Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 246 insertions, 0 deletions

diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c
new file mode 100644
index 0000000000..1854850b4b
--- /dev/null
+++ b/mm/mmap_lock.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: GPL-2.0
+#define CREATE_TRACE_POINTS
+#include <trace/events/mmap_lock.h>
+
+#include <linux/mm.h>
+#include <linux/cgroup.h>
+#include <linux/memcontrol.h>
+#include <linux/mmap_lock.h>
+#include <linux/mutex.h>
+#include <linux/percpu.h>
+#include <linux/rcupdate.h>
+#include <linux/smp.h>
+#include <linux/trace_events.h>
+#include <linux/local_lock.h>
+
+EXPORT_TRACEPOINT_SYMBOL(mmap_lock_start_locking);
+EXPORT_TRACEPOINT_SYMBOL(mmap_lock_acquire_returned);
+EXPORT_TRACEPOINT_SYMBOL(mmap_lock_released);
+
+#ifdef CONFIG_MEMCG
+
+/*
+ * Our various events all share the same buffer (because we don't want or need
+ * to allocate a set of buffers *per event type*), so we need to protect against
+ * concurrent _reg() and _unreg() calls, and count how many _reg() calls have
+ * been made.
+ */
+static DEFINE_MUTEX(reg_lock);
+static int reg_refcount; /* Protected by reg_lock. */
+
+/*
+ * Size of the buffer for memcg path names. Ignoring stack trace support,
+ * trace_events_hist.c uses MAX_FILTER_STR_VAL for this, so we also use it.
+ */
+#define MEMCG_PATH_BUF_SIZE MAX_FILTER_STR_VAL
+
+/*
+ * How many contexts our trace events might be called in: normal, softirq, irq,
+ * and NMI.
+ */
+#define CONTEXT_COUNT 4
+
+struct memcg_path {
+	local_lock_t lock;
+	char __rcu *buf;
+	local_t buf_idx;
+};
+static DEFINE_PER_CPU(struct memcg_path, memcg_paths) = {
+	.lock = INIT_LOCAL_LOCK(lock),
+	.buf_idx = LOCAL_INIT(0),
+};
+
+static char **tmp_bufs;
+
+/* Called with reg_lock held. */
+static void free_memcg_path_bufs(void)
+{
+	struct memcg_path *memcg_path;
+	int cpu;
+	char **old = tmp_bufs;
+
+	for_each_possible_cpu(cpu) {
+		memcg_path = per_cpu_ptr(&memcg_paths, cpu);
+		*(old++) = rcu_dereference_protected(memcg_path->buf,
+			lockdep_is_held(&reg_lock));
+		rcu_assign_pointer(memcg_path->buf, NULL);
+	}
+
+	/* Wait for inflight memcg_path_buf users to finish. */
+	synchronize_rcu();
+
+	old = tmp_bufs;
+	for_each_possible_cpu(cpu) {
+		kfree(*(old++));
+	}
+
+	kfree(tmp_bufs);
+	tmp_bufs = NULL;
+}
+
+int trace_mmap_lock_reg(void)
+{
+	int cpu;
+	char *new;
+
+	mutex_lock(&reg_lock);
+
+	/* If the refcount is going 0->1, proceed with allocating buffers. */
+	if (reg_refcount++)
+		goto out;
+
+	tmp_bufs = kmalloc_array(num_possible_cpus(), sizeof(*tmp_bufs),
+				 GFP_KERNEL);
+	if (tmp_bufs == NULL)
+		goto out_fail;
+
+	for_each_possible_cpu(cpu) {
+		new = kmalloc(MEMCG_PATH_BUF_SIZE * CONTEXT_COUNT, GFP_KERNEL);
+		if (new == NULL)
+			goto out_fail_free;
+		rcu_assign_pointer(per_cpu_ptr(&memcg_paths, cpu)->buf, new);
+		/* Don't need to wait for inflights, they'd have gotten NULL. */
+	}
+
+out:
+	mutex_unlock(&reg_lock);
+	return 0;
+
+out_fail_free:
+	free_memcg_path_bufs();
+out_fail:
+	/* Since we failed, undo the earlier ref increment. */
+	--reg_refcount;
+
+	mutex_unlock(&reg_lock);
+	return -ENOMEM;
+}
+
+void trace_mmap_lock_unreg(void)
+{
+	mutex_lock(&reg_lock);
+
+	/* If the refcount is going 1->0, proceed with freeing buffers. */
+	if (--reg_refcount)
+		goto out;
+
+	free_memcg_path_bufs();
+
+out:
+	mutex_unlock(&reg_lock);
+}
+
+static inline char *get_memcg_path_buf(void)
+{
+	struct memcg_path *memcg_path = this_cpu_ptr(&memcg_paths);
+	char *buf;
+	int idx;
+
+	rcu_read_lock();
+	buf = rcu_dereference(memcg_path->buf);
+	if (buf == NULL) {
+		rcu_read_unlock();
+		return NULL;
+	}
+	idx = local_add_return(MEMCG_PATH_BUF_SIZE, &memcg_path->buf_idx) -
+	      MEMCG_PATH_BUF_SIZE;
+	return &buf[idx];
+}
+
+static inline void put_memcg_path_buf(void)
+{
+	local_sub(MEMCG_PATH_BUF_SIZE, &this_cpu_ptr(&memcg_paths)->buf_idx);
+	rcu_read_unlock();
+}
+
+#define TRACE_MMAP_LOCK_EVENT(type, mm, ...)                                   \
+	do {                                                                   \
+		const char *memcg_path;                                        \
+		local_lock(&memcg_paths.lock);                                 \
+		memcg_path = get_mm_memcg_path(mm);                            \
+		trace_mmap_lock_##type(mm,                                     \
+				       memcg_path != NULL ? memcg_path : "",   \
+				       ##__VA_ARGS__);                         \
+		if (likely(memcg_path != NULL))                                \
+			put_memcg_path_buf();                                  \
+		local_unlock(&memcg_paths.lock);                               \
+	} while (0)
+
+#else /* !CONFIG_MEMCG */
+
+int trace_mmap_lock_reg(void)
+{
+	return 0;
+}
+
+void trace_mmap_lock_unreg(void)
+{
+}
+
+#define TRACE_MMAP_LOCK_EVENT(type, mm, ...)                                   \
+	trace_mmap_lock_##type(mm, "", ##__VA_ARGS__)
+
+#endif /* CONFIG_MEMCG */
+
+#ifdef CONFIG_TRACING
+#ifdef CONFIG_MEMCG
+/*
+ * Write the given mm_struct's memcg path to a percpu buffer, and return a
+ * pointer to it. If the path cannot be determined, or no buffer was available
+ * (because the trace event is being unregistered), NULL is returned.
+ *
+ * Note: buffers are allocated per-cpu to avoid locking, so preemption must be
+ * disabled by the caller before calling us, and re-enabled only after the
+ * caller is done with the pointer.
+ *
+ * The caller must call put_memcg_path_buf() once the buffer is no longer
+ * needed. This must be done while preemption is still disabled.
+ */
+static const char *get_mm_memcg_path(struct mm_struct *mm)
+{
+	char *buf = NULL;
+	struct mem_cgroup *memcg = get_mem_cgroup_from_mm(mm);
+
+	if (memcg == NULL)
+		goto out;
+	if (unlikely(memcg->css.cgroup == NULL))
+		goto out_put;
+
+	buf = get_memcg_path_buf();
+	if (buf == NULL)
+		goto out_put;
+
+	cgroup_path(memcg->css.cgroup, buf, MEMCG_PATH_BUF_SIZE);
+
+out_put:
+	css_put(&memcg->css);
+out:
+	return buf;
+}
+
+#endif /* CONFIG_MEMCG */
+
+/*
+ * Trace calls must be in a separate file, as otherwise there's a circular
+ * dependency between linux/mmap_lock.h and trace/events/mmap_lock.h.
+ */
+
+void __mmap_lock_do_trace_start_locking(struct mm_struct *mm, bool write)
+{
+	TRACE_MMAP_LOCK_EVENT(start_locking, mm, write);
+}
+EXPORT_SYMBOL(__mmap_lock_do_trace_start_locking);
+
+void __mmap_lock_do_trace_acquire_returned(struct mm_struct *mm, bool write,
+					   bool success)
+{
+	TRACE_MMAP_LOCK_EVENT(acquire_returned, mm, write, success);
+}
+EXPORT_SYMBOL(__mmap_lock_do_trace_acquire_returned);
+
+void __mmap_lock_do_trace_released(struct mm_struct *mm, bool write)
+{
+	TRACE_MMAP_LOCK_EVENT(released, mm, write);
+}
+EXPORT_SYMBOL(__mmap_lock_do_trace_released);
+#endif /* CONFIG_TRACING */