject reads on cgroup.procs in the subtree proper.
+ * They're always empty anyway.
+ */
+ if (cgroup_is_threaded(cgrp))
+ return ERR_PTR(-EOPNOTSUPP);
+
+ return __cgroup_procs_start(s, pos, CSS_TASK_ITER_PROCS |
+ CSS_TASK_ITER_THREADED);
+}
+
+static int cgroup_procs_show(struct seq_file *s, void *v)
+{
+ seq_printf(s, "%d\n", task_pid_vnr(v));
+ return 0;
+}
+
+static int cgroup_may_write(const struct cgroup *cgrp, struct super_block *sb)
+{
+ int ret;
+ struct inode *inode;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ inode = kernfs_get_inode(sb, cgrp->procs_file.kn);
+ if (!inode)
+ return -ENOMEM;
+
+ ret = inode_permission(&nop_mnt_idmap, inode, MAY_WRITE);
+ iput(inode);
+ return ret;
+}
+
+static int cgroup_procs_write_permission(struct cgroup *src_cgrp,
+ struct cgroup *dst_cgrp,
+ struct super_block *sb,
+ struct cgroup_namespace *ns)
+{
+ struct cgroup *com_cgrp = src_cgrp;
+ int ret;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* find the common ancestor */
+ while (!cgroup_is_descendant(dst_cgrp, com_cgrp))
+ com_cgrp = cgroup_parent(com_cgrp);
+
+ /* %current should be authorized to migrate to the common ancestor */
+ ret = cgroup_may_write(com_cgrp, sb);
+ if (ret)
+ return ret;
+
+ /*
+ * If namespaces are delegation boundaries, %current must be able
+ * to see both source and destination cgroups from its namespace.
+ */
+ if ((cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE) &&
+ (!cgroup_is_descendant(src_cgrp, ns->root_cset->dfl_cgrp) ||
+ !cgroup_is_descendant(dst_cgrp, ns->root_cset->dfl_cgrp)))
+ return -ENOENT;
+
+ return 0;
+}
+
+static int cgroup_attach_permissions(struct cgroup *src_cgrp,
+ struct cgroup *dst_cgrp,
+ struct super_block *sb, bool threadgroup,
+ struct cgroup_namespace *ns)
+{
+ int ret = 0;
+
+ ret = cgroup_procs_write_permission(src_cgrp, dst_cgrp, sb, ns);
+ if (ret)
+ return ret;
+
+ ret = cgroup_migrate_vet_dst(dst_cgrp);
+ if (ret)
+ return ret;
+
+ if (!threadgroup && (src_cgrp->dom_cgrp != dst_cgrp->dom_cgrp))
+ ret = -EOPNOTSUPP;
+
+ return ret;
+}
+
+static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
+ bool threadgroup)
+{
+ struct cgroup_file_ctx *ctx = of->priv;
+ struct cgroup *src_cgrp, *dst_cgrp;
+ struct task_struct *task;
+ const struct cred *saved_cred;
+ ssize_t ret;
+ bool threadgroup_locked;
+
+ dst_cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!dst_cgrp)
+ return -ENODEV;
+
+ task = cgroup_procs_write_start(buf, threadgroup, &threadgroup_locked);
+ ret = PTR_ERR_OR_ZERO(task);
+ if (ret)
+ goto out_unlock;
+
+ /* find the source cgroup */
+ spin_lock_irq(&css_set_lock);
+ src_cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
+ spin_unlock_irq(&css_set_lock);
+
+ /*
+ * Process and thread migrations follow same delegation rule. Check
+ * permissions using the credentials from file open to protect against
+ * inherited fd attacks.
+ */
+ saved_cred = override_creds(of->file->f_cred);
+ ret = cgroup_attach_permissions(src_cgrp, dst_cgrp,
+ of->file->f_path.dentry->d_sb,
+ threadgroup, ctx->ns);
+ revert_creds(saved_cred);
+ if (ret)
+ goto out_finish;
+
+ ret = cgroup_attach_task(dst_cgrp, task, threadgroup);
+
+out_finish:
+ cgroup_procs_write_finish(task, threadgroup_locked);
+out_unlock:
+ cgroup_kn_unlock(of->kn);
+
+ return ret;
+}
+
+static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ return __cgroup_procs_write(of, buf, true) ?: nbytes;
+}
+
+static void *cgroup_threads_start(struct seq_file *s, loff_t *pos)
+{
+ return __cgroup_procs_start(s, pos, 0);
+}
+
+static ssize_t cgroup_threads_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ return __cgroup_procs_write(of, buf, false) ?: nbytes;
+}
+
+/* cgroup core interface files for the default hierarchy */
+static struct cftype cgroup_base_files[] = {
+ {
+ .name = "cgroup.type",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = cgroup_type_show,
+ .write = cgroup_type_write,
+ },
+ {
+ .name = "cgroup.procs",
+ .flags = CFTYPE_NS_DELEGATABLE,
+ .file_offset = offsetof(struct cgroup, procs_file),
+ .release = cgroup_procs_release,
+ .seq_start = cgroup_procs_start,
+ .seq_next = cgroup_procs_next,
+ .seq_show = cgroup_procs_show,
+ .write = cgroup_procs_write,
+ },
+ {
+ .name = "cgroup.threads",
+ .flags = CFTYPE_NS_DELEGATABLE,
+ .release = cgroup_procs_release,
+ .seq_start = cgroup_threads_start,
+ .seq_next = cgroup_procs_next,
+ .seq_show = cgroup_procs_show,
+ .write = cgroup_threads_write,
+ },
+ {
+ .name = "cgroup.controllers",
+ .seq_show = cgroup_controllers_show,
+ },
+ {
+ .name = "cgroup.subtree_control",
+ .flags = CFTYPE_NS_DELEGATABLE,
+ .seq_show = cgroup_subtree_control_show,
+ .write = cgroup_subtree_control_write,
+ },
+ {
+ .name = "cgroup.events",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .file_offset = offsetof(struct cgroup, events_file),
+ .seq_show = cgroup_events_show,
+ },
+ {
+ .name = "cgroup.max.descendants",
+ .seq_show = cgroup_max_descendants_show,
+ .write = cgroup_max_descendants_write,
+ },
+ {
+ .name = "cgroup.max.depth",
+ .seq_show = cgroup_max_depth_show,
+ .write = cgroup_max_depth_write,
+ },
+ {
+ .name = "cgroup.stat",
+ .seq_show = cgroup_stat_show,
+ },
+ {
+ .name = "cgroup.freeze",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = cgroup_freeze_show,
+ .write = cgroup_freeze_write,
+ },
+ {
+ .name = "cgroup.kill",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .write = cgroup_kill_write,
+ },
+ {
+ .name = "cpu.stat",
+ .seq_show = cpu_stat_show,
+ },
+ {
+ .name = "cpu.stat.local",
+ .seq_show = cpu_local_stat_show,
+ },
+ { } /* terminate */
+};
+
+static struct cftype cgroup_psi_files[] = {
+#ifdef CONFIG_PSI
+ {
+ .name = "io.pressure",
+ .file_offset = offsetof(struct cgroup, psi_files[PSI_IO]),
+ .seq_show = cgroup_io_pressure_show,
+ .write = cgroup_io_pressure_write,
+ .poll = cgroup_pressure_poll,
+ .release = cgroup_pressure_release,
+ },
+ {
+ .name = "memory.pressure",
+ .file_offset = offsetof(struct cgroup, psi_files[PSI_MEM]),
+ .seq_show = cgroup_memory_pressure_show,
+ .write = cgroup_memory_pressure_write,
+ .poll = cgroup_pressure_poll,
+ .release = cgroup_pressure_release,
+ },
+ {
+ .name = "cpu.pressure",
+ .file_offset = offsetof(struct cgroup, psi_files[PSI_CPU]),
+ .seq_show = cgroup_cpu_pressure_show,
+ .write = cgroup_cpu_pressure_write,
+ .poll = cgroup_pressure_poll,
+ .release = cgroup_pressure_release,
+ },
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+ {
+ .name = "irq.pressure",
+ .file_offset = offsetof(struct cgroup, psi_files[PSI_IRQ]),
+ .seq_show = cgroup_irq_pressure_show,
+ .write = cgroup_irq_pressure_write,
+ .poll = cgroup_pressure_poll,
+ .release = cgroup_pressure_release,
+ },
+#endif
+ {
+ .name = "cgroup.pressure",
+ .seq_show = cgroup_pressure_show,
+ .write = cgroup_pressure_write,
+ },
+#endif /* CONFIG_PSI */
+ { } /* terminate */
+};
+
+/*
+ * css destruction is four-stage process.
+ *
+ * 1. Destruction starts. Killing of the percpu_ref is initiated.
+ * Implemented in kill_css().
+ *
+ * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
+ * and thus css_tryget_online() is guaranteed to fail, the css can be
+ * offlined by invoking offline_css(). After offlining, the base ref is
+ * put. Implemented in css_killed_work_fn().
+ *
+ * 3. When the percpu_ref reaches zero, the only possible remaining
+ * accessors are inside RCU read sections. css_release() schedules the
+ * RCU callback.
+ *
+ * 4. After the grace period, the css can be freed. Implemented in
+ * css_free_rwork_fn().
+ *
+ * It is actually hairier because both step 2 and 4 require process context
+ * and thus involve punting to css->destroy_work adding two additional
+ * steps to the already complex sequence.
+ */
+static void css_free_rwork_fn(struct work_struct *work)
+{
+ struct cgroup_subsys_state *css = container_of(to_rcu_work(work),
+ struct cgroup_subsys_state, destroy_rwork);
+ struct cgroup_subsys *ss = css->ss;
+ struct cgroup *cgrp = css->cgroup;
+
+ percpu_ref_exit(&css->refcnt);
+
+ if (ss) {
+ /* css free path */
+ struct cgroup_subsys_state *parent = css->parent;
+ int id = css->id;
+
+ ss->css_free(css);
+ cgroup_idr_remove(&ss->css_idr, id);
+ cgroup_put(cgrp);
+
+ if (parent)
+ css_put(parent);
+ } else {
+ /* cgroup free path */
+ atomic_dec(&cgrp->root->nr_cgrps);
+ cgroup1_pidlist_destroy_all(cgrp);
+ cancel_work_sync(&cgrp->release_agent_work);
+ bpf_cgrp_storage_free(cgrp);
+
+ if (cgroup_parent(cgrp)) {
+ /*
+ * We get a ref to the parent, and put the ref when
+ * this cgroup is being freed, so it's guaranteed
+ * that the parent won't be destroyed before its
+ * children.
+ */
+ cgroup_put(cgroup_parent(cgrp));
+ kernfs_put(cgrp->kn);
+ psi_cgroup_free(cgrp);
+ cgroup_rstat_exit(cgrp);
+ kfree(cgrp);
+ } else {
+ /*
+ * This is root cgroup's refcnt reaching zero,
+ * which indicates that the root should be
+ * released.
+ */
+ cgroup_destroy_root(cgrp->root);
+ }
+ }
+}
+
+static void css_release_work_fn(struct work_struct *work)
+{
+ struct cgroup_subsys_state *css =
+ container_of(work, struct cgroup_subsys_state, destroy_work);
+ struct cgroup_subsys *ss = css->ss;
+ struct cgroup *cgrp = css->cgroup;
+
+ cgroup_lock();
+
+ css->flags |= CSS_RELEASED;
+ list_del_rcu(&css->sibling);
+
+ if (ss) {
+ /* css release path */
+ if (!list_empty(&css->rstat_css_node)) {
+ cgroup_rstat_flush(cgrp);
+ list_del_rcu(&css->rstat_css_node);
+ }
+
+ cgroup_idr_replace(&ss->css_idr, NULL, css->id);
+ if (ss->css_released)
+ ss->css_released(css);
+ } else {
+ struct cgroup *tcgrp;
+
+ /* cgroup release path */
+ TRACE_CGROUP_PATH(release, cgrp);
+
+ cgroup_rstat_flush(cgrp);
+
+ spin_lock_irq(&css_set_lock);
+ for (tcgrp = cgroup_parent(cgrp); tcgrp;
+ tcgrp = cgroup_parent(tcgrp))
+ tcgrp->nr_dying_descendants--;
+ spin_unlock_irq(&css_set_lock);
+
+ /*
+ * There are two control paths which try to determine
+ * cgroup from dentry without going through kernfs -
+ * cgroupstats_build() and css_tryget_online_from_dir().
+ * Those are supported by RCU protecting clearing of
+ * cgrp->kn->priv backpointer.
+ */
+ if (cgrp->kn)
+ RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv,
+ NULL);
+ }
+
+ cgroup_unlock();
+
+ INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn);
+ queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork);
+}
+
+static void css_release(struct percpu_ref *ref)
+{
+ struct cgroup_subsys_state *css =
+ container_of(ref, struct cgroup_subsys_state, refcnt);
+
+ INIT_WORK(&css->destroy_work, css_release_work_fn);
+ queue_work(cgroup_destroy_wq, &css->destroy_work);
+}
+
+static void init_and_link_css(struct cgroup_subsys_state *css,
+ struct cgroup_subsys *ss, struct cgroup *cgrp)
+{
+ lockdep_assert_held(&cgroup_mutex);
+
+ cgroup_get_live(cgrp);
+
+ memset(css, 0, sizeof(*css));
+ css->cgroup = cgrp;
+ css->ss = ss;
+ css->id = -1;
+ INIT_LIST_HEAD(&css->sibling);
+ INIT_LIST_HEAD(&css->children);
+ INIT_LIST_HEAD(&css->rstat_css_node);
+ css->serial_nr = css_serial_nr_next++;
+ atomic_set(&css->online_cnt, 0);
+
+ if (cgroup_parent(cgrp)) {
+ css->parent = cgroup_css(cgroup_parent(cgrp), ss);
+ css_get(css->parent);
+ }
+
+ if (ss->css_rstat_flush)
+ list_add_rcu(&css->rstat_css_node, &cgrp->rstat_css_list);
+
+ BUG_ON(cgroup_css(cgrp, ss));
+}
+
+/* invoke ->css_online() on a new CSS and mark it online if successful */
+static int online_css(struct cgroup_subsys_state *css)
+{
+ struct cgroup_subsys *ss = css->ss;
+ int ret = 0;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ if (ss->css_online)
+ ret = ss->css_online(css);
+ if (!ret) {
+ css->flags |= CSS_ONLINE;
+ rcu_assign_pointer(css->cgroup->subsys[ss->id], css);
+
+ atomic_inc(&css->online_cnt);
+ if (css->parent)
+ atomic_inc(&css->parent->online_cnt);
+ }
+ return ret;
+}
+
+/* if the CSS is online, invoke ->css_offline() on it and mark it offline */
+static void offline_css(struct cgroup_subsys_state *css)
+{
+ struct cgroup_subsys *ss = css->ss;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ if (!(css->flags & CSS_ONLINE))
+ return;
+
+ if (ss->css_offline)
+ ss->css_offline(css);
+
+ css->flags &= ~CSS_ONLINE;
+ RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL);
+
+ wake_up_all(&css->cgroup->offline_waitq);
+}
+
+/**
+ * css_create - create a cgroup_subsys_state
+ * @cgrp: the cgroup new css will be associated with
+ * @ss: the subsys of new css
+ *
+ * Create a new css associated with @cgrp - @ss pair. On success, the new
+ * css is online and installed in @cgrp. This function doesn't create the
+ * interface files. Returns 0 on success, -errno on failure.
+ */
+static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
+{
+ struct cgroup *parent = cgroup_parent(cgrp);
+ struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss);
+ struct cgroup_subsys_state *css;
+ int err;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ css = ss->css_alloc(parent_css);
+ if (!css)
+ css = ERR_PTR(-ENOMEM);
+ if (IS_ERR(css))
+ return css;
+
+ init_and_link_css(css, ss, cgrp);
+
+ err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL);
+ if (err)
+ goto err_free_css;
+
+ err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL);
+ if (err < 0)
+ goto err_free_css;
+ css->id = err;
+
+ /* @css is ready to be brought online now, make it visible */
+ list_add_tail_rcu(&css->sibling, &parent_css->children);
+ cgroup_idr_replace(&ss->css_idr, css, css->id);
+
+ err = online_css(css);
+ if (err)
+ goto err_list_del;
+
+ return css;
+
+err_list_del:
+ list_del_rcu(&css->sibling);
+err_free_css:
+ list_del_rcu(&css->rstat_css_node);
+ INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn);
+ queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork);
+ return ERR_PTR(err);
+}
+
+/*
+ * The returned cgroup is fully initialized including its control mask, but
+ * it doesn't have the control mask applied.
+ */
+static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
+ umode_t mode)
+{
+ struct cgroup_root *root = parent->root;
+ struct cgroup *cgrp, *tcgrp;
+ struct kernfs_node *kn;
+ int level = parent->level + 1;
+ int ret;
+
+ /* allocate the cgroup and its ID, 0 is reserved for the root */
+ cgrp = kzalloc(struct_size(cgrp, ancestors, (level + 1)), GFP_KERNEL);
+ if (!cgrp)
+ return ERR_PTR(-ENOMEM);
+
+ ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL);
+ if (ret)
+ goto out_free_cgrp;
+
+ ret = cgroup_rstat_init(cgrp);
+ if (ret)
+ goto out_cancel_ref;
+
+ /* create the directory */
+ kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
+ if (IS_ERR(kn)) {
+ ret = PTR_ERR(kn);
+ goto out_stat_exit;
+ }
+ cgrp->kn = kn;
+
+ init_cgroup_housekeeping(cgrp);
+
+ cgrp->self.parent = &parent->self;
+ cgrp->root = root;
+ cgrp->level = level;
+
+ ret = psi_cgroup_alloc(cgrp);
+ if (ret)
+ goto out_kernfs_remove;
+
+ ret = cgroup_bpf_inherit(cgrp);
+ if (ret)
+ goto out_psi_free;
+
+ /*
+ * New cgroup inherits effective freeze counter, and
+ * if the parent has to be frozen, the child has too.
+ */
+ cgrp->freezer.e_freeze = parent->freezer.e_freeze;
+ if (cgrp->freezer.e_freeze) {
+ /*
+ * Set the CGRP_FREEZE flag, so when a process will be
+ * attached to the child cgroup, it will become frozen.
+ * At this point the new cgroup is unpopulated, so we can
+ * consider it frozen immediately.
+ */
+ set_bit(CGRP_FREEZE, &cgrp->flags);
+ set_bit(CGRP_FROZEN, &cgrp->flags);
+ }
+
+ spin_lock_irq(&css_set_lock);
+ for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) {
+ cgrp->ancestors[tcgrp->level] = tcgrp;
+
+ if (tcgrp != cgrp) {
+ tcgrp->nr_descendants++;
+
+ /*
+ * If the new cgroup is frozen, all ancestor cgroups
+ * get a new frozen descendant, but their state can't
+ * change because of this.
+ */
+ if (cgrp->freezer.e_freeze)
+ tcgrp->freezer.nr_frozen_descendants++;
+ }
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ if (notify_on_release(parent))
+ set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
+
+ if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags))
+ set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
+
+ cgrp->self.serial_nr = css_serial_nr_next++;
+
+ /* allocation complete, commit to creation */
+ list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children);
+ atomic_inc(&root->nr_cgrps);
+ cgroup_get_live(parent);
+
+ /*
+ * On the default hierarchy, a child doesn't automatically inherit
+ * subtree_control from the parent. Each is configured manually.
+ */
+ if (!cgroup_on_dfl(cgrp))
+ cgrp->subtree_control = cgroup_control(cgrp);
+
+ cgroup_propagate_control(cgrp);
+
+ return cgrp;
+
+out_psi_free:
+ psi_cgroup_free(cgrp);
+out_kernfs_remove:
+ kernfs_remove(cgrp->kn);
+out_stat_exit:
+ cgroup_rstat_exit(cgrp);
+out_cancel_ref:
+ percpu_ref_exit(&cgrp->self.refcnt);
+out_free_cgrp:
+ kfree(cgrp);
+ return ERR_PTR(ret);
+}
+
+static bool cgroup_check_hierarchy_limits(struct cgroup *parent)
+{
+ struct cgroup *cgroup;
+ int ret = false;
+ int level = 1;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ for (cgroup = parent; cgroup; cgroup = cgroup_parent(cgroup)) {
+ if (cgroup->nr_descendants >= cgroup->max_descendants)
+ goto fail;
+
+ if (level > cgroup->max_depth)
+ goto fail;
+
+ level++;
+ }
+
+ ret = true;
+fail:
+ return ret;
+}
+
+int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode)
+{
+ struct cgroup *parent, *cgrp;
+ int ret;
+
+ /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */
+ if (strchr(name, '\n'))
+ return -EINVAL;
+
+ parent = cgroup_kn_lock_live(parent_kn, false);
+ if (!parent)
+ return -ENODEV;
+
+ if (!cgroup_check_hierarchy_limits(parent)) {
+ ret = -EAGAIN;
+ goto out_unlock;
+ }
+
+ cgrp = cgroup_create(parent, name, mode);
+ if (IS_ERR(cgrp)) {
+ ret = PTR_ERR(cgrp);
+ goto out_unlock;
+ }
+
+ /*
+ * This extra ref will be put in cgroup_free_fn() and guarantees
+ * that @cgrp->kn is always accessible.
+ */
+ kernfs_get(cgrp->kn);
+
+ ret = cgroup_kn_set_ugid(cgrp->kn);
+ if (ret)
+ goto out_destroy;
+
+ ret = css_populate_dir(&cgrp->self);
+ if (ret)
+ goto out_destroy;
+
+ ret = cgroup_apply_control_enable(cgrp);
+ if (ret)
+ goto out_destroy;
+
+ TRACE_CGROUP_PATH(mkdir, cgrp);
+
+ /* let's create and online css's */
+ kernfs_activate(cgrp->kn);
+
+ ret = 0;
+ goto out_unlock;
+
+out_destroy:
+ cgroup_destroy_locked(cgrp);
+out_unlock:
+ cgroup_kn_unlock(parent_kn);
+ return ret;
+}
+
+/*
+ * This is called when the refcnt of a css is confirmed to be killed.
+ * css_tryget_online() is now guaranteed to fail. Tell the subsystem to
+ * initiate destruction and put the css ref from kill_css().
+ */
+static void css_killed_work_fn(struct work_struct *work)
+{
+ struct cgroup_subsys_state *css =
+ container_of(work, struct cgroup_subsys_state, destroy_work);
+
+ cgroup_lock();
+
+ do {
+ offline_css(css);
+ css_put(css);
+ /* @css can't go away while we're holding cgroup_mutex */
+ css = css->parent;
+ } while (css && atomic_dec_and_test(&css->online_cnt));
+
+ cgroup_unlock();
+}
+
+/* css kill confirmation processing requires process context, bounce */
+static void css_killed_ref_fn(struct percpu_ref *ref)
+{
+ struct cgroup_subsys_state *css =
+ container_of(ref, struct cgroup_subsys_state, refcnt);
+
+ if (atomic_dec_and_test(&css->online_cnt)) {
+ INIT_WORK(&css->destroy_work, css_killed_work_fn);
+ queue_work(cgroup_destroy_wq, &css->destroy_work);
+ }
+}
+
+/**
+ * kill_css - destroy a css
+ * @css: css to destroy
+ *
+ * This function initiates destruction of @css by removing cgroup interface
+ * files and putting its base reference. ->css_offline() will be invoked
+ * asynchronously once css_tryget_online() is guaranteed to fail and when
+ * the reference count reaches zero, @css will be released.
+ */
+static void kill_css(struct cgroup_subsys_state *css)
+{
+ lockdep_assert_held(&cgroup_mutex);
+
+ if (css->flags & CSS_DYING)
+ return;
+
+ css->flags |= CSS_DYING;
+
+ /*
+ * This must happen before css is disassociated with its cgroup.
+ * See seq_css() for details.
+ */
+ css_clear_dir(css);
+
+ /*
+ * Killing would put the base ref, but we need to keep it alive
+ * until after ->css_offline().
+ */
+ css_get(css);
+
+ /*
+ * cgroup core guarantees that, by the time ->css_offline() is
+ * invoked, no new css reference will be given out via
+ * css_tryget_online(). We can't simply call percpu_ref_kill() and
+ * proceed to offlining css's because percpu_ref_kill() doesn't
+ * guarantee that the ref is seen as killed on all CPUs on return.
+ *
+ * Use percpu_ref_kill_and_confirm() to get notifications as each
+ * css is confirmed to be seen as killed on all CPUs.
+ */
+ percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);
+}
+
+/**
+ * cgroup_destroy_locked - the first stage of cgroup destruction
+ * @cgrp: cgroup to be destroyed
+ *
+ * css's make use of percpu refcnts whose killing latency shouldn't be
+ * exposed to userland and are RCU protected. Also, cgroup core needs to
+ * guarantee that css_tryget_online() won't succeed by the time
+ * ->css_offline() is invoked. To satisfy all the requirements,
+ * destruction is implemented in the following two steps.
+ *
+ * s1. Verify @cgrp can be destroyed and mark it dying. Remove all
+ * userland visible parts and start killing the percpu refcnts of
+ * css's. Set up so that the next stage will be kicked off once all
+ * the percpu refcnts are confirmed to be killed.
+ *
+ * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
+ * rest of destruction. Once all cgroup references are gone, the
+ * cgroup is RCU-freed.
+ *
+ * This function implements s1. After this step, @cgrp is gone as far as
+ * the userland is concerned and a new cgroup with the same name may be
+ * created. As cgroup doesn't care about the names internally, this
+ * doesn't cause any problem.
+ */
+static int cgroup_destroy_locked(struct cgroup *cgrp)
+ __releases(&cgroup_mutex) __acquires(&cgroup_mutex)
+{
+ struct cgroup *tcgrp, *parent = cgroup_parent(cgrp);
+ struct cgroup_subsys_state *css;
+ struct cgrp_cset_link *link;
+ int ssid;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /*
+ * Only migration can raise populated from zero and we're already
+ * holding cgroup_mutex.
+ */
+ if (cgroup_is_populated(cgrp))
+ return -EBUSY;
+
+ /*
+ * Make sure there's no live children. We can't test emptiness of
+ * ->self.children as dead children linger on it while being
+ * drained; otherwise, "rmdir parent/child parent" may fail.
+ */
+ if (css_has_online_children(&cgrp->self))
+ return -EBUSY;
+
+ /*
+ * Mark @cgrp and the associated csets dead. The former prevents
+ * further task migration and child creation by disabling
+ * cgroup_kn_lock_live(). The latter makes the csets ignored by
+ * the migration path.
+ */
+ cgrp->self.flags &= ~CSS_ONLINE;
+
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry(link, &cgrp->cset_links, cset_link)
+ link->cset->dead = true;
+ spin_unlock_irq(&css_set_lock);
+
+ /* initiate massacre of all css's */
+ for_each_css(css, ssid, cgrp)
+ kill_css(css);
+
+ /* clear and remove @cgrp dir, @cgrp has an extra ref on its kn */
+ css_clear_dir(&cgrp->self);
+ kernfs_remove(cgrp->kn);
+
+ if (cgroup_is_threaded(cgrp))
+ parent->nr_threaded_children--;
+
+ spin_lock_irq(&css_set_lock);
+ for (tcgrp = parent; tcgrp; tcgrp = cgroup_parent(tcgrp)) {
+ tcgrp->nr_descendants--;
+ tcgrp->nr_dying_descendants++;
+ /*
+ * If the dying cgroup is frozen, decrease frozen descendants
+ * counters of ancestor cgroups.
+ */
+ if (test_bit(CGRP_FROZEN, &cgrp->flags))
+ tcgrp->freezer.nr_frozen_descendants--;
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ cgroup1_check_for_release(parent);
+
+ cgroup_bpf_offline(cgrp);
+
+ /* put the base reference */
+ percpu_ref_kill(&cgrp->self.refcnt);
+
+ return 0;
+};
+
+int cgroup_rmdir(struct kernfs_node *kn)
+{
+ struct cgroup *cgrp;
+ int ret = 0;
+
+ cgrp = cgroup_kn_lock_live(kn, false);
+ if (!cgrp)
+ return 0;
+
+ ret = cgroup_destroy_locked(cgrp);
+ if (!ret)
+ TRACE_CGROUP_PATH(rmdir, cgrp);
+
+ cgroup_kn_unlock(kn);
+ return ret;
+}
+
+static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
+ .show_options = cgroup_show_options,
+ .mkdir = cgroup_mkdir,
+ .rmdir = cgroup_rmdir,
+ .show_path = cgroup_show_path,
+};
+
+static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)
+{
+ struct cgroup_subsys_state *css;
+
+ pr_debug("Initializing cgroup subsys %s\n", ss->name);
+
+ cgroup_lock();
+
+ idr_init(&ss->css_idr);
+ INIT_LIST_HEAD(&ss->cfts);
+
+ /* Create the root cgroup state for this subsystem */
+ ss->root = &cgrp_dfl_root;
+ css = ss->css_alloc(NULL);
+ /* We don't handle early failures gracefully */
+ BUG_ON(IS_ERR(css));
+ init_and_link_css(css, ss, &cgrp_dfl_root.cgrp);
+
+ /*
+ * Root csses are never destroyed and we can't initialize
+ * percpu_ref during early init. Disable refcnting.
+ */
+ css->flags |= CSS_NO_REF;
+
+ if (early) {
+ /* allocation can't be done safely during early init */
+ css->id = 1;
+ } else {
+ css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL);
+ BUG_ON(css->id < 0);
+ }
+
+ /* Update the init_css_set to contain a subsys
+ * pointer to this state - since the subsystem is
+ * newly registered, all tasks and hence the
+ * init_css_set is in the subsystem's root cgroup. */
+ init_css_set.subsys[ss->id] = css;
+
+ have_fork_callback |= (bool)ss->fork << ss->id;
+ have_exit_callback |= (bool)ss->exit << ss->id;
+ have_release_callback |= (bool)ss->release << ss->id;
+ have_canfork_callback |= (bool)ss->can_fork << ss->id;
+
+ /* At system boot, before all subsystems have been
+ * registered, no tasks have been forked, so we don't
+ * need to invoke fork callbacks here. */
+ BUG_ON(!list_empty(&init_task.tasks));
+
+ BUG_ON(online_css(css));
+
+ cgroup_unlock();
+}
+
+/**
+ * cgroup_init_early - cgroup initialization at system boot
+ *
+ * Initialize cgroups at system boot, and initialize any
+ * subsystems that request early init.
+ */
+int __init cgroup_init_early(void)
+{
+ static struct cgroup_fs_context __initdata ctx;
+ struct cgroup_subsys *ss;
+ int i;
+
+ ctx.root = &cgrp_dfl_root;
+ init_cgroup_root(&ctx);
+ cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF;
+
+ RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
+
+ for_each_subsys(ss, i) {
+ WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id,
+ "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p id:name=%d:%s\n",
+ i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free,
+ ss->id, ss->name);
+ WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN,
+ "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]);
+
+ ss->id = i;
+ ss->name = cgroup_subsys_name[i];
+ if (!ss->legacy_name)
+ ss->legacy_name = cgroup_subsys_name[i];
+
+ if (ss->early_init)
+ cgroup_init_subsys(ss, true);
+ }
+ return 0;
+}
+
+/**
+ * cgroup_init - cgroup initialization
+ *
+ * Register cgroup filesystem and /proc file, and initialize
+ * any subsystems that didn't request early init.
+ */
+int __init cgroup_init(void)
+{
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16);
+ BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files));
+ BUG_ON(cgroup_init_cftypes(NULL, cgroup_psi_files));
+ BUG_ON(cgroup_init_cftypes(NULL, cgroup1_base_files));
+
+ cgroup_rstat_boot();
+
+ get_user_ns(init_cgroup_ns.user_ns);
+
+ cgroup_lock();
+
+ /*
+ * Add init_css_set to the hash table so that dfl_root can link to
+ * it during init.
+ */
+ hash_add(css_set_table, &init_css_set.hlist,
+ css_set_hash(init_css_set.subsys));
+
+ BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0));
+
+ cgroup_unlock();
+
+ for_each_subsys(ss, ssid) {
+ if (ss->early_init) {
+ struct cgroup_subsys_state *css =
+ init_css_set.subsys[ss->id];
+
+ css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2,
+ GFP_KERNEL);
+ BUG_ON(css->id < 0);
+ } else {
+ cgroup_init_subsys(ss, false);
+ }
+
+ list_add_tail(&init_css_set.e_cset_node[ssid],
+ &cgrp_dfl_root.cgrp.e_csets[ssid]);
+
+ /*
+ * Setting dfl_root subsys_mask needs to consider the
+ * disabled flag and cftype registration needs kmalloc,
+ * both of which aren't available during early_init.
+ */
+ if (!cgroup_ssid_enabled(ssid))
+ continue;
+
+ if (cgroup1_ssid_disabled(ssid))
+ pr_info("Disabling %s control group subsystem in v1 mounts\n",
+ ss->name);
+
+ cgrp_dfl_root.subsys_mask |= 1 << ss->id;
+
+ /* implicit controllers must be threaded too */
+ WARN_ON(ss->implicit_on_dfl && !ss->threaded);
+
+ if (ss->implicit_on_dfl)
+ cgrp_dfl_implicit_ss_mask |= 1 << ss->id;
+ else if (!ss->dfl_cftypes)
+ cgrp_dfl_inhibit_ss_mask |= 1 << ss->id;
+
+ if (ss->threaded)
+ cgrp_dfl_threaded_ss_mask |= 1 << ss->id;
+
+ if (ss->dfl_cftypes == ss->legacy_cftypes) {
+ WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes));
+ } else {
+ WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes));
+ WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes));
+ }
+
+ if (ss->bind)
+ ss->bind(init_css_set.subsys[ssid]);
+
+ cgroup_lock();
+ css_populate_dir(init_css_set.subsys[ssid]);
+ cgroup_unlock();
+ }
+
+ /* init_css_set.subsys[] has been updated, re-hash */
+ hash_del(&init_css_set.hlist);
+ hash_add(css_set_table, &init_css_set.hlist,
+ css_set_hash(init_css_set.subsys));
+
+ WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup"));
+ WARN_ON(register_filesystem(&cgroup_fs_type));
+ WARN_ON(register_filesystem(&cgroup2_fs_type));
+ WARN_ON(!proc_create_single("cgroups", 0, NULL, proc_cgroupstats_show));
+#ifdef CONFIG_CPUSETS
+ WARN_ON(register_filesystem(&cpuset_fs_type));
+#endif
+
+ return 0;
+}
+
+static int __init cgroup_wq_init(void)
+{
+ /*
+ * There isn't much point in executing destruction path in
+ * parallel. Good chunk is serialized with cgroup_mutex anyway.
+ * Use 1 for @max_active.
+ *
+ * We would prefer to do this in cgroup_init() above, but that
+ * is called before init_workqueues(): so leave this until after.
+ */
+ cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
+ BUG_ON(!cgroup_destroy_wq);
+ return 0;
+}
+core_initcall(cgroup_wq_init);
+
+void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen)
+{
+ struct kernfs_node *kn;
+
+ kn = kernfs_find_and_get_node_by_id(cgrp_dfl_root.kf_root, id);
+ if (!kn)
+ return;
+ kernfs_path(kn, buf, buflen);
+ kernfs_put(kn);
+}
+
+/*
+ * cgroup_get_from_id : get the cgroup associated with cgroup id
+ * @id: cgroup id
+ * On success return the cgrp or ERR_PTR on failure
+ * Only cgroups within current task's cgroup NS are valid.
+ */
+struct cgroup *cgroup_get_from_id(u64 id)
+{
+ struct kernfs_node *kn;
+ struct cgroup *cgrp, *root_cgrp;
+
+ kn = kernfs_find_and_get_node_by_id(cgrp_dfl_root.kf_root, id);
+ if (!kn)
+ return ERR_PTR(-ENOENT);
+
+ if (kernfs_type(kn) != KERNFS_DIR) {
+ kernfs_put(kn);
+ return ERR_PTR(-ENOENT);
+ }
+
+ rcu_read_lock();
+
+ cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
+ if (cgrp && !cgroup_tryget(cgrp))
+ cgrp = NULL;
+
+ rcu_read_unlock();
+ kernfs_put(kn);
+
+ if (!cgrp)
+ return ERR_PTR(-ENOENT);
+
+ root_cgrp = current_cgns_cgroup_dfl();
+ if (!cgroup_is_descendant(cgrp, root_cgrp)) {
+ cgroup_put(cgrp);
+ return ERR_PTR(-ENOENT);
+ }
+
+ return cgrp;
+}
+EXPORT_SYMBOL_GPL(cgroup_get_from_id);
+
+/*
+ * proc_cgroup_show()
+ * - Print task's cgroup paths into seq_file, one line for each hierarchy
+ * - Used for /proc/<pid>/cgroup.
+ */
+int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *tsk)
+{
+ char *buf;
+ int retval;
+ struct cgroup_root *root;
+
+ retval = -ENOMEM;
+ buf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!buf)
+ goto out;
+
+ cgroup_lock();
+ spin_lock_irq(&css_set_lock);
+
+ for_each_root(root) {
+ struct cgroup_subsys *ss;
+ struct cgroup *cgrp;
+ int ssid, count = 0;
+
+ if (root == &cgrp_dfl_root && !READ_ONCE(cgrp_dfl_visible))
+ continue;
+
+ seq_printf(m, "%d:", root->hierarchy_id);
+ if (root != &cgrp_dfl_root)
+ for_each_subsys(ss, ssid)
+ if (root->subsys_mask & (1 << ssid))
+ seq_printf(m, "%s%s", count++ ? "," : "",
+ ss->legacy_name);
+ if (strlen(root->name))
+ seq_printf(m, "%sname=%s", count ? "," : "",
+ root->name);
+ seq_putc(m, ':');
+
+ cgrp = task_cgroup_from_root(tsk, root);
+
+ /*
+ * On traditional hierarchies, all zombie tasks show up as
+ * belonging to the root cgroup. On the default hierarchy,
+ * while a zombie doesn't show up in "cgroup.procs" and
+ * thus can't be migrated, its /proc/PID/cgroup keeps
+ * reporting the cgroup it belonged to before exiting. If
+ * the cgroup is removed before the zombie is reaped,
+ * " (deleted)" is appended to the cgroup path.
+ */
+ if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) {
+ retval = cgroup_path_ns_locked(cgrp, buf, PATH_MAX,
+ current->nsproxy->cgroup_ns);
+ if (retval >= PATH_MAX)
+ retval = -ENAMETOOLONG;
+ if (retval < 0)
+ goto out_unlock;
+
+ seq_puts(m, buf);
+ } else {
+ seq_puts(m, "/");
+ }
+
+ if (cgroup_on_dfl(cgrp) && cgroup_is_dead(cgrp))
+ seq_puts(m, " (deleted)\n");
+ else
+ seq_putc(m, '\n');
+ }
+
+ retval = 0;
+out_unlock:
+ spin_unlock_irq(&css_set_lock);
+ cgroup_unlock();
+ kfree(buf);
+out:
+ return retval;
+}
+
+/**
+ * cgroup_fork - initialize cgroup related fields during copy_process()
+ * @child: pointer to task_struct of forking parent process.
+ *
+ * A task is associated with the init_css_set until cgroup_post_fork()
+ * attaches it to the target css_set.
+ */
+void cgroup_fork(struct task_struct *child)
+{
+ RCU_INIT_POINTER(child->cgroups, &init_css_set);
+ INIT_LIST_HEAD(&child->cg_list);
+}
+
+/**
+ * cgroup_v1v2_get_from_file - get a cgroup pointer from a file pointer
+ * @f: file corresponding to cgroup_dir
+ *
+ * Find the cgroup from a file pointer associated with a cgroup directory.
+ * Returns a pointer to the cgroup on success. ERR_PTR is returned if the
+ * cgroup cannot be found.
+ */
+static struct cgroup *cgroup_v1v2_get_from_file(struct file *f)
+{
+ struct cgroup_subsys_state *css;
+
+ css = css_tryget_online_from_dir(f->f_path.dentry, NULL);
+ if (IS_ERR(css))
+ return ERR_CAST(css);
+
+ return css->cgroup;
+}
+
+/**
+ * cgroup_get_from_file - same as cgroup_v1v2_get_from_file, but only supports
+ * cgroup2.
+ * @f: file corresponding to cgroup2_dir
+ */
+static struct cgroup *cgroup_get_from_file(struct file *f)
+{
+ struct cgroup *cgrp = cgroup_v1v2_get_from_file(f);
+
+ if (IS_ERR(cgrp))
+ return ERR_CAST(cgrp);
+
+ if (!cgroup_on_dfl(cgrp)) {
+ cgroup_put(cgrp);
+ return ERR_PTR(-EBADF);
+ }
+
+ return cgrp;
+}
+
+/**
+ * cgroup_css_set_fork - find or create a css_set for a child process
+ * @kargs: the arguments passed to create the child process
+ *
+ * This functions finds or creates a new css_set which the child
+ * process will be attached to in cgroup_post_fork(). By default,
+ * the child process will be given the same css_set as its parent.
+ *
+ * If CLONE_INTO_CGROUP is specified this function will try to find an
+ * existing css_set which includes the requested cgroup and if not create
+ * a new css_set that the child will be attached to later. If this function
+ * succeeds it will hold cgroup_threadgroup_rwsem on return. If
+ * CLONE_INTO_CGROUP is requested this function will grab cgroup mutex
+ * before grabbing cgroup_threadgroup_rwsem and will hold a reference
+ * to the target cgroup.
+ */
+static int cgroup_css_set_fork(struct kernel_clone_args *kargs)
+ __acquires(&cgroup_mutex) __acquires(&cgroup_threadgroup_rwsem)
+{
+ int ret;
+ struct cgroup *dst_cgrp = NULL;
+ struct css_set *cset;
+ struct super_block *sb;
+ struct file *f;
+
+ if (kargs->flags & CLONE_INTO_CGROUP)
+ cgroup_lock();
+
+ cgroup_threadgroup_change_begin(current);
+
+ spin_lock_irq(&css_set_lock);
+ cset = task_css_set(current);
+ get_css_set(cset);
+ spin_unlock_irq(&css_set_lock);
+
+ if (!(kargs->flags & CLONE_INTO_CGROUP)) {
+ kargs->cset = cset;
+ return 0;
+ }
+
+ f = fget_raw(kargs->cgroup);
+ if (!f) {
+ ret = -EBADF;
+ goto err;
+ }
+ sb = f->f_path.dentry->d_sb;
+
+ dst_cgrp = cgroup_get_from_file(f);
+ if (IS_ERR(dst_cgrp)) {
+ ret = PTR_ERR(dst_cgrp);
+ dst_cgrp = NULL;
+ goto err;
+ }
+
+ if (cgroup_is_dead(dst_cgrp)) {
+ ret = -ENODEV;
+ goto err;
+ }
+
+ /*
+ * Verify that we the target cgroup is writable for us. This is
+ * usually done by the vfs layer but since we're not going through
+ * the vfs layer here we need to do it "manually".
+ */
+ ret = cgroup_may_write(dst_cgrp, sb);
+ if (ret)
+ goto err;
+
+ /*
+ * Spawning a task directly into a cgroup works by passing a file
+ * descriptor to the target cgroup directory. This can even be an O_PATH
+ * file descriptor. But it can never be a cgroup.procs file descriptor.
+ * This was done on purpose so spawning into a cgroup could be
+ * conceptualized as an atomic
+ *
+ * fd = openat(dfd_cgroup, "cgroup.procs", ...);
+ * write(fd, <child-pid>, ...);
+ *
+ * sequence, i.e. it's a shorthand for the caller opening and writing
+ * cgroup.procs of the cgroup indicated by @dfd_cgroup. This allows us
+ * to always use the caller's credentials.
+ */
+ ret = cgroup_attach_permissions(cset->dfl_cgrp, dst_cgrp, sb,
+ !(kargs->flags & CLONE_THREAD),
+ current->nsproxy->cgroup_ns);
+ if (ret)
+ goto err;
+
+ kargs->cset = find_css_set(cset, dst_cgrp);
+ if (!kargs->cset) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ put_css_set(cset);
+ fput(f);
+ kargs->cgrp = dst_cgrp;
+ return ret;
+
+err:
+ cgroup_threadgroup_change_end(current);
+ cgroup_unlock();
+ if (f)
+ fput(f);
+ if (dst_cgrp)
+ cgroup_put(dst_cgrp);
+ put_css_set(cset);
+ if (kargs->cset)
+ put_css_set(kargs->cset);
+ return ret;
+}
+
+/**
+ * cgroup_css_set_put_fork - drop references we took during fork
+ * @kargs: the arguments passed to create the child process
+ *
+ * Drop references to the prepared css_set and target cgroup if
+ * CLONE_INTO_CGROUP was requested.
+ */
+static void cgroup_css_set_put_fork(struct kernel_clone_args *kargs)
+ __releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex)
+{
+ struct cgroup *cgrp = kargs->cgrp;
+ struct css_set *cset = kargs->cset;
+
+ cgroup_threadgroup_change_end(current);
+
+ if (cset) {
+ put_css_set(cset);
+ kargs->cset = NULL;
+ }
+
+ if (kargs->flags & CLONE_INTO_CGROUP) {
+ cgroup_unlock();
+ if (cgrp) {
+ cgroup_put(cgrp);
+ kargs->cgrp = NULL;
+ }
+ }
+}
+
+/**
+ * cgroup_can_fork - called on a new task before the process is exposed
+ * @child: the child process
+ * @kargs: the arguments passed to create the child process
+ *
+ * This prepares a new css_set for the child process which the child will
+ * be attached to in cgroup_post_fork().
+ * This calls the subsystem can_fork() callbacks. If the cgroup_can_fork()
+ * callback returns an error, the fork aborts with that error code. This
+ * allows for a cgroup subsystem to conditionally allow or deny new forks.
+ */
+int cgroup_can_fork(struct task_struct *child, struct kernel_clone_args *kargs)
+{
+ struct cgroup_subsys *ss;
+ int i, j, ret;
+
+ ret = cgroup_css_set_fork(kargs);
+ if (ret)
+ return ret;
+
+ do_each_subsys_mask(ss, i, have_canfork_callback) {
+ ret = ss->can_fork(child, kargs->cset);
+ if (ret)
+ goto out_revert;
+ } while_each_subsys_mask();
+
+ return 0;
+
+out_revert:
+ for_each_subsys(ss, j) {
+ if (j >= i)
+ break;
+ if (ss->cancel_fork)
+ ss->cancel_fork(child, kargs->cset);
+ }
+
+ cgroup_css_set_put_fork(kargs);
+
+ return ret;
+}
+
+/**
+ * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork()
+ * @child: the child process
+ * @kargs: the arguments passed to create the child process
+ *
+ * This calls the cancel_fork() callbacks if a fork failed *after*
+ * cgroup_can_fork() succeeded and cleans up references we took to
+ * prepare a new css_set for the child process in cgroup_can_fork().
+ */
+void cgroup_cancel_fork(struct task_struct *child,
+ struct kernel_clone_args *kargs)
+{
+ struct cgroup_subsys *ss;
+ int i;
+
+ for_each_subsys(ss, i)
+ if (ss->cancel_fork)
+ ss->cancel_fork(child, kargs->cset);
+
+ cgroup_css_set_put_fork(kargs);
+}
+
+/**
+ * cgroup_post_fork - finalize cgroup setup for the child process
+ * @child: the child process
+ * @kargs: the arguments passed to create the child process
+ *
+ * Attach the child process to its css_set calling the subsystem fork()
+ * callbacks.
+ */
+void cgroup_post_fork(struct task_struct *child,
+ struct kernel_clone_args *kargs)
+ __releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex)
+{
+ unsigned long cgrp_flags = 0;
+ bool kill = false;
+ struct cgroup_subsys *ss;
+ struct css_set *cset;
+ int i;
+
+ cset = kargs->cset;
+ kargs->cset = NULL;
+
+ spin_lock_irq(&css_set_lock);
+
+ /* init tasks are special, only link regular threads */
+ if (likely(child->pid)) {
+ if (kargs->cgrp)
+ cgrp_flags = kargs->cgrp->flags;
+ else
+ cgrp_flags = cset->dfl_cgrp->flags;
+
+ WARN_ON_ONCE(!list_empty(&child->cg_list));
+ cset->nr_tasks++;
+ css_set_move_task(child, NULL, cset, false);
+ } else {
+ put_css_set(cset);
+ cset = NULL;
+ }
+
+ if (!(child->flags & PF_KTHREAD)) {
+ if (unlikely(test_bit(CGRP_FREEZE, &cgrp_flags))) {
+ /*
+ * If the cgroup has to be frozen, the new task has
+ * too. Let's set the JOBCTL_TRAP_FREEZE jobctl bit to
+ * get the task into the frozen state.
+ */
+ spin_lock(&child->sighand->siglock);
+ WARN_ON_ONCE(child->frozen);
+ child->jobctl |= JOBCTL_TRAP_FREEZE;
+ spin_unlock(&child->sighand->siglock);
+
+ /*
+ * Calling cgroup_update_frozen() isn't required here,
+ * because it will be called anyway a bit later from
+ * do_freezer_trap(). So we avoid cgroup's transient
+ * switch from the frozen state and back.
+ */
+ }
+
+ /*
+ * If the cgroup is to be killed notice it now and take the
+ * child down right after we finished preparing it for
+ * userspace.
+ */
+ kill = test_bit(CGRP_KILL, &cgrp_flags);
+ }
+
+ spin_unlock_irq(&css_set_lock);
+
+ /*
+ * Call ss->fork(). This must happen after @child is linked on
+ * css_set; otherwise, @child might change state between ->fork()
+ * and addition to css_set.
+ */
+ do_each_subsys_mask(ss, i, have_fork_callback) {
+ ss->fork(child);
+ } while_each_subsys_mask();
+
+ /* Make the new cset the root_cset of the new cgroup namespace. */
+ if (kargs->flags & CLONE_NEWCGROUP) {
+ struct css_set *rcset = child->nsproxy->cgroup_ns->root_cset;
+
+ get_css_set(cset);
+ child->nsproxy->cgroup_ns->root_cset = cset;
+ put_css_set(rcset);
+ }
+
+ /* Cgroup has to be killed so take down child immediately. */
+ if (unlikely(kill))
+ do_send_sig_info(SIGKILL, SEND_SIG_NOINFO, child, PIDTYPE_TGID);
+
+ cgroup_css_set_put_fork(kargs);
+}
+
+/**
+ * cgroup_exit - detach cgroup from exiting task
+ * @tsk: pointer to task_struct of exiting process
+ *
+ * Description: Detach cgroup from @tsk.
+ *
+ */
+void cgroup_exit(struct task_struct *tsk)
+{
+ struct cgroup_subsys *ss;
+ struct css_set *cset;
+ int i;
+
+ spin_lock_irq(&css_set_lock);
+
+ WARN_ON_ONCE(list_empty(&tsk->cg_list));
+ cset = task_css_set(tsk);
+ css_set_move_task(tsk, cset, NULL, false);
+ list_add_tail(&tsk->cg_list, &cset->dying_tasks);
+ cset->nr_tasks--;
+
+ if (dl_task(tsk))
+ dec_dl_tasks_cs(tsk);
+
+ WARN_ON_ONCE(cgroup_task_frozen(tsk));
+ if (unlikely(!(tsk->flags & PF_KTHREAD) &&
+ test_bit(CGRP_FREEZE, &task_dfl_cgroup(tsk)->flags)))
+ cgroup_update_frozen(task_dfl_cgroup(tsk));
+
+ spin_unlock_irq(&css_set_lock);
+
+ /* see cgroup_post_fork() for details */
+ do_each_subsys_mask(ss, i, have_exit_callback) {
+ ss->exit(tsk);
+ } while_each_subsys_mask();
+}
+
+void cgroup_release(struct task_struct *task)
+{
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ do_each_subsys_mask(ss, ssid, have_release_callback) {
+ ss->release(task);
+ } while_each_subsys_mask();
+
+ spin_lock_irq(&css_set_lock);
+ css_set_skip_task_iters(task_css_set(task), task);
+ list_del_init(&task->cg_list);
+ spin_unlock_irq(&css_set_lock);
+}
+
+void cgroup_free(struct task_struct *task)
+{
+ struct css_set *cset = task_css_set(task);
+ put_css_set(cset);
+}
+
+static int __init cgroup_disable(char *str)
+{
+ struct cgroup_subsys *ss;
+ char *token;
+ int i;
+
+ while ((token = strsep(&str, ",")) != NULL) {
+ if (!*token)
+ continue;
+
+ for_each_subsys(ss, i) {
+ if (strcmp(token, ss->name) &&
+ strcmp(token, ss->legacy_name))
+ continue;
+
+ static_branch_disable(cgroup_subsys_enabled_key[i]);
+ pr_info("Disabling %s control group subsystem\n",
+ ss->name);
+ }
+
+ for (i = 0; i < OPT_FEATURE_COUNT; i++) {
+ if (strcmp(token, cgroup_opt_feature_names[i]))
+ continue;
+ cgroup_feature_disable_mask |= 1 << i;
+ pr_info("Disabling %s control group feature\n",
+ cgroup_opt_feature_names[i]);
+ break;
+ }
+ }
+ return 1;
+}
+__setup("cgroup_disable=", cgroup_disable);
+
+void __init __weak enable_debug_cgroup(void) { }
+
+static int __init enable_cgroup_debug(char *str)
+{
+ cgroup_debug = true;
+ enable_debug_cgroup();
+ return 1;
+}
+__setup("cgroup_debug", enable_cgroup_debug);
+
+/**
+ * css_tryget_online_from_dir - get corresponding css from a cgroup dentry
+ * @dentry: directory dentry of interest
+ * @ss: subsystem of interest
+ *
+ * If @dentry is a directory for a cgroup which has @ss enabled on it, try
+ * to get the corresponding css and return it. If such css doesn't exist
+ * or can't be pinned, an ERR_PTR value is returned.
+ */
+struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
+ struct cgroup_subsys *ss)
+{
+ struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
+ struct file_system_type *s_type = dentry->d_sb->s_type;
+ struct cgroup_subsys_state *css = NULL;
+ struct cgroup *cgrp;
+
+ /* is @dentry a cgroup dir? */
+ if ((s_type != &cgroup_fs_type && s_type != &cgroup2_fs_type) ||
+ !kn || kernfs_type(kn) != KERNFS_DIR)
+ return ERR_PTR(-EBADF);
+
+ rcu_read_lock();
+
+ /*
+ * This path doesn't originate from kernfs and @kn could already
+ * have been or be removed at any point. @kn->priv is RCU
+ * protected for this access. See css_release_work_fn() for details.
+ */
+ cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
+ if (cgrp)
+ css = cgroup_css(cgrp, ss);
+
+ if (!css || !css_tryget_online(css))
+ css = ERR_PTR(-ENOENT);
+
+ rcu_read_unlock();
+ return css;
+}
+
+/**
+ * css_from_id - lookup css by id
+ * @id: the cgroup id
+ * @ss: cgroup subsys to be looked into
+ *
+ * Returns the css if there's valid one with @id, otherwise returns NULL.
+ * Should be called under rcu_read_lock().
+ */
+struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
+{
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ return idr_find(&ss->css_idr, id);
+}
+
+/**
+ * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path
+ * @path: path on the default hierarchy
+ *
+ * Find the cgroup at @path on the default hierarchy, increment its
+ * reference count and return it. Returns pointer to the found cgroup on
+ * success, ERR_PTR(-ENOENT) if @path doesn't exist or if the cgroup has already
+ * been released and ERR_PTR(-ENOTDIR) if @path points to a non-directory.
+ */
+struct cgroup *cgroup_get_from_path(const char *path)
+{
+ struct kernfs_node *kn;
+ struct cgroup *cgrp = ERR_PTR(-ENOENT);
+ struct cgroup *root_cgrp;
+
+ root_cgrp = current_cgns_cgroup_dfl();
+ kn = kernfs_walk_and_get(root_cgrp->kn, path);
+ if (!kn)
+ goto out;
+
+ if (kernfs_type(kn) != KERNFS_DIR) {
+ cgrp = ERR_PTR(-ENOTDIR);
+ goto out_kernfs;
+ }
+
+ rcu_read_lock();
+
+ cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
+ if (!cgrp || !cgroup_tryget(cgrp))
+ cgrp = ERR_PTR(-ENOENT);
+
+ rcu_read_unlock();
+
+out_kernfs:
+ kernfs_put(kn);
+out:
+ return cgrp;
+}
+EXPORT_SYMBOL_GPL(cgroup_get_from_path);
+
+/**
+ * cgroup_v1v2_get_from_fd - get a cgroup pointer from a fd
+ * @fd: fd obtained by open(cgroup_dir)
+ *
+ * Find the cgroup from a fd which should be obtained
+ * by opening a cgroup directory. Returns a pointer to the
+ * cgroup on success. ERR_PTR is returned if the cgroup
+ * cannot be found.
+ */
+struct cgroup *cgroup_v1v2_get_from_fd(int fd)
+{
+ struct cgroup *cgrp;
+ struct fd f = fdget_raw(fd);
+ if (!f.file)
+ return ERR_PTR(-EBADF);
+
+ cgrp = cgroup_v1v2_get_from_file(f.file);
+ fdput(f);
+ return cgrp;
+}
+
+/**
+ * cgroup_get_from_fd - same as cgroup_v1v2_get_from_fd, but only supports
+ * cgroup2.
+ * @fd: fd obtained by open(cgroup2_dir)
+ */
+struct cgroup *cgroup_get_from_fd(int fd)
+{
+ struct cgroup *cgrp = cgroup_v1v2_get_from_fd(fd);
+
+ if (IS_ERR(cgrp))
+ return ERR_CAST(cgrp);
+
+ if (!cgroup_on_dfl(cgrp)) {
+ cgroup_put(cgrp);
+ return ERR_PTR(-EBADF);
+ }
+ return cgrp;
+}
+EXPORT_SYMBOL_GPL(cgroup_get_from_fd);
+
+static u64 power_of_ten(int power)
+{
+ u64 v = 1;
+ while (power--)
+ v *= 10;
+ return v;
+}
+
+/**
+ * cgroup_parse_float - parse a floating number
+ * @input: input string
+ * @dec_shift: number of decimal digits to shift
+ * @v: output
+ *
+ * Parse a decimal floating point number in @input and store the result in
+ * @v with decimal point right shifted @dec_shift times. For example, if
+ * @input is "12.3456" and @dec_shift is 3, *@v will be set to 12345.
+ * Returns 0 on success, -errno otherwise.
+ *
+ * There's nothing cgroup specific about this function except that it's
+ * currently the only user.
+ */
+int cgroup_parse_float(const char *input, unsigned dec_shift, s64 *v)
+{
+ s64 whole, frac = 0;
+ int fstart = 0, fend = 0, flen;
+
+ if (!sscanf(input, "%lld.%n%lld%n", &whole, &fstart, &frac, &fend))
+ return -EINVAL;
+ if (frac < 0)
+ return -EINVAL;
+
+ flen = fend > fstart ? fend - fstart : 0;
+ if (flen < dec_shift)
+ frac *= power_of_ten(dec_shift - flen);
+ else
+ frac = DIV_ROUND_CLOSEST_ULL(frac, power_of_ten(flen - dec_shift));
+
+ *v = whole * power_of_ten(dec_shift) + frac;
+ return 0;
+}
+
+/*
+ * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data
+ * definition in cgroup-defs.h.
+ */
+#ifdef CONFIG_SOCK_CGROUP_DATA
+
+void cgroup_sk_alloc(struct sock_cgroup_data *skcd)
+{
+ struct cgroup *cgroup;
+
+ rcu_read_lock();
+ /* Don't associate the sock with unrelated interrupted task's cgroup. */
+ if (in_interrupt()) {
+ cgroup = &cgrp_dfl_root.cgrp;
+ cgroup_get(cgroup);
+ goto out;
+ }
+
+ while (true) {
+ struct css_set *cset;
+
+ cset = task_css_set(current);
+ if (likely(cgroup_tryget(cset->dfl_cgrp))) {
+ cgroup = cset->dfl_cgrp;
+ break;
+ }
+ cpu_relax();
+ }
+out:
+ skcd->cgroup = cgroup;
+ cgroup_bpf_get(cgroup);
+ rcu_read_unlock();
+}
+
+void cgroup_sk_clone(struct sock_cgroup_data *skcd)
+{
+ struct cgroup *cgrp = sock_cgroup_ptr(skcd);
+
+ /*
+ * We might be cloning a socket which is left in an empty
+ * cgroup and the cgroup might have already been rmdir'd.
+ * Don't use cgroup_get_live().
+ */
+ cgroup_get(cgrp);
+ cgroup_bpf_get(cgrp);
+}
+
+void cgroup_sk_free(struct sock_cgroup_data *skcd)
+{
+ struct cgroup *cgrp = sock_cgroup_ptr(skcd);
+
+ cgroup_bpf_put(cgrp);
+ cgroup_put(cgrp);
+}
+
+#endif /* CONFIG_SOCK_CGROUP_DATA */
+
+#ifdef CONFIG_SYSFS
+static ssize_t show_delegatable_files(struct cftype *files, char *buf,
+ ssize_t size, const char *prefix)
+{
+ struct cftype *cft;
+ ssize_t ret = 0;
+
+ for (cft = files; cft && cft->name[0] != '\0'; cft++) {
+ if (!(cft->flags & CFTYPE_NS_DELEGATABLE))
+ continue;
+
+ if (prefix)
+ ret += snprintf(buf + ret, size - ret, "%s.", prefix);
+
+ ret += snprintf(buf + ret, size - ret, "%s\n", cft->name);
+
+ if (WARN_ON(ret >= size))
+ break;
+ }
+
+ return ret;
+}
+
+static ssize_t delegate_show(struct kobject *kobj, struct kobj_attribute *attr,
+ char *buf)
+{
+ struct cgroup_subsys *ss;
+ int ssid;
+ ssize_t ret = 0;
+
+ ret = show_delegatable_files(cgroup_base_files, buf + ret,
+ PAGE_SIZE - ret, NULL);
+ if (cgroup_psi_enabled())
+ ret += show_delegatable_files(cgroup_psi_files, buf + ret,
+ PAGE_SIZE - ret, NULL);
+
+ for_each_subsys(ss, ssid)
+ ret += show_delegatable_files(ss->dfl_cftypes, buf + ret,
+ PAGE_SIZE - ret,
+ cgroup_subsys_name[ssid]);
+
+ return ret;
+}
+static struct kobj_attribute cgroup_delegate_attr = __ATTR_RO(delegate);
+
+static ssize_t features_show(struct kobject *kobj, struct kobj_attribute *attr,
+ char *buf)
+{
+ return snprintf(buf, PAGE_SIZE,
+ "nsdelegate\n"
+ "favordynmods\n"
+ "memory_localevents\n"
+ "memory_recursiveprot\n");
+}
+static struct kobj_attribute cgroup_features_attr = __ATTR_RO(features);
+
+static struct attribute *cgroup_sysfs_attrs[] = {
+ &cgroup_delegate_attr.attr,
+ &cgroup_features_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group cgroup_sysfs_attr_group = {
+ .attrs = cgroup_sysfs_attrs,
+ .name = "cgroup",
+};
+
+static int __init cgroup_sysfs_init(void)
+{
+ return sysfs_create_group(kernel_kobj, &cgroup_sysfs_attr_group);
+}
+subsys_initcall(cgroup_sysfs_init);
+
+#endif /* CONFIG_SYSFS */
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
new file mode 100644
index 0000000000..4749e0c86c
--- /dev/null
+++ b/kernel/cgroup/cpuset.c
@@ -0,0 +1,4321 @@
+/*
+ * kernel/cpuset.c
+ *
+ * Processor and Memory placement constraints for sets of tasks.
+ *
+ * Copyright (C) 2003 BULL SA.
+ * Copyright (C) 2004-2007 Silicon Graphics, Inc.
+ * Copyright (C) 2006 Google, Inc
+ *
+ * Portions derived from Patrick Mochel's sysfs code.
+ * sysfs is Copyright (c) 2001-3 Patrick Mochel
+ *
+ * 2003-10-10 Written by Simon Derr.
+ * 2003-10-22 Updates by Stephen Hemminger.
+ * 2004 May-July Rework by Paul Jackson.
+ * 2006 Rework by Paul Menage to use generic cgroups
+ * 2008 Rework of the scheduler domains and CPU hotplug handling
+ * by Max Krasnyansky
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/cpuset.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mempolicy.h>
+#include <linux/mm.h>
+#include <linux/memory.h>
+#include <linux/export.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+#include <linux/sched/deadline.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/task.h>
+#include <linux/security.h>
+#include <linux/spinlock.h>
+#include <linux/oom.h>
+#include <linux/sched/isolation.h>
+#include <linux/cgroup.h>
+#include <linux/wait.h>
+
+DEFINE_STATIC_KEY_FALSE(cpusets_pre_enable_key);
+DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key);
+
+/*
+ * There could be abnormal cpuset configurations for cpu or memory
+ * node binding, add this key to provide a quick low-cost judgment
+ * of the situation.
+ */
+DEFINE_STATIC_KEY_FALSE(cpusets_insane_config_key);
+
+/* See "Frequency meter" comments, below. */
+
+struct fmeter {
+ int cnt; /* unprocessed events count */
+ int val; /* most recent output value */
+ time64_t time; /* clock (secs) when val computed */
+ spinlock_t lock; /* guards read or write of above */
+};
+
+/*
+ * Invalid partition error code
+ */
+enum prs_errcode {
+ PERR_NONE = 0,
+ PERR_INVCPUS,
+ PERR_INVPARENT,
+ PERR_NOTPART,
+ PERR_NOTEXCL,
+ PERR_NOCPUS,
+ PERR_HOTPLUG,
+ PERR_CPUSEMPTY,
+};
+
+static const char * const perr_strings[] = {
+ [PERR_INVCPUS] = "Invalid cpu list in cpuset.cpus",
+ [PERR_INVPARENT] = "Parent is an invalid partition root",
+ [PERR_NOTPART] = "Parent is not a partition root",
+ [PERR_NOTEXCL] = "Cpu list in cpuset.cpus not exclusive",
+ [PERR_NOCPUS] = "Parent unable to distribute cpu downstream",
+ [PERR_HOTPLUG] = "No cpu available due to hotplug",
+ [PERR_CPUSEMPTY] = "cpuset.cpus is empty",
+};
+
+struct cpuset {
+ struct cgroup_subsys_state css;
+
+ unsigned long flags; /* "unsigned long" so bitops work */
+
+ /*
+ * On default hierarchy:
+ *
+ * The user-configured masks can only be changed by writing to
+ * cpuset.cpus and cpuset.mems, and won't be limited by the
+ * parent masks.
+ *
+ * The effective masks is the real masks that apply to the tasks
+ * in the cpuset. They may be changed if the configured masks are
+ * changed or hotplug happens.
+ *
+ * effective_mask == configured_mask & parent's effective_mask,
+ * and if it ends up empty, it will inherit the parent's mask.
+ *
+ *
+ * On legacy hierarchy:
+ *
+ * The user-configured masks are always the same with effective masks.
+ */
+
+ /* user-configured CPUs and Memory Nodes allow to tasks */
+ cpumask_var_t cpus_allowed;
+ nodemask_t mems_allowed;
+
+ /* effective CPUs and Memory Nodes allow to tasks */
+ cpumask_var_t effective_cpus;
+ nodemask_t effective_mems;
+
+ /*
+ * CPUs allocated to child sub-partitions (default hierarchy only)
+ * - CPUs granted by the parent = effective_cpus U subparts_cpus
+ * - effective_cpus and subparts_cpus are mutually exclusive.
+ *
+ * effective_cpus contains only onlined CPUs, but subparts_cpus
+ * may have offlined ones.
+ */
+ cpumask_var_t subparts_cpus;
+
+ /*
+ * This is old Memory Nodes tasks took on.
+ *
+ * - top_cpuset.old_mems_allowed is initialized to mems_allowed.
+ * - A new cpuset's old_mems_allowed is initialized when some
+ * task is moved into it.
+ * - old_mems_allowed is used in cpuset_migrate_mm() when we change
+ * cpuset.mems_allowed and have tasks' nodemask updated, and
+ * then old_mems_allowed is updated to mems_allowed.
+ */
+ nodemask_t old_mems_allowed;
+
+ struct fmeter fmeter; /* memory_pressure filter */
+
+ /*
+ * Tasks are being attached to this cpuset. Used to prevent
+ * zeroing cpus/mems_allowed between ->can_attach() and ->attach().
+ */
+ int attach_in_progress;
+
+ /* partition number for rebuild_sched_domains() */
+ int pn;
+
+ /* for custom sched domain */
+ int relax_domain_level;
+
+ /* number of CPUs in subparts_cpus */
+ int nr_subparts_cpus;
+
+ /* partition root state */
+ int partition_root_state;
+
+ /*
+ * Default hierarchy only:
+ * use_parent_ecpus - set if using parent's effective_cpus
+ * child_ecpus_count - # of children with use_parent_ecpus set
+ */
+ int use_parent_ecpus;
+ int child_ecpus_count;
+
+ /*
+ * number of SCHED_DEADLINE tasks attached to this cpuset, so that we
+ * know when to rebuild associated root domain bandwidth information.
+ */
+ int nr_deadline_tasks;
+ int nr_migrate_dl_tasks;
+ u64 sum_migrate_dl_bw;
+
+ /* Invalid partition error code, not lock protected */
+ enum prs_errcode prs_err;
+
+ /* Handle for cpuset.cpus.partition */
+ struct cgroup_file partition_file;
+};
+
+/*
+ * Partition root states:
+ *
+ * 0 - member (not a partition root)
+ * 1 - partition root
+ * 2 - partition root without load balancing (isolated)
+ * -1 - invalid partition root
+ * -2 - invalid isolated partition root
+ */
+#define PRS_MEMBER 0
+#define PRS_ROOT 1
+#define PRS_ISOLATED 2
+#define PRS_INVALID_ROOT -1
+#define PRS_INVALID_ISOLATED -2
+
+static inline bool is_prs_invalid(int prs_state)
+{
+ return prs_state < 0;
+}
+
+/*
+ * Temporary cpumasks for working with partitions that are passed among
+ * functions to avoid memory allocation in inner functions.
+ */
+struct tmpmasks {
+ cpumask_var_t addmask, delmask; /* For partition root */
+ cpumask_var_t new_cpus; /* For update_cpumasks_hier() */
+};
+
+static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)
+{
+ return css ? container_of(css, struct cpuset, css) : NULL;
+}
+
+/* Retrieve the cpuset for a task */
+static inline struct cpuset *task_cs(struct task_struct *task)
+{
+ return css_cs(task_css(task, cpuset_cgrp_id));
+}
+
+static inline struct cpuset *parent_cs(struct cpuset *cs)
+{
+ return css_cs(cs->css.parent);
+}
+
+void inc_dl_tasks_cs(struct task_struct *p)
+{
+ struct cpuset *cs = task_cs(p);
+
+ cs->nr_deadline_tasks++;
+}
+
+void dec_dl_tasks_cs(struct task_struct *p)
+{
+ struct cpuset *cs = task_cs(p);
+
+ cs->nr_deadline_tasks--;
+}
+
+/* bits in struct cpuset flags field */
+typedef enum {
+ CS_ONLINE,
+ CS_CPU_EXCLUSIVE,
+ CS_MEM_EXCLUSIVE,
+ CS_MEM_HARDWALL,
+ CS_MEMORY_MIGRATE,
+ CS_SCHED_LOAD_BALANCE,
+ CS_SPREAD_PAGE,
+ CS_SPREAD_SLAB,
+} cpuset_flagbits_t;
+
+/* convenient tests for these bits */
+static inline bool is_cpuset_online(struct cpuset *cs)
+{
+ return test_bit(CS_ONLINE, &cs->flags) && !css_is_dying(&cs->css);
+}
+
+static inline int is_cpu_exclusive(const struct cpuset *cs)
+{
+ return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
+}
+
+static inline int is_mem_exclusive(const struct cpuset *cs)
+{
+ return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
+}
+
+static inline int is_mem_hardwall(const struct cpuset *cs)
+{
+ return test_bit(CS_MEM_HARDWALL, &cs->flags);
+}
+
+static inline int is_sched_load_balance(const struct cpuset *cs)
+{
+ return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
+}
+
+static inline int is_memory_migrate(const struct cpuset *cs)
+{
+ return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
+}
+
+static inline int is_spread_page(const struct cpuset *cs)
+{
+ return test_bit(CS_SPREAD_PAGE, &cs->flags);
+}
+
+static inline int is_spread_slab(const struct cpuset *cs)
+{
+ return test_bit(CS_SPREAD_SLAB, &cs->flags);
+}
+
+static inline int is_partition_valid(const struct cpuset *cs)
+{
+ return cs->partition_root_state > 0;
+}
+
+static inline int is_partition_invalid(const struct cpuset *cs)
+{
+ return cs->partition_root_state < 0;
+}
+
+/*
+ * Callers should hold callback_lock to modify partition_root_state.
+ */
+static inline void make_partition_invalid(struct cpuset *cs)
+{
+ if (is_partition_valid(cs))
+ cs->partition_root_state = -cs->partition_root_state;
+}
+
+/*
+ * Send notification event of whenever partition_root_state changes.
+ */
+static inline void notify_partition_change(struct cpuset *cs, int old_prs)
+{
+ if (old_prs == cs->partition_root_state)
+ return;
+ cgroup_file_notify(&cs->partition_file);
+
+ /* Reset prs_err if not invalid */
+ if (is_partition_valid(cs))
+ WRITE_ONCE(cs->prs_err, PERR_NONE);
+}
+
+static struct cpuset top_cpuset = {
+ .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
+ (1 << CS_MEM_EXCLUSIVE)),
+ .partition_root_state = PRS_ROOT,
+};
+
+/**
+ * cpuset_for_each_child - traverse online children of a cpuset
+ * @child_cs: loop cursor pointing to the current child
+ * @pos_css: used for iteration
+ * @parent_cs: target cpuset to walk children of
+ *
+ * Walk @child_cs through the online children of @parent_cs. Must be used
+ * with RCU read locked.
+ */
+#define cpuset_for_each_child(child_cs, pos_css, parent_cs) \
+ css_for_each_child((pos_css), &(parent_cs)->css) \
+ if (is_cpuset_online(((child_cs) = css_cs((pos_css)))))
+
+/**
+ * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants
+ * @des_cs: loop cursor pointing to the current descendant
+ * @pos_css: used for iteration
+ * @root_cs: target cpuset to walk ancestor of
+ *
+ * Walk @des_cs through the online descendants of @root_cs. Must be used
+ * with RCU read locked. The caller may modify @pos_css by calling
+ * css_rightmost_descendant() to skip subtree. @root_cs is included in the
+ * iteration and the first node to be visited.
+ */
+#define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs) \
+ css_for_each_descendant_pre((pos_css), &(root_cs)->css) \
+ if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
+
+/*
+ * There are two global locks guarding cpuset structures - cpuset_mutex and
+ * callback_lock. We also require taking task_lock() when dereferencing a
+ * task's cpuset pointer. See "The task_lock() exception", at the end of this
+ * comment. The cpuset code uses only cpuset_mutex. Other kernel subsystems
+ * can use cpuset_lock()/cpuset_unlock() to prevent change to cpuset
+ * structures. Note that cpuset_mutex needs to be a mutex as it is used in
+ * paths that rely on priority inheritance (e.g. scheduler - on RT) for
+ * correctness.
+ *
+ * A task must hold both locks to modify cpusets. If a task holds
+ * cpuset_mutex, it blocks others, ensuring that it is the only task able to
+ * also acquire callback_lock and be able to modify cpusets. It can perform
+ * various checks on the cpuset structure first, knowing nothing will change.
+ * It can also allocate memory while just holding cpuset_mutex. While it is
+ * performing these checks, various callback routines can briefly acquire
+ * callback_lock to query cpusets. Once it is ready to make the changes, it
+ * takes callback_lock, blocking everyone else.
+ *
+ * Calls to the kernel memory allocator can not be made while holding
+ * callback_lock, as that would risk double tripping on callback_lock
+ * from one of the callbacks into the cpuset code from within
+ * __alloc_pages().
+ *
+ * If a task is only holding callback_lock, then it has read-only
+ * access to cpusets.
+ *
+ * Now, the task_struct fields mems_allowed and mempolicy may be changed
+ * by other task, we use alloc_lock in the task_struct fields to protect
+ * them.
+ *
+ * The cpuset_common_file_read() handlers only hold callback_lock across
+ * small pieces of code, such as when reading out possibly multi-word
+ * cpumasks and nodemasks.
+ *
+ * Accessing a task's cpuset should be done in accordance with the
+ * guidelines for accessing subsystem state in kernel/cgroup.c
+ */
+
+static DEFINE_MUTEX(cpuset_mutex);
+
+void cpuset_lock(void)
+{
+ mutex_lock(&cpuset_mutex);
+}
+
+void cpuset_unlock(void)
+{
+ mutex_unlock(&cpuset_mutex);
+}
+
+static DEFINE_SPINLOCK(callback_lock);
+
+static struct workqueue_struct *cpuset_migrate_mm_wq;
+
+/*
+ * CPU / memory hotplug is handled asynchronously.
+ */
+static void cpuset_hotplug_workfn(struct work_struct *work);
+static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
+
+static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);
+
+static inline void check_insane_mems_config(nodemask_t *nodes)
+{
+ if (!cpusets_insane_config() &&
+ movable_only_nodes(nodes)) {
+ static_branch_enable(&cpusets_insane_config_key);
+ pr_info("Unsupported (movable nodes only) cpuset configuration detected (nmask=%*pbl)!\n"
+ "Cpuset allocations might fail even with a lot of memory available.\n",
+ nodemask_pr_args(nodes));
+ }
+}
+
+/*
+ * Cgroup v2 behavior is used on the "cpus" and "mems" control files when
+ * on default hierarchy or when the cpuset_v2_mode flag is set by mounting
+ * the v1 cpuset cgroup filesystem with the "cpuset_v2_mode" mount option.
+ * With v2 behavior, "cpus" and "mems" are always what the users have
+ * requested and won't be changed by hotplug events. Only the effective
+ * cpus or mems will be affected.
+ */
+static inline bool is_in_v2_mode(void)
+{
+ return cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||
+ (cpuset_cgrp_subsys.root->flags & CGRP_ROOT_CPUSET_V2_MODE);
+}
+
+/**
+ * partition_is_populated - check if partition has tasks
+ * @cs: partition root to be checked
+ * @excluded_child: a child cpuset to be excluded in task checking
+ * Return: true if there are tasks, false otherwise
+ *
+ * It is assumed that @cs is a valid partition root. @excluded_child should
+ * be non-NULL when this cpuset is going to become a partition itself.
+ */
+static inline bool partition_is_populated(struct cpuset *cs,
+ struct cpuset *excluded_child)
+{
+ struct cgroup_subsys_state *css;
+ struct cpuset *child;
+
+ if (cs->css.cgroup->nr_populated_csets)
+ return true;
+ if (!excluded_child && !cs->nr_subparts_cpus)
+ return cgroup_is_populated(cs->css.cgroup);
+
+ rcu_read_lock();
+ cpuset_for_each_child(child, css, cs) {
+ if (child == excluded_child)
+ continue;
+ if (is_partition_valid(child))
+ continue;
+ if (cgroup_is_populated(child->css.cgroup)) {
+ rcu_read_unlock();
+ return true;
+ }
+ }
+ rcu_read_unlock();
+ return false;
+}
+
+/*
+ * Return in pmask the portion of a task's cpusets's cpus_allowed that
+ * are online and are capable of running the task. If none are found,
+ * walk up the cpuset hierarchy until we find one that does have some
+ * appropriate cpus.
+ *
+ * One way or another, we guarantee to return some non-empty subset
+ * of cpu_online_mask.
+ *
+ * Call with callback_lock or cpuset_mutex held.
+ */
+static void guarantee_online_cpus(struct task_struct *tsk,
+ struct cpumask *pmask)
+{
+ const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
+ struct cpuset *cs;
+
+ if (WARN_ON(!cpumask_and(pmask, possible_mask, cpu_online_mask)))
+ cpumask_copy(pmask, cpu_online_mask);
+
+ rcu_read_lock();
+ cs = task_cs(tsk);
+
+ while (!cpumask_intersects(cs->effective_cpus, pmask)) {
+ cs = parent_cs(cs);
+ if (unlikely(!cs)) {
+ /*
+ * The top cpuset doesn't have any online cpu as a
+ * consequence of a race between cpuset_hotplug_work
+ * and cpu hotplug notifier. But we know the top
+ * cpuset's effective_cpus is on its way to be
+ * identical to cpu_online_mask.
+ */
+ goto out_unlock;
+ }
+ }
+ cpumask_and(pmask, pmask, cs->effective_cpus);
+
+out_unlock:
+ rcu_read_unlock();
+}
+
+/*
+ * Return in *pmask the portion of a cpusets's mems_allowed that
+ * are online, with memory. If none are online with memory, walk
+ * up the cpuset hierarchy until we find one that does have some
+ * online mems. The top cpuset always has some mems online.
+ *
+ * One way or another, we guarantee to return some non-empty subset
+ * of node_states[N_MEMORY].
+ *
+ * Call with callback_lock or cpuset_mutex held.
+ */
+static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
+{
+ while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY]))
+ cs = parent_cs(cs);
+ nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]);
+}
+
+/*
+ * update task's spread flag if cpuset's page/slab spread flag is set
+ *
+ * Call with callback_lock or cpuset_mutex held. The check can be skipped
+ * if on default hierarchy.
+ */
+static void cpuset_update_task_spread_flags(struct cpuset *cs,
+ struct task_struct *tsk)
+{
+ if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys))
+ return;
+
+ if (is_spread_page(cs))
+ task_set_spread_page(tsk);
+ else
+ task_clear_spread_page(tsk);
+
+ if (is_spread_slab(cs))
+ task_set_spread_slab(tsk);
+ else
+ task_clear_spread_slab(tsk);
+}
+
+/*
+ * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
+ *
+ * One cpuset is a subset of another if all its allowed CPUs and
+ * Memory Nodes are a subset of the other, and its exclusive flags
+ * are only set if the other's are set. Call holding cpuset_mutex.
+ */
+
+static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
+{
+ return cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
+ nodes_subset(p->mems_allowed, q->mems_allowed) &&
+ is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
+ is_mem_exclusive(p) <= is_mem_exclusive(q);
+}
+
+/**
+ * alloc_cpumasks - allocate three cpumasks for cpuset
+ * @cs: the cpuset that have cpumasks to be allocated.
+ * @tmp: the tmpmasks structure pointer
+ * Return: 0 if successful, -ENOMEM otherwise.
+ *
+ * Only one of the two input arguments should be non-NULL.
+ */
+static inline int alloc_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
+{
+ cpumask_var_t *pmask1, *pmask2, *pmask3;
+
+ if (cs) {
+ pmask1 = &cs->cpus_allowed;
+ pmask2 = &cs->effective_cpus;
+ pmask3 = &cs->subparts_cpus;
+ } else {
+ pmask1 = &tmp->new_cpus;
+ pmask2 = &tmp->addmask;
+ pmask3 = &tmp->delmask;
+ }
+
+ if (!zalloc_cpumask_var(pmask1, GFP_KERNEL))
+ return -ENOMEM;
+
+ if (!zalloc_cpumask_var(pmask2, GFP_KERNEL))
+ goto free_one;
+
+ if (!zalloc_cpumask_var(pmask3, GFP_KERNEL))
+ goto free_two;
+
+ return 0;
+
+free_two:
+ free_cpumask_var(*pmask2);
+free_one:
+ free_cpumask_var(*pmask1);
+ return -ENOMEM;
+}
+
+/**
+ * free_cpumasks - free cpumasks in a tmpmasks structure
+ * @cs: the cpuset that have cpumasks to be free.
+ * @tmp: the tmpmasks structure pointer
+ */
+static inline void free_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
+{
+ if (cs) {
+ free_cpumask_var(cs->cpus_allowed);
+ free_cpumask_var(cs->effective_cpus);
+ free_cpumask_var(cs->subparts_cpus);
+ }
+ if (tmp) {
+ free_cpumask_var(tmp->new_cpus);
+ free_cpumask_var(tmp->addmask);
+ free_cpumask_var(tmp->delmask);
+ }
+}
+
+/**
+ * alloc_trial_cpuset - allocate a trial cpuset
+ * @cs: the cpuset that the trial cpuset duplicates
+ */
+static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
+{
+ struct cpuset *trial;
+
+ trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
+ if (!trial)
+ return NULL;
+
+ if (alloc_cpumasks(trial, NULL)) {
+ kfree(trial);
+ return NULL;
+ }
+
+ cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
+ cpumask_copy(trial->effective_cpus, cs->effective_cpus);
+ return trial;
+}
+
+/**
+ * free_cpuset - free the cpuset
+ * @cs: the cpuset to be freed
+ */
+static inline void free_cpuset(struct cpuset *cs)
+{
+ free_cpumasks(cs, NULL);
+ kfree(cs);
+}
+
+/*
+ * validate_change_legacy() - Validate conditions specific to legacy (v1)
+ * behavior.
+ */
+static int validate_change_legacy(struct cpuset *cur, struct cpuset *trial)
+{
+ struct cgroup_subsys_state *css;
+ struct cpuset *c, *par;
+ int ret;
+
+ WARN_ON_ONCE(!rcu_read_lock_held());
+
+ /* Each of our child cpusets must be a subset of us */
+ ret = -EBUSY;
+ cpuset_for_each_child(c, css, cur)
+ if (!is_cpuset_subset(c, trial))
+ goto out;
+
+ /* On legacy hierarchy, we must be a subset of our parent cpuset. */
+ ret = -EACCES;
+ par = parent_cs(cur);
+ if (par && !is_cpuset_subset(trial, par))
+ goto out;
+
+ ret = 0;
+out:
+ return ret;
+}
+
+/*
+ * validate_change() - Used to validate that any proposed cpuset change
+ * follows the structural rules for cpusets.
+ *
+ * If we replaced the flag and mask values of the current cpuset
+ * (cur) with those values in the trial cpuset (trial), would
+ * our various subset and exclusive rules still be valid? Presumes
+ * cpuset_mutex held.
+ *
+ * 'cur' is the address of an actual, in-use cpuset. Operations
+ * such as list traversal that depend on the actual address of the
+ * cpuset in the list must use cur below, not trial.
+ *
+ * 'trial' is the address of bulk structure copy of cur, with
+ * perhaps one or more of the fields cpus_allowed, mems_allowed,
+ * or flags changed to new, trial values.
+ *
+ * Return 0 if valid, -errno if not.
+ */
+
+static int validate_change(struct cpuset *cur, struct cpuset *trial)
+{
+ struct cgroup_subsys_state *css;
+ struct cpuset *c, *par;
+ int ret = 0;
+
+ rcu_read_lock();
+
+ if (!is_in_v2_mode())
+ ret = validate_change_legacy(cur, trial);
+ if (ret)
+ goto out;
+
+ /* Remaining checks don't apply to root cpuset */
+ if (cur == &top_cpuset)
+ goto out;
+
+ par = parent_cs(cur);
+
+ /*
+ * Cpusets with tasks - existing or newly being attached - can't
+ * be changed to have empty cpus_allowed or mems_allowed.
+ */
+ ret = -ENOSPC;
+ if ((cgroup_is_populated(cur->css.cgroup) || cur->attach_in_progress)) {
+ if (!cpumask_empty(cur->cpus_allowed) &&
+ cpumask_empty(trial->cpus_allowed))
+ goto out;
+ if (!nodes_empty(cur->mems_allowed) &&
+ nodes_empty(trial->mems_allowed))
+ goto out;
+ }
+
+ /*
+ * We can't shrink if we won't have enough room for SCHED_DEADLINE
+ * tasks.
+ */
+ ret = -EBUSY;
+ if (is_cpu_exclusive(cur) &&
+ !cpuset_cpumask_can_shrink(cur->cpus_allowed,
+ trial->cpus_allowed))
+ goto out;
+
+ /*
+ * If either I or some sibling (!= me) is exclusive, we can't
+ * overlap
+ */
+ ret = -EINVAL;
+ cpuset_for_each_child(c, css, par) {
+ if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
+ c != cur &&
+ cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
+ goto out;
+ if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
+ c != cur &&
+ nodes_intersects(trial->mems_allowed, c->mems_allowed))
+ goto out;
+ }
+
+ ret = 0;
+out:
+ rcu_read_unlock();
+ return ret;
+}
+
+#ifdef CONFIG_SMP
+/*
+ * Helper routine for generate_sched_domains().
+ * Do cpusets a, b have overlapping effective cpus_allowed masks?
+ */
+static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
+{
+ return cpumask_intersects(a->effective_cpus, b->effective_cpus);
+}
+
+static void
+update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
+{
+ if (dattr->relax_domain_level < c->relax_domain_level)
+ dattr->relax_domain_level = c->relax_domain_level;
+ return;
+}
+
+static void update_domain_attr_tree(struct sched_domain_attr *dattr,
+ struct cpuset *root_cs)
+{
+ struct cpuset *cp;
+ struct cgroup_subsys_state *pos_css;
+
+ rcu_read_lock();
+ cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
+ /* skip the whole subtree if @cp doesn't have any CPU */
+ if (cpumask_empty(cp->cpus_allowed)) {
+ pos_css = css_rightmost_descendant(pos_css);
+ continue;
+ }
+
+ if (is_sched_load_balance(cp))
+ update_domain_attr(dattr, cp);
+ }
+ rcu_read_unlock();
+}
+
+/* Must be called with cpuset_mutex held. */
+static inline int nr_cpusets(void)
+{
+ /* jump label reference count + the top-level cpuset */
+ return static_key_count(&cpusets_enabled_key.key) + 1;
+}
+
+/*
+ * generate_sched_domains()
+ *
+ * This function builds a partial partition of the systems CPUs
+ * A 'partial partition' is a set of non-overlapping subsets whose
+ * union is a subset of that set.
+ * The output of this function needs to be passed to kernel/sched/core.c
+ * partition_sched_domains() routine, which will rebuild the scheduler's
+ * load balancing domains (sched domains) as specified by that partial
+ * partition.
+ *
+ * See "What is sched_load_balance" in Documentation/admin-guide/cgroup-v1/cpusets.rst
+ * for a background explanation of this.
+ *
+ * Does not return errors, on the theory that the callers of this
+ * routine would rather not worry about failures to rebuild sched
+ * domains when operating in the severe memory shortage situations
+ * that could cause allocation failures below.
+ *
+ * Must be called with cpuset_mutex held.
+ *
+ * The three key local variables below are:
+ * cp - cpuset pointer, used (together with pos_css) to perform a
+ * top-down scan of all cpusets. For our purposes, rebuilding
+ * the schedulers sched domains, we can ignore !is_sched_load_
+ * balance cpusets.
+ * csa - (for CpuSet Array) Array of pointers to all the cpusets
+ * that need to be load balanced, for convenient iterative
+ * access by the subsequent code that finds the best partition,
+ * i.e the set of domains (subsets) of CPUs such that the
+ * cpus_allowed of every cpuset marked is_sched_load_balance
+ * is a subset of one of these domains, while there are as
+ * many such domains as possible, each as small as possible.
+ * doms - Conversion of 'csa' to an array of cpumasks, for passing to
+ * the kernel/sched/core.c routine partition_sched_domains() in a
+ * convenient format, that can be easily compared to the prior
+ * value to determine what partition elements (sched domains)
+ * were changed (added or removed.)
+ *
+ * Finding the best partition (set of domains):
+ * The triple nested loops below over i, j, k scan over the
+ * load balanced cpusets (using the array of cpuset pointers in
+ * csa[]) looking for pairs of cpusets that have overlapping
+ * cpus_allowed, but which don't have the same 'pn' partition
+ * number and gives them in the same partition number. It keeps
+ * looping on the 'restart' label until it can no longer find
+ * any such pairs.
+ *
+ * The union of the cpus_allowed masks from the set of
+ * all cpusets having the same 'pn' value then form the one
+ * element of the partition (one sched domain) to be passed to
+ * partition_sched_domains().
+ */
+static int generate_sched_domains(cpumask_var_t **domains,
+ struct sched_domain_attr **attributes)
+{
+ struct cpuset *cp; /* top-down scan of cpusets */
+ struct cpuset **csa; /* array of all cpuset ptrs */
+ int csn; /* how many cpuset ptrs in csa so far */
+ int i, j, k; /* indices for partition finding loops */
+ cpumask_var_t *doms; /* resulting partition; i.e. sched domains */
+ struct sched_domain_attr *dattr; /* attributes for custom domains */
+ int ndoms = 0; /* number of sched domains in result */
+ int nslot; /* next empty doms[] struct cpumask slot */
+ struct cgroup_subsys_state *pos_css;
+ bool root_load_balance = is_sched_load_balance(&top_cpuset);
+
+ doms = NULL;
+ dattr = NULL;
+ csa = NULL;
+
+ /* Special case for the 99% of systems with one, full, sched domain */
+ if (root_load_balance && !top_cpuset.nr_subparts_cpus) {
+ ndoms = 1;
+ doms = alloc_sched_domains(ndoms);
+ if (!doms)
+ goto done;
+
+ dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
+ if (dattr) {
+ *dattr = SD_ATTR_INIT;
+ update_domain_attr_tree(dattr, &top_cpuset);
+ }
+ cpumask_and(doms[0], top_cpuset.effective_cpus,
+ housekeeping_cpumask(HK_TYPE_DOMAIN));
+
+ goto done;
+ }
+
+ csa = kmalloc_array(nr_cpusets(), sizeof(cp), GFP_KERNEL);
+ if (!csa)
+ goto done;
+ csn = 0;
+
+ rcu_read_lock();
+ if (root_load_balance)
+ csa[csn++] = &top_cpuset;
+ cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {
+ if (cp == &top_cpuset)
+ continue;
+ /*
+ * Continue traversing beyond @cp iff @cp has some CPUs and
+ * isn't load balancing. The former is obvious. The
+ * latter: All child cpusets contain a subset of the
+ * parent's cpus, so just skip them, and then we call
+ * update_domain_attr_tree() to calc relax_domain_level of
+ * the corresponding sched domain.
+ *
+ * If root is load-balancing, we can skip @cp if it
+ * is a subset of the root's effective_cpus.
+ */
+ if (!cpumask_empty(cp->cpus_allowed) &&
+ !(is_sched_load_balance(cp) &&
+ cpumask_intersects(cp->cpus_allowed,
+ housekeeping_cpumask(HK_TYPE_DOMAIN))))
+ continue;
+
+ if (root_load_balance &&
+ cpumask_subset(cp->cpus_allowed, top_cpuset.effective_cpus))
+ continue;
+
+ if (is_sched_load_balance(cp) &&
+ !cpumask_empty(cp->effective_cpus))
+ csa[csn++] = cp;
+
+ /* skip @cp's subtree if not a partition root */
+ if (!is_partition_valid(cp))
+ pos_css = css_rightmost_descendant(pos_css);
+ }
+ rcu_read_unlock();
+
+ for (i = 0; i < csn; i++)
+ csa[i]->pn = i;
+ ndoms = csn;
+
+restart:
+ /* Find the best partition (set of sched domains) */
+ for (i = 0; i < csn; i++) {
+ struct cpuset *a = csa[i];
+ int apn = a->pn;
+
+ for (j = 0; j < csn; j++) {
+ struct cpuset *b = csa[j];
+ int bpn = b->pn;
+
+ if (apn != bpn && cpusets_overlap(a, b)) {
+ for (k = 0; k < csn; k++) {
+ struct cpuset *c = csa[k];
+
+ if (c->pn == bpn)
+ c->pn = apn;
+ }
+ ndoms--; /* one less element */
+ goto restart;
+ }
+ }
+ }
+
+ /*
+ * Now we know how many domains to create.
+ * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
+ */
+ doms = alloc_sched_domains(ndoms);
+ if (!doms)
+ goto done;
+
+ /*
+ * The rest of the code, including the scheduler, can deal with
+ * dattr==NULL case. No need to abort if alloc fails.
+ */
+ dattr = kmalloc_array(ndoms, sizeof(struct sched_domain_attr),
+ GFP_KERNEL);
+
+ for (nslot = 0, i = 0; i < csn; i++) {
+ struct cpuset *a = csa[i];
+ struct cpumask *dp;
+ int apn = a->pn;
+
+ if (apn < 0) {
+ /* Skip completed partitions */
+ continue;
+ }
+
+ dp = doms[nslot];
+
+ if (nslot == ndoms) {
+ static int warnings = 10;
+ if (warnings) {
+ pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n",
+ nslot, ndoms, csn, i, apn);
+ warnings--;
+ }
+ continue;
+ }
+
+ cpumask_clear(dp);
+ if (dattr)
+ *(dattr + nslot) = SD_ATTR_INIT;
+ for (j = i; j < csn; j++) {
+ struct cpuset *b = csa[j];
+
+ if (apn == b->pn) {
+ cpumask_or(dp, dp, b->effective_cpus);
+ cpumask_and(dp, dp, housekeeping_cpumask(HK_TYPE_DOMAIN));
+ if (dattr)
+ update_domain_attr_tree(dattr + nslot, b);
+
+ /* Done with this partition */
+ b->pn = -1;
+ }
+ }
+ nslot++;
+ }
+ BUG_ON(nslot != ndoms);
+
+done:
+ kfree(csa);
+
+ /*
+ * Fallback to the default domain if kmalloc() failed.
+ * See comments in partition_sched_domains().
+ */
+ if (doms == NULL)
+ ndoms = 1;
+
+ *domains = doms;
+ *attributes = dattr;
+ return ndoms;
+}
+
+static void dl_update_tasks_root_domain(struct cpuset *cs)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ if (cs->nr_deadline_tasks == 0)
+ return;
+
+ css_task_iter_start(&cs->css, 0, &it);
+
+ while ((task = css_task_iter_next(&it)))
+ dl_add_task_root_domain(task);
+
+ css_task_iter_end(&it);
+}
+
+static void dl_rebuild_rd_accounting(void)
+{
+ struct cpuset *cs = NULL;
+ struct cgroup_subsys_state *pos_css;
+
+ lockdep_assert_held(&cpuset_mutex);
+ lockdep_assert_cpus_held();
+ lockdep_assert_held(&sched_domains_mutex);
+
+ rcu_read_lock();
+
+ /*
+ * Clear default root domain DL accounting, it will be computed again
+ * if a task belongs to it.
+ */
+ dl_clear_root_domain(&def_root_domain);
+
+ cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
+
+ if (cpumask_empty(cs->effective_cpus)) {
+ pos_css = css_rightmost_descendant(pos_css);
+ continue;
+ }
+
+ css_get(&cs->css);
+
+ rcu_read_unlock();
+
+ dl_update_tasks_root_domain(cs);
+
+ rcu_read_lock();
+ css_put(&cs->css);
+ }
+ rcu_read_unlock();
+}
+
+static void
+partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
+ struct sched_domain_attr *dattr_new)
+{
+ mutex_lock(&sched_domains_mutex);
+ partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
+ dl_rebuild_rd_accounting();
+ mutex_unlock(&sched_domains_mutex);
+}
+
+/*
+ * Rebuild scheduler domains.
+ *
+ * If the flag 'sched_load_balance' of any cpuset with non-empty
+ * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
+ * which has that flag enabled, or if any cpuset with a non-empty
+ * 'cpus' is removed, then call this routine to rebuild the
+ * scheduler's dynamic sched domains.
+ *
+ * Call with cpuset_mutex held. Takes cpus_read_lock().
+ */
+static void rebuild_sched_domains_locked(void)
+{
+ struct cgroup_subsys_state *pos_css;
+ struct sched_domain_attr *attr;
+ cpumask_var_t *doms;
+ struct cpuset *cs;
+ int ndoms;
+
+ lockdep_assert_cpus_held();
+ lockdep_assert_held(&cpuset_mutex);
+
+ /*
+ * If we have raced with CPU hotplug, return early to avoid
+ * passing doms with offlined cpu to partition_sched_domains().
+ * Anyways, cpuset_hotplug_workfn() will rebuild sched domains.
+ *
+ * With no CPUs in any subpartitions, top_cpuset's effective CPUs
+ * should be the same as the active CPUs, so checking only top_cpuset
+ * is enough to detect racing CPU offlines.
+ */
+ if (!top_cpuset.nr_subparts_cpus &&
+ !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
+ return;
+
+ /*
+ * With subpartition CPUs, however, the effective CPUs of a partition
+ * root should be only a subset of the active CPUs. Since a CPU in any
+ * partition root could be offlined, all must be checked.
+ */
+ if (top_cpuset.nr_subparts_cpus) {
+ rcu_read_lock();
+ cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
+ if (!is_partition_valid(cs)) {
+ pos_css = css_rightmost_descendant(pos_css);
+ continue;
+ }
+ if (!cpumask_subset(cs->effective_cpus,
+ cpu_active_mask)) {
+ rcu_read_unlock();
+ return;
+ }
+ }
+ rcu_read_unlock();
+ }
+
+ /* Generate domain masks and attrs */
+ ndoms = generate_sched_domains(&doms, &attr);
+
+ /* Have scheduler rebuild the domains */
+ partition_and_rebuild_sched_domains(ndoms, doms, attr);
+}
+#else /* !CONFIG_SMP */
+static void rebuild_sched_domains_locked(void)
+{
+}
+#endif /* CONFIG_SMP */
+
+void rebuild_sched_domains(void)
+{
+ cpus_read_lock();
+ mutex_lock(&cpuset_mutex);
+ rebuild_sched_domains_locked();
+ mutex_unlock(&cpuset_mutex);
+ cpus_read_unlock();
+}
+
+/**
+ * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
+ * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
+ * @new_cpus: the temp variable for the new effective_cpus mask
+ *
+ * Iterate through each task of @cs updating its cpus_allowed to the
+ * effective cpuset's. As this function is called with cpuset_mutex held,
+ * cpuset membership stays stable. For top_cpuset, task_cpu_possible_mask()
+ * is used instead of effective_cpus to make sure all offline CPUs are also
+ * included as hotplug code won't update cpumasks for tasks in top_cpuset.
+ */
+static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+ bool top_cs = cs == &top_cpuset;
+
+ css_task_iter_start(&cs->css, 0, &it);
+ while ((task = css_task_iter_next(&it))) {
+ const struct cpumask *possible_mask = task_cpu_possible_mask(task);
+
+ if (top_cs) {
+ /*
+ * Percpu kthreads in top_cpuset are ignored
+ */
+ if (kthread_is_per_cpu(task))
+ continue;
+ cpumask_andnot(new_cpus, possible_mask, cs->subparts_cpus);
+ } else {
+ cpumask_and(new_cpus, possible_mask, cs->effective_cpus);
+ }
+ set_cpus_allowed_ptr(task, new_cpus);
+ }
+ css_task_iter_end(&it);
+}
+
+/**
+ * compute_effective_cpumask - Compute the effective cpumask of the cpuset
+ * @new_cpus: the temp variable for the new effective_cpus mask
+ * @cs: the cpuset the need to recompute the new effective_cpus mask
+ * @parent: the parent cpuset
+ *
+ * If the parent has subpartition CPUs, include them in the list of
+ * allowable CPUs in computing the new effective_cpus mask. Since offlined
+ * CPUs are not removed from subparts_cpus, we have to use cpu_active_mask
+ * to mask those out.
+ */
+static void compute_effective_cpumask(struct cpumask *new_cpus,
+ struct cpuset *cs, struct cpuset *parent)
+{
+ if (parent->nr_subparts_cpus && is_partition_valid(cs)) {
+ cpumask_or(new_cpus, parent->effective_cpus,
+ parent->subparts_cpus);
+ cpumask_and(new_cpus, new_cpus, cs->cpus_allowed);
+ cpumask_and(new_cpus, new_cpus, cpu_active_mask);
+ } else {
+ cpumask_and(new_cpus, cs->cpus_allowed, parent->effective_cpus);
+ }
+}
+
+/*
+ * Commands for update_parent_subparts_cpumask
+ */
+enum subparts_cmd {
+ partcmd_enable, /* Enable partition root */
+ partcmd_disable, /* Disable partition root */
+ partcmd_update, /* Update parent's subparts_cpus */
+ partcmd_invalidate, /* Make partition invalid */
+};
+
+static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
+ int turning_on);
+static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs,
+ struct tmpmasks *tmp);
+
+/*
+ * Update partition exclusive flag
+ *
+ * Return: 0 if successful, an error code otherwise
+ */
+static int update_partition_exclusive(struct cpuset *cs, int new_prs)
+{
+ bool exclusive = (new_prs > 0);
+
+ if (exclusive && !is_cpu_exclusive(cs)) {
+ if (update_flag(CS_CPU_EXCLUSIVE, cs, 1))
+ return PERR_NOTEXCL;
+ } else if (!exclusive && is_cpu_exclusive(cs)) {
+ /* Turning off CS_CPU_EXCLUSIVE will not return error */
+ update_flag(CS_CPU_EXCLUSIVE, cs, 0);
+ }
+ return 0;
+}
+
+/*
+ * Update partition load balance flag and/or rebuild sched domain
+ *
+ * Changing load balance flag will automatically call
+ * rebuild_sched_domains_locked().
+ * This function is for cgroup v2 only.
+ */
+static void update_partition_sd_lb(struct cpuset *cs, int old_prs)
+{
+ int new_prs = cs->partition_root_state;
+ bool rebuild_domains = (new_prs > 0) || (old_prs > 0);
+ bool new_lb;
+
+ /*
+ * If cs is not a valid partition root, the load balance state
+ * will follow its parent.
+ */
+ if (new_prs > 0) {
+ new_lb = (new_prs != PRS_ISOLATED);
+ } else {
+ new_lb = is_sched_load_balance(parent_cs(cs));
+ }
+ if (new_lb != !!is_sched_load_balance(cs)) {
+ rebuild_domains = true;
+ if (new_lb)
+ set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
+ else
+ clear_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
+ }
+
+ if (rebuild_domains)
+ rebuild_sched_domains_locked();
+}
+
+/**
+ * update_parent_subparts_cpumask - update subparts_cpus mask of parent cpuset
+ * @cs: The cpuset that requests change in partition root state
+ * @cmd: Partition root state change command
+ * @newmask: Optional new cpumask for partcmd_update
+ * @tmp: Temporary addmask and delmask
+ * Return: 0 or a partition root state error code
+ *
+ * For partcmd_enable, the cpuset is being transformed from a non-partition
+ * root to a partition root. The cpus_allowed mask of the given cpuset will
+ * be put into parent's subparts_cpus and taken away from parent's
+ * effective_cpus. The function will return 0 if all the CPUs listed in
+ * cpus_allowed can be granted or an error code will be returned.
+ *
+ * For partcmd_disable, the cpuset is being transformed from a partition
+ * root back to a non-partition root. Any CPUs in cpus_allowed that are in
+ * parent's subparts_cpus will be taken away from that cpumask and put back
+ * into parent's effective_cpus. 0 will always be returned.
+ *
+ * For partcmd_update, if the optional newmask is specified, the cpu list is
+ * to be changed from cpus_allowed to newmask. Otherwise, cpus_allowed is
+ * assumed to remain the same. The cpuset should either be a valid or invalid
+ * partition root. The partition root state may change from valid to invalid
+ * or vice versa. An error code will only be returned if transitioning from
+ * invalid to valid violates the exclusivity rule.
+ *
+ * For partcmd_invalidate, the current partition will be made invalid.
+ *
+ * The partcmd_enable and partcmd_disable commands are used by
+ * update_prstate(). An error code may be returned and the caller will check
+ * for error.
+ *
+ * The partcmd_update command is used by update_cpumasks_hier() with newmask
+ * NULL and update_cpumask() with newmask set. The partcmd_invalidate is used
+ * by update_cpumask() with NULL newmask. In both cases, the callers won't
+ * check for error and so partition_root_state and prs_error will be updated
+ * directly.
+ */
+static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
+ struct cpumask *newmask,
+ struct tmpmasks *tmp)
+{
+ struct cpuset *parent = parent_cs(cs);
+ int adding; /* Moving cpus from effective_cpus to subparts_cpus */
+ int deleting; /* Moving cpus from subparts_cpus to effective_cpus */
+ int old_prs, new_prs;
+ int part_error = PERR_NONE; /* Partition error? */
+
+ lockdep_assert_held(&cpuset_mutex);
+
+ /*
+ * The parent must be a partition root.
+ * The new cpumask, if present, or the current cpus_allowed must
+ * not be empty.
+ */
+ if (!is_partition_valid(parent)) {
+ return is_partition_invalid(parent)
+ ? PERR_INVPARENT : PERR_NOTPART;
+ }
+ if (!newmask && cpumask_empty(cs->cpus_allowed))
+ return PERR_CPUSEMPTY;
+
+ /*
+ * new_prs will only be changed for the partcmd_update and
+ * partcmd_invalidate commands.
+ */
+ adding = deleting = false;
+ old_prs = new_prs = cs->partition_root_state;
+ if (cmd == partcmd_enable) {
+ /*
+ * Enabling partition root is not allowed if cpus_allowed
+ * doesn't overlap parent's cpus_allowed.
+ */
+ if (!cpumask_intersects(cs->cpus_allowed, parent->cpus_allowed))
+ return PERR_INVCPUS;
+
+ /*
+ * A parent can be left with no CPU as long as there is no
+ * task directly associated with the parent partition.
+ */
+ if (cpumask_subset(parent->effective_cpus, cs->cpus_allowed) &&
+ partition_is_populated(parent, cs))
+ return PERR_NOCPUS;
+
+ cpumask_copy(tmp->addmask, cs->cpus_allowed);
+ adding = true;
+ } else if (cmd == partcmd_disable) {
+ /*
+ * Need to remove cpus from parent's subparts_cpus for valid
+ * partition root.
+ */
+ deleting = !is_prs_invalid(old_prs) &&
+ cpumask_and(tmp->delmask, cs->cpus_allowed,
+ parent->subparts_cpus);
+ } else if (cmd == partcmd_invalidate) {
+ if (is_prs_invalid(old_prs))
+ return 0;
+
+ /*
+ * Make the current partition invalid. It is assumed that
+ * invalidation is caused by violating cpu exclusivity rule.
+ */
+ deleting = cpumask_and(tmp->delmask, cs->cpus_allowed,
+ parent->subparts_cpus);
+ if (old_prs > 0) {
+ new_prs = -old_prs;
+ part_error = PERR_NOTEXCL;
+ }
+ } else if (newmask) {
+ /*
+ * partcmd_update with newmask:
+ *
+ * Compute add/delete mask to/from subparts_cpus
+ *
+ * delmask = cpus_allowed & ~newmask & parent->subparts_cpus
+ * addmask = newmask & parent->cpus_allowed
+ * & ~parent->subparts_cpus
+ */
+ cpumask_andnot(tmp->delmask, cs->cpus_allowed, newmask);
+ deleting = cpumask_and(tmp->delmask, tmp->delmask,
+ parent->subparts_cpus);
+
+ cpumask_and(tmp->addmask, newmask, parent->cpus_allowed);
+ adding = cpumask_andnot(tmp->addmask, tmp->addmask,
+ parent->subparts_cpus);
+ /*
+ * Empty cpumask is not allowed
+ */
+ if (cpumask_empty(newmask)) {
+ part_error = PERR_CPUSEMPTY;
+ /*
+ * Make partition invalid if parent's effective_cpus could
+ * become empty and there are tasks in the parent.
+ */
+ } else if (adding &&
+ cpumask_subset(parent->effective_cpus, tmp->addmask) &&
+ !cpumask_intersects(tmp->delmask, cpu_active_mask) &&
+ partition_is_populated(parent, cs)) {
+ part_error = PERR_NOCPUS;
+ adding = false;
+ deleting = cpumask_and(tmp->delmask, cs->cpus_allowed,
+ parent->subparts_cpus);
+ }
+ } else {
+ /*
+ * partcmd_update w/o newmask:
+ *
+ * delmask = cpus_allowed & parent->subparts_cpus
+ * addmask = cpus_allowed & parent->cpus_allowed
+ * & ~parent->subparts_cpus
+ *
+ * This gets invoked either due to a hotplug event or from
+ * update_cpumasks_hier(). This can cause the state of a
+ * partition root to transition from valid to invalid or vice
+ * versa. So we still need to compute the addmask and delmask.
+
+ * A partition error happens when:
+ * 1) Cpuset is valid partition, but parent does not distribute
+ * out any CPUs.
+ * 2) Parent has tasks and all its effective CPUs will have
+ * to be distributed out.
+ */
+ cpumask_and(tmp->addmask, cs->cpus_allowed,
+ parent->cpus_allowed);
+ adding = cpumask_andnot(tmp->addmask, tmp->addmask,
+ parent->subparts_cpus);
+
+ if ((is_partition_valid(cs) && !parent->nr_subparts_cpus) ||
+ (adding &&
+ cpumask_subset(parent->effective_cpus, tmp->addmask) &&
+ partition_is_populated(parent, cs))) {
+ part_error = PERR_NOCPUS;
+ adding = false;
+ }
+
+ if (part_error && is_partition_valid(cs) &&
+ parent->nr_subparts_cpus)
+ deleting = cpumask_and(tmp->delmask, cs->cpus_allowed,
+ parent->subparts_cpus);
+ }
+ if (part_error)
+ WRITE_ONCE(cs->prs_err, part_error);
+
+ if (cmd == partcmd_update) {
+ /*
+ * Check for possible transition between valid and invalid
+ * partition root.
+ */
+ switch (cs->partition_root_state) {
+ case PRS_ROOT:
+ case PRS_ISOLATED:
+ if (part_error)
+ new_prs = -old_prs;
+ break;
+ case PRS_INVALID_ROOT:
+ case PRS_INVALID_ISOLATED:
+ if (!part_error)
+ new_prs = -old_prs;
+ break;
+ }
+ }
+
+ if (!adding && !deleting && (new_prs == old_prs))
+ return 0;
+
+ /*
+ * Transitioning between invalid to valid or vice versa may require
+ * changing CS_CPU_EXCLUSIVE.
+ */
+ if (old_prs != new_prs) {
+ int err = update_partition_exclusive(cs, new_prs);
+
+ if (err)
+ return err;
+ }
+
+ /*
+ * Change the parent's subparts_cpus.
+ * Newly added CPUs will be removed from effective_cpus and
+ * newly deleted ones will be added back to effective_cpus.
+ */
+ spin_lock_irq(&callback_lock);
+ if (adding) {
+ cpumask_or(parent->subparts_cpus,
+ parent->subparts_cpus, tmp->addmask);
+ cpumask_andnot(parent->effective_cpus,
+ parent->effective_cpus, tmp->addmask);
+ }
+ if (deleting) {
+ cpumask_andnot(parent->subparts_cpus,
+ parent->subparts_cpus, tmp->delmask);
+ /*
+ * Some of the CPUs in subparts_cpus might have been offlined.
+ */
+ cpumask_and(tmp->delmask, tmp->delmask, cpu_active_mask);
+ cpumask_or(parent->effective_cpus,
+ parent->effective_cpus, tmp->delmask);
+ }
+
+ parent->nr_subparts_cpus = cpumask_weight(parent->subparts_cpus);
+
+ if (old_prs != new_prs)
+ cs->partition_root_state = new_prs;
+
+ spin_unlock_irq(&callback_lock);
+
+ if (adding || deleting) {
+ update_tasks_cpumask(parent, tmp->addmask);
+ if (parent->child_ecpus_count)
+ update_sibling_cpumasks(parent, cs, tmp);
+ }
+
+ /*
+ * For partcmd_update without newmask, it is being called from
+ * cpuset_hotplug_workfn() where cpus_read_lock() wasn't taken.
+ * Update the load balance flag and scheduling domain if
+ * cpus_read_trylock() is successful.
+ */
+ if ((cmd == partcmd_update) && !newmask && cpus_read_trylock()) {
+ update_partition_sd_lb(cs, old_prs);
+ cpus_read_unlock();
+ }
+
+ notify_partition_change(cs, old_prs);
+ return 0;
+}
+
+/*
+ * update_cpumasks_hier() flags
+ */
+#define HIER_CHECKALL 0x01 /* Check all cpusets with no skipping */
+#define HIER_NO_SD_REBUILD 0x02 /* Don't rebuild sched domains */
+
+/*
+ * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree
+ * @cs: the cpuset to consider
+ * @tmp: temp variables for calculating effective_cpus & partition setup
+ * @force: don't skip any descendant cpusets if set
+ *
+ * When configured cpumask is changed, the effective cpumasks of this cpuset
+ * and all its descendants need to be updated.
+ *
+ * On legacy hierarchy, effective_cpus will be the same with cpu_allowed.
+ *
+ * Called with cpuset_mutex held
+ */
+static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
+ int flags)
+{
+ struct cpuset *cp;
+ struct cgroup_subsys_state *pos_css;
+ bool need_rebuild_sched_domains = false;
+ int old_prs, new_prs;
+
+ rcu_read_lock();
+ cpuset_for_each_descendant_pre(cp, pos_css, cs) {
+ struct cpuset *parent = parent_cs(cp);
+ bool update_parent = false;
+
+ compute_effective_cpumask(tmp->new_cpus, cp, parent);
+
+ /*
+ * If it becomes empty, inherit the effective mask of the
+ * parent, which is guaranteed to have some CPUs unless
+ * it is a partition root that has explicitly distributed
+ * out all its CPUs.
+ */
+ if (is_in_v2_mode() && cpumask_empty(tmp->new_cpus)) {
+ if (is_partition_valid(cp) &&
+ cpumask_equal(cp->cpus_allowed, cp->subparts_cpus))
+ goto update_parent_subparts;
+
+ cpumask_copy(tmp->new_cpus, parent->effective_cpus);
+ if (!cp->use_parent_ecpus) {
+ cp->use_parent_ecpus = true;
+ parent->child_ecpus_count++;
+ }
+ } else if (cp->use_parent_ecpus) {
+ cp->use_parent_ecpus = false;
+ WARN_ON_ONCE(!parent->child_ecpus_count);
+ parent->child_ecpus_count--;
+ }
+
+ /*
+ * Skip the whole subtree if
+ * 1) the cpumask remains the same,
+ * 2) has no partition root state,
+ * 3) HIER_CHECKALL flag not set, and
+ * 4) for v2 load balance state same as its parent.
+ */
+ if (!cp->partition_root_state && !(flags & HIER_CHECKALL) &&
+ cpumask_equal(tmp->new_cpus, cp->effective_cpus) &&
+ (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||
+ (is_sched_load_balance(parent) == is_sched_load_balance(cp)))) {
+ pos_css = css_rightmost_descendant(pos_css);
+ continue;
+ }
+
+update_parent_subparts:
+ /*
+ * update_parent_subparts_cpumask() should have been called
+ * for cs already in update_cpumask(). We should also call
+ * update_tasks_cpumask() again for tasks in the parent
+ * cpuset if the parent's subparts_cpus changes.
+ */
+ old_prs = new_prs = cp->partition_root_state;
+ if ((cp != cs) && old_prs) {
+ switch (parent->partition_root_state) {
+ case PRS_ROOT:
+ case PRS_ISOLATED:
+ update_parent = true;
+ break;
+
+ default:
+ /*
+ * When parent is not a partition root or is
+ * invalid, child partition roots become
+ * invalid too.
+ */
+ if (is_partition_valid(cp))
+ new_prs = -cp->partition_root_state;
+ WRITE_ONCE(cp->prs_err,
+ is_partition_invalid(parent)
+ ? PERR_INVPARENT : PERR_NOTPART);
+ break;
+ }
+ }
+
+ if (!css_tryget_online(&cp->css))
+ continue;
+ rcu_read_unlock();
+
+ if (update_parent) {
+ update_parent_subparts_cpumask(cp, partcmd_update, NULL,
+ tmp);
+ /*
+ * The cpuset partition_root_state may become
+ * invalid. Capture it.
+ */
+ new_prs = cp->partition_root_state;
+ }
+
+ spin_lock_irq(&callback_lock);
+
+ if (cp->nr_subparts_cpus && !is_partition_valid(cp)) {
+ /*
+ * Put all active subparts_cpus back to effective_cpus.
+ */
+ cpumask_or(tmp->new_cpus, tmp->new_cpus,
+ cp->subparts_cpus);
+ cpumask_and(tmp->new_cpus, tmp->new_cpus,
+ cpu_active_mask);
+ cp->nr_subparts_cpus = 0;
+ cpumask_clear(cp->subparts_cpus);
+ }
+
+ cpumask_copy(cp->effective_cpus, tmp->new_cpus);
+ if (cp->nr_subparts_cpus) {
+ /*
+ * Make sure that effective_cpus & subparts_cpus
+ * are mutually exclusive.
+ */
+ cpumask_andnot(cp->effective_cpus, cp->effective_cpus,
+ cp->subparts_cpus);
+ }
+
+ cp->partition_root_state = new_prs;
+ spin_unlock_irq(&callback_lock);
+
+ notify_partition_change(cp, old_prs);
+
+ WARN_ON(!is_in_v2_mode() &&
+ !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
+
+ update_tasks_cpumask(cp, tmp->new_cpus);
+
+ /*
+ * On default hierarchy, inherit the CS_SCHED_LOAD_BALANCE
+ * from parent if current cpuset isn't a valid partition root
+ * and their load balance states differ.
+ */
+ if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
+ !is_partition_valid(cp) &&
+ (is_sched_load_balance(parent) != is_sched_load_balance(cp))) {
+ if (is_sched_load_balance(parent))
+ set_bit(CS_SCHED_LOAD_BALANCE, &cp->flags);
+ else
+ clear_bit(CS_SCHED_LOAD_BALANCE, &cp->flags);
+ }
+
+ /*
+ * On legacy hierarchy, if the effective cpumask of any non-
+ * empty cpuset is changed, we need to rebuild sched domains.
+ * On default hierarchy, the cpuset needs to be a partition
+ * root as well.
+ */
+ if (!cpumask_empty(cp->cpus_allowed) &&
+ is_sched_load_balance(cp) &&
+ (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||
+ is_partition_valid(cp)))
+ need_rebuild_sched_domains = true;
+
+ rcu_read_lock();
+ css_put(&cp->css);
+ }
+ rcu_read_unlock();
+
+ if (need_rebuild_sched_domains && !(flags & HIER_NO_SD_REBUILD))
+ rebuild_sched_domains_locked();
+}
+
+/**
+ * update_sibling_cpumasks - Update siblings cpumasks
+ * @parent: Parent cpuset
+ * @cs: Current cpuset
+ * @tmp: Temp variables
+ */
+static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs,
+ struct tmpmasks *tmp)
+{
+ struct cpuset *sibling;
+ struct cgroup_subsys_state *pos_css;
+
+ lockdep_assert_held(&cpuset_mutex);
+
+ /*
+ * Check all its siblings and call update_cpumasks_hier()
+ * if their use_parent_ecpus flag is set in order for them
+ * to use the right effective_cpus value.
+ *
+ * The update_cpumasks_hier() function may sleep. So we have to
+ * release the RCU read lock before calling it. HIER_NO_SD_REBUILD
+ * flag is used to suppress rebuild of sched domains as the callers
+ * will take care of that.
+ */
+ rcu_read_lock();
+ cpuset_for_each_child(sibling, pos_css, parent) {
+ if (sibling == cs)
+ continue;
+ if (!sibling->use_parent_ecpus)
+ continue;
+ if (!css_tryget_online(&sibling->css))
+ continue;
+
+ rcu_read_unlock();
+ update_cpumasks_hier(sibling, tmp, HIER_NO_SD_REBUILD);
+ rcu_read_lock();
+ css_put(&sibling->css);
+ }
+ rcu_read_unlock();
+}
+
+/**
+ * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
+ * @cs: the cpuset to consider
+ * @trialcs: trial cpuset
+ * @buf: buffer of cpu numbers written to this cpuset
+ */
+static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
+ const char *buf)
+{
+ int retval;
+ struct tmpmasks tmp;
+ bool invalidate = false;
+ int old_prs = cs->partition_root_state;
+
+ /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
+ if (cs == &top_cpuset)
+ return -EACCES;
+
+ /*
+ * An empty cpus_allowed is ok only if the cpuset has no tasks.
+ * Since cpulist_parse() fails on an empty mask, we special case
+ * that parsing. The validate_change() call ensures that cpusets
+ * with tasks have cpus.
+ */
+ if (!*buf) {
+ cpumask_clear(trialcs->cpus_allowed);
+ } else {
+ retval = cpulist_parse(buf, trialcs->cpus_allowed);
+ if (retval < 0)
+ return retval;
+
+ if (!cpumask_subset(trialcs->cpus_allowed,
+ top_cpuset.cpus_allowed))
+ return -EINVAL;
+ }
+
+ /* Nothing to do if the cpus didn't change */
+ if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
+ return 0;
+
+ if (alloc_cpumasks(NULL, &tmp))
+ return -ENOMEM;
+
+ retval = validate_change(cs, trialcs);
+
+ if ((retval == -EINVAL) && cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) {
+ struct cpuset *cp, *parent;
+ struct cgroup_subsys_state *css;
+
+ /*
+ * The -EINVAL error code indicates that partition sibling
+ * CPU exclusivity rule has been violated. We still allow
+ * the cpumask change to proceed while invalidating the
+ * partition. However, any conflicting sibling partitions
+ * have to be marked as invalid too.
+ */
+ invalidate = true;
+ rcu_read_lock();
+ parent = parent_cs(cs);
+ cpuset_for_each_child(cp, css, parent)
+ if (is_partition_valid(cp) &&
+ cpumask_intersects(trialcs->cpus_allowed, cp->cpus_allowed)) {
+ rcu_read_unlock();
+ update_parent_subparts_cpumask(cp, partcmd_invalidate, NULL, &tmp);
+ rcu_read_lock();
+ }
+ rcu_read_unlock();
+ retval = 0;
+ }
+ if (retval < 0)
+ goto out_free;
+
+ if (cs->partition_root_state) {
+ if (invalidate)
+ update_parent_subparts_cpumask(cs, partcmd_invalidate,
+ NULL, &tmp);
+ else
+ update_parent_subparts_cpumask(cs, partcmd_update,
+ trialcs->cpus_allowed, &tmp);
+ }
+
+ compute_effective_cpumask(trialcs->effective_cpus, trialcs,
+ parent_cs(cs));
+ spin_lock_irq(&callback_lock);
+ cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
+
+ /*
+ * Make sure that subparts_cpus, if not empty, is a subset of
+ * cpus_allowed. Clear subparts_cpus if partition not valid or
+ * empty effective cpus with tasks.
+ */
+ if (cs->nr_subparts_cpus) {
+ if (!is_partition_valid(cs) ||
+ (cpumask_subset(trialcs->effective_cpus, cs->subparts_cpus) &&
+ partition_is_populated(cs, NULL))) {
+ cs->nr_subparts_cpus = 0;
+ cpumask_clear(cs->subparts_cpus);
+ } else {
+ cpumask_and(cs->subparts_cpus, cs->subparts_cpus,
+ cs->cpus_allowed);
+ cs->nr_subparts_cpus = cpumask_weight(cs->subparts_cpus);
+ }
+ }
+ spin_unlock_irq(&callback_lock);
+
+ /* effective_cpus will be updated here */
+ update_cpumasks_hier(cs, &tmp, 0);
+
+ if (cs->partition_root_state) {
+ struct cpuset *parent = parent_cs(cs);
+
+ /*
+ * For partition root, update the cpumasks of sibling
+ * cpusets if they use parent's effective_cpus.
+ */
+ if (parent->child_ecpus_count)
+ update_sibling_cpumasks(parent, cs, &tmp);
+
+ /* Update CS_SCHED_LOAD_BALANCE and/or sched_domains */
+ update_partition_sd_lb(cs, old_prs);
+ }
+out_free:
+ free_cpumasks(NULL, &tmp);
+ return 0;
+}
+
+/*
+ * Migrate memory region from one set of nodes to another. This is
+ * performed asynchronously as it can be called from process migration path
+ * holding locks involved in process management. All mm migrations are
+ * performed in the queued order and can be waited for by flushing
+ * cpuset_migrate_mm_wq.
+ */
+
+struct cpuset_migrate_mm_work {
+ struct work_struct work;
+ struct mm_struct *mm;
+ nodemask_t from;
+ nodemask_t to;
+};
+
+static void cpuset_migrate_mm_workfn(struct work_struct *work)
+{
+ struct cpuset_migrate_mm_work *mwork =
+ container_of(work, struct cpuset_migrate_mm_work, work);
+
+ /* on a wq worker, no need to worry about %current's mems_allowed */
+ do_migrate_pages(mwork->mm, &mwork->from, &mwork->to, MPOL_MF_MOVE_ALL);
+ mmput(mwork->mm);
+ kfree(mwork);
+}
+
+static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
+ const nodemask_t *to)
+{
+ struct cpuset_migrate_mm_work *mwork;
+
+ if (nodes_equal(*from, *to)) {
+ mmput(mm);
+ return;
+ }
+
+ mwork = kzalloc(sizeof(*mwork), GFP_KERNEL);
+ if (mwork) {
+ mwork->mm = mm;
+ mwork->from = *from;
+ mwork->to = *to;
+ INIT_WORK(&mwork->work, cpuset_migrate_mm_workfn);
+ queue_work(cpuset_migrate_mm_wq, &mwork->work);
+ } else {
+ mmput(mm);
+ }
+}
+
+static void cpuset_post_attach(void)
+{
+ flush_workqueue(cpuset_migrate_mm_wq);
+}
+
+/*
+ * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
+ * @tsk: the task to change
+ * @newmems: new nodes that the task will be set
+ *
+ * We use the mems_allowed_seq seqlock to safely update both tsk->mems_allowed
+ * and rebind an eventual tasks' mempolicy. If the task is allocating in
+ * parallel, it might temporarily see an empty intersection, which results in
+ * a seqlock check and retry before OOM or allocation failure.
+ */
+static void cpuset_change_task_nodemask(struct task_struct *tsk,
+ nodemask_t *newmems)
+{
+ task_lock(tsk);
+
+ local_irq_disable();
+ write_seqcount_begin(&tsk->mems_allowed_seq);
+
+ nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
+ mpol_rebind_task(tsk, newmems);
+ tsk->mems_allowed = *newmems;
+
+ write_seqcount_end(&tsk->mems_allowed_seq);
+ local_irq_enable();
+
+ task_unlock(tsk);
+}
+
+static void *cpuset_being_rebound;
+
+/**
+ * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
+ * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
+ *
+ * Iterate through each task of @cs updating its mems_allowed to the
+ * effective cpuset's. As this function is called with cpuset_mutex held,
+ * cpuset membership stays stable.
+ */
+static void update_tasks_nodemask(struct cpuset *cs)
+{
+ static nodemask_t newmems; /* protected by cpuset_mutex */
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
+
+ guarantee_online_mems(cs, &newmems);
+
+ /*
+ * The mpol_rebind_mm() call takes mmap_lock, which we couldn't
+ * take while holding tasklist_lock. Forks can happen - the
+ * mpol_dup() cpuset_being_rebound check will catch such forks,
+ * and rebind their vma mempolicies too. Because we still hold
+ * the global cpuset_mutex, we know that no other rebind effort
+ * will be contending for the global variable cpuset_being_rebound.
+ * It's ok if we rebind the same mm twice; mpol_rebind_mm()
+ * is idempotent. Also migrate pages in each mm to new nodes.
+ */
+ css_task_iter_start(&cs->css, 0, &it);
+ while ((task = css_task_iter_next(&it))) {
+ struct mm_struct *mm;
+ bool migrate;
+
+ cpuset_change_task_nodemask(task, &newmems);
+
+ mm = get_task_mm(task);
+ if (!mm)
+ continue;
+
+ migrate = is_memory_migrate(cs);
+
+ mpol_rebind_mm(mm, &cs->mems_allowed);
+ if (migrate)
+ cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems);
+ else
+ mmput(mm);
+ }
+ css_task_iter_end(&it);
+
+ /*
+ * All the tasks' nodemasks have been updated, update
+ * cs->old_mems_allowed.
+ */
+ cs->old_mems_allowed = newmems;
+
+ /* We're done rebinding vmas to this cpuset's new mems_allowed. */
+ cpuset_being_rebound = NULL;
+}
+
+/*
+ * update_nodemasks_hier - Update effective nodemasks and tasks in the subtree
+ * @cs: the cpuset to consider
+ * @new_mems: a temp variable for calculating new effective_mems
+ *
+ * When configured nodemask is changed, the effective nodemasks of this cpuset
+ * and all its descendants need to be updated.
+ *
+ * On legacy hierarchy, effective_mems will be the same with mems_allowed.
+ *
+ * Called with cpuset_mutex held
+ */
+static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
+{
+ struct cpuset *cp;
+ struct cgroup_subsys_state *pos_css;
+
+ rcu_read_lock();
+ cpuset_for_each_descendant_pre(cp, pos_css, cs) {
+ struct cpuset *parent = parent_cs(cp);
+
+ nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems);
+
+ /*
+ * If it becomes empty, inherit the effective mask of the
+ * parent, which is guaranteed to have some MEMs.
+ */
+ if (is_in_v2_mode() && nodes_empty(*new_mems))
+ *new_mems = parent->effective_mems;
+
+ /* Skip the whole subtree if the nodemask remains the same. */
+ if (nodes_equal(*new_mems, cp->effective_mems)) {
+ pos_css = css_rightmost_descendant(pos_css);
+ continue;
+ }
+
+ if (!css_tryget_online(&cp->css))
+ continue;
+ rcu_read_unlock();
+
+ spin_lock_irq(&callback_lock);
+ cp->effective_mems = *new_mems;
+ spin_unlock_irq(&callback_lock);
+
+ WARN_ON(!is_in_v2_mode() &&
+ !nodes_equal(cp->mems_allowed, cp->effective_mems));
+
+ update_tasks_nodemask(cp);
+
+ rcu_read_lock();
+ css_put(&cp->css);
+ }
+ rcu_read_unlock();
+}
+
+/*
+ * Handle user request to change the 'mems' memory placement
+ * of a cpuset. Needs to validate the request, update the
+ * cpusets mems_allowed, and for each task in the cpuset,
+ * update mems_allowed and rebind task's mempolicy and any vma
+ * mempolicies and if the cpuset is marked 'memory_migrate',
+ * migrate the tasks pages to the new memory.
+ *
+ * Call with cpuset_mutex held. May take callback_lock during call.
+ * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
+ * lock each such tasks mm->mmap_lock, scan its vma's and rebind
+ * their mempolicies to the cpusets new mems_allowed.
+ */
+static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
+ const char *buf)
+{
+ int retval;
+
+ /*
+ * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
+ * it's read-only
+ */
+ if (cs == &top_cpuset) {
+ retval = -EACCES;
+ goto done;
+ }
+
+ /*
+ * An empty mems_allowed is ok iff there are no tasks in the cpuset.
+ * Since nodelist_parse() fails on an empty mask, we special case
+ * that parsing. The validate_change() call ensures that cpusets
+ * with tasks have memory.
+ */
+ if (!*buf) {
+ nodes_clear(trialcs->mems_allowed);
+ } else {
+ retval = nodelist_parse(buf, trialcs->mems_allowed);
+ if (retval < 0)
+ goto done;
+
+ if (!nodes_subset(trialcs->mems_allowed,
+ top_cpuset.mems_allowed)) {
+ retval = -EINVAL;
+ goto done;
+ }
+ }
+
+ if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
+ retval = 0; /* Too easy - nothing to do */
+ goto done;
+ }
+ retval = validate_change(cs, trialcs);
+ if (retval < 0)
+ goto done;
+
+ check_insane_mems_config(&trialcs->mems_allowed);
+
+ spin_lock_irq(&callback_lock);
+ cs->mems_allowed = trialcs->mems_allowed;
+ spin_unlock_irq(&callback_lock);
+
+ /* use trialcs->mems_allowed as a temp variable */
+ update_nodemasks_hier(cs, &trialcs->mems_allowed);
+done:
+ return retval;
+}
+
+bool current_cpuset_is_being_rebound(void)
+{
+ bool ret;
+
+ rcu_read_lock();
+ ret = task_cs(current) == cpuset_being_rebound;
+ rcu_read_unlock();
+
+ return ret;
+}
+
+static int update_relax_domain_level(struct cpuset *cs, s64 val)
+{
+#ifdef CONFIG_SMP
+ if (val < -1 || val >= sched_domain_level_max)
+ return -EINVAL;
+#endif
+
+ if (val != cs->relax_domain_level) {
+ cs->relax_domain_level = val;
+ if (!cpumask_empty(cs->cpus_allowed) &&
+ is_sched_load_balance(cs))
+ rebuild_sched_domains_locked();
+ }
+
+ return 0;
+}
+
+/**
+ * update_tasks_flags - update the spread flags of tasks in the cpuset.
+ * @cs: the cpuset in which each task's spread flags needs to be changed
+ *
+ * Iterate through each task of @cs updating its spread flags. As this
+ * function is called with cpuset_mutex held, cpuset membership stays
+ * stable.
+ */
+static void update_tasks_flags(struct cpuset *cs)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ css_task_iter_start(&cs->css, 0, &it);
+ while ((task = css_task_iter_next(&it)))
+ cpuset_update_task_spread_flags(cs, task);
+ css_task_iter_end(&it);
+}
+
+/*
+ * update_flag - read a 0 or a 1 in a file and update associated flag
+ * bit: the bit to update (see cpuset_flagbits_t)
+ * cs: the cpuset to update
+ * turning_on: whether the flag is being set or cleared
+ *
+ * Call with cpuset_mutex held.
+ */
+
+static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
+ int turning_on)
+{
+ struct cpuset *trialcs;
+ int balance_flag_changed;
+ int spread_flag_changed;
+ int err;
+
+ trialcs = alloc_trial_cpuset(cs);
+ if (!trialcs)
+ return -ENOMEM;
+
+ if (turning_on)
+ set_bit(bit, &trialcs->flags);
+ else
+ clear_bit(bit, &trialcs->flags);
+
+ err = validate_change(cs, trialcs);
+ if (err < 0)
+ goto out;
+
+ balance_flag_changed = (is_sched_load_balance(cs) !=
+ is_sched_load_balance(trialcs));
+
+ spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
+ || (is_spread_page(cs) != is_spread_page(trialcs)));
+
+ spin_lock_irq(&callback_lock);
+ cs->flags = trialcs->flags;
+ spin_unlock_irq(&callback_lock);
+
+ if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
+ rebuild_sched_domains_locked();
+
+ if (spread_flag_changed)
+ update_tasks_flags(cs);
+out:
+ free_cpuset(trialcs);
+ return err;
+}
+
+/**
+ * update_prstate - update partition_root_state
+ * @cs: the cpuset to update
+ * @new_prs: new partition root state
+ * Return: 0 if successful, != 0 if error
+ *
+ * Call with cpuset_mutex held.
+ */
+static int update_prstate(struct cpuset *cs, int new_prs)
+{
+ int err = PERR_NONE, old_prs = cs->partition_root_state;
+ struct cpuset *parent = parent_cs(cs);
+ struct tmpmasks tmpmask;
+
+ if (old_prs == new_prs)
+ return 0;
+
+ /*
+ * For a previously invalid partition root, leave it at being
+ * invalid if new_prs is not "member".
+ */
+ if (new_prs && is_prs_invalid(old_prs)) {
+ cs->partition_root_state = -new_prs;
+ return 0;
+ }
+
+ if (alloc_cpumasks(NULL, &tmpmask))
+ return -ENOMEM;
+
+ err = update_partition_exclusive(cs, new_prs);
+ if (err)
+ goto out;
+
+ if (!old_prs) {
+ /*
+ * cpus_allowed cannot be empty.
+ */
+ if (cpumask_empty(cs->cpus_allowed)) {
+ err = PERR_CPUSEMPTY;
+ goto out;
+ }
+
+ err = update_parent_subparts_cpumask(cs, partcmd_enable,
+ NULL, &tmpmask);
+ } else if (old_prs && new_prs) {
+ /*
+ * A change in load balance state only, no change in cpumasks.
+ */
+ ;
+ } else {
+ /*
+ * Switching back to member is always allowed even if it
+ * disables child partitions.
+ */
+ update_parent_subparts_cpumask(cs, partcmd_disable, NULL,
+ &tmpmask);
+
+ /*
+ * If there are child partitions, they will all become invalid.
+ */
+ if (unlikely(cs->nr_subparts_cpus)) {
+ spin_lock_irq(&callback_lock);
+ cs->nr_subparts_cpus = 0;
+ cpumask_clear(cs->subparts_cpus);
+ compute_effective_cpumask(cs->effective_cpus, cs, parent);
+ spin_unlock_irq(&callback_lock);
+ }
+ }
+out:
+ /*
+ * Make partition invalid & disable CS_CPU_EXCLUSIVE if an error
+ * happens.
+ */
+ if (err) {
+ new_prs = -new_prs;
+ update_partition_exclusive(cs, new_prs);
+ }
+
+ spin_lock_irq(&callback_lock);
+ cs->partition_root_state = new_prs;
+ WRITE_ONCE(cs->prs_err, err);
+ spin_unlock_irq(&callback_lock);
+
+ /*
+ * Update child cpusets, if present.
+ * Force update if switching back to member.
+ */
+ if (!list_empty(&cs->css.children))
+ update_cpumasks_hier(cs, &tmpmask, !new_prs ? HIER_CHECKALL : 0);
+
+ /* Update sched domains and load balance flag */
+ update_partition_sd_lb(cs, old_prs);
+
+ notify_partition_change(cs, old_prs);
+ free_cpumasks(NULL, &tmpmask);
+ return 0;
+}
+
+/*
+ * Frequency meter - How fast is some event occurring?
+ *
+ * These routines manage a digitally filtered, constant time based,
+ * event frequency meter. There are four routines:
+ * fmeter_init() - initialize a frequency meter.
+ * fmeter_markevent() - called each time the event happens.
+ * fmeter_getrate() - returns the recent rate of such events.
+ * fmeter_update() - internal routine used to update fmeter.
+ *
+ * A common data structure is passed to each of these routines,
+ * which is used to keep track of the state required to manage the
+ * frequency meter and its digital filter.
+ *
+ * The filter works on the number of events marked per unit time.
+ * The filter is single-pole low-pass recursive (IIR). The time unit
+ * is 1 second. Arithmetic is done using 32-bit integers scaled to
+ * simulate 3 decimal digits of precision (multiplied by 1000).
+ *
+ * With an FM_COEF of 933, and a time base of 1 second, the filter
+ * has a half-life of 10 seconds, meaning that if the events quit
+ * happening, then the rate returned from the fmeter_getrate()
+ * will be cut in half each 10 seconds, until it converges to zero.
+ *
+ * It is not worth doing a real infinitely recursive filter. If more
+ * than FM_MAXTICKS ticks have elapsed since the last filter event,
+ * just compute FM_MAXTICKS ticks worth, by which point the level
+ * will be stable.
+ *
+ * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
+ * arithmetic overflow in the fmeter_update() routine.
+ *
+ * Given the simple 32 bit integer arithmetic used, this meter works
+ * best for reporting rates between one per millisecond (msec) and
+ * one per 32 (approx) seconds. At constant rates faster than one
+ * per msec it maxes out at values just under 1,000,000. At constant
+ * rates between one per msec, and one per second it will stabilize
+ * to a value N*1000, where N is the rate of events per second.
+ * At constant rates between one per second and one per 32 seconds,
+ * it will be choppy, moving up on the seconds that have an event,
+ * and then decaying until the next event. At rates slower than
+ * about one in 32 seconds, it decays all the way back to zero between
+ * each event.
+ */
+
+#define FM_COEF 933 /* coefficient for half-life of 10 secs */
+#define FM_MAXTICKS ((u32)99) /* useless computing more ticks than this */
+#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
+#define FM_SCALE 1000 /* faux fixed point scale */
+
+/* Initialize a frequency meter */
+static void fmeter_init(struct fmeter *fmp)
+{
+ fmp->cnt = 0;
+ fmp->val = 0;
+ fmp->time = 0;
+ spin_lock_init(&fmp->lock);
+}
+
+/* Internal meter update - process cnt events and update value */
+static void fmeter_update(struct fmeter *fmp)
+{
+ time64_t now;
+ u32 ticks;
+
+ now = ktime_get_seconds();
+ ticks = now - fmp->time;
+
+ if (ticks == 0)
+ return;
+
+ ticks = min(FM_MAXTICKS, ticks);
+ while (ticks-- > 0)
+ fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
+ fmp->time = now;
+
+ fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
+ fmp->cnt = 0;
+}
+
+/* Process any previous ticks, then bump cnt by one (times scale). */
+static void fmeter_markevent(struct fmeter *fmp)
+{
+ spin_lock(&fmp->lock);
+ fmeter_update(fmp);
+ fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
+ spin_unlock(&fmp->lock);
+}
+
+/* Process any previous ticks, then return current value. */
+static int fmeter_getrate(struct fmeter *fmp)
+{
+ int val;
+
+ spin_lock(&fmp->lock);
+ fmeter_update(fmp);
+ val = fmp->val;
+ spin_unlock(&fmp->lock);
+ return val;
+}
+
+static struct cpuset *cpuset_attach_old_cs;
+
+/*
+ * Check to see if a cpuset can accept a new task
+ * For v1, cpus_allowed and mems_allowed can't be empty.
+ * For v2, effective_cpus can't be empty.
+ * Note that in v1, effective_cpus = cpus_allowed.
+ */
+static int cpuset_can_attach_check(struct cpuset *cs)
+{
+ if (cpumask_empty(cs->effective_cpus) ||
+ (!is_in_v2_mode() && nodes_empty(cs->mems_allowed)))
+ return -ENOSPC;
+ return 0;
+}
+
+static void reset_migrate_dl_data(struct cpuset *cs)
+{
+ cs->nr_migrate_dl_tasks = 0;
+ cs->sum_migrate_dl_bw = 0;
+}
+
+/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
+static int cpuset_can_attach(struct cgroup_taskset *tset)
+{
+ struct cgroup_subsys_state *css;
+ struct cpuset *cs, *oldcs;
+ struct task_struct *task;
+ bool cpus_updated, mems_updated;
+ int ret;
+
+ /* used later by cpuset_attach() */
+ cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css));
+ oldcs = cpuset_attach_old_cs;
+ cs = css_cs(css);
+
+ mutex_lock(&cpuset_mutex);
+
+ /* Check to see if task is allowed in the cpuset */
+ ret = cpuset_can_attach_check(cs);
+ if (ret)
+ goto out_unlock;
+
+ cpus_updated = !cpumask_equal(cs->effective_cpus, oldcs->effective_cpus);
+ mems_updated = !nodes_equal(cs->effective_mems, oldcs->effective_mems);
+
+ cgroup_taskset_for_each(task, css, tset) {
+ ret = task_can_attach(task);
+ if (ret)
+ goto out_unlock;
+
+ /*
+ * Skip rights over task check in v2 when nothing changes,
+ * migration permission derives from hierarchy ownership in
+ * cgroup_procs_write_permission()).
+ */
+ if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||
+ (cpus_updated || mems_updated)) {
+ ret = security_task_setscheduler(task);
+ if (ret)
+ goto out_unlock;
+ }
+
+ if (dl_task(task)) {
+ cs->nr_migrate_dl_tasks++;
+ cs->sum_migrate_dl_bw += task->dl.dl_bw;
+ }
+ }
+
+ if (!cs->nr_migrate_dl_tasks)
+ goto out_success;
+
+ if (!cpumask_intersects(oldcs->effective_cpus, cs->effective_cpus)) {
+ int cpu = cpumask_any_and(cpu_active_mask, cs->effective_cpus);
+
+ if (unlikely(cpu >= nr_cpu_ids)) {
+ reset_migrate_dl_data(cs);
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ ret = dl_bw_alloc(cpu, cs->sum_migrate_dl_bw);
+ if (ret) {
+ reset_migrate_dl_data(cs);
+ goto out_unlock;
+ }
+ }
+
+out_success:
+ /*
+ * Mark attach is in progress. This makes validate_change() fail
+ * changes which zero cpus/mems_allowed.
+ */
+ cs->attach_in_progress++;
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ return ret;
+}
+
+static void cpuset_cancel_attach(struct cgroup_taskset *tset)
+{
+ struct cgroup_subsys_state *css;
+ struct cpuset *cs;
+
+ cgroup_taskset_first(tset, &css);
+ cs = css_cs(css);
+
+ mutex_lock(&cpuset_mutex);
+ cs->attach_in_progress--;
+ if (!cs->attach_in_progress)
+ wake_up(&cpuset_attach_wq);
+
+ if (cs->nr_migrate_dl_tasks) {
+ int cpu = cpumask_any(cs->effective_cpus);
+
+ dl_bw_free(cpu, cs->sum_migrate_dl_bw);
+ reset_migrate_dl_data(cs);
+ }
+
+ mutex_unlock(&cpuset_mutex);
+}
+
+/*
+ * Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach_task()
+ * but we can't allocate it dynamically there. Define it global and
+ * allocate from cpuset_init().
+ */
+static cpumask_var_t cpus_attach;
+static nodemask_t cpuset_attach_nodemask_to;
+
+static void cpuset_attach_task(struct cpuset *cs, struct task_struct *task)
+{
+ lockdep_assert_held(&cpuset_mutex);
+
+ if (cs != &top_cpuset)
+ guarantee_online_cpus(task, cpus_attach);
+ else
+ cpumask_andnot(cpus_attach, task_cpu_possible_mask(task),
+ cs->subparts_cpus);
+ /*
+ * can_attach beforehand should guarantee that this doesn't
+ * fail. TODO: have a better way to handle failure here
+ */
+ WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));
+
+ cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
+ cpuset_update_task_spread_flags(cs, task);
+}
+
+static void cpuset_attach(struct cgroup_taskset *tset)
+{
+ struct task_struct *task;
+ struct task_struct *leader;
+ struct cgroup_subsys_state *css;
+ struct cpuset *cs;
+ struct cpuset *oldcs = cpuset_attach_old_cs;
+ bool cpus_updated, mems_updated;
+
+ cgroup_taskset_first(tset, &css);
+ cs = css_cs(css);
+
+ lockdep_assert_cpus_held(); /* see cgroup_attach_lock() */
+ mutex_lock(&cpuset_mutex);
+ cpus_updated = !cpumask_equal(cs->effective_cpus,
+ oldcs->effective_cpus);
+ mems_updated = !nodes_equal(cs->effective_mems, oldcs->effective_mems);
+
+ /*
+ * In the default hierarchy, enabling cpuset in the child cgroups
+ * will trigger a number of cpuset_attach() calls with no change
+ * in effective cpus and mems. In that case, we can optimize out
+ * by skipping the task iteration and update.
+ */
+ if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
+ !cpus_updated && !mems_updated) {
+ cpuset_attach_nodemask_to = cs->effective_mems;
+ goto out;
+ }
+
+ guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
+
+ cgroup_taskset_for_each(task, css, tset)
+ cpuset_attach_task(cs, task);
+
+ /*
+ * Change mm for all threadgroup leaders. This is expensive and may
+ * sleep and should be moved outside migration path proper. Skip it
+ * if there is no change in effective_mems and CS_MEMORY_MIGRATE is
+ * not set.
+ */
+ cpuset_attach_nodemask_to = cs->effective_mems;
+ if (!is_memory_migrate(cs) && !mems_updated)
+ goto out;
+
+ cgroup_taskset_for_each_leader(leader, css, tset) {
+ struct mm_struct *mm = get_task_mm(leader);
+
+ if (mm) {
+ mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
+
+ /*
+ * old_mems_allowed is the same with mems_allowed
+ * here, except if this task is being moved
+ * automatically due to hotplug. In that case
+ * @mems_allowed has been updated and is empty, so
+ * @old_mems_allowed is the right nodesets that we
+ * migrate mm from.
+ */
+ if (is_memory_migrate(cs))
+ cpuset_migrate_mm(mm, &oldcs->old_mems_allowed,
+ &cpuset_attach_nodemask_to);
+ else
+ mmput(mm);
+ }
+ }
+
+out:
+ cs->old_mems_allowed = cpuset_attach_nodemask_to;
+
+ if (cs->nr_migrate_dl_tasks) {
+ cs->nr_deadline_tasks += cs->nr_migrate_dl_tasks;
+ oldcs->nr_deadline_tasks -= cs->nr_migrate_dl_tasks;
+ reset_migrate_dl_data(cs);
+ }
+
+ cs->attach_in_progress--;
+ if (!cs->attach_in_progress)
+ wake_up(&cpuset_attach_wq);
+
+ mutex_unlock(&cpuset_mutex);
+}
+
+/* The various types of files and directories in a cpuset file system */
+
+typedef enum {
+ FILE_MEMORY_MIGRATE,
+ FILE_CPULIST,
+ FILE_MEMLIST,
+ FILE_EFFECTIVE_CPULIST,
+ FILE_EFFECTIVE_MEMLIST,
+ FILE_SUBPARTS_CPULIST,
+ FILE_CPU_EXCLUSIVE,
+ FILE_MEM_EXCLUSIVE,
+ FILE_MEM_HARDWALL,
+ FILE_SCHED_LOAD_BALANCE,
+ FILE_PARTITION_ROOT,
+ FILE_SCHED_RELAX_DOMAIN_LEVEL,
+ FILE_MEMORY_PRESSURE_ENABLED,
+ FILE_MEMORY_PRESSURE,
+ FILE_SPREAD_PAGE,
+ FILE_SPREAD_SLAB,
+} cpuset_filetype_t;
+
+static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft,
+ u64 val)
+{
+ struct cpuset *cs = css_cs(css);
+ cpuset_filetype_t type = cft->private;
+ int retval = 0;
+
+ cpus_read_lock();
+ mutex_lock(&cpuset_mutex);
+ if (!is_cpuset_online(cs)) {
+ retval = -ENODEV;
+ goto out_unlock;
+ }
+
+ switch (type) {
+ case FILE_CPU_EXCLUSIVE:
+ retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
+ break;
+ case FILE_MEM_EXCLUSIVE:
+ retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
+ break;
+ case FILE_MEM_HARDWALL:
+ retval = update_flag(CS_MEM_HARDWALL, cs, val);
+ break;
+ case FILE_SCHED_LOAD_BALANCE:
+ retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
+ break;
+ case FILE_MEMORY_MIGRATE:
+ retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
+ break;
+ case FILE_MEMORY_PRESSURE_ENABLED:
+ cpuset_memory_pressure_enabled = !!val;
+ break;
+ case FILE_SPREAD_PAGE:
+ retval = update_flag(CS_SPREAD_PAGE, cs, val);
+ break;
+ case FILE_SPREAD_SLAB:
+ retval = update_flag(CS_SPREAD_SLAB, cs, val);
+ break;
+ default:
+ retval = -EINVAL;
+ break;
+ }
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ cpus_read_unlock();
+ return retval;
+}
+
+static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft,
+ s64 val)
+{
+ struct cpuset *cs = css_cs(css);
+ cpuset_filetype_t type = cft->private;
+ int retval = -ENODEV;
+
+ cpus_read_lock();
+ mutex_lock(&cpuset_mutex);
+ if (!is_cpuset_online(cs))
+ goto out_unlock;
+
+ switch (type) {
+ case FILE_SCHED_RELAX_DOMAIN_LEVEL:
+ retval = update_relax_domain_level(cs, val);
+ break;
+ default:
+ retval = -EINVAL;
+ break;
+ }
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ cpus_read_unlock();
+ return retval;
+}
+
+/*
+ * Common handling for a write to a "cpus" or "mems" file.
+ */
+static ssize_t cpuset_write_resmask(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cpuset *cs = css_cs(of_css(of));
+ struct cpuset *trialcs;
+ int retval = -ENODEV;
+
+ buf = strstrip(buf);
+
+ /*
+ * CPU or memory hotunplug may leave @cs w/o any execution
+ * resources, in which case the hotplug code asynchronously updates
+ * configuration and transfers all tasks to the nearest ancestor
+ * which can execute.
+ *
+ * As writes to "cpus" or "mems" may restore @cs's execution
+ * resources, wait for the previously scheduled operations before
+ * proceeding, so that we don't end up keep removing tasks added
+ * after execution capability is restored.
+ *
+ * cpuset_hotplug_work calls back into cgroup core via
+ * cgroup_transfer_tasks() and waiting for it from a cgroupfs
+ * operation like this one can lead to a deadlock through kernfs
+ * active_ref protection. Let's break the protection. Losing the
+ * protection is okay as we check whether @cs is online after
+ * grabbing cpuset_mutex anyway. This only happens on the legacy
+ * hierarchies.
+ */
+ css_get(&cs->css);
+ kernfs_break_active_protection(of->kn);
+ flush_work(&cpuset_hotplug_work);
+
+ cpus_read_lock();
+ mutex_lock(&cpuset_mutex);
+ if (!is_cpuset_online(cs))
+ goto out_unlock;
+
+ trialcs = alloc_trial_cpuset(cs);
+ if (!trialcs) {
+ retval = -ENOMEM;
+ goto out_unlock;
+ }
+
+ switch (of_cft(of)->private) {
+ case FILE_CPULIST:
+ retval = update_cpumask(cs, trialcs, buf);
+ break;
+ case FILE_MEMLIST:
+ retval = update_nodemask(cs, trialcs, buf);
+ break;
+ default:
+ retval = -EINVAL;
+ break;
+ }
+
+ free_cpuset(trialcs);
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ cpus_read_unlock();
+ kernfs_unbreak_active_protection(of->kn);
+ css_put(&cs->css);
+ flush_workqueue(cpuset_migrate_mm_wq);
+ return retval ?: nbytes;
+}
+
+/*
+ * These ascii lists should be read in a single call, by using a user
+ * buffer large enough to hold the entire map. If read in smaller
+ * chunks, there is no guarantee of atomicity. Since the display format
+ * used, list of ranges of sequential numbers, is variable length,
+ * and since these maps can change value dynamically, one could read
+ * gibberish by doing partial reads while a list was changing.
+ */
+static int cpuset_common_seq_show(struct seq_file *sf, void *v)
+{
+ struct cpuset *cs = css_cs(seq_css(sf));
+ cpuset_filetype_t type = seq_cft(sf)->private;
+ int ret = 0;
+
+ spin_lock_irq(&callback_lock);
+
+ switch (type) {
+ case FILE_CPULIST:
+ seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->cpus_allowed));
+ break;
+ case FILE_MEMLIST:
+ seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->mems_allowed));
+ break;
+ case FILE_EFFECTIVE_CPULIST:
+ seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->effective_cpus));
+ break;
+ case FILE_EFFECTIVE_MEMLIST:
+ seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->effective_mems));
+ break;
+ case FILE_SUBPARTS_CPULIST:
+ seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->subparts_cpus));
+ break;
+ default:
+ ret = -EINVAL;
+ }
+
+ spin_unlock_irq(&callback_lock);
+ return ret;
+}
+
+static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft)
+{
+ struct cpuset *cs = css_cs(css);
+ cpuset_filetype_t type = cft->private;
+ switch (type) {
+ case FILE_CPU_EXCLUSIVE:
+ return is_cpu_exclusive(cs);
+ case FILE_MEM_EXCLUSIVE:
+ return is_mem_exclusive(cs);
+ case FILE_MEM_HARDWALL:
+ return is_mem_hardwall(cs);
+ case FILE_SCHED_LOAD_BALANCE:
+ return is_sched_load_balance(cs);
+ case FILE_MEMORY_MIGRATE:
+ return is_memory_migrate(cs);
+ case FILE_MEMORY_PRESSURE_ENABLED:
+ return cpuset_memory_pressure_enabled;
+ case FILE_MEMORY_PRESSURE:
+ return fmeter_getrate(&cs->fmeter);
+ case FILE_SPREAD_PAGE:
+ return is_spread_page(cs);
+ case FILE_SPREAD_SLAB:
+ return is_spread_slab(cs);
+ default:
+ BUG();
+ }
+
+ /* Unreachable but makes gcc happy */
+ return 0;
+}
+
+static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
+{
+ struct cpuset *cs = css_cs(css);
+ cpuset_filetype_t type = cft->private;
+ switch (type) {
+ case FILE_SCHED_RELAX_DOMAIN_LEVEL:
+ return cs->relax_domain_level;
+ default:
+ BUG();
+ }
+
+ /* Unreachable but makes gcc happy */
+ return 0;
+}
+
+static int sched_partition_show(struct seq_file *seq, void *v)
+{
+ struct cpuset *cs = css_cs(seq_css(seq));
+ const char *err, *type = NULL;
+
+ switch (cs->partition_root_state) {
+ case PRS_ROOT:
+ seq_puts(seq, "root\n");
+ break;
+ case PRS_ISOLATED:
+ seq_puts(seq, "isolated\n");
+ break;
+ case PRS_MEMBER:
+ seq_puts(seq, "member\n");
+ break;
+ case PRS_INVALID_ROOT:
+ type = "root";
+ fallthrough;
+ case PRS_INVALID_ISOLATED:
+ if (!type)
+ type = "isolated";
+ err = perr_strings[READ_ONCE(cs->prs_err)];
+ if (err)
+ seq_printf(seq, "%s invalid (%s)\n", type, err);
+ else
+ seq_printf(seq, "%s invalid\n", type);
+ break;
+ }
+ return 0;
+}
+
+static ssize_t sched_partition_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct cpuset *cs = css_cs(of_css(of));
+ int val;
+ int retval = -ENODEV;
+
+ buf = strstrip(buf);
+
+ /*
+ * Convert "root" to ENABLED, and convert "member" to DISABLED.
+ */
+ if (!strcmp(buf, "root"))
+ val = PRS_ROOT;
+ else if (!strcmp(buf, "member"))
+ val = PRS_MEMBER;
+ else if (!strcmp(buf, "isolated"))
+ val = PRS_ISOLATED;
+ else
+ return -EINVAL;
+
+ css_get(&cs->css);
+ cpus_read_lock();
+ mutex_lock(&cpuset_mutex);
+ if (!is_cpuset_online(cs))
+ goto out_unlock;
+
+ retval = update_prstate(cs, val);
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ cpus_read_unlock();
+ css_put(&cs->css);
+ return retval ?: nbytes;
+}
+
+/*
+ * for the common functions, 'private' gives the type of file
+ */
+
+static struct cftype legacy_files[] = {
+ {
+ .name = "cpus",
+ .seq_show = cpuset_common_seq_show,
+ .write = cpuset_write_resmask,
+ .max_write_len = (100U + 6 * NR_CPUS),
+ .private = FILE_CPULIST,
+ },
+
+ {
+ .name = "mems",
+ .seq_show = cpuset_common_seq_show,
+ .write = cpuset_write_resmask,
+ .max_write_len = (100U + 6 * MAX_NUMNODES),
+ .private = FILE_MEMLIST,
+ },
+
+ {
+ .name = "effective_cpus",
+ .seq_show = cpuset_common_seq_show,
+ .private = FILE_EFFECTIVE_CPULIST,
+ },
+
+ {
+ .name = "effective_mems",
+ .seq_show = cpuset_common_seq_show,
+ .private = FILE_EFFECTIVE_MEMLIST,
+ },
+
+ {
+ .name = "cpu_exclusive",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_CPU_EXCLUSIVE,
+ },
+
+ {
+ .name = "mem_exclusive",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_MEM_EXCLUSIVE,
+ },
+
+ {
+ .name = "mem_hardwall",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_MEM_HARDWALL,
+ },
+
+ {
+ .name = "sched_load_balance",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_SCHED_LOAD_BALANCE,
+ },
+
+ {
+ .name = "sched_relax_domain_level",
+ .read_s64 = cpuset_read_s64,
+ .write_s64 = cpuset_write_s64,
+ .private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
+ },
+
+ {
+ .name = "memory_migrate",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_MEMORY_MIGRATE,
+ },
+
+ {
+ .name = "memory_pressure",
+ .read_u64 = cpuset_read_u64,
+ .private = FILE_MEMORY_PRESSURE,
+ },
+
+ {
+ .name = "memory_spread_page",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_SPREAD_PAGE,
+ },
+
+ {
+ .name = "memory_spread_slab",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_SPREAD_SLAB,
+ },
+
+ {
+ .name = "memory_pressure_enabled",
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_MEMORY_PRESSURE_ENABLED,
+ },
+
+ { } /* terminate */
+};
+
+/*
+ * This is currently a minimal set for the default hierarchy. It can be
+ * expanded later on by migrating more features and control files from v1.
+ */
+static struct cftype dfl_files[] = {
+ {
+ .name = "cpus",
+ .seq_show = cpuset_common_seq_show,
+ .write = cpuset_write_resmask,
+ .max_write_len = (100U + 6 * NR_CPUS),
+ .private = FILE_CPULIST,
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+
+ {
+ .name = "mems",
+ .seq_show = cpuset_common_seq_show,
+ .write = cpuset_write_resmask,
+ .max_write_len = (100U + 6 * MAX_NUMNODES),
+ .private = FILE_MEMLIST,
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+
+ {
+ .name = "cpus.effective",
+ .seq_show = cpuset_common_seq_show,
+ .private = FILE_EFFECTIVE_CPULIST,
+ },
+
+ {
+ .name = "mems.effective",
+ .seq_show = cpuset_common_seq_show,
+ .private = FILE_EFFECTIVE_MEMLIST,
+ },
+
+ {
+ .name = "cpus.partition",
+ .seq_show = sched_partition_show,
+ .write = sched_partition_write,
+ .private = FILE_PARTITION_ROOT,
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .file_offset = offsetof(struct cpuset, partition_file),
+ },
+
+ {
+ .name = "cpus.subpartitions",
+ .seq_show = cpuset_common_seq_show,
+ .private = FILE_SUBPARTS_CPULIST,
+ .flags = CFTYPE_DEBUG,
+ },
+
+ { } /* terminate */
+};
+
+
+/**
+ * cpuset_css_alloc - Allocate a cpuset css
+ * @parent_css: Parent css of the control group that the new cpuset will be
+ * part of
+ * Return: cpuset css on success, -ENOMEM on failure.
+ *
+ * Allocate and initialize a new cpuset css, for non-NULL @parent_css, return
+ * top cpuset css otherwise.
+ */
+static struct cgroup_subsys_state *
+cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+ struct cpuset *cs;
+
+ if (!parent_css)
+ return &top_cpuset.css;
+
+ cs = kzalloc(sizeof(*cs), GFP_KERNEL);
+ if (!cs)
+ return ERR_PTR(-ENOMEM);
+
+ if (alloc_cpumasks(cs, NULL)) {
+ kfree(cs);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ __set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
+ nodes_clear(cs->mems_allowed);
+ nodes_clear(cs->effective_mems);
+ fmeter_init(&cs->fmeter);
+ cs->relax_domain_level = -1;
+
+ /* Set CS_MEMORY_MIGRATE for default hierarchy */
+ if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys))
+ __set_bit(CS_MEMORY_MIGRATE, &cs->flags);
+
+ return &cs->css;
+}
+
+static int cpuset_css_online(struct cgroup_subsys_state *css)
+{
+ struct cpuset *cs = css_cs(css);
+ struct cpuset *parent = parent_cs(cs);
+ struct cpuset *tmp_cs;
+ struct cgroup_subsys_state *pos_css;
+
+ if (!parent)
+ return 0;
+
+ cpus_read_lock();
+ mutex_lock(&cpuset_mutex);
+
+ set_bit(CS_ONLINE, &cs->flags);
+ if (is_spread_page(parent))
+ set_bit(CS_SPREAD_PAGE, &cs->flags);
+ if (is_spread_slab(parent))
+ set_bit(CS_SPREAD_SLAB, &cs->flags);
+
+ cpuset_inc();
+
+ spin_lock_irq(&callback_lock);
+ if (is_in_v2_mode()) {
+ cpumask_copy(cs->effective_cpus, parent->effective_cpus);
+ cs->effective_mems = parent->effective_mems;
+ cs->use_parent_ecpus = true;
+ parent->child_ecpus_count++;
+ }
+
+ /*
+ * For v2, clear CS_SCHED_LOAD_BALANCE if parent is isolated
+ */
+ if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
+ !is_sched_load_balance(parent))
+ clear_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
+
+ spin_unlock_irq(&callback_lock);
+
+ if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
+ goto out_unlock;
+
+ /*
+ * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
+ * set. This flag handling is implemented in cgroup core for
+ * historical reasons - the flag may be specified during mount.
+ *
+ * Currently, if any sibling cpusets have exclusive cpus or mem, we
+ * refuse to clone the configuration - thereby refusing the task to
+ * be entered, and as a result refusing the sys_unshare() or
+ * clone() which initiated it. If this becomes a problem for some
+ * users who wish to allow that scenario, then this could be
+ * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
+ * (and likewise for mems) to the new cgroup.
+ */
+ rcu_read_lock();
+ cpuset_for_each_child(tmp_cs, pos_css, parent) {
+ if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
+ rcu_read_unlock();
+ goto out_unlock;
+ }
+ }
+ rcu_read_unlock();
+
+ spin_lock_irq(&callback_lock);
+ cs->mems_allowed = parent->mems_allowed;
+ cs->effective_mems = parent->mems_allowed;
+ cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
+ cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
+ spin_unlock_irq(&callback_lock);
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ cpus_read_unlock();
+ return 0;
+}
+
+/*
+ * If the cpuset being removed has its flag 'sched_load_balance'
+ * enabled, then simulate turning sched_load_balance off, which
+ * will call rebuild_sched_domains_locked(). That is not needed
+ * in the default hierarchy where only changes in partition
+ * will cause repartitioning.
+ *
+ * If the cpuset has the 'sched.partition' flag enabled, simulate
+ * turning 'sched.partition" off.
+ */
+
+static void cpuset_css_offline(struct cgroup_subsys_state *css)
+{
+ struct cpuset *cs = css_cs(css);
+
+ cpus_read_lock();
+ mutex_lock(&cpuset_mutex);
+
+ if (is_partition_valid(cs))
+ update_prstate(cs, 0);
+
+ if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
+ is_sched_load_balance(cs))
+ update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
+
+ if (cs->use_parent_ecpus) {
+ struct cpuset *parent = parent_cs(cs);
+
+ cs->use_parent_ecpus = false;
+ parent->child_ecpus_count--;
+ }
+
+ cpuset_dec();
+ clear_bit(CS_ONLINE, &cs->flags);
+
+ mutex_unlock(&cpuset_mutex);
+ cpus_read_unlock();
+}
+
+static void cpuset_css_free(struct cgroup_subsys_state *css)
+{
+ struct cpuset *cs = css_cs(css);
+
+ free_cpuset(cs);
+}
+
+static void cpuset_bind(struct cgroup_subsys_state *root_css)
+{
+ mutex_lock(&cpuset_mutex);
+ spin_lock_irq(&callback_lock);
+
+ if (is_in_v2_mode()) {
+ cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
+ top_cpuset.mems_allowed = node_possible_map;
+ } else {
+ cpumask_copy(top_cpuset.cpus_allowed,
+ top_cpuset.effective_cpus);
+ top_cpuset.mems_allowed = top_cpuset.effective_mems;
+ }
+
+ spin_unlock_irq(&callback_lock);
+ mutex_unlock(&cpuset_mutex);
+}
+
+/*
+ * In case the child is cloned into a cpuset different from its parent,
+ * additional checks are done to see if the move is allowed.
+ */
+static int cpuset_can_fork(struct task_struct *task, struct css_set *cset)
+{
+ struct cpuset *cs = css_cs(cset->subsys[cpuset_cgrp_id]);
+ bool same_cs;
+ int ret;
+
+ rcu_read_lock();
+ same_cs = (cs == task_cs(current));
+ rcu_read_unlock();
+
+ if (same_cs)
+ return 0;
+
+ lockdep_assert_held(&cgroup_mutex);
+ mutex_lock(&cpuset_mutex);
+
+ /* Check to see if task is allowed in the cpuset */
+ ret = cpuset_can_attach_check(cs);
+ if (ret)
+ goto out_unlock;
+
+ ret = task_can_attach(task);
+ if (ret)
+ goto out_unlock;
+
+ ret = security_task_setscheduler(task);
+ if (ret)
+ goto out_unlock;
+
+ /*
+ * Mark attach is in progress. This makes validate_change() fail
+ * changes which zero cpus/mems_allowed.
+ */
+ cs->attach_in_progress++;
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ return ret;
+}
+
+static void cpuset_cancel_fork(struct task_struct *task, struct css_set *cset)
+{
+ struct cpuset *cs = css_cs(cset->subsys[cpuset_cgrp_id]);
+ bool same_cs;
+
+ rcu_read_lock();
+ same_cs = (cs == task_cs(current));
+ rcu_read_unlock();
+
+ if (same_cs)
+ return;
+
+ mutex_lock(&cpuset_mutex);
+ cs->attach_in_progress--;
+ if (!cs->attach_in_progress)
+ wake_up(&cpuset_attach_wq);
+ mutex_unlock(&cpuset_mutex);
+}
+
+/*
+ * Make sure the new task conform to the current state of its parent,
+ * which could have been changed by cpuset just after it inherits the
+ * state from the parent and before it sits on the cgroup's task list.
+ */
+static void cpuset_fork(struct task_struct *task)
+{
+ struct cpuset *cs;
+ bool same_cs;
+
+ rcu_read_lock();
+ cs = task_cs(task);
+ same_cs = (cs == task_cs(current));
+ rcu_read_unlock();
+
+ if (same_cs) {
+ if (cs == &top_cpuset)
+ return;
+
+ set_cpus_allowed_ptr(task, current->cpus_ptr);
+ task->mems_allowed = current->mems_allowed;
+ return;
+ }
+
+ /* CLONE_INTO_CGROUP */
+ mutex_lock(&cpuset_mutex);
+ guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
+ cpuset_attach_task(cs, task);
+
+ cs->attach_in_progress--;
+ if (!cs->attach_in_progress)
+ wake_up(&cpuset_attach_wq);
+
+ mutex_unlock(&cpuset_mutex);
+}
+
+struct cgroup_subsys cpuset_cgrp_subsys = {
+ .css_alloc = cpuset_css_alloc,
+ .css_online = cpuset_css_online,
+ .css_offline = cpuset_css_offline,
+ .css_free = cpuset_css_free,
+ .can_attach = cpuset_can_attach,
+ .cancel_attach = cpuset_cancel_attach,
+ .attach = cpuset_attach,
+ .post_attach = cpuset_post_attach,
+ .bind = cpuset_bind,
+ .can_fork = cpuset_can_fork,
+ .cancel_fork = cpuset_cancel_fork,
+ .fork = cpuset_fork,
+ .legacy_cftypes = legacy_files,
+ .dfl_cftypes = dfl_files,
+ .early_init = true,
+ .threaded = true,
+};
+
+/**
+ * cpuset_init - initialize cpusets at system boot
+ *
+ * Description: Initialize top_cpuset
+ **/
+
+int __init cpuset_init(void)
+{
+ BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL));
+ BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL));
+ BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL));
+
+ cpumask_setall(top_cpuset.cpus_allowed);
+ nodes_setall(top_cpuset.mems_allowed);
+ cpumask_setall(top_cpuset.effective_cpus);
+ nodes_setall(top_cpuset.effective_mems);
+
+ fmeter_init(&top_cpuset.fmeter);
+ set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
+ top_cpuset.relax_domain_level = -1;
+
+ BUG_ON(!alloc_cpumask_var(&cpus_attach, GFP_KERNEL));
+
+ return 0;
+}
+
+/*
+ * If CPU and/or memory hotplug handlers, below, unplug any CPUs
+ * or memory nodes, we need to walk over the cpuset hierarchy,
+ * removing that CPU or node from all cpusets. If this removes the
+ * last CPU or node from a cpuset, then move the tasks in the empty
+ * cpuset to its next-highest non-empty parent.
+ */
+static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
+{
+ struct cpuset *parent;
+
+ /*
+ * Find its next-highest non-empty parent, (top cpuset
+ * has online cpus, so can't be empty).
+ */
+ parent = parent_cs(cs);
+ while (cpumask_empty(parent->cpus_allowed) ||
+ nodes_empty(parent->mems_allowed))
+ parent = parent_cs(parent);
+
+ if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
+ pr_err("cpuset: failed to transfer tasks out of empty cpuset ");
+ pr_cont_cgroup_name(cs->css.cgroup);
+ pr_cont("\n");
+ }
+}
+
+static void
+hotplug_update_tasks_legacy(struct cpuset *cs,
+ struct cpumask *new_cpus, nodemask_t *new_mems,
+ bool cpus_updated, bool mems_updated)
+{
+ bool is_empty;
+
+ spin_lock_irq(&callback_lock);
+ cpumask_copy(cs->cpus_allowed, new_cpus);
+ cpumask_copy(cs->effective_cpus, new_cpus);
+ cs->mems_allowed = *new_mems;
+ cs->effective_mems = *new_mems;
+ spin_unlock_irq(&callback_lock);
+
+ /*
+ * Don't call update_tasks_cpumask() if the cpuset becomes empty,
+ * as the tasks will be migrated to an ancestor.
+ */
+ if (cpus_updated && !cpumask_empty(cs->cpus_allowed))
+ update_tasks_cpumask(cs, new_cpus);
+ if (mems_updated && !nodes_empty(cs->mems_allowed))
+ update_tasks_nodemask(cs);
+
+ is_empty = cpumask_empty(cs->cpus_allowed) ||
+ nodes_empty(cs->mems_allowed);
+
+ /*
+ * Move tasks to the nearest ancestor with execution resources,
+ * This is full cgroup operation which will also call back into
+ * cpuset. Should be done outside any lock.
+ */
+ if (is_empty) {
+ mutex_unlock(&cpuset_mutex);
+ remove_tasks_in_empty_cpuset(cs);
+ mutex_lock(&cpuset_mutex);
+ }
+}
+
+static void
+hotplug_update_tasks(struct cpuset *cs,
+ struct cpumask *new_cpus, nodemask_t *new_mems,
+ bool cpus_updated, bool mems_updated)
+{
+ /* A partition root is allowed to have empty effective cpus */
+ if (cpumask_empty(new_cpus) && !is_partition_valid(cs))
+ cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus);
+ if (nodes_empty(*new_mems))
+ *new_mems = parent_cs(cs)->effective_mems;
+
+ spin_lock_irq(&callback_lock);
+ cpumask_copy(cs->effective_cpus, new_cpus);
+ cs->effective_mems = *new_mems;
+ spin_unlock_irq(&callback_lock);
+
+ if (cpus_updated)
+ update_tasks_cpumask(cs, new_cpus);
+ if (mems_updated)
+ update_tasks_nodemask(cs);
+}
+
+static bool force_rebuild;
+
+void cpuset_force_rebuild(void)
+{
+ force_rebuild = true;
+}
+
+/**
+ * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
+ * @cs: cpuset in interest
+ * @tmp: the tmpmasks structure pointer
+ *
+ * Compare @cs's cpu and mem masks against top_cpuset and if some have gone
+ * offline, update @cs accordingly. If @cs ends up with no CPU or memory,
+ * all its tasks are moved to the nearest ancestor with both resources.
+ */
+static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp)
+{
+ static cpumask_t new_cpus;
+ static nodemask_t new_mems;
+ bool cpus_updated;
+ bool mems_updated;
+ struct cpuset *parent;
+retry:
+ wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
+
+ mutex_lock(&cpuset_mutex);
+
+ /*
+ * We have raced with task attaching. We wait until attaching
+ * is finished, so we won't attach a task to an empty cpuset.
+ */
+ if (cs->attach_in_progress) {
+ mutex_unlock(&cpuset_mutex);
+ goto retry;
+ }
+
+ parent = parent_cs(cs);
+ compute_effective_cpumask(&new_cpus, cs, parent);
+ nodes_and(new_mems, cs->mems_allowed, parent->effective_mems);
+
+ if (cs->nr_subparts_cpus)
+ /*
+ * Make sure that CPUs allocated to child partitions
+ * do not show up in effective_cpus.
+ */
+ cpumask_andnot(&new_cpus, &new_cpus, cs->subparts_cpus);
+
+ if (!tmp || !cs->partition_root_state)
+ goto update_tasks;
+
+ /*
+ * In the unlikely event that a partition root has empty
+ * effective_cpus with tasks, we will have to invalidate child
+ * partitions, if present, by setting nr_subparts_cpus to 0 to
+ * reclaim their cpus.
+ */
+ if (cs->nr_subparts_cpus && is_partition_valid(cs) &&
+ cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)) {
+ spin_lock_irq(&callback_lock);
+ cs->nr_subparts_cpus = 0;
+ cpumask_clear(cs->subparts_cpus);
+ spin_unlock_irq(&callback_lock);
+ compute_effective_cpumask(&new_cpus, cs, parent);
+ }
+
+ /*
+ * Force the partition to become invalid if either one of
+ * the following conditions hold:
+ * 1) empty effective cpus but not valid empty partition.
+ * 2) parent is invalid or doesn't grant any cpus to child
+ * partitions.
+ */
+ if (is_partition_valid(cs) && (!parent->nr_subparts_cpus ||
+ (cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)))) {
+ int old_prs, parent_prs;
+
+ update_parent_subparts_cpumask(cs, partcmd_disable, NULL, tmp);
+ if (cs->nr_subparts_cpus) {
+ spin_lock_irq(&callback_lock);
+ cs->nr_subparts_cpus = 0;
+ cpumask_clear(cs->subparts_cpus);
+ spin_unlock_irq(&callback_lock);
+ compute_effective_cpumask(&new_cpus, cs, parent);
+ }
+
+ old_prs = cs->partition_root_state;
+ parent_prs = parent->partition_root_state;
+ if (is_partition_valid(cs)) {
+ spin_lock_irq(&callback_lock);
+ make_partition_invalid(cs);
+ spin_unlock_irq(&callback_lock);
+ if (is_prs_invalid(parent_prs))
+ WRITE_ONCE(cs->prs_err, PERR_INVPARENT);
+ else if (!parent_prs)
+ WRITE_ONCE(cs->prs_err, PERR_NOTPART);
+ else
+ WRITE_ONCE(cs->prs_err, PERR_HOTPLUG);
+ notify_partition_change(cs, old_prs);
+ }
+ cpuset_force_rebuild();
+ }
+
+ /*
+ * On the other hand, an invalid partition root may be transitioned
+ * back to a regular one.
+ */
+ else if (is_partition_valid(parent) && is_partition_invalid(cs)) {
+ update_parent_subparts_cpumask(cs, partcmd_update, NULL, tmp);
+ if (is_partition_valid(cs))
+ cpuset_force_rebuild();
+ }
+
+update_tasks:
+ cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus);
+ mems_updated = !nodes_equal(new_mems, cs->effective_mems);
+ if (!cpus_updated && !mems_updated)
+ goto unlock; /* Hotplug doesn't affect this cpuset */
+
+ if (mems_updated)
+ check_insane_mems_config(&new_mems);
+
+ if (is_in_v2_mode())
+ hotplug_update_tasks(cs, &new_cpus, &new_mems,
+ cpus_updated, mems_updated);
+ else
+ hotplug_update_tasks_legacy(cs, &new_cpus, &new_mems,
+ cpus_updated, mems_updated);
+
+unlock:
+ mutex_unlock(&cpuset_mutex);
+}
+
+/**
+ * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
+ * @work: unused
+ *
+ * This function is called after either CPU or memory configuration has
+ * changed and updates cpuset accordingly. The top_cpuset is always
+ * synchronized to cpu_active_mask and N_MEMORY, which is necessary in
+ * order to make cpusets transparent (of no affect) on systems that are
+ * actively using CPU hotplug but making no active use of cpusets.
+ *
+ * Non-root cpusets are only affected by offlining. If any CPUs or memory
+ * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on
+ * all descendants.
+ *
+ * Note that CPU offlining during suspend is ignored. We don't modify
+ * cpusets across suspend/resume cycles at all.
+ */
+static void cpuset_hotplug_workfn(struct work_struct *work)
+{
+ static cpumask_t new_cpus;
+ static nodemask_t new_mems;
+ bool cpus_updated, mems_updated;
+ bool on_dfl = is_in_v2_mode();
+ struct tmpmasks tmp, *ptmp = NULL;
+
+ if (on_dfl && !alloc_cpumasks(NULL, &tmp))
+ ptmp = &tmp;
+
+ mutex_lock(&cpuset_mutex);
+
+ /* fetch the available cpus/mems and find out which changed how */
+ cpumask_copy(&new_cpus, cpu_active_mask);
+ new_mems = node_states[N_MEMORY];
+
+ /*
+ * If subparts_cpus is populated, it is likely that the check below
+ * will produce a false positive on cpus_updated when the cpu list
+ * isn't changed. It is extra work, but it is better to be safe.
+ */
+ cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus);
+ mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
+
+ /*
+ * In the rare case that hotplug removes all the cpus in subparts_cpus,
+ * we assumed that cpus are updated.
+ */
+ if (!cpus_updated && top_cpuset.nr_subparts_cpus)
+ cpus_updated = true;
+
+ /* synchronize cpus_allowed to cpu_active_mask */
+ if (cpus_updated) {
+ spin_lock_irq(&callback_lock);
+ if (!on_dfl)
+ cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
+ /*
+ * Make sure that CPUs allocated to child partitions
+ * do not show up in effective_cpus. If no CPU is left,
+ * we clear the subparts_cpus & let the child partitions
+ * fight for the CPUs again.
+ */
+ if (top_cpuset.nr_subparts_cpus) {
+ if (cpumask_subset(&new_cpus,
+ top_cpuset.subparts_cpus)) {
+ top_cpuset.nr_subparts_cpus = 0;
+ cpumask_clear(top_cpuset.subparts_cpus);
+ } else {
+ cpumask_andnot(&new_cpus, &new_cpus,
+ top_cpuset.subparts_cpus);
+ }
+ }
+ cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
+ spin_unlock_irq(&callback_lock);
+ /* we don't mess with cpumasks of tasks in top_cpuset */
+ }
+
+ /* synchronize mems_allowed to N_MEMORY */
+ if (mems_updated) {
+ spin_lock_irq(&callback_lock);
+ if (!on_dfl)
+ top_cpuset.mems_allowed = new_mems;
+ top_cpuset.effective_mems = new_mems;
+ spin_unlock_irq(&callback_lock);
+ update_tasks_nodemask(&top_cpuset);
+ }
+
+ mutex_unlock(&cpuset_mutex);
+
+ /* if cpus or mems changed, we need to propagate to descendants */
+ if (cpus_updated || mems_updated) {
+ struct cpuset *cs;
+ struct cgroup_subsys_state *pos_css;
+
+ rcu_read_lock();
+ cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
+ if (cs == &top_cpuset || !css_tryget_online(&cs->css))
+ continue;
+ rcu_read_unlock();
+
+ cpuset_hotplug_update_tasks(cs, ptmp);
+
+ rcu_read_lock();
+ css_put(&cs->css);
+ }
+ rcu_read_unlock();
+ }
+
+ /* rebuild sched domains if cpus_allowed has changed */
+ if (cpus_updated || force_rebuild) {
+ force_rebuild = false;
+ rebuild_sched_domains();
+ }
+
+ free_cpumasks(NULL, ptmp);
+}
+
+void cpuset_update_active_cpus(void)
+{
+ /*
+ * We're inside cpu hotplug critical region which usually nests
+ * inside cgroup synchronization. Bounce actual hotplug processing
+ * to a work item to avoid reverse locking order.
+ */
+ schedule_work(&cpuset_hotplug_work);
+}
+
+void cpuset_wait_for_hotplug(void)
+{
+ flush_work(&cpuset_hotplug_work);
+}
+
+/*
+ * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
+ * Call this routine anytime after node_states[N_MEMORY] changes.
+ * See cpuset_update_active_cpus() for CPU hotplug handling.
+ */
+static int cpuset_track_online_nodes(struct notifier_block *self,
+ unsigned long action, void *arg)
+{
+ schedule_work(&cpuset_hotplug_work);
+ return NOTIFY_OK;
+}
+
+/**
+ * cpuset_init_smp - initialize cpus_allowed
+ *
+ * Description: Finish top cpuset after cpu, node maps are initialized
+ */
+void __init cpuset_init_smp(void)
+{
+ /*
+ * cpus_allowd/mems_allowed set to v2 values in the initial
+ * cpuset_bind() call will be reset to v1 values in another
+ * cpuset_bind() call when v1 cpuset is mounted.
+ */
+ top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
+
+ cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);
+ top_cpuset.effective_mems = node_states[N_MEMORY];
+
+ hotplug_memory_notifier(cpuset_track_online_nodes, CPUSET_CALLBACK_PRI);
+
+ cpuset_migrate_mm_wq = alloc_ordered_workqueue("cpuset_migrate_mm", 0);
+ BUG_ON(!cpuset_migrate_mm_wq);
+}
+
+/**
+ * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
+ * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
+ * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
+ *
+ * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
+ * attached to the specified @tsk. Guaranteed to return some non-empty
+ * subset of cpu_online_mask, even if this means going outside the
+ * tasks cpuset, except when the task is in the top cpuset.
+ **/
+
+void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
+{
+ unsigned long flags;
+ struct cpuset *cs;
+
+ spin_lock_irqsave(&callback_lock, flags);
+ rcu_read_lock();
+
+ cs = task_cs(tsk);
+ if (cs != &top_cpuset)
+ guarantee_online_cpus(tsk, pmask);
+ /*
+ * Tasks in the top cpuset won't get update to their cpumasks
+ * when a hotplug online/offline event happens. So we include all
+ * offline cpus in the allowed cpu list.
+ */
+ if ((cs == &top_cpuset) || cpumask_empty(pmask)) {
+ const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
+
+ /*
+ * We first exclude cpus allocated to partitions. If there is no
+ * allowable online cpu left, we fall back to all possible cpus.
+ */
+ cpumask_andnot(pmask, possible_mask, top_cpuset.subparts_cpus);
+ if (!cpumask_intersects(pmask, cpu_online_mask))
+ cpumask_copy(pmask, possible_mask);
+ }
+
+ rcu_read_unlock();
+ spin_unlock_irqrestore(&callback_lock, flags);
+}
+
+/**
+ * cpuset_cpus_allowed_fallback - final fallback before complete catastrophe.
+ * @tsk: pointer to task_struct with which the scheduler is struggling
+ *
+ * Description: In the case that the scheduler cannot find an allowed cpu in
+ * tsk->cpus_allowed, we fall back to task_cs(tsk)->cpus_allowed. In legacy
+ * mode however, this value is the same as task_cs(tsk)->effective_cpus,
+ * which will not contain a sane cpumask during cases such as cpu hotplugging.
+ * This is the absolute last resort for the scheduler and it is only used if
+ * _every_ other avenue has been traveled.
+ *
+ * Returns true if the affinity of @tsk was changed, false otherwise.
+ **/
+
+bool cpuset_cpus_allowed_fallback(struct task_struct *tsk)
+{
+ const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
+ const struct cpumask *cs_mask;
+ bool changed = false;
+
+ rcu_read_lock();
+ cs_mask = task_cs(tsk)->cpus_allowed;
+ if (is_in_v2_mode() && cpumask_subset(cs_mask, possible_mask)) {
+ do_set_cpus_allowed(tsk, cs_mask);
+ changed = true;
+ }
+ rcu_read_unlock();
+
+ /*
+ * We own tsk->cpus_allowed, nobody can change it under us.
+ *
+ * But we used cs && cs->cpus_allowed lockless and thus can
+ * race with cgroup_attach_task() or update_cpumask() and get
+ * the wrong tsk->cpus_allowed. However, both cases imply the
+ * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
+ * which takes task_rq_lock().
+ *
+ * If we are called after it dropped the lock we must see all
+ * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
+ * set any mask even if it is not right from task_cs() pov,
+ * the pending set_cpus_allowed_ptr() will fix things.
+ *
+ * select_fallback_rq() will fix things ups and set cpu_possible_mask
+ * if required.
+ */
+ return changed;
+}
+
+void __init cpuset_init_current_mems_allowed(void)
+{
+ nodes_setall(current->mems_allowed);
+}
+
+/**
+ * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
+ * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
+ *
+ * Description: Returns the nodemask_t mems_allowed of the cpuset
+ * attached to the specified @tsk. Guaranteed to return some non-empty
+ * subset of node_states[N_MEMORY], even if this means going outside the
+ * tasks cpuset.
+ **/
+
+nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
+{
+ nodemask_t mask;
+ unsigned long flags;
+
+ spin_lock_irqsave(&callback_lock, flags);
+ rcu_read_lock();
+ guarantee_online_mems(task_cs(tsk), &mask);
+ rcu_read_unlock();
+ spin_unlock_irqrestore(&callback_lock, flags);
+
+ return mask;
+}
+
+/**
+ * cpuset_nodemask_valid_mems_allowed - check nodemask vs. current mems_allowed
+ * @nodemask: the nodemask to be checked
+ *
+ * Are any of the nodes in the nodemask allowed in current->mems_allowed?
+ */
+int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
+{
+ return nodes_intersects(*nodemask, current->mems_allowed);
+}
+
+/*
+ * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
+ * mem_hardwall ancestor to the specified cpuset. Call holding
+ * callback_lock. If no ancestor is mem_exclusive or mem_hardwall
+ * (an unusual configuration), then returns the root cpuset.
+ */
+static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
+{
+ while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs))
+ cs = parent_cs(cs);
+ return cs;
+}
+
+/*
+ * cpuset_node_allowed - Can we allocate on a memory node?
+ * @node: is this an allowed node?
+ * @gfp_mask: memory allocation flags
+ *
+ * If we're in interrupt, yes, we can always allocate. If @node is set in
+ * current's mems_allowed, yes. If it's not a __GFP_HARDWALL request and this
+ * node is set in the nearest hardwalled cpuset ancestor to current's cpuset,
+ * yes. If current has access to memory reserves as an oom victim, yes.
+ * Otherwise, no.
+ *
+ * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
+ * and do not allow allocations outside the current tasks cpuset
+ * unless the task has been OOM killed.
+ * GFP_KERNEL allocations are not so marked, so can escape to the
+ * nearest enclosing hardwalled ancestor cpuset.
+ *
+ * Scanning up parent cpusets requires callback_lock. The
+ * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
+ * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
+ * current tasks mems_allowed came up empty on the first pass over
+ * the zonelist. So only GFP_KERNEL allocations, if all nodes in the
+ * cpuset are short of memory, might require taking the callback_lock.
+ *
+ * The first call here from mm/page_alloc:get_page_from_freelist()
+ * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
+ * so no allocation on a node outside the cpuset is allowed (unless
+ * in interrupt, of course).
+ *
+ * The second pass through get_page_from_freelist() doesn't even call
+ * here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
+ * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
+ * in alloc_flags. That logic and the checks below have the combined
+ * affect that:
+ * in_interrupt - any node ok (current task context irrelevant)
+ * GFP_ATOMIC - any node ok
+ * tsk_is_oom_victim - any node ok
+ * GFP_KERNEL - any node in enclosing hardwalled cpuset ok
+ * GFP_USER - only nodes in current tasks mems allowed ok.
+ */
+bool cpuset_node_allowed(int node, gfp_t gfp_mask)
+{
+ struct cpuset *cs; /* current cpuset ancestors */
+ bool allowed; /* is allocation in zone z allowed? */
+ unsigned long flags;
+
+ if (in_interrupt())
+ return true;
+ if (node_isset(node, current->mems_allowed))
+ return true;
+ /*
+ * Allow tasks that have access to memory reserves because they have
+ * been OOM killed to get memory anywhere.
+ */
+ if (unlikely(tsk_is_oom_victim(current)))
+ return true;
+ if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
+ return false;
+
+ if (current->flags & PF_EXITING) /* Let dying task have memory */
+ return true;
+
+ /* Not hardwall and node outside mems_allowed: scan up cpusets */
+ spin_lock_irqsave(&callback_lock, flags);
+
+ rcu_read_lock();
+ cs = nearest_hardwall_ancestor(task_cs(current));
+ allowed = node_isset(node, cs->mems_allowed);
+ rcu_read_unlock();
+
+ spin_unlock_irqrestore(&callback_lock, flags);
+ return allowed;
+}
+
+/**
+ * cpuset_spread_node() - On which node to begin search for a page
+ * @rotor: round robin rotor
+ *
+ * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
+ * tasks in a cpuset with is_spread_page or is_spread_slab set),
+ * and if the memory allocation used cpuset_mem_spread_node()
+ * to determine on which node to start looking, as it will for
+ * certain page cache or slab cache pages such as used for file
+ * system buffers and inode caches, then instead of starting on the
+ * local node to look for a free page, rather spread the starting
+ * node around the tasks mems_allowed nodes.
+ *
+ * We don't have to worry about the returned node being offline
+ * because "it can't happen", and even if it did, it would be ok.
+ *
+ * The routines calling guarantee_online_mems() are careful to
+ * only set nodes in task->mems_allowed that are online. So it
+ * should not be possible for the following code to return an
+ * offline node. But if it did, that would be ok, as this routine
+ * is not returning the node where the allocation must be, only
+ * the node where the search should start. The zonelist passed to
+ * __alloc_pages() will include all nodes. If the slab allocator
+ * is passed an offline node, it will fall back to the local node.
+ * See kmem_cache_alloc_node().
+ */
+static int cpuset_spread_node(int *rotor)
+{
+ return *rotor = next_node_in(*rotor, current->mems_allowed);
+}
+
+/**
+ * cpuset_mem_spread_node() - On which node to begin search for a file page
+ */
+int cpuset_mem_spread_node(void)
+{
+ if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
+ current->cpuset_mem_spread_rotor =
+ node_random(&current->mems_allowed);
+
+ return cpuset_spread_node(&current->cpuset_mem_spread_rotor);
+}
+
+/**
+ * cpuset_slab_spread_node() - On which node to begin search for a slab page
+ */
+int cpuset_slab_spread_node(void)
+{
+ if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
+ current->cpuset_slab_spread_rotor =
+ node_random(&current->mems_allowed);
+
+ return cpuset_spread_node(&current->cpuset_slab_spread_rotor);
+}
+EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
+
+/**
+ * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
+ * @tsk1: pointer to task_struct of some task.
+ * @tsk2: pointer to task_struct of some other task.
+ *
+ * Description: Return true if @tsk1's mems_allowed intersects the
+ * mems_allowed of @tsk2. Used by the OOM killer to determine if
+ * one of the task's memory usage might impact the memory available
+ * to the other.
+ **/
+
+int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
+ const struct task_struct *tsk2)
+{
+ return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
+}
+
+/**
+ * cpuset_print_current_mems_allowed - prints current's cpuset and mems_allowed
+ *
+ * Description: Prints current's name, cpuset name, and cached copy of its
+ * mems_allowed to the kernel log.
+ */
+void cpuset_print_current_mems_allowed(void)
+{
+ struct cgroup *cgrp;
+
+ rcu_read_lock();
+
+ cgrp = task_cs(current)->css.cgroup;
+ pr_cont(",cpuset=");
+ pr_cont_cgroup_name(cgrp);
+ pr_cont(",mems_allowed=%*pbl",
+ nodemask_pr_args(&current->mems_allowed));
+
+ rcu_read_unlock();
+}
+
+/*
+ * Collection of memory_pressure is suppressed unless
+ * this flag is enabled by writing "1" to the special
+ * cpuset file 'memory_pressure_enabled' in the root cpuset.
+ */
+
+int cpuset_memory_pressure_enabled __read_mostly;
+
+/*
+ * __cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
+ *
+ * Keep a running average of the rate of synchronous (direct)
+ * page reclaim efforts initiated by tasks in each cpuset.
+ *
+ * This represents the rate at which some task in the cpuset
+ * ran low on memory on all nodes it was allowed to use, and
+ * had to enter the kernels page reclaim code in an effort to
+ * create more free memory by tossing clean pages or swapping
+ * or writing dirty pages.
+ *
+ * Display to user space in the per-cpuset read-only file
+ * "memory_pressure". Value displayed is an integer
+ * representing the recent rate of entry into the synchronous
+ * (direct) page reclaim by any task attached to the cpuset.
+ */
+
+void __cpuset_memory_pressure_bump(void)
+{
+ rcu_read_lock();
+ fmeter_markevent(&task_cs(current)->fmeter);
+ rcu_read_unlock();
+}
+
+#ifdef CONFIG_PROC_PID_CPUSET
+/*
+ * proc_cpuset_show()
+ * - Print tasks cpuset path into seq_file.
+ * - Used for /proc/<pid>/cpuset.
+ * - No need to task_lock(tsk) on this tsk->cpuset reference, as it
+ * doesn't really matter if tsk->cpuset changes after we read it,
+ * and we take cpuset_mutex, keeping cpuset_attach() from changing it
+ * anyway.
+ */
+int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *tsk)
+{
+ char *buf;
+ struct cgroup_subsys_state *css;
+ int retval;
+
+ retval = -ENOMEM;
+ buf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!buf)
+ goto out;
+
+ css = task_get_css(tsk, cpuset_cgrp_id);
+ retval = cgroup_path_ns(css->cgroup, buf, PATH_MAX,
+ current->nsproxy->cgroup_ns);
+ css_put(css);
+ if (retval >= PATH_MAX)
+ retval = -ENAMETOOLONG;
+ if (retval < 0)
+ goto out_free;
+ seq_puts(m, buf);
+ seq_putc(m, '\n');
+ retval = 0;
+out_free:
+ kfree(buf);
+out:
+ return retval;
+}
+#endif /* CONFIG_PROC_PID_CPUSET */
+
+/* Display task mems_allowed in /proc/<pid>/status file. */
+void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
+{
+ seq_printf(m, "Mems_allowed:\t%*pb\n",
+ nodemask_pr_args(&task->mems_allowed));
+ seq_printf(m, "Mems_allowed_list:\t%*pbl\n",
+ nodemask_pr_args(&task->mems_allowed));
+}
diff --git a/kernel/cgroup/debug.c b/kernel/cgroup/debug.c
new file mode 100644
index 0000000000..80aa3f027a
--- /dev/null
+++ b/kernel/cgroup/debug.c
@@ -0,0 +1,381 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Debug controller
+ *
+ * WARNING: This controller is for cgroup core debugging only.
+ * Its interfaces are unstable and subject to changes at any time.
+ */
+#include <linux/ctype.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+
+#include "cgroup-internal.h"
+
+static struct cgroup_subsys_state *
+debug_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+ struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
+
+ if (!css)
+ return ERR_PTR(-ENOMEM);
+
+ return css;
+}
+
+static void debug_css_free(struct cgroup_subsys_state *css)
+{
+ kfree(css);
+}
+
+/*
+ * debug_taskcount_read - return the number of tasks in a cgroup.
+ * @cgrp: the cgroup in question
+ */
+static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ return cgroup_task_count(css->cgroup);
+}
+
+static int current_css_set_read(struct seq_file *seq, void *v)
+{
+ struct kernfs_open_file *of = seq->private;
+ struct css_set *cset;
+ struct cgroup_subsys *ss;
+ struct cgroup_subsys_state *css;
+ int i, refcnt;
+
+ if (!cgroup_kn_lock_live(of->kn, false))
+ return -ENODEV;
+
+ spin_lock_irq(&css_set_lock);
+ rcu_read_lock();
+ cset = task_css_set(current);
+ refcnt = refcount_read(&cset->refcount);
+ seq_printf(seq, "css_set %pK %d", cset, refcnt);
+ if (refcnt > cset->nr_tasks)
+ seq_printf(seq, " +%d", refcnt - cset->nr_tasks);
+ seq_puts(seq, "\n");
+
+ /*
+ * Print the css'es stored in the current css_set.
+ */
+ for_each_subsys(ss, i) {
+ css = cset->subsys[ss->id];
+ if (!css)
+ continue;
+ seq_printf(seq, "%2d: %-4s\t- %p[%d]\n", ss->id, ss->name,
+ css, css->id);
+ }
+ rcu_read_unlock();
+ spin_unlock_irq(&css_set_lock);
+ cgroup_kn_unlock(of->kn);
+ return 0;
+}
+
+static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ u64 count;
+
+ rcu_read_lock();
+ count = refcount_read(&task_css_set(current)->refcount);
+ rcu_read_unlock();
+ return count;
+}
+
+static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
+{
+ struct cgrp_cset_link *link;
+ struct css_set *cset;
+ char *name_buf;
+
+ name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
+ if (!name_buf)
+ return -ENOMEM;
+
+ spin_lock_irq(&css_set_lock);
+ rcu_read_lock();
+ cset = task_css_set(current);
+ list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
+ struct cgroup *c = link->cgrp;
+
+ cgroup_name(c, name_buf, NAME_MAX + 1);
+ seq_printf(seq, "Root %d group %s\n",
+ c->root->hierarchy_id, name_buf);
+ }
+ rcu_read_unlock();
+ spin_unlock_irq(&css_set_lock);
+ kfree(name_buf);
+ return 0;
+}
+
+#define MAX_TASKS_SHOWN_PER_CSS 25
+static int cgroup_css_links_read(struct seq_file *seq, void *v)
+{
+ struct cgroup_subsys_state *css = seq_css(seq);
+ struct cgrp_cset_link *link;
+ int dead_cnt = 0, extra_refs = 0, threaded_csets = 0;
+
+ spin_lock_irq(&css_set_lock);
+
+ list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
+ struct css_set *cset = link->cset;
+ struct task_struct *task;
+ int count = 0;
+ int refcnt = refcount_read(&cset->refcount);
+
+ /*
+ * Print out the proc_cset and threaded_cset relationship
+ * and highlight difference between refcount and task_count.
+ */
+ seq_printf(seq, "css_set %pK", cset);
+ if (rcu_dereference_protected(cset->dom_cset, 1) != cset) {
+ threaded_csets++;
+ seq_printf(seq, "=>%pK", cset->dom_cset);
+ }
+ if (!list_empty(&cset->threaded_csets)) {
+ struct css_set *tcset;
+ int idx = 0;
+
+ list_for_each_entry(tcset, &cset->threaded_csets,
+ threaded_csets_node) {
+ seq_puts(seq, idx ? "," : "<=");
+ seq_printf(seq, "%pK", tcset);
+ idx++;
+ }
+ } else {
+ seq_printf(seq, " %d", refcnt);
+ if (refcnt - cset->nr_tasks > 0) {
+ int extra = refcnt - cset->nr_tasks;
+
+ seq_printf(seq, " +%d", extra);
+ /*
+ * Take out the one additional reference in
+ * init_css_set.
+ */
+ if (cset == &init_css_set)
+ extra--;
+ extra_refs += extra;
+ }
+ }
+ seq_puts(seq, "\n");
+
+ list_for_each_entry(task, &cset->tasks, cg_list) {
+ if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
+ seq_printf(seq, " task %d\n",
+ task_pid_vnr(task));
+ }
+
+ list_for_each_entry(task, &cset->mg_tasks, cg_list) {
+ if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
+ seq_printf(seq, " task %d\n",
+ task_pid_vnr(task));
+ }
+ /* show # of overflowed tasks */
+ if (count > MAX_TASKS_SHOWN_PER_CSS)
+ seq_printf(seq, " ... (%d)\n",
+ count - MAX_TASKS_SHOWN_PER_CSS);
+
+ if (cset->dead) {
+ seq_puts(seq, " [dead]\n");
+ dead_cnt++;
+ }
+
+ WARN_ON(count != cset->nr_tasks);
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ if (!dead_cnt && !extra_refs && !threaded_csets)
+ return 0;
+
+ seq_puts(seq, "\n");
+ if (threaded_csets)
+ seq_printf(seq, "threaded css_sets = %d\n", threaded_csets);
+ if (extra_refs)
+ seq_printf(seq, "extra references = %d\n", extra_refs);
+ if (dead_cnt)
+ seq_printf(seq, "dead css_sets = %d\n", dead_cnt);
+
+ return 0;
+}
+
+static int cgroup_subsys_states_read(struct seq_file *seq, void *v)
+{
+ struct kernfs_open_file *of = seq->private;
+ struct cgroup *cgrp;
+ struct cgroup_subsys *ss;
+ struct cgroup_subsys_state *css;
+ char pbuf[16];
+ int i;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENODEV;
+
+ for_each_subsys(ss, i) {
+ css = rcu_dereference_check(cgrp->subsys[ss->id], true);
+ if (!css)
+ continue;
+
+ pbuf[0] = '\0';
+
+ /* Show the parent CSS if applicable*/
+ if (css->parent)
+ snprintf(pbuf, sizeof(pbuf) - 1, " P=%d",
+ css->parent->id);
+ seq_printf(seq, "%2d: %-4s\t- %p[%d] %d%s\n", ss->id, ss->name,
+ css, css->id,
+ atomic_read(&css->online_cnt), pbuf);
+ }
+
+ cgroup_kn_unlock(of->kn);
+ return 0;
+}
+
+static void cgroup_masks_read_one(struct seq_file *seq, const char *name,
+ u16 mask)
+{
+ struct cgroup_subsys *ss;
+ int ssid;
+ bool first = true;
+
+ seq_printf(seq, "%-17s: ", name);
+ for_each_subsys(ss, ssid) {
+ if (!(mask & (1 << ssid)))
+ continue;
+ if (!first)
+ seq_puts(seq, ", ");
+ seq_puts(seq, ss->name);
+ first = false;
+ }
+ seq_putc(seq, '\n');
+}
+
+static int cgroup_masks_read(struct seq_file *seq, void *v)
+{
+ struct kernfs_open_file *of = seq->private;
+ struct cgroup *cgrp;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENODEV;
+
+ cgroup_masks_read_one(seq, "subtree_control", cgrp->subtree_control);
+ cgroup_masks_read_one(seq, "subtree_ss_mask", cgrp->subtree_ss_mask);
+
+ cgroup_kn_unlock(of->kn);
+ return 0;
+}
+
+static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
+{
+ return (!cgroup_is_populated(css->cgroup) &&
+ !css_has_online_children(&css->cgroup->self));
+}
+
+static struct cftype debug_legacy_files[] = {
+ {
+ .name = "taskcount",
+ .read_u64 = debug_taskcount_read,
+ },
+
+ {
+ .name = "current_css_set",
+ .seq_show = current_css_set_read,
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ },
+
+ {
+ .name = "current_css_set_refcount",
+ .read_u64 = current_css_set_refcount_read,
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ },
+
+ {
+ .name = "current_css_set_cg_links",
+ .seq_show = current_css_set_cg_links_read,
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ },
+
+ {
+ .name = "cgroup_css_links",
+ .seq_show = cgroup_css_links_read,
+ },
+
+ {
+ .name = "cgroup_subsys_states",
+ .seq_show = cgroup_subsys_states_read,
+ },
+
+ {
+ .name = "cgroup_masks",
+ .seq_show = cgroup_masks_read,
+ },
+
+ {
+ .name = "releasable",
+ .read_u64 = releasable_read,
+ },
+
+ { } /* terminate */
+};
+
+static struct cftype debug_files[] = {
+ {
+ .name = "taskcount",
+ .read_u64 = debug_taskcount_read,
+ },
+
+ {
+ .name = "current_css_set",
+ .seq_show = current_css_set_read,
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ },
+
+ {
+ .name = "current_css_set_refcount",
+ .read_u64 = current_css_set_refcount_read,
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ },
+
+ {
+ .name = "current_css_set_cg_links",
+ .seq_show = current_css_set_cg_links_read,
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ },
+
+ {
+ .name = "css_links",
+ .seq_show = cgroup_css_links_read,
+ },
+
+ {
+ .name = "csses",
+ .seq_show = cgroup_subsys_states_read,
+ },
+
+ {
+ .name = "masks",
+ .seq_show = cgroup_masks_read,
+ },
+
+ { } /* terminate */
+};
+
+struct cgroup_subsys debug_cgrp_subsys = {
+ .css_alloc = debug_css_alloc,
+ .css_free = debug_css_free,
+ .legacy_cftypes = debug_legacy_files,
+};
+
+/*
+ * On v2, debug is an implicit controller enabled by "cgroup_debug" boot
+ * parameter.
+ */
+void __init enable_debug_cgroup(void)
+{
+ debug_cgrp_subsys.dfl_cftypes = debug_files;
+ debug_cgrp_subsys.implicit_on_dfl = true;
+ debug_cgrp_subsys.threaded = true;
+}
diff --git a/kernel/cgroup/freezer.c b/kernel/cgroup/freezer.c
new file mode 100644
index 0000000000..617861a547
--- /dev/null
+++ b/kernel/cgroup/freezer.c
@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/cgroup.h>
+#include <linux/sched.h>
+#include <linux/sched/task.h>
+#include <linux/sched/signal.h>
+
+#include "cgroup-internal.h"
+
+#include <trace/events/cgroup.h>
+
+/*
+ * Propagate the cgroup frozen state upwards by the cgroup tree.
+ */
+static void cgroup_propagate_frozen(struct cgroup *cgrp, bool frozen)
+{
+ int desc = 1;
+
+ /*
+ * If the new state is frozen, some freezing ancestor cgroups may change
+ * their state too, depending on if all their descendants are frozen.
+ *
+ * Otherwise, all ancestor cgroups are forced into the non-frozen state.
+ */
+ while ((cgrp = cgroup_parent(cgrp))) {
+ if (frozen) {
+ cgrp->freezer.nr_frozen_descendants += desc;
+ if (!test_bit(CGRP_FROZEN, &cgrp->flags) &&
+ test_bit(CGRP_FREEZE, &cgrp->flags) &&
+ cgrp->freezer.nr_frozen_descendants ==
+ cgrp->nr_descendants) {
+ set_bit(CGRP_FROZEN, &cgrp->flags);
+ cgroup_file_notify(&cgrp->events_file);
+ TRACE_CGROUP_PATH(notify_frozen, cgrp, 1);
+ desc++;
+ }
+ } else {
+ cgrp->freezer.nr_frozen_descendants -= desc;
+ if (test_bit(CGRP_FROZEN, &cgrp->flags)) {
+ clear_bit(CGRP_FROZEN, &cgrp->flags);
+ cgroup_file_notify(&cgrp->events_file);
+ TRACE_CGROUP_PATH(notify_frozen, cgrp, 0);
+ desc++;
+ }
+ }
+ }
+}
+
+/*
+ * Revisit the cgroup frozen state.
+ * Checks if the cgroup is really frozen and perform all state transitions.
+ */
+void cgroup_update_frozen(struct cgroup *cgrp)
+{
+ bool frozen;
+
+ lockdep_assert_held(&css_set_lock);
+
+ /*
+ * If the cgroup has to be frozen (CGRP_FREEZE bit set),
+ * and all tasks are frozen and/or stopped, let's consider
+ * the cgroup frozen. Otherwise it's not frozen.
+ */
+ frozen = test_bit(CGRP_FREEZE, &cgrp->flags) &&
+ cgrp->freezer.nr_frozen_tasks == __cgroup_task_count(cgrp);
+
+ if (frozen) {
+ /* Already there? */
+ if (test_bit(CGRP_FROZEN, &cgrp->flags))
+ return;
+
+ set_bit(CGRP_FROZEN, &cgrp->flags);
+ } else {
+ /* Already there? */
+ if (!test_bit(CGRP_FROZEN, &cgrp->flags))
+ return;
+
+ clear_bit(CGRP_FROZEN, &cgrp->flags);
+ }
+ cgroup_file_notify(&cgrp->events_file);
+ TRACE_CGROUP_PATH(notify_frozen, cgrp, frozen);
+
+ /* Update the state of ancestor cgroups. */
+ cgroup_propagate_frozen(cgrp, frozen);
+}
+
+/*
+ * Increment cgroup's nr_frozen_tasks.
+ */
+static void cgroup_inc_frozen_cnt(struct cgroup *cgrp)
+{
+ cgrp->freezer.nr_frozen_tasks++;
+}
+
+/*
+ * Decrement cgroup's nr_frozen_tasks.
+ */
+static void cgroup_dec_frozen_cnt(struct cgroup *cgrp)
+{
+ cgrp->freezer.nr_frozen_tasks--;
+ WARN_ON_ONCE(cgrp->freezer.nr_frozen_tasks < 0);
+}
+
+/*
+ * Enter frozen/stopped state, if not yet there. Update cgroup's counters,
+ * and revisit the state of the cgroup, if necessary.
+ */
+void cgroup_enter_frozen(void)
+{
+ struct cgroup *cgrp;
+
+ if (current->frozen)
+ return;
+
+ spin_lock_irq(&css_set_lock);
+ current->frozen = true;
+ cgrp = task_dfl_cgroup(current);
+ cgroup_inc_frozen_cnt(cgrp);
+ cgroup_update_frozen(cgrp);
+ spin_unlock_irq(&css_set_lock);
+}
+
+/*
+ * Conditionally leave frozen/stopped state. Update cgroup's counters,
+ * and revisit the state of the cgroup, if necessary.
+ *
+ * If always_leave is not set, and the cgroup is freezing,
+ * we're racing with the cgroup freezing. In this case, we don't
+ * drop the frozen counter to avoid a transient switch to
+ * the unfrozen state.
+ */
+void cgroup_leave_frozen(bool always_leave)
+{
+ struct cgroup *cgrp;
+
+ spin_lock_irq(&css_set_lock);
+ cgrp = task_dfl_cgroup(current);
+ if (always_leave || !test_bit(CGRP_FREEZE, &cgrp->flags)) {
+ cgroup_dec_frozen_cnt(cgrp);
+ cgroup_update_frozen(cgrp);
+ WARN_ON_ONCE(!current->frozen);
+ current->frozen = false;
+ } else if (!(current->jobctl & JOBCTL_TRAP_FREEZE)) {
+ spin_lock(&current->sighand->siglock);
+ current->jobctl |= JOBCTL_TRAP_FREEZE;
+ set_thread_flag(TIF_SIGPENDING);
+ spin_unlock(&current->sighand->siglock);
+ }
+ spin_unlock_irq(&css_set_lock);
+}
+
+/*
+ * Freeze or unfreeze the task by setting or clearing the JOBCTL_TRAP_FREEZE
+ * jobctl bit.
+ */
+static void cgroup_freeze_task(struct task_struct *task, bool freeze)
+{
+ unsigned long flags;
+
+ /* If the task is about to die, don't bother with freezing it. */
+ if (!lock_task_sighand(task, &flags))
+ return;
+
+ if (freeze) {
+ task->jobctl |= JOBCTL_TRAP_FREEZE;
+ signal_wake_up(task, false);
+ } else {
+ task->jobctl &= ~JOBCTL_TRAP_FREEZE;
+ wake_up_process(task);
+ }
+
+ unlock_task_sighand(task, &flags);
+}
+
+/*
+ * Freeze or unfreeze all tasks in the given cgroup.
+ */
+static void cgroup_do_freeze(struct cgroup *cgrp, bool freeze)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ spin_lock_irq(&css_set_lock);
+ if (freeze)
+ set_bit(CGRP_FREEZE, &cgrp->flags);
+ else
+ clear_bit(CGRP_FREEZE, &cgrp->flags);
+ spin_unlock_irq(&css_set_lock);
+
+ if (freeze)
+ TRACE_CGROUP_PATH(freeze, cgrp);
+ else
+ TRACE_CGROUP_PATH(unfreeze, cgrp);
+
+ css_task_iter_start(&cgrp->self, 0, &it);
+ while ((task = css_task_iter_next(&it))) {
+ /*
+ * Ignore kernel threads here. Freezing cgroups containing
+ * kthreads isn't supported.
+ */
+ if (task->flags & PF_KTHREAD)
+ continue;
+ cgroup_freeze_task(task, freeze);
+ }
+ css_task_iter_end(&it);
+
+ /*
+ * Cgroup state should be revisited here to cover empty leaf cgroups
+ * and cgroups which descendants are already in the desired state.
+ */
+ spin_lock_irq(&css_set_lock);
+ if (cgrp->nr_descendants == cgrp->freezer.nr_frozen_descendants)
+ cgroup_update_frozen(cgrp);
+ spin_unlock_irq(&css_set_lock);
+}
+
+/*
+ * Adjust the task state (freeze or unfreeze) and revisit the state of
+ * source and destination cgroups.
+ */
+void cgroup_freezer_migrate_task(struct task_struct *task,
+ struct cgroup *src, struct cgroup *dst)
+{
+ lockdep_assert_held(&css_set_lock);
+
+ /*
+ * Kernel threads are not supposed to be frozen at all.
+ */
+ if (task->flags & PF_KTHREAD)
+ return;
+
+ /*
+ * It's not necessary to do changes if both of the src and dst cgroups
+ * are not freezing and task is not frozen.
+ */
+ if (!test_bit(CGRP_FREEZE, &src->flags) &&
+ !test_bit(CGRP_FREEZE, &dst->flags) &&
+ !task->frozen)
+ return;
+
+ /*
+ * Adjust counters of freezing and frozen tasks.
+ * Note, that if the task is frozen, but the destination cgroup is not
+ * frozen, we bump both counters to keep them balanced.
+ */
+ if (task->frozen) {
+ cgroup_inc_frozen_cnt(dst);
+ cgroup_dec_frozen_cnt(src);
+ }
+ cgroup_update_frozen(dst);
+ cgroup_update_frozen(src);
+
+ /*
+ * Force the task to the desired state.
+ */
+ cgroup_freeze_task(task, test_bit(CGRP_FREEZE, &dst->flags));
+}
+
+void cgroup_freeze(struct cgroup *cgrp, bool freeze)
+{
+ struct cgroup_subsys_state *css;
+ struct cgroup *dsct;
+ bool applied = false;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /*
+ * Nothing changed? Just exit.
+ */
+ if (cgrp->freezer.freeze == freeze)
+ return;
+
+ cgrp->freezer.freeze = freeze;
+
+ /*
+ * Propagate changes downwards the cgroup tree.
+ */
+ css_for_each_descendant_pre(css, &cgrp->self) {
+ dsct = css->cgroup;
+
+ if (cgroup_is_dead(dsct))
+ continue;
+
+ if (freeze) {
+ dsct->freezer.e_freeze++;
+ /*
+ * Already frozen because of ancestor's settings?
+ */
+ if (dsct->freezer.e_freeze > 1)
+ continue;
+ } else {
+ dsct->freezer.e_freeze--;
+ /*
+ * Still frozen because of ancestor's settings?
+ */
+ if (dsct->freezer.e_freeze > 0)
+ continue;
+
+ WARN_ON_ONCE(dsct->freezer.e_freeze < 0);
+ }
+
+ /*
+ * Do change actual state: freeze or unfreeze.
+ */
+ cgroup_do_freeze(dsct, freeze);
+ applied = true;
+ }
+
+ /*
+ * Even if the actual state hasn't changed, let's notify a user.
+ * The state can be enforced by an ancestor cgroup: the cgroup
+ * can already be in the desired state or it can be locked in the
+ * opposite state, so that the transition will never happen.
+ * In both cases it's better to notify a user, that there is
+ * nothing to wait for.
+ */
+ if (!applied) {
+ TRACE_CGROUP_PATH(notify_frozen, cgrp,
+ test_bit(CGRP_FROZEN, &cgrp->flags));
+ cgroup_file_notify(&cgrp->events_file);
+ }
+}
diff --git a/kernel/cgroup/legacy_freezer.c b/kernel/cgroup/legacy_freezer.c
new file mode 100644
index 0000000000..66d1708042
--- /dev/null
+++ b/kernel/cgroup/legacy_freezer.c
@@ -0,0 +1,487 @@
+/*
+ * cgroup_freezer.c - control group freezer subsystem
+ *
+ * Copyright IBM Corporation, 2007
+ *
+ * Author : Cedric Le Goater <clg@fr.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2.1 of the GNU Lesser General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/cgroup.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/freezer.h>
+#include <linux/seq_file.h>
+#include <linux/mutex.h>
+#include <linux/cpu.h>
+
+/*
+ * A cgroup is freezing if any FREEZING flags are set. FREEZING_SELF is
+ * set if "FROZEN" is written to freezer.state cgroupfs file, and cleared
+ * for "THAWED". FREEZING_PARENT is set if the parent freezer is FREEZING
+ * for whatever reason. IOW, a cgroup has FREEZING_PARENT set if one of
+ * its ancestors has FREEZING_SELF set.
+ */
+enum freezer_state_flags {
+ CGROUP_FREEZER_ONLINE = (1 << 0), /* freezer is fully online */
+ CGROUP_FREEZING_SELF = (1 << 1), /* this freezer is freezing */
+ CGROUP_FREEZING_PARENT = (1 << 2), /* the parent freezer is freezing */
+ CGROUP_FROZEN = (1 << 3), /* this and its descendants frozen */
+
+ /* mask for all FREEZING flags */
+ CGROUP_FREEZING = CGROUP_FREEZING_SELF | CGROUP_FREEZING_PARENT,
+};
+
+struct freezer {
+ struct cgroup_subsys_state css;
+ unsigned int state;
+};
+
+static DEFINE_MUTEX(freezer_mutex);
+
+static inline struct freezer *css_freezer(struct cgroup_subsys_state *css)
+{
+ return css ? container_of(css, struct freezer, css) : NULL;
+}
+
+static inline struct freezer *task_freezer(struct task_struct *task)
+{
+ return css_freezer(task_css(task, freezer_cgrp_id));
+}
+
+static struct freezer *parent_freezer(struct freezer *freezer)
+{
+ return css_freezer(freezer->css.parent);
+}
+
+bool cgroup_freezing(struct task_struct *task)
+{
+ bool ret;
+ unsigned int state;
+
+ rcu_read_lock();
+ /* Check if the cgroup is still FREEZING, but not FROZEN. The extra
+ * !FROZEN check is required, because the FREEZING bit is not cleared
+ * when the state FROZEN is reached.
+ */
+ state = task_freezer(task)->state;
+ ret = (state & CGROUP_FREEZING) && !(state & CGROUP_FROZEN);
+ rcu_read_unlock();
+
+ return ret;
+}
+
+static const char *freezer_state_strs(unsigned int state)
+{
+ if (state & CGROUP_FROZEN)
+ return "FROZEN";
+ if (state & CGROUP_FREEZING)
+ return "FREEZING";
+ return "THAWED";
+};
+
+static struct cgroup_subsys_state *
+freezer_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+ struct freezer *freezer;
+
+ freezer = kzalloc(sizeof(struct freezer), GFP_KERNEL);
+ if (!freezer)
+ return ERR_PTR(-ENOMEM);
+
+ return &freezer->css;
+}
+
+/**
+ * freezer_css_online - commit creation of a freezer css
+ * @css: css being created
+ *
+ * We're committing to creation of @css. Mark it online and inherit
+ * parent's freezing state while holding both parent's and our
+ * freezer->lock.
+ */
+static int freezer_css_online(struct cgroup_subsys_state *css)
+{
+ struct freezer *freezer = css_freezer(css);
+ struct freezer *parent = parent_freezer(freezer);
+
+ cpus_read_lock();
+ mutex_lock(&freezer_mutex);
+
+ freezer->state |= CGROUP_FREEZER_ONLINE;
+
+ if (parent && (parent->state & CGROUP_FREEZING)) {
+ freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN;
+ static_branch_inc_cpuslocked(&freezer_active);
+ }
+
+ mutex_unlock(&freezer_mutex);
+ cpus_read_unlock();
+ return 0;
+}
+
+/**
+ * freezer_css_offline - initiate destruction of a freezer css
+ * @css: css being destroyed
+ *
+ * @css is going away. Mark it dead and decrement system_freezing_count if
+ * it was holding one.
+ */
+static void freezer_css_offline(struct cgroup_subsys_state *css)
+{
+ struct freezer *freezer = css_freezer(css);
+
+ cpus_read_lock();
+ mutex_lock(&freezer_mutex);
+
+ if (freezer->state & CGROUP_FREEZING)
+ static_branch_dec_cpuslocked(&freezer_active);
+
+ freezer->state = 0;
+
+ mutex_unlock(&freezer_mutex);
+ cpus_read_unlock();
+}
+
+static void freezer_css_free(struct cgroup_subsys_state *css)
+{
+ kfree(css_freezer(css));
+}
+
+/*
+ * Tasks can be migrated into a different freezer anytime regardless of its
+ * current state. freezer_attach() is responsible for making new tasks
+ * conform to the current state.
+ *
+ * Freezer state changes and task migration are synchronized via
+ * @freezer->lock. freezer_attach() makes the new tasks conform to the
+ * current state and all following state changes can see the new tasks.
+ */
+static void freezer_attach(struct cgroup_taskset *tset)
+{
+ struct task_struct *task;
+ struct cgroup_subsys_state *new_css;
+
+ mutex_lock(&freezer_mutex);
+
+ /*
+ * Make the new tasks conform to the current state of @new_css.
+ * For simplicity, when migrating any task to a FROZEN cgroup, we
+ * revert it to FREEZING and let update_if_frozen() determine the
+ * correct state later.
+ *
+ * Tasks in @tset are on @new_css but may not conform to its
+ * current state before executing the following - !frozen tasks may
+ * be visible in a FROZEN cgroup and frozen tasks in a THAWED one.
+ */
+ cgroup_taskset_for_each(task, new_css, tset) {
+ struct freezer *freezer = css_freezer(new_css);
+
+ if (!(freezer->state & CGROUP_FREEZING)) {
+ __thaw_task(task);
+ } else {
+ freeze_task(task);
+
+ /* clear FROZEN and propagate upwards */
+ while (freezer && (freezer->state & CGROUP_FROZEN)) {
+ freezer->state &= ~CGROUP_FROZEN;
+ freezer = parent_freezer(freezer);
+ }
+ }
+ }
+
+ mutex_unlock(&freezer_mutex);
+}
+
+/**
+ * freezer_fork - cgroup post fork callback
+ * @task: a task which has just been forked
+ *
+ * @task has just been created and should conform to the current state of
+ * the cgroup_freezer it belongs to. This function may race against
+ * freezer_attach(). Losing to freezer_attach() means that we don't have
+ * to do anything as freezer_attach() will put @task into the appropriate
+ * state.
+ */
+static void freezer_fork(struct task_struct *task)
+{
+ struct freezer *freezer;
+
+ /*
+ * The root cgroup is non-freezable, so we can skip locking the
+ * freezer. This is safe regardless of race with task migration.
+ * If we didn't race or won, skipping is obviously the right thing
+ * to do. If we lost and root is the new cgroup, noop is still the
+ * right thing to do.
+ */
+ if (task_css_is_root(task, freezer_cgrp_id))
+ return;
+
+ mutex_lock(&freezer_mutex);
+ rcu_read_lock();
+
+ freezer = task_freezer(task);
+ if (freezer->state & CGROUP_FREEZING)
+ freeze_task(task);
+
+ rcu_read_unlock();
+ mutex_unlock(&freezer_mutex);
+}
+
+/**
+ * update_if_frozen - update whether a cgroup finished freezing
+ * @css: css of interest
+ *
+ * Once FREEZING is initiated, transition to FROZEN is lazily updated by
+ * calling this function. If the current state is FREEZING but not FROZEN,
+ * this function checks whether all tasks of this cgroup and the descendant
+ * cgroups finished freezing and, if so, sets FROZEN.
+ *
+ * The caller is responsible for grabbing RCU read lock and calling
+ * update_if_frozen() on all descendants prior to invoking this function.
+ *
+ * Task states and freezer state might disagree while tasks are being
+ * migrated into or out of @css, so we can't verify task states against
+ * @freezer state here. See freezer_attach() for details.
+ */
+static void update_if_frozen(struct cgroup_subsys_state *css)
+{
+ struct freezer *freezer = css_freezer(css);
+ struct cgroup_subsys_state *pos;
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ lockdep_assert_held(&freezer_mutex);
+
+ if (!(freezer->state & CGROUP_FREEZING) ||
+ (freezer->state & CGROUP_FROZEN))
+ return;
+
+ /* are all (live) children frozen? */
+ rcu_read_lock();
+ css_for_each_child(pos, css) {
+ struct freezer *child = css_freezer(pos);
+
+ if ((child->state & CGROUP_FREEZER_ONLINE) &&
+ !(child->state & CGROUP_FROZEN)) {
+ rcu_read_unlock();
+ return;
+ }
+ }
+ rcu_read_unlock();
+
+ /* are all tasks frozen? */
+ css_task_iter_start(css, 0, &it);
+
+ while ((task = css_task_iter_next(&it))) {
+ if (freezing(task) && !frozen(task))
+ goto out_iter_end;
+ }
+
+ freezer->state |= CGROUP_FROZEN;
+out_iter_end:
+ css_task_iter_end(&it);
+}
+
+static int freezer_read(struct seq_file *m, void *v)
+{
+ struct cgroup_subsys_state *css = seq_css(m), *pos;
+
+ mutex_lock(&freezer_mutex);
+ rcu_read_lock();
+
+ /* update states bottom-up */
+ css_for_each_descendant_post(pos, css) {
+ if (!css_tryget_online(pos))
+ continue;
+ rcu_read_unlock();
+
+ update_if_frozen(pos);
+
+ rcu_read_lock();
+ css_put(pos);
+ }
+
+ rcu_read_unlock();
+ mutex_unlock(&freezer_mutex);
+
+ seq_puts(m, freezer_state_strs(css_freezer(css)->state));
+ seq_putc(m, '\n');
+ return 0;
+}
+
+static void freeze_cgroup(struct freezer *freezer)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ css_task_iter_start(&freezer->css, 0, &it);
+ while ((task = css_task_iter_next(&it)))
+ freeze_task(task);
+ css_task_iter_end(&it);
+}
+
+static void unfreeze_cgroup(struct freezer *freezer)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ css_task_iter_start(&freezer->css, 0, &it);
+ while ((task = css_task_iter_next(&it)))
+ __thaw_task(task);
+ css_task_iter_end(&it);
+}
+
+/**
+ * freezer_apply_state - apply state change to a single cgroup_freezer
+ * @freezer: freezer to apply state change to
+ * @freeze: whether to freeze or unfreeze
+ * @state: CGROUP_FREEZING_* flag to set or clear
+ *
+ * Set or clear @state on @cgroup according to @freeze, and perform
+ * freezing or thawing as necessary.
+ */
+static void freezer_apply_state(struct freezer *freezer, bool freeze,
+ unsigned int state)
+{
+ /* also synchronizes against task migration, see freezer_attach() */
+ lockdep_assert_held(&freezer_mutex);
+
+ if (!(freezer->state & CGROUP_FREEZER_ONLINE))
+ return;
+
+ if (freeze) {
+ if (!(freezer->state & CGROUP_FREEZING))
+ static_branch_inc_cpuslocked(&freezer_active);
+ freezer->state |= state;
+ freeze_cgroup(freezer);
+ } else {
+ bool was_freezing = freezer->state & CGROUP_FREEZING;
+
+ freezer->state &= ~state;
+
+ if (!(freezer->state & CGROUP_FREEZING)) {
+ freezer->state &= ~CGROUP_FROZEN;
+ if (was_freezing)
+ static_branch_dec_cpuslocked(&freezer_active);
+ unfreeze_cgroup(freezer);
+ }
+ }
+}
+
+/**
+ * freezer_change_state - change the freezing state of a cgroup_freezer
+ * @freezer: freezer of interest
+ * @freeze: whether to freeze or thaw
+ *
+ * Freeze or thaw @freezer according to @freeze. The operations are
+ * recursive - all descendants of @freezer will be affected.
+ */
+static void freezer_change_state(struct freezer *freezer, bool freeze)
+{
+ struct cgroup_subsys_state *pos;
+
+ cpus_read_lock();
+ /*
+ * Update all its descendants in pre-order traversal. Each
+ * descendant will try to inherit its parent's FREEZING state as
+ * CGROUP_FREEZING_PARENT.
+ */
+ mutex_lock(&freezer_mutex);
+ rcu_read_lock();
+ css_for_each_descendant_pre(pos, &freezer->css) {
+ struct freezer *pos_f = css_freezer(pos);
+ struct freezer *parent = parent_freezer(pos_f);
+
+ if (!css_tryget_online(pos))
+ continue;
+ rcu_read_unlock();
+
+ if (pos_f == freezer)
+ freezer_apply_state(pos_f, freeze,
+ CGROUP_FREEZING_SELF);
+ else
+ freezer_apply_state(pos_f,
+ parent->state & CGROUP_FREEZING,
+ CGROUP_FREEZING_PARENT);
+
+ rcu_read_lock();
+ css_put(pos);
+ }
+ rcu_read_unlock();
+ mutex_unlock(&freezer_mutex);
+ cpus_read_unlock();
+}
+
+static ssize_t freezer_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ bool freeze;
+
+ buf = strstrip(buf);
+
+ if (strcmp(buf, freezer_state_strs(0)) == 0)
+ freeze = false;
+ else if (strcmp(buf, freezer_state_strs(CGROUP_FROZEN)) == 0)
+ freeze = true;
+ else
+ return -EINVAL;
+
+ freezer_change_state(css_freezer(of_css(of)), freeze);
+ return nbytes;
+}
+
+static u64 freezer_self_freezing_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ struct freezer *freezer = css_freezer(css);
+
+ return (bool)(freezer->state & CGROUP_FREEZING_SELF);
+}
+
+static u64 freezer_parent_freezing_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ struct freezer *freezer = css_freezer(css);
+
+ return (bool)(freezer->state & CGROUP_FREEZING_PARENT);
+}
+
+static struct cftype files[] = {
+ {
+ .name = "state",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = freezer_read,
+ .write = freezer_write,
+ },
+ {
+ .name = "self_freezing",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .read_u64 = freezer_self_freezing_read,
+ },
+ {
+ .name = "parent_freezing",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .read_u64 = freezer_parent_freezing_read,
+ },
+ { } /* terminate */
+};
+
+struct cgroup_subsys freezer_cgrp_subsys = {
+ .css_alloc = freezer_css_alloc,
+ .css_online = freezer_css_online,
+ .css_offline = freezer_css_offline,
+ .css_free = freezer_css_free,
+ .attach = freezer_attach,
+ .fork = freezer_fork,
+ .legacy_cftypes = files,
+};
diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c
new file mode 100644
index 0000000000..79a3717a58
--- /dev/null
+++ b/kernel/cgroup/misc.c
@@ -0,0 +1,422 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Miscellaneous cgroup controller
+ *
+ * Copyright 2020 Google LLC
+ * Author: Vipin Sharma <vipinsh@google.com>
+ */
+
+#include <linux/limits.h>
+#include <linux/cgroup.h>
+#include <linux/errno.h>
+#include <linux/atomic.h>
+#include <linux/slab.h>
+#include <linux/misc_cgroup.h>
+
+#define MAX_STR "max"
+#define MAX_NUM U64_MAX
+
+/* Miscellaneous res name, keep it in sync with enum misc_res_type */
+static const char *const misc_res_name[] = {
+#ifdef CONFIG_KVM_AMD_SEV
+ /* AMD SEV ASIDs resource */
+ "sev",
+ /* AMD SEV-ES ASIDs resource */
+ "sev_es",
+#endif
+};
+
+/* Root misc cgroup */
+static struct misc_cg root_cg;
+
+/*
+ * Miscellaneous resources capacity for the entire machine. 0 capacity means
+ * resource is not initialized or not present in the host.
+ *
+ * root_cg.max and capacity are independent of each other. root_cg.max can be
+ * more than the actual capacity. We are using Limits resource distribution
+ * model of cgroup for miscellaneous controller.
+ */
+static u64 misc_res_capacity[MISC_CG_RES_TYPES];
+
+/**
+ * parent_misc() - Get the parent of the passed misc cgroup.
+ * @cgroup: cgroup whose parent needs to be fetched.
+ *
+ * Context: Any context.
+ * Return:
+ * * struct misc_cg* - Parent of the @cgroup.
+ * * %NULL - If @cgroup is null or the passed cgroup does not have a parent.
+ */
+static struct misc_cg *parent_misc(struct misc_cg *cgroup)
+{
+ return cgroup ? css_misc(cgroup->css.parent) : NULL;
+}
+
+/**
+ * valid_type() - Check if @type is valid or not.
+ * @type: misc res type.
+ *
+ * Context: Any context.
+ * Return:
+ * * true - If valid type.
+ * * false - If not valid type.
+ */
+static inline bool valid_type(enum misc_res_type type)
+{
+ return type >= 0 && type < MISC_CG_RES_TYPES;
+}
+
+/**
+ * misc_cg_res_total_usage() - Get the current total usage of the resource.
+ * @type: misc res type.
+ *
+ * Context: Any context.
+ * Return: Current total usage of the resource.
+ */
+u64 misc_cg_res_total_usage(enum misc_res_type type)
+{
+ if (valid_type(type))
+ return atomic64_read(&root_cg.res[type].usage);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(misc_cg_res_total_usage);
+
+/**
+ * misc_cg_set_capacity() - Set the capacity of the misc cgroup res.
+ * @type: Type of the misc res.
+ * @capacity: Supported capacity of the misc res on the host.
+ *
+ * If capacity is 0 then the charging a misc cgroup fails for that type.
+ *
+ * Context: Any context.
+ * Return:
+ * * %0 - Successfully registered the capacity.
+ * * %-EINVAL - If @type is invalid.
+ */
+int misc_cg_set_capacity(enum misc_res_type type, u64 capacity)
+{
+ if (!valid_type(type))
+ return -EINVAL;
+
+ WRITE_ONCE(misc_res_capacity[type], capacity);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(misc_cg_set_capacity);
+
+/**
+ * misc_cg_cancel_charge() - Cancel the charge from the misc cgroup.
+ * @type: Misc res type in misc cg to cancel the charge from.
+ * @cg: Misc cgroup to cancel charge from.
+ * @amount: Amount to cancel.
+ *
+ * Context: Any context.
+ */
+static void misc_cg_cancel_charge(enum misc_res_type type, struct misc_cg *cg,
+ u64 amount)
+{
+ WARN_ONCE(atomic64_add_negative(-amount, &cg->res[type].usage),
+ "misc cgroup resource %s became less than 0",
+ misc_res_name[type]);
+}
+
+/**
+ * misc_cg_try_charge() - Try charging the misc cgroup.
+ * @type: Misc res type to charge.
+ * @cg: Misc cgroup which will be charged.
+ * @amount: Amount to charge.
+ *
+ * Charge @amount to the misc cgroup. Caller must use the same cgroup during
+ * the uncharge call.
+ *
+ * Context: Any context.
+ * Return:
+ * * %0 - If successfully charged.
+ * * -EINVAL - If @type is invalid or misc res has 0 capacity.
+ * * -EBUSY - If max limit will be crossed or total usage will be more than the
+ * capacity.
+ */
+int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg, u64 amount)
+{
+ struct misc_cg *i, *j;
+ int ret;
+ struct misc_res *res;
+ u64 new_usage;
+
+ if (!(valid_type(type) && cg && READ_ONCE(misc_res_capacity[type])))
+ return -EINVAL;
+
+ if (!amount)
+ return 0;
+
+ for (i = cg; i; i = parent_misc(i)) {
+ res = &i->res[type];
+
+ new_usage = atomic64_add_return(amount, &res->usage);
+ if (new_usage > READ_ONCE(res->max) ||
+ new_usage > READ_ONCE(misc_res_capacity[type])) {
+ ret = -EBUSY;
+ goto err_charge;
+ }
+ }
+ return 0;
+
+err_charge:
+ for (j = i; j; j = parent_misc(j)) {
+ atomic64_inc(&j->res[type].events);
+ cgroup_file_notify(&j->events_file);
+ }
+
+ for (j = cg; j != i; j = parent_misc(j))
+ misc_cg_cancel_charge(type, j, amount);
+ misc_cg_cancel_charge(type, i, amount);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(misc_cg_try_charge);
+
+/**
+ * misc_cg_uncharge() - Uncharge the misc cgroup.
+ * @type: Misc res type which was charged.
+ * @cg: Misc cgroup which will be uncharged.
+ * @amount: Charged amount.
+ *
+ * Context: Any context.
+ */
+void misc_cg_uncharge(enum misc_res_type type, struct misc_cg *cg, u64 amount)
+{
+ struct misc_cg *i;
+
+ if (!(amount && valid_type(type) && cg))
+ return;
+
+ for (i = cg; i; i = parent_misc(i))
+ misc_cg_cancel_charge(type, i, amount);
+}
+EXPORT_SYMBOL_GPL(misc_cg_uncharge);
+
+/**
+ * misc_cg_max_show() - Show the misc cgroup max limit.
+ * @sf: Interface file
+ * @v: Arguments passed
+ *
+ * Context: Any context.
+ * Return: 0 to denote successful print.
+ */
+static int misc_cg_max_show(struct seq_file *sf, void *v)
+{
+ int i;
+ struct misc_cg *cg = css_misc(seq_css(sf));
+ u64 max;
+
+ for (i = 0; i < MISC_CG_RES_TYPES; i++) {
+ if (READ_ONCE(misc_res_capacity[i])) {
+ max = READ_ONCE(cg->res[i].max);
+ if (max == MAX_NUM)
+ seq_printf(sf, "%s max\n", misc_res_name[i]);
+ else
+ seq_printf(sf, "%s %llu\n", misc_res_name[i],
+ max);
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * misc_cg_max_write() - Update the maximum limit of the cgroup.
+ * @of: Handler for the file.
+ * @buf: Data from the user. It should be either "max", 0, or a positive
+ * integer.
+ * @nbytes: Number of bytes of the data.
+ * @off: Offset in the file.
+ *
+ * User can pass data like:
+ * echo sev 23 > misc.max, OR
+ * echo sev max > misc.max
+ *
+ * Context: Any context.
+ * Return:
+ * * >= 0 - Number of bytes processed in the input.
+ * * -EINVAL - If buf is not valid.
+ * * -ERANGE - If number is bigger than the u64 capacity.
+ */
+static ssize_t misc_cg_max_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct misc_cg *cg;
+ u64 max;
+ int ret = 0, i;
+ enum misc_res_type type = MISC_CG_RES_TYPES;
+ char *token;
+
+ buf = strstrip(buf);
+ token = strsep(&buf, " ");
+
+ if (!token || !buf)
+ return -EINVAL;
+
+ for (i = 0; i < MISC_CG_RES_TYPES; i++) {
+ if (!strcmp(misc_res_name[i], token)) {
+ type = i;
+ break;
+ }
+ }
+
+ if (type == MISC_CG_RES_TYPES)
+ return -EINVAL;
+
+ if (!strcmp(MAX_STR, buf)) {
+ max = MAX_NUM;
+ } else {
+ ret = kstrtou64(buf, 0, &max);
+ if (ret)
+ return ret;
+ }
+
+ cg = css_misc(of_css(of));
+
+ if (READ_ONCE(misc_res_capacity[type]))
+ WRITE_ONCE(cg->res[type].max, max);
+ else
+ ret = -EINVAL;
+
+ return ret ? ret : nbytes;
+}
+
+/**
+ * misc_cg_current_show() - Show the current usage of the misc cgroup.
+ * @sf: Interface file
+ * @v: Arguments passed
+ *
+ * Context: Any context.
+ * Return: 0 to denote successful print.
+ */
+static int misc_cg_current_show(struct seq_file *sf, void *v)
+{
+ int i;
+ u64 usage;
+ struct misc_cg *cg = css_misc(seq_css(sf));
+
+ for (i = 0; i < MISC_CG_RES_TYPES; i++) {
+ usage = atomic64_read(&cg->res[i].usage);
+ if (READ_ONCE(misc_res_capacity[i]) || usage)
+ seq_printf(sf, "%s %llu\n", misc_res_name[i], usage);
+ }
+
+ return 0;
+}
+
+/**
+ * misc_cg_capacity_show() - Show the total capacity of misc res on the host.
+ * @sf: Interface file
+ * @v: Arguments passed
+ *
+ * Only present in the root cgroup directory.
+ *
+ * Context: Any context.
+ * Return: 0 to denote successful print.
+ */
+static int misc_cg_capacity_show(struct seq_file *sf, void *v)
+{
+ int i;
+ u64 cap;
+
+ for (i = 0; i < MISC_CG_RES_TYPES; i++) {
+ cap = READ_ONCE(misc_res_capacity[i]);
+ if (cap)
+ seq_printf(sf, "%s %llu\n", misc_res_name[i], cap);
+ }
+
+ return 0;
+}
+
+static int misc_events_show(struct seq_file *sf, void *v)
+{
+ struct misc_cg *cg = css_misc(seq_css(sf));
+ u64 events;
+ int i;
+
+ for (i = 0; i < MISC_CG_RES_TYPES; i++) {
+ events = atomic64_read(&cg->res[i].events);
+ if (READ_ONCE(misc_res_capacity[i]) || events)
+ seq_printf(sf, "%s.max %llu\n", misc_res_name[i], events);
+ }
+ return 0;
+}
+
+/* Misc cgroup interface files */
+static struct cftype misc_cg_files[] = {
+ {
+ .name = "max",
+ .write = misc_cg_max_write,
+ .seq_show = misc_cg_max_show,
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+ {
+ .name = "current",
+ .seq_show = misc_cg_current_show,
+ },
+ {
+ .name = "capacity",
+ .seq_show = misc_cg_capacity_show,
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ },
+ {
+ .name = "events",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .file_offset = offsetof(struct misc_cg, events_file),
+ .seq_show = misc_events_show,
+ },
+ {}
+};
+
+/**
+ * misc_cg_alloc() - Allocate misc cgroup.
+ * @parent_css: Parent cgroup.
+ *
+ * Context: Process context.
+ * Return:
+ * * struct cgroup_subsys_state* - css of the allocated cgroup.
+ * * ERR_PTR(-ENOMEM) - No memory available to allocate.
+ */
+static struct cgroup_subsys_state *
+misc_cg_alloc(struct cgroup_subsys_state *parent_css)
+{
+ enum misc_res_type i;
+ struct misc_cg *cg;
+
+ if (!parent_css) {
+ cg = &root_cg;
+ } else {
+ cg = kzalloc(sizeof(*cg), GFP_KERNEL);
+ if (!cg)
+ return ERR_PTR(-ENOMEM);
+ }
+
+ for (i = 0; i < MISC_CG_RES_TYPES; i++) {
+ WRITE_ONCE(cg->res[i].max, MAX_NUM);
+ atomic64_set(&cg->res[i].usage, 0);
+ }
+
+ return &cg->css;
+}
+
+/**
+ * misc_cg_free() - Free the misc cgroup.
+ * @css: cgroup subsys object.
+ *
+ * Context: Any context.
+ */
+static void misc_cg_free(struct cgroup_subsys_state *css)
+{
+ kfree(css_misc(css));
+}
+
+/* Cgroup controller callbacks */
+struct cgroup_subsys misc_cgrp_subsys = {
+ .css_alloc = misc_cg_alloc,
+ .css_free = misc_cg_free,
+ .legacy_cftypes = misc_cg_files,
+ .dfl_cftypes = misc_cg_files,
+};
diff --git a/kernel/cgroup/namespace.c b/kernel/cgroup/namespace.c
new file mode 100644
index 0000000000..144a464e45
--- /dev/null
+++ b/kernel/cgroup/namespace.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "cgroup-internal.h"
+
+#include <linux/sched/task.h>
+#include <linux/slab.h>
+#include <linux/nsproxy.h>
+#include <linux/proc_ns.h>
+
+
+/* cgroup namespaces */
+
+static struct ucounts *inc_cgroup_namespaces(struct user_namespace *ns)
+{
+ return inc_ucount(ns, current_euid(), UCOUNT_CGROUP_NAMESPACES);
+}
+
+static void dec_cgroup_namespaces(struct ucounts *ucounts)
+{
+ dec_ucount(ucounts, UCOUNT_CGROUP_NAMESPACES);
+}
+
+static struct cgroup_namespace *alloc_cgroup_ns(void)
+{
+ struct cgroup_namespace *new_ns;
+ int ret;
+
+ new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL_ACCOUNT);
+ if (!new_ns)
+ return ERR_PTR(-ENOMEM);
+ ret = ns_alloc_inum(&new_ns->ns);
+ if (ret) {
+ kfree(new_ns);
+ return ERR_PTR(ret);
+ }
+ refcount_set(&new_ns->ns.count, 1);
+ new_ns->ns.ops = &cgroupns_operations;
+ return new_ns;
+}
+
+void free_cgroup_ns(struct cgroup_namespace *ns)
+{
+ put_css_set(ns->root_cset);
+ dec_cgroup_namespaces(ns->ucounts);
+ put_user_ns(ns->user_ns);
+ ns_free_inum(&ns->ns);
+ kfree(ns);
+}
+EXPORT_SYMBOL(free_cgroup_ns);
+
+struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
+ struct user_namespace *user_ns,
+ struct cgroup_namespace *old_ns)
+{
+ struct cgroup_namespace *new_ns;
+ struct ucounts *ucounts;
+ struct css_set *cset;
+
+ BUG_ON(!old_ns);
+
+ if (!(flags & CLONE_NEWCGROUP)) {
+ get_cgroup_ns(old_ns);
+ return old_ns;
+ }
+
+ /* Allow only sysadmin to create cgroup namespace. */
+ if (!ns_capable(user_ns, CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+
+ ucounts = inc_cgroup_namespaces(user_ns);
+ if (!ucounts)
+ return ERR_PTR(-ENOSPC);
+
+ /* It is not safe to take cgroup_mutex here */
+ spin_lock_irq(&css_set_lock);
+ cset = task_css_set(current);
+ get_css_set(cset);
+ spin_unlock_irq(&css_set_lock);
+
+ new_ns = alloc_cgroup_ns();
+ if (IS_ERR(new_ns)) {
+ put_css_set(cset);
+ dec_cgroup_namespaces(ucounts);
+ return new_ns;
+ }
+
+ new_ns->user_ns = get_user_ns(user_ns);
+ new_ns->ucounts = ucounts;
+ new_ns->root_cset = cset;
+
+ return new_ns;
+}
+
+static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
+{
+ return container_of(ns, struct cgroup_namespace, ns);
+}
+
+static int cgroupns_install(struct nsset *nsset, struct ns_common *ns)
+{
+ struct nsproxy *nsproxy = nsset->nsproxy;
+ struct cgroup_namespace *cgroup_ns = to_cg_ns(ns);
+
+ if (!ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN) ||
+ !ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ /* Don't need to do anything if we are attaching to our own cgroupns. */
+ if (cgroup_ns == nsproxy->cgroup_ns)
+ return 0;
+
+ get_cgroup_ns(cgroup_ns);
+ put_cgroup_ns(nsproxy->cgroup_ns);
+ nsproxy->cgroup_ns = cgroup_ns;
+
+ return 0;
+}
+
+static struct ns_common *cgroupns_get(struct task_struct *task)
+{
+ struct cgroup_namespace *ns = NULL;
+ struct nsproxy *nsproxy;
+
+ task_lock(task);
+ nsproxy = task->nsproxy;
+ if (nsproxy) {
+ ns = nsproxy->cgroup_ns;
+ get_cgroup_ns(ns);
+ }
+ task_unlock(task);
+
+ return ns ? &ns->ns : NULL;
+}
+
+static void cgroupns_put(struct ns_common *ns)
+{
+ put_cgroup_ns(to_cg_ns(ns));
+}
+
+static struct user_namespace *cgroupns_owner(struct ns_common *ns)
+{
+ return to_cg_ns(ns)->user_ns;
+}
+
+const struct proc_ns_operations cgroupns_operations = {
+ .name = "cgroup",
+ .type = CLONE_NEWCGROUP,
+ .get = cgroupns_get,
+ .put = cgroupns_put,
+ .install = cgroupns_install,
+ .owner = cgroupns_owner,
+};
diff --git a/kernel/cgroup/pids.c b/kernel/cgroup/pids.c
new file mode 100644
index 0000000000..7695e60bcb
--- /dev/null
+++ b/kernel/cgroup/pids.c
@@ -0,0 +1,387 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Process number limiting controller for cgroups.
+ *
+ * Used to allow a cgroup hierarchy to stop any new processes from fork()ing
+ * after a certain limit is reached.
+ *
+ * Since it is trivial to hit the task limit without hitting any kmemcg limits
+ * in place, PIDs are a fundamental resource. As such, PID exhaustion must be
+ * preventable in the scope of a cgroup hierarchy by allowing resource limiting
+ * of the number of tasks in a cgroup.
+ *
+ * In order to use the `pids` controller, set the maximum number of tasks in
+ * pids.max (this is not available in the root cgroup for obvious reasons). The
+ * number of processes currently in the cgroup is given by pids.current.
+ * Organisational operations are not blocked by cgroup policies, so it is
+ * possible to have pids.current > pids.max. However, it is not possible to
+ * violate a cgroup policy through fork(). fork() will return -EAGAIN if forking
+ * would cause a cgroup policy to be violated.
+ *
+ * To set a cgroup to have no limit, set pids.max to "max". This is the default
+ * for all new cgroups (N.B. that PID limits are hierarchical, so the most
+ * stringent limit in the hierarchy is followed).
+ *
+ * pids.current tracks all child cgroup hierarchies, so parent/pids.current is
+ * a superset of parent/child/pids.current.
+ *
+ * Copyright (C) 2015 Aleksa Sarai <cyphar@cyphar.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/threads.h>
+#include <linux/atomic.h>
+#include <linux/cgroup.h>
+#include <linux/slab.h>
+#include <linux/sched/task.h>
+
+#define PIDS_MAX (PID_MAX_LIMIT + 1ULL)
+#define PIDS_MAX_STR "max"
+
+struct pids_cgroup {
+ struct cgroup_subsys_state css;
+
+ /*
+ * Use 64-bit types so that we can safely represent "max" as
+ * %PIDS_MAX = (%PID_MAX_LIMIT + 1).
+ */
+ atomic64_t counter;
+ atomic64_t limit;
+ int64_t watermark;
+
+ /* Handle for "pids.events" */
+ struct cgroup_file events_file;
+
+ /* Number of times fork failed because limit was hit. */
+ atomic64_t events_limit;
+};
+
+static struct pids_cgroup *css_pids(struct cgroup_subsys_state *css)
+{
+ return container_of(css, struct pids_cgroup, css);
+}
+
+static struct pids_cgroup *parent_pids(struct pids_cgroup *pids)
+{
+ return css_pids(pids->css.parent);
+}
+
+static struct cgroup_subsys_state *
+pids_css_alloc(struct cgroup_subsys_state *parent)
+{
+ struct pids_cgroup *pids;
+
+ pids = kzalloc(sizeof(struct pids_cgroup), GFP_KERNEL);
+ if (!pids)
+ return ERR_PTR(-ENOMEM);
+
+ atomic64_set(&pids->counter, 0);
+ atomic64_set(&pids->limit, PIDS_MAX);
+ atomic64_set(&pids->events_limit, 0);
+ return &pids->css;
+}
+
+static void pids_css_free(struct cgroup_subsys_state *css)
+{
+ kfree(css_pids(css));
+}
+
+static void pids_update_watermark(struct pids_cgroup *p, int64_t nr_pids)
+{
+ /*
+ * This is racy, but we don't need perfectly accurate tallying of
+ * the watermark, and this lets us avoid extra atomic overhead.
+ */
+ if (nr_pids > READ_ONCE(p->watermark))
+ WRITE_ONCE(p->watermark, nr_pids);
+}
+
+/**
+ * pids_cancel - uncharge the local pid count
+ * @pids: the pid cgroup state
+ * @num: the number of pids to cancel
+ *
+ * This function will WARN if the pid count goes under 0, because such a case is
+ * a bug in the pids controller proper.
+ */
+static void pids_cancel(struct pids_cgroup *pids, int num)
+{
+ /*
+ * A negative count (or overflow for that matter) is invalid,
+ * and indicates a bug in the `pids` controller proper.
+ */
+ WARN_ON_ONCE(atomic64_add_negative(-num, &pids->counter));
+}
+
+/**
+ * pids_uncharge - hierarchically uncharge the pid count
+ * @pids: the pid cgroup state
+ * @num: the number of pids to uncharge
+ */
+static void pids_uncharge(struct pids_cgroup *pids, int num)
+{
+ struct pids_cgroup *p;
+
+ for (p = pids; parent_pids(p); p = parent_pids(p))
+ pids_cancel(p, num);
+}
+
+/**
+ * pids_charge - hierarchically charge the pid count
+ * @pids: the pid cgroup state
+ * @num: the number of pids to charge
+ *
+ * This function does *not* follow the pid limit set. It cannot fail and the new
+ * pid count may exceed the limit. This is only used for reverting failed
+ * attaches, where there is no other way out than violating the limit.
+ */
+static void pids_charge(struct pids_cgroup *pids, int num)
+{
+ struct pids_cgroup *p;
+
+ for (p = pids; parent_pids(p); p = parent_pids(p)) {
+ int64_t new = atomic64_add_return(num, &p->counter);
+
+ pids_update_watermark(p, new);
+ }
+}
+
+/**
+ * pids_try_charge - hierarchically try to charge the pid count
+ * @pids: the pid cgroup state
+ * @num: the number of pids to charge
+ *
+ * This function follows the set limit. It will fail if the charge would cause
+ * the new value to exceed the hierarchical limit. Returns 0 if the charge
+ * succeeded, otherwise -EAGAIN.
+ */
+static int pids_try_charge(struct pids_cgroup *pids, int num)
+{
+ struct pids_cgroup *p, *q;
+
+ for (p = pids; parent_pids(p); p = parent_pids(p)) {
+ int64_t new = atomic64_add_return(num, &p->counter);
+ int64_t limit = atomic64_read(&p->limit);
+
+ /*
+ * Since new is capped to the maximum number of pid_t, if
+ * p->limit is %PIDS_MAX then we know that this test will never
+ * fail.
+ */
+ if (new > limit)
+ goto revert;
+
+ /*
+ * Not technically accurate if we go over limit somewhere up
+ * the hierarchy, but that's tolerable for the watermark.
+ */
+ pids_update_watermark(p, new);
+ }
+
+ return 0;
+
+revert:
+ for (q = pids; q != p; q = parent_pids(q))
+ pids_cancel(q, num);
+ pids_cancel(p, num);
+
+ return -EAGAIN;
+}
+
+static int pids_can_attach(struct cgroup_taskset *tset)
+{
+ struct task_struct *task;
+ struct cgroup_subsys_state *dst_css;
+
+ cgroup_taskset_for_each(task, dst_css, tset) {
+ struct pids_cgroup *pids = css_pids(dst_css);
+ struct cgroup_subsys_state *old_css;
+ struct pids_cgroup *old_pids;
+
+ /*
+ * No need to pin @old_css between here and cancel_attach()
+ * because cgroup core protects it from being freed before
+ * the migration completes or fails.
+ */
+ old_css = task_css(task, pids_cgrp_id);
+ old_pids = css_pids(old_css);
+
+ pids_charge(pids, 1);
+ pids_uncharge(old_pids, 1);
+ }
+
+ return 0;
+}
+
+static void pids_cancel_attach(struct cgroup_taskset *tset)
+{
+ struct task_struct *task;
+ struct cgroup_subsys_state *dst_css;
+
+ cgroup_taskset_for_each(task, dst_css, tset) {
+ struct pids_cgroup *pids = css_pids(dst_css);
+ struct cgroup_subsys_state *old_css;
+ struct pids_cgroup *old_pids;
+
+ old_css = task_css(task, pids_cgrp_id);
+ old_pids = css_pids(old_css);
+
+ pids_charge(old_pids, 1);
+ pids_uncharge(pids, 1);
+ }
+}
+
+/*
+ * task_css_check(true) in pids_can_fork() and pids_cancel_fork() relies
+ * on cgroup_threadgroup_change_begin() held by the copy_process().
+ */
+static int pids_can_fork(struct task_struct *task, struct css_set *cset)
+{
+ struct cgroup_subsys_state *css;
+ struct pids_cgroup *pids;
+ int err;
+
+ if (cset)
+ css = cset->subsys[pids_cgrp_id];
+ else
+ css = task_css_check(current, pids_cgrp_id, true);
+ pids = css_pids(css);
+ err = pids_try_charge(pids, 1);
+ if (err) {
+ /* Only log the first time events_limit is incremented. */
+ if (atomic64_inc_return(&pids->events_limit) == 1) {
+ pr_info("cgroup: fork rejected by pids controller in ");
+ pr_cont_cgroup_path(css->cgroup);
+ pr_cont("\n");
+ }
+ cgroup_file_notify(&pids->events_file);
+ }
+ return err;
+}
+
+static void pids_cancel_fork(struct task_struct *task, struct css_set *cset)
+{
+ struct cgroup_subsys_state *css;
+ struct pids_cgroup *pids;
+
+ if (cset)
+ css = cset->subsys[pids_cgrp_id];
+ else
+ css = task_css_check(current, pids_cgrp_id, true);
+ pids = css_pids(css);
+ pids_uncharge(pids, 1);
+}
+
+static void pids_release(struct task_struct *task)
+{
+ struct pids_cgroup *pids = css_pids(task_css(task, pids_cgrp_id));
+
+ pids_uncharge(pids, 1);
+}
+
+static ssize_t pids_max_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct cgroup_subsys_state *css = of_css(of);
+ struct pids_cgroup *pids = css_pids(css);
+ int64_t limit;
+ int err;
+
+ buf = strstrip(buf);
+ if (!strcmp(buf, PIDS_MAX_STR)) {
+ limit = PIDS_MAX;
+ goto set_limit;
+ }
+
+ err = kstrtoll(buf, 0, &limit);
+ if (err)
+ return err;
+
+ if (limit < 0 || limit >= PIDS_MAX)
+ return -EINVAL;
+
+set_limit:
+ /*
+ * Limit updates don't need to be mutex'd, since it isn't
+ * critical that any racing fork()s follow the new limit.
+ */
+ atomic64_set(&pids->limit, limit);
+ return nbytes;
+}
+
+static int pids_max_show(struct seq_file *sf, void *v)
+{
+ struct cgroup_subsys_state *css = seq_css(sf);
+ struct pids_cgroup *pids = css_pids(css);
+ int64_t limit = atomic64_read(&pids->limit);
+
+ if (limit >= PIDS_MAX)
+ seq_printf(sf, "%s\n", PIDS_MAX_STR);
+ else
+ seq_printf(sf, "%lld\n", limit);
+
+ return 0;
+}
+
+static s64 pids_current_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ struct pids_cgroup *pids = css_pids(css);
+
+ return atomic64_read(&pids->counter);
+}
+
+static s64 pids_peak_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ struct pids_cgroup *pids = css_pids(css);
+
+ return READ_ONCE(pids->watermark);
+}
+
+static int pids_events_show(struct seq_file *sf, void *v)
+{
+ struct pids_cgroup *pids = css_pids(seq_css(sf));
+
+ seq_printf(sf, "max %lld\n", (s64)atomic64_read(&pids->events_limit));
+ return 0;
+}
+
+static struct cftype pids_files[] = {
+ {
+ .name = "max",
+ .write = pids_max_write,
+ .seq_show = pids_max_show,
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+ {
+ .name = "current",
+ .read_s64 = pids_current_read,
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+ {
+ .name = "peak",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .read_s64 = pids_peak_read,
+ },
+ {
+ .name = "events",
+ .seq_show = pids_events_show,
+ .file_offset = offsetof(struct pids_cgroup, events_file),
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+ { } /* terminate */
+};
+
+struct cgroup_subsys pids_cgrp_subsys = {
+ .css_alloc = pids_css_alloc,
+ .css_free = pids_css_free,
+ .can_attach = pids_can_attach,
+ .cancel_attach = pids_cancel_attach,
+ .can_fork = pids_can_fork,
+ .cancel_fork = pids_cancel_fork,
+ .release = pids_release,
+ .legacy_cftypes = pids_files,
+ .dfl_cftypes = pids_files,
+ .threaded = true,
+};
diff --git a/kernel/cgroup/rdma.c b/kernel/cgroup/rdma.c
new file mode 100644
index 0000000000..ef5878fb20
--- /dev/null
+++ b/kernel/cgroup/rdma.c
@@ -0,0 +1,612 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * RDMA resource limiting controller for cgroups.
+ *
+ * Used to allow a cgroup hierarchy to stop processes from consuming
+ * additional RDMA resources after a certain limit is reached.
+ *
+ * Copyright (C) 2016 Parav Pandit <pandit.parav@gmail.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <linux/cgroup.h>
+#include <linux/parser.h>
+#include <linux/cgroup_rdma.h>
+
+#define RDMACG_MAX_STR "max"
+
+/*
+ * Protects list of resource pools maintained on per cgroup basis
+ * and rdma device list.
+ */
+static DEFINE_MUTEX(rdmacg_mutex);
+static LIST_HEAD(rdmacg_devices);
+
+enum rdmacg_file_type {
+ RDMACG_RESOURCE_TYPE_MAX,
+ RDMACG_RESOURCE_TYPE_STAT,
+};
+
+/*
+ * resource table definition as to be seen by the user.
+ * Need to add entries to it when more resources are
+ * added/defined at IB verb/core layer.
+ */
+static char const *rdmacg_resource_names[] = {
+ [RDMACG_RESOURCE_HCA_HANDLE] = "hca_handle",
+ [RDMACG_RESOURCE_HCA_OBJECT] = "hca_object",
+};
+
+/* resource tracker for each resource of rdma cgroup */
+struct rdmacg_resource {
+ int max;
+ int usage;
+};
+
+/*
+ * resource pool object which represents per cgroup, per device
+ * resources. There are multiple instances of this object per cgroup,
+ * therefore it cannot be embedded within rdma_cgroup structure. It
+ * is maintained as list.
+ */
+struct rdmacg_resource_pool {
+ struct rdmacg_device *device;
+ struct rdmacg_resource resources[RDMACG_RESOURCE_MAX];
+
+ struct list_head cg_node;
+ struct list_head dev_node;
+
+ /* count active user tasks of this pool */
+ u64 usage_sum;
+ /* total number counts which are set to max */
+ int num_max_cnt;
+};
+
+static struct rdma_cgroup *css_rdmacg(struct cgroup_subsys_state *css)
+{
+ return container_of(css, struct rdma_cgroup, css);
+}
+
+static struct rdma_cgroup *parent_rdmacg(struct rdma_cgroup *cg)
+{
+ return css_rdmacg(cg->css.parent);
+}
+
+static inline struct rdma_cgroup *get_current_rdmacg(void)
+{
+ return css_rdmacg(task_get_css(current, rdma_cgrp_id));
+}
+
+static void set_resource_limit(struct rdmacg_resource_pool *rpool,
+ int index, int new_max)
+{
+ if (new_max == S32_MAX) {
+ if (rpool->resources[index].max != S32_MAX)
+ rpool->num_max_cnt++;
+ } else {
+ if (rpool->resources[index].max == S32_MAX)
+ rpool->num_max_cnt--;
+ }
+ rpool->resources[index].max = new_max;
+}
+
+static void set_all_resource_max_limit(struct rdmacg_resource_pool *rpool)
+{
+ int i;
+
+ for (i = 0; i < RDMACG_RESOURCE_MAX; i++)
+ set_resource_limit(rpool, i, S32_MAX);
+}
+
+static void free_cg_rpool_locked(struct rdmacg_resource_pool *rpool)
+{
+ lockdep_assert_held(&rdmacg_mutex);
+
+ list_del(&rpool->cg_node);
+ list_del(&rpool->dev_node);
+ kfree(rpool);
+}
+
+static struct rdmacg_resource_pool *
+find_cg_rpool_locked(struct rdma_cgroup *cg,
+ struct rdmacg_device *device)
+
+{
+ struct rdmacg_resource_pool *pool;
+
+ lockdep_assert_held(&rdmacg_mutex);
+
+ list_for_each_entry(pool, &cg->rpools, cg_node)
+ if (pool->device == device)
+ return pool;
+
+ return NULL;
+}
+
+static struct rdmacg_resource_pool *
+get_cg_rpool_locked(struct rdma_cgroup *cg, struct rdmacg_device *device)
+{
+ struct rdmacg_resource_pool *rpool;
+
+ rpool = find_cg_rpool_locked(cg, device);
+ if (rpool)
+ return rpool;
+
+ rpool = kzalloc(sizeof(*rpool), GFP_KERNEL);
+ if (!rpool)
+ return ERR_PTR(-ENOMEM);
+
+ rpool->device = device;
+ set_all_resource_max_limit(rpool);
+
+ INIT_LIST_HEAD(&rpool->cg_node);
+ INIT_LIST_HEAD(&rpool->dev_node);
+ list_add_tail(&rpool->cg_node, &cg->rpools);
+ list_add_tail(&rpool->dev_node, &device->rpools);
+ return rpool;
+}
+
+/**
+ * uncharge_cg_locked - uncharge resource for rdma cgroup
+ * @cg: pointer to cg to uncharge and all parents in hierarchy
+ * @device: pointer to rdmacg device
+ * @index: index of the resource to uncharge in cg (resource pool)
+ *
+ * It also frees the resource pool which was created as part of
+ * charging operation when there are no resources attached to
+ * resource pool.
+ */
+static void
+uncharge_cg_locked(struct rdma_cgroup *cg,
+ struct rdmacg_device *device,
+ enum rdmacg_resource_type index)
+{
+ struct rdmacg_resource_pool *rpool;
+
+ rpool = find_cg_rpool_locked(cg, device);
+
+ /*
+ * rpool cannot be null at this stage. Let kernel operate in case
+ * if there a bug in IB stack or rdma controller, instead of crashing
+ * the system.
+ */
+ if (unlikely(!rpool)) {
+ pr_warn("Invalid device %p or rdma cgroup %p\n", cg, device);
+ return;
+ }
+
+ rpool->resources[index].usage--;
+
+ /*
+ * A negative count (or overflow) is invalid,
+ * it indicates a bug in the rdma controller.
+ */
+ WARN_ON_ONCE(rpool->resources[index].usage < 0);
+ rpool->usage_sum--;
+ if (rpool->usage_sum == 0 &&
+ rpool->num_max_cnt == RDMACG_RESOURCE_MAX) {
+ /*
+ * No user of the rpool and all entries are set to max, so
+ * safe to delete this rpool.
+ */
+ free_cg_rpool_locked(rpool);
+ }
+}
+
+/**
+ * rdmacg_uncharge_hierarchy - hierarchically uncharge rdma resource count
+ * @cg: pointer to cg to uncharge and all parents in hierarchy
+ * @device: pointer to rdmacg device
+ * @stop_cg: while traversing hirerchy, when meet with stop_cg cgroup
+ * stop uncharging
+ * @index: index of the resource to uncharge in cg in given resource pool
+ */
+static void rdmacg_uncharge_hierarchy(struct rdma_cgroup *cg,
+ struct rdmacg_device *device,
+ struct rdma_cgroup *stop_cg,
+ enum rdmacg_resource_type index)
+{
+ struct rdma_cgroup *p;
+
+ mutex_lock(&rdmacg_mutex);
+
+ for (p = cg; p != stop_cg; p = parent_rdmacg(p))
+ uncharge_cg_locked(p, device, index);
+
+ mutex_unlock(&rdmacg_mutex);
+
+ css_put(&cg->css);
+}
+
+/**
+ * rdmacg_uncharge - hierarchically uncharge rdma resource count
+ * @cg: pointer to cg to uncharge and all parents in hierarchy
+ * @device: pointer to rdmacg device
+ * @index: index of the resource to uncharge in cgroup in given resource pool
+ */
+void rdmacg_uncharge(struct rdma_cgroup *cg,
+ struct rdmacg_device *device,
+ enum rdmacg_resource_type index)
+{
+ if (index >= RDMACG_RESOURCE_MAX)
+ return;
+
+ rdmacg_uncharge_hierarchy(cg, device, NULL, index);
+}
+EXPORT_SYMBOL(rdmacg_uncharge);
+
+/**
+ * rdmacg_try_charge - hierarchically try to charge the rdma resource
+ * @rdmacg: pointer to rdma cgroup which will own this resource
+ * @device: pointer to rdmacg device
+ * @index: index of the resource to charge in cgroup (resource pool)
+ *
+ * This function follows charging resource in hierarchical way.
+ * It will fail if the charge would cause the new value to exceed the
+ * hierarchical limit.
+ * Returns 0 if the charge succeeded, otherwise -EAGAIN, -ENOMEM or -EINVAL.
+ * Returns pointer to rdmacg for this resource when charging is successful.
+ *
+ * Charger needs to account resources on two criteria.
+ * (a) per cgroup & (b) per device resource usage.
+ * Per cgroup resource usage ensures that tasks of cgroup doesn't cross
+ * the configured limits. Per device provides granular configuration
+ * in multi device usage. It allocates resource pool in the hierarchy
+ * for each parent it come across for first resource. Later on resource
+ * pool will be available. Therefore it will be much faster thereon
+ * to charge/uncharge.
+ */
+int rdmacg_try_charge(struct rdma_cgroup **rdmacg,
+ struct rdmacg_device *device,
+ enum rdmacg_resource_type index)
+{
+ struct rdma_cgroup *cg, *p;
+ struct rdmacg_resource_pool *rpool;
+ s64 new;
+ int ret = 0;
+
+ if (index >= RDMACG_RESOURCE_MAX)
+ return -EINVAL;
+
+ /*
+ * hold on to css, as cgroup can be removed but resource
+ * accounting happens on css.
+ */
+ cg = get_current_rdmacg();
+
+ mutex_lock(&rdmacg_mutex);
+ for (p = cg; p; p = parent_rdmacg(p)) {
+ rpool = get_cg_rpool_locked(p, device);
+ if (IS_ERR(rpool)) {
+ ret = PTR_ERR(rpool);
+ goto err;
+ } else {
+ new = rpool->resources[index].usage + 1;
+ if (new > rpool->resources[index].max) {
+ ret = -EAGAIN;
+ goto err;
+ } else {
+ rpool->resources[index].usage = new;
+ rpool->usage_sum++;
+ }
+ }
+ }
+ mutex_unlock(&rdmacg_mutex);
+
+ *rdmacg = cg;
+ return 0;
+
+err:
+ mutex_unlock(&rdmacg_mutex);
+ rdmacg_uncharge_hierarchy(cg, device, p, index);
+ return ret;
+}
+EXPORT_SYMBOL(rdmacg_try_charge);
+
+/**
+ * rdmacg_register_device - register rdmacg device to rdma controller.
+ * @device: pointer to rdmacg device whose resources need to be accounted.
+ *
+ * If IB stack wish a device to participate in rdma cgroup resource
+ * tracking, it must invoke this API to register with rdma cgroup before
+ * any user space application can start using the RDMA resources.
+ */
+void rdmacg_register_device(struct rdmacg_device *device)
+{
+ INIT_LIST_HEAD(&device->dev_node);
+ INIT_LIST_HEAD(&device->rpools);
+
+ mutex_lock(&rdmacg_mutex);
+ list_add_tail(&device->dev_node, &rdmacg_devices);
+ mutex_unlock(&rdmacg_mutex);
+}
+EXPORT_SYMBOL(rdmacg_register_device);
+
+/**
+ * rdmacg_unregister_device - unregister rdmacg device from rdma controller.
+ * @device: pointer to rdmacg device which was previously registered with rdma
+ * controller using rdmacg_register_device().
+ *
+ * IB stack must invoke this after all the resources of the IB device
+ * are destroyed and after ensuring that no more resources will be created
+ * when this API is invoked.
+ */
+void rdmacg_unregister_device(struct rdmacg_device *device)
+{
+ struct rdmacg_resource_pool *rpool, *tmp;
+
+ /*
+ * Synchronize with any active resource settings,
+ * usage query happening via configfs.
+ */
+ mutex_lock(&rdmacg_mutex);
+ list_del_init(&device->dev_node);
+
+ /*
+ * Now that this device is off the cgroup list, its safe to free
+ * all the rpool resources.
+ */
+ list_for_each_entry_safe(rpool, tmp, &device->rpools, dev_node)
+ free_cg_rpool_locked(rpool);
+
+ mutex_unlock(&rdmacg_mutex);
+}
+EXPORT_SYMBOL(rdmacg_unregister_device);
+
+static int parse_resource(char *c, int *intval)
+{
+ substring_t argstr;
+ char *name, *value = c;
+ size_t len;
+ int ret, i;
+
+ name = strsep(&value, "=");
+ if (!name || !value)
+ return -EINVAL;
+
+ i = match_string(rdmacg_resource_names, RDMACG_RESOURCE_MAX, name);
+ if (i < 0)
+ return i;
+
+ len = strlen(value);
+
+ argstr.from = value;
+ argstr.to = value + len;
+
+ ret = match_int(&argstr, intval);
+ if (ret >= 0) {
+ if (*intval < 0)
+ return -EINVAL;
+ return i;
+ }
+ if (strncmp(value, RDMACG_MAX_STR, len) == 0) {
+ *intval = S32_MAX;
+ return i;
+ }
+ return -EINVAL;
+}
+
+static int rdmacg_parse_limits(char *options,
+ int *new_limits, unsigned long *enables)
+{
+ char *c;
+ int err = -EINVAL;
+
+ /* parse resource options */
+ while ((c = strsep(&options, " ")) != NULL) {
+ int index, intval;
+
+ index = parse_resource(c, &intval);
+ if (index < 0)
+ goto err;
+
+ new_limits[index] = intval;
+ *enables |= BIT(index);
+ }
+ return 0;
+
+err:
+ return err;
+}
+
+static struct rdmacg_device *rdmacg_get_device_locked(const char *name)
+{
+ struct rdmacg_device *device;
+
+ lockdep_assert_held(&rdmacg_mutex);
+
+ list_for_each_entry(device, &rdmacg_devices, dev_node)
+ if (!strcmp(name, device->name))
+ return device;
+
+ return NULL;
+}
+
+static ssize_t rdmacg_resource_set_max(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct rdma_cgroup *cg = css_rdmacg(of_css(of));
+ const char *dev_name;
+ struct rdmacg_resource_pool *rpool;
+ struct rdmacg_device *device;
+ char *options = strstrip(buf);
+ int *new_limits;
+ unsigned long enables = 0;
+ int i = 0, ret = 0;
+
+ /* extract the device name first */
+ dev_name = strsep(&options, " ");
+ if (!dev_name) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ new_limits = kcalloc(RDMACG_RESOURCE_MAX, sizeof(int), GFP_KERNEL);
+ if (!new_limits) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ ret = rdmacg_parse_limits(options, new_limits, &enables);
+ if (ret)
+ goto parse_err;
+
+ /* acquire lock to synchronize with hot plug devices */
+ mutex_lock(&rdmacg_mutex);
+
+ device = rdmacg_get_device_locked(dev_name);
+ if (!device) {
+ ret = -ENODEV;
+ goto dev_err;
+ }
+
+ rpool = get_cg_rpool_locked(cg, device);
+ if (IS_ERR(rpool)) {
+ ret = PTR_ERR(rpool);
+ goto dev_err;
+ }
+
+ /* now set the new limits of the rpool */
+ for_each_set_bit(i, &enables, RDMACG_RESOURCE_MAX)
+ set_resource_limit(rpool, i, new_limits[i]);
+
+ if (rpool->usage_sum == 0 &&
+ rpool->num_max_cnt == RDMACG_RESOURCE_MAX) {
+ /*
+ * No user of the rpool and all entries are set to max, so
+ * safe to delete this rpool.
+ */
+ free_cg_rpool_locked(rpool);
+ }
+
+dev_err:
+ mutex_unlock(&rdmacg_mutex);
+
+parse_err:
+ kfree(new_limits);
+
+err:
+ return ret ?: nbytes;
+}
+
+static void print_rpool_values(struct seq_file *sf,
+ struct rdmacg_resource_pool *rpool)
+{
+ enum rdmacg_file_type sf_type;
+ int i;
+ u32 value;
+
+ sf_type = seq_cft(sf)->private;
+
+ for (i = 0; i < RDMACG_RESOURCE_MAX; i++) {
+ seq_puts(sf, rdmacg_resource_names[i]);
+ seq_putc(sf, '=');
+ if (sf_type == RDMACG_RESOURCE_TYPE_MAX) {
+ if (rpool)
+ value = rpool->resources[i].max;
+ else
+ value = S32_MAX;
+ } else {
+ if (rpool)
+ value = rpool->resources[i].usage;
+ else
+ value = 0;
+ }
+
+ if (value == S32_MAX)
+ seq_puts(sf, RDMACG_MAX_STR);
+ else
+ seq_printf(sf, "%d", value);
+ seq_putc(sf, ' ');
+ }
+}
+
+static int rdmacg_resource_read(struct seq_file *sf, void *v)
+{
+ struct rdmacg_device *device;
+ struct rdmacg_resource_pool *rpool;
+ struct rdma_cgroup *cg = css_rdmacg(seq_css(sf));
+
+ mutex_lock(&rdmacg_mutex);
+
+ list_for_each_entry(device, &rdmacg_devices, dev_node) {
+ seq_printf(sf, "%s ", device->name);
+
+ rpool = find_cg_rpool_locked(cg, device);
+ print_rpool_values(sf, rpool);
+
+ seq_putc(sf, '\n');
+ }
+
+ mutex_unlock(&rdmacg_mutex);
+ return 0;
+}
+
+static struct cftype rdmacg_files[] = {
+ {
+ .name = "max",
+ .write = rdmacg_resource_set_max,
+ .seq_show = rdmacg_resource_read,
+ .private = RDMACG_RESOURCE_TYPE_MAX,
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+ {
+ .name = "current",
+ .seq_show = rdmacg_resource_read,
+ .private = RDMACG_RESOURCE_TYPE_STAT,
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+ { } /* terminate */
+};
+
+static struct cgroup_subsys_state *
+rdmacg_css_alloc(struct cgroup_subsys_state *parent)
+{
+ struct rdma_cgroup *cg;
+
+ cg = kzalloc(sizeof(*cg), GFP_KERNEL);
+ if (!cg)
+ return ERR_PTR(-ENOMEM);
+
+ INIT_LIST_HEAD(&cg->rpools);
+ return &cg->css;
+}
+
+static void rdmacg_css_free(struct cgroup_subsys_state *css)
+{
+ struct rdma_cgroup *cg = css_rdmacg(css);
+
+ kfree(cg);
+}
+
+/**
+ * rdmacg_css_offline - cgroup css_offline callback
+ * @css: css of interest
+ *
+ * This function is called when @css is about to go away and responsible
+ * for shooting down all rdmacg associated with @css. As part of that it
+ * marks all the resource pool entries to max value, so that when resources are
+ * uncharged, associated resource pool can be freed as well.
+ */
+static void rdmacg_css_offline(struct cgroup_subsys_state *css)
+{
+ struct rdma_cgroup *cg = css_rdmacg(css);
+ struct rdmacg_resource_pool *rpool;
+
+ mutex_lock(&rdmacg_mutex);
+
+ list_for_each_entry(rpool, &cg->rpools, cg_node)
+ set_all_resource_max_limit(rpool);
+
+ mutex_unlock(&rdmacg_mutex);
+}
+
+struct cgroup_subsys rdma_cgrp_subsys = {
+ .css_alloc = rdmacg_css_alloc,
+ .css_free = rdmacg_css_free,
+ .css_offline = rdmacg_css_offline,
+ .legacy_cftypes = rdmacg_files,
+ .dfl_cftypes = rdmacg_files,
+};
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
new file mode 100644
index 0000000000..d80d7a6081
--- /dev/null
+++ b/kernel/cgroup/rstat.c
@@ -0,0 +1,541 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include "cgroup-internal.h"
+
+#include <linux/sched/cputime.h>
+
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/btf_ids.h>
+
+static DEFINE_SPINLOCK(cgroup_rstat_lock);
+static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock);
+
+static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu);
+
+static struct cgroup_rstat_cpu *cgroup_rstat_cpu(struct cgroup *cgrp, int cpu)
+{
+ return per_cpu_ptr(cgrp->rstat_cpu, cpu);
+}
+
+/**
+ * cgroup_rstat_updated - keep track of updated rstat_cpu
+ * @cgrp: target cgroup
+ * @cpu: cpu on which rstat_cpu was updated
+ *
+ * @cgrp's rstat_cpu on @cpu was updated. Put it on the parent's matching
+ * rstat_cpu->updated_children list. See the comment on top of
+ * cgroup_rstat_cpu definition for details.
+ */
+__bpf_kfunc void cgroup_rstat_updated(struct cgroup *cgrp, int cpu)
+{
+ raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu);
+ unsigned long flags;
+
+ /*
+ * Speculative already-on-list test. This may race leading to
+ * temporary inaccuracies, which is fine.
+ *
+ * Because @parent's updated_children is terminated with @parent
+ * instead of NULL, we can tell whether @cgrp is on the list by
+ * testing the next pointer for NULL.
+ */
+ if (data_race(cgroup_rstat_cpu(cgrp, cpu)->updated_next))
+ return;
+
+ raw_spin_lock_irqsave(cpu_lock, flags);
+
+ /* put @cgrp and all ancestors on the corresponding updated lists */
+ while (true) {
+ struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
+ struct cgroup *parent = cgroup_parent(cgrp);
+ struct cgroup_rstat_cpu *prstatc;
+
+ /*
+ * Both additions and removals are bottom-up. If a cgroup
+ * is already in the tree, all ancestors are.
+ */
+ if (rstatc->updated_next)
+ break;
+
+ /* Root has no parent to link it to, but mark it busy */
+ if (!parent) {
+ rstatc->updated_next = cgrp;
+ break;
+ }
+
+ prstatc = cgroup_rstat_cpu(parent, cpu);
+ rstatc->updated_next = prstatc->updated_children;
+ prstatc->updated_children = cgrp;
+
+ cgrp = parent;
+ }
+
+ raw_spin_unlock_irqrestore(cpu_lock, flags);
+}
+
+/**
+ * cgroup_rstat_cpu_pop_updated - iterate and dismantle rstat_cpu updated tree
+ * @pos: current position
+ * @root: root of the tree to traversal
+ * @cpu: target cpu
+ *
+ * Walks the updated rstat_cpu tree on @cpu from @root. %NULL @pos starts
+ * the traversal and %NULL return indicates the end. During traversal,
+ * each returned cgroup is unlinked from the tree. Must be called with the
+ * matching cgroup_rstat_cpu_lock held.
+ *
+ * The only ordering guarantee is that, for a parent and a child pair
+ * covered by a given traversal, if a child is visited, its parent is
+ * guaranteed to be visited afterwards.
+ */
+static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos,
+ struct cgroup *root, int cpu)
+{
+ struct cgroup_rstat_cpu *rstatc;
+ struct cgroup *parent;
+
+ if (pos == root)
+ return NULL;
+
+ /*
+ * We're gonna walk down to the first leaf and visit/remove it. We
+ * can pick whatever unvisited node as the starting point.
+ */
+ if (!pos) {
+ pos = root;
+ /* return NULL if this subtree is not on-list */
+ if (!cgroup_rstat_cpu(pos, cpu)->updated_next)
+ return NULL;
+ } else {
+ pos = cgroup_parent(pos);
+ }
+
+ /* walk down to the first leaf */
+ while (true) {
+ rstatc = cgroup_rstat_cpu(pos, cpu);
+ if (rstatc->updated_children == pos)
+ break;
+ pos = rstatc->updated_children;
+ }
+
+ /*
+ * Unlink @pos from the tree. As the updated_children list is
+ * singly linked, we have to walk it to find the removal point.
+ * However, due to the way we traverse, @pos will be the first
+ * child in most cases. The only exception is @root.
+ */
+ parent = cgroup_parent(pos);
+ if (parent) {
+ struct cgroup_rstat_cpu *prstatc;
+ struct cgroup **nextp;
+
+ prstatc = cgroup_rstat_cpu(parent, cpu);
+ nextp = &prstatc->updated_children;
+ while (*nextp != pos) {
+ struct cgroup_rstat_cpu *nrstatc;
+
+ nrstatc = cgroup_rstat_cpu(*nextp, cpu);
+ WARN_ON_ONCE(*nextp == parent);
+ nextp = &nrstatc->updated_next;
+ }
+ *nextp = rstatc->updated_next;
+ }
+
+ rstatc->updated_next = NULL;
+ return pos;
+}
+
+/*
+ * A hook for bpf stat collectors to attach to and flush their stats.
+ * Together with providing bpf kfuncs for cgroup_rstat_updated() and
+ * cgroup_rstat_flush(), this enables a complete workflow where bpf progs that
+ * collect cgroup stats can integrate with rstat for efficient flushing.
+ *
+ * A static noinline declaration here could cause the compiler to optimize away
+ * the function. A global noinline declaration will keep the definition, but may
+ * optimize away the callsite. Therefore, __weak is needed to ensure that the
+ * call is still emitted, by telling the compiler that we don't know what the
+ * function might eventually be.
+ *
+ * __diag_* below are needed to dismiss the missing prototype warning.
+ */
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+ "kfuncs which will be used in BPF programs");
+
+__weak noinline void bpf_rstat_flush(struct cgroup *cgrp,
+ struct cgroup *parent, int cpu)
+{
+}
+
+__diag_pop();
+
+/* see cgroup_rstat_flush() */
+static void cgroup_rstat_flush_locked(struct cgroup *cgrp)
+ __releases(&cgroup_rstat_lock) __acquires(&cgroup_rstat_lock)
+{
+ int cpu;
+
+ lockdep_assert_held(&cgroup_rstat_lock);
+
+ for_each_possible_cpu(cpu) {
+ raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock,
+ cpu);
+ struct cgroup *pos = NULL;
+ unsigned long flags;
+
+ /*
+ * The _irqsave() is needed because cgroup_rstat_lock is
+ * spinlock_t which is a sleeping lock on PREEMPT_RT. Acquiring
+ * this lock with the _irq() suffix only disables interrupts on
+ * a non-PREEMPT_RT kernel. The raw_spinlock_t below disables
+ * interrupts on both configurations. The _irqsave() ensures
+ * that interrupts are always disabled and later restored.
+ */
+ raw_spin_lock_irqsave(cpu_lock, flags);
+ while ((pos = cgroup_rstat_cpu_pop_updated(pos, cgrp, cpu))) {
+ struct cgroup_subsys_state *css;
+
+ cgroup_base_stat_flush(pos, cpu);
+ bpf_rstat_flush(pos, cgroup_parent(pos), cpu);
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(css, &pos->rstat_css_list,
+ rstat_css_node)
+ css->ss->css_rstat_flush(css, cpu);
+ rcu_read_unlock();
+ }
+ raw_spin_unlock_irqrestore(cpu_lock, flags);
+
+ /* play nice and yield if necessary */
+ if (need_resched() || spin_needbreak(&cgroup_rstat_lock)) {
+ spin_unlock_irq(&cgroup_rstat_lock);
+ if (!cond_resched())
+ cpu_relax();
+ spin_lock_irq(&cgroup_rstat_lock);
+ }
+ }
+}
+
+/**
+ * cgroup_rstat_flush - flush stats in @cgrp's subtree
+ * @cgrp: target cgroup
+ *
+ * Collect all per-cpu stats in @cgrp's subtree into the global counters
+ * and propagate them upwards. After this function returns, all cgroups in
+ * the subtree have up-to-date ->stat.
+ *
+ * This also gets all cgroups in the subtree including @cgrp off the
+ * ->updated_children lists.
+ *
+ * This function may block.
+ */
+__bpf_kfunc void cgroup_rstat_flush(struct cgroup *cgrp)
+{
+ might_sleep();
+
+ spin_lock_irq(&cgroup_rstat_lock);
+ cgroup_rstat_flush_locked(cgrp);
+ spin_unlock_irq(&cgroup_rstat_lock);
+}
+
+/**
+ * cgroup_rstat_flush_hold - flush stats in @cgrp's subtree and hold
+ * @cgrp: target cgroup
+ *
+ * Flush stats in @cgrp's subtree and prevent further flushes. Must be
+ * paired with cgroup_rstat_flush_release().
+ *
+ * This function may block.
+ */
+void cgroup_rstat_flush_hold(struct cgroup *cgrp)
+ __acquires(&cgroup_rstat_lock)
+{
+ might_sleep();
+ spin_lock_irq(&cgroup_rstat_lock);
+ cgroup_rstat_flush_locked(cgrp);
+}
+
+/**
+ * cgroup_rstat_flush_release - release cgroup_rstat_flush_hold()
+ */
+void cgroup_rstat_flush_release(void)
+ __releases(&cgroup_rstat_lock)
+{
+ spin_unlock_irq(&cgroup_rstat_lock);
+}
+
+int cgroup_rstat_init(struct cgroup *cgrp)
+{
+ int cpu;
+
+ /* the root cgrp has rstat_cpu preallocated */
+ if (!cgrp->rstat_cpu) {
+ cgrp->rstat_cpu = alloc_percpu(struct cgroup_rstat_cpu);
+ if (!cgrp->rstat_cpu)
+ return -ENOMEM;
+ }
+
+ /* ->updated_children list is self terminated */
+ for_each_possible_cpu(cpu) {
+ struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
+
+ rstatc->updated_children = cgrp;
+ u64_stats_init(&rstatc->bsync);
+ }
+
+ return 0;
+}
+
+void cgroup_rstat_exit(struct cgroup *cgrp)
+{
+ int cpu;
+
+ cgroup_rstat_flush(cgrp);
+
+ /* sanity check */
+ for_each_possible_cpu(cpu) {
+ struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
+
+ if (WARN_ON_ONCE(rstatc->updated_children != cgrp) ||
+ WARN_ON_ONCE(rstatc->updated_next))
+ return;
+ }
+
+ free_percpu(cgrp->rstat_cpu);
+ cgrp->rstat_cpu = NULL;
+}
+
+void __init cgroup_rstat_boot(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ raw_spin_lock_init(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu));
+}
+
+/*
+ * Functions for cgroup basic resource statistics implemented on top of
+ * rstat.
+ */
+static void cgroup_base_stat_add(struct cgroup_base_stat *dst_bstat,
+ struct cgroup_base_stat *src_bstat)
+{
+ dst_bstat->cputime.utime += src_bstat->cputime.utime;
+ dst_bstat->cputime.stime += src_bstat->cputime.stime;
+ dst_bstat->cputime.sum_exec_runtime += src_bstat->cputime.sum_exec_runtime;
+#ifdef CONFIG_SCHED_CORE
+ dst_bstat->forceidle_sum += src_bstat->forceidle_sum;
+#endif
+}
+
+static void cgroup_base_stat_sub(struct cgroup_base_stat *dst_bstat,
+ struct cgroup_base_stat *src_bstat)
+{
+ dst_bstat->cputime.utime -= src_bstat->cputime.utime;
+ dst_bstat->cputime.stime -= src_bstat->cputime.stime;
+ dst_bstat->cputime.sum_exec_runtime -= src_bstat->cputime.sum_exec_runtime;
+#ifdef CONFIG_SCHED_CORE
+ dst_bstat->forceidle_sum -= src_bstat->forceidle_sum;
+#endif
+}
+
+static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu)
+{
+ struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
+ struct cgroup *parent = cgroup_parent(cgrp);
+ struct cgroup_rstat_cpu *prstatc;
+ struct cgroup_base_stat delta;
+ unsigned seq;
+
+ /* Root-level stats are sourced from system-wide CPU stats */
+ if (!parent)
+ return;
+
+ /* fetch the current per-cpu values */
+ do {
+ seq = __u64_stats_fetch_begin(&rstatc->bsync);
+ delta = rstatc->bstat;
+ } while (__u64_stats_fetch_retry(&rstatc->bsync, seq));
+
+ /* propagate per-cpu delta to cgroup and per-cpu global statistics */
+ cgroup_base_stat_sub(&delta, &rstatc->last_bstat);
+ cgroup_base_stat_add(&cgrp->bstat, &delta);
+ cgroup_base_stat_add(&rstatc->last_bstat, &delta);
+ cgroup_base_stat_add(&rstatc->subtree_bstat, &delta);
+
+ /* propagate cgroup and per-cpu global delta to parent (unless that's root) */
+ if (cgroup_parent(parent)) {
+ delta = cgrp->bstat;
+ cgroup_base_stat_sub(&delta, &cgrp->last_bstat);
+ cgroup_base_stat_add(&parent->bstat, &delta);
+ cgroup_base_stat_add(&cgrp->last_bstat, &delta);
+
+ delta = rstatc->subtree_bstat;
+ prstatc = cgroup_rstat_cpu(parent, cpu);
+ cgroup_base_stat_sub(&delta, &rstatc->last_subtree_bstat);
+ cgroup_base_stat_add(&prstatc->subtree_bstat, &delta);
+ cgroup_base_stat_add(&rstatc->last_subtree_bstat, &delta);
+ }
+}
+
+static struct cgroup_rstat_cpu *
+cgroup_base_stat_cputime_account_begin(struct cgroup *cgrp, unsigned long *flags)
+{
+ struct cgroup_rstat_cpu *rstatc;
+
+ rstatc = get_cpu_ptr(cgrp->rstat_cpu);
+ *flags = u64_stats_update_begin_irqsave(&rstatc->bsync);
+ return rstatc;
+}
+
+static void cgroup_base_stat_cputime_account_end(struct cgroup *cgrp,
+ struct cgroup_rstat_cpu *rstatc,
+ unsigned long flags)
+{
+ u64_stats_update_end_irqrestore(&rstatc->bsync, flags);
+ cgroup_rstat_updated(cgrp, smp_processor_id());
+ put_cpu_ptr(rstatc);
+}
+
+void __cgroup_account_cputime(struct cgroup *cgrp, u64 delta_exec)
+{
+ struct cgroup_rstat_cpu *rstatc;
+ unsigned long flags;
+
+ rstatc = cgroup_base_stat_cputime_account_begin(cgrp, &flags);
+ rstatc->bstat.cputime.sum_exec_runtime += delta_exec;
+ cgroup_base_stat_cputime_account_end(cgrp, rstatc, flags);
+}
+
+void __cgroup_account_cputime_field(struct cgroup *cgrp,
+ enum cpu_usage_stat index, u64 delta_exec)
+{
+ struct cgroup_rstat_cpu *rstatc;
+ unsigned long flags;
+
+ rstatc = cgroup_base_stat_cputime_account_begin(cgrp, &flags);
+
+ switch (index) {
+ case CPUTIME_USER:
+ case CPUTIME_NICE:
+ rstatc->bstat.cputime.utime += delta_exec;
+ break;
+ case CPUTIME_SYSTEM:
+ case CPUTIME_IRQ:
+ case CPUTIME_SOFTIRQ:
+ rstatc->bstat.cputime.stime += delta_exec;
+ break;
+#ifdef CONFIG_SCHED_CORE
+ case CPUTIME_FORCEIDLE:
+ rstatc->bstat.forceidle_sum += delta_exec;
+ break;
+#endif
+ default:
+ break;
+ }
+
+ cgroup_base_stat_cputime_account_end(cgrp, rstatc, flags);
+}
+
+/*
+ * compute the cputime for the root cgroup by getting the per cpu data
+ * at a global level, then categorizing the fields in a manner consistent
+ * with how it is done by __cgroup_account_cputime_field for each bit of
+ * cpu time attributed to a cgroup.
+ */
+static void root_cgroup_cputime(struct cgroup_base_stat *bstat)
+{
+ struct task_cputime *cputime = &bstat->cputime;
+ int i;
+
+ memset(bstat, 0, sizeof(*bstat));
+ for_each_possible_cpu(i) {
+ struct kernel_cpustat kcpustat;
+ u64 *cpustat = kcpustat.cpustat;
+ u64 user = 0;
+ u64 sys = 0;
+
+ kcpustat_cpu_fetch(&kcpustat, i);
+
+ user += cpustat[CPUTIME_USER];
+ user += cpustat[CPUTIME_NICE];
+ cputime->utime += user;
+
+ sys += cpustat[CPUTIME_SYSTEM];
+ sys += cpustat[CPUTIME_IRQ];
+ sys += cpustat[CPUTIME_SOFTIRQ];
+ cputime->stime += sys;
+
+ cputime->sum_exec_runtime += user;
+ cputime->sum_exec_runtime += sys;
+ cputime->sum_exec_runtime += cpustat[CPUTIME_STEAL];
+
+#ifdef CONFIG_SCHED_CORE
+ bstat->forceidle_sum += cpustat[CPUTIME_FORCEIDLE];
+#endif
+ }
+}
+
+void cgroup_base_stat_cputime_show(struct seq_file *seq)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+ u64 usage, utime, stime;
+ struct cgroup_base_stat bstat;
+#ifdef CONFIG_SCHED_CORE
+ u64 forceidle_time;
+#endif
+
+ if (cgroup_parent(cgrp)) {
+ cgroup_rstat_flush_hold(cgrp);
+ usage = cgrp->bstat.cputime.sum_exec_runtime;
+ cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime,
+ &utime, &stime);
+#ifdef CONFIG_SCHED_CORE
+ forceidle_time = cgrp->bstat.forceidle_sum;
+#endif
+ cgroup_rstat_flush_release();
+ } else {
+ root_cgroup_cputime(&bstat);
+ usage = bstat.cputime.sum_exec_runtime;
+ utime = bstat.cputime.utime;
+ stime = bstat.cputime.stime;
+#ifdef CONFIG_SCHED_CORE
+ forceidle_time = bstat.forceidle_sum;
+#endif
+ }
+
+ do_div(usage, NSEC_PER_USEC);
+ do_div(utime, NSEC_PER_USEC);
+ do_div(stime, NSEC_PER_USEC);
+#ifdef CONFIG_SCHED_CORE
+ do_div(forceidle_time, NSEC_PER_USEC);
+#endif
+
+ seq_printf(seq, "usage_usec %llu\n"
+ "user_usec %llu\n"
+ "system_usec %llu\n",
+ usage, utime, stime);
+
+#ifdef CONFIG_SCHED_CORE
+ seq_printf(seq, "core_sched.force_idle_usec %llu\n", forceidle_time);
+#endif
+}
+
+/* Add bpf kfuncs for cgroup_rstat_updated() and cgroup_rstat_flush() */
+BTF_SET8_START(bpf_rstat_kfunc_ids)
+BTF_ID_FLAGS(func, cgroup_rstat_updated)
+BTF_ID_FLAGS(func, cgroup_rstat_flush, KF_SLEEPABLE)
+BTF_SET8_END(bpf_rstat_kfunc_ids)
+
+static const struct btf_kfunc_id_set bpf_rstat_kfunc_set = {
+ .owner = THIS_MODULE,
+ .set = &bpf_rstat_kfunc_ids,
+};
+
+static int __init bpf_rstat_kfunc_init(void)
+{
+ return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING,
+ &bpf_rstat_kfunc_set);
+}
+late_initcall(bpf_rstat_kfunc_init);