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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
b46e756f KS |
2 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
3 | ||
4 | #include <linux/mm.h> | |
5 | #include <linux/sched.h> | |
6e84f315 | 6 | #include <linux/sched/mm.h> |
f7ccbae4 | 7 | #include <linux/sched/coredump.h> |
b46e756f KS |
8 | #include <linux/mmu_notifier.h> |
9 | #include <linux/rmap.h> | |
10 | #include <linux/swap.h> | |
11 | #include <linux/mm_inline.h> | |
12 | #include <linux/kthread.h> | |
13 | #include <linux/khugepaged.h> | |
14 | #include <linux/freezer.h> | |
15 | #include <linux/mman.h> | |
16 | #include <linux/hashtable.h> | |
17 | #include <linux/userfaultfd_k.h> | |
18 | #include <linux/page_idle.h> | |
19 | #include <linux/swapops.h> | |
f3f0e1d2 | 20 | #include <linux/shmem_fs.h> |
b46e756f KS |
21 | |
22 | #include <asm/tlb.h> | |
23 | #include <asm/pgalloc.h> | |
24 | #include "internal.h" | |
25 | ||
26 | enum scan_result { | |
27 | SCAN_FAIL, | |
28 | SCAN_SUCCEED, | |
29 | SCAN_PMD_NULL, | |
30 | SCAN_EXCEED_NONE_PTE, | |
31 | SCAN_PTE_NON_PRESENT, | |
32 | SCAN_PAGE_RO, | |
0db501f7 | 33 | SCAN_LACK_REFERENCED_PAGE, |
b46e756f KS |
34 | SCAN_PAGE_NULL, |
35 | SCAN_SCAN_ABORT, | |
36 | SCAN_PAGE_COUNT, | |
37 | SCAN_PAGE_LRU, | |
38 | SCAN_PAGE_LOCK, | |
39 | SCAN_PAGE_ANON, | |
40 | SCAN_PAGE_COMPOUND, | |
41 | SCAN_ANY_PROCESS, | |
42 | SCAN_VMA_NULL, | |
43 | SCAN_VMA_CHECK, | |
44 | SCAN_ADDRESS_RANGE, | |
45 | SCAN_SWAP_CACHE_PAGE, | |
46 | SCAN_DEL_PAGE_LRU, | |
47 | SCAN_ALLOC_HUGE_PAGE_FAIL, | |
48 | SCAN_CGROUP_CHARGE_FAIL, | |
f3f0e1d2 KS |
49 | SCAN_EXCEED_SWAP_PTE, |
50 | SCAN_TRUNCATED, | |
99cb0dbd | 51 | SCAN_PAGE_HAS_PRIVATE, |
b46e756f KS |
52 | }; |
53 | ||
54 | #define CREATE_TRACE_POINTS | |
55 | #include <trace/events/huge_memory.h> | |
56 | ||
57 | /* default scan 8*512 pte (or vmas) every 30 second */ | |
58 | static unsigned int khugepaged_pages_to_scan __read_mostly; | |
59 | static unsigned int khugepaged_pages_collapsed; | |
60 | static unsigned int khugepaged_full_scans; | |
61 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
62 | /* during fragmentation poll the hugepage allocator once every minute */ | |
63 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
64 | static unsigned long khugepaged_sleep_expire; | |
65 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
66 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
67 | /* | |
68 | * default collapse hugepages if there is at least one pte mapped like | |
69 | * it would have happened if the vma was large enough during page | |
70 | * fault. | |
71 | */ | |
72 | static unsigned int khugepaged_max_ptes_none __read_mostly; | |
73 | static unsigned int khugepaged_max_ptes_swap __read_mostly; | |
74 | ||
75 | #define MM_SLOTS_HASH_BITS 10 | |
76 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
77 | ||
78 | static struct kmem_cache *mm_slot_cache __read_mostly; | |
79 | ||
80 | /** | |
81 | * struct mm_slot - hash lookup from mm to mm_slot | |
82 | * @hash: hash collision list | |
83 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
84 | * @mm: the mm that this information is valid for | |
85 | */ | |
86 | struct mm_slot { | |
87 | struct hlist_node hash; | |
88 | struct list_head mm_node; | |
89 | struct mm_struct *mm; | |
90 | }; | |
91 | ||
92 | /** | |
93 | * struct khugepaged_scan - cursor for scanning | |
94 | * @mm_head: the head of the mm list to scan | |
95 | * @mm_slot: the current mm_slot we are scanning | |
96 | * @address: the next address inside that to be scanned | |
97 | * | |
98 | * There is only the one khugepaged_scan instance of this cursor structure. | |
99 | */ | |
100 | struct khugepaged_scan { | |
101 | struct list_head mm_head; | |
102 | struct mm_slot *mm_slot; | |
103 | unsigned long address; | |
104 | }; | |
105 | ||
106 | static struct khugepaged_scan khugepaged_scan = { | |
107 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), | |
108 | }; | |
109 | ||
e1465d12 | 110 | #ifdef CONFIG_SYSFS |
b46e756f KS |
111 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, |
112 | struct kobj_attribute *attr, | |
113 | char *buf) | |
114 | { | |
115 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
116 | } | |
117 | ||
118 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
119 | struct kobj_attribute *attr, | |
120 | const char *buf, size_t count) | |
121 | { | |
122 | unsigned long msecs; | |
123 | int err; | |
124 | ||
125 | err = kstrtoul(buf, 10, &msecs); | |
126 | if (err || msecs > UINT_MAX) | |
127 | return -EINVAL; | |
128 | ||
129 | khugepaged_scan_sleep_millisecs = msecs; | |
130 | khugepaged_sleep_expire = 0; | |
131 | wake_up_interruptible(&khugepaged_wait); | |
132 | ||
133 | return count; | |
134 | } | |
135 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
136 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
137 | scan_sleep_millisecs_store); | |
138 | ||
139 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
140 | struct kobj_attribute *attr, | |
141 | char *buf) | |
142 | { | |
143 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
144 | } | |
145 | ||
146 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
147 | struct kobj_attribute *attr, | |
148 | const char *buf, size_t count) | |
149 | { | |
150 | unsigned long msecs; | |
151 | int err; | |
152 | ||
153 | err = kstrtoul(buf, 10, &msecs); | |
154 | if (err || msecs > UINT_MAX) | |
155 | return -EINVAL; | |
156 | ||
157 | khugepaged_alloc_sleep_millisecs = msecs; | |
158 | khugepaged_sleep_expire = 0; | |
159 | wake_up_interruptible(&khugepaged_wait); | |
160 | ||
161 | return count; | |
162 | } | |
163 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
164 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
165 | alloc_sleep_millisecs_store); | |
166 | ||
167 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
168 | struct kobj_attribute *attr, | |
169 | char *buf) | |
170 | { | |
171 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
172 | } | |
173 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
174 | struct kobj_attribute *attr, | |
175 | const char *buf, size_t count) | |
176 | { | |
177 | int err; | |
178 | unsigned long pages; | |
179 | ||
180 | err = kstrtoul(buf, 10, &pages); | |
181 | if (err || !pages || pages > UINT_MAX) | |
182 | return -EINVAL; | |
183 | ||
184 | khugepaged_pages_to_scan = pages; | |
185 | ||
186 | return count; | |
187 | } | |
188 | static struct kobj_attribute pages_to_scan_attr = | |
189 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
190 | pages_to_scan_store); | |
191 | ||
192 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
193 | struct kobj_attribute *attr, | |
194 | char *buf) | |
195 | { | |
196 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
197 | } | |
198 | static struct kobj_attribute pages_collapsed_attr = | |
199 | __ATTR_RO(pages_collapsed); | |
200 | ||
201 | static ssize_t full_scans_show(struct kobject *kobj, | |
202 | struct kobj_attribute *attr, | |
203 | char *buf) | |
204 | { | |
205 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
206 | } | |
207 | static struct kobj_attribute full_scans_attr = | |
208 | __ATTR_RO(full_scans); | |
209 | ||
210 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
211 | struct kobj_attribute *attr, char *buf) | |
212 | { | |
213 | return single_hugepage_flag_show(kobj, attr, buf, | |
214 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
215 | } | |
216 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
217 | struct kobj_attribute *attr, | |
218 | const char *buf, size_t count) | |
219 | { | |
220 | return single_hugepage_flag_store(kobj, attr, buf, count, | |
221 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
222 | } | |
223 | static struct kobj_attribute khugepaged_defrag_attr = | |
224 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
225 | khugepaged_defrag_store); | |
226 | ||
227 | /* | |
228 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
229 | * any unmapped ptes in turn potentially increasing the memory | |
230 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
231 | * reduce the available free memory in the system as it | |
232 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
233 | * free memory in the system during the khugepaged scan. | |
234 | */ | |
235 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
236 | struct kobj_attribute *attr, | |
237 | char *buf) | |
238 | { | |
239 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
240 | } | |
241 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
242 | struct kobj_attribute *attr, | |
243 | const char *buf, size_t count) | |
244 | { | |
245 | int err; | |
246 | unsigned long max_ptes_none; | |
247 | ||
248 | err = kstrtoul(buf, 10, &max_ptes_none); | |
249 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
250 | return -EINVAL; | |
251 | ||
252 | khugepaged_max_ptes_none = max_ptes_none; | |
253 | ||
254 | return count; | |
255 | } | |
256 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
257 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
258 | khugepaged_max_ptes_none_store); | |
259 | ||
260 | static ssize_t khugepaged_max_ptes_swap_show(struct kobject *kobj, | |
261 | struct kobj_attribute *attr, | |
262 | char *buf) | |
263 | { | |
264 | return sprintf(buf, "%u\n", khugepaged_max_ptes_swap); | |
265 | } | |
266 | ||
267 | static ssize_t khugepaged_max_ptes_swap_store(struct kobject *kobj, | |
268 | struct kobj_attribute *attr, | |
269 | const char *buf, size_t count) | |
270 | { | |
271 | int err; | |
272 | unsigned long max_ptes_swap; | |
273 | ||
274 | err = kstrtoul(buf, 10, &max_ptes_swap); | |
275 | if (err || max_ptes_swap > HPAGE_PMD_NR-1) | |
276 | return -EINVAL; | |
277 | ||
278 | khugepaged_max_ptes_swap = max_ptes_swap; | |
279 | ||
280 | return count; | |
281 | } | |
282 | ||
283 | static struct kobj_attribute khugepaged_max_ptes_swap_attr = | |
284 | __ATTR(max_ptes_swap, 0644, khugepaged_max_ptes_swap_show, | |
285 | khugepaged_max_ptes_swap_store); | |
286 | ||
287 | static struct attribute *khugepaged_attr[] = { | |
288 | &khugepaged_defrag_attr.attr, | |
289 | &khugepaged_max_ptes_none_attr.attr, | |
290 | &pages_to_scan_attr.attr, | |
291 | &pages_collapsed_attr.attr, | |
292 | &full_scans_attr.attr, | |
293 | &scan_sleep_millisecs_attr.attr, | |
294 | &alloc_sleep_millisecs_attr.attr, | |
295 | &khugepaged_max_ptes_swap_attr.attr, | |
296 | NULL, | |
297 | }; | |
298 | ||
299 | struct attribute_group khugepaged_attr_group = { | |
300 | .attrs = khugepaged_attr, | |
301 | .name = "khugepaged", | |
302 | }; | |
e1465d12 | 303 | #endif /* CONFIG_SYSFS */ |
b46e756f | 304 | |
f3f0e1d2 | 305 | #define VM_NO_KHUGEPAGED (VM_SPECIAL | VM_HUGETLB) |
b46e756f KS |
306 | |
307 | int hugepage_madvise(struct vm_area_struct *vma, | |
308 | unsigned long *vm_flags, int advice) | |
309 | { | |
310 | switch (advice) { | |
311 | case MADV_HUGEPAGE: | |
312 | #ifdef CONFIG_S390 | |
313 | /* | |
314 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
315 | * can't handle this properly after s390_enable_sie, so we simply | |
316 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
317 | */ | |
318 | if (mm_has_pgste(vma->vm_mm)) | |
319 | return 0; | |
320 | #endif | |
321 | *vm_flags &= ~VM_NOHUGEPAGE; | |
322 | *vm_flags |= VM_HUGEPAGE; | |
323 | /* | |
324 | * If the vma become good for khugepaged to scan, | |
325 | * register it here without waiting a page fault that | |
326 | * may not happen any time soon. | |
327 | */ | |
328 | if (!(*vm_flags & VM_NO_KHUGEPAGED) && | |
329 | khugepaged_enter_vma_merge(vma, *vm_flags)) | |
330 | return -ENOMEM; | |
331 | break; | |
332 | case MADV_NOHUGEPAGE: | |
333 | *vm_flags &= ~VM_HUGEPAGE; | |
334 | *vm_flags |= VM_NOHUGEPAGE; | |
335 | /* | |
336 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
337 | * this vma even if we leave the mm registered in khugepaged if | |
338 | * it got registered before VM_NOHUGEPAGE was set. | |
339 | */ | |
340 | break; | |
341 | } | |
342 | ||
343 | return 0; | |
344 | } | |
345 | ||
346 | int __init khugepaged_init(void) | |
347 | { | |
348 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
349 | sizeof(struct mm_slot), | |
350 | __alignof__(struct mm_slot), 0, NULL); | |
351 | if (!mm_slot_cache) | |
352 | return -ENOMEM; | |
353 | ||
354 | khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; | |
355 | khugepaged_max_ptes_none = HPAGE_PMD_NR - 1; | |
356 | khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8; | |
357 | ||
358 | return 0; | |
359 | } | |
360 | ||
361 | void __init khugepaged_destroy(void) | |
362 | { | |
363 | kmem_cache_destroy(mm_slot_cache); | |
364 | } | |
365 | ||
366 | static inline struct mm_slot *alloc_mm_slot(void) | |
367 | { | |
368 | if (!mm_slot_cache) /* initialization failed */ | |
369 | return NULL; | |
370 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
371 | } | |
372 | ||
373 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
374 | { | |
375 | kmem_cache_free(mm_slot_cache, mm_slot); | |
376 | } | |
377 | ||
378 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
379 | { | |
380 | struct mm_slot *mm_slot; | |
381 | ||
382 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) | |
383 | if (mm == mm_slot->mm) | |
384 | return mm_slot; | |
385 | ||
386 | return NULL; | |
387 | } | |
388 | ||
389 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
390 | struct mm_slot *mm_slot) | |
391 | { | |
392 | mm_slot->mm = mm; | |
393 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); | |
394 | } | |
395 | ||
396 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
397 | { | |
398 | return atomic_read(&mm->mm_users) == 0; | |
399 | } | |
400 | ||
50f8b92f SL |
401 | static bool hugepage_vma_check(struct vm_area_struct *vma, |
402 | unsigned long vm_flags) | |
c2231020 | 403 | { |
50f8b92f SL |
404 | if ((!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || |
405 | (vm_flags & VM_NOHUGEPAGE) || | |
c2231020 YS |
406 | test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) |
407 | return false; | |
99cb0dbd SL |
408 | |
409 | if (shmem_file(vma->vm_file) || | |
410 | (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && | |
411 | vma->vm_file && | |
412 | (vm_flags & VM_DENYWRITE))) { | |
c2231020 YS |
413 | if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) |
414 | return false; | |
415 | return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, | |
416 | HPAGE_PMD_NR); | |
417 | } | |
418 | if (!vma->anon_vma || vma->vm_ops) | |
419 | return false; | |
420 | if (is_vma_temporary_stack(vma)) | |
421 | return false; | |
50f8b92f | 422 | return !(vm_flags & VM_NO_KHUGEPAGED); |
c2231020 YS |
423 | } |
424 | ||
b46e756f KS |
425 | int __khugepaged_enter(struct mm_struct *mm) |
426 | { | |
427 | struct mm_slot *mm_slot; | |
428 | int wakeup; | |
429 | ||
430 | mm_slot = alloc_mm_slot(); | |
431 | if (!mm_slot) | |
432 | return -ENOMEM; | |
433 | ||
434 | /* __khugepaged_exit() must not run from under us */ | |
435 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); | |
436 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { | |
437 | free_mm_slot(mm_slot); | |
438 | return 0; | |
439 | } | |
440 | ||
441 | spin_lock(&khugepaged_mm_lock); | |
442 | insert_to_mm_slots_hash(mm, mm_slot); | |
443 | /* | |
444 | * Insert just behind the scanning cursor, to let the area settle | |
445 | * down a little. | |
446 | */ | |
447 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
448 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
449 | spin_unlock(&khugepaged_mm_lock); | |
450 | ||
f1f10076 | 451 | mmgrab(mm); |
b46e756f KS |
452 | if (wakeup) |
453 | wake_up_interruptible(&khugepaged_wait); | |
454 | ||
455 | return 0; | |
456 | } | |
457 | ||
458 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, | |
459 | unsigned long vm_flags) | |
460 | { | |
461 | unsigned long hstart, hend; | |
c2231020 YS |
462 | |
463 | /* | |
99cb0dbd SL |
464 | * khugepaged only supports read-only files for non-shmem files. |
465 | * khugepaged does not yet work on special mappings. And | |
466 | * file-private shmem THP is not supported. | |
c2231020 | 467 | */ |
50f8b92f | 468 | if (!hugepage_vma_check(vma, vm_flags)) |
b46e756f | 469 | return 0; |
c2231020 | 470 | |
b46e756f KS |
471 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
472 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
473 | if (hstart < hend) | |
474 | return khugepaged_enter(vma, vm_flags); | |
475 | return 0; | |
476 | } | |
477 | ||
478 | void __khugepaged_exit(struct mm_struct *mm) | |
479 | { | |
480 | struct mm_slot *mm_slot; | |
481 | int free = 0; | |
482 | ||
483 | spin_lock(&khugepaged_mm_lock); | |
484 | mm_slot = get_mm_slot(mm); | |
485 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
486 | hash_del(&mm_slot->hash); | |
487 | list_del(&mm_slot->mm_node); | |
488 | free = 1; | |
489 | } | |
490 | spin_unlock(&khugepaged_mm_lock); | |
491 | ||
492 | if (free) { | |
493 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
494 | free_mm_slot(mm_slot); | |
495 | mmdrop(mm); | |
496 | } else if (mm_slot) { | |
497 | /* | |
498 | * This is required to serialize against | |
499 | * khugepaged_test_exit() (which is guaranteed to run | |
500 | * under mmap sem read mode). Stop here (after we | |
501 | * return all pagetables will be destroyed) until | |
502 | * khugepaged has finished working on the pagetables | |
503 | * under the mmap_sem. | |
504 | */ | |
505 | down_write(&mm->mmap_sem); | |
506 | up_write(&mm->mmap_sem); | |
507 | } | |
508 | } | |
509 | ||
510 | static void release_pte_page(struct page *page) | |
511 | { | |
d44d363f | 512 | dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); |
b46e756f KS |
513 | unlock_page(page); |
514 | putback_lru_page(page); | |
515 | } | |
516 | ||
517 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
518 | { | |
519 | while (--_pte >= pte) { | |
520 | pte_t pteval = *_pte; | |
521 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) | |
522 | release_pte_page(pte_page(pteval)); | |
523 | } | |
524 | } | |
525 | ||
526 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, | |
527 | unsigned long address, | |
528 | pte_t *pte) | |
529 | { | |
530 | struct page *page = NULL; | |
531 | pte_t *_pte; | |
0db501f7 EA |
532 | int none_or_zero = 0, result = 0, referenced = 0; |
533 | bool writable = false; | |
b46e756f KS |
534 | |
535 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
536 | _pte++, address += PAGE_SIZE) { | |
537 | pte_t pteval = *_pte; | |
538 | if (pte_none(pteval) || (pte_present(pteval) && | |
539 | is_zero_pfn(pte_pfn(pteval)))) { | |
540 | if (!userfaultfd_armed(vma) && | |
541 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
542 | continue; | |
543 | } else { | |
544 | result = SCAN_EXCEED_NONE_PTE; | |
545 | goto out; | |
546 | } | |
547 | } | |
548 | if (!pte_present(pteval)) { | |
549 | result = SCAN_PTE_NON_PRESENT; | |
550 | goto out; | |
551 | } | |
552 | page = vm_normal_page(vma, address, pteval); | |
553 | if (unlikely(!page)) { | |
554 | result = SCAN_PAGE_NULL; | |
555 | goto out; | |
556 | } | |
557 | ||
fece2029 KS |
558 | /* TODO: teach khugepaged to collapse THP mapped with pte */ |
559 | if (PageCompound(page)) { | |
560 | result = SCAN_PAGE_COMPOUND; | |
561 | goto out; | |
562 | } | |
563 | ||
b46e756f | 564 | VM_BUG_ON_PAGE(!PageAnon(page), page); |
b46e756f KS |
565 | |
566 | /* | |
567 | * We can do it before isolate_lru_page because the | |
568 | * page can't be freed from under us. NOTE: PG_lock | |
569 | * is needed to serialize against split_huge_page | |
570 | * when invoked from the VM. | |
571 | */ | |
572 | if (!trylock_page(page)) { | |
573 | result = SCAN_PAGE_LOCK; | |
574 | goto out; | |
575 | } | |
576 | ||
577 | /* | |
578 | * cannot use mapcount: can't collapse if there's a gup pin. | |
579 | * The page must only be referenced by the scanned process | |
580 | * and page swap cache. | |
581 | */ | |
2948be5a | 582 | if (page_count(page) != 1 + PageSwapCache(page)) { |
b46e756f KS |
583 | unlock_page(page); |
584 | result = SCAN_PAGE_COUNT; | |
585 | goto out; | |
586 | } | |
587 | if (pte_write(pteval)) { | |
588 | writable = true; | |
589 | } else { | |
590 | if (PageSwapCache(page) && | |
591 | !reuse_swap_page(page, NULL)) { | |
592 | unlock_page(page); | |
593 | result = SCAN_SWAP_CACHE_PAGE; | |
594 | goto out; | |
595 | } | |
596 | /* | |
597 | * Page is not in the swap cache. It can be collapsed | |
598 | * into a THP. | |
599 | */ | |
600 | } | |
601 | ||
602 | /* | |
603 | * Isolate the page to avoid collapsing an hugepage | |
604 | * currently in use by the VM. | |
605 | */ | |
606 | if (isolate_lru_page(page)) { | |
607 | unlock_page(page); | |
608 | result = SCAN_DEL_PAGE_LRU; | |
609 | goto out; | |
610 | } | |
d44d363f SL |
611 | inc_node_page_state(page, |
612 | NR_ISOLATED_ANON + page_is_file_cache(page)); | |
b46e756f KS |
613 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
614 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
615 | ||
0db501f7 | 616 | /* There should be enough young pte to collapse the page */ |
b46e756f KS |
617 | if (pte_young(pteval) || |
618 | page_is_young(page) || PageReferenced(page) || | |
619 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 620 | referenced++; |
b46e756f KS |
621 | } |
622 | if (likely(writable)) { | |
623 | if (likely(referenced)) { | |
624 | result = SCAN_SUCCEED; | |
625 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, | |
626 | referenced, writable, result); | |
627 | return 1; | |
628 | } | |
629 | } else { | |
630 | result = SCAN_PAGE_RO; | |
631 | } | |
632 | ||
633 | out: | |
634 | release_pte_pages(pte, _pte); | |
635 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, | |
636 | referenced, writable, result); | |
637 | return 0; | |
638 | } | |
639 | ||
640 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
641 | struct vm_area_struct *vma, | |
642 | unsigned long address, | |
643 | spinlock_t *ptl) | |
644 | { | |
645 | pte_t *_pte; | |
338a16ba DR |
646 | for (_pte = pte; _pte < pte + HPAGE_PMD_NR; |
647 | _pte++, page++, address += PAGE_SIZE) { | |
b46e756f KS |
648 | pte_t pteval = *_pte; |
649 | struct page *src_page; | |
650 | ||
651 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
652 | clear_user_highpage(page, address); | |
653 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
654 | if (is_zero_pfn(pte_pfn(pteval))) { | |
655 | /* | |
656 | * ptl mostly unnecessary. | |
657 | */ | |
658 | spin_lock(ptl); | |
659 | /* | |
660 | * paravirt calls inside pte_clear here are | |
661 | * superfluous. | |
662 | */ | |
663 | pte_clear(vma->vm_mm, address, _pte); | |
664 | spin_unlock(ptl); | |
665 | } | |
666 | } else { | |
667 | src_page = pte_page(pteval); | |
668 | copy_user_highpage(page, src_page, address, vma); | |
669 | VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page); | |
670 | release_pte_page(src_page); | |
671 | /* | |
672 | * ptl mostly unnecessary, but preempt has to | |
673 | * be disabled to update the per-cpu stats | |
674 | * inside page_remove_rmap(). | |
675 | */ | |
676 | spin_lock(ptl); | |
677 | /* | |
678 | * paravirt calls inside pte_clear here are | |
679 | * superfluous. | |
680 | */ | |
681 | pte_clear(vma->vm_mm, address, _pte); | |
682 | page_remove_rmap(src_page, false); | |
683 | spin_unlock(ptl); | |
684 | free_page_and_swap_cache(src_page); | |
685 | } | |
b46e756f KS |
686 | } |
687 | } | |
688 | ||
689 | static void khugepaged_alloc_sleep(void) | |
690 | { | |
691 | DEFINE_WAIT(wait); | |
692 | ||
693 | add_wait_queue(&khugepaged_wait, &wait); | |
694 | freezable_schedule_timeout_interruptible( | |
695 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
696 | remove_wait_queue(&khugepaged_wait, &wait); | |
697 | } | |
698 | ||
699 | static int khugepaged_node_load[MAX_NUMNODES]; | |
700 | ||
701 | static bool khugepaged_scan_abort(int nid) | |
702 | { | |
703 | int i; | |
704 | ||
705 | /* | |
a5f5f91d | 706 | * If node_reclaim_mode is disabled, then no extra effort is made to |
b46e756f KS |
707 | * allocate memory locally. |
708 | */ | |
a5f5f91d | 709 | if (!node_reclaim_mode) |
b46e756f KS |
710 | return false; |
711 | ||
712 | /* If there is a count for this node already, it must be acceptable */ | |
713 | if (khugepaged_node_load[nid]) | |
714 | return false; | |
715 | ||
716 | for (i = 0; i < MAX_NUMNODES; i++) { | |
717 | if (!khugepaged_node_load[i]) | |
718 | continue; | |
a55c7454 | 719 | if (node_distance(nid, i) > node_reclaim_distance) |
b46e756f KS |
720 | return true; |
721 | } | |
722 | return false; | |
723 | } | |
724 | ||
725 | /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */ | |
726 | static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void) | |
727 | { | |
25160354 | 728 | return khugepaged_defrag() ? GFP_TRANSHUGE : GFP_TRANSHUGE_LIGHT; |
b46e756f KS |
729 | } |
730 | ||
731 | #ifdef CONFIG_NUMA | |
732 | static int khugepaged_find_target_node(void) | |
733 | { | |
734 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
735 | int nid, target_node = 0, max_value = 0; | |
736 | ||
737 | /* find first node with max normal pages hit */ | |
738 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
739 | if (khugepaged_node_load[nid] > max_value) { | |
740 | max_value = khugepaged_node_load[nid]; | |
741 | target_node = nid; | |
742 | } | |
743 | ||
744 | /* do some balance if several nodes have the same hit record */ | |
745 | if (target_node <= last_khugepaged_target_node) | |
746 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
747 | nid++) | |
748 | if (max_value == khugepaged_node_load[nid]) { | |
749 | target_node = nid; | |
750 | break; | |
751 | } | |
752 | ||
753 | last_khugepaged_target_node = target_node; | |
754 | return target_node; | |
755 | } | |
756 | ||
757 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
758 | { | |
759 | if (IS_ERR(*hpage)) { | |
760 | if (!*wait) | |
761 | return false; | |
762 | ||
763 | *wait = false; | |
764 | *hpage = NULL; | |
765 | khugepaged_alloc_sleep(); | |
766 | } else if (*hpage) { | |
767 | put_page(*hpage); | |
768 | *hpage = NULL; | |
769 | } | |
770 | ||
771 | return true; | |
772 | } | |
773 | ||
774 | static struct page * | |
988ddb71 | 775 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f KS |
776 | { |
777 | VM_BUG_ON_PAGE(*hpage, *hpage); | |
778 | ||
b46e756f KS |
779 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); |
780 | if (unlikely(!*hpage)) { | |
781 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
782 | *hpage = ERR_PTR(-ENOMEM); | |
783 | return NULL; | |
784 | } | |
785 | ||
786 | prep_transhuge_page(*hpage); | |
787 | count_vm_event(THP_COLLAPSE_ALLOC); | |
788 | return *hpage; | |
789 | } | |
790 | #else | |
791 | static int khugepaged_find_target_node(void) | |
792 | { | |
793 | return 0; | |
794 | } | |
795 | ||
796 | static inline struct page *alloc_khugepaged_hugepage(void) | |
797 | { | |
798 | struct page *page; | |
799 | ||
800 | page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(), | |
801 | HPAGE_PMD_ORDER); | |
802 | if (page) | |
803 | prep_transhuge_page(page); | |
804 | return page; | |
805 | } | |
806 | ||
807 | static struct page *khugepaged_alloc_hugepage(bool *wait) | |
808 | { | |
809 | struct page *hpage; | |
810 | ||
811 | do { | |
812 | hpage = alloc_khugepaged_hugepage(); | |
813 | if (!hpage) { | |
814 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
815 | if (!*wait) | |
816 | return NULL; | |
817 | ||
818 | *wait = false; | |
819 | khugepaged_alloc_sleep(); | |
820 | } else | |
821 | count_vm_event(THP_COLLAPSE_ALLOC); | |
822 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
823 | ||
824 | return hpage; | |
825 | } | |
826 | ||
827 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
828 | { | |
829 | if (!*hpage) | |
830 | *hpage = khugepaged_alloc_hugepage(wait); | |
831 | ||
832 | if (unlikely(!*hpage)) | |
833 | return false; | |
834 | ||
835 | return true; | |
836 | } | |
837 | ||
838 | static struct page * | |
988ddb71 | 839 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f | 840 | { |
b46e756f KS |
841 | VM_BUG_ON(!*hpage); |
842 | ||
843 | return *hpage; | |
844 | } | |
845 | #endif | |
846 | ||
b46e756f KS |
847 | /* |
848 | * If mmap_sem temporarily dropped, revalidate vma | |
849 | * before taking mmap_sem. | |
850 | * Return 0 if succeeds, otherwise return none-zero | |
851 | * value (scan code). | |
852 | */ | |
853 | ||
c131f751 KS |
854 | static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, |
855 | struct vm_area_struct **vmap) | |
b46e756f KS |
856 | { |
857 | struct vm_area_struct *vma; | |
858 | unsigned long hstart, hend; | |
859 | ||
860 | if (unlikely(khugepaged_test_exit(mm))) | |
861 | return SCAN_ANY_PROCESS; | |
862 | ||
c131f751 | 863 | *vmap = vma = find_vma(mm, address); |
b46e756f KS |
864 | if (!vma) |
865 | return SCAN_VMA_NULL; | |
866 | ||
867 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
868 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
869 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
870 | return SCAN_ADDRESS_RANGE; | |
50f8b92f | 871 | if (!hugepage_vma_check(vma, vma->vm_flags)) |
b46e756f KS |
872 | return SCAN_VMA_CHECK; |
873 | return 0; | |
874 | } | |
875 | ||
876 | /* | |
877 | * Bring missing pages in from swap, to complete THP collapse. | |
878 | * Only done if khugepaged_scan_pmd believes it is worthwhile. | |
879 | * | |
880 | * Called and returns without pte mapped or spinlocks held, | |
881 | * but with mmap_sem held to protect against vma changes. | |
882 | */ | |
883 | ||
884 | static bool __collapse_huge_page_swapin(struct mm_struct *mm, | |
885 | struct vm_area_struct *vma, | |
0db501f7 EA |
886 | unsigned long address, pmd_t *pmd, |
887 | int referenced) | |
b46e756f | 888 | { |
2b740303 SJ |
889 | int swapped_in = 0; |
890 | vm_fault_t ret = 0; | |
82b0f8c3 | 891 | struct vm_fault vmf = { |
b46e756f KS |
892 | .vma = vma, |
893 | .address = address, | |
894 | .flags = FAULT_FLAG_ALLOW_RETRY, | |
895 | .pmd = pmd, | |
0721ec8b | 896 | .pgoff = linear_page_index(vma, address), |
b46e756f KS |
897 | }; |
898 | ||
982785c6 EA |
899 | /* we only decide to swapin, if there is enough young ptes */ |
900 | if (referenced < HPAGE_PMD_NR/2) { | |
901 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); | |
902 | return false; | |
903 | } | |
82b0f8c3 JK |
904 | vmf.pte = pte_offset_map(pmd, address); |
905 | for (; vmf.address < address + HPAGE_PMD_NR*PAGE_SIZE; | |
906 | vmf.pte++, vmf.address += PAGE_SIZE) { | |
2994302b JK |
907 | vmf.orig_pte = *vmf.pte; |
908 | if (!is_swap_pte(vmf.orig_pte)) | |
b46e756f KS |
909 | continue; |
910 | swapped_in++; | |
2994302b | 911 | ret = do_swap_page(&vmf); |
0db501f7 | 912 | |
b46e756f KS |
913 | /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */ |
914 | if (ret & VM_FAULT_RETRY) { | |
915 | down_read(&mm->mmap_sem); | |
82b0f8c3 | 916 | if (hugepage_vma_revalidate(mm, address, &vmf.vma)) { |
47f863ea | 917 | /* vma is no longer available, don't continue to swapin */ |
0db501f7 | 918 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f | 919 | return false; |
47f863ea | 920 | } |
b46e756f | 921 | /* check if the pmd is still valid */ |
835152a2 SP |
922 | if (mm_find_pmd(mm, address) != pmd) { |
923 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); | |
b46e756f | 924 | return false; |
835152a2 | 925 | } |
b46e756f KS |
926 | } |
927 | if (ret & VM_FAULT_ERROR) { | |
0db501f7 | 928 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f KS |
929 | return false; |
930 | } | |
931 | /* pte is unmapped now, we need to map it */ | |
82b0f8c3 | 932 | vmf.pte = pte_offset_map(pmd, vmf.address); |
b46e756f | 933 | } |
82b0f8c3 JK |
934 | vmf.pte--; |
935 | pte_unmap(vmf.pte); | |
0db501f7 | 936 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1); |
b46e756f KS |
937 | return true; |
938 | } | |
939 | ||
940 | static void collapse_huge_page(struct mm_struct *mm, | |
941 | unsigned long address, | |
942 | struct page **hpage, | |
0db501f7 | 943 | int node, int referenced) |
b46e756f KS |
944 | { |
945 | pmd_t *pmd, _pmd; | |
946 | pte_t *pte; | |
947 | pgtable_t pgtable; | |
948 | struct page *new_page; | |
949 | spinlock_t *pmd_ptl, *pte_ptl; | |
950 | int isolated = 0, result = 0; | |
951 | struct mem_cgroup *memcg; | |
c131f751 | 952 | struct vm_area_struct *vma; |
ac46d4f3 | 953 | struct mmu_notifier_range range; |
b46e756f KS |
954 | gfp_t gfp; |
955 | ||
956 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
957 | ||
958 | /* Only allocate from the target node */ | |
41b6167e | 959 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
b46e756f | 960 | |
988ddb71 KS |
961 | /* |
962 | * Before allocating the hugepage, release the mmap_sem read lock. | |
963 | * The allocation can take potentially a long time if it involves | |
964 | * sync compaction, and we do not need to hold the mmap_sem during | |
965 | * that. We will recheck the vma after taking it again in write mode. | |
966 | */ | |
967 | up_read(&mm->mmap_sem); | |
968 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
b46e756f KS |
969 | if (!new_page) { |
970 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
971 | goto out_nolock; | |
972 | } | |
973 | ||
2a70f6a7 | 974 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { |
b46e756f KS |
975 | result = SCAN_CGROUP_CHARGE_FAIL; |
976 | goto out_nolock; | |
977 | } | |
978 | ||
979 | down_read(&mm->mmap_sem); | |
c131f751 | 980 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f KS |
981 | if (result) { |
982 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
983 | up_read(&mm->mmap_sem); | |
984 | goto out_nolock; | |
985 | } | |
986 | ||
987 | pmd = mm_find_pmd(mm, address); | |
988 | if (!pmd) { | |
989 | result = SCAN_PMD_NULL; | |
990 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
991 | up_read(&mm->mmap_sem); | |
992 | goto out_nolock; | |
993 | } | |
994 | ||
995 | /* | |
996 | * __collapse_huge_page_swapin always returns with mmap_sem locked. | |
47f863ea | 997 | * If it fails, we release mmap_sem and jump out_nolock. |
b46e756f KS |
998 | * Continuing to collapse causes inconsistency. |
999 | */ | |
0db501f7 | 1000 | if (!__collapse_huge_page_swapin(mm, vma, address, pmd, referenced)) { |
b46e756f KS |
1001 | mem_cgroup_cancel_charge(new_page, memcg, true); |
1002 | up_read(&mm->mmap_sem); | |
1003 | goto out_nolock; | |
1004 | } | |
1005 | ||
1006 | up_read(&mm->mmap_sem); | |
1007 | /* | |
1008 | * Prevent all access to pagetables with the exception of | |
1009 | * gup_fast later handled by the ptep_clear_flush and the VM | |
1010 | * handled by the anon_vma lock + PG_lock. | |
1011 | */ | |
1012 | down_write(&mm->mmap_sem); | |
59ea6d06 AA |
1013 | result = SCAN_ANY_PROCESS; |
1014 | if (!mmget_still_valid(mm)) | |
1015 | goto out; | |
c131f751 | 1016 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f KS |
1017 | if (result) |
1018 | goto out; | |
1019 | /* check if the pmd is still valid */ | |
1020 | if (mm_find_pmd(mm, address) != pmd) | |
1021 | goto out; | |
1022 | ||
1023 | anon_vma_lock_write(vma->anon_vma); | |
1024 | ||
1025 | pte = pte_offset_map(pmd, address); | |
1026 | pte_ptl = pte_lockptr(mm, pmd); | |
1027 | ||
7269f999 | 1028 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, |
6f4f13e8 | 1029 | address, address + HPAGE_PMD_SIZE); |
ac46d4f3 | 1030 | mmu_notifier_invalidate_range_start(&range); |
b46e756f KS |
1031 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
1032 | /* | |
1033 | * After this gup_fast can't run anymore. This also removes | |
1034 | * any huge TLB entry from the CPU so we won't allow | |
1035 | * huge and small TLB entries for the same virtual address | |
1036 | * to avoid the risk of CPU bugs in that area. | |
1037 | */ | |
1038 | _pmd = pmdp_collapse_flush(vma, address, pmd); | |
1039 | spin_unlock(pmd_ptl); | |
ac46d4f3 | 1040 | mmu_notifier_invalidate_range_end(&range); |
b46e756f KS |
1041 | |
1042 | spin_lock(pte_ptl); | |
1043 | isolated = __collapse_huge_page_isolate(vma, address, pte); | |
1044 | spin_unlock(pte_ptl); | |
1045 | ||
1046 | if (unlikely(!isolated)) { | |
1047 | pte_unmap(pte); | |
1048 | spin_lock(pmd_ptl); | |
1049 | BUG_ON(!pmd_none(*pmd)); | |
1050 | /* | |
1051 | * We can only use set_pmd_at when establishing | |
1052 | * hugepmds and never for establishing regular pmds that | |
1053 | * points to regular pagetables. Use pmd_populate for that | |
1054 | */ | |
1055 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
1056 | spin_unlock(pmd_ptl); | |
1057 | anon_vma_unlock_write(vma->anon_vma); | |
1058 | result = SCAN_FAIL; | |
1059 | goto out; | |
1060 | } | |
1061 | ||
1062 | /* | |
1063 | * All pages are isolated and locked so anon_vma rmap | |
1064 | * can't run anymore. | |
1065 | */ | |
1066 | anon_vma_unlock_write(vma->anon_vma); | |
1067 | ||
1068 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); | |
1069 | pte_unmap(pte); | |
1070 | __SetPageUptodate(new_page); | |
1071 | pgtable = pmd_pgtable(_pmd); | |
1072 | ||
1073 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); | |
f55e1014 | 1074 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); |
b46e756f KS |
1075 | |
1076 | /* | |
1077 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
1078 | * this is needed to avoid the copy_huge_page writes to become | |
1079 | * visible after the set_pmd_at() write. | |
1080 | */ | |
1081 | smp_wmb(); | |
1082 | ||
1083 | spin_lock(pmd_ptl); | |
1084 | BUG_ON(!pmd_none(*pmd)); | |
1085 | page_add_new_anon_rmap(new_page, vma, address, true); | |
1086 | mem_cgroup_commit_charge(new_page, memcg, false, true); | |
1ff9e6e1 | 1087 | count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1); |
b46e756f KS |
1088 | lru_cache_add_active_or_unevictable(new_page, vma); |
1089 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
1090 | set_pmd_at(mm, address, pmd, _pmd); | |
1091 | update_mmu_cache_pmd(vma, address, pmd); | |
1092 | spin_unlock(pmd_ptl); | |
1093 | ||
1094 | *hpage = NULL; | |
1095 | ||
1096 | khugepaged_pages_collapsed++; | |
1097 | result = SCAN_SUCCEED; | |
1098 | out_up_write: | |
1099 | up_write(&mm->mmap_sem); | |
1100 | out_nolock: | |
1101 | trace_mm_collapse_huge_page(mm, isolated, result); | |
1102 | return; | |
1103 | out: | |
1104 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1105 | goto out_up_write; | |
1106 | } | |
1107 | ||
1108 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
1109 | struct vm_area_struct *vma, | |
1110 | unsigned long address, | |
1111 | struct page **hpage) | |
1112 | { | |
1113 | pmd_t *pmd; | |
1114 | pte_t *pte, *_pte; | |
0db501f7 | 1115 | int ret = 0, none_or_zero = 0, result = 0, referenced = 0; |
b46e756f KS |
1116 | struct page *page = NULL; |
1117 | unsigned long _address; | |
1118 | spinlock_t *ptl; | |
1119 | int node = NUMA_NO_NODE, unmapped = 0; | |
0db501f7 | 1120 | bool writable = false; |
b46e756f KS |
1121 | |
1122 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1123 | ||
1124 | pmd = mm_find_pmd(mm, address); | |
1125 | if (!pmd) { | |
1126 | result = SCAN_PMD_NULL; | |
1127 | goto out; | |
1128 | } | |
1129 | ||
1130 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1131 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1132 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1133 | _pte++, _address += PAGE_SIZE) { | |
1134 | pte_t pteval = *_pte; | |
1135 | if (is_swap_pte(pteval)) { | |
1136 | if (++unmapped <= khugepaged_max_ptes_swap) { | |
1137 | continue; | |
1138 | } else { | |
1139 | result = SCAN_EXCEED_SWAP_PTE; | |
1140 | goto out_unmap; | |
1141 | } | |
1142 | } | |
1143 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
1144 | if (!userfaultfd_armed(vma) && | |
1145 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
1146 | continue; | |
1147 | } else { | |
1148 | result = SCAN_EXCEED_NONE_PTE; | |
1149 | goto out_unmap; | |
1150 | } | |
1151 | } | |
1152 | if (!pte_present(pteval)) { | |
1153 | result = SCAN_PTE_NON_PRESENT; | |
1154 | goto out_unmap; | |
1155 | } | |
1156 | if (pte_write(pteval)) | |
1157 | writable = true; | |
1158 | ||
1159 | page = vm_normal_page(vma, _address, pteval); | |
1160 | if (unlikely(!page)) { | |
1161 | result = SCAN_PAGE_NULL; | |
1162 | goto out_unmap; | |
1163 | } | |
1164 | ||
1165 | /* TODO: teach khugepaged to collapse THP mapped with pte */ | |
1166 | if (PageCompound(page)) { | |
1167 | result = SCAN_PAGE_COMPOUND; | |
1168 | goto out_unmap; | |
1169 | } | |
1170 | ||
1171 | /* | |
1172 | * Record which node the original page is from and save this | |
1173 | * information to khugepaged_node_load[]. | |
1174 | * Khupaged will allocate hugepage from the node has the max | |
1175 | * hit record. | |
1176 | */ | |
1177 | node = page_to_nid(page); | |
1178 | if (khugepaged_scan_abort(node)) { | |
1179 | result = SCAN_SCAN_ABORT; | |
1180 | goto out_unmap; | |
1181 | } | |
1182 | khugepaged_node_load[node]++; | |
1183 | if (!PageLRU(page)) { | |
1184 | result = SCAN_PAGE_LRU; | |
1185 | goto out_unmap; | |
1186 | } | |
1187 | if (PageLocked(page)) { | |
1188 | result = SCAN_PAGE_LOCK; | |
1189 | goto out_unmap; | |
1190 | } | |
1191 | if (!PageAnon(page)) { | |
1192 | result = SCAN_PAGE_ANON; | |
1193 | goto out_unmap; | |
1194 | } | |
1195 | ||
1196 | /* | |
1197 | * cannot use mapcount: can't collapse if there's a gup pin. | |
1198 | * The page must only be referenced by the scanned process | |
1199 | * and page swap cache. | |
1200 | */ | |
2948be5a | 1201 | if (page_count(page) != 1 + PageSwapCache(page)) { |
b46e756f KS |
1202 | result = SCAN_PAGE_COUNT; |
1203 | goto out_unmap; | |
1204 | } | |
1205 | if (pte_young(pteval) || | |
1206 | page_is_young(page) || PageReferenced(page) || | |
1207 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 1208 | referenced++; |
b46e756f KS |
1209 | } |
1210 | if (writable) { | |
1211 | if (referenced) { | |
1212 | result = SCAN_SUCCEED; | |
1213 | ret = 1; | |
1214 | } else { | |
0db501f7 | 1215 | result = SCAN_LACK_REFERENCED_PAGE; |
b46e756f KS |
1216 | } |
1217 | } else { | |
1218 | result = SCAN_PAGE_RO; | |
1219 | } | |
1220 | out_unmap: | |
1221 | pte_unmap_unlock(pte, ptl); | |
1222 | if (ret) { | |
1223 | node = khugepaged_find_target_node(); | |
1224 | /* collapse_huge_page will return with the mmap_sem released */ | |
c131f751 | 1225 | collapse_huge_page(mm, address, hpage, node, referenced); |
b46e756f KS |
1226 | } |
1227 | out: | |
1228 | trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, | |
1229 | none_or_zero, result, unmapped); | |
1230 | return ret; | |
1231 | } | |
1232 | ||
1233 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
1234 | { | |
1235 | struct mm_struct *mm = mm_slot->mm; | |
1236 | ||
35f3aa39 | 1237 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
1238 | |
1239 | if (khugepaged_test_exit(mm)) { | |
1240 | /* free mm_slot */ | |
1241 | hash_del(&mm_slot->hash); | |
1242 | list_del(&mm_slot->mm_node); | |
1243 | ||
1244 | /* | |
1245 | * Not strictly needed because the mm exited already. | |
1246 | * | |
1247 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1248 | */ | |
1249 | ||
1250 | /* khugepaged_mm_lock actually not necessary for the below */ | |
1251 | free_mm_slot(mm_slot); | |
1252 | mmdrop(mm); | |
1253 | } | |
1254 | } | |
1255 | ||
e496cf3d | 1256 | #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) |
f3f0e1d2 KS |
1257 | static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) |
1258 | { | |
1259 | struct vm_area_struct *vma; | |
1260 | unsigned long addr; | |
1261 | pmd_t *pmd, _pmd; | |
1262 | ||
1263 | i_mmap_lock_write(mapping); | |
1264 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { | |
1265 | /* probably overkill */ | |
1266 | if (vma->anon_vma) | |
1267 | continue; | |
1268 | addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
1269 | if (addr & ~HPAGE_PMD_MASK) | |
1270 | continue; | |
1271 | if (vma->vm_end < addr + HPAGE_PMD_SIZE) | |
1272 | continue; | |
1273 | pmd = mm_find_pmd(vma->vm_mm, addr); | |
1274 | if (!pmd) | |
1275 | continue; | |
1276 | /* | |
1277 | * We need exclusive mmap_sem to retract page table. | |
1278 | * If trylock fails we would end up with pte-mapped THP after | |
1279 | * re-fault. Not ideal, but it's more important to not disturb | |
1280 | * the system too much. | |
1281 | */ | |
1282 | if (down_write_trylock(&vma->vm_mm->mmap_sem)) { | |
1283 | spinlock_t *ptl = pmd_lock(vma->vm_mm, pmd); | |
1284 | /* assume page table is clear */ | |
1285 | _pmd = pmdp_collapse_flush(vma, addr, pmd); | |
1286 | spin_unlock(ptl); | |
1287 | up_write(&vma->vm_mm->mmap_sem); | |
c4812909 | 1288 | mm_dec_nr_ptes(vma->vm_mm); |
d670ffd8 | 1289 | pte_free(vma->vm_mm, pmd_pgtable(_pmd)); |
f3f0e1d2 KS |
1290 | } |
1291 | } | |
1292 | i_mmap_unlock_write(mapping); | |
1293 | } | |
1294 | ||
1295 | /** | |
99cb0dbd | 1296 | * collapse_file - collapse filemap/tmpfs/shmem pages into huge one. |
f3f0e1d2 KS |
1297 | * |
1298 | * Basic scheme is simple, details are more complex: | |
87c460a0 | 1299 | * - allocate and lock a new huge page; |
77da9389 | 1300 | * - scan page cache replacing old pages with the new one |
99cb0dbd | 1301 | * + swap/gup in pages if necessary; |
f3f0e1d2 | 1302 | * + fill in gaps; |
77da9389 MW |
1303 | * + keep old pages around in case rollback is required; |
1304 | * - if replacing succeeds: | |
f3f0e1d2 KS |
1305 | * + copy data over; |
1306 | * + free old pages; | |
87c460a0 | 1307 | * + unlock huge page; |
f3f0e1d2 KS |
1308 | * - if replacing failed; |
1309 | * + put all pages back and unfreeze them; | |
77da9389 | 1310 | * + restore gaps in the page cache; |
87c460a0 | 1311 | * + unlock and free huge page; |
f3f0e1d2 | 1312 | */ |
579c571e SL |
1313 | static void collapse_file(struct mm_struct *mm, |
1314 | struct file *file, pgoff_t start, | |
f3f0e1d2 KS |
1315 | struct page **hpage, int node) |
1316 | { | |
579c571e | 1317 | struct address_space *mapping = file->f_mapping; |
f3f0e1d2 | 1318 | gfp_t gfp; |
77da9389 | 1319 | struct page *new_page; |
f3f0e1d2 KS |
1320 | struct mem_cgroup *memcg; |
1321 | pgoff_t index, end = start + HPAGE_PMD_NR; | |
1322 | LIST_HEAD(pagelist); | |
77da9389 | 1323 | XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); |
f3f0e1d2 | 1324 | int nr_none = 0, result = SCAN_SUCCEED; |
99cb0dbd | 1325 | bool is_shmem = shmem_file(file); |
f3f0e1d2 | 1326 | |
99cb0dbd | 1327 | VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); |
f3f0e1d2 KS |
1328 | VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); |
1329 | ||
1330 | /* Only allocate from the target node */ | |
41b6167e | 1331 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
f3f0e1d2 KS |
1332 | |
1333 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
1334 | if (!new_page) { | |
1335 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
1336 | goto out; | |
1337 | } | |
1338 | ||
2a70f6a7 | 1339 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { |
f3f0e1d2 KS |
1340 | result = SCAN_CGROUP_CHARGE_FAIL; |
1341 | goto out; | |
1342 | } | |
1343 | ||
95feeabb HD |
1344 | /* This will be less messy when we use multi-index entries */ |
1345 | do { | |
1346 | xas_lock_irq(&xas); | |
1347 | xas_create_range(&xas); | |
1348 | if (!xas_error(&xas)) | |
1349 | break; | |
1350 | xas_unlock_irq(&xas); | |
1351 | if (!xas_nomem(&xas, GFP_KERNEL)) { | |
1352 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1353 | result = SCAN_FAIL; | |
1354 | goto out; | |
1355 | } | |
1356 | } while (1); | |
1357 | ||
042a3082 | 1358 | __SetPageLocked(new_page); |
99cb0dbd SL |
1359 | if (is_shmem) |
1360 | __SetPageSwapBacked(new_page); | |
f3f0e1d2 KS |
1361 | new_page->index = start; |
1362 | new_page->mapping = mapping; | |
f3f0e1d2 | 1363 | |
f3f0e1d2 | 1364 | /* |
87c460a0 HD |
1365 | * At this point the new_page is locked and not up-to-date. |
1366 | * It's safe to insert it into the page cache, because nobody would | |
1367 | * be able to map it or use it in another way until we unlock it. | |
f3f0e1d2 KS |
1368 | */ |
1369 | ||
77da9389 MW |
1370 | xas_set(&xas, start); |
1371 | for (index = start; index < end; index++) { | |
1372 | struct page *page = xas_next(&xas); | |
1373 | ||
1374 | VM_BUG_ON(index != xas.xa_index); | |
99cb0dbd SL |
1375 | if (is_shmem) { |
1376 | if (!page) { | |
1377 | /* | |
1378 | * Stop if extent has been truncated or | |
1379 | * hole-punched, and is now completely | |
1380 | * empty. | |
1381 | */ | |
1382 | if (index == start) { | |
1383 | if (!xas_next_entry(&xas, end - 1)) { | |
1384 | result = SCAN_TRUNCATED; | |
1385 | goto xa_locked; | |
1386 | } | |
1387 | xas_set(&xas, index); | |
1388 | } | |
1389 | if (!shmem_charge(mapping->host, 1)) { | |
1390 | result = SCAN_FAIL; | |
042a3082 | 1391 | goto xa_locked; |
701270fa | 1392 | } |
99cb0dbd SL |
1393 | xas_store(&xas, new_page); |
1394 | nr_none++; | |
1395 | continue; | |
701270fa | 1396 | } |
99cb0dbd SL |
1397 | |
1398 | if (xa_is_value(page) || !PageUptodate(page)) { | |
1399 | xas_unlock_irq(&xas); | |
1400 | /* swap in or instantiate fallocated page */ | |
1401 | if (shmem_getpage(mapping->host, index, &page, | |
1402 | SGP_NOHUGE)) { | |
1403 | result = SCAN_FAIL; | |
1404 | goto xa_unlocked; | |
1405 | } | |
1406 | } else if (trylock_page(page)) { | |
1407 | get_page(page); | |
1408 | xas_unlock_irq(&xas); | |
1409 | } else { | |
1410 | result = SCAN_PAGE_LOCK; | |
042a3082 | 1411 | goto xa_locked; |
77da9389 | 1412 | } |
99cb0dbd SL |
1413 | } else { /* !is_shmem */ |
1414 | if (!page || xa_is_value(page)) { | |
1415 | xas_unlock_irq(&xas); | |
1416 | page_cache_sync_readahead(mapping, &file->f_ra, | |
1417 | file, index, | |
1418 | PAGE_SIZE); | |
1419 | /* drain pagevecs to help isolate_lru_page() */ | |
1420 | lru_add_drain(); | |
1421 | page = find_lock_page(mapping, index); | |
1422 | if (unlikely(page == NULL)) { | |
1423 | result = SCAN_FAIL; | |
1424 | goto xa_unlocked; | |
1425 | } | |
1426 | } else if (!PageUptodate(page)) { | |
1427 | xas_unlock_irq(&xas); | |
1428 | wait_on_page_locked(page); | |
1429 | if (!trylock_page(page)) { | |
1430 | result = SCAN_PAGE_LOCK; | |
1431 | goto xa_unlocked; | |
1432 | } | |
1433 | get_page(page); | |
1434 | } else if (PageDirty(page)) { | |
f3f0e1d2 | 1435 | result = SCAN_FAIL; |
99cb0dbd SL |
1436 | goto xa_locked; |
1437 | } else if (trylock_page(page)) { | |
1438 | get_page(page); | |
1439 | xas_unlock_irq(&xas); | |
1440 | } else { | |
1441 | result = SCAN_PAGE_LOCK; | |
1442 | goto xa_locked; | |
f3f0e1d2 | 1443 | } |
f3f0e1d2 KS |
1444 | } |
1445 | ||
1446 | /* | |
b93b0163 | 1447 | * The page must be locked, so we can drop the i_pages lock |
f3f0e1d2 KS |
1448 | * without racing with truncate. |
1449 | */ | |
1450 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
1451 | VM_BUG_ON_PAGE(!PageUptodate(page), page); | |
06a5e126 HD |
1452 | |
1453 | /* | |
1454 | * If file was truncated then extended, or hole-punched, before | |
1455 | * we locked the first page, then a THP might be there already. | |
1456 | */ | |
1457 | if (PageTransCompound(page)) { | |
1458 | result = SCAN_PAGE_COMPOUND; | |
1459 | goto out_unlock; | |
1460 | } | |
f3f0e1d2 KS |
1461 | |
1462 | if (page_mapping(page) != mapping) { | |
1463 | result = SCAN_TRUNCATED; | |
1464 | goto out_unlock; | |
1465 | } | |
f3f0e1d2 KS |
1466 | |
1467 | if (isolate_lru_page(page)) { | |
1468 | result = SCAN_DEL_PAGE_LRU; | |
042a3082 | 1469 | goto out_unlock; |
f3f0e1d2 KS |
1470 | } |
1471 | ||
99cb0dbd SL |
1472 | if (page_has_private(page) && |
1473 | !try_to_release_page(page, GFP_KERNEL)) { | |
1474 | result = SCAN_PAGE_HAS_PRIVATE; | |
1475 | goto out_unlock; | |
1476 | } | |
1477 | ||
f3f0e1d2 | 1478 | if (page_mapped(page)) |
977fbdcd | 1479 | unmap_mapping_pages(mapping, index, 1, false); |
f3f0e1d2 | 1480 | |
77da9389 MW |
1481 | xas_lock_irq(&xas); |
1482 | xas_set(&xas, index); | |
f3f0e1d2 | 1483 | |
77da9389 | 1484 | VM_BUG_ON_PAGE(page != xas_load(&xas), page); |
f3f0e1d2 KS |
1485 | VM_BUG_ON_PAGE(page_mapped(page), page); |
1486 | ||
1487 | /* | |
1488 | * The page is expected to have page_count() == 3: | |
1489 | * - we hold a pin on it; | |
77da9389 | 1490 | * - one reference from page cache; |
f3f0e1d2 KS |
1491 | * - one from isolate_lru_page; |
1492 | */ | |
1493 | if (!page_ref_freeze(page, 3)) { | |
1494 | result = SCAN_PAGE_COUNT; | |
042a3082 HD |
1495 | xas_unlock_irq(&xas); |
1496 | putback_lru_page(page); | |
1497 | goto out_unlock; | |
f3f0e1d2 KS |
1498 | } |
1499 | ||
1500 | /* | |
1501 | * Add the page to the list to be able to undo the collapse if | |
1502 | * something go wrong. | |
1503 | */ | |
1504 | list_add_tail(&page->lru, &pagelist); | |
1505 | ||
1506 | /* Finally, replace with the new page. */ | |
4101196b | 1507 | xas_store(&xas, new_page); |
f3f0e1d2 | 1508 | continue; |
f3f0e1d2 KS |
1509 | out_unlock: |
1510 | unlock_page(page); | |
1511 | put_page(page); | |
042a3082 | 1512 | goto xa_unlocked; |
f3f0e1d2 KS |
1513 | } |
1514 | ||
99cb0dbd SL |
1515 | if (is_shmem) |
1516 | __inc_node_page_state(new_page, NR_SHMEM_THPS); | |
09d91cda | 1517 | else { |
99cb0dbd | 1518 | __inc_node_page_state(new_page, NR_FILE_THPS); |
09d91cda SL |
1519 | filemap_nr_thps_inc(mapping); |
1520 | } | |
99cb0dbd | 1521 | |
042a3082 HD |
1522 | if (nr_none) { |
1523 | struct zone *zone = page_zone(new_page); | |
1524 | ||
1525 | __mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none); | |
99cb0dbd SL |
1526 | if (is_shmem) |
1527 | __mod_node_page_state(zone->zone_pgdat, | |
1528 | NR_SHMEM, nr_none); | |
042a3082 HD |
1529 | } |
1530 | ||
1531 | xa_locked: | |
1532 | xas_unlock_irq(&xas); | |
77da9389 | 1533 | xa_unlocked: |
042a3082 | 1534 | |
f3f0e1d2 | 1535 | if (result == SCAN_SUCCEED) { |
77da9389 | 1536 | struct page *page, *tmp; |
f3f0e1d2 KS |
1537 | |
1538 | /* | |
77da9389 MW |
1539 | * Replacing old pages with new one has succeeded, now we |
1540 | * need to copy the content and free the old pages. | |
f3f0e1d2 | 1541 | */ |
2af8ff29 | 1542 | index = start; |
f3f0e1d2 | 1543 | list_for_each_entry_safe(page, tmp, &pagelist, lru) { |
2af8ff29 HD |
1544 | while (index < page->index) { |
1545 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1546 | index++; | |
1547 | } | |
f3f0e1d2 KS |
1548 | copy_highpage(new_page + (page->index % HPAGE_PMD_NR), |
1549 | page); | |
1550 | list_del(&page->lru); | |
f3f0e1d2 | 1551 | page->mapping = NULL; |
042a3082 | 1552 | page_ref_unfreeze(page, 1); |
f3f0e1d2 KS |
1553 | ClearPageActive(page); |
1554 | ClearPageUnevictable(page); | |
042a3082 | 1555 | unlock_page(page); |
f3f0e1d2 | 1556 | put_page(page); |
2af8ff29 HD |
1557 | index++; |
1558 | } | |
1559 | while (index < end) { | |
1560 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1561 | index++; | |
f3f0e1d2 KS |
1562 | } |
1563 | ||
f3f0e1d2 | 1564 | SetPageUptodate(new_page); |
87c460a0 | 1565 | page_ref_add(new_page, HPAGE_PMD_NR - 1); |
f3f0e1d2 | 1566 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
99cb0dbd SL |
1567 | |
1568 | if (is_shmem) { | |
1569 | set_page_dirty(new_page); | |
1570 | lru_cache_add_anon(new_page); | |
1571 | } else { | |
1572 | lru_cache_add_file(new_page); | |
1573 | } | |
1ff9e6e1 | 1574 | count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1); |
f3f0e1d2 | 1575 | |
042a3082 HD |
1576 | /* |
1577 | * Remove pte page tables, so we can re-fault the page as huge. | |
1578 | */ | |
1579 | retract_page_tables(mapping, start); | |
f3f0e1d2 | 1580 | *hpage = NULL; |
87aa7529 YS |
1581 | |
1582 | khugepaged_pages_collapsed++; | |
f3f0e1d2 | 1583 | } else { |
77da9389 | 1584 | struct page *page; |
aaa52e34 | 1585 | |
77da9389 | 1586 | /* Something went wrong: roll back page cache changes */ |
77da9389 | 1587 | xas_lock_irq(&xas); |
aaa52e34 | 1588 | mapping->nrpages -= nr_none; |
99cb0dbd SL |
1589 | |
1590 | if (is_shmem) | |
1591 | shmem_uncharge(mapping->host, nr_none); | |
aaa52e34 | 1592 | |
77da9389 MW |
1593 | xas_set(&xas, start); |
1594 | xas_for_each(&xas, page, end - 1) { | |
f3f0e1d2 KS |
1595 | page = list_first_entry_or_null(&pagelist, |
1596 | struct page, lru); | |
77da9389 | 1597 | if (!page || xas.xa_index < page->index) { |
f3f0e1d2 KS |
1598 | if (!nr_none) |
1599 | break; | |
f3f0e1d2 | 1600 | nr_none--; |
59749e6c | 1601 | /* Put holes back where they were */ |
77da9389 | 1602 | xas_store(&xas, NULL); |
f3f0e1d2 KS |
1603 | continue; |
1604 | } | |
1605 | ||
77da9389 | 1606 | VM_BUG_ON_PAGE(page->index != xas.xa_index, page); |
f3f0e1d2 KS |
1607 | |
1608 | /* Unfreeze the page. */ | |
1609 | list_del(&page->lru); | |
1610 | page_ref_unfreeze(page, 2); | |
77da9389 MW |
1611 | xas_store(&xas, page); |
1612 | xas_pause(&xas); | |
1613 | xas_unlock_irq(&xas); | |
f3f0e1d2 | 1614 | unlock_page(page); |
042a3082 | 1615 | putback_lru_page(page); |
77da9389 | 1616 | xas_lock_irq(&xas); |
f3f0e1d2 KS |
1617 | } |
1618 | VM_BUG_ON(nr_none); | |
77da9389 | 1619 | xas_unlock_irq(&xas); |
f3f0e1d2 | 1620 | |
f3f0e1d2 | 1621 | mem_cgroup_cancel_charge(new_page, memcg, true); |
f3f0e1d2 KS |
1622 | new_page->mapping = NULL; |
1623 | } | |
042a3082 HD |
1624 | |
1625 | unlock_page(new_page); | |
f3f0e1d2 KS |
1626 | out: |
1627 | VM_BUG_ON(!list_empty(&pagelist)); | |
1628 | /* TODO: tracepoints */ | |
1629 | } | |
1630 | ||
579c571e SL |
1631 | static void khugepaged_scan_file(struct mm_struct *mm, |
1632 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
1633 | { |
1634 | struct page *page = NULL; | |
579c571e | 1635 | struct address_space *mapping = file->f_mapping; |
85b392db | 1636 | XA_STATE(xas, &mapping->i_pages, start); |
f3f0e1d2 KS |
1637 | int present, swap; |
1638 | int node = NUMA_NO_NODE; | |
1639 | int result = SCAN_SUCCEED; | |
1640 | ||
1641 | present = 0; | |
1642 | swap = 0; | |
1643 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1644 | rcu_read_lock(); | |
85b392db MW |
1645 | xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) { |
1646 | if (xas_retry(&xas, page)) | |
f3f0e1d2 | 1647 | continue; |
f3f0e1d2 | 1648 | |
85b392db | 1649 | if (xa_is_value(page)) { |
f3f0e1d2 KS |
1650 | if (++swap > khugepaged_max_ptes_swap) { |
1651 | result = SCAN_EXCEED_SWAP_PTE; | |
1652 | break; | |
1653 | } | |
1654 | continue; | |
1655 | } | |
1656 | ||
1657 | if (PageTransCompound(page)) { | |
1658 | result = SCAN_PAGE_COMPOUND; | |
1659 | break; | |
1660 | } | |
1661 | ||
1662 | node = page_to_nid(page); | |
1663 | if (khugepaged_scan_abort(node)) { | |
1664 | result = SCAN_SCAN_ABORT; | |
1665 | break; | |
1666 | } | |
1667 | khugepaged_node_load[node]++; | |
1668 | ||
1669 | if (!PageLRU(page)) { | |
1670 | result = SCAN_PAGE_LRU; | |
1671 | break; | |
1672 | } | |
1673 | ||
99cb0dbd SL |
1674 | if (page_count(page) != |
1675 | 1 + page_mapcount(page) + page_has_private(page)) { | |
f3f0e1d2 KS |
1676 | result = SCAN_PAGE_COUNT; |
1677 | break; | |
1678 | } | |
1679 | ||
1680 | /* | |
1681 | * We probably should check if the page is referenced here, but | |
1682 | * nobody would transfer pte_young() to PageReferenced() for us. | |
1683 | * And rmap walk here is just too costly... | |
1684 | */ | |
1685 | ||
1686 | present++; | |
1687 | ||
1688 | if (need_resched()) { | |
85b392db | 1689 | xas_pause(&xas); |
f3f0e1d2 | 1690 | cond_resched_rcu(); |
f3f0e1d2 KS |
1691 | } |
1692 | } | |
1693 | rcu_read_unlock(); | |
1694 | ||
1695 | if (result == SCAN_SUCCEED) { | |
1696 | if (present < HPAGE_PMD_NR - khugepaged_max_ptes_none) { | |
1697 | result = SCAN_EXCEED_NONE_PTE; | |
1698 | } else { | |
1699 | node = khugepaged_find_target_node(); | |
579c571e | 1700 | collapse_file(mm, file, start, hpage, node); |
f3f0e1d2 KS |
1701 | } |
1702 | } | |
1703 | ||
1704 | /* TODO: tracepoints */ | |
1705 | } | |
1706 | #else | |
579c571e SL |
1707 | static void khugepaged_scan_file(struct mm_struct *mm, |
1708 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
1709 | { |
1710 | BUILD_BUG(); | |
1711 | } | |
1712 | #endif | |
1713 | ||
b46e756f KS |
1714 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, |
1715 | struct page **hpage) | |
1716 | __releases(&khugepaged_mm_lock) | |
1717 | __acquires(&khugepaged_mm_lock) | |
1718 | { | |
1719 | struct mm_slot *mm_slot; | |
1720 | struct mm_struct *mm; | |
1721 | struct vm_area_struct *vma; | |
1722 | int progress = 0; | |
1723 | ||
1724 | VM_BUG_ON(!pages); | |
35f3aa39 | 1725 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
1726 | |
1727 | if (khugepaged_scan.mm_slot) | |
1728 | mm_slot = khugepaged_scan.mm_slot; | |
1729 | else { | |
1730 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
1731 | struct mm_slot, mm_node); | |
1732 | khugepaged_scan.address = 0; | |
1733 | khugepaged_scan.mm_slot = mm_slot; | |
1734 | } | |
1735 | spin_unlock(&khugepaged_mm_lock); | |
1736 | ||
1737 | mm = mm_slot->mm; | |
3b454ad3 YS |
1738 | /* |
1739 | * Don't wait for semaphore (to avoid long wait times). Just move to | |
1740 | * the next mm on the list. | |
1741 | */ | |
1742 | vma = NULL; | |
1743 | if (unlikely(!down_read_trylock(&mm->mmap_sem))) | |
1744 | goto breakouterloop_mmap_sem; | |
1745 | if (likely(!khugepaged_test_exit(mm))) | |
b46e756f KS |
1746 | vma = find_vma(mm, khugepaged_scan.address); |
1747 | ||
1748 | progress++; | |
1749 | for (; vma; vma = vma->vm_next) { | |
1750 | unsigned long hstart, hend; | |
1751 | ||
1752 | cond_resched(); | |
1753 | if (unlikely(khugepaged_test_exit(mm))) { | |
1754 | progress++; | |
1755 | break; | |
1756 | } | |
50f8b92f | 1757 | if (!hugepage_vma_check(vma, vma->vm_flags)) { |
b46e756f KS |
1758 | skip: |
1759 | progress++; | |
1760 | continue; | |
1761 | } | |
1762 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
1763 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1764 | if (hstart >= hend) | |
1765 | goto skip; | |
1766 | if (khugepaged_scan.address > hend) | |
1767 | goto skip; | |
1768 | if (khugepaged_scan.address < hstart) | |
1769 | khugepaged_scan.address = hstart; | |
1770 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); | |
1771 | ||
1772 | while (khugepaged_scan.address < hend) { | |
1773 | int ret; | |
1774 | cond_resched(); | |
1775 | if (unlikely(khugepaged_test_exit(mm))) | |
1776 | goto breakouterloop; | |
1777 | ||
1778 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
1779 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
1780 | hend); | |
99cb0dbd | 1781 | if (IS_ENABLED(CONFIG_SHMEM) && vma->vm_file) { |
e496cf3d | 1782 | struct file *file; |
f3f0e1d2 KS |
1783 | pgoff_t pgoff = linear_page_index(vma, |
1784 | khugepaged_scan.address); | |
99cb0dbd SL |
1785 | |
1786 | if (shmem_file(vma->vm_file) | |
1787 | && !shmem_huge_enabled(vma)) | |
e496cf3d KS |
1788 | goto skip; |
1789 | file = get_file(vma->vm_file); | |
f3f0e1d2 KS |
1790 | up_read(&mm->mmap_sem); |
1791 | ret = 1; | |
579c571e | 1792 | khugepaged_scan_file(mm, file, pgoff, hpage); |
f3f0e1d2 KS |
1793 | fput(file); |
1794 | } else { | |
1795 | ret = khugepaged_scan_pmd(mm, vma, | |
1796 | khugepaged_scan.address, | |
1797 | hpage); | |
1798 | } | |
b46e756f KS |
1799 | /* move to next address */ |
1800 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
1801 | progress += HPAGE_PMD_NR; | |
1802 | if (ret) | |
1803 | /* we released mmap_sem so break loop */ | |
1804 | goto breakouterloop_mmap_sem; | |
1805 | if (progress >= pages) | |
1806 | goto breakouterloop; | |
1807 | } | |
1808 | } | |
1809 | breakouterloop: | |
1810 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
1811 | breakouterloop_mmap_sem: | |
1812 | ||
1813 | spin_lock(&khugepaged_mm_lock); | |
1814 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); | |
1815 | /* | |
1816 | * Release the current mm_slot if this mm is about to die, or | |
1817 | * if we scanned all vmas of this mm. | |
1818 | */ | |
1819 | if (khugepaged_test_exit(mm) || !vma) { | |
1820 | /* | |
1821 | * Make sure that if mm_users is reaching zero while | |
1822 | * khugepaged runs here, khugepaged_exit will find | |
1823 | * mm_slot not pointing to the exiting mm. | |
1824 | */ | |
1825 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
1826 | khugepaged_scan.mm_slot = list_entry( | |
1827 | mm_slot->mm_node.next, | |
1828 | struct mm_slot, mm_node); | |
1829 | khugepaged_scan.address = 0; | |
1830 | } else { | |
1831 | khugepaged_scan.mm_slot = NULL; | |
1832 | khugepaged_full_scans++; | |
1833 | } | |
1834 | ||
1835 | collect_mm_slot(mm_slot); | |
1836 | } | |
1837 | ||
1838 | return progress; | |
1839 | } | |
1840 | ||
1841 | static int khugepaged_has_work(void) | |
1842 | { | |
1843 | return !list_empty(&khugepaged_scan.mm_head) && | |
1844 | khugepaged_enabled(); | |
1845 | } | |
1846 | ||
1847 | static int khugepaged_wait_event(void) | |
1848 | { | |
1849 | return !list_empty(&khugepaged_scan.mm_head) || | |
1850 | kthread_should_stop(); | |
1851 | } | |
1852 | ||
1853 | static void khugepaged_do_scan(void) | |
1854 | { | |
1855 | struct page *hpage = NULL; | |
1856 | unsigned int progress = 0, pass_through_head = 0; | |
1857 | unsigned int pages = khugepaged_pages_to_scan; | |
1858 | bool wait = true; | |
1859 | ||
1860 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
1861 | ||
1862 | while (progress < pages) { | |
1863 | if (!khugepaged_prealloc_page(&hpage, &wait)) | |
1864 | break; | |
1865 | ||
1866 | cond_resched(); | |
1867 | ||
1868 | if (unlikely(kthread_should_stop() || try_to_freeze())) | |
1869 | break; | |
1870 | ||
1871 | spin_lock(&khugepaged_mm_lock); | |
1872 | if (!khugepaged_scan.mm_slot) | |
1873 | pass_through_head++; | |
1874 | if (khugepaged_has_work() && | |
1875 | pass_through_head < 2) | |
1876 | progress += khugepaged_scan_mm_slot(pages - progress, | |
1877 | &hpage); | |
1878 | else | |
1879 | progress = pages; | |
1880 | spin_unlock(&khugepaged_mm_lock); | |
1881 | } | |
1882 | ||
1883 | if (!IS_ERR_OR_NULL(hpage)) | |
1884 | put_page(hpage); | |
1885 | } | |
1886 | ||
1887 | static bool khugepaged_should_wakeup(void) | |
1888 | { | |
1889 | return kthread_should_stop() || | |
1890 | time_after_eq(jiffies, khugepaged_sleep_expire); | |
1891 | } | |
1892 | ||
1893 | static void khugepaged_wait_work(void) | |
1894 | { | |
1895 | if (khugepaged_has_work()) { | |
1896 | const unsigned long scan_sleep_jiffies = | |
1897 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs); | |
1898 | ||
1899 | if (!scan_sleep_jiffies) | |
1900 | return; | |
1901 | ||
1902 | khugepaged_sleep_expire = jiffies + scan_sleep_jiffies; | |
1903 | wait_event_freezable_timeout(khugepaged_wait, | |
1904 | khugepaged_should_wakeup(), | |
1905 | scan_sleep_jiffies); | |
1906 | return; | |
1907 | } | |
1908 | ||
1909 | if (khugepaged_enabled()) | |
1910 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
1911 | } | |
1912 | ||
1913 | static int khugepaged(void *none) | |
1914 | { | |
1915 | struct mm_slot *mm_slot; | |
1916 | ||
1917 | set_freezable(); | |
1918 | set_user_nice(current, MAX_NICE); | |
1919 | ||
1920 | while (!kthread_should_stop()) { | |
1921 | khugepaged_do_scan(); | |
1922 | khugepaged_wait_work(); | |
1923 | } | |
1924 | ||
1925 | spin_lock(&khugepaged_mm_lock); | |
1926 | mm_slot = khugepaged_scan.mm_slot; | |
1927 | khugepaged_scan.mm_slot = NULL; | |
1928 | if (mm_slot) | |
1929 | collect_mm_slot(mm_slot); | |
1930 | spin_unlock(&khugepaged_mm_lock); | |
1931 | return 0; | |
1932 | } | |
1933 | ||
1934 | static void set_recommended_min_free_kbytes(void) | |
1935 | { | |
1936 | struct zone *zone; | |
1937 | int nr_zones = 0; | |
1938 | unsigned long recommended_min; | |
1939 | ||
b7d349c7 JK |
1940 | for_each_populated_zone(zone) { |
1941 | /* | |
1942 | * We don't need to worry about fragmentation of | |
1943 | * ZONE_MOVABLE since it only has movable pages. | |
1944 | */ | |
1945 | if (zone_idx(zone) > gfp_zone(GFP_USER)) | |
1946 | continue; | |
1947 | ||
b46e756f | 1948 | nr_zones++; |
b7d349c7 | 1949 | } |
b46e756f KS |
1950 | |
1951 | /* Ensure 2 pageblocks are free to assist fragmentation avoidance */ | |
1952 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
1953 | ||
1954 | /* | |
1955 | * Make sure that on average at least two pageblocks are almost free | |
1956 | * of another type, one for a migratetype to fall back to and a | |
1957 | * second to avoid subsequent fallbacks of other types There are 3 | |
1958 | * MIGRATE_TYPES we care about. | |
1959 | */ | |
1960 | recommended_min += pageblock_nr_pages * nr_zones * | |
1961 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
1962 | ||
1963 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
1964 | recommended_min = min(recommended_min, | |
1965 | (unsigned long) nr_free_buffer_pages() / 20); | |
1966 | recommended_min <<= (PAGE_SHIFT-10); | |
1967 | ||
1968 | if (recommended_min > min_free_kbytes) { | |
1969 | if (user_min_free_kbytes >= 0) | |
1970 | pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n", | |
1971 | min_free_kbytes, recommended_min); | |
1972 | ||
1973 | min_free_kbytes = recommended_min; | |
1974 | } | |
1975 | setup_per_zone_wmarks(); | |
1976 | } | |
1977 | ||
1978 | int start_stop_khugepaged(void) | |
1979 | { | |
1980 | static struct task_struct *khugepaged_thread __read_mostly; | |
1981 | static DEFINE_MUTEX(khugepaged_mutex); | |
1982 | int err = 0; | |
1983 | ||
1984 | mutex_lock(&khugepaged_mutex); | |
1985 | if (khugepaged_enabled()) { | |
1986 | if (!khugepaged_thread) | |
1987 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
1988 | "khugepaged"); | |
1989 | if (IS_ERR(khugepaged_thread)) { | |
1990 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); | |
1991 | err = PTR_ERR(khugepaged_thread); | |
1992 | khugepaged_thread = NULL; | |
1993 | goto fail; | |
1994 | } | |
1995 | ||
1996 | if (!list_empty(&khugepaged_scan.mm_head)) | |
1997 | wake_up_interruptible(&khugepaged_wait); | |
1998 | ||
1999 | set_recommended_min_free_kbytes(); | |
2000 | } else if (khugepaged_thread) { | |
2001 | kthread_stop(khugepaged_thread); | |
2002 | khugepaged_thread = NULL; | |
2003 | } | |
2004 | fail: | |
2005 | mutex_unlock(&khugepaged_mutex); | |
2006 | return err; | |
2007 | } |