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)))
53 * This has to be called after a get_task_mm()/mmget_not_zero()
54 * followed by taking the mmap_sem for writing before modifying the
55 * vmas or anything the coredump pretends not to change from under it.
57 * It also has to be called when mmgrab() is used in the context of
58 * the process, but then the mm_count refcount is transferred outside
59 * the context of the process to run down_write() on that pinned mm.
61 * NOTE: find_extend_vma() called from GUP context is the only place
62 * that can modify the "mm" (notably the vm_start/end) under mmap_sem
63 * for reading and outside the context of the process, so it is also
64 * the only case that holds the mmap_sem for reading that must call
65 * this function. Generally if the mmap_sem is hold for reading
66 * there's no need of this check after get_task_mm()/mmget_not_zero().
68 * This function can be obsoleted and the check can be removed, after
69 * the coredump code will hold the mmap_sem for writing before
70 * invoking the ->core_dump methods.
72 static inline bool mmget_still_valid(struct mm_struct *mm)
74 return likely(!mm->core_state);
78 * mmget() - Pin the address space associated with a &struct mm_struct.
79 * @mm: The address space to pin.
81 * Make sure that the address space of the given &struct mm_struct doesn't
82 * go away. This does not protect against parts of the address space being
83 * modified or freed, however.
85 * Never use this function to pin this address space for an
86 * unbounded/indefinite amount of time.
88 * Use mmput() to release the reference acquired by mmget().
90 * See also <Documentation/vm/active_mm.rst> for an in-depth explanation
91 * of &mm_struct.mm_count vs &mm_struct.mm_users.
93 static inline void mmget(struct mm_struct *mm)
95 atomic_inc(&mm->mm_users);
98 static inline bool mmget_not_zero(struct mm_struct *mm)
100 return atomic_inc_not_zero(&mm->mm_users);
103 /* mmput gets rid of the mappings and all user-space */
104 extern void mmput(struct mm_struct *);
106 /* same as above but performs the slow path from the async context. Can
107 * be called from the atomic context as well
109 void mmput_async(struct mm_struct *);
112 /* Grab a reference to a task's mm, if it is not already going away */
113 extern struct mm_struct *get_task_mm(struct task_struct *task);
115 * Grab a reference to a task's mm, if it is not already going away
116 * and ptrace_may_access with the mode parameter passed to it
119 extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
120 /* Remove the current tasks stale references to the old mm_struct */
121 extern void mm_release(struct task_struct *, struct mm_struct *);
124 extern void mm_update_next_owner(struct mm_struct *mm);
126 static inline void mm_update_next_owner(struct mm_struct *mm)
129 #endif /* CONFIG_MEMCG */
132 extern void arch_pick_mmap_layout(struct mm_struct *mm,
133 struct rlimit *rlim_stack);
135 arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
136 unsigned long, unsigned long);
138 arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
139 unsigned long len, unsigned long pgoff,
140 unsigned long flags);
142 static inline void arch_pick_mmap_layout(struct mm_struct *mm,
143 struct rlimit *rlim_stack) {}
146 static inline bool in_vfork(struct task_struct *tsk)
151 * need RCU to access ->real_parent if CLONE_VM was used along with
154 * We check real_parent->mm == tsk->mm because CLONE_VFORK does not
157 * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus
158 * ->real_parent is not necessarily the task doing vfork(), so in
159 * theory we can't rely on task_lock() if we want to dereference it.
161 * And in this case we can't trust the real_parent->mm == tsk->mm
162 * check, it can be false negative. But we do not care, if init or
163 * another oom-unkillable task does this it should blame itself.
166 ret = tsk->vfork_done && tsk->real_parent->mm == tsk->mm;
173 * Applies per-task gfp context to the given allocation flags.
174 * PF_MEMALLOC_NOIO implies GFP_NOIO
175 * PF_MEMALLOC_NOFS implies GFP_NOFS
176 * PF_MEMALLOC_NOCMA implies no allocation from CMA region.
178 static inline gfp_t current_gfp_context(gfp_t flags)
180 if (unlikely(current->flags &
181 (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS | PF_MEMALLOC_NOCMA))) {
183 * NOIO implies both NOIO and NOFS and it is a weaker context
184 * so always make sure it makes precedence
186 if (current->flags & PF_MEMALLOC_NOIO)
187 flags &= ~(__GFP_IO | __GFP_FS);
188 else if (current->flags & PF_MEMALLOC_NOFS)
191 if (current->flags & PF_MEMALLOC_NOCMA)
192 flags &= ~__GFP_MOVABLE;
198 #ifdef CONFIG_LOCKDEP
199 extern void __fs_reclaim_acquire(void);
200 extern void __fs_reclaim_release(void);
201 extern void fs_reclaim_acquire(gfp_t gfp_mask);
202 extern void fs_reclaim_release(gfp_t gfp_mask);
204 static inline void __fs_reclaim_acquire(void) { }
205 static inline void __fs_reclaim_release(void) { }
206 static inline void fs_reclaim_acquire(gfp_t gfp_mask) { }
207 static inline void fs_reclaim_release(gfp_t gfp_mask) { }
211 * memalloc_noio_save - Marks implicit GFP_NOIO allocation scope.
213 * This functions marks the beginning of the GFP_NOIO allocation scope.
214 * All further allocations will implicitly drop __GFP_IO flag and so
215 * they are safe for the IO critical section from the allocation recursion
216 * point of view. Use memalloc_noio_restore to end the scope with flags
217 * returned by this function.
219 * This function is safe to be used from any context.
221 static inline unsigned int memalloc_noio_save(void)
223 unsigned int flags = current->flags & PF_MEMALLOC_NOIO;
224 current->flags |= PF_MEMALLOC_NOIO;
229 * memalloc_noio_restore - Ends the implicit GFP_NOIO scope.
230 * @flags: Flags to restore.
232 * Ends the implicit GFP_NOIO scope started by memalloc_noio_save function.
233 * Always make sure that that the given flags is the return value from the
234 * pairing memalloc_noio_save call.
236 static inline void memalloc_noio_restore(unsigned int flags)
238 current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
242 * memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope.
244 * This functions marks the beginning of the GFP_NOFS allocation scope.
245 * All further allocations will implicitly drop __GFP_FS flag and so
246 * they are safe for the FS critical section from the allocation recursion
247 * point of view. Use memalloc_nofs_restore to end the scope with flags
248 * returned by this function.
250 * This function is safe to be used from any context.
252 static inline unsigned int memalloc_nofs_save(void)
254 unsigned int flags = current->flags & PF_MEMALLOC_NOFS;
255 current->flags |= PF_MEMALLOC_NOFS;
260 * memalloc_nofs_restore - Ends the implicit GFP_NOFS scope.
261 * @flags: Flags to restore.
263 * Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function.
264 * Always make sure that that the given flags is the return value from the
265 * pairing memalloc_nofs_save call.
267 static inline void memalloc_nofs_restore(unsigned int flags)
269 current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags;
272 static inline unsigned int memalloc_noreclaim_save(void)
274 unsigned int flags = current->flags & PF_MEMALLOC;
275 current->flags |= PF_MEMALLOC;
279 static inline void memalloc_noreclaim_restore(unsigned int flags)
281 current->flags = (current->flags & ~PF_MEMALLOC) | flags;
285 static inline unsigned int memalloc_nocma_save(void)
287 unsigned int flags = current->flags & PF_MEMALLOC_NOCMA;
289 current->flags |= PF_MEMALLOC_NOCMA;
293 static inline void memalloc_nocma_restore(unsigned int flags)
295 current->flags = (current->flags & ~PF_MEMALLOC_NOCMA) | flags;
298 static inline unsigned int memalloc_nocma_save(void)
303 static inline void memalloc_nocma_restore(unsigned int flags)
310 * memalloc_use_memcg - Starts the remote memcg charging scope.
311 * @memcg: memcg to charge.
313 * This function marks the beginning of the remote memcg charging scope. All the
314 * __GFP_ACCOUNT allocations till the end of the scope will be charged to the
317 * NOTE: This function is not nesting safe.
319 static inline void memalloc_use_memcg(struct mem_cgroup *memcg)
321 WARN_ON_ONCE(current->active_memcg);
322 current->active_memcg = memcg;
326 * memalloc_unuse_memcg - Ends the remote memcg charging scope.
328 * This function marks the end of the remote memcg charging scope started by
329 * memalloc_use_memcg().
331 static inline void memalloc_unuse_memcg(void)
333 current->active_memcg = NULL;
336 static inline void memalloc_use_memcg(struct mem_cgroup *memcg)
340 static inline void memalloc_unuse_memcg(void)
345 #ifdef CONFIG_MEMBARRIER
347 MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0),
348 MEMBARRIER_STATE_PRIVATE_EXPEDITED = (1U << 1),
349 MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY = (1U << 2),
350 MEMBARRIER_STATE_GLOBAL_EXPEDITED = (1U << 3),
351 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY = (1U << 4),
352 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE = (1U << 5),
356 MEMBARRIER_FLAG_SYNC_CORE = (1U << 0),
359 #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
360 #include <asm/membarrier.h>
363 static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
365 if (current->mm != mm)
367 if (likely(!(atomic_read(&mm->membarrier_state) &
368 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE)))
370 sync_core_before_usermode();
373 extern void membarrier_exec_mmap(struct mm_struct *mm);
376 #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
377 static inline void membarrier_arch_switch_mm(struct mm_struct *prev,
378 struct mm_struct *next,
379 struct task_struct *tsk)
383 static inline void membarrier_exec_mmap(struct mm_struct *mm)
386 static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
391 #endif /* _LINUX_SCHED_MM_H */