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Commit | Line | Data |
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71e3aac0 AA |
1 | /* |
2 | * Copyright (C) 2009 Red Hat, Inc. | |
3 | * | |
4 | * This work is licensed under the terms of the GNU GPL, version 2. See | |
5 | * the COPYING file in the top-level directory. | |
6 | */ | |
7 | ||
ae3a8c1c AM |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
9 | ||
71e3aac0 AA |
10 | #include <linux/mm.h> |
11 | #include <linux/sched.h> | |
12 | #include <linux/highmem.h> | |
13 | #include <linux/hugetlb.h> | |
14 | #include <linux/mmu_notifier.h> | |
15 | #include <linux/rmap.h> | |
16 | #include <linux/swap.h> | |
97ae1749 | 17 | #include <linux/shrinker.h> |
ba76149f | 18 | #include <linux/mm_inline.h> |
4897c765 | 19 | #include <linux/dax.h> |
ba76149f AA |
20 | #include <linux/kthread.h> |
21 | #include <linux/khugepaged.h> | |
878aee7d | 22 | #include <linux/freezer.h> |
a664b2d8 | 23 | #include <linux/mman.h> |
325adeb5 | 24 | #include <linux/pagemap.h> |
4daae3b4 | 25 | #include <linux/migrate.h> |
43b5fbbd | 26 | #include <linux/hashtable.h> |
6b251fc9 | 27 | #include <linux/userfaultfd_k.h> |
97ae1749 | 28 | |
71e3aac0 AA |
29 | #include <asm/tlb.h> |
30 | #include <asm/pgalloc.h> | |
31 | #include "internal.h" | |
32 | ||
ba76149f | 33 | /* |
8bfa3f9a JW |
34 | * By default transparent hugepage support is disabled in order that avoid |
35 | * to risk increase the memory footprint of applications without a guaranteed | |
36 | * benefit. When transparent hugepage support is enabled, is for all mappings, | |
37 | * and khugepaged scans all mappings. | |
38 | * Defrag is invoked by khugepaged hugepage allocations and by page faults | |
39 | * for all hugepage allocations. | |
ba76149f | 40 | */ |
71e3aac0 | 41 | unsigned long transparent_hugepage_flags __read_mostly = |
13ece886 | 42 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS |
ba76149f | 43 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| |
13ece886 AA |
44 | #endif |
45 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE | |
46 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| | |
47 | #endif | |
d39d33c3 | 48 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)| |
79da5407 KS |
49 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| |
50 | (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
ba76149f AA |
51 | |
52 | /* default scan 8*512 pte (or vmas) every 30 second */ | |
53 | static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8; | |
54 | static unsigned int khugepaged_pages_collapsed; | |
55 | static unsigned int khugepaged_full_scans; | |
56 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
57 | /* during fragmentation poll the hugepage allocator once every minute */ | |
58 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
59 | static struct task_struct *khugepaged_thread __read_mostly; | |
60 | static DEFINE_MUTEX(khugepaged_mutex); | |
61 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
62 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
63 | /* | |
64 | * default collapse hugepages if there is at least one pte mapped like | |
65 | * it would have happened if the vma was large enough during page | |
66 | * fault. | |
67 | */ | |
68 | static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1; | |
69 | ||
70 | static int khugepaged(void *none); | |
ba76149f | 71 | static int khugepaged_slab_init(void); |
65ebb64f | 72 | static void khugepaged_slab_exit(void); |
ba76149f | 73 | |
43b5fbbd SL |
74 | #define MM_SLOTS_HASH_BITS 10 |
75 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
76 | ||
ba76149f AA |
77 | static struct kmem_cache *mm_slot_cache __read_mostly; |
78 | ||
79 | /** | |
80 | * struct mm_slot - hash lookup from mm to mm_slot | |
81 | * @hash: hash collision list | |
82 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
83 | * @mm: the mm that this information is valid for | |
84 | */ | |
85 | struct mm_slot { | |
86 | struct hlist_node hash; | |
87 | struct list_head mm_node; | |
88 | struct mm_struct *mm; | |
89 | }; | |
90 | ||
91 | /** | |
92 | * struct khugepaged_scan - cursor for scanning | |
93 | * @mm_head: the head of the mm list to scan | |
94 | * @mm_slot: the current mm_slot we are scanning | |
95 | * @address: the next address inside that to be scanned | |
96 | * | |
97 | * There is only the one khugepaged_scan instance of this cursor structure. | |
98 | */ | |
99 | struct khugepaged_scan { | |
100 | struct list_head mm_head; | |
101 | struct mm_slot *mm_slot; | |
102 | unsigned long address; | |
2f1da642 HS |
103 | }; |
104 | static struct khugepaged_scan khugepaged_scan = { | |
ba76149f AA |
105 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), |
106 | }; | |
107 | ||
f000565a 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 | |
fc437044 | 176 | struct page *get_huge_zero_page(void) |
97ae1749 KS |
177 | { |
178 | struct page *zero_page; | |
179 | retry: | |
180 | if (likely(atomic_inc_not_zero(&huge_zero_refcount))) | |
4db0c3c2 | 181 | return READ_ONCE(huge_zero_page); |
97ae1749 KS |
182 | |
183 | zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, | |
4a6c1297 | 184 | HPAGE_PMD_ORDER); |
d8a8e1f0 KS |
185 | if (!zero_page) { |
186 | count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); | |
5918d10a | 187 | return NULL; |
d8a8e1f0 KS |
188 | } |
189 | count_vm_event(THP_ZERO_PAGE_ALLOC); | |
97ae1749 | 190 | preempt_disable(); |
5918d10a | 191 | if (cmpxchg(&huge_zero_page, NULL, zero_page)) { |
97ae1749 | 192 | preempt_enable(); |
5ddacbe9 | 193 | __free_pages(zero_page, compound_order(zero_page)); |
97ae1749 KS |
194 | goto retry; |
195 | } | |
196 | ||
197 | /* We take additional reference here. It will be put back by shrinker */ | |
198 | atomic_set(&huge_zero_refcount, 2); | |
199 | preempt_enable(); | |
4db0c3c2 | 200 | return READ_ONCE(huge_zero_page); |
4a6c1297 KS |
201 | } |
202 | ||
97ae1749 | 203 | static void put_huge_zero_page(void) |
4a6c1297 | 204 | { |
97ae1749 KS |
205 | /* |
206 | * Counter should never go to zero here. Only shrinker can put | |
207 | * last reference. | |
208 | */ | |
209 | BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); | |
4a6c1297 KS |
210 | } |
211 | ||
48896466 GC |
212 | static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, |
213 | struct shrink_control *sc) | |
4a6c1297 | 214 | { |
48896466 GC |
215 | /* we can free zero page only if last reference remains */ |
216 | return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; | |
217 | } | |
97ae1749 | 218 | |
48896466 GC |
219 | static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, |
220 | struct shrink_control *sc) | |
221 | { | |
97ae1749 | 222 | if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { |
5918d10a KS |
223 | struct page *zero_page = xchg(&huge_zero_page, NULL); |
224 | BUG_ON(zero_page == NULL); | |
5ddacbe9 | 225 | __free_pages(zero_page, compound_order(zero_page)); |
48896466 | 226 | return HPAGE_PMD_NR; |
97ae1749 KS |
227 | } |
228 | ||
229 | return 0; | |
4a6c1297 KS |
230 | } |
231 | ||
97ae1749 | 232 | static struct shrinker huge_zero_page_shrinker = { |
48896466 GC |
233 | .count_objects = shrink_huge_zero_page_count, |
234 | .scan_objects = shrink_huge_zero_page_scan, | |
97ae1749 KS |
235 | .seeks = DEFAULT_SEEKS, |
236 | }; | |
237 | ||
71e3aac0 | 238 | #ifdef CONFIG_SYSFS |
ba76149f | 239 | |
71e3aac0 AA |
240 | static ssize_t double_flag_show(struct kobject *kobj, |
241 | struct kobj_attribute *attr, char *buf, | |
242 | enum transparent_hugepage_flag enabled, | |
243 | enum transparent_hugepage_flag req_madv) | |
244 | { | |
245 | if (test_bit(enabled, &transparent_hugepage_flags)) { | |
246 | VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags)); | |
247 | return sprintf(buf, "[always] madvise never\n"); | |
248 | } else if (test_bit(req_madv, &transparent_hugepage_flags)) | |
249 | return sprintf(buf, "always [madvise] never\n"); | |
250 | else | |
251 | return sprintf(buf, "always madvise [never]\n"); | |
252 | } | |
253 | static ssize_t double_flag_store(struct kobject *kobj, | |
254 | struct kobj_attribute *attr, | |
255 | const char *buf, size_t count, | |
256 | enum transparent_hugepage_flag enabled, | |
257 | enum transparent_hugepage_flag req_madv) | |
258 | { | |
259 | if (!memcmp("always", buf, | |
260 | min(sizeof("always")-1, count))) { | |
261 | set_bit(enabled, &transparent_hugepage_flags); | |
262 | clear_bit(req_madv, &transparent_hugepage_flags); | |
263 | } else if (!memcmp("madvise", buf, | |
264 | min(sizeof("madvise")-1, count))) { | |
265 | clear_bit(enabled, &transparent_hugepage_flags); | |
266 | set_bit(req_madv, &transparent_hugepage_flags); | |
267 | } else if (!memcmp("never", buf, | |
268 | min(sizeof("never")-1, count))) { | |
269 | clear_bit(enabled, &transparent_hugepage_flags); | |
270 | clear_bit(req_madv, &transparent_hugepage_flags); | |
271 | } else | |
272 | return -EINVAL; | |
273 | ||
274 | return count; | |
275 | } | |
276 | ||
277 | static ssize_t enabled_show(struct kobject *kobj, | |
278 | struct kobj_attribute *attr, char *buf) | |
279 | { | |
280 | return double_flag_show(kobj, attr, buf, | |
281 | TRANSPARENT_HUGEPAGE_FLAG, | |
282 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
283 | } | |
284 | static ssize_t enabled_store(struct kobject *kobj, | |
285 | struct kobj_attribute *attr, | |
286 | const char *buf, size_t count) | |
287 | { | |
ba76149f AA |
288 | ssize_t ret; |
289 | ||
290 | ret = double_flag_store(kobj, attr, buf, count, | |
291 | TRANSPARENT_HUGEPAGE_FLAG, | |
292 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
293 | ||
294 | if (ret > 0) { | |
911891af XG |
295 | int err; |
296 | ||
297 | mutex_lock(&khugepaged_mutex); | |
79553da2 | 298 | err = start_stop_khugepaged(); |
911891af XG |
299 | mutex_unlock(&khugepaged_mutex); |
300 | ||
ba76149f AA |
301 | if (err) |
302 | ret = err; | |
303 | } | |
304 | ||
305 | return ret; | |
71e3aac0 AA |
306 | } |
307 | static struct kobj_attribute enabled_attr = | |
308 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
309 | ||
310 | static ssize_t single_flag_show(struct kobject *kobj, | |
311 | struct kobj_attribute *attr, char *buf, | |
312 | enum transparent_hugepage_flag flag) | |
313 | { | |
e27e6151 BH |
314 | return sprintf(buf, "%d\n", |
315 | !!test_bit(flag, &transparent_hugepage_flags)); | |
71e3aac0 | 316 | } |
e27e6151 | 317 | |
71e3aac0 AA |
318 | static ssize_t single_flag_store(struct kobject *kobj, |
319 | struct kobj_attribute *attr, | |
320 | const char *buf, size_t count, | |
321 | enum transparent_hugepage_flag flag) | |
322 | { | |
e27e6151 BH |
323 | unsigned long value; |
324 | int ret; | |
325 | ||
326 | ret = kstrtoul(buf, 10, &value); | |
327 | if (ret < 0) | |
328 | return ret; | |
329 | if (value > 1) | |
330 | return -EINVAL; | |
331 | ||
332 | if (value) | |
71e3aac0 | 333 | set_bit(flag, &transparent_hugepage_flags); |
e27e6151 | 334 | else |
71e3aac0 | 335 | clear_bit(flag, &transparent_hugepage_flags); |
71e3aac0 AA |
336 | |
337 | return count; | |
338 | } | |
339 | ||
340 | /* | |
341 | * Currently defrag only disables __GFP_NOWAIT for allocation. A blind | |
342 | * __GFP_REPEAT is too aggressive, it's never worth swapping tons of | |
343 | * memory just to allocate one more hugepage. | |
344 | */ | |
345 | static ssize_t defrag_show(struct kobject *kobj, | |
346 | struct kobj_attribute *attr, char *buf) | |
347 | { | |
348 | return double_flag_show(kobj, attr, buf, | |
349 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
350 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
351 | } | |
352 | static ssize_t defrag_store(struct kobject *kobj, | |
353 | struct kobj_attribute *attr, | |
354 | const char *buf, size_t count) | |
355 | { | |
356 | return double_flag_store(kobj, attr, buf, count, | |
357 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
358 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
359 | } | |
360 | static struct kobj_attribute defrag_attr = | |
361 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
362 | ||
79da5407 KS |
363 | static ssize_t use_zero_page_show(struct kobject *kobj, |
364 | struct kobj_attribute *attr, char *buf) | |
365 | { | |
366 | return single_flag_show(kobj, attr, buf, | |
367 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
368 | } | |
369 | static ssize_t use_zero_page_store(struct kobject *kobj, | |
370 | struct kobj_attribute *attr, const char *buf, size_t count) | |
371 | { | |
372 | return single_flag_store(kobj, attr, buf, count, | |
373 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
374 | } | |
375 | static struct kobj_attribute use_zero_page_attr = | |
376 | __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); | |
71e3aac0 AA |
377 | #ifdef CONFIG_DEBUG_VM |
378 | static ssize_t debug_cow_show(struct kobject *kobj, | |
379 | struct kobj_attribute *attr, char *buf) | |
380 | { | |
381 | return single_flag_show(kobj, attr, buf, | |
382 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
383 | } | |
384 | static ssize_t debug_cow_store(struct kobject *kobj, | |
385 | struct kobj_attribute *attr, | |
386 | const char *buf, size_t count) | |
387 | { | |
388 | return single_flag_store(kobj, attr, buf, count, | |
389 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
390 | } | |
391 | static struct kobj_attribute debug_cow_attr = | |
392 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
393 | #endif /* CONFIG_DEBUG_VM */ | |
394 | ||
395 | static struct attribute *hugepage_attr[] = { | |
396 | &enabled_attr.attr, | |
397 | &defrag_attr.attr, | |
79da5407 | 398 | &use_zero_page_attr.attr, |
71e3aac0 AA |
399 | #ifdef CONFIG_DEBUG_VM |
400 | &debug_cow_attr.attr, | |
401 | #endif | |
402 | NULL, | |
403 | }; | |
404 | ||
405 | static struct attribute_group hugepage_attr_group = { | |
406 | .attrs = hugepage_attr, | |
ba76149f AA |
407 | }; |
408 | ||
409 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, | |
410 | struct kobj_attribute *attr, | |
411 | char *buf) | |
412 | { | |
413 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
414 | } | |
415 | ||
416 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
417 | struct kobj_attribute *attr, | |
418 | const char *buf, size_t count) | |
419 | { | |
420 | unsigned long msecs; | |
421 | int err; | |
422 | ||
3dbb95f7 | 423 | err = kstrtoul(buf, 10, &msecs); |
ba76149f AA |
424 | if (err || msecs > UINT_MAX) |
425 | return -EINVAL; | |
426 | ||
427 | khugepaged_scan_sleep_millisecs = msecs; | |
428 | wake_up_interruptible(&khugepaged_wait); | |
429 | ||
430 | return count; | |
431 | } | |
432 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
433 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
434 | scan_sleep_millisecs_store); | |
435 | ||
436 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
437 | struct kobj_attribute *attr, | |
438 | char *buf) | |
439 | { | |
440 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
441 | } | |
442 | ||
443 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
444 | struct kobj_attribute *attr, | |
445 | const char *buf, size_t count) | |
446 | { | |
447 | unsigned long msecs; | |
448 | int err; | |
449 | ||
3dbb95f7 | 450 | err = kstrtoul(buf, 10, &msecs); |
ba76149f AA |
451 | if (err || msecs > UINT_MAX) |
452 | return -EINVAL; | |
453 | ||
454 | khugepaged_alloc_sleep_millisecs = msecs; | |
455 | wake_up_interruptible(&khugepaged_wait); | |
456 | ||
457 | return count; | |
458 | } | |
459 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
460 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
461 | alloc_sleep_millisecs_store); | |
462 | ||
463 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
464 | struct kobj_attribute *attr, | |
465 | char *buf) | |
466 | { | |
467 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
468 | } | |
469 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
470 | struct kobj_attribute *attr, | |
471 | const char *buf, size_t count) | |
472 | { | |
473 | int err; | |
474 | unsigned long pages; | |
475 | ||
3dbb95f7 | 476 | err = kstrtoul(buf, 10, &pages); |
ba76149f AA |
477 | if (err || !pages || pages > UINT_MAX) |
478 | return -EINVAL; | |
479 | ||
480 | khugepaged_pages_to_scan = pages; | |
481 | ||
482 | return count; | |
483 | } | |
484 | static struct kobj_attribute pages_to_scan_attr = | |
485 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
486 | pages_to_scan_store); | |
487 | ||
488 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
489 | struct kobj_attribute *attr, | |
490 | char *buf) | |
491 | { | |
492 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
493 | } | |
494 | static struct kobj_attribute pages_collapsed_attr = | |
495 | __ATTR_RO(pages_collapsed); | |
496 | ||
497 | static ssize_t full_scans_show(struct kobject *kobj, | |
498 | struct kobj_attribute *attr, | |
499 | char *buf) | |
500 | { | |
501 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
502 | } | |
503 | static struct kobj_attribute full_scans_attr = | |
504 | __ATTR_RO(full_scans); | |
505 | ||
506 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
507 | struct kobj_attribute *attr, char *buf) | |
508 | { | |
509 | return single_flag_show(kobj, attr, buf, | |
510 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
511 | } | |
512 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
513 | struct kobj_attribute *attr, | |
514 | const char *buf, size_t count) | |
515 | { | |
516 | return single_flag_store(kobj, attr, buf, count, | |
517 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
518 | } | |
519 | static struct kobj_attribute khugepaged_defrag_attr = | |
520 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
521 | khugepaged_defrag_store); | |
522 | ||
523 | /* | |
524 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
525 | * any unmapped ptes in turn potentially increasing the memory | |
526 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
527 | * reduce the available free memory in the system as it | |
528 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
529 | * free memory in the system during the khugepaged scan. | |
530 | */ | |
531 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
532 | struct kobj_attribute *attr, | |
533 | char *buf) | |
534 | { | |
535 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
536 | } | |
537 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
538 | struct kobj_attribute *attr, | |
539 | const char *buf, size_t count) | |
540 | { | |
541 | int err; | |
542 | unsigned long max_ptes_none; | |
543 | ||
3dbb95f7 | 544 | err = kstrtoul(buf, 10, &max_ptes_none); |
ba76149f AA |
545 | if (err || max_ptes_none > HPAGE_PMD_NR-1) |
546 | return -EINVAL; | |
547 | ||
548 | khugepaged_max_ptes_none = max_ptes_none; | |
549 | ||
550 | return count; | |
551 | } | |
552 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
553 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
554 | khugepaged_max_ptes_none_store); | |
555 | ||
556 | static struct attribute *khugepaged_attr[] = { | |
557 | &khugepaged_defrag_attr.attr, | |
558 | &khugepaged_max_ptes_none_attr.attr, | |
559 | &pages_to_scan_attr.attr, | |
560 | &pages_collapsed_attr.attr, | |
561 | &full_scans_attr.attr, | |
562 | &scan_sleep_millisecs_attr.attr, | |
563 | &alloc_sleep_millisecs_attr.attr, | |
564 | NULL, | |
565 | }; | |
566 | ||
567 | static struct attribute_group khugepaged_attr_group = { | |
568 | .attrs = khugepaged_attr, | |
569 | .name = "khugepaged", | |
71e3aac0 | 570 | }; |
71e3aac0 | 571 | |
569e5590 | 572 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
71e3aac0 | 573 | { |
71e3aac0 AA |
574 | int err; |
575 | ||
569e5590 SL |
576 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); |
577 | if (unlikely(!*hugepage_kobj)) { | |
ae3a8c1c | 578 | pr_err("failed to create transparent hugepage kobject\n"); |
569e5590 | 579 | return -ENOMEM; |
ba76149f AA |
580 | } |
581 | ||
569e5590 | 582 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); |
ba76149f | 583 | if (err) { |
ae3a8c1c | 584 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 585 | goto delete_obj; |
ba76149f AA |
586 | } |
587 | ||
569e5590 | 588 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); |
ba76149f | 589 | if (err) { |
ae3a8c1c | 590 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 591 | goto remove_hp_group; |
ba76149f | 592 | } |
569e5590 SL |
593 | |
594 | return 0; | |
595 | ||
596 | remove_hp_group: | |
597 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
598 | delete_obj: | |
599 | kobject_put(*hugepage_kobj); | |
600 | return err; | |
601 | } | |
602 | ||
603 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
604 | { | |
605 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
606 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
607 | kobject_put(hugepage_kobj); | |
608 | } | |
609 | #else | |
610 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
611 | { | |
612 | return 0; | |
613 | } | |
614 | ||
615 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
616 | { | |
617 | } | |
618 | #endif /* CONFIG_SYSFS */ | |
619 | ||
620 | static int __init hugepage_init(void) | |
621 | { | |
622 | int err; | |
623 | struct kobject *hugepage_kobj; | |
624 | ||
625 | if (!has_transparent_hugepage()) { | |
626 | transparent_hugepage_flags = 0; | |
627 | return -EINVAL; | |
628 | } | |
629 | ||
630 | err = hugepage_init_sysfs(&hugepage_kobj); | |
631 | if (err) | |
65ebb64f | 632 | goto err_sysfs; |
ba76149f AA |
633 | |
634 | err = khugepaged_slab_init(); | |
635 | if (err) | |
65ebb64f | 636 | goto err_slab; |
ba76149f | 637 | |
65ebb64f KS |
638 | err = register_shrinker(&huge_zero_page_shrinker); |
639 | if (err) | |
640 | goto err_hzp_shrinker; | |
97ae1749 | 641 | |
97562cd2 RR |
642 | /* |
643 | * By default disable transparent hugepages on smaller systems, | |
644 | * where the extra memory used could hurt more than TLB overhead | |
645 | * is likely to save. The admin can still enable it through /sys. | |
646 | */ | |
79553da2 | 647 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) { |
97562cd2 | 648 | transparent_hugepage_flags = 0; |
79553da2 KS |
649 | return 0; |
650 | } | |
97562cd2 | 651 | |
79553da2 | 652 | err = start_stop_khugepaged(); |
65ebb64f KS |
653 | if (err) |
654 | goto err_khugepaged; | |
ba76149f | 655 | |
569e5590 | 656 | return 0; |
65ebb64f KS |
657 | err_khugepaged: |
658 | unregister_shrinker(&huge_zero_page_shrinker); | |
659 | err_hzp_shrinker: | |
660 | khugepaged_slab_exit(); | |
661 | err_slab: | |
569e5590 | 662 | hugepage_exit_sysfs(hugepage_kobj); |
65ebb64f | 663 | err_sysfs: |
ba76149f | 664 | return err; |
71e3aac0 | 665 | } |
a64fb3cd | 666 | subsys_initcall(hugepage_init); |
71e3aac0 AA |
667 | |
668 | static int __init setup_transparent_hugepage(char *str) | |
669 | { | |
670 | int ret = 0; | |
671 | if (!str) | |
672 | goto out; | |
673 | if (!strcmp(str, "always")) { | |
674 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
675 | &transparent_hugepage_flags); | |
676 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
677 | &transparent_hugepage_flags); | |
678 | ret = 1; | |
679 | } else if (!strcmp(str, "madvise")) { | |
680 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
681 | &transparent_hugepage_flags); | |
682 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
683 | &transparent_hugepage_flags); | |
684 | ret = 1; | |
685 | } else if (!strcmp(str, "never")) { | |
686 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
687 | &transparent_hugepage_flags); | |
688 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
689 | &transparent_hugepage_flags); | |
690 | ret = 1; | |
691 | } | |
692 | out: | |
693 | if (!ret) | |
ae3a8c1c | 694 | pr_warn("transparent_hugepage= cannot parse, ignored\n"); |
71e3aac0 AA |
695 | return ret; |
696 | } | |
697 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
698 | ||
b32967ff | 699 | pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) |
71e3aac0 AA |
700 | { |
701 | if (likely(vma->vm_flags & VM_WRITE)) | |
702 | pmd = pmd_mkwrite(pmd); | |
703 | return pmd; | |
704 | } | |
705 | ||
3122359a | 706 | static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot) |
b3092b3b BL |
707 | { |
708 | pmd_t entry; | |
3122359a | 709 | entry = mk_pmd(page, prot); |
b3092b3b BL |
710 | entry = pmd_mkhuge(entry); |
711 | return entry; | |
712 | } | |
713 | ||
71e3aac0 AA |
714 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, |
715 | struct vm_area_struct *vma, | |
230c92a8 | 716 | unsigned long address, pmd_t *pmd, |
6b251fc9 AA |
717 | struct page *page, gfp_t gfp, |
718 | unsigned int flags) | |
71e3aac0 | 719 | { |
00501b53 | 720 | struct mem_cgroup *memcg; |
71e3aac0 | 721 | pgtable_t pgtable; |
c4088ebd | 722 | spinlock_t *ptl; |
230c92a8 | 723 | unsigned long haddr = address & HPAGE_PMD_MASK; |
71e3aac0 | 724 | |
309381fe | 725 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
00501b53 | 726 | |
6b251fc9 AA |
727 | if (mem_cgroup_try_charge(page, mm, gfp, &memcg)) { |
728 | put_page(page); | |
729 | count_vm_event(THP_FAULT_FALLBACK); | |
730 | return VM_FAULT_FALLBACK; | |
731 | } | |
00501b53 | 732 | |
71e3aac0 | 733 | pgtable = pte_alloc_one(mm, haddr); |
00501b53 JW |
734 | if (unlikely(!pgtable)) { |
735 | mem_cgroup_cancel_charge(page, memcg); | |
6b251fc9 | 736 | put_page(page); |
71e3aac0 | 737 | return VM_FAULT_OOM; |
00501b53 | 738 | } |
71e3aac0 AA |
739 | |
740 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
52f37629 MK |
741 | /* |
742 | * The memory barrier inside __SetPageUptodate makes sure that | |
743 | * clear_huge_page writes become visible before the set_pmd_at() | |
744 | * write. | |
745 | */ | |
71e3aac0 AA |
746 | __SetPageUptodate(page); |
747 | ||
c4088ebd | 748 | ptl = pmd_lock(mm, pmd); |
71e3aac0 | 749 | if (unlikely(!pmd_none(*pmd))) { |
c4088ebd | 750 | spin_unlock(ptl); |
00501b53 | 751 | mem_cgroup_cancel_charge(page, memcg); |
71e3aac0 AA |
752 | put_page(page); |
753 | pte_free(mm, pgtable); | |
754 | } else { | |
755 | pmd_t entry; | |
6b251fc9 AA |
756 | |
757 | /* Deliver the page fault to userland */ | |
758 | if (userfaultfd_missing(vma)) { | |
759 | int ret; | |
760 | ||
761 | spin_unlock(ptl); | |
762 | mem_cgroup_cancel_charge(page, memcg); | |
763 | put_page(page); | |
764 | pte_free(mm, pgtable); | |
230c92a8 | 765 | ret = handle_userfault(vma, address, flags, |
6b251fc9 AA |
766 | VM_UFFD_MISSING); |
767 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
768 | return ret; | |
769 | } | |
770 | ||
3122359a KS |
771 | entry = mk_huge_pmd(page, vma->vm_page_prot); |
772 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
71e3aac0 | 773 | page_add_new_anon_rmap(page, vma, haddr); |
00501b53 JW |
774 | mem_cgroup_commit_charge(page, memcg, false); |
775 | lru_cache_add_active_or_unevictable(page, vma); | |
6b0b50b0 | 776 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
71e3aac0 | 777 | set_pmd_at(mm, haddr, pmd, entry); |
71e3aac0 | 778 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
e1f56c89 | 779 | atomic_long_inc(&mm->nr_ptes); |
c4088ebd | 780 | spin_unlock(ptl); |
6b251fc9 | 781 | count_vm_event(THP_FAULT_ALLOC); |
71e3aac0 AA |
782 | } |
783 | ||
aa2e878e | 784 | return 0; |
71e3aac0 AA |
785 | } |
786 | ||
cc5d462f | 787 | static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp) |
0bbbc0b3 | 788 | { |
cc5d462f | 789 | return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp; |
0bbbc0b3 AA |
790 | } |
791 | ||
c4088ebd | 792 | /* Caller must hold page table lock. */ |
4897c765 | 793 | bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, |
97ae1749 | 794 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, |
5918d10a | 795 | struct page *zero_page) |
fc9fe822 KS |
796 | { |
797 | pmd_t entry; | |
7c414164 AM |
798 | if (!pmd_none(*pmd)) |
799 | return false; | |
5918d10a | 800 | entry = mk_pmd(zero_page, vma->vm_page_prot); |
fc9fe822 | 801 | entry = pmd_mkhuge(entry); |
6b0b50b0 | 802 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
fc9fe822 | 803 | set_pmd_at(mm, haddr, pmd, entry); |
e1f56c89 | 804 | atomic_long_inc(&mm->nr_ptes); |
7c414164 | 805 | return true; |
fc9fe822 KS |
806 | } |
807 | ||
71e3aac0 AA |
808 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, |
809 | unsigned long address, pmd_t *pmd, | |
810 | unsigned int flags) | |
811 | { | |
077fcf11 | 812 | gfp_t gfp; |
71e3aac0 AA |
813 | struct page *page; |
814 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
71e3aac0 | 815 | |
128ec037 | 816 | if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) |
c0292554 | 817 | return VM_FAULT_FALLBACK; |
128ec037 KS |
818 | if (unlikely(anon_vma_prepare(vma))) |
819 | return VM_FAULT_OOM; | |
6d50e60c | 820 | if (unlikely(khugepaged_enter(vma, vma->vm_flags))) |
128ec037 | 821 | return VM_FAULT_OOM; |
593befa6 | 822 | if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) && |
128ec037 | 823 | transparent_hugepage_use_zero_page()) { |
c4088ebd | 824 | spinlock_t *ptl; |
128ec037 KS |
825 | pgtable_t pgtable; |
826 | struct page *zero_page; | |
827 | bool set; | |
6b251fc9 | 828 | int ret; |
128ec037 KS |
829 | pgtable = pte_alloc_one(mm, haddr); |
830 | if (unlikely(!pgtable)) | |
ba76149f | 831 | return VM_FAULT_OOM; |
128ec037 KS |
832 | zero_page = get_huge_zero_page(); |
833 | if (unlikely(!zero_page)) { | |
834 | pte_free(mm, pgtable); | |
81ab4201 | 835 | count_vm_event(THP_FAULT_FALLBACK); |
c0292554 | 836 | return VM_FAULT_FALLBACK; |
b9bbfbe3 | 837 | } |
c4088ebd | 838 | ptl = pmd_lock(mm, pmd); |
6b251fc9 AA |
839 | ret = 0; |
840 | set = false; | |
841 | if (pmd_none(*pmd)) { | |
842 | if (userfaultfd_missing(vma)) { | |
843 | spin_unlock(ptl); | |
230c92a8 | 844 | ret = handle_userfault(vma, address, flags, |
6b251fc9 AA |
845 | VM_UFFD_MISSING); |
846 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
847 | } else { | |
848 | set_huge_zero_page(pgtable, mm, vma, | |
849 | haddr, pmd, | |
850 | zero_page); | |
851 | spin_unlock(ptl); | |
852 | set = true; | |
853 | } | |
854 | } else | |
855 | spin_unlock(ptl); | |
128ec037 KS |
856 | if (!set) { |
857 | pte_free(mm, pgtable); | |
858 | put_huge_zero_page(); | |
edad9d2c | 859 | } |
6b251fc9 | 860 | return ret; |
71e3aac0 | 861 | } |
077fcf11 AK |
862 | gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0); |
863 | page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); | |
128ec037 KS |
864 | if (unlikely(!page)) { |
865 | count_vm_event(THP_FAULT_FALLBACK); | |
c0292554 | 866 | return VM_FAULT_FALLBACK; |
128ec037 | 867 | } |
230c92a8 AA |
868 | return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp, |
869 | flags); | |
71e3aac0 AA |
870 | } |
871 | ||
872 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, | |
873 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
874 | struct vm_area_struct *vma) | |
875 | { | |
c4088ebd | 876 | spinlock_t *dst_ptl, *src_ptl; |
71e3aac0 AA |
877 | struct page *src_page; |
878 | pmd_t pmd; | |
879 | pgtable_t pgtable; | |
880 | int ret; | |
881 | ||
882 | ret = -ENOMEM; | |
883 | pgtable = pte_alloc_one(dst_mm, addr); | |
884 | if (unlikely(!pgtable)) | |
885 | goto out; | |
886 | ||
c4088ebd KS |
887 | dst_ptl = pmd_lock(dst_mm, dst_pmd); |
888 | src_ptl = pmd_lockptr(src_mm, src_pmd); | |
889 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
71e3aac0 AA |
890 | |
891 | ret = -EAGAIN; | |
892 | pmd = *src_pmd; | |
893 | if (unlikely(!pmd_trans_huge(pmd))) { | |
894 | pte_free(dst_mm, pgtable); | |
895 | goto out_unlock; | |
896 | } | |
fc9fe822 | 897 | /* |
c4088ebd | 898 | * When page table lock is held, the huge zero pmd should not be |
fc9fe822 KS |
899 | * under splitting since we don't split the page itself, only pmd to |
900 | * a page table. | |
901 | */ | |
902 | if (is_huge_zero_pmd(pmd)) { | |
5918d10a | 903 | struct page *zero_page; |
97ae1749 KS |
904 | /* |
905 | * get_huge_zero_page() will never allocate a new page here, | |
906 | * since we already have a zero page to copy. It just takes a | |
907 | * reference. | |
908 | */ | |
5918d10a | 909 | zero_page = get_huge_zero_page(); |
6b251fc9 | 910 | set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, |
5918d10a | 911 | zero_page); |
fc9fe822 KS |
912 | ret = 0; |
913 | goto out_unlock; | |
914 | } | |
de466bd6 | 915 | |
71e3aac0 AA |
916 | if (unlikely(pmd_trans_splitting(pmd))) { |
917 | /* split huge page running from under us */ | |
c4088ebd KS |
918 | spin_unlock(src_ptl); |
919 | spin_unlock(dst_ptl); | |
71e3aac0 AA |
920 | pte_free(dst_mm, pgtable); |
921 | ||
922 | wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */ | |
923 | goto out; | |
924 | } | |
925 | src_page = pmd_page(pmd); | |
309381fe | 926 | VM_BUG_ON_PAGE(!PageHead(src_page), src_page); |
71e3aac0 AA |
927 | get_page(src_page); |
928 | page_dup_rmap(src_page); | |
929 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
930 | ||
931 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
932 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
6b0b50b0 | 933 | pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); |
71e3aac0 | 934 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); |
e1f56c89 | 935 | atomic_long_inc(&dst_mm->nr_ptes); |
71e3aac0 AA |
936 | |
937 | ret = 0; | |
938 | out_unlock: | |
c4088ebd KS |
939 | spin_unlock(src_ptl); |
940 | spin_unlock(dst_ptl); | |
71e3aac0 AA |
941 | out: |
942 | return ret; | |
943 | } | |
944 | ||
a1dd450b WD |
945 | void huge_pmd_set_accessed(struct mm_struct *mm, |
946 | struct vm_area_struct *vma, | |
947 | unsigned long address, | |
948 | pmd_t *pmd, pmd_t orig_pmd, | |
949 | int dirty) | |
950 | { | |
c4088ebd | 951 | spinlock_t *ptl; |
a1dd450b WD |
952 | pmd_t entry; |
953 | unsigned long haddr; | |
954 | ||
c4088ebd | 955 | ptl = pmd_lock(mm, pmd); |
a1dd450b WD |
956 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
957 | goto unlock; | |
958 | ||
959 | entry = pmd_mkyoung(orig_pmd); | |
960 | haddr = address & HPAGE_PMD_MASK; | |
961 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty)) | |
962 | update_mmu_cache_pmd(vma, address, pmd); | |
963 | ||
964 | unlock: | |
c4088ebd | 965 | spin_unlock(ptl); |
a1dd450b WD |
966 | } |
967 | ||
5338a937 HD |
968 | /* |
969 | * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages | |
970 | * during copy_user_huge_page()'s copy_page_rep(): in the case when | |
971 | * the source page gets split and a tail freed before copy completes. | |
972 | * Called under pmd_lock of checked pmd, so safe from splitting itself. | |
973 | */ | |
974 | static void get_user_huge_page(struct page *page) | |
975 | { | |
976 | if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) { | |
977 | struct page *endpage = page + HPAGE_PMD_NR; | |
978 | ||
979 | atomic_add(HPAGE_PMD_NR, &page->_count); | |
980 | while (++page < endpage) | |
981 | get_huge_page_tail(page); | |
982 | } else { | |
983 | get_page(page); | |
984 | } | |
985 | } | |
986 | ||
987 | static void put_user_huge_page(struct page *page) | |
988 | { | |
989 | if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) { | |
990 | struct page *endpage = page + HPAGE_PMD_NR; | |
991 | ||
992 | while (page < endpage) | |
993 | put_page(page++); | |
994 | } else { | |
995 | put_page(page); | |
996 | } | |
997 | } | |
998 | ||
71e3aac0 AA |
999 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, |
1000 | struct vm_area_struct *vma, | |
1001 | unsigned long address, | |
1002 | pmd_t *pmd, pmd_t orig_pmd, | |
1003 | struct page *page, | |
1004 | unsigned long haddr) | |
1005 | { | |
00501b53 | 1006 | struct mem_cgroup *memcg; |
c4088ebd | 1007 | spinlock_t *ptl; |
71e3aac0 AA |
1008 | pgtable_t pgtable; |
1009 | pmd_t _pmd; | |
1010 | int ret = 0, i; | |
1011 | struct page **pages; | |
2ec74c3e SG |
1012 | unsigned long mmun_start; /* For mmu_notifiers */ |
1013 | unsigned long mmun_end; /* For mmu_notifiers */ | |
71e3aac0 AA |
1014 | |
1015 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
1016 | GFP_KERNEL); | |
1017 | if (unlikely(!pages)) { | |
1018 | ret |= VM_FAULT_OOM; | |
1019 | goto out; | |
1020 | } | |
1021 | ||
1022 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
cc5d462f AK |
1023 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE | |
1024 | __GFP_OTHER_NODE, | |
19ee151e | 1025 | vma, address, page_to_nid(page)); |
b9bbfbe3 | 1026 | if (unlikely(!pages[i] || |
00501b53 JW |
1027 | mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL, |
1028 | &memcg))) { | |
b9bbfbe3 | 1029 | if (pages[i]) |
71e3aac0 | 1030 | put_page(pages[i]); |
b9bbfbe3 | 1031 | while (--i >= 0) { |
00501b53 JW |
1032 | memcg = (void *)page_private(pages[i]); |
1033 | set_page_private(pages[i], 0); | |
1034 | mem_cgroup_cancel_charge(pages[i], memcg); | |
b9bbfbe3 AA |
1035 | put_page(pages[i]); |
1036 | } | |
71e3aac0 AA |
1037 | kfree(pages); |
1038 | ret |= VM_FAULT_OOM; | |
1039 | goto out; | |
1040 | } | |
00501b53 | 1041 | set_page_private(pages[i], (unsigned long)memcg); |
71e3aac0 AA |
1042 | } |
1043 | ||
1044 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1045 | copy_user_highpage(pages[i], page + i, | |
0089e485 | 1046 | haddr + PAGE_SIZE * i, vma); |
71e3aac0 AA |
1047 | __SetPageUptodate(pages[i]); |
1048 | cond_resched(); | |
1049 | } | |
1050 | ||
2ec74c3e SG |
1051 | mmun_start = haddr; |
1052 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1053 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1054 | ||
c4088ebd | 1055 | ptl = pmd_lock(mm, pmd); |
71e3aac0 AA |
1056 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1057 | goto out_free_pages; | |
309381fe | 1058 | VM_BUG_ON_PAGE(!PageHead(page), page); |
71e3aac0 | 1059 | |
8809aa2d | 1060 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
71e3aac0 AA |
1061 | /* leave pmd empty until pte is filled */ |
1062 | ||
6b0b50b0 | 1063 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
71e3aac0 AA |
1064 | pmd_populate(mm, &_pmd, pgtable); |
1065 | ||
1066 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
1067 | pte_t *pte, entry; | |
1068 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
1069 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
00501b53 JW |
1070 | memcg = (void *)page_private(pages[i]); |
1071 | set_page_private(pages[i], 0); | |
71e3aac0 | 1072 | page_add_new_anon_rmap(pages[i], vma, haddr); |
00501b53 JW |
1073 | mem_cgroup_commit_charge(pages[i], memcg, false); |
1074 | lru_cache_add_active_or_unevictable(pages[i], vma); | |
71e3aac0 AA |
1075 | pte = pte_offset_map(&_pmd, haddr); |
1076 | VM_BUG_ON(!pte_none(*pte)); | |
1077 | set_pte_at(mm, haddr, pte, entry); | |
1078 | pte_unmap(pte); | |
1079 | } | |
1080 | kfree(pages); | |
1081 | ||
71e3aac0 AA |
1082 | smp_wmb(); /* make pte visible before pmd */ |
1083 | pmd_populate(mm, pmd, pgtable); | |
1084 | page_remove_rmap(page); | |
c4088ebd | 1085 | spin_unlock(ptl); |
71e3aac0 | 1086 | |
2ec74c3e SG |
1087 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
1088 | ||
71e3aac0 AA |
1089 | ret |= VM_FAULT_WRITE; |
1090 | put_page(page); | |
1091 | ||
1092 | out: | |
1093 | return ret; | |
1094 | ||
1095 | out_free_pages: | |
c4088ebd | 1096 | spin_unlock(ptl); |
2ec74c3e | 1097 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
b9bbfbe3 | 1098 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
00501b53 JW |
1099 | memcg = (void *)page_private(pages[i]); |
1100 | set_page_private(pages[i], 0); | |
1101 | mem_cgroup_cancel_charge(pages[i], memcg); | |
71e3aac0 | 1102 | put_page(pages[i]); |
b9bbfbe3 | 1103 | } |
71e3aac0 AA |
1104 | kfree(pages); |
1105 | goto out; | |
1106 | } | |
1107 | ||
1108 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
1109 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) | |
1110 | { | |
c4088ebd | 1111 | spinlock_t *ptl; |
71e3aac0 | 1112 | int ret = 0; |
93b4796d | 1113 | struct page *page = NULL, *new_page; |
00501b53 | 1114 | struct mem_cgroup *memcg; |
71e3aac0 | 1115 | unsigned long haddr; |
2ec74c3e SG |
1116 | unsigned long mmun_start; /* For mmu_notifiers */ |
1117 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 1118 | gfp_t huge_gfp; /* for allocation and charge */ |
71e3aac0 | 1119 | |
c4088ebd | 1120 | ptl = pmd_lockptr(mm, pmd); |
81d1b09c | 1121 | VM_BUG_ON_VMA(!vma->anon_vma, vma); |
93b4796d KS |
1122 | haddr = address & HPAGE_PMD_MASK; |
1123 | if (is_huge_zero_pmd(orig_pmd)) | |
1124 | goto alloc; | |
c4088ebd | 1125 | spin_lock(ptl); |
71e3aac0 AA |
1126 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1127 | goto out_unlock; | |
1128 | ||
1129 | page = pmd_page(orig_pmd); | |
309381fe | 1130 | VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); |
71e3aac0 AA |
1131 | if (page_mapcount(page) == 1) { |
1132 | pmd_t entry; | |
1133 | entry = pmd_mkyoung(orig_pmd); | |
1134 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
1135 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) | |
b113da65 | 1136 | update_mmu_cache_pmd(vma, address, pmd); |
71e3aac0 AA |
1137 | ret |= VM_FAULT_WRITE; |
1138 | goto out_unlock; | |
1139 | } | |
5338a937 | 1140 | get_user_huge_page(page); |
c4088ebd | 1141 | spin_unlock(ptl); |
93b4796d | 1142 | alloc: |
71e3aac0 | 1143 | if (transparent_hugepage_enabled(vma) && |
077fcf11 | 1144 | !transparent_hugepage_debug_cow()) { |
3b363692 MH |
1145 | huge_gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0); |
1146 | new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); | |
077fcf11 | 1147 | } else |
71e3aac0 AA |
1148 | new_page = NULL; |
1149 | ||
1150 | if (unlikely(!new_page)) { | |
eecc1e42 | 1151 | if (!page) { |
e9b71ca9 KS |
1152 | split_huge_page_pmd(vma, address, pmd); |
1153 | ret |= VM_FAULT_FALLBACK; | |
93b4796d KS |
1154 | } else { |
1155 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, | |
1156 | pmd, orig_pmd, page, haddr); | |
9845cbbd | 1157 | if (ret & VM_FAULT_OOM) { |
93b4796d | 1158 | split_huge_page(page); |
9845cbbd KS |
1159 | ret |= VM_FAULT_FALLBACK; |
1160 | } | |
5338a937 | 1161 | put_user_huge_page(page); |
93b4796d | 1162 | } |
17766dde | 1163 | count_vm_event(THP_FAULT_FALLBACK); |
71e3aac0 AA |
1164 | goto out; |
1165 | } | |
1166 | ||
3b363692 | 1167 | if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg))) { |
b9bbfbe3 | 1168 | put_page(new_page); |
93b4796d KS |
1169 | if (page) { |
1170 | split_huge_page(page); | |
5338a937 | 1171 | put_user_huge_page(page); |
9845cbbd KS |
1172 | } else |
1173 | split_huge_page_pmd(vma, address, pmd); | |
1174 | ret |= VM_FAULT_FALLBACK; | |
17766dde | 1175 | count_vm_event(THP_FAULT_FALLBACK); |
b9bbfbe3 AA |
1176 | goto out; |
1177 | } | |
1178 | ||
17766dde DR |
1179 | count_vm_event(THP_FAULT_ALLOC); |
1180 | ||
eecc1e42 | 1181 | if (!page) |
93b4796d KS |
1182 | clear_huge_page(new_page, haddr, HPAGE_PMD_NR); |
1183 | else | |
1184 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); | |
71e3aac0 AA |
1185 | __SetPageUptodate(new_page); |
1186 | ||
2ec74c3e SG |
1187 | mmun_start = haddr; |
1188 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1189 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1190 | ||
c4088ebd | 1191 | spin_lock(ptl); |
93b4796d | 1192 | if (page) |
5338a937 | 1193 | put_user_huge_page(page); |
b9bbfbe3 | 1194 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { |
c4088ebd | 1195 | spin_unlock(ptl); |
00501b53 | 1196 | mem_cgroup_cancel_charge(new_page, memcg); |
71e3aac0 | 1197 | put_page(new_page); |
2ec74c3e | 1198 | goto out_mn; |
b9bbfbe3 | 1199 | } else { |
71e3aac0 | 1200 | pmd_t entry; |
3122359a KS |
1201 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); |
1202 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
8809aa2d | 1203 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
71e3aac0 | 1204 | page_add_new_anon_rmap(new_page, vma, haddr); |
00501b53 JW |
1205 | mem_cgroup_commit_charge(new_page, memcg, false); |
1206 | lru_cache_add_active_or_unevictable(new_page, vma); | |
71e3aac0 | 1207 | set_pmd_at(mm, haddr, pmd, entry); |
b113da65 | 1208 | update_mmu_cache_pmd(vma, address, pmd); |
eecc1e42 | 1209 | if (!page) { |
93b4796d | 1210 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
97ae1749 KS |
1211 | put_huge_zero_page(); |
1212 | } else { | |
309381fe | 1213 | VM_BUG_ON_PAGE(!PageHead(page), page); |
93b4796d KS |
1214 | page_remove_rmap(page); |
1215 | put_page(page); | |
1216 | } | |
71e3aac0 AA |
1217 | ret |= VM_FAULT_WRITE; |
1218 | } | |
c4088ebd | 1219 | spin_unlock(ptl); |
2ec74c3e SG |
1220 | out_mn: |
1221 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
71e3aac0 AA |
1222 | out: |
1223 | return ret; | |
2ec74c3e | 1224 | out_unlock: |
c4088ebd | 1225 | spin_unlock(ptl); |
2ec74c3e | 1226 | return ret; |
71e3aac0 AA |
1227 | } |
1228 | ||
b676b293 | 1229 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, |
71e3aac0 AA |
1230 | unsigned long addr, |
1231 | pmd_t *pmd, | |
1232 | unsigned int flags) | |
1233 | { | |
b676b293 | 1234 | struct mm_struct *mm = vma->vm_mm; |
71e3aac0 AA |
1235 | struct page *page = NULL; |
1236 | ||
c4088ebd | 1237 | assert_spin_locked(pmd_lockptr(mm, pmd)); |
71e3aac0 AA |
1238 | |
1239 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1240 | goto out; | |
1241 | ||
85facf25 KS |
1242 | /* Avoid dumping huge zero page */ |
1243 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) | |
1244 | return ERR_PTR(-EFAULT); | |
1245 | ||
2b4847e7 | 1246 | /* Full NUMA hinting faults to serialise migration in fault paths */ |
8a0516ed | 1247 | if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) |
2b4847e7 MG |
1248 | goto out; |
1249 | ||
71e3aac0 | 1250 | page = pmd_page(*pmd); |
309381fe | 1251 | VM_BUG_ON_PAGE(!PageHead(page), page); |
71e3aac0 AA |
1252 | if (flags & FOLL_TOUCH) { |
1253 | pmd_t _pmd; | |
1254 | /* | |
1255 | * We should set the dirty bit only for FOLL_WRITE but | |
1256 | * for now the dirty bit in the pmd is meaningless. | |
1257 | * And if the dirty bit will become meaningful and | |
1258 | * we'll only set it with FOLL_WRITE, an atomic | |
1259 | * set_bit will be required on the pmd to set the | |
1260 | * young bit, instead of the current set_pmd_at. | |
1261 | */ | |
1262 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
8663890a AK |
1263 | if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, |
1264 | pmd, _pmd, 1)) | |
1265 | update_mmu_cache_pmd(vma, addr, pmd); | |
71e3aac0 | 1266 | } |
84d33df2 | 1267 | if ((flags & FOLL_POPULATE) && (vma->vm_flags & VM_LOCKED)) { |
b676b293 DR |
1268 | if (page->mapping && trylock_page(page)) { |
1269 | lru_add_drain(); | |
1270 | if (page->mapping) | |
1271 | mlock_vma_page(page); | |
1272 | unlock_page(page); | |
1273 | } | |
1274 | } | |
71e3aac0 | 1275 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
309381fe | 1276 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
71e3aac0 | 1277 | if (flags & FOLL_GET) |
70b50f94 | 1278 | get_page_foll(page); |
71e3aac0 AA |
1279 | |
1280 | out: | |
1281 | return page; | |
1282 | } | |
1283 | ||
d10e63f2 | 1284 | /* NUMA hinting page fault entry point for trans huge pmds */ |
4daae3b4 MG |
1285 | int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, |
1286 | unsigned long addr, pmd_t pmd, pmd_t *pmdp) | |
d10e63f2 | 1287 | { |
c4088ebd | 1288 | spinlock_t *ptl; |
b8916634 | 1289 | struct anon_vma *anon_vma = NULL; |
b32967ff | 1290 | struct page *page; |
d10e63f2 | 1291 | unsigned long haddr = addr & HPAGE_PMD_MASK; |
8191acbd | 1292 | int page_nid = -1, this_nid = numa_node_id(); |
90572890 | 1293 | int target_nid, last_cpupid = -1; |
8191acbd MG |
1294 | bool page_locked; |
1295 | bool migrated = false; | |
b191f9b1 | 1296 | bool was_writable; |
6688cc05 | 1297 | int flags = 0; |
d10e63f2 | 1298 | |
c0e7cad9 MG |
1299 | /* A PROT_NONE fault should not end up here */ |
1300 | BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))); | |
1301 | ||
c4088ebd | 1302 | ptl = pmd_lock(mm, pmdp); |
d10e63f2 MG |
1303 | if (unlikely(!pmd_same(pmd, *pmdp))) |
1304 | goto out_unlock; | |
1305 | ||
de466bd6 MG |
1306 | /* |
1307 | * If there are potential migrations, wait for completion and retry | |
1308 | * without disrupting NUMA hinting information. Do not relock and | |
1309 | * check_same as the page may no longer be mapped. | |
1310 | */ | |
1311 | if (unlikely(pmd_trans_migrating(*pmdp))) { | |
5d833062 | 1312 | page = pmd_page(*pmdp); |
de466bd6 | 1313 | spin_unlock(ptl); |
5d833062 | 1314 | wait_on_page_locked(page); |
de466bd6 MG |
1315 | goto out; |
1316 | } | |
1317 | ||
d10e63f2 | 1318 | page = pmd_page(pmd); |
a1a46184 | 1319 | BUG_ON(is_huge_zero_page(page)); |
8191acbd | 1320 | page_nid = page_to_nid(page); |
90572890 | 1321 | last_cpupid = page_cpupid_last(page); |
03c5a6e1 | 1322 | count_vm_numa_event(NUMA_HINT_FAULTS); |
04bb2f94 | 1323 | if (page_nid == this_nid) { |
03c5a6e1 | 1324 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
04bb2f94 RR |
1325 | flags |= TNF_FAULT_LOCAL; |
1326 | } | |
4daae3b4 | 1327 | |
bea66fbd MG |
1328 | /* See similar comment in do_numa_page for explanation */ |
1329 | if (!(vma->vm_flags & VM_WRITE)) | |
6688cc05 PZ |
1330 | flags |= TNF_NO_GROUP; |
1331 | ||
ff9042b1 MG |
1332 | /* |
1333 | * Acquire the page lock to serialise THP migrations but avoid dropping | |
1334 | * page_table_lock if at all possible | |
1335 | */ | |
b8916634 MG |
1336 | page_locked = trylock_page(page); |
1337 | target_nid = mpol_misplaced(page, vma, haddr); | |
1338 | if (target_nid == -1) { | |
1339 | /* If the page was locked, there are no parallel migrations */ | |
a54a407f | 1340 | if (page_locked) |
b8916634 | 1341 | goto clear_pmdnuma; |
2b4847e7 | 1342 | } |
4daae3b4 | 1343 | |
de466bd6 | 1344 | /* Migration could have started since the pmd_trans_migrating check */ |
2b4847e7 | 1345 | if (!page_locked) { |
c4088ebd | 1346 | spin_unlock(ptl); |
b8916634 | 1347 | wait_on_page_locked(page); |
a54a407f | 1348 | page_nid = -1; |
b8916634 MG |
1349 | goto out; |
1350 | } | |
1351 | ||
2b4847e7 MG |
1352 | /* |
1353 | * Page is misplaced. Page lock serialises migrations. Acquire anon_vma | |
1354 | * to serialises splits | |
1355 | */ | |
b8916634 | 1356 | get_page(page); |
c4088ebd | 1357 | spin_unlock(ptl); |
b8916634 | 1358 | anon_vma = page_lock_anon_vma_read(page); |
4daae3b4 | 1359 | |
c69307d5 | 1360 | /* Confirm the PMD did not change while page_table_lock was released */ |
c4088ebd | 1361 | spin_lock(ptl); |
b32967ff MG |
1362 | if (unlikely(!pmd_same(pmd, *pmdp))) { |
1363 | unlock_page(page); | |
1364 | put_page(page); | |
a54a407f | 1365 | page_nid = -1; |
4daae3b4 | 1366 | goto out_unlock; |
b32967ff | 1367 | } |
ff9042b1 | 1368 | |
c3a489ca MG |
1369 | /* Bail if we fail to protect against THP splits for any reason */ |
1370 | if (unlikely(!anon_vma)) { | |
1371 | put_page(page); | |
1372 | page_nid = -1; | |
1373 | goto clear_pmdnuma; | |
1374 | } | |
1375 | ||
a54a407f MG |
1376 | /* |
1377 | * Migrate the THP to the requested node, returns with page unlocked | |
8a0516ed | 1378 | * and access rights restored. |
a54a407f | 1379 | */ |
c4088ebd | 1380 | spin_unlock(ptl); |
b32967ff | 1381 | migrated = migrate_misplaced_transhuge_page(mm, vma, |
340ef390 | 1382 | pmdp, pmd, addr, page, target_nid); |
6688cc05 PZ |
1383 | if (migrated) { |
1384 | flags |= TNF_MIGRATED; | |
8191acbd | 1385 | page_nid = target_nid; |
074c2381 MG |
1386 | } else |
1387 | flags |= TNF_MIGRATE_FAIL; | |
b32967ff | 1388 | |
8191acbd | 1389 | goto out; |
b32967ff | 1390 | clear_pmdnuma: |
a54a407f | 1391 | BUG_ON(!PageLocked(page)); |
b191f9b1 | 1392 | was_writable = pmd_write(pmd); |
4d942466 | 1393 | pmd = pmd_modify(pmd, vma->vm_page_prot); |
b7b04004 | 1394 | pmd = pmd_mkyoung(pmd); |
b191f9b1 MG |
1395 | if (was_writable) |
1396 | pmd = pmd_mkwrite(pmd); | |
d10e63f2 | 1397 | set_pmd_at(mm, haddr, pmdp, pmd); |
d10e63f2 | 1398 | update_mmu_cache_pmd(vma, addr, pmdp); |
a54a407f | 1399 | unlock_page(page); |
d10e63f2 | 1400 | out_unlock: |
c4088ebd | 1401 | spin_unlock(ptl); |
b8916634 MG |
1402 | |
1403 | out: | |
1404 | if (anon_vma) | |
1405 | page_unlock_anon_vma_read(anon_vma); | |
1406 | ||
8191acbd | 1407 | if (page_nid != -1) |
6688cc05 | 1408 | task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags); |
8191acbd | 1409 | |
d10e63f2 MG |
1410 | return 0; |
1411 | } | |
1412 | ||
71e3aac0 | 1413 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
f21760b1 | 1414 | pmd_t *pmd, unsigned long addr) |
71e3aac0 | 1415 | { |
bf929152 | 1416 | spinlock_t *ptl; |
71e3aac0 AA |
1417 | int ret = 0; |
1418 | ||
bf929152 | 1419 | if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) { |
025c5b24 | 1420 | pgtable_t pgtable; |
f5c8ad47 | 1421 | pmd_t orig_pmd; |
a6bf2bb0 AK |
1422 | /* |
1423 | * For architectures like ppc64 we look at deposited pgtable | |
8809aa2d | 1424 | * when calling pmdp_huge_get_and_clear. So do the |
a6bf2bb0 AK |
1425 | * pgtable_trans_huge_withdraw after finishing pmdp related |
1426 | * operations. | |
1427 | */ | |
8809aa2d AK |
1428 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, |
1429 | tlb->fullmm); | |
025c5b24 | 1430 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); |
4897c765 MW |
1431 | if (vma_is_dax(vma)) { |
1432 | if (is_huge_zero_pmd(orig_pmd)) { | |
1433 | pgtable = NULL; | |
1434 | } else { | |
1435 | spin_unlock(ptl); | |
1436 | return 1; | |
1437 | } | |
1438 | } else { | |
1439 | pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd); | |
1440 | } | |
479f0abb | 1441 | if (is_huge_zero_pmd(orig_pmd)) { |
e1f56c89 | 1442 | atomic_long_dec(&tlb->mm->nr_ptes); |
bf929152 | 1443 | spin_unlock(ptl); |
97ae1749 | 1444 | put_huge_zero_page(); |
479f0abb | 1445 | } else { |
4897c765 | 1446 | struct page *page = pmd_page(orig_pmd); |
479f0abb | 1447 | page_remove_rmap(page); |
309381fe | 1448 | VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); |
479f0abb | 1449 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); |
309381fe | 1450 | VM_BUG_ON_PAGE(!PageHead(page), page); |
e1f56c89 | 1451 | atomic_long_dec(&tlb->mm->nr_ptes); |
bf929152 | 1452 | spin_unlock(ptl); |
479f0abb KS |
1453 | tlb_remove_page(tlb, page); |
1454 | } | |
4897c765 MW |
1455 | if (pgtable) |
1456 | pte_free(tlb->mm, pgtable); | |
025c5b24 NH |
1457 | ret = 1; |
1458 | } | |
71e3aac0 AA |
1459 | return ret; |
1460 | } | |
1461 | ||
37a1c49a AA |
1462 | int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, |
1463 | unsigned long old_addr, | |
1464 | unsigned long new_addr, unsigned long old_end, | |
1465 | pmd_t *old_pmd, pmd_t *new_pmd) | |
1466 | { | |
bf929152 | 1467 | spinlock_t *old_ptl, *new_ptl; |
37a1c49a AA |
1468 | int ret = 0; |
1469 | pmd_t pmd; | |
1470 | ||
1471 | struct mm_struct *mm = vma->vm_mm; | |
1472 | ||
1473 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1474 | (new_addr & ~HPAGE_PMD_MASK) || | |
1475 | old_end - old_addr < HPAGE_PMD_SIZE || | |
1476 | (new_vma->vm_flags & VM_NOHUGEPAGE)) | |
1477 | goto out; | |
1478 | ||
1479 | /* | |
1480 | * The destination pmd shouldn't be established, free_pgtables() | |
1481 | * should have release it. | |
1482 | */ | |
1483 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1484 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
1485 | goto out; | |
1486 | } | |
1487 | ||
bf929152 KS |
1488 | /* |
1489 | * We don't have to worry about the ordering of src and dst | |
1490 | * ptlocks because exclusive mmap_sem prevents deadlock. | |
1491 | */ | |
1492 | ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl); | |
025c5b24 | 1493 | if (ret == 1) { |
bf929152 KS |
1494 | new_ptl = pmd_lockptr(mm, new_pmd); |
1495 | if (new_ptl != old_ptl) | |
1496 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); | |
8809aa2d | 1497 | pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); |
025c5b24 | 1498 | VM_BUG_ON(!pmd_none(*new_pmd)); |
3592806c | 1499 | |
b3084f4d AK |
1500 | if (pmd_move_must_withdraw(new_ptl, old_ptl)) { |
1501 | pgtable_t pgtable; | |
3592806c KS |
1502 | pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); |
1503 | pgtable_trans_huge_deposit(mm, new_pmd, pgtable); | |
3592806c | 1504 | } |
b3084f4d AK |
1505 | set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); |
1506 | if (new_ptl != old_ptl) | |
1507 | spin_unlock(new_ptl); | |
bf929152 | 1508 | spin_unlock(old_ptl); |
37a1c49a AA |
1509 | } |
1510 | out: | |
1511 | return ret; | |
1512 | } | |
1513 | ||
f123d74a MG |
1514 | /* |
1515 | * Returns | |
1516 | * - 0 if PMD could not be locked | |
1517 | * - 1 if PMD was locked but protections unchange and TLB flush unnecessary | |
1518 | * - HPAGE_PMD_NR is protections changed and TLB flush necessary | |
1519 | */ | |
cd7548ab | 1520 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
e944fd67 | 1521 | unsigned long addr, pgprot_t newprot, int prot_numa) |
cd7548ab JW |
1522 | { |
1523 | struct mm_struct *mm = vma->vm_mm; | |
bf929152 | 1524 | spinlock_t *ptl; |
cd7548ab JW |
1525 | int ret = 0; |
1526 | ||
bf929152 | 1527 | if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) { |
025c5b24 | 1528 | pmd_t entry; |
b191f9b1 | 1529 | bool preserve_write = prot_numa && pmd_write(*pmd); |
ba68bc01 | 1530 | ret = 1; |
e944fd67 MG |
1531 | |
1532 | /* | |
1533 | * Avoid trapping faults against the zero page. The read-only | |
1534 | * data is likely to be read-cached on the local CPU and | |
1535 | * local/remote hits to the zero page are not interesting. | |
1536 | */ | |
1537 | if (prot_numa && is_huge_zero_pmd(*pmd)) { | |
1538 | spin_unlock(ptl); | |
ba68bc01 | 1539 | return ret; |
e944fd67 MG |
1540 | } |
1541 | ||
10c1045f | 1542 | if (!prot_numa || !pmd_protnone(*pmd)) { |
8809aa2d | 1543 | entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd); |
10c1045f | 1544 | entry = pmd_modify(entry, newprot); |
b191f9b1 MG |
1545 | if (preserve_write) |
1546 | entry = pmd_mkwrite(entry); | |
10c1045f MG |
1547 | ret = HPAGE_PMD_NR; |
1548 | set_pmd_at(mm, addr, pmd, entry); | |
b191f9b1 | 1549 | BUG_ON(!preserve_write && pmd_write(entry)); |
10c1045f | 1550 | } |
bf929152 | 1551 | spin_unlock(ptl); |
025c5b24 NH |
1552 | } |
1553 | ||
1554 | return ret; | |
1555 | } | |
1556 | ||
1557 | /* | |
1558 | * Returns 1 if a given pmd maps a stable (not under splitting) thp. | |
1559 | * Returns -1 if it maps a thp under splitting. Returns 0 otherwise. | |
1560 | * | |
1561 | * Note that if it returns 1, this routine returns without unlocking page | |
1562 | * table locks. So callers must unlock them. | |
1563 | */ | |
bf929152 KS |
1564 | int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma, |
1565 | spinlock_t **ptl) | |
025c5b24 | 1566 | { |
bf929152 | 1567 | *ptl = pmd_lock(vma->vm_mm, pmd); |
cd7548ab JW |
1568 | if (likely(pmd_trans_huge(*pmd))) { |
1569 | if (unlikely(pmd_trans_splitting(*pmd))) { | |
bf929152 | 1570 | spin_unlock(*ptl); |
cd7548ab | 1571 | wait_split_huge_page(vma->anon_vma, pmd); |
025c5b24 | 1572 | return -1; |
cd7548ab | 1573 | } else { |
025c5b24 NH |
1574 | /* Thp mapped by 'pmd' is stable, so we can |
1575 | * handle it as it is. */ | |
1576 | return 1; | |
cd7548ab | 1577 | } |
025c5b24 | 1578 | } |
bf929152 | 1579 | spin_unlock(*ptl); |
025c5b24 | 1580 | return 0; |
cd7548ab JW |
1581 | } |
1582 | ||
117b0791 KS |
1583 | /* |
1584 | * This function returns whether a given @page is mapped onto the @address | |
1585 | * in the virtual space of @mm. | |
1586 | * | |
1587 | * When it's true, this function returns *pmd with holding the page table lock | |
1588 | * and passing it back to the caller via @ptl. | |
1589 | * If it's false, returns NULL without holding the page table lock. | |
1590 | */ | |
71e3aac0 AA |
1591 | pmd_t *page_check_address_pmd(struct page *page, |
1592 | struct mm_struct *mm, | |
1593 | unsigned long address, | |
117b0791 KS |
1594 | enum page_check_address_pmd_flag flag, |
1595 | spinlock_t **ptl) | |
71e3aac0 | 1596 | { |
b5a8cad3 KS |
1597 | pgd_t *pgd; |
1598 | pud_t *pud; | |
117b0791 | 1599 | pmd_t *pmd; |
71e3aac0 AA |
1600 | |
1601 | if (address & ~HPAGE_PMD_MASK) | |
117b0791 | 1602 | return NULL; |
71e3aac0 | 1603 | |
b5a8cad3 KS |
1604 | pgd = pgd_offset(mm, address); |
1605 | if (!pgd_present(*pgd)) | |
117b0791 | 1606 | return NULL; |
b5a8cad3 KS |
1607 | pud = pud_offset(pgd, address); |
1608 | if (!pud_present(*pud)) | |
1609 | return NULL; | |
1610 | pmd = pmd_offset(pud, address); | |
1611 | ||
117b0791 | 1612 | *ptl = pmd_lock(mm, pmd); |
b5a8cad3 | 1613 | if (!pmd_present(*pmd)) |
117b0791 | 1614 | goto unlock; |
71e3aac0 | 1615 | if (pmd_page(*pmd) != page) |
117b0791 | 1616 | goto unlock; |
94fcc585 AA |
1617 | /* |
1618 | * split_vma() may create temporary aliased mappings. There is | |
1619 | * no risk as long as all huge pmd are found and have their | |
1620 | * splitting bit set before __split_huge_page_refcount | |
1621 | * runs. Finding the same huge pmd more than once during the | |
1622 | * same rmap walk is not a problem. | |
1623 | */ | |
1624 | if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG && | |
1625 | pmd_trans_splitting(*pmd)) | |
117b0791 | 1626 | goto unlock; |
71e3aac0 AA |
1627 | if (pmd_trans_huge(*pmd)) { |
1628 | VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG && | |
1629 | !pmd_trans_splitting(*pmd)); | |
117b0791 | 1630 | return pmd; |
71e3aac0 | 1631 | } |
117b0791 KS |
1632 | unlock: |
1633 | spin_unlock(*ptl); | |
1634 | return NULL; | |
71e3aac0 AA |
1635 | } |
1636 | ||
1637 | static int __split_huge_page_splitting(struct page *page, | |
1638 | struct vm_area_struct *vma, | |
1639 | unsigned long address) | |
1640 | { | |
1641 | struct mm_struct *mm = vma->vm_mm; | |
117b0791 | 1642 | spinlock_t *ptl; |
71e3aac0 AA |
1643 | pmd_t *pmd; |
1644 | int ret = 0; | |
2ec74c3e SG |
1645 | /* For mmu_notifiers */ |
1646 | const unsigned long mmun_start = address; | |
1647 | const unsigned long mmun_end = address + HPAGE_PMD_SIZE; | |
71e3aac0 | 1648 | |
2ec74c3e | 1649 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
71e3aac0 | 1650 | pmd = page_check_address_pmd(page, mm, address, |
117b0791 | 1651 | PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl); |
71e3aac0 AA |
1652 | if (pmd) { |
1653 | /* | |
1654 | * We can't temporarily set the pmd to null in order | |
1655 | * to split it, the pmd must remain marked huge at all | |
1656 | * times or the VM won't take the pmd_trans_huge paths | |
5a505085 | 1657 | * and it won't wait on the anon_vma->root->rwsem to |
71e3aac0 AA |
1658 | * serialize against split_huge_page*. |
1659 | */ | |
2ec74c3e | 1660 | pmdp_splitting_flush(vma, address, pmd); |
34ee645e | 1661 | |
71e3aac0 | 1662 | ret = 1; |
117b0791 | 1663 | spin_unlock(ptl); |
71e3aac0 | 1664 | } |
2ec74c3e | 1665 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
71e3aac0 AA |
1666 | |
1667 | return ret; | |
1668 | } | |
1669 | ||
5bc7b8ac SL |
1670 | static void __split_huge_page_refcount(struct page *page, |
1671 | struct list_head *list) | |
71e3aac0 AA |
1672 | { |
1673 | int i; | |
71e3aac0 | 1674 | struct zone *zone = page_zone(page); |
fa9add64 | 1675 | struct lruvec *lruvec; |
70b50f94 | 1676 | int tail_count = 0; |
71e3aac0 AA |
1677 | |
1678 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
1679 | spin_lock_irq(&zone->lru_lock); | |
fa9add64 HD |
1680 | lruvec = mem_cgroup_page_lruvec(page, zone); |
1681 | ||
71e3aac0 | 1682 | compound_lock(page); |
e94c8a9c KH |
1683 | /* complete memcg works before add pages to LRU */ |
1684 | mem_cgroup_split_huge_fixup(page); | |
71e3aac0 | 1685 | |
45676885 | 1686 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { |
71e3aac0 AA |
1687 | struct page *page_tail = page + i; |
1688 | ||
70b50f94 AA |
1689 | /* tail_page->_mapcount cannot change */ |
1690 | BUG_ON(page_mapcount(page_tail) < 0); | |
1691 | tail_count += page_mapcount(page_tail); | |
1692 | /* check for overflow */ | |
1693 | BUG_ON(tail_count < 0); | |
1694 | BUG_ON(atomic_read(&page_tail->_count) != 0); | |
1695 | /* | |
1696 | * tail_page->_count is zero and not changing from | |
1697 | * under us. But get_page_unless_zero() may be running | |
1698 | * from under us on the tail_page. If we used | |
1699 | * atomic_set() below instead of atomic_add(), we | |
1700 | * would then run atomic_set() concurrently with | |
1701 | * get_page_unless_zero(), and atomic_set() is | |
1702 | * implemented in C not using locked ops. spin_unlock | |
1703 | * on x86 sometime uses locked ops because of PPro | |
1704 | * errata 66, 92, so unless somebody can guarantee | |
1705 | * atomic_set() here would be safe on all archs (and | |
1706 | * not only on x86), it's safer to use atomic_add(). | |
1707 | */ | |
1708 | atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1, | |
1709 | &page_tail->_count); | |
71e3aac0 AA |
1710 | |
1711 | /* after clearing PageTail the gup refcount can be released */ | |
3a79d52a | 1712 | smp_mb__after_atomic(); |
71e3aac0 | 1713 | |
f4c18e6f | 1714 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; |
71e3aac0 AA |
1715 | page_tail->flags |= (page->flags & |
1716 | ((1L << PG_referenced) | | |
1717 | (1L << PG_swapbacked) | | |
1718 | (1L << PG_mlocked) | | |
e180cf80 KS |
1719 | (1L << PG_uptodate) | |
1720 | (1L << PG_active) | | |
1721 | (1L << PG_unevictable))); | |
71e3aac0 AA |
1722 | page_tail->flags |= (1L << PG_dirty); |
1723 | ||
70b50f94 | 1724 | /* clear PageTail before overwriting first_page */ |
71e3aac0 AA |
1725 | smp_wmb(); |
1726 | ||
1727 | /* | |
1728 | * __split_huge_page_splitting() already set the | |
1729 | * splitting bit in all pmd that could map this | |
1730 | * hugepage, that will ensure no CPU can alter the | |
1731 | * mapcount on the head page. The mapcount is only | |
1732 | * accounted in the head page and it has to be | |
1733 | * transferred to all tail pages in the below code. So | |
1734 | * for this code to be safe, the split the mapcount | |
1735 | * can't change. But that doesn't mean userland can't | |
1736 | * keep changing and reading the page contents while | |
1737 | * we transfer the mapcount, so the pmd splitting | |
1738 | * status is achieved setting a reserved bit in the | |
1739 | * pmd, not by clearing the present bit. | |
1740 | */ | |
71e3aac0 AA |
1741 | page_tail->_mapcount = page->_mapcount; |
1742 | ||
1743 | BUG_ON(page_tail->mapping); | |
1744 | page_tail->mapping = page->mapping; | |
1745 | ||
45676885 | 1746 | page_tail->index = page->index + i; |
90572890 | 1747 | page_cpupid_xchg_last(page_tail, page_cpupid_last(page)); |
71e3aac0 AA |
1748 | |
1749 | BUG_ON(!PageAnon(page_tail)); | |
1750 | BUG_ON(!PageUptodate(page_tail)); | |
1751 | BUG_ON(!PageDirty(page_tail)); | |
1752 | BUG_ON(!PageSwapBacked(page_tail)); | |
1753 | ||
5bc7b8ac | 1754 | lru_add_page_tail(page, page_tail, lruvec, list); |
71e3aac0 | 1755 | } |
70b50f94 AA |
1756 | atomic_sub(tail_count, &page->_count); |
1757 | BUG_ON(atomic_read(&page->_count) <= 0); | |
71e3aac0 | 1758 | |
fa9add64 | 1759 | __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1); |
79134171 | 1760 | |
71e3aac0 AA |
1761 | ClearPageCompound(page); |
1762 | compound_unlock(page); | |
1763 | spin_unlock_irq(&zone->lru_lock); | |
1764 | ||
1765 | for (i = 1; i < HPAGE_PMD_NR; i++) { | |
1766 | struct page *page_tail = page + i; | |
1767 | BUG_ON(page_count(page_tail) <= 0); | |
1768 | /* | |
1769 | * Tail pages may be freed if there wasn't any mapping | |
1770 | * like if add_to_swap() is running on a lru page that | |
1771 | * had its mapping zapped. And freeing these pages | |
1772 | * requires taking the lru_lock so we do the put_page | |
1773 | * of the tail pages after the split is complete. | |
1774 | */ | |
1775 | put_page(page_tail); | |
1776 | } | |
1777 | ||
1778 | /* | |
1779 | * Only the head page (now become a regular page) is required | |
1780 | * to be pinned by the caller. | |
1781 | */ | |
1782 | BUG_ON(page_count(page) <= 0); | |
1783 | } | |
1784 | ||
1785 | static int __split_huge_page_map(struct page *page, | |
1786 | struct vm_area_struct *vma, | |
1787 | unsigned long address) | |
1788 | { | |
1789 | struct mm_struct *mm = vma->vm_mm; | |
117b0791 | 1790 | spinlock_t *ptl; |
71e3aac0 AA |
1791 | pmd_t *pmd, _pmd; |
1792 | int ret = 0, i; | |
1793 | pgtable_t pgtable; | |
1794 | unsigned long haddr; | |
1795 | ||
71e3aac0 | 1796 | pmd = page_check_address_pmd(page, mm, address, |
117b0791 | 1797 | PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl); |
71e3aac0 | 1798 | if (pmd) { |
6b0b50b0 | 1799 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
71e3aac0 | 1800 | pmd_populate(mm, &_pmd, pgtable); |
f8303c25 WL |
1801 | if (pmd_write(*pmd)) |
1802 | BUG_ON(page_mapcount(page) != 1); | |
71e3aac0 | 1803 | |
e3ebcf64 GS |
1804 | haddr = address; |
1805 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
71e3aac0 AA |
1806 | pte_t *pte, entry; |
1807 | BUG_ON(PageCompound(page+i)); | |
abc40bd2 | 1808 | /* |
8a0516ed MG |
1809 | * Note that NUMA hinting access restrictions are not |
1810 | * transferred to avoid any possibility of altering | |
1811 | * permissions across VMAs. | |
abc40bd2 | 1812 | */ |
71e3aac0 AA |
1813 | entry = mk_pte(page + i, vma->vm_page_prot); |
1814 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
1815 | if (!pmd_write(*pmd)) | |
1816 | entry = pte_wrprotect(entry); | |
71e3aac0 AA |
1817 | if (!pmd_young(*pmd)) |
1818 | entry = pte_mkold(entry); | |
1819 | pte = pte_offset_map(&_pmd, haddr); | |
1820 | BUG_ON(!pte_none(*pte)); | |
1821 | set_pte_at(mm, haddr, pte, entry); | |
1822 | pte_unmap(pte); | |
1823 | } | |
1824 | ||
71e3aac0 AA |
1825 | smp_wmb(); /* make pte visible before pmd */ |
1826 | /* | |
1827 | * Up to this point the pmd is present and huge and | |
1828 | * userland has the whole access to the hugepage | |
1829 | * during the split (which happens in place). If we | |
1830 | * overwrite the pmd with the not-huge version | |
1831 | * pointing to the pte here (which of course we could | |
1832 | * if all CPUs were bug free), userland could trigger | |
1833 | * a small page size TLB miss on the small sized TLB | |
1834 | * while the hugepage TLB entry is still established | |
1835 | * in the huge TLB. Some CPU doesn't like that. See | |
1836 | * http://support.amd.com/us/Processor_TechDocs/41322.pdf, | |
1837 | * Erratum 383 on page 93. Intel should be safe but is | |
1838 | * also warns that it's only safe if the permission | |
1839 | * and cache attributes of the two entries loaded in | |
1840 | * the two TLB is identical (which should be the case | |
1841 | * here). But it is generally safer to never allow | |
1842 | * small and huge TLB entries for the same virtual | |
1843 | * address to be loaded simultaneously. So instead of | |
1844 | * doing "pmd_populate(); flush_tlb_range();" we first | |
1845 | * mark the current pmd notpresent (atomically because | |
1846 | * here the pmd_trans_huge and pmd_trans_splitting | |
1847 | * must remain set at all times on the pmd until the | |
1848 | * split is complete for this pmd), then we flush the | |
1849 | * SMP TLB and finally we write the non-huge version | |
1850 | * of the pmd entry with pmd_populate. | |
1851 | */ | |
46dcde73 | 1852 | pmdp_invalidate(vma, address, pmd); |
71e3aac0 AA |
1853 | pmd_populate(mm, pmd, pgtable); |
1854 | ret = 1; | |
117b0791 | 1855 | spin_unlock(ptl); |
71e3aac0 | 1856 | } |
71e3aac0 AA |
1857 | |
1858 | return ret; | |
1859 | } | |
1860 | ||
5a505085 | 1861 | /* must be called with anon_vma->root->rwsem held */ |
71e3aac0 | 1862 | static void __split_huge_page(struct page *page, |
5bc7b8ac SL |
1863 | struct anon_vma *anon_vma, |
1864 | struct list_head *list) | |
71e3aac0 AA |
1865 | { |
1866 | int mapcount, mapcount2; | |
bf181b9f | 1867 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
71e3aac0 AA |
1868 | struct anon_vma_chain *avc; |
1869 | ||
1870 | BUG_ON(!PageHead(page)); | |
1871 | BUG_ON(PageTail(page)); | |
1872 | ||
1873 | mapcount = 0; | |
bf181b9f | 1874 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { |
71e3aac0 AA |
1875 | struct vm_area_struct *vma = avc->vma; |
1876 | unsigned long addr = vma_address(page, vma); | |
1877 | BUG_ON(is_vma_temporary_stack(vma)); | |
71e3aac0 AA |
1878 | mapcount += __split_huge_page_splitting(page, vma, addr); |
1879 | } | |
05759d38 AA |
1880 | /* |
1881 | * It is critical that new vmas are added to the tail of the | |
1882 | * anon_vma list. This guarantes that if copy_huge_pmd() runs | |
1883 | * and establishes a child pmd before | |
1884 | * __split_huge_page_splitting() freezes the parent pmd (so if | |
1885 | * we fail to prevent copy_huge_pmd() from running until the | |
1886 | * whole __split_huge_page() is complete), we will still see | |
1887 | * the newly established pmd of the child later during the | |
1888 | * walk, to be able to set it as pmd_trans_splitting too. | |
1889 | */ | |
ff9e43eb | 1890 | if (mapcount != page_mapcount(page)) { |
ae3a8c1c AM |
1891 | pr_err("mapcount %d page_mapcount %d\n", |
1892 | mapcount, page_mapcount(page)); | |
ff9e43eb KS |
1893 | BUG(); |
1894 | } | |
71e3aac0 | 1895 | |
5bc7b8ac | 1896 | __split_huge_page_refcount(page, list); |
71e3aac0 AA |
1897 | |
1898 | mapcount2 = 0; | |
bf181b9f | 1899 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { |
71e3aac0 AA |
1900 | struct vm_area_struct *vma = avc->vma; |
1901 | unsigned long addr = vma_address(page, vma); | |
1902 | BUG_ON(is_vma_temporary_stack(vma)); | |
71e3aac0 AA |
1903 | mapcount2 += __split_huge_page_map(page, vma, addr); |
1904 | } | |
ff9e43eb | 1905 | if (mapcount != mapcount2) { |
ae3a8c1c AM |
1906 | pr_err("mapcount %d mapcount2 %d page_mapcount %d\n", |
1907 | mapcount, mapcount2, page_mapcount(page)); | |
ff9e43eb KS |
1908 | BUG(); |
1909 | } | |
71e3aac0 AA |
1910 | } |
1911 | ||
5bc7b8ac SL |
1912 | /* |
1913 | * Split a hugepage into normal pages. This doesn't change the position of head | |
1914 | * page. If @list is null, tail pages will be added to LRU list, otherwise, to | |
1915 | * @list. Both head page and tail pages will inherit mapping, flags, and so on | |
1916 | * from the hugepage. | |
1917 | * Return 0 if the hugepage is split successfully otherwise return 1. | |
1918 | */ | |
1919 | int split_huge_page_to_list(struct page *page, struct list_head *list) | |
71e3aac0 AA |
1920 | { |
1921 | struct anon_vma *anon_vma; | |
1922 | int ret = 1; | |
1923 | ||
5918d10a | 1924 | BUG_ON(is_huge_zero_page(page)); |
71e3aac0 | 1925 | BUG_ON(!PageAnon(page)); |
062f1af2 MG |
1926 | |
1927 | /* | |
1928 | * The caller does not necessarily hold an mmap_sem that would prevent | |
1929 | * the anon_vma disappearing so we first we take a reference to it | |
1930 | * and then lock the anon_vma for write. This is similar to | |
1931 | * page_lock_anon_vma_read except the write lock is taken to serialise | |
1932 | * against parallel split or collapse operations. | |
1933 | */ | |
1934 | anon_vma = page_get_anon_vma(page); | |
71e3aac0 AA |
1935 | if (!anon_vma) |
1936 | goto out; | |
062f1af2 MG |
1937 | anon_vma_lock_write(anon_vma); |
1938 | ||
71e3aac0 AA |
1939 | ret = 0; |
1940 | if (!PageCompound(page)) | |
1941 | goto out_unlock; | |
1942 | ||
1943 | BUG_ON(!PageSwapBacked(page)); | |
5bc7b8ac | 1944 | __split_huge_page(page, anon_vma, list); |
81ab4201 | 1945 | count_vm_event(THP_SPLIT); |
71e3aac0 AA |
1946 | |
1947 | BUG_ON(PageCompound(page)); | |
1948 | out_unlock: | |
08b52706 | 1949 | anon_vma_unlock_write(anon_vma); |
062f1af2 | 1950 | put_anon_vma(anon_vma); |
71e3aac0 AA |
1951 | out: |
1952 | return ret; | |
1953 | } | |
1954 | ||
9050d7eb | 1955 | #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE) |
78f11a25 | 1956 | |
60ab3244 AA |
1957 | int hugepage_madvise(struct vm_area_struct *vma, |
1958 | unsigned long *vm_flags, int advice) | |
0af4e98b | 1959 | { |
a664b2d8 AA |
1960 | switch (advice) { |
1961 | case MADV_HUGEPAGE: | |
1e1836e8 AT |
1962 | #ifdef CONFIG_S390 |
1963 | /* | |
1964 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
1965 | * can't handle this properly after s390_enable_sie, so we simply | |
1966 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
1967 | */ | |
1968 | if (mm_has_pgste(vma->vm_mm)) | |
1969 | return 0; | |
1970 | #endif | |
a664b2d8 AA |
1971 | /* |
1972 | * Be somewhat over-protective like KSM for now! | |
1973 | */ | |
78f11a25 | 1974 | if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP)) |
a664b2d8 AA |
1975 | return -EINVAL; |
1976 | *vm_flags &= ~VM_NOHUGEPAGE; | |
1977 | *vm_flags |= VM_HUGEPAGE; | |
60ab3244 AA |
1978 | /* |
1979 | * If the vma become good for khugepaged to scan, | |
1980 | * register it here without waiting a page fault that | |
1981 | * may not happen any time soon. | |
1982 | */ | |
6d50e60c | 1983 | if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags))) |
60ab3244 | 1984 | return -ENOMEM; |
a664b2d8 AA |
1985 | break; |
1986 | case MADV_NOHUGEPAGE: | |
1987 | /* | |
1988 | * Be somewhat over-protective like KSM for now! | |
1989 | */ | |
78f11a25 | 1990 | if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP)) |
a664b2d8 AA |
1991 | return -EINVAL; |
1992 | *vm_flags &= ~VM_HUGEPAGE; | |
1993 | *vm_flags |= VM_NOHUGEPAGE; | |
60ab3244 AA |
1994 | /* |
1995 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
1996 | * this vma even if we leave the mm registered in khugepaged if | |
1997 | * it got registered before VM_NOHUGEPAGE was set. | |
1998 | */ | |
a664b2d8 AA |
1999 | break; |
2000 | } | |
0af4e98b AA |
2001 | |
2002 | return 0; | |
2003 | } | |
2004 | ||
ba76149f AA |
2005 | static int __init khugepaged_slab_init(void) |
2006 | { | |
2007 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
2008 | sizeof(struct mm_slot), | |
2009 | __alignof__(struct mm_slot), 0, NULL); | |
2010 | if (!mm_slot_cache) | |
2011 | return -ENOMEM; | |
2012 | ||
2013 | return 0; | |
2014 | } | |
2015 | ||
65ebb64f KS |
2016 | static void __init khugepaged_slab_exit(void) |
2017 | { | |
2018 | kmem_cache_destroy(mm_slot_cache); | |
2019 | } | |
2020 | ||
ba76149f AA |
2021 | static inline struct mm_slot *alloc_mm_slot(void) |
2022 | { | |
2023 | if (!mm_slot_cache) /* initialization failed */ | |
2024 | return NULL; | |
2025 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
2026 | } | |
2027 | ||
2028 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
2029 | { | |
2030 | kmem_cache_free(mm_slot_cache, mm_slot); | |
2031 | } | |
2032 | ||
ba76149f AA |
2033 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) |
2034 | { | |
2035 | struct mm_slot *mm_slot; | |
ba76149f | 2036 | |
b67bfe0d | 2037 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) |
ba76149f AA |
2038 | if (mm == mm_slot->mm) |
2039 | return mm_slot; | |
43b5fbbd | 2040 | |
ba76149f AA |
2041 | return NULL; |
2042 | } | |
2043 | ||
2044 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
2045 | struct mm_slot *mm_slot) | |
2046 | { | |
ba76149f | 2047 | mm_slot->mm = mm; |
43b5fbbd | 2048 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); |
ba76149f AA |
2049 | } |
2050 | ||
2051 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
2052 | { | |
2053 | return atomic_read(&mm->mm_users) == 0; | |
2054 | } | |
2055 | ||
2056 | int __khugepaged_enter(struct mm_struct *mm) | |
2057 | { | |
2058 | struct mm_slot *mm_slot; | |
2059 | int wakeup; | |
2060 | ||
2061 | mm_slot = alloc_mm_slot(); | |
2062 | if (!mm_slot) | |
2063 | return -ENOMEM; | |
2064 | ||
2065 | /* __khugepaged_exit() must not run from under us */ | |
96dad67f | 2066 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); |
ba76149f AA |
2067 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { |
2068 | free_mm_slot(mm_slot); | |
2069 | return 0; | |
2070 | } | |
2071 | ||
2072 | spin_lock(&khugepaged_mm_lock); | |
2073 | insert_to_mm_slots_hash(mm, mm_slot); | |
2074 | /* | |
2075 | * Insert just behind the scanning cursor, to let the area settle | |
2076 | * down a little. | |
2077 | */ | |
2078 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
2079 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
2080 | spin_unlock(&khugepaged_mm_lock); | |
2081 | ||
2082 | atomic_inc(&mm->mm_count); | |
2083 | if (wakeup) | |
2084 | wake_up_interruptible(&khugepaged_wait); | |
2085 | ||
2086 | return 0; | |
2087 | } | |
2088 | ||
6d50e60c DR |
2089 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, |
2090 | unsigned long vm_flags) | |
ba76149f AA |
2091 | { |
2092 | unsigned long hstart, hend; | |
2093 | if (!vma->anon_vma) | |
2094 | /* | |
2095 | * Not yet faulted in so we will register later in the | |
2096 | * page fault if needed. | |
2097 | */ | |
2098 | return 0; | |
78f11a25 | 2099 | if (vma->vm_ops) |
ba76149f AA |
2100 | /* khugepaged not yet working on file or special mappings */ |
2101 | return 0; | |
6d50e60c | 2102 | VM_BUG_ON_VMA(vm_flags & VM_NO_THP, vma); |
ba76149f AA |
2103 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2104 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2105 | if (hstart < hend) | |
6d50e60c | 2106 | return khugepaged_enter(vma, vm_flags); |
ba76149f AA |
2107 | return 0; |
2108 | } | |
2109 | ||
2110 | void __khugepaged_exit(struct mm_struct *mm) | |
2111 | { | |
2112 | struct mm_slot *mm_slot; | |
2113 | int free = 0; | |
2114 | ||
2115 | spin_lock(&khugepaged_mm_lock); | |
2116 | mm_slot = get_mm_slot(mm); | |
2117 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
43b5fbbd | 2118 | hash_del(&mm_slot->hash); |
ba76149f AA |
2119 | list_del(&mm_slot->mm_node); |
2120 | free = 1; | |
2121 | } | |
d788e80a | 2122 | spin_unlock(&khugepaged_mm_lock); |
ba76149f AA |
2123 | |
2124 | if (free) { | |
ba76149f AA |
2125 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); |
2126 | free_mm_slot(mm_slot); | |
2127 | mmdrop(mm); | |
2128 | } else if (mm_slot) { | |
ba76149f AA |
2129 | /* |
2130 | * This is required to serialize against | |
2131 | * khugepaged_test_exit() (which is guaranteed to run | |
2132 | * under mmap sem read mode). Stop here (after we | |
2133 | * return all pagetables will be destroyed) until | |
2134 | * khugepaged has finished working on the pagetables | |
2135 | * under the mmap_sem. | |
2136 | */ | |
2137 | down_write(&mm->mmap_sem); | |
2138 | up_write(&mm->mmap_sem); | |
d788e80a | 2139 | } |
ba76149f AA |
2140 | } |
2141 | ||
2142 | static void release_pte_page(struct page *page) | |
2143 | { | |
2144 | /* 0 stands for page_is_file_cache(page) == false */ | |
2145 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
2146 | unlock_page(page); | |
2147 | putback_lru_page(page); | |
2148 | } | |
2149 | ||
2150 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
2151 | { | |
2152 | while (--_pte >= pte) { | |
2153 | pte_t pteval = *_pte; | |
ca0984ca | 2154 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) |
ba76149f AA |
2155 | release_pte_page(pte_page(pteval)); |
2156 | } | |
2157 | } | |
2158 | ||
ba76149f AA |
2159 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, |
2160 | unsigned long address, | |
2161 | pte_t *pte) | |
2162 | { | |
2163 | struct page *page; | |
2164 | pte_t *_pte; | |
ca0984ca | 2165 | int none_or_zero = 0; |
10359213 | 2166 | bool referenced = false, writable = false; |
ba76149f AA |
2167 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; |
2168 | _pte++, address += PAGE_SIZE) { | |
2169 | pte_t pteval = *_pte; | |
ca0984ca | 2170 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
c1294d05 AA |
2171 | if (!userfaultfd_armed(vma) && |
2172 | ++none_or_zero <= khugepaged_max_ptes_none) | |
ba76149f | 2173 | continue; |
344aa35c | 2174 | else |
ba76149f | 2175 | goto out; |
ba76149f | 2176 | } |
10359213 | 2177 | if (!pte_present(pteval)) |
ba76149f | 2178 | goto out; |
ba76149f | 2179 | page = vm_normal_page(vma, address, pteval); |
344aa35c | 2180 | if (unlikely(!page)) |
ba76149f | 2181 | goto out; |
344aa35c | 2182 | |
309381fe SL |
2183 | VM_BUG_ON_PAGE(PageCompound(page), page); |
2184 | VM_BUG_ON_PAGE(!PageAnon(page), page); | |
2185 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
ba76149f | 2186 | |
ba76149f AA |
2187 | /* |
2188 | * We can do it before isolate_lru_page because the | |
2189 | * page can't be freed from under us. NOTE: PG_lock | |
2190 | * is needed to serialize against split_huge_page | |
2191 | * when invoked from the VM. | |
2192 | */ | |
344aa35c | 2193 | if (!trylock_page(page)) |
ba76149f | 2194 | goto out; |
10359213 EA |
2195 | |
2196 | /* | |
2197 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2198 | * The page must only be referenced by the scanned process | |
2199 | * and page swap cache. | |
2200 | */ | |
2201 | if (page_count(page) != 1 + !!PageSwapCache(page)) { | |
2202 | unlock_page(page); | |
2203 | goto out; | |
2204 | } | |
2205 | if (pte_write(pteval)) { | |
2206 | writable = true; | |
2207 | } else { | |
2208 | if (PageSwapCache(page) && !reuse_swap_page(page)) { | |
2209 | unlock_page(page); | |
2210 | goto out; | |
2211 | } | |
2212 | /* | |
2213 | * Page is not in the swap cache. It can be collapsed | |
2214 | * into a THP. | |
2215 | */ | |
2216 | } | |
2217 | ||
ba76149f AA |
2218 | /* |
2219 | * Isolate the page to avoid collapsing an hugepage | |
2220 | * currently in use by the VM. | |
2221 | */ | |
2222 | if (isolate_lru_page(page)) { | |
2223 | unlock_page(page); | |
ba76149f AA |
2224 | goto out; |
2225 | } | |
2226 | /* 0 stands for page_is_file_cache(page) == false */ | |
2227 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
309381fe SL |
2228 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
2229 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
ba76149f AA |
2230 | |
2231 | /* If there is no mapped pte young don't collapse the page */ | |
8ee53820 AA |
2232 | if (pte_young(pteval) || PageReferenced(page) || |
2233 | mmu_notifier_test_young(vma->vm_mm, address)) | |
10359213 | 2234 | referenced = true; |
ba76149f | 2235 | } |
10359213 | 2236 | if (likely(referenced && writable)) |
344aa35c | 2237 | return 1; |
ba76149f | 2238 | out: |
344aa35c BL |
2239 | release_pte_pages(pte, _pte); |
2240 | return 0; | |
ba76149f AA |
2241 | } |
2242 | ||
2243 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
2244 | struct vm_area_struct *vma, | |
2245 | unsigned long address, | |
2246 | spinlock_t *ptl) | |
2247 | { | |
2248 | pte_t *_pte; | |
2249 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { | |
2250 | pte_t pteval = *_pte; | |
2251 | struct page *src_page; | |
2252 | ||
ca0984ca | 2253 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
ba76149f AA |
2254 | clear_user_highpage(page, address); |
2255 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
ca0984ca EA |
2256 | if (is_zero_pfn(pte_pfn(pteval))) { |
2257 | /* | |
2258 | * ptl mostly unnecessary. | |
2259 | */ | |
2260 | spin_lock(ptl); | |
2261 | /* | |
2262 | * paravirt calls inside pte_clear here are | |
2263 | * superfluous. | |
2264 | */ | |
2265 | pte_clear(vma->vm_mm, address, _pte); | |
2266 | spin_unlock(ptl); | |
2267 | } | |
ba76149f AA |
2268 | } else { |
2269 | src_page = pte_page(pteval); | |
2270 | copy_user_highpage(page, src_page, address, vma); | |
309381fe | 2271 | VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page); |
ba76149f AA |
2272 | release_pte_page(src_page); |
2273 | /* | |
2274 | * ptl mostly unnecessary, but preempt has to | |
2275 | * be disabled to update the per-cpu stats | |
2276 | * inside page_remove_rmap(). | |
2277 | */ | |
2278 | spin_lock(ptl); | |
2279 | /* | |
2280 | * paravirt calls inside pte_clear here are | |
2281 | * superfluous. | |
2282 | */ | |
2283 | pte_clear(vma->vm_mm, address, _pte); | |
2284 | page_remove_rmap(src_page); | |
2285 | spin_unlock(ptl); | |
2286 | free_page_and_swap_cache(src_page); | |
2287 | } | |
2288 | ||
2289 | address += PAGE_SIZE; | |
2290 | page++; | |
2291 | } | |
2292 | } | |
2293 | ||
26234f36 | 2294 | static void khugepaged_alloc_sleep(void) |
ba76149f | 2295 | { |
26234f36 XG |
2296 | wait_event_freezable_timeout(khugepaged_wait, false, |
2297 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
2298 | } | |
ba76149f | 2299 | |
9f1b868a BL |
2300 | static int khugepaged_node_load[MAX_NUMNODES]; |
2301 | ||
14a4e214 DR |
2302 | static bool khugepaged_scan_abort(int nid) |
2303 | { | |
2304 | int i; | |
2305 | ||
2306 | /* | |
2307 | * If zone_reclaim_mode is disabled, then no extra effort is made to | |
2308 | * allocate memory locally. | |
2309 | */ | |
2310 | if (!zone_reclaim_mode) | |
2311 | return false; | |
2312 | ||
2313 | /* If there is a count for this node already, it must be acceptable */ | |
2314 | if (khugepaged_node_load[nid]) | |
2315 | return false; | |
2316 | ||
2317 | for (i = 0; i < MAX_NUMNODES; i++) { | |
2318 | if (!khugepaged_node_load[i]) | |
2319 | continue; | |
2320 | if (node_distance(nid, i) > RECLAIM_DISTANCE) | |
2321 | return true; | |
2322 | } | |
2323 | return false; | |
2324 | } | |
2325 | ||
26234f36 | 2326 | #ifdef CONFIG_NUMA |
9f1b868a BL |
2327 | static int khugepaged_find_target_node(void) |
2328 | { | |
2329 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
2330 | int nid, target_node = 0, max_value = 0; | |
2331 | ||
2332 | /* find first node with max normal pages hit */ | |
2333 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
2334 | if (khugepaged_node_load[nid] > max_value) { | |
2335 | max_value = khugepaged_node_load[nid]; | |
2336 | target_node = nid; | |
2337 | } | |
2338 | ||
2339 | /* do some balance if several nodes have the same hit record */ | |
2340 | if (target_node <= last_khugepaged_target_node) | |
2341 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
2342 | nid++) | |
2343 | if (max_value == khugepaged_node_load[nid]) { | |
2344 | target_node = nid; | |
2345 | break; | |
2346 | } | |
2347 | ||
2348 | last_khugepaged_target_node = target_node; | |
2349 | return target_node; | |
2350 | } | |
2351 | ||
26234f36 XG |
2352 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) |
2353 | { | |
2354 | if (IS_ERR(*hpage)) { | |
2355 | if (!*wait) | |
2356 | return false; | |
2357 | ||
2358 | *wait = false; | |
e3b4126c | 2359 | *hpage = NULL; |
26234f36 XG |
2360 | khugepaged_alloc_sleep(); |
2361 | } else if (*hpage) { | |
2362 | put_page(*hpage); | |
2363 | *hpage = NULL; | |
2364 | } | |
2365 | ||
2366 | return true; | |
2367 | } | |
2368 | ||
3b363692 MH |
2369 | static struct page * |
2370 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
26234f36 XG |
2371 | struct vm_area_struct *vma, unsigned long address, |
2372 | int node) | |
2373 | { | |
309381fe | 2374 | VM_BUG_ON_PAGE(*hpage, *hpage); |
8b164568 | 2375 | |
ce83d217 | 2376 | /* |
8b164568 VB |
2377 | * Before allocating the hugepage, release the mmap_sem read lock. |
2378 | * The allocation can take potentially a long time if it involves | |
2379 | * sync compaction, and we do not need to hold the mmap_sem during | |
2380 | * that. We will recheck the vma after taking it again in write mode. | |
ce83d217 | 2381 | */ |
8b164568 VB |
2382 | up_read(&mm->mmap_sem); |
2383 | ||
3b363692 | 2384 | *hpage = alloc_pages_exact_node(node, gfp, HPAGE_PMD_ORDER); |
26234f36 | 2385 | if (unlikely(!*hpage)) { |
81ab4201 | 2386 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); |
ce83d217 | 2387 | *hpage = ERR_PTR(-ENOMEM); |
26234f36 | 2388 | return NULL; |
ce83d217 | 2389 | } |
26234f36 | 2390 | |
65b3c07b | 2391 | count_vm_event(THP_COLLAPSE_ALLOC); |
26234f36 XG |
2392 | return *hpage; |
2393 | } | |
2394 | #else | |
9f1b868a BL |
2395 | static int khugepaged_find_target_node(void) |
2396 | { | |
2397 | return 0; | |
2398 | } | |
2399 | ||
10dc4155 BL |
2400 | static inline struct page *alloc_hugepage(int defrag) |
2401 | { | |
2402 | return alloc_pages(alloc_hugepage_gfpmask(defrag, 0), | |
2403 | HPAGE_PMD_ORDER); | |
2404 | } | |
2405 | ||
26234f36 XG |
2406 | static struct page *khugepaged_alloc_hugepage(bool *wait) |
2407 | { | |
2408 | struct page *hpage; | |
2409 | ||
2410 | do { | |
2411 | hpage = alloc_hugepage(khugepaged_defrag()); | |
2412 | if (!hpage) { | |
2413 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
2414 | if (!*wait) | |
2415 | return NULL; | |
2416 | ||
2417 | *wait = false; | |
2418 | khugepaged_alloc_sleep(); | |
2419 | } else | |
2420 | count_vm_event(THP_COLLAPSE_ALLOC); | |
2421 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
2422 | ||
2423 | return hpage; | |
2424 | } | |
2425 | ||
2426 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
2427 | { | |
2428 | if (!*hpage) | |
2429 | *hpage = khugepaged_alloc_hugepage(wait); | |
2430 | ||
2431 | if (unlikely(!*hpage)) | |
2432 | return false; | |
2433 | ||
2434 | return true; | |
2435 | } | |
2436 | ||
3b363692 MH |
2437 | static struct page * |
2438 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
26234f36 XG |
2439 | struct vm_area_struct *vma, unsigned long address, |
2440 | int node) | |
2441 | { | |
2442 | up_read(&mm->mmap_sem); | |
2443 | VM_BUG_ON(!*hpage); | |
3b363692 | 2444 | |
26234f36 XG |
2445 | return *hpage; |
2446 | } | |
692e0b35 AA |
2447 | #endif |
2448 | ||
fa475e51 BL |
2449 | static bool hugepage_vma_check(struct vm_area_struct *vma) |
2450 | { | |
2451 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || | |
2452 | (vma->vm_flags & VM_NOHUGEPAGE)) | |
2453 | return false; | |
2454 | ||
2455 | if (!vma->anon_vma || vma->vm_ops) | |
2456 | return false; | |
2457 | if (is_vma_temporary_stack(vma)) | |
2458 | return false; | |
81d1b09c | 2459 | VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma); |
fa475e51 BL |
2460 | return true; |
2461 | } | |
2462 | ||
26234f36 XG |
2463 | static void collapse_huge_page(struct mm_struct *mm, |
2464 | unsigned long address, | |
2465 | struct page **hpage, | |
2466 | struct vm_area_struct *vma, | |
2467 | int node) | |
2468 | { | |
26234f36 XG |
2469 | pmd_t *pmd, _pmd; |
2470 | pte_t *pte; | |
2471 | pgtable_t pgtable; | |
2472 | struct page *new_page; | |
c4088ebd | 2473 | spinlock_t *pmd_ptl, *pte_ptl; |
26234f36 XG |
2474 | int isolated; |
2475 | unsigned long hstart, hend; | |
00501b53 | 2476 | struct mem_cgroup *memcg; |
2ec74c3e SG |
2477 | unsigned long mmun_start; /* For mmu_notifiers */ |
2478 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 2479 | gfp_t gfp; |
26234f36 XG |
2480 | |
2481 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2482 | ||
3b363692 MH |
2483 | /* Only allocate from the target node */ |
2484 | gfp = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) | | |
2485 | __GFP_THISNODE; | |
2486 | ||
26234f36 | 2487 | /* release the mmap_sem read lock. */ |
3b363692 | 2488 | new_page = khugepaged_alloc_page(hpage, gfp, mm, vma, address, node); |
26234f36 XG |
2489 | if (!new_page) |
2490 | return; | |
2491 | ||
00501b53 | 2492 | if (unlikely(mem_cgroup_try_charge(new_page, mm, |
3b363692 | 2493 | gfp, &memcg))) |
ce83d217 | 2494 | return; |
ba76149f AA |
2495 | |
2496 | /* | |
2497 | * Prevent all access to pagetables with the exception of | |
2498 | * gup_fast later hanlded by the ptep_clear_flush and the VM | |
2499 | * handled by the anon_vma lock + PG_lock. | |
2500 | */ | |
2501 | down_write(&mm->mmap_sem); | |
2502 | if (unlikely(khugepaged_test_exit(mm))) | |
2503 | goto out; | |
2504 | ||
2505 | vma = find_vma(mm, address); | |
a8f531eb L |
2506 | if (!vma) |
2507 | goto out; | |
ba76149f AA |
2508 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2509 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2510 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
2511 | goto out; | |
fa475e51 | 2512 | if (!hugepage_vma_check(vma)) |
a7d6e4ec | 2513 | goto out; |
6219049a BL |
2514 | pmd = mm_find_pmd(mm, address); |
2515 | if (!pmd) | |
ba76149f | 2516 | goto out; |
ba76149f | 2517 | |
4fc3f1d6 | 2518 | anon_vma_lock_write(vma->anon_vma); |
ba76149f AA |
2519 | |
2520 | pte = pte_offset_map(pmd, address); | |
c4088ebd | 2521 | pte_ptl = pte_lockptr(mm, pmd); |
ba76149f | 2522 | |
2ec74c3e SG |
2523 | mmun_start = address; |
2524 | mmun_end = address + HPAGE_PMD_SIZE; | |
2525 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
c4088ebd | 2526 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
ba76149f AA |
2527 | /* |
2528 | * After this gup_fast can't run anymore. This also removes | |
2529 | * any huge TLB entry from the CPU so we won't allow | |
2530 | * huge and small TLB entries for the same virtual address | |
2531 | * to avoid the risk of CPU bugs in that area. | |
2532 | */ | |
15a25b2e | 2533 | _pmd = pmdp_collapse_flush(vma, address, pmd); |
c4088ebd | 2534 | spin_unlock(pmd_ptl); |
2ec74c3e | 2535 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
ba76149f | 2536 | |
c4088ebd | 2537 | spin_lock(pte_ptl); |
ba76149f | 2538 | isolated = __collapse_huge_page_isolate(vma, address, pte); |
c4088ebd | 2539 | spin_unlock(pte_ptl); |
ba76149f AA |
2540 | |
2541 | if (unlikely(!isolated)) { | |
453c7192 | 2542 | pte_unmap(pte); |
c4088ebd | 2543 | spin_lock(pmd_ptl); |
ba76149f | 2544 | BUG_ON(!pmd_none(*pmd)); |
7c342512 AK |
2545 | /* |
2546 | * We can only use set_pmd_at when establishing | |
2547 | * hugepmds and never for establishing regular pmds that | |
2548 | * points to regular pagetables. Use pmd_populate for that | |
2549 | */ | |
2550 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
c4088ebd | 2551 | spin_unlock(pmd_ptl); |
08b52706 | 2552 | anon_vma_unlock_write(vma->anon_vma); |
ce83d217 | 2553 | goto out; |
ba76149f AA |
2554 | } |
2555 | ||
2556 | /* | |
2557 | * All pages are isolated and locked so anon_vma rmap | |
2558 | * can't run anymore. | |
2559 | */ | |
08b52706 | 2560 | anon_vma_unlock_write(vma->anon_vma); |
ba76149f | 2561 | |
c4088ebd | 2562 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); |
453c7192 | 2563 | pte_unmap(pte); |
ba76149f AA |
2564 | __SetPageUptodate(new_page); |
2565 | pgtable = pmd_pgtable(_pmd); | |
ba76149f | 2566 | |
3122359a KS |
2567 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); |
2568 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); | |
ba76149f AA |
2569 | |
2570 | /* | |
2571 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
2572 | * this is needed to avoid the copy_huge_page writes to become | |
2573 | * visible after the set_pmd_at() write. | |
2574 | */ | |
2575 | smp_wmb(); | |
2576 | ||
c4088ebd | 2577 | spin_lock(pmd_ptl); |
ba76149f AA |
2578 | BUG_ON(!pmd_none(*pmd)); |
2579 | page_add_new_anon_rmap(new_page, vma, address); | |
00501b53 JW |
2580 | mem_cgroup_commit_charge(new_page, memcg, false); |
2581 | lru_cache_add_active_or_unevictable(new_page, vma); | |
fce144b4 | 2582 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
ba76149f | 2583 | set_pmd_at(mm, address, pmd, _pmd); |
b113da65 | 2584 | update_mmu_cache_pmd(vma, address, pmd); |
c4088ebd | 2585 | spin_unlock(pmd_ptl); |
ba76149f AA |
2586 | |
2587 | *hpage = NULL; | |
420256ef | 2588 | |
ba76149f | 2589 | khugepaged_pages_collapsed++; |
ce83d217 | 2590 | out_up_write: |
ba76149f | 2591 | up_write(&mm->mmap_sem); |
0bbbc0b3 AA |
2592 | return; |
2593 | ||
ce83d217 | 2594 | out: |
00501b53 | 2595 | mem_cgroup_cancel_charge(new_page, memcg); |
ce83d217 | 2596 | goto out_up_write; |
ba76149f AA |
2597 | } |
2598 | ||
2599 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
2600 | struct vm_area_struct *vma, | |
2601 | unsigned long address, | |
2602 | struct page **hpage) | |
2603 | { | |
ba76149f AA |
2604 | pmd_t *pmd; |
2605 | pte_t *pte, *_pte; | |
ca0984ca | 2606 | int ret = 0, none_or_zero = 0; |
ba76149f AA |
2607 | struct page *page; |
2608 | unsigned long _address; | |
2609 | spinlock_t *ptl; | |
00ef2d2f | 2610 | int node = NUMA_NO_NODE; |
10359213 | 2611 | bool writable = false, referenced = false; |
ba76149f AA |
2612 | |
2613 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2614 | ||
6219049a BL |
2615 | pmd = mm_find_pmd(mm, address); |
2616 | if (!pmd) | |
ba76149f | 2617 | goto out; |
ba76149f | 2618 | |
9f1b868a | 2619 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); |
ba76149f AA |
2620 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
2621 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
2622 | _pte++, _address += PAGE_SIZE) { | |
2623 | pte_t pteval = *_pte; | |
ca0984ca | 2624 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
c1294d05 AA |
2625 | if (!userfaultfd_armed(vma) && |
2626 | ++none_or_zero <= khugepaged_max_ptes_none) | |
ba76149f AA |
2627 | continue; |
2628 | else | |
2629 | goto out_unmap; | |
2630 | } | |
10359213 | 2631 | if (!pte_present(pteval)) |
ba76149f | 2632 | goto out_unmap; |
10359213 EA |
2633 | if (pte_write(pteval)) |
2634 | writable = true; | |
2635 | ||
ba76149f AA |
2636 | page = vm_normal_page(vma, _address, pteval); |
2637 | if (unlikely(!page)) | |
2638 | goto out_unmap; | |
5c4b4be3 | 2639 | /* |
9f1b868a BL |
2640 | * Record which node the original page is from and save this |
2641 | * information to khugepaged_node_load[]. | |
2642 | * Khupaged will allocate hugepage from the node has the max | |
2643 | * hit record. | |
5c4b4be3 | 2644 | */ |
9f1b868a | 2645 | node = page_to_nid(page); |
14a4e214 DR |
2646 | if (khugepaged_scan_abort(node)) |
2647 | goto out_unmap; | |
9f1b868a | 2648 | khugepaged_node_load[node]++; |
309381fe | 2649 | VM_BUG_ON_PAGE(PageCompound(page), page); |
ba76149f AA |
2650 | if (!PageLRU(page) || PageLocked(page) || !PageAnon(page)) |
2651 | goto out_unmap; | |
10359213 EA |
2652 | /* |
2653 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2654 | * The page must only be referenced by the scanned process | |
2655 | * and page swap cache. | |
2656 | */ | |
2657 | if (page_count(page) != 1 + !!PageSwapCache(page)) | |
ba76149f | 2658 | goto out_unmap; |
8ee53820 AA |
2659 | if (pte_young(pteval) || PageReferenced(page) || |
2660 | mmu_notifier_test_young(vma->vm_mm, address)) | |
10359213 | 2661 | referenced = true; |
ba76149f | 2662 | } |
10359213 | 2663 | if (referenced && writable) |
ba76149f AA |
2664 | ret = 1; |
2665 | out_unmap: | |
2666 | pte_unmap_unlock(pte, ptl); | |
9f1b868a BL |
2667 | if (ret) { |
2668 | node = khugepaged_find_target_node(); | |
ce83d217 | 2669 | /* collapse_huge_page will return with the mmap_sem released */ |
5c4b4be3 | 2670 | collapse_huge_page(mm, address, hpage, vma, node); |
9f1b868a | 2671 | } |
ba76149f AA |
2672 | out: |
2673 | return ret; | |
2674 | } | |
2675 | ||
2676 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
2677 | { | |
2678 | struct mm_struct *mm = mm_slot->mm; | |
2679 | ||
b9980cdc | 2680 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2681 | |
2682 | if (khugepaged_test_exit(mm)) { | |
2683 | /* free mm_slot */ | |
43b5fbbd | 2684 | hash_del(&mm_slot->hash); |
ba76149f AA |
2685 | list_del(&mm_slot->mm_node); |
2686 | ||
2687 | /* | |
2688 | * Not strictly needed because the mm exited already. | |
2689 | * | |
2690 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
2691 | */ | |
2692 | ||
2693 | /* khugepaged_mm_lock actually not necessary for the below */ | |
2694 | free_mm_slot(mm_slot); | |
2695 | mmdrop(mm); | |
2696 | } | |
2697 | } | |
2698 | ||
2699 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
2700 | struct page **hpage) | |
2f1da642 HS |
2701 | __releases(&khugepaged_mm_lock) |
2702 | __acquires(&khugepaged_mm_lock) | |
ba76149f AA |
2703 | { |
2704 | struct mm_slot *mm_slot; | |
2705 | struct mm_struct *mm; | |
2706 | struct vm_area_struct *vma; | |
2707 | int progress = 0; | |
2708 | ||
2709 | VM_BUG_ON(!pages); | |
b9980cdc | 2710 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2711 | |
2712 | if (khugepaged_scan.mm_slot) | |
2713 | mm_slot = khugepaged_scan.mm_slot; | |
2714 | else { | |
2715 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2716 | struct mm_slot, mm_node); | |
2717 | khugepaged_scan.address = 0; | |
2718 | khugepaged_scan.mm_slot = mm_slot; | |
2719 | } | |
2720 | spin_unlock(&khugepaged_mm_lock); | |
2721 | ||
2722 | mm = mm_slot->mm; | |
2723 | down_read(&mm->mmap_sem); | |
2724 | if (unlikely(khugepaged_test_exit(mm))) | |
2725 | vma = NULL; | |
2726 | else | |
2727 | vma = find_vma(mm, khugepaged_scan.address); | |
2728 | ||
2729 | progress++; | |
2730 | for (; vma; vma = vma->vm_next) { | |
2731 | unsigned long hstart, hend; | |
2732 | ||
2733 | cond_resched(); | |
2734 | if (unlikely(khugepaged_test_exit(mm))) { | |
2735 | progress++; | |
2736 | break; | |
2737 | } | |
fa475e51 BL |
2738 | if (!hugepage_vma_check(vma)) { |
2739 | skip: | |
ba76149f AA |
2740 | progress++; |
2741 | continue; | |
2742 | } | |
ba76149f AA |
2743 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2744 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
a7d6e4ec AA |
2745 | if (hstart >= hend) |
2746 | goto skip; | |
2747 | if (khugepaged_scan.address > hend) | |
2748 | goto skip; | |
ba76149f AA |
2749 | if (khugepaged_scan.address < hstart) |
2750 | khugepaged_scan.address = hstart; | |
a7d6e4ec | 2751 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); |
ba76149f AA |
2752 | |
2753 | while (khugepaged_scan.address < hend) { | |
2754 | int ret; | |
2755 | cond_resched(); | |
2756 | if (unlikely(khugepaged_test_exit(mm))) | |
2757 | goto breakouterloop; | |
2758 | ||
2759 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2760 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2761 | hend); | |
2762 | ret = khugepaged_scan_pmd(mm, vma, | |
2763 | khugepaged_scan.address, | |
2764 | hpage); | |
2765 | /* move to next address */ | |
2766 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2767 | progress += HPAGE_PMD_NR; | |
2768 | if (ret) | |
2769 | /* we released mmap_sem so break loop */ | |
2770 | goto breakouterloop_mmap_sem; | |
2771 | if (progress >= pages) | |
2772 | goto breakouterloop; | |
2773 | } | |
2774 | } | |
2775 | breakouterloop: | |
2776 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2777 | breakouterloop_mmap_sem: | |
2778 | ||
2779 | spin_lock(&khugepaged_mm_lock); | |
a7d6e4ec | 2780 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); |
ba76149f AA |
2781 | /* |
2782 | * Release the current mm_slot if this mm is about to die, or | |
2783 | * if we scanned all vmas of this mm. | |
2784 | */ | |
2785 | if (khugepaged_test_exit(mm) || !vma) { | |
2786 | /* | |
2787 | * Make sure that if mm_users is reaching zero while | |
2788 | * khugepaged runs here, khugepaged_exit will find | |
2789 | * mm_slot not pointing to the exiting mm. | |
2790 | */ | |
2791 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2792 | khugepaged_scan.mm_slot = list_entry( | |
2793 | mm_slot->mm_node.next, | |
2794 | struct mm_slot, mm_node); | |
2795 | khugepaged_scan.address = 0; | |
2796 | } else { | |
2797 | khugepaged_scan.mm_slot = NULL; | |
2798 | khugepaged_full_scans++; | |
2799 | } | |
2800 | ||
2801 | collect_mm_slot(mm_slot); | |
2802 | } | |
2803 | ||
2804 | return progress; | |
2805 | } | |
2806 | ||
2807 | static int khugepaged_has_work(void) | |
2808 | { | |
2809 | return !list_empty(&khugepaged_scan.mm_head) && | |
2810 | khugepaged_enabled(); | |
2811 | } | |
2812 | ||
2813 | static int khugepaged_wait_event(void) | |
2814 | { | |
2815 | return !list_empty(&khugepaged_scan.mm_head) || | |
2017c0bf | 2816 | kthread_should_stop(); |
ba76149f AA |
2817 | } |
2818 | ||
d516904b | 2819 | static void khugepaged_do_scan(void) |
ba76149f | 2820 | { |
d516904b | 2821 | struct page *hpage = NULL; |
ba76149f AA |
2822 | unsigned int progress = 0, pass_through_head = 0; |
2823 | unsigned int pages = khugepaged_pages_to_scan; | |
d516904b | 2824 | bool wait = true; |
ba76149f AA |
2825 | |
2826 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2827 | ||
2828 | while (progress < pages) { | |
26234f36 | 2829 | if (!khugepaged_prealloc_page(&hpage, &wait)) |
d516904b | 2830 | break; |
26234f36 | 2831 | |
420256ef | 2832 | cond_resched(); |
ba76149f | 2833 | |
cd092411 | 2834 | if (unlikely(kthread_should_stop() || try_to_freeze())) |
878aee7d AA |
2835 | break; |
2836 | ||
ba76149f AA |
2837 | spin_lock(&khugepaged_mm_lock); |
2838 | if (!khugepaged_scan.mm_slot) | |
2839 | pass_through_head++; | |
2840 | if (khugepaged_has_work() && | |
2841 | pass_through_head < 2) | |
2842 | progress += khugepaged_scan_mm_slot(pages - progress, | |
d516904b | 2843 | &hpage); |
ba76149f AA |
2844 | else |
2845 | progress = pages; | |
2846 | spin_unlock(&khugepaged_mm_lock); | |
2847 | } | |
ba76149f | 2848 | |
d516904b XG |
2849 | if (!IS_ERR_OR_NULL(hpage)) |
2850 | put_page(hpage); | |
0bbbc0b3 AA |
2851 | } |
2852 | ||
2017c0bf XG |
2853 | static void khugepaged_wait_work(void) |
2854 | { | |
2017c0bf XG |
2855 | if (khugepaged_has_work()) { |
2856 | if (!khugepaged_scan_sleep_millisecs) | |
2857 | return; | |
2858 | ||
2859 | wait_event_freezable_timeout(khugepaged_wait, | |
2860 | kthread_should_stop(), | |
2861 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs)); | |
2862 | return; | |
2863 | } | |
2864 | ||
2865 | if (khugepaged_enabled()) | |
2866 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2867 | } | |
2868 | ||
ba76149f AA |
2869 | static int khugepaged(void *none) |
2870 | { | |
2871 | struct mm_slot *mm_slot; | |
2872 | ||
878aee7d | 2873 | set_freezable(); |
8698a745 | 2874 | set_user_nice(current, MAX_NICE); |
ba76149f | 2875 | |
b7231789 XG |
2876 | while (!kthread_should_stop()) { |
2877 | khugepaged_do_scan(); | |
2878 | khugepaged_wait_work(); | |
2879 | } | |
ba76149f AA |
2880 | |
2881 | spin_lock(&khugepaged_mm_lock); | |
2882 | mm_slot = khugepaged_scan.mm_slot; | |
2883 | khugepaged_scan.mm_slot = NULL; | |
2884 | if (mm_slot) | |
2885 | collect_mm_slot(mm_slot); | |
2886 | spin_unlock(&khugepaged_mm_lock); | |
ba76149f AA |
2887 | return 0; |
2888 | } | |
2889 | ||
c5a647d0 KS |
2890 | static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, |
2891 | unsigned long haddr, pmd_t *pmd) | |
2892 | { | |
2893 | struct mm_struct *mm = vma->vm_mm; | |
2894 | pgtable_t pgtable; | |
2895 | pmd_t _pmd; | |
2896 | int i; | |
2897 | ||
8809aa2d | 2898 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
c5a647d0 KS |
2899 | /* leave pmd empty until pte is filled */ |
2900 | ||
6b0b50b0 | 2901 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
c5a647d0 KS |
2902 | pmd_populate(mm, &_pmd, pgtable); |
2903 | ||
2904 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
2905 | pte_t *pte, entry; | |
2906 | entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); | |
2907 | entry = pte_mkspecial(entry); | |
2908 | pte = pte_offset_map(&_pmd, haddr); | |
2909 | VM_BUG_ON(!pte_none(*pte)); | |
2910 | set_pte_at(mm, haddr, pte, entry); | |
2911 | pte_unmap(pte); | |
2912 | } | |
2913 | smp_wmb(); /* make pte visible before pmd */ | |
2914 | pmd_populate(mm, pmd, pgtable); | |
97ae1749 | 2915 | put_huge_zero_page(); |
c5a647d0 KS |
2916 | } |
2917 | ||
e180377f KS |
2918 | void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address, |
2919 | pmd_t *pmd) | |
71e3aac0 | 2920 | { |
c4088ebd | 2921 | spinlock_t *ptl; |
4897c765 | 2922 | struct page *page = NULL; |
e180377f | 2923 | struct mm_struct *mm = vma->vm_mm; |
c5a647d0 KS |
2924 | unsigned long haddr = address & HPAGE_PMD_MASK; |
2925 | unsigned long mmun_start; /* For mmu_notifiers */ | |
2926 | unsigned long mmun_end; /* For mmu_notifiers */ | |
e180377f KS |
2927 | |
2928 | BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE); | |
71e3aac0 | 2929 | |
c5a647d0 KS |
2930 | mmun_start = haddr; |
2931 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
750e8165 | 2932 | again: |
c5a647d0 | 2933 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
c4088ebd | 2934 | ptl = pmd_lock(mm, pmd); |
4897c765 MW |
2935 | if (unlikely(!pmd_trans_huge(*pmd))) |
2936 | goto unlock; | |
2937 | if (vma_is_dax(vma)) { | |
2938 | pmdp_huge_clear_flush(vma, haddr, pmd); | |
2939 | } else if (is_huge_zero_pmd(*pmd)) { | |
c5a647d0 | 2940 | __split_huge_zero_page_pmd(vma, haddr, pmd); |
4897c765 MW |
2941 | } else { |
2942 | page = pmd_page(*pmd); | |
2943 | VM_BUG_ON_PAGE(!page_count(page), page); | |
2944 | get_page(page); | |
71e3aac0 | 2945 | } |
4897c765 | 2946 | unlock: |
c4088ebd | 2947 | spin_unlock(ptl); |
c5a647d0 | 2948 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
71e3aac0 | 2949 | |
4897c765 MW |
2950 | if (!page) |
2951 | return; | |
71e3aac0 | 2952 | |
4897c765 | 2953 | split_huge_page(page); |
71e3aac0 | 2954 | put_page(page); |
750e8165 HD |
2955 | |
2956 | /* | |
2957 | * We don't always have down_write of mmap_sem here: a racing | |
2958 | * do_huge_pmd_wp_page() might have copied-on-write to another | |
2959 | * huge page before our split_huge_page() got the anon_vma lock. | |
2960 | */ | |
2961 | if (unlikely(pmd_trans_huge(*pmd))) | |
2962 | goto again; | |
71e3aac0 | 2963 | } |
94fcc585 | 2964 | |
e180377f KS |
2965 | void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address, |
2966 | pmd_t *pmd) | |
2967 | { | |
2968 | struct vm_area_struct *vma; | |
2969 | ||
2970 | vma = find_vma(mm, address); | |
2971 | BUG_ON(vma == NULL); | |
2972 | split_huge_page_pmd(vma, address, pmd); | |
2973 | } | |
2974 | ||
94fcc585 AA |
2975 | static void split_huge_page_address(struct mm_struct *mm, |
2976 | unsigned long address) | |
2977 | { | |
f72e7dcd HD |
2978 | pgd_t *pgd; |
2979 | pud_t *pud; | |
94fcc585 AA |
2980 | pmd_t *pmd; |
2981 | ||
2982 | VM_BUG_ON(!(address & ~HPAGE_PMD_MASK)); | |
2983 | ||
f72e7dcd HD |
2984 | pgd = pgd_offset(mm, address); |
2985 | if (!pgd_present(*pgd)) | |
2986 | return; | |
2987 | ||
2988 | pud = pud_offset(pgd, address); | |
2989 | if (!pud_present(*pud)) | |
2990 | return; | |
2991 | ||
2992 | pmd = pmd_offset(pud, address); | |
2993 | if (!pmd_present(*pmd)) | |
94fcc585 AA |
2994 | return; |
2995 | /* | |
2996 | * Caller holds the mmap_sem write mode, so a huge pmd cannot | |
2997 | * materialize from under us. | |
2998 | */ | |
e180377f | 2999 | split_huge_page_pmd_mm(mm, address, pmd); |
94fcc585 AA |
3000 | } |
3001 | ||
e1b9996b | 3002 | void vma_adjust_trans_huge(struct vm_area_struct *vma, |
94fcc585 AA |
3003 | unsigned long start, |
3004 | unsigned long end, | |
3005 | long adjust_next) | |
3006 | { | |
3007 | /* | |
3008 | * If the new start address isn't hpage aligned and it could | |
3009 | * previously contain an hugepage: check if we need to split | |
3010 | * an huge pmd. | |
3011 | */ | |
3012 | if (start & ~HPAGE_PMD_MASK && | |
3013 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
3014 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
3015 | split_huge_page_address(vma->vm_mm, start); | |
3016 | ||
3017 | /* | |
3018 | * If the new end address isn't hpage aligned and it could | |
3019 | * previously contain an hugepage: check if we need to split | |
3020 | * an huge pmd. | |
3021 | */ | |
3022 | if (end & ~HPAGE_PMD_MASK && | |
3023 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
3024 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
3025 | split_huge_page_address(vma->vm_mm, end); | |
3026 | ||
3027 | /* | |
3028 | * If we're also updating the vma->vm_next->vm_start, if the new | |
3029 | * vm_next->vm_start isn't page aligned and it could previously | |
3030 | * contain an hugepage: check if we need to split an huge pmd. | |
3031 | */ | |
3032 | if (adjust_next > 0) { | |
3033 | struct vm_area_struct *next = vma->vm_next; | |
3034 | unsigned long nstart = next->vm_start; | |
3035 | nstart += adjust_next << PAGE_SHIFT; | |
3036 | if (nstart & ~HPAGE_PMD_MASK && | |
3037 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
3038 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
3039 | split_huge_page_address(next->vm_mm, nstart); | |
3040 | } | |
3041 | } |