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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, | |
e1e267c7 | 32 | SCAN_PTE_UFFD_WP, |
b46e756f | 33 | SCAN_PAGE_RO, |
0db501f7 | 34 | SCAN_LACK_REFERENCED_PAGE, |
b46e756f KS |
35 | SCAN_PAGE_NULL, |
36 | SCAN_SCAN_ABORT, | |
37 | SCAN_PAGE_COUNT, | |
38 | SCAN_PAGE_LRU, | |
39 | SCAN_PAGE_LOCK, | |
40 | SCAN_PAGE_ANON, | |
41 | SCAN_PAGE_COMPOUND, | |
42 | SCAN_ANY_PROCESS, | |
43 | SCAN_VMA_NULL, | |
44 | SCAN_VMA_CHECK, | |
45 | SCAN_ADDRESS_RANGE, | |
46 | SCAN_SWAP_CACHE_PAGE, | |
47 | SCAN_DEL_PAGE_LRU, | |
48 | SCAN_ALLOC_HUGE_PAGE_FAIL, | |
49 | SCAN_CGROUP_CHARGE_FAIL, | |
f3f0e1d2 KS |
50 | SCAN_EXCEED_SWAP_PTE, |
51 | SCAN_TRUNCATED, | |
99cb0dbd | 52 | SCAN_PAGE_HAS_PRIVATE, |
b46e756f KS |
53 | }; |
54 | ||
55 | #define CREATE_TRACE_POINTS | |
56 | #include <trace/events/huge_memory.h> | |
57 | ||
58 | /* default scan 8*512 pte (or vmas) every 30 second */ | |
59 | static unsigned int khugepaged_pages_to_scan __read_mostly; | |
60 | static unsigned int khugepaged_pages_collapsed; | |
61 | static unsigned int khugepaged_full_scans; | |
62 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
63 | /* during fragmentation poll the hugepage allocator once every minute */ | |
64 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
65 | static unsigned long khugepaged_sleep_expire; | |
66 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
67 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
68 | /* | |
69 | * default collapse hugepages if there is at least one pte mapped like | |
70 | * it would have happened if the vma was large enough during page | |
71 | * fault. | |
72 | */ | |
73 | static unsigned int khugepaged_max_ptes_none __read_mostly; | |
74 | static unsigned int khugepaged_max_ptes_swap __read_mostly; | |
75 | ||
76 | #define MM_SLOTS_HASH_BITS 10 | |
77 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
78 | ||
79 | static struct kmem_cache *mm_slot_cache __read_mostly; | |
80 | ||
27e1f827 SL |
81 | #define MAX_PTE_MAPPED_THP 8 |
82 | ||
b46e756f KS |
83 | /** |
84 | * struct mm_slot - hash lookup from mm to mm_slot | |
85 | * @hash: hash collision list | |
86 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
87 | * @mm: the mm that this information is valid for | |
88 | */ | |
89 | struct mm_slot { | |
90 | struct hlist_node hash; | |
91 | struct list_head mm_node; | |
92 | struct mm_struct *mm; | |
27e1f827 SL |
93 | |
94 | /* pte-mapped THP in this mm */ | |
95 | int nr_pte_mapped_thp; | |
96 | unsigned long pte_mapped_thp[MAX_PTE_MAPPED_THP]; | |
b46e756f KS |
97 | }; |
98 | ||
99 | /** | |
100 | * struct khugepaged_scan - cursor for scanning | |
101 | * @mm_head: the head of the mm list to scan | |
102 | * @mm_slot: the current mm_slot we are scanning | |
103 | * @address: the next address inside that to be scanned | |
104 | * | |
105 | * There is only the one khugepaged_scan instance of this cursor structure. | |
106 | */ | |
107 | struct khugepaged_scan { | |
108 | struct list_head mm_head; | |
109 | struct mm_slot *mm_slot; | |
110 | unsigned long address; | |
111 | }; | |
112 | ||
113 | static struct khugepaged_scan khugepaged_scan = { | |
114 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), | |
115 | }; | |
116 | ||
e1465d12 | 117 | #ifdef CONFIG_SYSFS |
b46e756f KS |
118 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, |
119 | struct kobj_attribute *attr, | |
120 | char *buf) | |
121 | { | |
122 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
123 | } | |
124 | ||
125 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
126 | struct kobj_attribute *attr, | |
127 | const char *buf, size_t count) | |
128 | { | |
129 | unsigned long msecs; | |
130 | int err; | |
131 | ||
132 | err = kstrtoul(buf, 10, &msecs); | |
133 | if (err || msecs > UINT_MAX) | |
134 | return -EINVAL; | |
135 | ||
136 | khugepaged_scan_sleep_millisecs = msecs; | |
137 | khugepaged_sleep_expire = 0; | |
138 | wake_up_interruptible(&khugepaged_wait); | |
139 | ||
140 | return count; | |
141 | } | |
142 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
143 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
144 | scan_sleep_millisecs_store); | |
145 | ||
146 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
147 | struct kobj_attribute *attr, | |
148 | char *buf) | |
149 | { | |
150 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
151 | } | |
152 | ||
153 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
154 | struct kobj_attribute *attr, | |
155 | const char *buf, size_t count) | |
156 | { | |
157 | unsigned long msecs; | |
158 | int err; | |
159 | ||
160 | err = kstrtoul(buf, 10, &msecs); | |
161 | if (err || msecs > UINT_MAX) | |
162 | return -EINVAL; | |
163 | ||
164 | khugepaged_alloc_sleep_millisecs = msecs; | |
165 | khugepaged_sleep_expire = 0; | |
166 | wake_up_interruptible(&khugepaged_wait); | |
167 | ||
168 | return count; | |
169 | } | |
170 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
171 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
172 | alloc_sleep_millisecs_store); | |
173 | ||
174 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
175 | struct kobj_attribute *attr, | |
176 | char *buf) | |
177 | { | |
178 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
179 | } | |
180 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
181 | struct kobj_attribute *attr, | |
182 | const char *buf, size_t count) | |
183 | { | |
184 | int err; | |
185 | unsigned long pages; | |
186 | ||
187 | err = kstrtoul(buf, 10, &pages); | |
188 | if (err || !pages || pages > UINT_MAX) | |
189 | return -EINVAL; | |
190 | ||
191 | khugepaged_pages_to_scan = pages; | |
192 | ||
193 | return count; | |
194 | } | |
195 | static struct kobj_attribute pages_to_scan_attr = | |
196 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
197 | pages_to_scan_store); | |
198 | ||
199 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
200 | struct kobj_attribute *attr, | |
201 | char *buf) | |
202 | { | |
203 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
204 | } | |
205 | static struct kobj_attribute pages_collapsed_attr = | |
206 | __ATTR_RO(pages_collapsed); | |
207 | ||
208 | static ssize_t full_scans_show(struct kobject *kobj, | |
209 | struct kobj_attribute *attr, | |
210 | char *buf) | |
211 | { | |
212 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
213 | } | |
214 | static struct kobj_attribute full_scans_attr = | |
215 | __ATTR_RO(full_scans); | |
216 | ||
217 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
218 | struct kobj_attribute *attr, char *buf) | |
219 | { | |
220 | return single_hugepage_flag_show(kobj, attr, buf, | |
221 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
222 | } | |
223 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
224 | struct kobj_attribute *attr, | |
225 | const char *buf, size_t count) | |
226 | { | |
227 | return single_hugepage_flag_store(kobj, attr, buf, count, | |
228 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
229 | } | |
230 | static struct kobj_attribute khugepaged_defrag_attr = | |
231 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
232 | khugepaged_defrag_store); | |
233 | ||
234 | /* | |
235 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
236 | * any unmapped ptes in turn potentially increasing the memory | |
237 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
238 | * reduce the available free memory in the system as it | |
239 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
240 | * free memory in the system during the khugepaged scan. | |
241 | */ | |
242 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
243 | struct kobj_attribute *attr, | |
244 | char *buf) | |
245 | { | |
246 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
247 | } | |
248 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
249 | struct kobj_attribute *attr, | |
250 | const char *buf, size_t count) | |
251 | { | |
252 | int err; | |
253 | unsigned long max_ptes_none; | |
254 | ||
255 | err = kstrtoul(buf, 10, &max_ptes_none); | |
256 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
257 | return -EINVAL; | |
258 | ||
259 | khugepaged_max_ptes_none = max_ptes_none; | |
260 | ||
261 | return count; | |
262 | } | |
263 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
264 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
265 | khugepaged_max_ptes_none_store); | |
266 | ||
267 | static ssize_t khugepaged_max_ptes_swap_show(struct kobject *kobj, | |
268 | struct kobj_attribute *attr, | |
269 | char *buf) | |
270 | { | |
271 | return sprintf(buf, "%u\n", khugepaged_max_ptes_swap); | |
272 | } | |
273 | ||
274 | static ssize_t khugepaged_max_ptes_swap_store(struct kobject *kobj, | |
275 | struct kobj_attribute *attr, | |
276 | const char *buf, size_t count) | |
277 | { | |
278 | int err; | |
279 | unsigned long max_ptes_swap; | |
280 | ||
281 | err = kstrtoul(buf, 10, &max_ptes_swap); | |
282 | if (err || max_ptes_swap > HPAGE_PMD_NR-1) | |
283 | return -EINVAL; | |
284 | ||
285 | khugepaged_max_ptes_swap = max_ptes_swap; | |
286 | ||
287 | return count; | |
288 | } | |
289 | ||
290 | static struct kobj_attribute khugepaged_max_ptes_swap_attr = | |
291 | __ATTR(max_ptes_swap, 0644, khugepaged_max_ptes_swap_show, | |
292 | khugepaged_max_ptes_swap_store); | |
293 | ||
294 | static struct attribute *khugepaged_attr[] = { | |
295 | &khugepaged_defrag_attr.attr, | |
296 | &khugepaged_max_ptes_none_attr.attr, | |
297 | &pages_to_scan_attr.attr, | |
298 | &pages_collapsed_attr.attr, | |
299 | &full_scans_attr.attr, | |
300 | &scan_sleep_millisecs_attr.attr, | |
301 | &alloc_sleep_millisecs_attr.attr, | |
302 | &khugepaged_max_ptes_swap_attr.attr, | |
303 | NULL, | |
304 | }; | |
305 | ||
306 | struct attribute_group khugepaged_attr_group = { | |
307 | .attrs = khugepaged_attr, | |
308 | .name = "khugepaged", | |
309 | }; | |
e1465d12 | 310 | #endif /* CONFIG_SYSFS */ |
b46e756f | 311 | |
b46e756f KS |
312 | int hugepage_madvise(struct vm_area_struct *vma, |
313 | unsigned long *vm_flags, int advice) | |
314 | { | |
315 | switch (advice) { | |
316 | case MADV_HUGEPAGE: | |
317 | #ifdef CONFIG_S390 | |
318 | /* | |
319 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
320 | * can't handle this properly after s390_enable_sie, so we simply | |
321 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
322 | */ | |
323 | if (mm_has_pgste(vma->vm_mm)) | |
324 | return 0; | |
325 | #endif | |
326 | *vm_flags &= ~VM_NOHUGEPAGE; | |
327 | *vm_flags |= VM_HUGEPAGE; | |
328 | /* | |
329 | * If the vma become good for khugepaged to scan, | |
330 | * register it here without waiting a page fault that | |
331 | * may not happen any time soon. | |
332 | */ | |
333 | if (!(*vm_flags & VM_NO_KHUGEPAGED) && | |
334 | khugepaged_enter_vma_merge(vma, *vm_flags)) | |
335 | return -ENOMEM; | |
336 | break; | |
337 | case MADV_NOHUGEPAGE: | |
338 | *vm_flags &= ~VM_HUGEPAGE; | |
339 | *vm_flags |= VM_NOHUGEPAGE; | |
340 | /* | |
341 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
342 | * this vma even if we leave the mm registered in khugepaged if | |
343 | * it got registered before VM_NOHUGEPAGE was set. | |
344 | */ | |
345 | break; | |
346 | } | |
347 | ||
348 | return 0; | |
349 | } | |
350 | ||
351 | int __init khugepaged_init(void) | |
352 | { | |
353 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
354 | sizeof(struct mm_slot), | |
355 | __alignof__(struct mm_slot), 0, NULL); | |
356 | if (!mm_slot_cache) | |
357 | return -ENOMEM; | |
358 | ||
359 | khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; | |
360 | khugepaged_max_ptes_none = HPAGE_PMD_NR - 1; | |
361 | khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8; | |
362 | ||
363 | return 0; | |
364 | } | |
365 | ||
366 | void __init khugepaged_destroy(void) | |
367 | { | |
368 | kmem_cache_destroy(mm_slot_cache); | |
369 | } | |
370 | ||
371 | static inline struct mm_slot *alloc_mm_slot(void) | |
372 | { | |
373 | if (!mm_slot_cache) /* initialization failed */ | |
374 | return NULL; | |
375 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
376 | } | |
377 | ||
378 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
379 | { | |
380 | kmem_cache_free(mm_slot_cache, mm_slot); | |
381 | } | |
382 | ||
383 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
384 | { | |
385 | struct mm_slot *mm_slot; | |
386 | ||
387 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) | |
388 | if (mm == mm_slot->mm) | |
389 | return mm_slot; | |
390 | ||
391 | return NULL; | |
392 | } | |
393 | ||
394 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
395 | struct mm_slot *mm_slot) | |
396 | { | |
397 | mm_slot->mm = mm; | |
398 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); | |
399 | } | |
400 | ||
401 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
402 | { | |
403 | return atomic_read(&mm->mm_users) == 0; | |
404 | } | |
405 | ||
50f8b92f SL |
406 | static bool hugepage_vma_check(struct vm_area_struct *vma, |
407 | unsigned long vm_flags) | |
c2231020 | 408 | { |
50f8b92f SL |
409 | if ((!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || |
410 | (vm_flags & VM_NOHUGEPAGE) || | |
c2231020 YS |
411 | test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) |
412 | return false; | |
99cb0dbd SL |
413 | |
414 | if (shmem_file(vma->vm_file) || | |
415 | (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && | |
416 | vma->vm_file && | |
417 | (vm_flags & VM_DENYWRITE))) { | |
c2231020 YS |
418 | return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, |
419 | HPAGE_PMD_NR); | |
420 | } | |
421 | if (!vma->anon_vma || vma->vm_ops) | |
422 | return false; | |
222100ee | 423 | if (vma_is_temporary_stack(vma)) |
c2231020 | 424 | return false; |
50f8b92f | 425 | return !(vm_flags & VM_NO_KHUGEPAGED); |
c2231020 YS |
426 | } |
427 | ||
b46e756f KS |
428 | int __khugepaged_enter(struct mm_struct *mm) |
429 | { | |
430 | struct mm_slot *mm_slot; | |
431 | int wakeup; | |
432 | ||
433 | mm_slot = alloc_mm_slot(); | |
434 | if (!mm_slot) | |
435 | return -ENOMEM; | |
436 | ||
437 | /* __khugepaged_exit() must not run from under us */ | |
438 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); | |
439 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { | |
440 | free_mm_slot(mm_slot); | |
441 | return 0; | |
442 | } | |
443 | ||
444 | spin_lock(&khugepaged_mm_lock); | |
445 | insert_to_mm_slots_hash(mm, mm_slot); | |
446 | /* | |
447 | * Insert just behind the scanning cursor, to let the area settle | |
448 | * down a little. | |
449 | */ | |
450 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
451 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
452 | spin_unlock(&khugepaged_mm_lock); | |
453 | ||
f1f10076 | 454 | mmgrab(mm); |
b46e756f KS |
455 | if (wakeup) |
456 | wake_up_interruptible(&khugepaged_wait); | |
457 | ||
458 | return 0; | |
459 | } | |
460 | ||
461 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, | |
462 | unsigned long vm_flags) | |
463 | { | |
464 | unsigned long hstart, hend; | |
c2231020 YS |
465 | |
466 | /* | |
99cb0dbd SL |
467 | * khugepaged only supports read-only files for non-shmem files. |
468 | * khugepaged does not yet work on special mappings. And | |
469 | * file-private shmem THP is not supported. | |
c2231020 | 470 | */ |
50f8b92f | 471 | if (!hugepage_vma_check(vma, vm_flags)) |
b46e756f | 472 | return 0; |
c2231020 | 473 | |
b46e756f KS |
474 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
475 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
476 | if (hstart < hend) | |
477 | return khugepaged_enter(vma, vm_flags); | |
478 | return 0; | |
479 | } | |
480 | ||
481 | void __khugepaged_exit(struct mm_struct *mm) | |
482 | { | |
483 | struct mm_slot *mm_slot; | |
484 | int free = 0; | |
485 | ||
486 | spin_lock(&khugepaged_mm_lock); | |
487 | mm_slot = get_mm_slot(mm); | |
488 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
489 | hash_del(&mm_slot->hash); | |
490 | list_del(&mm_slot->mm_node); | |
491 | free = 1; | |
492 | } | |
493 | spin_unlock(&khugepaged_mm_lock); | |
494 | ||
495 | if (free) { | |
496 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
497 | free_mm_slot(mm_slot); | |
498 | mmdrop(mm); | |
499 | } else if (mm_slot) { | |
500 | /* | |
501 | * This is required to serialize against | |
502 | * khugepaged_test_exit() (which is guaranteed to run | |
503 | * under mmap sem read mode). Stop here (after we | |
504 | * return all pagetables will be destroyed) until | |
505 | * khugepaged has finished working on the pagetables | |
506 | * under the mmap_sem. | |
507 | */ | |
508 | down_write(&mm->mmap_sem); | |
509 | up_write(&mm->mmap_sem); | |
510 | } | |
511 | } | |
512 | ||
513 | static void release_pte_page(struct page *page) | |
514 | { | |
5503fbf2 KS |
515 | mod_node_page_state(page_pgdat(page), |
516 | NR_ISOLATED_ANON + page_is_file_lru(page), | |
517 | -compound_nr(page)); | |
b46e756f KS |
518 | unlock_page(page); |
519 | putback_lru_page(page); | |
520 | } | |
521 | ||
5503fbf2 KS |
522 | static void release_pte_pages(pte_t *pte, pte_t *_pte, |
523 | struct list_head *compound_pagelist) | |
b46e756f | 524 | { |
5503fbf2 KS |
525 | struct page *page, *tmp; |
526 | ||
b46e756f KS |
527 | while (--_pte >= pte) { |
528 | pte_t pteval = *_pte; | |
5503fbf2 KS |
529 | |
530 | page = pte_page(pteval); | |
531 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)) && | |
532 | !PageCompound(page)) | |
533 | release_pte_page(page); | |
534 | } | |
535 | ||
536 | list_for_each_entry_safe(page, tmp, compound_pagelist, lru) { | |
537 | list_del(&page->lru); | |
538 | release_pte_page(page); | |
b46e756f KS |
539 | } |
540 | } | |
541 | ||
9445689f KS |
542 | static bool is_refcount_suitable(struct page *page) |
543 | { | |
544 | int expected_refcount; | |
545 | ||
546 | expected_refcount = total_mapcount(page); | |
547 | if (PageSwapCache(page)) | |
548 | expected_refcount += compound_nr(page); | |
549 | ||
550 | return page_count(page) == expected_refcount; | |
551 | } | |
552 | ||
b46e756f KS |
553 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, |
554 | unsigned long address, | |
5503fbf2 KS |
555 | pte_t *pte, |
556 | struct list_head *compound_pagelist) | |
b46e756f KS |
557 | { |
558 | struct page *page = NULL; | |
559 | pte_t *_pte; | |
0db501f7 EA |
560 | int none_or_zero = 0, result = 0, referenced = 0; |
561 | bool writable = false; | |
b46e756f KS |
562 | |
563 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
564 | _pte++, address += PAGE_SIZE) { | |
565 | pte_t pteval = *_pte; | |
566 | if (pte_none(pteval) || (pte_present(pteval) && | |
567 | is_zero_pfn(pte_pfn(pteval)))) { | |
568 | if (!userfaultfd_armed(vma) && | |
569 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
570 | continue; | |
571 | } else { | |
572 | result = SCAN_EXCEED_NONE_PTE; | |
573 | goto out; | |
574 | } | |
575 | } | |
576 | if (!pte_present(pteval)) { | |
577 | result = SCAN_PTE_NON_PRESENT; | |
578 | goto out; | |
579 | } | |
580 | page = vm_normal_page(vma, address, pteval); | |
581 | if (unlikely(!page)) { | |
582 | result = SCAN_PAGE_NULL; | |
583 | goto out; | |
584 | } | |
585 | ||
5503fbf2 KS |
586 | VM_BUG_ON_PAGE(!PageAnon(page), page); |
587 | ||
fece2029 | 588 | if (PageCompound(page)) { |
5503fbf2 KS |
589 | struct page *p; |
590 | page = compound_head(page); | |
fece2029 | 591 | |
5503fbf2 KS |
592 | /* |
593 | * Check if we have dealt with the compound page | |
594 | * already | |
595 | */ | |
596 | list_for_each_entry(p, compound_pagelist, lru) { | |
597 | if (page == p) | |
598 | goto next; | |
599 | } | |
600 | } | |
b46e756f KS |
601 | |
602 | /* | |
603 | * We can do it before isolate_lru_page because the | |
604 | * page can't be freed from under us. NOTE: PG_lock | |
605 | * is needed to serialize against split_huge_page | |
606 | * when invoked from the VM. | |
607 | */ | |
608 | if (!trylock_page(page)) { | |
609 | result = SCAN_PAGE_LOCK; | |
610 | goto out; | |
611 | } | |
612 | ||
613 | /* | |
9445689f KS |
614 | * Check if the page has any GUP (or other external) pins. |
615 | * | |
616 | * The page table that maps the page has been already unlinked | |
617 | * from the page table tree and this process cannot get | |
618 | * an additinal pin on the page. | |
619 | * | |
620 | * New pins can come later if the page is shared across fork, | |
621 | * but not from this process. The other process cannot write to | |
622 | * the page, only trigger CoW. | |
b46e756f | 623 | */ |
9445689f | 624 | if (!is_refcount_suitable(page)) { |
b46e756f KS |
625 | unlock_page(page); |
626 | result = SCAN_PAGE_COUNT; | |
627 | goto out; | |
628 | } | |
5503fbf2 KS |
629 | if (!pte_write(pteval) && PageSwapCache(page) && |
630 | !reuse_swap_page(page, NULL)) { | |
b46e756f | 631 | /* |
5503fbf2 KS |
632 | * Page is in the swap cache and cannot be re-used. |
633 | * It cannot be collapsed into a THP. | |
b46e756f | 634 | */ |
5503fbf2 KS |
635 | unlock_page(page); |
636 | result = SCAN_SWAP_CACHE_PAGE; | |
637 | goto out; | |
b46e756f KS |
638 | } |
639 | ||
640 | /* | |
641 | * Isolate the page to avoid collapsing an hugepage | |
642 | * currently in use by the VM. | |
643 | */ | |
644 | if (isolate_lru_page(page)) { | |
645 | unlock_page(page); | |
646 | result = SCAN_DEL_PAGE_LRU; | |
647 | goto out; | |
648 | } | |
5503fbf2 KS |
649 | mod_node_page_state(page_pgdat(page), |
650 | NR_ISOLATED_ANON + page_is_file_lru(page), | |
651 | compound_nr(page)); | |
b46e756f KS |
652 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
653 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
654 | ||
5503fbf2 KS |
655 | if (PageCompound(page)) |
656 | list_add_tail(&page->lru, compound_pagelist); | |
657 | next: | |
0db501f7 | 658 | /* There should be enough young pte to collapse the page */ |
b46e756f KS |
659 | if (pte_young(pteval) || |
660 | page_is_young(page) || PageReferenced(page) || | |
661 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 662 | referenced++; |
5503fbf2 KS |
663 | |
664 | if (pte_write(pteval)) | |
665 | writable = true; | |
b46e756f KS |
666 | } |
667 | if (likely(writable)) { | |
668 | if (likely(referenced)) { | |
669 | result = SCAN_SUCCEED; | |
670 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, | |
671 | referenced, writable, result); | |
672 | return 1; | |
673 | } | |
674 | } else { | |
675 | result = SCAN_PAGE_RO; | |
676 | } | |
677 | ||
678 | out: | |
5503fbf2 | 679 | release_pte_pages(pte, _pte, compound_pagelist); |
b46e756f KS |
680 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, |
681 | referenced, writable, result); | |
682 | return 0; | |
683 | } | |
684 | ||
685 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
686 | struct vm_area_struct *vma, | |
687 | unsigned long address, | |
5503fbf2 KS |
688 | spinlock_t *ptl, |
689 | struct list_head *compound_pagelist) | |
b46e756f | 690 | { |
5503fbf2 | 691 | struct page *src_page, *tmp; |
b46e756f | 692 | pte_t *_pte; |
338a16ba DR |
693 | for (_pte = pte; _pte < pte + HPAGE_PMD_NR; |
694 | _pte++, page++, address += PAGE_SIZE) { | |
b46e756f | 695 | pte_t pteval = *_pte; |
b46e756f KS |
696 | |
697 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
698 | clear_user_highpage(page, address); | |
699 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
700 | if (is_zero_pfn(pte_pfn(pteval))) { | |
701 | /* | |
702 | * ptl mostly unnecessary. | |
703 | */ | |
704 | spin_lock(ptl); | |
705 | /* | |
706 | * paravirt calls inside pte_clear here are | |
707 | * superfluous. | |
708 | */ | |
709 | pte_clear(vma->vm_mm, address, _pte); | |
710 | spin_unlock(ptl); | |
711 | } | |
712 | } else { | |
713 | src_page = pte_page(pteval); | |
714 | copy_user_highpage(page, src_page, address, vma); | |
5503fbf2 KS |
715 | if (!PageCompound(src_page)) |
716 | release_pte_page(src_page); | |
b46e756f KS |
717 | /* |
718 | * ptl mostly unnecessary, but preempt has to | |
719 | * be disabled to update the per-cpu stats | |
720 | * inside page_remove_rmap(). | |
721 | */ | |
722 | spin_lock(ptl); | |
723 | /* | |
724 | * paravirt calls inside pte_clear here are | |
725 | * superfluous. | |
726 | */ | |
727 | pte_clear(vma->vm_mm, address, _pte); | |
728 | page_remove_rmap(src_page, false); | |
729 | spin_unlock(ptl); | |
730 | free_page_and_swap_cache(src_page); | |
731 | } | |
b46e756f | 732 | } |
5503fbf2 KS |
733 | |
734 | list_for_each_entry_safe(src_page, tmp, compound_pagelist, lru) { | |
735 | list_del(&src_page->lru); | |
736 | release_pte_page(src_page); | |
737 | } | |
b46e756f KS |
738 | } |
739 | ||
740 | static void khugepaged_alloc_sleep(void) | |
741 | { | |
742 | DEFINE_WAIT(wait); | |
743 | ||
744 | add_wait_queue(&khugepaged_wait, &wait); | |
745 | freezable_schedule_timeout_interruptible( | |
746 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
747 | remove_wait_queue(&khugepaged_wait, &wait); | |
748 | } | |
749 | ||
750 | static int khugepaged_node_load[MAX_NUMNODES]; | |
751 | ||
752 | static bool khugepaged_scan_abort(int nid) | |
753 | { | |
754 | int i; | |
755 | ||
756 | /* | |
a5f5f91d | 757 | * If node_reclaim_mode is disabled, then no extra effort is made to |
b46e756f KS |
758 | * allocate memory locally. |
759 | */ | |
a5f5f91d | 760 | if (!node_reclaim_mode) |
b46e756f KS |
761 | return false; |
762 | ||
763 | /* If there is a count for this node already, it must be acceptable */ | |
764 | if (khugepaged_node_load[nid]) | |
765 | return false; | |
766 | ||
767 | for (i = 0; i < MAX_NUMNODES; i++) { | |
768 | if (!khugepaged_node_load[i]) | |
769 | continue; | |
a55c7454 | 770 | if (node_distance(nid, i) > node_reclaim_distance) |
b46e756f KS |
771 | return true; |
772 | } | |
773 | return false; | |
774 | } | |
775 | ||
776 | /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */ | |
777 | static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void) | |
778 | { | |
25160354 | 779 | return khugepaged_defrag() ? GFP_TRANSHUGE : GFP_TRANSHUGE_LIGHT; |
b46e756f KS |
780 | } |
781 | ||
782 | #ifdef CONFIG_NUMA | |
783 | static int khugepaged_find_target_node(void) | |
784 | { | |
785 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
786 | int nid, target_node = 0, max_value = 0; | |
787 | ||
788 | /* find first node with max normal pages hit */ | |
789 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
790 | if (khugepaged_node_load[nid] > max_value) { | |
791 | max_value = khugepaged_node_load[nid]; | |
792 | target_node = nid; | |
793 | } | |
794 | ||
795 | /* do some balance if several nodes have the same hit record */ | |
796 | if (target_node <= last_khugepaged_target_node) | |
797 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
798 | nid++) | |
799 | if (max_value == khugepaged_node_load[nid]) { | |
800 | target_node = nid; | |
801 | break; | |
802 | } | |
803 | ||
804 | last_khugepaged_target_node = target_node; | |
805 | return target_node; | |
806 | } | |
807 | ||
808 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
809 | { | |
810 | if (IS_ERR(*hpage)) { | |
811 | if (!*wait) | |
812 | return false; | |
813 | ||
814 | *wait = false; | |
815 | *hpage = NULL; | |
816 | khugepaged_alloc_sleep(); | |
817 | } else if (*hpage) { | |
818 | put_page(*hpage); | |
819 | *hpage = NULL; | |
820 | } | |
821 | ||
822 | return true; | |
823 | } | |
824 | ||
825 | static struct page * | |
988ddb71 | 826 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f KS |
827 | { |
828 | VM_BUG_ON_PAGE(*hpage, *hpage); | |
829 | ||
b46e756f KS |
830 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); |
831 | if (unlikely(!*hpage)) { | |
832 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
833 | *hpage = ERR_PTR(-ENOMEM); | |
834 | return NULL; | |
835 | } | |
836 | ||
837 | prep_transhuge_page(*hpage); | |
838 | count_vm_event(THP_COLLAPSE_ALLOC); | |
839 | return *hpage; | |
840 | } | |
841 | #else | |
842 | static int khugepaged_find_target_node(void) | |
843 | { | |
844 | return 0; | |
845 | } | |
846 | ||
847 | static inline struct page *alloc_khugepaged_hugepage(void) | |
848 | { | |
849 | struct page *page; | |
850 | ||
851 | page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(), | |
852 | HPAGE_PMD_ORDER); | |
853 | if (page) | |
854 | prep_transhuge_page(page); | |
855 | return page; | |
856 | } | |
857 | ||
858 | static struct page *khugepaged_alloc_hugepage(bool *wait) | |
859 | { | |
860 | struct page *hpage; | |
861 | ||
862 | do { | |
863 | hpage = alloc_khugepaged_hugepage(); | |
864 | if (!hpage) { | |
865 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
866 | if (!*wait) | |
867 | return NULL; | |
868 | ||
869 | *wait = false; | |
870 | khugepaged_alloc_sleep(); | |
871 | } else | |
872 | count_vm_event(THP_COLLAPSE_ALLOC); | |
873 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
874 | ||
875 | return hpage; | |
876 | } | |
877 | ||
878 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
879 | { | |
880 | if (!*hpage) | |
881 | *hpage = khugepaged_alloc_hugepage(wait); | |
882 | ||
883 | if (unlikely(!*hpage)) | |
884 | return false; | |
885 | ||
886 | return true; | |
887 | } | |
888 | ||
889 | static struct page * | |
988ddb71 | 890 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f | 891 | { |
b46e756f KS |
892 | VM_BUG_ON(!*hpage); |
893 | ||
894 | return *hpage; | |
895 | } | |
896 | #endif | |
897 | ||
b46e756f KS |
898 | /* |
899 | * If mmap_sem temporarily dropped, revalidate vma | |
900 | * before taking mmap_sem. | |
901 | * Return 0 if succeeds, otherwise return none-zero | |
902 | * value (scan code). | |
903 | */ | |
904 | ||
c131f751 KS |
905 | static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, |
906 | struct vm_area_struct **vmap) | |
b46e756f KS |
907 | { |
908 | struct vm_area_struct *vma; | |
909 | unsigned long hstart, hend; | |
910 | ||
911 | if (unlikely(khugepaged_test_exit(mm))) | |
912 | return SCAN_ANY_PROCESS; | |
913 | ||
c131f751 | 914 | *vmap = vma = find_vma(mm, address); |
b46e756f KS |
915 | if (!vma) |
916 | return SCAN_VMA_NULL; | |
917 | ||
918 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
919 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
920 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
921 | return SCAN_ADDRESS_RANGE; | |
50f8b92f | 922 | if (!hugepage_vma_check(vma, vma->vm_flags)) |
b46e756f KS |
923 | return SCAN_VMA_CHECK; |
924 | return 0; | |
925 | } | |
926 | ||
927 | /* | |
928 | * Bring missing pages in from swap, to complete THP collapse. | |
929 | * Only done if khugepaged_scan_pmd believes it is worthwhile. | |
930 | * | |
931 | * Called and returns without pte mapped or spinlocks held, | |
932 | * but with mmap_sem held to protect against vma changes. | |
933 | */ | |
934 | ||
935 | static bool __collapse_huge_page_swapin(struct mm_struct *mm, | |
936 | struct vm_area_struct *vma, | |
0db501f7 EA |
937 | unsigned long address, pmd_t *pmd, |
938 | int referenced) | |
b46e756f | 939 | { |
2b740303 SJ |
940 | int swapped_in = 0; |
941 | vm_fault_t ret = 0; | |
82b0f8c3 | 942 | struct vm_fault vmf = { |
b46e756f KS |
943 | .vma = vma, |
944 | .address = address, | |
945 | .flags = FAULT_FLAG_ALLOW_RETRY, | |
946 | .pmd = pmd, | |
0721ec8b | 947 | .pgoff = linear_page_index(vma, address), |
b46e756f KS |
948 | }; |
949 | ||
82b0f8c3 JK |
950 | vmf.pte = pte_offset_map(pmd, address); |
951 | for (; vmf.address < address + HPAGE_PMD_NR*PAGE_SIZE; | |
952 | vmf.pte++, vmf.address += PAGE_SIZE) { | |
2994302b JK |
953 | vmf.orig_pte = *vmf.pte; |
954 | if (!is_swap_pte(vmf.orig_pte)) | |
b46e756f KS |
955 | continue; |
956 | swapped_in++; | |
2994302b | 957 | ret = do_swap_page(&vmf); |
0db501f7 | 958 | |
b46e756f KS |
959 | /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */ |
960 | if (ret & VM_FAULT_RETRY) { | |
961 | down_read(&mm->mmap_sem); | |
82b0f8c3 | 962 | if (hugepage_vma_revalidate(mm, address, &vmf.vma)) { |
47f863ea | 963 | /* vma is no longer available, don't continue to swapin */ |
0db501f7 | 964 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f | 965 | return false; |
47f863ea | 966 | } |
b46e756f | 967 | /* check if the pmd is still valid */ |
835152a2 SP |
968 | if (mm_find_pmd(mm, address) != pmd) { |
969 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); | |
b46e756f | 970 | return false; |
835152a2 | 971 | } |
b46e756f KS |
972 | } |
973 | if (ret & VM_FAULT_ERROR) { | |
0db501f7 | 974 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f KS |
975 | return false; |
976 | } | |
977 | /* pte is unmapped now, we need to map it */ | |
82b0f8c3 | 978 | vmf.pte = pte_offset_map(pmd, vmf.address); |
b46e756f | 979 | } |
82b0f8c3 JK |
980 | vmf.pte--; |
981 | pte_unmap(vmf.pte); | |
ae2c5d80 KS |
982 | |
983 | /* Drain LRU add pagevec to remove extra pin on the swapped in pages */ | |
984 | if (swapped_in) | |
985 | lru_add_drain(); | |
986 | ||
0db501f7 | 987 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1); |
b46e756f KS |
988 | return true; |
989 | } | |
990 | ||
991 | static void collapse_huge_page(struct mm_struct *mm, | |
992 | unsigned long address, | |
993 | struct page **hpage, | |
ffe945e6 | 994 | int node, int referenced, int unmapped) |
b46e756f | 995 | { |
5503fbf2 | 996 | LIST_HEAD(compound_pagelist); |
b46e756f KS |
997 | pmd_t *pmd, _pmd; |
998 | pte_t *pte; | |
999 | pgtable_t pgtable; | |
1000 | struct page *new_page; | |
1001 | spinlock_t *pmd_ptl, *pte_ptl; | |
1002 | int isolated = 0, result = 0; | |
1003 | struct mem_cgroup *memcg; | |
c131f751 | 1004 | struct vm_area_struct *vma; |
ac46d4f3 | 1005 | struct mmu_notifier_range range; |
b46e756f KS |
1006 | gfp_t gfp; |
1007 | ||
1008 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1009 | ||
1010 | /* Only allocate from the target node */ | |
41b6167e | 1011 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
b46e756f | 1012 | |
988ddb71 KS |
1013 | /* |
1014 | * Before allocating the hugepage, release the mmap_sem read lock. | |
1015 | * The allocation can take potentially a long time if it involves | |
1016 | * sync compaction, and we do not need to hold the mmap_sem during | |
1017 | * that. We will recheck the vma after taking it again in write mode. | |
1018 | */ | |
1019 | up_read(&mm->mmap_sem); | |
1020 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
b46e756f KS |
1021 | if (!new_page) { |
1022 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
1023 | goto out_nolock; | |
1024 | } | |
1025 | ||
2a70f6a7 | 1026 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { |
b46e756f KS |
1027 | result = SCAN_CGROUP_CHARGE_FAIL; |
1028 | goto out_nolock; | |
1029 | } | |
1030 | ||
1031 | down_read(&mm->mmap_sem); | |
c131f751 | 1032 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f KS |
1033 | if (result) { |
1034 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1035 | up_read(&mm->mmap_sem); | |
1036 | goto out_nolock; | |
1037 | } | |
1038 | ||
1039 | pmd = mm_find_pmd(mm, address); | |
1040 | if (!pmd) { | |
1041 | result = SCAN_PMD_NULL; | |
1042 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1043 | up_read(&mm->mmap_sem); | |
1044 | goto out_nolock; | |
1045 | } | |
1046 | ||
1047 | /* | |
1048 | * __collapse_huge_page_swapin always returns with mmap_sem locked. | |
47f863ea | 1049 | * If it fails, we release mmap_sem and jump out_nolock. |
b46e756f KS |
1050 | * Continuing to collapse causes inconsistency. |
1051 | */ | |
ffe945e6 KS |
1052 | if (unmapped && !__collapse_huge_page_swapin(mm, vma, address, |
1053 | pmd, referenced)) { | |
b46e756f KS |
1054 | mem_cgroup_cancel_charge(new_page, memcg, true); |
1055 | up_read(&mm->mmap_sem); | |
1056 | goto out_nolock; | |
1057 | } | |
1058 | ||
1059 | up_read(&mm->mmap_sem); | |
1060 | /* | |
1061 | * Prevent all access to pagetables with the exception of | |
1062 | * gup_fast later handled by the ptep_clear_flush and the VM | |
1063 | * handled by the anon_vma lock + PG_lock. | |
1064 | */ | |
1065 | down_write(&mm->mmap_sem); | |
59ea6d06 AA |
1066 | result = SCAN_ANY_PROCESS; |
1067 | if (!mmget_still_valid(mm)) | |
1068 | goto out; | |
c131f751 | 1069 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f KS |
1070 | if (result) |
1071 | goto out; | |
1072 | /* check if the pmd is still valid */ | |
1073 | if (mm_find_pmd(mm, address) != pmd) | |
1074 | goto out; | |
1075 | ||
1076 | anon_vma_lock_write(vma->anon_vma); | |
1077 | ||
7269f999 | 1078 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, |
6f4f13e8 | 1079 | address, address + HPAGE_PMD_SIZE); |
ac46d4f3 | 1080 | mmu_notifier_invalidate_range_start(&range); |
ec649c9d VS |
1081 | |
1082 | pte = pte_offset_map(pmd, address); | |
1083 | pte_ptl = pte_lockptr(mm, pmd); | |
1084 | ||
b46e756f KS |
1085 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
1086 | /* | |
1087 | * After this gup_fast can't run anymore. This also removes | |
1088 | * any huge TLB entry from the CPU so we won't allow | |
1089 | * huge and small TLB entries for the same virtual address | |
1090 | * to avoid the risk of CPU bugs in that area. | |
1091 | */ | |
1092 | _pmd = pmdp_collapse_flush(vma, address, pmd); | |
1093 | spin_unlock(pmd_ptl); | |
ac46d4f3 | 1094 | mmu_notifier_invalidate_range_end(&range); |
b46e756f KS |
1095 | |
1096 | spin_lock(pte_ptl); | |
5503fbf2 KS |
1097 | isolated = __collapse_huge_page_isolate(vma, address, pte, |
1098 | &compound_pagelist); | |
b46e756f KS |
1099 | spin_unlock(pte_ptl); |
1100 | ||
1101 | if (unlikely(!isolated)) { | |
1102 | pte_unmap(pte); | |
1103 | spin_lock(pmd_ptl); | |
1104 | BUG_ON(!pmd_none(*pmd)); | |
1105 | /* | |
1106 | * We can only use set_pmd_at when establishing | |
1107 | * hugepmds and never for establishing regular pmds that | |
1108 | * points to regular pagetables. Use pmd_populate for that | |
1109 | */ | |
1110 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
1111 | spin_unlock(pmd_ptl); | |
1112 | anon_vma_unlock_write(vma->anon_vma); | |
1113 | result = SCAN_FAIL; | |
1114 | goto out; | |
1115 | } | |
1116 | ||
1117 | /* | |
1118 | * All pages are isolated and locked so anon_vma rmap | |
1119 | * can't run anymore. | |
1120 | */ | |
1121 | anon_vma_unlock_write(vma->anon_vma); | |
1122 | ||
5503fbf2 KS |
1123 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl, |
1124 | &compound_pagelist); | |
b46e756f KS |
1125 | pte_unmap(pte); |
1126 | __SetPageUptodate(new_page); | |
1127 | pgtable = pmd_pgtable(_pmd); | |
1128 | ||
1129 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); | |
f55e1014 | 1130 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); |
b46e756f KS |
1131 | |
1132 | /* | |
1133 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
1134 | * this is needed to avoid the copy_huge_page writes to become | |
1135 | * visible after the set_pmd_at() write. | |
1136 | */ | |
1137 | smp_wmb(); | |
1138 | ||
1139 | spin_lock(pmd_ptl); | |
1140 | BUG_ON(!pmd_none(*pmd)); | |
1141 | page_add_new_anon_rmap(new_page, vma, address, true); | |
1142 | mem_cgroup_commit_charge(new_page, memcg, false, true); | |
1ff9e6e1 | 1143 | count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1); |
b46e756f KS |
1144 | lru_cache_add_active_or_unevictable(new_page, vma); |
1145 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
1146 | set_pmd_at(mm, address, pmd, _pmd); | |
1147 | update_mmu_cache_pmd(vma, address, pmd); | |
1148 | spin_unlock(pmd_ptl); | |
1149 | ||
1150 | *hpage = NULL; | |
1151 | ||
1152 | khugepaged_pages_collapsed++; | |
1153 | result = SCAN_SUCCEED; | |
1154 | out_up_write: | |
1155 | up_write(&mm->mmap_sem); | |
1156 | out_nolock: | |
1157 | trace_mm_collapse_huge_page(mm, isolated, result); | |
1158 | return; | |
1159 | out: | |
1160 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1161 | goto out_up_write; | |
1162 | } | |
1163 | ||
1164 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
1165 | struct vm_area_struct *vma, | |
1166 | unsigned long address, | |
1167 | struct page **hpage) | |
1168 | { | |
1169 | pmd_t *pmd; | |
1170 | pte_t *pte, *_pte; | |
0db501f7 | 1171 | int ret = 0, none_or_zero = 0, result = 0, referenced = 0; |
b46e756f KS |
1172 | struct page *page = NULL; |
1173 | unsigned long _address; | |
1174 | spinlock_t *ptl; | |
1175 | int node = NUMA_NO_NODE, unmapped = 0; | |
0db501f7 | 1176 | bool writable = false; |
b46e756f KS |
1177 | |
1178 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1179 | ||
1180 | pmd = mm_find_pmd(mm, address); | |
1181 | if (!pmd) { | |
1182 | result = SCAN_PMD_NULL; | |
1183 | goto out; | |
1184 | } | |
1185 | ||
1186 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1187 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1188 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1189 | _pte++, _address += PAGE_SIZE) { | |
1190 | pte_t pteval = *_pte; | |
1191 | if (is_swap_pte(pteval)) { | |
1192 | if (++unmapped <= khugepaged_max_ptes_swap) { | |
e1e267c7 PX |
1193 | /* |
1194 | * Always be strict with uffd-wp | |
1195 | * enabled swap entries. Please see | |
1196 | * comment below for pte_uffd_wp(). | |
1197 | */ | |
1198 | if (pte_swp_uffd_wp(pteval)) { | |
1199 | result = SCAN_PTE_UFFD_WP; | |
1200 | goto out_unmap; | |
1201 | } | |
b46e756f KS |
1202 | continue; |
1203 | } else { | |
1204 | result = SCAN_EXCEED_SWAP_PTE; | |
1205 | goto out_unmap; | |
1206 | } | |
1207 | } | |
1208 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
1209 | if (!userfaultfd_armed(vma) && | |
1210 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
1211 | continue; | |
1212 | } else { | |
1213 | result = SCAN_EXCEED_NONE_PTE; | |
1214 | goto out_unmap; | |
1215 | } | |
1216 | } | |
1217 | if (!pte_present(pteval)) { | |
1218 | result = SCAN_PTE_NON_PRESENT; | |
1219 | goto out_unmap; | |
1220 | } | |
e1e267c7 PX |
1221 | if (pte_uffd_wp(pteval)) { |
1222 | /* | |
1223 | * Don't collapse the page if any of the small | |
1224 | * PTEs are armed with uffd write protection. | |
1225 | * Here we can also mark the new huge pmd as | |
1226 | * write protected if any of the small ones is | |
1227 | * marked but that could bring uknown | |
1228 | * userfault messages that falls outside of | |
1229 | * the registered range. So, just be simple. | |
1230 | */ | |
1231 | result = SCAN_PTE_UFFD_WP; | |
1232 | goto out_unmap; | |
1233 | } | |
b46e756f KS |
1234 | if (pte_write(pteval)) |
1235 | writable = true; | |
1236 | ||
1237 | page = vm_normal_page(vma, _address, pteval); | |
1238 | if (unlikely(!page)) { | |
1239 | result = SCAN_PAGE_NULL; | |
1240 | goto out_unmap; | |
1241 | } | |
1242 | ||
5503fbf2 | 1243 | page = compound_head(page); |
b46e756f KS |
1244 | |
1245 | /* | |
1246 | * Record which node the original page is from and save this | |
1247 | * information to khugepaged_node_load[]. | |
1248 | * Khupaged will allocate hugepage from the node has the max | |
1249 | * hit record. | |
1250 | */ | |
1251 | node = page_to_nid(page); | |
1252 | if (khugepaged_scan_abort(node)) { | |
1253 | result = SCAN_SCAN_ABORT; | |
1254 | goto out_unmap; | |
1255 | } | |
1256 | khugepaged_node_load[node]++; | |
1257 | if (!PageLRU(page)) { | |
1258 | result = SCAN_PAGE_LRU; | |
1259 | goto out_unmap; | |
1260 | } | |
1261 | if (PageLocked(page)) { | |
1262 | result = SCAN_PAGE_LOCK; | |
1263 | goto out_unmap; | |
1264 | } | |
1265 | if (!PageAnon(page)) { | |
1266 | result = SCAN_PAGE_ANON; | |
1267 | goto out_unmap; | |
1268 | } | |
1269 | ||
1270 | /* | |
9445689f KS |
1271 | * Check if the page has any GUP (or other external) pins. |
1272 | * | |
1273 | * Here the check is racy it may see totmal_mapcount > refcount | |
1274 | * in some cases. | |
1275 | * For example, one process with one forked child process. | |
1276 | * The parent has the PMD split due to MADV_DONTNEED, then | |
1277 | * the child is trying unmap the whole PMD, but khugepaged | |
1278 | * may be scanning the parent between the child has | |
1279 | * PageDoubleMap flag cleared and dec the mapcount. So | |
1280 | * khugepaged may see total_mapcount > refcount. | |
1281 | * | |
1282 | * But such case is ephemeral we could always retry collapse | |
1283 | * later. However it may report false positive if the page | |
1284 | * has excessive GUP pins (i.e. 512). Anyway the same check | |
1285 | * will be done again later the risk seems low. | |
b46e756f | 1286 | */ |
9445689f | 1287 | if (!is_refcount_suitable(page)) { |
b46e756f KS |
1288 | result = SCAN_PAGE_COUNT; |
1289 | goto out_unmap; | |
1290 | } | |
1291 | if (pte_young(pteval) || | |
1292 | page_is_young(page) || PageReferenced(page) || | |
1293 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 1294 | referenced++; |
b46e756f | 1295 | } |
ffe945e6 | 1296 | if (!writable) { |
b46e756f | 1297 | result = SCAN_PAGE_RO; |
ffe945e6 KS |
1298 | } else if (!referenced || (unmapped && referenced < HPAGE_PMD_NR/2)) { |
1299 | result = SCAN_LACK_REFERENCED_PAGE; | |
1300 | } else { | |
1301 | result = SCAN_SUCCEED; | |
1302 | ret = 1; | |
b46e756f KS |
1303 | } |
1304 | out_unmap: | |
1305 | pte_unmap_unlock(pte, ptl); | |
1306 | if (ret) { | |
1307 | node = khugepaged_find_target_node(); | |
1308 | /* collapse_huge_page will return with the mmap_sem released */ | |
ffe945e6 KS |
1309 | collapse_huge_page(mm, address, hpage, node, |
1310 | referenced, unmapped); | |
b46e756f KS |
1311 | } |
1312 | out: | |
1313 | trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, | |
1314 | none_or_zero, result, unmapped); | |
1315 | return ret; | |
1316 | } | |
1317 | ||
1318 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
1319 | { | |
1320 | struct mm_struct *mm = mm_slot->mm; | |
1321 | ||
35f3aa39 | 1322 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
1323 | |
1324 | if (khugepaged_test_exit(mm)) { | |
1325 | /* free mm_slot */ | |
1326 | hash_del(&mm_slot->hash); | |
1327 | list_del(&mm_slot->mm_node); | |
1328 | ||
1329 | /* | |
1330 | * Not strictly needed because the mm exited already. | |
1331 | * | |
1332 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1333 | */ | |
1334 | ||
1335 | /* khugepaged_mm_lock actually not necessary for the below */ | |
1336 | free_mm_slot(mm_slot); | |
1337 | mmdrop(mm); | |
1338 | } | |
1339 | } | |
1340 | ||
396bcc52 | 1341 | #ifdef CONFIG_SHMEM |
27e1f827 SL |
1342 | /* |
1343 | * Notify khugepaged that given addr of the mm is pte-mapped THP. Then | |
1344 | * khugepaged should try to collapse the page table. | |
1345 | */ | |
1346 | static int khugepaged_add_pte_mapped_thp(struct mm_struct *mm, | |
1347 | unsigned long addr) | |
1348 | { | |
1349 | struct mm_slot *mm_slot; | |
1350 | ||
1351 | VM_BUG_ON(addr & ~HPAGE_PMD_MASK); | |
1352 | ||
1353 | spin_lock(&khugepaged_mm_lock); | |
1354 | mm_slot = get_mm_slot(mm); | |
1355 | if (likely(mm_slot && mm_slot->nr_pte_mapped_thp < MAX_PTE_MAPPED_THP)) | |
1356 | mm_slot->pte_mapped_thp[mm_slot->nr_pte_mapped_thp++] = addr; | |
1357 | spin_unlock(&khugepaged_mm_lock); | |
1358 | return 0; | |
1359 | } | |
1360 | ||
1361 | /** | |
1362 | * Try to collapse a pte-mapped THP for mm at address haddr. | |
1363 | * | |
1364 | * This function checks whether all the PTEs in the PMD are pointing to the | |
1365 | * right THP. If so, retract the page table so the THP can refault in with | |
1366 | * as pmd-mapped. | |
1367 | */ | |
1368 | void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) | |
1369 | { | |
1370 | unsigned long haddr = addr & HPAGE_PMD_MASK; | |
1371 | struct vm_area_struct *vma = find_vma(mm, haddr); | |
1372 | struct page *hpage = NULL; | |
1373 | pte_t *start_pte, *pte; | |
1374 | pmd_t *pmd, _pmd; | |
1375 | spinlock_t *ptl; | |
1376 | int count = 0; | |
1377 | int i; | |
1378 | ||
1379 | if (!vma || !vma->vm_file || | |
1380 | vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE) | |
1381 | return; | |
1382 | ||
1383 | /* | |
1384 | * This vm_flags may not have VM_HUGEPAGE if the page was not | |
1385 | * collapsed by this mm. But we can still collapse if the page is | |
1386 | * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check() | |
1387 | * will not fail the vma for missing VM_HUGEPAGE | |
1388 | */ | |
1389 | if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE)) | |
1390 | return; | |
1391 | ||
1392 | pmd = mm_find_pmd(mm, haddr); | |
1393 | if (!pmd) | |
1394 | return; | |
1395 | ||
1396 | start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl); | |
1397 | ||
1398 | /* step 1: check all mapped PTEs are to the right huge page */ | |
1399 | for (i = 0, addr = haddr, pte = start_pte; | |
1400 | i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) { | |
1401 | struct page *page; | |
1402 | ||
1403 | /* empty pte, skip */ | |
1404 | if (pte_none(*pte)) | |
1405 | continue; | |
1406 | ||
1407 | /* page swapped out, abort */ | |
1408 | if (!pte_present(*pte)) | |
1409 | goto abort; | |
1410 | ||
1411 | page = vm_normal_page(vma, addr, *pte); | |
1412 | ||
1413 | if (!page || !PageCompound(page)) | |
1414 | goto abort; | |
1415 | ||
1416 | if (!hpage) { | |
1417 | hpage = compound_head(page); | |
1418 | /* | |
1419 | * The mapping of the THP should not change. | |
1420 | * | |
1421 | * Note that uprobe, debugger, or MAP_PRIVATE may | |
1422 | * change the page table, but the new page will | |
1423 | * not pass PageCompound() check. | |
1424 | */ | |
1425 | if (WARN_ON(hpage->mapping != vma->vm_file->f_mapping)) | |
1426 | goto abort; | |
1427 | } | |
1428 | ||
1429 | /* | |
1430 | * Confirm the page maps to the correct subpage. | |
1431 | * | |
1432 | * Note that uprobe, debugger, or MAP_PRIVATE may change | |
1433 | * the page table, but the new page will not pass | |
1434 | * PageCompound() check. | |
1435 | */ | |
1436 | if (WARN_ON(hpage + i != page)) | |
1437 | goto abort; | |
1438 | count++; | |
1439 | } | |
1440 | ||
1441 | /* step 2: adjust rmap */ | |
1442 | for (i = 0, addr = haddr, pte = start_pte; | |
1443 | i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) { | |
1444 | struct page *page; | |
1445 | ||
1446 | if (pte_none(*pte)) | |
1447 | continue; | |
1448 | page = vm_normal_page(vma, addr, *pte); | |
1449 | page_remove_rmap(page, false); | |
1450 | } | |
1451 | ||
1452 | pte_unmap_unlock(start_pte, ptl); | |
1453 | ||
1454 | /* step 3: set proper refcount and mm_counters. */ | |
1455 | if (hpage) { | |
1456 | page_ref_sub(hpage, count); | |
1457 | add_mm_counter(vma->vm_mm, mm_counter_file(hpage), -count); | |
1458 | } | |
1459 | ||
1460 | /* step 4: collapse pmd */ | |
1461 | ptl = pmd_lock(vma->vm_mm, pmd); | |
1462 | _pmd = pmdp_collapse_flush(vma, addr, pmd); | |
1463 | spin_unlock(ptl); | |
1464 | mm_dec_nr_ptes(mm); | |
1465 | pte_free(mm, pmd_pgtable(_pmd)); | |
1466 | return; | |
1467 | ||
1468 | abort: | |
1469 | pte_unmap_unlock(start_pte, ptl); | |
1470 | } | |
1471 | ||
1472 | static int khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) | |
1473 | { | |
1474 | struct mm_struct *mm = mm_slot->mm; | |
1475 | int i; | |
1476 | ||
1477 | if (likely(mm_slot->nr_pte_mapped_thp == 0)) | |
1478 | return 0; | |
1479 | ||
1480 | if (!down_write_trylock(&mm->mmap_sem)) | |
1481 | return -EBUSY; | |
1482 | ||
1483 | if (unlikely(khugepaged_test_exit(mm))) | |
1484 | goto out; | |
1485 | ||
1486 | for (i = 0; i < mm_slot->nr_pte_mapped_thp; i++) | |
1487 | collapse_pte_mapped_thp(mm, mm_slot->pte_mapped_thp[i]); | |
1488 | ||
1489 | out: | |
1490 | mm_slot->nr_pte_mapped_thp = 0; | |
1491 | up_write(&mm->mmap_sem); | |
1492 | return 0; | |
1493 | } | |
1494 | ||
f3f0e1d2 KS |
1495 | static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) |
1496 | { | |
1497 | struct vm_area_struct *vma; | |
1498 | unsigned long addr; | |
1499 | pmd_t *pmd, _pmd; | |
1500 | ||
1501 | i_mmap_lock_write(mapping); | |
1502 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { | |
27e1f827 SL |
1503 | /* |
1504 | * Check vma->anon_vma to exclude MAP_PRIVATE mappings that | |
1505 | * got written to. These VMAs are likely not worth investing | |
1506 | * down_write(mmap_sem) as PMD-mapping is likely to be split | |
1507 | * later. | |
1508 | * | |
1509 | * Not that vma->anon_vma check is racy: it can be set up after | |
1510 | * the check but before we took mmap_sem by the fault path. | |
1511 | * But page lock would prevent establishing any new ptes of the | |
1512 | * page, so we are safe. | |
1513 | * | |
1514 | * An alternative would be drop the check, but check that page | |
1515 | * table is clear before calling pmdp_collapse_flush() under | |
1516 | * ptl. It has higher chance to recover THP for the VMA, but | |
1517 | * has higher cost too. | |
1518 | */ | |
f3f0e1d2 KS |
1519 | if (vma->anon_vma) |
1520 | continue; | |
1521 | addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
1522 | if (addr & ~HPAGE_PMD_MASK) | |
1523 | continue; | |
1524 | if (vma->vm_end < addr + HPAGE_PMD_SIZE) | |
1525 | continue; | |
1526 | pmd = mm_find_pmd(vma->vm_mm, addr); | |
1527 | if (!pmd) | |
1528 | continue; | |
1529 | /* | |
1530 | * We need exclusive mmap_sem to retract page table. | |
27e1f827 SL |
1531 | * |
1532 | * We use trylock due to lock inversion: we need to acquire | |
1533 | * mmap_sem while holding page lock. Fault path does it in | |
1534 | * reverse order. Trylock is a way to avoid deadlock. | |
f3f0e1d2 KS |
1535 | */ |
1536 | if (down_write_trylock(&vma->vm_mm->mmap_sem)) { | |
1537 | spinlock_t *ptl = pmd_lock(vma->vm_mm, pmd); | |
1538 | /* assume page table is clear */ | |
1539 | _pmd = pmdp_collapse_flush(vma, addr, pmd); | |
1540 | spin_unlock(ptl); | |
1541 | up_write(&vma->vm_mm->mmap_sem); | |
c4812909 | 1542 | mm_dec_nr_ptes(vma->vm_mm); |
d670ffd8 | 1543 | pte_free(vma->vm_mm, pmd_pgtable(_pmd)); |
27e1f827 SL |
1544 | } else { |
1545 | /* Try again later */ | |
1546 | khugepaged_add_pte_mapped_thp(vma->vm_mm, addr); | |
f3f0e1d2 KS |
1547 | } |
1548 | } | |
1549 | i_mmap_unlock_write(mapping); | |
1550 | } | |
1551 | ||
1552 | /** | |
99cb0dbd | 1553 | * collapse_file - collapse filemap/tmpfs/shmem pages into huge one. |
f3f0e1d2 KS |
1554 | * |
1555 | * Basic scheme is simple, details are more complex: | |
87c460a0 | 1556 | * - allocate and lock a new huge page; |
77da9389 | 1557 | * - scan page cache replacing old pages with the new one |
99cb0dbd | 1558 | * + swap/gup in pages if necessary; |
f3f0e1d2 | 1559 | * + fill in gaps; |
77da9389 MW |
1560 | * + keep old pages around in case rollback is required; |
1561 | * - if replacing succeeds: | |
f3f0e1d2 KS |
1562 | * + copy data over; |
1563 | * + free old pages; | |
87c460a0 | 1564 | * + unlock huge page; |
f3f0e1d2 KS |
1565 | * - if replacing failed; |
1566 | * + put all pages back and unfreeze them; | |
77da9389 | 1567 | * + restore gaps in the page cache; |
87c460a0 | 1568 | * + unlock and free huge page; |
f3f0e1d2 | 1569 | */ |
579c571e SL |
1570 | static void collapse_file(struct mm_struct *mm, |
1571 | struct file *file, pgoff_t start, | |
f3f0e1d2 KS |
1572 | struct page **hpage, int node) |
1573 | { | |
579c571e | 1574 | struct address_space *mapping = file->f_mapping; |
f3f0e1d2 | 1575 | gfp_t gfp; |
77da9389 | 1576 | struct page *new_page; |
f3f0e1d2 KS |
1577 | struct mem_cgroup *memcg; |
1578 | pgoff_t index, end = start + HPAGE_PMD_NR; | |
1579 | LIST_HEAD(pagelist); | |
77da9389 | 1580 | XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); |
f3f0e1d2 | 1581 | int nr_none = 0, result = SCAN_SUCCEED; |
99cb0dbd | 1582 | bool is_shmem = shmem_file(file); |
f3f0e1d2 | 1583 | |
99cb0dbd | 1584 | VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); |
f3f0e1d2 KS |
1585 | VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); |
1586 | ||
1587 | /* Only allocate from the target node */ | |
41b6167e | 1588 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
f3f0e1d2 KS |
1589 | |
1590 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
1591 | if (!new_page) { | |
1592 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
1593 | goto out; | |
1594 | } | |
1595 | ||
2a70f6a7 | 1596 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { |
f3f0e1d2 KS |
1597 | result = SCAN_CGROUP_CHARGE_FAIL; |
1598 | goto out; | |
1599 | } | |
1600 | ||
95feeabb HD |
1601 | /* This will be less messy when we use multi-index entries */ |
1602 | do { | |
1603 | xas_lock_irq(&xas); | |
1604 | xas_create_range(&xas); | |
1605 | if (!xas_error(&xas)) | |
1606 | break; | |
1607 | xas_unlock_irq(&xas); | |
1608 | if (!xas_nomem(&xas, GFP_KERNEL)) { | |
1609 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1610 | result = SCAN_FAIL; | |
1611 | goto out; | |
1612 | } | |
1613 | } while (1); | |
1614 | ||
042a3082 | 1615 | __SetPageLocked(new_page); |
99cb0dbd SL |
1616 | if (is_shmem) |
1617 | __SetPageSwapBacked(new_page); | |
f3f0e1d2 KS |
1618 | new_page->index = start; |
1619 | new_page->mapping = mapping; | |
f3f0e1d2 | 1620 | |
f3f0e1d2 | 1621 | /* |
87c460a0 HD |
1622 | * At this point the new_page is locked and not up-to-date. |
1623 | * It's safe to insert it into the page cache, because nobody would | |
1624 | * be able to map it or use it in another way until we unlock it. | |
f3f0e1d2 KS |
1625 | */ |
1626 | ||
77da9389 MW |
1627 | xas_set(&xas, start); |
1628 | for (index = start; index < end; index++) { | |
1629 | struct page *page = xas_next(&xas); | |
1630 | ||
1631 | VM_BUG_ON(index != xas.xa_index); | |
99cb0dbd SL |
1632 | if (is_shmem) { |
1633 | if (!page) { | |
1634 | /* | |
1635 | * Stop if extent has been truncated or | |
1636 | * hole-punched, and is now completely | |
1637 | * empty. | |
1638 | */ | |
1639 | if (index == start) { | |
1640 | if (!xas_next_entry(&xas, end - 1)) { | |
1641 | result = SCAN_TRUNCATED; | |
1642 | goto xa_locked; | |
1643 | } | |
1644 | xas_set(&xas, index); | |
1645 | } | |
1646 | if (!shmem_charge(mapping->host, 1)) { | |
1647 | result = SCAN_FAIL; | |
042a3082 | 1648 | goto xa_locked; |
701270fa | 1649 | } |
99cb0dbd SL |
1650 | xas_store(&xas, new_page); |
1651 | nr_none++; | |
1652 | continue; | |
701270fa | 1653 | } |
99cb0dbd SL |
1654 | |
1655 | if (xa_is_value(page) || !PageUptodate(page)) { | |
1656 | xas_unlock_irq(&xas); | |
1657 | /* swap in or instantiate fallocated page */ | |
1658 | if (shmem_getpage(mapping->host, index, &page, | |
1659 | SGP_NOHUGE)) { | |
1660 | result = SCAN_FAIL; | |
1661 | goto xa_unlocked; | |
1662 | } | |
1663 | } else if (trylock_page(page)) { | |
1664 | get_page(page); | |
1665 | xas_unlock_irq(&xas); | |
1666 | } else { | |
1667 | result = SCAN_PAGE_LOCK; | |
042a3082 | 1668 | goto xa_locked; |
77da9389 | 1669 | } |
99cb0dbd SL |
1670 | } else { /* !is_shmem */ |
1671 | if (!page || xa_is_value(page)) { | |
1672 | xas_unlock_irq(&xas); | |
1673 | page_cache_sync_readahead(mapping, &file->f_ra, | |
1674 | file, index, | |
1675 | PAGE_SIZE); | |
1676 | /* drain pagevecs to help isolate_lru_page() */ | |
1677 | lru_add_drain(); | |
1678 | page = find_lock_page(mapping, index); | |
1679 | if (unlikely(page == NULL)) { | |
1680 | result = SCAN_FAIL; | |
1681 | goto xa_unlocked; | |
1682 | } | |
75f36069 SL |
1683 | } else if (PageDirty(page)) { |
1684 | /* | |
1685 | * khugepaged only works on read-only fd, | |
1686 | * so this page is dirty because it hasn't | |
1687 | * been flushed since first write. There | |
1688 | * won't be new dirty pages. | |
1689 | * | |
1690 | * Trigger async flush here and hope the | |
1691 | * writeback is done when khugepaged | |
1692 | * revisits this page. | |
1693 | * | |
1694 | * This is a one-off situation. We are not | |
1695 | * forcing writeback in loop. | |
1696 | */ | |
1697 | xas_unlock_irq(&xas); | |
1698 | filemap_flush(mapping); | |
1699 | result = SCAN_FAIL; | |
1700 | goto xa_unlocked; | |
99cb0dbd SL |
1701 | } else if (trylock_page(page)) { |
1702 | get_page(page); | |
1703 | xas_unlock_irq(&xas); | |
1704 | } else { | |
1705 | result = SCAN_PAGE_LOCK; | |
1706 | goto xa_locked; | |
f3f0e1d2 | 1707 | } |
f3f0e1d2 KS |
1708 | } |
1709 | ||
1710 | /* | |
b93b0163 | 1711 | * The page must be locked, so we can drop the i_pages lock |
f3f0e1d2 KS |
1712 | * without racing with truncate. |
1713 | */ | |
1714 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
4655e5e5 SL |
1715 | |
1716 | /* make sure the page is up to date */ | |
1717 | if (unlikely(!PageUptodate(page))) { | |
1718 | result = SCAN_FAIL; | |
1719 | goto out_unlock; | |
1720 | } | |
06a5e126 HD |
1721 | |
1722 | /* | |
1723 | * If file was truncated then extended, or hole-punched, before | |
1724 | * we locked the first page, then a THP might be there already. | |
1725 | */ | |
1726 | if (PageTransCompound(page)) { | |
1727 | result = SCAN_PAGE_COMPOUND; | |
1728 | goto out_unlock; | |
1729 | } | |
f3f0e1d2 KS |
1730 | |
1731 | if (page_mapping(page) != mapping) { | |
1732 | result = SCAN_TRUNCATED; | |
1733 | goto out_unlock; | |
1734 | } | |
f3f0e1d2 | 1735 | |
4655e5e5 SL |
1736 | if (!is_shmem && PageDirty(page)) { |
1737 | /* | |
1738 | * khugepaged only works on read-only fd, so this | |
1739 | * page is dirty because it hasn't been flushed | |
1740 | * since first write. | |
1741 | */ | |
1742 | result = SCAN_FAIL; | |
1743 | goto out_unlock; | |
1744 | } | |
1745 | ||
f3f0e1d2 KS |
1746 | if (isolate_lru_page(page)) { |
1747 | result = SCAN_DEL_PAGE_LRU; | |
042a3082 | 1748 | goto out_unlock; |
f3f0e1d2 KS |
1749 | } |
1750 | ||
99cb0dbd SL |
1751 | if (page_has_private(page) && |
1752 | !try_to_release_page(page, GFP_KERNEL)) { | |
1753 | result = SCAN_PAGE_HAS_PRIVATE; | |
2f33a706 | 1754 | putback_lru_page(page); |
99cb0dbd SL |
1755 | goto out_unlock; |
1756 | } | |
1757 | ||
f3f0e1d2 | 1758 | if (page_mapped(page)) |
977fbdcd | 1759 | unmap_mapping_pages(mapping, index, 1, false); |
f3f0e1d2 | 1760 | |
77da9389 MW |
1761 | xas_lock_irq(&xas); |
1762 | xas_set(&xas, index); | |
f3f0e1d2 | 1763 | |
77da9389 | 1764 | VM_BUG_ON_PAGE(page != xas_load(&xas), page); |
f3f0e1d2 KS |
1765 | VM_BUG_ON_PAGE(page_mapped(page), page); |
1766 | ||
1767 | /* | |
1768 | * The page is expected to have page_count() == 3: | |
1769 | * - we hold a pin on it; | |
77da9389 | 1770 | * - one reference from page cache; |
f3f0e1d2 KS |
1771 | * - one from isolate_lru_page; |
1772 | */ | |
1773 | if (!page_ref_freeze(page, 3)) { | |
1774 | result = SCAN_PAGE_COUNT; | |
042a3082 HD |
1775 | xas_unlock_irq(&xas); |
1776 | putback_lru_page(page); | |
1777 | goto out_unlock; | |
f3f0e1d2 KS |
1778 | } |
1779 | ||
1780 | /* | |
1781 | * Add the page to the list to be able to undo the collapse if | |
1782 | * something go wrong. | |
1783 | */ | |
1784 | list_add_tail(&page->lru, &pagelist); | |
1785 | ||
1786 | /* Finally, replace with the new page. */ | |
4101196b | 1787 | xas_store(&xas, new_page); |
f3f0e1d2 | 1788 | continue; |
f3f0e1d2 KS |
1789 | out_unlock: |
1790 | unlock_page(page); | |
1791 | put_page(page); | |
042a3082 | 1792 | goto xa_unlocked; |
f3f0e1d2 KS |
1793 | } |
1794 | ||
99cb0dbd SL |
1795 | if (is_shmem) |
1796 | __inc_node_page_state(new_page, NR_SHMEM_THPS); | |
09d91cda | 1797 | else { |
99cb0dbd | 1798 | __inc_node_page_state(new_page, NR_FILE_THPS); |
09d91cda SL |
1799 | filemap_nr_thps_inc(mapping); |
1800 | } | |
99cb0dbd | 1801 | |
042a3082 HD |
1802 | if (nr_none) { |
1803 | struct zone *zone = page_zone(new_page); | |
1804 | ||
1805 | __mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none); | |
99cb0dbd SL |
1806 | if (is_shmem) |
1807 | __mod_node_page_state(zone->zone_pgdat, | |
1808 | NR_SHMEM, nr_none); | |
042a3082 HD |
1809 | } |
1810 | ||
1811 | xa_locked: | |
1812 | xas_unlock_irq(&xas); | |
77da9389 | 1813 | xa_unlocked: |
042a3082 | 1814 | |
f3f0e1d2 | 1815 | if (result == SCAN_SUCCEED) { |
77da9389 | 1816 | struct page *page, *tmp; |
f3f0e1d2 KS |
1817 | |
1818 | /* | |
77da9389 MW |
1819 | * Replacing old pages with new one has succeeded, now we |
1820 | * need to copy the content and free the old pages. | |
f3f0e1d2 | 1821 | */ |
2af8ff29 | 1822 | index = start; |
f3f0e1d2 | 1823 | list_for_each_entry_safe(page, tmp, &pagelist, lru) { |
2af8ff29 HD |
1824 | while (index < page->index) { |
1825 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1826 | index++; | |
1827 | } | |
f3f0e1d2 KS |
1828 | copy_highpage(new_page + (page->index % HPAGE_PMD_NR), |
1829 | page); | |
1830 | list_del(&page->lru); | |
f3f0e1d2 | 1831 | page->mapping = NULL; |
042a3082 | 1832 | page_ref_unfreeze(page, 1); |
f3f0e1d2 KS |
1833 | ClearPageActive(page); |
1834 | ClearPageUnevictable(page); | |
042a3082 | 1835 | unlock_page(page); |
f3f0e1d2 | 1836 | put_page(page); |
2af8ff29 HD |
1837 | index++; |
1838 | } | |
1839 | while (index < end) { | |
1840 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1841 | index++; | |
f3f0e1d2 KS |
1842 | } |
1843 | ||
f3f0e1d2 | 1844 | SetPageUptodate(new_page); |
87c460a0 | 1845 | page_ref_add(new_page, HPAGE_PMD_NR - 1); |
f3f0e1d2 | 1846 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
99cb0dbd SL |
1847 | |
1848 | if (is_shmem) { | |
1849 | set_page_dirty(new_page); | |
1850 | lru_cache_add_anon(new_page); | |
1851 | } else { | |
1852 | lru_cache_add_file(new_page); | |
1853 | } | |
1ff9e6e1 | 1854 | count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1); |
f3f0e1d2 | 1855 | |
042a3082 HD |
1856 | /* |
1857 | * Remove pte page tables, so we can re-fault the page as huge. | |
1858 | */ | |
1859 | retract_page_tables(mapping, start); | |
f3f0e1d2 | 1860 | *hpage = NULL; |
87aa7529 YS |
1861 | |
1862 | khugepaged_pages_collapsed++; | |
f3f0e1d2 | 1863 | } else { |
77da9389 | 1864 | struct page *page; |
aaa52e34 | 1865 | |
77da9389 | 1866 | /* Something went wrong: roll back page cache changes */ |
77da9389 | 1867 | xas_lock_irq(&xas); |
aaa52e34 | 1868 | mapping->nrpages -= nr_none; |
99cb0dbd SL |
1869 | |
1870 | if (is_shmem) | |
1871 | shmem_uncharge(mapping->host, nr_none); | |
aaa52e34 | 1872 | |
77da9389 MW |
1873 | xas_set(&xas, start); |
1874 | xas_for_each(&xas, page, end - 1) { | |
f3f0e1d2 KS |
1875 | page = list_first_entry_or_null(&pagelist, |
1876 | struct page, lru); | |
77da9389 | 1877 | if (!page || xas.xa_index < page->index) { |
f3f0e1d2 KS |
1878 | if (!nr_none) |
1879 | break; | |
f3f0e1d2 | 1880 | nr_none--; |
59749e6c | 1881 | /* Put holes back where they were */ |
77da9389 | 1882 | xas_store(&xas, NULL); |
f3f0e1d2 KS |
1883 | continue; |
1884 | } | |
1885 | ||
77da9389 | 1886 | VM_BUG_ON_PAGE(page->index != xas.xa_index, page); |
f3f0e1d2 KS |
1887 | |
1888 | /* Unfreeze the page. */ | |
1889 | list_del(&page->lru); | |
1890 | page_ref_unfreeze(page, 2); | |
77da9389 MW |
1891 | xas_store(&xas, page); |
1892 | xas_pause(&xas); | |
1893 | xas_unlock_irq(&xas); | |
f3f0e1d2 | 1894 | unlock_page(page); |
042a3082 | 1895 | putback_lru_page(page); |
77da9389 | 1896 | xas_lock_irq(&xas); |
f3f0e1d2 KS |
1897 | } |
1898 | VM_BUG_ON(nr_none); | |
77da9389 | 1899 | xas_unlock_irq(&xas); |
f3f0e1d2 | 1900 | |
f3f0e1d2 | 1901 | mem_cgroup_cancel_charge(new_page, memcg, true); |
f3f0e1d2 KS |
1902 | new_page->mapping = NULL; |
1903 | } | |
042a3082 HD |
1904 | |
1905 | unlock_page(new_page); | |
f3f0e1d2 KS |
1906 | out: |
1907 | VM_BUG_ON(!list_empty(&pagelist)); | |
1908 | /* TODO: tracepoints */ | |
1909 | } | |
1910 | ||
579c571e SL |
1911 | static void khugepaged_scan_file(struct mm_struct *mm, |
1912 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
1913 | { |
1914 | struct page *page = NULL; | |
579c571e | 1915 | struct address_space *mapping = file->f_mapping; |
85b392db | 1916 | XA_STATE(xas, &mapping->i_pages, start); |
f3f0e1d2 KS |
1917 | int present, swap; |
1918 | int node = NUMA_NO_NODE; | |
1919 | int result = SCAN_SUCCEED; | |
1920 | ||
1921 | present = 0; | |
1922 | swap = 0; | |
1923 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1924 | rcu_read_lock(); | |
85b392db MW |
1925 | xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) { |
1926 | if (xas_retry(&xas, page)) | |
f3f0e1d2 | 1927 | continue; |
f3f0e1d2 | 1928 | |
85b392db | 1929 | if (xa_is_value(page)) { |
f3f0e1d2 KS |
1930 | if (++swap > khugepaged_max_ptes_swap) { |
1931 | result = SCAN_EXCEED_SWAP_PTE; | |
1932 | break; | |
1933 | } | |
1934 | continue; | |
1935 | } | |
1936 | ||
1937 | if (PageTransCompound(page)) { | |
1938 | result = SCAN_PAGE_COMPOUND; | |
1939 | break; | |
1940 | } | |
1941 | ||
1942 | node = page_to_nid(page); | |
1943 | if (khugepaged_scan_abort(node)) { | |
1944 | result = SCAN_SCAN_ABORT; | |
1945 | break; | |
1946 | } | |
1947 | khugepaged_node_load[node]++; | |
1948 | ||
1949 | if (!PageLRU(page)) { | |
1950 | result = SCAN_PAGE_LRU; | |
1951 | break; | |
1952 | } | |
1953 | ||
99cb0dbd SL |
1954 | if (page_count(page) != |
1955 | 1 + page_mapcount(page) + page_has_private(page)) { | |
f3f0e1d2 KS |
1956 | result = SCAN_PAGE_COUNT; |
1957 | break; | |
1958 | } | |
1959 | ||
1960 | /* | |
1961 | * We probably should check if the page is referenced here, but | |
1962 | * nobody would transfer pte_young() to PageReferenced() for us. | |
1963 | * And rmap walk here is just too costly... | |
1964 | */ | |
1965 | ||
1966 | present++; | |
1967 | ||
1968 | if (need_resched()) { | |
85b392db | 1969 | xas_pause(&xas); |
f3f0e1d2 | 1970 | cond_resched_rcu(); |
f3f0e1d2 KS |
1971 | } |
1972 | } | |
1973 | rcu_read_unlock(); | |
1974 | ||
1975 | if (result == SCAN_SUCCEED) { | |
1976 | if (present < HPAGE_PMD_NR - khugepaged_max_ptes_none) { | |
1977 | result = SCAN_EXCEED_NONE_PTE; | |
1978 | } else { | |
1979 | node = khugepaged_find_target_node(); | |
579c571e | 1980 | collapse_file(mm, file, start, hpage, node); |
f3f0e1d2 KS |
1981 | } |
1982 | } | |
1983 | ||
1984 | /* TODO: tracepoints */ | |
1985 | } | |
1986 | #else | |
579c571e SL |
1987 | static void khugepaged_scan_file(struct mm_struct *mm, |
1988 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
1989 | { |
1990 | BUILD_BUG(); | |
1991 | } | |
27e1f827 SL |
1992 | |
1993 | static int khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) | |
1994 | { | |
1995 | return 0; | |
1996 | } | |
f3f0e1d2 KS |
1997 | #endif |
1998 | ||
b46e756f KS |
1999 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, |
2000 | struct page **hpage) | |
2001 | __releases(&khugepaged_mm_lock) | |
2002 | __acquires(&khugepaged_mm_lock) | |
2003 | { | |
2004 | struct mm_slot *mm_slot; | |
2005 | struct mm_struct *mm; | |
2006 | struct vm_area_struct *vma; | |
2007 | int progress = 0; | |
2008 | ||
2009 | VM_BUG_ON(!pages); | |
35f3aa39 | 2010 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
2011 | |
2012 | if (khugepaged_scan.mm_slot) | |
2013 | mm_slot = khugepaged_scan.mm_slot; | |
2014 | else { | |
2015 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2016 | struct mm_slot, mm_node); | |
2017 | khugepaged_scan.address = 0; | |
2018 | khugepaged_scan.mm_slot = mm_slot; | |
2019 | } | |
2020 | spin_unlock(&khugepaged_mm_lock); | |
27e1f827 | 2021 | khugepaged_collapse_pte_mapped_thps(mm_slot); |
b46e756f KS |
2022 | |
2023 | mm = mm_slot->mm; | |
3b454ad3 YS |
2024 | /* |
2025 | * Don't wait for semaphore (to avoid long wait times). Just move to | |
2026 | * the next mm on the list. | |
2027 | */ | |
2028 | vma = NULL; | |
2029 | if (unlikely(!down_read_trylock(&mm->mmap_sem))) | |
2030 | goto breakouterloop_mmap_sem; | |
2031 | if (likely(!khugepaged_test_exit(mm))) | |
b46e756f KS |
2032 | vma = find_vma(mm, khugepaged_scan.address); |
2033 | ||
2034 | progress++; | |
2035 | for (; vma; vma = vma->vm_next) { | |
2036 | unsigned long hstart, hend; | |
2037 | ||
2038 | cond_resched(); | |
2039 | if (unlikely(khugepaged_test_exit(mm))) { | |
2040 | progress++; | |
2041 | break; | |
2042 | } | |
50f8b92f | 2043 | if (!hugepage_vma_check(vma, vma->vm_flags)) { |
b46e756f KS |
2044 | skip: |
2045 | progress++; | |
2046 | continue; | |
2047 | } | |
2048 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2049 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2050 | if (hstart >= hend) | |
2051 | goto skip; | |
2052 | if (khugepaged_scan.address > hend) | |
2053 | goto skip; | |
2054 | if (khugepaged_scan.address < hstart) | |
2055 | khugepaged_scan.address = hstart; | |
2056 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); | |
396bcc52 MWO |
2057 | if (shmem_file(vma->vm_file) && !shmem_huge_enabled(vma)) |
2058 | goto skip; | |
b46e756f KS |
2059 | |
2060 | while (khugepaged_scan.address < hend) { | |
2061 | int ret; | |
2062 | cond_resched(); | |
2063 | if (unlikely(khugepaged_test_exit(mm))) | |
2064 | goto breakouterloop; | |
2065 | ||
2066 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2067 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2068 | hend); | |
99cb0dbd | 2069 | if (IS_ENABLED(CONFIG_SHMEM) && vma->vm_file) { |
396bcc52 | 2070 | struct file *file = get_file(vma->vm_file); |
f3f0e1d2 KS |
2071 | pgoff_t pgoff = linear_page_index(vma, |
2072 | khugepaged_scan.address); | |
99cb0dbd | 2073 | |
f3f0e1d2 KS |
2074 | up_read(&mm->mmap_sem); |
2075 | ret = 1; | |
579c571e | 2076 | khugepaged_scan_file(mm, file, pgoff, hpage); |
f3f0e1d2 KS |
2077 | fput(file); |
2078 | } else { | |
2079 | ret = khugepaged_scan_pmd(mm, vma, | |
2080 | khugepaged_scan.address, | |
2081 | hpage); | |
2082 | } | |
b46e756f KS |
2083 | /* move to next address */ |
2084 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2085 | progress += HPAGE_PMD_NR; | |
2086 | if (ret) | |
2087 | /* we released mmap_sem so break loop */ | |
2088 | goto breakouterloop_mmap_sem; | |
2089 | if (progress >= pages) | |
2090 | goto breakouterloop; | |
2091 | } | |
2092 | } | |
2093 | breakouterloop: | |
2094 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2095 | breakouterloop_mmap_sem: | |
2096 | ||
2097 | spin_lock(&khugepaged_mm_lock); | |
2098 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); | |
2099 | /* | |
2100 | * Release the current mm_slot if this mm is about to die, or | |
2101 | * if we scanned all vmas of this mm. | |
2102 | */ | |
2103 | if (khugepaged_test_exit(mm) || !vma) { | |
2104 | /* | |
2105 | * Make sure that if mm_users is reaching zero while | |
2106 | * khugepaged runs here, khugepaged_exit will find | |
2107 | * mm_slot not pointing to the exiting mm. | |
2108 | */ | |
2109 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2110 | khugepaged_scan.mm_slot = list_entry( | |
2111 | mm_slot->mm_node.next, | |
2112 | struct mm_slot, mm_node); | |
2113 | khugepaged_scan.address = 0; | |
2114 | } else { | |
2115 | khugepaged_scan.mm_slot = NULL; | |
2116 | khugepaged_full_scans++; | |
2117 | } | |
2118 | ||
2119 | collect_mm_slot(mm_slot); | |
2120 | } | |
2121 | ||
2122 | return progress; | |
2123 | } | |
2124 | ||
2125 | static int khugepaged_has_work(void) | |
2126 | { | |
2127 | return !list_empty(&khugepaged_scan.mm_head) && | |
2128 | khugepaged_enabled(); | |
2129 | } | |
2130 | ||
2131 | static int khugepaged_wait_event(void) | |
2132 | { | |
2133 | return !list_empty(&khugepaged_scan.mm_head) || | |
2134 | kthread_should_stop(); | |
2135 | } | |
2136 | ||
2137 | static void khugepaged_do_scan(void) | |
2138 | { | |
2139 | struct page *hpage = NULL; | |
2140 | unsigned int progress = 0, pass_through_head = 0; | |
2141 | unsigned int pages = khugepaged_pages_to_scan; | |
2142 | bool wait = true; | |
2143 | ||
2144 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2145 | ||
a980df33 KS |
2146 | lru_add_drain_all(); |
2147 | ||
b46e756f KS |
2148 | while (progress < pages) { |
2149 | if (!khugepaged_prealloc_page(&hpage, &wait)) | |
2150 | break; | |
2151 | ||
2152 | cond_resched(); | |
2153 | ||
2154 | if (unlikely(kthread_should_stop() || try_to_freeze())) | |
2155 | break; | |
2156 | ||
2157 | spin_lock(&khugepaged_mm_lock); | |
2158 | if (!khugepaged_scan.mm_slot) | |
2159 | pass_through_head++; | |
2160 | if (khugepaged_has_work() && | |
2161 | pass_through_head < 2) | |
2162 | progress += khugepaged_scan_mm_slot(pages - progress, | |
2163 | &hpage); | |
2164 | else | |
2165 | progress = pages; | |
2166 | spin_unlock(&khugepaged_mm_lock); | |
2167 | } | |
2168 | ||
2169 | if (!IS_ERR_OR_NULL(hpage)) | |
2170 | put_page(hpage); | |
2171 | } | |
2172 | ||
2173 | static bool khugepaged_should_wakeup(void) | |
2174 | { | |
2175 | return kthread_should_stop() || | |
2176 | time_after_eq(jiffies, khugepaged_sleep_expire); | |
2177 | } | |
2178 | ||
2179 | static void khugepaged_wait_work(void) | |
2180 | { | |
2181 | if (khugepaged_has_work()) { | |
2182 | const unsigned long scan_sleep_jiffies = | |
2183 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs); | |
2184 | ||
2185 | if (!scan_sleep_jiffies) | |
2186 | return; | |
2187 | ||
2188 | khugepaged_sleep_expire = jiffies + scan_sleep_jiffies; | |
2189 | wait_event_freezable_timeout(khugepaged_wait, | |
2190 | khugepaged_should_wakeup(), | |
2191 | scan_sleep_jiffies); | |
2192 | return; | |
2193 | } | |
2194 | ||
2195 | if (khugepaged_enabled()) | |
2196 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2197 | } | |
2198 | ||
2199 | static int khugepaged(void *none) | |
2200 | { | |
2201 | struct mm_slot *mm_slot; | |
2202 | ||
2203 | set_freezable(); | |
2204 | set_user_nice(current, MAX_NICE); | |
2205 | ||
2206 | while (!kthread_should_stop()) { | |
2207 | khugepaged_do_scan(); | |
2208 | khugepaged_wait_work(); | |
2209 | } | |
2210 | ||
2211 | spin_lock(&khugepaged_mm_lock); | |
2212 | mm_slot = khugepaged_scan.mm_slot; | |
2213 | khugepaged_scan.mm_slot = NULL; | |
2214 | if (mm_slot) | |
2215 | collect_mm_slot(mm_slot); | |
2216 | spin_unlock(&khugepaged_mm_lock); | |
2217 | return 0; | |
2218 | } | |
2219 | ||
2220 | static void set_recommended_min_free_kbytes(void) | |
2221 | { | |
2222 | struct zone *zone; | |
2223 | int nr_zones = 0; | |
2224 | unsigned long recommended_min; | |
2225 | ||
b7d349c7 JK |
2226 | for_each_populated_zone(zone) { |
2227 | /* | |
2228 | * We don't need to worry about fragmentation of | |
2229 | * ZONE_MOVABLE since it only has movable pages. | |
2230 | */ | |
2231 | if (zone_idx(zone) > gfp_zone(GFP_USER)) | |
2232 | continue; | |
2233 | ||
b46e756f | 2234 | nr_zones++; |
b7d349c7 | 2235 | } |
b46e756f KS |
2236 | |
2237 | /* Ensure 2 pageblocks are free to assist fragmentation avoidance */ | |
2238 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
2239 | ||
2240 | /* | |
2241 | * Make sure that on average at least two pageblocks are almost free | |
2242 | * of another type, one for a migratetype to fall back to and a | |
2243 | * second to avoid subsequent fallbacks of other types There are 3 | |
2244 | * MIGRATE_TYPES we care about. | |
2245 | */ | |
2246 | recommended_min += pageblock_nr_pages * nr_zones * | |
2247 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
2248 | ||
2249 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
2250 | recommended_min = min(recommended_min, | |
2251 | (unsigned long) nr_free_buffer_pages() / 20); | |
2252 | recommended_min <<= (PAGE_SHIFT-10); | |
2253 | ||
2254 | if (recommended_min > min_free_kbytes) { | |
2255 | if (user_min_free_kbytes >= 0) | |
2256 | pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n", | |
2257 | min_free_kbytes, recommended_min); | |
2258 | ||
2259 | min_free_kbytes = recommended_min; | |
2260 | } | |
2261 | setup_per_zone_wmarks(); | |
2262 | } | |
2263 | ||
2264 | int start_stop_khugepaged(void) | |
2265 | { | |
2266 | static struct task_struct *khugepaged_thread __read_mostly; | |
2267 | static DEFINE_MUTEX(khugepaged_mutex); | |
2268 | int err = 0; | |
2269 | ||
2270 | mutex_lock(&khugepaged_mutex); | |
2271 | if (khugepaged_enabled()) { | |
2272 | if (!khugepaged_thread) | |
2273 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
2274 | "khugepaged"); | |
2275 | if (IS_ERR(khugepaged_thread)) { | |
2276 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); | |
2277 | err = PTR_ERR(khugepaged_thread); | |
2278 | khugepaged_thread = NULL; | |
2279 | goto fail; | |
2280 | } | |
2281 | ||
2282 | if (!list_empty(&khugepaged_scan.mm_head)) | |
2283 | wake_up_interruptible(&khugepaged_wait); | |
2284 | ||
2285 | set_recommended_min_free_kbytes(); | |
2286 | } else if (khugepaged_thread) { | |
2287 | kthread_stop(khugepaged_thread); | |
2288 | khugepaged_thread = NULL; | |
2289 | } | |
2290 | fail: | |
2291 | mutex_unlock(&khugepaged_mutex); | |
2292 | return err; | |
2293 | } |