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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, | |
b46e756f KS |
51 | }; |
52 | ||
53 | #define CREATE_TRACE_POINTS | |
54 | #include <trace/events/huge_memory.h> | |
55 | ||
56 | /* default scan 8*512 pte (or vmas) every 30 second */ | |
57 | static unsigned int khugepaged_pages_to_scan __read_mostly; | |
58 | static unsigned int khugepaged_pages_collapsed; | |
59 | static unsigned int khugepaged_full_scans; | |
60 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
61 | /* during fragmentation poll the hugepage allocator once every minute */ | |
62 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
63 | static unsigned long khugepaged_sleep_expire; | |
64 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
65 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
66 | /* | |
67 | * default collapse hugepages if there is at least one pte mapped like | |
68 | * it would have happened if the vma was large enough during page | |
69 | * fault. | |
70 | */ | |
71 | static unsigned int khugepaged_max_ptes_none __read_mostly; | |
72 | static unsigned int khugepaged_max_ptes_swap __read_mostly; | |
73 | ||
74 | #define MM_SLOTS_HASH_BITS 10 | |
75 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
76 | ||
77 | static struct kmem_cache *mm_slot_cache __read_mostly; | |
78 | ||
79 | /** | |
80 | * struct mm_slot - hash lookup from mm to mm_slot | |
81 | * @hash: hash collision list | |
82 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
83 | * @mm: the mm that this information is valid for | |
84 | */ | |
85 | struct mm_slot { | |
86 | struct hlist_node hash; | |
87 | struct list_head mm_node; | |
88 | struct mm_struct *mm; | |
89 | }; | |
90 | ||
91 | /** | |
92 | * struct khugepaged_scan - cursor for scanning | |
93 | * @mm_head: the head of the mm list to scan | |
94 | * @mm_slot: the current mm_slot we are scanning | |
95 | * @address: the next address inside that to be scanned | |
96 | * | |
97 | * There is only the one khugepaged_scan instance of this cursor structure. | |
98 | */ | |
99 | struct khugepaged_scan { | |
100 | struct list_head mm_head; | |
101 | struct mm_slot *mm_slot; | |
102 | unsigned long address; | |
103 | }; | |
104 | ||
105 | static struct khugepaged_scan khugepaged_scan = { | |
106 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), | |
107 | }; | |
108 | ||
e1465d12 | 109 | #ifdef CONFIG_SYSFS |
b46e756f KS |
110 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, |
111 | struct kobj_attribute *attr, | |
112 | char *buf) | |
113 | { | |
114 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
115 | } | |
116 | ||
117 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
118 | struct kobj_attribute *attr, | |
119 | const char *buf, size_t count) | |
120 | { | |
121 | unsigned long msecs; | |
122 | int err; | |
123 | ||
124 | err = kstrtoul(buf, 10, &msecs); | |
125 | if (err || msecs > UINT_MAX) | |
126 | return -EINVAL; | |
127 | ||
128 | khugepaged_scan_sleep_millisecs = msecs; | |
129 | khugepaged_sleep_expire = 0; | |
130 | wake_up_interruptible(&khugepaged_wait); | |
131 | ||
132 | return count; | |
133 | } | |
134 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
135 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
136 | scan_sleep_millisecs_store); | |
137 | ||
138 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
139 | struct kobj_attribute *attr, | |
140 | char *buf) | |
141 | { | |
142 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
143 | } | |
144 | ||
145 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
146 | struct kobj_attribute *attr, | |
147 | const char *buf, size_t count) | |
148 | { | |
149 | unsigned long msecs; | |
150 | int err; | |
151 | ||
152 | err = kstrtoul(buf, 10, &msecs); | |
153 | if (err || msecs > UINT_MAX) | |
154 | return -EINVAL; | |
155 | ||
156 | khugepaged_alloc_sleep_millisecs = msecs; | |
157 | khugepaged_sleep_expire = 0; | |
158 | wake_up_interruptible(&khugepaged_wait); | |
159 | ||
160 | return count; | |
161 | } | |
162 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
163 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
164 | alloc_sleep_millisecs_store); | |
165 | ||
166 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
167 | struct kobj_attribute *attr, | |
168 | char *buf) | |
169 | { | |
170 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
171 | } | |
172 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
173 | struct kobj_attribute *attr, | |
174 | const char *buf, size_t count) | |
175 | { | |
176 | int err; | |
177 | unsigned long pages; | |
178 | ||
179 | err = kstrtoul(buf, 10, &pages); | |
180 | if (err || !pages || pages > UINT_MAX) | |
181 | return -EINVAL; | |
182 | ||
183 | khugepaged_pages_to_scan = pages; | |
184 | ||
185 | return count; | |
186 | } | |
187 | static struct kobj_attribute pages_to_scan_attr = | |
188 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
189 | pages_to_scan_store); | |
190 | ||
191 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
192 | struct kobj_attribute *attr, | |
193 | char *buf) | |
194 | { | |
195 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
196 | } | |
197 | static struct kobj_attribute pages_collapsed_attr = | |
198 | __ATTR_RO(pages_collapsed); | |
199 | ||
200 | static ssize_t full_scans_show(struct kobject *kobj, | |
201 | struct kobj_attribute *attr, | |
202 | char *buf) | |
203 | { | |
204 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
205 | } | |
206 | static struct kobj_attribute full_scans_attr = | |
207 | __ATTR_RO(full_scans); | |
208 | ||
209 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
210 | struct kobj_attribute *attr, char *buf) | |
211 | { | |
212 | return single_hugepage_flag_show(kobj, attr, buf, | |
213 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
214 | } | |
215 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
216 | struct kobj_attribute *attr, | |
217 | const char *buf, size_t count) | |
218 | { | |
219 | return single_hugepage_flag_store(kobj, attr, buf, count, | |
220 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
221 | } | |
222 | static struct kobj_attribute khugepaged_defrag_attr = | |
223 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
224 | khugepaged_defrag_store); | |
225 | ||
226 | /* | |
227 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
228 | * any unmapped ptes in turn potentially increasing the memory | |
229 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
230 | * reduce the available free memory in the system as it | |
231 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
232 | * free memory in the system during the khugepaged scan. | |
233 | */ | |
234 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
235 | struct kobj_attribute *attr, | |
236 | char *buf) | |
237 | { | |
238 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
239 | } | |
240 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
241 | struct kobj_attribute *attr, | |
242 | const char *buf, size_t count) | |
243 | { | |
244 | int err; | |
245 | unsigned long max_ptes_none; | |
246 | ||
247 | err = kstrtoul(buf, 10, &max_ptes_none); | |
248 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
249 | return -EINVAL; | |
250 | ||
251 | khugepaged_max_ptes_none = max_ptes_none; | |
252 | ||
253 | return count; | |
254 | } | |
255 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
256 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
257 | khugepaged_max_ptes_none_store); | |
258 | ||
259 | static ssize_t khugepaged_max_ptes_swap_show(struct kobject *kobj, | |
260 | struct kobj_attribute *attr, | |
261 | char *buf) | |
262 | { | |
263 | return sprintf(buf, "%u\n", khugepaged_max_ptes_swap); | |
264 | } | |
265 | ||
266 | static ssize_t khugepaged_max_ptes_swap_store(struct kobject *kobj, | |
267 | struct kobj_attribute *attr, | |
268 | const char *buf, size_t count) | |
269 | { | |
270 | int err; | |
271 | unsigned long max_ptes_swap; | |
272 | ||
273 | err = kstrtoul(buf, 10, &max_ptes_swap); | |
274 | if (err || max_ptes_swap > HPAGE_PMD_NR-1) | |
275 | return -EINVAL; | |
276 | ||
277 | khugepaged_max_ptes_swap = max_ptes_swap; | |
278 | ||
279 | return count; | |
280 | } | |
281 | ||
282 | static struct kobj_attribute khugepaged_max_ptes_swap_attr = | |
283 | __ATTR(max_ptes_swap, 0644, khugepaged_max_ptes_swap_show, | |
284 | khugepaged_max_ptes_swap_store); | |
285 | ||
286 | static struct attribute *khugepaged_attr[] = { | |
287 | &khugepaged_defrag_attr.attr, | |
288 | &khugepaged_max_ptes_none_attr.attr, | |
289 | &pages_to_scan_attr.attr, | |
290 | &pages_collapsed_attr.attr, | |
291 | &full_scans_attr.attr, | |
292 | &scan_sleep_millisecs_attr.attr, | |
293 | &alloc_sleep_millisecs_attr.attr, | |
294 | &khugepaged_max_ptes_swap_attr.attr, | |
295 | NULL, | |
296 | }; | |
297 | ||
298 | struct attribute_group khugepaged_attr_group = { | |
299 | .attrs = khugepaged_attr, | |
300 | .name = "khugepaged", | |
301 | }; | |
e1465d12 | 302 | #endif /* CONFIG_SYSFS */ |
b46e756f | 303 | |
f3f0e1d2 | 304 | #define VM_NO_KHUGEPAGED (VM_SPECIAL | VM_HUGETLB) |
b46e756f KS |
305 | |
306 | int hugepage_madvise(struct vm_area_struct *vma, | |
307 | unsigned long *vm_flags, int advice) | |
308 | { | |
309 | switch (advice) { | |
310 | case MADV_HUGEPAGE: | |
311 | #ifdef CONFIG_S390 | |
312 | /* | |
313 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
314 | * can't handle this properly after s390_enable_sie, so we simply | |
315 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
316 | */ | |
317 | if (mm_has_pgste(vma->vm_mm)) | |
318 | return 0; | |
319 | #endif | |
320 | *vm_flags &= ~VM_NOHUGEPAGE; | |
321 | *vm_flags |= VM_HUGEPAGE; | |
322 | /* | |
323 | * If the vma become good for khugepaged to scan, | |
324 | * register it here without waiting a page fault that | |
325 | * may not happen any time soon. | |
326 | */ | |
327 | if (!(*vm_flags & VM_NO_KHUGEPAGED) && | |
328 | khugepaged_enter_vma_merge(vma, *vm_flags)) | |
329 | return -ENOMEM; | |
330 | break; | |
331 | case MADV_NOHUGEPAGE: | |
332 | *vm_flags &= ~VM_HUGEPAGE; | |
333 | *vm_flags |= VM_NOHUGEPAGE; | |
334 | /* | |
335 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
336 | * this vma even if we leave the mm registered in khugepaged if | |
337 | * it got registered before VM_NOHUGEPAGE was set. | |
338 | */ | |
339 | break; | |
340 | } | |
341 | ||
342 | return 0; | |
343 | } | |
344 | ||
345 | int __init khugepaged_init(void) | |
346 | { | |
347 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
348 | sizeof(struct mm_slot), | |
349 | __alignof__(struct mm_slot), 0, NULL); | |
350 | if (!mm_slot_cache) | |
351 | return -ENOMEM; | |
352 | ||
353 | khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; | |
354 | khugepaged_max_ptes_none = HPAGE_PMD_NR - 1; | |
355 | khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8; | |
356 | ||
357 | return 0; | |
358 | } | |
359 | ||
360 | void __init khugepaged_destroy(void) | |
361 | { | |
362 | kmem_cache_destroy(mm_slot_cache); | |
363 | } | |
364 | ||
365 | static inline struct mm_slot *alloc_mm_slot(void) | |
366 | { | |
367 | if (!mm_slot_cache) /* initialization failed */ | |
368 | return NULL; | |
369 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
370 | } | |
371 | ||
372 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
373 | { | |
374 | kmem_cache_free(mm_slot_cache, mm_slot); | |
375 | } | |
376 | ||
377 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
378 | { | |
379 | struct mm_slot *mm_slot; | |
380 | ||
381 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) | |
382 | if (mm == mm_slot->mm) | |
383 | return mm_slot; | |
384 | ||
385 | return NULL; | |
386 | } | |
387 | ||
388 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
389 | struct mm_slot *mm_slot) | |
390 | { | |
391 | mm_slot->mm = mm; | |
392 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); | |
393 | } | |
394 | ||
395 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
396 | { | |
397 | return atomic_read(&mm->mm_users) == 0; | |
398 | } | |
399 | ||
400 | int __khugepaged_enter(struct mm_struct *mm) | |
401 | { | |
402 | struct mm_slot *mm_slot; | |
403 | int wakeup; | |
404 | ||
405 | mm_slot = alloc_mm_slot(); | |
406 | if (!mm_slot) | |
407 | return -ENOMEM; | |
408 | ||
409 | /* __khugepaged_exit() must not run from under us */ | |
410 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); | |
411 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { | |
412 | free_mm_slot(mm_slot); | |
413 | return 0; | |
414 | } | |
415 | ||
416 | spin_lock(&khugepaged_mm_lock); | |
417 | insert_to_mm_slots_hash(mm, mm_slot); | |
418 | /* | |
419 | * Insert just behind the scanning cursor, to let the area settle | |
420 | * down a little. | |
421 | */ | |
422 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
423 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
424 | spin_unlock(&khugepaged_mm_lock); | |
425 | ||
f1f10076 | 426 | mmgrab(mm); |
b46e756f KS |
427 | if (wakeup) |
428 | wake_up_interruptible(&khugepaged_wait); | |
429 | ||
430 | return 0; | |
431 | } | |
432 | ||
433 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, | |
434 | unsigned long vm_flags) | |
435 | { | |
436 | unsigned long hstart, hend; | |
437 | if (!vma->anon_vma) | |
438 | /* | |
439 | * Not yet faulted in so we will register later in the | |
440 | * page fault if needed. | |
441 | */ | |
442 | return 0; | |
443 | if (vma->vm_ops || (vm_flags & VM_NO_KHUGEPAGED)) | |
444 | /* khugepaged not yet working on file or special mappings */ | |
445 | return 0; | |
446 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
447 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
448 | if (hstart < hend) | |
449 | return khugepaged_enter(vma, vm_flags); | |
450 | return 0; | |
451 | } | |
452 | ||
453 | void __khugepaged_exit(struct mm_struct *mm) | |
454 | { | |
455 | struct mm_slot *mm_slot; | |
456 | int free = 0; | |
457 | ||
458 | spin_lock(&khugepaged_mm_lock); | |
459 | mm_slot = get_mm_slot(mm); | |
460 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
461 | hash_del(&mm_slot->hash); | |
462 | list_del(&mm_slot->mm_node); | |
463 | free = 1; | |
464 | } | |
465 | spin_unlock(&khugepaged_mm_lock); | |
466 | ||
467 | if (free) { | |
468 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
469 | free_mm_slot(mm_slot); | |
470 | mmdrop(mm); | |
471 | } else if (mm_slot) { | |
472 | /* | |
473 | * This is required to serialize against | |
474 | * khugepaged_test_exit() (which is guaranteed to run | |
475 | * under mmap sem read mode). Stop here (after we | |
476 | * return all pagetables will be destroyed) until | |
477 | * khugepaged has finished working on the pagetables | |
478 | * under the mmap_sem. | |
479 | */ | |
480 | down_write(&mm->mmap_sem); | |
481 | up_write(&mm->mmap_sem); | |
482 | } | |
483 | } | |
484 | ||
485 | static void release_pte_page(struct page *page) | |
486 | { | |
d44d363f | 487 | dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); |
b46e756f KS |
488 | unlock_page(page); |
489 | putback_lru_page(page); | |
490 | } | |
491 | ||
492 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
493 | { | |
494 | while (--_pte >= pte) { | |
495 | pte_t pteval = *_pte; | |
496 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) | |
497 | release_pte_page(pte_page(pteval)); | |
498 | } | |
499 | } | |
500 | ||
501 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, | |
502 | unsigned long address, | |
503 | pte_t *pte) | |
504 | { | |
505 | struct page *page = NULL; | |
506 | pte_t *_pte; | |
0db501f7 EA |
507 | int none_or_zero = 0, result = 0, referenced = 0; |
508 | bool writable = false; | |
b46e756f KS |
509 | |
510 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
511 | _pte++, address += PAGE_SIZE) { | |
512 | pte_t pteval = *_pte; | |
513 | if (pte_none(pteval) || (pte_present(pteval) && | |
514 | is_zero_pfn(pte_pfn(pteval)))) { | |
515 | if (!userfaultfd_armed(vma) && | |
516 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
517 | continue; | |
518 | } else { | |
519 | result = SCAN_EXCEED_NONE_PTE; | |
520 | goto out; | |
521 | } | |
522 | } | |
523 | if (!pte_present(pteval)) { | |
524 | result = SCAN_PTE_NON_PRESENT; | |
525 | goto out; | |
526 | } | |
527 | page = vm_normal_page(vma, address, pteval); | |
528 | if (unlikely(!page)) { | |
529 | result = SCAN_PAGE_NULL; | |
530 | goto out; | |
531 | } | |
532 | ||
533 | VM_BUG_ON_PAGE(PageCompound(page), page); | |
534 | VM_BUG_ON_PAGE(!PageAnon(page), page); | |
b46e756f KS |
535 | |
536 | /* | |
537 | * We can do it before isolate_lru_page because the | |
538 | * page can't be freed from under us. NOTE: PG_lock | |
539 | * is needed to serialize against split_huge_page | |
540 | * when invoked from the VM. | |
541 | */ | |
542 | if (!trylock_page(page)) { | |
543 | result = SCAN_PAGE_LOCK; | |
544 | goto out; | |
545 | } | |
546 | ||
547 | /* | |
548 | * cannot use mapcount: can't collapse if there's a gup pin. | |
549 | * The page must only be referenced by the scanned process | |
550 | * and page swap cache. | |
551 | */ | |
2948be5a | 552 | if (page_count(page) != 1 + PageSwapCache(page)) { |
b46e756f KS |
553 | unlock_page(page); |
554 | result = SCAN_PAGE_COUNT; | |
555 | goto out; | |
556 | } | |
557 | if (pte_write(pteval)) { | |
558 | writable = true; | |
559 | } else { | |
560 | if (PageSwapCache(page) && | |
561 | !reuse_swap_page(page, NULL)) { | |
562 | unlock_page(page); | |
563 | result = SCAN_SWAP_CACHE_PAGE; | |
564 | goto out; | |
565 | } | |
566 | /* | |
567 | * Page is not in the swap cache. It can be collapsed | |
568 | * into a THP. | |
569 | */ | |
570 | } | |
571 | ||
572 | /* | |
573 | * Isolate the page to avoid collapsing an hugepage | |
574 | * currently in use by the VM. | |
575 | */ | |
576 | if (isolate_lru_page(page)) { | |
577 | unlock_page(page); | |
578 | result = SCAN_DEL_PAGE_LRU; | |
579 | goto out; | |
580 | } | |
d44d363f SL |
581 | inc_node_page_state(page, |
582 | NR_ISOLATED_ANON + page_is_file_cache(page)); | |
b46e756f KS |
583 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
584 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
585 | ||
0db501f7 | 586 | /* There should be enough young pte to collapse the page */ |
b46e756f KS |
587 | if (pte_young(pteval) || |
588 | page_is_young(page) || PageReferenced(page) || | |
589 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 590 | referenced++; |
b46e756f KS |
591 | } |
592 | if (likely(writable)) { | |
593 | if (likely(referenced)) { | |
594 | result = SCAN_SUCCEED; | |
595 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, | |
596 | referenced, writable, result); | |
597 | return 1; | |
598 | } | |
599 | } else { | |
600 | result = SCAN_PAGE_RO; | |
601 | } | |
602 | ||
603 | out: | |
604 | release_pte_pages(pte, _pte); | |
605 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, | |
606 | referenced, writable, result); | |
607 | return 0; | |
608 | } | |
609 | ||
610 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
611 | struct vm_area_struct *vma, | |
612 | unsigned long address, | |
613 | spinlock_t *ptl) | |
614 | { | |
615 | pte_t *_pte; | |
338a16ba DR |
616 | for (_pte = pte; _pte < pte + HPAGE_PMD_NR; |
617 | _pte++, page++, address += PAGE_SIZE) { | |
b46e756f KS |
618 | pte_t pteval = *_pte; |
619 | struct page *src_page; | |
620 | ||
621 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
622 | clear_user_highpage(page, address); | |
623 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
624 | if (is_zero_pfn(pte_pfn(pteval))) { | |
625 | /* | |
626 | * ptl mostly unnecessary. | |
627 | */ | |
628 | spin_lock(ptl); | |
629 | /* | |
630 | * paravirt calls inside pte_clear here are | |
631 | * superfluous. | |
632 | */ | |
633 | pte_clear(vma->vm_mm, address, _pte); | |
634 | spin_unlock(ptl); | |
635 | } | |
636 | } else { | |
637 | src_page = pte_page(pteval); | |
638 | copy_user_highpage(page, src_page, address, vma); | |
639 | VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page); | |
640 | release_pte_page(src_page); | |
641 | /* | |
642 | * ptl mostly unnecessary, but preempt has to | |
643 | * be disabled to update the per-cpu stats | |
644 | * inside page_remove_rmap(). | |
645 | */ | |
646 | spin_lock(ptl); | |
647 | /* | |
648 | * paravirt calls inside pte_clear here are | |
649 | * superfluous. | |
650 | */ | |
651 | pte_clear(vma->vm_mm, address, _pte); | |
652 | page_remove_rmap(src_page, false); | |
653 | spin_unlock(ptl); | |
654 | free_page_and_swap_cache(src_page); | |
655 | } | |
b46e756f KS |
656 | } |
657 | } | |
658 | ||
659 | static void khugepaged_alloc_sleep(void) | |
660 | { | |
661 | DEFINE_WAIT(wait); | |
662 | ||
663 | add_wait_queue(&khugepaged_wait, &wait); | |
664 | freezable_schedule_timeout_interruptible( | |
665 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
666 | remove_wait_queue(&khugepaged_wait, &wait); | |
667 | } | |
668 | ||
669 | static int khugepaged_node_load[MAX_NUMNODES]; | |
670 | ||
671 | static bool khugepaged_scan_abort(int nid) | |
672 | { | |
673 | int i; | |
674 | ||
675 | /* | |
a5f5f91d | 676 | * If node_reclaim_mode is disabled, then no extra effort is made to |
b46e756f KS |
677 | * allocate memory locally. |
678 | */ | |
a5f5f91d | 679 | if (!node_reclaim_mode) |
b46e756f KS |
680 | return false; |
681 | ||
682 | /* If there is a count for this node already, it must be acceptable */ | |
683 | if (khugepaged_node_load[nid]) | |
684 | return false; | |
685 | ||
686 | for (i = 0; i < MAX_NUMNODES; i++) { | |
687 | if (!khugepaged_node_load[i]) | |
688 | continue; | |
689 | if (node_distance(nid, i) > RECLAIM_DISTANCE) | |
690 | return true; | |
691 | } | |
692 | return false; | |
693 | } | |
694 | ||
695 | /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */ | |
696 | static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void) | |
697 | { | |
25160354 | 698 | return khugepaged_defrag() ? GFP_TRANSHUGE : GFP_TRANSHUGE_LIGHT; |
b46e756f KS |
699 | } |
700 | ||
701 | #ifdef CONFIG_NUMA | |
702 | static int khugepaged_find_target_node(void) | |
703 | { | |
704 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
705 | int nid, target_node = 0, max_value = 0; | |
706 | ||
707 | /* find first node with max normal pages hit */ | |
708 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
709 | if (khugepaged_node_load[nid] > max_value) { | |
710 | max_value = khugepaged_node_load[nid]; | |
711 | target_node = nid; | |
712 | } | |
713 | ||
714 | /* do some balance if several nodes have the same hit record */ | |
715 | if (target_node <= last_khugepaged_target_node) | |
716 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
717 | nid++) | |
718 | if (max_value == khugepaged_node_load[nid]) { | |
719 | target_node = nid; | |
720 | break; | |
721 | } | |
722 | ||
723 | last_khugepaged_target_node = target_node; | |
724 | return target_node; | |
725 | } | |
726 | ||
727 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
728 | { | |
729 | if (IS_ERR(*hpage)) { | |
730 | if (!*wait) | |
731 | return false; | |
732 | ||
733 | *wait = false; | |
734 | *hpage = NULL; | |
735 | khugepaged_alloc_sleep(); | |
736 | } else if (*hpage) { | |
737 | put_page(*hpage); | |
738 | *hpage = NULL; | |
739 | } | |
740 | ||
741 | return true; | |
742 | } | |
743 | ||
744 | static struct page * | |
988ddb71 | 745 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f KS |
746 | { |
747 | VM_BUG_ON_PAGE(*hpage, *hpage); | |
748 | ||
b46e756f KS |
749 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); |
750 | if (unlikely(!*hpage)) { | |
751 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
752 | *hpage = ERR_PTR(-ENOMEM); | |
753 | return NULL; | |
754 | } | |
755 | ||
756 | prep_transhuge_page(*hpage); | |
757 | count_vm_event(THP_COLLAPSE_ALLOC); | |
758 | return *hpage; | |
759 | } | |
760 | #else | |
761 | static int khugepaged_find_target_node(void) | |
762 | { | |
763 | return 0; | |
764 | } | |
765 | ||
766 | static inline struct page *alloc_khugepaged_hugepage(void) | |
767 | { | |
768 | struct page *page; | |
769 | ||
770 | page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(), | |
771 | HPAGE_PMD_ORDER); | |
772 | if (page) | |
773 | prep_transhuge_page(page); | |
774 | return page; | |
775 | } | |
776 | ||
777 | static struct page *khugepaged_alloc_hugepage(bool *wait) | |
778 | { | |
779 | struct page *hpage; | |
780 | ||
781 | do { | |
782 | hpage = alloc_khugepaged_hugepage(); | |
783 | if (!hpage) { | |
784 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
785 | if (!*wait) | |
786 | return NULL; | |
787 | ||
788 | *wait = false; | |
789 | khugepaged_alloc_sleep(); | |
790 | } else | |
791 | count_vm_event(THP_COLLAPSE_ALLOC); | |
792 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
793 | ||
794 | return hpage; | |
795 | } | |
796 | ||
797 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
798 | { | |
799 | if (!*hpage) | |
800 | *hpage = khugepaged_alloc_hugepage(wait); | |
801 | ||
802 | if (unlikely(!*hpage)) | |
803 | return false; | |
804 | ||
805 | return true; | |
806 | } | |
807 | ||
808 | static struct page * | |
988ddb71 | 809 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f | 810 | { |
b46e756f KS |
811 | VM_BUG_ON(!*hpage); |
812 | ||
813 | return *hpage; | |
814 | } | |
815 | #endif | |
816 | ||
817 | static bool hugepage_vma_check(struct vm_area_struct *vma) | |
818 | { | |
819 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || | |
18600332 MH |
820 | (vma->vm_flags & VM_NOHUGEPAGE) || |
821 | test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) | |
b46e756f | 822 | return false; |
f3f0e1d2 | 823 | if (shmem_file(vma->vm_file)) { |
e496cf3d KS |
824 | if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) |
825 | return false; | |
f3f0e1d2 KS |
826 | return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, |
827 | HPAGE_PMD_NR); | |
828 | } | |
b46e756f KS |
829 | if (!vma->anon_vma || vma->vm_ops) |
830 | return false; | |
831 | if (is_vma_temporary_stack(vma)) | |
832 | return false; | |
833 | return !(vma->vm_flags & VM_NO_KHUGEPAGED); | |
834 | } | |
835 | ||
836 | /* | |
837 | * If mmap_sem temporarily dropped, revalidate vma | |
838 | * before taking mmap_sem. | |
839 | * Return 0 if succeeds, otherwise return none-zero | |
840 | * value (scan code). | |
841 | */ | |
842 | ||
c131f751 KS |
843 | static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, |
844 | struct vm_area_struct **vmap) | |
b46e756f KS |
845 | { |
846 | struct vm_area_struct *vma; | |
847 | unsigned long hstart, hend; | |
848 | ||
849 | if (unlikely(khugepaged_test_exit(mm))) | |
850 | return SCAN_ANY_PROCESS; | |
851 | ||
c131f751 | 852 | *vmap = vma = find_vma(mm, address); |
b46e756f KS |
853 | if (!vma) |
854 | return SCAN_VMA_NULL; | |
855 | ||
856 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
857 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
858 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
859 | return SCAN_ADDRESS_RANGE; | |
860 | if (!hugepage_vma_check(vma)) | |
861 | return SCAN_VMA_CHECK; | |
862 | return 0; | |
863 | } | |
864 | ||
865 | /* | |
866 | * Bring missing pages in from swap, to complete THP collapse. | |
867 | * Only done if khugepaged_scan_pmd believes it is worthwhile. | |
868 | * | |
869 | * Called and returns without pte mapped or spinlocks held, | |
870 | * but with mmap_sem held to protect against vma changes. | |
871 | */ | |
872 | ||
873 | static bool __collapse_huge_page_swapin(struct mm_struct *mm, | |
874 | struct vm_area_struct *vma, | |
0db501f7 EA |
875 | unsigned long address, pmd_t *pmd, |
876 | int referenced) | |
b46e756f | 877 | { |
b46e756f | 878 | int swapped_in = 0, ret = 0; |
82b0f8c3 | 879 | struct vm_fault vmf = { |
b46e756f KS |
880 | .vma = vma, |
881 | .address = address, | |
882 | .flags = FAULT_FLAG_ALLOW_RETRY, | |
883 | .pmd = pmd, | |
0721ec8b | 884 | .pgoff = linear_page_index(vma, address), |
b46e756f KS |
885 | }; |
886 | ||
982785c6 EA |
887 | /* we only decide to swapin, if there is enough young ptes */ |
888 | if (referenced < HPAGE_PMD_NR/2) { | |
889 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); | |
890 | return false; | |
891 | } | |
82b0f8c3 JK |
892 | vmf.pte = pte_offset_map(pmd, address); |
893 | for (; vmf.address < address + HPAGE_PMD_NR*PAGE_SIZE; | |
894 | vmf.pte++, vmf.address += PAGE_SIZE) { | |
2994302b JK |
895 | vmf.orig_pte = *vmf.pte; |
896 | if (!is_swap_pte(vmf.orig_pte)) | |
b46e756f KS |
897 | continue; |
898 | swapped_in++; | |
2994302b | 899 | ret = do_swap_page(&vmf); |
0db501f7 | 900 | |
b46e756f KS |
901 | /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */ |
902 | if (ret & VM_FAULT_RETRY) { | |
903 | down_read(&mm->mmap_sem); | |
82b0f8c3 | 904 | if (hugepage_vma_revalidate(mm, address, &vmf.vma)) { |
47f863ea | 905 | /* vma is no longer available, don't continue to swapin */ |
0db501f7 | 906 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f | 907 | return false; |
47f863ea | 908 | } |
b46e756f | 909 | /* check if the pmd is still valid */ |
835152a2 SP |
910 | if (mm_find_pmd(mm, address) != pmd) { |
911 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); | |
b46e756f | 912 | return false; |
835152a2 | 913 | } |
b46e756f KS |
914 | } |
915 | if (ret & VM_FAULT_ERROR) { | |
0db501f7 | 916 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f KS |
917 | return false; |
918 | } | |
919 | /* pte is unmapped now, we need to map it */ | |
82b0f8c3 | 920 | vmf.pte = pte_offset_map(pmd, vmf.address); |
b46e756f | 921 | } |
82b0f8c3 JK |
922 | vmf.pte--; |
923 | pte_unmap(vmf.pte); | |
0db501f7 | 924 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1); |
b46e756f KS |
925 | return true; |
926 | } | |
927 | ||
928 | static void collapse_huge_page(struct mm_struct *mm, | |
929 | unsigned long address, | |
930 | struct page **hpage, | |
0db501f7 | 931 | int node, int referenced) |
b46e756f KS |
932 | { |
933 | pmd_t *pmd, _pmd; | |
934 | pte_t *pte; | |
935 | pgtable_t pgtable; | |
936 | struct page *new_page; | |
937 | spinlock_t *pmd_ptl, *pte_ptl; | |
938 | int isolated = 0, result = 0; | |
939 | struct mem_cgroup *memcg; | |
c131f751 | 940 | struct vm_area_struct *vma; |
b46e756f KS |
941 | unsigned long mmun_start; /* For mmu_notifiers */ |
942 | unsigned long mmun_end; /* For mmu_notifiers */ | |
943 | gfp_t gfp; | |
944 | ||
945 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
946 | ||
947 | /* Only allocate from the target node */ | |
41b6167e | 948 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
b46e756f | 949 | |
988ddb71 KS |
950 | /* |
951 | * Before allocating the hugepage, release the mmap_sem read lock. | |
952 | * The allocation can take potentially a long time if it involves | |
953 | * sync compaction, and we do not need to hold the mmap_sem during | |
954 | * that. We will recheck the vma after taking it again in write mode. | |
955 | */ | |
956 | up_read(&mm->mmap_sem); | |
957 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
b46e756f KS |
958 | if (!new_page) { |
959 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
960 | goto out_nolock; | |
961 | } | |
962 | ||
963 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { | |
964 | result = SCAN_CGROUP_CHARGE_FAIL; | |
965 | goto out_nolock; | |
966 | } | |
967 | ||
968 | down_read(&mm->mmap_sem); | |
c131f751 | 969 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f KS |
970 | if (result) { |
971 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
972 | up_read(&mm->mmap_sem); | |
973 | goto out_nolock; | |
974 | } | |
975 | ||
976 | pmd = mm_find_pmd(mm, address); | |
977 | if (!pmd) { | |
978 | result = SCAN_PMD_NULL; | |
979 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
980 | up_read(&mm->mmap_sem); | |
981 | goto out_nolock; | |
982 | } | |
983 | ||
984 | /* | |
985 | * __collapse_huge_page_swapin always returns with mmap_sem locked. | |
47f863ea | 986 | * If it fails, we release mmap_sem and jump out_nolock. |
b46e756f KS |
987 | * Continuing to collapse causes inconsistency. |
988 | */ | |
0db501f7 | 989 | if (!__collapse_huge_page_swapin(mm, vma, address, pmd, referenced)) { |
b46e756f KS |
990 | mem_cgroup_cancel_charge(new_page, memcg, true); |
991 | up_read(&mm->mmap_sem); | |
992 | goto out_nolock; | |
993 | } | |
994 | ||
995 | up_read(&mm->mmap_sem); | |
996 | /* | |
997 | * Prevent all access to pagetables with the exception of | |
998 | * gup_fast later handled by the ptep_clear_flush and the VM | |
999 | * handled by the anon_vma lock + PG_lock. | |
1000 | */ | |
1001 | down_write(&mm->mmap_sem); | |
c131f751 | 1002 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f KS |
1003 | if (result) |
1004 | goto out; | |
1005 | /* check if the pmd is still valid */ | |
1006 | if (mm_find_pmd(mm, address) != pmd) | |
1007 | goto out; | |
1008 | ||
1009 | anon_vma_lock_write(vma->anon_vma); | |
1010 | ||
1011 | pte = pte_offset_map(pmd, address); | |
1012 | pte_ptl = pte_lockptr(mm, pmd); | |
1013 | ||
1014 | mmun_start = address; | |
1015 | mmun_end = address + HPAGE_PMD_SIZE; | |
1016 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1017 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ | |
1018 | /* | |
1019 | * After this gup_fast can't run anymore. This also removes | |
1020 | * any huge TLB entry from the CPU so we won't allow | |
1021 | * huge and small TLB entries for the same virtual address | |
1022 | * to avoid the risk of CPU bugs in that area. | |
1023 | */ | |
1024 | _pmd = pmdp_collapse_flush(vma, address, pmd); | |
1025 | spin_unlock(pmd_ptl); | |
1026 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
1027 | ||
1028 | spin_lock(pte_ptl); | |
1029 | isolated = __collapse_huge_page_isolate(vma, address, pte); | |
1030 | spin_unlock(pte_ptl); | |
1031 | ||
1032 | if (unlikely(!isolated)) { | |
1033 | pte_unmap(pte); | |
1034 | spin_lock(pmd_ptl); | |
1035 | BUG_ON(!pmd_none(*pmd)); | |
1036 | /* | |
1037 | * We can only use set_pmd_at when establishing | |
1038 | * hugepmds and never for establishing regular pmds that | |
1039 | * points to regular pagetables. Use pmd_populate for that | |
1040 | */ | |
1041 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
1042 | spin_unlock(pmd_ptl); | |
1043 | anon_vma_unlock_write(vma->anon_vma); | |
1044 | result = SCAN_FAIL; | |
1045 | goto out; | |
1046 | } | |
1047 | ||
1048 | /* | |
1049 | * All pages are isolated and locked so anon_vma rmap | |
1050 | * can't run anymore. | |
1051 | */ | |
1052 | anon_vma_unlock_write(vma->anon_vma); | |
1053 | ||
1054 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); | |
1055 | pte_unmap(pte); | |
1056 | __SetPageUptodate(new_page); | |
1057 | pgtable = pmd_pgtable(_pmd); | |
1058 | ||
1059 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); | |
f55e1014 | 1060 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); |
b46e756f KS |
1061 | |
1062 | /* | |
1063 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
1064 | * this is needed to avoid the copy_huge_page writes to become | |
1065 | * visible after the set_pmd_at() write. | |
1066 | */ | |
1067 | smp_wmb(); | |
1068 | ||
1069 | spin_lock(pmd_ptl); | |
1070 | BUG_ON(!pmd_none(*pmd)); | |
1071 | page_add_new_anon_rmap(new_page, vma, address, true); | |
1072 | mem_cgroup_commit_charge(new_page, memcg, false, true); | |
1073 | lru_cache_add_active_or_unevictable(new_page, vma); | |
1074 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
1075 | set_pmd_at(mm, address, pmd, _pmd); | |
1076 | update_mmu_cache_pmd(vma, address, pmd); | |
1077 | spin_unlock(pmd_ptl); | |
1078 | ||
1079 | *hpage = NULL; | |
1080 | ||
1081 | khugepaged_pages_collapsed++; | |
1082 | result = SCAN_SUCCEED; | |
1083 | out_up_write: | |
1084 | up_write(&mm->mmap_sem); | |
1085 | out_nolock: | |
1086 | trace_mm_collapse_huge_page(mm, isolated, result); | |
1087 | return; | |
1088 | out: | |
1089 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1090 | goto out_up_write; | |
1091 | } | |
1092 | ||
1093 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
1094 | struct vm_area_struct *vma, | |
1095 | unsigned long address, | |
1096 | struct page **hpage) | |
1097 | { | |
1098 | pmd_t *pmd; | |
1099 | pte_t *pte, *_pte; | |
0db501f7 | 1100 | int ret = 0, none_or_zero = 0, result = 0, referenced = 0; |
b46e756f KS |
1101 | struct page *page = NULL; |
1102 | unsigned long _address; | |
1103 | spinlock_t *ptl; | |
1104 | int node = NUMA_NO_NODE, unmapped = 0; | |
0db501f7 | 1105 | bool writable = false; |
b46e756f KS |
1106 | |
1107 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1108 | ||
1109 | pmd = mm_find_pmd(mm, address); | |
1110 | if (!pmd) { | |
1111 | result = SCAN_PMD_NULL; | |
1112 | goto out; | |
1113 | } | |
1114 | ||
1115 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1116 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1117 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1118 | _pte++, _address += PAGE_SIZE) { | |
1119 | pte_t pteval = *_pte; | |
1120 | if (is_swap_pte(pteval)) { | |
1121 | if (++unmapped <= khugepaged_max_ptes_swap) { | |
1122 | continue; | |
1123 | } else { | |
1124 | result = SCAN_EXCEED_SWAP_PTE; | |
1125 | goto out_unmap; | |
1126 | } | |
1127 | } | |
1128 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
1129 | if (!userfaultfd_armed(vma) && | |
1130 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
1131 | continue; | |
1132 | } else { | |
1133 | result = SCAN_EXCEED_NONE_PTE; | |
1134 | goto out_unmap; | |
1135 | } | |
1136 | } | |
1137 | if (!pte_present(pteval)) { | |
1138 | result = SCAN_PTE_NON_PRESENT; | |
1139 | goto out_unmap; | |
1140 | } | |
1141 | if (pte_write(pteval)) | |
1142 | writable = true; | |
1143 | ||
1144 | page = vm_normal_page(vma, _address, pteval); | |
1145 | if (unlikely(!page)) { | |
1146 | result = SCAN_PAGE_NULL; | |
1147 | goto out_unmap; | |
1148 | } | |
1149 | ||
1150 | /* TODO: teach khugepaged to collapse THP mapped with pte */ | |
1151 | if (PageCompound(page)) { | |
1152 | result = SCAN_PAGE_COMPOUND; | |
1153 | goto out_unmap; | |
1154 | } | |
1155 | ||
1156 | /* | |
1157 | * Record which node the original page is from and save this | |
1158 | * information to khugepaged_node_load[]. | |
1159 | * Khupaged will allocate hugepage from the node has the max | |
1160 | * hit record. | |
1161 | */ | |
1162 | node = page_to_nid(page); | |
1163 | if (khugepaged_scan_abort(node)) { | |
1164 | result = SCAN_SCAN_ABORT; | |
1165 | goto out_unmap; | |
1166 | } | |
1167 | khugepaged_node_load[node]++; | |
1168 | if (!PageLRU(page)) { | |
1169 | result = SCAN_PAGE_LRU; | |
1170 | goto out_unmap; | |
1171 | } | |
1172 | if (PageLocked(page)) { | |
1173 | result = SCAN_PAGE_LOCK; | |
1174 | goto out_unmap; | |
1175 | } | |
1176 | if (!PageAnon(page)) { | |
1177 | result = SCAN_PAGE_ANON; | |
1178 | goto out_unmap; | |
1179 | } | |
1180 | ||
1181 | /* | |
1182 | * cannot use mapcount: can't collapse if there's a gup pin. | |
1183 | * The page must only be referenced by the scanned process | |
1184 | * and page swap cache. | |
1185 | */ | |
2948be5a | 1186 | if (page_count(page) != 1 + PageSwapCache(page)) { |
b46e756f KS |
1187 | result = SCAN_PAGE_COUNT; |
1188 | goto out_unmap; | |
1189 | } | |
1190 | if (pte_young(pteval) || | |
1191 | page_is_young(page) || PageReferenced(page) || | |
1192 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 1193 | referenced++; |
b46e756f KS |
1194 | } |
1195 | if (writable) { | |
1196 | if (referenced) { | |
1197 | result = SCAN_SUCCEED; | |
1198 | ret = 1; | |
1199 | } else { | |
0db501f7 | 1200 | result = SCAN_LACK_REFERENCED_PAGE; |
b46e756f KS |
1201 | } |
1202 | } else { | |
1203 | result = SCAN_PAGE_RO; | |
1204 | } | |
1205 | out_unmap: | |
1206 | pte_unmap_unlock(pte, ptl); | |
1207 | if (ret) { | |
1208 | node = khugepaged_find_target_node(); | |
1209 | /* collapse_huge_page will return with the mmap_sem released */ | |
c131f751 | 1210 | collapse_huge_page(mm, address, hpage, node, referenced); |
b46e756f KS |
1211 | } |
1212 | out: | |
1213 | trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, | |
1214 | none_or_zero, result, unmapped); | |
1215 | return ret; | |
1216 | } | |
1217 | ||
1218 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
1219 | { | |
1220 | struct mm_struct *mm = mm_slot->mm; | |
1221 | ||
1222 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); | |
1223 | ||
1224 | if (khugepaged_test_exit(mm)) { | |
1225 | /* free mm_slot */ | |
1226 | hash_del(&mm_slot->hash); | |
1227 | list_del(&mm_slot->mm_node); | |
1228 | ||
1229 | /* | |
1230 | * Not strictly needed because the mm exited already. | |
1231 | * | |
1232 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1233 | */ | |
1234 | ||
1235 | /* khugepaged_mm_lock actually not necessary for the below */ | |
1236 | free_mm_slot(mm_slot); | |
1237 | mmdrop(mm); | |
1238 | } | |
1239 | } | |
1240 | ||
e496cf3d | 1241 | #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) |
f3f0e1d2 KS |
1242 | static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) |
1243 | { | |
1244 | struct vm_area_struct *vma; | |
1245 | unsigned long addr; | |
1246 | pmd_t *pmd, _pmd; | |
1247 | ||
1248 | i_mmap_lock_write(mapping); | |
1249 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { | |
1250 | /* probably overkill */ | |
1251 | if (vma->anon_vma) | |
1252 | continue; | |
1253 | addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
1254 | if (addr & ~HPAGE_PMD_MASK) | |
1255 | continue; | |
1256 | if (vma->vm_end < addr + HPAGE_PMD_SIZE) | |
1257 | continue; | |
1258 | pmd = mm_find_pmd(vma->vm_mm, addr); | |
1259 | if (!pmd) | |
1260 | continue; | |
1261 | /* | |
1262 | * We need exclusive mmap_sem to retract page table. | |
1263 | * If trylock fails we would end up with pte-mapped THP after | |
1264 | * re-fault. Not ideal, but it's more important to not disturb | |
1265 | * the system too much. | |
1266 | */ | |
1267 | if (down_write_trylock(&vma->vm_mm->mmap_sem)) { | |
1268 | spinlock_t *ptl = pmd_lock(vma->vm_mm, pmd); | |
1269 | /* assume page table is clear */ | |
1270 | _pmd = pmdp_collapse_flush(vma, addr, pmd); | |
1271 | spin_unlock(ptl); | |
1272 | up_write(&vma->vm_mm->mmap_sem); | |
c4812909 | 1273 | mm_dec_nr_ptes(vma->vm_mm); |
d670ffd8 | 1274 | pte_free(vma->vm_mm, pmd_pgtable(_pmd)); |
f3f0e1d2 KS |
1275 | } |
1276 | } | |
1277 | i_mmap_unlock_write(mapping); | |
1278 | } | |
1279 | ||
1280 | /** | |
1281 | * collapse_shmem - collapse small tmpfs/shmem pages into huge one. | |
1282 | * | |
1283 | * Basic scheme is simple, details are more complex: | |
1284 | * - allocate and freeze a new huge page; | |
1285 | * - scan over radix tree replacing old pages the new one | |
1286 | * + swap in pages if necessary; | |
1287 | * + fill in gaps; | |
1288 | * + keep old pages around in case if rollback is required; | |
1289 | * - if replacing succeed: | |
1290 | * + copy data over; | |
1291 | * + free old pages; | |
1292 | * + unfreeze huge page; | |
1293 | * - if replacing failed; | |
1294 | * + put all pages back and unfreeze them; | |
1295 | * + restore gaps in the radix-tree; | |
1296 | * + free huge page; | |
1297 | */ | |
1298 | static void collapse_shmem(struct mm_struct *mm, | |
1299 | struct address_space *mapping, pgoff_t start, | |
1300 | struct page **hpage, int node) | |
1301 | { | |
1302 | gfp_t gfp; | |
1303 | struct page *page, *new_page, *tmp; | |
1304 | struct mem_cgroup *memcg; | |
1305 | pgoff_t index, end = start + HPAGE_PMD_NR; | |
1306 | LIST_HEAD(pagelist); | |
1307 | struct radix_tree_iter iter; | |
1308 | void **slot; | |
1309 | int nr_none = 0, result = SCAN_SUCCEED; | |
1310 | ||
1311 | VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); | |
1312 | ||
1313 | /* Only allocate from the target node */ | |
41b6167e | 1314 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
f3f0e1d2 KS |
1315 | |
1316 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
1317 | if (!new_page) { | |
1318 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
1319 | goto out; | |
1320 | } | |
1321 | ||
1322 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { | |
1323 | result = SCAN_CGROUP_CHARGE_FAIL; | |
1324 | goto out; | |
1325 | } | |
1326 | ||
1327 | new_page->index = start; | |
1328 | new_page->mapping = mapping; | |
1329 | __SetPageSwapBacked(new_page); | |
1330 | __SetPageLocked(new_page); | |
1331 | BUG_ON(!page_ref_freeze(new_page, 1)); | |
1332 | ||
1333 | ||
1334 | /* | |
1335 | * At this point the new_page is 'frozen' (page_count() is zero), locked | |
1336 | * and not up-to-date. It's safe to insert it into radix tree, because | |
1337 | * nobody would be able to map it or use it in other way until we | |
1338 | * unfreeze it. | |
1339 | */ | |
1340 | ||
1341 | index = start; | |
1342 | spin_lock_irq(&mapping->tree_lock); | |
1343 | radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) { | |
1344 | int n = min(iter.index, end) - index; | |
1345 | ||
1346 | /* | |
1347 | * Handle holes in the radix tree: charge it from shmem and | |
1348 | * insert relevant subpage of new_page into the radix-tree. | |
1349 | */ | |
1350 | if (n && !shmem_charge(mapping->host, n)) { | |
1351 | result = SCAN_FAIL; | |
1352 | break; | |
1353 | } | |
1354 | nr_none += n; | |
1355 | for (; index < min(iter.index, end); index++) { | |
1356 | radix_tree_insert(&mapping->page_tree, index, | |
1357 | new_page + (index % HPAGE_PMD_NR)); | |
1358 | } | |
1359 | ||
1360 | /* We are done. */ | |
1361 | if (index >= end) | |
1362 | break; | |
1363 | ||
1364 | page = radix_tree_deref_slot_protected(slot, | |
1365 | &mapping->tree_lock); | |
1366 | if (radix_tree_exceptional_entry(page) || !PageUptodate(page)) { | |
1367 | spin_unlock_irq(&mapping->tree_lock); | |
1368 | /* swap in or instantiate fallocated page */ | |
1369 | if (shmem_getpage(mapping->host, index, &page, | |
1370 | SGP_NOHUGE)) { | |
1371 | result = SCAN_FAIL; | |
1372 | goto tree_unlocked; | |
1373 | } | |
1374 | spin_lock_irq(&mapping->tree_lock); | |
1375 | } else if (trylock_page(page)) { | |
1376 | get_page(page); | |
1377 | } else { | |
1378 | result = SCAN_PAGE_LOCK; | |
1379 | break; | |
1380 | } | |
1381 | ||
1382 | /* | |
1383 | * The page must be locked, so we can drop the tree_lock | |
1384 | * without racing with truncate. | |
1385 | */ | |
1386 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
1387 | VM_BUG_ON_PAGE(!PageUptodate(page), page); | |
1388 | VM_BUG_ON_PAGE(PageTransCompound(page), page); | |
1389 | ||
1390 | if (page_mapping(page) != mapping) { | |
1391 | result = SCAN_TRUNCATED; | |
1392 | goto out_unlock; | |
1393 | } | |
1394 | spin_unlock_irq(&mapping->tree_lock); | |
1395 | ||
1396 | if (isolate_lru_page(page)) { | |
1397 | result = SCAN_DEL_PAGE_LRU; | |
1398 | goto out_isolate_failed; | |
1399 | } | |
1400 | ||
1401 | if (page_mapped(page)) | |
977fbdcd | 1402 | unmap_mapping_pages(mapping, index, 1, false); |
f3f0e1d2 KS |
1403 | |
1404 | spin_lock_irq(&mapping->tree_lock); | |
1405 | ||
91a45f71 JW |
1406 | slot = radix_tree_lookup_slot(&mapping->page_tree, index); |
1407 | VM_BUG_ON_PAGE(page != radix_tree_deref_slot_protected(slot, | |
1408 | &mapping->tree_lock), page); | |
f3f0e1d2 KS |
1409 | VM_BUG_ON_PAGE(page_mapped(page), page); |
1410 | ||
1411 | /* | |
1412 | * The page is expected to have page_count() == 3: | |
1413 | * - we hold a pin on it; | |
1414 | * - one reference from radix tree; | |
1415 | * - one from isolate_lru_page; | |
1416 | */ | |
1417 | if (!page_ref_freeze(page, 3)) { | |
1418 | result = SCAN_PAGE_COUNT; | |
1419 | goto out_lru; | |
1420 | } | |
1421 | ||
1422 | /* | |
1423 | * Add the page to the list to be able to undo the collapse if | |
1424 | * something go wrong. | |
1425 | */ | |
1426 | list_add_tail(&page->lru, &pagelist); | |
1427 | ||
1428 | /* Finally, replace with the new page. */ | |
6d75f366 | 1429 | radix_tree_replace_slot(&mapping->page_tree, slot, |
f3f0e1d2 KS |
1430 | new_page + (index % HPAGE_PMD_NR)); |
1431 | ||
148deab2 | 1432 | slot = radix_tree_iter_resume(slot, &iter); |
f3f0e1d2 KS |
1433 | index++; |
1434 | continue; | |
1435 | out_lru: | |
1436 | spin_unlock_irq(&mapping->tree_lock); | |
1437 | putback_lru_page(page); | |
1438 | out_isolate_failed: | |
1439 | unlock_page(page); | |
1440 | put_page(page); | |
1441 | goto tree_unlocked; | |
1442 | out_unlock: | |
1443 | unlock_page(page); | |
1444 | put_page(page); | |
1445 | break; | |
1446 | } | |
1447 | ||
1448 | /* | |
1449 | * Handle hole in radix tree at the end of the range. | |
1450 | * This code only triggers if there's nothing in radix tree | |
1451 | * beyond 'end'. | |
1452 | */ | |
1453 | if (result == SCAN_SUCCEED && index < end) { | |
1454 | int n = end - index; | |
1455 | ||
1456 | if (!shmem_charge(mapping->host, n)) { | |
1457 | result = SCAN_FAIL; | |
1458 | goto tree_locked; | |
1459 | } | |
1460 | ||
1461 | for (; index < end; index++) { | |
1462 | radix_tree_insert(&mapping->page_tree, index, | |
1463 | new_page + (index % HPAGE_PMD_NR)); | |
1464 | } | |
1465 | nr_none += n; | |
1466 | } | |
1467 | ||
1468 | tree_locked: | |
1469 | spin_unlock_irq(&mapping->tree_lock); | |
1470 | tree_unlocked: | |
1471 | ||
1472 | if (result == SCAN_SUCCEED) { | |
1473 | unsigned long flags; | |
1474 | struct zone *zone = page_zone(new_page); | |
1475 | ||
1476 | /* | |
1477 | * Replacing old pages with new one has succeed, now we need to | |
1478 | * copy the content and free old pages. | |
1479 | */ | |
1480 | list_for_each_entry_safe(page, tmp, &pagelist, lru) { | |
1481 | copy_highpage(new_page + (page->index % HPAGE_PMD_NR), | |
1482 | page); | |
1483 | list_del(&page->lru); | |
1484 | unlock_page(page); | |
1485 | page_ref_unfreeze(page, 1); | |
1486 | page->mapping = NULL; | |
1487 | ClearPageActive(page); | |
1488 | ClearPageUnevictable(page); | |
1489 | put_page(page); | |
1490 | } | |
1491 | ||
1492 | local_irq_save(flags); | |
11fb9989 | 1493 | __inc_node_page_state(new_page, NR_SHMEM_THPS); |
f3f0e1d2 | 1494 | if (nr_none) { |
11fb9989 MG |
1495 | __mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none); |
1496 | __mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none); | |
f3f0e1d2 KS |
1497 | } |
1498 | local_irq_restore(flags); | |
1499 | ||
1500 | /* | |
1501 | * Remove pte page tables, so we can re-faulti | |
1502 | * the page as huge. | |
1503 | */ | |
1504 | retract_page_tables(mapping, start); | |
1505 | ||
1506 | /* Everything is ready, let's unfreeze the new_page */ | |
1507 | set_page_dirty(new_page); | |
1508 | SetPageUptodate(new_page); | |
1509 | page_ref_unfreeze(new_page, HPAGE_PMD_NR); | |
1510 | mem_cgroup_commit_charge(new_page, memcg, false, true); | |
1511 | lru_cache_add_anon(new_page); | |
1512 | unlock_page(new_page); | |
1513 | ||
1514 | *hpage = NULL; | |
1515 | } else { | |
1516 | /* Something went wrong: rollback changes to the radix-tree */ | |
1517 | shmem_uncharge(mapping->host, nr_none); | |
1518 | spin_lock_irq(&mapping->tree_lock); | |
1519 | radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, | |
1520 | start) { | |
1521 | if (iter.index >= end) | |
1522 | break; | |
1523 | page = list_first_entry_or_null(&pagelist, | |
1524 | struct page, lru); | |
1525 | if (!page || iter.index < page->index) { | |
1526 | if (!nr_none) | |
1527 | break; | |
f3f0e1d2 | 1528 | nr_none--; |
59749e6c JW |
1529 | /* Put holes back where they were */ |
1530 | radix_tree_delete(&mapping->page_tree, | |
1531 | iter.index); | |
f3f0e1d2 KS |
1532 | continue; |
1533 | } | |
1534 | ||
1535 | VM_BUG_ON_PAGE(page->index != iter.index, page); | |
1536 | ||
1537 | /* Unfreeze the page. */ | |
1538 | list_del(&page->lru); | |
1539 | page_ref_unfreeze(page, 2); | |
6d75f366 JW |
1540 | radix_tree_replace_slot(&mapping->page_tree, |
1541 | slot, page); | |
148deab2 | 1542 | slot = radix_tree_iter_resume(slot, &iter); |
f3f0e1d2 KS |
1543 | spin_unlock_irq(&mapping->tree_lock); |
1544 | putback_lru_page(page); | |
1545 | unlock_page(page); | |
1546 | spin_lock_irq(&mapping->tree_lock); | |
1547 | } | |
1548 | VM_BUG_ON(nr_none); | |
1549 | spin_unlock_irq(&mapping->tree_lock); | |
1550 | ||
1551 | /* Unfreeze new_page, caller would take care about freeing it */ | |
1552 | page_ref_unfreeze(new_page, 1); | |
1553 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1554 | unlock_page(new_page); | |
1555 | new_page->mapping = NULL; | |
1556 | } | |
1557 | out: | |
1558 | VM_BUG_ON(!list_empty(&pagelist)); | |
1559 | /* TODO: tracepoints */ | |
1560 | } | |
1561 | ||
1562 | static void khugepaged_scan_shmem(struct mm_struct *mm, | |
1563 | struct address_space *mapping, | |
1564 | pgoff_t start, struct page **hpage) | |
1565 | { | |
1566 | struct page *page = NULL; | |
1567 | struct radix_tree_iter iter; | |
1568 | void **slot; | |
1569 | int present, swap; | |
1570 | int node = NUMA_NO_NODE; | |
1571 | int result = SCAN_SUCCEED; | |
1572 | ||
1573 | present = 0; | |
1574 | swap = 0; | |
1575 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1576 | rcu_read_lock(); | |
1577 | radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) { | |
1578 | if (iter.index >= start + HPAGE_PMD_NR) | |
1579 | break; | |
1580 | ||
1581 | page = radix_tree_deref_slot(slot); | |
1582 | if (radix_tree_deref_retry(page)) { | |
1583 | slot = radix_tree_iter_retry(&iter); | |
1584 | continue; | |
1585 | } | |
1586 | ||
1587 | if (radix_tree_exception(page)) { | |
1588 | if (++swap > khugepaged_max_ptes_swap) { | |
1589 | result = SCAN_EXCEED_SWAP_PTE; | |
1590 | break; | |
1591 | } | |
1592 | continue; | |
1593 | } | |
1594 | ||
1595 | if (PageTransCompound(page)) { | |
1596 | result = SCAN_PAGE_COMPOUND; | |
1597 | break; | |
1598 | } | |
1599 | ||
1600 | node = page_to_nid(page); | |
1601 | if (khugepaged_scan_abort(node)) { | |
1602 | result = SCAN_SCAN_ABORT; | |
1603 | break; | |
1604 | } | |
1605 | khugepaged_node_load[node]++; | |
1606 | ||
1607 | if (!PageLRU(page)) { | |
1608 | result = SCAN_PAGE_LRU; | |
1609 | break; | |
1610 | } | |
1611 | ||
1612 | if (page_count(page) != 1 + page_mapcount(page)) { | |
1613 | result = SCAN_PAGE_COUNT; | |
1614 | break; | |
1615 | } | |
1616 | ||
1617 | /* | |
1618 | * We probably should check if the page is referenced here, but | |
1619 | * nobody would transfer pte_young() to PageReferenced() for us. | |
1620 | * And rmap walk here is just too costly... | |
1621 | */ | |
1622 | ||
1623 | present++; | |
1624 | ||
1625 | if (need_resched()) { | |
148deab2 | 1626 | slot = radix_tree_iter_resume(slot, &iter); |
f3f0e1d2 | 1627 | cond_resched_rcu(); |
f3f0e1d2 KS |
1628 | } |
1629 | } | |
1630 | rcu_read_unlock(); | |
1631 | ||
1632 | if (result == SCAN_SUCCEED) { | |
1633 | if (present < HPAGE_PMD_NR - khugepaged_max_ptes_none) { | |
1634 | result = SCAN_EXCEED_NONE_PTE; | |
1635 | } else { | |
1636 | node = khugepaged_find_target_node(); | |
1637 | collapse_shmem(mm, mapping, start, hpage, node); | |
1638 | } | |
1639 | } | |
1640 | ||
1641 | /* TODO: tracepoints */ | |
1642 | } | |
1643 | #else | |
1644 | static void khugepaged_scan_shmem(struct mm_struct *mm, | |
1645 | struct address_space *mapping, | |
1646 | pgoff_t start, struct page **hpage) | |
1647 | { | |
1648 | BUILD_BUG(); | |
1649 | } | |
1650 | #endif | |
1651 | ||
b46e756f KS |
1652 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, |
1653 | struct page **hpage) | |
1654 | __releases(&khugepaged_mm_lock) | |
1655 | __acquires(&khugepaged_mm_lock) | |
1656 | { | |
1657 | struct mm_slot *mm_slot; | |
1658 | struct mm_struct *mm; | |
1659 | struct vm_area_struct *vma; | |
1660 | int progress = 0; | |
1661 | ||
1662 | VM_BUG_ON(!pages); | |
1663 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); | |
1664 | ||
1665 | if (khugepaged_scan.mm_slot) | |
1666 | mm_slot = khugepaged_scan.mm_slot; | |
1667 | else { | |
1668 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
1669 | struct mm_slot, mm_node); | |
1670 | khugepaged_scan.address = 0; | |
1671 | khugepaged_scan.mm_slot = mm_slot; | |
1672 | } | |
1673 | spin_unlock(&khugepaged_mm_lock); | |
1674 | ||
1675 | mm = mm_slot->mm; | |
1676 | down_read(&mm->mmap_sem); | |
1677 | if (unlikely(khugepaged_test_exit(mm))) | |
1678 | vma = NULL; | |
1679 | else | |
1680 | vma = find_vma(mm, khugepaged_scan.address); | |
1681 | ||
1682 | progress++; | |
1683 | for (; vma; vma = vma->vm_next) { | |
1684 | unsigned long hstart, hend; | |
1685 | ||
1686 | cond_resched(); | |
1687 | if (unlikely(khugepaged_test_exit(mm))) { | |
1688 | progress++; | |
1689 | break; | |
1690 | } | |
1691 | if (!hugepage_vma_check(vma)) { | |
1692 | skip: | |
1693 | progress++; | |
1694 | continue; | |
1695 | } | |
1696 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
1697 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1698 | if (hstart >= hend) | |
1699 | goto skip; | |
1700 | if (khugepaged_scan.address > hend) | |
1701 | goto skip; | |
1702 | if (khugepaged_scan.address < hstart) | |
1703 | khugepaged_scan.address = hstart; | |
1704 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); | |
1705 | ||
1706 | while (khugepaged_scan.address < hend) { | |
1707 | int ret; | |
1708 | cond_resched(); | |
1709 | if (unlikely(khugepaged_test_exit(mm))) | |
1710 | goto breakouterloop; | |
1711 | ||
1712 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
1713 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
1714 | hend); | |
f3f0e1d2 | 1715 | if (shmem_file(vma->vm_file)) { |
e496cf3d | 1716 | struct file *file; |
f3f0e1d2 KS |
1717 | pgoff_t pgoff = linear_page_index(vma, |
1718 | khugepaged_scan.address); | |
e496cf3d KS |
1719 | if (!shmem_huge_enabled(vma)) |
1720 | goto skip; | |
1721 | file = get_file(vma->vm_file); | |
f3f0e1d2 KS |
1722 | up_read(&mm->mmap_sem); |
1723 | ret = 1; | |
1724 | khugepaged_scan_shmem(mm, file->f_mapping, | |
1725 | pgoff, hpage); | |
1726 | fput(file); | |
1727 | } else { | |
1728 | ret = khugepaged_scan_pmd(mm, vma, | |
1729 | khugepaged_scan.address, | |
1730 | hpage); | |
1731 | } | |
b46e756f KS |
1732 | /* move to next address */ |
1733 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
1734 | progress += HPAGE_PMD_NR; | |
1735 | if (ret) | |
1736 | /* we released mmap_sem so break loop */ | |
1737 | goto breakouterloop_mmap_sem; | |
1738 | if (progress >= pages) | |
1739 | goto breakouterloop; | |
1740 | } | |
1741 | } | |
1742 | breakouterloop: | |
1743 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
1744 | breakouterloop_mmap_sem: | |
1745 | ||
1746 | spin_lock(&khugepaged_mm_lock); | |
1747 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); | |
1748 | /* | |
1749 | * Release the current mm_slot if this mm is about to die, or | |
1750 | * if we scanned all vmas of this mm. | |
1751 | */ | |
1752 | if (khugepaged_test_exit(mm) || !vma) { | |
1753 | /* | |
1754 | * Make sure that if mm_users is reaching zero while | |
1755 | * khugepaged runs here, khugepaged_exit will find | |
1756 | * mm_slot not pointing to the exiting mm. | |
1757 | */ | |
1758 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
1759 | khugepaged_scan.mm_slot = list_entry( | |
1760 | mm_slot->mm_node.next, | |
1761 | struct mm_slot, mm_node); | |
1762 | khugepaged_scan.address = 0; | |
1763 | } else { | |
1764 | khugepaged_scan.mm_slot = NULL; | |
1765 | khugepaged_full_scans++; | |
1766 | } | |
1767 | ||
1768 | collect_mm_slot(mm_slot); | |
1769 | } | |
1770 | ||
1771 | return progress; | |
1772 | } | |
1773 | ||
1774 | static int khugepaged_has_work(void) | |
1775 | { | |
1776 | return !list_empty(&khugepaged_scan.mm_head) && | |
1777 | khugepaged_enabled(); | |
1778 | } | |
1779 | ||
1780 | static int khugepaged_wait_event(void) | |
1781 | { | |
1782 | return !list_empty(&khugepaged_scan.mm_head) || | |
1783 | kthread_should_stop(); | |
1784 | } | |
1785 | ||
1786 | static void khugepaged_do_scan(void) | |
1787 | { | |
1788 | struct page *hpage = NULL; | |
1789 | unsigned int progress = 0, pass_through_head = 0; | |
1790 | unsigned int pages = khugepaged_pages_to_scan; | |
1791 | bool wait = true; | |
1792 | ||
1793 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
1794 | ||
1795 | while (progress < pages) { | |
1796 | if (!khugepaged_prealloc_page(&hpage, &wait)) | |
1797 | break; | |
1798 | ||
1799 | cond_resched(); | |
1800 | ||
1801 | if (unlikely(kthread_should_stop() || try_to_freeze())) | |
1802 | break; | |
1803 | ||
1804 | spin_lock(&khugepaged_mm_lock); | |
1805 | if (!khugepaged_scan.mm_slot) | |
1806 | pass_through_head++; | |
1807 | if (khugepaged_has_work() && | |
1808 | pass_through_head < 2) | |
1809 | progress += khugepaged_scan_mm_slot(pages - progress, | |
1810 | &hpage); | |
1811 | else | |
1812 | progress = pages; | |
1813 | spin_unlock(&khugepaged_mm_lock); | |
1814 | } | |
1815 | ||
1816 | if (!IS_ERR_OR_NULL(hpage)) | |
1817 | put_page(hpage); | |
1818 | } | |
1819 | ||
1820 | static bool khugepaged_should_wakeup(void) | |
1821 | { | |
1822 | return kthread_should_stop() || | |
1823 | time_after_eq(jiffies, khugepaged_sleep_expire); | |
1824 | } | |
1825 | ||
1826 | static void khugepaged_wait_work(void) | |
1827 | { | |
1828 | if (khugepaged_has_work()) { | |
1829 | const unsigned long scan_sleep_jiffies = | |
1830 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs); | |
1831 | ||
1832 | if (!scan_sleep_jiffies) | |
1833 | return; | |
1834 | ||
1835 | khugepaged_sleep_expire = jiffies + scan_sleep_jiffies; | |
1836 | wait_event_freezable_timeout(khugepaged_wait, | |
1837 | khugepaged_should_wakeup(), | |
1838 | scan_sleep_jiffies); | |
1839 | return; | |
1840 | } | |
1841 | ||
1842 | if (khugepaged_enabled()) | |
1843 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
1844 | } | |
1845 | ||
1846 | static int khugepaged(void *none) | |
1847 | { | |
1848 | struct mm_slot *mm_slot; | |
1849 | ||
1850 | set_freezable(); | |
1851 | set_user_nice(current, MAX_NICE); | |
1852 | ||
1853 | while (!kthread_should_stop()) { | |
1854 | khugepaged_do_scan(); | |
1855 | khugepaged_wait_work(); | |
1856 | } | |
1857 | ||
1858 | spin_lock(&khugepaged_mm_lock); | |
1859 | mm_slot = khugepaged_scan.mm_slot; | |
1860 | khugepaged_scan.mm_slot = NULL; | |
1861 | if (mm_slot) | |
1862 | collect_mm_slot(mm_slot); | |
1863 | spin_unlock(&khugepaged_mm_lock); | |
1864 | return 0; | |
1865 | } | |
1866 | ||
1867 | static void set_recommended_min_free_kbytes(void) | |
1868 | { | |
1869 | struct zone *zone; | |
1870 | int nr_zones = 0; | |
1871 | unsigned long recommended_min; | |
1872 | ||
1873 | for_each_populated_zone(zone) | |
1874 | nr_zones++; | |
1875 | ||
1876 | /* Ensure 2 pageblocks are free to assist fragmentation avoidance */ | |
1877 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
1878 | ||
1879 | /* | |
1880 | * Make sure that on average at least two pageblocks are almost free | |
1881 | * of another type, one for a migratetype to fall back to and a | |
1882 | * second to avoid subsequent fallbacks of other types There are 3 | |
1883 | * MIGRATE_TYPES we care about. | |
1884 | */ | |
1885 | recommended_min += pageblock_nr_pages * nr_zones * | |
1886 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
1887 | ||
1888 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
1889 | recommended_min = min(recommended_min, | |
1890 | (unsigned long) nr_free_buffer_pages() / 20); | |
1891 | recommended_min <<= (PAGE_SHIFT-10); | |
1892 | ||
1893 | if (recommended_min > min_free_kbytes) { | |
1894 | if (user_min_free_kbytes >= 0) | |
1895 | pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n", | |
1896 | min_free_kbytes, recommended_min); | |
1897 | ||
1898 | min_free_kbytes = recommended_min; | |
1899 | } | |
1900 | setup_per_zone_wmarks(); | |
1901 | } | |
1902 | ||
1903 | int start_stop_khugepaged(void) | |
1904 | { | |
1905 | static struct task_struct *khugepaged_thread __read_mostly; | |
1906 | static DEFINE_MUTEX(khugepaged_mutex); | |
1907 | int err = 0; | |
1908 | ||
1909 | mutex_lock(&khugepaged_mutex); | |
1910 | if (khugepaged_enabled()) { | |
1911 | if (!khugepaged_thread) | |
1912 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
1913 | "khugepaged"); | |
1914 | if (IS_ERR(khugepaged_thread)) { | |
1915 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); | |
1916 | err = PTR_ERR(khugepaged_thread); | |
1917 | khugepaged_thread = NULL; | |
1918 | goto fail; | |
1919 | } | |
1920 | ||
1921 | if (!list_empty(&khugepaged_scan.mm_head)) | |
1922 | wake_up_interruptible(&khugepaged_wait); | |
1923 | ||
1924 | set_recommended_min_free_kbytes(); | |
1925 | } else if (khugepaged_thread) { | |
1926 | kthread_stop(khugepaged_thread); | |
1927 | khugepaged_thread = NULL; | |
1928 | } | |
1929 | fail: | |
1930 | mutex_unlock(&khugepaged_mutex); | |
1931 | return err; | |
1932 | } |