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 extern void arch_pick_mmap_layout(struct mm_struct *mm,
137 struct rlimit *rlim_stack);
139 arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
140 unsigned long, unsigned long);
142 arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
143 unsigned long len, unsigned long pgoff,
144 unsigned long flags);
146 static inline void arch_pick_mmap_layout(struct mm_struct *mm,
147 struct rlimit *rlim_stack) {}
150 static inline bool in_vfork(struct task_struct *tsk)
155 * need RCU to access ->real_parent if CLONE_VM was used along with
158 * We check real_parent->mm == tsk->mm because CLONE_VFORK does not
161 * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus
162 * ->real_parent is not necessarily the task doing vfork(), so in
163 * theory we can't rely on task_lock() if we want to dereference it.
165 * And in this case we can't trust the real_parent->mm == tsk->mm
166 * check, it can be false negative. But we do not care, if init or
167 * another oom-unkillable task does this it should blame itself.
170 ret = tsk->vfork_done &&
171 rcu_dereference(tsk->real_parent)->mm == tsk->mm;
178 * Applies per-task gfp context to the given allocation flags.
179 * PF_MEMALLOC_NOIO implies GFP_NOIO
180 * PF_MEMALLOC_NOFS implies GFP_NOFS
182 static inline gfp_t current_gfp_context(gfp_t flags)
185 * NOIO implies both NOIO and NOFS and it is a weaker context
186 * so always make sure it makes precendence
188 if (unlikely(current->flags & PF_MEMALLOC_NOIO))
189 flags &= ~(__GFP_IO | __GFP_FS);
190 else if (unlikely(current->flags & PF_MEMALLOC_NOFS))
195 #ifdef CONFIG_LOCKDEP
196 extern void __fs_reclaim_acquire(void);
197 extern void __fs_reclaim_release(void);
198 extern void fs_reclaim_acquire(gfp_t gfp_mask);
199 extern void fs_reclaim_release(gfp_t gfp_mask);
201 static inline void __fs_reclaim_acquire(void) { }
202 static inline void __fs_reclaim_release(void) { }
203 static inline void fs_reclaim_acquire(gfp_t gfp_mask) { }
204 static inline void fs_reclaim_release(gfp_t gfp_mask) { }
208 * memalloc_noio_save - Marks implicit GFP_NOIO allocation scope.
210 * This functions marks the beginning of the GFP_NOIO allocation scope.
211 * All further allocations will implicitly drop __GFP_IO flag and so
212 * they are safe for the IO critical section from the allocation recursion
213 * point of view. Use memalloc_noio_restore to end the scope with flags
214 * returned by this function.
216 * This function is safe to be used from any context.
218 static inline unsigned int memalloc_noio_save(void)
220 unsigned int flags = current->flags & PF_MEMALLOC_NOIO;
221 current->flags |= PF_MEMALLOC_NOIO;
226 * memalloc_noio_restore - Ends the implicit GFP_NOIO scope.
227 * @flags: Flags to restore.
229 * Ends the implicit GFP_NOIO scope started by memalloc_noio_save function.
230 * Always make sure that that the given flags is the return value from the
231 * pairing memalloc_noio_save call.
233 static inline void memalloc_noio_restore(unsigned int flags)
235 current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
239 * memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope.
241 * This functions marks the beginning of the GFP_NOFS allocation scope.
242 * All further allocations will implicitly drop __GFP_FS flag and so
243 * they are safe for the FS critical section from the allocation recursion
244 * point of view. Use memalloc_nofs_restore to end the scope with flags
245 * returned by this function.
247 * This function is safe to be used from any context.
249 static inline unsigned int memalloc_nofs_save(void)
251 unsigned int flags = current->flags & PF_MEMALLOC_NOFS;
252 current->flags |= PF_MEMALLOC_NOFS;
257 * memalloc_nofs_restore - Ends the implicit GFP_NOFS scope.
258 * @flags: Flags to restore.
260 * Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function.
261 * Always make sure that that the given flags is the return value from the
262 * pairing memalloc_nofs_save call.
264 static inline void memalloc_nofs_restore(unsigned int flags)
266 current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags;
269 static inline unsigned int memalloc_noreclaim_save(void)
271 unsigned int flags = current->flags & PF_MEMALLOC;
272 current->flags |= PF_MEMALLOC;
276 static inline void memalloc_noreclaim_restore(unsigned int flags)
278 current->flags = (current->flags & ~PF_MEMALLOC) | flags;
283 * memalloc_use_memcg - Starts the remote memcg charging scope.
284 * @memcg: memcg to charge.
286 * This function marks the beginning of the remote memcg charging scope. All the
287 * __GFP_ACCOUNT allocations till the end of the scope will be charged to the
290 * NOTE: This function is not nesting safe.
292 static inline void memalloc_use_memcg(struct mem_cgroup *memcg)
294 WARN_ON_ONCE(current->active_memcg);
295 current->active_memcg = memcg;
299 * memalloc_unuse_memcg - Ends the remote memcg charging scope.
301 * This function marks the end of the remote memcg charging scope started by
302 * memalloc_use_memcg().
304 static inline void memalloc_unuse_memcg(void)
306 current->active_memcg = NULL;
309 static inline void memalloc_use_memcg(struct mem_cgroup *memcg)
313 static inline void memalloc_unuse_memcg(void)
318 #ifdef CONFIG_MEMBARRIER
320 MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0),
321 MEMBARRIER_STATE_PRIVATE_EXPEDITED = (1U << 1),
322 MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY = (1U << 2),
323 MEMBARRIER_STATE_GLOBAL_EXPEDITED = (1U << 3),
324 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY = (1U << 4),
325 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE = (1U << 5),
329 MEMBARRIER_FLAG_SYNC_CORE = (1U << 0),
332 #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
333 #include <asm/membarrier.h>
336 static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
338 if (current->mm != mm)
340 if (likely(!(atomic_read(&mm->membarrier_state) &
341 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE)))
343 sync_core_before_usermode();
346 static inline void membarrier_execve(struct task_struct *t)
348 atomic_set(&t->mm->membarrier_state, 0);
351 #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
352 static inline void membarrier_arch_switch_mm(struct mm_struct *prev,
353 struct mm_struct *next,
354 struct task_struct *tsk)
358 static inline void membarrier_execve(struct task_struct *t)
361 static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
366 #endif /* _LINUX_SCHED_MM_H */