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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 AA |
108 | |
109 | static int set_recommended_min_free_kbytes(void) | |
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 AA |
143 | setup_per_zone_wmarks(); |
144 | return 0; | |
145 | } | |
f000565a | 146 | |
79553da2 | 147 | static int start_stop_khugepaged(void) |
ba76149f AA |
148 | { |
149 | int err = 0; | |
150 | if (khugepaged_enabled()) { | |
ba76149f AA |
151 | if (!khugepaged_thread) |
152 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
153 | "khugepaged"); | |
154 | if (unlikely(IS_ERR(khugepaged_thread))) { | |
ae3a8c1c | 155 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); |
ba76149f AA |
156 | err = PTR_ERR(khugepaged_thread); |
157 | khugepaged_thread = NULL; | |
79553da2 | 158 | goto fail; |
ba76149f | 159 | } |
911891af XG |
160 | |
161 | if (!list_empty(&khugepaged_scan.mm_head)) | |
ba76149f | 162 | wake_up_interruptible(&khugepaged_wait); |
f000565a AA |
163 | |
164 | set_recommended_min_free_kbytes(); | |
911891af | 165 | } else if (khugepaged_thread) { |
911891af XG |
166 | kthread_stop(khugepaged_thread); |
167 | khugepaged_thread = NULL; | |
168 | } | |
79553da2 | 169 | fail: |
ba76149f AA |
170 | return err; |
171 | } | |
71e3aac0 | 172 | |
97ae1749 | 173 | static atomic_t huge_zero_refcount; |
56873f43 | 174 | struct page *huge_zero_page __read_mostly; |
4a6c1297 | 175 | |
97ae1749 KS |
176 | static inline bool is_huge_zero_pmd(pmd_t pmd) |
177 | { | |
5918d10a | 178 | return is_huge_zero_page(pmd_page(pmd)); |
97ae1749 KS |
179 | } |
180 | ||
5918d10a | 181 | static struct page *get_huge_zero_page(void) |
97ae1749 KS |
182 | { |
183 | struct page *zero_page; | |
184 | retry: | |
185 | if (likely(atomic_inc_not_zero(&huge_zero_refcount))) | |
4db0c3c2 | 186 | return READ_ONCE(huge_zero_page); |
97ae1749 KS |
187 | |
188 | zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, | |
4a6c1297 | 189 | HPAGE_PMD_ORDER); |
d8a8e1f0 KS |
190 | if (!zero_page) { |
191 | count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); | |
5918d10a | 192 | return NULL; |
d8a8e1f0 KS |
193 | } |
194 | count_vm_event(THP_ZERO_PAGE_ALLOC); | |
97ae1749 | 195 | preempt_disable(); |
5918d10a | 196 | if (cmpxchg(&huge_zero_page, NULL, zero_page)) { |
97ae1749 | 197 | preempt_enable(); |
5ddacbe9 | 198 | __free_pages(zero_page, compound_order(zero_page)); |
97ae1749 KS |
199 | goto retry; |
200 | } | |
201 | ||
202 | /* We take additional reference here. It will be put back by shrinker */ | |
203 | atomic_set(&huge_zero_refcount, 2); | |
204 | preempt_enable(); | |
4db0c3c2 | 205 | return READ_ONCE(huge_zero_page); |
4a6c1297 KS |
206 | } |
207 | ||
97ae1749 | 208 | static void put_huge_zero_page(void) |
4a6c1297 | 209 | { |
97ae1749 KS |
210 | /* |
211 | * Counter should never go to zero here. Only shrinker can put | |
212 | * last reference. | |
213 | */ | |
214 | BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); | |
4a6c1297 KS |
215 | } |
216 | ||
48896466 GC |
217 | static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, |
218 | struct shrink_control *sc) | |
4a6c1297 | 219 | { |
48896466 GC |
220 | /* we can free zero page only if last reference remains */ |
221 | return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; | |
222 | } | |
97ae1749 | 223 | |
48896466 GC |
224 | static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, |
225 | struct shrink_control *sc) | |
226 | { | |
97ae1749 | 227 | if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { |
5918d10a KS |
228 | struct page *zero_page = xchg(&huge_zero_page, NULL); |
229 | BUG_ON(zero_page == NULL); | |
5ddacbe9 | 230 | __free_pages(zero_page, compound_order(zero_page)); |
48896466 | 231 | return HPAGE_PMD_NR; |
97ae1749 KS |
232 | } |
233 | ||
234 | return 0; | |
4a6c1297 KS |
235 | } |
236 | ||
97ae1749 | 237 | static struct shrinker huge_zero_page_shrinker = { |
48896466 GC |
238 | .count_objects = shrink_huge_zero_page_count, |
239 | .scan_objects = shrink_huge_zero_page_scan, | |
97ae1749 KS |
240 | .seeks = DEFAULT_SEEKS, |
241 | }; | |
242 | ||
71e3aac0 | 243 | #ifdef CONFIG_SYSFS |
ba76149f | 244 | |
71e3aac0 AA |
245 | static ssize_t double_flag_show(struct kobject *kobj, |
246 | struct kobj_attribute *attr, char *buf, | |
247 | enum transparent_hugepage_flag enabled, | |
248 | enum transparent_hugepage_flag req_madv) | |
249 | { | |
250 | if (test_bit(enabled, &transparent_hugepage_flags)) { | |
251 | VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags)); | |
252 | return sprintf(buf, "[always] madvise never\n"); | |
253 | } else if (test_bit(req_madv, &transparent_hugepage_flags)) | |
254 | return sprintf(buf, "always [madvise] never\n"); | |
255 | else | |
256 | return sprintf(buf, "always madvise [never]\n"); | |
257 | } | |
258 | static ssize_t double_flag_store(struct kobject *kobj, | |
259 | struct kobj_attribute *attr, | |
260 | const char *buf, size_t count, | |
261 | enum transparent_hugepage_flag enabled, | |
262 | enum transparent_hugepage_flag req_madv) | |
263 | { | |
264 | if (!memcmp("always", buf, | |
265 | min(sizeof("always")-1, count))) { | |
266 | set_bit(enabled, &transparent_hugepage_flags); | |
267 | clear_bit(req_madv, &transparent_hugepage_flags); | |
268 | } else if (!memcmp("madvise", buf, | |
269 | min(sizeof("madvise")-1, count))) { | |
270 | clear_bit(enabled, &transparent_hugepage_flags); | |
271 | set_bit(req_madv, &transparent_hugepage_flags); | |
272 | } else if (!memcmp("never", buf, | |
273 | min(sizeof("never")-1, count))) { | |
274 | clear_bit(enabled, &transparent_hugepage_flags); | |
275 | clear_bit(req_madv, &transparent_hugepage_flags); | |
276 | } else | |
277 | return -EINVAL; | |
278 | ||
279 | return count; | |
280 | } | |
281 | ||
282 | static ssize_t enabled_show(struct kobject *kobj, | |
283 | struct kobj_attribute *attr, char *buf) | |
284 | { | |
285 | return double_flag_show(kobj, attr, buf, | |
286 | TRANSPARENT_HUGEPAGE_FLAG, | |
287 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
288 | } | |
289 | static ssize_t enabled_store(struct kobject *kobj, | |
290 | struct kobj_attribute *attr, | |
291 | const char *buf, size_t count) | |
292 | { | |
ba76149f AA |
293 | ssize_t ret; |
294 | ||
295 | ret = double_flag_store(kobj, attr, buf, count, | |
296 | TRANSPARENT_HUGEPAGE_FLAG, | |
297 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
298 | ||
299 | if (ret > 0) { | |
911891af XG |
300 | int err; |
301 | ||
302 | mutex_lock(&khugepaged_mutex); | |
79553da2 | 303 | err = start_stop_khugepaged(); |
911891af XG |
304 | mutex_unlock(&khugepaged_mutex); |
305 | ||
ba76149f AA |
306 | if (err) |
307 | ret = err; | |
308 | } | |
309 | ||
310 | return ret; | |
71e3aac0 AA |
311 | } |
312 | static struct kobj_attribute enabled_attr = | |
313 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
314 | ||
315 | static ssize_t single_flag_show(struct kobject *kobj, | |
316 | struct kobj_attribute *attr, char *buf, | |
317 | enum transparent_hugepage_flag flag) | |
318 | { | |
e27e6151 BH |
319 | return sprintf(buf, "%d\n", |
320 | !!test_bit(flag, &transparent_hugepage_flags)); | |
71e3aac0 | 321 | } |
e27e6151 | 322 | |
71e3aac0 AA |
323 | static ssize_t single_flag_store(struct kobject *kobj, |
324 | struct kobj_attribute *attr, | |
325 | const char *buf, size_t count, | |
326 | enum transparent_hugepage_flag flag) | |
327 | { | |
e27e6151 BH |
328 | unsigned long value; |
329 | int ret; | |
330 | ||
331 | ret = kstrtoul(buf, 10, &value); | |
332 | if (ret < 0) | |
333 | return ret; | |
334 | if (value > 1) | |
335 | return -EINVAL; | |
336 | ||
337 | if (value) | |
71e3aac0 | 338 | set_bit(flag, &transparent_hugepage_flags); |
e27e6151 | 339 | else |
71e3aac0 | 340 | clear_bit(flag, &transparent_hugepage_flags); |
71e3aac0 AA |
341 | |
342 | return count; | |
343 | } | |
344 | ||
345 | /* | |
346 | * Currently defrag only disables __GFP_NOWAIT for allocation. A blind | |
347 | * __GFP_REPEAT is too aggressive, it's never worth swapping tons of | |
348 | * memory just to allocate one more hugepage. | |
349 | */ | |
350 | static ssize_t defrag_show(struct kobject *kobj, | |
351 | struct kobj_attribute *attr, char *buf) | |
352 | { | |
353 | return double_flag_show(kobj, attr, buf, | |
354 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
355 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
356 | } | |
357 | static ssize_t defrag_store(struct kobject *kobj, | |
358 | struct kobj_attribute *attr, | |
359 | const char *buf, size_t count) | |
360 | { | |
361 | return double_flag_store(kobj, attr, buf, count, | |
362 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
363 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
364 | } | |
365 | static struct kobj_attribute defrag_attr = | |
366 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
367 | ||
79da5407 KS |
368 | static ssize_t use_zero_page_show(struct kobject *kobj, |
369 | struct kobj_attribute *attr, char *buf) | |
370 | { | |
371 | return single_flag_show(kobj, attr, buf, | |
372 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
373 | } | |
374 | static ssize_t use_zero_page_store(struct kobject *kobj, | |
375 | struct kobj_attribute *attr, const char *buf, size_t count) | |
376 | { | |
377 | return single_flag_store(kobj, attr, buf, count, | |
378 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
379 | } | |
380 | static struct kobj_attribute use_zero_page_attr = | |
381 | __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); | |
71e3aac0 AA |
382 | #ifdef CONFIG_DEBUG_VM |
383 | static ssize_t debug_cow_show(struct kobject *kobj, | |
384 | struct kobj_attribute *attr, char *buf) | |
385 | { | |
386 | return single_flag_show(kobj, attr, buf, | |
387 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
388 | } | |
389 | static ssize_t debug_cow_store(struct kobject *kobj, | |
390 | struct kobj_attribute *attr, | |
391 | const char *buf, size_t count) | |
392 | { | |
393 | return single_flag_store(kobj, attr, buf, count, | |
394 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
395 | } | |
396 | static struct kobj_attribute debug_cow_attr = | |
397 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
398 | #endif /* CONFIG_DEBUG_VM */ | |
399 | ||
400 | static struct attribute *hugepage_attr[] = { | |
401 | &enabled_attr.attr, | |
402 | &defrag_attr.attr, | |
79da5407 | 403 | &use_zero_page_attr.attr, |
71e3aac0 AA |
404 | #ifdef CONFIG_DEBUG_VM |
405 | &debug_cow_attr.attr, | |
406 | #endif | |
407 | NULL, | |
408 | }; | |
409 | ||
410 | static struct attribute_group hugepage_attr_group = { | |
411 | .attrs = hugepage_attr, | |
ba76149f AA |
412 | }; |
413 | ||
414 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, | |
415 | struct kobj_attribute *attr, | |
416 | char *buf) | |
417 | { | |
418 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
419 | } | |
420 | ||
421 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
422 | struct kobj_attribute *attr, | |
423 | const char *buf, size_t count) | |
424 | { | |
425 | unsigned long msecs; | |
426 | int err; | |
427 | ||
3dbb95f7 | 428 | err = kstrtoul(buf, 10, &msecs); |
ba76149f AA |
429 | if (err || msecs > UINT_MAX) |
430 | return -EINVAL; | |
431 | ||
432 | khugepaged_scan_sleep_millisecs = msecs; | |
433 | wake_up_interruptible(&khugepaged_wait); | |
434 | ||
435 | return count; | |
436 | } | |
437 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
438 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
439 | scan_sleep_millisecs_store); | |
440 | ||
441 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
442 | struct kobj_attribute *attr, | |
443 | char *buf) | |
444 | { | |
445 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
446 | } | |
447 | ||
448 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
449 | struct kobj_attribute *attr, | |
450 | const char *buf, size_t count) | |
451 | { | |
452 | unsigned long msecs; | |
453 | int err; | |
454 | ||
3dbb95f7 | 455 | err = kstrtoul(buf, 10, &msecs); |
ba76149f AA |
456 | if (err || msecs > UINT_MAX) |
457 | return -EINVAL; | |
458 | ||
459 | khugepaged_alloc_sleep_millisecs = msecs; | |
460 | wake_up_interruptible(&khugepaged_wait); | |
461 | ||
462 | return count; | |
463 | } | |
464 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
465 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
466 | alloc_sleep_millisecs_store); | |
467 | ||
468 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
469 | struct kobj_attribute *attr, | |
470 | char *buf) | |
471 | { | |
472 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
473 | } | |
474 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
475 | struct kobj_attribute *attr, | |
476 | const char *buf, size_t count) | |
477 | { | |
478 | int err; | |
479 | unsigned long pages; | |
480 | ||
3dbb95f7 | 481 | err = kstrtoul(buf, 10, &pages); |
ba76149f AA |
482 | if (err || !pages || pages > UINT_MAX) |
483 | return -EINVAL; | |
484 | ||
485 | khugepaged_pages_to_scan = pages; | |
486 | ||
487 | return count; | |
488 | } | |
489 | static struct kobj_attribute pages_to_scan_attr = | |
490 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
491 | pages_to_scan_store); | |
492 | ||
493 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
494 | struct kobj_attribute *attr, | |
495 | char *buf) | |
496 | { | |
497 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
498 | } | |
499 | static struct kobj_attribute pages_collapsed_attr = | |
500 | __ATTR_RO(pages_collapsed); | |
501 | ||
502 | static ssize_t full_scans_show(struct kobject *kobj, | |
503 | struct kobj_attribute *attr, | |
504 | char *buf) | |
505 | { | |
506 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
507 | } | |
508 | static struct kobj_attribute full_scans_attr = | |
509 | __ATTR_RO(full_scans); | |
510 | ||
511 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
512 | struct kobj_attribute *attr, char *buf) | |
513 | { | |
514 | return single_flag_show(kobj, attr, buf, | |
515 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
516 | } | |
517 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
518 | struct kobj_attribute *attr, | |
519 | const char *buf, size_t count) | |
520 | { | |
521 | return single_flag_store(kobj, attr, buf, count, | |
522 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
523 | } | |
524 | static struct kobj_attribute khugepaged_defrag_attr = | |
525 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
526 | khugepaged_defrag_store); | |
527 | ||
528 | /* | |
529 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
530 | * any unmapped ptes in turn potentially increasing the memory | |
531 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
532 | * reduce the available free memory in the system as it | |
533 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
534 | * free memory in the system during the khugepaged scan. | |
535 | */ | |
536 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
537 | struct kobj_attribute *attr, | |
538 | char *buf) | |
539 | { | |
540 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
541 | } | |
542 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
543 | struct kobj_attribute *attr, | |
544 | const char *buf, size_t count) | |
545 | { | |
546 | int err; | |
547 | unsigned long max_ptes_none; | |
548 | ||
3dbb95f7 | 549 | err = kstrtoul(buf, 10, &max_ptes_none); |
ba76149f AA |
550 | if (err || max_ptes_none > HPAGE_PMD_NR-1) |
551 | return -EINVAL; | |
552 | ||
553 | khugepaged_max_ptes_none = max_ptes_none; | |
554 | ||
555 | return count; | |
556 | } | |
557 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
558 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
559 | khugepaged_max_ptes_none_store); | |
560 | ||
561 | static struct attribute *khugepaged_attr[] = { | |
562 | &khugepaged_defrag_attr.attr, | |
563 | &khugepaged_max_ptes_none_attr.attr, | |
564 | &pages_to_scan_attr.attr, | |
565 | &pages_collapsed_attr.attr, | |
566 | &full_scans_attr.attr, | |
567 | &scan_sleep_millisecs_attr.attr, | |
568 | &alloc_sleep_millisecs_attr.attr, | |
569 | NULL, | |
570 | }; | |
571 | ||
572 | static struct attribute_group khugepaged_attr_group = { | |
573 | .attrs = khugepaged_attr, | |
574 | .name = "khugepaged", | |
71e3aac0 | 575 | }; |
71e3aac0 | 576 | |
569e5590 | 577 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
71e3aac0 | 578 | { |
71e3aac0 AA |
579 | int err; |
580 | ||
569e5590 SL |
581 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); |
582 | if (unlikely(!*hugepage_kobj)) { | |
ae3a8c1c | 583 | pr_err("failed to create transparent hugepage kobject\n"); |
569e5590 | 584 | return -ENOMEM; |
ba76149f AA |
585 | } |
586 | ||
569e5590 | 587 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); |
ba76149f | 588 | if (err) { |
ae3a8c1c | 589 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 590 | goto delete_obj; |
ba76149f AA |
591 | } |
592 | ||
569e5590 | 593 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); |
ba76149f | 594 | if (err) { |
ae3a8c1c | 595 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 596 | goto remove_hp_group; |
ba76149f | 597 | } |
569e5590 SL |
598 | |
599 | return 0; | |
600 | ||
601 | remove_hp_group: | |
602 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
603 | delete_obj: | |
604 | kobject_put(*hugepage_kobj); | |
605 | return err; | |
606 | } | |
607 | ||
608 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
609 | { | |
610 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
611 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
612 | kobject_put(hugepage_kobj); | |
613 | } | |
614 | #else | |
615 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
616 | { | |
617 | return 0; | |
618 | } | |
619 | ||
620 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
621 | { | |
622 | } | |
623 | #endif /* CONFIG_SYSFS */ | |
624 | ||
625 | static int __init hugepage_init(void) | |
626 | { | |
627 | int err; | |
628 | struct kobject *hugepage_kobj; | |
629 | ||
630 | if (!has_transparent_hugepage()) { | |
631 | transparent_hugepage_flags = 0; | |
632 | return -EINVAL; | |
633 | } | |
634 | ||
635 | err = hugepage_init_sysfs(&hugepage_kobj); | |
636 | if (err) | |
65ebb64f | 637 | goto err_sysfs; |
ba76149f AA |
638 | |
639 | err = khugepaged_slab_init(); | |
640 | if (err) | |
65ebb64f | 641 | goto err_slab; |
ba76149f | 642 | |
65ebb64f KS |
643 | err = register_shrinker(&huge_zero_page_shrinker); |
644 | if (err) | |
645 | goto err_hzp_shrinker; | |
97ae1749 | 646 | |
97562cd2 RR |
647 | /* |
648 | * By default disable transparent hugepages on smaller systems, | |
649 | * where the extra memory used could hurt more than TLB overhead | |
650 | * is likely to save. The admin can still enable it through /sys. | |
651 | */ | |
79553da2 | 652 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) { |
97562cd2 | 653 | transparent_hugepage_flags = 0; |
79553da2 KS |
654 | return 0; |
655 | } | |
97562cd2 | 656 | |
79553da2 | 657 | err = start_stop_khugepaged(); |
65ebb64f KS |
658 | if (err) |
659 | goto err_khugepaged; | |
ba76149f | 660 | |
569e5590 | 661 | return 0; |
65ebb64f KS |
662 | err_khugepaged: |
663 | unregister_shrinker(&huge_zero_page_shrinker); | |
664 | err_hzp_shrinker: | |
665 | khugepaged_slab_exit(); | |
666 | err_slab: | |
569e5590 | 667 | hugepage_exit_sysfs(hugepage_kobj); |
65ebb64f | 668 | err_sysfs: |
ba76149f | 669 | return err; |
71e3aac0 | 670 | } |
a64fb3cd | 671 | subsys_initcall(hugepage_init); |
71e3aac0 AA |
672 | |
673 | static int __init setup_transparent_hugepage(char *str) | |
674 | { | |
675 | int ret = 0; | |
676 | if (!str) | |
677 | goto out; | |
678 | if (!strcmp(str, "always")) { | |
679 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
680 | &transparent_hugepage_flags); | |
681 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
682 | &transparent_hugepage_flags); | |
683 | ret = 1; | |
684 | } else if (!strcmp(str, "madvise")) { | |
685 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
686 | &transparent_hugepage_flags); | |
687 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
688 | &transparent_hugepage_flags); | |
689 | ret = 1; | |
690 | } else if (!strcmp(str, "never")) { | |
691 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
692 | &transparent_hugepage_flags); | |
693 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
694 | &transparent_hugepage_flags); | |
695 | ret = 1; | |
696 | } | |
697 | out: | |
698 | if (!ret) | |
ae3a8c1c | 699 | pr_warn("transparent_hugepage= cannot parse, ignored\n"); |
71e3aac0 AA |
700 | return ret; |
701 | } | |
702 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
703 | ||
b32967ff | 704 | pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) |
71e3aac0 AA |
705 | { |
706 | if (likely(vma->vm_flags & VM_WRITE)) | |
707 | pmd = pmd_mkwrite(pmd); | |
708 | return pmd; | |
709 | } | |
710 | ||
3122359a | 711 | static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot) |
b3092b3b BL |
712 | { |
713 | pmd_t entry; | |
3122359a | 714 | entry = mk_pmd(page, prot); |
b3092b3b BL |
715 | entry = pmd_mkhuge(entry); |
716 | return entry; | |
717 | } | |
718 | ||
71e3aac0 AA |
719 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, |
720 | struct vm_area_struct *vma, | |
230c92a8 | 721 | unsigned long address, pmd_t *pmd, |
6b251fc9 AA |
722 | struct page *page, gfp_t gfp, |
723 | unsigned int flags) | |
71e3aac0 | 724 | { |
00501b53 | 725 | struct mem_cgroup *memcg; |
71e3aac0 | 726 | pgtable_t pgtable; |
c4088ebd | 727 | spinlock_t *ptl; |
230c92a8 | 728 | unsigned long haddr = address & HPAGE_PMD_MASK; |
71e3aac0 | 729 | |
309381fe | 730 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
00501b53 | 731 | |
6b251fc9 AA |
732 | if (mem_cgroup_try_charge(page, mm, gfp, &memcg)) { |
733 | put_page(page); | |
734 | count_vm_event(THP_FAULT_FALLBACK); | |
735 | return VM_FAULT_FALLBACK; | |
736 | } | |
00501b53 | 737 | |
71e3aac0 | 738 | pgtable = pte_alloc_one(mm, haddr); |
00501b53 JW |
739 | if (unlikely(!pgtable)) { |
740 | mem_cgroup_cancel_charge(page, memcg); | |
6b251fc9 | 741 | put_page(page); |
71e3aac0 | 742 | return VM_FAULT_OOM; |
00501b53 | 743 | } |
71e3aac0 AA |
744 | |
745 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
52f37629 MK |
746 | /* |
747 | * The memory barrier inside __SetPageUptodate makes sure that | |
748 | * clear_huge_page writes become visible before the set_pmd_at() | |
749 | * write. | |
750 | */ | |
71e3aac0 AA |
751 | __SetPageUptodate(page); |
752 | ||
c4088ebd | 753 | ptl = pmd_lock(mm, pmd); |
71e3aac0 | 754 | if (unlikely(!pmd_none(*pmd))) { |
c4088ebd | 755 | spin_unlock(ptl); |
00501b53 | 756 | mem_cgroup_cancel_charge(page, memcg); |
71e3aac0 AA |
757 | put_page(page); |
758 | pte_free(mm, pgtable); | |
759 | } else { | |
760 | pmd_t entry; | |
6b251fc9 AA |
761 | |
762 | /* Deliver the page fault to userland */ | |
763 | if (userfaultfd_missing(vma)) { | |
764 | int ret; | |
765 | ||
766 | spin_unlock(ptl); | |
767 | mem_cgroup_cancel_charge(page, memcg); | |
768 | put_page(page); | |
769 | pte_free(mm, pgtable); | |
230c92a8 | 770 | ret = handle_userfault(vma, address, flags, |
6b251fc9 AA |
771 | VM_UFFD_MISSING); |
772 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
773 | return ret; | |
774 | } | |
775 | ||
3122359a KS |
776 | entry = mk_huge_pmd(page, vma->vm_page_prot); |
777 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
71e3aac0 | 778 | page_add_new_anon_rmap(page, vma, haddr); |
00501b53 JW |
779 | mem_cgroup_commit_charge(page, memcg, false); |
780 | lru_cache_add_active_or_unevictable(page, vma); | |
6b0b50b0 | 781 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
71e3aac0 | 782 | set_pmd_at(mm, haddr, pmd, entry); |
71e3aac0 | 783 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
e1f56c89 | 784 | atomic_long_inc(&mm->nr_ptes); |
c4088ebd | 785 | spin_unlock(ptl); |
6b251fc9 | 786 | count_vm_event(THP_FAULT_ALLOC); |
71e3aac0 AA |
787 | } |
788 | ||
aa2e878e | 789 | return 0; |
71e3aac0 AA |
790 | } |
791 | ||
cc5d462f | 792 | static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp) |
0bbbc0b3 | 793 | { |
cc5d462f | 794 | return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp; |
0bbbc0b3 AA |
795 | } |
796 | ||
c4088ebd | 797 | /* Caller must hold page table lock. */ |
4897c765 | 798 | bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, |
97ae1749 | 799 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, |
5918d10a | 800 | struct page *zero_page) |
fc9fe822 KS |
801 | { |
802 | pmd_t entry; | |
7c414164 AM |
803 | if (!pmd_none(*pmd)) |
804 | return false; | |
5918d10a | 805 | entry = mk_pmd(zero_page, vma->vm_page_prot); |
fc9fe822 | 806 | entry = pmd_mkhuge(entry); |
6b0b50b0 | 807 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
fc9fe822 | 808 | set_pmd_at(mm, haddr, pmd, entry); |
e1f56c89 | 809 | atomic_long_inc(&mm->nr_ptes); |
7c414164 | 810 | return true; |
fc9fe822 KS |
811 | } |
812 | ||
71e3aac0 AA |
813 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, |
814 | unsigned long address, pmd_t *pmd, | |
815 | unsigned int flags) | |
816 | { | |
077fcf11 | 817 | gfp_t gfp; |
71e3aac0 AA |
818 | struct page *page; |
819 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
71e3aac0 | 820 | |
128ec037 | 821 | if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) |
c0292554 | 822 | return VM_FAULT_FALLBACK; |
128ec037 KS |
823 | if (unlikely(anon_vma_prepare(vma))) |
824 | return VM_FAULT_OOM; | |
6d50e60c | 825 | if (unlikely(khugepaged_enter(vma, vma->vm_flags))) |
128ec037 | 826 | return VM_FAULT_OOM; |
593befa6 | 827 | if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) && |
128ec037 | 828 | transparent_hugepage_use_zero_page()) { |
c4088ebd | 829 | spinlock_t *ptl; |
128ec037 KS |
830 | pgtable_t pgtable; |
831 | struct page *zero_page; | |
832 | bool set; | |
6b251fc9 | 833 | int ret; |
128ec037 KS |
834 | pgtable = pte_alloc_one(mm, haddr); |
835 | if (unlikely(!pgtable)) | |
ba76149f | 836 | return VM_FAULT_OOM; |
128ec037 KS |
837 | zero_page = get_huge_zero_page(); |
838 | if (unlikely(!zero_page)) { | |
839 | pte_free(mm, pgtable); | |
81ab4201 | 840 | count_vm_event(THP_FAULT_FALLBACK); |
c0292554 | 841 | return VM_FAULT_FALLBACK; |
b9bbfbe3 | 842 | } |
c4088ebd | 843 | ptl = pmd_lock(mm, pmd); |
6b251fc9 AA |
844 | ret = 0; |
845 | set = false; | |
846 | if (pmd_none(*pmd)) { | |
847 | if (userfaultfd_missing(vma)) { | |
848 | spin_unlock(ptl); | |
230c92a8 | 849 | ret = handle_userfault(vma, address, flags, |
6b251fc9 AA |
850 | VM_UFFD_MISSING); |
851 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
852 | } else { | |
853 | set_huge_zero_page(pgtable, mm, vma, | |
854 | haddr, pmd, | |
855 | zero_page); | |
856 | spin_unlock(ptl); | |
857 | set = true; | |
858 | } | |
859 | } else | |
860 | spin_unlock(ptl); | |
128ec037 KS |
861 | if (!set) { |
862 | pte_free(mm, pgtable); | |
863 | put_huge_zero_page(); | |
edad9d2c | 864 | } |
6b251fc9 | 865 | return ret; |
71e3aac0 | 866 | } |
077fcf11 AK |
867 | gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0); |
868 | page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); | |
128ec037 KS |
869 | if (unlikely(!page)) { |
870 | count_vm_event(THP_FAULT_FALLBACK); | |
c0292554 | 871 | return VM_FAULT_FALLBACK; |
128ec037 | 872 | } |
230c92a8 AA |
873 | return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp, |
874 | flags); | |
71e3aac0 AA |
875 | } |
876 | ||
877 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, | |
878 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
879 | struct vm_area_struct *vma) | |
880 | { | |
c4088ebd | 881 | spinlock_t *dst_ptl, *src_ptl; |
71e3aac0 AA |
882 | struct page *src_page; |
883 | pmd_t pmd; | |
884 | pgtable_t pgtable; | |
885 | int ret; | |
886 | ||
887 | ret = -ENOMEM; | |
888 | pgtable = pte_alloc_one(dst_mm, addr); | |
889 | if (unlikely(!pgtable)) | |
890 | goto out; | |
891 | ||
c4088ebd KS |
892 | dst_ptl = pmd_lock(dst_mm, dst_pmd); |
893 | src_ptl = pmd_lockptr(src_mm, src_pmd); | |
894 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
71e3aac0 AA |
895 | |
896 | ret = -EAGAIN; | |
897 | pmd = *src_pmd; | |
898 | if (unlikely(!pmd_trans_huge(pmd))) { | |
899 | pte_free(dst_mm, pgtable); | |
900 | goto out_unlock; | |
901 | } | |
fc9fe822 | 902 | /* |
c4088ebd | 903 | * When page table lock is held, the huge zero pmd should not be |
fc9fe822 KS |
904 | * under splitting since we don't split the page itself, only pmd to |
905 | * a page table. | |
906 | */ | |
907 | if (is_huge_zero_pmd(pmd)) { | |
5918d10a | 908 | struct page *zero_page; |
97ae1749 KS |
909 | /* |
910 | * get_huge_zero_page() will never allocate a new page here, | |
911 | * since we already have a zero page to copy. It just takes a | |
912 | * reference. | |
913 | */ | |
5918d10a | 914 | zero_page = get_huge_zero_page(); |
6b251fc9 | 915 | set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, |
5918d10a | 916 | zero_page); |
fc9fe822 KS |
917 | ret = 0; |
918 | goto out_unlock; | |
919 | } | |
de466bd6 | 920 | |
71e3aac0 AA |
921 | if (unlikely(pmd_trans_splitting(pmd))) { |
922 | /* split huge page running from under us */ | |
c4088ebd KS |
923 | spin_unlock(src_ptl); |
924 | spin_unlock(dst_ptl); | |
71e3aac0 AA |
925 | pte_free(dst_mm, pgtable); |
926 | ||
927 | wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */ | |
928 | goto out; | |
929 | } | |
930 | src_page = pmd_page(pmd); | |
309381fe | 931 | VM_BUG_ON_PAGE(!PageHead(src_page), src_page); |
71e3aac0 AA |
932 | get_page(src_page); |
933 | page_dup_rmap(src_page); | |
934 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
935 | ||
936 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
937 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
6b0b50b0 | 938 | pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); |
71e3aac0 | 939 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); |
e1f56c89 | 940 | atomic_long_inc(&dst_mm->nr_ptes); |
71e3aac0 AA |
941 | |
942 | ret = 0; | |
943 | out_unlock: | |
c4088ebd KS |
944 | spin_unlock(src_ptl); |
945 | spin_unlock(dst_ptl); | |
71e3aac0 AA |
946 | out: |
947 | return ret; | |
948 | } | |
949 | ||
a1dd450b WD |
950 | void huge_pmd_set_accessed(struct mm_struct *mm, |
951 | struct vm_area_struct *vma, | |
952 | unsigned long address, | |
953 | pmd_t *pmd, pmd_t orig_pmd, | |
954 | int dirty) | |
955 | { | |
c4088ebd | 956 | spinlock_t *ptl; |
a1dd450b WD |
957 | pmd_t entry; |
958 | unsigned long haddr; | |
959 | ||
c4088ebd | 960 | ptl = pmd_lock(mm, pmd); |
a1dd450b WD |
961 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
962 | goto unlock; | |
963 | ||
964 | entry = pmd_mkyoung(orig_pmd); | |
965 | haddr = address & HPAGE_PMD_MASK; | |
966 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty)) | |
967 | update_mmu_cache_pmd(vma, address, pmd); | |
968 | ||
969 | unlock: | |
c4088ebd | 970 | spin_unlock(ptl); |
a1dd450b WD |
971 | } |
972 | ||
5338a937 HD |
973 | /* |
974 | * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages | |
975 | * during copy_user_huge_page()'s copy_page_rep(): in the case when | |
976 | * the source page gets split and a tail freed before copy completes. | |
977 | * Called under pmd_lock of checked pmd, so safe from splitting itself. | |
978 | */ | |
979 | static void get_user_huge_page(struct page *page) | |
980 | { | |
981 | if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) { | |
982 | struct page *endpage = page + HPAGE_PMD_NR; | |
983 | ||
984 | atomic_add(HPAGE_PMD_NR, &page->_count); | |
985 | while (++page < endpage) | |
986 | get_huge_page_tail(page); | |
987 | } else { | |
988 | get_page(page); | |
989 | } | |
990 | } | |
991 | ||
992 | static void put_user_huge_page(struct page *page) | |
993 | { | |
994 | if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) { | |
995 | struct page *endpage = page + HPAGE_PMD_NR; | |
996 | ||
997 | while (page < endpage) | |
998 | put_page(page++); | |
999 | } else { | |
1000 | put_page(page); | |
1001 | } | |
1002 | } | |
1003 | ||
71e3aac0 AA |
1004 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, |
1005 | struct vm_area_struct *vma, | |
1006 | unsigned long address, | |
1007 | pmd_t *pmd, pmd_t orig_pmd, | |
1008 | struct page *page, | |
1009 | unsigned long haddr) | |
1010 | { | |
00501b53 | 1011 | struct mem_cgroup *memcg; |
c4088ebd | 1012 | spinlock_t *ptl; |
71e3aac0 AA |
1013 | pgtable_t pgtable; |
1014 | pmd_t _pmd; | |
1015 | int ret = 0, i; | |
1016 | struct page **pages; | |
2ec74c3e SG |
1017 | unsigned long mmun_start; /* For mmu_notifiers */ |
1018 | unsigned long mmun_end; /* For mmu_notifiers */ | |
71e3aac0 AA |
1019 | |
1020 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
1021 | GFP_KERNEL); | |
1022 | if (unlikely(!pages)) { | |
1023 | ret |= VM_FAULT_OOM; | |
1024 | goto out; | |
1025 | } | |
1026 | ||
1027 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
cc5d462f AK |
1028 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE | |
1029 | __GFP_OTHER_NODE, | |
19ee151e | 1030 | vma, address, page_to_nid(page)); |
b9bbfbe3 | 1031 | if (unlikely(!pages[i] || |
00501b53 JW |
1032 | mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL, |
1033 | &memcg))) { | |
b9bbfbe3 | 1034 | if (pages[i]) |
71e3aac0 | 1035 | put_page(pages[i]); |
b9bbfbe3 | 1036 | while (--i >= 0) { |
00501b53 JW |
1037 | memcg = (void *)page_private(pages[i]); |
1038 | set_page_private(pages[i], 0); | |
1039 | mem_cgroup_cancel_charge(pages[i], memcg); | |
b9bbfbe3 AA |
1040 | put_page(pages[i]); |
1041 | } | |
71e3aac0 AA |
1042 | kfree(pages); |
1043 | ret |= VM_FAULT_OOM; | |
1044 | goto out; | |
1045 | } | |
00501b53 | 1046 | set_page_private(pages[i], (unsigned long)memcg); |
71e3aac0 AA |
1047 | } |
1048 | ||
1049 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1050 | copy_user_highpage(pages[i], page + i, | |
0089e485 | 1051 | haddr + PAGE_SIZE * i, vma); |
71e3aac0 AA |
1052 | __SetPageUptodate(pages[i]); |
1053 | cond_resched(); | |
1054 | } | |
1055 | ||
2ec74c3e SG |
1056 | mmun_start = haddr; |
1057 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1058 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1059 | ||
c4088ebd | 1060 | ptl = pmd_lock(mm, pmd); |
71e3aac0 AA |
1061 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1062 | goto out_free_pages; | |
309381fe | 1063 | VM_BUG_ON_PAGE(!PageHead(page), page); |
71e3aac0 | 1064 | |
8809aa2d | 1065 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
71e3aac0 AA |
1066 | /* leave pmd empty until pte is filled */ |
1067 | ||
6b0b50b0 | 1068 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
71e3aac0 AA |
1069 | pmd_populate(mm, &_pmd, pgtable); |
1070 | ||
1071 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
1072 | pte_t *pte, entry; | |
1073 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
1074 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
00501b53 JW |
1075 | memcg = (void *)page_private(pages[i]); |
1076 | set_page_private(pages[i], 0); | |
71e3aac0 | 1077 | page_add_new_anon_rmap(pages[i], vma, haddr); |
00501b53 JW |
1078 | mem_cgroup_commit_charge(pages[i], memcg, false); |
1079 | lru_cache_add_active_or_unevictable(pages[i], vma); | |
71e3aac0 AA |
1080 | pte = pte_offset_map(&_pmd, haddr); |
1081 | VM_BUG_ON(!pte_none(*pte)); | |
1082 | set_pte_at(mm, haddr, pte, entry); | |
1083 | pte_unmap(pte); | |
1084 | } | |
1085 | kfree(pages); | |
1086 | ||
71e3aac0 AA |
1087 | smp_wmb(); /* make pte visible before pmd */ |
1088 | pmd_populate(mm, pmd, pgtable); | |
1089 | page_remove_rmap(page); | |
c4088ebd | 1090 | spin_unlock(ptl); |
71e3aac0 | 1091 | |
2ec74c3e SG |
1092 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
1093 | ||
71e3aac0 AA |
1094 | ret |= VM_FAULT_WRITE; |
1095 | put_page(page); | |
1096 | ||
1097 | out: | |
1098 | return ret; | |
1099 | ||
1100 | out_free_pages: | |
c4088ebd | 1101 | spin_unlock(ptl); |
2ec74c3e | 1102 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
b9bbfbe3 | 1103 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
00501b53 JW |
1104 | memcg = (void *)page_private(pages[i]); |
1105 | set_page_private(pages[i], 0); | |
1106 | mem_cgroup_cancel_charge(pages[i], memcg); | |
71e3aac0 | 1107 | put_page(pages[i]); |
b9bbfbe3 | 1108 | } |
71e3aac0 AA |
1109 | kfree(pages); |
1110 | goto out; | |
1111 | } | |
1112 | ||
1113 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
1114 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) | |
1115 | { | |
c4088ebd | 1116 | spinlock_t *ptl; |
71e3aac0 | 1117 | int ret = 0; |
93b4796d | 1118 | struct page *page = NULL, *new_page; |
00501b53 | 1119 | struct mem_cgroup *memcg; |
71e3aac0 | 1120 | unsigned long haddr; |
2ec74c3e SG |
1121 | unsigned long mmun_start; /* For mmu_notifiers */ |
1122 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 1123 | gfp_t huge_gfp; /* for allocation and charge */ |
71e3aac0 | 1124 | |
c4088ebd | 1125 | ptl = pmd_lockptr(mm, pmd); |
81d1b09c | 1126 | VM_BUG_ON_VMA(!vma->anon_vma, vma); |
93b4796d KS |
1127 | haddr = address & HPAGE_PMD_MASK; |
1128 | if (is_huge_zero_pmd(orig_pmd)) | |
1129 | goto alloc; | |
c4088ebd | 1130 | spin_lock(ptl); |
71e3aac0 AA |
1131 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1132 | goto out_unlock; | |
1133 | ||
1134 | page = pmd_page(orig_pmd); | |
309381fe | 1135 | VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); |
71e3aac0 AA |
1136 | if (page_mapcount(page) == 1) { |
1137 | pmd_t entry; | |
1138 | entry = pmd_mkyoung(orig_pmd); | |
1139 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
1140 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) | |
b113da65 | 1141 | update_mmu_cache_pmd(vma, address, pmd); |
71e3aac0 AA |
1142 | ret |= VM_FAULT_WRITE; |
1143 | goto out_unlock; | |
1144 | } | |
5338a937 | 1145 | get_user_huge_page(page); |
c4088ebd | 1146 | spin_unlock(ptl); |
93b4796d | 1147 | alloc: |
71e3aac0 | 1148 | if (transparent_hugepage_enabled(vma) && |
077fcf11 | 1149 | !transparent_hugepage_debug_cow()) { |
3b363692 MH |
1150 | huge_gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0); |
1151 | new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); | |
077fcf11 | 1152 | } else |
71e3aac0 AA |
1153 | new_page = NULL; |
1154 | ||
1155 | if (unlikely(!new_page)) { | |
eecc1e42 | 1156 | if (!page) { |
e9b71ca9 KS |
1157 | split_huge_page_pmd(vma, address, pmd); |
1158 | ret |= VM_FAULT_FALLBACK; | |
93b4796d KS |
1159 | } else { |
1160 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, | |
1161 | pmd, orig_pmd, page, haddr); | |
9845cbbd | 1162 | if (ret & VM_FAULT_OOM) { |
93b4796d | 1163 | split_huge_page(page); |
9845cbbd KS |
1164 | ret |= VM_FAULT_FALLBACK; |
1165 | } | |
5338a937 | 1166 | put_user_huge_page(page); |
93b4796d | 1167 | } |
17766dde | 1168 | count_vm_event(THP_FAULT_FALLBACK); |
71e3aac0 AA |
1169 | goto out; |
1170 | } | |
1171 | ||
3b363692 | 1172 | if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg))) { |
b9bbfbe3 | 1173 | put_page(new_page); |
93b4796d KS |
1174 | if (page) { |
1175 | split_huge_page(page); | |
5338a937 | 1176 | put_user_huge_page(page); |
9845cbbd KS |
1177 | } else |
1178 | split_huge_page_pmd(vma, address, pmd); | |
1179 | ret |= VM_FAULT_FALLBACK; | |
17766dde | 1180 | count_vm_event(THP_FAULT_FALLBACK); |
b9bbfbe3 AA |
1181 | goto out; |
1182 | } | |
1183 | ||
17766dde DR |
1184 | count_vm_event(THP_FAULT_ALLOC); |
1185 | ||
eecc1e42 | 1186 | if (!page) |
93b4796d KS |
1187 | clear_huge_page(new_page, haddr, HPAGE_PMD_NR); |
1188 | else | |
1189 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); | |
71e3aac0 AA |
1190 | __SetPageUptodate(new_page); |
1191 | ||
2ec74c3e SG |
1192 | mmun_start = haddr; |
1193 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1194 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1195 | ||
c4088ebd | 1196 | spin_lock(ptl); |
93b4796d | 1197 | if (page) |
5338a937 | 1198 | put_user_huge_page(page); |
b9bbfbe3 | 1199 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { |
c4088ebd | 1200 | spin_unlock(ptl); |
00501b53 | 1201 | mem_cgroup_cancel_charge(new_page, memcg); |
71e3aac0 | 1202 | put_page(new_page); |
2ec74c3e | 1203 | goto out_mn; |
b9bbfbe3 | 1204 | } else { |
71e3aac0 | 1205 | pmd_t entry; |
3122359a KS |
1206 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); |
1207 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
8809aa2d | 1208 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
71e3aac0 | 1209 | page_add_new_anon_rmap(new_page, vma, haddr); |
00501b53 JW |
1210 | mem_cgroup_commit_charge(new_page, memcg, false); |
1211 | lru_cache_add_active_or_unevictable(new_page, vma); | |
71e3aac0 | 1212 | set_pmd_at(mm, haddr, pmd, entry); |
b113da65 | 1213 | update_mmu_cache_pmd(vma, address, pmd); |
eecc1e42 | 1214 | if (!page) { |
93b4796d | 1215 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
97ae1749 KS |
1216 | put_huge_zero_page(); |
1217 | } else { | |
309381fe | 1218 | VM_BUG_ON_PAGE(!PageHead(page), page); |
93b4796d KS |
1219 | page_remove_rmap(page); |
1220 | put_page(page); | |
1221 | } | |
71e3aac0 AA |
1222 | ret |= VM_FAULT_WRITE; |
1223 | } | |
c4088ebd | 1224 | spin_unlock(ptl); |
2ec74c3e SG |
1225 | out_mn: |
1226 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
71e3aac0 AA |
1227 | out: |
1228 | return ret; | |
2ec74c3e | 1229 | out_unlock: |
c4088ebd | 1230 | spin_unlock(ptl); |
2ec74c3e | 1231 | return ret; |
71e3aac0 AA |
1232 | } |
1233 | ||
b676b293 | 1234 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, |
71e3aac0 AA |
1235 | unsigned long addr, |
1236 | pmd_t *pmd, | |
1237 | unsigned int flags) | |
1238 | { | |
b676b293 | 1239 | struct mm_struct *mm = vma->vm_mm; |
71e3aac0 AA |
1240 | struct page *page = NULL; |
1241 | ||
c4088ebd | 1242 | assert_spin_locked(pmd_lockptr(mm, pmd)); |
71e3aac0 AA |
1243 | |
1244 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1245 | goto out; | |
1246 | ||
85facf25 KS |
1247 | /* Avoid dumping huge zero page */ |
1248 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) | |
1249 | return ERR_PTR(-EFAULT); | |
1250 | ||
2b4847e7 | 1251 | /* Full NUMA hinting faults to serialise migration in fault paths */ |
8a0516ed | 1252 | if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) |
2b4847e7 MG |
1253 | goto out; |
1254 | ||
71e3aac0 | 1255 | page = pmd_page(*pmd); |
309381fe | 1256 | VM_BUG_ON_PAGE(!PageHead(page), page); |
71e3aac0 AA |
1257 | if (flags & FOLL_TOUCH) { |
1258 | pmd_t _pmd; | |
1259 | /* | |
1260 | * We should set the dirty bit only for FOLL_WRITE but | |
1261 | * for now the dirty bit in the pmd is meaningless. | |
1262 | * And if the dirty bit will become meaningful and | |
1263 | * we'll only set it with FOLL_WRITE, an atomic | |
1264 | * set_bit will be required on the pmd to set the | |
1265 | * young bit, instead of the current set_pmd_at. | |
1266 | */ | |
1267 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
8663890a AK |
1268 | if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, |
1269 | pmd, _pmd, 1)) | |
1270 | update_mmu_cache_pmd(vma, addr, pmd); | |
71e3aac0 | 1271 | } |
84d33df2 | 1272 | if ((flags & FOLL_POPULATE) && (vma->vm_flags & VM_LOCKED)) { |
b676b293 DR |
1273 | if (page->mapping && trylock_page(page)) { |
1274 | lru_add_drain(); | |
1275 | if (page->mapping) | |
1276 | mlock_vma_page(page); | |
1277 | unlock_page(page); | |
1278 | } | |
1279 | } | |
71e3aac0 | 1280 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
309381fe | 1281 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
71e3aac0 | 1282 | if (flags & FOLL_GET) |
70b50f94 | 1283 | get_page_foll(page); |
71e3aac0 AA |
1284 | |
1285 | out: | |
1286 | return page; | |
1287 | } | |
1288 | ||
d10e63f2 | 1289 | /* NUMA hinting page fault entry point for trans huge pmds */ |
4daae3b4 MG |
1290 | int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, |
1291 | unsigned long addr, pmd_t pmd, pmd_t *pmdp) | |
d10e63f2 | 1292 | { |
c4088ebd | 1293 | spinlock_t *ptl; |
b8916634 | 1294 | struct anon_vma *anon_vma = NULL; |
b32967ff | 1295 | struct page *page; |
d10e63f2 | 1296 | unsigned long haddr = addr & HPAGE_PMD_MASK; |
8191acbd | 1297 | int page_nid = -1, this_nid = numa_node_id(); |
90572890 | 1298 | int target_nid, last_cpupid = -1; |
8191acbd MG |
1299 | bool page_locked; |
1300 | bool migrated = false; | |
b191f9b1 | 1301 | bool was_writable; |
6688cc05 | 1302 | int flags = 0; |
d10e63f2 | 1303 | |
c0e7cad9 MG |
1304 | /* A PROT_NONE fault should not end up here */ |
1305 | BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))); | |
1306 | ||
c4088ebd | 1307 | ptl = pmd_lock(mm, pmdp); |
d10e63f2 MG |
1308 | if (unlikely(!pmd_same(pmd, *pmdp))) |
1309 | goto out_unlock; | |
1310 | ||
de466bd6 MG |
1311 | /* |
1312 | * If there are potential migrations, wait for completion and retry | |
1313 | * without disrupting NUMA hinting information. Do not relock and | |
1314 | * check_same as the page may no longer be mapped. | |
1315 | */ | |
1316 | if (unlikely(pmd_trans_migrating(*pmdp))) { | |
5d833062 | 1317 | page = pmd_page(*pmdp); |
de466bd6 | 1318 | spin_unlock(ptl); |
5d833062 | 1319 | wait_on_page_locked(page); |
de466bd6 MG |
1320 | goto out; |
1321 | } | |
1322 | ||
d10e63f2 | 1323 | page = pmd_page(pmd); |
a1a46184 | 1324 | BUG_ON(is_huge_zero_page(page)); |
8191acbd | 1325 | page_nid = page_to_nid(page); |
90572890 | 1326 | last_cpupid = page_cpupid_last(page); |
03c5a6e1 | 1327 | count_vm_numa_event(NUMA_HINT_FAULTS); |
04bb2f94 | 1328 | if (page_nid == this_nid) { |
03c5a6e1 | 1329 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
04bb2f94 RR |
1330 | flags |= TNF_FAULT_LOCAL; |
1331 | } | |
4daae3b4 | 1332 | |
bea66fbd MG |
1333 | /* See similar comment in do_numa_page for explanation */ |
1334 | if (!(vma->vm_flags & VM_WRITE)) | |
6688cc05 PZ |
1335 | flags |= TNF_NO_GROUP; |
1336 | ||
ff9042b1 MG |
1337 | /* |
1338 | * Acquire the page lock to serialise THP migrations but avoid dropping | |
1339 | * page_table_lock if at all possible | |
1340 | */ | |
b8916634 MG |
1341 | page_locked = trylock_page(page); |
1342 | target_nid = mpol_misplaced(page, vma, haddr); | |
1343 | if (target_nid == -1) { | |
1344 | /* If the page was locked, there are no parallel migrations */ | |
a54a407f | 1345 | if (page_locked) |
b8916634 | 1346 | goto clear_pmdnuma; |
2b4847e7 | 1347 | } |
4daae3b4 | 1348 | |
de466bd6 | 1349 | /* Migration could have started since the pmd_trans_migrating check */ |
2b4847e7 | 1350 | if (!page_locked) { |
c4088ebd | 1351 | spin_unlock(ptl); |
b8916634 | 1352 | wait_on_page_locked(page); |
a54a407f | 1353 | page_nid = -1; |
b8916634 MG |
1354 | goto out; |
1355 | } | |
1356 | ||
2b4847e7 MG |
1357 | /* |
1358 | * Page is misplaced. Page lock serialises migrations. Acquire anon_vma | |
1359 | * to serialises splits | |
1360 | */ | |
b8916634 | 1361 | get_page(page); |
c4088ebd | 1362 | spin_unlock(ptl); |
b8916634 | 1363 | anon_vma = page_lock_anon_vma_read(page); |
4daae3b4 | 1364 | |
c69307d5 | 1365 | /* Confirm the PMD did not change while page_table_lock was released */ |
c4088ebd | 1366 | spin_lock(ptl); |
b32967ff MG |
1367 | if (unlikely(!pmd_same(pmd, *pmdp))) { |
1368 | unlock_page(page); | |
1369 | put_page(page); | |
a54a407f | 1370 | page_nid = -1; |
4daae3b4 | 1371 | goto out_unlock; |
b32967ff | 1372 | } |
ff9042b1 | 1373 | |
c3a489ca MG |
1374 | /* Bail if we fail to protect against THP splits for any reason */ |
1375 | if (unlikely(!anon_vma)) { | |
1376 | put_page(page); | |
1377 | page_nid = -1; | |
1378 | goto clear_pmdnuma; | |
1379 | } | |
1380 | ||
a54a407f MG |
1381 | /* |
1382 | * Migrate the THP to the requested node, returns with page unlocked | |
8a0516ed | 1383 | * and access rights restored. |
a54a407f | 1384 | */ |
c4088ebd | 1385 | spin_unlock(ptl); |
b32967ff | 1386 | migrated = migrate_misplaced_transhuge_page(mm, vma, |
340ef390 | 1387 | pmdp, pmd, addr, page, target_nid); |
6688cc05 PZ |
1388 | if (migrated) { |
1389 | flags |= TNF_MIGRATED; | |
8191acbd | 1390 | page_nid = target_nid; |
074c2381 MG |
1391 | } else |
1392 | flags |= TNF_MIGRATE_FAIL; | |
b32967ff | 1393 | |
8191acbd | 1394 | goto out; |
b32967ff | 1395 | clear_pmdnuma: |
a54a407f | 1396 | BUG_ON(!PageLocked(page)); |
b191f9b1 | 1397 | was_writable = pmd_write(pmd); |
4d942466 | 1398 | pmd = pmd_modify(pmd, vma->vm_page_prot); |
b7b04004 | 1399 | pmd = pmd_mkyoung(pmd); |
b191f9b1 MG |
1400 | if (was_writable) |
1401 | pmd = pmd_mkwrite(pmd); | |
d10e63f2 | 1402 | set_pmd_at(mm, haddr, pmdp, pmd); |
d10e63f2 | 1403 | update_mmu_cache_pmd(vma, addr, pmdp); |
a54a407f | 1404 | unlock_page(page); |
d10e63f2 | 1405 | out_unlock: |
c4088ebd | 1406 | spin_unlock(ptl); |
b8916634 MG |
1407 | |
1408 | out: | |
1409 | if (anon_vma) | |
1410 | page_unlock_anon_vma_read(anon_vma); | |
1411 | ||
8191acbd | 1412 | if (page_nid != -1) |
6688cc05 | 1413 | task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags); |
8191acbd | 1414 | |
d10e63f2 MG |
1415 | return 0; |
1416 | } | |
1417 | ||
71e3aac0 | 1418 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
f21760b1 | 1419 | pmd_t *pmd, unsigned long addr) |
71e3aac0 | 1420 | { |
bf929152 | 1421 | spinlock_t *ptl; |
71e3aac0 AA |
1422 | int ret = 0; |
1423 | ||
bf929152 | 1424 | if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) { |
025c5b24 | 1425 | pgtable_t pgtable; |
f5c8ad47 | 1426 | pmd_t orig_pmd; |
a6bf2bb0 AK |
1427 | /* |
1428 | * For architectures like ppc64 we look at deposited pgtable | |
8809aa2d | 1429 | * when calling pmdp_huge_get_and_clear. So do the |
a6bf2bb0 AK |
1430 | * pgtable_trans_huge_withdraw after finishing pmdp related |
1431 | * operations. | |
1432 | */ | |
8809aa2d AK |
1433 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, |
1434 | tlb->fullmm); | |
025c5b24 | 1435 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); |
4897c765 MW |
1436 | if (vma_is_dax(vma)) { |
1437 | if (is_huge_zero_pmd(orig_pmd)) { | |
1438 | pgtable = NULL; | |
1439 | } else { | |
1440 | spin_unlock(ptl); | |
1441 | return 1; | |
1442 | } | |
1443 | } else { | |
1444 | pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd); | |
1445 | } | |
479f0abb | 1446 | if (is_huge_zero_pmd(orig_pmd)) { |
e1f56c89 | 1447 | atomic_long_dec(&tlb->mm->nr_ptes); |
bf929152 | 1448 | spin_unlock(ptl); |
97ae1749 | 1449 | put_huge_zero_page(); |
479f0abb | 1450 | } else { |
4897c765 | 1451 | struct page *page = pmd_page(orig_pmd); |
479f0abb | 1452 | page_remove_rmap(page); |
309381fe | 1453 | VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); |
479f0abb | 1454 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); |
309381fe | 1455 | VM_BUG_ON_PAGE(!PageHead(page), page); |
e1f56c89 | 1456 | atomic_long_dec(&tlb->mm->nr_ptes); |
bf929152 | 1457 | spin_unlock(ptl); |
479f0abb KS |
1458 | tlb_remove_page(tlb, page); |
1459 | } | |
4897c765 MW |
1460 | if (pgtable) |
1461 | pte_free(tlb->mm, pgtable); | |
025c5b24 NH |
1462 | ret = 1; |
1463 | } | |
71e3aac0 AA |
1464 | return ret; |
1465 | } | |
1466 | ||
37a1c49a AA |
1467 | int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, |
1468 | unsigned long old_addr, | |
1469 | unsigned long new_addr, unsigned long old_end, | |
1470 | pmd_t *old_pmd, pmd_t *new_pmd) | |
1471 | { | |
bf929152 | 1472 | spinlock_t *old_ptl, *new_ptl; |
37a1c49a AA |
1473 | int ret = 0; |
1474 | pmd_t pmd; | |
1475 | ||
1476 | struct mm_struct *mm = vma->vm_mm; | |
1477 | ||
1478 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1479 | (new_addr & ~HPAGE_PMD_MASK) || | |
1480 | old_end - old_addr < HPAGE_PMD_SIZE || | |
1481 | (new_vma->vm_flags & VM_NOHUGEPAGE)) | |
1482 | goto out; | |
1483 | ||
1484 | /* | |
1485 | * The destination pmd shouldn't be established, free_pgtables() | |
1486 | * should have release it. | |
1487 | */ | |
1488 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1489 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
1490 | goto out; | |
1491 | } | |
1492 | ||
bf929152 KS |
1493 | /* |
1494 | * We don't have to worry about the ordering of src and dst | |
1495 | * ptlocks because exclusive mmap_sem prevents deadlock. | |
1496 | */ | |
1497 | ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl); | |
025c5b24 | 1498 | if (ret == 1) { |
bf929152 KS |
1499 | new_ptl = pmd_lockptr(mm, new_pmd); |
1500 | if (new_ptl != old_ptl) | |
1501 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); | |
8809aa2d | 1502 | pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); |
025c5b24 | 1503 | VM_BUG_ON(!pmd_none(*new_pmd)); |
3592806c | 1504 | |
b3084f4d AK |
1505 | if (pmd_move_must_withdraw(new_ptl, old_ptl)) { |
1506 | pgtable_t pgtable; | |
3592806c KS |
1507 | pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); |
1508 | pgtable_trans_huge_deposit(mm, new_pmd, pgtable); | |
3592806c | 1509 | } |
b3084f4d AK |
1510 | set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); |
1511 | if (new_ptl != old_ptl) | |
1512 | spin_unlock(new_ptl); | |
bf929152 | 1513 | spin_unlock(old_ptl); |
37a1c49a AA |
1514 | } |
1515 | out: | |
1516 | return ret; | |
1517 | } | |
1518 | ||
f123d74a MG |
1519 | /* |
1520 | * Returns | |
1521 | * - 0 if PMD could not be locked | |
1522 | * - 1 if PMD was locked but protections unchange and TLB flush unnecessary | |
1523 | * - HPAGE_PMD_NR is protections changed and TLB flush necessary | |
1524 | */ | |
cd7548ab | 1525 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
e944fd67 | 1526 | unsigned long addr, pgprot_t newprot, int prot_numa) |
cd7548ab JW |
1527 | { |
1528 | struct mm_struct *mm = vma->vm_mm; | |
bf929152 | 1529 | spinlock_t *ptl; |
cd7548ab JW |
1530 | int ret = 0; |
1531 | ||
bf929152 | 1532 | if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) { |
025c5b24 | 1533 | pmd_t entry; |
b191f9b1 | 1534 | bool preserve_write = prot_numa && pmd_write(*pmd); |
ba68bc01 | 1535 | ret = 1; |
e944fd67 MG |
1536 | |
1537 | /* | |
1538 | * Avoid trapping faults against the zero page. The read-only | |
1539 | * data is likely to be read-cached on the local CPU and | |
1540 | * local/remote hits to the zero page are not interesting. | |
1541 | */ | |
1542 | if (prot_numa && is_huge_zero_pmd(*pmd)) { | |
1543 | spin_unlock(ptl); | |
ba68bc01 | 1544 | return ret; |
e944fd67 MG |
1545 | } |
1546 | ||
10c1045f | 1547 | if (!prot_numa || !pmd_protnone(*pmd)) { |
8809aa2d | 1548 | entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd); |
10c1045f | 1549 | entry = pmd_modify(entry, newprot); |
b191f9b1 MG |
1550 | if (preserve_write) |
1551 | entry = pmd_mkwrite(entry); | |
10c1045f MG |
1552 | ret = HPAGE_PMD_NR; |
1553 | set_pmd_at(mm, addr, pmd, entry); | |
b191f9b1 | 1554 | BUG_ON(!preserve_write && pmd_write(entry)); |
10c1045f | 1555 | } |
bf929152 | 1556 | spin_unlock(ptl); |
025c5b24 NH |
1557 | } |
1558 | ||
1559 | return ret; | |
1560 | } | |
1561 | ||
1562 | /* | |
1563 | * Returns 1 if a given pmd maps a stable (not under splitting) thp. | |
1564 | * Returns -1 if it maps a thp under splitting. Returns 0 otherwise. | |
1565 | * | |
1566 | * Note that if it returns 1, this routine returns without unlocking page | |
1567 | * table locks. So callers must unlock them. | |
1568 | */ | |
bf929152 KS |
1569 | int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma, |
1570 | spinlock_t **ptl) | |
025c5b24 | 1571 | { |
bf929152 | 1572 | *ptl = pmd_lock(vma->vm_mm, pmd); |
cd7548ab JW |
1573 | if (likely(pmd_trans_huge(*pmd))) { |
1574 | if (unlikely(pmd_trans_splitting(*pmd))) { | |
bf929152 | 1575 | spin_unlock(*ptl); |
cd7548ab | 1576 | wait_split_huge_page(vma->anon_vma, pmd); |
025c5b24 | 1577 | return -1; |
cd7548ab | 1578 | } else { |
025c5b24 NH |
1579 | /* Thp mapped by 'pmd' is stable, so we can |
1580 | * handle it as it is. */ | |
1581 | return 1; | |
cd7548ab | 1582 | } |
025c5b24 | 1583 | } |
bf929152 | 1584 | spin_unlock(*ptl); |
025c5b24 | 1585 | return 0; |
cd7548ab JW |
1586 | } |
1587 | ||
117b0791 KS |
1588 | /* |
1589 | * This function returns whether a given @page is mapped onto the @address | |
1590 | * in the virtual space of @mm. | |
1591 | * | |
1592 | * When it's true, this function returns *pmd with holding the page table lock | |
1593 | * and passing it back to the caller via @ptl. | |
1594 | * If it's false, returns NULL without holding the page table lock. | |
1595 | */ | |
71e3aac0 AA |
1596 | pmd_t *page_check_address_pmd(struct page *page, |
1597 | struct mm_struct *mm, | |
1598 | unsigned long address, | |
117b0791 KS |
1599 | enum page_check_address_pmd_flag flag, |
1600 | spinlock_t **ptl) | |
71e3aac0 | 1601 | { |
b5a8cad3 KS |
1602 | pgd_t *pgd; |
1603 | pud_t *pud; | |
117b0791 | 1604 | pmd_t *pmd; |
71e3aac0 AA |
1605 | |
1606 | if (address & ~HPAGE_PMD_MASK) | |
117b0791 | 1607 | return NULL; |
71e3aac0 | 1608 | |
b5a8cad3 KS |
1609 | pgd = pgd_offset(mm, address); |
1610 | if (!pgd_present(*pgd)) | |
117b0791 | 1611 | return NULL; |
b5a8cad3 KS |
1612 | pud = pud_offset(pgd, address); |
1613 | if (!pud_present(*pud)) | |
1614 | return NULL; | |
1615 | pmd = pmd_offset(pud, address); | |
1616 | ||
117b0791 | 1617 | *ptl = pmd_lock(mm, pmd); |
b5a8cad3 | 1618 | if (!pmd_present(*pmd)) |
117b0791 | 1619 | goto unlock; |
71e3aac0 | 1620 | if (pmd_page(*pmd) != page) |
117b0791 | 1621 | goto unlock; |
94fcc585 AA |
1622 | /* |
1623 | * split_vma() may create temporary aliased mappings. There is | |
1624 | * no risk as long as all huge pmd are found and have their | |
1625 | * splitting bit set before __split_huge_page_refcount | |
1626 | * runs. Finding the same huge pmd more than once during the | |
1627 | * same rmap walk is not a problem. | |
1628 | */ | |
1629 | if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG && | |
1630 | pmd_trans_splitting(*pmd)) | |
117b0791 | 1631 | goto unlock; |
71e3aac0 AA |
1632 | if (pmd_trans_huge(*pmd)) { |
1633 | VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG && | |
1634 | !pmd_trans_splitting(*pmd)); | |
117b0791 | 1635 | return pmd; |
71e3aac0 | 1636 | } |
117b0791 KS |
1637 | unlock: |
1638 | spin_unlock(*ptl); | |
1639 | return NULL; | |
71e3aac0 AA |
1640 | } |
1641 | ||
1642 | static int __split_huge_page_splitting(struct page *page, | |
1643 | struct vm_area_struct *vma, | |
1644 | unsigned long address) | |
1645 | { | |
1646 | struct mm_struct *mm = vma->vm_mm; | |
117b0791 | 1647 | spinlock_t *ptl; |
71e3aac0 AA |
1648 | pmd_t *pmd; |
1649 | int ret = 0; | |
2ec74c3e SG |
1650 | /* For mmu_notifiers */ |
1651 | const unsigned long mmun_start = address; | |
1652 | const unsigned long mmun_end = address + HPAGE_PMD_SIZE; | |
71e3aac0 | 1653 | |
2ec74c3e | 1654 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
71e3aac0 | 1655 | pmd = page_check_address_pmd(page, mm, address, |
117b0791 | 1656 | PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl); |
71e3aac0 AA |
1657 | if (pmd) { |
1658 | /* | |
1659 | * We can't temporarily set the pmd to null in order | |
1660 | * to split it, the pmd must remain marked huge at all | |
1661 | * times or the VM won't take the pmd_trans_huge paths | |
5a505085 | 1662 | * and it won't wait on the anon_vma->root->rwsem to |
71e3aac0 AA |
1663 | * serialize against split_huge_page*. |
1664 | */ | |
2ec74c3e | 1665 | pmdp_splitting_flush(vma, address, pmd); |
34ee645e | 1666 | |
71e3aac0 | 1667 | ret = 1; |
117b0791 | 1668 | spin_unlock(ptl); |
71e3aac0 | 1669 | } |
2ec74c3e | 1670 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
71e3aac0 AA |
1671 | |
1672 | return ret; | |
1673 | } | |
1674 | ||
5bc7b8ac SL |
1675 | static void __split_huge_page_refcount(struct page *page, |
1676 | struct list_head *list) | |
71e3aac0 AA |
1677 | { |
1678 | int i; | |
71e3aac0 | 1679 | struct zone *zone = page_zone(page); |
fa9add64 | 1680 | struct lruvec *lruvec; |
70b50f94 | 1681 | int tail_count = 0; |
71e3aac0 AA |
1682 | |
1683 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
1684 | spin_lock_irq(&zone->lru_lock); | |
fa9add64 HD |
1685 | lruvec = mem_cgroup_page_lruvec(page, zone); |
1686 | ||
71e3aac0 | 1687 | compound_lock(page); |
e94c8a9c KH |
1688 | /* complete memcg works before add pages to LRU */ |
1689 | mem_cgroup_split_huge_fixup(page); | |
71e3aac0 | 1690 | |
45676885 | 1691 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { |
71e3aac0 AA |
1692 | struct page *page_tail = page + i; |
1693 | ||
70b50f94 AA |
1694 | /* tail_page->_mapcount cannot change */ |
1695 | BUG_ON(page_mapcount(page_tail) < 0); | |
1696 | tail_count += page_mapcount(page_tail); | |
1697 | /* check for overflow */ | |
1698 | BUG_ON(tail_count < 0); | |
1699 | BUG_ON(atomic_read(&page_tail->_count) != 0); | |
1700 | /* | |
1701 | * tail_page->_count is zero and not changing from | |
1702 | * under us. But get_page_unless_zero() may be running | |
1703 | * from under us on the tail_page. If we used | |
1704 | * atomic_set() below instead of atomic_add(), we | |
1705 | * would then run atomic_set() concurrently with | |
1706 | * get_page_unless_zero(), and atomic_set() is | |
1707 | * implemented in C not using locked ops. spin_unlock | |
1708 | * on x86 sometime uses locked ops because of PPro | |
1709 | * errata 66, 92, so unless somebody can guarantee | |
1710 | * atomic_set() here would be safe on all archs (and | |
1711 | * not only on x86), it's safer to use atomic_add(). | |
1712 | */ | |
1713 | atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1, | |
1714 | &page_tail->_count); | |
71e3aac0 AA |
1715 | |
1716 | /* after clearing PageTail the gup refcount can be released */ | |
3a79d52a | 1717 | smp_mb__after_atomic(); |
71e3aac0 | 1718 | |
f4c18e6f | 1719 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; |
71e3aac0 AA |
1720 | page_tail->flags |= (page->flags & |
1721 | ((1L << PG_referenced) | | |
1722 | (1L << PG_swapbacked) | | |
1723 | (1L << PG_mlocked) | | |
e180cf80 KS |
1724 | (1L << PG_uptodate) | |
1725 | (1L << PG_active) | | |
1726 | (1L << PG_unevictable))); | |
71e3aac0 AA |
1727 | page_tail->flags |= (1L << PG_dirty); |
1728 | ||
70b50f94 | 1729 | /* clear PageTail before overwriting first_page */ |
71e3aac0 AA |
1730 | smp_wmb(); |
1731 | ||
1732 | /* | |
1733 | * __split_huge_page_splitting() already set the | |
1734 | * splitting bit in all pmd that could map this | |
1735 | * hugepage, that will ensure no CPU can alter the | |
1736 | * mapcount on the head page. The mapcount is only | |
1737 | * accounted in the head page and it has to be | |
1738 | * transferred to all tail pages in the below code. So | |
1739 | * for this code to be safe, the split the mapcount | |
1740 | * can't change. But that doesn't mean userland can't | |
1741 | * keep changing and reading the page contents while | |
1742 | * we transfer the mapcount, so the pmd splitting | |
1743 | * status is achieved setting a reserved bit in the | |
1744 | * pmd, not by clearing the present bit. | |
1745 | */ | |
71e3aac0 AA |
1746 | page_tail->_mapcount = page->_mapcount; |
1747 | ||
1748 | BUG_ON(page_tail->mapping); | |
1749 | page_tail->mapping = page->mapping; | |
1750 | ||
45676885 | 1751 | page_tail->index = page->index + i; |
90572890 | 1752 | page_cpupid_xchg_last(page_tail, page_cpupid_last(page)); |
71e3aac0 AA |
1753 | |
1754 | BUG_ON(!PageAnon(page_tail)); | |
1755 | BUG_ON(!PageUptodate(page_tail)); | |
1756 | BUG_ON(!PageDirty(page_tail)); | |
1757 | BUG_ON(!PageSwapBacked(page_tail)); | |
1758 | ||
5bc7b8ac | 1759 | lru_add_page_tail(page, page_tail, lruvec, list); |
71e3aac0 | 1760 | } |
70b50f94 AA |
1761 | atomic_sub(tail_count, &page->_count); |
1762 | BUG_ON(atomic_read(&page->_count) <= 0); | |
71e3aac0 | 1763 | |
fa9add64 | 1764 | __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1); |
79134171 | 1765 | |
71e3aac0 AA |
1766 | ClearPageCompound(page); |
1767 | compound_unlock(page); | |
1768 | spin_unlock_irq(&zone->lru_lock); | |
1769 | ||
1770 | for (i = 1; i < HPAGE_PMD_NR; i++) { | |
1771 | struct page *page_tail = page + i; | |
1772 | BUG_ON(page_count(page_tail) <= 0); | |
1773 | /* | |
1774 | * Tail pages may be freed if there wasn't any mapping | |
1775 | * like if add_to_swap() is running on a lru page that | |
1776 | * had its mapping zapped. And freeing these pages | |
1777 | * requires taking the lru_lock so we do the put_page | |
1778 | * of the tail pages after the split is complete. | |
1779 | */ | |
1780 | put_page(page_tail); | |
1781 | } | |
1782 | ||
1783 | /* | |
1784 | * Only the head page (now become a regular page) is required | |
1785 | * to be pinned by the caller. | |
1786 | */ | |
1787 | BUG_ON(page_count(page) <= 0); | |
1788 | } | |
1789 | ||
1790 | static int __split_huge_page_map(struct page *page, | |
1791 | struct vm_area_struct *vma, | |
1792 | unsigned long address) | |
1793 | { | |
1794 | struct mm_struct *mm = vma->vm_mm; | |
117b0791 | 1795 | spinlock_t *ptl; |
71e3aac0 AA |
1796 | pmd_t *pmd, _pmd; |
1797 | int ret = 0, i; | |
1798 | pgtable_t pgtable; | |
1799 | unsigned long haddr; | |
1800 | ||
71e3aac0 | 1801 | pmd = page_check_address_pmd(page, mm, address, |
117b0791 | 1802 | PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl); |
71e3aac0 | 1803 | if (pmd) { |
6b0b50b0 | 1804 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
71e3aac0 | 1805 | pmd_populate(mm, &_pmd, pgtable); |
f8303c25 WL |
1806 | if (pmd_write(*pmd)) |
1807 | BUG_ON(page_mapcount(page) != 1); | |
71e3aac0 | 1808 | |
e3ebcf64 GS |
1809 | haddr = address; |
1810 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
71e3aac0 AA |
1811 | pte_t *pte, entry; |
1812 | BUG_ON(PageCompound(page+i)); | |
abc40bd2 | 1813 | /* |
8a0516ed MG |
1814 | * Note that NUMA hinting access restrictions are not |
1815 | * transferred to avoid any possibility of altering | |
1816 | * permissions across VMAs. | |
abc40bd2 | 1817 | */ |
71e3aac0 AA |
1818 | entry = mk_pte(page + i, vma->vm_page_prot); |
1819 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
1820 | if (!pmd_write(*pmd)) | |
1821 | entry = pte_wrprotect(entry); | |
71e3aac0 AA |
1822 | if (!pmd_young(*pmd)) |
1823 | entry = pte_mkold(entry); | |
1824 | pte = pte_offset_map(&_pmd, haddr); | |
1825 | BUG_ON(!pte_none(*pte)); | |
1826 | set_pte_at(mm, haddr, pte, entry); | |
1827 | pte_unmap(pte); | |
1828 | } | |
1829 | ||
71e3aac0 AA |
1830 | smp_wmb(); /* make pte visible before pmd */ |
1831 | /* | |
1832 | * Up to this point the pmd is present and huge and | |
1833 | * userland has the whole access to the hugepage | |
1834 | * during the split (which happens in place). If we | |
1835 | * overwrite the pmd with the not-huge version | |
1836 | * pointing to the pte here (which of course we could | |
1837 | * if all CPUs were bug free), userland could trigger | |
1838 | * a small page size TLB miss on the small sized TLB | |
1839 | * while the hugepage TLB entry is still established | |
1840 | * in the huge TLB. Some CPU doesn't like that. See | |
1841 | * http://support.amd.com/us/Processor_TechDocs/41322.pdf, | |
1842 | * Erratum 383 on page 93. Intel should be safe but is | |
1843 | * also warns that it's only safe if the permission | |
1844 | * and cache attributes of the two entries loaded in | |
1845 | * the two TLB is identical (which should be the case | |
1846 | * here). But it is generally safer to never allow | |
1847 | * small and huge TLB entries for the same virtual | |
1848 | * address to be loaded simultaneously. So instead of | |
1849 | * doing "pmd_populate(); flush_tlb_range();" we first | |
1850 | * mark the current pmd notpresent (atomically because | |
1851 | * here the pmd_trans_huge and pmd_trans_splitting | |
1852 | * must remain set at all times on the pmd until the | |
1853 | * split is complete for this pmd), then we flush the | |
1854 | * SMP TLB and finally we write the non-huge version | |
1855 | * of the pmd entry with pmd_populate. | |
1856 | */ | |
46dcde73 | 1857 | pmdp_invalidate(vma, address, pmd); |
71e3aac0 AA |
1858 | pmd_populate(mm, pmd, pgtable); |
1859 | ret = 1; | |
117b0791 | 1860 | spin_unlock(ptl); |
71e3aac0 | 1861 | } |
71e3aac0 AA |
1862 | |
1863 | return ret; | |
1864 | } | |
1865 | ||
5a505085 | 1866 | /* must be called with anon_vma->root->rwsem held */ |
71e3aac0 | 1867 | static void __split_huge_page(struct page *page, |
5bc7b8ac SL |
1868 | struct anon_vma *anon_vma, |
1869 | struct list_head *list) | |
71e3aac0 AA |
1870 | { |
1871 | int mapcount, mapcount2; | |
bf181b9f | 1872 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
71e3aac0 AA |
1873 | struct anon_vma_chain *avc; |
1874 | ||
1875 | BUG_ON(!PageHead(page)); | |
1876 | BUG_ON(PageTail(page)); | |
1877 | ||
1878 | mapcount = 0; | |
bf181b9f | 1879 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { |
71e3aac0 AA |
1880 | struct vm_area_struct *vma = avc->vma; |
1881 | unsigned long addr = vma_address(page, vma); | |
1882 | BUG_ON(is_vma_temporary_stack(vma)); | |
71e3aac0 AA |
1883 | mapcount += __split_huge_page_splitting(page, vma, addr); |
1884 | } | |
05759d38 AA |
1885 | /* |
1886 | * It is critical that new vmas are added to the tail of the | |
1887 | * anon_vma list. This guarantes that if copy_huge_pmd() runs | |
1888 | * and establishes a child pmd before | |
1889 | * __split_huge_page_splitting() freezes the parent pmd (so if | |
1890 | * we fail to prevent copy_huge_pmd() from running until the | |
1891 | * whole __split_huge_page() is complete), we will still see | |
1892 | * the newly established pmd of the child later during the | |
1893 | * walk, to be able to set it as pmd_trans_splitting too. | |
1894 | */ | |
ff9e43eb | 1895 | if (mapcount != page_mapcount(page)) { |
ae3a8c1c AM |
1896 | pr_err("mapcount %d page_mapcount %d\n", |
1897 | mapcount, page_mapcount(page)); | |
ff9e43eb KS |
1898 | BUG(); |
1899 | } | |
71e3aac0 | 1900 | |
5bc7b8ac | 1901 | __split_huge_page_refcount(page, list); |
71e3aac0 AA |
1902 | |
1903 | mapcount2 = 0; | |
bf181b9f | 1904 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { |
71e3aac0 AA |
1905 | struct vm_area_struct *vma = avc->vma; |
1906 | unsigned long addr = vma_address(page, vma); | |
1907 | BUG_ON(is_vma_temporary_stack(vma)); | |
71e3aac0 AA |
1908 | mapcount2 += __split_huge_page_map(page, vma, addr); |
1909 | } | |
ff9e43eb | 1910 | if (mapcount != mapcount2) { |
ae3a8c1c AM |
1911 | pr_err("mapcount %d mapcount2 %d page_mapcount %d\n", |
1912 | mapcount, mapcount2, page_mapcount(page)); | |
ff9e43eb KS |
1913 | BUG(); |
1914 | } | |
71e3aac0 AA |
1915 | } |
1916 | ||
5bc7b8ac SL |
1917 | /* |
1918 | * Split a hugepage into normal pages. This doesn't change the position of head | |
1919 | * page. If @list is null, tail pages will be added to LRU list, otherwise, to | |
1920 | * @list. Both head page and tail pages will inherit mapping, flags, and so on | |
1921 | * from the hugepage. | |
1922 | * Return 0 if the hugepage is split successfully otherwise return 1. | |
1923 | */ | |
1924 | int split_huge_page_to_list(struct page *page, struct list_head *list) | |
71e3aac0 AA |
1925 | { |
1926 | struct anon_vma *anon_vma; | |
1927 | int ret = 1; | |
1928 | ||
5918d10a | 1929 | BUG_ON(is_huge_zero_page(page)); |
71e3aac0 | 1930 | BUG_ON(!PageAnon(page)); |
062f1af2 MG |
1931 | |
1932 | /* | |
1933 | * The caller does not necessarily hold an mmap_sem that would prevent | |
1934 | * the anon_vma disappearing so we first we take a reference to it | |
1935 | * and then lock the anon_vma for write. This is similar to | |
1936 | * page_lock_anon_vma_read except the write lock is taken to serialise | |
1937 | * against parallel split or collapse operations. | |
1938 | */ | |
1939 | anon_vma = page_get_anon_vma(page); | |
71e3aac0 AA |
1940 | if (!anon_vma) |
1941 | goto out; | |
062f1af2 MG |
1942 | anon_vma_lock_write(anon_vma); |
1943 | ||
71e3aac0 AA |
1944 | ret = 0; |
1945 | if (!PageCompound(page)) | |
1946 | goto out_unlock; | |
1947 | ||
1948 | BUG_ON(!PageSwapBacked(page)); | |
5bc7b8ac | 1949 | __split_huge_page(page, anon_vma, list); |
81ab4201 | 1950 | count_vm_event(THP_SPLIT); |
71e3aac0 AA |
1951 | |
1952 | BUG_ON(PageCompound(page)); | |
1953 | out_unlock: | |
08b52706 | 1954 | anon_vma_unlock_write(anon_vma); |
062f1af2 | 1955 | put_anon_vma(anon_vma); |
71e3aac0 AA |
1956 | out: |
1957 | return ret; | |
1958 | } | |
1959 | ||
9050d7eb | 1960 | #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE) |
78f11a25 | 1961 | |
60ab3244 AA |
1962 | int hugepage_madvise(struct vm_area_struct *vma, |
1963 | unsigned long *vm_flags, int advice) | |
0af4e98b | 1964 | { |
a664b2d8 AA |
1965 | switch (advice) { |
1966 | case MADV_HUGEPAGE: | |
1e1836e8 AT |
1967 | #ifdef CONFIG_S390 |
1968 | /* | |
1969 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
1970 | * can't handle this properly after s390_enable_sie, so we simply | |
1971 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
1972 | */ | |
1973 | if (mm_has_pgste(vma->vm_mm)) | |
1974 | return 0; | |
1975 | #endif | |
a664b2d8 AA |
1976 | /* |
1977 | * Be somewhat over-protective like KSM for now! | |
1978 | */ | |
78f11a25 | 1979 | if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP)) |
a664b2d8 AA |
1980 | return -EINVAL; |
1981 | *vm_flags &= ~VM_NOHUGEPAGE; | |
1982 | *vm_flags |= VM_HUGEPAGE; | |
60ab3244 AA |
1983 | /* |
1984 | * If the vma become good for khugepaged to scan, | |
1985 | * register it here without waiting a page fault that | |
1986 | * may not happen any time soon. | |
1987 | */ | |
6d50e60c | 1988 | if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags))) |
60ab3244 | 1989 | return -ENOMEM; |
a664b2d8 AA |
1990 | break; |
1991 | case MADV_NOHUGEPAGE: | |
1992 | /* | |
1993 | * Be somewhat over-protective like KSM for now! | |
1994 | */ | |
78f11a25 | 1995 | if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP)) |
a664b2d8 AA |
1996 | return -EINVAL; |
1997 | *vm_flags &= ~VM_HUGEPAGE; | |
1998 | *vm_flags |= VM_NOHUGEPAGE; | |
60ab3244 AA |
1999 | /* |
2000 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
2001 | * this vma even if we leave the mm registered in khugepaged if | |
2002 | * it got registered before VM_NOHUGEPAGE was set. | |
2003 | */ | |
a664b2d8 AA |
2004 | break; |
2005 | } | |
0af4e98b AA |
2006 | |
2007 | return 0; | |
2008 | } | |
2009 | ||
ba76149f AA |
2010 | static int __init khugepaged_slab_init(void) |
2011 | { | |
2012 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
2013 | sizeof(struct mm_slot), | |
2014 | __alignof__(struct mm_slot), 0, NULL); | |
2015 | if (!mm_slot_cache) | |
2016 | return -ENOMEM; | |
2017 | ||
2018 | return 0; | |
2019 | } | |
2020 | ||
65ebb64f KS |
2021 | static void __init khugepaged_slab_exit(void) |
2022 | { | |
2023 | kmem_cache_destroy(mm_slot_cache); | |
2024 | } | |
2025 | ||
ba76149f AA |
2026 | static inline struct mm_slot *alloc_mm_slot(void) |
2027 | { | |
2028 | if (!mm_slot_cache) /* initialization failed */ | |
2029 | return NULL; | |
2030 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
2031 | } | |
2032 | ||
2033 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
2034 | { | |
2035 | kmem_cache_free(mm_slot_cache, mm_slot); | |
2036 | } | |
2037 | ||
ba76149f AA |
2038 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) |
2039 | { | |
2040 | struct mm_slot *mm_slot; | |
ba76149f | 2041 | |
b67bfe0d | 2042 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) |
ba76149f AA |
2043 | if (mm == mm_slot->mm) |
2044 | return mm_slot; | |
43b5fbbd | 2045 | |
ba76149f AA |
2046 | return NULL; |
2047 | } | |
2048 | ||
2049 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
2050 | struct mm_slot *mm_slot) | |
2051 | { | |
ba76149f | 2052 | mm_slot->mm = mm; |
43b5fbbd | 2053 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); |
ba76149f AA |
2054 | } |
2055 | ||
2056 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
2057 | { | |
2058 | return atomic_read(&mm->mm_users) == 0; | |
2059 | } | |
2060 | ||
2061 | int __khugepaged_enter(struct mm_struct *mm) | |
2062 | { | |
2063 | struct mm_slot *mm_slot; | |
2064 | int wakeup; | |
2065 | ||
2066 | mm_slot = alloc_mm_slot(); | |
2067 | if (!mm_slot) | |
2068 | return -ENOMEM; | |
2069 | ||
2070 | /* __khugepaged_exit() must not run from under us */ | |
96dad67f | 2071 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); |
ba76149f AA |
2072 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { |
2073 | free_mm_slot(mm_slot); | |
2074 | return 0; | |
2075 | } | |
2076 | ||
2077 | spin_lock(&khugepaged_mm_lock); | |
2078 | insert_to_mm_slots_hash(mm, mm_slot); | |
2079 | /* | |
2080 | * Insert just behind the scanning cursor, to let the area settle | |
2081 | * down a little. | |
2082 | */ | |
2083 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
2084 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
2085 | spin_unlock(&khugepaged_mm_lock); | |
2086 | ||
2087 | atomic_inc(&mm->mm_count); | |
2088 | if (wakeup) | |
2089 | wake_up_interruptible(&khugepaged_wait); | |
2090 | ||
2091 | return 0; | |
2092 | } | |
2093 | ||
6d50e60c DR |
2094 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, |
2095 | unsigned long vm_flags) | |
ba76149f AA |
2096 | { |
2097 | unsigned long hstart, hend; | |
2098 | if (!vma->anon_vma) | |
2099 | /* | |
2100 | * Not yet faulted in so we will register later in the | |
2101 | * page fault if needed. | |
2102 | */ | |
2103 | return 0; | |
78f11a25 | 2104 | if (vma->vm_ops) |
ba76149f AA |
2105 | /* khugepaged not yet working on file or special mappings */ |
2106 | return 0; | |
6d50e60c | 2107 | VM_BUG_ON_VMA(vm_flags & VM_NO_THP, vma); |
ba76149f AA |
2108 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2109 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2110 | if (hstart < hend) | |
6d50e60c | 2111 | return khugepaged_enter(vma, vm_flags); |
ba76149f AA |
2112 | return 0; |
2113 | } | |
2114 | ||
2115 | void __khugepaged_exit(struct mm_struct *mm) | |
2116 | { | |
2117 | struct mm_slot *mm_slot; | |
2118 | int free = 0; | |
2119 | ||
2120 | spin_lock(&khugepaged_mm_lock); | |
2121 | mm_slot = get_mm_slot(mm); | |
2122 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
43b5fbbd | 2123 | hash_del(&mm_slot->hash); |
ba76149f AA |
2124 | list_del(&mm_slot->mm_node); |
2125 | free = 1; | |
2126 | } | |
d788e80a | 2127 | spin_unlock(&khugepaged_mm_lock); |
ba76149f AA |
2128 | |
2129 | if (free) { | |
ba76149f AA |
2130 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); |
2131 | free_mm_slot(mm_slot); | |
2132 | mmdrop(mm); | |
2133 | } else if (mm_slot) { | |
ba76149f AA |
2134 | /* |
2135 | * This is required to serialize against | |
2136 | * khugepaged_test_exit() (which is guaranteed to run | |
2137 | * under mmap sem read mode). Stop here (after we | |
2138 | * return all pagetables will be destroyed) until | |
2139 | * khugepaged has finished working on the pagetables | |
2140 | * under the mmap_sem. | |
2141 | */ | |
2142 | down_write(&mm->mmap_sem); | |
2143 | up_write(&mm->mmap_sem); | |
d788e80a | 2144 | } |
ba76149f AA |
2145 | } |
2146 | ||
2147 | static void release_pte_page(struct page *page) | |
2148 | { | |
2149 | /* 0 stands for page_is_file_cache(page) == false */ | |
2150 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
2151 | unlock_page(page); | |
2152 | putback_lru_page(page); | |
2153 | } | |
2154 | ||
2155 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
2156 | { | |
2157 | while (--_pte >= pte) { | |
2158 | pte_t pteval = *_pte; | |
ca0984ca | 2159 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) |
ba76149f AA |
2160 | release_pte_page(pte_page(pteval)); |
2161 | } | |
2162 | } | |
2163 | ||
ba76149f AA |
2164 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, |
2165 | unsigned long address, | |
2166 | pte_t *pte) | |
2167 | { | |
2168 | struct page *page; | |
2169 | pte_t *_pte; | |
ca0984ca | 2170 | int none_or_zero = 0; |
10359213 | 2171 | bool referenced = false, writable = false; |
ba76149f AA |
2172 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; |
2173 | _pte++, address += PAGE_SIZE) { | |
2174 | pte_t pteval = *_pte; | |
ca0984ca | 2175 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
c1294d05 AA |
2176 | if (!userfaultfd_armed(vma) && |
2177 | ++none_or_zero <= khugepaged_max_ptes_none) | |
ba76149f | 2178 | continue; |
344aa35c | 2179 | else |
ba76149f | 2180 | goto out; |
ba76149f | 2181 | } |
10359213 | 2182 | if (!pte_present(pteval)) |
ba76149f | 2183 | goto out; |
ba76149f | 2184 | page = vm_normal_page(vma, address, pteval); |
344aa35c | 2185 | if (unlikely(!page)) |
ba76149f | 2186 | goto out; |
344aa35c | 2187 | |
309381fe SL |
2188 | VM_BUG_ON_PAGE(PageCompound(page), page); |
2189 | VM_BUG_ON_PAGE(!PageAnon(page), page); | |
2190 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
ba76149f | 2191 | |
ba76149f AA |
2192 | /* |
2193 | * We can do it before isolate_lru_page because the | |
2194 | * page can't be freed from under us. NOTE: PG_lock | |
2195 | * is needed to serialize against split_huge_page | |
2196 | * when invoked from the VM. | |
2197 | */ | |
344aa35c | 2198 | if (!trylock_page(page)) |
ba76149f | 2199 | goto out; |
10359213 EA |
2200 | |
2201 | /* | |
2202 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2203 | * The page must only be referenced by the scanned process | |
2204 | * and page swap cache. | |
2205 | */ | |
2206 | if (page_count(page) != 1 + !!PageSwapCache(page)) { | |
2207 | unlock_page(page); | |
2208 | goto out; | |
2209 | } | |
2210 | if (pte_write(pteval)) { | |
2211 | writable = true; | |
2212 | } else { | |
2213 | if (PageSwapCache(page) && !reuse_swap_page(page)) { | |
2214 | unlock_page(page); | |
2215 | goto out; | |
2216 | } | |
2217 | /* | |
2218 | * Page is not in the swap cache. It can be collapsed | |
2219 | * into a THP. | |
2220 | */ | |
2221 | } | |
2222 | ||
ba76149f AA |
2223 | /* |
2224 | * Isolate the page to avoid collapsing an hugepage | |
2225 | * currently in use by the VM. | |
2226 | */ | |
2227 | if (isolate_lru_page(page)) { | |
2228 | unlock_page(page); | |
ba76149f AA |
2229 | goto out; |
2230 | } | |
2231 | /* 0 stands for page_is_file_cache(page) == false */ | |
2232 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
309381fe SL |
2233 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
2234 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
ba76149f AA |
2235 | |
2236 | /* If there is no mapped pte young don't collapse the page */ | |
8ee53820 AA |
2237 | if (pte_young(pteval) || PageReferenced(page) || |
2238 | mmu_notifier_test_young(vma->vm_mm, address)) | |
10359213 | 2239 | referenced = true; |
ba76149f | 2240 | } |
10359213 | 2241 | if (likely(referenced && writable)) |
344aa35c | 2242 | return 1; |
ba76149f | 2243 | out: |
344aa35c BL |
2244 | release_pte_pages(pte, _pte); |
2245 | return 0; | |
ba76149f AA |
2246 | } |
2247 | ||
2248 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
2249 | struct vm_area_struct *vma, | |
2250 | unsigned long address, | |
2251 | spinlock_t *ptl) | |
2252 | { | |
2253 | pte_t *_pte; | |
2254 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { | |
2255 | pte_t pteval = *_pte; | |
2256 | struct page *src_page; | |
2257 | ||
ca0984ca | 2258 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
ba76149f AA |
2259 | clear_user_highpage(page, address); |
2260 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
ca0984ca EA |
2261 | if (is_zero_pfn(pte_pfn(pteval))) { |
2262 | /* | |
2263 | * ptl mostly unnecessary. | |
2264 | */ | |
2265 | spin_lock(ptl); | |
2266 | /* | |
2267 | * paravirt calls inside pte_clear here are | |
2268 | * superfluous. | |
2269 | */ | |
2270 | pte_clear(vma->vm_mm, address, _pte); | |
2271 | spin_unlock(ptl); | |
2272 | } | |
ba76149f AA |
2273 | } else { |
2274 | src_page = pte_page(pteval); | |
2275 | copy_user_highpage(page, src_page, address, vma); | |
309381fe | 2276 | VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page); |
ba76149f AA |
2277 | release_pte_page(src_page); |
2278 | /* | |
2279 | * ptl mostly unnecessary, but preempt has to | |
2280 | * be disabled to update the per-cpu stats | |
2281 | * inside page_remove_rmap(). | |
2282 | */ | |
2283 | spin_lock(ptl); | |
2284 | /* | |
2285 | * paravirt calls inside pte_clear here are | |
2286 | * superfluous. | |
2287 | */ | |
2288 | pte_clear(vma->vm_mm, address, _pte); | |
2289 | page_remove_rmap(src_page); | |
2290 | spin_unlock(ptl); | |
2291 | free_page_and_swap_cache(src_page); | |
2292 | } | |
2293 | ||
2294 | address += PAGE_SIZE; | |
2295 | page++; | |
2296 | } | |
2297 | } | |
2298 | ||
26234f36 | 2299 | static void khugepaged_alloc_sleep(void) |
ba76149f | 2300 | { |
26234f36 XG |
2301 | wait_event_freezable_timeout(khugepaged_wait, false, |
2302 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
2303 | } | |
ba76149f | 2304 | |
9f1b868a BL |
2305 | static int khugepaged_node_load[MAX_NUMNODES]; |
2306 | ||
14a4e214 DR |
2307 | static bool khugepaged_scan_abort(int nid) |
2308 | { | |
2309 | int i; | |
2310 | ||
2311 | /* | |
2312 | * If zone_reclaim_mode is disabled, then no extra effort is made to | |
2313 | * allocate memory locally. | |
2314 | */ | |
2315 | if (!zone_reclaim_mode) | |
2316 | return false; | |
2317 | ||
2318 | /* If there is a count for this node already, it must be acceptable */ | |
2319 | if (khugepaged_node_load[nid]) | |
2320 | return false; | |
2321 | ||
2322 | for (i = 0; i < MAX_NUMNODES; i++) { | |
2323 | if (!khugepaged_node_load[i]) | |
2324 | continue; | |
2325 | if (node_distance(nid, i) > RECLAIM_DISTANCE) | |
2326 | return true; | |
2327 | } | |
2328 | return false; | |
2329 | } | |
2330 | ||
26234f36 | 2331 | #ifdef CONFIG_NUMA |
9f1b868a BL |
2332 | static int khugepaged_find_target_node(void) |
2333 | { | |
2334 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
2335 | int nid, target_node = 0, max_value = 0; | |
2336 | ||
2337 | /* find first node with max normal pages hit */ | |
2338 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
2339 | if (khugepaged_node_load[nid] > max_value) { | |
2340 | max_value = khugepaged_node_load[nid]; | |
2341 | target_node = nid; | |
2342 | } | |
2343 | ||
2344 | /* do some balance if several nodes have the same hit record */ | |
2345 | if (target_node <= last_khugepaged_target_node) | |
2346 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
2347 | nid++) | |
2348 | if (max_value == khugepaged_node_load[nid]) { | |
2349 | target_node = nid; | |
2350 | break; | |
2351 | } | |
2352 | ||
2353 | last_khugepaged_target_node = target_node; | |
2354 | return target_node; | |
2355 | } | |
2356 | ||
26234f36 XG |
2357 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) |
2358 | { | |
2359 | if (IS_ERR(*hpage)) { | |
2360 | if (!*wait) | |
2361 | return false; | |
2362 | ||
2363 | *wait = false; | |
e3b4126c | 2364 | *hpage = NULL; |
26234f36 XG |
2365 | khugepaged_alloc_sleep(); |
2366 | } else if (*hpage) { | |
2367 | put_page(*hpage); | |
2368 | *hpage = NULL; | |
2369 | } | |
2370 | ||
2371 | return true; | |
2372 | } | |
2373 | ||
3b363692 MH |
2374 | static struct page * |
2375 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
26234f36 XG |
2376 | struct vm_area_struct *vma, unsigned long address, |
2377 | int node) | |
2378 | { | |
309381fe | 2379 | VM_BUG_ON_PAGE(*hpage, *hpage); |
8b164568 | 2380 | |
ce83d217 | 2381 | /* |
8b164568 VB |
2382 | * Before allocating the hugepage, release the mmap_sem read lock. |
2383 | * The allocation can take potentially a long time if it involves | |
2384 | * sync compaction, and we do not need to hold the mmap_sem during | |
2385 | * that. We will recheck the vma after taking it again in write mode. | |
ce83d217 | 2386 | */ |
8b164568 VB |
2387 | up_read(&mm->mmap_sem); |
2388 | ||
3b363692 | 2389 | *hpage = alloc_pages_exact_node(node, gfp, HPAGE_PMD_ORDER); |
26234f36 | 2390 | if (unlikely(!*hpage)) { |
81ab4201 | 2391 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); |
ce83d217 | 2392 | *hpage = ERR_PTR(-ENOMEM); |
26234f36 | 2393 | return NULL; |
ce83d217 | 2394 | } |
26234f36 | 2395 | |
65b3c07b | 2396 | count_vm_event(THP_COLLAPSE_ALLOC); |
26234f36 XG |
2397 | return *hpage; |
2398 | } | |
2399 | #else | |
9f1b868a BL |
2400 | static int khugepaged_find_target_node(void) |
2401 | { | |
2402 | return 0; | |
2403 | } | |
2404 | ||
10dc4155 BL |
2405 | static inline struct page *alloc_hugepage(int defrag) |
2406 | { | |
2407 | return alloc_pages(alloc_hugepage_gfpmask(defrag, 0), | |
2408 | HPAGE_PMD_ORDER); | |
2409 | } | |
2410 | ||
26234f36 XG |
2411 | static struct page *khugepaged_alloc_hugepage(bool *wait) |
2412 | { | |
2413 | struct page *hpage; | |
2414 | ||
2415 | do { | |
2416 | hpage = alloc_hugepage(khugepaged_defrag()); | |
2417 | if (!hpage) { | |
2418 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
2419 | if (!*wait) | |
2420 | return NULL; | |
2421 | ||
2422 | *wait = false; | |
2423 | khugepaged_alloc_sleep(); | |
2424 | } else | |
2425 | count_vm_event(THP_COLLAPSE_ALLOC); | |
2426 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
2427 | ||
2428 | return hpage; | |
2429 | } | |
2430 | ||
2431 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
2432 | { | |
2433 | if (!*hpage) | |
2434 | *hpage = khugepaged_alloc_hugepage(wait); | |
2435 | ||
2436 | if (unlikely(!*hpage)) | |
2437 | return false; | |
2438 | ||
2439 | return true; | |
2440 | } | |
2441 | ||
3b363692 MH |
2442 | static struct page * |
2443 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
26234f36 XG |
2444 | struct vm_area_struct *vma, unsigned long address, |
2445 | int node) | |
2446 | { | |
2447 | up_read(&mm->mmap_sem); | |
2448 | VM_BUG_ON(!*hpage); | |
3b363692 | 2449 | |
26234f36 XG |
2450 | return *hpage; |
2451 | } | |
692e0b35 AA |
2452 | #endif |
2453 | ||
fa475e51 BL |
2454 | static bool hugepage_vma_check(struct vm_area_struct *vma) |
2455 | { | |
2456 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || | |
2457 | (vma->vm_flags & VM_NOHUGEPAGE)) | |
2458 | return false; | |
2459 | ||
2460 | if (!vma->anon_vma || vma->vm_ops) | |
2461 | return false; | |
2462 | if (is_vma_temporary_stack(vma)) | |
2463 | return false; | |
81d1b09c | 2464 | VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma); |
fa475e51 BL |
2465 | return true; |
2466 | } | |
2467 | ||
26234f36 XG |
2468 | static void collapse_huge_page(struct mm_struct *mm, |
2469 | unsigned long address, | |
2470 | struct page **hpage, | |
2471 | struct vm_area_struct *vma, | |
2472 | int node) | |
2473 | { | |
26234f36 XG |
2474 | pmd_t *pmd, _pmd; |
2475 | pte_t *pte; | |
2476 | pgtable_t pgtable; | |
2477 | struct page *new_page; | |
c4088ebd | 2478 | spinlock_t *pmd_ptl, *pte_ptl; |
26234f36 XG |
2479 | int isolated; |
2480 | unsigned long hstart, hend; | |
00501b53 | 2481 | struct mem_cgroup *memcg; |
2ec74c3e SG |
2482 | unsigned long mmun_start; /* For mmu_notifiers */ |
2483 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 2484 | gfp_t gfp; |
26234f36 XG |
2485 | |
2486 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2487 | ||
3b363692 MH |
2488 | /* Only allocate from the target node */ |
2489 | gfp = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) | | |
2490 | __GFP_THISNODE; | |
2491 | ||
26234f36 | 2492 | /* release the mmap_sem read lock. */ |
3b363692 | 2493 | new_page = khugepaged_alloc_page(hpage, gfp, mm, vma, address, node); |
26234f36 XG |
2494 | if (!new_page) |
2495 | return; | |
2496 | ||
00501b53 | 2497 | if (unlikely(mem_cgroup_try_charge(new_page, mm, |
3b363692 | 2498 | gfp, &memcg))) |
ce83d217 | 2499 | return; |
ba76149f AA |
2500 | |
2501 | /* | |
2502 | * Prevent all access to pagetables with the exception of | |
2503 | * gup_fast later hanlded by the ptep_clear_flush and the VM | |
2504 | * handled by the anon_vma lock + PG_lock. | |
2505 | */ | |
2506 | down_write(&mm->mmap_sem); | |
2507 | if (unlikely(khugepaged_test_exit(mm))) | |
2508 | goto out; | |
2509 | ||
2510 | vma = find_vma(mm, address); | |
a8f531eb L |
2511 | if (!vma) |
2512 | goto out; | |
ba76149f AA |
2513 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2514 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2515 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
2516 | goto out; | |
fa475e51 | 2517 | if (!hugepage_vma_check(vma)) |
a7d6e4ec | 2518 | goto out; |
6219049a BL |
2519 | pmd = mm_find_pmd(mm, address); |
2520 | if (!pmd) | |
ba76149f | 2521 | goto out; |
ba76149f | 2522 | |
4fc3f1d6 | 2523 | anon_vma_lock_write(vma->anon_vma); |
ba76149f AA |
2524 | |
2525 | pte = pte_offset_map(pmd, address); | |
c4088ebd | 2526 | pte_ptl = pte_lockptr(mm, pmd); |
ba76149f | 2527 | |
2ec74c3e SG |
2528 | mmun_start = address; |
2529 | mmun_end = address + HPAGE_PMD_SIZE; | |
2530 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
c4088ebd | 2531 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
ba76149f AA |
2532 | /* |
2533 | * After this gup_fast can't run anymore. This also removes | |
2534 | * any huge TLB entry from the CPU so we won't allow | |
2535 | * huge and small TLB entries for the same virtual address | |
2536 | * to avoid the risk of CPU bugs in that area. | |
2537 | */ | |
15a25b2e | 2538 | _pmd = pmdp_collapse_flush(vma, address, pmd); |
c4088ebd | 2539 | spin_unlock(pmd_ptl); |
2ec74c3e | 2540 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
ba76149f | 2541 | |
c4088ebd | 2542 | spin_lock(pte_ptl); |
ba76149f | 2543 | isolated = __collapse_huge_page_isolate(vma, address, pte); |
c4088ebd | 2544 | spin_unlock(pte_ptl); |
ba76149f AA |
2545 | |
2546 | if (unlikely(!isolated)) { | |
453c7192 | 2547 | pte_unmap(pte); |
c4088ebd | 2548 | spin_lock(pmd_ptl); |
ba76149f | 2549 | BUG_ON(!pmd_none(*pmd)); |
7c342512 AK |
2550 | /* |
2551 | * We can only use set_pmd_at when establishing | |
2552 | * hugepmds and never for establishing regular pmds that | |
2553 | * points to regular pagetables. Use pmd_populate for that | |
2554 | */ | |
2555 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
c4088ebd | 2556 | spin_unlock(pmd_ptl); |
08b52706 | 2557 | anon_vma_unlock_write(vma->anon_vma); |
ce83d217 | 2558 | goto out; |
ba76149f AA |
2559 | } |
2560 | ||
2561 | /* | |
2562 | * All pages are isolated and locked so anon_vma rmap | |
2563 | * can't run anymore. | |
2564 | */ | |
08b52706 | 2565 | anon_vma_unlock_write(vma->anon_vma); |
ba76149f | 2566 | |
c4088ebd | 2567 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); |
453c7192 | 2568 | pte_unmap(pte); |
ba76149f AA |
2569 | __SetPageUptodate(new_page); |
2570 | pgtable = pmd_pgtable(_pmd); | |
ba76149f | 2571 | |
3122359a KS |
2572 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); |
2573 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); | |
ba76149f AA |
2574 | |
2575 | /* | |
2576 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
2577 | * this is needed to avoid the copy_huge_page writes to become | |
2578 | * visible after the set_pmd_at() write. | |
2579 | */ | |
2580 | smp_wmb(); | |
2581 | ||
c4088ebd | 2582 | spin_lock(pmd_ptl); |
ba76149f AA |
2583 | BUG_ON(!pmd_none(*pmd)); |
2584 | page_add_new_anon_rmap(new_page, vma, address); | |
00501b53 JW |
2585 | mem_cgroup_commit_charge(new_page, memcg, false); |
2586 | lru_cache_add_active_or_unevictable(new_page, vma); | |
fce144b4 | 2587 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
ba76149f | 2588 | set_pmd_at(mm, address, pmd, _pmd); |
b113da65 | 2589 | update_mmu_cache_pmd(vma, address, pmd); |
c4088ebd | 2590 | spin_unlock(pmd_ptl); |
ba76149f AA |
2591 | |
2592 | *hpage = NULL; | |
420256ef | 2593 | |
ba76149f | 2594 | khugepaged_pages_collapsed++; |
ce83d217 | 2595 | out_up_write: |
ba76149f | 2596 | up_write(&mm->mmap_sem); |
0bbbc0b3 AA |
2597 | return; |
2598 | ||
ce83d217 | 2599 | out: |
00501b53 | 2600 | mem_cgroup_cancel_charge(new_page, memcg); |
ce83d217 | 2601 | goto out_up_write; |
ba76149f AA |
2602 | } |
2603 | ||
2604 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
2605 | struct vm_area_struct *vma, | |
2606 | unsigned long address, | |
2607 | struct page **hpage) | |
2608 | { | |
ba76149f AA |
2609 | pmd_t *pmd; |
2610 | pte_t *pte, *_pte; | |
ca0984ca | 2611 | int ret = 0, none_or_zero = 0; |
ba76149f AA |
2612 | struct page *page; |
2613 | unsigned long _address; | |
2614 | spinlock_t *ptl; | |
00ef2d2f | 2615 | int node = NUMA_NO_NODE; |
10359213 | 2616 | bool writable = false, referenced = false; |
ba76149f AA |
2617 | |
2618 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2619 | ||
6219049a BL |
2620 | pmd = mm_find_pmd(mm, address); |
2621 | if (!pmd) | |
ba76149f | 2622 | goto out; |
ba76149f | 2623 | |
9f1b868a | 2624 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); |
ba76149f AA |
2625 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
2626 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
2627 | _pte++, _address += PAGE_SIZE) { | |
2628 | pte_t pteval = *_pte; | |
ca0984ca | 2629 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
c1294d05 AA |
2630 | if (!userfaultfd_armed(vma) && |
2631 | ++none_or_zero <= khugepaged_max_ptes_none) | |
ba76149f AA |
2632 | continue; |
2633 | else | |
2634 | goto out_unmap; | |
2635 | } | |
10359213 | 2636 | if (!pte_present(pteval)) |
ba76149f | 2637 | goto out_unmap; |
10359213 EA |
2638 | if (pte_write(pteval)) |
2639 | writable = true; | |
2640 | ||
ba76149f AA |
2641 | page = vm_normal_page(vma, _address, pteval); |
2642 | if (unlikely(!page)) | |
2643 | goto out_unmap; | |
5c4b4be3 | 2644 | /* |
9f1b868a BL |
2645 | * Record which node the original page is from and save this |
2646 | * information to khugepaged_node_load[]. | |
2647 | * Khupaged will allocate hugepage from the node has the max | |
2648 | * hit record. | |
5c4b4be3 | 2649 | */ |
9f1b868a | 2650 | node = page_to_nid(page); |
14a4e214 DR |
2651 | if (khugepaged_scan_abort(node)) |
2652 | goto out_unmap; | |
9f1b868a | 2653 | khugepaged_node_load[node]++; |
309381fe | 2654 | VM_BUG_ON_PAGE(PageCompound(page), page); |
ba76149f AA |
2655 | if (!PageLRU(page) || PageLocked(page) || !PageAnon(page)) |
2656 | goto out_unmap; | |
10359213 EA |
2657 | /* |
2658 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2659 | * The page must only be referenced by the scanned process | |
2660 | * and page swap cache. | |
2661 | */ | |
2662 | if (page_count(page) != 1 + !!PageSwapCache(page)) | |
ba76149f | 2663 | goto out_unmap; |
8ee53820 AA |
2664 | if (pte_young(pteval) || PageReferenced(page) || |
2665 | mmu_notifier_test_young(vma->vm_mm, address)) | |
10359213 | 2666 | referenced = true; |
ba76149f | 2667 | } |
10359213 | 2668 | if (referenced && writable) |
ba76149f AA |
2669 | ret = 1; |
2670 | out_unmap: | |
2671 | pte_unmap_unlock(pte, ptl); | |
9f1b868a BL |
2672 | if (ret) { |
2673 | node = khugepaged_find_target_node(); | |
ce83d217 | 2674 | /* collapse_huge_page will return with the mmap_sem released */ |
5c4b4be3 | 2675 | collapse_huge_page(mm, address, hpage, vma, node); |
9f1b868a | 2676 | } |
ba76149f AA |
2677 | out: |
2678 | return ret; | |
2679 | } | |
2680 | ||
2681 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
2682 | { | |
2683 | struct mm_struct *mm = mm_slot->mm; | |
2684 | ||
b9980cdc | 2685 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2686 | |
2687 | if (khugepaged_test_exit(mm)) { | |
2688 | /* free mm_slot */ | |
43b5fbbd | 2689 | hash_del(&mm_slot->hash); |
ba76149f AA |
2690 | list_del(&mm_slot->mm_node); |
2691 | ||
2692 | /* | |
2693 | * Not strictly needed because the mm exited already. | |
2694 | * | |
2695 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
2696 | */ | |
2697 | ||
2698 | /* khugepaged_mm_lock actually not necessary for the below */ | |
2699 | free_mm_slot(mm_slot); | |
2700 | mmdrop(mm); | |
2701 | } | |
2702 | } | |
2703 | ||
2704 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
2705 | struct page **hpage) | |
2f1da642 HS |
2706 | __releases(&khugepaged_mm_lock) |
2707 | __acquires(&khugepaged_mm_lock) | |
ba76149f AA |
2708 | { |
2709 | struct mm_slot *mm_slot; | |
2710 | struct mm_struct *mm; | |
2711 | struct vm_area_struct *vma; | |
2712 | int progress = 0; | |
2713 | ||
2714 | VM_BUG_ON(!pages); | |
b9980cdc | 2715 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2716 | |
2717 | if (khugepaged_scan.mm_slot) | |
2718 | mm_slot = khugepaged_scan.mm_slot; | |
2719 | else { | |
2720 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2721 | struct mm_slot, mm_node); | |
2722 | khugepaged_scan.address = 0; | |
2723 | khugepaged_scan.mm_slot = mm_slot; | |
2724 | } | |
2725 | spin_unlock(&khugepaged_mm_lock); | |
2726 | ||
2727 | mm = mm_slot->mm; | |
2728 | down_read(&mm->mmap_sem); | |
2729 | if (unlikely(khugepaged_test_exit(mm))) | |
2730 | vma = NULL; | |
2731 | else | |
2732 | vma = find_vma(mm, khugepaged_scan.address); | |
2733 | ||
2734 | progress++; | |
2735 | for (; vma; vma = vma->vm_next) { | |
2736 | unsigned long hstart, hend; | |
2737 | ||
2738 | cond_resched(); | |
2739 | if (unlikely(khugepaged_test_exit(mm))) { | |
2740 | progress++; | |
2741 | break; | |
2742 | } | |
fa475e51 BL |
2743 | if (!hugepage_vma_check(vma)) { |
2744 | skip: | |
ba76149f AA |
2745 | progress++; |
2746 | continue; | |
2747 | } | |
ba76149f AA |
2748 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2749 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
a7d6e4ec AA |
2750 | if (hstart >= hend) |
2751 | goto skip; | |
2752 | if (khugepaged_scan.address > hend) | |
2753 | goto skip; | |
ba76149f AA |
2754 | if (khugepaged_scan.address < hstart) |
2755 | khugepaged_scan.address = hstart; | |
a7d6e4ec | 2756 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); |
ba76149f AA |
2757 | |
2758 | while (khugepaged_scan.address < hend) { | |
2759 | int ret; | |
2760 | cond_resched(); | |
2761 | if (unlikely(khugepaged_test_exit(mm))) | |
2762 | goto breakouterloop; | |
2763 | ||
2764 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2765 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2766 | hend); | |
2767 | ret = khugepaged_scan_pmd(mm, vma, | |
2768 | khugepaged_scan.address, | |
2769 | hpage); | |
2770 | /* move to next address */ | |
2771 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2772 | progress += HPAGE_PMD_NR; | |
2773 | if (ret) | |
2774 | /* we released mmap_sem so break loop */ | |
2775 | goto breakouterloop_mmap_sem; | |
2776 | if (progress >= pages) | |
2777 | goto breakouterloop; | |
2778 | } | |
2779 | } | |
2780 | breakouterloop: | |
2781 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2782 | breakouterloop_mmap_sem: | |
2783 | ||
2784 | spin_lock(&khugepaged_mm_lock); | |
a7d6e4ec | 2785 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); |
ba76149f AA |
2786 | /* |
2787 | * Release the current mm_slot if this mm is about to die, or | |
2788 | * if we scanned all vmas of this mm. | |
2789 | */ | |
2790 | if (khugepaged_test_exit(mm) || !vma) { | |
2791 | /* | |
2792 | * Make sure that if mm_users is reaching zero while | |
2793 | * khugepaged runs here, khugepaged_exit will find | |
2794 | * mm_slot not pointing to the exiting mm. | |
2795 | */ | |
2796 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2797 | khugepaged_scan.mm_slot = list_entry( | |
2798 | mm_slot->mm_node.next, | |
2799 | struct mm_slot, mm_node); | |
2800 | khugepaged_scan.address = 0; | |
2801 | } else { | |
2802 | khugepaged_scan.mm_slot = NULL; | |
2803 | khugepaged_full_scans++; | |
2804 | } | |
2805 | ||
2806 | collect_mm_slot(mm_slot); | |
2807 | } | |
2808 | ||
2809 | return progress; | |
2810 | } | |
2811 | ||
2812 | static int khugepaged_has_work(void) | |
2813 | { | |
2814 | return !list_empty(&khugepaged_scan.mm_head) && | |
2815 | khugepaged_enabled(); | |
2816 | } | |
2817 | ||
2818 | static int khugepaged_wait_event(void) | |
2819 | { | |
2820 | return !list_empty(&khugepaged_scan.mm_head) || | |
2017c0bf | 2821 | kthread_should_stop(); |
ba76149f AA |
2822 | } |
2823 | ||
d516904b | 2824 | static void khugepaged_do_scan(void) |
ba76149f | 2825 | { |
d516904b | 2826 | struct page *hpage = NULL; |
ba76149f AA |
2827 | unsigned int progress = 0, pass_through_head = 0; |
2828 | unsigned int pages = khugepaged_pages_to_scan; | |
d516904b | 2829 | bool wait = true; |
ba76149f AA |
2830 | |
2831 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2832 | ||
2833 | while (progress < pages) { | |
26234f36 | 2834 | if (!khugepaged_prealloc_page(&hpage, &wait)) |
d516904b | 2835 | break; |
26234f36 | 2836 | |
420256ef | 2837 | cond_resched(); |
ba76149f | 2838 | |
cd092411 | 2839 | if (unlikely(kthread_should_stop() || try_to_freeze())) |
878aee7d AA |
2840 | break; |
2841 | ||
ba76149f AA |
2842 | spin_lock(&khugepaged_mm_lock); |
2843 | if (!khugepaged_scan.mm_slot) | |
2844 | pass_through_head++; | |
2845 | if (khugepaged_has_work() && | |
2846 | pass_through_head < 2) | |
2847 | progress += khugepaged_scan_mm_slot(pages - progress, | |
d516904b | 2848 | &hpage); |
ba76149f AA |
2849 | else |
2850 | progress = pages; | |
2851 | spin_unlock(&khugepaged_mm_lock); | |
2852 | } | |
ba76149f | 2853 | |
d516904b XG |
2854 | if (!IS_ERR_OR_NULL(hpage)) |
2855 | put_page(hpage); | |
0bbbc0b3 AA |
2856 | } |
2857 | ||
2017c0bf XG |
2858 | static void khugepaged_wait_work(void) |
2859 | { | |
2017c0bf XG |
2860 | if (khugepaged_has_work()) { |
2861 | if (!khugepaged_scan_sleep_millisecs) | |
2862 | return; | |
2863 | ||
2864 | wait_event_freezable_timeout(khugepaged_wait, | |
2865 | kthread_should_stop(), | |
2866 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs)); | |
2867 | return; | |
2868 | } | |
2869 | ||
2870 | if (khugepaged_enabled()) | |
2871 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2872 | } | |
2873 | ||
ba76149f AA |
2874 | static int khugepaged(void *none) |
2875 | { | |
2876 | struct mm_slot *mm_slot; | |
2877 | ||
878aee7d | 2878 | set_freezable(); |
8698a745 | 2879 | set_user_nice(current, MAX_NICE); |
ba76149f | 2880 | |
b7231789 XG |
2881 | while (!kthread_should_stop()) { |
2882 | khugepaged_do_scan(); | |
2883 | khugepaged_wait_work(); | |
2884 | } | |
ba76149f AA |
2885 | |
2886 | spin_lock(&khugepaged_mm_lock); | |
2887 | mm_slot = khugepaged_scan.mm_slot; | |
2888 | khugepaged_scan.mm_slot = NULL; | |
2889 | if (mm_slot) | |
2890 | collect_mm_slot(mm_slot); | |
2891 | spin_unlock(&khugepaged_mm_lock); | |
ba76149f AA |
2892 | return 0; |
2893 | } | |
2894 | ||
c5a647d0 KS |
2895 | static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, |
2896 | unsigned long haddr, pmd_t *pmd) | |
2897 | { | |
2898 | struct mm_struct *mm = vma->vm_mm; | |
2899 | pgtable_t pgtable; | |
2900 | pmd_t _pmd; | |
2901 | int i; | |
2902 | ||
8809aa2d | 2903 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
c5a647d0 KS |
2904 | /* leave pmd empty until pte is filled */ |
2905 | ||
6b0b50b0 | 2906 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
c5a647d0 KS |
2907 | pmd_populate(mm, &_pmd, pgtable); |
2908 | ||
2909 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
2910 | pte_t *pte, entry; | |
2911 | entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); | |
2912 | entry = pte_mkspecial(entry); | |
2913 | pte = pte_offset_map(&_pmd, haddr); | |
2914 | VM_BUG_ON(!pte_none(*pte)); | |
2915 | set_pte_at(mm, haddr, pte, entry); | |
2916 | pte_unmap(pte); | |
2917 | } | |
2918 | smp_wmb(); /* make pte visible before pmd */ | |
2919 | pmd_populate(mm, pmd, pgtable); | |
97ae1749 | 2920 | put_huge_zero_page(); |
c5a647d0 KS |
2921 | } |
2922 | ||
e180377f KS |
2923 | void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address, |
2924 | pmd_t *pmd) | |
71e3aac0 | 2925 | { |
c4088ebd | 2926 | spinlock_t *ptl; |
4897c765 | 2927 | struct page *page = NULL; |
e180377f | 2928 | struct mm_struct *mm = vma->vm_mm; |
c5a647d0 KS |
2929 | unsigned long haddr = address & HPAGE_PMD_MASK; |
2930 | unsigned long mmun_start; /* For mmu_notifiers */ | |
2931 | unsigned long mmun_end; /* For mmu_notifiers */ | |
e180377f KS |
2932 | |
2933 | BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE); | |
71e3aac0 | 2934 | |
c5a647d0 KS |
2935 | mmun_start = haddr; |
2936 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
750e8165 | 2937 | again: |
c5a647d0 | 2938 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
c4088ebd | 2939 | ptl = pmd_lock(mm, pmd); |
4897c765 MW |
2940 | if (unlikely(!pmd_trans_huge(*pmd))) |
2941 | goto unlock; | |
2942 | if (vma_is_dax(vma)) { | |
2943 | pmdp_huge_clear_flush(vma, haddr, pmd); | |
2944 | } else if (is_huge_zero_pmd(*pmd)) { | |
c5a647d0 | 2945 | __split_huge_zero_page_pmd(vma, haddr, pmd); |
4897c765 MW |
2946 | } else { |
2947 | page = pmd_page(*pmd); | |
2948 | VM_BUG_ON_PAGE(!page_count(page), page); | |
2949 | get_page(page); | |
71e3aac0 | 2950 | } |
4897c765 | 2951 | unlock: |
c4088ebd | 2952 | spin_unlock(ptl); |
c5a647d0 | 2953 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
71e3aac0 | 2954 | |
4897c765 MW |
2955 | if (!page) |
2956 | return; | |
71e3aac0 | 2957 | |
4897c765 | 2958 | split_huge_page(page); |
71e3aac0 | 2959 | put_page(page); |
750e8165 HD |
2960 | |
2961 | /* | |
2962 | * We don't always have down_write of mmap_sem here: a racing | |
2963 | * do_huge_pmd_wp_page() might have copied-on-write to another | |
2964 | * huge page before our split_huge_page() got the anon_vma lock. | |
2965 | */ | |
2966 | if (unlikely(pmd_trans_huge(*pmd))) | |
2967 | goto again; | |
71e3aac0 | 2968 | } |
94fcc585 | 2969 | |
e180377f KS |
2970 | void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address, |
2971 | pmd_t *pmd) | |
2972 | { | |
2973 | struct vm_area_struct *vma; | |
2974 | ||
2975 | vma = find_vma(mm, address); | |
2976 | BUG_ON(vma == NULL); | |
2977 | split_huge_page_pmd(vma, address, pmd); | |
2978 | } | |
2979 | ||
94fcc585 AA |
2980 | static void split_huge_page_address(struct mm_struct *mm, |
2981 | unsigned long address) | |
2982 | { | |
f72e7dcd HD |
2983 | pgd_t *pgd; |
2984 | pud_t *pud; | |
94fcc585 AA |
2985 | pmd_t *pmd; |
2986 | ||
2987 | VM_BUG_ON(!(address & ~HPAGE_PMD_MASK)); | |
2988 | ||
f72e7dcd HD |
2989 | pgd = pgd_offset(mm, address); |
2990 | if (!pgd_present(*pgd)) | |
2991 | return; | |
2992 | ||
2993 | pud = pud_offset(pgd, address); | |
2994 | if (!pud_present(*pud)) | |
2995 | return; | |
2996 | ||
2997 | pmd = pmd_offset(pud, address); | |
2998 | if (!pmd_present(*pmd)) | |
94fcc585 AA |
2999 | return; |
3000 | /* | |
3001 | * Caller holds the mmap_sem write mode, so a huge pmd cannot | |
3002 | * materialize from under us. | |
3003 | */ | |
e180377f | 3004 | split_huge_page_pmd_mm(mm, address, pmd); |
94fcc585 AA |
3005 | } |
3006 | ||
e1b9996b | 3007 | void vma_adjust_trans_huge(struct vm_area_struct *vma, |
94fcc585 AA |
3008 | unsigned long start, |
3009 | unsigned long end, | |
3010 | long adjust_next) | |
3011 | { | |
3012 | /* | |
3013 | * If the new start address isn't hpage aligned and it could | |
3014 | * previously contain an hugepage: check if we need to split | |
3015 | * an huge pmd. | |
3016 | */ | |
3017 | if (start & ~HPAGE_PMD_MASK && | |
3018 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
3019 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
3020 | split_huge_page_address(vma->vm_mm, start); | |
3021 | ||
3022 | /* | |
3023 | * If the new end address isn't hpage aligned and it could | |
3024 | * previously contain an hugepage: check if we need to split | |
3025 | * an huge pmd. | |
3026 | */ | |
3027 | if (end & ~HPAGE_PMD_MASK && | |
3028 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
3029 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
3030 | split_huge_page_address(vma->vm_mm, end); | |
3031 | ||
3032 | /* | |
3033 | * If we're also updating the vma->vm_next->vm_start, if the new | |
3034 | * vm_next->vm_start isn't page aligned and it could previously | |
3035 | * contain an hugepage: check if we need to split an huge pmd. | |
3036 | */ | |
3037 | if (adjust_next > 0) { | |
3038 | struct vm_area_struct *next = vma->vm_next; | |
3039 | unsigned long nstart = next->vm_start; | |
3040 | nstart += adjust_next << PAGE_SHIFT; | |
3041 | if (nstart & ~HPAGE_PMD_MASK && | |
3042 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
3043 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
3044 | split_huge_page_address(next->vm_mm, nstart); | |
3045 | } | |
3046 | } |