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