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Commit | Line | Data |
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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 | ||
ae3a8c1c AM |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
9 | ||
71e3aac0 AA |
10 | #include <linux/mm.h> |
11 | #include <linux/sched.h> | |
12 | #include <linux/highmem.h> | |
13 | #include <linux/hugetlb.h> | |
14 | #include <linux/mmu_notifier.h> | |
15 | #include <linux/rmap.h> | |
16 | #include <linux/swap.h> | |
97ae1749 | 17 | #include <linux/shrinker.h> |
ba76149f | 18 | #include <linux/mm_inline.h> |
4897c765 | 19 | #include <linux/dax.h> |
ba76149f AA |
20 | #include <linux/kthread.h> |
21 | #include <linux/khugepaged.h> | |
878aee7d | 22 | #include <linux/freezer.h> |
a664b2d8 | 23 | #include <linux/mman.h> |
325adeb5 | 24 | #include <linux/pagemap.h> |
4daae3b4 | 25 | #include <linux/migrate.h> |
43b5fbbd | 26 | #include <linux/hashtable.h> |
6b251fc9 | 27 | #include <linux/userfaultfd_k.h> |
97ae1749 | 28 | |
71e3aac0 AA |
29 | #include <asm/tlb.h> |
30 | #include <asm/pgalloc.h> | |
31 | #include "internal.h" | |
32 | ||
ba76149f | 33 | /* |
8bfa3f9a JW |
34 | * By default transparent hugepage support is disabled in order that avoid |
35 | * to risk increase the memory footprint of applications without a guaranteed | |
36 | * benefit. When transparent hugepage support is enabled, is for all mappings, | |
37 | * and khugepaged scans all mappings. | |
38 | * Defrag is invoked by khugepaged hugepage allocations and by page faults | |
39 | * for all hugepage allocations. | |
ba76149f | 40 | */ |
71e3aac0 | 41 | unsigned long transparent_hugepage_flags __read_mostly = |
13ece886 | 42 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS |
ba76149f | 43 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| |
13ece886 AA |
44 | #endif |
45 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE | |
46 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| | |
47 | #endif | |
d39d33c3 | 48 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)| |
79da5407 KS |
49 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| |
50 | (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
ba76149f AA |
51 | |
52 | /* default scan 8*512 pte (or vmas) every 30 second */ | |
53 | static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8; | |
54 | static unsigned int khugepaged_pages_collapsed; | |
55 | static unsigned int khugepaged_full_scans; | |
56 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
57 | /* during fragmentation poll the hugepage allocator once every minute */ | |
58 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
59 | static struct task_struct *khugepaged_thread __read_mostly; | |
60 | static DEFINE_MUTEX(khugepaged_mutex); | |
61 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
62 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
63 | /* | |
64 | * default collapse hugepages if there is at least one pte mapped like | |
65 | * it would have happened if the vma was large enough during page | |
66 | * fault. | |
67 | */ | |
68 | static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1; | |
69 | ||
70 | static int khugepaged(void *none); | |
ba76149f | 71 | static int khugepaged_slab_init(void); |
65ebb64f | 72 | static void khugepaged_slab_exit(void); |
ba76149f | 73 | |
43b5fbbd SL |
74 | #define MM_SLOTS_HASH_BITS 10 |
75 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
76 | ||
ba76149f AA |
77 | static struct kmem_cache *mm_slot_cache __read_mostly; |
78 | ||
79 | /** | |
80 | * struct mm_slot - hash lookup from mm to mm_slot | |
81 | * @hash: hash collision list | |
82 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
83 | * @mm: the mm that this information is valid for | |
84 | */ | |
85 | struct mm_slot { | |
86 | struct hlist_node hash; | |
87 | struct list_head mm_node; | |
88 | struct mm_struct *mm; | |
89 | }; | |
90 | ||
91 | /** | |
92 | * struct khugepaged_scan - cursor for scanning | |
93 | * @mm_head: the head of the mm list to scan | |
94 | * @mm_slot: the current mm_slot we are scanning | |
95 | * @address: the next address inside that to be scanned | |
96 | * | |
97 | * There is only the one khugepaged_scan instance of this cursor structure. | |
98 | */ | |
99 | struct khugepaged_scan { | |
100 | struct list_head mm_head; | |
101 | struct mm_slot *mm_slot; | |
102 | unsigned long address; | |
2f1da642 HS |
103 | }; |
104 | static struct khugepaged_scan khugepaged_scan = { | |
ba76149f AA |
105 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), |
106 | }; | |
107 | ||
f000565a | 108 | |
2c0b80d4 | 109 | static void set_recommended_min_free_kbytes(void) |
f000565a AA |
110 | { |
111 | struct zone *zone; | |
112 | int nr_zones = 0; | |
113 | unsigned long recommended_min; | |
f000565a | 114 | |
f000565a AA |
115 | for_each_populated_zone(zone) |
116 | nr_zones++; | |
117 | ||
118 | /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */ | |
119 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
120 | ||
121 | /* | |
122 | * Make sure that on average at least two pageblocks are almost free | |
123 | * of another type, one for a migratetype to fall back to and a | |
124 | * second to avoid subsequent fallbacks of other types There are 3 | |
125 | * MIGRATE_TYPES we care about. | |
126 | */ | |
127 | recommended_min += pageblock_nr_pages * nr_zones * | |
128 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
129 | ||
130 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
131 | recommended_min = min(recommended_min, | |
132 | (unsigned long) nr_free_buffer_pages() / 20); | |
133 | recommended_min <<= (PAGE_SHIFT-10); | |
134 | ||
42aa83cb HP |
135 | if (recommended_min > min_free_kbytes) { |
136 | if (user_min_free_kbytes >= 0) | |
137 | pr_info("raising min_free_kbytes from %d to %lu " | |
138 | "to help transparent hugepage allocations\n", | |
139 | min_free_kbytes, recommended_min); | |
140 | ||
f000565a | 141 | min_free_kbytes = recommended_min; |
42aa83cb | 142 | } |
f000565a | 143 | setup_per_zone_wmarks(); |
f000565a | 144 | } |
f000565a | 145 | |
79553da2 | 146 | static int start_stop_khugepaged(void) |
ba76149f AA |
147 | { |
148 | int err = 0; | |
149 | if (khugepaged_enabled()) { | |
ba76149f AA |
150 | if (!khugepaged_thread) |
151 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
152 | "khugepaged"); | |
153 | if (unlikely(IS_ERR(khugepaged_thread))) { | |
ae3a8c1c | 154 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); |
ba76149f AA |
155 | err = PTR_ERR(khugepaged_thread); |
156 | khugepaged_thread = NULL; | |
79553da2 | 157 | goto fail; |
ba76149f | 158 | } |
911891af XG |
159 | |
160 | if (!list_empty(&khugepaged_scan.mm_head)) | |
ba76149f | 161 | wake_up_interruptible(&khugepaged_wait); |
f000565a AA |
162 | |
163 | set_recommended_min_free_kbytes(); | |
911891af | 164 | } else if (khugepaged_thread) { |
911891af XG |
165 | kthread_stop(khugepaged_thread); |
166 | khugepaged_thread = NULL; | |
167 | } | |
79553da2 | 168 | fail: |
ba76149f AA |
169 | return err; |
170 | } | |
71e3aac0 | 171 | |
97ae1749 | 172 | static atomic_t huge_zero_refcount; |
56873f43 | 173 | struct page *huge_zero_page __read_mostly; |
4a6c1297 | 174 | |
fc437044 | 175 | struct page *get_huge_zero_page(void) |
97ae1749 KS |
176 | { |
177 | struct page *zero_page; | |
178 | retry: | |
179 | if (likely(atomic_inc_not_zero(&huge_zero_refcount))) | |
4db0c3c2 | 180 | return READ_ONCE(huge_zero_page); |
97ae1749 KS |
181 | |
182 | zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, | |
4a6c1297 | 183 | HPAGE_PMD_ORDER); |
d8a8e1f0 KS |
184 | if (!zero_page) { |
185 | count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); | |
5918d10a | 186 | return NULL; |
d8a8e1f0 KS |
187 | } |
188 | count_vm_event(THP_ZERO_PAGE_ALLOC); | |
97ae1749 | 189 | preempt_disable(); |
5918d10a | 190 | if (cmpxchg(&huge_zero_page, NULL, zero_page)) { |
97ae1749 | 191 | preempt_enable(); |
5ddacbe9 | 192 | __free_pages(zero_page, compound_order(zero_page)); |
97ae1749 KS |
193 | goto retry; |
194 | } | |
195 | ||
196 | /* We take additional reference here. It will be put back by shrinker */ | |
197 | atomic_set(&huge_zero_refcount, 2); | |
198 | preempt_enable(); | |
4db0c3c2 | 199 | return READ_ONCE(huge_zero_page); |
4a6c1297 KS |
200 | } |
201 | ||
97ae1749 | 202 | static void put_huge_zero_page(void) |
4a6c1297 | 203 | { |
97ae1749 KS |
204 | /* |
205 | * Counter should never go to zero here. Only shrinker can put | |
206 | * last reference. | |
207 | */ | |
208 | BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); | |
4a6c1297 KS |
209 | } |
210 | ||
48896466 GC |
211 | static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, |
212 | struct shrink_control *sc) | |
4a6c1297 | 213 | { |
48896466 GC |
214 | /* we can free zero page only if last reference remains */ |
215 | return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; | |
216 | } | |
97ae1749 | 217 | |
48896466 GC |
218 | static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, |
219 | struct shrink_control *sc) | |
220 | { | |
97ae1749 | 221 | if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { |
5918d10a KS |
222 | struct page *zero_page = xchg(&huge_zero_page, NULL); |
223 | BUG_ON(zero_page == NULL); | |
5ddacbe9 | 224 | __free_pages(zero_page, compound_order(zero_page)); |
48896466 | 225 | return HPAGE_PMD_NR; |
97ae1749 KS |
226 | } |
227 | ||
228 | return 0; | |
4a6c1297 KS |
229 | } |
230 | ||
97ae1749 | 231 | static struct shrinker huge_zero_page_shrinker = { |
48896466 GC |
232 | .count_objects = shrink_huge_zero_page_count, |
233 | .scan_objects = shrink_huge_zero_page_scan, | |
97ae1749 KS |
234 | .seeks = DEFAULT_SEEKS, |
235 | }; | |
236 | ||
71e3aac0 | 237 | #ifdef CONFIG_SYSFS |
ba76149f | 238 | |
71e3aac0 AA |
239 | static ssize_t double_flag_show(struct kobject *kobj, |
240 | struct kobj_attribute *attr, char *buf, | |
241 | enum transparent_hugepage_flag enabled, | |
242 | enum transparent_hugepage_flag req_madv) | |
243 | { | |
244 | if (test_bit(enabled, &transparent_hugepage_flags)) { | |
245 | VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags)); | |
246 | return sprintf(buf, "[always] madvise never\n"); | |
247 | } else if (test_bit(req_madv, &transparent_hugepage_flags)) | |
248 | return sprintf(buf, "always [madvise] never\n"); | |
249 | else | |
250 | return sprintf(buf, "always madvise [never]\n"); | |
251 | } | |
252 | static ssize_t double_flag_store(struct kobject *kobj, | |
253 | struct kobj_attribute *attr, | |
254 | const char *buf, size_t count, | |
255 | enum transparent_hugepage_flag enabled, | |
256 | enum transparent_hugepage_flag req_madv) | |
257 | { | |
258 | if (!memcmp("always", buf, | |
259 | min(sizeof("always")-1, count))) { | |
260 | set_bit(enabled, &transparent_hugepage_flags); | |
261 | clear_bit(req_madv, &transparent_hugepage_flags); | |
262 | } else if (!memcmp("madvise", buf, | |
263 | min(sizeof("madvise")-1, count))) { | |
264 | clear_bit(enabled, &transparent_hugepage_flags); | |
265 | set_bit(req_madv, &transparent_hugepage_flags); | |
266 | } else if (!memcmp("never", buf, | |
267 | min(sizeof("never")-1, count))) { | |
268 | clear_bit(enabled, &transparent_hugepage_flags); | |
269 | clear_bit(req_madv, &transparent_hugepage_flags); | |
270 | } else | |
271 | return -EINVAL; | |
272 | ||
273 | return count; | |
274 | } | |
275 | ||
276 | static ssize_t enabled_show(struct kobject *kobj, | |
277 | struct kobj_attribute *attr, char *buf) | |
278 | { | |
279 | return double_flag_show(kobj, attr, buf, | |
280 | TRANSPARENT_HUGEPAGE_FLAG, | |
281 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
282 | } | |
283 | static ssize_t enabled_store(struct kobject *kobj, | |
284 | struct kobj_attribute *attr, | |
285 | const char *buf, size_t count) | |
286 | { | |
ba76149f AA |
287 | ssize_t ret; |
288 | ||
289 | ret = double_flag_store(kobj, attr, buf, count, | |
290 | TRANSPARENT_HUGEPAGE_FLAG, | |
291 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
292 | ||
293 | if (ret > 0) { | |
911891af XG |
294 | int err; |
295 | ||
296 | mutex_lock(&khugepaged_mutex); | |
79553da2 | 297 | err = start_stop_khugepaged(); |
911891af XG |
298 | mutex_unlock(&khugepaged_mutex); |
299 | ||
ba76149f AA |
300 | if (err) |
301 | ret = err; | |
302 | } | |
303 | ||
304 | return ret; | |
71e3aac0 AA |
305 | } |
306 | static struct kobj_attribute enabled_attr = | |
307 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
308 | ||
309 | static ssize_t single_flag_show(struct kobject *kobj, | |
310 | struct kobj_attribute *attr, char *buf, | |
311 | enum transparent_hugepage_flag flag) | |
312 | { | |
e27e6151 BH |
313 | return sprintf(buf, "%d\n", |
314 | !!test_bit(flag, &transparent_hugepage_flags)); | |
71e3aac0 | 315 | } |
e27e6151 | 316 | |
71e3aac0 AA |
317 | static ssize_t single_flag_store(struct kobject *kobj, |
318 | struct kobj_attribute *attr, | |
319 | const char *buf, size_t count, | |
320 | enum transparent_hugepage_flag flag) | |
321 | { | |
e27e6151 BH |
322 | unsigned long value; |
323 | int ret; | |
324 | ||
325 | ret = kstrtoul(buf, 10, &value); | |
326 | if (ret < 0) | |
327 | return ret; | |
328 | if (value > 1) | |
329 | return -EINVAL; | |
330 | ||
331 | if (value) | |
71e3aac0 | 332 | set_bit(flag, &transparent_hugepage_flags); |
e27e6151 | 333 | else |
71e3aac0 | 334 | clear_bit(flag, &transparent_hugepage_flags); |
71e3aac0 AA |
335 | |
336 | return count; | |
337 | } | |
338 | ||
339 | /* | |
340 | * Currently defrag only disables __GFP_NOWAIT for allocation. A blind | |
341 | * __GFP_REPEAT is too aggressive, it's never worth swapping tons of | |
342 | * memory just to allocate one more hugepage. | |
343 | */ | |
344 | static ssize_t defrag_show(struct kobject *kobj, | |
345 | struct kobj_attribute *attr, char *buf) | |
346 | { | |
347 | return double_flag_show(kobj, attr, buf, | |
348 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
349 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
350 | } | |
351 | static ssize_t defrag_store(struct kobject *kobj, | |
352 | struct kobj_attribute *attr, | |
353 | const char *buf, size_t count) | |
354 | { | |
355 | return double_flag_store(kobj, attr, buf, count, | |
356 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
357 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
358 | } | |
359 | static struct kobj_attribute defrag_attr = | |
360 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
361 | ||
79da5407 KS |
362 | static ssize_t use_zero_page_show(struct kobject *kobj, |
363 | struct kobj_attribute *attr, char *buf) | |
364 | { | |
365 | return single_flag_show(kobj, attr, buf, | |
366 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
367 | } | |
368 | static ssize_t use_zero_page_store(struct kobject *kobj, | |
369 | struct kobj_attribute *attr, const char *buf, size_t count) | |
370 | { | |
371 | return single_flag_store(kobj, attr, buf, count, | |
372 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
373 | } | |
374 | static struct kobj_attribute use_zero_page_attr = | |
375 | __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); | |
71e3aac0 AA |
376 | #ifdef CONFIG_DEBUG_VM |
377 | static ssize_t debug_cow_show(struct kobject *kobj, | |
378 | struct kobj_attribute *attr, char *buf) | |
379 | { | |
380 | return single_flag_show(kobj, attr, buf, | |
381 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
382 | } | |
383 | static ssize_t debug_cow_store(struct kobject *kobj, | |
384 | struct kobj_attribute *attr, | |
385 | const char *buf, size_t count) | |
386 | { | |
387 | return single_flag_store(kobj, attr, buf, count, | |
388 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
389 | } | |
390 | static struct kobj_attribute debug_cow_attr = | |
391 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
392 | #endif /* CONFIG_DEBUG_VM */ | |
393 | ||
394 | static struct attribute *hugepage_attr[] = { | |
395 | &enabled_attr.attr, | |
396 | &defrag_attr.attr, | |
79da5407 | 397 | &use_zero_page_attr.attr, |
71e3aac0 AA |
398 | #ifdef CONFIG_DEBUG_VM |
399 | &debug_cow_attr.attr, | |
400 | #endif | |
401 | NULL, | |
402 | }; | |
403 | ||
404 | static struct attribute_group hugepage_attr_group = { | |
405 | .attrs = hugepage_attr, | |
ba76149f AA |
406 | }; |
407 | ||
408 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, | |
409 | struct kobj_attribute *attr, | |
410 | char *buf) | |
411 | { | |
412 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
413 | } | |
414 | ||
415 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
416 | struct kobj_attribute *attr, | |
417 | const char *buf, size_t count) | |
418 | { | |
419 | unsigned long msecs; | |
420 | int err; | |
421 | ||
3dbb95f7 | 422 | err = kstrtoul(buf, 10, &msecs); |
ba76149f AA |
423 | if (err || msecs > UINT_MAX) |
424 | return -EINVAL; | |
425 | ||
426 | khugepaged_scan_sleep_millisecs = msecs; | |
427 | wake_up_interruptible(&khugepaged_wait); | |
428 | ||
429 | return count; | |
430 | } | |
431 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
432 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
433 | scan_sleep_millisecs_store); | |
434 | ||
435 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
436 | struct kobj_attribute *attr, | |
437 | char *buf) | |
438 | { | |
439 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
440 | } | |
441 | ||
442 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
443 | struct kobj_attribute *attr, | |
444 | const char *buf, size_t count) | |
445 | { | |
446 | unsigned long msecs; | |
447 | int err; | |
448 | ||
3dbb95f7 | 449 | err = kstrtoul(buf, 10, &msecs); |
ba76149f AA |
450 | if (err || msecs > UINT_MAX) |
451 | return -EINVAL; | |
452 | ||
453 | khugepaged_alloc_sleep_millisecs = msecs; | |
454 | wake_up_interruptible(&khugepaged_wait); | |
455 | ||
456 | return count; | |
457 | } | |
458 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
459 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
460 | alloc_sleep_millisecs_store); | |
461 | ||
462 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
463 | struct kobj_attribute *attr, | |
464 | char *buf) | |
465 | { | |
466 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
467 | } | |
468 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
469 | struct kobj_attribute *attr, | |
470 | const char *buf, size_t count) | |
471 | { | |
472 | int err; | |
473 | unsigned long pages; | |
474 | ||
3dbb95f7 | 475 | err = kstrtoul(buf, 10, &pages); |
ba76149f AA |
476 | if (err || !pages || pages > UINT_MAX) |
477 | return -EINVAL; | |
478 | ||
479 | khugepaged_pages_to_scan = pages; | |
480 | ||
481 | return count; | |
482 | } | |
483 | static struct kobj_attribute pages_to_scan_attr = | |
484 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
485 | pages_to_scan_store); | |
486 | ||
487 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
488 | struct kobj_attribute *attr, | |
489 | char *buf) | |
490 | { | |
491 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
492 | } | |
493 | static struct kobj_attribute pages_collapsed_attr = | |
494 | __ATTR_RO(pages_collapsed); | |
495 | ||
496 | static ssize_t full_scans_show(struct kobject *kobj, | |
497 | struct kobj_attribute *attr, | |
498 | char *buf) | |
499 | { | |
500 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
501 | } | |
502 | static struct kobj_attribute full_scans_attr = | |
503 | __ATTR_RO(full_scans); | |
504 | ||
505 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
506 | struct kobj_attribute *attr, char *buf) | |
507 | { | |
508 | return single_flag_show(kobj, attr, buf, | |
509 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
510 | } | |
511 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
512 | struct kobj_attribute *attr, | |
513 | const char *buf, size_t count) | |
514 | { | |
515 | return single_flag_store(kobj, attr, buf, count, | |
516 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
517 | } | |
518 | static struct kobj_attribute khugepaged_defrag_attr = | |
519 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
520 | khugepaged_defrag_store); | |
521 | ||
522 | /* | |
523 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
524 | * any unmapped ptes in turn potentially increasing the memory | |
525 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
526 | * reduce the available free memory in the system as it | |
527 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
528 | * free memory in the system during the khugepaged scan. | |
529 | */ | |
530 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
531 | struct kobj_attribute *attr, | |
532 | char *buf) | |
533 | { | |
534 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
535 | } | |
536 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
537 | struct kobj_attribute *attr, | |
538 | const char *buf, size_t count) | |
539 | { | |
540 | int err; | |
541 | unsigned long max_ptes_none; | |
542 | ||
3dbb95f7 | 543 | err = kstrtoul(buf, 10, &max_ptes_none); |
ba76149f AA |
544 | if (err || max_ptes_none > HPAGE_PMD_NR-1) |
545 | return -EINVAL; | |
546 | ||
547 | khugepaged_max_ptes_none = max_ptes_none; | |
548 | ||
549 | return count; | |
550 | } | |
551 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
552 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
553 | khugepaged_max_ptes_none_store); | |
554 | ||
555 | static struct attribute *khugepaged_attr[] = { | |
556 | &khugepaged_defrag_attr.attr, | |
557 | &khugepaged_max_ptes_none_attr.attr, | |
558 | &pages_to_scan_attr.attr, | |
559 | &pages_collapsed_attr.attr, | |
560 | &full_scans_attr.attr, | |
561 | &scan_sleep_millisecs_attr.attr, | |
562 | &alloc_sleep_millisecs_attr.attr, | |
563 | NULL, | |
564 | }; | |
565 | ||
566 | static struct attribute_group khugepaged_attr_group = { | |
567 | .attrs = khugepaged_attr, | |
568 | .name = "khugepaged", | |
71e3aac0 | 569 | }; |
71e3aac0 | 570 | |
569e5590 | 571 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
71e3aac0 | 572 | { |
71e3aac0 AA |
573 | int err; |
574 | ||
569e5590 SL |
575 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); |
576 | if (unlikely(!*hugepage_kobj)) { | |
ae3a8c1c | 577 | pr_err("failed to create transparent hugepage kobject\n"); |
569e5590 | 578 | return -ENOMEM; |
ba76149f AA |
579 | } |
580 | ||
569e5590 | 581 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); |
ba76149f | 582 | if (err) { |
ae3a8c1c | 583 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 584 | goto delete_obj; |
ba76149f AA |
585 | } |
586 | ||
569e5590 | 587 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); |
ba76149f | 588 | if (err) { |
ae3a8c1c | 589 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 590 | goto remove_hp_group; |
ba76149f | 591 | } |
569e5590 SL |
592 | |
593 | return 0; | |
594 | ||
595 | remove_hp_group: | |
596 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
597 | delete_obj: | |
598 | kobject_put(*hugepage_kobj); | |
599 | return err; | |
600 | } | |
601 | ||
602 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
603 | { | |
604 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
605 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
606 | kobject_put(hugepage_kobj); | |
607 | } | |
608 | #else | |
609 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
610 | { | |
611 | return 0; | |
612 | } | |
613 | ||
614 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
615 | { | |
616 | } | |
617 | #endif /* CONFIG_SYSFS */ | |
618 | ||
619 | static int __init hugepage_init(void) | |
620 | { | |
621 | int err; | |
622 | struct kobject *hugepage_kobj; | |
623 | ||
624 | if (!has_transparent_hugepage()) { | |
625 | transparent_hugepage_flags = 0; | |
626 | return -EINVAL; | |
627 | } | |
628 | ||
629 | err = hugepage_init_sysfs(&hugepage_kobj); | |
630 | if (err) | |
65ebb64f | 631 | goto err_sysfs; |
ba76149f AA |
632 | |
633 | err = khugepaged_slab_init(); | |
634 | if (err) | |
65ebb64f | 635 | goto err_slab; |
ba76149f | 636 | |
65ebb64f KS |
637 | err = register_shrinker(&huge_zero_page_shrinker); |
638 | if (err) | |
639 | goto err_hzp_shrinker; | |
97ae1749 | 640 | |
97562cd2 RR |
641 | /* |
642 | * By default disable transparent hugepages on smaller systems, | |
643 | * where the extra memory used could hurt more than TLB overhead | |
644 | * is likely to save. The admin can still enable it through /sys. | |
645 | */ | |
79553da2 | 646 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) { |
97562cd2 | 647 | transparent_hugepage_flags = 0; |
79553da2 KS |
648 | return 0; |
649 | } | |
97562cd2 | 650 | |
79553da2 | 651 | err = start_stop_khugepaged(); |
65ebb64f KS |
652 | if (err) |
653 | goto err_khugepaged; | |
ba76149f | 654 | |
569e5590 | 655 | return 0; |
65ebb64f KS |
656 | err_khugepaged: |
657 | unregister_shrinker(&huge_zero_page_shrinker); | |
658 | err_hzp_shrinker: | |
659 | khugepaged_slab_exit(); | |
660 | err_slab: | |
569e5590 | 661 | hugepage_exit_sysfs(hugepage_kobj); |
65ebb64f | 662 | err_sysfs: |
ba76149f | 663 | return err; |
71e3aac0 | 664 | } |
a64fb3cd | 665 | subsys_initcall(hugepage_init); |
71e3aac0 AA |
666 | |
667 | static int __init setup_transparent_hugepage(char *str) | |
668 | { | |
669 | int ret = 0; | |
670 | if (!str) | |
671 | goto out; | |
672 | if (!strcmp(str, "always")) { | |
673 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
674 | &transparent_hugepage_flags); | |
675 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
676 | &transparent_hugepage_flags); | |
677 | ret = 1; | |
678 | } else if (!strcmp(str, "madvise")) { | |
679 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
680 | &transparent_hugepage_flags); | |
681 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
682 | &transparent_hugepage_flags); | |
683 | ret = 1; | |
684 | } else if (!strcmp(str, "never")) { | |
685 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
686 | &transparent_hugepage_flags); | |
687 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
688 | &transparent_hugepage_flags); | |
689 | ret = 1; | |
690 | } | |
691 | out: | |
692 | if (!ret) | |
ae3a8c1c | 693 | pr_warn("transparent_hugepage= cannot parse, ignored\n"); |
71e3aac0 AA |
694 | return ret; |
695 | } | |
696 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
697 | ||
b32967ff | 698 | pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) |
71e3aac0 AA |
699 | { |
700 | if (likely(vma->vm_flags & VM_WRITE)) | |
701 | pmd = pmd_mkwrite(pmd); | |
702 | return pmd; | |
703 | } | |
704 | ||
3122359a | 705 | static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot) |
b3092b3b BL |
706 | { |
707 | pmd_t entry; | |
3122359a | 708 | entry = mk_pmd(page, prot); |
b3092b3b BL |
709 | entry = pmd_mkhuge(entry); |
710 | return entry; | |
711 | } | |
712 | ||
71e3aac0 AA |
713 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, |
714 | struct vm_area_struct *vma, | |
230c92a8 | 715 | unsigned long address, pmd_t *pmd, |
6b251fc9 AA |
716 | struct page *page, gfp_t gfp, |
717 | unsigned int flags) | |
71e3aac0 | 718 | { |
00501b53 | 719 | struct mem_cgroup *memcg; |
71e3aac0 | 720 | pgtable_t pgtable; |
c4088ebd | 721 | spinlock_t *ptl; |
230c92a8 | 722 | unsigned long haddr = address & HPAGE_PMD_MASK; |
71e3aac0 | 723 | |
309381fe | 724 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
00501b53 | 725 | |
6b251fc9 AA |
726 | if (mem_cgroup_try_charge(page, mm, gfp, &memcg)) { |
727 | put_page(page); | |
728 | count_vm_event(THP_FAULT_FALLBACK); | |
729 | return VM_FAULT_FALLBACK; | |
730 | } | |
00501b53 | 731 | |
71e3aac0 | 732 | pgtable = pte_alloc_one(mm, haddr); |
00501b53 JW |
733 | if (unlikely(!pgtable)) { |
734 | mem_cgroup_cancel_charge(page, memcg); | |
6b251fc9 | 735 | put_page(page); |
71e3aac0 | 736 | return VM_FAULT_OOM; |
00501b53 | 737 | } |
71e3aac0 AA |
738 | |
739 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
52f37629 MK |
740 | /* |
741 | * The memory barrier inside __SetPageUptodate makes sure that | |
742 | * clear_huge_page writes become visible before the set_pmd_at() | |
743 | * write. | |
744 | */ | |
71e3aac0 AA |
745 | __SetPageUptodate(page); |
746 | ||
c4088ebd | 747 | ptl = pmd_lock(mm, pmd); |
71e3aac0 | 748 | if (unlikely(!pmd_none(*pmd))) { |
c4088ebd | 749 | spin_unlock(ptl); |
00501b53 | 750 | mem_cgroup_cancel_charge(page, memcg); |
71e3aac0 AA |
751 | put_page(page); |
752 | pte_free(mm, pgtable); | |
753 | } else { | |
754 | pmd_t entry; | |
6b251fc9 AA |
755 | |
756 | /* Deliver the page fault to userland */ | |
757 | if (userfaultfd_missing(vma)) { | |
758 | int ret; | |
759 | ||
760 | spin_unlock(ptl); | |
761 | mem_cgroup_cancel_charge(page, memcg); | |
762 | put_page(page); | |
763 | pte_free(mm, pgtable); | |
230c92a8 | 764 | ret = handle_userfault(vma, address, flags, |
6b251fc9 AA |
765 | VM_UFFD_MISSING); |
766 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
767 | return ret; | |
768 | } | |
769 | ||
3122359a KS |
770 | entry = mk_huge_pmd(page, vma->vm_page_prot); |
771 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
71e3aac0 | 772 | page_add_new_anon_rmap(page, vma, haddr); |
00501b53 JW |
773 | mem_cgroup_commit_charge(page, memcg, false); |
774 | lru_cache_add_active_or_unevictable(page, vma); | |
6b0b50b0 | 775 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
71e3aac0 | 776 | set_pmd_at(mm, haddr, pmd, entry); |
71e3aac0 | 777 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
e1f56c89 | 778 | atomic_long_inc(&mm->nr_ptes); |
c4088ebd | 779 | spin_unlock(ptl); |
6b251fc9 | 780 | count_vm_event(THP_FAULT_ALLOC); |
71e3aac0 AA |
781 | } |
782 | ||
aa2e878e | 783 | return 0; |
71e3aac0 AA |
784 | } |
785 | ||
cc5d462f | 786 | static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp) |
0bbbc0b3 | 787 | { |
cc5d462f | 788 | return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp; |
0bbbc0b3 AA |
789 | } |
790 | ||
c4088ebd | 791 | /* Caller must hold page table lock. */ |
d295e341 | 792 | static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, |
97ae1749 | 793 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, |
5918d10a | 794 | struct page *zero_page) |
fc9fe822 KS |
795 | { |
796 | pmd_t entry; | |
7c414164 AM |
797 | if (!pmd_none(*pmd)) |
798 | return false; | |
5918d10a | 799 | entry = mk_pmd(zero_page, vma->vm_page_prot); |
fc9fe822 | 800 | entry = pmd_mkhuge(entry); |
6b0b50b0 | 801 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
fc9fe822 | 802 | set_pmd_at(mm, haddr, pmd, entry); |
e1f56c89 | 803 | atomic_long_inc(&mm->nr_ptes); |
7c414164 | 804 | return true; |
fc9fe822 KS |
805 | } |
806 | ||
71e3aac0 AA |
807 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, |
808 | unsigned long address, pmd_t *pmd, | |
809 | unsigned int flags) | |
810 | { | |
077fcf11 | 811 | gfp_t gfp; |
71e3aac0 AA |
812 | struct page *page; |
813 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
71e3aac0 | 814 | |
128ec037 | 815 | if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) |
c0292554 | 816 | return VM_FAULT_FALLBACK; |
128ec037 KS |
817 | if (unlikely(anon_vma_prepare(vma))) |
818 | return VM_FAULT_OOM; | |
6d50e60c | 819 | if (unlikely(khugepaged_enter(vma, vma->vm_flags))) |
128ec037 | 820 | return VM_FAULT_OOM; |
593befa6 | 821 | if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) && |
128ec037 | 822 | transparent_hugepage_use_zero_page()) { |
c4088ebd | 823 | spinlock_t *ptl; |
128ec037 KS |
824 | pgtable_t pgtable; |
825 | struct page *zero_page; | |
826 | bool set; | |
6b251fc9 | 827 | int ret; |
128ec037 KS |
828 | pgtable = pte_alloc_one(mm, haddr); |
829 | if (unlikely(!pgtable)) | |
ba76149f | 830 | return VM_FAULT_OOM; |
128ec037 KS |
831 | zero_page = get_huge_zero_page(); |
832 | if (unlikely(!zero_page)) { | |
833 | pte_free(mm, pgtable); | |
81ab4201 | 834 | count_vm_event(THP_FAULT_FALLBACK); |
c0292554 | 835 | return VM_FAULT_FALLBACK; |
b9bbfbe3 | 836 | } |
c4088ebd | 837 | ptl = pmd_lock(mm, pmd); |
6b251fc9 AA |
838 | ret = 0; |
839 | set = false; | |
840 | if (pmd_none(*pmd)) { | |
841 | if (userfaultfd_missing(vma)) { | |
842 | spin_unlock(ptl); | |
230c92a8 | 843 | ret = handle_userfault(vma, address, flags, |
6b251fc9 AA |
844 | VM_UFFD_MISSING); |
845 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
846 | } else { | |
847 | set_huge_zero_page(pgtable, mm, vma, | |
848 | haddr, pmd, | |
849 | zero_page); | |
850 | spin_unlock(ptl); | |
851 | set = true; | |
852 | } | |
853 | } else | |
854 | spin_unlock(ptl); | |
128ec037 KS |
855 | if (!set) { |
856 | pte_free(mm, pgtable); | |
857 | put_huge_zero_page(); | |
edad9d2c | 858 | } |
6b251fc9 | 859 | return ret; |
71e3aac0 | 860 | } |
077fcf11 AK |
861 | gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0); |
862 | page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); | |
128ec037 KS |
863 | if (unlikely(!page)) { |
864 | count_vm_event(THP_FAULT_FALLBACK); | |
c0292554 | 865 | return VM_FAULT_FALLBACK; |
128ec037 | 866 | } |
230c92a8 AA |
867 | return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp, |
868 | flags); | |
71e3aac0 AA |
869 | } |
870 | ||
ae18d6dc | 871 | static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, |
5cad465d MW |
872 | pmd_t *pmd, unsigned long pfn, pgprot_t prot, bool write) |
873 | { | |
874 | struct mm_struct *mm = vma->vm_mm; | |
875 | pmd_t entry; | |
876 | spinlock_t *ptl; | |
877 | ||
878 | ptl = pmd_lock(mm, pmd); | |
879 | if (pmd_none(*pmd)) { | |
880 | entry = pmd_mkhuge(pfn_pmd(pfn, prot)); | |
881 | if (write) { | |
882 | entry = pmd_mkyoung(pmd_mkdirty(entry)); | |
883 | entry = maybe_pmd_mkwrite(entry, vma); | |
884 | } | |
885 | set_pmd_at(mm, addr, pmd, entry); | |
886 | update_mmu_cache_pmd(vma, addr, pmd); | |
887 | } | |
888 | spin_unlock(ptl); | |
5cad465d MW |
889 | } |
890 | ||
891 | int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, | |
892 | pmd_t *pmd, unsigned long pfn, bool write) | |
893 | { | |
894 | pgprot_t pgprot = vma->vm_page_prot; | |
895 | /* | |
896 | * If we had pmd_special, we could avoid all these restrictions, | |
897 | * but we need to be consistent with PTEs and architectures that | |
898 | * can't support a 'special' bit. | |
899 | */ | |
900 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); | |
901 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == | |
902 | (VM_PFNMAP|VM_MIXEDMAP)); | |
903 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); | |
904 | BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); | |
905 | ||
906 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
907 | return VM_FAULT_SIGBUS; | |
908 | if (track_pfn_insert(vma, &pgprot, pfn)) | |
909 | return VM_FAULT_SIGBUS; | |
ae18d6dc MW |
910 | insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write); |
911 | return VM_FAULT_NOPAGE; | |
5cad465d MW |
912 | } |
913 | ||
71e3aac0 AA |
914 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
915 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
916 | struct vm_area_struct *vma) | |
917 | { | |
c4088ebd | 918 | spinlock_t *dst_ptl, *src_ptl; |
71e3aac0 AA |
919 | struct page *src_page; |
920 | pmd_t pmd; | |
921 | pgtable_t pgtable; | |
922 | int ret; | |
923 | ||
924 | ret = -ENOMEM; | |
925 | pgtable = pte_alloc_one(dst_mm, addr); | |
926 | if (unlikely(!pgtable)) | |
927 | goto out; | |
928 | ||
c4088ebd KS |
929 | dst_ptl = pmd_lock(dst_mm, dst_pmd); |
930 | src_ptl = pmd_lockptr(src_mm, src_pmd); | |
931 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
71e3aac0 AA |
932 | |
933 | ret = -EAGAIN; | |
934 | pmd = *src_pmd; | |
935 | if (unlikely(!pmd_trans_huge(pmd))) { | |
936 | pte_free(dst_mm, pgtable); | |
937 | goto out_unlock; | |
938 | } | |
fc9fe822 | 939 | /* |
c4088ebd | 940 | * When page table lock is held, the huge zero pmd should not be |
fc9fe822 KS |
941 | * under splitting since we don't split the page itself, only pmd to |
942 | * a page table. | |
943 | */ | |
944 | if (is_huge_zero_pmd(pmd)) { | |
5918d10a | 945 | struct page *zero_page; |
97ae1749 KS |
946 | /* |
947 | * get_huge_zero_page() will never allocate a new page here, | |
948 | * since we already have a zero page to copy. It just takes a | |
949 | * reference. | |
950 | */ | |
5918d10a | 951 | zero_page = get_huge_zero_page(); |
6b251fc9 | 952 | set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, |
5918d10a | 953 | zero_page); |
fc9fe822 KS |
954 | ret = 0; |
955 | goto out_unlock; | |
956 | } | |
de466bd6 | 957 | |
71e3aac0 AA |
958 | if (unlikely(pmd_trans_splitting(pmd))) { |
959 | /* split huge page running from under us */ | |
c4088ebd KS |
960 | spin_unlock(src_ptl); |
961 | spin_unlock(dst_ptl); | |
71e3aac0 AA |
962 | pte_free(dst_mm, pgtable); |
963 | ||
964 | wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */ | |
965 | goto out; | |
966 | } | |
967 | src_page = pmd_page(pmd); | |
309381fe | 968 | VM_BUG_ON_PAGE(!PageHead(src_page), src_page); |
71e3aac0 AA |
969 | get_page(src_page); |
970 | page_dup_rmap(src_page); | |
971 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
972 | ||
973 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
974 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
6b0b50b0 | 975 | pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); |
71e3aac0 | 976 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); |
e1f56c89 | 977 | atomic_long_inc(&dst_mm->nr_ptes); |
71e3aac0 AA |
978 | |
979 | ret = 0; | |
980 | out_unlock: | |
c4088ebd KS |
981 | spin_unlock(src_ptl); |
982 | spin_unlock(dst_ptl); | |
71e3aac0 AA |
983 | out: |
984 | return ret; | |
985 | } | |
986 | ||
a1dd450b WD |
987 | void huge_pmd_set_accessed(struct mm_struct *mm, |
988 | struct vm_area_struct *vma, | |
989 | unsigned long address, | |
990 | pmd_t *pmd, pmd_t orig_pmd, | |
991 | int dirty) | |
992 | { | |
c4088ebd | 993 | spinlock_t *ptl; |
a1dd450b WD |
994 | pmd_t entry; |
995 | unsigned long haddr; | |
996 | ||
c4088ebd | 997 | ptl = pmd_lock(mm, pmd); |
a1dd450b WD |
998 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
999 | goto unlock; | |
1000 | ||
1001 | entry = pmd_mkyoung(orig_pmd); | |
1002 | haddr = address & HPAGE_PMD_MASK; | |
1003 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty)) | |
1004 | update_mmu_cache_pmd(vma, address, pmd); | |
1005 | ||
1006 | unlock: | |
c4088ebd | 1007 | spin_unlock(ptl); |
a1dd450b WD |
1008 | } |
1009 | ||
5338a937 HD |
1010 | /* |
1011 | * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages | |
1012 | * during copy_user_huge_page()'s copy_page_rep(): in the case when | |
1013 | * the source page gets split and a tail freed before copy completes. | |
1014 | * Called under pmd_lock of checked pmd, so safe from splitting itself. | |
1015 | */ | |
1016 | static void get_user_huge_page(struct page *page) | |
1017 | { | |
1018 | if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) { | |
1019 | struct page *endpage = page + HPAGE_PMD_NR; | |
1020 | ||
1021 | atomic_add(HPAGE_PMD_NR, &page->_count); | |
1022 | while (++page < endpage) | |
1023 | get_huge_page_tail(page); | |
1024 | } else { | |
1025 | get_page(page); | |
1026 | } | |
1027 | } | |
1028 | ||
1029 | static void put_user_huge_page(struct page *page) | |
1030 | { | |
1031 | if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) { | |
1032 | struct page *endpage = page + HPAGE_PMD_NR; | |
1033 | ||
1034 | while (page < endpage) | |
1035 | put_page(page++); | |
1036 | } else { | |
1037 | put_page(page); | |
1038 | } | |
1039 | } | |
1040 | ||
71e3aac0 AA |
1041 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, |
1042 | struct vm_area_struct *vma, | |
1043 | unsigned long address, | |
1044 | pmd_t *pmd, pmd_t orig_pmd, | |
1045 | struct page *page, | |
1046 | unsigned long haddr) | |
1047 | { | |
00501b53 | 1048 | struct mem_cgroup *memcg; |
c4088ebd | 1049 | spinlock_t *ptl; |
71e3aac0 AA |
1050 | pgtable_t pgtable; |
1051 | pmd_t _pmd; | |
1052 | int ret = 0, i; | |
1053 | struct page **pages; | |
2ec74c3e SG |
1054 | unsigned long mmun_start; /* For mmu_notifiers */ |
1055 | unsigned long mmun_end; /* For mmu_notifiers */ | |
71e3aac0 AA |
1056 | |
1057 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
1058 | GFP_KERNEL); | |
1059 | if (unlikely(!pages)) { | |
1060 | ret |= VM_FAULT_OOM; | |
1061 | goto out; | |
1062 | } | |
1063 | ||
1064 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
cc5d462f AK |
1065 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE | |
1066 | __GFP_OTHER_NODE, | |
19ee151e | 1067 | vma, address, page_to_nid(page)); |
b9bbfbe3 | 1068 | if (unlikely(!pages[i] || |
00501b53 JW |
1069 | mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL, |
1070 | &memcg))) { | |
b9bbfbe3 | 1071 | if (pages[i]) |
71e3aac0 | 1072 | put_page(pages[i]); |
b9bbfbe3 | 1073 | while (--i >= 0) { |
00501b53 JW |
1074 | memcg = (void *)page_private(pages[i]); |
1075 | set_page_private(pages[i], 0); | |
1076 | mem_cgroup_cancel_charge(pages[i], memcg); | |
b9bbfbe3 AA |
1077 | put_page(pages[i]); |
1078 | } | |
71e3aac0 AA |
1079 | kfree(pages); |
1080 | ret |= VM_FAULT_OOM; | |
1081 | goto out; | |
1082 | } | |
00501b53 | 1083 | set_page_private(pages[i], (unsigned long)memcg); |
71e3aac0 AA |
1084 | } |
1085 | ||
1086 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1087 | copy_user_highpage(pages[i], page + i, | |
0089e485 | 1088 | haddr + PAGE_SIZE * i, vma); |
71e3aac0 AA |
1089 | __SetPageUptodate(pages[i]); |
1090 | cond_resched(); | |
1091 | } | |
1092 | ||
2ec74c3e SG |
1093 | mmun_start = haddr; |
1094 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1095 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1096 | ||
c4088ebd | 1097 | ptl = pmd_lock(mm, pmd); |
71e3aac0 AA |
1098 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1099 | goto out_free_pages; | |
309381fe | 1100 | VM_BUG_ON_PAGE(!PageHead(page), page); |
71e3aac0 | 1101 | |
8809aa2d | 1102 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
71e3aac0 AA |
1103 | /* leave pmd empty until pte is filled */ |
1104 | ||
6b0b50b0 | 1105 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
71e3aac0 AA |
1106 | pmd_populate(mm, &_pmd, pgtable); |
1107 | ||
1108 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
1109 | pte_t *pte, entry; | |
1110 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
1111 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
00501b53 JW |
1112 | memcg = (void *)page_private(pages[i]); |
1113 | set_page_private(pages[i], 0); | |
71e3aac0 | 1114 | page_add_new_anon_rmap(pages[i], vma, haddr); |
00501b53 JW |
1115 | mem_cgroup_commit_charge(pages[i], memcg, false); |
1116 | lru_cache_add_active_or_unevictable(pages[i], vma); | |
71e3aac0 AA |
1117 | pte = pte_offset_map(&_pmd, haddr); |
1118 | VM_BUG_ON(!pte_none(*pte)); | |
1119 | set_pte_at(mm, haddr, pte, entry); | |
1120 | pte_unmap(pte); | |
1121 | } | |
1122 | kfree(pages); | |
1123 | ||
71e3aac0 AA |
1124 | smp_wmb(); /* make pte visible before pmd */ |
1125 | pmd_populate(mm, pmd, pgtable); | |
1126 | page_remove_rmap(page); | |
c4088ebd | 1127 | spin_unlock(ptl); |
71e3aac0 | 1128 | |
2ec74c3e SG |
1129 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
1130 | ||
71e3aac0 AA |
1131 | ret |= VM_FAULT_WRITE; |
1132 | put_page(page); | |
1133 | ||
1134 | out: | |
1135 | return ret; | |
1136 | ||
1137 | out_free_pages: | |
c4088ebd | 1138 | spin_unlock(ptl); |
2ec74c3e | 1139 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
b9bbfbe3 | 1140 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
00501b53 JW |
1141 | memcg = (void *)page_private(pages[i]); |
1142 | set_page_private(pages[i], 0); | |
1143 | mem_cgroup_cancel_charge(pages[i], memcg); | |
71e3aac0 | 1144 | put_page(pages[i]); |
b9bbfbe3 | 1145 | } |
71e3aac0 AA |
1146 | kfree(pages); |
1147 | goto out; | |
1148 | } | |
1149 | ||
1150 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
1151 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) | |
1152 | { | |
c4088ebd | 1153 | spinlock_t *ptl; |
71e3aac0 | 1154 | int ret = 0; |
93b4796d | 1155 | struct page *page = NULL, *new_page; |
00501b53 | 1156 | struct mem_cgroup *memcg; |
71e3aac0 | 1157 | unsigned long haddr; |
2ec74c3e SG |
1158 | unsigned long mmun_start; /* For mmu_notifiers */ |
1159 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 1160 | gfp_t huge_gfp; /* for allocation and charge */ |
71e3aac0 | 1161 | |
c4088ebd | 1162 | ptl = pmd_lockptr(mm, pmd); |
81d1b09c | 1163 | VM_BUG_ON_VMA(!vma->anon_vma, vma); |
93b4796d KS |
1164 | haddr = address & HPAGE_PMD_MASK; |
1165 | if (is_huge_zero_pmd(orig_pmd)) | |
1166 | goto alloc; | |
c4088ebd | 1167 | spin_lock(ptl); |
71e3aac0 AA |
1168 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1169 | goto out_unlock; | |
1170 | ||
1171 | page = pmd_page(orig_pmd); | |
309381fe | 1172 | VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); |
71e3aac0 AA |
1173 | if (page_mapcount(page) == 1) { |
1174 | pmd_t entry; | |
1175 | entry = pmd_mkyoung(orig_pmd); | |
1176 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
1177 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) | |
b113da65 | 1178 | update_mmu_cache_pmd(vma, address, pmd); |
71e3aac0 AA |
1179 | ret |= VM_FAULT_WRITE; |
1180 | goto out_unlock; | |
1181 | } | |
5338a937 | 1182 | get_user_huge_page(page); |
c4088ebd | 1183 | spin_unlock(ptl); |
93b4796d | 1184 | alloc: |
71e3aac0 | 1185 | if (transparent_hugepage_enabled(vma) && |
077fcf11 | 1186 | !transparent_hugepage_debug_cow()) { |
3b363692 MH |
1187 | huge_gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0); |
1188 | new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); | |
077fcf11 | 1189 | } else |
71e3aac0 AA |
1190 | new_page = NULL; |
1191 | ||
1192 | if (unlikely(!new_page)) { | |
eecc1e42 | 1193 | if (!page) { |
e9b71ca9 KS |
1194 | split_huge_page_pmd(vma, address, pmd); |
1195 | ret |= VM_FAULT_FALLBACK; | |
93b4796d KS |
1196 | } else { |
1197 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, | |
1198 | pmd, orig_pmd, page, haddr); | |
9845cbbd | 1199 | if (ret & VM_FAULT_OOM) { |
93b4796d | 1200 | split_huge_page(page); |
9845cbbd KS |
1201 | ret |= VM_FAULT_FALLBACK; |
1202 | } | |
5338a937 | 1203 | put_user_huge_page(page); |
93b4796d | 1204 | } |
17766dde | 1205 | count_vm_event(THP_FAULT_FALLBACK); |
71e3aac0 AA |
1206 | goto out; |
1207 | } | |
1208 | ||
3b363692 | 1209 | if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg))) { |
b9bbfbe3 | 1210 | put_page(new_page); |
93b4796d KS |
1211 | if (page) { |
1212 | split_huge_page(page); | |
5338a937 | 1213 | put_user_huge_page(page); |
9845cbbd KS |
1214 | } else |
1215 | split_huge_page_pmd(vma, address, pmd); | |
1216 | ret |= VM_FAULT_FALLBACK; | |
17766dde | 1217 | count_vm_event(THP_FAULT_FALLBACK); |
b9bbfbe3 AA |
1218 | goto out; |
1219 | } | |
1220 | ||
17766dde DR |
1221 | count_vm_event(THP_FAULT_ALLOC); |
1222 | ||
eecc1e42 | 1223 | if (!page) |
93b4796d KS |
1224 | clear_huge_page(new_page, haddr, HPAGE_PMD_NR); |
1225 | else | |
1226 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); | |
71e3aac0 AA |
1227 | __SetPageUptodate(new_page); |
1228 | ||
2ec74c3e SG |
1229 | mmun_start = haddr; |
1230 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1231 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1232 | ||
c4088ebd | 1233 | spin_lock(ptl); |
93b4796d | 1234 | if (page) |
5338a937 | 1235 | put_user_huge_page(page); |
b9bbfbe3 | 1236 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { |
c4088ebd | 1237 | spin_unlock(ptl); |
00501b53 | 1238 | mem_cgroup_cancel_charge(new_page, memcg); |
71e3aac0 | 1239 | put_page(new_page); |
2ec74c3e | 1240 | goto out_mn; |
b9bbfbe3 | 1241 | } else { |
71e3aac0 | 1242 | pmd_t entry; |
3122359a KS |
1243 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); |
1244 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
8809aa2d | 1245 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
71e3aac0 | 1246 | page_add_new_anon_rmap(new_page, vma, haddr); |
00501b53 JW |
1247 | mem_cgroup_commit_charge(new_page, memcg, false); |
1248 | lru_cache_add_active_or_unevictable(new_page, vma); | |
71e3aac0 | 1249 | set_pmd_at(mm, haddr, pmd, entry); |
b113da65 | 1250 | update_mmu_cache_pmd(vma, address, pmd); |
eecc1e42 | 1251 | if (!page) { |
93b4796d | 1252 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
97ae1749 KS |
1253 | put_huge_zero_page(); |
1254 | } else { | |
309381fe | 1255 | VM_BUG_ON_PAGE(!PageHead(page), page); |
93b4796d KS |
1256 | page_remove_rmap(page); |
1257 | put_page(page); | |
1258 | } | |
71e3aac0 AA |
1259 | ret |= VM_FAULT_WRITE; |
1260 | } | |
c4088ebd | 1261 | spin_unlock(ptl); |
2ec74c3e SG |
1262 | out_mn: |
1263 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
71e3aac0 AA |
1264 | out: |
1265 | return ret; | |
2ec74c3e | 1266 | out_unlock: |
c4088ebd | 1267 | spin_unlock(ptl); |
2ec74c3e | 1268 | return ret; |
71e3aac0 AA |
1269 | } |
1270 | ||
b676b293 | 1271 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, |
71e3aac0 AA |
1272 | unsigned long addr, |
1273 | pmd_t *pmd, | |
1274 | unsigned int flags) | |
1275 | { | |
b676b293 | 1276 | struct mm_struct *mm = vma->vm_mm; |
71e3aac0 AA |
1277 | struct page *page = NULL; |
1278 | ||
c4088ebd | 1279 | assert_spin_locked(pmd_lockptr(mm, pmd)); |
71e3aac0 AA |
1280 | |
1281 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1282 | goto out; | |
1283 | ||
85facf25 KS |
1284 | /* Avoid dumping huge zero page */ |
1285 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) | |
1286 | return ERR_PTR(-EFAULT); | |
1287 | ||
2b4847e7 | 1288 | /* Full NUMA hinting faults to serialise migration in fault paths */ |
8a0516ed | 1289 | if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) |
2b4847e7 MG |
1290 | goto out; |
1291 | ||
71e3aac0 | 1292 | page = pmd_page(*pmd); |
309381fe | 1293 | VM_BUG_ON_PAGE(!PageHead(page), page); |
71e3aac0 AA |
1294 | if (flags & FOLL_TOUCH) { |
1295 | pmd_t _pmd; | |
1296 | /* | |
1297 | * We should set the dirty bit only for FOLL_WRITE but | |
1298 | * for now the dirty bit in the pmd is meaningless. | |
1299 | * And if the dirty bit will become meaningful and | |
1300 | * we'll only set it with FOLL_WRITE, an atomic | |
1301 | * set_bit will be required on the pmd to set the | |
1302 | * young bit, instead of the current set_pmd_at. | |
1303 | */ | |
1304 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
8663890a AK |
1305 | if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, |
1306 | pmd, _pmd, 1)) | |
1307 | update_mmu_cache_pmd(vma, addr, pmd); | |
71e3aac0 | 1308 | } |
84d33df2 | 1309 | if ((flags & FOLL_POPULATE) && (vma->vm_flags & VM_LOCKED)) { |
b676b293 DR |
1310 | if (page->mapping && trylock_page(page)) { |
1311 | lru_add_drain(); | |
1312 | if (page->mapping) | |
1313 | mlock_vma_page(page); | |
1314 | unlock_page(page); | |
1315 | } | |
1316 | } | |
71e3aac0 | 1317 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
309381fe | 1318 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
71e3aac0 | 1319 | if (flags & FOLL_GET) |
70b50f94 | 1320 | get_page_foll(page); |
71e3aac0 AA |
1321 | |
1322 | out: | |
1323 | return page; | |
1324 | } | |
1325 | ||
d10e63f2 | 1326 | /* NUMA hinting page fault entry point for trans huge pmds */ |
4daae3b4 MG |
1327 | int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, |
1328 | unsigned long addr, pmd_t pmd, pmd_t *pmdp) | |
d10e63f2 | 1329 | { |
c4088ebd | 1330 | spinlock_t *ptl; |
b8916634 | 1331 | struct anon_vma *anon_vma = NULL; |
b32967ff | 1332 | struct page *page; |
d10e63f2 | 1333 | unsigned long haddr = addr & HPAGE_PMD_MASK; |
8191acbd | 1334 | int page_nid = -1, this_nid = numa_node_id(); |
90572890 | 1335 | int target_nid, last_cpupid = -1; |
8191acbd MG |
1336 | bool page_locked; |
1337 | bool migrated = false; | |
b191f9b1 | 1338 | bool was_writable; |
6688cc05 | 1339 | int flags = 0; |
d10e63f2 | 1340 | |
c0e7cad9 MG |
1341 | /* A PROT_NONE fault should not end up here */ |
1342 | BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))); | |
1343 | ||
c4088ebd | 1344 | ptl = pmd_lock(mm, pmdp); |
d10e63f2 MG |
1345 | if (unlikely(!pmd_same(pmd, *pmdp))) |
1346 | goto out_unlock; | |
1347 | ||
de466bd6 MG |
1348 | /* |
1349 | * If there are potential migrations, wait for completion and retry | |
1350 | * without disrupting NUMA hinting information. Do not relock and | |
1351 | * check_same as the page may no longer be mapped. | |
1352 | */ | |
1353 | if (unlikely(pmd_trans_migrating(*pmdp))) { | |
5d833062 | 1354 | page = pmd_page(*pmdp); |
de466bd6 | 1355 | spin_unlock(ptl); |
5d833062 | 1356 | wait_on_page_locked(page); |
de466bd6 MG |
1357 | goto out; |
1358 | } | |
1359 | ||
d10e63f2 | 1360 | page = pmd_page(pmd); |
a1a46184 | 1361 | BUG_ON(is_huge_zero_page(page)); |
8191acbd | 1362 | page_nid = page_to_nid(page); |
90572890 | 1363 | last_cpupid = page_cpupid_last(page); |
03c5a6e1 | 1364 | count_vm_numa_event(NUMA_HINT_FAULTS); |
04bb2f94 | 1365 | if (page_nid == this_nid) { |
03c5a6e1 | 1366 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
04bb2f94 RR |
1367 | flags |= TNF_FAULT_LOCAL; |
1368 | } | |
4daae3b4 | 1369 | |
bea66fbd MG |
1370 | /* See similar comment in do_numa_page for explanation */ |
1371 | if (!(vma->vm_flags & VM_WRITE)) | |
6688cc05 PZ |
1372 | flags |= TNF_NO_GROUP; |
1373 | ||
ff9042b1 MG |
1374 | /* |
1375 | * Acquire the page lock to serialise THP migrations but avoid dropping | |
1376 | * page_table_lock if at all possible | |
1377 | */ | |
b8916634 MG |
1378 | page_locked = trylock_page(page); |
1379 | target_nid = mpol_misplaced(page, vma, haddr); | |
1380 | if (target_nid == -1) { | |
1381 | /* If the page was locked, there are no parallel migrations */ | |
a54a407f | 1382 | if (page_locked) |
b8916634 | 1383 | goto clear_pmdnuma; |
2b4847e7 | 1384 | } |
4daae3b4 | 1385 | |
de466bd6 | 1386 | /* Migration could have started since the pmd_trans_migrating check */ |
2b4847e7 | 1387 | if (!page_locked) { |
c4088ebd | 1388 | spin_unlock(ptl); |
b8916634 | 1389 | wait_on_page_locked(page); |
a54a407f | 1390 | page_nid = -1; |
b8916634 MG |
1391 | goto out; |
1392 | } | |
1393 | ||
2b4847e7 MG |
1394 | /* |
1395 | * Page is misplaced. Page lock serialises migrations. Acquire anon_vma | |
1396 | * to serialises splits | |
1397 | */ | |
b8916634 | 1398 | get_page(page); |
c4088ebd | 1399 | spin_unlock(ptl); |
b8916634 | 1400 | anon_vma = page_lock_anon_vma_read(page); |
4daae3b4 | 1401 | |
c69307d5 | 1402 | /* Confirm the PMD did not change while page_table_lock was released */ |
c4088ebd | 1403 | spin_lock(ptl); |
b32967ff MG |
1404 | if (unlikely(!pmd_same(pmd, *pmdp))) { |
1405 | unlock_page(page); | |
1406 | put_page(page); | |
a54a407f | 1407 | page_nid = -1; |
4daae3b4 | 1408 | goto out_unlock; |
b32967ff | 1409 | } |
ff9042b1 | 1410 | |
c3a489ca MG |
1411 | /* Bail if we fail to protect against THP splits for any reason */ |
1412 | if (unlikely(!anon_vma)) { | |
1413 | put_page(page); | |
1414 | page_nid = -1; | |
1415 | goto clear_pmdnuma; | |
1416 | } | |
1417 | ||
a54a407f MG |
1418 | /* |
1419 | * Migrate the THP to the requested node, returns with page unlocked | |
8a0516ed | 1420 | * and access rights restored. |
a54a407f | 1421 | */ |
c4088ebd | 1422 | spin_unlock(ptl); |
b32967ff | 1423 | migrated = migrate_misplaced_transhuge_page(mm, vma, |
340ef390 | 1424 | pmdp, pmd, addr, page, target_nid); |
6688cc05 PZ |
1425 | if (migrated) { |
1426 | flags |= TNF_MIGRATED; | |
8191acbd | 1427 | page_nid = target_nid; |
074c2381 MG |
1428 | } else |
1429 | flags |= TNF_MIGRATE_FAIL; | |
b32967ff | 1430 | |
8191acbd | 1431 | goto out; |
b32967ff | 1432 | clear_pmdnuma: |
a54a407f | 1433 | BUG_ON(!PageLocked(page)); |
b191f9b1 | 1434 | was_writable = pmd_write(pmd); |
4d942466 | 1435 | pmd = pmd_modify(pmd, vma->vm_page_prot); |
b7b04004 | 1436 | pmd = pmd_mkyoung(pmd); |
b191f9b1 MG |
1437 | if (was_writable) |
1438 | pmd = pmd_mkwrite(pmd); | |
d10e63f2 | 1439 | set_pmd_at(mm, haddr, pmdp, pmd); |
d10e63f2 | 1440 | update_mmu_cache_pmd(vma, addr, pmdp); |
a54a407f | 1441 | unlock_page(page); |
d10e63f2 | 1442 | out_unlock: |
c4088ebd | 1443 | spin_unlock(ptl); |
b8916634 MG |
1444 | |
1445 | out: | |
1446 | if (anon_vma) | |
1447 | page_unlock_anon_vma_read(anon_vma); | |
1448 | ||
8191acbd | 1449 | if (page_nid != -1) |
6688cc05 | 1450 | task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags); |
8191acbd | 1451 | |
d10e63f2 MG |
1452 | return 0; |
1453 | } | |
1454 | ||
71e3aac0 | 1455 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
f21760b1 | 1456 | pmd_t *pmd, unsigned long addr) |
71e3aac0 | 1457 | { |
da146769 | 1458 | pmd_t orig_pmd; |
bf929152 | 1459 | spinlock_t *ptl; |
71e3aac0 | 1460 | |
da146769 KS |
1461 | if (__pmd_trans_huge_lock(pmd, vma, &ptl) != 1) |
1462 | return 0; | |
1463 | /* | |
1464 | * For architectures like ppc64 we look at deposited pgtable | |
1465 | * when calling pmdp_huge_get_and_clear. So do the | |
1466 | * pgtable_trans_huge_withdraw after finishing pmdp related | |
1467 | * operations. | |
1468 | */ | |
1469 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1470 | tlb->fullmm); | |
1471 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1472 | if (vma_is_dax(vma)) { | |
1473 | spin_unlock(ptl); | |
1474 | if (is_huge_zero_pmd(orig_pmd)) | |
97ae1749 | 1475 | put_huge_zero_page(); |
da146769 KS |
1476 | } else if (is_huge_zero_pmd(orig_pmd)) { |
1477 | pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); | |
1478 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1479 | spin_unlock(ptl); | |
1480 | put_huge_zero_page(); | |
1481 | } else { | |
1482 | struct page *page = pmd_page(orig_pmd); | |
1483 | page_remove_rmap(page); | |
1484 | VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); | |
1485 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1486 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
1487 | pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); | |
1488 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1489 | spin_unlock(ptl); | |
1490 | tlb_remove_page(tlb, page); | |
025c5b24 | 1491 | } |
da146769 | 1492 | return 1; |
71e3aac0 AA |
1493 | } |
1494 | ||
37a1c49a AA |
1495 | int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, |
1496 | unsigned long old_addr, | |
1497 | unsigned long new_addr, unsigned long old_end, | |
1498 | pmd_t *old_pmd, pmd_t *new_pmd) | |
1499 | { | |
bf929152 | 1500 | spinlock_t *old_ptl, *new_ptl; |
37a1c49a AA |
1501 | int ret = 0; |
1502 | pmd_t pmd; | |
1503 | ||
1504 | struct mm_struct *mm = vma->vm_mm; | |
1505 | ||
1506 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1507 | (new_addr & ~HPAGE_PMD_MASK) || | |
1508 | old_end - old_addr < HPAGE_PMD_SIZE || | |
1509 | (new_vma->vm_flags & VM_NOHUGEPAGE)) | |
1510 | goto out; | |
1511 | ||
1512 | /* | |
1513 | * The destination pmd shouldn't be established, free_pgtables() | |
1514 | * should have release it. | |
1515 | */ | |
1516 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1517 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
1518 | goto out; | |
1519 | } | |
1520 | ||
bf929152 KS |
1521 | /* |
1522 | * We don't have to worry about the ordering of src and dst | |
1523 | * ptlocks because exclusive mmap_sem prevents deadlock. | |
1524 | */ | |
1525 | ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl); | |
025c5b24 | 1526 | if (ret == 1) { |
bf929152 KS |
1527 | new_ptl = pmd_lockptr(mm, new_pmd); |
1528 | if (new_ptl != old_ptl) | |
1529 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); | |
8809aa2d | 1530 | pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); |
025c5b24 | 1531 | VM_BUG_ON(!pmd_none(*new_pmd)); |
3592806c | 1532 | |
b3084f4d AK |
1533 | if (pmd_move_must_withdraw(new_ptl, old_ptl)) { |
1534 | pgtable_t pgtable; | |
3592806c KS |
1535 | pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); |
1536 | pgtable_trans_huge_deposit(mm, new_pmd, pgtable); | |
3592806c | 1537 | } |
b3084f4d AK |
1538 | set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); |
1539 | if (new_ptl != old_ptl) | |
1540 | spin_unlock(new_ptl); | |
bf929152 | 1541 | spin_unlock(old_ptl); |
37a1c49a AA |
1542 | } |
1543 | out: | |
1544 | return ret; | |
1545 | } | |
1546 | ||
f123d74a MG |
1547 | /* |
1548 | * Returns | |
1549 | * - 0 if PMD could not be locked | |
1550 | * - 1 if PMD was locked but protections unchange and TLB flush unnecessary | |
1551 | * - HPAGE_PMD_NR is protections changed and TLB flush necessary | |
1552 | */ | |
cd7548ab | 1553 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
e944fd67 | 1554 | unsigned long addr, pgprot_t newprot, int prot_numa) |
cd7548ab JW |
1555 | { |
1556 | struct mm_struct *mm = vma->vm_mm; | |
bf929152 | 1557 | spinlock_t *ptl; |
cd7548ab JW |
1558 | int ret = 0; |
1559 | ||
bf929152 | 1560 | if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) { |
025c5b24 | 1561 | pmd_t entry; |
b191f9b1 | 1562 | bool preserve_write = prot_numa && pmd_write(*pmd); |
ba68bc01 | 1563 | ret = 1; |
e944fd67 MG |
1564 | |
1565 | /* | |
1566 | * Avoid trapping faults against the zero page. The read-only | |
1567 | * data is likely to be read-cached on the local CPU and | |
1568 | * local/remote hits to the zero page are not interesting. | |
1569 | */ | |
1570 | if (prot_numa && is_huge_zero_pmd(*pmd)) { | |
1571 | spin_unlock(ptl); | |
ba68bc01 | 1572 | return ret; |
e944fd67 MG |
1573 | } |
1574 | ||
10c1045f | 1575 | if (!prot_numa || !pmd_protnone(*pmd)) { |
8809aa2d | 1576 | entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd); |
10c1045f | 1577 | entry = pmd_modify(entry, newprot); |
b191f9b1 MG |
1578 | if (preserve_write) |
1579 | entry = pmd_mkwrite(entry); | |
10c1045f MG |
1580 | ret = HPAGE_PMD_NR; |
1581 | set_pmd_at(mm, addr, pmd, entry); | |
b191f9b1 | 1582 | BUG_ON(!preserve_write && pmd_write(entry)); |
10c1045f | 1583 | } |
bf929152 | 1584 | spin_unlock(ptl); |
025c5b24 NH |
1585 | } |
1586 | ||
1587 | return ret; | |
1588 | } | |
1589 | ||
1590 | /* | |
1591 | * Returns 1 if a given pmd maps a stable (not under splitting) thp. | |
1592 | * Returns -1 if it maps a thp under splitting. Returns 0 otherwise. | |
1593 | * | |
1594 | * Note that if it returns 1, this routine returns without unlocking page | |
1595 | * table locks. So callers must unlock them. | |
1596 | */ | |
bf929152 KS |
1597 | int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma, |
1598 | spinlock_t **ptl) | |
025c5b24 | 1599 | { |
bf929152 | 1600 | *ptl = pmd_lock(vma->vm_mm, pmd); |
cd7548ab JW |
1601 | if (likely(pmd_trans_huge(*pmd))) { |
1602 | if (unlikely(pmd_trans_splitting(*pmd))) { | |
bf929152 | 1603 | spin_unlock(*ptl); |
cd7548ab | 1604 | wait_split_huge_page(vma->anon_vma, pmd); |
025c5b24 | 1605 | return -1; |
cd7548ab | 1606 | } else { |
025c5b24 NH |
1607 | /* Thp mapped by 'pmd' is stable, so we can |
1608 | * handle it as it is. */ | |
1609 | return 1; | |
cd7548ab | 1610 | } |
025c5b24 | 1611 | } |
bf929152 | 1612 | spin_unlock(*ptl); |
025c5b24 | 1613 | return 0; |
cd7548ab JW |
1614 | } |
1615 | ||
117b0791 KS |
1616 | /* |
1617 | * This function returns whether a given @page is mapped onto the @address | |
1618 | * in the virtual space of @mm. | |
1619 | * | |
1620 | * When it's true, this function returns *pmd with holding the page table lock | |
1621 | * and passing it back to the caller via @ptl. | |
1622 | * If it's false, returns NULL without holding the page table lock. | |
1623 | */ | |
71e3aac0 AA |
1624 | pmd_t *page_check_address_pmd(struct page *page, |
1625 | struct mm_struct *mm, | |
1626 | unsigned long address, | |
117b0791 KS |
1627 | enum page_check_address_pmd_flag flag, |
1628 | spinlock_t **ptl) | |
71e3aac0 | 1629 | { |
b5a8cad3 KS |
1630 | pgd_t *pgd; |
1631 | pud_t *pud; | |
117b0791 | 1632 | pmd_t *pmd; |
71e3aac0 AA |
1633 | |
1634 | if (address & ~HPAGE_PMD_MASK) | |
117b0791 | 1635 | return NULL; |
71e3aac0 | 1636 | |
b5a8cad3 KS |
1637 | pgd = pgd_offset(mm, address); |
1638 | if (!pgd_present(*pgd)) | |
117b0791 | 1639 | return NULL; |
b5a8cad3 KS |
1640 | pud = pud_offset(pgd, address); |
1641 | if (!pud_present(*pud)) | |
1642 | return NULL; | |
1643 | pmd = pmd_offset(pud, address); | |
1644 | ||
117b0791 | 1645 | *ptl = pmd_lock(mm, pmd); |
b5a8cad3 | 1646 | if (!pmd_present(*pmd)) |
117b0791 | 1647 | goto unlock; |
71e3aac0 | 1648 | if (pmd_page(*pmd) != page) |
117b0791 | 1649 | goto unlock; |
94fcc585 AA |
1650 | /* |
1651 | * split_vma() may create temporary aliased mappings. There is | |
1652 | * no risk as long as all huge pmd are found and have their | |
1653 | * splitting bit set before __split_huge_page_refcount | |
1654 | * runs. Finding the same huge pmd more than once during the | |
1655 | * same rmap walk is not a problem. | |
1656 | */ | |
1657 | if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG && | |
1658 | pmd_trans_splitting(*pmd)) | |
117b0791 | 1659 | goto unlock; |
71e3aac0 AA |
1660 | if (pmd_trans_huge(*pmd)) { |
1661 | VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG && | |
1662 | !pmd_trans_splitting(*pmd)); | |
117b0791 | 1663 | return pmd; |
71e3aac0 | 1664 | } |
117b0791 KS |
1665 | unlock: |
1666 | spin_unlock(*ptl); | |
1667 | return NULL; | |
71e3aac0 AA |
1668 | } |
1669 | ||
1670 | static int __split_huge_page_splitting(struct page *page, | |
1671 | struct vm_area_struct *vma, | |
1672 | unsigned long address) | |
1673 | { | |
1674 | struct mm_struct *mm = vma->vm_mm; | |
117b0791 | 1675 | spinlock_t *ptl; |
71e3aac0 AA |
1676 | pmd_t *pmd; |
1677 | int ret = 0; | |
2ec74c3e SG |
1678 | /* For mmu_notifiers */ |
1679 | const unsigned long mmun_start = address; | |
1680 | const unsigned long mmun_end = address + HPAGE_PMD_SIZE; | |
71e3aac0 | 1681 | |
2ec74c3e | 1682 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
71e3aac0 | 1683 | pmd = page_check_address_pmd(page, mm, address, |
117b0791 | 1684 | PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl); |
71e3aac0 AA |
1685 | if (pmd) { |
1686 | /* | |
1687 | * We can't temporarily set the pmd to null in order | |
1688 | * to split it, the pmd must remain marked huge at all | |
1689 | * times or the VM won't take the pmd_trans_huge paths | |
5a505085 | 1690 | * and it won't wait on the anon_vma->root->rwsem to |
71e3aac0 AA |
1691 | * serialize against split_huge_page*. |
1692 | */ | |
2ec74c3e | 1693 | pmdp_splitting_flush(vma, address, pmd); |
34ee645e | 1694 | |
71e3aac0 | 1695 | ret = 1; |
117b0791 | 1696 | spin_unlock(ptl); |
71e3aac0 | 1697 | } |
2ec74c3e | 1698 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
71e3aac0 AA |
1699 | |
1700 | return ret; | |
1701 | } | |
1702 | ||
5bc7b8ac SL |
1703 | static void __split_huge_page_refcount(struct page *page, |
1704 | struct list_head *list) | |
71e3aac0 AA |
1705 | { |
1706 | int i; | |
71e3aac0 | 1707 | struct zone *zone = page_zone(page); |
fa9add64 | 1708 | struct lruvec *lruvec; |
70b50f94 | 1709 | int tail_count = 0; |
71e3aac0 AA |
1710 | |
1711 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
1712 | spin_lock_irq(&zone->lru_lock); | |
fa9add64 HD |
1713 | lruvec = mem_cgroup_page_lruvec(page, zone); |
1714 | ||
71e3aac0 | 1715 | compound_lock(page); |
e94c8a9c KH |
1716 | /* complete memcg works before add pages to LRU */ |
1717 | mem_cgroup_split_huge_fixup(page); | |
71e3aac0 | 1718 | |
45676885 | 1719 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { |
71e3aac0 AA |
1720 | struct page *page_tail = page + i; |
1721 | ||
70b50f94 AA |
1722 | /* tail_page->_mapcount cannot change */ |
1723 | BUG_ON(page_mapcount(page_tail) < 0); | |
1724 | tail_count += page_mapcount(page_tail); | |
1725 | /* check for overflow */ | |
1726 | BUG_ON(tail_count < 0); | |
1727 | BUG_ON(atomic_read(&page_tail->_count) != 0); | |
1728 | /* | |
1729 | * tail_page->_count is zero and not changing from | |
1730 | * under us. But get_page_unless_zero() may be running | |
1731 | * from under us on the tail_page. If we used | |
1732 | * atomic_set() below instead of atomic_add(), we | |
1733 | * would then run atomic_set() concurrently with | |
1734 | * get_page_unless_zero(), and atomic_set() is | |
1735 | * implemented in C not using locked ops. spin_unlock | |
1736 | * on x86 sometime uses locked ops because of PPro | |
1737 | * errata 66, 92, so unless somebody can guarantee | |
1738 | * atomic_set() here would be safe on all archs (and | |
1739 | * not only on x86), it's safer to use atomic_add(). | |
1740 | */ | |
1741 | atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1, | |
1742 | &page_tail->_count); | |
71e3aac0 AA |
1743 | |
1744 | /* after clearing PageTail the gup refcount can be released */ | |
3a79d52a | 1745 | smp_mb__after_atomic(); |
71e3aac0 | 1746 | |
f4c18e6f | 1747 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; |
71e3aac0 AA |
1748 | page_tail->flags |= (page->flags & |
1749 | ((1L << PG_referenced) | | |
1750 | (1L << PG_swapbacked) | | |
1751 | (1L << PG_mlocked) | | |
e180cf80 KS |
1752 | (1L << PG_uptodate) | |
1753 | (1L << PG_active) | | |
1754 | (1L << PG_unevictable))); | |
71e3aac0 AA |
1755 | page_tail->flags |= (1L << PG_dirty); |
1756 | ||
70b50f94 | 1757 | /* clear PageTail before overwriting first_page */ |
71e3aac0 AA |
1758 | smp_wmb(); |
1759 | ||
1760 | /* | |
1761 | * __split_huge_page_splitting() already set the | |
1762 | * splitting bit in all pmd that could map this | |
1763 | * hugepage, that will ensure no CPU can alter the | |
1764 | * mapcount on the head page. The mapcount is only | |
1765 | * accounted in the head page and it has to be | |
1766 | * transferred to all tail pages in the below code. So | |
1767 | * for this code to be safe, the split the mapcount | |
1768 | * can't change. But that doesn't mean userland can't | |
1769 | * keep changing and reading the page contents while | |
1770 | * we transfer the mapcount, so the pmd splitting | |
1771 | * status is achieved setting a reserved bit in the | |
1772 | * pmd, not by clearing the present bit. | |
1773 | */ | |
71e3aac0 AA |
1774 | page_tail->_mapcount = page->_mapcount; |
1775 | ||
1776 | BUG_ON(page_tail->mapping); | |
1777 | page_tail->mapping = page->mapping; | |
1778 | ||
45676885 | 1779 | page_tail->index = page->index + i; |
90572890 | 1780 | page_cpupid_xchg_last(page_tail, page_cpupid_last(page)); |
71e3aac0 AA |
1781 | |
1782 | BUG_ON(!PageAnon(page_tail)); | |
1783 | BUG_ON(!PageUptodate(page_tail)); | |
1784 | BUG_ON(!PageDirty(page_tail)); | |
1785 | BUG_ON(!PageSwapBacked(page_tail)); | |
1786 | ||
5bc7b8ac | 1787 | lru_add_page_tail(page, page_tail, lruvec, list); |
71e3aac0 | 1788 | } |
70b50f94 AA |
1789 | atomic_sub(tail_count, &page->_count); |
1790 | BUG_ON(atomic_read(&page->_count) <= 0); | |
71e3aac0 | 1791 | |
fa9add64 | 1792 | __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1); |
79134171 | 1793 | |
71e3aac0 AA |
1794 | ClearPageCompound(page); |
1795 | compound_unlock(page); | |
1796 | spin_unlock_irq(&zone->lru_lock); | |
1797 | ||
1798 | for (i = 1; i < HPAGE_PMD_NR; i++) { | |
1799 | struct page *page_tail = page + i; | |
1800 | BUG_ON(page_count(page_tail) <= 0); | |
1801 | /* | |
1802 | * Tail pages may be freed if there wasn't any mapping | |
1803 | * like if add_to_swap() is running on a lru page that | |
1804 | * had its mapping zapped. And freeing these pages | |
1805 | * requires taking the lru_lock so we do the put_page | |
1806 | * of the tail pages after the split is complete. | |
1807 | */ | |
1808 | put_page(page_tail); | |
1809 | } | |
1810 | ||
1811 | /* | |
1812 | * Only the head page (now become a regular page) is required | |
1813 | * to be pinned by the caller. | |
1814 | */ | |
1815 | BUG_ON(page_count(page) <= 0); | |
1816 | } | |
1817 | ||
1818 | static int __split_huge_page_map(struct page *page, | |
1819 | struct vm_area_struct *vma, | |
1820 | unsigned long address) | |
1821 | { | |
1822 | struct mm_struct *mm = vma->vm_mm; | |
117b0791 | 1823 | spinlock_t *ptl; |
71e3aac0 AA |
1824 | pmd_t *pmd, _pmd; |
1825 | int ret = 0, i; | |
1826 | pgtable_t pgtable; | |
1827 | unsigned long haddr; | |
1828 | ||
71e3aac0 | 1829 | pmd = page_check_address_pmd(page, mm, address, |
117b0791 | 1830 | PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl); |
71e3aac0 | 1831 | if (pmd) { |
6b0b50b0 | 1832 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
71e3aac0 | 1833 | pmd_populate(mm, &_pmd, pgtable); |
f8303c25 WL |
1834 | if (pmd_write(*pmd)) |
1835 | BUG_ON(page_mapcount(page) != 1); | |
71e3aac0 | 1836 | |
e3ebcf64 GS |
1837 | haddr = address; |
1838 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
71e3aac0 AA |
1839 | pte_t *pte, entry; |
1840 | BUG_ON(PageCompound(page+i)); | |
abc40bd2 | 1841 | /* |
8a0516ed MG |
1842 | * Note that NUMA hinting access restrictions are not |
1843 | * transferred to avoid any possibility of altering | |
1844 | * permissions across VMAs. | |
abc40bd2 | 1845 | */ |
71e3aac0 AA |
1846 | entry = mk_pte(page + i, vma->vm_page_prot); |
1847 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
1848 | if (!pmd_write(*pmd)) | |
1849 | entry = pte_wrprotect(entry); | |
71e3aac0 AA |
1850 | if (!pmd_young(*pmd)) |
1851 | entry = pte_mkold(entry); | |
1852 | pte = pte_offset_map(&_pmd, haddr); | |
1853 | BUG_ON(!pte_none(*pte)); | |
1854 | set_pte_at(mm, haddr, pte, entry); | |
1855 | pte_unmap(pte); | |
1856 | } | |
1857 | ||
71e3aac0 AA |
1858 | smp_wmb(); /* make pte visible before pmd */ |
1859 | /* | |
1860 | * Up to this point the pmd is present and huge and | |
1861 | * userland has the whole access to the hugepage | |
1862 | * during the split (which happens in place). If we | |
1863 | * overwrite the pmd with the not-huge version | |
1864 | * pointing to the pte here (which of course we could | |
1865 | * if all CPUs were bug free), userland could trigger | |
1866 | * a small page size TLB miss on the small sized TLB | |
1867 | * while the hugepage TLB entry is still established | |
1868 | * in the huge TLB. Some CPU doesn't like that. See | |
1869 | * http://support.amd.com/us/Processor_TechDocs/41322.pdf, | |
1870 | * Erratum 383 on page 93. Intel should be safe but is | |
1871 | * also warns that it's only safe if the permission | |
1872 | * and cache attributes of the two entries loaded in | |
1873 | * the two TLB is identical (which should be the case | |
1874 | * here). But it is generally safer to never allow | |
1875 | * small and huge TLB entries for the same virtual | |
1876 | * address to be loaded simultaneously. So instead of | |
1877 | * doing "pmd_populate(); flush_tlb_range();" we first | |
1878 | * mark the current pmd notpresent (atomically because | |
1879 | * here the pmd_trans_huge and pmd_trans_splitting | |
1880 | * must remain set at all times on the pmd until the | |
1881 | * split is complete for this pmd), then we flush the | |
1882 | * SMP TLB and finally we write the non-huge version | |
1883 | * of the pmd entry with pmd_populate. | |
1884 | */ | |
46dcde73 | 1885 | pmdp_invalidate(vma, address, pmd); |
71e3aac0 AA |
1886 | pmd_populate(mm, pmd, pgtable); |
1887 | ret = 1; | |
117b0791 | 1888 | spin_unlock(ptl); |
71e3aac0 | 1889 | } |
71e3aac0 AA |
1890 | |
1891 | return ret; | |
1892 | } | |
1893 | ||
5a505085 | 1894 | /* must be called with anon_vma->root->rwsem held */ |
71e3aac0 | 1895 | static void __split_huge_page(struct page *page, |
5bc7b8ac SL |
1896 | struct anon_vma *anon_vma, |
1897 | struct list_head *list) | |
71e3aac0 AA |
1898 | { |
1899 | int mapcount, mapcount2; | |
bf181b9f | 1900 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
71e3aac0 AA |
1901 | struct anon_vma_chain *avc; |
1902 | ||
1903 | BUG_ON(!PageHead(page)); | |
1904 | BUG_ON(PageTail(page)); | |
1905 | ||
1906 | mapcount = 0; | |
bf181b9f | 1907 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { |
71e3aac0 AA |
1908 | struct vm_area_struct *vma = avc->vma; |
1909 | unsigned long addr = vma_address(page, vma); | |
1910 | BUG_ON(is_vma_temporary_stack(vma)); | |
71e3aac0 AA |
1911 | mapcount += __split_huge_page_splitting(page, vma, addr); |
1912 | } | |
05759d38 AA |
1913 | /* |
1914 | * It is critical that new vmas are added to the tail of the | |
1915 | * anon_vma list. This guarantes that if copy_huge_pmd() runs | |
1916 | * and establishes a child pmd before | |
1917 | * __split_huge_page_splitting() freezes the parent pmd (so if | |
1918 | * we fail to prevent copy_huge_pmd() from running until the | |
1919 | * whole __split_huge_page() is complete), we will still see | |
1920 | * the newly established pmd of the child later during the | |
1921 | * walk, to be able to set it as pmd_trans_splitting too. | |
1922 | */ | |
ff9e43eb | 1923 | if (mapcount != page_mapcount(page)) { |
ae3a8c1c AM |
1924 | pr_err("mapcount %d page_mapcount %d\n", |
1925 | mapcount, page_mapcount(page)); | |
ff9e43eb KS |
1926 | BUG(); |
1927 | } | |
71e3aac0 | 1928 | |
5bc7b8ac | 1929 | __split_huge_page_refcount(page, list); |
71e3aac0 AA |
1930 | |
1931 | mapcount2 = 0; | |
bf181b9f | 1932 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { |
71e3aac0 AA |
1933 | struct vm_area_struct *vma = avc->vma; |
1934 | unsigned long addr = vma_address(page, vma); | |
1935 | BUG_ON(is_vma_temporary_stack(vma)); | |
71e3aac0 AA |
1936 | mapcount2 += __split_huge_page_map(page, vma, addr); |
1937 | } | |
ff9e43eb | 1938 | if (mapcount != mapcount2) { |
ae3a8c1c AM |
1939 | pr_err("mapcount %d mapcount2 %d page_mapcount %d\n", |
1940 | mapcount, mapcount2, page_mapcount(page)); | |
ff9e43eb KS |
1941 | BUG(); |
1942 | } | |
71e3aac0 AA |
1943 | } |
1944 | ||
5bc7b8ac SL |
1945 | /* |
1946 | * Split a hugepage into normal pages. This doesn't change the position of head | |
1947 | * page. If @list is null, tail pages will be added to LRU list, otherwise, to | |
1948 | * @list. Both head page and tail pages will inherit mapping, flags, and so on | |
1949 | * from the hugepage. | |
1950 | * Return 0 if the hugepage is split successfully otherwise return 1. | |
1951 | */ | |
1952 | int split_huge_page_to_list(struct page *page, struct list_head *list) | |
71e3aac0 AA |
1953 | { |
1954 | struct anon_vma *anon_vma; | |
1955 | int ret = 1; | |
1956 | ||
5918d10a | 1957 | BUG_ON(is_huge_zero_page(page)); |
71e3aac0 | 1958 | BUG_ON(!PageAnon(page)); |
062f1af2 MG |
1959 | |
1960 | /* | |
1961 | * The caller does not necessarily hold an mmap_sem that would prevent | |
1962 | * the anon_vma disappearing so we first we take a reference to it | |
1963 | * and then lock the anon_vma for write. This is similar to | |
1964 | * page_lock_anon_vma_read except the write lock is taken to serialise | |
1965 | * against parallel split or collapse operations. | |
1966 | */ | |
1967 | anon_vma = page_get_anon_vma(page); | |
71e3aac0 AA |
1968 | if (!anon_vma) |
1969 | goto out; | |
062f1af2 MG |
1970 | anon_vma_lock_write(anon_vma); |
1971 | ||
71e3aac0 AA |
1972 | ret = 0; |
1973 | if (!PageCompound(page)) | |
1974 | goto out_unlock; | |
1975 | ||
1976 | BUG_ON(!PageSwapBacked(page)); | |
5bc7b8ac | 1977 | __split_huge_page(page, anon_vma, list); |
81ab4201 | 1978 | count_vm_event(THP_SPLIT); |
71e3aac0 AA |
1979 | |
1980 | BUG_ON(PageCompound(page)); | |
1981 | out_unlock: | |
08b52706 | 1982 | anon_vma_unlock_write(anon_vma); |
062f1af2 | 1983 | put_anon_vma(anon_vma); |
71e3aac0 AA |
1984 | out: |
1985 | return ret; | |
1986 | } | |
1987 | ||
9050d7eb | 1988 | #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE) |
78f11a25 | 1989 | |
60ab3244 AA |
1990 | int hugepage_madvise(struct vm_area_struct *vma, |
1991 | unsigned long *vm_flags, int advice) | |
0af4e98b | 1992 | { |
a664b2d8 AA |
1993 | switch (advice) { |
1994 | case MADV_HUGEPAGE: | |
1e1836e8 AT |
1995 | #ifdef CONFIG_S390 |
1996 | /* | |
1997 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
1998 | * can't handle this properly after s390_enable_sie, so we simply | |
1999 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
2000 | */ | |
2001 | if (mm_has_pgste(vma->vm_mm)) | |
2002 | return 0; | |
2003 | #endif | |
a664b2d8 AA |
2004 | /* |
2005 | * Be somewhat over-protective like KSM for now! | |
2006 | */ | |
78f11a25 | 2007 | if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP)) |
a664b2d8 AA |
2008 | return -EINVAL; |
2009 | *vm_flags &= ~VM_NOHUGEPAGE; | |
2010 | *vm_flags |= VM_HUGEPAGE; | |
60ab3244 AA |
2011 | /* |
2012 | * If the vma become good for khugepaged to scan, | |
2013 | * register it here without waiting a page fault that | |
2014 | * may not happen any time soon. | |
2015 | */ | |
6d50e60c | 2016 | if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags))) |
60ab3244 | 2017 | return -ENOMEM; |
a664b2d8 AA |
2018 | break; |
2019 | case MADV_NOHUGEPAGE: | |
2020 | /* | |
2021 | * Be somewhat over-protective like KSM for now! | |
2022 | */ | |
78f11a25 | 2023 | if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP)) |
a664b2d8 AA |
2024 | return -EINVAL; |
2025 | *vm_flags &= ~VM_HUGEPAGE; | |
2026 | *vm_flags |= VM_NOHUGEPAGE; | |
60ab3244 AA |
2027 | /* |
2028 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
2029 | * this vma even if we leave the mm registered in khugepaged if | |
2030 | * it got registered before VM_NOHUGEPAGE was set. | |
2031 | */ | |
a664b2d8 AA |
2032 | break; |
2033 | } | |
0af4e98b AA |
2034 | |
2035 | return 0; | |
2036 | } | |
2037 | ||
ba76149f AA |
2038 | static int __init khugepaged_slab_init(void) |
2039 | { | |
2040 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
2041 | sizeof(struct mm_slot), | |
2042 | __alignof__(struct mm_slot), 0, NULL); | |
2043 | if (!mm_slot_cache) | |
2044 | return -ENOMEM; | |
2045 | ||
2046 | return 0; | |
2047 | } | |
2048 | ||
65ebb64f KS |
2049 | static void __init khugepaged_slab_exit(void) |
2050 | { | |
2051 | kmem_cache_destroy(mm_slot_cache); | |
2052 | } | |
2053 | ||
ba76149f AA |
2054 | static inline struct mm_slot *alloc_mm_slot(void) |
2055 | { | |
2056 | if (!mm_slot_cache) /* initialization failed */ | |
2057 | return NULL; | |
2058 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
2059 | } | |
2060 | ||
2061 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
2062 | { | |
2063 | kmem_cache_free(mm_slot_cache, mm_slot); | |
2064 | } | |
2065 | ||
ba76149f AA |
2066 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) |
2067 | { | |
2068 | struct mm_slot *mm_slot; | |
ba76149f | 2069 | |
b67bfe0d | 2070 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) |
ba76149f AA |
2071 | if (mm == mm_slot->mm) |
2072 | return mm_slot; | |
43b5fbbd | 2073 | |
ba76149f AA |
2074 | return NULL; |
2075 | } | |
2076 | ||
2077 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
2078 | struct mm_slot *mm_slot) | |
2079 | { | |
ba76149f | 2080 | mm_slot->mm = mm; |
43b5fbbd | 2081 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); |
ba76149f AA |
2082 | } |
2083 | ||
2084 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
2085 | { | |
2086 | return atomic_read(&mm->mm_users) == 0; | |
2087 | } | |
2088 | ||
2089 | int __khugepaged_enter(struct mm_struct *mm) | |
2090 | { | |
2091 | struct mm_slot *mm_slot; | |
2092 | int wakeup; | |
2093 | ||
2094 | mm_slot = alloc_mm_slot(); | |
2095 | if (!mm_slot) | |
2096 | return -ENOMEM; | |
2097 | ||
2098 | /* __khugepaged_exit() must not run from under us */ | |
96dad67f | 2099 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); |
ba76149f AA |
2100 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { |
2101 | free_mm_slot(mm_slot); | |
2102 | return 0; | |
2103 | } | |
2104 | ||
2105 | spin_lock(&khugepaged_mm_lock); | |
2106 | insert_to_mm_slots_hash(mm, mm_slot); | |
2107 | /* | |
2108 | * Insert just behind the scanning cursor, to let the area settle | |
2109 | * down a little. | |
2110 | */ | |
2111 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
2112 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
2113 | spin_unlock(&khugepaged_mm_lock); | |
2114 | ||
2115 | atomic_inc(&mm->mm_count); | |
2116 | if (wakeup) | |
2117 | wake_up_interruptible(&khugepaged_wait); | |
2118 | ||
2119 | return 0; | |
2120 | } | |
2121 | ||
6d50e60c DR |
2122 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, |
2123 | unsigned long vm_flags) | |
ba76149f AA |
2124 | { |
2125 | unsigned long hstart, hend; | |
2126 | if (!vma->anon_vma) | |
2127 | /* | |
2128 | * Not yet faulted in so we will register later in the | |
2129 | * page fault if needed. | |
2130 | */ | |
2131 | return 0; | |
78f11a25 | 2132 | if (vma->vm_ops) |
ba76149f AA |
2133 | /* khugepaged not yet working on file or special mappings */ |
2134 | return 0; | |
6d50e60c | 2135 | VM_BUG_ON_VMA(vm_flags & VM_NO_THP, vma); |
ba76149f AA |
2136 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2137 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2138 | if (hstart < hend) | |
6d50e60c | 2139 | return khugepaged_enter(vma, vm_flags); |
ba76149f AA |
2140 | return 0; |
2141 | } | |
2142 | ||
2143 | void __khugepaged_exit(struct mm_struct *mm) | |
2144 | { | |
2145 | struct mm_slot *mm_slot; | |
2146 | int free = 0; | |
2147 | ||
2148 | spin_lock(&khugepaged_mm_lock); | |
2149 | mm_slot = get_mm_slot(mm); | |
2150 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
43b5fbbd | 2151 | hash_del(&mm_slot->hash); |
ba76149f AA |
2152 | list_del(&mm_slot->mm_node); |
2153 | free = 1; | |
2154 | } | |
d788e80a | 2155 | spin_unlock(&khugepaged_mm_lock); |
ba76149f AA |
2156 | |
2157 | if (free) { | |
ba76149f AA |
2158 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); |
2159 | free_mm_slot(mm_slot); | |
2160 | mmdrop(mm); | |
2161 | } else if (mm_slot) { | |
ba76149f AA |
2162 | /* |
2163 | * This is required to serialize against | |
2164 | * khugepaged_test_exit() (which is guaranteed to run | |
2165 | * under mmap sem read mode). Stop here (after we | |
2166 | * return all pagetables will be destroyed) until | |
2167 | * khugepaged has finished working on the pagetables | |
2168 | * under the mmap_sem. | |
2169 | */ | |
2170 | down_write(&mm->mmap_sem); | |
2171 | up_write(&mm->mmap_sem); | |
d788e80a | 2172 | } |
ba76149f AA |
2173 | } |
2174 | ||
2175 | static void release_pte_page(struct page *page) | |
2176 | { | |
2177 | /* 0 stands for page_is_file_cache(page) == false */ | |
2178 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
2179 | unlock_page(page); | |
2180 | putback_lru_page(page); | |
2181 | } | |
2182 | ||
2183 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
2184 | { | |
2185 | while (--_pte >= pte) { | |
2186 | pte_t pteval = *_pte; | |
ca0984ca | 2187 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) |
ba76149f AA |
2188 | release_pte_page(pte_page(pteval)); |
2189 | } | |
2190 | } | |
2191 | ||
ba76149f AA |
2192 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, |
2193 | unsigned long address, | |
2194 | pte_t *pte) | |
2195 | { | |
2196 | struct page *page; | |
2197 | pte_t *_pte; | |
ca0984ca | 2198 | int none_or_zero = 0; |
10359213 | 2199 | bool referenced = false, writable = false; |
ba76149f AA |
2200 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; |
2201 | _pte++, address += PAGE_SIZE) { | |
2202 | pte_t pteval = *_pte; | |
ca0984ca | 2203 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
c1294d05 AA |
2204 | if (!userfaultfd_armed(vma) && |
2205 | ++none_or_zero <= khugepaged_max_ptes_none) | |
ba76149f | 2206 | continue; |
344aa35c | 2207 | else |
ba76149f | 2208 | goto out; |
ba76149f | 2209 | } |
10359213 | 2210 | if (!pte_present(pteval)) |
ba76149f | 2211 | goto out; |
ba76149f | 2212 | page = vm_normal_page(vma, address, pteval); |
344aa35c | 2213 | if (unlikely(!page)) |
ba76149f | 2214 | goto out; |
344aa35c | 2215 | |
309381fe SL |
2216 | VM_BUG_ON_PAGE(PageCompound(page), page); |
2217 | VM_BUG_ON_PAGE(!PageAnon(page), page); | |
2218 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
ba76149f | 2219 | |
ba76149f AA |
2220 | /* |
2221 | * We can do it before isolate_lru_page because the | |
2222 | * page can't be freed from under us. NOTE: PG_lock | |
2223 | * is needed to serialize against split_huge_page | |
2224 | * when invoked from the VM. | |
2225 | */ | |
344aa35c | 2226 | if (!trylock_page(page)) |
ba76149f | 2227 | goto out; |
10359213 EA |
2228 | |
2229 | /* | |
2230 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2231 | * The page must only be referenced by the scanned process | |
2232 | * and page swap cache. | |
2233 | */ | |
2234 | if (page_count(page) != 1 + !!PageSwapCache(page)) { | |
2235 | unlock_page(page); | |
2236 | goto out; | |
2237 | } | |
2238 | if (pte_write(pteval)) { | |
2239 | writable = true; | |
2240 | } else { | |
2241 | if (PageSwapCache(page) && !reuse_swap_page(page)) { | |
2242 | unlock_page(page); | |
2243 | goto out; | |
2244 | } | |
2245 | /* | |
2246 | * Page is not in the swap cache. It can be collapsed | |
2247 | * into a THP. | |
2248 | */ | |
2249 | } | |
2250 | ||
ba76149f AA |
2251 | /* |
2252 | * Isolate the page to avoid collapsing an hugepage | |
2253 | * currently in use by the VM. | |
2254 | */ | |
2255 | if (isolate_lru_page(page)) { | |
2256 | unlock_page(page); | |
ba76149f AA |
2257 | goto out; |
2258 | } | |
2259 | /* 0 stands for page_is_file_cache(page) == false */ | |
2260 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
309381fe SL |
2261 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
2262 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
ba76149f AA |
2263 | |
2264 | /* If there is no mapped pte young don't collapse the page */ | |
8ee53820 AA |
2265 | if (pte_young(pteval) || PageReferenced(page) || |
2266 | mmu_notifier_test_young(vma->vm_mm, address)) | |
10359213 | 2267 | referenced = true; |
ba76149f | 2268 | } |
10359213 | 2269 | if (likely(referenced && writable)) |
344aa35c | 2270 | return 1; |
ba76149f | 2271 | out: |
344aa35c BL |
2272 | release_pte_pages(pte, _pte); |
2273 | return 0; | |
ba76149f AA |
2274 | } |
2275 | ||
2276 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
2277 | struct vm_area_struct *vma, | |
2278 | unsigned long address, | |
2279 | spinlock_t *ptl) | |
2280 | { | |
2281 | pte_t *_pte; | |
2282 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { | |
2283 | pte_t pteval = *_pte; | |
2284 | struct page *src_page; | |
2285 | ||
ca0984ca | 2286 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
ba76149f AA |
2287 | clear_user_highpage(page, address); |
2288 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
ca0984ca EA |
2289 | if (is_zero_pfn(pte_pfn(pteval))) { |
2290 | /* | |
2291 | * ptl mostly unnecessary. | |
2292 | */ | |
2293 | spin_lock(ptl); | |
2294 | /* | |
2295 | * paravirt calls inside pte_clear here are | |
2296 | * superfluous. | |
2297 | */ | |
2298 | pte_clear(vma->vm_mm, address, _pte); | |
2299 | spin_unlock(ptl); | |
2300 | } | |
ba76149f AA |
2301 | } else { |
2302 | src_page = pte_page(pteval); | |
2303 | copy_user_highpage(page, src_page, address, vma); | |
309381fe | 2304 | VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page); |
ba76149f AA |
2305 | release_pte_page(src_page); |
2306 | /* | |
2307 | * ptl mostly unnecessary, but preempt has to | |
2308 | * be disabled to update the per-cpu stats | |
2309 | * inside page_remove_rmap(). | |
2310 | */ | |
2311 | spin_lock(ptl); | |
2312 | /* | |
2313 | * paravirt calls inside pte_clear here are | |
2314 | * superfluous. | |
2315 | */ | |
2316 | pte_clear(vma->vm_mm, address, _pte); | |
2317 | page_remove_rmap(src_page); | |
2318 | spin_unlock(ptl); | |
2319 | free_page_and_swap_cache(src_page); | |
2320 | } | |
2321 | ||
2322 | address += PAGE_SIZE; | |
2323 | page++; | |
2324 | } | |
2325 | } | |
2326 | ||
26234f36 | 2327 | static void khugepaged_alloc_sleep(void) |
ba76149f | 2328 | { |
bde43c6c PM |
2329 | DEFINE_WAIT(wait); |
2330 | ||
2331 | add_wait_queue(&khugepaged_wait, &wait); | |
2332 | freezable_schedule_timeout_interruptible( | |
2333 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
2334 | remove_wait_queue(&khugepaged_wait, &wait); | |
26234f36 | 2335 | } |
ba76149f | 2336 | |
9f1b868a BL |
2337 | static int khugepaged_node_load[MAX_NUMNODES]; |
2338 | ||
14a4e214 DR |
2339 | static bool khugepaged_scan_abort(int nid) |
2340 | { | |
2341 | int i; | |
2342 | ||
2343 | /* | |
2344 | * If zone_reclaim_mode is disabled, then no extra effort is made to | |
2345 | * allocate memory locally. | |
2346 | */ | |
2347 | if (!zone_reclaim_mode) | |
2348 | return false; | |
2349 | ||
2350 | /* If there is a count for this node already, it must be acceptable */ | |
2351 | if (khugepaged_node_load[nid]) | |
2352 | return false; | |
2353 | ||
2354 | for (i = 0; i < MAX_NUMNODES; i++) { | |
2355 | if (!khugepaged_node_load[i]) | |
2356 | continue; | |
2357 | if (node_distance(nid, i) > RECLAIM_DISTANCE) | |
2358 | return true; | |
2359 | } | |
2360 | return false; | |
2361 | } | |
2362 | ||
26234f36 | 2363 | #ifdef CONFIG_NUMA |
9f1b868a BL |
2364 | static int khugepaged_find_target_node(void) |
2365 | { | |
2366 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
2367 | int nid, target_node = 0, max_value = 0; | |
2368 | ||
2369 | /* find first node with max normal pages hit */ | |
2370 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
2371 | if (khugepaged_node_load[nid] > max_value) { | |
2372 | max_value = khugepaged_node_load[nid]; | |
2373 | target_node = nid; | |
2374 | } | |
2375 | ||
2376 | /* do some balance if several nodes have the same hit record */ | |
2377 | if (target_node <= last_khugepaged_target_node) | |
2378 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
2379 | nid++) | |
2380 | if (max_value == khugepaged_node_load[nid]) { | |
2381 | target_node = nid; | |
2382 | break; | |
2383 | } | |
2384 | ||
2385 | last_khugepaged_target_node = target_node; | |
2386 | return target_node; | |
2387 | } | |
2388 | ||
26234f36 XG |
2389 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) |
2390 | { | |
2391 | if (IS_ERR(*hpage)) { | |
2392 | if (!*wait) | |
2393 | return false; | |
2394 | ||
2395 | *wait = false; | |
e3b4126c | 2396 | *hpage = NULL; |
26234f36 XG |
2397 | khugepaged_alloc_sleep(); |
2398 | } else if (*hpage) { | |
2399 | put_page(*hpage); | |
2400 | *hpage = NULL; | |
2401 | } | |
2402 | ||
2403 | return true; | |
2404 | } | |
2405 | ||
3b363692 MH |
2406 | static struct page * |
2407 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
26234f36 XG |
2408 | struct vm_area_struct *vma, unsigned long address, |
2409 | int node) | |
2410 | { | |
309381fe | 2411 | VM_BUG_ON_PAGE(*hpage, *hpage); |
8b164568 | 2412 | |
ce83d217 | 2413 | /* |
8b164568 VB |
2414 | * Before allocating the hugepage, release the mmap_sem read lock. |
2415 | * The allocation can take potentially a long time if it involves | |
2416 | * sync compaction, and we do not need to hold the mmap_sem during | |
2417 | * that. We will recheck the vma after taking it again in write mode. | |
ce83d217 | 2418 | */ |
8b164568 VB |
2419 | up_read(&mm->mmap_sem); |
2420 | ||
96db800f | 2421 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); |
26234f36 | 2422 | if (unlikely(!*hpage)) { |
81ab4201 | 2423 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); |
ce83d217 | 2424 | *hpage = ERR_PTR(-ENOMEM); |
26234f36 | 2425 | return NULL; |
ce83d217 | 2426 | } |
26234f36 | 2427 | |
65b3c07b | 2428 | count_vm_event(THP_COLLAPSE_ALLOC); |
26234f36 XG |
2429 | return *hpage; |
2430 | } | |
2431 | #else | |
9f1b868a BL |
2432 | static int khugepaged_find_target_node(void) |
2433 | { | |
2434 | return 0; | |
2435 | } | |
2436 | ||
10dc4155 BL |
2437 | static inline struct page *alloc_hugepage(int defrag) |
2438 | { | |
2439 | return alloc_pages(alloc_hugepage_gfpmask(defrag, 0), | |
2440 | HPAGE_PMD_ORDER); | |
2441 | } | |
2442 | ||
26234f36 XG |
2443 | static struct page *khugepaged_alloc_hugepage(bool *wait) |
2444 | { | |
2445 | struct page *hpage; | |
2446 | ||
2447 | do { | |
2448 | hpage = alloc_hugepage(khugepaged_defrag()); | |
2449 | if (!hpage) { | |
2450 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
2451 | if (!*wait) | |
2452 | return NULL; | |
2453 | ||
2454 | *wait = false; | |
2455 | khugepaged_alloc_sleep(); | |
2456 | } else | |
2457 | count_vm_event(THP_COLLAPSE_ALLOC); | |
2458 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
2459 | ||
2460 | return hpage; | |
2461 | } | |
2462 | ||
2463 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
2464 | { | |
2465 | if (!*hpage) | |
2466 | *hpage = khugepaged_alloc_hugepage(wait); | |
2467 | ||
2468 | if (unlikely(!*hpage)) | |
2469 | return false; | |
2470 | ||
2471 | return true; | |
2472 | } | |
2473 | ||
3b363692 MH |
2474 | static struct page * |
2475 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
26234f36 XG |
2476 | struct vm_area_struct *vma, unsigned long address, |
2477 | int node) | |
2478 | { | |
2479 | up_read(&mm->mmap_sem); | |
2480 | VM_BUG_ON(!*hpage); | |
3b363692 | 2481 | |
26234f36 XG |
2482 | return *hpage; |
2483 | } | |
692e0b35 AA |
2484 | #endif |
2485 | ||
fa475e51 BL |
2486 | static bool hugepage_vma_check(struct vm_area_struct *vma) |
2487 | { | |
2488 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || | |
2489 | (vma->vm_flags & VM_NOHUGEPAGE)) | |
2490 | return false; | |
2491 | ||
2492 | if (!vma->anon_vma || vma->vm_ops) | |
2493 | return false; | |
2494 | if (is_vma_temporary_stack(vma)) | |
2495 | return false; | |
81d1b09c | 2496 | VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma); |
fa475e51 BL |
2497 | return true; |
2498 | } | |
2499 | ||
26234f36 XG |
2500 | static void collapse_huge_page(struct mm_struct *mm, |
2501 | unsigned long address, | |
2502 | struct page **hpage, | |
2503 | struct vm_area_struct *vma, | |
2504 | int node) | |
2505 | { | |
26234f36 XG |
2506 | pmd_t *pmd, _pmd; |
2507 | pte_t *pte; | |
2508 | pgtable_t pgtable; | |
2509 | struct page *new_page; | |
c4088ebd | 2510 | spinlock_t *pmd_ptl, *pte_ptl; |
26234f36 XG |
2511 | int isolated; |
2512 | unsigned long hstart, hend; | |
00501b53 | 2513 | struct mem_cgroup *memcg; |
2ec74c3e SG |
2514 | unsigned long mmun_start; /* For mmu_notifiers */ |
2515 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 2516 | gfp_t gfp; |
26234f36 XG |
2517 | |
2518 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2519 | ||
3b363692 MH |
2520 | /* Only allocate from the target node */ |
2521 | gfp = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) | | |
2522 | __GFP_THISNODE; | |
2523 | ||
26234f36 | 2524 | /* release the mmap_sem read lock. */ |
3b363692 | 2525 | new_page = khugepaged_alloc_page(hpage, gfp, mm, vma, address, node); |
26234f36 XG |
2526 | if (!new_page) |
2527 | return; | |
2528 | ||
00501b53 | 2529 | if (unlikely(mem_cgroup_try_charge(new_page, mm, |
3b363692 | 2530 | gfp, &memcg))) |
ce83d217 | 2531 | return; |
ba76149f AA |
2532 | |
2533 | /* | |
2534 | * Prevent all access to pagetables with the exception of | |
2535 | * gup_fast later hanlded by the ptep_clear_flush and the VM | |
2536 | * handled by the anon_vma lock + PG_lock. | |
2537 | */ | |
2538 | down_write(&mm->mmap_sem); | |
2539 | if (unlikely(khugepaged_test_exit(mm))) | |
2540 | goto out; | |
2541 | ||
2542 | vma = find_vma(mm, address); | |
a8f531eb L |
2543 | if (!vma) |
2544 | goto out; | |
ba76149f AA |
2545 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2546 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2547 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
2548 | goto out; | |
fa475e51 | 2549 | if (!hugepage_vma_check(vma)) |
a7d6e4ec | 2550 | goto out; |
6219049a BL |
2551 | pmd = mm_find_pmd(mm, address); |
2552 | if (!pmd) | |
ba76149f | 2553 | goto out; |
ba76149f | 2554 | |
4fc3f1d6 | 2555 | anon_vma_lock_write(vma->anon_vma); |
ba76149f AA |
2556 | |
2557 | pte = pte_offset_map(pmd, address); | |
c4088ebd | 2558 | pte_ptl = pte_lockptr(mm, pmd); |
ba76149f | 2559 | |
2ec74c3e SG |
2560 | mmun_start = address; |
2561 | mmun_end = address + HPAGE_PMD_SIZE; | |
2562 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
c4088ebd | 2563 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
ba76149f AA |
2564 | /* |
2565 | * After this gup_fast can't run anymore. This also removes | |
2566 | * any huge TLB entry from the CPU so we won't allow | |
2567 | * huge and small TLB entries for the same virtual address | |
2568 | * to avoid the risk of CPU bugs in that area. | |
2569 | */ | |
15a25b2e | 2570 | _pmd = pmdp_collapse_flush(vma, address, pmd); |
c4088ebd | 2571 | spin_unlock(pmd_ptl); |
2ec74c3e | 2572 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
ba76149f | 2573 | |
c4088ebd | 2574 | spin_lock(pte_ptl); |
ba76149f | 2575 | isolated = __collapse_huge_page_isolate(vma, address, pte); |
c4088ebd | 2576 | spin_unlock(pte_ptl); |
ba76149f AA |
2577 | |
2578 | if (unlikely(!isolated)) { | |
453c7192 | 2579 | pte_unmap(pte); |
c4088ebd | 2580 | spin_lock(pmd_ptl); |
ba76149f | 2581 | BUG_ON(!pmd_none(*pmd)); |
7c342512 AK |
2582 | /* |
2583 | * We can only use set_pmd_at when establishing | |
2584 | * hugepmds and never for establishing regular pmds that | |
2585 | * points to regular pagetables. Use pmd_populate for that | |
2586 | */ | |
2587 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
c4088ebd | 2588 | spin_unlock(pmd_ptl); |
08b52706 | 2589 | anon_vma_unlock_write(vma->anon_vma); |
ce83d217 | 2590 | goto out; |
ba76149f AA |
2591 | } |
2592 | ||
2593 | /* | |
2594 | * All pages are isolated and locked so anon_vma rmap | |
2595 | * can't run anymore. | |
2596 | */ | |
08b52706 | 2597 | anon_vma_unlock_write(vma->anon_vma); |
ba76149f | 2598 | |
c4088ebd | 2599 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); |
453c7192 | 2600 | pte_unmap(pte); |
ba76149f AA |
2601 | __SetPageUptodate(new_page); |
2602 | pgtable = pmd_pgtable(_pmd); | |
ba76149f | 2603 | |
3122359a KS |
2604 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); |
2605 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); | |
ba76149f AA |
2606 | |
2607 | /* | |
2608 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
2609 | * this is needed to avoid the copy_huge_page writes to become | |
2610 | * visible after the set_pmd_at() write. | |
2611 | */ | |
2612 | smp_wmb(); | |
2613 | ||
c4088ebd | 2614 | spin_lock(pmd_ptl); |
ba76149f AA |
2615 | BUG_ON(!pmd_none(*pmd)); |
2616 | page_add_new_anon_rmap(new_page, vma, address); | |
00501b53 JW |
2617 | mem_cgroup_commit_charge(new_page, memcg, false); |
2618 | lru_cache_add_active_or_unevictable(new_page, vma); | |
fce144b4 | 2619 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
ba76149f | 2620 | set_pmd_at(mm, address, pmd, _pmd); |
b113da65 | 2621 | update_mmu_cache_pmd(vma, address, pmd); |
c4088ebd | 2622 | spin_unlock(pmd_ptl); |
ba76149f AA |
2623 | |
2624 | *hpage = NULL; | |
420256ef | 2625 | |
ba76149f | 2626 | khugepaged_pages_collapsed++; |
ce83d217 | 2627 | out_up_write: |
ba76149f | 2628 | up_write(&mm->mmap_sem); |
0bbbc0b3 AA |
2629 | return; |
2630 | ||
ce83d217 | 2631 | out: |
00501b53 | 2632 | mem_cgroup_cancel_charge(new_page, memcg); |
ce83d217 | 2633 | goto out_up_write; |
ba76149f AA |
2634 | } |
2635 | ||
2636 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
2637 | struct vm_area_struct *vma, | |
2638 | unsigned long address, | |
2639 | struct page **hpage) | |
2640 | { | |
ba76149f AA |
2641 | pmd_t *pmd; |
2642 | pte_t *pte, *_pte; | |
ca0984ca | 2643 | int ret = 0, none_or_zero = 0; |
ba76149f AA |
2644 | struct page *page; |
2645 | unsigned long _address; | |
2646 | spinlock_t *ptl; | |
00ef2d2f | 2647 | int node = NUMA_NO_NODE; |
10359213 | 2648 | bool writable = false, referenced = false; |
ba76149f AA |
2649 | |
2650 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2651 | ||
6219049a BL |
2652 | pmd = mm_find_pmd(mm, address); |
2653 | if (!pmd) | |
ba76149f | 2654 | goto out; |
ba76149f | 2655 | |
9f1b868a | 2656 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); |
ba76149f AA |
2657 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
2658 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
2659 | _pte++, _address += PAGE_SIZE) { | |
2660 | pte_t pteval = *_pte; | |
ca0984ca | 2661 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
c1294d05 AA |
2662 | if (!userfaultfd_armed(vma) && |
2663 | ++none_or_zero <= khugepaged_max_ptes_none) | |
ba76149f AA |
2664 | continue; |
2665 | else | |
2666 | goto out_unmap; | |
2667 | } | |
10359213 | 2668 | if (!pte_present(pteval)) |
ba76149f | 2669 | goto out_unmap; |
10359213 EA |
2670 | if (pte_write(pteval)) |
2671 | writable = true; | |
2672 | ||
ba76149f AA |
2673 | page = vm_normal_page(vma, _address, pteval); |
2674 | if (unlikely(!page)) | |
2675 | goto out_unmap; | |
5c4b4be3 | 2676 | /* |
9f1b868a BL |
2677 | * Record which node the original page is from and save this |
2678 | * information to khugepaged_node_load[]. | |
2679 | * Khupaged will allocate hugepage from the node has the max | |
2680 | * hit record. | |
5c4b4be3 | 2681 | */ |
9f1b868a | 2682 | node = page_to_nid(page); |
14a4e214 DR |
2683 | if (khugepaged_scan_abort(node)) |
2684 | goto out_unmap; | |
9f1b868a | 2685 | khugepaged_node_load[node]++; |
309381fe | 2686 | VM_BUG_ON_PAGE(PageCompound(page), page); |
ba76149f AA |
2687 | if (!PageLRU(page) || PageLocked(page) || !PageAnon(page)) |
2688 | goto out_unmap; | |
10359213 EA |
2689 | /* |
2690 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2691 | * The page must only be referenced by the scanned process | |
2692 | * and page swap cache. | |
2693 | */ | |
2694 | if (page_count(page) != 1 + !!PageSwapCache(page)) | |
ba76149f | 2695 | goto out_unmap; |
8ee53820 AA |
2696 | if (pte_young(pteval) || PageReferenced(page) || |
2697 | mmu_notifier_test_young(vma->vm_mm, address)) | |
10359213 | 2698 | referenced = true; |
ba76149f | 2699 | } |
10359213 | 2700 | if (referenced && writable) |
ba76149f AA |
2701 | ret = 1; |
2702 | out_unmap: | |
2703 | pte_unmap_unlock(pte, ptl); | |
9f1b868a BL |
2704 | if (ret) { |
2705 | node = khugepaged_find_target_node(); | |
ce83d217 | 2706 | /* collapse_huge_page will return with the mmap_sem released */ |
5c4b4be3 | 2707 | collapse_huge_page(mm, address, hpage, vma, node); |
9f1b868a | 2708 | } |
ba76149f AA |
2709 | out: |
2710 | return ret; | |
2711 | } | |
2712 | ||
2713 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
2714 | { | |
2715 | struct mm_struct *mm = mm_slot->mm; | |
2716 | ||
b9980cdc | 2717 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2718 | |
2719 | if (khugepaged_test_exit(mm)) { | |
2720 | /* free mm_slot */ | |
43b5fbbd | 2721 | hash_del(&mm_slot->hash); |
ba76149f AA |
2722 | list_del(&mm_slot->mm_node); |
2723 | ||
2724 | /* | |
2725 | * Not strictly needed because the mm exited already. | |
2726 | * | |
2727 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
2728 | */ | |
2729 | ||
2730 | /* khugepaged_mm_lock actually not necessary for the below */ | |
2731 | free_mm_slot(mm_slot); | |
2732 | mmdrop(mm); | |
2733 | } | |
2734 | } | |
2735 | ||
2736 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
2737 | struct page **hpage) | |
2f1da642 HS |
2738 | __releases(&khugepaged_mm_lock) |
2739 | __acquires(&khugepaged_mm_lock) | |
ba76149f AA |
2740 | { |
2741 | struct mm_slot *mm_slot; | |
2742 | struct mm_struct *mm; | |
2743 | struct vm_area_struct *vma; | |
2744 | int progress = 0; | |
2745 | ||
2746 | VM_BUG_ON(!pages); | |
b9980cdc | 2747 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2748 | |
2749 | if (khugepaged_scan.mm_slot) | |
2750 | mm_slot = khugepaged_scan.mm_slot; | |
2751 | else { | |
2752 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2753 | struct mm_slot, mm_node); | |
2754 | khugepaged_scan.address = 0; | |
2755 | khugepaged_scan.mm_slot = mm_slot; | |
2756 | } | |
2757 | spin_unlock(&khugepaged_mm_lock); | |
2758 | ||
2759 | mm = mm_slot->mm; | |
2760 | down_read(&mm->mmap_sem); | |
2761 | if (unlikely(khugepaged_test_exit(mm))) | |
2762 | vma = NULL; | |
2763 | else | |
2764 | vma = find_vma(mm, khugepaged_scan.address); | |
2765 | ||
2766 | progress++; | |
2767 | for (; vma; vma = vma->vm_next) { | |
2768 | unsigned long hstart, hend; | |
2769 | ||
2770 | cond_resched(); | |
2771 | if (unlikely(khugepaged_test_exit(mm))) { | |
2772 | progress++; | |
2773 | break; | |
2774 | } | |
fa475e51 BL |
2775 | if (!hugepage_vma_check(vma)) { |
2776 | skip: | |
ba76149f AA |
2777 | progress++; |
2778 | continue; | |
2779 | } | |
ba76149f AA |
2780 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2781 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
a7d6e4ec AA |
2782 | if (hstart >= hend) |
2783 | goto skip; | |
2784 | if (khugepaged_scan.address > hend) | |
2785 | goto skip; | |
ba76149f AA |
2786 | if (khugepaged_scan.address < hstart) |
2787 | khugepaged_scan.address = hstart; | |
a7d6e4ec | 2788 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); |
ba76149f AA |
2789 | |
2790 | while (khugepaged_scan.address < hend) { | |
2791 | int ret; | |
2792 | cond_resched(); | |
2793 | if (unlikely(khugepaged_test_exit(mm))) | |
2794 | goto breakouterloop; | |
2795 | ||
2796 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2797 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2798 | hend); | |
2799 | ret = khugepaged_scan_pmd(mm, vma, | |
2800 | khugepaged_scan.address, | |
2801 | hpage); | |
2802 | /* move to next address */ | |
2803 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2804 | progress += HPAGE_PMD_NR; | |
2805 | if (ret) | |
2806 | /* we released mmap_sem so break loop */ | |
2807 | goto breakouterloop_mmap_sem; | |
2808 | if (progress >= pages) | |
2809 | goto breakouterloop; | |
2810 | } | |
2811 | } | |
2812 | breakouterloop: | |
2813 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2814 | breakouterloop_mmap_sem: | |
2815 | ||
2816 | spin_lock(&khugepaged_mm_lock); | |
a7d6e4ec | 2817 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); |
ba76149f AA |
2818 | /* |
2819 | * Release the current mm_slot if this mm is about to die, or | |
2820 | * if we scanned all vmas of this mm. | |
2821 | */ | |
2822 | if (khugepaged_test_exit(mm) || !vma) { | |
2823 | /* | |
2824 | * Make sure that if mm_users is reaching zero while | |
2825 | * khugepaged runs here, khugepaged_exit will find | |
2826 | * mm_slot not pointing to the exiting mm. | |
2827 | */ | |
2828 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2829 | khugepaged_scan.mm_slot = list_entry( | |
2830 | mm_slot->mm_node.next, | |
2831 | struct mm_slot, mm_node); | |
2832 | khugepaged_scan.address = 0; | |
2833 | } else { | |
2834 | khugepaged_scan.mm_slot = NULL; | |
2835 | khugepaged_full_scans++; | |
2836 | } | |
2837 | ||
2838 | collect_mm_slot(mm_slot); | |
2839 | } | |
2840 | ||
2841 | return progress; | |
2842 | } | |
2843 | ||
2844 | static int khugepaged_has_work(void) | |
2845 | { | |
2846 | return !list_empty(&khugepaged_scan.mm_head) && | |
2847 | khugepaged_enabled(); | |
2848 | } | |
2849 | ||
2850 | static int khugepaged_wait_event(void) | |
2851 | { | |
2852 | return !list_empty(&khugepaged_scan.mm_head) || | |
2017c0bf | 2853 | kthread_should_stop(); |
ba76149f AA |
2854 | } |
2855 | ||
d516904b | 2856 | static void khugepaged_do_scan(void) |
ba76149f | 2857 | { |
d516904b | 2858 | struct page *hpage = NULL; |
ba76149f AA |
2859 | unsigned int progress = 0, pass_through_head = 0; |
2860 | unsigned int pages = khugepaged_pages_to_scan; | |
d516904b | 2861 | bool wait = true; |
ba76149f AA |
2862 | |
2863 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2864 | ||
2865 | while (progress < pages) { | |
26234f36 | 2866 | if (!khugepaged_prealloc_page(&hpage, &wait)) |
d516904b | 2867 | break; |
26234f36 | 2868 | |
420256ef | 2869 | cond_resched(); |
ba76149f | 2870 | |
cd092411 | 2871 | if (unlikely(kthread_should_stop() || try_to_freeze())) |
878aee7d AA |
2872 | break; |
2873 | ||
ba76149f AA |
2874 | spin_lock(&khugepaged_mm_lock); |
2875 | if (!khugepaged_scan.mm_slot) | |
2876 | pass_through_head++; | |
2877 | if (khugepaged_has_work() && | |
2878 | pass_through_head < 2) | |
2879 | progress += khugepaged_scan_mm_slot(pages - progress, | |
d516904b | 2880 | &hpage); |
ba76149f AA |
2881 | else |
2882 | progress = pages; | |
2883 | spin_unlock(&khugepaged_mm_lock); | |
2884 | } | |
ba76149f | 2885 | |
d516904b XG |
2886 | if (!IS_ERR_OR_NULL(hpage)) |
2887 | put_page(hpage); | |
0bbbc0b3 AA |
2888 | } |
2889 | ||
2017c0bf XG |
2890 | static void khugepaged_wait_work(void) |
2891 | { | |
2017c0bf XG |
2892 | if (khugepaged_has_work()) { |
2893 | if (!khugepaged_scan_sleep_millisecs) | |
2894 | return; | |
2895 | ||
2896 | wait_event_freezable_timeout(khugepaged_wait, | |
2897 | kthread_should_stop(), | |
2898 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs)); | |
2899 | return; | |
2900 | } | |
2901 | ||
2902 | if (khugepaged_enabled()) | |
2903 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2904 | } | |
2905 | ||
ba76149f AA |
2906 | static int khugepaged(void *none) |
2907 | { | |
2908 | struct mm_slot *mm_slot; | |
2909 | ||
878aee7d | 2910 | set_freezable(); |
8698a745 | 2911 | set_user_nice(current, MAX_NICE); |
ba76149f | 2912 | |
b7231789 XG |
2913 | while (!kthread_should_stop()) { |
2914 | khugepaged_do_scan(); | |
2915 | khugepaged_wait_work(); | |
2916 | } | |
ba76149f AA |
2917 | |
2918 | spin_lock(&khugepaged_mm_lock); | |
2919 | mm_slot = khugepaged_scan.mm_slot; | |
2920 | khugepaged_scan.mm_slot = NULL; | |
2921 | if (mm_slot) | |
2922 | collect_mm_slot(mm_slot); | |
2923 | spin_unlock(&khugepaged_mm_lock); | |
ba76149f AA |
2924 | return 0; |
2925 | } | |
2926 | ||
c5a647d0 KS |
2927 | static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, |
2928 | unsigned long haddr, pmd_t *pmd) | |
2929 | { | |
2930 | struct mm_struct *mm = vma->vm_mm; | |
2931 | pgtable_t pgtable; | |
2932 | pmd_t _pmd; | |
2933 | int i; | |
2934 | ||
8809aa2d | 2935 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
c5a647d0 KS |
2936 | /* leave pmd empty until pte is filled */ |
2937 | ||
6b0b50b0 | 2938 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
c5a647d0 KS |
2939 | pmd_populate(mm, &_pmd, pgtable); |
2940 | ||
2941 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
2942 | pte_t *pte, entry; | |
2943 | entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); | |
2944 | entry = pte_mkspecial(entry); | |
2945 | pte = pte_offset_map(&_pmd, haddr); | |
2946 | VM_BUG_ON(!pte_none(*pte)); | |
2947 | set_pte_at(mm, haddr, pte, entry); | |
2948 | pte_unmap(pte); | |
2949 | } | |
2950 | smp_wmb(); /* make pte visible before pmd */ | |
2951 | pmd_populate(mm, pmd, pgtable); | |
97ae1749 | 2952 | put_huge_zero_page(); |
c5a647d0 KS |
2953 | } |
2954 | ||
e180377f KS |
2955 | void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address, |
2956 | pmd_t *pmd) | |
71e3aac0 | 2957 | { |
c4088ebd | 2958 | spinlock_t *ptl; |
4897c765 | 2959 | struct page *page = NULL; |
e180377f | 2960 | struct mm_struct *mm = vma->vm_mm; |
c5a647d0 KS |
2961 | unsigned long haddr = address & HPAGE_PMD_MASK; |
2962 | unsigned long mmun_start; /* For mmu_notifiers */ | |
2963 | unsigned long mmun_end; /* For mmu_notifiers */ | |
e180377f KS |
2964 | |
2965 | BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE); | |
71e3aac0 | 2966 | |
c5a647d0 KS |
2967 | mmun_start = haddr; |
2968 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
750e8165 | 2969 | again: |
c5a647d0 | 2970 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
c4088ebd | 2971 | ptl = pmd_lock(mm, pmd); |
4897c765 MW |
2972 | if (unlikely(!pmd_trans_huge(*pmd))) |
2973 | goto unlock; | |
2974 | if (vma_is_dax(vma)) { | |
5b701b84 KS |
2975 | pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
2976 | if (is_huge_zero_pmd(_pmd)) | |
2977 | put_huge_zero_page(); | |
4897c765 | 2978 | } else if (is_huge_zero_pmd(*pmd)) { |
c5a647d0 | 2979 | __split_huge_zero_page_pmd(vma, haddr, pmd); |
4897c765 MW |
2980 | } else { |
2981 | page = pmd_page(*pmd); | |
2982 | VM_BUG_ON_PAGE(!page_count(page), page); | |
2983 | get_page(page); | |
71e3aac0 | 2984 | } |
4897c765 | 2985 | unlock: |
c4088ebd | 2986 | spin_unlock(ptl); |
c5a647d0 | 2987 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
71e3aac0 | 2988 | |
4897c765 MW |
2989 | if (!page) |
2990 | return; | |
71e3aac0 | 2991 | |
4897c765 | 2992 | split_huge_page(page); |
71e3aac0 | 2993 | put_page(page); |
750e8165 HD |
2994 | |
2995 | /* | |
2996 | * We don't always have down_write of mmap_sem here: a racing | |
2997 | * do_huge_pmd_wp_page() might have copied-on-write to another | |
2998 | * huge page before our split_huge_page() got the anon_vma lock. | |
2999 | */ | |
3000 | if (unlikely(pmd_trans_huge(*pmd))) | |
3001 | goto again; | |
71e3aac0 | 3002 | } |
94fcc585 | 3003 | |
e180377f KS |
3004 | void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address, |
3005 | pmd_t *pmd) | |
3006 | { | |
3007 | struct vm_area_struct *vma; | |
3008 | ||
3009 | vma = find_vma(mm, address); | |
3010 | BUG_ON(vma == NULL); | |
3011 | split_huge_page_pmd(vma, address, pmd); | |
3012 | } | |
3013 | ||
94fcc585 AA |
3014 | static void split_huge_page_address(struct mm_struct *mm, |
3015 | unsigned long address) | |
3016 | { | |
f72e7dcd HD |
3017 | pgd_t *pgd; |
3018 | pud_t *pud; | |
94fcc585 AA |
3019 | pmd_t *pmd; |
3020 | ||
3021 | VM_BUG_ON(!(address & ~HPAGE_PMD_MASK)); | |
3022 | ||
f72e7dcd HD |
3023 | pgd = pgd_offset(mm, address); |
3024 | if (!pgd_present(*pgd)) | |
3025 | return; | |
3026 | ||
3027 | pud = pud_offset(pgd, address); | |
3028 | if (!pud_present(*pud)) | |
3029 | return; | |
3030 | ||
3031 | pmd = pmd_offset(pud, address); | |
3032 | if (!pmd_present(*pmd)) | |
94fcc585 AA |
3033 | return; |
3034 | /* | |
3035 | * Caller holds the mmap_sem write mode, so a huge pmd cannot | |
3036 | * materialize from under us. | |
3037 | */ | |
e180377f | 3038 | split_huge_page_pmd_mm(mm, address, pmd); |
94fcc585 AA |
3039 | } |
3040 | ||
e1b9996b | 3041 | void vma_adjust_trans_huge(struct vm_area_struct *vma, |
94fcc585 AA |
3042 | unsigned long start, |
3043 | unsigned long end, | |
3044 | long adjust_next) | |
3045 | { | |
3046 | /* | |
3047 | * If the new start address isn't hpage aligned and it could | |
3048 | * previously contain an hugepage: check if we need to split | |
3049 | * an huge pmd. | |
3050 | */ | |
3051 | if (start & ~HPAGE_PMD_MASK && | |
3052 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
3053 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
3054 | split_huge_page_address(vma->vm_mm, start); | |
3055 | ||
3056 | /* | |
3057 | * If the new end address isn't hpage aligned and it could | |
3058 | * previously contain an hugepage: check if we need to split | |
3059 | * an huge pmd. | |
3060 | */ | |
3061 | if (end & ~HPAGE_PMD_MASK && | |
3062 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
3063 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
3064 | split_huge_page_address(vma->vm_mm, end); | |
3065 | ||
3066 | /* | |
3067 | * If we're also updating the vma->vm_next->vm_start, if the new | |
3068 | * vm_next->vm_start isn't page aligned and it could previously | |
3069 | * contain an hugepage: check if we need to split an huge pmd. | |
3070 | */ | |
3071 | if (adjust_next > 0) { | |
3072 | struct vm_area_struct *next = vma->vm_next; | |
3073 | unsigned long nstart = next->vm_start; | |
3074 | nstart += adjust_next << PAGE_SHIFT; | |
3075 | if (nstart & ~HPAGE_PMD_MASK && | |
3076 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
3077 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
3078 | split_huge_page_address(next->vm_mm, nstart); | |
3079 | } | |
3080 | } |