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/mm/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/mm/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, len, flags) (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 :
157 : unsigned long
158 : generic_get_unmapped_area(struct file *filp, unsigned long addr,
159 : unsigned long len, unsigned long pgoff,
160 : unsigned long flags);
161 : unsigned long
162 : generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
163 : unsigned long len, unsigned long pgoff,
164 : unsigned long flags);
165 : #else
166 : static inline void arch_pick_mmap_layout(struct mm_struct *mm,
167 : struct rlimit *rlim_stack) {}
168 : #endif
169 :
170 : static inline bool in_vfork(struct task_struct *tsk)
171 : {
172 : bool ret;
173 :
174 : /*
175 : * need RCU to access ->real_parent if CLONE_VM was used along with
176 : * CLONE_PARENT.
177 : *
178 : * We check real_parent->mm == tsk->mm because CLONE_VFORK does not
179 : * imply CLONE_VM
180 : *
181 : * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus
182 : * ->real_parent is not necessarily the task doing vfork(), so in
183 : * theory we can't rely on task_lock() if we want to dereference it.
184 : *
185 : * And in this case we can't trust the real_parent->mm == tsk->mm
186 : * check, it can be false negative. But we do not care, if init or
187 : * another oom-unkillable task does this it should blame itself.
188 : */
189 : rcu_read_lock();
190 0 : ret = tsk->vfork_done &&
191 0 : rcu_dereference(tsk->real_parent)->mm == tsk->mm;
192 : rcu_read_unlock();
193 :
194 : return ret;
195 : }
196 :
197 : /*
198 : * Applies per-task gfp context to the given allocation flags.
199 : * PF_MEMALLOC_NOIO implies GFP_NOIO
200 : * PF_MEMALLOC_NOFS implies GFP_NOFS
201 : * PF_MEMALLOC_PIN implies !GFP_MOVABLE
202 : */
203 8905 : static inline gfp_t current_gfp_context(gfp_t flags)
204 : {
205 8905 : unsigned int pflags = READ_ONCE(current->flags);
206 :
207 8905 : if (unlikely(pflags & (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS | PF_MEMALLOC_PIN))) {
208 : /*
209 : * NOIO implies both NOIO and NOFS and it is a weaker context
210 : * so always make sure it makes precedence
211 : */
212 0 : if (pflags & PF_MEMALLOC_NOIO)
213 0 : flags &= ~(__GFP_IO | __GFP_FS);
214 0 : else if (pflags & PF_MEMALLOC_NOFS)
215 0 : flags &= ~__GFP_FS;
216 :
217 0 : if (pflags & PF_MEMALLOC_PIN)
218 0 : flags &= ~__GFP_MOVABLE;
219 : }
220 8905 : return flags;
221 : }
222 :
223 : #ifdef CONFIG_LOCKDEP
224 : extern void __fs_reclaim_acquire(unsigned long ip);
225 : extern void __fs_reclaim_release(unsigned long ip);
226 : extern void fs_reclaim_acquire(gfp_t gfp_mask);
227 : extern void fs_reclaim_release(gfp_t gfp_mask);
228 : #else
229 : static inline void __fs_reclaim_acquire(unsigned long ip) { }
230 : static inline void __fs_reclaim_release(unsigned long ip) { }
231 : static inline void fs_reclaim_acquire(gfp_t gfp_mask) { }
232 : static inline void fs_reclaim_release(gfp_t gfp_mask) { }
233 : #endif
234 :
235 : /* Any memory-allocation retry loop should use
236 : * memalloc_retry_wait(), and pass the flags for the most
237 : * constrained allocation attempt that might have failed.
238 : * This provides useful documentation of where loops are,
239 : * and a central place to fine tune the waiting as the MM
240 : * implementation changes.
241 : */
242 : static inline void memalloc_retry_wait(gfp_t gfp_flags)
243 : {
244 : /* We use io_schedule_timeout because waiting for memory
245 : * typically included waiting for dirty pages to be
246 : * written out, which requires IO.
247 : */
248 : __set_current_state(TASK_UNINTERRUPTIBLE);
249 : gfp_flags = current_gfp_context(gfp_flags);
250 : if (gfpflags_allow_blocking(gfp_flags) &&
251 : !(gfp_flags & __GFP_NORETRY))
252 : /* Probably waited already, no need for much more */
253 : io_schedule_timeout(1);
254 : else
255 : /* Probably didn't wait, and has now released a lock,
256 : * so now is a good time to wait
257 : */
258 : io_schedule_timeout(HZ/50);
259 : }
260 :
261 : /**
262 : * might_alloc - Mark possible allocation sites
263 : * @gfp_mask: gfp_t flags that would be used to allocate
264 : *
265 : * Similar to might_sleep() and other annotations, this can be used in functions
266 : * that might allocate, but often don't. Compiles to nothing without
267 : * CONFIG_LOCKDEP. Includes a conditional might_sleep() if @gfp allows blocking.
268 : */
269 : static inline void might_alloc(gfp_t gfp_mask)
270 : {
271 430106 : fs_reclaim_acquire(gfp_mask);
272 430106 : fs_reclaim_release(gfp_mask);
273 :
274 430106 : might_sleep_if(gfpflags_allow_blocking(gfp_mask));
275 : }
276 :
277 : /**
278 : * memalloc_noio_save - Marks implicit GFP_NOIO allocation scope.
279 : *
280 : * This functions marks the beginning of the GFP_NOIO allocation scope.
281 : * All further allocations will implicitly drop __GFP_IO flag and so
282 : * they are safe for the IO critical section from the allocation recursion
283 : * point of view. Use memalloc_noio_restore to end the scope with flags
284 : * returned by this function.
285 : *
286 : * This function is safe to be used from any context.
287 : */
288 : static inline unsigned int memalloc_noio_save(void)
289 : {
290 18 : unsigned int flags = current->flags & PF_MEMALLOC_NOIO;
291 18 : current->flags |= PF_MEMALLOC_NOIO;
292 : return flags;
293 : }
294 :
295 : /**
296 : * memalloc_noio_restore - Ends the implicit GFP_NOIO scope.
297 : * @flags: Flags to restore.
298 : *
299 : * Ends the implicit GFP_NOIO scope started by memalloc_noio_save function.
300 : * Always make sure that the given flags is the return value from the
301 : * pairing memalloc_noio_save call.
302 : */
303 : static inline void memalloc_noio_restore(unsigned int flags)
304 : {
305 36 : current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
306 : }
307 :
308 : /**
309 : * memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope.
310 : *
311 : * This functions marks the beginning of the GFP_NOFS allocation scope.
312 : * All further allocations will implicitly drop __GFP_FS flag and so
313 : * they are safe for the FS critical section from the allocation recursion
314 : * point of view. Use memalloc_nofs_restore to end the scope with flags
315 : * returned by this function.
316 : *
317 : * This function is safe to be used from any context.
318 : */
319 : static inline unsigned int memalloc_nofs_save(void)
320 : {
321 0 : unsigned int flags = current->flags & PF_MEMALLOC_NOFS;
322 0 : current->flags |= PF_MEMALLOC_NOFS;
323 : return flags;
324 : }
325 :
326 : /**
327 : * memalloc_nofs_restore - Ends the implicit GFP_NOFS scope.
328 : * @flags: Flags to restore.
329 : *
330 : * Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function.
331 : * Always make sure that the given flags is the return value from the
332 : * pairing memalloc_nofs_save call.
333 : */
334 : static inline void memalloc_nofs_restore(unsigned int flags)
335 : {
336 0 : current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags;
337 : }
338 :
339 : static inline unsigned int memalloc_noreclaim_save(void)
340 : {
341 0 : unsigned int flags = current->flags & PF_MEMALLOC;
342 0 : current->flags |= PF_MEMALLOC;
343 : return flags;
344 : }
345 :
346 : static inline void memalloc_noreclaim_restore(unsigned int flags)
347 : {
348 0 : current->flags = (current->flags & ~PF_MEMALLOC) | flags;
349 : }
350 :
351 : static inline unsigned int memalloc_pin_save(void)
352 : {
353 0 : unsigned int flags = current->flags & PF_MEMALLOC_PIN;
354 :
355 0 : current->flags |= PF_MEMALLOC_PIN;
356 : return flags;
357 : }
358 :
359 : static inline void memalloc_pin_restore(unsigned int flags)
360 : {
361 0 : current->flags = (current->flags & ~PF_MEMALLOC_PIN) | flags;
362 : }
363 :
364 : #ifdef CONFIG_MEMCG
365 : DECLARE_PER_CPU(struct mem_cgroup *, int_active_memcg);
366 : /**
367 : * set_active_memcg - Starts the remote memcg charging scope.
368 : * @memcg: memcg to charge.
369 : *
370 : * This function marks the beginning of the remote memcg charging scope. All the
371 : * __GFP_ACCOUNT allocations till the end of the scope will be charged to the
372 : * given memcg.
373 : *
374 : * NOTE: This function can nest. Users must save the return value and
375 : * reset the previous value after their own charging scope is over.
376 : */
377 : static inline struct mem_cgroup *
378 : set_active_memcg(struct mem_cgroup *memcg)
379 : {
380 : struct mem_cgroup *old;
381 :
382 : if (!in_task()) {
383 : old = this_cpu_read(int_active_memcg);
384 : this_cpu_write(int_active_memcg, memcg);
385 : } else {
386 : old = current->active_memcg;
387 : current->active_memcg = memcg;
388 : }
389 :
390 : return old;
391 : }
392 : #else
393 : static inline struct mem_cgroup *
394 : set_active_memcg(struct mem_cgroup *memcg)
395 : {
396 : return NULL;
397 : }
398 : #endif
399 :
400 : #ifdef CONFIG_MEMBARRIER
401 : enum {
402 : MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0),
403 : MEMBARRIER_STATE_PRIVATE_EXPEDITED = (1U << 1),
404 : MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY = (1U << 2),
405 : MEMBARRIER_STATE_GLOBAL_EXPEDITED = (1U << 3),
406 : MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY = (1U << 4),
407 : MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE = (1U << 5),
408 : MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ_READY = (1U << 6),
409 : MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ = (1U << 7),
410 : };
411 :
412 : enum {
413 : MEMBARRIER_FLAG_SYNC_CORE = (1U << 0),
414 : MEMBARRIER_FLAG_RSEQ = (1U << 1),
415 : };
416 :
417 : #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
418 : #include <asm/membarrier.h>
419 : #endif
420 :
421 : static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
422 : {
423 0 : if (current->mm != mm)
424 : return;
425 0 : if (likely(!(atomic_read(&mm->membarrier_state) &
426 : MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE)))
427 : return;
428 : sync_core_before_usermode();
429 : }
430 :
431 : extern void membarrier_exec_mmap(struct mm_struct *mm);
432 :
433 : extern void membarrier_update_current_mm(struct mm_struct *next_mm);
434 :
435 : #else
436 : #ifdef CONFIG_ARCH_HAS_MEMBARRIER_CALLBACKS
437 : static inline void membarrier_arch_switch_mm(struct mm_struct *prev,
438 : struct mm_struct *next,
439 : struct task_struct *tsk)
440 : {
441 : }
442 : #endif
443 : static inline void membarrier_exec_mmap(struct mm_struct *mm)
444 : {
445 : }
446 : static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
447 : {
448 : }
449 : static inline void membarrier_update_current_mm(struct mm_struct *next_mm)
450 : {
451 : }
452 : #endif
453 :
454 : #ifdef CONFIG_IOMMU_SVA
455 : static inline void mm_pasid_init(struct mm_struct *mm)
456 : {
457 : mm->pasid = INVALID_IOASID;
458 : }
459 :
460 : /* Associate a PASID with an mm_struct: */
461 : static inline void mm_pasid_set(struct mm_struct *mm, u32 pasid)
462 : {
463 : mm->pasid = pasid;
464 : }
465 :
466 : static inline void mm_pasid_drop(struct mm_struct *mm)
467 : {
468 : if (pasid_valid(mm->pasid)) {
469 : ioasid_free(mm->pasid);
470 : mm->pasid = INVALID_IOASID;
471 : }
472 : }
473 : #else
474 : static inline void mm_pasid_init(struct mm_struct *mm) {}
475 : static inline void mm_pasid_set(struct mm_struct *mm, u32 pasid) {}
476 : static inline void mm_pasid_drop(struct mm_struct *mm) {}
477 : #endif
478 :
479 : #endif /* _LINUX_SCHED_MM_H */
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