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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 | ||
27e1f827 SL |
80 | #define MAX_PTE_MAPPED_THP 8 |
81 | ||
b46e756f KS |
82 | /** |
83 | * struct mm_slot - hash lookup from mm to mm_slot | |
84 | * @hash: hash collision list | |
85 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
86 | * @mm: the mm that this information is valid for | |
87 | */ | |
88 | struct mm_slot { | |
89 | struct hlist_node hash; | |
90 | struct list_head mm_node; | |
91 | struct mm_struct *mm; | |
27e1f827 SL |
92 | |
93 | /* pte-mapped THP in this mm */ | |
94 | int nr_pte_mapped_thp; | |
95 | unsigned long pte_mapped_thp[MAX_PTE_MAPPED_THP]; | |
b46e756f KS |
96 | }; |
97 | ||
98 | /** | |
99 | * struct khugepaged_scan - cursor for scanning | |
100 | * @mm_head: the head of the mm list to scan | |
101 | * @mm_slot: the current mm_slot we are scanning | |
102 | * @address: the next address inside that to be scanned | |
103 | * | |
104 | * There is only the one khugepaged_scan instance of this cursor structure. | |
105 | */ | |
106 | struct khugepaged_scan { | |
107 | struct list_head mm_head; | |
108 | struct mm_slot *mm_slot; | |
109 | unsigned long address; | |
110 | }; | |
111 | ||
112 | static struct khugepaged_scan khugepaged_scan = { | |
113 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), | |
114 | }; | |
115 | ||
e1465d12 | 116 | #ifdef CONFIG_SYSFS |
b46e756f KS |
117 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, |
118 | struct kobj_attribute *attr, | |
119 | char *buf) | |
120 | { | |
121 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
122 | } | |
123 | ||
124 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
125 | struct kobj_attribute *attr, | |
126 | const char *buf, size_t count) | |
127 | { | |
128 | unsigned long msecs; | |
129 | int err; | |
130 | ||
131 | err = kstrtoul(buf, 10, &msecs); | |
132 | if (err || msecs > UINT_MAX) | |
133 | return -EINVAL; | |
134 | ||
135 | khugepaged_scan_sleep_millisecs = msecs; | |
136 | khugepaged_sleep_expire = 0; | |
137 | wake_up_interruptible(&khugepaged_wait); | |
138 | ||
139 | return count; | |
140 | } | |
141 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
142 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
143 | scan_sleep_millisecs_store); | |
144 | ||
145 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
146 | struct kobj_attribute *attr, | |
147 | char *buf) | |
148 | { | |
149 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
150 | } | |
151 | ||
152 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
153 | struct kobj_attribute *attr, | |
154 | const char *buf, size_t count) | |
155 | { | |
156 | unsigned long msecs; | |
157 | int err; | |
158 | ||
159 | err = kstrtoul(buf, 10, &msecs); | |
160 | if (err || msecs > UINT_MAX) | |
161 | return -EINVAL; | |
162 | ||
163 | khugepaged_alloc_sleep_millisecs = msecs; | |
164 | khugepaged_sleep_expire = 0; | |
165 | wake_up_interruptible(&khugepaged_wait); | |
166 | ||
167 | return count; | |
168 | } | |
169 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
170 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
171 | alloc_sleep_millisecs_store); | |
172 | ||
173 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
174 | struct kobj_attribute *attr, | |
175 | char *buf) | |
176 | { | |
177 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
178 | } | |
179 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
180 | struct kobj_attribute *attr, | |
181 | const char *buf, size_t count) | |
182 | { | |
183 | int err; | |
184 | unsigned long pages; | |
185 | ||
186 | err = kstrtoul(buf, 10, &pages); | |
187 | if (err || !pages || pages > UINT_MAX) | |
188 | return -EINVAL; | |
189 | ||
190 | khugepaged_pages_to_scan = pages; | |
191 | ||
192 | return count; | |
193 | } | |
194 | static struct kobj_attribute pages_to_scan_attr = | |
195 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
196 | pages_to_scan_store); | |
197 | ||
198 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
199 | struct kobj_attribute *attr, | |
200 | char *buf) | |
201 | { | |
202 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
203 | } | |
204 | static struct kobj_attribute pages_collapsed_attr = | |
205 | __ATTR_RO(pages_collapsed); | |
206 | ||
207 | static ssize_t full_scans_show(struct kobject *kobj, | |
208 | struct kobj_attribute *attr, | |
209 | char *buf) | |
210 | { | |
211 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
212 | } | |
213 | static struct kobj_attribute full_scans_attr = | |
214 | __ATTR_RO(full_scans); | |
215 | ||
216 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
217 | struct kobj_attribute *attr, char *buf) | |
218 | { | |
219 | return single_hugepage_flag_show(kobj, attr, buf, | |
220 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
221 | } | |
222 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
223 | struct kobj_attribute *attr, | |
224 | const char *buf, size_t count) | |
225 | { | |
226 | return single_hugepage_flag_store(kobj, attr, buf, count, | |
227 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
228 | } | |
229 | static struct kobj_attribute khugepaged_defrag_attr = | |
230 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
231 | khugepaged_defrag_store); | |
232 | ||
233 | /* | |
234 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
235 | * any unmapped ptes in turn potentially increasing the memory | |
236 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
237 | * reduce the available free memory in the system as it | |
238 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
239 | * free memory in the system during the khugepaged scan. | |
240 | */ | |
241 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
242 | struct kobj_attribute *attr, | |
243 | char *buf) | |
244 | { | |
245 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
246 | } | |
247 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
248 | struct kobj_attribute *attr, | |
249 | const char *buf, size_t count) | |
250 | { | |
251 | int err; | |
252 | unsigned long max_ptes_none; | |
253 | ||
254 | err = kstrtoul(buf, 10, &max_ptes_none); | |
255 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
256 | return -EINVAL; | |
257 | ||
258 | khugepaged_max_ptes_none = max_ptes_none; | |
259 | ||
260 | return count; | |
261 | } | |
262 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
263 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
264 | khugepaged_max_ptes_none_store); | |
265 | ||
266 | static ssize_t khugepaged_max_ptes_swap_show(struct kobject *kobj, | |
267 | struct kobj_attribute *attr, | |
268 | char *buf) | |
269 | { | |
270 | return sprintf(buf, "%u\n", khugepaged_max_ptes_swap); | |
271 | } | |
272 | ||
273 | static ssize_t khugepaged_max_ptes_swap_store(struct kobject *kobj, | |
274 | struct kobj_attribute *attr, | |
275 | const char *buf, size_t count) | |
276 | { | |
277 | int err; | |
278 | unsigned long max_ptes_swap; | |
279 | ||
280 | err = kstrtoul(buf, 10, &max_ptes_swap); | |
281 | if (err || max_ptes_swap > HPAGE_PMD_NR-1) | |
282 | return -EINVAL; | |
283 | ||
284 | khugepaged_max_ptes_swap = max_ptes_swap; | |
285 | ||
286 | return count; | |
287 | } | |
288 | ||
289 | static struct kobj_attribute khugepaged_max_ptes_swap_attr = | |
290 | __ATTR(max_ptes_swap, 0644, khugepaged_max_ptes_swap_show, | |
291 | khugepaged_max_ptes_swap_store); | |
292 | ||
293 | static struct attribute *khugepaged_attr[] = { | |
294 | &khugepaged_defrag_attr.attr, | |
295 | &khugepaged_max_ptes_none_attr.attr, | |
296 | &pages_to_scan_attr.attr, | |
297 | &pages_collapsed_attr.attr, | |
298 | &full_scans_attr.attr, | |
299 | &scan_sleep_millisecs_attr.attr, | |
300 | &alloc_sleep_millisecs_attr.attr, | |
301 | &khugepaged_max_ptes_swap_attr.attr, | |
302 | NULL, | |
303 | }; | |
304 | ||
305 | struct attribute_group khugepaged_attr_group = { | |
306 | .attrs = khugepaged_attr, | |
307 | .name = "khugepaged", | |
308 | }; | |
e1465d12 | 309 | #endif /* CONFIG_SYSFS */ |
b46e756f | 310 | |
f3f0e1d2 | 311 | #define VM_NO_KHUGEPAGED (VM_SPECIAL | VM_HUGETLB) |
b46e756f KS |
312 | |
313 | int hugepage_madvise(struct vm_area_struct *vma, | |
314 | unsigned long *vm_flags, int advice) | |
315 | { | |
316 | switch (advice) { | |
317 | case MADV_HUGEPAGE: | |
318 | #ifdef CONFIG_S390 | |
319 | /* | |
320 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
321 | * can't handle this properly after s390_enable_sie, so we simply | |
322 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
323 | */ | |
324 | if (mm_has_pgste(vma->vm_mm)) | |
325 | return 0; | |
326 | #endif | |
327 | *vm_flags &= ~VM_NOHUGEPAGE; | |
328 | *vm_flags |= VM_HUGEPAGE; | |
329 | /* | |
330 | * If the vma become good for khugepaged to scan, | |
331 | * register it here without waiting a page fault that | |
332 | * may not happen any time soon. | |
333 | */ | |
334 | if (!(*vm_flags & VM_NO_KHUGEPAGED) && | |
335 | khugepaged_enter_vma_merge(vma, *vm_flags)) | |
336 | return -ENOMEM; | |
337 | break; | |
338 | case MADV_NOHUGEPAGE: | |
339 | *vm_flags &= ~VM_HUGEPAGE; | |
340 | *vm_flags |= VM_NOHUGEPAGE; | |
341 | /* | |
342 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
343 | * this vma even if we leave the mm registered in khugepaged if | |
344 | * it got registered before VM_NOHUGEPAGE was set. | |
345 | */ | |
346 | break; | |
347 | } | |
348 | ||
349 | return 0; | |
350 | } | |
351 | ||
352 | int __init khugepaged_init(void) | |
353 | { | |
354 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
355 | sizeof(struct mm_slot), | |
356 | __alignof__(struct mm_slot), 0, NULL); | |
357 | if (!mm_slot_cache) | |
358 | return -ENOMEM; | |
359 | ||
360 | khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; | |
361 | khugepaged_max_ptes_none = HPAGE_PMD_NR - 1; | |
362 | khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8; | |
363 | ||
364 | return 0; | |
365 | } | |
366 | ||
367 | void __init khugepaged_destroy(void) | |
368 | { | |
369 | kmem_cache_destroy(mm_slot_cache); | |
370 | } | |
371 | ||
372 | static inline struct mm_slot *alloc_mm_slot(void) | |
373 | { | |
374 | if (!mm_slot_cache) /* initialization failed */ | |
375 | return NULL; | |
376 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
377 | } | |
378 | ||
379 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
380 | { | |
381 | kmem_cache_free(mm_slot_cache, mm_slot); | |
382 | } | |
383 | ||
384 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
385 | { | |
386 | struct mm_slot *mm_slot; | |
387 | ||
388 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) | |
389 | if (mm == mm_slot->mm) | |
390 | return mm_slot; | |
391 | ||
392 | return NULL; | |
393 | } | |
394 | ||
395 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
396 | struct mm_slot *mm_slot) | |
397 | { | |
398 | mm_slot->mm = mm; | |
399 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); | |
400 | } | |
401 | ||
402 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
403 | { | |
404 | return atomic_read(&mm->mm_users) == 0; | |
405 | } | |
406 | ||
50f8b92f SL |
407 | static bool hugepage_vma_check(struct vm_area_struct *vma, |
408 | unsigned long vm_flags) | |
c2231020 | 409 | { |
50f8b92f SL |
410 | if ((!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || |
411 | (vm_flags & VM_NOHUGEPAGE) || | |
c2231020 YS |
412 | test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) |
413 | return false; | |
99cb0dbd SL |
414 | |
415 | if (shmem_file(vma->vm_file) || | |
416 | (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && | |
417 | vma->vm_file && | |
418 | (vm_flags & VM_DENYWRITE))) { | |
c2231020 YS |
419 | if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) |
420 | return false; | |
421 | return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, | |
422 | HPAGE_PMD_NR); | |
423 | } | |
424 | if (!vma->anon_vma || vma->vm_ops) | |
425 | return false; | |
426 | if (is_vma_temporary_stack(vma)) | |
427 | return false; | |
50f8b92f | 428 | return !(vm_flags & VM_NO_KHUGEPAGED); |
c2231020 YS |
429 | } |
430 | ||
b46e756f KS |
431 | int __khugepaged_enter(struct mm_struct *mm) |
432 | { | |
433 | struct mm_slot *mm_slot; | |
434 | int wakeup; | |
435 | ||
436 | mm_slot = alloc_mm_slot(); | |
437 | if (!mm_slot) | |
438 | return -ENOMEM; | |
439 | ||
440 | /* __khugepaged_exit() must not run from under us */ | |
441 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); | |
442 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { | |
443 | free_mm_slot(mm_slot); | |
444 | return 0; | |
445 | } | |
446 | ||
447 | spin_lock(&khugepaged_mm_lock); | |
448 | insert_to_mm_slots_hash(mm, mm_slot); | |
449 | /* | |
450 | * Insert just behind the scanning cursor, to let the area settle | |
451 | * down a little. | |
452 | */ | |
453 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
454 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
455 | spin_unlock(&khugepaged_mm_lock); | |
456 | ||
f1f10076 | 457 | mmgrab(mm); |
b46e756f KS |
458 | if (wakeup) |
459 | wake_up_interruptible(&khugepaged_wait); | |
460 | ||
461 | return 0; | |
462 | } | |
463 | ||
464 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, | |
465 | unsigned long vm_flags) | |
466 | { | |
467 | unsigned long hstart, hend; | |
c2231020 YS |
468 | |
469 | /* | |
99cb0dbd SL |
470 | * khugepaged only supports read-only files for non-shmem files. |
471 | * khugepaged does not yet work on special mappings. And | |
472 | * file-private shmem THP is not supported. | |
c2231020 | 473 | */ |
50f8b92f | 474 | if (!hugepage_vma_check(vma, vm_flags)) |
b46e756f | 475 | return 0; |
c2231020 | 476 | |
b46e756f KS |
477 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
478 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
479 | if (hstart < hend) | |
480 | return khugepaged_enter(vma, vm_flags); | |
481 | return 0; | |
482 | } | |
483 | ||
484 | void __khugepaged_exit(struct mm_struct *mm) | |
485 | { | |
486 | struct mm_slot *mm_slot; | |
487 | int free = 0; | |
488 | ||
489 | spin_lock(&khugepaged_mm_lock); | |
490 | mm_slot = get_mm_slot(mm); | |
491 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
492 | hash_del(&mm_slot->hash); | |
493 | list_del(&mm_slot->mm_node); | |
494 | free = 1; | |
495 | } | |
496 | spin_unlock(&khugepaged_mm_lock); | |
497 | ||
498 | if (free) { | |
499 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
500 | free_mm_slot(mm_slot); | |
501 | mmdrop(mm); | |
502 | } else if (mm_slot) { | |
503 | /* | |
504 | * This is required to serialize against | |
505 | * khugepaged_test_exit() (which is guaranteed to run | |
506 | * under mmap sem read mode). Stop here (after we | |
507 | * return all pagetables will be destroyed) until | |
508 | * khugepaged has finished working on the pagetables | |
509 | * under the mmap_sem. | |
510 | */ | |
511 | down_write(&mm->mmap_sem); | |
512 | up_write(&mm->mmap_sem); | |
513 | } | |
514 | } | |
515 | ||
516 | static void release_pte_page(struct page *page) | |
517 | { | |
d44d363f | 518 | dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); |
b46e756f KS |
519 | unlock_page(page); |
520 | putback_lru_page(page); | |
521 | } | |
522 | ||
523 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
524 | { | |
525 | while (--_pte >= pte) { | |
526 | pte_t pteval = *_pte; | |
527 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) | |
528 | release_pte_page(pte_page(pteval)); | |
529 | } | |
530 | } | |
531 | ||
532 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, | |
533 | unsigned long address, | |
534 | pte_t *pte) | |
535 | { | |
536 | struct page *page = NULL; | |
537 | pte_t *_pte; | |
0db501f7 EA |
538 | int none_or_zero = 0, result = 0, referenced = 0; |
539 | bool writable = false; | |
b46e756f KS |
540 | |
541 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
542 | _pte++, address += PAGE_SIZE) { | |
543 | pte_t pteval = *_pte; | |
544 | if (pte_none(pteval) || (pte_present(pteval) && | |
545 | is_zero_pfn(pte_pfn(pteval)))) { | |
546 | if (!userfaultfd_armed(vma) && | |
547 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
548 | continue; | |
549 | } else { | |
550 | result = SCAN_EXCEED_NONE_PTE; | |
551 | goto out; | |
552 | } | |
553 | } | |
554 | if (!pte_present(pteval)) { | |
555 | result = SCAN_PTE_NON_PRESENT; | |
556 | goto out; | |
557 | } | |
558 | page = vm_normal_page(vma, address, pteval); | |
559 | if (unlikely(!page)) { | |
560 | result = SCAN_PAGE_NULL; | |
561 | goto out; | |
562 | } | |
563 | ||
fece2029 KS |
564 | /* TODO: teach khugepaged to collapse THP mapped with pte */ |
565 | if (PageCompound(page)) { | |
566 | result = SCAN_PAGE_COMPOUND; | |
567 | goto out; | |
568 | } | |
569 | ||
b46e756f | 570 | VM_BUG_ON_PAGE(!PageAnon(page), page); |
b46e756f KS |
571 | |
572 | /* | |
573 | * We can do it before isolate_lru_page because the | |
574 | * page can't be freed from under us. NOTE: PG_lock | |
575 | * is needed to serialize against split_huge_page | |
576 | * when invoked from the VM. | |
577 | */ | |
578 | if (!trylock_page(page)) { | |
579 | result = SCAN_PAGE_LOCK; | |
580 | goto out; | |
581 | } | |
582 | ||
583 | /* | |
584 | * cannot use mapcount: can't collapse if there's a gup pin. | |
585 | * The page must only be referenced by the scanned process | |
586 | * and page swap cache. | |
587 | */ | |
2948be5a | 588 | if (page_count(page) != 1 + PageSwapCache(page)) { |
b46e756f KS |
589 | unlock_page(page); |
590 | result = SCAN_PAGE_COUNT; | |
591 | goto out; | |
592 | } | |
593 | if (pte_write(pteval)) { | |
594 | writable = true; | |
595 | } else { | |
596 | if (PageSwapCache(page) && | |
597 | !reuse_swap_page(page, NULL)) { | |
598 | unlock_page(page); | |
599 | result = SCAN_SWAP_CACHE_PAGE; | |
600 | goto out; | |
601 | } | |
602 | /* | |
603 | * Page is not in the swap cache. It can be collapsed | |
604 | * into a THP. | |
605 | */ | |
606 | } | |
607 | ||
608 | /* | |
609 | * Isolate the page to avoid collapsing an hugepage | |
610 | * currently in use by the VM. | |
611 | */ | |
612 | if (isolate_lru_page(page)) { | |
613 | unlock_page(page); | |
614 | result = SCAN_DEL_PAGE_LRU; | |
615 | goto out; | |
616 | } | |
d44d363f SL |
617 | inc_node_page_state(page, |
618 | NR_ISOLATED_ANON + page_is_file_cache(page)); | |
b46e756f KS |
619 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
620 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
621 | ||
0db501f7 | 622 | /* There should be enough young pte to collapse the page */ |
b46e756f KS |
623 | if (pte_young(pteval) || |
624 | page_is_young(page) || PageReferenced(page) || | |
625 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 626 | referenced++; |
b46e756f KS |
627 | } |
628 | if (likely(writable)) { | |
629 | if (likely(referenced)) { | |
630 | result = SCAN_SUCCEED; | |
631 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, | |
632 | referenced, writable, result); | |
633 | return 1; | |
634 | } | |
635 | } else { | |
636 | result = SCAN_PAGE_RO; | |
637 | } | |
638 | ||
639 | out: | |
640 | release_pte_pages(pte, _pte); | |
641 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, | |
642 | referenced, writable, result); | |
643 | return 0; | |
644 | } | |
645 | ||
646 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
647 | struct vm_area_struct *vma, | |
648 | unsigned long address, | |
649 | spinlock_t *ptl) | |
650 | { | |
651 | pte_t *_pte; | |
338a16ba DR |
652 | for (_pte = pte; _pte < pte + HPAGE_PMD_NR; |
653 | _pte++, page++, address += PAGE_SIZE) { | |
b46e756f KS |
654 | pte_t pteval = *_pte; |
655 | struct page *src_page; | |
656 | ||
657 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
658 | clear_user_highpage(page, address); | |
659 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
660 | if (is_zero_pfn(pte_pfn(pteval))) { | |
661 | /* | |
662 | * ptl mostly unnecessary. | |
663 | */ | |
664 | spin_lock(ptl); | |
665 | /* | |
666 | * paravirt calls inside pte_clear here are | |
667 | * superfluous. | |
668 | */ | |
669 | pte_clear(vma->vm_mm, address, _pte); | |
670 | spin_unlock(ptl); | |
671 | } | |
672 | } else { | |
673 | src_page = pte_page(pteval); | |
674 | copy_user_highpage(page, src_page, address, vma); | |
675 | VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page); | |
676 | release_pte_page(src_page); | |
677 | /* | |
678 | * ptl mostly unnecessary, but preempt has to | |
679 | * be disabled to update the per-cpu stats | |
680 | * inside page_remove_rmap(). | |
681 | */ | |
682 | spin_lock(ptl); | |
683 | /* | |
684 | * paravirt calls inside pte_clear here are | |
685 | * superfluous. | |
686 | */ | |
687 | pte_clear(vma->vm_mm, address, _pte); | |
688 | page_remove_rmap(src_page, false); | |
689 | spin_unlock(ptl); | |
690 | free_page_and_swap_cache(src_page); | |
691 | } | |
b46e756f KS |
692 | } |
693 | } | |
694 | ||
695 | static void khugepaged_alloc_sleep(void) | |
696 | { | |
697 | DEFINE_WAIT(wait); | |
698 | ||
699 | add_wait_queue(&khugepaged_wait, &wait); | |
700 | freezable_schedule_timeout_interruptible( | |
701 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
702 | remove_wait_queue(&khugepaged_wait, &wait); | |
703 | } | |
704 | ||
705 | static int khugepaged_node_load[MAX_NUMNODES]; | |
706 | ||
707 | static bool khugepaged_scan_abort(int nid) | |
708 | { | |
709 | int i; | |
710 | ||
711 | /* | |
a5f5f91d | 712 | * If node_reclaim_mode is disabled, then no extra effort is made to |
b46e756f KS |
713 | * allocate memory locally. |
714 | */ | |
a5f5f91d | 715 | if (!node_reclaim_mode) |
b46e756f KS |
716 | return false; |
717 | ||
718 | /* If there is a count for this node already, it must be acceptable */ | |
719 | if (khugepaged_node_load[nid]) | |
720 | return false; | |
721 | ||
722 | for (i = 0; i < MAX_NUMNODES; i++) { | |
723 | if (!khugepaged_node_load[i]) | |
724 | continue; | |
a55c7454 | 725 | if (node_distance(nid, i) > node_reclaim_distance) |
b46e756f KS |
726 | return true; |
727 | } | |
728 | return false; | |
729 | } | |
730 | ||
731 | /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */ | |
732 | static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void) | |
733 | { | |
25160354 | 734 | return khugepaged_defrag() ? GFP_TRANSHUGE : GFP_TRANSHUGE_LIGHT; |
b46e756f KS |
735 | } |
736 | ||
737 | #ifdef CONFIG_NUMA | |
738 | static int khugepaged_find_target_node(void) | |
739 | { | |
740 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
741 | int nid, target_node = 0, max_value = 0; | |
742 | ||
743 | /* find first node with max normal pages hit */ | |
744 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
745 | if (khugepaged_node_load[nid] > max_value) { | |
746 | max_value = khugepaged_node_load[nid]; | |
747 | target_node = nid; | |
748 | } | |
749 | ||
750 | /* do some balance if several nodes have the same hit record */ | |
751 | if (target_node <= last_khugepaged_target_node) | |
752 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
753 | nid++) | |
754 | if (max_value == khugepaged_node_load[nid]) { | |
755 | target_node = nid; | |
756 | break; | |
757 | } | |
758 | ||
759 | last_khugepaged_target_node = target_node; | |
760 | return target_node; | |
761 | } | |
762 | ||
763 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
764 | { | |
765 | if (IS_ERR(*hpage)) { | |
766 | if (!*wait) | |
767 | return false; | |
768 | ||
769 | *wait = false; | |
770 | *hpage = NULL; | |
771 | khugepaged_alloc_sleep(); | |
772 | } else if (*hpage) { | |
773 | put_page(*hpage); | |
774 | *hpage = NULL; | |
775 | } | |
776 | ||
777 | return true; | |
778 | } | |
779 | ||
780 | static struct page * | |
988ddb71 | 781 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f KS |
782 | { |
783 | VM_BUG_ON_PAGE(*hpage, *hpage); | |
784 | ||
b46e756f KS |
785 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); |
786 | if (unlikely(!*hpage)) { | |
787 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
788 | *hpage = ERR_PTR(-ENOMEM); | |
789 | return NULL; | |
790 | } | |
791 | ||
792 | prep_transhuge_page(*hpage); | |
793 | count_vm_event(THP_COLLAPSE_ALLOC); | |
794 | return *hpage; | |
795 | } | |
796 | #else | |
797 | static int khugepaged_find_target_node(void) | |
798 | { | |
799 | return 0; | |
800 | } | |
801 | ||
802 | static inline struct page *alloc_khugepaged_hugepage(void) | |
803 | { | |
804 | struct page *page; | |
805 | ||
806 | page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(), | |
807 | HPAGE_PMD_ORDER); | |
808 | if (page) | |
809 | prep_transhuge_page(page); | |
810 | return page; | |
811 | } | |
812 | ||
813 | static struct page *khugepaged_alloc_hugepage(bool *wait) | |
814 | { | |
815 | struct page *hpage; | |
816 | ||
817 | do { | |
818 | hpage = alloc_khugepaged_hugepage(); | |
819 | if (!hpage) { | |
820 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
821 | if (!*wait) | |
822 | return NULL; | |
823 | ||
824 | *wait = false; | |
825 | khugepaged_alloc_sleep(); | |
826 | } else | |
827 | count_vm_event(THP_COLLAPSE_ALLOC); | |
828 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
829 | ||
830 | return hpage; | |
831 | } | |
832 | ||
833 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
834 | { | |
835 | if (!*hpage) | |
836 | *hpage = khugepaged_alloc_hugepage(wait); | |
837 | ||
838 | if (unlikely(!*hpage)) | |
839 | return false; | |
840 | ||
841 | return true; | |
842 | } | |
843 | ||
844 | static struct page * | |
988ddb71 | 845 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f | 846 | { |
b46e756f KS |
847 | VM_BUG_ON(!*hpage); |
848 | ||
849 | return *hpage; | |
850 | } | |
851 | #endif | |
852 | ||
b46e756f KS |
853 | /* |
854 | * If mmap_sem temporarily dropped, revalidate vma | |
855 | * before taking mmap_sem. | |
856 | * Return 0 if succeeds, otherwise return none-zero | |
857 | * value (scan code). | |
858 | */ | |
859 | ||
c131f751 KS |
860 | static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, |
861 | struct vm_area_struct **vmap) | |
b46e756f KS |
862 | { |
863 | struct vm_area_struct *vma; | |
864 | unsigned long hstart, hend; | |
865 | ||
866 | if (unlikely(khugepaged_test_exit(mm))) | |
867 | return SCAN_ANY_PROCESS; | |
868 | ||
c131f751 | 869 | *vmap = vma = find_vma(mm, address); |
b46e756f KS |
870 | if (!vma) |
871 | return SCAN_VMA_NULL; | |
872 | ||
873 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
874 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
875 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
876 | return SCAN_ADDRESS_RANGE; | |
50f8b92f | 877 | if (!hugepage_vma_check(vma, vma->vm_flags)) |
b46e756f KS |
878 | return SCAN_VMA_CHECK; |
879 | return 0; | |
880 | } | |
881 | ||
882 | /* | |
883 | * Bring missing pages in from swap, to complete THP collapse. | |
884 | * Only done if khugepaged_scan_pmd believes it is worthwhile. | |
885 | * | |
886 | * Called and returns without pte mapped or spinlocks held, | |
887 | * but with mmap_sem held to protect against vma changes. | |
888 | */ | |
889 | ||
890 | static bool __collapse_huge_page_swapin(struct mm_struct *mm, | |
891 | struct vm_area_struct *vma, | |
0db501f7 EA |
892 | unsigned long address, pmd_t *pmd, |
893 | int referenced) | |
b46e756f | 894 | { |
2b740303 SJ |
895 | int swapped_in = 0; |
896 | vm_fault_t ret = 0; | |
82b0f8c3 | 897 | struct vm_fault vmf = { |
b46e756f KS |
898 | .vma = vma, |
899 | .address = address, | |
900 | .flags = FAULT_FLAG_ALLOW_RETRY, | |
901 | .pmd = pmd, | |
0721ec8b | 902 | .pgoff = linear_page_index(vma, address), |
b46e756f KS |
903 | }; |
904 | ||
982785c6 EA |
905 | /* we only decide to swapin, if there is enough young ptes */ |
906 | if (referenced < HPAGE_PMD_NR/2) { | |
907 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); | |
908 | return false; | |
909 | } | |
82b0f8c3 JK |
910 | vmf.pte = pte_offset_map(pmd, address); |
911 | for (; vmf.address < address + HPAGE_PMD_NR*PAGE_SIZE; | |
912 | vmf.pte++, vmf.address += PAGE_SIZE) { | |
2994302b JK |
913 | vmf.orig_pte = *vmf.pte; |
914 | if (!is_swap_pte(vmf.orig_pte)) | |
b46e756f KS |
915 | continue; |
916 | swapped_in++; | |
2994302b | 917 | ret = do_swap_page(&vmf); |
0db501f7 | 918 | |
b46e756f KS |
919 | /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */ |
920 | if (ret & VM_FAULT_RETRY) { | |
921 | down_read(&mm->mmap_sem); | |
82b0f8c3 | 922 | if (hugepage_vma_revalidate(mm, address, &vmf.vma)) { |
47f863ea | 923 | /* vma is no longer available, don't continue to swapin */ |
0db501f7 | 924 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f | 925 | return false; |
47f863ea | 926 | } |
b46e756f | 927 | /* check if the pmd is still valid */ |
835152a2 SP |
928 | if (mm_find_pmd(mm, address) != pmd) { |
929 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); | |
b46e756f | 930 | return false; |
835152a2 | 931 | } |
b46e756f KS |
932 | } |
933 | if (ret & VM_FAULT_ERROR) { | |
0db501f7 | 934 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f KS |
935 | return false; |
936 | } | |
937 | /* pte is unmapped now, we need to map it */ | |
82b0f8c3 | 938 | vmf.pte = pte_offset_map(pmd, vmf.address); |
b46e756f | 939 | } |
82b0f8c3 JK |
940 | vmf.pte--; |
941 | pte_unmap(vmf.pte); | |
0db501f7 | 942 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1); |
b46e756f KS |
943 | return true; |
944 | } | |
945 | ||
946 | static void collapse_huge_page(struct mm_struct *mm, | |
947 | unsigned long address, | |
948 | struct page **hpage, | |
0db501f7 | 949 | int node, int referenced) |
b46e756f KS |
950 | { |
951 | pmd_t *pmd, _pmd; | |
952 | pte_t *pte; | |
953 | pgtable_t pgtable; | |
954 | struct page *new_page; | |
955 | spinlock_t *pmd_ptl, *pte_ptl; | |
956 | int isolated = 0, result = 0; | |
957 | struct mem_cgroup *memcg; | |
c131f751 | 958 | struct vm_area_struct *vma; |
ac46d4f3 | 959 | struct mmu_notifier_range range; |
b46e756f KS |
960 | gfp_t gfp; |
961 | ||
962 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
963 | ||
964 | /* Only allocate from the target node */ | |
41b6167e | 965 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
b46e756f | 966 | |
988ddb71 KS |
967 | /* |
968 | * Before allocating the hugepage, release the mmap_sem read lock. | |
969 | * The allocation can take potentially a long time if it involves | |
970 | * sync compaction, and we do not need to hold the mmap_sem during | |
971 | * that. We will recheck the vma after taking it again in write mode. | |
972 | */ | |
973 | up_read(&mm->mmap_sem); | |
974 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
b46e756f KS |
975 | if (!new_page) { |
976 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
977 | goto out_nolock; | |
978 | } | |
979 | ||
2a70f6a7 | 980 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { |
b46e756f KS |
981 | result = SCAN_CGROUP_CHARGE_FAIL; |
982 | goto out_nolock; | |
983 | } | |
984 | ||
985 | down_read(&mm->mmap_sem); | |
c131f751 | 986 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f KS |
987 | if (result) { |
988 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
989 | up_read(&mm->mmap_sem); | |
990 | goto out_nolock; | |
991 | } | |
992 | ||
993 | pmd = mm_find_pmd(mm, address); | |
994 | if (!pmd) { | |
995 | result = SCAN_PMD_NULL; | |
996 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
997 | up_read(&mm->mmap_sem); | |
998 | goto out_nolock; | |
999 | } | |
1000 | ||
1001 | /* | |
1002 | * __collapse_huge_page_swapin always returns with mmap_sem locked. | |
47f863ea | 1003 | * If it fails, we release mmap_sem and jump out_nolock. |
b46e756f KS |
1004 | * Continuing to collapse causes inconsistency. |
1005 | */ | |
0db501f7 | 1006 | if (!__collapse_huge_page_swapin(mm, vma, address, pmd, referenced)) { |
b46e756f KS |
1007 | mem_cgroup_cancel_charge(new_page, memcg, true); |
1008 | up_read(&mm->mmap_sem); | |
1009 | goto out_nolock; | |
1010 | } | |
1011 | ||
1012 | up_read(&mm->mmap_sem); | |
1013 | /* | |
1014 | * Prevent all access to pagetables with the exception of | |
1015 | * gup_fast later handled by the ptep_clear_flush and the VM | |
1016 | * handled by the anon_vma lock + PG_lock. | |
1017 | */ | |
1018 | down_write(&mm->mmap_sem); | |
59ea6d06 AA |
1019 | result = SCAN_ANY_PROCESS; |
1020 | if (!mmget_still_valid(mm)) | |
1021 | goto out; | |
c131f751 | 1022 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f KS |
1023 | if (result) |
1024 | goto out; | |
1025 | /* check if the pmd is still valid */ | |
1026 | if (mm_find_pmd(mm, address) != pmd) | |
1027 | goto out; | |
1028 | ||
1029 | anon_vma_lock_write(vma->anon_vma); | |
1030 | ||
1031 | pte = pte_offset_map(pmd, address); | |
1032 | pte_ptl = pte_lockptr(mm, pmd); | |
1033 | ||
7269f999 | 1034 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, |
6f4f13e8 | 1035 | address, address + HPAGE_PMD_SIZE); |
ac46d4f3 | 1036 | mmu_notifier_invalidate_range_start(&range); |
b46e756f KS |
1037 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
1038 | /* | |
1039 | * After this gup_fast can't run anymore. This also removes | |
1040 | * any huge TLB entry from the CPU so we won't allow | |
1041 | * huge and small TLB entries for the same virtual address | |
1042 | * to avoid the risk of CPU bugs in that area. | |
1043 | */ | |
1044 | _pmd = pmdp_collapse_flush(vma, address, pmd); | |
1045 | spin_unlock(pmd_ptl); | |
ac46d4f3 | 1046 | mmu_notifier_invalidate_range_end(&range); |
b46e756f KS |
1047 | |
1048 | spin_lock(pte_ptl); | |
1049 | isolated = __collapse_huge_page_isolate(vma, address, pte); | |
1050 | spin_unlock(pte_ptl); | |
1051 | ||
1052 | if (unlikely(!isolated)) { | |
1053 | pte_unmap(pte); | |
1054 | spin_lock(pmd_ptl); | |
1055 | BUG_ON(!pmd_none(*pmd)); | |
1056 | /* | |
1057 | * We can only use set_pmd_at when establishing | |
1058 | * hugepmds and never for establishing regular pmds that | |
1059 | * points to regular pagetables. Use pmd_populate for that | |
1060 | */ | |
1061 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
1062 | spin_unlock(pmd_ptl); | |
1063 | anon_vma_unlock_write(vma->anon_vma); | |
1064 | result = SCAN_FAIL; | |
1065 | goto out; | |
1066 | } | |
1067 | ||
1068 | /* | |
1069 | * All pages are isolated and locked so anon_vma rmap | |
1070 | * can't run anymore. | |
1071 | */ | |
1072 | anon_vma_unlock_write(vma->anon_vma); | |
1073 | ||
1074 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); | |
1075 | pte_unmap(pte); | |
1076 | __SetPageUptodate(new_page); | |
1077 | pgtable = pmd_pgtable(_pmd); | |
1078 | ||
1079 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); | |
f55e1014 | 1080 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); |
b46e756f KS |
1081 | |
1082 | /* | |
1083 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
1084 | * this is needed to avoid the copy_huge_page writes to become | |
1085 | * visible after the set_pmd_at() write. | |
1086 | */ | |
1087 | smp_wmb(); | |
1088 | ||
1089 | spin_lock(pmd_ptl); | |
1090 | BUG_ON(!pmd_none(*pmd)); | |
1091 | page_add_new_anon_rmap(new_page, vma, address, true); | |
1092 | mem_cgroup_commit_charge(new_page, memcg, false, true); | |
1ff9e6e1 | 1093 | count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1); |
b46e756f KS |
1094 | lru_cache_add_active_or_unevictable(new_page, vma); |
1095 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
1096 | set_pmd_at(mm, address, pmd, _pmd); | |
1097 | update_mmu_cache_pmd(vma, address, pmd); | |
1098 | spin_unlock(pmd_ptl); | |
1099 | ||
1100 | *hpage = NULL; | |
1101 | ||
1102 | khugepaged_pages_collapsed++; | |
1103 | result = SCAN_SUCCEED; | |
1104 | out_up_write: | |
1105 | up_write(&mm->mmap_sem); | |
1106 | out_nolock: | |
1107 | trace_mm_collapse_huge_page(mm, isolated, result); | |
1108 | return; | |
1109 | out: | |
1110 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1111 | goto out_up_write; | |
1112 | } | |
1113 | ||
1114 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
1115 | struct vm_area_struct *vma, | |
1116 | unsigned long address, | |
1117 | struct page **hpage) | |
1118 | { | |
1119 | pmd_t *pmd; | |
1120 | pte_t *pte, *_pte; | |
0db501f7 | 1121 | int ret = 0, none_or_zero = 0, result = 0, referenced = 0; |
b46e756f KS |
1122 | struct page *page = NULL; |
1123 | unsigned long _address; | |
1124 | spinlock_t *ptl; | |
1125 | int node = NUMA_NO_NODE, unmapped = 0; | |
0db501f7 | 1126 | bool writable = false; |
b46e756f KS |
1127 | |
1128 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1129 | ||
1130 | pmd = mm_find_pmd(mm, address); | |
1131 | if (!pmd) { | |
1132 | result = SCAN_PMD_NULL; | |
1133 | goto out; | |
1134 | } | |
1135 | ||
1136 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1137 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1138 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1139 | _pte++, _address += PAGE_SIZE) { | |
1140 | pte_t pteval = *_pte; | |
1141 | if (is_swap_pte(pteval)) { | |
1142 | if (++unmapped <= khugepaged_max_ptes_swap) { | |
1143 | continue; | |
1144 | } else { | |
1145 | result = SCAN_EXCEED_SWAP_PTE; | |
1146 | goto out_unmap; | |
1147 | } | |
1148 | } | |
1149 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
1150 | if (!userfaultfd_armed(vma) && | |
1151 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
1152 | continue; | |
1153 | } else { | |
1154 | result = SCAN_EXCEED_NONE_PTE; | |
1155 | goto out_unmap; | |
1156 | } | |
1157 | } | |
1158 | if (!pte_present(pteval)) { | |
1159 | result = SCAN_PTE_NON_PRESENT; | |
1160 | goto out_unmap; | |
1161 | } | |
1162 | if (pte_write(pteval)) | |
1163 | writable = true; | |
1164 | ||
1165 | page = vm_normal_page(vma, _address, pteval); | |
1166 | if (unlikely(!page)) { | |
1167 | result = SCAN_PAGE_NULL; | |
1168 | goto out_unmap; | |
1169 | } | |
1170 | ||
1171 | /* TODO: teach khugepaged to collapse THP mapped with pte */ | |
1172 | if (PageCompound(page)) { | |
1173 | result = SCAN_PAGE_COMPOUND; | |
1174 | goto out_unmap; | |
1175 | } | |
1176 | ||
1177 | /* | |
1178 | * Record which node the original page is from and save this | |
1179 | * information to khugepaged_node_load[]. | |
1180 | * Khupaged will allocate hugepage from the node has the max | |
1181 | * hit record. | |
1182 | */ | |
1183 | node = page_to_nid(page); | |
1184 | if (khugepaged_scan_abort(node)) { | |
1185 | result = SCAN_SCAN_ABORT; | |
1186 | goto out_unmap; | |
1187 | } | |
1188 | khugepaged_node_load[node]++; | |
1189 | if (!PageLRU(page)) { | |
1190 | result = SCAN_PAGE_LRU; | |
1191 | goto out_unmap; | |
1192 | } | |
1193 | if (PageLocked(page)) { | |
1194 | result = SCAN_PAGE_LOCK; | |
1195 | goto out_unmap; | |
1196 | } | |
1197 | if (!PageAnon(page)) { | |
1198 | result = SCAN_PAGE_ANON; | |
1199 | goto out_unmap; | |
1200 | } | |
1201 | ||
1202 | /* | |
1203 | * cannot use mapcount: can't collapse if there's a gup pin. | |
1204 | * The page must only be referenced by the scanned process | |
1205 | * and page swap cache. | |
1206 | */ | |
2948be5a | 1207 | if (page_count(page) != 1 + PageSwapCache(page)) { |
b46e756f KS |
1208 | result = SCAN_PAGE_COUNT; |
1209 | goto out_unmap; | |
1210 | } | |
1211 | if (pte_young(pteval) || | |
1212 | page_is_young(page) || PageReferenced(page) || | |
1213 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 1214 | referenced++; |
b46e756f KS |
1215 | } |
1216 | if (writable) { | |
1217 | if (referenced) { | |
1218 | result = SCAN_SUCCEED; | |
1219 | ret = 1; | |
1220 | } else { | |
0db501f7 | 1221 | result = SCAN_LACK_REFERENCED_PAGE; |
b46e756f KS |
1222 | } |
1223 | } else { | |
1224 | result = SCAN_PAGE_RO; | |
1225 | } | |
1226 | out_unmap: | |
1227 | pte_unmap_unlock(pte, ptl); | |
1228 | if (ret) { | |
1229 | node = khugepaged_find_target_node(); | |
1230 | /* collapse_huge_page will return with the mmap_sem released */ | |
c131f751 | 1231 | collapse_huge_page(mm, address, hpage, node, referenced); |
b46e756f KS |
1232 | } |
1233 | out: | |
1234 | trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, | |
1235 | none_or_zero, result, unmapped); | |
1236 | return ret; | |
1237 | } | |
1238 | ||
1239 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
1240 | { | |
1241 | struct mm_struct *mm = mm_slot->mm; | |
1242 | ||
35f3aa39 | 1243 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
1244 | |
1245 | if (khugepaged_test_exit(mm)) { | |
1246 | /* free mm_slot */ | |
1247 | hash_del(&mm_slot->hash); | |
1248 | list_del(&mm_slot->mm_node); | |
1249 | ||
1250 | /* | |
1251 | * Not strictly needed because the mm exited already. | |
1252 | * | |
1253 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1254 | */ | |
1255 | ||
1256 | /* khugepaged_mm_lock actually not necessary for the below */ | |
1257 | free_mm_slot(mm_slot); | |
1258 | mmdrop(mm); | |
1259 | } | |
1260 | } | |
1261 | ||
e496cf3d | 1262 | #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) |
27e1f827 SL |
1263 | /* |
1264 | * Notify khugepaged that given addr of the mm is pte-mapped THP. Then | |
1265 | * khugepaged should try to collapse the page table. | |
1266 | */ | |
1267 | static int khugepaged_add_pte_mapped_thp(struct mm_struct *mm, | |
1268 | unsigned long addr) | |
1269 | { | |
1270 | struct mm_slot *mm_slot; | |
1271 | ||
1272 | VM_BUG_ON(addr & ~HPAGE_PMD_MASK); | |
1273 | ||
1274 | spin_lock(&khugepaged_mm_lock); | |
1275 | mm_slot = get_mm_slot(mm); | |
1276 | if (likely(mm_slot && mm_slot->nr_pte_mapped_thp < MAX_PTE_MAPPED_THP)) | |
1277 | mm_slot->pte_mapped_thp[mm_slot->nr_pte_mapped_thp++] = addr; | |
1278 | spin_unlock(&khugepaged_mm_lock); | |
1279 | return 0; | |
1280 | } | |
1281 | ||
1282 | /** | |
1283 | * Try to collapse a pte-mapped THP for mm at address haddr. | |
1284 | * | |
1285 | * This function checks whether all the PTEs in the PMD are pointing to the | |
1286 | * right THP. If so, retract the page table so the THP can refault in with | |
1287 | * as pmd-mapped. | |
1288 | */ | |
1289 | void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) | |
1290 | { | |
1291 | unsigned long haddr = addr & HPAGE_PMD_MASK; | |
1292 | struct vm_area_struct *vma = find_vma(mm, haddr); | |
1293 | struct page *hpage = NULL; | |
1294 | pte_t *start_pte, *pte; | |
1295 | pmd_t *pmd, _pmd; | |
1296 | spinlock_t *ptl; | |
1297 | int count = 0; | |
1298 | int i; | |
1299 | ||
1300 | if (!vma || !vma->vm_file || | |
1301 | vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE) | |
1302 | return; | |
1303 | ||
1304 | /* | |
1305 | * This vm_flags may not have VM_HUGEPAGE if the page was not | |
1306 | * collapsed by this mm. But we can still collapse if the page is | |
1307 | * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check() | |
1308 | * will not fail the vma for missing VM_HUGEPAGE | |
1309 | */ | |
1310 | if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE)) | |
1311 | return; | |
1312 | ||
1313 | pmd = mm_find_pmd(mm, haddr); | |
1314 | if (!pmd) | |
1315 | return; | |
1316 | ||
1317 | start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl); | |
1318 | ||
1319 | /* step 1: check all mapped PTEs are to the right huge page */ | |
1320 | for (i = 0, addr = haddr, pte = start_pte; | |
1321 | i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) { | |
1322 | struct page *page; | |
1323 | ||
1324 | /* empty pte, skip */ | |
1325 | if (pte_none(*pte)) | |
1326 | continue; | |
1327 | ||
1328 | /* page swapped out, abort */ | |
1329 | if (!pte_present(*pte)) | |
1330 | goto abort; | |
1331 | ||
1332 | page = vm_normal_page(vma, addr, *pte); | |
1333 | ||
1334 | if (!page || !PageCompound(page)) | |
1335 | goto abort; | |
1336 | ||
1337 | if (!hpage) { | |
1338 | hpage = compound_head(page); | |
1339 | /* | |
1340 | * The mapping of the THP should not change. | |
1341 | * | |
1342 | * Note that uprobe, debugger, or MAP_PRIVATE may | |
1343 | * change the page table, but the new page will | |
1344 | * not pass PageCompound() check. | |
1345 | */ | |
1346 | if (WARN_ON(hpage->mapping != vma->vm_file->f_mapping)) | |
1347 | goto abort; | |
1348 | } | |
1349 | ||
1350 | /* | |
1351 | * Confirm the page maps to the correct subpage. | |
1352 | * | |
1353 | * Note that uprobe, debugger, or MAP_PRIVATE may change | |
1354 | * the page table, but the new page will not pass | |
1355 | * PageCompound() check. | |
1356 | */ | |
1357 | if (WARN_ON(hpage + i != page)) | |
1358 | goto abort; | |
1359 | count++; | |
1360 | } | |
1361 | ||
1362 | /* step 2: adjust rmap */ | |
1363 | for (i = 0, addr = haddr, pte = start_pte; | |
1364 | i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) { | |
1365 | struct page *page; | |
1366 | ||
1367 | if (pte_none(*pte)) | |
1368 | continue; | |
1369 | page = vm_normal_page(vma, addr, *pte); | |
1370 | page_remove_rmap(page, false); | |
1371 | } | |
1372 | ||
1373 | pte_unmap_unlock(start_pte, ptl); | |
1374 | ||
1375 | /* step 3: set proper refcount and mm_counters. */ | |
1376 | if (hpage) { | |
1377 | page_ref_sub(hpage, count); | |
1378 | add_mm_counter(vma->vm_mm, mm_counter_file(hpage), -count); | |
1379 | } | |
1380 | ||
1381 | /* step 4: collapse pmd */ | |
1382 | ptl = pmd_lock(vma->vm_mm, pmd); | |
1383 | _pmd = pmdp_collapse_flush(vma, addr, pmd); | |
1384 | spin_unlock(ptl); | |
1385 | mm_dec_nr_ptes(mm); | |
1386 | pte_free(mm, pmd_pgtable(_pmd)); | |
1387 | return; | |
1388 | ||
1389 | abort: | |
1390 | pte_unmap_unlock(start_pte, ptl); | |
1391 | } | |
1392 | ||
1393 | static int khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) | |
1394 | { | |
1395 | struct mm_struct *mm = mm_slot->mm; | |
1396 | int i; | |
1397 | ||
1398 | if (likely(mm_slot->nr_pte_mapped_thp == 0)) | |
1399 | return 0; | |
1400 | ||
1401 | if (!down_write_trylock(&mm->mmap_sem)) | |
1402 | return -EBUSY; | |
1403 | ||
1404 | if (unlikely(khugepaged_test_exit(mm))) | |
1405 | goto out; | |
1406 | ||
1407 | for (i = 0; i < mm_slot->nr_pte_mapped_thp; i++) | |
1408 | collapse_pte_mapped_thp(mm, mm_slot->pte_mapped_thp[i]); | |
1409 | ||
1410 | out: | |
1411 | mm_slot->nr_pte_mapped_thp = 0; | |
1412 | up_write(&mm->mmap_sem); | |
1413 | return 0; | |
1414 | } | |
1415 | ||
f3f0e1d2 KS |
1416 | static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) |
1417 | { | |
1418 | struct vm_area_struct *vma; | |
1419 | unsigned long addr; | |
1420 | pmd_t *pmd, _pmd; | |
1421 | ||
1422 | i_mmap_lock_write(mapping); | |
1423 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { | |
27e1f827 SL |
1424 | /* |
1425 | * Check vma->anon_vma to exclude MAP_PRIVATE mappings that | |
1426 | * got written to. These VMAs are likely not worth investing | |
1427 | * down_write(mmap_sem) as PMD-mapping is likely to be split | |
1428 | * later. | |
1429 | * | |
1430 | * Not that vma->anon_vma check is racy: it can be set up after | |
1431 | * the check but before we took mmap_sem by the fault path. | |
1432 | * But page lock would prevent establishing any new ptes of the | |
1433 | * page, so we are safe. | |
1434 | * | |
1435 | * An alternative would be drop the check, but check that page | |
1436 | * table is clear before calling pmdp_collapse_flush() under | |
1437 | * ptl. It has higher chance to recover THP for the VMA, but | |
1438 | * has higher cost too. | |
1439 | */ | |
f3f0e1d2 KS |
1440 | if (vma->anon_vma) |
1441 | continue; | |
1442 | addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
1443 | if (addr & ~HPAGE_PMD_MASK) | |
1444 | continue; | |
1445 | if (vma->vm_end < addr + HPAGE_PMD_SIZE) | |
1446 | continue; | |
1447 | pmd = mm_find_pmd(vma->vm_mm, addr); | |
1448 | if (!pmd) | |
1449 | continue; | |
1450 | /* | |
1451 | * We need exclusive mmap_sem to retract page table. | |
27e1f827 SL |
1452 | * |
1453 | * We use trylock due to lock inversion: we need to acquire | |
1454 | * mmap_sem while holding page lock. Fault path does it in | |
1455 | * reverse order. Trylock is a way to avoid deadlock. | |
f3f0e1d2 KS |
1456 | */ |
1457 | if (down_write_trylock(&vma->vm_mm->mmap_sem)) { | |
1458 | spinlock_t *ptl = pmd_lock(vma->vm_mm, pmd); | |
1459 | /* assume page table is clear */ | |
1460 | _pmd = pmdp_collapse_flush(vma, addr, pmd); | |
1461 | spin_unlock(ptl); | |
1462 | up_write(&vma->vm_mm->mmap_sem); | |
c4812909 | 1463 | mm_dec_nr_ptes(vma->vm_mm); |
d670ffd8 | 1464 | pte_free(vma->vm_mm, pmd_pgtable(_pmd)); |
27e1f827 SL |
1465 | } else { |
1466 | /* Try again later */ | |
1467 | khugepaged_add_pte_mapped_thp(vma->vm_mm, addr); | |
f3f0e1d2 KS |
1468 | } |
1469 | } | |
1470 | i_mmap_unlock_write(mapping); | |
1471 | } | |
1472 | ||
1473 | /** | |
99cb0dbd | 1474 | * collapse_file - collapse filemap/tmpfs/shmem pages into huge one. |
f3f0e1d2 KS |
1475 | * |
1476 | * Basic scheme is simple, details are more complex: | |
87c460a0 | 1477 | * - allocate and lock a new huge page; |
77da9389 | 1478 | * - scan page cache replacing old pages with the new one |
99cb0dbd | 1479 | * + swap/gup in pages if necessary; |
f3f0e1d2 | 1480 | * + fill in gaps; |
77da9389 MW |
1481 | * + keep old pages around in case rollback is required; |
1482 | * - if replacing succeeds: | |
f3f0e1d2 KS |
1483 | * + copy data over; |
1484 | * + free old pages; | |
87c460a0 | 1485 | * + unlock huge page; |
f3f0e1d2 KS |
1486 | * - if replacing failed; |
1487 | * + put all pages back and unfreeze them; | |
77da9389 | 1488 | * + restore gaps in the page cache; |
87c460a0 | 1489 | * + unlock and free huge page; |
f3f0e1d2 | 1490 | */ |
579c571e SL |
1491 | static void collapse_file(struct mm_struct *mm, |
1492 | struct file *file, pgoff_t start, | |
f3f0e1d2 KS |
1493 | struct page **hpage, int node) |
1494 | { | |
579c571e | 1495 | struct address_space *mapping = file->f_mapping; |
f3f0e1d2 | 1496 | gfp_t gfp; |
77da9389 | 1497 | struct page *new_page; |
f3f0e1d2 KS |
1498 | struct mem_cgroup *memcg; |
1499 | pgoff_t index, end = start + HPAGE_PMD_NR; | |
1500 | LIST_HEAD(pagelist); | |
77da9389 | 1501 | XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); |
f3f0e1d2 | 1502 | int nr_none = 0, result = SCAN_SUCCEED; |
99cb0dbd | 1503 | bool is_shmem = shmem_file(file); |
f3f0e1d2 | 1504 | |
99cb0dbd | 1505 | VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); |
f3f0e1d2 KS |
1506 | VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); |
1507 | ||
1508 | /* Only allocate from the target node */ | |
41b6167e | 1509 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
f3f0e1d2 KS |
1510 | |
1511 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
1512 | if (!new_page) { | |
1513 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
1514 | goto out; | |
1515 | } | |
1516 | ||
2a70f6a7 | 1517 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { |
f3f0e1d2 KS |
1518 | result = SCAN_CGROUP_CHARGE_FAIL; |
1519 | goto out; | |
1520 | } | |
1521 | ||
95feeabb HD |
1522 | /* This will be less messy when we use multi-index entries */ |
1523 | do { | |
1524 | xas_lock_irq(&xas); | |
1525 | xas_create_range(&xas); | |
1526 | if (!xas_error(&xas)) | |
1527 | break; | |
1528 | xas_unlock_irq(&xas); | |
1529 | if (!xas_nomem(&xas, GFP_KERNEL)) { | |
1530 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1531 | result = SCAN_FAIL; | |
1532 | goto out; | |
1533 | } | |
1534 | } while (1); | |
1535 | ||
042a3082 | 1536 | __SetPageLocked(new_page); |
99cb0dbd SL |
1537 | if (is_shmem) |
1538 | __SetPageSwapBacked(new_page); | |
f3f0e1d2 KS |
1539 | new_page->index = start; |
1540 | new_page->mapping = mapping; | |
f3f0e1d2 | 1541 | |
f3f0e1d2 | 1542 | /* |
87c460a0 HD |
1543 | * At this point the new_page is locked and not up-to-date. |
1544 | * It's safe to insert it into the page cache, because nobody would | |
1545 | * be able to map it or use it in another way until we unlock it. | |
f3f0e1d2 KS |
1546 | */ |
1547 | ||
77da9389 MW |
1548 | xas_set(&xas, start); |
1549 | for (index = start; index < end; index++) { | |
1550 | struct page *page = xas_next(&xas); | |
1551 | ||
1552 | VM_BUG_ON(index != xas.xa_index); | |
99cb0dbd SL |
1553 | if (is_shmem) { |
1554 | if (!page) { | |
1555 | /* | |
1556 | * Stop if extent has been truncated or | |
1557 | * hole-punched, and is now completely | |
1558 | * empty. | |
1559 | */ | |
1560 | if (index == start) { | |
1561 | if (!xas_next_entry(&xas, end - 1)) { | |
1562 | result = SCAN_TRUNCATED; | |
1563 | goto xa_locked; | |
1564 | } | |
1565 | xas_set(&xas, index); | |
1566 | } | |
1567 | if (!shmem_charge(mapping->host, 1)) { | |
1568 | result = SCAN_FAIL; | |
042a3082 | 1569 | goto xa_locked; |
701270fa | 1570 | } |
99cb0dbd SL |
1571 | xas_store(&xas, new_page); |
1572 | nr_none++; | |
1573 | continue; | |
701270fa | 1574 | } |
99cb0dbd SL |
1575 | |
1576 | if (xa_is_value(page) || !PageUptodate(page)) { | |
1577 | xas_unlock_irq(&xas); | |
1578 | /* swap in or instantiate fallocated page */ | |
1579 | if (shmem_getpage(mapping->host, index, &page, | |
1580 | SGP_NOHUGE)) { | |
1581 | result = SCAN_FAIL; | |
1582 | goto xa_unlocked; | |
1583 | } | |
1584 | } else if (trylock_page(page)) { | |
1585 | get_page(page); | |
1586 | xas_unlock_irq(&xas); | |
1587 | } else { | |
1588 | result = SCAN_PAGE_LOCK; | |
042a3082 | 1589 | goto xa_locked; |
77da9389 | 1590 | } |
99cb0dbd SL |
1591 | } else { /* !is_shmem */ |
1592 | if (!page || xa_is_value(page)) { | |
1593 | xas_unlock_irq(&xas); | |
1594 | page_cache_sync_readahead(mapping, &file->f_ra, | |
1595 | file, index, | |
1596 | PAGE_SIZE); | |
1597 | /* drain pagevecs to help isolate_lru_page() */ | |
1598 | lru_add_drain(); | |
1599 | page = find_lock_page(mapping, index); | |
1600 | if (unlikely(page == NULL)) { | |
1601 | result = SCAN_FAIL; | |
1602 | goto xa_unlocked; | |
1603 | } | |
1604 | } else if (!PageUptodate(page)) { | |
1605 | xas_unlock_irq(&xas); | |
1606 | wait_on_page_locked(page); | |
1607 | if (!trylock_page(page)) { | |
1608 | result = SCAN_PAGE_LOCK; | |
1609 | goto xa_unlocked; | |
1610 | } | |
1611 | get_page(page); | |
1612 | } else if (PageDirty(page)) { | |
f3f0e1d2 | 1613 | result = SCAN_FAIL; |
99cb0dbd SL |
1614 | goto xa_locked; |
1615 | } else if (trylock_page(page)) { | |
1616 | get_page(page); | |
1617 | xas_unlock_irq(&xas); | |
1618 | } else { | |
1619 | result = SCAN_PAGE_LOCK; | |
1620 | goto xa_locked; | |
f3f0e1d2 | 1621 | } |
f3f0e1d2 KS |
1622 | } |
1623 | ||
1624 | /* | |
b93b0163 | 1625 | * The page must be locked, so we can drop the i_pages lock |
f3f0e1d2 KS |
1626 | * without racing with truncate. |
1627 | */ | |
1628 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
1629 | VM_BUG_ON_PAGE(!PageUptodate(page), page); | |
06a5e126 HD |
1630 | |
1631 | /* | |
1632 | * If file was truncated then extended, or hole-punched, before | |
1633 | * we locked the first page, then a THP might be there already. | |
1634 | */ | |
1635 | if (PageTransCompound(page)) { | |
1636 | result = SCAN_PAGE_COMPOUND; | |
1637 | goto out_unlock; | |
1638 | } | |
f3f0e1d2 KS |
1639 | |
1640 | if (page_mapping(page) != mapping) { | |
1641 | result = SCAN_TRUNCATED; | |
1642 | goto out_unlock; | |
1643 | } | |
f3f0e1d2 KS |
1644 | |
1645 | if (isolate_lru_page(page)) { | |
1646 | result = SCAN_DEL_PAGE_LRU; | |
042a3082 | 1647 | goto out_unlock; |
f3f0e1d2 KS |
1648 | } |
1649 | ||
99cb0dbd SL |
1650 | if (page_has_private(page) && |
1651 | !try_to_release_page(page, GFP_KERNEL)) { | |
1652 | result = SCAN_PAGE_HAS_PRIVATE; | |
1653 | goto out_unlock; | |
1654 | } | |
1655 | ||
f3f0e1d2 | 1656 | if (page_mapped(page)) |
977fbdcd | 1657 | unmap_mapping_pages(mapping, index, 1, false); |
f3f0e1d2 | 1658 | |
77da9389 MW |
1659 | xas_lock_irq(&xas); |
1660 | xas_set(&xas, index); | |
f3f0e1d2 | 1661 | |
77da9389 | 1662 | VM_BUG_ON_PAGE(page != xas_load(&xas), page); |
f3f0e1d2 KS |
1663 | VM_BUG_ON_PAGE(page_mapped(page), page); |
1664 | ||
1665 | /* | |
1666 | * The page is expected to have page_count() == 3: | |
1667 | * - we hold a pin on it; | |
77da9389 | 1668 | * - one reference from page cache; |
f3f0e1d2 KS |
1669 | * - one from isolate_lru_page; |
1670 | */ | |
1671 | if (!page_ref_freeze(page, 3)) { | |
1672 | result = SCAN_PAGE_COUNT; | |
042a3082 HD |
1673 | xas_unlock_irq(&xas); |
1674 | putback_lru_page(page); | |
1675 | goto out_unlock; | |
f3f0e1d2 KS |
1676 | } |
1677 | ||
1678 | /* | |
1679 | * Add the page to the list to be able to undo the collapse if | |
1680 | * something go wrong. | |
1681 | */ | |
1682 | list_add_tail(&page->lru, &pagelist); | |
1683 | ||
1684 | /* Finally, replace with the new page. */ | |
4101196b | 1685 | xas_store(&xas, new_page); |
f3f0e1d2 | 1686 | continue; |
f3f0e1d2 KS |
1687 | out_unlock: |
1688 | unlock_page(page); | |
1689 | put_page(page); | |
042a3082 | 1690 | goto xa_unlocked; |
f3f0e1d2 KS |
1691 | } |
1692 | ||
99cb0dbd SL |
1693 | if (is_shmem) |
1694 | __inc_node_page_state(new_page, NR_SHMEM_THPS); | |
09d91cda | 1695 | else { |
99cb0dbd | 1696 | __inc_node_page_state(new_page, NR_FILE_THPS); |
09d91cda SL |
1697 | filemap_nr_thps_inc(mapping); |
1698 | } | |
99cb0dbd | 1699 | |
042a3082 HD |
1700 | if (nr_none) { |
1701 | struct zone *zone = page_zone(new_page); | |
1702 | ||
1703 | __mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none); | |
99cb0dbd SL |
1704 | if (is_shmem) |
1705 | __mod_node_page_state(zone->zone_pgdat, | |
1706 | NR_SHMEM, nr_none); | |
042a3082 HD |
1707 | } |
1708 | ||
1709 | xa_locked: | |
1710 | xas_unlock_irq(&xas); | |
77da9389 | 1711 | xa_unlocked: |
042a3082 | 1712 | |
f3f0e1d2 | 1713 | if (result == SCAN_SUCCEED) { |
77da9389 | 1714 | struct page *page, *tmp; |
f3f0e1d2 KS |
1715 | |
1716 | /* | |
77da9389 MW |
1717 | * Replacing old pages with new one has succeeded, now we |
1718 | * need to copy the content and free the old pages. | |
f3f0e1d2 | 1719 | */ |
2af8ff29 | 1720 | index = start; |
f3f0e1d2 | 1721 | list_for_each_entry_safe(page, tmp, &pagelist, lru) { |
2af8ff29 HD |
1722 | while (index < page->index) { |
1723 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1724 | index++; | |
1725 | } | |
f3f0e1d2 KS |
1726 | copy_highpage(new_page + (page->index % HPAGE_PMD_NR), |
1727 | page); | |
1728 | list_del(&page->lru); | |
f3f0e1d2 | 1729 | page->mapping = NULL; |
042a3082 | 1730 | page_ref_unfreeze(page, 1); |
f3f0e1d2 KS |
1731 | ClearPageActive(page); |
1732 | ClearPageUnevictable(page); | |
042a3082 | 1733 | unlock_page(page); |
f3f0e1d2 | 1734 | put_page(page); |
2af8ff29 HD |
1735 | index++; |
1736 | } | |
1737 | while (index < end) { | |
1738 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1739 | index++; | |
f3f0e1d2 KS |
1740 | } |
1741 | ||
f3f0e1d2 | 1742 | SetPageUptodate(new_page); |
87c460a0 | 1743 | page_ref_add(new_page, HPAGE_PMD_NR - 1); |
f3f0e1d2 | 1744 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
99cb0dbd SL |
1745 | |
1746 | if (is_shmem) { | |
1747 | set_page_dirty(new_page); | |
1748 | lru_cache_add_anon(new_page); | |
1749 | } else { | |
1750 | lru_cache_add_file(new_page); | |
1751 | } | |
1ff9e6e1 | 1752 | count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1); |
f3f0e1d2 | 1753 | |
042a3082 HD |
1754 | /* |
1755 | * Remove pte page tables, so we can re-fault the page as huge. | |
1756 | */ | |
1757 | retract_page_tables(mapping, start); | |
f3f0e1d2 | 1758 | *hpage = NULL; |
87aa7529 YS |
1759 | |
1760 | khugepaged_pages_collapsed++; | |
f3f0e1d2 | 1761 | } else { |
77da9389 | 1762 | struct page *page; |
aaa52e34 | 1763 | |
77da9389 | 1764 | /* Something went wrong: roll back page cache changes */ |
77da9389 | 1765 | xas_lock_irq(&xas); |
aaa52e34 | 1766 | mapping->nrpages -= nr_none; |
99cb0dbd SL |
1767 | |
1768 | if (is_shmem) | |
1769 | shmem_uncharge(mapping->host, nr_none); | |
aaa52e34 | 1770 | |
77da9389 MW |
1771 | xas_set(&xas, start); |
1772 | xas_for_each(&xas, page, end - 1) { | |
f3f0e1d2 KS |
1773 | page = list_first_entry_or_null(&pagelist, |
1774 | struct page, lru); | |
77da9389 | 1775 | if (!page || xas.xa_index < page->index) { |
f3f0e1d2 KS |
1776 | if (!nr_none) |
1777 | break; | |
f3f0e1d2 | 1778 | nr_none--; |
59749e6c | 1779 | /* Put holes back where they were */ |
77da9389 | 1780 | xas_store(&xas, NULL); |
f3f0e1d2 KS |
1781 | continue; |
1782 | } | |
1783 | ||
77da9389 | 1784 | VM_BUG_ON_PAGE(page->index != xas.xa_index, page); |
f3f0e1d2 KS |
1785 | |
1786 | /* Unfreeze the page. */ | |
1787 | list_del(&page->lru); | |
1788 | page_ref_unfreeze(page, 2); | |
77da9389 MW |
1789 | xas_store(&xas, page); |
1790 | xas_pause(&xas); | |
1791 | xas_unlock_irq(&xas); | |
f3f0e1d2 | 1792 | unlock_page(page); |
042a3082 | 1793 | putback_lru_page(page); |
77da9389 | 1794 | xas_lock_irq(&xas); |
f3f0e1d2 KS |
1795 | } |
1796 | VM_BUG_ON(nr_none); | |
77da9389 | 1797 | xas_unlock_irq(&xas); |
f3f0e1d2 | 1798 | |
f3f0e1d2 | 1799 | mem_cgroup_cancel_charge(new_page, memcg, true); |
f3f0e1d2 KS |
1800 | new_page->mapping = NULL; |
1801 | } | |
042a3082 HD |
1802 | |
1803 | unlock_page(new_page); | |
f3f0e1d2 KS |
1804 | out: |
1805 | VM_BUG_ON(!list_empty(&pagelist)); | |
1806 | /* TODO: tracepoints */ | |
1807 | } | |
1808 | ||
579c571e SL |
1809 | static void khugepaged_scan_file(struct mm_struct *mm, |
1810 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
1811 | { |
1812 | struct page *page = NULL; | |
579c571e | 1813 | struct address_space *mapping = file->f_mapping; |
85b392db | 1814 | XA_STATE(xas, &mapping->i_pages, start); |
f3f0e1d2 KS |
1815 | int present, swap; |
1816 | int node = NUMA_NO_NODE; | |
1817 | int result = SCAN_SUCCEED; | |
1818 | ||
1819 | present = 0; | |
1820 | swap = 0; | |
1821 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1822 | rcu_read_lock(); | |
85b392db MW |
1823 | xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) { |
1824 | if (xas_retry(&xas, page)) | |
f3f0e1d2 | 1825 | continue; |
f3f0e1d2 | 1826 | |
85b392db | 1827 | if (xa_is_value(page)) { |
f3f0e1d2 KS |
1828 | if (++swap > khugepaged_max_ptes_swap) { |
1829 | result = SCAN_EXCEED_SWAP_PTE; | |
1830 | break; | |
1831 | } | |
1832 | continue; | |
1833 | } | |
1834 | ||
1835 | if (PageTransCompound(page)) { | |
1836 | result = SCAN_PAGE_COMPOUND; | |
1837 | break; | |
1838 | } | |
1839 | ||
1840 | node = page_to_nid(page); | |
1841 | if (khugepaged_scan_abort(node)) { | |
1842 | result = SCAN_SCAN_ABORT; | |
1843 | break; | |
1844 | } | |
1845 | khugepaged_node_load[node]++; | |
1846 | ||
1847 | if (!PageLRU(page)) { | |
1848 | result = SCAN_PAGE_LRU; | |
1849 | break; | |
1850 | } | |
1851 | ||
99cb0dbd SL |
1852 | if (page_count(page) != |
1853 | 1 + page_mapcount(page) + page_has_private(page)) { | |
f3f0e1d2 KS |
1854 | result = SCAN_PAGE_COUNT; |
1855 | break; | |
1856 | } | |
1857 | ||
1858 | /* | |
1859 | * We probably should check if the page is referenced here, but | |
1860 | * nobody would transfer pte_young() to PageReferenced() for us. | |
1861 | * And rmap walk here is just too costly... | |
1862 | */ | |
1863 | ||
1864 | present++; | |
1865 | ||
1866 | if (need_resched()) { | |
85b392db | 1867 | xas_pause(&xas); |
f3f0e1d2 | 1868 | cond_resched_rcu(); |
f3f0e1d2 KS |
1869 | } |
1870 | } | |
1871 | rcu_read_unlock(); | |
1872 | ||
1873 | if (result == SCAN_SUCCEED) { | |
1874 | if (present < HPAGE_PMD_NR - khugepaged_max_ptes_none) { | |
1875 | result = SCAN_EXCEED_NONE_PTE; | |
1876 | } else { | |
1877 | node = khugepaged_find_target_node(); | |
579c571e | 1878 | collapse_file(mm, file, start, hpage, node); |
f3f0e1d2 KS |
1879 | } |
1880 | } | |
1881 | ||
1882 | /* TODO: tracepoints */ | |
1883 | } | |
1884 | #else | |
579c571e SL |
1885 | static void khugepaged_scan_file(struct mm_struct *mm, |
1886 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
1887 | { |
1888 | BUILD_BUG(); | |
1889 | } | |
27e1f827 SL |
1890 | |
1891 | static int khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) | |
1892 | { | |
1893 | return 0; | |
1894 | } | |
f3f0e1d2 KS |
1895 | #endif |
1896 | ||
b46e756f KS |
1897 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, |
1898 | struct page **hpage) | |
1899 | __releases(&khugepaged_mm_lock) | |
1900 | __acquires(&khugepaged_mm_lock) | |
1901 | { | |
1902 | struct mm_slot *mm_slot; | |
1903 | struct mm_struct *mm; | |
1904 | struct vm_area_struct *vma; | |
1905 | int progress = 0; | |
1906 | ||
1907 | VM_BUG_ON(!pages); | |
35f3aa39 | 1908 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
1909 | |
1910 | if (khugepaged_scan.mm_slot) | |
1911 | mm_slot = khugepaged_scan.mm_slot; | |
1912 | else { | |
1913 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
1914 | struct mm_slot, mm_node); | |
1915 | khugepaged_scan.address = 0; | |
1916 | khugepaged_scan.mm_slot = mm_slot; | |
1917 | } | |
1918 | spin_unlock(&khugepaged_mm_lock); | |
27e1f827 | 1919 | khugepaged_collapse_pte_mapped_thps(mm_slot); |
b46e756f KS |
1920 | |
1921 | mm = mm_slot->mm; | |
3b454ad3 YS |
1922 | /* |
1923 | * Don't wait for semaphore (to avoid long wait times). Just move to | |
1924 | * the next mm on the list. | |
1925 | */ | |
1926 | vma = NULL; | |
1927 | if (unlikely(!down_read_trylock(&mm->mmap_sem))) | |
1928 | goto breakouterloop_mmap_sem; | |
1929 | if (likely(!khugepaged_test_exit(mm))) | |
b46e756f KS |
1930 | vma = find_vma(mm, khugepaged_scan.address); |
1931 | ||
1932 | progress++; | |
1933 | for (; vma; vma = vma->vm_next) { | |
1934 | unsigned long hstart, hend; | |
1935 | ||
1936 | cond_resched(); | |
1937 | if (unlikely(khugepaged_test_exit(mm))) { | |
1938 | progress++; | |
1939 | break; | |
1940 | } | |
50f8b92f | 1941 | if (!hugepage_vma_check(vma, vma->vm_flags)) { |
b46e756f KS |
1942 | skip: |
1943 | progress++; | |
1944 | continue; | |
1945 | } | |
1946 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
1947 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1948 | if (hstart >= hend) | |
1949 | goto skip; | |
1950 | if (khugepaged_scan.address > hend) | |
1951 | goto skip; | |
1952 | if (khugepaged_scan.address < hstart) | |
1953 | khugepaged_scan.address = hstart; | |
1954 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); | |
1955 | ||
1956 | while (khugepaged_scan.address < hend) { | |
1957 | int ret; | |
1958 | cond_resched(); | |
1959 | if (unlikely(khugepaged_test_exit(mm))) | |
1960 | goto breakouterloop; | |
1961 | ||
1962 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
1963 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
1964 | hend); | |
99cb0dbd | 1965 | if (IS_ENABLED(CONFIG_SHMEM) && vma->vm_file) { |
e496cf3d | 1966 | struct file *file; |
f3f0e1d2 KS |
1967 | pgoff_t pgoff = linear_page_index(vma, |
1968 | khugepaged_scan.address); | |
99cb0dbd SL |
1969 | |
1970 | if (shmem_file(vma->vm_file) | |
1971 | && !shmem_huge_enabled(vma)) | |
e496cf3d KS |
1972 | goto skip; |
1973 | file = get_file(vma->vm_file); | |
f3f0e1d2 KS |
1974 | up_read(&mm->mmap_sem); |
1975 | ret = 1; | |
579c571e | 1976 | khugepaged_scan_file(mm, file, pgoff, hpage); |
f3f0e1d2 KS |
1977 | fput(file); |
1978 | } else { | |
1979 | ret = khugepaged_scan_pmd(mm, vma, | |
1980 | khugepaged_scan.address, | |
1981 | hpage); | |
1982 | } | |
b46e756f KS |
1983 | /* move to next address */ |
1984 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
1985 | progress += HPAGE_PMD_NR; | |
1986 | if (ret) | |
1987 | /* we released mmap_sem so break loop */ | |
1988 | goto breakouterloop_mmap_sem; | |
1989 | if (progress >= pages) | |
1990 | goto breakouterloop; | |
1991 | } | |
1992 | } | |
1993 | breakouterloop: | |
1994 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
1995 | breakouterloop_mmap_sem: | |
1996 | ||
1997 | spin_lock(&khugepaged_mm_lock); | |
1998 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); | |
1999 | /* | |
2000 | * Release the current mm_slot if this mm is about to die, or | |
2001 | * if we scanned all vmas of this mm. | |
2002 | */ | |
2003 | if (khugepaged_test_exit(mm) || !vma) { | |
2004 | /* | |
2005 | * Make sure that if mm_users is reaching zero while | |
2006 | * khugepaged runs here, khugepaged_exit will find | |
2007 | * mm_slot not pointing to the exiting mm. | |
2008 | */ | |
2009 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2010 | khugepaged_scan.mm_slot = list_entry( | |
2011 | mm_slot->mm_node.next, | |
2012 | struct mm_slot, mm_node); | |
2013 | khugepaged_scan.address = 0; | |
2014 | } else { | |
2015 | khugepaged_scan.mm_slot = NULL; | |
2016 | khugepaged_full_scans++; | |
2017 | } | |
2018 | ||
2019 | collect_mm_slot(mm_slot); | |
2020 | } | |
2021 | ||
2022 | return progress; | |
2023 | } | |
2024 | ||
2025 | static int khugepaged_has_work(void) | |
2026 | { | |
2027 | return !list_empty(&khugepaged_scan.mm_head) && | |
2028 | khugepaged_enabled(); | |
2029 | } | |
2030 | ||
2031 | static int khugepaged_wait_event(void) | |
2032 | { | |
2033 | return !list_empty(&khugepaged_scan.mm_head) || | |
2034 | kthread_should_stop(); | |
2035 | } | |
2036 | ||
2037 | static void khugepaged_do_scan(void) | |
2038 | { | |
2039 | struct page *hpage = NULL; | |
2040 | unsigned int progress = 0, pass_through_head = 0; | |
2041 | unsigned int pages = khugepaged_pages_to_scan; | |
2042 | bool wait = true; | |
2043 | ||
2044 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2045 | ||
2046 | while (progress < pages) { | |
2047 | if (!khugepaged_prealloc_page(&hpage, &wait)) | |
2048 | break; | |
2049 | ||
2050 | cond_resched(); | |
2051 | ||
2052 | if (unlikely(kthread_should_stop() || try_to_freeze())) | |
2053 | break; | |
2054 | ||
2055 | spin_lock(&khugepaged_mm_lock); | |
2056 | if (!khugepaged_scan.mm_slot) | |
2057 | pass_through_head++; | |
2058 | if (khugepaged_has_work() && | |
2059 | pass_through_head < 2) | |
2060 | progress += khugepaged_scan_mm_slot(pages - progress, | |
2061 | &hpage); | |
2062 | else | |
2063 | progress = pages; | |
2064 | spin_unlock(&khugepaged_mm_lock); | |
2065 | } | |
2066 | ||
2067 | if (!IS_ERR_OR_NULL(hpage)) | |
2068 | put_page(hpage); | |
2069 | } | |
2070 | ||
2071 | static bool khugepaged_should_wakeup(void) | |
2072 | { | |
2073 | return kthread_should_stop() || | |
2074 | time_after_eq(jiffies, khugepaged_sleep_expire); | |
2075 | } | |
2076 | ||
2077 | static void khugepaged_wait_work(void) | |
2078 | { | |
2079 | if (khugepaged_has_work()) { | |
2080 | const unsigned long scan_sleep_jiffies = | |
2081 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs); | |
2082 | ||
2083 | if (!scan_sleep_jiffies) | |
2084 | return; | |
2085 | ||
2086 | khugepaged_sleep_expire = jiffies + scan_sleep_jiffies; | |
2087 | wait_event_freezable_timeout(khugepaged_wait, | |
2088 | khugepaged_should_wakeup(), | |
2089 | scan_sleep_jiffies); | |
2090 | return; | |
2091 | } | |
2092 | ||
2093 | if (khugepaged_enabled()) | |
2094 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2095 | } | |
2096 | ||
2097 | static int khugepaged(void *none) | |
2098 | { | |
2099 | struct mm_slot *mm_slot; | |
2100 | ||
2101 | set_freezable(); | |
2102 | set_user_nice(current, MAX_NICE); | |
2103 | ||
2104 | while (!kthread_should_stop()) { | |
2105 | khugepaged_do_scan(); | |
2106 | khugepaged_wait_work(); | |
2107 | } | |
2108 | ||
2109 | spin_lock(&khugepaged_mm_lock); | |
2110 | mm_slot = khugepaged_scan.mm_slot; | |
2111 | khugepaged_scan.mm_slot = NULL; | |
2112 | if (mm_slot) | |
2113 | collect_mm_slot(mm_slot); | |
2114 | spin_unlock(&khugepaged_mm_lock); | |
2115 | return 0; | |
2116 | } | |
2117 | ||
2118 | static void set_recommended_min_free_kbytes(void) | |
2119 | { | |
2120 | struct zone *zone; | |
2121 | int nr_zones = 0; | |
2122 | unsigned long recommended_min; | |
2123 | ||
b7d349c7 JK |
2124 | for_each_populated_zone(zone) { |
2125 | /* | |
2126 | * We don't need to worry about fragmentation of | |
2127 | * ZONE_MOVABLE since it only has movable pages. | |
2128 | */ | |
2129 | if (zone_idx(zone) > gfp_zone(GFP_USER)) | |
2130 | continue; | |
2131 | ||
b46e756f | 2132 | nr_zones++; |
b7d349c7 | 2133 | } |
b46e756f KS |
2134 | |
2135 | /* Ensure 2 pageblocks are free to assist fragmentation avoidance */ | |
2136 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
2137 | ||
2138 | /* | |
2139 | * Make sure that on average at least two pageblocks are almost free | |
2140 | * of another type, one for a migratetype to fall back to and a | |
2141 | * second to avoid subsequent fallbacks of other types There are 3 | |
2142 | * MIGRATE_TYPES we care about. | |
2143 | */ | |
2144 | recommended_min += pageblock_nr_pages * nr_zones * | |
2145 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
2146 | ||
2147 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
2148 | recommended_min = min(recommended_min, | |
2149 | (unsigned long) nr_free_buffer_pages() / 20); | |
2150 | recommended_min <<= (PAGE_SHIFT-10); | |
2151 | ||
2152 | if (recommended_min > min_free_kbytes) { | |
2153 | if (user_min_free_kbytes >= 0) | |
2154 | pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n", | |
2155 | min_free_kbytes, recommended_min); | |
2156 | ||
2157 | min_free_kbytes = recommended_min; | |
2158 | } | |
2159 | setup_per_zone_wmarks(); | |
2160 | } | |
2161 | ||
2162 | int start_stop_khugepaged(void) | |
2163 | { | |
2164 | static struct task_struct *khugepaged_thread __read_mostly; | |
2165 | static DEFINE_MUTEX(khugepaged_mutex); | |
2166 | int err = 0; | |
2167 | ||
2168 | mutex_lock(&khugepaged_mutex); | |
2169 | if (khugepaged_enabled()) { | |
2170 | if (!khugepaged_thread) | |
2171 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
2172 | "khugepaged"); | |
2173 | if (IS_ERR(khugepaged_thread)) { | |
2174 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); | |
2175 | err = PTR_ERR(khugepaged_thread); | |
2176 | khugepaged_thread = NULL; | |
2177 | goto fail; | |
2178 | } | |
2179 | ||
2180 | if (!list_empty(&khugepaged_scan.mm_head)) | |
2181 | wake_up_interruptible(&khugepaged_wait); | |
2182 | ||
2183 | set_recommended_min_free_kbytes(); | |
2184 | } else if (khugepaged_thread) { | |
2185 | kthread_stop(khugepaged_thread); | |
2186 | khugepaged_thread = NULL; | |
2187 | } | |
2188 | fail: | |
2189 | mutex_unlock(&khugepaged_mutex); | |
2190 | return err; | |
2191 | } |