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- /* 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 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);
- }
- /**
- * 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
- #ifndef arch_get_mmap_end
- #define arch_get_mmap_end(addr) (TASK_SIZE)
- #endif
- #ifndef arch_get_mmap_base
- #define arch_get_mmap_base(addr, base) (base)
- #endif
- 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)
- {
- unsigned int pflags = READ_ONCE(current->flags);
- if (unlikely(pflags & (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS))) {
- /*
- * NOIO implies both NOIO and NOFS and it is a weaker context
- * so always make sure it makes precedence
- */
- if (pflags & PF_MEMALLOC_NOIO)
- flags &= ~(__GFP_IO | __GFP_FS);
- else if (pflags & 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 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 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_CMA
- static inline unsigned int memalloc_nocma_save(void)
- {
- unsigned int flags = current->flags & PF_MEMALLOC_NOCMA;
- current->flags |= PF_MEMALLOC_NOCMA;
- return flags;
- }
- static inline void memalloc_nocma_restore(unsigned int flags)
- {
- current->flags = (current->flags & ~PF_MEMALLOC_NOCMA) | flags;
- }
- #else
- static inline unsigned int memalloc_nocma_save(void)
- {
- return 0;
- }
- static inline void memalloc_nocma_restore(unsigned int flags)
- {
- }
- #endif
- #ifdef CONFIG_MEMCG
- DECLARE_PER_CPU(struct mem_cgroup *, int_active_memcg);
- /**
- * set_active_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 can nest. Users must save the return value and
- * reset the previous value after their own charging scope is over.
- */
- static inline struct mem_cgroup *
- set_active_memcg(struct mem_cgroup *memcg)
- {
- struct mem_cgroup *old;
- if (in_interrupt()) {
- old = this_cpu_read(int_active_memcg);
- this_cpu_write(int_active_memcg, memcg);
- } else {
- old = current->active_memcg;
- current->active_memcg = memcg;
- }
- return old;
- }
- #else
- static inline struct mem_cgroup *
- set_active_memcg(struct mem_cgroup *memcg)
- {
- return NULL;
- }
- #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),
- MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ_READY = (1U << 6),
- MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ = (1U << 7),
- };
- enum {
- MEMBARRIER_FLAG_SYNC_CORE = (1U << 0),
- MEMBARRIER_FLAG_RSEQ = (1U << 1),
- };
- #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();
- }
- extern void membarrier_exec_mmap(struct mm_struct *mm);
- #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_exec_mmap(struct mm_struct *mm)
- {
- }
- static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
- {
- }
- #endif
- #endif /* _LINUX_SCHED_MM_H */
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