1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SCHED_MM_H
3 #define _LINUX_SCHED_MM_H
5 #include <linux/kernel.h>
6 #include <linux/atomic.h>
7 #include <linux/sched.h>
8 #include <linux/mm_types.h>
10 #include <linux/sync_core.h>
13 * Routines for handling mm_structs
15 extern struct mm_struct *mm_alloc(void);
18 * mmgrab() - Pin a &struct mm_struct.
19 * @mm: The &struct mm_struct to pin.
21 * Make sure that @mm will not get freed even after the owning task
22 * exits. This doesn't guarantee that the associated address space
23 * will still exist later on and mmget_not_zero() has to be used before
26 * This is a preferred way to to pin @mm for a longer/unbounded amount
29 * Use mmdrop() to release the reference acquired by mmgrab().
31 * See also <Documentation/vm/active_mm.rst> for an in-depth explanation
32 * of &mm_struct.mm_count vs &mm_struct.mm_users.
34 static inline void mmgrab(struct mm_struct *mm)
36 atomic_inc(&mm->mm_count);
39 extern void __mmdrop(struct mm_struct *mm);
41 static inline void mmdrop(struct mm_struct *mm)
44 * The implicit full barrier implied by atomic_dec_and_test() is
45 * required by the membarrier system call before returning to
46 * user-space, after storing to rq->curr.
48 if (unlikely(atomic_dec_and_test(&mm->mm_count)))
52 void mmdrop(struct mm_struct *mm);
55 * This has to be called after a get_task_mm()/mmget_not_zero()
56 * followed by taking the mmap_sem for writing before modifying the
57 * vmas or anything the coredump pretends not to change from under it.
59 * It also has to be called when mmgrab() is used in the context of
60 * the process, but then the mm_count refcount is transferred outside
61 * the context of the process to run down_write() on that pinned mm.
63 * NOTE: find_extend_vma() called from GUP context is the only place
64 * that can modify the "mm" (notably the vm_start/end) under mmap_sem
65 * for reading and outside the context of the process, so it is also
66 * the only case that holds the mmap_sem for reading that must call
67 * this function. Generally if the mmap_sem is hold for reading
68 * there's no need of this check after get_task_mm()/mmget_not_zero().
70 * This function can be obsoleted and the check can be removed, after
71 * the coredump code will hold the mmap_sem for writing before
72 * invoking the ->core_dump methods.
74 static inline bool mmget_still_valid(struct mm_struct *mm)
76 return likely(!mm->core_state);
80 * mmget() - Pin the address space associated with a &struct mm_struct.
81 * @mm: The address space to pin.
83 * Make sure that the address space of the given &struct mm_struct doesn't
84 * go away. This does not protect against parts of the address space being
85 * modified or freed, however.
87 * Never use this function to pin this address space for an
88 * unbounded/indefinite amount of time.
90 * Use mmput() to release the reference acquired by mmget().
92 * See also <Documentation/vm/active_mm.rst> for an in-depth explanation
93 * of &mm_struct.mm_count vs &mm_struct.mm_users.
95 static inline void mmget(struct mm_struct *mm)
97 atomic_inc(&mm->mm_users);
100 static inline bool mmget_not_zero(struct mm_struct *mm)
102 return atomic_inc_not_zero(&mm->mm_users);
105 /* mmput gets rid of the mappings and all user-space */
106 extern void mmput(struct mm_struct *);
108 /* same as above but performs the slow path from the async context. Can
109 * be called from the atomic context as well
111 void mmput_async(struct mm_struct *);
114 /* Grab a reference to a task's mm, if it is not already going away */
115 extern struct mm_struct *get_task_mm(struct task_struct *task);
117 * Grab a reference to a task's mm, if it is not already going away
118 * and ptrace_may_access with the mode parameter passed to it
121 extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
122 /* Remove the current tasks stale references to the old mm_struct on exit() */
123 extern void exit_mm_release(struct task_struct *, struct mm_struct *);
124 /* Remove the current tasks stale references to the old mm_struct on exec() */
125 extern void exec_mm_release(struct task_struct *, struct mm_struct *);
128 extern void mm_update_next_owner(struct mm_struct *mm);
130 static inline void mm_update_next_owner(struct mm_struct *mm)
133 #endif /* CONFIG_MEMCG */
136 #ifndef arch_get_mmap_end
137 #define arch_get_mmap_end(addr) (TASK_SIZE)
140 #ifndef arch_get_mmap_base
141 #define arch_get_mmap_base(addr, base) (base)
144 extern void arch_pick_mmap_layout(struct mm_struct *mm,
145 struct rlimit *rlim_stack);
147 arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
148 unsigned long, unsigned long);
150 arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
151 unsigned long len, unsigned long pgoff,
152 unsigned long flags);
154 static inline void arch_pick_mmap_layout(struct mm_struct *mm,
155 struct rlimit *rlim_stack) {}
158 static inline bool in_vfork(struct task_struct *tsk)
163 * need RCU to access ->real_parent if CLONE_VM was used along with
166 * We check real_parent->mm == tsk->mm because CLONE_VFORK does not
169 * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus
170 * ->real_parent is not necessarily the task doing vfork(), so in
171 * theory we can't rely on task_lock() if we want to dereference it.
173 * And in this case we can't trust the real_parent->mm == tsk->mm
174 * check, it can be false negative. But we do not care, if init or
175 * another oom-unkillable task does this it should blame itself.
178 ret = tsk->vfork_done &&
179 rcu_dereference(tsk->real_parent)->mm == tsk->mm;
186 * Applies per-task gfp context to the given allocation flags.
187 * PF_MEMALLOC_NOIO implies GFP_NOIO
188 * PF_MEMALLOC_NOFS implies GFP_NOFS
189 * PF_MEMALLOC_NOCMA implies no allocation from CMA region.
191 static inline gfp_t current_gfp_context(gfp_t flags)
193 if (unlikely(current->flags &
194 (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS | PF_MEMALLOC_NOCMA))) {
196 * NOIO implies both NOIO and NOFS and it is a weaker context
197 * so always make sure it makes precedence
199 if (current->flags & PF_MEMALLOC_NOIO)
200 flags &= ~(__GFP_IO | __GFP_FS);
201 else if (current->flags & PF_MEMALLOC_NOFS)
204 if (current->flags & PF_MEMALLOC_NOCMA)
205 flags &= ~__GFP_MOVABLE;
211 #ifdef CONFIG_LOCKDEP
212 extern void __fs_reclaim_acquire(void);
213 extern void __fs_reclaim_release(void);
214 extern void fs_reclaim_acquire(gfp_t gfp_mask);
215 extern void fs_reclaim_release(gfp_t gfp_mask);
217 static inline void __fs_reclaim_acquire(void) { }
218 static inline void __fs_reclaim_release(void) { }
219 static inline void fs_reclaim_acquire(gfp_t gfp_mask) { }
220 static inline void fs_reclaim_release(gfp_t gfp_mask) { }
224 * memalloc_noio_save - Marks implicit GFP_NOIO allocation scope.
226 * This functions marks the beginning of the GFP_NOIO allocation scope.
227 * All further allocations will implicitly drop __GFP_IO flag and so
228 * they are safe for the IO critical section from the allocation recursion
229 * point of view. Use memalloc_noio_restore to end the scope with flags
230 * returned by this function.
232 * This function is safe to be used from any context.
234 static inline unsigned int memalloc_noio_save(void)
236 unsigned int flags = current->flags & PF_MEMALLOC_NOIO;
237 current->flags |= PF_MEMALLOC_NOIO;
242 * memalloc_noio_restore - Ends the implicit GFP_NOIO scope.
243 * @flags: Flags to restore.
245 * Ends the implicit GFP_NOIO scope started by memalloc_noio_save function.
246 * Always make sure that that the given flags is the return value from the
247 * pairing memalloc_noio_save call.
249 static inline void memalloc_noio_restore(unsigned int flags)
251 current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
255 * memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope.
257 * This functions marks the beginning of the GFP_NOFS allocation scope.
258 * All further allocations will implicitly drop __GFP_FS flag and so
259 * they are safe for the FS critical section from the allocation recursion
260 * point of view. Use memalloc_nofs_restore to end the scope with flags
261 * returned by this function.
263 * This function is safe to be used from any context.
265 static inline unsigned int memalloc_nofs_save(void)
267 unsigned int flags = current->flags & PF_MEMALLOC_NOFS;
268 current->flags |= PF_MEMALLOC_NOFS;
273 * memalloc_nofs_restore - Ends the implicit GFP_NOFS scope.
274 * @flags: Flags to restore.
276 * Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function.
277 * Always make sure that that the given flags is the return value from the
278 * pairing memalloc_nofs_save call.
280 static inline void memalloc_nofs_restore(unsigned int flags)
282 current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags;
285 static inline unsigned int memalloc_noreclaim_save(void)
287 unsigned int flags = current->flags & PF_MEMALLOC;
288 current->flags |= PF_MEMALLOC;
292 static inline void memalloc_noreclaim_restore(unsigned int flags)
294 current->flags = (current->flags & ~PF_MEMALLOC) | flags;
298 static inline unsigned int memalloc_nocma_save(void)
300 unsigned int flags = current->flags & PF_MEMALLOC_NOCMA;
302 current->flags |= PF_MEMALLOC_NOCMA;
306 static inline void memalloc_nocma_restore(unsigned int flags)
308 current->flags = (current->flags & ~PF_MEMALLOC_NOCMA) | flags;
311 static inline unsigned int memalloc_nocma_save(void)
316 static inline void memalloc_nocma_restore(unsigned int flags)
323 * memalloc_use_memcg - Starts the remote memcg charging scope.
324 * @memcg: memcg to charge.
326 * This function marks the beginning of the remote memcg charging scope. All the
327 * __GFP_ACCOUNT allocations till the end of the scope will be charged to the
330 * NOTE: This function is not nesting safe.
332 static inline void memalloc_use_memcg(struct mem_cgroup *memcg)
334 WARN_ON_ONCE(current->active_memcg);
335 current->active_memcg = memcg;
339 * memalloc_unuse_memcg - Ends the remote memcg charging scope.
341 * This function marks the end of the remote memcg charging scope started by
342 * memalloc_use_memcg().
344 static inline void memalloc_unuse_memcg(void)
346 current->active_memcg = NULL;
349 static inline void memalloc_use_memcg(struct mem_cgroup *memcg)
353 static inline void memalloc_unuse_memcg(void)
358 #ifdef CONFIG_MEMBARRIER
360 MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0),
361 MEMBARRIER_STATE_PRIVATE_EXPEDITED = (1U << 1),
362 MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY = (1U << 2),
363 MEMBARRIER_STATE_GLOBAL_EXPEDITED = (1U << 3),
364 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY = (1U << 4),
365 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE = (1U << 5),
369 MEMBARRIER_FLAG_SYNC_CORE = (1U << 0),
372 #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
373 #include <asm/membarrier.h>
376 static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
378 if (current->mm != mm)
380 if (likely(!(atomic_read(&mm->membarrier_state) &
381 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE)))
383 sync_core_before_usermode();
386 extern void membarrier_exec_mmap(struct mm_struct *mm);
389 #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
390 static inline void membarrier_arch_switch_mm(struct mm_struct *prev,
391 struct mm_struct *next,
392 struct task_struct *tsk)
396 static inline void membarrier_exec_mmap(struct mm_struct *mm)
399 static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
404 #endif /* _LINUX_SCHED_MM_H */