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>
11 #include <linux/ioasid.h>
14 * Routines for handling mm_structs
16 extern struct mm_struct *mm_alloc(void);
19 * mmgrab() - Pin a &struct mm_struct.
20 * @mm: The &struct mm_struct to pin.
22 * Make sure that @mm will not get freed even after the owning task
23 * exits. This doesn't guarantee that the associated address space
24 * will still exist later on and mmget_not_zero() has to be used before
27 * This is a preferred way to pin @mm for a longer/unbounded amount
30 * Use mmdrop() to release the reference acquired by mmgrab().
32 * See also <Documentation/vm/active_mm.rst> for an in-depth explanation
33 * of &mm_struct.mm_count vs &mm_struct.mm_users.
35 static inline void mmgrab(struct mm_struct *mm)
37 atomic_inc(&mm->mm_count);
40 extern void __mmdrop(struct mm_struct *mm);
42 static inline void mmdrop(struct mm_struct *mm)
45 * The implicit full barrier implied by atomic_dec_and_test() is
46 * required by the membarrier system call before returning to
47 * user-space, after storing to rq->curr.
49 if (unlikely(atomic_dec_and_test(&mm->mm_count)))
53 #ifdef CONFIG_PREEMPT_RT
55 * RCU callback for delayed mm drop. Not strictly RCU, but call_rcu() is
56 * by far the least expensive way to do that.
58 static inline void __mmdrop_delayed(struct rcu_head *rhp)
60 struct mm_struct *mm = container_of(rhp, struct mm_struct, delayed_drop);
66 * Invoked from finish_task_switch(). Delegates the heavy lifting on RT
69 static inline void mmdrop_sched(struct mm_struct *mm)
71 /* Provides a full memory barrier. See mmdrop() */
72 if (atomic_dec_and_test(&mm->mm_count))
73 call_rcu(&mm->delayed_drop, __mmdrop_delayed);
76 static inline void mmdrop_sched(struct mm_struct *mm)
83 * mmget() - Pin the address space associated with a &struct mm_struct.
84 * @mm: The address space to pin.
86 * Make sure that the address space of the given &struct mm_struct doesn't
87 * go away. This does not protect against parts of the address space being
88 * modified or freed, however.
90 * Never use this function to pin this address space for an
91 * unbounded/indefinite amount of time.
93 * Use mmput() to release the reference acquired by mmget().
95 * See also <Documentation/vm/active_mm.rst> for an in-depth explanation
96 * of &mm_struct.mm_count vs &mm_struct.mm_users.
98 static inline void mmget(struct mm_struct *mm)
100 atomic_inc(&mm->mm_users);
103 static inline bool mmget_not_zero(struct mm_struct *mm)
105 return atomic_inc_not_zero(&mm->mm_users);
108 /* mmput gets rid of the mappings and all user-space */
109 extern void mmput(struct mm_struct *);
111 /* same as above but performs the slow path from the async context. Can
112 * be called from the atomic context as well
114 void mmput_async(struct mm_struct *);
117 /* Grab a reference to a task's mm, if it is not already going away */
118 extern struct mm_struct *get_task_mm(struct task_struct *task);
120 * Grab a reference to a task's mm, if it is not already going away
121 * and ptrace_may_access with the mode parameter passed to it
124 extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
125 /* Remove the current tasks stale references to the old mm_struct on exit() */
126 extern void exit_mm_release(struct task_struct *, struct mm_struct *);
127 /* Remove the current tasks stale references to the old mm_struct on exec() */
128 extern void exec_mm_release(struct task_struct *, struct mm_struct *);
131 extern void mm_update_next_owner(struct mm_struct *mm);
133 static inline void mm_update_next_owner(struct mm_struct *mm)
136 #endif /* CONFIG_MEMCG */
139 #ifndef arch_get_mmap_end
140 #define arch_get_mmap_end(addr) (TASK_SIZE)
143 #ifndef arch_get_mmap_base
144 #define arch_get_mmap_base(addr, base) (base)
147 extern void arch_pick_mmap_layout(struct mm_struct *mm,
148 struct rlimit *rlim_stack);
150 arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
151 unsigned long, unsigned long);
153 arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
154 unsigned long len, unsigned long pgoff,
155 unsigned long flags);
157 static inline void arch_pick_mmap_layout(struct mm_struct *mm,
158 struct rlimit *rlim_stack) {}
161 static inline bool in_vfork(struct task_struct *tsk)
166 * need RCU to access ->real_parent if CLONE_VM was used along with
169 * We check real_parent->mm == tsk->mm because CLONE_VFORK does not
172 * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus
173 * ->real_parent is not necessarily the task doing vfork(), so in
174 * theory we can't rely on task_lock() if we want to dereference it.
176 * And in this case we can't trust the real_parent->mm == tsk->mm
177 * check, it can be false negative. But we do not care, if init or
178 * another oom-unkillable task does this it should blame itself.
181 ret = tsk->vfork_done &&
182 rcu_dereference(tsk->real_parent)->mm == tsk->mm;
189 * Applies per-task gfp context to the given allocation flags.
190 * PF_MEMALLOC_NOIO implies GFP_NOIO
191 * PF_MEMALLOC_NOFS implies GFP_NOFS
192 * PF_MEMALLOC_PIN implies !GFP_MOVABLE
194 static inline gfp_t current_gfp_context(gfp_t flags)
196 unsigned int pflags = READ_ONCE(current->flags);
198 if (unlikely(pflags & (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS | PF_MEMALLOC_PIN))) {
200 * NOIO implies both NOIO and NOFS and it is a weaker context
201 * so always make sure it makes precedence
203 if (pflags & PF_MEMALLOC_NOIO)
204 flags &= ~(__GFP_IO | __GFP_FS);
205 else if (pflags & PF_MEMALLOC_NOFS)
208 if (pflags & PF_MEMALLOC_PIN)
209 flags &= ~__GFP_MOVABLE;
214 #ifdef CONFIG_LOCKDEP
215 extern void __fs_reclaim_acquire(unsigned long ip);
216 extern void __fs_reclaim_release(unsigned long ip);
217 extern void fs_reclaim_acquire(gfp_t gfp_mask);
218 extern void fs_reclaim_release(gfp_t gfp_mask);
220 static inline void __fs_reclaim_acquire(unsigned long ip) { }
221 static inline void __fs_reclaim_release(unsigned long ip) { }
222 static inline void fs_reclaim_acquire(gfp_t gfp_mask) { }
223 static inline void fs_reclaim_release(gfp_t gfp_mask) { }
226 /* Any memory-allocation retry loop should use
227 * memalloc_retry_wait(), and pass the flags for the most
228 * constrained allocation attempt that might have failed.
229 * This provides useful documentation of where loops are,
230 * and a central place to fine tune the waiting as the MM
231 * implementation changes.
233 static inline void memalloc_retry_wait(gfp_t gfp_flags)
235 /* We use io_schedule_timeout because waiting for memory
236 * typically included waiting for dirty pages to be
237 * written out, which requires IO.
239 __set_current_state(TASK_UNINTERRUPTIBLE);
240 gfp_flags = current_gfp_context(gfp_flags);
241 if (gfpflags_allow_blocking(gfp_flags) &&
242 !(gfp_flags & __GFP_NORETRY))
243 /* Probably waited already, no need for much more */
244 io_schedule_timeout(1);
246 /* Probably didn't wait, and has now released a lock,
247 * so now is a good time to wait
249 io_schedule_timeout(HZ/50);
253 * might_alloc - Mark possible allocation sites
254 * @gfp_mask: gfp_t flags that would be used to allocate
256 * Similar to might_sleep() and other annotations, this can be used in functions
257 * that might allocate, but often don't. Compiles to nothing without
258 * CONFIG_LOCKDEP. Includes a conditional might_sleep() if @gfp allows blocking.
260 static inline void might_alloc(gfp_t gfp_mask)
262 fs_reclaim_acquire(gfp_mask);
263 fs_reclaim_release(gfp_mask);
265 might_sleep_if(gfpflags_allow_blocking(gfp_mask));
269 * memalloc_noio_save - Marks implicit GFP_NOIO allocation scope.
271 * This functions marks the beginning of the GFP_NOIO allocation scope.
272 * All further allocations will implicitly drop __GFP_IO flag and so
273 * they are safe for the IO critical section from the allocation recursion
274 * point of view. Use memalloc_noio_restore to end the scope with flags
275 * returned by this function.
277 * This function is safe to be used from any context.
279 static inline unsigned int memalloc_noio_save(void)
281 unsigned int flags = current->flags & PF_MEMALLOC_NOIO;
282 current->flags |= PF_MEMALLOC_NOIO;
287 * memalloc_noio_restore - Ends the implicit GFP_NOIO scope.
288 * @flags: Flags to restore.
290 * Ends the implicit GFP_NOIO scope started by memalloc_noio_save function.
291 * Always make sure that the given flags is the return value from the
292 * pairing memalloc_noio_save call.
294 static inline void memalloc_noio_restore(unsigned int flags)
296 current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
300 * memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope.
302 * This functions marks the beginning of the GFP_NOFS allocation scope.
303 * All further allocations will implicitly drop __GFP_FS flag and so
304 * they are safe for the FS critical section from the allocation recursion
305 * point of view. Use memalloc_nofs_restore to end the scope with flags
306 * returned by this function.
308 * This function is safe to be used from any context.
310 static inline unsigned int memalloc_nofs_save(void)
312 unsigned int flags = current->flags & PF_MEMALLOC_NOFS;
313 current->flags |= PF_MEMALLOC_NOFS;
318 * memalloc_nofs_restore - Ends the implicit GFP_NOFS scope.
319 * @flags: Flags to restore.
321 * Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function.
322 * Always make sure that the given flags is the return value from the
323 * pairing memalloc_nofs_save call.
325 static inline void memalloc_nofs_restore(unsigned int flags)
327 current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags;
330 static inline unsigned int memalloc_noreclaim_save(void)
332 unsigned int flags = current->flags & PF_MEMALLOC;
333 current->flags |= PF_MEMALLOC;
337 static inline void memalloc_noreclaim_restore(unsigned int flags)
339 current->flags = (current->flags & ~PF_MEMALLOC) | flags;
342 static inline unsigned int memalloc_pin_save(void)
344 unsigned int flags = current->flags & PF_MEMALLOC_PIN;
346 current->flags |= PF_MEMALLOC_PIN;
350 static inline void memalloc_pin_restore(unsigned int flags)
352 current->flags = (current->flags & ~PF_MEMALLOC_PIN) | flags;
356 DECLARE_PER_CPU(struct mem_cgroup *, int_active_memcg);
358 * set_active_memcg - Starts the remote memcg charging scope.
359 * @memcg: memcg to charge.
361 * This function marks the beginning of the remote memcg charging scope. All the
362 * __GFP_ACCOUNT allocations till the end of the scope will be charged to the
365 * NOTE: This function can nest. Users must save the return value and
366 * reset the previous value after their own charging scope is over.
368 static inline struct mem_cgroup *
369 set_active_memcg(struct mem_cgroup *memcg)
371 struct mem_cgroup *old;
374 old = this_cpu_read(int_active_memcg);
375 this_cpu_write(int_active_memcg, memcg);
377 old = current->active_memcg;
378 current->active_memcg = memcg;
384 static inline struct mem_cgroup *
385 set_active_memcg(struct mem_cgroup *memcg)
391 #ifdef CONFIG_MEMBARRIER
393 MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0),
394 MEMBARRIER_STATE_PRIVATE_EXPEDITED = (1U << 1),
395 MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY = (1U << 2),
396 MEMBARRIER_STATE_GLOBAL_EXPEDITED = (1U << 3),
397 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY = (1U << 4),
398 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE = (1U << 5),
399 MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ_READY = (1U << 6),
400 MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ = (1U << 7),
404 MEMBARRIER_FLAG_SYNC_CORE = (1U << 0),
405 MEMBARRIER_FLAG_RSEQ = (1U << 1),
408 #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
409 #include <asm/membarrier.h>
412 static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
414 if (current->mm != mm)
416 if (likely(!(atomic_read(&mm->membarrier_state) &
417 MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE)))
419 sync_core_before_usermode();
422 extern void membarrier_exec_mmap(struct mm_struct *mm);
424 extern void membarrier_update_current_mm(struct mm_struct *next_mm);
427 #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
428 static inline void membarrier_arch_switch_mm(struct mm_struct *prev,
429 struct mm_struct *next,
430 struct task_struct *tsk)
434 static inline void membarrier_exec_mmap(struct mm_struct *mm)
437 static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
440 static inline void membarrier_update_current_mm(struct mm_struct *next_mm)
445 #ifdef CONFIG_IOMMU_SVA
446 static inline void mm_pasid_init(struct mm_struct *mm)
448 mm->pasid = INVALID_IOASID;
451 /* Associate a PASID with an mm_struct: */
452 static inline void mm_pasid_set(struct mm_struct *mm, u32 pasid)
457 static inline void mm_pasid_drop(struct mm_struct *mm)
459 if (pasid_valid(mm->pasid)) {
460 ioasid_free(mm->pasid);
461 mm->pasid = INVALID_IOASID;
465 static inline void mm_pasid_init(struct mm_struct *mm) {}
466 static inline void mm_pasid_set(struct mm_struct *mm, u32 pasid) {}
467 static inline void mm_pasid_drop(struct mm_struct *mm) {}
470 #endif /* _LINUX_SCHED_MM_H */