Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0 */
2 : #ifndef _LINUX_SCHED_MM_H
3 : #define _LINUX_SCHED_MM_H
4 :
5 : #include <linux/kernel.h>
6 : #include <linux/atomic.h>
7 : #include <linux/sched.h>
8 : #include <linux/mm_types.h>
9 : #include <linux/gfp.h>
10 : #include <linux/sync_core.h>
11 : #include <linux/ioasid.h>
12 :
13 : /*
14 : * Routines for handling mm_structs
15 : */
16 : extern struct mm_struct *mm_alloc(void);
17 :
18 : /**
19 : * mmgrab() - Pin a &struct mm_struct.
20 : * @mm: The &struct mm_struct to pin.
21 : *
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
25 : * accessing it.
26 : *
27 : * This is a preferred way to pin @mm for a longer/unbounded amount
28 : * of time.
29 : *
30 : * Use mmdrop() to release the reference acquired by mmgrab().
31 : *
32 : * See also <Documentation/vm/active_mm.rst> for an in-depth explanation
33 : * of &mm_struct.mm_count vs &mm_struct.mm_users.
34 : */
35 : static inline void mmgrab(struct mm_struct *mm)
36 : {
37 2 : atomic_inc(&mm->mm_count);
38 : }
39 :
40 : extern void __mmdrop(struct mm_struct *mm);
41 :
42 : static inline void mmdrop(struct mm_struct *mm)
43 : {
44 : /*
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.
48 : */
49 0 : if (unlikely(atomic_dec_and_test(&mm->mm_count)))
50 0 : __mmdrop(mm);
51 : }
52 :
53 : #ifdef CONFIG_PREEMPT_RT
54 : /*
55 : * RCU callback for delayed mm drop. Not strictly RCU, but call_rcu() is
56 : * by far the least expensive way to do that.
57 : */
58 : static inline void __mmdrop_delayed(struct rcu_head *rhp)
59 : {
60 : struct mm_struct *mm = container_of(rhp, struct mm_struct, delayed_drop);
61 :
62 : __mmdrop(mm);
63 : }
64 :
65 : /*
66 : * Invoked from finish_task_switch(). Delegates the heavy lifting on RT
67 : * kernels via RCU.
68 : */
69 : static inline void mmdrop_sched(struct mm_struct *mm)
70 : {
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);
74 : }
75 : #else
76 : static inline void mmdrop_sched(struct mm_struct *mm)
77 : {
78 : mmdrop(mm);
79 : }
80 : #endif
81 :
82 : /**
83 : * mmget() - Pin the address space associated with a &struct mm_struct.
84 : * @mm: The address space to pin.
85 : *
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.
89 : *
90 : * Never use this function to pin this address space for an
91 : * unbounded/indefinite amount of time.
92 : *
93 : * Use mmput() to release the reference acquired by mmget().
94 : *
95 : * See also <Documentation/vm/active_mm.rst> for an in-depth explanation
96 : * of &mm_struct.mm_count vs &mm_struct.mm_users.
97 : */
98 : static inline void mmget(struct mm_struct *mm)
99 : {
100 0 : atomic_inc(&mm->mm_users);
101 : }
102 :
103 : static inline bool mmget_not_zero(struct mm_struct *mm)
104 : {
105 0 : return atomic_inc_not_zero(&mm->mm_users);
106 : }
107 :
108 : /* mmput gets rid of the mappings and all user-space */
109 : extern void mmput(struct mm_struct *);
110 : #ifdef CONFIG_MMU
111 : /* same as above but performs the slow path from the async context. Can
112 : * be called from the atomic context as well
113 : */
114 : void mmput_async(struct mm_struct *);
115 : #endif
116 :
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);
119 : /*
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
122 : * succeeds.
123 : */
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 *);
129 :
130 : #ifdef CONFIG_MEMCG
131 : extern void mm_update_next_owner(struct mm_struct *mm);
132 : #else
133 : static inline void mm_update_next_owner(struct mm_struct *mm)
134 : {
135 : }
136 : #endif /* CONFIG_MEMCG */
137 :
138 : #ifdef CONFIG_MMU
139 : #ifndef arch_get_mmap_end
140 : #define arch_get_mmap_end(addr) (TASK_SIZE)
141 : #endif
142 :
143 : #ifndef arch_get_mmap_base
144 : #define arch_get_mmap_base(addr, base) (base)
145 : #endif
146 :
147 : extern void arch_pick_mmap_layout(struct mm_struct *mm,
148 : struct rlimit *rlim_stack);
149 : extern unsigned long
150 : arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
151 : unsigned long, unsigned long);
152 : extern 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);
156 : #else
157 : static inline void arch_pick_mmap_layout(struct mm_struct *mm,
158 : struct rlimit *rlim_stack) {}
159 : #endif
160 :
161 : static inline bool in_vfork(struct task_struct *tsk)
162 : {
163 : bool ret;
164 :
165 : /*
166 : * need RCU to access ->real_parent if CLONE_VM was used along with
167 : * CLONE_PARENT.
168 : *
169 : * We check real_parent->mm == tsk->mm because CLONE_VFORK does not
170 : * imply CLONE_VM
171 : *
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.
175 : *
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.
179 : */
180 : rcu_read_lock();
181 0 : ret = tsk->vfork_done &&
182 0 : rcu_dereference(tsk->real_parent)->mm == tsk->mm;
183 : rcu_read_unlock();
184 :
185 : return ret;
186 : }
187 :
188 : /*
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
193 : */
194 706 : static inline gfp_t current_gfp_context(gfp_t flags)
195 : {
196 706 : unsigned int pflags = READ_ONCE(current->flags);
197 :
198 706 : if (unlikely(pflags & (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS | PF_MEMALLOC_PIN))) {
199 : /*
200 : * NOIO implies both NOIO and NOFS and it is a weaker context
201 : * so always make sure it makes precedence
202 : */
203 0 : if (pflags & PF_MEMALLOC_NOIO)
204 0 : flags &= ~(__GFP_IO | __GFP_FS);
205 0 : else if (pflags & PF_MEMALLOC_NOFS)
206 0 : flags &= ~__GFP_FS;
207 :
208 0 : if (pflags & PF_MEMALLOC_PIN)
209 0 : flags &= ~__GFP_MOVABLE;
210 : }
211 706 : return flags;
212 : }
213 :
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);
219 : #else
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) { }
224 : #endif
225 :
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.
232 : */
233 : static inline void memalloc_retry_wait(gfp_t gfp_flags)
234 : {
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.
238 : */
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);
245 : else
246 : /* Probably didn't wait, and has now released a lock,
247 : * so now is a good time to wait
248 : */
249 : io_schedule_timeout(HZ/50);
250 : }
251 :
252 : /**
253 : * might_alloc - Mark possible allocation sites
254 : * @gfp_mask: gfp_t flags that would be used to allocate
255 : *
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.
259 : */
260 : static inline void might_alloc(gfp_t gfp_mask)
261 : {
262 18327 : fs_reclaim_acquire(gfp_mask);
263 18327 : fs_reclaim_release(gfp_mask);
264 :
265 18327 : might_sleep_if(gfpflags_allow_blocking(gfp_mask));
266 : }
267 :
268 : /**
269 : * memalloc_noio_save - Marks implicit GFP_NOIO allocation scope.
270 : *
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.
276 : *
277 : * This function is safe to be used from any context.
278 : */
279 : static inline unsigned int memalloc_noio_save(void)
280 : {
281 0 : unsigned int flags = current->flags & PF_MEMALLOC_NOIO;
282 0 : current->flags |= PF_MEMALLOC_NOIO;
283 : return flags;
284 : }
285 :
286 : /**
287 : * memalloc_noio_restore - Ends the implicit GFP_NOIO scope.
288 : * @flags: Flags to restore.
289 : *
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.
293 : */
294 : static inline void memalloc_noio_restore(unsigned int flags)
295 : {
296 0 : current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
297 : }
298 :
299 : /**
300 : * memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope.
301 : *
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.
307 : *
308 : * This function is safe to be used from any context.
309 : */
310 : static inline unsigned int memalloc_nofs_save(void)
311 : {
312 0 : unsigned int flags = current->flags & PF_MEMALLOC_NOFS;
313 0 : current->flags |= PF_MEMALLOC_NOFS;
314 : return flags;
315 : }
316 :
317 : /**
318 : * memalloc_nofs_restore - Ends the implicit GFP_NOFS scope.
319 : * @flags: Flags to restore.
320 : *
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.
324 : */
325 : static inline void memalloc_nofs_restore(unsigned int flags)
326 : {
327 0 : current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags;
328 : }
329 :
330 : static inline unsigned int memalloc_noreclaim_save(void)
331 : {
332 0 : unsigned int flags = current->flags & PF_MEMALLOC;
333 0 : current->flags |= PF_MEMALLOC;
334 : return flags;
335 : }
336 :
337 : static inline void memalloc_noreclaim_restore(unsigned int flags)
338 : {
339 0 : current->flags = (current->flags & ~PF_MEMALLOC) | flags;
340 : }
341 :
342 : static inline unsigned int memalloc_pin_save(void)
343 : {
344 0 : unsigned int flags = current->flags & PF_MEMALLOC_PIN;
345 :
346 0 : current->flags |= PF_MEMALLOC_PIN;
347 : return flags;
348 : }
349 :
350 : static inline void memalloc_pin_restore(unsigned int flags)
351 : {
352 0 : current->flags = (current->flags & ~PF_MEMALLOC_PIN) | flags;
353 : }
354 :
355 : #ifdef CONFIG_MEMCG
356 : DECLARE_PER_CPU(struct mem_cgroup *, int_active_memcg);
357 : /**
358 : * set_active_memcg - Starts the remote memcg charging scope.
359 : * @memcg: memcg to charge.
360 : *
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
363 : * given memcg.
364 : *
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.
367 : */
368 : static inline struct mem_cgroup *
369 : set_active_memcg(struct mem_cgroup *memcg)
370 : {
371 : struct mem_cgroup *old;
372 :
373 : if (!in_task()) {
374 : old = this_cpu_read(int_active_memcg);
375 : this_cpu_write(int_active_memcg, memcg);
376 : } else {
377 : old = current->active_memcg;
378 : current->active_memcg = memcg;
379 : }
380 :
381 : return old;
382 : }
383 : #else
384 : static inline struct mem_cgroup *
385 : set_active_memcg(struct mem_cgroup *memcg)
386 : {
387 : return NULL;
388 : }
389 : #endif
390 :
391 : #ifdef CONFIG_MEMBARRIER
392 : enum {
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),
401 : };
402 :
403 : enum {
404 : MEMBARRIER_FLAG_SYNC_CORE = (1U << 0),
405 : MEMBARRIER_FLAG_RSEQ = (1U << 1),
406 : };
407 :
408 : #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
409 : #include <asm/membarrier.h>
410 : #endif
411 :
412 : static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
413 : {
414 0 : if (current->mm != mm)
415 : return;
416 0 : if (likely(!(atomic_read(&mm->membarrier_state) &
417 : MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE)))
418 : return;
419 : sync_core_before_usermode();
420 : }
421 :
422 : extern void membarrier_exec_mmap(struct mm_struct *mm);
423 :
424 : extern void membarrier_update_current_mm(struct mm_struct *next_mm);
425 :
426 : #else
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)
431 : {
432 : }
433 : #endif
434 : static inline void membarrier_exec_mmap(struct mm_struct *mm)
435 : {
436 : }
437 : static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
438 : {
439 : }
440 : static inline void membarrier_update_current_mm(struct mm_struct *next_mm)
441 : {
442 : }
443 : #endif
444 :
445 : #ifdef CONFIG_IOMMU_SVA
446 : static inline void mm_pasid_init(struct mm_struct *mm)
447 : {
448 : mm->pasid = INVALID_IOASID;
449 : }
450 :
451 : /* Associate a PASID with an mm_struct: */
452 : static inline void mm_pasid_set(struct mm_struct *mm, u32 pasid)
453 : {
454 : mm->pasid = pasid;
455 : }
456 :
457 : static inline void mm_pasid_drop(struct mm_struct *mm)
458 : {
459 : if (pasid_valid(mm->pasid)) {
460 : ioasid_free(mm->pasid);
461 : mm->pasid = INVALID_IOASID;
462 : }
463 : }
464 : #else
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) {}
468 : #endif
469 :
470 : #endif /* _LINUX_SCHED_MM_H */
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