Commit | Line | Data |
---|---|---|
71e3aac0 AA |
1 | /* |
2 | * Copyright (C) 2009 Red Hat, Inc. | |
3 | * | |
4 | * This work is licensed under the terms of the GNU GPL, version 2. See | |
5 | * the COPYING file in the top-level directory. | |
6 | */ | |
7 | ||
8 | #include <linux/mm.h> | |
9 | #include <linux/sched.h> | |
10 | #include <linux/highmem.h> | |
11 | #include <linux/hugetlb.h> | |
12 | #include <linux/mmu_notifier.h> | |
13 | #include <linux/rmap.h> | |
14 | #include <linux/swap.h> | |
97ae1749 | 15 | #include <linux/shrinker.h> |
ba76149f AA |
16 | #include <linux/mm_inline.h> |
17 | #include <linux/kthread.h> | |
18 | #include <linux/khugepaged.h> | |
878aee7d | 19 | #include <linux/freezer.h> |
a664b2d8 | 20 | #include <linux/mman.h> |
325adeb5 | 21 | #include <linux/pagemap.h> |
4daae3b4 | 22 | #include <linux/migrate.h> |
43b5fbbd | 23 | #include <linux/hashtable.h> |
97ae1749 | 24 | |
71e3aac0 AA |
25 | #include <asm/tlb.h> |
26 | #include <asm/pgalloc.h> | |
27 | #include "internal.h" | |
28 | ||
ba76149f AA |
29 | /* |
30 | * By default transparent hugepage support is enabled for all mappings | |
31 | * and khugepaged scans all mappings. Defrag is only invoked by | |
32 | * khugepaged hugepage allocations and by page faults inside | |
33 | * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived | |
34 | * allocations. | |
35 | */ | |
71e3aac0 | 36 | unsigned long transparent_hugepage_flags __read_mostly = |
13ece886 | 37 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS |
ba76149f | 38 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| |
13ece886 AA |
39 | #endif |
40 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE | |
41 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| | |
42 | #endif | |
d39d33c3 | 43 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)| |
79da5407 KS |
44 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| |
45 | (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
ba76149f AA |
46 | |
47 | /* default scan 8*512 pte (or vmas) every 30 second */ | |
48 | static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8; | |
49 | static unsigned int khugepaged_pages_collapsed; | |
50 | static unsigned int khugepaged_full_scans; | |
51 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
52 | /* during fragmentation poll the hugepage allocator once every minute */ | |
53 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
54 | static struct task_struct *khugepaged_thread __read_mostly; | |
55 | static DEFINE_MUTEX(khugepaged_mutex); | |
56 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
57 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
58 | /* | |
59 | * default collapse hugepages if there is at least one pte mapped like | |
60 | * it would have happened if the vma was large enough during page | |
61 | * fault. | |
62 | */ | |
63 | static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1; | |
64 | ||
65 | static int khugepaged(void *none); | |
ba76149f | 66 | static int khugepaged_slab_init(void); |
ba76149f | 67 | |
43b5fbbd SL |
68 | #define MM_SLOTS_HASH_BITS 10 |
69 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
70 | ||
ba76149f AA |
71 | static struct kmem_cache *mm_slot_cache __read_mostly; |
72 | ||
73 | /** | |
74 | * struct mm_slot - hash lookup from mm to mm_slot | |
75 | * @hash: hash collision list | |
76 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
77 | * @mm: the mm that this information is valid for | |
78 | */ | |
79 | struct mm_slot { | |
80 | struct hlist_node hash; | |
81 | struct list_head mm_node; | |
82 | struct mm_struct *mm; | |
83 | }; | |
84 | ||
85 | /** | |
86 | * struct khugepaged_scan - cursor for scanning | |
87 | * @mm_head: the head of the mm list to scan | |
88 | * @mm_slot: the current mm_slot we are scanning | |
89 | * @address: the next address inside that to be scanned | |
90 | * | |
91 | * There is only the one khugepaged_scan instance of this cursor structure. | |
92 | */ | |
93 | struct khugepaged_scan { | |
94 | struct list_head mm_head; | |
95 | struct mm_slot *mm_slot; | |
96 | unsigned long address; | |
2f1da642 HS |
97 | }; |
98 | static struct khugepaged_scan khugepaged_scan = { | |
ba76149f AA |
99 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), |
100 | }; | |
101 | ||
f000565a AA |
102 | |
103 | static int set_recommended_min_free_kbytes(void) | |
104 | { | |
105 | struct zone *zone; | |
106 | int nr_zones = 0; | |
107 | unsigned long recommended_min; | |
f000565a | 108 | |
17c230af | 109 | if (!khugepaged_enabled()) |
f000565a AA |
110 | return 0; |
111 | ||
112 | for_each_populated_zone(zone) | |
113 | nr_zones++; | |
114 | ||
115 | /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */ | |
116 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
117 | ||
118 | /* | |
119 | * Make sure that on average at least two pageblocks are almost free | |
120 | * of another type, one for a migratetype to fall back to and a | |
121 | * second to avoid subsequent fallbacks of other types There are 3 | |
122 | * MIGRATE_TYPES we care about. | |
123 | */ | |
124 | recommended_min += pageblock_nr_pages * nr_zones * | |
125 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
126 | ||
127 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
128 | recommended_min = min(recommended_min, | |
129 | (unsigned long) nr_free_buffer_pages() / 20); | |
130 | recommended_min <<= (PAGE_SHIFT-10); | |
131 | ||
132 | if (recommended_min > min_free_kbytes) | |
133 | min_free_kbytes = recommended_min; | |
134 | setup_per_zone_wmarks(); | |
135 | return 0; | |
136 | } | |
137 | late_initcall(set_recommended_min_free_kbytes); | |
138 | ||
ba76149f AA |
139 | static int start_khugepaged(void) |
140 | { | |
141 | int err = 0; | |
142 | if (khugepaged_enabled()) { | |
ba76149f AA |
143 | if (!khugepaged_thread) |
144 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
145 | "khugepaged"); | |
146 | if (unlikely(IS_ERR(khugepaged_thread))) { | |
147 | printk(KERN_ERR | |
148 | "khugepaged: kthread_run(khugepaged) failed\n"); | |
149 | err = PTR_ERR(khugepaged_thread); | |
150 | khugepaged_thread = NULL; | |
151 | } | |
911891af XG |
152 | |
153 | if (!list_empty(&khugepaged_scan.mm_head)) | |
ba76149f | 154 | wake_up_interruptible(&khugepaged_wait); |
f000565a AA |
155 | |
156 | set_recommended_min_free_kbytes(); | |
911891af | 157 | } else if (khugepaged_thread) { |
911891af XG |
158 | kthread_stop(khugepaged_thread); |
159 | khugepaged_thread = NULL; | |
160 | } | |
637e3a27 | 161 | |
ba76149f AA |
162 | return err; |
163 | } | |
71e3aac0 | 164 | |
97ae1749 KS |
165 | static atomic_t huge_zero_refcount; |
166 | static unsigned long huge_zero_pfn __read_mostly; | |
167 | ||
168 | static inline bool is_huge_zero_pfn(unsigned long pfn) | |
4a6c1297 | 169 | { |
97ae1749 KS |
170 | unsigned long zero_pfn = ACCESS_ONCE(huge_zero_pfn); |
171 | return zero_pfn && pfn == zero_pfn; | |
172 | } | |
4a6c1297 | 173 | |
97ae1749 KS |
174 | static inline bool is_huge_zero_pmd(pmd_t pmd) |
175 | { | |
176 | return is_huge_zero_pfn(pmd_pfn(pmd)); | |
177 | } | |
178 | ||
179 | static unsigned long get_huge_zero_page(void) | |
180 | { | |
181 | struct page *zero_page; | |
182 | retry: | |
183 | if (likely(atomic_inc_not_zero(&huge_zero_refcount))) | |
184 | return ACCESS_ONCE(huge_zero_pfn); | |
185 | ||
186 | zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, | |
4a6c1297 | 187 | HPAGE_PMD_ORDER); |
d8a8e1f0 KS |
188 | if (!zero_page) { |
189 | count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); | |
97ae1749 | 190 | return 0; |
d8a8e1f0 KS |
191 | } |
192 | count_vm_event(THP_ZERO_PAGE_ALLOC); | |
97ae1749 KS |
193 | preempt_disable(); |
194 | if (cmpxchg(&huge_zero_pfn, 0, page_to_pfn(zero_page))) { | |
195 | preempt_enable(); | |
196 | __free_page(zero_page); | |
197 | goto retry; | |
198 | } | |
199 | ||
200 | /* We take additional reference here. It will be put back by shrinker */ | |
201 | atomic_set(&huge_zero_refcount, 2); | |
202 | preempt_enable(); | |
203 | return ACCESS_ONCE(huge_zero_pfn); | |
4a6c1297 KS |
204 | } |
205 | ||
97ae1749 | 206 | static void put_huge_zero_page(void) |
4a6c1297 | 207 | { |
97ae1749 KS |
208 | /* |
209 | * Counter should never go to zero here. Only shrinker can put | |
210 | * last reference. | |
211 | */ | |
212 | BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); | |
4a6c1297 KS |
213 | } |
214 | ||
97ae1749 KS |
215 | static int shrink_huge_zero_page(struct shrinker *shrink, |
216 | struct shrink_control *sc) | |
4a6c1297 | 217 | { |
97ae1749 KS |
218 | if (!sc->nr_to_scan) |
219 | /* we can free zero page only if last reference remains */ | |
220 | return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; | |
221 | ||
222 | if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { | |
223 | unsigned long zero_pfn = xchg(&huge_zero_pfn, 0); | |
224 | BUG_ON(zero_pfn == 0); | |
225 | __free_page(__pfn_to_page(zero_pfn)); | |
226 | } | |
227 | ||
228 | return 0; | |
4a6c1297 KS |
229 | } |
230 | ||
97ae1749 KS |
231 | static struct shrinker huge_zero_page_shrinker = { |
232 | .shrink = shrink_huge_zero_page, | |
233 | .seeks = DEFAULT_SEEKS, | |
234 | }; | |
235 | ||
71e3aac0 | 236 | #ifdef CONFIG_SYSFS |
ba76149f | 237 | |
71e3aac0 AA |
238 | static ssize_t double_flag_show(struct kobject *kobj, |
239 | struct kobj_attribute *attr, char *buf, | |
240 | enum transparent_hugepage_flag enabled, | |
241 | enum transparent_hugepage_flag req_madv) | |
242 | { | |
243 | if (test_bit(enabled, &transparent_hugepage_flags)) { | |
244 | VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags)); | |
245 | return sprintf(buf, "[always] madvise never\n"); | |
246 | } else if (test_bit(req_madv, &transparent_hugepage_flags)) | |
247 | return sprintf(buf, "always [madvise] never\n"); | |
248 | else | |
249 | return sprintf(buf, "always madvise [never]\n"); | |
250 | } | |
251 | static ssize_t double_flag_store(struct kobject *kobj, | |
252 | struct kobj_attribute *attr, | |
253 | const char *buf, size_t count, | |
254 | enum transparent_hugepage_flag enabled, | |
255 | enum transparent_hugepage_flag req_madv) | |
256 | { | |
257 | if (!memcmp("always", buf, | |
258 | min(sizeof("always")-1, count))) { | |
259 | set_bit(enabled, &transparent_hugepage_flags); | |
260 | clear_bit(req_madv, &transparent_hugepage_flags); | |
261 | } else if (!memcmp("madvise", buf, | |
262 | min(sizeof("madvise")-1, count))) { | |
263 | clear_bit(enabled, &transparent_hugepage_flags); | |
264 | set_bit(req_madv, &transparent_hugepage_flags); | |
265 | } else if (!memcmp("never", buf, | |
266 | min(sizeof("never")-1, count))) { | |
267 | clear_bit(enabled, &transparent_hugepage_flags); | |
268 | clear_bit(req_madv, &transparent_hugepage_flags); | |
269 | } else | |
270 | return -EINVAL; | |
271 | ||
272 | return count; | |
273 | } | |
274 | ||
275 | static ssize_t enabled_show(struct kobject *kobj, | |
276 | struct kobj_attribute *attr, char *buf) | |
277 | { | |
278 | return double_flag_show(kobj, attr, buf, | |
279 | TRANSPARENT_HUGEPAGE_FLAG, | |
280 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
281 | } | |
282 | static ssize_t enabled_store(struct kobject *kobj, | |
283 | struct kobj_attribute *attr, | |
284 | const char *buf, size_t count) | |
285 | { | |
ba76149f AA |
286 | ssize_t ret; |
287 | ||
288 | ret = double_flag_store(kobj, attr, buf, count, | |
289 | TRANSPARENT_HUGEPAGE_FLAG, | |
290 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
291 | ||
292 | if (ret > 0) { | |
911891af XG |
293 | int err; |
294 | ||
295 | mutex_lock(&khugepaged_mutex); | |
296 | err = start_khugepaged(); | |
297 | mutex_unlock(&khugepaged_mutex); | |
298 | ||
ba76149f AA |
299 | if (err) |
300 | ret = err; | |
301 | } | |
302 | ||
303 | return ret; | |
71e3aac0 AA |
304 | } |
305 | static struct kobj_attribute enabled_attr = | |
306 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
307 | ||
308 | static ssize_t single_flag_show(struct kobject *kobj, | |
309 | struct kobj_attribute *attr, char *buf, | |
310 | enum transparent_hugepage_flag flag) | |
311 | { | |
e27e6151 BH |
312 | return sprintf(buf, "%d\n", |
313 | !!test_bit(flag, &transparent_hugepage_flags)); | |
71e3aac0 | 314 | } |
e27e6151 | 315 | |
71e3aac0 AA |
316 | static ssize_t single_flag_store(struct kobject *kobj, |
317 | struct kobj_attribute *attr, | |
318 | const char *buf, size_t count, | |
319 | enum transparent_hugepage_flag flag) | |
320 | { | |
e27e6151 BH |
321 | unsigned long value; |
322 | int ret; | |
323 | ||
324 | ret = kstrtoul(buf, 10, &value); | |
325 | if (ret < 0) | |
326 | return ret; | |
327 | if (value > 1) | |
328 | return -EINVAL; | |
329 | ||
330 | if (value) | |
71e3aac0 | 331 | set_bit(flag, &transparent_hugepage_flags); |
e27e6151 | 332 | else |
71e3aac0 | 333 | clear_bit(flag, &transparent_hugepage_flags); |
71e3aac0 AA |
334 | |
335 | return count; | |
336 | } | |
337 | ||
338 | /* | |
339 | * Currently defrag only disables __GFP_NOWAIT for allocation. A blind | |
340 | * __GFP_REPEAT is too aggressive, it's never worth swapping tons of | |
341 | * memory just to allocate one more hugepage. | |
342 | */ | |
343 | static ssize_t defrag_show(struct kobject *kobj, | |
344 | struct kobj_attribute *attr, char *buf) | |
345 | { | |
346 | return double_flag_show(kobj, attr, buf, | |
347 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
348 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
349 | } | |
350 | static ssize_t defrag_store(struct kobject *kobj, | |
351 | struct kobj_attribute *attr, | |
352 | const char *buf, size_t count) | |
353 | { | |
354 | return double_flag_store(kobj, attr, buf, count, | |
355 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
356 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
357 | } | |
358 | static struct kobj_attribute defrag_attr = | |
359 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
360 | ||
79da5407 KS |
361 | static ssize_t use_zero_page_show(struct kobject *kobj, |
362 | struct kobj_attribute *attr, char *buf) | |
363 | { | |
364 | return single_flag_show(kobj, attr, buf, | |
365 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
366 | } | |
367 | static ssize_t use_zero_page_store(struct kobject *kobj, | |
368 | struct kobj_attribute *attr, const char *buf, size_t count) | |
369 | { | |
370 | return single_flag_store(kobj, attr, buf, count, | |
371 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
372 | } | |
373 | static struct kobj_attribute use_zero_page_attr = | |
374 | __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); | |
71e3aac0 AA |
375 | #ifdef CONFIG_DEBUG_VM |
376 | static ssize_t debug_cow_show(struct kobject *kobj, | |
377 | struct kobj_attribute *attr, char *buf) | |
378 | { | |
379 | return single_flag_show(kobj, attr, buf, | |
380 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
381 | } | |
382 | static ssize_t debug_cow_store(struct kobject *kobj, | |
383 | struct kobj_attribute *attr, | |
384 | const char *buf, size_t count) | |
385 | { | |
386 | return single_flag_store(kobj, attr, buf, count, | |
387 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
388 | } | |
389 | static struct kobj_attribute debug_cow_attr = | |
390 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
391 | #endif /* CONFIG_DEBUG_VM */ | |
392 | ||
393 | static struct attribute *hugepage_attr[] = { | |
394 | &enabled_attr.attr, | |
395 | &defrag_attr.attr, | |
79da5407 | 396 | &use_zero_page_attr.attr, |
71e3aac0 AA |
397 | #ifdef CONFIG_DEBUG_VM |
398 | &debug_cow_attr.attr, | |
399 | #endif | |
400 | NULL, | |
401 | }; | |
402 | ||
403 | static struct attribute_group hugepage_attr_group = { | |
404 | .attrs = hugepage_attr, | |
ba76149f AA |
405 | }; |
406 | ||
407 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, | |
408 | struct kobj_attribute *attr, | |
409 | char *buf) | |
410 | { | |
411 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
412 | } | |
413 | ||
414 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
415 | struct kobj_attribute *attr, | |
416 | const char *buf, size_t count) | |
417 | { | |
418 | unsigned long msecs; | |
419 | int err; | |
420 | ||
421 | err = strict_strtoul(buf, 10, &msecs); | |
422 | if (err || msecs > UINT_MAX) | |
423 | return -EINVAL; | |
424 | ||
425 | khugepaged_scan_sleep_millisecs = msecs; | |
426 | wake_up_interruptible(&khugepaged_wait); | |
427 | ||
428 | return count; | |
429 | } | |
430 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
431 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
432 | scan_sleep_millisecs_store); | |
433 | ||
434 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
435 | struct kobj_attribute *attr, | |
436 | char *buf) | |
437 | { | |
438 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
439 | } | |
440 | ||
441 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
442 | struct kobj_attribute *attr, | |
443 | const char *buf, size_t count) | |
444 | { | |
445 | unsigned long msecs; | |
446 | int err; | |
447 | ||
448 | err = strict_strtoul(buf, 10, &msecs); | |
449 | if (err || msecs > UINT_MAX) | |
450 | return -EINVAL; | |
451 | ||
452 | khugepaged_alloc_sleep_millisecs = msecs; | |
453 | wake_up_interruptible(&khugepaged_wait); | |
454 | ||
455 | return count; | |
456 | } | |
457 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
458 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
459 | alloc_sleep_millisecs_store); | |
460 | ||
461 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
462 | struct kobj_attribute *attr, | |
463 | char *buf) | |
464 | { | |
465 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
466 | } | |
467 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
468 | struct kobj_attribute *attr, | |
469 | const char *buf, size_t count) | |
470 | { | |
471 | int err; | |
472 | unsigned long pages; | |
473 | ||
474 | err = strict_strtoul(buf, 10, &pages); | |
475 | if (err || !pages || pages > UINT_MAX) | |
476 | return -EINVAL; | |
477 | ||
478 | khugepaged_pages_to_scan = pages; | |
479 | ||
480 | return count; | |
481 | } | |
482 | static struct kobj_attribute pages_to_scan_attr = | |
483 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
484 | pages_to_scan_store); | |
485 | ||
486 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
487 | struct kobj_attribute *attr, | |
488 | char *buf) | |
489 | { | |
490 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
491 | } | |
492 | static struct kobj_attribute pages_collapsed_attr = | |
493 | __ATTR_RO(pages_collapsed); | |
494 | ||
495 | static ssize_t full_scans_show(struct kobject *kobj, | |
496 | struct kobj_attribute *attr, | |
497 | char *buf) | |
498 | { | |
499 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
500 | } | |
501 | static struct kobj_attribute full_scans_attr = | |
502 | __ATTR_RO(full_scans); | |
503 | ||
504 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
505 | struct kobj_attribute *attr, char *buf) | |
506 | { | |
507 | return single_flag_show(kobj, attr, buf, | |
508 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
509 | } | |
510 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
511 | struct kobj_attribute *attr, | |
512 | const char *buf, size_t count) | |
513 | { | |
514 | return single_flag_store(kobj, attr, buf, count, | |
515 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
516 | } | |
517 | static struct kobj_attribute khugepaged_defrag_attr = | |
518 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
519 | khugepaged_defrag_store); | |
520 | ||
521 | /* | |
522 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
523 | * any unmapped ptes in turn potentially increasing the memory | |
524 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
525 | * reduce the available free memory in the system as it | |
526 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
527 | * free memory in the system during the khugepaged scan. | |
528 | */ | |
529 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
530 | struct kobj_attribute *attr, | |
531 | char *buf) | |
532 | { | |
533 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
534 | } | |
535 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
536 | struct kobj_attribute *attr, | |
537 | const char *buf, size_t count) | |
538 | { | |
539 | int err; | |
540 | unsigned long max_ptes_none; | |
541 | ||
542 | err = strict_strtoul(buf, 10, &max_ptes_none); | |
543 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
544 | return -EINVAL; | |
545 | ||
546 | khugepaged_max_ptes_none = max_ptes_none; | |
547 | ||
548 | return count; | |
549 | } | |
550 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
551 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
552 | khugepaged_max_ptes_none_store); | |
553 | ||
554 | static struct attribute *khugepaged_attr[] = { | |
555 | &khugepaged_defrag_attr.attr, | |
556 | &khugepaged_max_ptes_none_attr.attr, | |
557 | &pages_to_scan_attr.attr, | |
558 | &pages_collapsed_attr.attr, | |
559 | &full_scans_attr.attr, | |
560 | &scan_sleep_millisecs_attr.attr, | |
561 | &alloc_sleep_millisecs_attr.attr, | |
562 | NULL, | |
563 | }; | |
564 | ||
565 | static struct attribute_group khugepaged_attr_group = { | |
566 | .attrs = khugepaged_attr, | |
567 | .name = "khugepaged", | |
71e3aac0 | 568 | }; |
71e3aac0 | 569 | |
569e5590 | 570 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
71e3aac0 | 571 | { |
71e3aac0 AA |
572 | int err; |
573 | ||
569e5590 SL |
574 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); |
575 | if (unlikely(!*hugepage_kobj)) { | |
2c79737a | 576 | printk(KERN_ERR "hugepage: failed to create transparent hugepage kobject\n"); |
569e5590 | 577 | return -ENOMEM; |
ba76149f AA |
578 | } |
579 | ||
569e5590 | 580 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); |
ba76149f | 581 | if (err) { |
2c79737a | 582 | printk(KERN_ERR "hugepage: failed to register transparent hugepage group\n"); |
569e5590 | 583 | goto delete_obj; |
ba76149f AA |
584 | } |
585 | ||
569e5590 | 586 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); |
ba76149f | 587 | if (err) { |
2c79737a | 588 | printk(KERN_ERR "hugepage: failed to register transparent hugepage group\n"); |
569e5590 | 589 | goto remove_hp_group; |
ba76149f | 590 | } |
569e5590 SL |
591 | |
592 | return 0; | |
593 | ||
594 | remove_hp_group: | |
595 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
596 | delete_obj: | |
597 | kobject_put(*hugepage_kobj); | |
598 | return err; | |
599 | } | |
600 | ||
601 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
602 | { | |
603 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
604 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
605 | kobject_put(hugepage_kobj); | |
606 | } | |
607 | #else | |
608 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
609 | { | |
610 | return 0; | |
611 | } | |
612 | ||
613 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
614 | { | |
615 | } | |
616 | #endif /* CONFIG_SYSFS */ | |
617 | ||
618 | static int __init hugepage_init(void) | |
619 | { | |
620 | int err; | |
621 | struct kobject *hugepage_kobj; | |
622 | ||
623 | if (!has_transparent_hugepage()) { | |
624 | transparent_hugepage_flags = 0; | |
625 | return -EINVAL; | |
626 | } | |
627 | ||
628 | err = hugepage_init_sysfs(&hugepage_kobj); | |
629 | if (err) | |
630 | return err; | |
ba76149f AA |
631 | |
632 | err = khugepaged_slab_init(); | |
633 | if (err) | |
634 | goto out; | |
635 | ||
97ae1749 KS |
636 | register_shrinker(&huge_zero_page_shrinker); |
637 | ||
97562cd2 RR |
638 | /* |
639 | * By default disable transparent hugepages on smaller systems, | |
640 | * where the extra memory used could hurt more than TLB overhead | |
641 | * is likely to save. The admin can still enable it through /sys. | |
642 | */ | |
643 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) | |
644 | transparent_hugepage_flags = 0; | |
645 | ||
ba76149f AA |
646 | start_khugepaged(); |
647 | ||
569e5590 | 648 | return 0; |
ba76149f | 649 | out: |
569e5590 | 650 | hugepage_exit_sysfs(hugepage_kobj); |
ba76149f | 651 | return err; |
71e3aac0 AA |
652 | } |
653 | module_init(hugepage_init) | |
654 | ||
655 | static int __init setup_transparent_hugepage(char *str) | |
656 | { | |
657 | int ret = 0; | |
658 | if (!str) | |
659 | goto out; | |
660 | if (!strcmp(str, "always")) { | |
661 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
662 | &transparent_hugepage_flags); | |
663 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
664 | &transparent_hugepage_flags); | |
665 | ret = 1; | |
666 | } else if (!strcmp(str, "madvise")) { | |
667 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
668 | &transparent_hugepage_flags); | |
669 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
670 | &transparent_hugepage_flags); | |
671 | ret = 1; | |
672 | } else if (!strcmp(str, "never")) { | |
673 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
674 | &transparent_hugepage_flags); | |
675 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
676 | &transparent_hugepage_flags); | |
677 | ret = 1; | |
678 | } | |
679 | out: | |
680 | if (!ret) | |
681 | printk(KERN_WARNING | |
682 | "transparent_hugepage= cannot parse, ignored\n"); | |
683 | return ret; | |
684 | } | |
685 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
686 | ||
b32967ff | 687 | pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) |
71e3aac0 AA |
688 | { |
689 | if (likely(vma->vm_flags & VM_WRITE)) | |
690 | pmd = pmd_mkwrite(pmd); | |
691 | return pmd; | |
692 | } | |
693 | ||
b3092b3b BL |
694 | static inline pmd_t mk_huge_pmd(struct page *page, struct vm_area_struct *vma) |
695 | { | |
696 | pmd_t entry; | |
697 | entry = mk_pmd(page, vma->vm_page_prot); | |
698 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
699 | entry = pmd_mkhuge(entry); | |
700 | return entry; | |
701 | } | |
702 | ||
71e3aac0 AA |
703 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, |
704 | struct vm_area_struct *vma, | |
705 | unsigned long haddr, pmd_t *pmd, | |
706 | struct page *page) | |
707 | { | |
71e3aac0 AA |
708 | pgtable_t pgtable; |
709 | ||
710 | VM_BUG_ON(!PageCompound(page)); | |
711 | pgtable = pte_alloc_one(mm, haddr); | |
edad9d2c | 712 | if (unlikely(!pgtable)) |
71e3aac0 | 713 | return VM_FAULT_OOM; |
71e3aac0 AA |
714 | |
715 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
716 | __SetPageUptodate(page); | |
717 | ||
718 | spin_lock(&mm->page_table_lock); | |
719 | if (unlikely(!pmd_none(*pmd))) { | |
720 | spin_unlock(&mm->page_table_lock); | |
b9bbfbe3 | 721 | mem_cgroup_uncharge_page(page); |
71e3aac0 AA |
722 | put_page(page); |
723 | pte_free(mm, pgtable); | |
724 | } else { | |
725 | pmd_t entry; | |
b3092b3b | 726 | entry = mk_huge_pmd(page, vma); |
71e3aac0 AA |
727 | /* |
728 | * The spinlocking to take the lru_lock inside | |
729 | * page_add_new_anon_rmap() acts as a full memory | |
730 | * barrier to be sure clear_huge_page writes become | |
731 | * visible after the set_pmd_at() write. | |
732 | */ | |
733 | page_add_new_anon_rmap(page, vma, haddr); | |
734 | set_pmd_at(mm, haddr, pmd, entry); | |
e3ebcf64 | 735 | pgtable_trans_huge_deposit(mm, pgtable); |
71e3aac0 | 736 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
1c641e84 | 737 | mm->nr_ptes++; |
71e3aac0 AA |
738 | spin_unlock(&mm->page_table_lock); |
739 | } | |
740 | ||
aa2e878e | 741 | return 0; |
71e3aac0 AA |
742 | } |
743 | ||
cc5d462f | 744 | static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp) |
0bbbc0b3 | 745 | { |
cc5d462f | 746 | return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp; |
0bbbc0b3 AA |
747 | } |
748 | ||
749 | static inline struct page *alloc_hugepage_vma(int defrag, | |
750 | struct vm_area_struct *vma, | |
cc5d462f AK |
751 | unsigned long haddr, int nd, |
752 | gfp_t extra_gfp) | |
0bbbc0b3 | 753 | { |
cc5d462f | 754 | return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp), |
5c4b4be3 | 755 | HPAGE_PMD_ORDER, vma, haddr, nd); |
0bbbc0b3 AA |
756 | } |
757 | ||
758 | #ifndef CONFIG_NUMA | |
71e3aac0 AA |
759 | static inline struct page *alloc_hugepage(int defrag) |
760 | { | |
cc5d462f | 761 | return alloc_pages(alloc_hugepage_gfpmask(defrag, 0), |
71e3aac0 AA |
762 | HPAGE_PMD_ORDER); |
763 | } | |
0bbbc0b3 | 764 | #endif |
71e3aac0 | 765 | |
3ea41e62 | 766 | static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, |
97ae1749 KS |
767 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, |
768 | unsigned long zero_pfn) | |
fc9fe822 KS |
769 | { |
770 | pmd_t entry; | |
3ea41e62 KS |
771 | if (!pmd_none(*pmd)) |
772 | return false; | |
97ae1749 | 773 | entry = pfn_pmd(zero_pfn, vma->vm_page_prot); |
fc9fe822 KS |
774 | entry = pmd_wrprotect(entry); |
775 | entry = pmd_mkhuge(entry); | |
776 | set_pmd_at(mm, haddr, pmd, entry); | |
777 | pgtable_trans_huge_deposit(mm, pgtable); | |
778 | mm->nr_ptes++; | |
3ea41e62 | 779 | return true; |
fc9fe822 KS |
780 | } |
781 | ||
71e3aac0 AA |
782 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, |
783 | unsigned long address, pmd_t *pmd, | |
784 | unsigned int flags) | |
785 | { | |
786 | struct page *page; | |
787 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
788 | pte_t *pte; | |
789 | ||
790 | if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) { | |
791 | if (unlikely(anon_vma_prepare(vma))) | |
792 | return VM_FAULT_OOM; | |
ba76149f AA |
793 | if (unlikely(khugepaged_enter(vma))) |
794 | return VM_FAULT_OOM; | |
79da5407 KS |
795 | if (!(flags & FAULT_FLAG_WRITE) && |
796 | transparent_hugepage_use_zero_page()) { | |
80371957 | 797 | pgtable_t pgtable; |
97ae1749 | 798 | unsigned long zero_pfn; |
3ea41e62 | 799 | bool set; |
80371957 KS |
800 | pgtable = pte_alloc_one(mm, haddr); |
801 | if (unlikely(!pgtable)) | |
802 | return VM_FAULT_OOM; | |
97ae1749 KS |
803 | zero_pfn = get_huge_zero_page(); |
804 | if (unlikely(!zero_pfn)) { | |
805 | pte_free(mm, pgtable); | |
806 | count_vm_event(THP_FAULT_FALLBACK); | |
807 | goto out; | |
808 | } | |
80371957 | 809 | spin_lock(&mm->page_table_lock); |
3ea41e62 | 810 | set = set_huge_zero_page(pgtable, mm, vma, haddr, pmd, |
97ae1749 | 811 | zero_pfn); |
80371957 | 812 | spin_unlock(&mm->page_table_lock); |
3ea41e62 KS |
813 | if (!set) { |
814 | pte_free(mm, pgtable); | |
815 | put_huge_zero_page(); | |
816 | } | |
80371957 KS |
817 | return 0; |
818 | } | |
0bbbc0b3 | 819 | page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
cc5d462f | 820 | vma, haddr, numa_node_id(), 0); |
81ab4201 AK |
821 | if (unlikely(!page)) { |
822 | count_vm_event(THP_FAULT_FALLBACK); | |
71e3aac0 | 823 | goto out; |
81ab4201 AK |
824 | } |
825 | count_vm_event(THP_FAULT_ALLOC); | |
b9bbfbe3 AA |
826 | if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) { |
827 | put_page(page); | |
828 | goto out; | |
829 | } | |
edad9d2c DR |
830 | if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, |
831 | page))) { | |
832 | mem_cgroup_uncharge_page(page); | |
833 | put_page(page); | |
834 | goto out; | |
835 | } | |
71e3aac0 | 836 | |
edad9d2c | 837 | return 0; |
71e3aac0 AA |
838 | } |
839 | out: | |
840 | /* | |
841 | * Use __pte_alloc instead of pte_alloc_map, because we can't | |
842 | * run pte_offset_map on the pmd, if an huge pmd could | |
843 | * materialize from under us from a different thread. | |
844 | */ | |
4fd01770 MG |
845 | if (unlikely(pmd_none(*pmd)) && |
846 | unlikely(__pte_alloc(mm, vma, pmd, address))) | |
71e3aac0 AA |
847 | return VM_FAULT_OOM; |
848 | /* if an huge pmd materialized from under us just retry later */ | |
849 | if (unlikely(pmd_trans_huge(*pmd))) | |
850 | return 0; | |
851 | /* | |
852 | * A regular pmd is established and it can't morph into a huge pmd | |
853 | * from under us anymore at this point because we hold the mmap_sem | |
854 | * read mode and khugepaged takes it in write mode. So now it's | |
855 | * safe to run pte_offset_map(). | |
856 | */ | |
857 | pte = pte_offset_map(pmd, address); | |
858 | return handle_pte_fault(mm, vma, address, pte, pmd, flags); | |
859 | } | |
860 | ||
861 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, | |
862 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
863 | struct vm_area_struct *vma) | |
864 | { | |
865 | struct page *src_page; | |
866 | pmd_t pmd; | |
867 | pgtable_t pgtable; | |
868 | int ret; | |
869 | ||
870 | ret = -ENOMEM; | |
871 | pgtable = pte_alloc_one(dst_mm, addr); | |
872 | if (unlikely(!pgtable)) | |
873 | goto out; | |
874 | ||
875 | spin_lock(&dst_mm->page_table_lock); | |
876 | spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING); | |
877 | ||
878 | ret = -EAGAIN; | |
879 | pmd = *src_pmd; | |
880 | if (unlikely(!pmd_trans_huge(pmd))) { | |
881 | pte_free(dst_mm, pgtable); | |
882 | goto out_unlock; | |
883 | } | |
fc9fe822 KS |
884 | /* |
885 | * mm->page_table_lock is enough to be sure that huge zero pmd is not | |
886 | * under splitting since we don't split the page itself, only pmd to | |
887 | * a page table. | |
888 | */ | |
889 | if (is_huge_zero_pmd(pmd)) { | |
97ae1749 | 890 | unsigned long zero_pfn; |
3ea41e62 | 891 | bool set; |
97ae1749 KS |
892 | /* |
893 | * get_huge_zero_page() will never allocate a new page here, | |
894 | * since we already have a zero page to copy. It just takes a | |
895 | * reference. | |
896 | */ | |
897 | zero_pfn = get_huge_zero_page(); | |
3ea41e62 | 898 | set = set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, |
97ae1749 | 899 | zero_pfn); |
3ea41e62 | 900 | BUG_ON(!set); /* unexpected !pmd_none(dst_pmd) */ |
fc9fe822 KS |
901 | ret = 0; |
902 | goto out_unlock; | |
903 | } | |
71e3aac0 AA |
904 | if (unlikely(pmd_trans_splitting(pmd))) { |
905 | /* split huge page running from under us */ | |
906 | spin_unlock(&src_mm->page_table_lock); | |
907 | spin_unlock(&dst_mm->page_table_lock); | |
908 | pte_free(dst_mm, pgtable); | |
909 | ||
910 | wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */ | |
911 | goto out; | |
912 | } | |
913 | src_page = pmd_page(pmd); | |
914 | VM_BUG_ON(!PageHead(src_page)); | |
915 | get_page(src_page); | |
916 | page_dup_rmap(src_page); | |
917 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
918 | ||
919 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
920 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
921 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
e3ebcf64 | 922 | pgtable_trans_huge_deposit(dst_mm, pgtable); |
1c641e84 | 923 | dst_mm->nr_ptes++; |
71e3aac0 AA |
924 | |
925 | ret = 0; | |
926 | out_unlock: | |
927 | spin_unlock(&src_mm->page_table_lock); | |
928 | spin_unlock(&dst_mm->page_table_lock); | |
929 | out: | |
930 | return ret; | |
931 | } | |
932 | ||
a1dd450b WD |
933 | void huge_pmd_set_accessed(struct mm_struct *mm, |
934 | struct vm_area_struct *vma, | |
935 | unsigned long address, | |
936 | pmd_t *pmd, pmd_t orig_pmd, | |
937 | int dirty) | |
938 | { | |
939 | pmd_t entry; | |
940 | unsigned long haddr; | |
941 | ||
942 | spin_lock(&mm->page_table_lock); | |
943 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
944 | goto unlock; | |
945 | ||
946 | entry = pmd_mkyoung(orig_pmd); | |
947 | haddr = address & HPAGE_PMD_MASK; | |
948 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty)) | |
949 | update_mmu_cache_pmd(vma, address, pmd); | |
950 | ||
951 | unlock: | |
952 | spin_unlock(&mm->page_table_lock); | |
953 | } | |
954 | ||
93b4796d KS |
955 | static int do_huge_pmd_wp_zero_page_fallback(struct mm_struct *mm, |
956 | struct vm_area_struct *vma, unsigned long address, | |
3ea41e62 | 957 | pmd_t *pmd, pmd_t orig_pmd, unsigned long haddr) |
93b4796d KS |
958 | { |
959 | pgtable_t pgtable; | |
960 | pmd_t _pmd; | |
961 | struct page *page; | |
962 | int i, ret = 0; | |
963 | unsigned long mmun_start; /* For mmu_notifiers */ | |
964 | unsigned long mmun_end; /* For mmu_notifiers */ | |
965 | ||
966 | page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); | |
967 | if (!page) { | |
968 | ret |= VM_FAULT_OOM; | |
969 | goto out; | |
970 | } | |
971 | ||
972 | if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) { | |
973 | put_page(page); | |
974 | ret |= VM_FAULT_OOM; | |
975 | goto out; | |
976 | } | |
977 | ||
978 | clear_user_highpage(page, address); | |
979 | __SetPageUptodate(page); | |
980 | ||
981 | mmun_start = haddr; | |
982 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
983 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
984 | ||
985 | spin_lock(&mm->page_table_lock); | |
3ea41e62 KS |
986 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
987 | goto out_free_page; | |
988 | ||
93b4796d KS |
989 | pmdp_clear_flush(vma, haddr, pmd); |
990 | /* leave pmd empty until pte is filled */ | |
991 | ||
992 | pgtable = pgtable_trans_huge_withdraw(mm); | |
993 | pmd_populate(mm, &_pmd, pgtable); | |
994 | ||
995 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
996 | pte_t *pte, entry; | |
997 | if (haddr == (address & PAGE_MASK)) { | |
998 | entry = mk_pte(page, vma->vm_page_prot); | |
999 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
1000 | page_add_new_anon_rmap(page, vma, haddr); | |
1001 | } else { | |
1002 | entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); | |
1003 | entry = pte_mkspecial(entry); | |
1004 | } | |
1005 | pte = pte_offset_map(&_pmd, haddr); | |
1006 | VM_BUG_ON(!pte_none(*pte)); | |
1007 | set_pte_at(mm, haddr, pte, entry); | |
1008 | pte_unmap(pte); | |
1009 | } | |
1010 | smp_wmb(); /* make pte visible before pmd */ | |
1011 | pmd_populate(mm, pmd, pgtable); | |
1012 | spin_unlock(&mm->page_table_lock); | |
97ae1749 | 1013 | put_huge_zero_page(); |
93b4796d KS |
1014 | inc_mm_counter(mm, MM_ANONPAGES); |
1015 | ||
1016 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
1017 | ||
1018 | ret |= VM_FAULT_WRITE; | |
1019 | out: | |
1020 | return ret; | |
3ea41e62 KS |
1021 | out_free_page: |
1022 | spin_unlock(&mm->page_table_lock); | |
1023 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
1024 | mem_cgroup_uncharge_page(page); | |
1025 | put_page(page); | |
1026 | goto out; | |
93b4796d KS |
1027 | } |
1028 | ||
71e3aac0 AA |
1029 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, |
1030 | struct vm_area_struct *vma, | |
1031 | unsigned long address, | |
1032 | pmd_t *pmd, pmd_t orig_pmd, | |
1033 | struct page *page, | |
1034 | unsigned long haddr) | |
1035 | { | |
1036 | pgtable_t pgtable; | |
1037 | pmd_t _pmd; | |
1038 | int ret = 0, i; | |
1039 | struct page **pages; | |
2ec74c3e SG |
1040 | unsigned long mmun_start; /* For mmu_notifiers */ |
1041 | unsigned long mmun_end; /* For mmu_notifiers */ | |
71e3aac0 AA |
1042 | |
1043 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
1044 | GFP_KERNEL); | |
1045 | if (unlikely(!pages)) { | |
1046 | ret |= VM_FAULT_OOM; | |
1047 | goto out; | |
1048 | } | |
1049 | ||
1050 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
cc5d462f AK |
1051 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE | |
1052 | __GFP_OTHER_NODE, | |
19ee151e | 1053 | vma, address, page_to_nid(page)); |
b9bbfbe3 AA |
1054 | if (unlikely(!pages[i] || |
1055 | mem_cgroup_newpage_charge(pages[i], mm, | |
1056 | GFP_KERNEL))) { | |
1057 | if (pages[i]) | |
71e3aac0 | 1058 | put_page(pages[i]); |
b9bbfbe3 AA |
1059 | mem_cgroup_uncharge_start(); |
1060 | while (--i >= 0) { | |
1061 | mem_cgroup_uncharge_page(pages[i]); | |
1062 | put_page(pages[i]); | |
1063 | } | |
1064 | mem_cgroup_uncharge_end(); | |
71e3aac0 AA |
1065 | kfree(pages); |
1066 | ret |= VM_FAULT_OOM; | |
1067 | goto out; | |
1068 | } | |
1069 | } | |
1070 | ||
1071 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1072 | copy_user_highpage(pages[i], page + i, | |
0089e485 | 1073 | haddr + PAGE_SIZE * i, vma); |
71e3aac0 AA |
1074 | __SetPageUptodate(pages[i]); |
1075 | cond_resched(); | |
1076 | } | |
1077 | ||
2ec74c3e SG |
1078 | mmun_start = haddr; |
1079 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1080 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1081 | ||
71e3aac0 AA |
1082 | spin_lock(&mm->page_table_lock); |
1083 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
1084 | goto out_free_pages; | |
1085 | VM_BUG_ON(!PageHead(page)); | |
1086 | ||
2ec74c3e | 1087 | pmdp_clear_flush(vma, haddr, pmd); |
71e3aac0 AA |
1088 | /* leave pmd empty until pte is filled */ |
1089 | ||
e3ebcf64 | 1090 | pgtable = pgtable_trans_huge_withdraw(mm); |
71e3aac0 AA |
1091 | pmd_populate(mm, &_pmd, pgtable); |
1092 | ||
1093 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
1094 | pte_t *pte, entry; | |
1095 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
1096 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
1097 | page_add_new_anon_rmap(pages[i], vma, haddr); | |
1098 | pte = pte_offset_map(&_pmd, haddr); | |
1099 | VM_BUG_ON(!pte_none(*pte)); | |
1100 | set_pte_at(mm, haddr, pte, entry); | |
1101 | pte_unmap(pte); | |
1102 | } | |
1103 | kfree(pages); | |
1104 | ||
71e3aac0 AA |
1105 | smp_wmb(); /* make pte visible before pmd */ |
1106 | pmd_populate(mm, pmd, pgtable); | |
1107 | page_remove_rmap(page); | |
1108 | spin_unlock(&mm->page_table_lock); | |
1109 | ||
2ec74c3e SG |
1110 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
1111 | ||
71e3aac0 AA |
1112 | ret |= VM_FAULT_WRITE; |
1113 | put_page(page); | |
1114 | ||
1115 | out: | |
1116 | return ret; | |
1117 | ||
1118 | out_free_pages: | |
1119 | spin_unlock(&mm->page_table_lock); | |
2ec74c3e | 1120 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
b9bbfbe3 AA |
1121 | mem_cgroup_uncharge_start(); |
1122 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1123 | mem_cgroup_uncharge_page(pages[i]); | |
71e3aac0 | 1124 | put_page(pages[i]); |
b9bbfbe3 AA |
1125 | } |
1126 | mem_cgroup_uncharge_end(); | |
71e3aac0 AA |
1127 | kfree(pages); |
1128 | goto out; | |
1129 | } | |
1130 | ||
1131 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
1132 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) | |
1133 | { | |
1134 | int ret = 0; | |
93b4796d | 1135 | struct page *page = NULL, *new_page; |
71e3aac0 | 1136 | unsigned long haddr; |
2ec74c3e SG |
1137 | unsigned long mmun_start; /* For mmu_notifiers */ |
1138 | unsigned long mmun_end; /* For mmu_notifiers */ | |
71e3aac0 AA |
1139 | |
1140 | VM_BUG_ON(!vma->anon_vma); | |
93b4796d KS |
1141 | haddr = address & HPAGE_PMD_MASK; |
1142 | if (is_huge_zero_pmd(orig_pmd)) | |
1143 | goto alloc; | |
71e3aac0 AA |
1144 | spin_lock(&mm->page_table_lock); |
1145 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
1146 | goto out_unlock; | |
1147 | ||
1148 | page = pmd_page(orig_pmd); | |
1149 | VM_BUG_ON(!PageCompound(page) || !PageHead(page)); | |
71e3aac0 AA |
1150 | if (page_mapcount(page) == 1) { |
1151 | pmd_t entry; | |
1152 | entry = pmd_mkyoung(orig_pmd); | |
1153 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
1154 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) | |
b113da65 | 1155 | update_mmu_cache_pmd(vma, address, pmd); |
71e3aac0 AA |
1156 | ret |= VM_FAULT_WRITE; |
1157 | goto out_unlock; | |
1158 | } | |
1159 | get_page(page); | |
1160 | spin_unlock(&mm->page_table_lock); | |
93b4796d | 1161 | alloc: |
71e3aac0 AA |
1162 | if (transparent_hugepage_enabled(vma) && |
1163 | !transparent_hugepage_debug_cow()) | |
0bbbc0b3 | 1164 | new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
cc5d462f | 1165 | vma, haddr, numa_node_id(), 0); |
71e3aac0 AA |
1166 | else |
1167 | new_page = NULL; | |
1168 | ||
1169 | if (unlikely(!new_page)) { | |
81ab4201 | 1170 | count_vm_event(THP_FAULT_FALLBACK); |
93b4796d KS |
1171 | if (is_huge_zero_pmd(orig_pmd)) { |
1172 | ret = do_huge_pmd_wp_zero_page_fallback(mm, vma, | |
3ea41e62 | 1173 | address, pmd, orig_pmd, haddr); |
93b4796d KS |
1174 | } else { |
1175 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, | |
1176 | pmd, orig_pmd, page, haddr); | |
1177 | if (ret & VM_FAULT_OOM) | |
1178 | split_huge_page(page); | |
1179 | put_page(page); | |
1180 | } | |
71e3aac0 AA |
1181 | goto out; |
1182 | } | |
81ab4201 | 1183 | count_vm_event(THP_FAULT_ALLOC); |
71e3aac0 | 1184 | |
b9bbfbe3 AA |
1185 | if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) { |
1186 | put_page(new_page); | |
93b4796d KS |
1187 | if (page) { |
1188 | split_huge_page(page); | |
1189 | put_page(page); | |
1190 | } | |
b9bbfbe3 AA |
1191 | ret |= VM_FAULT_OOM; |
1192 | goto out; | |
1193 | } | |
1194 | ||
93b4796d KS |
1195 | if (is_huge_zero_pmd(orig_pmd)) |
1196 | clear_huge_page(new_page, haddr, HPAGE_PMD_NR); | |
1197 | else | |
1198 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); | |
71e3aac0 AA |
1199 | __SetPageUptodate(new_page); |
1200 | ||
2ec74c3e SG |
1201 | mmun_start = haddr; |
1202 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1203 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1204 | ||
71e3aac0 | 1205 | spin_lock(&mm->page_table_lock); |
93b4796d KS |
1206 | if (page) |
1207 | put_page(page); | |
b9bbfbe3 | 1208 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { |
6f60b69d | 1209 | spin_unlock(&mm->page_table_lock); |
b9bbfbe3 | 1210 | mem_cgroup_uncharge_page(new_page); |
71e3aac0 | 1211 | put_page(new_page); |
2ec74c3e | 1212 | goto out_mn; |
b9bbfbe3 | 1213 | } else { |
71e3aac0 | 1214 | pmd_t entry; |
b3092b3b | 1215 | entry = mk_huge_pmd(new_page, vma); |
2ec74c3e | 1216 | pmdp_clear_flush(vma, haddr, pmd); |
71e3aac0 AA |
1217 | page_add_new_anon_rmap(new_page, vma, haddr); |
1218 | set_pmd_at(mm, haddr, pmd, entry); | |
b113da65 | 1219 | update_mmu_cache_pmd(vma, address, pmd); |
97ae1749 | 1220 | if (is_huge_zero_pmd(orig_pmd)) { |
93b4796d | 1221 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
97ae1749 KS |
1222 | put_huge_zero_page(); |
1223 | } else { | |
93b4796d KS |
1224 | VM_BUG_ON(!PageHead(page)); |
1225 | page_remove_rmap(page); | |
1226 | put_page(page); | |
1227 | } | |
71e3aac0 AA |
1228 | ret |= VM_FAULT_WRITE; |
1229 | } | |
71e3aac0 | 1230 | spin_unlock(&mm->page_table_lock); |
2ec74c3e SG |
1231 | out_mn: |
1232 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
71e3aac0 AA |
1233 | out: |
1234 | return ret; | |
2ec74c3e SG |
1235 | out_unlock: |
1236 | spin_unlock(&mm->page_table_lock); | |
1237 | return ret; | |
71e3aac0 AA |
1238 | } |
1239 | ||
b676b293 | 1240 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, |
71e3aac0 AA |
1241 | unsigned long addr, |
1242 | pmd_t *pmd, | |
1243 | unsigned int flags) | |
1244 | { | |
b676b293 | 1245 | struct mm_struct *mm = vma->vm_mm; |
71e3aac0 AA |
1246 | struct page *page = NULL; |
1247 | ||
1248 | assert_spin_locked(&mm->page_table_lock); | |
1249 | ||
1250 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1251 | goto out; | |
1252 | ||
85facf25 KS |
1253 | /* Avoid dumping huge zero page */ |
1254 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) | |
1255 | return ERR_PTR(-EFAULT); | |
1256 | ||
71e3aac0 AA |
1257 | page = pmd_page(*pmd); |
1258 | VM_BUG_ON(!PageHead(page)); | |
1259 | if (flags & FOLL_TOUCH) { | |
1260 | pmd_t _pmd; | |
1261 | /* | |
1262 | * We should set the dirty bit only for FOLL_WRITE but | |
1263 | * for now the dirty bit in the pmd is meaningless. | |
1264 | * And if the dirty bit will become meaningful and | |
1265 | * we'll only set it with FOLL_WRITE, an atomic | |
1266 | * set_bit will be required on the pmd to set the | |
1267 | * young bit, instead of the current set_pmd_at. | |
1268 | */ | |
1269 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
1270 | set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd); | |
1271 | } | |
b676b293 DR |
1272 | if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { |
1273 | if (page->mapping && trylock_page(page)) { | |
1274 | lru_add_drain(); | |
1275 | if (page->mapping) | |
1276 | mlock_vma_page(page); | |
1277 | unlock_page(page); | |
1278 | } | |
1279 | } | |
71e3aac0 AA |
1280 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
1281 | VM_BUG_ON(!PageCompound(page)); | |
1282 | if (flags & FOLL_GET) | |
70b50f94 | 1283 | get_page_foll(page); |
71e3aac0 AA |
1284 | |
1285 | out: | |
1286 | return page; | |
1287 | } | |
1288 | ||
d10e63f2 | 1289 | /* NUMA hinting page fault entry point for trans huge pmds */ |
4daae3b4 MG |
1290 | int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, |
1291 | unsigned long addr, pmd_t pmd, pmd_t *pmdp) | |
d10e63f2 | 1292 | { |
b32967ff | 1293 | struct page *page; |
d10e63f2 | 1294 | unsigned long haddr = addr & HPAGE_PMD_MASK; |
4daae3b4 | 1295 | int target_nid; |
03c5a6e1 | 1296 | int current_nid = -1; |
b32967ff | 1297 | bool migrated; |
d10e63f2 MG |
1298 | |
1299 | spin_lock(&mm->page_table_lock); | |
1300 | if (unlikely(!pmd_same(pmd, *pmdp))) | |
1301 | goto out_unlock; | |
1302 | ||
1303 | page = pmd_page(pmd); | |
4daae3b4 | 1304 | get_page(page); |
03c5a6e1 MG |
1305 | current_nid = page_to_nid(page); |
1306 | count_vm_numa_event(NUMA_HINT_FAULTS); | |
1307 | if (current_nid == numa_node_id()) | |
1308 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); | |
4daae3b4 MG |
1309 | |
1310 | target_nid = mpol_misplaced(page, vma, haddr); | |
b32967ff MG |
1311 | if (target_nid == -1) { |
1312 | put_page(page); | |
4daae3b4 | 1313 | goto clear_pmdnuma; |
b32967ff | 1314 | } |
4daae3b4 | 1315 | |
b32967ff MG |
1316 | /* Acquire the page lock to serialise THP migrations */ |
1317 | spin_unlock(&mm->page_table_lock); | |
1318 | lock_page(page); | |
4daae3b4 | 1319 | |
b32967ff | 1320 | /* Confirm the PTE did not while locked */ |
4daae3b4 | 1321 | spin_lock(&mm->page_table_lock); |
b32967ff MG |
1322 | if (unlikely(!pmd_same(pmd, *pmdp))) { |
1323 | unlock_page(page); | |
1324 | put_page(page); | |
4daae3b4 | 1325 | goto out_unlock; |
b32967ff MG |
1326 | } |
1327 | spin_unlock(&mm->page_table_lock); | |
4daae3b4 | 1328 | |
b32967ff MG |
1329 | /* Migrate the THP to the requested node */ |
1330 | migrated = migrate_misplaced_transhuge_page(mm, vma, | |
340ef390 HD |
1331 | pmdp, pmd, addr, page, target_nid); |
1332 | if (!migrated) | |
1333 | goto check_same; | |
b32967ff | 1334 | |
340ef390 | 1335 | task_numa_fault(target_nid, HPAGE_PMD_NR, true); |
b32967ff MG |
1336 | return 0; |
1337 | ||
340ef390 HD |
1338 | check_same: |
1339 | spin_lock(&mm->page_table_lock); | |
1340 | if (unlikely(!pmd_same(pmd, *pmdp))) | |
1341 | goto out_unlock; | |
b32967ff | 1342 | clear_pmdnuma: |
d10e63f2 MG |
1343 | pmd = pmd_mknonnuma(pmd); |
1344 | set_pmd_at(mm, haddr, pmdp, pmd); | |
1345 | VM_BUG_ON(pmd_numa(*pmdp)); | |
1346 | update_mmu_cache_pmd(vma, addr, pmdp); | |
d10e63f2 MG |
1347 | out_unlock: |
1348 | spin_unlock(&mm->page_table_lock); | |
b32967ff | 1349 | if (current_nid != -1) |
340ef390 | 1350 | task_numa_fault(current_nid, HPAGE_PMD_NR, false); |
d10e63f2 MG |
1351 | return 0; |
1352 | } | |
1353 | ||
71e3aac0 | 1354 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
f21760b1 | 1355 | pmd_t *pmd, unsigned long addr) |
71e3aac0 AA |
1356 | { |
1357 | int ret = 0; | |
1358 | ||
025c5b24 NH |
1359 | if (__pmd_trans_huge_lock(pmd, vma) == 1) { |
1360 | struct page *page; | |
1361 | pgtable_t pgtable; | |
f5c8ad47 | 1362 | pmd_t orig_pmd; |
e3ebcf64 | 1363 | pgtable = pgtable_trans_huge_withdraw(tlb->mm); |
f5c8ad47 | 1364 | orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd); |
025c5b24 | 1365 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); |
479f0abb KS |
1366 | if (is_huge_zero_pmd(orig_pmd)) { |
1367 | tlb->mm->nr_ptes--; | |
1368 | spin_unlock(&tlb->mm->page_table_lock); | |
97ae1749 | 1369 | put_huge_zero_page(); |
479f0abb KS |
1370 | } else { |
1371 | page = pmd_page(orig_pmd); | |
1372 | page_remove_rmap(page); | |
1373 | VM_BUG_ON(page_mapcount(page) < 0); | |
1374 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1375 | VM_BUG_ON(!PageHead(page)); | |
1376 | tlb->mm->nr_ptes--; | |
1377 | spin_unlock(&tlb->mm->page_table_lock); | |
1378 | tlb_remove_page(tlb, page); | |
1379 | } | |
025c5b24 NH |
1380 | pte_free(tlb->mm, pgtable); |
1381 | ret = 1; | |
1382 | } | |
71e3aac0 AA |
1383 | return ret; |
1384 | } | |
1385 | ||
0ca1634d JW |
1386 | int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
1387 | unsigned long addr, unsigned long end, | |
1388 | unsigned char *vec) | |
1389 | { | |
1390 | int ret = 0; | |
1391 | ||
025c5b24 NH |
1392 | if (__pmd_trans_huge_lock(pmd, vma) == 1) { |
1393 | /* | |
1394 | * All logical pages in the range are present | |
1395 | * if backed by a huge page. | |
1396 | */ | |
0ca1634d | 1397 | spin_unlock(&vma->vm_mm->page_table_lock); |
025c5b24 NH |
1398 | memset(vec, 1, (end - addr) >> PAGE_SHIFT); |
1399 | ret = 1; | |
1400 | } | |
0ca1634d JW |
1401 | |
1402 | return ret; | |
1403 | } | |
1404 | ||
37a1c49a AA |
1405 | int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, |
1406 | unsigned long old_addr, | |
1407 | unsigned long new_addr, unsigned long old_end, | |
1408 | pmd_t *old_pmd, pmd_t *new_pmd) | |
1409 | { | |
1410 | int ret = 0; | |
1411 | pmd_t pmd; | |
1412 | ||
1413 | struct mm_struct *mm = vma->vm_mm; | |
1414 | ||
1415 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1416 | (new_addr & ~HPAGE_PMD_MASK) || | |
1417 | old_end - old_addr < HPAGE_PMD_SIZE || | |
1418 | (new_vma->vm_flags & VM_NOHUGEPAGE)) | |
1419 | goto out; | |
1420 | ||
1421 | /* | |
1422 | * The destination pmd shouldn't be established, free_pgtables() | |
1423 | * should have release it. | |
1424 | */ | |
1425 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1426 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
1427 | goto out; | |
1428 | } | |
1429 | ||
025c5b24 NH |
1430 | ret = __pmd_trans_huge_lock(old_pmd, vma); |
1431 | if (ret == 1) { | |
1432 | pmd = pmdp_get_and_clear(mm, old_addr, old_pmd); | |
1433 | VM_BUG_ON(!pmd_none(*new_pmd)); | |
1434 | set_pmd_at(mm, new_addr, new_pmd, pmd); | |
37a1c49a AA |
1435 | spin_unlock(&mm->page_table_lock); |
1436 | } | |
1437 | out: | |
1438 | return ret; | |
1439 | } | |
1440 | ||
cd7548ab | 1441 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
4b10e7d5 | 1442 | unsigned long addr, pgprot_t newprot, int prot_numa) |
cd7548ab JW |
1443 | { |
1444 | struct mm_struct *mm = vma->vm_mm; | |
1445 | int ret = 0; | |
1446 | ||
025c5b24 NH |
1447 | if (__pmd_trans_huge_lock(pmd, vma) == 1) { |
1448 | pmd_t entry; | |
1449 | entry = pmdp_get_and_clear(mm, addr, pmd); | |
a4f1de17 | 1450 | if (!prot_numa) { |
4b10e7d5 | 1451 | entry = pmd_modify(entry, newprot); |
a4f1de17 HD |
1452 | BUG_ON(pmd_write(entry)); |
1453 | } else { | |
4b10e7d5 MG |
1454 | struct page *page = pmd_page(*pmd); |
1455 | ||
1456 | /* only check non-shared pages */ | |
1457 | if (page_mapcount(page) == 1 && | |
1458 | !pmd_numa(*pmd)) { | |
1459 | entry = pmd_mknuma(entry); | |
1460 | } | |
1461 | } | |
025c5b24 NH |
1462 | set_pmd_at(mm, addr, pmd, entry); |
1463 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1464 | ret = 1; | |
1465 | } | |
1466 | ||
1467 | return ret; | |
1468 | } | |
1469 | ||
1470 | /* | |
1471 | * Returns 1 if a given pmd maps a stable (not under splitting) thp. | |
1472 | * Returns -1 if it maps a thp under splitting. Returns 0 otherwise. | |
1473 | * | |
1474 | * Note that if it returns 1, this routine returns without unlocking page | |
1475 | * table locks. So callers must unlock them. | |
1476 | */ | |
1477 | int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) | |
1478 | { | |
1479 | spin_lock(&vma->vm_mm->page_table_lock); | |
cd7548ab JW |
1480 | if (likely(pmd_trans_huge(*pmd))) { |
1481 | if (unlikely(pmd_trans_splitting(*pmd))) { | |
025c5b24 | 1482 | spin_unlock(&vma->vm_mm->page_table_lock); |
cd7548ab | 1483 | wait_split_huge_page(vma->anon_vma, pmd); |
025c5b24 | 1484 | return -1; |
cd7548ab | 1485 | } else { |
025c5b24 NH |
1486 | /* Thp mapped by 'pmd' is stable, so we can |
1487 | * handle it as it is. */ | |
1488 | return 1; | |
cd7548ab | 1489 | } |
025c5b24 NH |
1490 | } |
1491 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1492 | return 0; | |
cd7548ab JW |
1493 | } |
1494 | ||
71e3aac0 AA |
1495 | pmd_t *page_check_address_pmd(struct page *page, |
1496 | struct mm_struct *mm, | |
1497 | unsigned long address, | |
1498 | enum page_check_address_pmd_flag flag) | |
1499 | { | |
71e3aac0 AA |
1500 | pmd_t *pmd, *ret = NULL; |
1501 | ||
1502 | if (address & ~HPAGE_PMD_MASK) | |
1503 | goto out; | |
1504 | ||
6219049a BL |
1505 | pmd = mm_find_pmd(mm, address); |
1506 | if (!pmd) | |
71e3aac0 | 1507 | goto out; |
71e3aac0 AA |
1508 | if (pmd_none(*pmd)) |
1509 | goto out; | |
1510 | if (pmd_page(*pmd) != page) | |
1511 | goto out; | |
94fcc585 AA |
1512 | /* |
1513 | * split_vma() may create temporary aliased mappings. There is | |
1514 | * no risk as long as all huge pmd are found and have their | |
1515 | * splitting bit set before __split_huge_page_refcount | |
1516 | * runs. Finding the same huge pmd more than once during the | |
1517 | * same rmap walk is not a problem. | |
1518 | */ | |
1519 | if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG && | |
1520 | pmd_trans_splitting(*pmd)) | |
1521 | goto out; | |
71e3aac0 AA |
1522 | if (pmd_trans_huge(*pmd)) { |
1523 | VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG && | |
1524 | !pmd_trans_splitting(*pmd)); | |
1525 | ret = pmd; | |
1526 | } | |
1527 | out: | |
1528 | return ret; | |
1529 | } | |
1530 | ||
1531 | static int __split_huge_page_splitting(struct page *page, | |
1532 | struct vm_area_struct *vma, | |
1533 | unsigned long address) | |
1534 | { | |
1535 | struct mm_struct *mm = vma->vm_mm; | |
1536 | pmd_t *pmd; | |
1537 | int ret = 0; | |
2ec74c3e SG |
1538 | /* For mmu_notifiers */ |
1539 | const unsigned long mmun_start = address; | |
1540 | const unsigned long mmun_end = address + HPAGE_PMD_SIZE; | |
71e3aac0 | 1541 | |
2ec74c3e | 1542 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
71e3aac0 AA |
1543 | spin_lock(&mm->page_table_lock); |
1544 | pmd = page_check_address_pmd(page, mm, address, | |
1545 | PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG); | |
1546 | if (pmd) { | |
1547 | /* | |
1548 | * We can't temporarily set the pmd to null in order | |
1549 | * to split it, the pmd must remain marked huge at all | |
1550 | * times or the VM won't take the pmd_trans_huge paths | |
5a505085 | 1551 | * and it won't wait on the anon_vma->root->rwsem to |
71e3aac0 AA |
1552 | * serialize against split_huge_page*. |
1553 | */ | |
2ec74c3e | 1554 | pmdp_splitting_flush(vma, address, pmd); |
71e3aac0 AA |
1555 | ret = 1; |
1556 | } | |
1557 | spin_unlock(&mm->page_table_lock); | |
2ec74c3e | 1558 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
71e3aac0 AA |
1559 | |
1560 | return ret; | |
1561 | } | |
1562 | ||
1563 | static void __split_huge_page_refcount(struct page *page) | |
1564 | { | |
1565 | int i; | |
71e3aac0 | 1566 | struct zone *zone = page_zone(page); |
fa9add64 | 1567 | struct lruvec *lruvec; |
70b50f94 | 1568 | int tail_count = 0; |
71e3aac0 AA |
1569 | |
1570 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
1571 | spin_lock_irq(&zone->lru_lock); | |
fa9add64 HD |
1572 | lruvec = mem_cgroup_page_lruvec(page, zone); |
1573 | ||
71e3aac0 | 1574 | compound_lock(page); |
e94c8a9c KH |
1575 | /* complete memcg works before add pages to LRU */ |
1576 | mem_cgroup_split_huge_fixup(page); | |
71e3aac0 | 1577 | |
45676885 | 1578 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { |
71e3aac0 AA |
1579 | struct page *page_tail = page + i; |
1580 | ||
70b50f94 AA |
1581 | /* tail_page->_mapcount cannot change */ |
1582 | BUG_ON(page_mapcount(page_tail) < 0); | |
1583 | tail_count += page_mapcount(page_tail); | |
1584 | /* check for overflow */ | |
1585 | BUG_ON(tail_count < 0); | |
1586 | BUG_ON(atomic_read(&page_tail->_count) != 0); | |
1587 | /* | |
1588 | * tail_page->_count is zero and not changing from | |
1589 | * under us. But get_page_unless_zero() may be running | |
1590 | * from under us on the tail_page. If we used | |
1591 | * atomic_set() below instead of atomic_add(), we | |
1592 | * would then run atomic_set() concurrently with | |
1593 | * get_page_unless_zero(), and atomic_set() is | |
1594 | * implemented in C not using locked ops. spin_unlock | |
1595 | * on x86 sometime uses locked ops because of PPro | |
1596 | * errata 66, 92, so unless somebody can guarantee | |
1597 | * atomic_set() here would be safe on all archs (and | |
1598 | * not only on x86), it's safer to use atomic_add(). | |
1599 | */ | |
1600 | atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1, | |
1601 | &page_tail->_count); | |
71e3aac0 AA |
1602 | |
1603 | /* after clearing PageTail the gup refcount can be released */ | |
1604 | smp_mb(); | |
1605 | ||
a6d30ddd JD |
1606 | /* |
1607 | * retain hwpoison flag of the poisoned tail page: | |
1608 | * fix for the unsuitable process killed on Guest Machine(KVM) | |
1609 | * by the memory-failure. | |
1610 | */ | |
1611 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON; | |
71e3aac0 AA |
1612 | page_tail->flags |= (page->flags & |
1613 | ((1L << PG_referenced) | | |
1614 | (1L << PG_swapbacked) | | |
1615 | (1L << PG_mlocked) | | |
1616 | (1L << PG_uptodate))); | |
1617 | page_tail->flags |= (1L << PG_dirty); | |
1618 | ||
70b50f94 | 1619 | /* clear PageTail before overwriting first_page */ |
71e3aac0 AA |
1620 | smp_wmb(); |
1621 | ||
1622 | /* | |
1623 | * __split_huge_page_splitting() already set the | |
1624 | * splitting bit in all pmd that could map this | |
1625 | * hugepage, that will ensure no CPU can alter the | |
1626 | * mapcount on the head page. The mapcount is only | |
1627 | * accounted in the head page and it has to be | |
1628 | * transferred to all tail pages in the below code. So | |
1629 | * for this code to be safe, the split the mapcount | |
1630 | * can't change. But that doesn't mean userland can't | |
1631 | * keep changing and reading the page contents while | |
1632 | * we transfer the mapcount, so the pmd splitting | |
1633 | * status is achieved setting a reserved bit in the | |
1634 | * pmd, not by clearing the present bit. | |
1635 | */ | |
71e3aac0 AA |
1636 | page_tail->_mapcount = page->_mapcount; |
1637 | ||
1638 | BUG_ON(page_tail->mapping); | |
1639 | page_tail->mapping = page->mapping; | |
1640 | ||
45676885 | 1641 | page_tail->index = page->index + i; |
22b751c3 | 1642 | page_nid_xchg_last(page_tail, page_nid_last(page)); |
71e3aac0 AA |
1643 | |
1644 | BUG_ON(!PageAnon(page_tail)); | |
1645 | BUG_ON(!PageUptodate(page_tail)); | |
1646 | BUG_ON(!PageDirty(page_tail)); | |
1647 | BUG_ON(!PageSwapBacked(page_tail)); | |
1648 | ||
fa9add64 | 1649 | lru_add_page_tail(page, page_tail, lruvec); |
71e3aac0 | 1650 | } |
70b50f94 AA |
1651 | atomic_sub(tail_count, &page->_count); |
1652 | BUG_ON(atomic_read(&page->_count) <= 0); | |
71e3aac0 | 1653 | |
fa9add64 | 1654 | __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1); |
79134171 AA |
1655 | __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR); |
1656 | ||
71e3aac0 AA |
1657 | ClearPageCompound(page); |
1658 | compound_unlock(page); | |
1659 | spin_unlock_irq(&zone->lru_lock); | |
1660 | ||
1661 | for (i = 1; i < HPAGE_PMD_NR; i++) { | |
1662 | struct page *page_tail = page + i; | |
1663 | BUG_ON(page_count(page_tail) <= 0); | |
1664 | /* | |
1665 | * Tail pages may be freed if there wasn't any mapping | |
1666 | * like if add_to_swap() is running on a lru page that | |
1667 | * had its mapping zapped. And freeing these pages | |
1668 | * requires taking the lru_lock so we do the put_page | |
1669 | * of the tail pages after the split is complete. | |
1670 | */ | |
1671 | put_page(page_tail); | |
1672 | } | |
1673 | ||
1674 | /* | |
1675 | * Only the head page (now become a regular page) is required | |
1676 | * to be pinned by the caller. | |
1677 | */ | |
1678 | BUG_ON(page_count(page) <= 0); | |
1679 | } | |
1680 | ||
1681 | static int __split_huge_page_map(struct page *page, | |
1682 | struct vm_area_struct *vma, | |
1683 | unsigned long address) | |
1684 | { | |
1685 | struct mm_struct *mm = vma->vm_mm; | |
1686 | pmd_t *pmd, _pmd; | |
1687 | int ret = 0, i; | |
1688 | pgtable_t pgtable; | |
1689 | unsigned long haddr; | |
1690 | ||
1691 | spin_lock(&mm->page_table_lock); | |
1692 | pmd = page_check_address_pmd(page, mm, address, | |
1693 | PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG); | |
1694 | if (pmd) { | |
e3ebcf64 | 1695 | pgtable = pgtable_trans_huge_withdraw(mm); |
71e3aac0 AA |
1696 | pmd_populate(mm, &_pmd, pgtable); |
1697 | ||
e3ebcf64 GS |
1698 | haddr = address; |
1699 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
71e3aac0 AA |
1700 | pte_t *pte, entry; |
1701 | BUG_ON(PageCompound(page+i)); | |
1702 | entry = mk_pte(page + i, vma->vm_page_prot); | |
1703 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
1704 | if (!pmd_write(*pmd)) | |
1705 | entry = pte_wrprotect(entry); | |
1706 | else | |
1707 | BUG_ON(page_mapcount(page) != 1); | |
1708 | if (!pmd_young(*pmd)) | |
1709 | entry = pte_mkold(entry); | |
1ba6e0b5 AA |
1710 | if (pmd_numa(*pmd)) |
1711 | entry = pte_mknuma(entry); | |
71e3aac0 AA |
1712 | pte = pte_offset_map(&_pmd, haddr); |
1713 | BUG_ON(!pte_none(*pte)); | |
1714 | set_pte_at(mm, haddr, pte, entry); | |
1715 | pte_unmap(pte); | |
1716 | } | |
1717 | ||
71e3aac0 AA |
1718 | smp_wmb(); /* make pte visible before pmd */ |
1719 | /* | |
1720 | * Up to this point the pmd is present and huge and | |
1721 | * userland has the whole access to the hugepage | |
1722 | * during the split (which happens in place). If we | |
1723 | * overwrite the pmd with the not-huge version | |
1724 | * pointing to the pte here (which of course we could | |
1725 | * if all CPUs were bug free), userland could trigger | |
1726 | * a small page size TLB miss on the small sized TLB | |
1727 | * while the hugepage TLB entry is still established | |
1728 | * in the huge TLB. Some CPU doesn't like that. See | |
1729 | * http://support.amd.com/us/Processor_TechDocs/41322.pdf, | |
1730 | * Erratum 383 on page 93. Intel should be safe but is | |
1731 | * also warns that it's only safe if the permission | |
1732 | * and cache attributes of the two entries loaded in | |
1733 | * the two TLB is identical (which should be the case | |
1734 | * here). But it is generally safer to never allow | |
1735 | * small and huge TLB entries for the same virtual | |
1736 | * address to be loaded simultaneously. So instead of | |
1737 | * doing "pmd_populate(); flush_tlb_range();" we first | |
1738 | * mark the current pmd notpresent (atomically because | |
1739 | * here the pmd_trans_huge and pmd_trans_splitting | |
1740 | * must remain set at all times on the pmd until the | |
1741 | * split is complete for this pmd), then we flush the | |
1742 | * SMP TLB and finally we write the non-huge version | |
1743 | * of the pmd entry with pmd_populate. | |
1744 | */ | |
46dcde73 | 1745 | pmdp_invalidate(vma, address, pmd); |
71e3aac0 AA |
1746 | pmd_populate(mm, pmd, pgtable); |
1747 | ret = 1; | |
1748 | } | |
1749 | spin_unlock(&mm->page_table_lock); | |
1750 | ||
1751 | return ret; | |
1752 | } | |
1753 | ||
5a505085 | 1754 | /* must be called with anon_vma->root->rwsem held */ |
71e3aac0 AA |
1755 | static void __split_huge_page(struct page *page, |
1756 | struct anon_vma *anon_vma) | |
1757 | { | |
1758 | int mapcount, mapcount2; | |
bf181b9f | 1759 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
71e3aac0 AA |
1760 | struct anon_vma_chain *avc; |
1761 | ||
1762 | BUG_ON(!PageHead(page)); | |
1763 | BUG_ON(PageTail(page)); | |
1764 | ||
1765 | mapcount = 0; | |
bf181b9f | 1766 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { |
71e3aac0 AA |
1767 | struct vm_area_struct *vma = avc->vma; |
1768 | unsigned long addr = vma_address(page, vma); | |
1769 | BUG_ON(is_vma_temporary_stack(vma)); | |
71e3aac0 AA |
1770 | mapcount += __split_huge_page_splitting(page, vma, addr); |
1771 | } | |
05759d38 AA |
1772 | /* |
1773 | * It is critical that new vmas are added to the tail of the | |
1774 | * anon_vma list. This guarantes that if copy_huge_pmd() runs | |
1775 | * and establishes a child pmd before | |
1776 | * __split_huge_page_splitting() freezes the parent pmd (so if | |
1777 | * we fail to prevent copy_huge_pmd() from running until the | |
1778 | * whole __split_huge_page() is complete), we will still see | |
1779 | * the newly established pmd of the child later during the | |
1780 | * walk, to be able to set it as pmd_trans_splitting too. | |
1781 | */ | |
1782 | if (mapcount != page_mapcount(page)) | |
1783 | printk(KERN_ERR "mapcount %d page_mapcount %d\n", | |
1784 | mapcount, page_mapcount(page)); | |
71e3aac0 AA |
1785 | BUG_ON(mapcount != page_mapcount(page)); |
1786 | ||
1787 | __split_huge_page_refcount(page); | |
1788 | ||
1789 | mapcount2 = 0; | |
bf181b9f | 1790 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { |
71e3aac0 AA |
1791 | struct vm_area_struct *vma = avc->vma; |
1792 | unsigned long addr = vma_address(page, vma); | |
1793 | BUG_ON(is_vma_temporary_stack(vma)); | |
71e3aac0 AA |
1794 | mapcount2 += __split_huge_page_map(page, vma, addr); |
1795 | } | |
05759d38 AA |
1796 | if (mapcount != mapcount2) |
1797 | printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n", | |
1798 | mapcount, mapcount2, page_mapcount(page)); | |
71e3aac0 AA |
1799 | BUG_ON(mapcount != mapcount2); |
1800 | } | |
1801 | ||
1802 | int split_huge_page(struct page *page) | |
1803 | { | |
1804 | struct anon_vma *anon_vma; | |
1805 | int ret = 1; | |
1806 | ||
c5a647d0 | 1807 | BUG_ON(is_huge_zero_pfn(page_to_pfn(page))); |
71e3aac0 | 1808 | BUG_ON(!PageAnon(page)); |
062f1af2 MG |
1809 | |
1810 | /* | |
1811 | * The caller does not necessarily hold an mmap_sem that would prevent | |
1812 | * the anon_vma disappearing so we first we take a reference to it | |
1813 | * and then lock the anon_vma for write. This is similar to | |
1814 | * page_lock_anon_vma_read except the write lock is taken to serialise | |
1815 | * against parallel split or collapse operations. | |
1816 | */ | |
1817 | anon_vma = page_get_anon_vma(page); | |
71e3aac0 AA |
1818 | if (!anon_vma) |
1819 | goto out; | |
062f1af2 MG |
1820 | anon_vma_lock_write(anon_vma); |
1821 | ||
71e3aac0 AA |
1822 | ret = 0; |
1823 | if (!PageCompound(page)) | |
1824 | goto out_unlock; | |
1825 | ||
1826 | BUG_ON(!PageSwapBacked(page)); | |
1827 | __split_huge_page(page, anon_vma); | |
81ab4201 | 1828 | count_vm_event(THP_SPLIT); |
71e3aac0 AA |
1829 | |
1830 | BUG_ON(PageCompound(page)); | |
1831 | out_unlock: | |
08b52706 | 1832 | anon_vma_unlock_write(anon_vma); |
062f1af2 | 1833 | put_anon_vma(anon_vma); |
71e3aac0 AA |
1834 | out: |
1835 | return ret; | |
1836 | } | |
1837 | ||
4b6e1e37 | 1838 | #define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE) |
78f11a25 | 1839 | |
60ab3244 AA |
1840 | int hugepage_madvise(struct vm_area_struct *vma, |
1841 | unsigned long *vm_flags, int advice) | |
0af4e98b | 1842 | { |
8e72033f GS |
1843 | struct mm_struct *mm = vma->vm_mm; |
1844 | ||
a664b2d8 AA |
1845 | switch (advice) { |
1846 | case MADV_HUGEPAGE: | |
1847 | /* | |
1848 | * Be somewhat over-protective like KSM for now! | |
1849 | */ | |
78f11a25 | 1850 | if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP)) |
a664b2d8 | 1851 | return -EINVAL; |
8e72033f GS |
1852 | if (mm->def_flags & VM_NOHUGEPAGE) |
1853 | return -EINVAL; | |
a664b2d8 AA |
1854 | *vm_flags &= ~VM_NOHUGEPAGE; |
1855 | *vm_flags |= VM_HUGEPAGE; | |
60ab3244 AA |
1856 | /* |
1857 | * If the vma become good for khugepaged to scan, | |
1858 | * register it here without waiting a page fault that | |
1859 | * may not happen any time soon. | |
1860 | */ | |
1861 | if (unlikely(khugepaged_enter_vma_merge(vma))) | |
1862 | return -ENOMEM; | |
a664b2d8 AA |
1863 | break; |
1864 | case MADV_NOHUGEPAGE: | |
1865 | /* | |
1866 | * Be somewhat over-protective like KSM for now! | |
1867 | */ | |
78f11a25 | 1868 | if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP)) |
a664b2d8 AA |
1869 | return -EINVAL; |
1870 | *vm_flags &= ~VM_HUGEPAGE; | |
1871 | *vm_flags |= VM_NOHUGEPAGE; | |
60ab3244 AA |
1872 | /* |
1873 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
1874 | * this vma even if we leave the mm registered in khugepaged if | |
1875 | * it got registered before VM_NOHUGEPAGE was set. | |
1876 | */ | |
a664b2d8 AA |
1877 | break; |
1878 | } | |
0af4e98b AA |
1879 | |
1880 | return 0; | |
1881 | } | |
1882 | ||
ba76149f AA |
1883 | static int __init khugepaged_slab_init(void) |
1884 | { | |
1885 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
1886 | sizeof(struct mm_slot), | |
1887 | __alignof__(struct mm_slot), 0, NULL); | |
1888 | if (!mm_slot_cache) | |
1889 | return -ENOMEM; | |
1890 | ||
1891 | return 0; | |
1892 | } | |
1893 | ||
ba76149f AA |
1894 | static inline struct mm_slot *alloc_mm_slot(void) |
1895 | { | |
1896 | if (!mm_slot_cache) /* initialization failed */ | |
1897 | return NULL; | |
1898 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
1899 | } | |
1900 | ||
1901 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
1902 | { | |
1903 | kmem_cache_free(mm_slot_cache, mm_slot); | |
1904 | } | |
1905 | ||
ba76149f AA |
1906 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) |
1907 | { | |
1908 | struct mm_slot *mm_slot; | |
ba76149f | 1909 | |
b67bfe0d | 1910 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) |
ba76149f AA |
1911 | if (mm == mm_slot->mm) |
1912 | return mm_slot; | |
43b5fbbd | 1913 | |
ba76149f AA |
1914 | return NULL; |
1915 | } | |
1916 | ||
1917 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
1918 | struct mm_slot *mm_slot) | |
1919 | { | |
ba76149f | 1920 | mm_slot->mm = mm; |
43b5fbbd | 1921 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); |
ba76149f AA |
1922 | } |
1923 | ||
1924 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
1925 | { | |
1926 | return atomic_read(&mm->mm_users) == 0; | |
1927 | } | |
1928 | ||
1929 | int __khugepaged_enter(struct mm_struct *mm) | |
1930 | { | |
1931 | struct mm_slot *mm_slot; | |
1932 | int wakeup; | |
1933 | ||
1934 | mm_slot = alloc_mm_slot(); | |
1935 | if (!mm_slot) | |
1936 | return -ENOMEM; | |
1937 | ||
1938 | /* __khugepaged_exit() must not run from under us */ | |
1939 | VM_BUG_ON(khugepaged_test_exit(mm)); | |
1940 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { | |
1941 | free_mm_slot(mm_slot); | |
1942 | return 0; | |
1943 | } | |
1944 | ||
1945 | spin_lock(&khugepaged_mm_lock); | |
1946 | insert_to_mm_slots_hash(mm, mm_slot); | |
1947 | /* | |
1948 | * Insert just behind the scanning cursor, to let the area settle | |
1949 | * down a little. | |
1950 | */ | |
1951 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
1952 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
1953 | spin_unlock(&khugepaged_mm_lock); | |
1954 | ||
1955 | atomic_inc(&mm->mm_count); | |
1956 | if (wakeup) | |
1957 | wake_up_interruptible(&khugepaged_wait); | |
1958 | ||
1959 | return 0; | |
1960 | } | |
1961 | ||
1962 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma) | |
1963 | { | |
1964 | unsigned long hstart, hend; | |
1965 | if (!vma->anon_vma) | |
1966 | /* | |
1967 | * Not yet faulted in so we will register later in the | |
1968 | * page fault if needed. | |
1969 | */ | |
1970 | return 0; | |
78f11a25 | 1971 | if (vma->vm_ops) |
ba76149f AA |
1972 | /* khugepaged not yet working on file or special mappings */ |
1973 | return 0; | |
b3b9c293 | 1974 | VM_BUG_ON(vma->vm_flags & VM_NO_THP); |
ba76149f AA |
1975 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
1976 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1977 | if (hstart < hend) | |
1978 | return khugepaged_enter(vma); | |
1979 | return 0; | |
1980 | } | |
1981 | ||
1982 | void __khugepaged_exit(struct mm_struct *mm) | |
1983 | { | |
1984 | struct mm_slot *mm_slot; | |
1985 | int free = 0; | |
1986 | ||
1987 | spin_lock(&khugepaged_mm_lock); | |
1988 | mm_slot = get_mm_slot(mm); | |
1989 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
43b5fbbd | 1990 | hash_del(&mm_slot->hash); |
ba76149f AA |
1991 | list_del(&mm_slot->mm_node); |
1992 | free = 1; | |
1993 | } | |
d788e80a | 1994 | spin_unlock(&khugepaged_mm_lock); |
ba76149f AA |
1995 | |
1996 | if (free) { | |
ba76149f AA |
1997 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); |
1998 | free_mm_slot(mm_slot); | |
1999 | mmdrop(mm); | |
2000 | } else if (mm_slot) { | |
ba76149f AA |
2001 | /* |
2002 | * This is required to serialize against | |
2003 | * khugepaged_test_exit() (which is guaranteed to run | |
2004 | * under mmap sem read mode). Stop here (after we | |
2005 | * return all pagetables will be destroyed) until | |
2006 | * khugepaged has finished working on the pagetables | |
2007 | * under the mmap_sem. | |
2008 | */ | |
2009 | down_write(&mm->mmap_sem); | |
2010 | up_write(&mm->mmap_sem); | |
d788e80a | 2011 | } |
ba76149f AA |
2012 | } |
2013 | ||
2014 | static void release_pte_page(struct page *page) | |
2015 | { | |
2016 | /* 0 stands for page_is_file_cache(page) == false */ | |
2017 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
2018 | unlock_page(page); | |
2019 | putback_lru_page(page); | |
2020 | } | |
2021 | ||
2022 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
2023 | { | |
2024 | while (--_pte >= pte) { | |
2025 | pte_t pteval = *_pte; | |
2026 | if (!pte_none(pteval)) | |
2027 | release_pte_page(pte_page(pteval)); | |
2028 | } | |
2029 | } | |
2030 | ||
ba76149f AA |
2031 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, |
2032 | unsigned long address, | |
2033 | pte_t *pte) | |
2034 | { | |
2035 | struct page *page; | |
2036 | pte_t *_pte; | |
344aa35c | 2037 | int referenced = 0, none = 0; |
ba76149f AA |
2038 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; |
2039 | _pte++, address += PAGE_SIZE) { | |
2040 | pte_t pteval = *_pte; | |
2041 | if (pte_none(pteval)) { | |
2042 | if (++none <= khugepaged_max_ptes_none) | |
2043 | continue; | |
344aa35c | 2044 | else |
ba76149f | 2045 | goto out; |
ba76149f | 2046 | } |
344aa35c | 2047 | if (!pte_present(pteval) || !pte_write(pteval)) |
ba76149f | 2048 | goto out; |
ba76149f | 2049 | page = vm_normal_page(vma, address, pteval); |
344aa35c | 2050 | if (unlikely(!page)) |
ba76149f | 2051 | goto out; |
344aa35c | 2052 | |
ba76149f AA |
2053 | VM_BUG_ON(PageCompound(page)); |
2054 | BUG_ON(!PageAnon(page)); | |
2055 | VM_BUG_ON(!PageSwapBacked(page)); | |
2056 | ||
2057 | /* cannot use mapcount: can't collapse if there's a gup pin */ | |
344aa35c | 2058 | if (page_count(page) != 1) |
ba76149f | 2059 | goto out; |
ba76149f AA |
2060 | /* |
2061 | * We can do it before isolate_lru_page because the | |
2062 | * page can't be freed from under us. NOTE: PG_lock | |
2063 | * is needed to serialize against split_huge_page | |
2064 | * when invoked from the VM. | |
2065 | */ | |
344aa35c | 2066 | if (!trylock_page(page)) |
ba76149f | 2067 | goto out; |
ba76149f AA |
2068 | /* |
2069 | * Isolate the page to avoid collapsing an hugepage | |
2070 | * currently in use by the VM. | |
2071 | */ | |
2072 | if (isolate_lru_page(page)) { | |
2073 | unlock_page(page); | |
ba76149f AA |
2074 | goto out; |
2075 | } | |
2076 | /* 0 stands for page_is_file_cache(page) == false */ | |
2077 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
2078 | VM_BUG_ON(!PageLocked(page)); | |
2079 | VM_BUG_ON(PageLRU(page)); | |
2080 | ||
2081 | /* If there is no mapped pte young don't collapse the page */ | |
8ee53820 AA |
2082 | if (pte_young(pteval) || PageReferenced(page) || |
2083 | mmu_notifier_test_young(vma->vm_mm, address)) | |
ba76149f AA |
2084 | referenced = 1; |
2085 | } | |
344aa35c BL |
2086 | if (likely(referenced)) |
2087 | return 1; | |
ba76149f | 2088 | out: |
344aa35c BL |
2089 | release_pte_pages(pte, _pte); |
2090 | return 0; | |
ba76149f AA |
2091 | } |
2092 | ||
2093 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
2094 | struct vm_area_struct *vma, | |
2095 | unsigned long address, | |
2096 | spinlock_t *ptl) | |
2097 | { | |
2098 | pte_t *_pte; | |
2099 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { | |
2100 | pte_t pteval = *_pte; | |
2101 | struct page *src_page; | |
2102 | ||
2103 | if (pte_none(pteval)) { | |
2104 | clear_user_highpage(page, address); | |
2105 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
2106 | } else { | |
2107 | src_page = pte_page(pteval); | |
2108 | copy_user_highpage(page, src_page, address, vma); | |
2109 | VM_BUG_ON(page_mapcount(src_page) != 1); | |
ba76149f AA |
2110 | release_pte_page(src_page); |
2111 | /* | |
2112 | * ptl mostly unnecessary, but preempt has to | |
2113 | * be disabled to update the per-cpu stats | |
2114 | * inside page_remove_rmap(). | |
2115 | */ | |
2116 | spin_lock(ptl); | |
2117 | /* | |
2118 | * paravirt calls inside pte_clear here are | |
2119 | * superfluous. | |
2120 | */ | |
2121 | pte_clear(vma->vm_mm, address, _pte); | |
2122 | page_remove_rmap(src_page); | |
2123 | spin_unlock(ptl); | |
2124 | free_page_and_swap_cache(src_page); | |
2125 | } | |
2126 | ||
2127 | address += PAGE_SIZE; | |
2128 | page++; | |
2129 | } | |
2130 | } | |
2131 | ||
26234f36 | 2132 | static void khugepaged_alloc_sleep(void) |
ba76149f | 2133 | { |
26234f36 XG |
2134 | wait_event_freezable_timeout(khugepaged_wait, false, |
2135 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
2136 | } | |
ba76149f | 2137 | |
26234f36 XG |
2138 | #ifdef CONFIG_NUMA |
2139 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
2140 | { | |
2141 | if (IS_ERR(*hpage)) { | |
2142 | if (!*wait) | |
2143 | return false; | |
2144 | ||
2145 | *wait = false; | |
e3b4126c | 2146 | *hpage = NULL; |
26234f36 XG |
2147 | khugepaged_alloc_sleep(); |
2148 | } else if (*hpage) { | |
2149 | put_page(*hpage); | |
2150 | *hpage = NULL; | |
2151 | } | |
2152 | ||
2153 | return true; | |
2154 | } | |
2155 | ||
2156 | static struct page | |
2157 | *khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm, | |
2158 | struct vm_area_struct *vma, unsigned long address, | |
2159 | int node) | |
2160 | { | |
0bbbc0b3 | 2161 | VM_BUG_ON(*hpage); |
ce83d217 AA |
2162 | /* |
2163 | * Allocate the page while the vma is still valid and under | |
2164 | * the mmap_sem read mode so there is no memory allocation | |
2165 | * later when we take the mmap_sem in write mode. This is more | |
2166 | * friendly behavior (OTOH it may actually hide bugs) to | |
2167 | * filesystems in userland with daemons allocating memory in | |
2168 | * the userland I/O paths. Allocating memory with the | |
2169 | * mmap_sem in read mode is good idea also to allow greater | |
2170 | * scalability. | |
2171 | */ | |
26234f36 | 2172 | *hpage = alloc_hugepage_vma(khugepaged_defrag(), vma, address, |
cc5d462f | 2173 | node, __GFP_OTHER_NODE); |
692e0b35 AA |
2174 | |
2175 | /* | |
2176 | * After allocating the hugepage, release the mmap_sem read lock in | |
2177 | * preparation for taking it in write mode. | |
2178 | */ | |
2179 | up_read(&mm->mmap_sem); | |
26234f36 | 2180 | if (unlikely(!*hpage)) { |
81ab4201 | 2181 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); |
ce83d217 | 2182 | *hpage = ERR_PTR(-ENOMEM); |
26234f36 | 2183 | return NULL; |
ce83d217 | 2184 | } |
26234f36 | 2185 | |
65b3c07b | 2186 | count_vm_event(THP_COLLAPSE_ALLOC); |
26234f36 XG |
2187 | return *hpage; |
2188 | } | |
2189 | #else | |
2190 | static struct page *khugepaged_alloc_hugepage(bool *wait) | |
2191 | { | |
2192 | struct page *hpage; | |
2193 | ||
2194 | do { | |
2195 | hpage = alloc_hugepage(khugepaged_defrag()); | |
2196 | if (!hpage) { | |
2197 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
2198 | if (!*wait) | |
2199 | return NULL; | |
2200 | ||
2201 | *wait = false; | |
2202 | khugepaged_alloc_sleep(); | |
2203 | } else | |
2204 | count_vm_event(THP_COLLAPSE_ALLOC); | |
2205 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
2206 | ||
2207 | return hpage; | |
2208 | } | |
2209 | ||
2210 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
2211 | { | |
2212 | if (!*hpage) | |
2213 | *hpage = khugepaged_alloc_hugepage(wait); | |
2214 | ||
2215 | if (unlikely(!*hpage)) | |
2216 | return false; | |
2217 | ||
2218 | return true; | |
2219 | } | |
2220 | ||
2221 | static struct page | |
2222 | *khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm, | |
2223 | struct vm_area_struct *vma, unsigned long address, | |
2224 | int node) | |
2225 | { | |
2226 | up_read(&mm->mmap_sem); | |
2227 | VM_BUG_ON(!*hpage); | |
2228 | return *hpage; | |
2229 | } | |
692e0b35 AA |
2230 | #endif |
2231 | ||
fa475e51 BL |
2232 | static bool hugepage_vma_check(struct vm_area_struct *vma) |
2233 | { | |
2234 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || | |
2235 | (vma->vm_flags & VM_NOHUGEPAGE)) | |
2236 | return false; | |
2237 | ||
2238 | if (!vma->anon_vma || vma->vm_ops) | |
2239 | return false; | |
2240 | if (is_vma_temporary_stack(vma)) | |
2241 | return false; | |
2242 | VM_BUG_ON(vma->vm_flags & VM_NO_THP); | |
2243 | return true; | |
2244 | } | |
2245 | ||
26234f36 XG |
2246 | static void collapse_huge_page(struct mm_struct *mm, |
2247 | unsigned long address, | |
2248 | struct page **hpage, | |
2249 | struct vm_area_struct *vma, | |
2250 | int node) | |
2251 | { | |
26234f36 XG |
2252 | pmd_t *pmd, _pmd; |
2253 | pte_t *pte; | |
2254 | pgtable_t pgtable; | |
2255 | struct page *new_page; | |
2256 | spinlock_t *ptl; | |
2257 | int isolated; | |
2258 | unsigned long hstart, hend; | |
2ec74c3e SG |
2259 | unsigned long mmun_start; /* For mmu_notifiers */ |
2260 | unsigned long mmun_end; /* For mmu_notifiers */ | |
26234f36 XG |
2261 | |
2262 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2263 | ||
2264 | /* release the mmap_sem read lock. */ | |
2265 | new_page = khugepaged_alloc_page(hpage, mm, vma, address, node); | |
2266 | if (!new_page) | |
2267 | return; | |
2268 | ||
420256ef | 2269 | if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) |
ce83d217 | 2270 | return; |
ba76149f AA |
2271 | |
2272 | /* | |
2273 | * Prevent all access to pagetables with the exception of | |
2274 | * gup_fast later hanlded by the ptep_clear_flush and the VM | |
2275 | * handled by the anon_vma lock + PG_lock. | |
2276 | */ | |
2277 | down_write(&mm->mmap_sem); | |
2278 | if (unlikely(khugepaged_test_exit(mm))) | |
2279 | goto out; | |
2280 | ||
2281 | vma = find_vma(mm, address); | |
2282 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2283 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2284 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
2285 | goto out; | |
fa475e51 | 2286 | if (!hugepage_vma_check(vma)) |
a7d6e4ec | 2287 | goto out; |
6219049a BL |
2288 | pmd = mm_find_pmd(mm, address); |
2289 | if (!pmd) | |
ba76149f | 2290 | goto out; |
6219049a | 2291 | if (pmd_trans_huge(*pmd)) |
ba76149f AA |
2292 | goto out; |
2293 | ||
4fc3f1d6 | 2294 | anon_vma_lock_write(vma->anon_vma); |
ba76149f AA |
2295 | |
2296 | pte = pte_offset_map(pmd, address); | |
2297 | ptl = pte_lockptr(mm, pmd); | |
2298 | ||
2ec74c3e SG |
2299 | mmun_start = address; |
2300 | mmun_end = address + HPAGE_PMD_SIZE; | |
2301 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
ba76149f AA |
2302 | spin_lock(&mm->page_table_lock); /* probably unnecessary */ |
2303 | /* | |
2304 | * After this gup_fast can't run anymore. This also removes | |
2305 | * any huge TLB entry from the CPU so we won't allow | |
2306 | * huge and small TLB entries for the same virtual address | |
2307 | * to avoid the risk of CPU bugs in that area. | |
2308 | */ | |
2ec74c3e | 2309 | _pmd = pmdp_clear_flush(vma, address, pmd); |
ba76149f | 2310 | spin_unlock(&mm->page_table_lock); |
2ec74c3e | 2311 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
ba76149f AA |
2312 | |
2313 | spin_lock(ptl); | |
2314 | isolated = __collapse_huge_page_isolate(vma, address, pte); | |
2315 | spin_unlock(ptl); | |
ba76149f AA |
2316 | |
2317 | if (unlikely(!isolated)) { | |
453c7192 | 2318 | pte_unmap(pte); |
ba76149f AA |
2319 | spin_lock(&mm->page_table_lock); |
2320 | BUG_ON(!pmd_none(*pmd)); | |
2321 | set_pmd_at(mm, address, pmd, _pmd); | |
2322 | spin_unlock(&mm->page_table_lock); | |
08b52706 | 2323 | anon_vma_unlock_write(vma->anon_vma); |
ce83d217 | 2324 | goto out; |
ba76149f AA |
2325 | } |
2326 | ||
2327 | /* | |
2328 | * All pages are isolated and locked so anon_vma rmap | |
2329 | * can't run anymore. | |
2330 | */ | |
08b52706 | 2331 | anon_vma_unlock_write(vma->anon_vma); |
ba76149f AA |
2332 | |
2333 | __collapse_huge_page_copy(pte, new_page, vma, address, ptl); | |
453c7192 | 2334 | pte_unmap(pte); |
ba76149f AA |
2335 | __SetPageUptodate(new_page); |
2336 | pgtable = pmd_pgtable(_pmd); | |
ba76149f | 2337 | |
b3092b3b | 2338 | _pmd = mk_huge_pmd(new_page, vma); |
ba76149f AA |
2339 | |
2340 | /* | |
2341 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
2342 | * this is needed to avoid the copy_huge_page writes to become | |
2343 | * visible after the set_pmd_at() write. | |
2344 | */ | |
2345 | smp_wmb(); | |
2346 | ||
2347 | spin_lock(&mm->page_table_lock); | |
2348 | BUG_ON(!pmd_none(*pmd)); | |
2349 | page_add_new_anon_rmap(new_page, vma, address); | |
2350 | set_pmd_at(mm, address, pmd, _pmd); | |
b113da65 | 2351 | update_mmu_cache_pmd(vma, address, pmd); |
e3ebcf64 | 2352 | pgtable_trans_huge_deposit(mm, pgtable); |
ba76149f AA |
2353 | spin_unlock(&mm->page_table_lock); |
2354 | ||
2355 | *hpage = NULL; | |
420256ef | 2356 | |
ba76149f | 2357 | khugepaged_pages_collapsed++; |
ce83d217 | 2358 | out_up_write: |
ba76149f | 2359 | up_write(&mm->mmap_sem); |
0bbbc0b3 AA |
2360 | return; |
2361 | ||
ce83d217 | 2362 | out: |
678ff896 | 2363 | mem_cgroup_uncharge_page(new_page); |
ce83d217 | 2364 | goto out_up_write; |
ba76149f AA |
2365 | } |
2366 | ||
2367 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
2368 | struct vm_area_struct *vma, | |
2369 | unsigned long address, | |
2370 | struct page **hpage) | |
2371 | { | |
ba76149f AA |
2372 | pmd_t *pmd; |
2373 | pte_t *pte, *_pte; | |
2374 | int ret = 0, referenced = 0, none = 0; | |
2375 | struct page *page; | |
2376 | unsigned long _address; | |
2377 | spinlock_t *ptl; | |
00ef2d2f | 2378 | int node = NUMA_NO_NODE; |
ba76149f AA |
2379 | |
2380 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2381 | ||
6219049a BL |
2382 | pmd = mm_find_pmd(mm, address); |
2383 | if (!pmd) | |
ba76149f | 2384 | goto out; |
6219049a | 2385 | if (pmd_trans_huge(*pmd)) |
ba76149f AA |
2386 | goto out; |
2387 | ||
2388 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
2389 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
2390 | _pte++, _address += PAGE_SIZE) { | |
2391 | pte_t pteval = *_pte; | |
2392 | if (pte_none(pteval)) { | |
2393 | if (++none <= khugepaged_max_ptes_none) | |
2394 | continue; | |
2395 | else | |
2396 | goto out_unmap; | |
2397 | } | |
2398 | if (!pte_present(pteval) || !pte_write(pteval)) | |
2399 | goto out_unmap; | |
2400 | page = vm_normal_page(vma, _address, pteval); | |
2401 | if (unlikely(!page)) | |
2402 | goto out_unmap; | |
5c4b4be3 AK |
2403 | /* |
2404 | * Chose the node of the first page. This could | |
2405 | * be more sophisticated and look at more pages, | |
2406 | * but isn't for now. | |
2407 | */ | |
00ef2d2f | 2408 | if (node == NUMA_NO_NODE) |
5c4b4be3 | 2409 | node = page_to_nid(page); |
ba76149f AA |
2410 | VM_BUG_ON(PageCompound(page)); |
2411 | if (!PageLRU(page) || PageLocked(page) || !PageAnon(page)) | |
2412 | goto out_unmap; | |
2413 | /* cannot use mapcount: can't collapse if there's a gup pin */ | |
2414 | if (page_count(page) != 1) | |
2415 | goto out_unmap; | |
8ee53820 AA |
2416 | if (pte_young(pteval) || PageReferenced(page) || |
2417 | mmu_notifier_test_young(vma->vm_mm, address)) | |
ba76149f AA |
2418 | referenced = 1; |
2419 | } | |
2420 | if (referenced) | |
2421 | ret = 1; | |
2422 | out_unmap: | |
2423 | pte_unmap_unlock(pte, ptl); | |
ce83d217 AA |
2424 | if (ret) |
2425 | /* collapse_huge_page will return with the mmap_sem released */ | |
5c4b4be3 | 2426 | collapse_huge_page(mm, address, hpage, vma, node); |
ba76149f AA |
2427 | out: |
2428 | return ret; | |
2429 | } | |
2430 | ||
2431 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
2432 | { | |
2433 | struct mm_struct *mm = mm_slot->mm; | |
2434 | ||
b9980cdc | 2435 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2436 | |
2437 | if (khugepaged_test_exit(mm)) { | |
2438 | /* free mm_slot */ | |
43b5fbbd | 2439 | hash_del(&mm_slot->hash); |
ba76149f AA |
2440 | list_del(&mm_slot->mm_node); |
2441 | ||
2442 | /* | |
2443 | * Not strictly needed because the mm exited already. | |
2444 | * | |
2445 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
2446 | */ | |
2447 | ||
2448 | /* khugepaged_mm_lock actually not necessary for the below */ | |
2449 | free_mm_slot(mm_slot); | |
2450 | mmdrop(mm); | |
2451 | } | |
2452 | } | |
2453 | ||
2454 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
2455 | struct page **hpage) | |
2f1da642 HS |
2456 | __releases(&khugepaged_mm_lock) |
2457 | __acquires(&khugepaged_mm_lock) | |
ba76149f AA |
2458 | { |
2459 | struct mm_slot *mm_slot; | |
2460 | struct mm_struct *mm; | |
2461 | struct vm_area_struct *vma; | |
2462 | int progress = 0; | |
2463 | ||
2464 | VM_BUG_ON(!pages); | |
b9980cdc | 2465 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2466 | |
2467 | if (khugepaged_scan.mm_slot) | |
2468 | mm_slot = khugepaged_scan.mm_slot; | |
2469 | else { | |
2470 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2471 | struct mm_slot, mm_node); | |
2472 | khugepaged_scan.address = 0; | |
2473 | khugepaged_scan.mm_slot = mm_slot; | |
2474 | } | |
2475 | spin_unlock(&khugepaged_mm_lock); | |
2476 | ||
2477 | mm = mm_slot->mm; | |
2478 | down_read(&mm->mmap_sem); | |
2479 | if (unlikely(khugepaged_test_exit(mm))) | |
2480 | vma = NULL; | |
2481 | else | |
2482 | vma = find_vma(mm, khugepaged_scan.address); | |
2483 | ||
2484 | progress++; | |
2485 | for (; vma; vma = vma->vm_next) { | |
2486 | unsigned long hstart, hend; | |
2487 | ||
2488 | cond_resched(); | |
2489 | if (unlikely(khugepaged_test_exit(mm))) { | |
2490 | progress++; | |
2491 | break; | |
2492 | } | |
fa475e51 BL |
2493 | if (!hugepage_vma_check(vma)) { |
2494 | skip: | |
ba76149f AA |
2495 | progress++; |
2496 | continue; | |
2497 | } | |
ba76149f AA |
2498 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2499 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
a7d6e4ec AA |
2500 | if (hstart >= hend) |
2501 | goto skip; | |
2502 | if (khugepaged_scan.address > hend) | |
2503 | goto skip; | |
ba76149f AA |
2504 | if (khugepaged_scan.address < hstart) |
2505 | khugepaged_scan.address = hstart; | |
a7d6e4ec | 2506 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); |
ba76149f AA |
2507 | |
2508 | while (khugepaged_scan.address < hend) { | |
2509 | int ret; | |
2510 | cond_resched(); | |
2511 | if (unlikely(khugepaged_test_exit(mm))) | |
2512 | goto breakouterloop; | |
2513 | ||
2514 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2515 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2516 | hend); | |
2517 | ret = khugepaged_scan_pmd(mm, vma, | |
2518 | khugepaged_scan.address, | |
2519 | hpage); | |
2520 | /* move to next address */ | |
2521 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2522 | progress += HPAGE_PMD_NR; | |
2523 | if (ret) | |
2524 | /* we released mmap_sem so break loop */ | |
2525 | goto breakouterloop_mmap_sem; | |
2526 | if (progress >= pages) | |
2527 | goto breakouterloop; | |
2528 | } | |
2529 | } | |
2530 | breakouterloop: | |
2531 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2532 | breakouterloop_mmap_sem: | |
2533 | ||
2534 | spin_lock(&khugepaged_mm_lock); | |
a7d6e4ec | 2535 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); |
ba76149f AA |
2536 | /* |
2537 | * Release the current mm_slot if this mm is about to die, or | |
2538 | * if we scanned all vmas of this mm. | |
2539 | */ | |
2540 | if (khugepaged_test_exit(mm) || !vma) { | |
2541 | /* | |
2542 | * Make sure that if mm_users is reaching zero while | |
2543 | * khugepaged runs here, khugepaged_exit will find | |
2544 | * mm_slot not pointing to the exiting mm. | |
2545 | */ | |
2546 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2547 | khugepaged_scan.mm_slot = list_entry( | |
2548 | mm_slot->mm_node.next, | |
2549 | struct mm_slot, mm_node); | |
2550 | khugepaged_scan.address = 0; | |
2551 | } else { | |
2552 | khugepaged_scan.mm_slot = NULL; | |
2553 | khugepaged_full_scans++; | |
2554 | } | |
2555 | ||
2556 | collect_mm_slot(mm_slot); | |
2557 | } | |
2558 | ||
2559 | return progress; | |
2560 | } | |
2561 | ||
2562 | static int khugepaged_has_work(void) | |
2563 | { | |
2564 | return !list_empty(&khugepaged_scan.mm_head) && | |
2565 | khugepaged_enabled(); | |
2566 | } | |
2567 | ||
2568 | static int khugepaged_wait_event(void) | |
2569 | { | |
2570 | return !list_empty(&khugepaged_scan.mm_head) || | |
2017c0bf | 2571 | kthread_should_stop(); |
ba76149f AA |
2572 | } |
2573 | ||
d516904b | 2574 | static void khugepaged_do_scan(void) |
ba76149f | 2575 | { |
d516904b | 2576 | struct page *hpage = NULL; |
ba76149f AA |
2577 | unsigned int progress = 0, pass_through_head = 0; |
2578 | unsigned int pages = khugepaged_pages_to_scan; | |
d516904b | 2579 | bool wait = true; |
ba76149f AA |
2580 | |
2581 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2582 | ||
2583 | while (progress < pages) { | |
26234f36 | 2584 | if (!khugepaged_prealloc_page(&hpage, &wait)) |
d516904b | 2585 | break; |
26234f36 | 2586 | |
420256ef | 2587 | cond_resched(); |
ba76149f | 2588 | |
878aee7d AA |
2589 | if (unlikely(kthread_should_stop() || freezing(current))) |
2590 | break; | |
2591 | ||
ba76149f AA |
2592 | spin_lock(&khugepaged_mm_lock); |
2593 | if (!khugepaged_scan.mm_slot) | |
2594 | pass_through_head++; | |
2595 | if (khugepaged_has_work() && | |
2596 | pass_through_head < 2) | |
2597 | progress += khugepaged_scan_mm_slot(pages - progress, | |
d516904b | 2598 | &hpage); |
ba76149f AA |
2599 | else |
2600 | progress = pages; | |
2601 | spin_unlock(&khugepaged_mm_lock); | |
2602 | } | |
ba76149f | 2603 | |
d516904b XG |
2604 | if (!IS_ERR_OR_NULL(hpage)) |
2605 | put_page(hpage); | |
0bbbc0b3 AA |
2606 | } |
2607 | ||
2017c0bf XG |
2608 | static void khugepaged_wait_work(void) |
2609 | { | |
2610 | try_to_freeze(); | |
2611 | ||
2612 | if (khugepaged_has_work()) { | |
2613 | if (!khugepaged_scan_sleep_millisecs) | |
2614 | return; | |
2615 | ||
2616 | wait_event_freezable_timeout(khugepaged_wait, | |
2617 | kthread_should_stop(), | |
2618 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs)); | |
2619 | return; | |
2620 | } | |
2621 | ||
2622 | if (khugepaged_enabled()) | |
2623 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2624 | } | |
2625 | ||
ba76149f AA |
2626 | static int khugepaged(void *none) |
2627 | { | |
2628 | struct mm_slot *mm_slot; | |
2629 | ||
878aee7d | 2630 | set_freezable(); |
ba76149f AA |
2631 | set_user_nice(current, 19); |
2632 | ||
b7231789 XG |
2633 | while (!kthread_should_stop()) { |
2634 | khugepaged_do_scan(); | |
2635 | khugepaged_wait_work(); | |
2636 | } | |
ba76149f AA |
2637 | |
2638 | spin_lock(&khugepaged_mm_lock); | |
2639 | mm_slot = khugepaged_scan.mm_slot; | |
2640 | khugepaged_scan.mm_slot = NULL; | |
2641 | if (mm_slot) | |
2642 | collect_mm_slot(mm_slot); | |
2643 | spin_unlock(&khugepaged_mm_lock); | |
ba76149f AA |
2644 | return 0; |
2645 | } | |
2646 | ||
c5a647d0 KS |
2647 | static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, |
2648 | unsigned long haddr, pmd_t *pmd) | |
2649 | { | |
2650 | struct mm_struct *mm = vma->vm_mm; | |
2651 | pgtable_t pgtable; | |
2652 | pmd_t _pmd; | |
2653 | int i; | |
2654 | ||
2655 | pmdp_clear_flush(vma, haddr, pmd); | |
2656 | /* leave pmd empty until pte is filled */ | |
2657 | ||
2658 | pgtable = pgtable_trans_huge_withdraw(mm); | |
2659 | pmd_populate(mm, &_pmd, pgtable); | |
2660 | ||
2661 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
2662 | pte_t *pte, entry; | |
2663 | entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); | |
2664 | entry = pte_mkspecial(entry); | |
2665 | pte = pte_offset_map(&_pmd, haddr); | |
2666 | VM_BUG_ON(!pte_none(*pte)); | |
2667 | set_pte_at(mm, haddr, pte, entry); | |
2668 | pte_unmap(pte); | |
2669 | } | |
2670 | smp_wmb(); /* make pte visible before pmd */ | |
2671 | pmd_populate(mm, pmd, pgtable); | |
97ae1749 | 2672 | put_huge_zero_page(); |
c5a647d0 KS |
2673 | } |
2674 | ||
e180377f KS |
2675 | void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address, |
2676 | pmd_t *pmd) | |
71e3aac0 AA |
2677 | { |
2678 | struct page *page; | |
e180377f | 2679 | struct mm_struct *mm = vma->vm_mm; |
c5a647d0 KS |
2680 | unsigned long haddr = address & HPAGE_PMD_MASK; |
2681 | unsigned long mmun_start; /* For mmu_notifiers */ | |
2682 | unsigned long mmun_end; /* For mmu_notifiers */ | |
e180377f KS |
2683 | |
2684 | BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE); | |
71e3aac0 | 2685 | |
c5a647d0 KS |
2686 | mmun_start = haddr; |
2687 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
2688 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
71e3aac0 AA |
2689 | spin_lock(&mm->page_table_lock); |
2690 | if (unlikely(!pmd_trans_huge(*pmd))) { | |
2691 | spin_unlock(&mm->page_table_lock); | |
c5a647d0 KS |
2692 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
2693 | return; | |
2694 | } | |
2695 | if (is_huge_zero_pmd(*pmd)) { | |
2696 | __split_huge_zero_page_pmd(vma, haddr, pmd); | |
2697 | spin_unlock(&mm->page_table_lock); | |
2698 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
71e3aac0 AA |
2699 | return; |
2700 | } | |
2701 | page = pmd_page(*pmd); | |
2702 | VM_BUG_ON(!page_count(page)); | |
2703 | get_page(page); | |
2704 | spin_unlock(&mm->page_table_lock); | |
c5a647d0 | 2705 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
71e3aac0 AA |
2706 | |
2707 | split_huge_page(page); | |
2708 | ||
2709 | put_page(page); | |
2710 | BUG_ON(pmd_trans_huge(*pmd)); | |
2711 | } | |
94fcc585 | 2712 | |
e180377f KS |
2713 | void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address, |
2714 | pmd_t *pmd) | |
2715 | { | |
2716 | struct vm_area_struct *vma; | |
2717 | ||
2718 | vma = find_vma(mm, address); | |
2719 | BUG_ON(vma == NULL); | |
2720 | split_huge_page_pmd(vma, address, pmd); | |
2721 | } | |
2722 | ||
94fcc585 AA |
2723 | static void split_huge_page_address(struct mm_struct *mm, |
2724 | unsigned long address) | |
2725 | { | |
94fcc585 AA |
2726 | pmd_t *pmd; |
2727 | ||
2728 | VM_BUG_ON(!(address & ~HPAGE_PMD_MASK)); | |
2729 | ||
6219049a BL |
2730 | pmd = mm_find_pmd(mm, address); |
2731 | if (!pmd) | |
94fcc585 AA |
2732 | return; |
2733 | /* | |
2734 | * Caller holds the mmap_sem write mode, so a huge pmd cannot | |
2735 | * materialize from under us. | |
2736 | */ | |
e180377f | 2737 | split_huge_page_pmd_mm(mm, address, pmd); |
94fcc585 AA |
2738 | } |
2739 | ||
2740 | void __vma_adjust_trans_huge(struct vm_area_struct *vma, | |
2741 | unsigned long start, | |
2742 | unsigned long end, | |
2743 | long adjust_next) | |
2744 | { | |
2745 | /* | |
2746 | * If the new start address isn't hpage aligned and it could | |
2747 | * previously contain an hugepage: check if we need to split | |
2748 | * an huge pmd. | |
2749 | */ | |
2750 | if (start & ~HPAGE_PMD_MASK && | |
2751 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
2752 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2753 | split_huge_page_address(vma->vm_mm, start); | |
2754 | ||
2755 | /* | |
2756 | * If the new end address isn't hpage aligned and it could | |
2757 | * previously contain an hugepage: check if we need to split | |
2758 | * an huge pmd. | |
2759 | */ | |
2760 | if (end & ~HPAGE_PMD_MASK && | |
2761 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
2762 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2763 | split_huge_page_address(vma->vm_mm, end); | |
2764 | ||
2765 | /* | |
2766 | * If we're also updating the vma->vm_next->vm_start, if the new | |
2767 | * vm_next->vm_start isn't page aligned and it could previously | |
2768 | * contain an hugepage: check if we need to split an huge pmd. | |
2769 | */ | |
2770 | if (adjust_next > 0) { | |
2771 | struct vm_area_struct *next = vma->vm_next; | |
2772 | unsigned long nstart = next->vm_start; | |
2773 | nstart += adjust_next << PAGE_SHIFT; | |
2774 | if (nstart & ~HPAGE_PMD_MASK && | |
2775 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
2776 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
2777 | split_huge_page_address(next->vm_mm, nstart); | |
2778 | } | |
2779 | } |