Branch data Line data Source code
1 : : /*
2 : : * mm/rmap.c - physical to virtual reverse mappings
3 : : *
4 : : * Copyright 2001, Rik van Riel <riel@conectiva.com.br>
5 : : * Released under the General Public License (GPL).
6 : : *
7 : : * Simple, low overhead reverse mapping scheme.
8 : : * Please try to keep this thing as modular as possible.
9 : : *
10 : : * Provides methods for unmapping each kind of mapped page:
11 : : * the anon methods track anonymous pages, and
12 : : * the file methods track pages belonging to an inode.
13 : : *
14 : : * Original design by Rik van Riel <riel@conectiva.com.br> 2001
15 : : * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
16 : : * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
17 : : * Contributions by Hugh Dickins 2003, 2004
18 : : */
19 : :
20 : : /*
21 : : * Lock ordering in mm:
22 : : *
23 : : * inode->i_mutex (while writing or truncating, not reading or faulting)
24 : : * mm->mmap_sem
25 : : * page->flags PG_locked (lock_page)
26 : : * hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share)
27 : : * mapping->i_mmap_rwsem
28 : : * anon_vma->rwsem
29 : : * mm->page_table_lock or pte_lock
30 : : * pgdat->lru_lock (in mark_page_accessed, isolate_lru_page)
31 : : * swap_lock (in swap_duplicate, swap_info_get)
32 : : * mmlist_lock (in mmput, drain_mmlist and others)
33 : : * mapping->private_lock (in __set_page_dirty_buffers)
34 : : * mem_cgroup_{begin,end}_page_stat (memcg->move_lock)
35 : : * i_pages lock (widely used)
36 : : * inode->i_lock (in set_page_dirty's __mark_inode_dirty)
37 : : * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
38 : : * sb_lock (within inode_lock in fs/fs-writeback.c)
39 : : * i_pages lock (widely used, in set_page_dirty,
40 : : * in arch-dependent flush_dcache_mmap_lock,
41 : : * within bdi.wb->list_lock in __sync_single_inode)
42 : : *
43 : : * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon)
44 : : * ->tasklist_lock
45 : : * pte map lock
46 : : */
47 : :
48 : : #include <linux/mm.h>
49 : : #include <linux/sched/mm.h>
50 : : #include <linux/sched/task.h>
51 : : #include <linux/pagemap.h>
52 : : #include <linux/swap.h>
53 : : #include <linux/swapops.h>
54 : : #include <linux/slab.h>
55 : : #include <linux/init.h>
56 : : #include <linux/ksm.h>
57 : : #include <linux/rmap.h>
58 : : #include <linux/rcupdate.h>
59 : : #include <linux/export.h>
60 : : #include <linux/memcontrol.h>
61 : : #include <linux/mmu_notifier.h>
62 : : #include <linux/migrate.h>
63 : : #include <linux/hugetlb.h>
64 : : #include <linux/huge_mm.h>
65 : : #include <linux/backing-dev.h>
66 : : #include <linux/page_idle.h>
67 : : #include <linux/memremap.h>
68 : : #include <linux/userfaultfd_k.h>
69 : :
70 : : #include <asm/tlbflush.h>
71 : :
72 : : #include <trace/events/tlb.h>
73 : :
74 : : #include "internal.h"
75 : :
76 : : static struct kmem_cache *anon_vma_cachep;
77 : : static struct kmem_cache *anon_vma_chain_cachep;
78 : :
79 : 11012276 : static inline struct anon_vma *anon_vma_alloc(void)
80 : : {
81 : : struct anon_vma *anon_vma;
82 : :
83 : 11012276 : anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
84 [ + + ]: 11016271 : if (anon_vma) {
85 : : atomic_set(&anon_vma->refcount, 1);
86 : 11008999 : anon_vma->degree = 1; /* Reference for first vma */
87 : 11008999 : anon_vma->parent = anon_vma;
88 : : /*
89 : : * Initialise the anon_vma root to point to itself. If called
90 : : * from fork, the root will be reset to the parents anon_vma.
91 : : */
92 : 11008999 : anon_vma->root = anon_vma;
93 : : }
94 : :
95 : 11016271 : return anon_vma;
96 : : }
97 : :
98 : 10552556 : static inline void anon_vma_free(struct anon_vma *anon_vma)
99 : : {
100 : : VM_BUG_ON(atomic_read(&anon_vma->refcount));
101 : :
102 : : /*
103 : : * Synchronize against page_lock_anon_vma_read() such that
104 : : * we can safely hold the lock without the anon_vma getting
105 : : * freed.
106 : : *
107 : : * Relies on the full mb implied by the atomic_dec_and_test() from
108 : : * put_anon_vma() against the acquire barrier implied by
109 : : * down_read_trylock() from page_lock_anon_vma_read(). This orders:
110 : : *
111 : : * page_lock_anon_vma_read() VS put_anon_vma()
112 : : * down_read_trylock() atomic_dec_and_test()
113 : : * LOCK MB
114 : : * atomic_read() rwsem_is_locked()
115 : : *
116 : : * LOCK should suffice since the actual taking of the lock must
117 : : * happen _before_ what follows.
118 : : */
119 : 10552556 : might_sleep();
120 [ + + ]: 21105136 : if (rwsem_is_locked(&anon_vma->root->rwsem)) {
121 : : anon_vma_lock_write(anon_vma);
122 : : anon_vma_unlock_write(anon_vma);
123 : : }
124 : :
125 : 10552568 : kmem_cache_free(anon_vma_cachep, anon_vma);
126 : 10552522 : }
127 : :
128 : : static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp)
129 : : {
130 : 21464521 : return kmem_cache_alloc(anon_vma_chain_cachep, gfp);
131 : : }
132 : :
133 : : static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
134 : : {
135 : 20685795 : kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
136 : : }
137 : :
138 : : static void anon_vma_chain_link(struct vm_area_struct *vma,
139 : : struct anon_vma_chain *avc,
140 : : struct anon_vma *anon_vma)
141 : : {
142 : 21465077 : avc->vma = vma;
143 : 21465077 : avc->anon_vma = anon_vma;
144 : 21465077 : list_add(&avc->same_vma, &vma->anon_vma_chain);
145 : 21465077 : anon_vma_interval_tree_insert(avc, &anon_vma->rb_root);
146 : : }
147 : :
148 : : /**
149 : : * __anon_vma_prepare - attach an anon_vma to a memory region
150 : : * @vma: the memory region in question
151 : : *
152 : : * This makes sure the memory mapping described by 'vma' has
153 : : * an 'anon_vma' attached to it, so that we can associate the
154 : : * anonymous pages mapped into it with that anon_vma.
155 : : *
156 : : * The common case will be that we already have one, which
157 : : * is handled inline by anon_vma_prepare(). But if
158 : : * not we either need to find an adjacent mapping that we
159 : : * can re-use the anon_vma from (very common when the only
160 : : * reason for splitting a vma has been mprotect()), or we
161 : : * allocate a new one.
162 : : *
163 : : * Anon-vma allocations are very subtle, because we may have
164 : : * optimistically looked up an anon_vma in page_lock_anon_vma_read()
165 : : * and that may actually touch the spinlock even in the newly
166 : : * allocated vma (it depends on RCU to make sure that the
167 : : * anon_vma isn't actually destroyed).
168 : : *
169 : : * As a result, we need to do proper anon_vma locking even
170 : : * for the new allocation. At the same time, we do not want
171 : : * to do any locking for the common case of already having
172 : : * an anon_vma.
173 : : *
174 : : * This must be called with the mmap_sem held for reading.
175 : : */
176 : 3256869 : int __anon_vma_prepare(struct vm_area_struct *vma)
177 : : {
178 : 3256869 : struct mm_struct *mm = vma->vm_mm;
179 : : struct anon_vma *anon_vma, *allocated;
180 : : struct anon_vma_chain *avc;
181 : :
182 : 3256869 : might_sleep();
183 : :
184 : : avc = anon_vma_chain_alloc(GFP_KERNEL);
185 [ + + ]: 3269332 : if (!avc)
186 : : goto out_enomem;
187 : :
188 : 3269220 : anon_vma = find_mergeable_anon_vma(vma);
189 : : allocated = NULL;
190 [ + + ]: 3266259 : if (!anon_vma) {
191 : 3249022 : anon_vma = anon_vma_alloc();
192 [ + - ]: 3260958 : if (unlikely(!anon_vma))
193 : : goto out_enomem_free_avc;
194 : : allocated = anon_vma;
195 : : }
196 : :
197 : : anon_vma_lock_write(anon_vma);
198 : : /* page_table_lock to protect against threads */
199 : : spin_lock(&mm->page_table_lock);
200 [ + + ]: 3266103 : if (likely(!vma->anon_vma)) {
201 : 3260385 : vma->anon_vma = anon_vma;
202 : : anon_vma_chain_link(vma, avc, anon_vma);
203 : : /* vma reference or self-parent link for new root */
204 : 3256882 : anon_vma->degree++;
205 : : allocated = NULL;
206 : : avc = NULL;
207 : : }
208 : : spin_unlock(&mm->page_table_lock);
209 : : anon_vma_unlock_write(anon_vma);
210 : :
211 [ - + ]: 3269054 : if (unlikely(allocated))
212 : 0 : put_anon_vma(allocated);
213 [ - + ]: 3269086 : if (unlikely(avc))
214 : : anon_vma_chain_free(avc);
215 : :
216 : : return 0;
217 : :
218 : : out_enomem_free_avc:
219 : : anon_vma_chain_free(avc);
220 : : out_enomem:
221 : : return -ENOMEM;
222 : : }
223 : :
224 : : /*
225 : : * This is a useful helper function for locking the anon_vma root as
226 : : * we traverse the vma->anon_vma_chain, looping over anon_vma's that
227 : : * have the same vma.
228 : : *
229 : : * Such anon_vma's should have the same root, so you'd expect to see
230 : : * just a single mutex_lock for the whole traversal.
231 : : */
232 : 31131811 : static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma)
233 : : {
234 : 31131811 : struct anon_vma *new_root = anon_vma->root;
235 [ + + ]: 31131811 : if (new_root != root) {
236 [ - + # # : 21697934 : if (WARN_ON_ONCE(root))
- + ]
237 : 0 : up_write(&root->rwsem);
238 : : root = new_root;
239 : 21698127 : down_write(&root->rwsem);
240 : : }
241 : 31132235 : return root;
242 : : }
243 : :
244 : : static inline void unlock_anon_vma_root(struct anon_vma *root)
245 : : {
246 [ + + # # : 38021807 : if (root)
+ + ]
247 : 21697318 : up_write(&root->rwsem);
248 : : }
249 : :
250 : : /*
251 : : * Attach the anon_vmas from src to dst.
252 : : * Returns 0 on success, -ENOMEM on failure.
253 : : *
254 : : * If dst->anon_vma is NULL this function tries to find and reuse existing
255 : : * anon_vma which has no vmas and only one child anon_vma. This prevents
256 : : * degradation of anon_vma hierarchy to endless linear chain in case of
257 : : * constantly forking task. On the other hand, an anon_vma with more than one
258 : : * child isn't reused even if there was no alive vma, thus rmap walker has a
259 : : * good chance of avoiding scanning the whole hierarchy when it searches where
260 : : * page is mapped.
261 : : */
262 : 12879778 : int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
263 : : {
264 : : struct anon_vma_chain *avc, *pavc;
265 : : struct anon_vma *root = NULL;
266 : :
267 [ + + ]: 23335416 : list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
268 : : struct anon_vma *anon_vma;
269 : :
270 : : avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
271 [ - + ]: 10455856 : if (unlikely(!avc)) {
272 : : unlock_anon_vma_root(root);
273 : : root = NULL;
274 : : avc = anon_vma_chain_alloc(GFP_KERNEL);
275 [ # # ]: 0 : if (!avc)
276 : : goto enomem_failure;
277 : : }
278 : 10455856 : anon_vma = pavc->anon_vma;
279 : 10455856 : root = lock_anon_vma_root(root, anon_vma);
280 : : anon_vma_chain_link(dst, avc, anon_vma);
281 : :
282 : : /*
283 : : * Reuse existing anon_vma if its degree lower than two,
284 : : * that means it has no vma and only one anon_vma child.
285 : : *
286 : : * Do not chose parent anon_vma, otherwise first child
287 : : * will always reuse it. Root anon_vma is never reused:
288 : : * it has self-parent reference and at least one child.
289 : : */
290 [ + + + + : 11346721 : if (!dst->anon_vma && anon_vma != src->anon_vma &&
+ + ]
291 : 891083 : anon_vma->degree < 2)
292 : 9315 : dst->anon_vma = anon_vma;
293 : : }
294 [ + + ]: 12881149 : if (dst->anon_vma)
295 : 1814331 : dst->anon_vma->degree++;
296 : : unlock_anon_vma_root(root);
297 : : return 0;
298 : :
299 : : enomem_failure:
300 : : /*
301 : : * dst->anon_vma is dropped here otherwise its degree can be incorrectly
302 : : * decremented in unlink_anon_vmas().
303 : : * We can safely do this because callers of anon_vma_clone() don't care
304 : : * about dst->anon_vma if anon_vma_clone() failed.
305 : : */
306 : 0 : dst->anon_vma = NULL;
307 : 0 : unlink_anon_vmas(dst);
308 : 0 : return -ENOMEM;
309 : : }
310 : :
311 : : /*
312 : : * Attach vma to its own anon_vma, as well as to the anon_vmas that
313 : : * the corresponding VMA in the parent process is attached to.
314 : : * Returns 0 on success, non-zero on failure.
315 : : */
316 : 14986570 : int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
317 : : {
318 : : struct anon_vma_chain *avc;
319 : : struct anon_vma *anon_vma;
320 : : int error;
321 : :
322 : : /* Don't bother if the parent process has no anon_vma here. */
323 [ + + ]: 14986570 : if (!pvma->anon_vma)
324 : : return 0;
325 : :
326 : : /* Drop inherited anon_vma, we'll reuse existing or allocate new. */
327 : 7758343 : vma->anon_vma = NULL;
328 : :
329 : : /*
330 : : * First, attach the new VMA to the parent VMA's anon_vmas,
331 : : * so rmap can find non-COWed pages in child processes.
332 : : */
333 : 7758343 : error = anon_vma_clone(vma, pvma);
334 [ + + ]: 7758387 : if (error)
335 : : return error;
336 : :
337 : : /* An existing anon_vma has been reused, all done then. */
338 [ + + ]: 7758384 : if (vma->anon_vma)
339 : : return 0;
340 : :
341 : : /* Then add our own anon_vma. */
342 : 7749018 : anon_vma = anon_vma_alloc();
343 [ + + ]: 7749075 : if (!anon_vma)
344 : : goto out_error;
345 : : avc = anon_vma_chain_alloc(GFP_KERNEL);
346 [ + - ]: 7749079 : if (!avc)
347 : : goto out_error_free_anon_vma;
348 : :
349 : : /*
350 : : * The root anon_vma's spinlock is the lock actually used when we
351 : : * lock any of the anon_vmas in this anon_vma tree.
352 : : */
353 : 7749079 : anon_vma->root = pvma->anon_vma->root;
354 : 7749079 : anon_vma->parent = pvma->anon_vma;
355 : : /*
356 : : * With refcounts, an anon_vma can stay around longer than the
357 : : * process it belongs to. The root anon_vma needs to be pinned until
358 : : * this anon_vma is freed, because the lock lives in the root.
359 : : */
360 : : get_anon_vma(anon_vma->root);
361 : : /* Mark this anon_vma as the one where our new (COWed) pages go. */
362 : 7749044 : vma->anon_vma = anon_vma;
363 : : anon_vma_lock_write(anon_vma);
364 : : anon_vma_chain_link(vma, avc, anon_vma);
365 : 7749020 : anon_vma->parent->degree++;
366 : : anon_vma_unlock_write(anon_vma);
367 : :
368 : 7749075 : return 0;
369 : :
370 : : out_error_free_anon_vma:
371 : 0 : put_anon_vma(anon_vma);
372 : : out_error:
373 : 26 : unlink_anon_vmas(vma);
374 : 0 : return -ENOMEM;
375 : : }
376 : :
377 : 25139013 : void unlink_anon_vmas(struct vm_area_struct *vma)
378 : : {
379 : : struct anon_vma_chain *avc, *next;
380 : : struct anon_vma *root = NULL;
381 : :
382 : : /*
383 : : * Unlink each anon_vma chained to the VMA. This list is ordered
384 : : * from newest to oldest, ensuring the root anon_vma gets freed last.
385 : : */
386 [ + + ]: 45824169 : list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
387 : 20683511 : struct anon_vma *anon_vma = avc->anon_vma;
388 : :
389 : 20683511 : root = lock_anon_vma_root(root, anon_vma);
390 : 20686102 : anon_vma_interval_tree_remove(avc, &anon_vma->rb_root);
391 : :
392 : : /*
393 : : * Leave empty anon_vmas on the list - we'll need
394 : : * to free them outside the lock.
395 : : */
396 [ + + ]: 20685954 : if (RB_EMPTY_ROOT(&anon_vma->rb_root.rb_root)) {
397 : 10552238 : anon_vma->parent->degree--;
398 : 10552238 : continue;
399 : : }
400 : :
401 : : list_del(&avc->same_vma);
402 : : anon_vma_chain_free(avc);
403 : : }
404 [ + + ]: 25140658 : if (vma->anon_vma)
405 : 12134447 : vma->anon_vma->degree--;
406 : : unlock_anon_vma_root(root);
407 : :
408 : : /*
409 : : * Iterate the list once more, it now only contains empty and unlinked
410 : : * anon_vmas, destroy them. Could not do before due to __put_anon_vma()
411 : : * needing to write-acquire the anon_vma->root->rwsem.
412 : : */
413 [ + + ]: 35693117 : list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
414 : 10552465 : struct anon_vma *anon_vma = avc->anon_vma;
415 : :
416 : : VM_WARN_ON(anon_vma->degree);
417 : 10552465 : put_anon_vma(anon_vma);
418 : :
419 : : list_del(&avc->same_vma);
420 : : anon_vma_chain_free(avc);
421 : : }
422 : 25140652 : }
423 : :
424 : 1103968 : static void anon_vma_ctor(void *data)
425 : : {
426 : : struct anon_vma *anon_vma = data;
427 : :
428 : 1103968 : init_rwsem(&anon_vma->rwsem);
429 : : atomic_set(&anon_vma->refcount, 0);
430 : 1103976 : anon_vma->rb_root = RB_ROOT_CACHED;
431 : 1103976 : }
432 : :
433 : 207 : void __init anon_vma_init(void)
434 : : {
435 : 207 : anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
436 : : 0, SLAB_TYPESAFE_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT,
437 : : anon_vma_ctor);
438 : 207 : anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain,
439 : : SLAB_PANIC|SLAB_ACCOUNT);
440 : 207 : }
441 : :
442 : : /*
443 : : * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
444 : : *
445 : : * Since there is no serialization what so ever against page_remove_rmap()
446 : : * the best this function can do is return a locked anon_vma that might
447 : : * have been relevant to this page.
448 : : *
449 : : * The page might have been remapped to a different anon_vma or the anon_vma
450 : : * returned may already be freed (and even reused).
451 : : *
452 : : * In case it was remapped to a different anon_vma, the new anon_vma will be a
453 : : * child of the old anon_vma, and the anon_vma lifetime rules will therefore
454 : : * ensure that any anon_vma obtained from the page will still be valid for as
455 : : * long as we observe page_mapped() [ hence all those page_mapped() tests ].
456 : : *
457 : : * All users of this function must be very careful when walking the anon_vma
458 : : * chain and verify that the page in question is indeed mapped in it
459 : : * [ something equivalent to page_mapped_in_vma() ].
460 : : *
461 : : * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap()
462 : : * that the anon_vma pointer from page->mapping is valid if there is a
463 : : * mapcount, we can dereference the anon_vma after observing those.
464 : : */
465 : 0 : struct anon_vma *page_get_anon_vma(struct page *page)
466 : : {
467 : : struct anon_vma *anon_vma = NULL;
468 : : unsigned long anon_mapping;
469 : :
470 : : rcu_read_lock();
471 : : anon_mapping = (unsigned long)READ_ONCE(page->mapping);
472 [ # # ]: 0 : if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
473 : : goto out;
474 [ # # ]: 0 : if (!page_mapped(page))
475 : : goto out;
476 : :
477 : 0 : anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
478 [ # # ]: 0 : if (!atomic_inc_not_zero(&anon_vma->refcount)) {
479 : : anon_vma = NULL;
480 : : goto out;
481 : : }
482 : :
483 : : /*
484 : : * If this page is still mapped, then its anon_vma cannot have been
485 : : * freed. But if it has been unmapped, we have no security against the
486 : : * anon_vma structure being freed and reused (for another anon_vma:
487 : : * SLAB_TYPESAFE_BY_RCU guarantees that - so the atomic_inc_not_zero()
488 : : * above cannot corrupt).
489 : : */
490 [ # # ]: 0 : if (!page_mapped(page)) {
491 : : rcu_read_unlock();
492 : 0 : put_anon_vma(anon_vma);
493 : 0 : return NULL;
494 : : }
495 : : out:
496 : : rcu_read_unlock();
497 : :
498 : 0 : return anon_vma;
499 : : }
500 : :
501 : : /*
502 : : * Similar to page_get_anon_vma() except it locks the anon_vma.
503 : : *
504 : : * Its a little more complex as it tries to keep the fast path to a single
505 : : * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
506 : : * reference like with page_get_anon_vma() and then block on the mutex.
507 : : */
508 : 0 : struct anon_vma *page_lock_anon_vma_read(struct page *page)
509 : : {
510 : : struct anon_vma *anon_vma = NULL;
511 : : struct anon_vma *root_anon_vma;
512 : : unsigned long anon_mapping;
513 : :
514 : : rcu_read_lock();
515 : : anon_mapping = (unsigned long)READ_ONCE(page->mapping);
516 [ # # ]: 0 : if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
517 : : goto out;
518 [ # # ]: 0 : if (!page_mapped(page))
519 : : goto out;
520 : :
521 : 0 : anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
522 : 0 : root_anon_vma = READ_ONCE(anon_vma->root);
523 [ # # ]: 0 : if (down_read_trylock(&root_anon_vma->rwsem)) {
524 : : /*
525 : : * If the page is still mapped, then this anon_vma is still
526 : : * its anon_vma, and holding the mutex ensures that it will
527 : : * not go away, see anon_vma_free().
528 : : */
529 [ # # ]: 0 : if (!page_mapped(page)) {
530 : 0 : up_read(&root_anon_vma->rwsem);
531 : : anon_vma = NULL;
532 : : }
533 : : goto out;
534 : : }
535 : :
536 : : /* trylock failed, we got to sleep */
537 [ # # ]: 0 : if (!atomic_inc_not_zero(&anon_vma->refcount)) {
538 : : anon_vma = NULL;
539 : : goto out;
540 : : }
541 : :
542 [ # # ]: 0 : if (!page_mapped(page)) {
543 : : rcu_read_unlock();
544 : 0 : put_anon_vma(anon_vma);
545 : 0 : return NULL;
546 : : }
547 : :
548 : : /* we pinned the anon_vma, its safe to sleep */
549 : : rcu_read_unlock();
550 : : anon_vma_lock_read(anon_vma);
551 : :
552 [ # # ]: 0 : if (atomic_dec_and_test(&anon_vma->refcount)) {
553 : : /*
554 : : * Oops, we held the last refcount, release the lock
555 : : * and bail -- can't simply use put_anon_vma() because
556 : : * we'll deadlock on the anon_vma_lock_write() recursion.
557 : : */
558 : : anon_vma_unlock_read(anon_vma);
559 : 0 : __put_anon_vma(anon_vma);
560 : : anon_vma = NULL;
561 : : }
562 : :
563 : 0 : return anon_vma;
564 : :
565 : : out:
566 : : rcu_read_unlock();
567 : 0 : return anon_vma;
568 : : }
569 : :
570 : 0 : void page_unlock_anon_vma_read(struct anon_vma *anon_vma)
571 : : {
572 : : anon_vma_unlock_read(anon_vma);
573 : 0 : }
574 : :
575 : : #ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
576 : : /*
577 : : * Flush TLB entries for recently unmapped pages from remote CPUs. It is
578 : : * important if a PTE was dirty when it was unmapped that it's flushed
579 : : * before any IO is initiated on the page to prevent lost writes. Similarly,
580 : : * it must be flushed before freeing to prevent data leakage.
581 : : */
582 : : void try_to_unmap_flush(void)
583 : : {
584 : : struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
585 : :
586 : : if (!tlb_ubc->flush_required)
587 : : return;
588 : :
589 : : arch_tlbbatch_flush(&tlb_ubc->arch);
590 : : tlb_ubc->flush_required = false;
591 : : tlb_ubc->writable = false;
592 : : }
593 : :
594 : : /* Flush iff there are potentially writable TLB entries that can race with IO */
595 : : void try_to_unmap_flush_dirty(void)
596 : : {
597 : : struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
598 : :
599 : : if (tlb_ubc->writable)
600 : : try_to_unmap_flush();
601 : : }
602 : :
603 : : static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable)
604 : : {
605 : : struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
606 : :
607 : : arch_tlbbatch_add_mm(&tlb_ubc->arch, mm);
608 : : tlb_ubc->flush_required = true;
609 : :
610 : : /*
611 : : * Ensure compiler does not re-order the setting of tlb_flush_batched
612 : : * before the PTE is cleared.
613 : : */
614 : : barrier();
615 : : mm->tlb_flush_batched = true;
616 : :
617 : : /*
618 : : * If the PTE was dirty then it's best to assume it's writable. The
619 : : * caller must use try_to_unmap_flush_dirty() or try_to_unmap_flush()
620 : : * before the page is queued for IO.
621 : : */
622 : : if (writable)
623 : : tlb_ubc->writable = true;
624 : : }
625 : :
626 : : /*
627 : : * Returns true if the TLB flush should be deferred to the end of a batch of
628 : : * unmap operations to reduce IPIs.
629 : : */
630 : : static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
631 : : {
632 : : bool should_defer = false;
633 : :
634 : : if (!(flags & TTU_BATCH_FLUSH))
635 : : return false;
636 : :
637 : : /* If remote CPUs need to be flushed then defer batch the flush */
638 : : if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids)
639 : : should_defer = true;
640 : : put_cpu();
641 : :
642 : : return should_defer;
643 : : }
644 : :
645 : : /*
646 : : * Reclaim unmaps pages under the PTL but do not flush the TLB prior to
647 : : * releasing the PTL if TLB flushes are batched. It's possible for a parallel
648 : : * operation such as mprotect or munmap to race between reclaim unmapping
649 : : * the page and flushing the page. If this race occurs, it potentially allows
650 : : * access to data via a stale TLB entry. Tracking all mm's that have TLB
651 : : * batching in flight would be expensive during reclaim so instead track
652 : : * whether TLB batching occurred in the past and if so then do a flush here
653 : : * if required. This will cost one additional flush per reclaim cycle paid
654 : : * by the first operation at risk such as mprotect and mumap.
655 : : *
656 : : * This must be called under the PTL so that an access to tlb_flush_batched
657 : : * that is potentially a "reclaim vs mprotect/munmap/etc" race will synchronise
658 : : * via the PTL.
659 : : */
660 : : void flush_tlb_batched_pending(struct mm_struct *mm)
661 : : {
662 : : if (mm->tlb_flush_batched) {
663 : : flush_tlb_mm(mm);
664 : :
665 : : /*
666 : : * Do not allow the compiler to re-order the clearing of
667 : : * tlb_flush_batched before the tlb is flushed.
668 : : */
669 : : barrier();
670 : : mm->tlb_flush_batched = false;
671 : : }
672 : : }
673 : : #else
674 : : static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable)
675 : : {
676 : : }
677 : :
678 : : static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
679 : : {
680 : : return false;
681 : : }
682 : : #endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
683 : :
684 : : /*
685 : : * At what user virtual address is page expected in vma?
686 : : * Caller should check the page is actually part of the vma.
687 : : */
688 : 0 : unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
689 : : {
690 : : unsigned long address;
691 [ # # ]: 0 : if (PageAnon(page)) {
692 : 0 : struct anon_vma *page__anon_vma = page_anon_vma(page);
693 : : /*
694 : : * Note: swapoff's unuse_vma() is more efficient with this
695 : : * check, and needs it to match anon_vma when KSM is active.
696 : : */
697 [ # # # # : 0 : if (!vma->anon_vma || !page__anon_vma ||
# # ]
698 : 0 : vma->anon_vma->root != page__anon_vma->root)
699 : : return -EFAULT;
700 [ # # ]: 0 : } else if (page->mapping) {
701 [ # # # # ]: 0 : if (!vma->vm_file || vma->vm_file->f_mapping != page->mapping)
702 : : return -EFAULT;
703 : : } else
704 : : return -EFAULT;
705 : : address = __vma_address(page, vma);
706 [ # # # # ]: 0 : if (unlikely(address < vma->vm_start || address >= vma->vm_end))
707 : : return -EFAULT;
708 : 0 : return address;
709 : : }
710 : :
711 : 0 : pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
712 : : {
713 : : pgd_t *pgd;
714 : : p4d_t *p4d;
715 : : pud_t *pud;
716 : : pmd_t *pmd = NULL;
717 : : pmd_t pmde;
718 : :
719 : 0 : pgd = pgd_offset(mm, address);
720 : : if (!pgd_present(*pgd))
721 : : goto out;
722 : :
723 : : p4d = p4d_offset(pgd, address);
724 : : if (!p4d_present(*p4d))
725 : : goto out;
726 : :
727 : : pud = pud_offset(p4d, address);
728 : : if (!pud_present(*pud))
729 : : goto out;
730 : :
731 : : pmd = pmd_offset(pud, address);
732 : : /*
733 : : * Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at()
734 : : * without holding anon_vma lock for write. So when looking for a
735 : : * genuine pmde (in which to find pte), test present and !THP together.
736 : : */
737 : 0 : pmde = *pmd;
738 : 0 : barrier();
739 [ # # ]: 0 : if (!pmd_present(pmde) || pmd_trans_huge(pmde))
740 : : pmd = NULL;
741 : : out:
742 : 0 : return pmd;
743 : : }
744 : :
745 : : struct page_referenced_arg {
746 : : int mapcount;
747 : : int referenced;
748 : : unsigned long vm_flags;
749 : : struct mem_cgroup *memcg;
750 : : };
751 : : /*
752 : : * arg: page_referenced_arg will be passed
753 : : */
754 : 0 : static bool page_referenced_one(struct page *page, struct vm_area_struct *vma,
755 : : unsigned long address, void *arg)
756 : : {
757 : : struct page_referenced_arg *pra = arg;
758 : 0 : struct page_vma_mapped_walk pvmw = {
759 : : .page = page,
760 : : .vma = vma,
761 : : .address = address,
762 : : };
763 : : int referenced = 0;
764 : :
765 [ # # ]: 0 : while (page_vma_mapped_walk(&pvmw)) {
766 : 0 : address = pvmw.address;
767 : :
768 [ # # ]: 0 : if (vma->vm_flags & VM_LOCKED) {
769 : : page_vma_mapped_walk_done(&pvmw);
770 : 0 : pra->vm_flags |= VM_LOCKED;
771 : 0 : return false; /* To break the loop */
772 : : }
773 : :
774 [ # # ]: 0 : if (pvmw.pte) {
775 [ # # ]: 0 : if (ptep_clear_flush_young_notify(vma, address,
776 : : pvmw.pte)) {
777 : : /*
778 : : * Don't treat a reference through
779 : : * a sequentially read mapping as such.
780 : : * If the page has been used in another mapping,
781 : : * we will catch it; if this other mapping is
782 : : * already gone, the unmap path will have set
783 : : * PG_referenced or activated the page.
784 : : */
785 [ # # ]: 0 : if (likely(!(vma->vm_flags & VM_SEQ_READ)))
786 : 0 : referenced++;
787 : : }
788 : : } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
789 : : if (pmdp_clear_flush_young_notify(vma, address,
790 : : pvmw.pmd))
791 : : referenced++;
792 : : } else {
793 : : /* unexpected pmd-mapped page? */
794 [ # # ]: 0 : WARN_ON_ONCE(1);
795 : : }
796 : :
797 : 0 : pra->mapcount--;
798 : : }
799 : :
800 : : if (referenced)
801 : : clear_page_idle(page);
802 : : if (test_and_clear_page_young(page))
803 : : referenced++;
804 : :
805 [ # # ]: 0 : if (referenced) {
806 : 0 : pra->referenced++;
807 : 0 : pra->vm_flags |= vma->vm_flags;
808 : : }
809 : :
810 [ # # ]: 0 : if (!pra->mapcount)
811 : : return false; /* To break the loop */
812 : :
813 : 0 : return true;
814 : : }
815 : :
816 : 0 : static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
817 : : {
818 : : struct page_referenced_arg *pra = arg;
819 : 0 : struct mem_cgroup *memcg = pra->memcg;
820 : :
821 [ # # ]: 0 : if (!mm_match_cgroup(vma->vm_mm, memcg))
822 : : return true;
823 : :
824 : 0 : return false;
825 : : }
826 : :
827 : : /**
828 : : * page_referenced - test if the page was referenced
829 : : * @page: the page to test
830 : : * @is_locked: caller holds lock on the page
831 : : * @memcg: target memory cgroup
832 : : * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
833 : : *
834 : : * Quick test_and_clear_referenced for all mappings to a page,
835 : : * returns the number of ptes which referenced the page.
836 : : */
837 : 0 : int page_referenced(struct page *page,
838 : : int is_locked,
839 : : struct mem_cgroup *memcg,
840 : : unsigned long *vm_flags)
841 : : {
842 : : int we_locked = 0;
843 : 0 : struct page_referenced_arg pra = {
844 : : .mapcount = total_mapcount(page),
845 : : .memcg = memcg,
846 : : };
847 : 0 : struct rmap_walk_control rwc = {
848 : : .rmap_one = page_referenced_one,
849 : : .arg = (void *)&pra,
850 : : .anon_lock = page_lock_anon_vma_read,
851 : : };
852 : :
853 : 0 : *vm_flags = 0;
854 [ # # ]: 0 : if (!pra.mapcount)
855 : : return 0;
856 : :
857 [ # # ]: 0 : if (!page_rmapping(page))
858 : : return 0;
859 : :
860 [ # # # # ]: 0 : if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
861 : 0 : we_locked = trylock_page(page);
862 [ # # ]: 0 : if (!we_locked)
863 : : return 1;
864 : : }
865 : :
866 : : /*
867 : : * If we are reclaiming on behalf of a cgroup, skip
868 : : * counting on behalf of references from different
869 : : * cgroups
870 : : */
871 [ # # ]: 0 : if (memcg) {
872 : 0 : rwc.invalid_vma = invalid_page_referenced_vma;
873 : : }
874 : :
875 : 0 : rmap_walk(page, &rwc);
876 : 0 : *vm_flags = pra.vm_flags;
877 : :
878 [ # # ]: 0 : if (we_locked)
879 : 0 : unlock_page(page);
880 : :
881 : 0 : return pra.referenced;
882 : : }
883 : :
884 : 140 : static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
885 : : unsigned long address, void *arg)
886 : : {
887 : 140 : struct page_vma_mapped_walk pvmw = {
888 : : .page = page,
889 : : .vma = vma,
890 : : .address = address,
891 : : .flags = PVMW_SYNC,
892 : : };
893 : : struct mmu_notifier_range range;
894 : : int *cleaned = arg;
895 : :
896 : : /*
897 : : * We have to assume the worse case ie pmd for invalidation. Note that
898 : : * the page can not be free from this function.
899 : : */
900 : : mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
901 : : 0, vma, vma->vm_mm, address,
902 : : min(vma->vm_end, address + page_size(page)));
903 : : mmu_notifier_invalidate_range_start(&range);
904 : :
905 [ + + ]: 280 : while (page_vma_mapped_walk(&pvmw)) {
906 : : int ret = 0;
907 : :
908 : 140 : address = pvmw.address;
909 [ + - ]: 140 : if (pvmw.pte) {
910 : : pte_t entry;
911 : : pte_t *pte = pvmw.pte;
912 : :
913 [ - + ]: 140 : if (!pte_dirty(*pte) && !pte_write(*pte))
914 : 0 : continue;
915 : :
916 : 140 : flush_cache_page(vma, address, pte_pfn(*pte));
917 : 140 : entry = ptep_clear_flush(vma, address, pte);
918 : : entry = pte_wrprotect(entry);
919 : : entry = pte_mkclean(entry);
920 : 140 : set_pte_at(vma->vm_mm, address, pte, entry);
921 : : ret = 1;
922 : : } else {
923 : : #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
924 : : pmd_t *pmd = pvmw.pmd;
925 : : pmd_t entry;
926 : :
927 : : if (!pmd_dirty(*pmd) && !pmd_write(*pmd))
928 : : continue;
929 : :
930 : : flush_cache_page(vma, address, page_to_pfn(page));
931 : : entry = pmdp_invalidate(vma, address, pmd);
932 : : entry = pmd_wrprotect(entry);
933 : : entry = pmd_mkclean(entry);
934 : : set_pmd_at(vma->vm_mm, address, pmd, entry);
935 : : ret = 1;
936 : : #else
937 : : /* unexpected pmd-mapped page? */
938 [ # # ]: 0 : WARN_ON_ONCE(1);
939 : : #endif
940 : : }
941 : :
942 : : /*
943 : : * No need to call mmu_notifier_invalidate_range() as we are
944 : : * downgrading page table protection not changing it to point
945 : : * to a new page.
946 : : *
947 : : * See Documentation/vm/mmu_notifier.rst
948 : : */
949 [ + - ]: 140 : if (ret)
950 : 140 : (*cleaned)++;
951 : : }
952 : :
953 : : mmu_notifier_invalidate_range_end(&range);
954 : :
955 : 140 : return true;
956 : : }
957 : :
958 : 140 : static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg)
959 : : {
960 [ - + ]: 140 : if (vma->vm_flags & VM_SHARED)
961 : : return false;
962 : :
963 : 0 : return true;
964 : : }
965 : :
966 : 102440 : int page_mkclean(struct page *page)
967 : : {
968 : 102440 : int cleaned = 0;
969 : : struct address_space *mapping;
970 : 102440 : struct rmap_walk_control rwc = {
971 : : .arg = (void *)&cleaned,
972 : : .rmap_one = page_mkclean_one,
973 : : .invalid_vma = invalid_mkclean_vma,
974 : : };
975 : :
976 [ - + ]: 102440 : BUG_ON(!PageLocked(page));
977 : :
978 [ + + ]: 102440 : if (!page_mapped(page))
979 : : return 0;
980 : :
981 : 140 : mapping = page_mapping(page);
982 [ + - ]: 140 : if (!mapping)
983 : : return 0;
984 : :
985 : 140 : rmap_walk(page, &rwc);
986 : :
987 : 140 : return cleaned;
988 : : }
989 : : EXPORT_SYMBOL_GPL(page_mkclean);
990 : :
991 : : /**
992 : : * page_move_anon_rmap - move a page to our anon_vma
993 : : * @page: the page to move to our anon_vma
994 : : * @vma: the vma the page belongs to
995 : : *
996 : : * When a page belongs exclusively to one process after a COW event,
997 : : * that page can be moved into the anon_vma that belongs to just that
998 : : * process, so the rmap code will not search the parent or sibling
999 : : * processes.
1000 : : */
1001 : 4536498 : void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma)
1002 : : {
1003 : 4536498 : struct anon_vma *anon_vma = vma->anon_vma;
1004 : :
1005 : : page = compound_head(page);
1006 : :
1007 : : VM_BUG_ON_PAGE(!PageLocked(page), page);
1008 : : VM_BUG_ON_VMA(!anon_vma, vma);
1009 : :
1010 : 4536498 : anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1011 : : /*
1012 : : * Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
1013 : : * simultaneously, so a concurrent reader (eg page_referenced()'s
1014 : : * PageAnon()) will not see one without the other.
1015 : : */
1016 : 4536498 : WRITE_ONCE(page->mapping, (struct address_space *) anon_vma);
1017 : 4536498 : }
1018 : :
1019 : : /**
1020 : : * __page_set_anon_rmap - set up new anonymous rmap
1021 : : * @page: Page or Hugepage to add to rmap
1022 : : * @vma: VM area to add page to.
1023 : : * @address: User virtual address of the mapping
1024 : : * @exclusive: the page is exclusively owned by the current process
1025 : : */
1026 : 18702952 : static void __page_set_anon_rmap(struct page *page,
1027 : : struct vm_area_struct *vma, unsigned long address, int exclusive)
1028 : : {
1029 : 18702952 : struct anon_vma *anon_vma = vma->anon_vma;
1030 : :
1031 [ - + ]: 18702952 : BUG_ON(!anon_vma);
1032 : :
1033 [ + + ]: 18714892 : if (PageAnon(page))
1034 : 18714892 : return;
1035 : :
1036 : : /*
1037 : : * If the page isn't exclusively mapped into this vma,
1038 : : * we must use the _oldest_ possible anon_vma for the
1039 : : * page mapping!
1040 : : */
1041 [ - + ]: 18697659 : if (!exclusive)
1042 : 0 : anon_vma = anon_vma->root;
1043 : :
1044 : 18697659 : anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1045 : 18697659 : page->mapping = (struct address_space *) anon_vma;
1046 : 18697659 : page->index = linear_page_index(vma, address);
1047 : : }
1048 : :
1049 : : /**
1050 : : * __page_check_anon_rmap - sanity check anonymous rmap addition
1051 : : * @page: the page to add the mapping to
1052 : : * @vma: the vm area in which the mapping is added
1053 : : * @address: the user virtual address mapped
1054 : : */
1055 : : static void __page_check_anon_rmap(struct page *page,
1056 : : struct vm_area_struct *vma, unsigned long address)
1057 : : {
1058 : : #ifdef CONFIG_DEBUG_VM
1059 : : /*
1060 : : * The page's anon-rmap details (mapping and index) are guaranteed to
1061 : : * be set up correctly at this point.
1062 : : *
1063 : : * We have exclusion against page_add_anon_rmap because the caller
1064 : : * always holds the page locked, except if called from page_dup_rmap,
1065 : : * in which case the page is already known to be setup.
1066 : : *
1067 : : * We have exclusion against page_add_new_anon_rmap because those pages
1068 : : * are initially only visible via the pagetables, and the pte is locked
1069 : : * over the call to page_add_new_anon_rmap.
1070 : : */
1071 : : BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
1072 : : BUG_ON(page_to_pgoff(page) != linear_page_index(vma, address));
1073 : : #endif
1074 : : }
1075 : :
1076 : : /**
1077 : : * page_add_anon_rmap - add pte mapping to an anonymous page
1078 : : * @page: the page to add the mapping to
1079 : : * @vma: the vm area in which the mapping is added
1080 : : * @address: the user virtual address mapped
1081 : : * @compound: charge the page as compound or small page
1082 : : *
1083 : : * The caller needs to hold the pte lock, and the page must be locked in
1084 : : * the anon_vma case: to serialize mapping,index checking after setting,
1085 : : * and to ensure that PageAnon is not being upgraded racily to PageKsm
1086 : : * (but PageKsm is never downgraded to PageAnon).
1087 : : */
1088 : 0 : void page_add_anon_rmap(struct page *page,
1089 : : struct vm_area_struct *vma, unsigned long address, bool compound)
1090 : : {
1091 [ # # ]: 0 : do_page_add_anon_rmap(page, vma, address, compound ? RMAP_COMPOUND : 0);
1092 : 0 : }
1093 : :
1094 : : /*
1095 : : * Special version of the above for do_swap_page, which often runs
1096 : : * into pages that are exclusively owned by the current process.
1097 : : * Everybody else should continue to use page_add_anon_rmap above.
1098 : : */
1099 : 0 : void do_page_add_anon_rmap(struct page *page,
1100 : : struct vm_area_struct *vma, unsigned long address, int flags)
1101 : : {
1102 : 0 : bool compound = flags & RMAP_COMPOUND;
1103 : : bool first;
1104 : :
1105 [ # # ]: 0 : if (compound) {
1106 : : atomic_t *mapcount;
1107 : : VM_BUG_ON_PAGE(!PageLocked(page), page);
1108 : : VM_BUG_ON_PAGE(!PageTransHuge(page), page);
1109 : : mapcount = compound_mapcount_ptr(page);
1110 : : first = atomic_inc_and_test(mapcount);
1111 : : } else {
1112 : 0 : first = atomic_inc_and_test(&page->_mapcount);
1113 : : }
1114 : :
1115 [ # # ]: 0 : if (first) {
1116 : : int nr = compound ? hpage_nr_pages(page) : 1;
1117 : : /*
1118 : : * We use the irq-unsafe __{inc|mod}_zone_page_stat because
1119 : : * these counters are not modified in interrupt context, and
1120 : : * pte lock(a spinlock) is held, which implies preemption
1121 : : * disabled.
1122 : : */
1123 [ # # ]: 0 : if (compound)
1124 : 0 : __inc_node_page_state(page, NR_ANON_THPS);
1125 : 0 : __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, nr);
1126 : : }
1127 : : if (unlikely(PageKsm(page)))
1128 : 0 : return;
1129 : :
1130 : : VM_BUG_ON_PAGE(!PageLocked(page), page);
1131 : :
1132 : : /* address might be in next vma when migration races vma_adjust */
1133 [ # # ]: 0 : if (first)
1134 : 0 : __page_set_anon_rmap(page, vma, address,
1135 : : flags & RMAP_EXCLUSIVE);
1136 : : else
1137 : : __page_check_anon_rmap(page, vma, address);
1138 : : }
1139 : :
1140 : : /**
1141 : : * page_add_new_anon_rmap - add pte mapping to a new anonymous page
1142 : : * @page: the page to add the mapping to
1143 : : * @vma: the vm area in which the mapping is added
1144 : : * @address: the user virtual address mapped
1145 : : * @compound: charge the page as compound or small page
1146 : : *
1147 : : * Same as page_add_anon_rmap but must only be called on *new* pages.
1148 : : * This means the inc-and-test can be bypassed.
1149 : : * Page does not have to be locked.
1150 : : */
1151 : 18694169 : void page_add_new_anon_rmap(struct page *page,
1152 : : struct vm_area_struct *vma, unsigned long address, bool compound)
1153 : : {
1154 : : int nr = compound ? hpage_nr_pages(page) : 1;
1155 : :
1156 : : VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
1157 : : __SetPageSwapBacked(page);
1158 [ - + ]: 18718009 : if (compound) {
1159 : : VM_BUG_ON_PAGE(!PageTransHuge(page), page);
1160 : : /* increment count (starts at -1) */
1161 : : atomic_set(compound_mapcount_ptr(page), 0);
1162 : 0 : __inc_node_page_state(page, NR_ANON_THPS);
1163 : : } else {
1164 : : /* Anon THP always mapped first with PMD */
1165 : : VM_BUG_ON_PAGE(PageTransCompound(page), page);
1166 : : /* increment count (starts at -1) */
1167 : : atomic_set(&page->_mapcount, 0);
1168 : : }
1169 : 18718009 : __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, nr);
1170 : 18709436 : __page_set_anon_rmap(page, vma, address, 1);
1171 : 18708745 : }
1172 : :
1173 : : /**
1174 : : * page_add_file_rmap - add pte mapping to a file page
1175 : : * @page: the page to add the mapping to
1176 : : * @compound: charge the page as compound or small page
1177 : : *
1178 : : * The caller needs to hold the pte lock.
1179 : : */
1180 : 170740395 : void page_add_file_rmap(struct page *page, bool compound)
1181 : : {
1182 : : int i, nr = 1;
1183 : :
1184 : : VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
1185 : 170740395 : lock_page_memcg(page);
1186 : : if (compound && PageTransHuge(page)) {
1187 : : for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
1188 : : if (atomic_inc_and_test(&page[i]._mapcount))
1189 : : nr++;
1190 : : }
1191 : : if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
1192 : : goto out;
1193 : : if (PageSwapBacked(page))
1194 : : __inc_node_page_state(page, NR_SHMEM_PMDMAPPED);
1195 : : else
1196 : : __inc_node_page_state(page, NR_FILE_PMDMAPPED);
1197 : : } else {
1198 : : if (PageTransCompound(page) && page_mapping(page)) {
1199 : : VM_WARN_ON_ONCE(!PageLocked(page));
1200 : :
1201 : : SetPageDoubleMap(compound_head(page));
1202 : : if (PageMlocked(page))
1203 : : clear_page_mlock(compound_head(page));
1204 : : }
1205 [ + + ]: 341460254 : if (!atomic_inc_and_test(&page->_mapcount))
1206 : : goto out;
1207 : : }
1208 : 17454820 : __mod_lruvec_page_state(page, NR_FILE_MAPPED, nr);
1209 : : out:
1210 : 170740692 : unlock_page_memcg(page);
1211 : 170740225 : }
1212 : :
1213 : 157588660 : static void page_remove_file_rmap(struct page *page, bool compound)
1214 : : {
1215 : : int i, nr = 1;
1216 : :
1217 : : VM_BUG_ON_PAGE(compound && !PageHead(page), page);
1218 : 157588660 : lock_page_memcg(page);
1219 : :
1220 : : /* Hugepages are not counted in NR_FILE_MAPPED for now. */
1221 : : if (unlikely(PageHuge(page))) {
1222 : : /* hugetlb pages are always mapped with pmds */
1223 : : atomic_dec(compound_mapcount_ptr(page));
1224 : : goto out;
1225 : : }
1226 : :
1227 : : /* page still mapped by someone else? */
1228 : : if (compound && PageTransHuge(page)) {
1229 : : for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
1230 : : if (atomic_add_negative(-1, &page[i]._mapcount))
1231 : : nr++;
1232 : : }
1233 : : if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
1234 : : goto out;
1235 : : if (PageSwapBacked(page))
1236 : : __dec_node_page_state(page, NR_SHMEM_PMDMAPPED);
1237 : : else
1238 : : __dec_node_page_state(page, NR_FILE_PMDMAPPED);
1239 : : } else {
1240 [ + + ]: 157582562 : if (!atomic_add_negative(-1, &page->_mapcount))
1241 : : goto out;
1242 : : }
1243 : :
1244 : : /*
1245 : : * We use the irq-unsafe __{inc|mod}_lruvec_page_state because
1246 : : * these counters are not modified in interrupt context, and
1247 : : * pte lock(a spinlock) is held, which implies preemption disabled.
1248 : : */
1249 : 14274017 : __mod_lruvec_page_state(page, NR_FILE_MAPPED, -nr);
1250 : :
1251 [ - + ]: 14270428 : if (unlikely(PageMlocked(page)))
1252 : 0 : clear_page_mlock(page);
1253 : : out:
1254 : 157580792 : unlock_page_memcg(page);
1255 : 157584490 : }
1256 : :
1257 : : static void page_remove_anon_compound_rmap(struct page *page)
1258 : : {
1259 : : int i, nr;
1260 : :
1261 : 0 : if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
1262 : : return;
1263 : :
1264 : : /* Hugepages are not counted in NR_ANON_PAGES for now. */
1265 : : if (unlikely(PageHuge(page)))
1266 : : return;
1267 : :
1268 : : if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
1269 : : return;
1270 : :
1271 : : __dec_node_page_state(page, NR_ANON_THPS);
1272 : :
1273 : : if (TestClearPageDoubleMap(page)) {
1274 : : /*
1275 : : * Subpages can be mapped with PTEs too. Check how many of
1276 : : * themi are still mapped.
1277 : : */
1278 : : for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
1279 : : if (atomic_add_negative(-1, &page[i]._mapcount))
1280 : : nr++;
1281 : : }
1282 : : } else {
1283 : : nr = HPAGE_PMD_NR;
1284 : : }
1285 : :
1286 : : if (unlikely(PageMlocked(page)))
1287 : : clear_page_mlock(page);
1288 : :
1289 : : if (nr) {
1290 : : __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, -nr);
1291 : : deferred_split_huge_page(page);
1292 : : }
1293 : : }
1294 : :
1295 : : /**
1296 : : * page_remove_rmap - take down pte mapping from a page
1297 : : * @page: page to remove mapping from
1298 : : * @compound: uncharge the page as compound or small page
1299 : : *
1300 : : * The caller needs to hold the pte lock.
1301 : : */
1302 : 194792099 : void page_remove_rmap(struct page *page, bool compound)
1303 : : {
1304 [ + + ]: 194806467 : if (!PageAnon(page))
1305 : 157579574 : return page_remove_file_rmap(page, compound);
1306 : :
1307 [ - + ]: 37226893 : if (compound)
1308 : : return page_remove_anon_compound_rmap(page);
1309 : :
1310 : : /* page still mapped by someone else? */
1311 [ + + ]: 37226893 : if (!atomic_add_negative(-1, &page->_mapcount))
1312 : : return;
1313 : :
1314 : : /*
1315 : : * We use the irq-unsafe __{inc|mod}_zone_page_stat because
1316 : : * these counters are not modified in interrupt context, and
1317 : : * pte lock(a spinlock) is held, which implies preemption disabled.
1318 : : */
1319 : 15736715 : __dec_node_page_state(page, NR_ANON_MAPPED);
1320 : :
1321 [ - + ]: 15735605 : if (unlikely(PageMlocked(page)))
1322 : 0 : clear_page_mlock(page);
1323 : :
1324 : : if (PageTransCompound(page))
1325 : : deferred_split_huge_page(compound_head(page));
1326 : :
1327 : : /*
1328 : : * It would be tidy to reset the PageAnon mapping here,
1329 : : * but that might overwrite a racing page_add_anon_rmap
1330 : : * which increments mapcount after us but sets mapping
1331 : : * before us: so leave the reset to free_unref_page,
1332 : : * and remember that it's only reliable while mapped.
1333 : : * Leaving it set also helps swapoff to reinstate ptes
1334 : : * faster for those pages still in swapcache.
1335 : : */
1336 : : }
1337 : :
1338 : : /*
1339 : : * @arg: enum ttu_flags will be passed to this argument
1340 : : */
1341 : 0 : static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
1342 : : unsigned long address, void *arg)
1343 : : {
1344 : 0 : struct mm_struct *mm = vma->vm_mm;
1345 : 0 : struct page_vma_mapped_walk pvmw = {
1346 : : .page = page,
1347 : : .vma = vma,
1348 : : .address = address,
1349 : : };
1350 : : pte_t pteval;
1351 : : struct page *subpage;
1352 : : bool ret = true;
1353 : : struct mmu_notifier_range range;
1354 : 0 : enum ttu_flags flags = (enum ttu_flags)arg;
1355 : :
1356 : : /* munlock has nothing to gain from examining un-locked vmas */
1357 [ # # # # ]: 0 : if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED))
1358 : : return true;
1359 : :
1360 : : if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION) &&
1361 : : is_zone_device_page(page) && !is_device_private_page(page))
1362 : : return true;
1363 : :
1364 : : if (flags & TTU_SPLIT_HUGE_PMD) {
1365 : : split_huge_pmd_address(vma, address,
1366 : : flags & TTU_SPLIT_FREEZE, page);
1367 : : }
1368 : :
1369 : : /*
1370 : : * For THP, we have to assume the worse case ie pmd for invalidation.
1371 : : * For hugetlb, it could be much worse if we need to do pud
1372 : : * invalidation in the case of pmd sharing.
1373 : : *
1374 : : * Note that the page can not be free in this function as call of
1375 : : * try_to_unmap() must hold a reference on the page.
1376 : : */
1377 : : mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1378 : : address,
1379 : : min(vma->vm_end, address + page_size(page)));
1380 : : if (PageHuge(page)) {
1381 : : /*
1382 : : * If sharing is possible, start and end will be adjusted
1383 : : * accordingly.
1384 : : */
1385 : : adjust_range_if_pmd_sharing_possible(vma, &range.start,
1386 : : &range.end);
1387 : : }
1388 : : mmu_notifier_invalidate_range_start(&range);
1389 : :
1390 [ # # ]: 0 : while (page_vma_mapped_walk(&pvmw)) {
1391 : : #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1392 : : /* PMD-mapped THP migration entry */
1393 : : if (!pvmw.pte && (flags & TTU_MIGRATION)) {
1394 : : VM_BUG_ON_PAGE(PageHuge(page) || !PageTransCompound(page), page);
1395 : :
1396 : : set_pmd_migration_entry(&pvmw, page);
1397 : : continue;
1398 : : }
1399 : : #endif
1400 : :
1401 : : /*
1402 : : * If the page is mlock()d, we cannot swap it out.
1403 : : * If it's recently referenced (perhaps page_referenced
1404 : : * skipped over this mm) then we should reactivate it.
1405 : : */
1406 [ # # ]: 0 : if (!(flags & TTU_IGNORE_MLOCK)) {
1407 [ # # ]: 0 : if (vma->vm_flags & VM_LOCKED) {
1408 : : /* PTE-mapped THP are never mlocked */
1409 : : if (!PageTransCompound(page)) {
1410 : : /*
1411 : : * Holding pte lock, we do *not* need
1412 : : * mmap_sem here
1413 : : */
1414 : 0 : mlock_vma_page(page);
1415 : : }
1416 : : ret = false;
1417 : : page_vma_mapped_walk_done(&pvmw);
1418 : : break;
1419 : : }
1420 [ # # ]: 0 : if (flags & TTU_MUNLOCK)
1421 : 0 : continue;
1422 : : }
1423 : :
1424 : : /* Unexpected PMD-mapped THP? */
1425 : : VM_BUG_ON_PAGE(!pvmw.pte, page);
1426 : :
1427 : 0 : subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte);
1428 : 0 : address = pvmw.address;
1429 : :
1430 : : if (PageHuge(page)) {
1431 : : if (huge_pmd_unshare(mm, &address, pvmw.pte)) {
1432 : : /*
1433 : : * huge_pmd_unshare unmapped an entire PMD
1434 : : * page. There is no way of knowing exactly
1435 : : * which PMDs may be cached for this mm, so
1436 : : * we must flush them all. start/end were
1437 : : * already adjusted above to cover this range.
1438 : : */
1439 : : flush_cache_range(vma, range.start, range.end);
1440 : : flush_tlb_range(vma, range.start, range.end);
1441 : : mmu_notifier_invalidate_range(mm, range.start,
1442 : : range.end);
1443 : :
1444 : : /*
1445 : : * The ref count of the PMD page was dropped
1446 : : * which is part of the way map counting
1447 : : * is done for shared PMDs. Return 'true'
1448 : : * here. When there is no other sharing,
1449 : : * huge_pmd_unshare returns false and we will
1450 : : * unmap the actual page and drop map count
1451 : : * to zero.
1452 : : */
1453 : : page_vma_mapped_walk_done(&pvmw);
1454 : : break;
1455 : : }
1456 : : }
1457 : :
1458 : : if (IS_ENABLED(CONFIG_MIGRATION) &&
1459 : : (flags & TTU_MIGRATION) &&
1460 : : is_zone_device_page(page)) {
1461 : : swp_entry_t entry;
1462 : : pte_t swp_pte;
1463 : :
1464 : : pteval = ptep_get_and_clear(mm, pvmw.address, pvmw.pte);
1465 : :
1466 : : /*
1467 : : * Store the pfn of the page in a special migration
1468 : : * pte. do_swap_page() will wait until the migration
1469 : : * pte is removed and then restart fault handling.
1470 : : */
1471 : : entry = make_migration_entry(page, 0);
1472 : : swp_pte = swp_entry_to_pte(entry);
1473 : : if (pte_soft_dirty(pteval))
1474 : : swp_pte = pte_swp_mksoft_dirty(swp_pte);
1475 : : set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte);
1476 : : /*
1477 : : * No need to invalidate here it will synchronize on
1478 : : * against the special swap migration pte.
1479 : : *
1480 : : * The assignment to subpage above was computed from a
1481 : : * swap PTE which results in an invalid pointer.
1482 : : * Since only PAGE_SIZE pages can currently be
1483 : : * migrated, just set it to page. This will need to be
1484 : : * changed when hugepage migrations to device private
1485 : : * memory are supported.
1486 : : */
1487 : : subpage = page;
1488 : : goto discard;
1489 : : }
1490 : :
1491 [ # # ]: 0 : if (!(flags & TTU_IGNORE_ACCESS)) {
1492 [ # # ]: 0 : if (ptep_clear_flush_young_notify(vma, address,
1493 : : pvmw.pte)) {
1494 : : ret = false;
1495 : : page_vma_mapped_walk_done(&pvmw);
1496 : : break;
1497 : : }
1498 : : }
1499 : :
1500 : : /* Nuke the page table entry. */
1501 : 0 : flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
1502 : : if (should_defer_flush(mm, flags)) {
1503 : : /*
1504 : : * We clear the PTE but do not flush so potentially
1505 : : * a remote CPU could still be writing to the page.
1506 : : * If the entry was previously clean then the
1507 : : * architecture must guarantee that a clear->dirty
1508 : : * transition on a cached TLB entry is written through
1509 : : * and traps if the PTE is unmapped.
1510 : : */
1511 : : pteval = ptep_get_and_clear(mm, address, pvmw.pte);
1512 : :
1513 : : set_tlb_ubc_flush_pending(mm, pte_dirty(pteval));
1514 : : } else {
1515 : 0 : pteval = ptep_clear_flush(vma, address, pvmw.pte);
1516 : : }
1517 : :
1518 : : /* Move the dirty bit to the page. Now the pte is gone. */
1519 [ # # ]: 0 : if (pte_dirty(pteval))
1520 : 0 : set_page_dirty(page);
1521 : :
1522 : : /* Update high watermark before we lower rss */
1523 : : update_hiwater_rss(mm);
1524 : :
1525 : : if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
1526 : : pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
1527 : : if (PageHuge(page)) {
1528 : : hugetlb_count_sub(compound_nr(page), mm);
1529 : : set_huge_swap_pte_at(mm, address,
1530 : : pvmw.pte, pteval,
1531 : : vma_mmu_pagesize(vma));
1532 : : } else {
1533 : : dec_mm_counter(mm, mm_counter(page));
1534 : : set_pte_at(mm, address, pvmw.pte, pteval);
1535 : : }
1536 : :
1537 : : } else if (pte_unused(pteval) && !userfaultfd_armed(vma)) {
1538 : : /*
1539 : : * The guest indicated that the page content is of no
1540 : : * interest anymore. Simply discard the pte, vmscan
1541 : : * will take care of the rest.
1542 : : * A future reference will then fault in a new zero
1543 : : * page. When userfaultfd is active, we must not drop
1544 : : * this page though, as its main user (postcopy
1545 : : * migration) will not expect userfaults on already
1546 : : * copied pages.
1547 : : */
1548 : : dec_mm_counter(mm, mm_counter(page));
1549 : : /* We have to invalidate as we cleared the pte */
1550 : : mmu_notifier_invalidate_range(mm, address,
1551 : : address + PAGE_SIZE);
1552 [ # # ]: 0 : } else if (IS_ENABLED(CONFIG_MIGRATION) &&
1553 : 0 : (flags & (TTU_MIGRATION|TTU_SPLIT_FREEZE))) {
1554 : : swp_entry_t entry;
1555 : : pte_t swp_pte;
1556 : :
1557 : : if (arch_unmap_one(mm, vma, address, pteval) < 0) {
1558 : : set_pte_at(mm, address, pvmw.pte, pteval);
1559 : : ret = false;
1560 : : page_vma_mapped_walk_done(&pvmw);
1561 : : break;
1562 : : }
1563 : :
1564 : : /*
1565 : : * Store the pfn of the page in a special migration
1566 : : * pte. do_swap_page() will wait until the migration
1567 : : * pte is removed and then restart fault handling.
1568 : : */
1569 : 0 : entry = make_migration_entry(subpage,
1570 : 0 : pte_write(pteval));
1571 : : swp_pte = swp_entry_to_pte(entry);
1572 : : if (pte_soft_dirty(pteval))
1573 : : swp_pte = pte_swp_mksoft_dirty(swp_pte);
1574 : 0 : set_pte_at(mm, address, pvmw.pte, swp_pte);
1575 : : /*
1576 : : * No need to invalidate here it will synchronize on
1577 : : * against the special swap migration pte.
1578 : : */
1579 [ # # ]: 0 : } else if (PageAnon(page)) {
1580 : 0 : swp_entry_t entry = { .val = page_private(subpage) };
1581 : : pte_t swp_pte;
1582 : : /*
1583 : : * Store the swap location in the pte.
1584 : : * See handle_pte_fault() ...
1585 : : */
1586 [ # # ]: 0 : if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) {
1587 [ # # ]: 0 : WARN_ON_ONCE(1);
1588 : : ret = false;
1589 : : /* We have to invalidate as we cleared the pte */
1590 : : mmu_notifier_invalidate_range(mm, address,
1591 : : address + PAGE_SIZE);
1592 : : page_vma_mapped_walk_done(&pvmw);
1593 : : break;
1594 : : }
1595 : :
1596 : : /* MADV_FREE page check */
1597 [ # # ]: 0 : if (!PageSwapBacked(page)) {
1598 [ # # ]: 0 : if (!PageDirty(page)) {
1599 : : /* Invalidate as we cleared the pte */
1600 : : mmu_notifier_invalidate_range(mm,
1601 : : address, address + PAGE_SIZE);
1602 : : dec_mm_counter(mm, MM_ANONPAGES);
1603 : : goto discard;
1604 : : }
1605 : :
1606 : : /*
1607 : : * If the page was redirtied, it cannot be
1608 : : * discarded. Remap the page to page table.
1609 : : */
1610 : 0 : set_pte_at(mm, address, pvmw.pte, pteval);
1611 : : SetPageSwapBacked(page);
1612 : : ret = false;
1613 : : page_vma_mapped_walk_done(&pvmw);
1614 : : break;
1615 : : }
1616 : :
1617 [ # # ]: 0 : if (swap_duplicate(entry) < 0) {
1618 : 0 : set_pte_at(mm, address, pvmw.pte, pteval);
1619 : : ret = false;
1620 : : page_vma_mapped_walk_done(&pvmw);
1621 : : break;
1622 : : }
1623 : : if (arch_unmap_one(mm, vma, address, pteval) < 0) {
1624 : : set_pte_at(mm, address, pvmw.pte, pteval);
1625 : : ret = false;
1626 : : page_vma_mapped_walk_done(&pvmw);
1627 : : break;
1628 : : }
1629 [ # # ]: 0 : if (list_empty(&mm->mmlist)) {
1630 : : spin_lock(&mmlist_lock);
1631 [ # # ]: 0 : if (list_empty(&mm->mmlist))
1632 : : list_add(&mm->mmlist, &init_mm.mmlist);
1633 : : spin_unlock(&mmlist_lock);
1634 : : }
1635 : : dec_mm_counter(mm, MM_ANONPAGES);
1636 : : inc_mm_counter(mm, MM_SWAPENTS);
1637 : : swp_pte = swp_entry_to_pte(entry);
1638 : : if (pte_soft_dirty(pteval))
1639 : : swp_pte = pte_swp_mksoft_dirty(swp_pte);
1640 : 0 : set_pte_at(mm, address, pvmw.pte, swp_pte);
1641 : : /* Invalidate as we cleared the pte */
1642 : : mmu_notifier_invalidate_range(mm, address,
1643 : : address + PAGE_SIZE);
1644 : : } else {
1645 : : /*
1646 : : * This is a locked file-backed page, thus it cannot
1647 : : * be removed from the page cache and replaced by a new
1648 : : * page before mmu_notifier_invalidate_range_end, so no
1649 : : * concurrent thread might update its page table to
1650 : : * point at new page while a device still is using this
1651 : : * page.
1652 : : *
1653 : : * See Documentation/vm/mmu_notifier.rst
1654 : : */
1655 : 0 : dec_mm_counter(mm, mm_counter_file(page));
1656 : : }
1657 : : discard:
1658 : : /*
1659 : : * No need to call mmu_notifier_invalidate_range() it has be
1660 : : * done above for all cases requiring it to happen under page
1661 : : * table lock before mmu_notifier_invalidate_range_end()
1662 : : *
1663 : : * See Documentation/vm/mmu_notifier.rst
1664 : : */
1665 : 0 : page_remove_rmap(subpage, PageHuge(page));
1666 : 0 : put_page(page);
1667 : : }
1668 : :
1669 : : mmu_notifier_invalidate_range_end(&range);
1670 : :
1671 : 0 : return ret;
1672 : : }
1673 : :
1674 : 0 : bool is_vma_temporary_stack(struct vm_area_struct *vma)
1675 : : {
1676 : 0 : int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
1677 : :
1678 [ # # # # ]: 0 : if (!maybe_stack)
1679 : : return false;
1680 : :
1681 [ # # # # ]: 0 : if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) ==
1682 : : VM_STACK_INCOMPLETE_SETUP)
1683 : : return true;
1684 : :
1685 : 0 : return false;
1686 : : }
1687 : :
1688 : 0 : static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
1689 : : {
1690 : 0 : return is_vma_temporary_stack(vma);
1691 : : }
1692 : :
1693 : 0 : static int page_mapcount_is_zero(struct page *page)
1694 : : {
1695 : 0 : return !total_mapcount(page);
1696 : : }
1697 : :
1698 : : /**
1699 : : * try_to_unmap - try to remove all page table mappings to a page
1700 : : * @page: the page to get unmapped
1701 : : * @flags: action and flags
1702 : : *
1703 : : * Tries to remove all the page table entries which are mapping this
1704 : : * page, used in the pageout path. Caller must hold the page lock.
1705 : : *
1706 : : * If unmap is successful, return true. Otherwise, false.
1707 : : */
1708 : 0 : bool try_to_unmap(struct page *page, enum ttu_flags flags)
1709 : : {
1710 : 0 : struct rmap_walk_control rwc = {
1711 : : .rmap_one = try_to_unmap_one,
1712 : 0 : .arg = (void *)flags,
1713 : : .done = page_mapcount_is_zero,
1714 : : .anon_lock = page_lock_anon_vma_read,
1715 : : };
1716 : :
1717 : : /*
1718 : : * During exec, a temporary VMA is setup and later moved.
1719 : : * The VMA is moved under the anon_vma lock but not the
1720 : : * page tables leading to a race where migration cannot
1721 : : * find the migration ptes. Rather than increasing the
1722 : : * locking requirements of exec(), migration skips
1723 : : * temporary VMAs until after exec() completes.
1724 : : */
1725 [ # # ]: 0 : if ((flags & (TTU_MIGRATION|TTU_SPLIT_FREEZE))
1726 [ # # ]: 0 : && !PageKsm(page) && PageAnon(page))
1727 : 0 : rwc.invalid_vma = invalid_migration_vma;
1728 : :
1729 [ # # ]: 0 : if (flags & TTU_RMAP_LOCKED)
1730 : 0 : rmap_walk_locked(page, &rwc);
1731 : : else
1732 : 0 : rmap_walk(page, &rwc);
1733 : :
1734 : 0 : return !page_mapcount(page) ? true : false;
1735 : : }
1736 : :
1737 : 0 : static int page_not_mapped(struct page *page)
1738 : : {
1739 : 0 : return !page_mapped(page);
1740 : : };
1741 : :
1742 : : /**
1743 : : * try_to_munlock - try to munlock a page
1744 : : * @page: the page to be munlocked
1745 : : *
1746 : : * Called from munlock code. Checks all of the VMAs mapping the page
1747 : : * to make sure nobody else has this page mlocked. The page will be
1748 : : * returned with PG_mlocked cleared if no other vmas have it mlocked.
1749 : : */
1750 : :
1751 : 0 : void try_to_munlock(struct page *page)
1752 : : {
1753 : 0 : struct rmap_walk_control rwc = {
1754 : : .rmap_one = try_to_unmap_one,
1755 : : .arg = (void *)TTU_MUNLOCK,
1756 : : .done = page_not_mapped,
1757 : : .anon_lock = page_lock_anon_vma_read,
1758 : :
1759 : : };
1760 : :
1761 : : VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page);
1762 : : VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);
1763 : :
1764 : 0 : rmap_walk(page, &rwc);
1765 : 0 : }
1766 : :
1767 : 10552524 : void __put_anon_vma(struct anon_vma *anon_vma)
1768 : : {
1769 : 10552524 : struct anon_vma *root = anon_vma->root;
1770 : :
1771 : 10552524 : anon_vma_free(anon_vma);
1772 [ + + - + ]: 18212877 : if (root != anon_vma && atomic_dec_and_test(&root->refcount))
1773 : 0 : anon_vma_free(root);
1774 : 10552241 : }
1775 : :
1776 : 0 : static struct anon_vma *rmap_walk_anon_lock(struct page *page,
1777 : : struct rmap_walk_control *rwc)
1778 : : {
1779 : : struct anon_vma *anon_vma;
1780 : :
1781 [ # # ]: 0 : if (rwc->anon_lock)
1782 : 0 : return rwc->anon_lock(page);
1783 : :
1784 : : /*
1785 : : * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
1786 : : * because that depends on page_mapped(); but not all its usages
1787 : : * are holding mmap_sem. Users without mmap_sem are required to
1788 : : * take a reference count to prevent the anon_vma disappearing
1789 : : */
1790 : 0 : anon_vma = page_anon_vma(page);
1791 [ # # ]: 0 : if (!anon_vma)
1792 : : return NULL;
1793 : :
1794 : : anon_vma_lock_read(anon_vma);
1795 : 0 : return anon_vma;
1796 : : }
1797 : :
1798 : : /*
1799 : : * rmap_walk_anon - do something to anonymous page using the object-based
1800 : : * rmap method
1801 : : * @page: the page to be handled
1802 : : * @rwc: control variable according to each walk type
1803 : : *
1804 : : * Find all the mappings of a page using the mapping pointer and the vma chains
1805 : : * contained in the anon_vma struct it points to.
1806 : : *
1807 : : * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1808 : : * where the page was found will be held for write. So, we won't recheck
1809 : : * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1810 : : * LOCKED.
1811 : : */
1812 : 0 : static void rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc,
1813 : : bool locked)
1814 : : {
1815 : : struct anon_vma *anon_vma;
1816 : : pgoff_t pgoff_start, pgoff_end;
1817 : : struct anon_vma_chain *avc;
1818 : :
1819 [ # # ]: 0 : if (locked) {
1820 : 0 : anon_vma = page_anon_vma(page);
1821 : : /* anon_vma disappear under us? */
1822 : : VM_BUG_ON_PAGE(!anon_vma, page);
1823 : : } else {
1824 : 0 : anon_vma = rmap_walk_anon_lock(page, rwc);
1825 : : }
1826 [ # # ]: 0 : if (!anon_vma)
1827 : 0 : return;
1828 : :
1829 : : pgoff_start = page_to_pgoff(page);
1830 : : pgoff_end = pgoff_start + hpage_nr_pages(page) - 1;
1831 [ # # ]: 0 : anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root,
1832 : : pgoff_start, pgoff_end) {
1833 : 0 : struct vm_area_struct *vma = avc->vma;
1834 : : unsigned long address = vma_address(page, vma);
1835 : :
1836 : 0 : cond_resched();
1837 : :
1838 [ # # # # ]: 0 : if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
1839 : 0 : continue;
1840 : :
1841 [ # # ]: 0 : if (!rwc->rmap_one(page, vma, address, rwc->arg))
1842 : : break;
1843 [ # # # # ]: 0 : if (rwc->done && rwc->done(page))
1844 : : break;
1845 : : }
1846 : :
1847 [ # # ]: 0 : if (!locked)
1848 : : anon_vma_unlock_read(anon_vma);
1849 : : }
1850 : :
1851 : : /*
1852 : : * rmap_walk_file - do something to file page using the object-based rmap method
1853 : : * @page: the page to be handled
1854 : : * @rwc: control variable according to each walk type
1855 : : *
1856 : : * Find all the mappings of a page using the mapping pointer and the vma chains
1857 : : * contained in the address_space struct it points to.
1858 : : *
1859 : : * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1860 : : * where the page was found will be held for write. So, we won't recheck
1861 : : * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1862 : : * LOCKED.
1863 : : */
1864 : 140 : static void rmap_walk_file(struct page *page, struct rmap_walk_control *rwc,
1865 : : bool locked)
1866 : : {
1867 : 140 : struct address_space *mapping = page_mapping(page);
1868 : : pgoff_t pgoff_start, pgoff_end;
1869 : : struct vm_area_struct *vma;
1870 : :
1871 : : /*
1872 : : * The page lock not only makes sure that page->mapping cannot
1873 : : * suddenly be NULLified by truncation, it makes sure that the
1874 : : * structure at mapping cannot be freed and reused yet,
1875 : : * so we can safely take mapping->i_mmap_rwsem.
1876 : : */
1877 : : VM_BUG_ON_PAGE(!PageLocked(page), page);
1878 : :
1879 [ + - ]: 140 : if (!mapping)
1880 : 140 : return;
1881 : :
1882 : : pgoff_start = page_to_pgoff(page);
1883 : : pgoff_end = pgoff_start + hpage_nr_pages(page) - 1;
1884 [ + - ]: 140 : if (!locked)
1885 : : i_mmap_lock_read(mapping);
1886 [ + + ]: 280 : vma_interval_tree_foreach(vma, &mapping->i_mmap,
1887 : : pgoff_start, pgoff_end) {
1888 : : unsigned long address = vma_address(page, vma);
1889 : :
1890 : 140 : cond_resched();
1891 : :
1892 [ + - - + ]: 140 : if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
1893 : 0 : continue;
1894 : :
1895 [ + - ]: 140 : if (!rwc->rmap_one(page, vma, address, rwc->arg))
1896 : : goto done;
1897 [ - + # # ]: 140 : if (rwc->done && rwc->done(page))
1898 : : goto done;
1899 : : }
1900 : :
1901 : : done:
1902 [ + - ]: 140 : if (!locked)
1903 : : i_mmap_unlock_read(mapping);
1904 : : }
1905 : :
1906 : 140 : void rmap_walk(struct page *page, struct rmap_walk_control *rwc)
1907 : : {
1908 : : if (unlikely(PageKsm(page)))
1909 : : rmap_walk_ksm(page, rwc);
1910 [ - + ]: 140 : else if (PageAnon(page))
1911 : 0 : rmap_walk_anon(page, rwc, false);
1912 : : else
1913 : 140 : rmap_walk_file(page, rwc, false);
1914 : 140 : }
1915 : :
1916 : : /* Like rmap_walk, but caller holds relevant rmap lock */
1917 : 0 : void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc)
1918 : : {
1919 : : /* no ksm support for now */
1920 : : VM_BUG_ON_PAGE(PageKsm(page), page);
1921 [ # # ]: 0 : if (PageAnon(page))
1922 : 0 : rmap_walk_anon(page, rwc, true);
1923 : : else
1924 : 0 : rmap_walk_file(page, rwc, true);
1925 : 0 : }
1926 : :
1927 : : #ifdef CONFIG_HUGETLB_PAGE
1928 : : /*
1929 : : * The following two functions are for anonymous (private mapped) hugepages.
1930 : : * Unlike common anonymous pages, anonymous hugepages have no accounting code
1931 : : * and no lru code, because we handle hugepages differently from common pages.
1932 : : */
1933 : : void hugepage_add_anon_rmap(struct page *page,
1934 : : struct vm_area_struct *vma, unsigned long address)
1935 : : {
1936 : : struct anon_vma *anon_vma = vma->anon_vma;
1937 : : int first;
1938 : :
1939 : : BUG_ON(!PageLocked(page));
1940 : : BUG_ON(!anon_vma);
1941 : : /* address might be in next vma when migration races vma_adjust */
1942 : : first = atomic_inc_and_test(compound_mapcount_ptr(page));
1943 : : if (first)
1944 : : __page_set_anon_rmap(page, vma, address, 0);
1945 : : }
1946 : :
1947 : : void hugepage_add_new_anon_rmap(struct page *page,
1948 : : struct vm_area_struct *vma, unsigned long address)
1949 : : {
1950 : : BUG_ON(address < vma->vm_start || address >= vma->vm_end);
1951 : : atomic_set(compound_mapcount_ptr(page), 0);
1952 : : __page_set_anon_rmap(page, vma, address, 1);
1953 : : }
1954 : : #endif /* CONFIG_HUGETLB_PAGE */
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