diff options
Diffstat (limited to 'include/linux/sched/mm.h')
| -rw-r--r-- | include/linux/sched/mm.h | 366 |
1 files changed, 366 insertions, 0 deletions
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h new file mode 100644 index 000000000..ef54f4b3f --- /dev/null +++ b/include/linux/sched/mm.h @@ -0,0 +1,366 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_SCHED_MM_H +#define _LINUX_SCHED_MM_H + +#include <linux/kernel.h> +#include <linux/atomic.h> +#include <linux/sched.h> +#include <linux/mm_types.h> +#include <linux/gfp.h> +#include <linux/sync_core.h> + +/* + * Routines for handling mm_structs + */ +extern struct mm_struct *mm_alloc(void); + +/** + * mmgrab() - Pin a &struct mm_struct. + * @mm: The &struct mm_struct to pin. + * + * Make sure that @mm will not get freed even after the owning task + * exits. This doesn't guarantee that the associated address space + * will still exist later on and mmget_not_zero() has to be used before + * accessing it. + * + * This is a preferred way to to pin @mm for a longer/unbounded amount + * of time. + * + * Use mmdrop() to release the reference acquired by mmgrab(). + * + * See also <Documentation/vm/active_mm.rst> for an in-depth explanation + * of &mm_struct.mm_count vs &mm_struct.mm_users. + */ +static inline void mmgrab(struct mm_struct *mm) +{ + atomic_inc(&mm->mm_count); +} + +extern void __mmdrop(struct mm_struct *mm); + +static inline void mmdrop(struct mm_struct *mm) +{ + /* + * The implicit full barrier implied by atomic_dec_and_test() is + * required by the membarrier system call before returning to + * user-space, after storing to rq->curr. + */ + if (unlikely(atomic_dec_and_test(&mm->mm_count))) + __mmdrop(mm); +} + +void mmdrop(struct mm_struct *mm); + +/* + * This has to be called after a get_task_mm()/mmget_not_zero() + * followed by taking the mmap_sem for writing before modifying the + * vmas or anything the coredump pretends not to change from under it. + * + * It also has to be called when mmgrab() is used in the context of + * the process, but then the mm_count refcount is transferred outside + * the context of the process to run down_write() on that pinned mm. + * + * NOTE: find_extend_vma() called from GUP context is the only place + * that can modify the "mm" (notably the vm_start/end) under mmap_sem + * for reading and outside the context of the process, so it is also + * the only case that holds the mmap_sem for reading that must call + * this function. Generally if the mmap_sem is hold for reading + * there's no need of this check after get_task_mm()/mmget_not_zero(). + * + * This function can be obsoleted and the check can be removed, after + * the coredump code will hold the mmap_sem for writing before + * invoking the ->core_dump methods. + */ +static inline bool mmget_still_valid(struct mm_struct *mm) +{ + return likely(!mm->core_state); +} + +/** + * mmget() - Pin the address space associated with a &struct mm_struct. + * @mm: The address space to pin. + * + * Make sure that the address space of the given &struct mm_struct doesn't + * go away. This does not protect against parts of the address space being + * modified or freed, however. + * + * Never use this function to pin this address space for an + * unbounded/indefinite amount of time. + * + * Use mmput() to release the reference acquired by mmget(). + * + * See also <Documentation/vm/active_mm.rst> for an in-depth explanation + * of &mm_struct.mm_count vs &mm_struct.mm_users. + */ +static inline void mmget(struct mm_struct *mm) +{ + atomic_inc(&mm->mm_users); +} + +static inline bool mmget_not_zero(struct mm_struct *mm) +{ + return atomic_inc_not_zero(&mm->mm_users); +} + +/* mmput gets rid of the mappings and all user-space */ +extern void mmput(struct mm_struct *); +#ifdef CONFIG_MMU +/* same as above but performs the slow path from the async context. Can + * be called from the atomic context as well + */ +void mmput_async(struct mm_struct *); +#endif + +/* Grab a reference to a task's mm, if it is not already going away */ +extern struct mm_struct *get_task_mm(struct task_struct *task); +/* + * Grab a reference to a task's mm, if it is not already going away + * and ptrace_may_access with the mode parameter passed to it + * succeeds. + */ +extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode); +/* Remove the current tasks stale references to the old mm_struct on exit() */ +extern void exit_mm_release(struct task_struct *, struct mm_struct *); +/* Remove the current tasks stale references to the old mm_struct on exec() */ +extern void exec_mm_release(struct task_struct *, struct mm_struct *); + +#ifdef CONFIG_MEMCG +extern void mm_update_next_owner(struct mm_struct *mm); +#else +static inline void mm_update_next_owner(struct mm_struct *mm) +{ +} +#endif /* CONFIG_MEMCG */ + +#ifdef CONFIG_MMU +extern void arch_pick_mmap_layout(struct mm_struct *mm, + struct rlimit *rlim_stack); +extern unsigned long +arch_get_unmapped_area(struct file *, unsigned long, unsigned long, + unsigned long, unsigned long); +extern unsigned long +arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, + unsigned long flags); +#else +static inline void arch_pick_mmap_layout(struct mm_struct *mm, + struct rlimit *rlim_stack) {} +#endif + +static inline bool in_vfork(struct task_struct *tsk) +{ + bool ret; + + /* + * need RCU to access ->real_parent if CLONE_VM was used along with + * CLONE_PARENT. + * + * We check real_parent->mm == tsk->mm because CLONE_VFORK does not + * imply CLONE_VM + * + * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus + * ->real_parent is not necessarily the task doing vfork(), so in + * theory we can't rely on task_lock() if we want to dereference it. + * + * And in this case we can't trust the real_parent->mm == tsk->mm + * check, it can be false negative. But we do not care, if init or + * another oom-unkillable task does this it should blame itself. + */ + rcu_read_lock(); + ret = tsk->vfork_done && + rcu_dereference(tsk->real_parent)->mm == tsk->mm; + rcu_read_unlock(); + + return ret; +} + +/* + * Applies per-task gfp context to the given allocation flags. + * PF_MEMALLOC_NOIO implies GFP_NOIO + * PF_MEMALLOC_NOFS implies GFP_NOFS + */ +static inline gfp_t current_gfp_context(gfp_t flags) +{ + /* + * NOIO implies both NOIO and NOFS and it is a weaker context + * so always make sure it makes precendence + */ + if (unlikely(current->flags & PF_MEMALLOC_NOIO)) + flags &= ~(__GFP_IO | __GFP_FS); + else if (unlikely(current->flags & PF_MEMALLOC_NOFS)) + flags &= ~__GFP_FS; + return flags; +} + +#ifdef CONFIG_LOCKDEP +extern void __fs_reclaim_acquire(void); +extern void __fs_reclaim_release(void); +extern void fs_reclaim_acquire(gfp_t gfp_mask); +extern void fs_reclaim_release(gfp_t gfp_mask); +#else +static inline void __fs_reclaim_acquire(void) { } +static inline void __fs_reclaim_release(void) { } +static inline void fs_reclaim_acquire(gfp_t gfp_mask) { } +static inline void fs_reclaim_release(gfp_t gfp_mask) { } +#endif + +/** + * memalloc_noio_save - Marks implicit GFP_NOIO allocation scope. + * + * This functions marks the beginning of the GFP_NOIO allocation scope. + * All further allocations will implicitly drop __GFP_IO flag and so + * they are safe for the IO critical section from the allocation recursion + * point of view. Use memalloc_noio_restore to end the scope with flags + * returned by this function. + * + * This function is safe to be used from any context. + */ +static inline unsigned int memalloc_noio_save(void) +{ + unsigned int flags = current->flags & PF_MEMALLOC_NOIO; + current->flags |= PF_MEMALLOC_NOIO; + return flags; +} + +/** + * memalloc_noio_restore - Ends the implicit GFP_NOIO scope. + * @flags: Flags to restore. + * + * Ends the implicit GFP_NOIO scope started by memalloc_noio_save function. + * Always make sure that that the given flags is the return value from the + * pairing memalloc_noio_save call. + */ +static inline void memalloc_noio_restore(unsigned int flags) +{ + current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags; +} + +/** + * memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope. + * + * This functions marks the beginning of the GFP_NOFS allocation scope. + * All further allocations will implicitly drop __GFP_FS flag and so + * they are safe for the FS critical section from the allocation recursion + * point of view. Use memalloc_nofs_restore to end the scope with flags + * returned by this function. + * + * This function is safe to be used from any context. + */ +static inline unsigned int memalloc_nofs_save(void) +{ + unsigned int flags = current->flags & PF_MEMALLOC_NOFS; + current->flags |= PF_MEMALLOC_NOFS; + return flags; +} + +/** + * memalloc_nofs_restore - Ends the implicit GFP_NOFS scope. + * @flags: Flags to restore. + * + * Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function. + * Always make sure that that the given flags is the return value from the + * pairing memalloc_nofs_save call. + */ +static inline void memalloc_nofs_restore(unsigned int flags) +{ + current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags; +} + +static inline unsigned int memalloc_noreclaim_save(void) +{ + unsigned int flags = current->flags & PF_MEMALLOC; + current->flags |= PF_MEMALLOC; + return flags; +} + +static inline void memalloc_noreclaim_restore(unsigned int flags) +{ + current->flags = (current->flags & ~PF_MEMALLOC) | flags; +} + +#ifdef CONFIG_MEMCG +/** + * memalloc_use_memcg - Starts the remote memcg charging scope. + * @memcg: memcg to charge. + * + * This function marks the beginning of the remote memcg charging scope. All the + * __GFP_ACCOUNT allocations till the end of the scope will be charged to the + * given memcg. + * + * NOTE: This function is not nesting safe. + */ +static inline void memalloc_use_memcg(struct mem_cgroup *memcg) +{ + WARN_ON_ONCE(current->active_memcg); + current->active_memcg = memcg; +} + +/** + * memalloc_unuse_memcg - Ends the remote memcg charging scope. + * + * This function marks the end of the remote memcg charging scope started by + * memalloc_use_memcg(). + */ +static inline void memalloc_unuse_memcg(void) +{ + current->active_memcg = NULL; +} +#else +static inline void memalloc_use_memcg(struct mem_cgroup *memcg) +{ +} + +static inline void memalloc_unuse_memcg(void) +{ +} +#endif + +#ifdef CONFIG_MEMBARRIER +enum { + MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0), + MEMBARRIER_STATE_PRIVATE_EXPEDITED = (1U << 1), + MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY = (1U << 2), + MEMBARRIER_STATE_GLOBAL_EXPEDITED = (1U << 3), + MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY = (1U << 4), + MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE = (1U << 5), +}; + +enum { + MEMBARRIER_FLAG_SYNC_CORE = (1U << 0), +}; + +#ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS +#include <asm/membarrier.h> +#endif + +static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm) +{ + if (current->mm != mm) + return; + if (likely(!(atomic_read(&mm->membarrier_state) & + MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE))) + return; + sync_core_before_usermode(); +} + +static inline void membarrier_execve(struct task_struct *t) +{ + atomic_set(&t->mm->membarrier_state, 0); +} +#else +#ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS +static inline void membarrier_arch_switch_mm(struct mm_struct *prev, + struct mm_struct *next, + struct task_struct *tsk) +{ +} +#endif +static inline void membarrier_execve(struct task_struct *t) +{ +} +static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm) +{ +} +#endif + +#endif /* _LINUX_SCHED_MM_H */ |