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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> |
e9b61f19 | 19 | #include <linux/swapops.h> |
4897c765 | 20 | #include <linux/dax.h> |
ba76149f AA |
21 | #include <linux/kthread.h> |
22 | #include <linux/khugepaged.h> | |
878aee7d | 23 | #include <linux/freezer.h> |
f25748e3 | 24 | #include <linux/pfn_t.h> |
a664b2d8 | 25 | #include <linux/mman.h> |
3565fce3 | 26 | #include <linux/memremap.h> |
325adeb5 | 27 | #include <linux/pagemap.h> |
49071d43 | 28 | #include <linux/debugfs.h> |
4daae3b4 | 29 | #include <linux/migrate.h> |
43b5fbbd | 30 | #include <linux/hashtable.h> |
6b251fc9 | 31 | #include <linux/userfaultfd_k.h> |
33c3fc71 | 32 | #include <linux/page_idle.h> |
97ae1749 | 33 | |
71e3aac0 AA |
34 | #include <asm/tlb.h> |
35 | #include <asm/pgalloc.h> | |
36 | #include "internal.h" | |
37 | ||
7d2eba05 EA |
38 | enum scan_result { |
39 | SCAN_FAIL, | |
40 | SCAN_SUCCEED, | |
41 | SCAN_PMD_NULL, | |
42 | SCAN_EXCEED_NONE_PTE, | |
43 | SCAN_PTE_NON_PRESENT, | |
44 | SCAN_PAGE_RO, | |
45 | SCAN_NO_REFERENCED_PAGE, | |
46 | SCAN_PAGE_NULL, | |
47 | SCAN_SCAN_ABORT, | |
48 | SCAN_PAGE_COUNT, | |
49 | SCAN_PAGE_LRU, | |
50 | SCAN_PAGE_LOCK, | |
51 | SCAN_PAGE_ANON, | |
b1caa957 | 52 | SCAN_PAGE_COMPOUND, |
7d2eba05 EA |
53 | SCAN_ANY_PROCESS, |
54 | SCAN_VMA_NULL, | |
55 | SCAN_VMA_CHECK, | |
56 | SCAN_ADDRESS_RANGE, | |
57 | SCAN_SWAP_CACHE_PAGE, | |
58 | SCAN_DEL_PAGE_LRU, | |
59 | SCAN_ALLOC_HUGE_PAGE_FAIL, | |
70652f6e EA |
60 | SCAN_CGROUP_CHARGE_FAIL, |
61 | SCAN_EXCEED_SWAP_PTE | |
7d2eba05 EA |
62 | }; |
63 | ||
64 | #define CREATE_TRACE_POINTS | |
65 | #include <trace/events/huge_memory.h> | |
66 | ||
ba76149f | 67 | /* |
8bfa3f9a JW |
68 | * By default transparent hugepage support is disabled in order that avoid |
69 | * to risk increase the memory footprint of applications without a guaranteed | |
70 | * benefit. When transparent hugepage support is enabled, is for all mappings, | |
71 | * and khugepaged scans all mappings. | |
72 | * Defrag is invoked by khugepaged hugepage allocations and by page faults | |
73 | * for all hugepage allocations. | |
ba76149f | 74 | */ |
71e3aac0 | 75 | unsigned long transparent_hugepage_flags __read_mostly = |
13ece886 | 76 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS |
ba76149f | 77 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| |
13ece886 AA |
78 | #endif |
79 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE | |
80 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| | |
81 | #endif | |
444eb2a4 | 82 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| |
79da5407 KS |
83 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| |
84 | (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
ba76149f AA |
85 | |
86 | /* default scan 8*512 pte (or vmas) every 30 second */ | |
ff20c2e0 | 87 | static unsigned int khugepaged_pages_to_scan __read_mostly; |
ba76149f AA |
88 | static unsigned int khugepaged_pages_collapsed; |
89 | static unsigned int khugepaged_full_scans; | |
90 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
91 | /* during fragmentation poll the hugepage allocator once every minute */ | |
92 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
f0508977 | 93 | static unsigned long khugepaged_sleep_expire; |
ba76149f AA |
94 | static struct task_struct *khugepaged_thread __read_mostly; |
95 | static DEFINE_MUTEX(khugepaged_mutex); | |
96 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
97 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
98 | /* | |
99 | * default collapse hugepages if there is at least one pte mapped like | |
100 | * it would have happened if the vma was large enough during page | |
101 | * fault. | |
102 | */ | |
ff20c2e0 | 103 | static unsigned int khugepaged_max_ptes_none __read_mostly; |
70652f6e | 104 | static unsigned int khugepaged_max_ptes_swap __read_mostly; |
ba76149f AA |
105 | |
106 | static int khugepaged(void *none); | |
ba76149f | 107 | static int khugepaged_slab_init(void); |
65ebb64f | 108 | static void khugepaged_slab_exit(void); |
ba76149f | 109 | |
43b5fbbd SL |
110 | #define MM_SLOTS_HASH_BITS 10 |
111 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
112 | ||
ba76149f AA |
113 | static struct kmem_cache *mm_slot_cache __read_mostly; |
114 | ||
115 | /** | |
116 | * struct mm_slot - hash lookup from mm to mm_slot | |
117 | * @hash: hash collision list | |
118 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
119 | * @mm: the mm that this information is valid for | |
120 | */ | |
121 | struct mm_slot { | |
122 | struct hlist_node hash; | |
123 | struct list_head mm_node; | |
124 | struct mm_struct *mm; | |
125 | }; | |
126 | ||
127 | /** | |
128 | * struct khugepaged_scan - cursor for scanning | |
129 | * @mm_head: the head of the mm list to scan | |
130 | * @mm_slot: the current mm_slot we are scanning | |
131 | * @address: the next address inside that to be scanned | |
132 | * | |
133 | * There is only the one khugepaged_scan instance of this cursor structure. | |
134 | */ | |
135 | struct khugepaged_scan { | |
136 | struct list_head mm_head; | |
137 | struct mm_slot *mm_slot; | |
138 | unsigned long address; | |
2f1da642 HS |
139 | }; |
140 | static struct khugepaged_scan khugepaged_scan = { | |
ba76149f AA |
141 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), |
142 | }; | |
143 | ||
9a982250 | 144 | static struct shrinker deferred_split_shrinker; |
f000565a | 145 | |
2c0b80d4 | 146 | static void set_recommended_min_free_kbytes(void) |
f000565a AA |
147 | { |
148 | struct zone *zone; | |
149 | int nr_zones = 0; | |
150 | unsigned long recommended_min; | |
f000565a | 151 | |
f000565a AA |
152 | for_each_populated_zone(zone) |
153 | nr_zones++; | |
154 | ||
974a786e | 155 | /* Ensure 2 pageblocks are free to assist fragmentation avoidance */ |
f000565a AA |
156 | recommended_min = pageblock_nr_pages * nr_zones * 2; |
157 | ||
158 | /* | |
159 | * Make sure that on average at least two pageblocks are almost free | |
160 | * of another type, one for a migratetype to fall back to and a | |
161 | * second to avoid subsequent fallbacks of other types There are 3 | |
162 | * MIGRATE_TYPES we care about. | |
163 | */ | |
164 | recommended_min += pageblock_nr_pages * nr_zones * | |
165 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
166 | ||
167 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
168 | recommended_min = min(recommended_min, | |
169 | (unsigned long) nr_free_buffer_pages() / 20); | |
170 | recommended_min <<= (PAGE_SHIFT-10); | |
171 | ||
42aa83cb HP |
172 | if (recommended_min > min_free_kbytes) { |
173 | if (user_min_free_kbytes >= 0) | |
756a025f | 174 | pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n", |
42aa83cb HP |
175 | min_free_kbytes, recommended_min); |
176 | ||
f000565a | 177 | min_free_kbytes = recommended_min; |
42aa83cb | 178 | } |
f000565a | 179 | setup_per_zone_wmarks(); |
f000565a | 180 | } |
f000565a | 181 | |
79553da2 | 182 | static int start_stop_khugepaged(void) |
ba76149f AA |
183 | { |
184 | int err = 0; | |
185 | if (khugepaged_enabled()) { | |
ba76149f AA |
186 | if (!khugepaged_thread) |
187 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
188 | "khugepaged"); | |
18e8e5c7 | 189 | if (IS_ERR(khugepaged_thread)) { |
ae3a8c1c | 190 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); |
ba76149f AA |
191 | err = PTR_ERR(khugepaged_thread); |
192 | khugepaged_thread = NULL; | |
79553da2 | 193 | goto fail; |
ba76149f | 194 | } |
911891af XG |
195 | |
196 | if (!list_empty(&khugepaged_scan.mm_head)) | |
ba76149f | 197 | wake_up_interruptible(&khugepaged_wait); |
f000565a AA |
198 | |
199 | set_recommended_min_free_kbytes(); | |
911891af | 200 | } else if (khugepaged_thread) { |
911891af XG |
201 | kthread_stop(khugepaged_thread); |
202 | khugepaged_thread = NULL; | |
203 | } | |
79553da2 | 204 | fail: |
ba76149f AA |
205 | return err; |
206 | } | |
71e3aac0 | 207 | |
97ae1749 | 208 | static atomic_t huge_zero_refcount; |
56873f43 | 209 | struct page *huge_zero_page __read_mostly; |
4a6c1297 | 210 | |
fc437044 | 211 | struct page *get_huge_zero_page(void) |
97ae1749 KS |
212 | { |
213 | struct page *zero_page; | |
214 | retry: | |
215 | if (likely(atomic_inc_not_zero(&huge_zero_refcount))) | |
4db0c3c2 | 216 | return READ_ONCE(huge_zero_page); |
97ae1749 KS |
217 | |
218 | zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, | |
4a6c1297 | 219 | HPAGE_PMD_ORDER); |
d8a8e1f0 KS |
220 | if (!zero_page) { |
221 | count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); | |
5918d10a | 222 | return NULL; |
d8a8e1f0 KS |
223 | } |
224 | count_vm_event(THP_ZERO_PAGE_ALLOC); | |
97ae1749 | 225 | preempt_disable(); |
5918d10a | 226 | if (cmpxchg(&huge_zero_page, NULL, zero_page)) { |
97ae1749 | 227 | preempt_enable(); |
5ddacbe9 | 228 | __free_pages(zero_page, compound_order(zero_page)); |
97ae1749 KS |
229 | goto retry; |
230 | } | |
231 | ||
232 | /* We take additional reference here. It will be put back by shrinker */ | |
233 | atomic_set(&huge_zero_refcount, 2); | |
234 | preempt_enable(); | |
4db0c3c2 | 235 | return READ_ONCE(huge_zero_page); |
4a6c1297 KS |
236 | } |
237 | ||
aa88b68c | 238 | void put_huge_zero_page(void) |
4a6c1297 | 239 | { |
97ae1749 KS |
240 | /* |
241 | * Counter should never go to zero here. Only shrinker can put | |
242 | * last reference. | |
243 | */ | |
244 | BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); | |
4a6c1297 KS |
245 | } |
246 | ||
48896466 GC |
247 | static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, |
248 | struct shrink_control *sc) | |
4a6c1297 | 249 | { |
48896466 GC |
250 | /* we can free zero page only if last reference remains */ |
251 | return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; | |
252 | } | |
97ae1749 | 253 | |
48896466 GC |
254 | static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, |
255 | struct shrink_control *sc) | |
256 | { | |
97ae1749 | 257 | if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { |
5918d10a KS |
258 | struct page *zero_page = xchg(&huge_zero_page, NULL); |
259 | BUG_ON(zero_page == NULL); | |
5ddacbe9 | 260 | __free_pages(zero_page, compound_order(zero_page)); |
48896466 | 261 | return HPAGE_PMD_NR; |
97ae1749 KS |
262 | } |
263 | ||
264 | return 0; | |
4a6c1297 KS |
265 | } |
266 | ||
97ae1749 | 267 | static struct shrinker huge_zero_page_shrinker = { |
48896466 GC |
268 | .count_objects = shrink_huge_zero_page_count, |
269 | .scan_objects = shrink_huge_zero_page_scan, | |
97ae1749 KS |
270 | .seeks = DEFAULT_SEEKS, |
271 | }; | |
272 | ||
71e3aac0 | 273 | #ifdef CONFIG_SYSFS |
ba76149f | 274 | |
444eb2a4 | 275 | static ssize_t triple_flag_store(struct kobject *kobj, |
71e3aac0 AA |
276 | struct kobj_attribute *attr, |
277 | const char *buf, size_t count, | |
278 | enum transparent_hugepage_flag enabled, | |
444eb2a4 | 279 | enum transparent_hugepage_flag deferred, |
71e3aac0 AA |
280 | enum transparent_hugepage_flag req_madv) |
281 | { | |
444eb2a4 MG |
282 | if (!memcmp("defer", buf, |
283 | min(sizeof("defer")-1, count))) { | |
284 | if (enabled == deferred) | |
285 | return -EINVAL; | |
286 | clear_bit(enabled, &transparent_hugepage_flags); | |
287 | clear_bit(req_madv, &transparent_hugepage_flags); | |
288 | set_bit(deferred, &transparent_hugepage_flags); | |
289 | } else if (!memcmp("always", buf, | |
71e3aac0 | 290 | min(sizeof("always")-1, count))) { |
444eb2a4 | 291 | clear_bit(deferred, &transparent_hugepage_flags); |
71e3aac0 | 292 | clear_bit(req_madv, &transparent_hugepage_flags); |
444eb2a4 | 293 | set_bit(enabled, &transparent_hugepage_flags); |
71e3aac0 AA |
294 | } else if (!memcmp("madvise", buf, |
295 | min(sizeof("madvise")-1, count))) { | |
296 | clear_bit(enabled, &transparent_hugepage_flags); | |
444eb2a4 | 297 | clear_bit(deferred, &transparent_hugepage_flags); |
71e3aac0 AA |
298 | set_bit(req_madv, &transparent_hugepage_flags); |
299 | } else if (!memcmp("never", buf, | |
300 | min(sizeof("never")-1, count))) { | |
301 | clear_bit(enabled, &transparent_hugepage_flags); | |
302 | clear_bit(req_madv, &transparent_hugepage_flags); | |
444eb2a4 | 303 | clear_bit(deferred, &transparent_hugepage_flags); |
71e3aac0 AA |
304 | } else |
305 | return -EINVAL; | |
306 | ||
307 | return count; | |
308 | } | |
309 | ||
310 | static ssize_t enabled_show(struct kobject *kobj, | |
311 | struct kobj_attribute *attr, char *buf) | |
312 | { | |
444eb2a4 MG |
313 | if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) |
314 | return sprintf(buf, "[always] madvise never\n"); | |
315 | else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
316 | return sprintf(buf, "always [madvise] never\n"); | |
317 | else | |
318 | return sprintf(buf, "always madvise [never]\n"); | |
71e3aac0 | 319 | } |
444eb2a4 | 320 | |
71e3aac0 AA |
321 | static ssize_t enabled_store(struct kobject *kobj, |
322 | struct kobj_attribute *attr, | |
323 | const char *buf, size_t count) | |
324 | { | |
ba76149f AA |
325 | ssize_t ret; |
326 | ||
444eb2a4 MG |
327 | ret = triple_flag_store(kobj, attr, buf, count, |
328 | TRANSPARENT_HUGEPAGE_FLAG, | |
ba76149f AA |
329 | TRANSPARENT_HUGEPAGE_FLAG, |
330 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
331 | ||
332 | if (ret > 0) { | |
911891af XG |
333 | int err; |
334 | ||
335 | mutex_lock(&khugepaged_mutex); | |
79553da2 | 336 | err = start_stop_khugepaged(); |
911891af XG |
337 | mutex_unlock(&khugepaged_mutex); |
338 | ||
ba76149f AA |
339 | if (err) |
340 | ret = err; | |
341 | } | |
342 | ||
343 | return ret; | |
71e3aac0 AA |
344 | } |
345 | static struct kobj_attribute enabled_attr = | |
346 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
347 | ||
348 | static ssize_t single_flag_show(struct kobject *kobj, | |
349 | struct kobj_attribute *attr, char *buf, | |
350 | enum transparent_hugepage_flag flag) | |
351 | { | |
e27e6151 BH |
352 | return sprintf(buf, "%d\n", |
353 | !!test_bit(flag, &transparent_hugepage_flags)); | |
71e3aac0 | 354 | } |
e27e6151 | 355 | |
71e3aac0 AA |
356 | static ssize_t single_flag_store(struct kobject *kobj, |
357 | struct kobj_attribute *attr, | |
358 | const char *buf, size_t count, | |
359 | enum transparent_hugepage_flag flag) | |
360 | { | |
e27e6151 BH |
361 | unsigned long value; |
362 | int ret; | |
363 | ||
364 | ret = kstrtoul(buf, 10, &value); | |
365 | if (ret < 0) | |
366 | return ret; | |
367 | if (value > 1) | |
368 | return -EINVAL; | |
369 | ||
370 | if (value) | |
71e3aac0 | 371 | set_bit(flag, &transparent_hugepage_flags); |
e27e6151 | 372 | else |
71e3aac0 | 373 | clear_bit(flag, &transparent_hugepage_flags); |
71e3aac0 AA |
374 | |
375 | return count; | |
376 | } | |
377 | ||
378 | /* | |
379 | * Currently defrag only disables __GFP_NOWAIT for allocation. A blind | |
380 | * __GFP_REPEAT is too aggressive, it's never worth swapping tons of | |
381 | * memory just to allocate one more hugepage. | |
382 | */ | |
383 | static ssize_t defrag_show(struct kobject *kobj, | |
384 | struct kobj_attribute *attr, char *buf) | |
385 | { | |
444eb2a4 MG |
386 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) |
387 | return sprintf(buf, "[always] defer madvise never\n"); | |
388 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) | |
389 | return sprintf(buf, "always [defer] madvise never\n"); | |
390 | else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
391 | return sprintf(buf, "always defer [madvise] never\n"); | |
392 | else | |
393 | return sprintf(buf, "always defer madvise [never]\n"); | |
394 | ||
71e3aac0 AA |
395 | } |
396 | static ssize_t defrag_store(struct kobject *kobj, | |
397 | struct kobj_attribute *attr, | |
398 | const char *buf, size_t count) | |
399 | { | |
444eb2a4 MG |
400 | return triple_flag_store(kobj, attr, buf, count, |
401 | TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, | |
402 | TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, | |
71e3aac0 AA |
403 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); |
404 | } | |
405 | static struct kobj_attribute defrag_attr = | |
406 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
407 | ||
79da5407 KS |
408 | static ssize_t use_zero_page_show(struct kobject *kobj, |
409 | struct kobj_attribute *attr, char *buf) | |
410 | { | |
411 | return single_flag_show(kobj, attr, buf, | |
412 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
413 | } | |
414 | static ssize_t use_zero_page_store(struct kobject *kobj, | |
415 | struct kobj_attribute *attr, const char *buf, size_t count) | |
416 | { | |
417 | return single_flag_store(kobj, attr, buf, count, | |
418 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
419 | } | |
420 | static struct kobj_attribute use_zero_page_attr = | |
421 | __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); | |
71e3aac0 AA |
422 | #ifdef CONFIG_DEBUG_VM |
423 | static ssize_t debug_cow_show(struct kobject *kobj, | |
424 | struct kobj_attribute *attr, char *buf) | |
425 | { | |
426 | return single_flag_show(kobj, attr, buf, | |
427 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
428 | } | |
429 | static ssize_t debug_cow_store(struct kobject *kobj, | |
430 | struct kobj_attribute *attr, | |
431 | const char *buf, size_t count) | |
432 | { | |
433 | return single_flag_store(kobj, attr, buf, count, | |
434 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
435 | } | |
436 | static struct kobj_attribute debug_cow_attr = | |
437 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
438 | #endif /* CONFIG_DEBUG_VM */ | |
439 | ||
440 | static struct attribute *hugepage_attr[] = { | |
441 | &enabled_attr.attr, | |
442 | &defrag_attr.attr, | |
79da5407 | 443 | &use_zero_page_attr.attr, |
71e3aac0 AA |
444 | #ifdef CONFIG_DEBUG_VM |
445 | &debug_cow_attr.attr, | |
446 | #endif | |
447 | NULL, | |
448 | }; | |
449 | ||
450 | static struct attribute_group hugepage_attr_group = { | |
451 | .attrs = hugepage_attr, | |
ba76149f AA |
452 | }; |
453 | ||
454 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, | |
455 | struct kobj_attribute *attr, | |
456 | char *buf) | |
457 | { | |
458 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
459 | } | |
460 | ||
461 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
462 | struct kobj_attribute *attr, | |
463 | const char *buf, size_t count) | |
464 | { | |
465 | unsigned long msecs; | |
466 | int err; | |
467 | ||
3dbb95f7 | 468 | err = kstrtoul(buf, 10, &msecs); |
ba76149f AA |
469 | if (err || msecs > UINT_MAX) |
470 | return -EINVAL; | |
471 | ||
472 | khugepaged_scan_sleep_millisecs = msecs; | |
f0508977 | 473 | khugepaged_sleep_expire = 0; |
ba76149f AA |
474 | wake_up_interruptible(&khugepaged_wait); |
475 | ||
476 | return count; | |
477 | } | |
478 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
479 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
480 | scan_sleep_millisecs_store); | |
481 | ||
482 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
483 | struct kobj_attribute *attr, | |
484 | char *buf) | |
485 | { | |
486 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
487 | } | |
488 | ||
489 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
490 | struct kobj_attribute *attr, | |
491 | const char *buf, size_t count) | |
492 | { | |
493 | unsigned long msecs; | |
494 | int err; | |
495 | ||
3dbb95f7 | 496 | err = kstrtoul(buf, 10, &msecs); |
ba76149f AA |
497 | if (err || msecs > UINT_MAX) |
498 | return -EINVAL; | |
499 | ||
500 | khugepaged_alloc_sleep_millisecs = msecs; | |
f0508977 | 501 | khugepaged_sleep_expire = 0; |
ba76149f AA |
502 | wake_up_interruptible(&khugepaged_wait); |
503 | ||
504 | return count; | |
505 | } | |
506 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
507 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
508 | alloc_sleep_millisecs_store); | |
509 | ||
510 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
511 | struct kobj_attribute *attr, | |
512 | char *buf) | |
513 | { | |
514 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
515 | } | |
516 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
517 | struct kobj_attribute *attr, | |
518 | const char *buf, size_t count) | |
519 | { | |
520 | int err; | |
521 | unsigned long pages; | |
522 | ||
3dbb95f7 | 523 | err = kstrtoul(buf, 10, &pages); |
ba76149f AA |
524 | if (err || !pages || pages > UINT_MAX) |
525 | return -EINVAL; | |
526 | ||
527 | khugepaged_pages_to_scan = pages; | |
528 | ||
529 | return count; | |
530 | } | |
531 | static struct kobj_attribute pages_to_scan_attr = | |
532 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
533 | pages_to_scan_store); | |
534 | ||
535 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
536 | struct kobj_attribute *attr, | |
537 | char *buf) | |
538 | { | |
539 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
540 | } | |
541 | static struct kobj_attribute pages_collapsed_attr = | |
542 | __ATTR_RO(pages_collapsed); | |
543 | ||
544 | static ssize_t full_scans_show(struct kobject *kobj, | |
545 | struct kobj_attribute *attr, | |
546 | char *buf) | |
547 | { | |
548 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
549 | } | |
550 | static struct kobj_attribute full_scans_attr = | |
551 | __ATTR_RO(full_scans); | |
552 | ||
553 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
554 | struct kobj_attribute *attr, char *buf) | |
555 | { | |
556 | return single_flag_show(kobj, attr, buf, | |
557 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
558 | } | |
559 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
560 | struct kobj_attribute *attr, | |
561 | const char *buf, size_t count) | |
562 | { | |
563 | return single_flag_store(kobj, attr, buf, count, | |
564 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
565 | } | |
566 | static struct kobj_attribute khugepaged_defrag_attr = | |
567 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
568 | khugepaged_defrag_store); | |
569 | ||
570 | /* | |
571 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
572 | * any unmapped ptes in turn potentially increasing the memory | |
573 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
574 | * reduce the available free memory in the system as it | |
575 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
576 | * free memory in the system during the khugepaged scan. | |
577 | */ | |
578 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
579 | struct kobj_attribute *attr, | |
580 | char *buf) | |
581 | { | |
582 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
583 | } | |
584 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
585 | struct kobj_attribute *attr, | |
586 | const char *buf, size_t count) | |
587 | { | |
588 | int err; | |
589 | unsigned long max_ptes_none; | |
590 | ||
3dbb95f7 | 591 | err = kstrtoul(buf, 10, &max_ptes_none); |
ba76149f AA |
592 | if (err || max_ptes_none > HPAGE_PMD_NR-1) |
593 | return -EINVAL; | |
594 | ||
595 | khugepaged_max_ptes_none = max_ptes_none; | |
596 | ||
597 | return count; | |
598 | } | |
599 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
600 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
601 | khugepaged_max_ptes_none_store); | |
602 | ||
70652f6e EA |
603 | static ssize_t khugepaged_max_ptes_swap_show(struct kobject *kobj, |
604 | struct kobj_attribute *attr, | |
605 | char *buf) | |
606 | { | |
607 | return sprintf(buf, "%u\n", khugepaged_max_ptes_swap); | |
608 | } | |
609 | ||
610 | static ssize_t khugepaged_max_ptes_swap_store(struct kobject *kobj, | |
611 | struct kobj_attribute *attr, | |
612 | const char *buf, size_t count) | |
613 | { | |
614 | int err; | |
615 | unsigned long max_ptes_swap; | |
616 | ||
617 | err = kstrtoul(buf, 10, &max_ptes_swap); | |
618 | if (err || max_ptes_swap > HPAGE_PMD_NR-1) | |
619 | return -EINVAL; | |
620 | ||
621 | khugepaged_max_ptes_swap = max_ptes_swap; | |
622 | ||
623 | return count; | |
624 | } | |
625 | ||
626 | static struct kobj_attribute khugepaged_max_ptes_swap_attr = | |
627 | __ATTR(max_ptes_swap, 0644, khugepaged_max_ptes_swap_show, | |
628 | khugepaged_max_ptes_swap_store); | |
629 | ||
ba76149f AA |
630 | static struct attribute *khugepaged_attr[] = { |
631 | &khugepaged_defrag_attr.attr, | |
632 | &khugepaged_max_ptes_none_attr.attr, | |
633 | &pages_to_scan_attr.attr, | |
634 | &pages_collapsed_attr.attr, | |
635 | &full_scans_attr.attr, | |
636 | &scan_sleep_millisecs_attr.attr, | |
637 | &alloc_sleep_millisecs_attr.attr, | |
70652f6e | 638 | &khugepaged_max_ptes_swap_attr.attr, |
ba76149f AA |
639 | NULL, |
640 | }; | |
641 | ||
642 | static struct attribute_group khugepaged_attr_group = { | |
643 | .attrs = khugepaged_attr, | |
644 | .name = "khugepaged", | |
71e3aac0 | 645 | }; |
71e3aac0 | 646 | |
569e5590 | 647 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
71e3aac0 | 648 | { |
71e3aac0 AA |
649 | int err; |
650 | ||
569e5590 SL |
651 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); |
652 | if (unlikely(!*hugepage_kobj)) { | |
ae3a8c1c | 653 | pr_err("failed to create transparent hugepage kobject\n"); |
569e5590 | 654 | return -ENOMEM; |
ba76149f AA |
655 | } |
656 | ||
569e5590 | 657 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); |
ba76149f | 658 | if (err) { |
ae3a8c1c | 659 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 660 | goto delete_obj; |
ba76149f AA |
661 | } |
662 | ||
569e5590 | 663 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); |
ba76149f | 664 | if (err) { |
ae3a8c1c | 665 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 666 | goto remove_hp_group; |
ba76149f | 667 | } |
569e5590 SL |
668 | |
669 | return 0; | |
670 | ||
671 | remove_hp_group: | |
672 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
673 | delete_obj: | |
674 | kobject_put(*hugepage_kobj); | |
675 | return err; | |
676 | } | |
677 | ||
678 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
679 | { | |
680 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
681 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
682 | kobject_put(hugepage_kobj); | |
683 | } | |
684 | #else | |
685 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
686 | { | |
687 | return 0; | |
688 | } | |
689 | ||
690 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
691 | { | |
692 | } | |
693 | #endif /* CONFIG_SYSFS */ | |
694 | ||
695 | static int __init hugepage_init(void) | |
696 | { | |
697 | int err; | |
698 | struct kobject *hugepage_kobj; | |
699 | ||
700 | if (!has_transparent_hugepage()) { | |
701 | transparent_hugepage_flags = 0; | |
702 | return -EINVAL; | |
703 | } | |
704 | ||
ff20c2e0 KS |
705 | khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; |
706 | khugepaged_max_ptes_none = HPAGE_PMD_NR - 1; | |
70652f6e | 707 | khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8; |
ff20c2e0 KS |
708 | /* |
709 | * hugepages can't be allocated by the buddy allocator | |
710 | */ | |
711 | MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); | |
712 | /* | |
713 | * we use page->mapping and page->index in second tail page | |
714 | * as list_head: assuming THP order >= 2 | |
715 | */ | |
716 | MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); | |
717 | ||
569e5590 SL |
718 | err = hugepage_init_sysfs(&hugepage_kobj); |
719 | if (err) | |
65ebb64f | 720 | goto err_sysfs; |
ba76149f AA |
721 | |
722 | err = khugepaged_slab_init(); | |
723 | if (err) | |
65ebb64f | 724 | goto err_slab; |
ba76149f | 725 | |
65ebb64f KS |
726 | err = register_shrinker(&huge_zero_page_shrinker); |
727 | if (err) | |
728 | goto err_hzp_shrinker; | |
9a982250 KS |
729 | err = register_shrinker(&deferred_split_shrinker); |
730 | if (err) | |
731 | goto err_split_shrinker; | |
97ae1749 | 732 | |
97562cd2 RR |
733 | /* |
734 | * By default disable transparent hugepages on smaller systems, | |
735 | * where the extra memory used could hurt more than TLB overhead | |
736 | * is likely to save. The admin can still enable it through /sys. | |
737 | */ | |
79553da2 | 738 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) { |
97562cd2 | 739 | transparent_hugepage_flags = 0; |
79553da2 KS |
740 | return 0; |
741 | } | |
97562cd2 | 742 | |
79553da2 | 743 | err = start_stop_khugepaged(); |
65ebb64f KS |
744 | if (err) |
745 | goto err_khugepaged; | |
ba76149f | 746 | |
569e5590 | 747 | return 0; |
65ebb64f | 748 | err_khugepaged: |
9a982250 KS |
749 | unregister_shrinker(&deferred_split_shrinker); |
750 | err_split_shrinker: | |
65ebb64f KS |
751 | unregister_shrinker(&huge_zero_page_shrinker); |
752 | err_hzp_shrinker: | |
753 | khugepaged_slab_exit(); | |
754 | err_slab: | |
569e5590 | 755 | hugepage_exit_sysfs(hugepage_kobj); |
65ebb64f | 756 | err_sysfs: |
ba76149f | 757 | return err; |
71e3aac0 | 758 | } |
a64fb3cd | 759 | subsys_initcall(hugepage_init); |
71e3aac0 AA |
760 | |
761 | static int __init setup_transparent_hugepage(char *str) | |
762 | { | |
763 | int ret = 0; | |
764 | if (!str) | |
765 | goto out; | |
766 | if (!strcmp(str, "always")) { | |
767 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
768 | &transparent_hugepage_flags); | |
769 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
770 | &transparent_hugepage_flags); | |
771 | ret = 1; | |
772 | } else if (!strcmp(str, "madvise")) { | |
773 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
774 | &transparent_hugepage_flags); | |
775 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
776 | &transparent_hugepage_flags); | |
777 | ret = 1; | |
778 | } else if (!strcmp(str, "never")) { | |
779 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
780 | &transparent_hugepage_flags); | |
781 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
782 | &transparent_hugepage_flags); | |
783 | ret = 1; | |
784 | } | |
785 | out: | |
786 | if (!ret) | |
ae3a8c1c | 787 | pr_warn("transparent_hugepage= cannot parse, ignored\n"); |
71e3aac0 AA |
788 | return ret; |
789 | } | |
790 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
791 | ||
b32967ff | 792 | pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) |
71e3aac0 AA |
793 | { |
794 | if (likely(vma->vm_flags & VM_WRITE)) | |
795 | pmd = pmd_mkwrite(pmd); | |
796 | return pmd; | |
797 | } | |
798 | ||
3122359a | 799 | static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot) |
b3092b3b | 800 | { |
340a43be | 801 | return pmd_mkhuge(mk_pmd(page, prot)); |
b3092b3b BL |
802 | } |
803 | ||
9a982250 KS |
804 | static inline struct list_head *page_deferred_list(struct page *page) |
805 | { | |
806 | /* | |
807 | * ->lru in the tail pages is occupied by compound_head. | |
808 | * Let's use ->mapping + ->index in the second tail page as list_head. | |
809 | */ | |
810 | return (struct list_head *)&page[2].mapping; | |
811 | } | |
812 | ||
813 | void prep_transhuge_page(struct page *page) | |
814 | { | |
815 | /* | |
816 | * we use page->mapping and page->indexlru in second tail page | |
817 | * as list_head: assuming THP order >= 2 | |
818 | */ | |
9a982250 KS |
819 | |
820 | INIT_LIST_HEAD(page_deferred_list(page)); | |
821 | set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); | |
822 | } | |
823 | ||
71e3aac0 AA |
824 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, |
825 | struct vm_area_struct *vma, | |
230c92a8 | 826 | unsigned long address, pmd_t *pmd, |
6b251fc9 AA |
827 | struct page *page, gfp_t gfp, |
828 | unsigned int flags) | |
71e3aac0 | 829 | { |
00501b53 | 830 | struct mem_cgroup *memcg; |
71e3aac0 | 831 | pgtable_t pgtable; |
c4088ebd | 832 | spinlock_t *ptl; |
230c92a8 | 833 | unsigned long haddr = address & HPAGE_PMD_MASK; |
71e3aac0 | 834 | |
309381fe | 835 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
00501b53 | 836 | |
f627c2f5 | 837 | if (mem_cgroup_try_charge(page, mm, gfp, &memcg, true)) { |
6b251fc9 AA |
838 | put_page(page); |
839 | count_vm_event(THP_FAULT_FALLBACK); | |
840 | return VM_FAULT_FALLBACK; | |
841 | } | |
00501b53 | 842 | |
71e3aac0 | 843 | pgtable = pte_alloc_one(mm, haddr); |
00501b53 | 844 | if (unlikely(!pgtable)) { |
f627c2f5 | 845 | mem_cgroup_cancel_charge(page, memcg, true); |
6b251fc9 | 846 | put_page(page); |
71e3aac0 | 847 | return VM_FAULT_OOM; |
00501b53 | 848 | } |
71e3aac0 AA |
849 | |
850 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
52f37629 MK |
851 | /* |
852 | * The memory barrier inside __SetPageUptodate makes sure that | |
853 | * clear_huge_page writes become visible before the set_pmd_at() | |
854 | * write. | |
855 | */ | |
71e3aac0 AA |
856 | __SetPageUptodate(page); |
857 | ||
c4088ebd | 858 | ptl = pmd_lock(mm, pmd); |
71e3aac0 | 859 | if (unlikely(!pmd_none(*pmd))) { |
c4088ebd | 860 | spin_unlock(ptl); |
f627c2f5 | 861 | mem_cgroup_cancel_charge(page, memcg, true); |
71e3aac0 AA |
862 | put_page(page); |
863 | pte_free(mm, pgtable); | |
864 | } else { | |
865 | pmd_t entry; | |
6b251fc9 AA |
866 | |
867 | /* Deliver the page fault to userland */ | |
868 | if (userfaultfd_missing(vma)) { | |
869 | int ret; | |
870 | ||
871 | spin_unlock(ptl); | |
f627c2f5 | 872 | mem_cgroup_cancel_charge(page, memcg, true); |
6b251fc9 AA |
873 | put_page(page); |
874 | pte_free(mm, pgtable); | |
230c92a8 | 875 | ret = handle_userfault(vma, address, flags, |
6b251fc9 AA |
876 | VM_UFFD_MISSING); |
877 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
878 | return ret; | |
879 | } | |
880 | ||
3122359a KS |
881 | entry = mk_huge_pmd(page, vma->vm_page_prot); |
882 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
d281ee61 | 883 | page_add_new_anon_rmap(page, vma, haddr, true); |
f627c2f5 | 884 | mem_cgroup_commit_charge(page, memcg, false, true); |
00501b53 | 885 | lru_cache_add_active_or_unevictable(page, vma); |
6b0b50b0 | 886 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
71e3aac0 | 887 | set_pmd_at(mm, haddr, pmd, entry); |
71e3aac0 | 888 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
e1f56c89 | 889 | atomic_long_inc(&mm->nr_ptes); |
c4088ebd | 890 | spin_unlock(ptl); |
6b251fc9 | 891 | count_vm_event(THP_FAULT_ALLOC); |
71e3aac0 AA |
892 | } |
893 | ||
aa2e878e | 894 | return 0; |
71e3aac0 AA |
895 | } |
896 | ||
444eb2a4 MG |
897 | /* |
898 | * If THP is set to always then directly reclaim/compact as necessary | |
899 | * If set to defer then do no reclaim and defer to khugepaged | |
900 | * If set to madvise and the VMA is flagged then directly reclaim/compact | |
901 | */ | |
902 | static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma) | |
903 | { | |
904 | gfp_t reclaim_flags = 0; | |
905 | ||
906 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags) && | |
907 | (vma->vm_flags & VM_HUGEPAGE)) | |
908 | reclaim_flags = __GFP_DIRECT_RECLAIM; | |
909 | else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) | |
910 | reclaim_flags = __GFP_KSWAPD_RECLAIM; | |
911 | else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) | |
912 | reclaim_flags = __GFP_DIRECT_RECLAIM; | |
913 | ||
914 | return GFP_TRANSHUGE | reclaim_flags; | |
915 | } | |
916 | ||
917 | /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */ | |
918 | static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void) | |
0bbbc0b3 | 919 | { |
444eb2a4 | 920 | return GFP_TRANSHUGE | (khugepaged_defrag() ? __GFP_DIRECT_RECLAIM : 0); |
0bbbc0b3 AA |
921 | } |
922 | ||
c4088ebd | 923 | /* Caller must hold page table lock. */ |
d295e341 | 924 | static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, |
97ae1749 | 925 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, |
5918d10a | 926 | struct page *zero_page) |
fc9fe822 KS |
927 | { |
928 | pmd_t entry; | |
7c414164 AM |
929 | if (!pmd_none(*pmd)) |
930 | return false; | |
5918d10a | 931 | entry = mk_pmd(zero_page, vma->vm_page_prot); |
fc9fe822 | 932 | entry = pmd_mkhuge(entry); |
12c9d70b MW |
933 | if (pgtable) |
934 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
fc9fe822 | 935 | set_pmd_at(mm, haddr, pmd, entry); |
e1f56c89 | 936 | atomic_long_inc(&mm->nr_ptes); |
7c414164 | 937 | return true; |
fc9fe822 KS |
938 | } |
939 | ||
71e3aac0 AA |
940 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, |
941 | unsigned long address, pmd_t *pmd, | |
942 | unsigned int flags) | |
943 | { | |
077fcf11 | 944 | gfp_t gfp; |
71e3aac0 AA |
945 | struct page *page; |
946 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
71e3aac0 | 947 | |
128ec037 | 948 | if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) |
c0292554 | 949 | return VM_FAULT_FALLBACK; |
128ec037 KS |
950 | if (unlikely(anon_vma_prepare(vma))) |
951 | return VM_FAULT_OOM; | |
6d50e60c | 952 | if (unlikely(khugepaged_enter(vma, vma->vm_flags))) |
128ec037 | 953 | return VM_FAULT_OOM; |
593befa6 | 954 | if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) && |
128ec037 | 955 | transparent_hugepage_use_zero_page()) { |
c4088ebd | 956 | spinlock_t *ptl; |
128ec037 KS |
957 | pgtable_t pgtable; |
958 | struct page *zero_page; | |
959 | bool set; | |
6b251fc9 | 960 | int ret; |
128ec037 KS |
961 | pgtable = pte_alloc_one(mm, haddr); |
962 | if (unlikely(!pgtable)) | |
ba76149f | 963 | return VM_FAULT_OOM; |
128ec037 KS |
964 | zero_page = get_huge_zero_page(); |
965 | if (unlikely(!zero_page)) { | |
966 | pte_free(mm, pgtable); | |
81ab4201 | 967 | count_vm_event(THP_FAULT_FALLBACK); |
c0292554 | 968 | return VM_FAULT_FALLBACK; |
b9bbfbe3 | 969 | } |
c4088ebd | 970 | ptl = pmd_lock(mm, pmd); |
6b251fc9 AA |
971 | ret = 0; |
972 | set = false; | |
973 | if (pmd_none(*pmd)) { | |
974 | if (userfaultfd_missing(vma)) { | |
975 | spin_unlock(ptl); | |
230c92a8 | 976 | ret = handle_userfault(vma, address, flags, |
6b251fc9 AA |
977 | VM_UFFD_MISSING); |
978 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
979 | } else { | |
980 | set_huge_zero_page(pgtable, mm, vma, | |
981 | haddr, pmd, | |
982 | zero_page); | |
983 | spin_unlock(ptl); | |
984 | set = true; | |
985 | } | |
986 | } else | |
987 | spin_unlock(ptl); | |
128ec037 KS |
988 | if (!set) { |
989 | pte_free(mm, pgtable); | |
990 | put_huge_zero_page(); | |
edad9d2c | 991 | } |
6b251fc9 | 992 | return ret; |
71e3aac0 | 993 | } |
444eb2a4 | 994 | gfp = alloc_hugepage_direct_gfpmask(vma); |
077fcf11 | 995 | page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); |
128ec037 KS |
996 | if (unlikely(!page)) { |
997 | count_vm_event(THP_FAULT_FALLBACK); | |
c0292554 | 998 | return VM_FAULT_FALLBACK; |
128ec037 | 999 | } |
9a982250 | 1000 | prep_transhuge_page(page); |
230c92a8 AA |
1001 | return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp, |
1002 | flags); | |
71e3aac0 AA |
1003 | } |
1004 | ||
ae18d6dc | 1005 | static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, |
f25748e3 | 1006 | pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write) |
5cad465d MW |
1007 | { |
1008 | struct mm_struct *mm = vma->vm_mm; | |
1009 | pmd_t entry; | |
1010 | spinlock_t *ptl; | |
1011 | ||
1012 | ptl = pmd_lock(mm, pmd); | |
f25748e3 DW |
1013 | entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); |
1014 | if (pfn_t_devmap(pfn)) | |
1015 | entry = pmd_mkdevmap(entry); | |
01871e59 RZ |
1016 | if (write) { |
1017 | entry = pmd_mkyoung(pmd_mkdirty(entry)); | |
1018 | entry = maybe_pmd_mkwrite(entry, vma); | |
5cad465d | 1019 | } |
01871e59 RZ |
1020 | set_pmd_at(mm, addr, pmd, entry); |
1021 | update_mmu_cache_pmd(vma, addr, pmd); | |
5cad465d | 1022 | spin_unlock(ptl); |
5cad465d MW |
1023 | } |
1024 | ||
1025 | int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, | |
f25748e3 | 1026 | pmd_t *pmd, pfn_t pfn, bool write) |
5cad465d MW |
1027 | { |
1028 | pgprot_t pgprot = vma->vm_page_prot; | |
1029 | /* | |
1030 | * If we had pmd_special, we could avoid all these restrictions, | |
1031 | * but we need to be consistent with PTEs and architectures that | |
1032 | * can't support a 'special' bit. | |
1033 | */ | |
1034 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); | |
1035 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == | |
1036 | (VM_PFNMAP|VM_MIXEDMAP)); | |
1037 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); | |
f25748e3 | 1038 | BUG_ON(!pfn_t_devmap(pfn)); |
5cad465d MW |
1039 | |
1040 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
1041 | return VM_FAULT_SIGBUS; | |
1042 | if (track_pfn_insert(vma, &pgprot, pfn)) | |
1043 | return VM_FAULT_SIGBUS; | |
ae18d6dc MW |
1044 | insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write); |
1045 | return VM_FAULT_NOPAGE; | |
5cad465d | 1046 | } |
dee41079 | 1047 | EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); |
5cad465d | 1048 | |
3565fce3 DW |
1049 | static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, |
1050 | pmd_t *pmd) | |
1051 | { | |
1052 | pmd_t _pmd; | |
1053 | ||
1054 | /* | |
1055 | * We should set the dirty bit only for FOLL_WRITE but for now | |
1056 | * the dirty bit in the pmd is meaningless. And if the dirty | |
1057 | * bit will become meaningful and we'll only set it with | |
1058 | * FOLL_WRITE, an atomic set_bit will be required on the pmd to | |
1059 | * set the young bit, instead of the current set_pmd_at. | |
1060 | */ | |
1061 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
1062 | if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, | |
1063 | pmd, _pmd, 1)) | |
1064 | update_mmu_cache_pmd(vma, addr, pmd); | |
1065 | } | |
1066 | ||
1067 | struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, | |
1068 | pmd_t *pmd, int flags) | |
1069 | { | |
1070 | unsigned long pfn = pmd_pfn(*pmd); | |
1071 | struct mm_struct *mm = vma->vm_mm; | |
1072 | struct dev_pagemap *pgmap; | |
1073 | struct page *page; | |
1074 | ||
1075 | assert_spin_locked(pmd_lockptr(mm, pmd)); | |
1076 | ||
1077 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1078 | return NULL; | |
1079 | ||
1080 | if (pmd_present(*pmd) && pmd_devmap(*pmd)) | |
1081 | /* pass */; | |
1082 | else | |
1083 | return NULL; | |
1084 | ||
1085 | if (flags & FOLL_TOUCH) | |
1086 | touch_pmd(vma, addr, pmd); | |
1087 | ||
1088 | /* | |
1089 | * device mapped pages can only be returned if the | |
1090 | * caller will manage the page reference count. | |
1091 | */ | |
1092 | if (!(flags & FOLL_GET)) | |
1093 | return ERR_PTR(-EEXIST); | |
1094 | ||
1095 | pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; | |
1096 | pgmap = get_dev_pagemap(pfn, NULL); | |
1097 | if (!pgmap) | |
1098 | return ERR_PTR(-EFAULT); | |
1099 | page = pfn_to_page(pfn); | |
1100 | get_page(page); | |
1101 | put_dev_pagemap(pgmap); | |
1102 | ||
1103 | return page; | |
1104 | } | |
1105 | ||
71e3aac0 AA |
1106 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
1107 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
1108 | struct vm_area_struct *vma) | |
1109 | { | |
c4088ebd | 1110 | spinlock_t *dst_ptl, *src_ptl; |
71e3aac0 AA |
1111 | struct page *src_page; |
1112 | pmd_t pmd; | |
12c9d70b | 1113 | pgtable_t pgtable = NULL; |
71e3aac0 AA |
1114 | int ret; |
1115 | ||
12c9d70b MW |
1116 | if (!vma_is_dax(vma)) { |
1117 | ret = -ENOMEM; | |
1118 | pgtable = pte_alloc_one(dst_mm, addr); | |
1119 | if (unlikely(!pgtable)) | |
1120 | goto out; | |
1121 | } | |
71e3aac0 | 1122 | |
c4088ebd KS |
1123 | dst_ptl = pmd_lock(dst_mm, dst_pmd); |
1124 | src_ptl = pmd_lockptr(src_mm, src_pmd); | |
1125 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
71e3aac0 AA |
1126 | |
1127 | ret = -EAGAIN; | |
1128 | pmd = *src_pmd; | |
5c7fb56e | 1129 | if (unlikely(!pmd_trans_huge(pmd) && !pmd_devmap(pmd))) { |
71e3aac0 AA |
1130 | pte_free(dst_mm, pgtable); |
1131 | goto out_unlock; | |
1132 | } | |
fc9fe822 | 1133 | /* |
c4088ebd | 1134 | * When page table lock is held, the huge zero pmd should not be |
fc9fe822 KS |
1135 | * under splitting since we don't split the page itself, only pmd to |
1136 | * a page table. | |
1137 | */ | |
1138 | if (is_huge_zero_pmd(pmd)) { | |
5918d10a | 1139 | struct page *zero_page; |
97ae1749 KS |
1140 | /* |
1141 | * get_huge_zero_page() will never allocate a new page here, | |
1142 | * since we already have a zero page to copy. It just takes a | |
1143 | * reference. | |
1144 | */ | |
5918d10a | 1145 | zero_page = get_huge_zero_page(); |
6b251fc9 | 1146 | set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, |
5918d10a | 1147 | zero_page); |
fc9fe822 KS |
1148 | ret = 0; |
1149 | goto out_unlock; | |
1150 | } | |
de466bd6 | 1151 | |
12c9d70b | 1152 | if (!vma_is_dax(vma)) { |
5c7fb56e DW |
1153 | /* thp accounting separate from pmd_devmap accounting */ |
1154 | src_page = pmd_page(pmd); | |
1155 | VM_BUG_ON_PAGE(!PageHead(src_page), src_page); | |
1156 | get_page(src_page); | |
1157 | page_dup_rmap(src_page, true); | |
1158 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
1159 | atomic_long_inc(&dst_mm->nr_ptes); | |
1160 | pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); | |
1161 | } | |
71e3aac0 AA |
1162 | |
1163 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
1164 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
1165 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
71e3aac0 AA |
1166 | |
1167 | ret = 0; | |
1168 | out_unlock: | |
c4088ebd KS |
1169 | spin_unlock(src_ptl); |
1170 | spin_unlock(dst_ptl); | |
71e3aac0 AA |
1171 | out: |
1172 | return ret; | |
1173 | } | |
1174 | ||
a1dd450b WD |
1175 | void huge_pmd_set_accessed(struct mm_struct *mm, |
1176 | struct vm_area_struct *vma, | |
1177 | unsigned long address, | |
1178 | pmd_t *pmd, pmd_t orig_pmd, | |
1179 | int dirty) | |
1180 | { | |
c4088ebd | 1181 | spinlock_t *ptl; |
a1dd450b WD |
1182 | pmd_t entry; |
1183 | unsigned long haddr; | |
1184 | ||
c4088ebd | 1185 | ptl = pmd_lock(mm, pmd); |
a1dd450b WD |
1186 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1187 | goto unlock; | |
1188 | ||
1189 | entry = pmd_mkyoung(orig_pmd); | |
1190 | haddr = address & HPAGE_PMD_MASK; | |
1191 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty)) | |
1192 | update_mmu_cache_pmd(vma, address, pmd); | |
1193 | ||
1194 | unlock: | |
c4088ebd | 1195 | spin_unlock(ptl); |
a1dd450b WD |
1196 | } |
1197 | ||
71e3aac0 AA |
1198 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, |
1199 | struct vm_area_struct *vma, | |
1200 | unsigned long address, | |
1201 | pmd_t *pmd, pmd_t orig_pmd, | |
1202 | struct page *page, | |
1203 | unsigned long haddr) | |
1204 | { | |
00501b53 | 1205 | struct mem_cgroup *memcg; |
c4088ebd | 1206 | spinlock_t *ptl; |
71e3aac0 AA |
1207 | pgtable_t pgtable; |
1208 | pmd_t _pmd; | |
1209 | int ret = 0, i; | |
1210 | struct page **pages; | |
2ec74c3e SG |
1211 | unsigned long mmun_start; /* For mmu_notifiers */ |
1212 | unsigned long mmun_end; /* For mmu_notifiers */ | |
71e3aac0 AA |
1213 | |
1214 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
1215 | GFP_KERNEL); | |
1216 | if (unlikely(!pages)) { | |
1217 | ret |= VM_FAULT_OOM; | |
1218 | goto out; | |
1219 | } | |
1220 | ||
1221 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
cc5d462f AK |
1222 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE | |
1223 | __GFP_OTHER_NODE, | |
19ee151e | 1224 | vma, address, page_to_nid(page)); |
b9bbfbe3 | 1225 | if (unlikely(!pages[i] || |
00501b53 | 1226 | mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL, |
f627c2f5 | 1227 | &memcg, false))) { |
b9bbfbe3 | 1228 | if (pages[i]) |
71e3aac0 | 1229 | put_page(pages[i]); |
b9bbfbe3 | 1230 | while (--i >= 0) { |
00501b53 JW |
1231 | memcg = (void *)page_private(pages[i]); |
1232 | set_page_private(pages[i], 0); | |
f627c2f5 KS |
1233 | mem_cgroup_cancel_charge(pages[i], memcg, |
1234 | false); | |
b9bbfbe3 AA |
1235 | put_page(pages[i]); |
1236 | } | |
71e3aac0 AA |
1237 | kfree(pages); |
1238 | ret |= VM_FAULT_OOM; | |
1239 | goto out; | |
1240 | } | |
00501b53 | 1241 | set_page_private(pages[i], (unsigned long)memcg); |
71e3aac0 AA |
1242 | } |
1243 | ||
1244 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1245 | copy_user_highpage(pages[i], page + i, | |
0089e485 | 1246 | haddr + PAGE_SIZE * i, vma); |
71e3aac0 AA |
1247 | __SetPageUptodate(pages[i]); |
1248 | cond_resched(); | |
1249 | } | |
1250 | ||
2ec74c3e SG |
1251 | mmun_start = haddr; |
1252 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1253 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1254 | ||
c4088ebd | 1255 | ptl = pmd_lock(mm, pmd); |
71e3aac0 AA |
1256 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1257 | goto out_free_pages; | |
309381fe | 1258 | VM_BUG_ON_PAGE(!PageHead(page), page); |
71e3aac0 | 1259 | |
8809aa2d | 1260 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
71e3aac0 AA |
1261 | /* leave pmd empty until pte is filled */ |
1262 | ||
6b0b50b0 | 1263 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
71e3aac0 AA |
1264 | pmd_populate(mm, &_pmd, pgtable); |
1265 | ||
1266 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
1267 | pte_t *pte, entry; | |
1268 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
1269 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
00501b53 JW |
1270 | memcg = (void *)page_private(pages[i]); |
1271 | set_page_private(pages[i], 0); | |
d281ee61 | 1272 | page_add_new_anon_rmap(pages[i], vma, haddr, false); |
f627c2f5 | 1273 | mem_cgroup_commit_charge(pages[i], memcg, false, false); |
00501b53 | 1274 | lru_cache_add_active_or_unevictable(pages[i], vma); |
71e3aac0 AA |
1275 | pte = pte_offset_map(&_pmd, haddr); |
1276 | VM_BUG_ON(!pte_none(*pte)); | |
1277 | set_pte_at(mm, haddr, pte, entry); | |
1278 | pte_unmap(pte); | |
1279 | } | |
1280 | kfree(pages); | |
1281 | ||
71e3aac0 AA |
1282 | smp_wmb(); /* make pte visible before pmd */ |
1283 | pmd_populate(mm, pmd, pgtable); | |
d281ee61 | 1284 | page_remove_rmap(page, true); |
c4088ebd | 1285 | spin_unlock(ptl); |
71e3aac0 | 1286 | |
2ec74c3e SG |
1287 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
1288 | ||
71e3aac0 AA |
1289 | ret |= VM_FAULT_WRITE; |
1290 | put_page(page); | |
1291 | ||
1292 | out: | |
1293 | return ret; | |
1294 | ||
1295 | out_free_pages: | |
c4088ebd | 1296 | spin_unlock(ptl); |
2ec74c3e | 1297 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
b9bbfbe3 | 1298 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
00501b53 JW |
1299 | memcg = (void *)page_private(pages[i]); |
1300 | set_page_private(pages[i], 0); | |
f627c2f5 | 1301 | mem_cgroup_cancel_charge(pages[i], memcg, false); |
71e3aac0 | 1302 | put_page(pages[i]); |
b9bbfbe3 | 1303 | } |
71e3aac0 AA |
1304 | kfree(pages); |
1305 | goto out; | |
1306 | } | |
1307 | ||
1308 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
1309 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) | |
1310 | { | |
c4088ebd | 1311 | spinlock_t *ptl; |
71e3aac0 | 1312 | int ret = 0; |
93b4796d | 1313 | struct page *page = NULL, *new_page; |
00501b53 | 1314 | struct mem_cgroup *memcg; |
71e3aac0 | 1315 | unsigned long haddr; |
2ec74c3e SG |
1316 | unsigned long mmun_start; /* For mmu_notifiers */ |
1317 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 1318 | gfp_t huge_gfp; /* for allocation and charge */ |
71e3aac0 | 1319 | |
c4088ebd | 1320 | ptl = pmd_lockptr(mm, pmd); |
81d1b09c | 1321 | VM_BUG_ON_VMA(!vma->anon_vma, vma); |
93b4796d KS |
1322 | haddr = address & HPAGE_PMD_MASK; |
1323 | if (is_huge_zero_pmd(orig_pmd)) | |
1324 | goto alloc; | |
c4088ebd | 1325 | spin_lock(ptl); |
71e3aac0 AA |
1326 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1327 | goto out_unlock; | |
1328 | ||
1329 | page = pmd_page(orig_pmd); | |
309381fe | 1330 | VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); |
1f25fe20 KS |
1331 | /* |
1332 | * We can only reuse the page if nobody else maps the huge page or it's | |
6d0a07ed | 1333 | * part. |
1f25fe20 | 1334 | */ |
6d0a07ed | 1335 | if (page_trans_huge_mapcount(page, NULL) == 1) { |
71e3aac0 AA |
1336 | pmd_t entry; |
1337 | entry = pmd_mkyoung(orig_pmd); | |
1338 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
1339 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) | |
b113da65 | 1340 | update_mmu_cache_pmd(vma, address, pmd); |
71e3aac0 AA |
1341 | ret |= VM_FAULT_WRITE; |
1342 | goto out_unlock; | |
1343 | } | |
ddc58f27 | 1344 | get_page(page); |
c4088ebd | 1345 | spin_unlock(ptl); |
93b4796d | 1346 | alloc: |
71e3aac0 | 1347 | if (transparent_hugepage_enabled(vma) && |
077fcf11 | 1348 | !transparent_hugepage_debug_cow()) { |
444eb2a4 | 1349 | huge_gfp = alloc_hugepage_direct_gfpmask(vma); |
3b363692 | 1350 | new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); |
077fcf11 | 1351 | } else |
71e3aac0 AA |
1352 | new_page = NULL; |
1353 | ||
9a982250 KS |
1354 | if (likely(new_page)) { |
1355 | prep_transhuge_page(new_page); | |
1356 | } else { | |
eecc1e42 | 1357 | if (!page) { |
78ddc534 | 1358 | split_huge_pmd(vma, pmd, address); |
e9b71ca9 | 1359 | ret |= VM_FAULT_FALLBACK; |
93b4796d KS |
1360 | } else { |
1361 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, | |
1362 | pmd, orig_pmd, page, haddr); | |
9845cbbd | 1363 | if (ret & VM_FAULT_OOM) { |
78ddc534 | 1364 | split_huge_pmd(vma, pmd, address); |
9845cbbd KS |
1365 | ret |= VM_FAULT_FALLBACK; |
1366 | } | |
ddc58f27 | 1367 | put_page(page); |
93b4796d | 1368 | } |
17766dde | 1369 | count_vm_event(THP_FAULT_FALLBACK); |
71e3aac0 AA |
1370 | goto out; |
1371 | } | |
1372 | ||
f627c2f5 KS |
1373 | if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg, |
1374 | true))) { | |
b9bbfbe3 | 1375 | put_page(new_page); |
93b4796d | 1376 | if (page) { |
78ddc534 | 1377 | split_huge_pmd(vma, pmd, address); |
ddc58f27 | 1378 | put_page(page); |
9845cbbd | 1379 | } else |
78ddc534 | 1380 | split_huge_pmd(vma, pmd, address); |
9845cbbd | 1381 | ret |= VM_FAULT_FALLBACK; |
17766dde | 1382 | count_vm_event(THP_FAULT_FALLBACK); |
b9bbfbe3 AA |
1383 | goto out; |
1384 | } | |
1385 | ||
17766dde DR |
1386 | count_vm_event(THP_FAULT_ALLOC); |
1387 | ||
eecc1e42 | 1388 | if (!page) |
93b4796d KS |
1389 | clear_huge_page(new_page, haddr, HPAGE_PMD_NR); |
1390 | else | |
1391 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); | |
71e3aac0 AA |
1392 | __SetPageUptodate(new_page); |
1393 | ||
2ec74c3e SG |
1394 | mmun_start = haddr; |
1395 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1396 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1397 | ||
c4088ebd | 1398 | spin_lock(ptl); |
93b4796d | 1399 | if (page) |
ddc58f27 | 1400 | put_page(page); |
b9bbfbe3 | 1401 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { |
c4088ebd | 1402 | spin_unlock(ptl); |
f627c2f5 | 1403 | mem_cgroup_cancel_charge(new_page, memcg, true); |
71e3aac0 | 1404 | put_page(new_page); |
2ec74c3e | 1405 | goto out_mn; |
b9bbfbe3 | 1406 | } else { |
71e3aac0 | 1407 | pmd_t entry; |
3122359a KS |
1408 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); |
1409 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
8809aa2d | 1410 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
d281ee61 | 1411 | page_add_new_anon_rmap(new_page, vma, haddr, true); |
f627c2f5 | 1412 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
00501b53 | 1413 | lru_cache_add_active_or_unevictable(new_page, vma); |
71e3aac0 | 1414 | set_pmd_at(mm, haddr, pmd, entry); |
b113da65 | 1415 | update_mmu_cache_pmd(vma, address, pmd); |
eecc1e42 | 1416 | if (!page) { |
93b4796d | 1417 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
97ae1749 KS |
1418 | put_huge_zero_page(); |
1419 | } else { | |
309381fe | 1420 | VM_BUG_ON_PAGE(!PageHead(page), page); |
d281ee61 | 1421 | page_remove_rmap(page, true); |
93b4796d KS |
1422 | put_page(page); |
1423 | } | |
71e3aac0 AA |
1424 | ret |= VM_FAULT_WRITE; |
1425 | } | |
c4088ebd | 1426 | spin_unlock(ptl); |
2ec74c3e SG |
1427 | out_mn: |
1428 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
71e3aac0 AA |
1429 | out: |
1430 | return ret; | |
2ec74c3e | 1431 | out_unlock: |
c4088ebd | 1432 | spin_unlock(ptl); |
2ec74c3e | 1433 | return ret; |
71e3aac0 AA |
1434 | } |
1435 | ||
b676b293 | 1436 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, |
71e3aac0 AA |
1437 | unsigned long addr, |
1438 | pmd_t *pmd, | |
1439 | unsigned int flags) | |
1440 | { | |
b676b293 | 1441 | struct mm_struct *mm = vma->vm_mm; |
71e3aac0 AA |
1442 | struct page *page = NULL; |
1443 | ||
c4088ebd | 1444 | assert_spin_locked(pmd_lockptr(mm, pmd)); |
71e3aac0 AA |
1445 | |
1446 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1447 | goto out; | |
1448 | ||
85facf25 KS |
1449 | /* Avoid dumping huge zero page */ |
1450 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) | |
1451 | return ERR_PTR(-EFAULT); | |
1452 | ||
2b4847e7 | 1453 | /* Full NUMA hinting faults to serialise migration in fault paths */ |
8a0516ed | 1454 | if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) |
2b4847e7 MG |
1455 | goto out; |
1456 | ||
71e3aac0 | 1457 | page = pmd_page(*pmd); |
309381fe | 1458 | VM_BUG_ON_PAGE(!PageHead(page), page); |
3565fce3 DW |
1459 | if (flags & FOLL_TOUCH) |
1460 | touch_pmd(vma, addr, pmd); | |
de60f5f1 | 1461 | if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { |
e90309c9 KS |
1462 | /* |
1463 | * We don't mlock() pte-mapped THPs. This way we can avoid | |
1464 | * leaking mlocked pages into non-VM_LOCKED VMAs. | |
1465 | * | |
1466 | * In most cases the pmd is the only mapping of the page as we | |
1467 | * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for | |
1468 | * writable private mappings in populate_vma_page_range(). | |
1469 | * | |
1470 | * The only scenario when we have the page shared here is if we | |
1471 | * mlocking read-only mapping shared over fork(). We skip | |
1472 | * mlocking such pages. | |
1473 | */ | |
1474 | if (compound_mapcount(page) == 1 && !PageDoubleMap(page) && | |
1475 | page->mapping && trylock_page(page)) { | |
b676b293 DR |
1476 | lru_add_drain(); |
1477 | if (page->mapping) | |
1478 | mlock_vma_page(page); | |
1479 | unlock_page(page); | |
1480 | } | |
1481 | } | |
71e3aac0 | 1482 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
309381fe | 1483 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
71e3aac0 | 1484 | if (flags & FOLL_GET) |
ddc58f27 | 1485 | get_page(page); |
71e3aac0 AA |
1486 | |
1487 | out: | |
1488 | return page; | |
1489 | } | |
1490 | ||
d10e63f2 | 1491 | /* NUMA hinting page fault entry point for trans huge pmds */ |
4daae3b4 MG |
1492 | int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, |
1493 | unsigned long addr, pmd_t pmd, pmd_t *pmdp) | |
d10e63f2 | 1494 | { |
c4088ebd | 1495 | spinlock_t *ptl; |
b8916634 | 1496 | struct anon_vma *anon_vma = NULL; |
b32967ff | 1497 | struct page *page; |
d10e63f2 | 1498 | unsigned long haddr = addr & HPAGE_PMD_MASK; |
8191acbd | 1499 | int page_nid = -1, this_nid = numa_node_id(); |
90572890 | 1500 | int target_nid, last_cpupid = -1; |
8191acbd MG |
1501 | bool page_locked; |
1502 | bool migrated = false; | |
b191f9b1 | 1503 | bool was_writable; |
6688cc05 | 1504 | int flags = 0; |
d10e63f2 | 1505 | |
c0e7cad9 MG |
1506 | /* A PROT_NONE fault should not end up here */ |
1507 | BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))); | |
1508 | ||
c4088ebd | 1509 | ptl = pmd_lock(mm, pmdp); |
d10e63f2 MG |
1510 | if (unlikely(!pmd_same(pmd, *pmdp))) |
1511 | goto out_unlock; | |
1512 | ||
de466bd6 MG |
1513 | /* |
1514 | * If there are potential migrations, wait for completion and retry | |
1515 | * without disrupting NUMA hinting information. Do not relock and | |
1516 | * check_same as the page may no longer be mapped. | |
1517 | */ | |
1518 | if (unlikely(pmd_trans_migrating(*pmdp))) { | |
5d833062 | 1519 | page = pmd_page(*pmdp); |
de466bd6 | 1520 | spin_unlock(ptl); |
5d833062 | 1521 | wait_on_page_locked(page); |
de466bd6 MG |
1522 | goto out; |
1523 | } | |
1524 | ||
d10e63f2 | 1525 | page = pmd_page(pmd); |
a1a46184 | 1526 | BUG_ON(is_huge_zero_page(page)); |
8191acbd | 1527 | page_nid = page_to_nid(page); |
90572890 | 1528 | last_cpupid = page_cpupid_last(page); |
03c5a6e1 | 1529 | count_vm_numa_event(NUMA_HINT_FAULTS); |
04bb2f94 | 1530 | if (page_nid == this_nid) { |
03c5a6e1 | 1531 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
04bb2f94 RR |
1532 | flags |= TNF_FAULT_LOCAL; |
1533 | } | |
4daae3b4 | 1534 | |
bea66fbd MG |
1535 | /* See similar comment in do_numa_page for explanation */ |
1536 | if (!(vma->vm_flags & VM_WRITE)) | |
6688cc05 PZ |
1537 | flags |= TNF_NO_GROUP; |
1538 | ||
ff9042b1 MG |
1539 | /* |
1540 | * Acquire the page lock to serialise THP migrations but avoid dropping | |
1541 | * page_table_lock if at all possible | |
1542 | */ | |
b8916634 MG |
1543 | page_locked = trylock_page(page); |
1544 | target_nid = mpol_misplaced(page, vma, haddr); | |
1545 | if (target_nid == -1) { | |
1546 | /* If the page was locked, there are no parallel migrations */ | |
a54a407f | 1547 | if (page_locked) |
b8916634 | 1548 | goto clear_pmdnuma; |
2b4847e7 | 1549 | } |
4daae3b4 | 1550 | |
de466bd6 | 1551 | /* Migration could have started since the pmd_trans_migrating check */ |
2b4847e7 | 1552 | if (!page_locked) { |
c4088ebd | 1553 | spin_unlock(ptl); |
b8916634 | 1554 | wait_on_page_locked(page); |
a54a407f | 1555 | page_nid = -1; |
b8916634 MG |
1556 | goto out; |
1557 | } | |
1558 | ||
2b4847e7 MG |
1559 | /* |
1560 | * Page is misplaced. Page lock serialises migrations. Acquire anon_vma | |
1561 | * to serialises splits | |
1562 | */ | |
b8916634 | 1563 | get_page(page); |
c4088ebd | 1564 | spin_unlock(ptl); |
b8916634 | 1565 | anon_vma = page_lock_anon_vma_read(page); |
4daae3b4 | 1566 | |
c69307d5 | 1567 | /* Confirm the PMD did not change while page_table_lock was released */ |
c4088ebd | 1568 | spin_lock(ptl); |
b32967ff MG |
1569 | if (unlikely(!pmd_same(pmd, *pmdp))) { |
1570 | unlock_page(page); | |
1571 | put_page(page); | |
a54a407f | 1572 | page_nid = -1; |
4daae3b4 | 1573 | goto out_unlock; |
b32967ff | 1574 | } |
ff9042b1 | 1575 | |
c3a489ca MG |
1576 | /* Bail if we fail to protect against THP splits for any reason */ |
1577 | if (unlikely(!anon_vma)) { | |
1578 | put_page(page); | |
1579 | page_nid = -1; | |
1580 | goto clear_pmdnuma; | |
1581 | } | |
1582 | ||
a54a407f MG |
1583 | /* |
1584 | * Migrate the THP to the requested node, returns with page unlocked | |
8a0516ed | 1585 | * and access rights restored. |
a54a407f | 1586 | */ |
c4088ebd | 1587 | spin_unlock(ptl); |
b32967ff | 1588 | migrated = migrate_misplaced_transhuge_page(mm, vma, |
340ef390 | 1589 | pmdp, pmd, addr, page, target_nid); |
6688cc05 PZ |
1590 | if (migrated) { |
1591 | flags |= TNF_MIGRATED; | |
8191acbd | 1592 | page_nid = target_nid; |
074c2381 MG |
1593 | } else |
1594 | flags |= TNF_MIGRATE_FAIL; | |
b32967ff | 1595 | |
8191acbd | 1596 | goto out; |
b32967ff | 1597 | clear_pmdnuma: |
a54a407f | 1598 | BUG_ON(!PageLocked(page)); |
b191f9b1 | 1599 | was_writable = pmd_write(pmd); |
4d942466 | 1600 | pmd = pmd_modify(pmd, vma->vm_page_prot); |
b7b04004 | 1601 | pmd = pmd_mkyoung(pmd); |
b191f9b1 MG |
1602 | if (was_writable) |
1603 | pmd = pmd_mkwrite(pmd); | |
d10e63f2 | 1604 | set_pmd_at(mm, haddr, pmdp, pmd); |
d10e63f2 | 1605 | update_mmu_cache_pmd(vma, addr, pmdp); |
a54a407f | 1606 | unlock_page(page); |
d10e63f2 | 1607 | out_unlock: |
c4088ebd | 1608 | spin_unlock(ptl); |
b8916634 MG |
1609 | |
1610 | out: | |
1611 | if (anon_vma) | |
1612 | page_unlock_anon_vma_read(anon_vma); | |
1613 | ||
8191acbd | 1614 | if (page_nid != -1) |
6688cc05 | 1615 | task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags); |
8191acbd | 1616 | |
d10e63f2 MG |
1617 | return 0; |
1618 | } | |
1619 | ||
b8d3c4c3 MK |
1620 | int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
1621 | pmd_t *pmd, unsigned long addr, unsigned long next) | |
1622 | ||
1623 | { | |
1624 | spinlock_t *ptl; | |
1625 | pmd_t orig_pmd; | |
1626 | struct page *page; | |
1627 | struct mm_struct *mm = tlb->mm; | |
1628 | int ret = 0; | |
1629 | ||
b6ec57f4 KS |
1630 | ptl = pmd_trans_huge_lock(pmd, vma); |
1631 | if (!ptl) | |
25eedabe | 1632 | goto out_unlocked; |
b8d3c4c3 MK |
1633 | |
1634 | orig_pmd = *pmd; | |
1635 | if (is_huge_zero_pmd(orig_pmd)) { | |
1636 | ret = 1; | |
1637 | goto out; | |
1638 | } | |
1639 | ||
1640 | page = pmd_page(orig_pmd); | |
1641 | /* | |
1642 | * If other processes are mapping this page, we couldn't discard | |
1643 | * the page unless they all do MADV_FREE so let's skip the page. | |
1644 | */ | |
1645 | if (page_mapcount(page) != 1) | |
1646 | goto out; | |
1647 | ||
1648 | if (!trylock_page(page)) | |
1649 | goto out; | |
1650 | ||
1651 | /* | |
1652 | * If user want to discard part-pages of THP, split it so MADV_FREE | |
1653 | * will deactivate only them. | |
1654 | */ | |
1655 | if (next - addr != HPAGE_PMD_SIZE) { | |
1656 | get_page(page); | |
1657 | spin_unlock(ptl); | |
9818b8cd | 1658 | split_huge_page(page); |
b8d3c4c3 MK |
1659 | put_page(page); |
1660 | unlock_page(page); | |
b8d3c4c3 MK |
1661 | goto out_unlocked; |
1662 | } | |
1663 | ||
1664 | if (PageDirty(page)) | |
1665 | ClearPageDirty(page); | |
1666 | unlock_page(page); | |
1667 | ||
1668 | if (PageActive(page)) | |
1669 | deactivate_page(page); | |
1670 | ||
1671 | if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { | |
1672 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1673 | tlb->fullmm); | |
1674 | orig_pmd = pmd_mkold(orig_pmd); | |
1675 | orig_pmd = pmd_mkclean(orig_pmd); | |
1676 | ||
1677 | set_pmd_at(mm, addr, pmd, orig_pmd); | |
1678 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1679 | } | |
1680 | ret = 1; | |
1681 | out: | |
1682 | spin_unlock(ptl); | |
1683 | out_unlocked: | |
1684 | return ret; | |
1685 | } | |
1686 | ||
71e3aac0 | 1687 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
f21760b1 | 1688 | pmd_t *pmd, unsigned long addr) |
71e3aac0 | 1689 | { |
da146769 | 1690 | pmd_t orig_pmd; |
bf929152 | 1691 | spinlock_t *ptl; |
71e3aac0 | 1692 | |
b6ec57f4 KS |
1693 | ptl = __pmd_trans_huge_lock(pmd, vma); |
1694 | if (!ptl) | |
da146769 KS |
1695 | return 0; |
1696 | /* | |
1697 | * For architectures like ppc64 we look at deposited pgtable | |
1698 | * when calling pmdp_huge_get_and_clear. So do the | |
1699 | * pgtable_trans_huge_withdraw after finishing pmdp related | |
1700 | * operations. | |
1701 | */ | |
1702 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1703 | tlb->fullmm); | |
1704 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1705 | if (vma_is_dax(vma)) { | |
1706 | spin_unlock(ptl); | |
1707 | if (is_huge_zero_pmd(orig_pmd)) | |
aa88b68c | 1708 | tlb_remove_page(tlb, pmd_page(orig_pmd)); |
da146769 KS |
1709 | } else if (is_huge_zero_pmd(orig_pmd)) { |
1710 | pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); | |
1711 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1712 | spin_unlock(ptl); | |
aa88b68c | 1713 | tlb_remove_page(tlb, pmd_page(orig_pmd)); |
da146769 KS |
1714 | } else { |
1715 | struct page *page = pmd_page(orig_pmd); | |
d281ee61 | 1716 | page_remove_rmap(page, true); |
da146769 KS |
1717 | VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); |
1718 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1719 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
1720 | pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); | |
1721 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1722 | spin_unlock(ptl); | |
e77b0852 | 1723 | tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); |
025c5b24 | 1724 | } |
da146769 | 1725 | return 1; |
71e3aac0 AA |
1726 | } |
1727 | ||
bf8616d5 | 1728 | bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, |
37a1c49a AA |
1729 | unsigned long new_addr, unsigned long old_end, |
1730 | pmd_t *old_pmd, pmd_t *new_pmd) | |
1731 | { | |
bf929152 | 1732 | spinlock_t *old_ptl, *new_ptl; |
37a1c49a | 1733 | pmd_t pmd; |
37a1c49a AA |
1734 | struct mm_struct *mm = vma->vm_mm; |
1735 | ||
1736 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1737 | (new_addr & ~HPAGE_PMD_MASK) || | |
bf8616d5 | 1738 | old_end - old_addr < HPAGE_PMD_SIZE) |
4b471e88 | 1739 | return false; |
37a1c49a AA |
1740 | |
1741 | /* | |
1742 | * The destination pmd shouldn't be established, free_pgtables() | |
1743 | * should have release it. | |
1744 | */ | |
1745 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1746 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
4b471e88 | 1747 | return false; |
37a1c49a AA |
1748 | } |
1749 | ||
bf929152 KS |
1750 | /* |
1751 | * We don't have to worry about the ordering of src and dst | |
1752 | * ptlocks because exclusive mmap_sem prevents deadlock. | |
1753 | */ | |
b6ec57f4 KS |
1754 | old_ptl = __pmd_trans_huge_lock(old_pmd, vma); |
1755 | if (old_ptl) { | |
bf929152 KS |
1756 | new_ptl = pmd_lockptr(mm, new_pmd); |
1757 | if (new_ptl != old_ptl) | |
1758 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); | |
8809aa2d | 1759 | pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); |
025c5b24 | 1760 | VM_BUG_ON(!pmd_none(*new_pmd)); |
3592806c | 1761 | |
69a8ec2d KS |
1762 | if (pmd_move_must_withdraw(new_ptl, old_ptl) && |
1763 | vma_is_anonymous(vma)) { | |
b3084f4d | 1764 | pgtable_t pgtable; |
3592806c KS |
1765 | pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); |
1766 | pgtable_trans_huge_deposit(mm, new_pmd, pgtable); | |
3592806c | 1767 | } |
b3084f4d AK |
1768 | set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); |
1769 | if (new_ptl != old_ptl) | |
1770 | spin_unlock(new_ptl); | |
bf929152 | 1771 | spin_unlock(old_ptl); |
4b471e88 | 1772 | return true; |
37a1c49a | 1773 | } |
4b471e88 | 1774 | return false; |
37a1c49a AA |
1775 | } |
1776 | ||
f123d74a MG |
1777 | /* |
1778 | * Returns | |
1779 | * - 0 if PMD could not be locked | |
1780 | * - 1 if PMD was locked but protections unchange and TLB flush unnecessary | |
1781 | * - HPAGE_PMD_NR is protections changed and TLB flush necessary | |
1782 | */ | |
cd7548ab | 1783 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
e944fd67 | 1784 | unsigned long addr, pgprot_t newprot, int prot_numa) |
cd7548ab JW |
1785 | { |
1786 | struct mm_struct *mm = vma->vm_mm; | |
bf929152 | 1787 | spinlock_t *ptl; |
cd7548ab JW |
1788 | int ret = 0; |
1789 | ||
b6ec57f4 KS |
1790 | ptl = __pmd_trans_huge_lock(pmd, vma); |
1791 | if (ptl) { | |
025c5b24 | 1792 | pmd_t entry; |
b191f9b1 | 1793 | bool preserve_write = prot_numa && pmd_write(*pmd); |
ba68bc01 | 1794 | ret = 1; |
e944fd67 MG |
1795 | |
1796 | /* | |
1797 | * Avoid trapping faults against the zero page. The read-only | |
1798 | * data is likely to be read-cached on the local CPU and | |
1799 | * local/remote hits to the zero page are not interesting. | |
1800 | */ | |
1801 | if (prot_numa && is_huge_zero_pmd(*pmd)) { | |
1802 | spin_unlock(ptl); | |
ba68bc01 | 1803 | return ret; |
e944fd67 MG |
1804 | } |
1805 | ||
10c1045f | 1806 | if (!prot_numa || !pmd_protnone(*pmd)) { |
8809aa2d | 1807 | entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd); |
10c1045f | 1808 | entry = pmd_modify(entry, newprot); |
b191f9b1 MG |
1809 | if (preserve_write) |
1810 | entry = pmd_mkwrite(entry); | |
10c1045f MG |
1811 | ret = HPAGE_PMD_NR; |
1812 | set_pmd_at(mm, addr, pmd, entry); | |
b191f9b1 | 1813 | BUG_ON(!preserve_write && pmd_write(entry)); |
10c1045f | 1814 | } |
bf929152 | 1815 | spin_unlock(ptl); |
025c5b24 NH |
1816 | } |
1817 | ||
1818 | return ret; | |
1819 | } | |
1820 | ||
1821 | /* | |
4b471e88 | 1822 | * Returns true if a given pmd maps a thp, false otherwise. |
025c5b24 | 1823 | * |
4b471e88 KS |
1824 | * Note that if it returns true, this routine returns without unlocking page |
1825 | * table lock. So callers must unlock it. | |
025c5b24 | 1826 | */ |
b6ec57f4 | 1827 | spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) |
025c5b24 | 1828 | { |
b6ec57f4 KS |
1829 | spinlock_t *ptl; |
1830 | ptl = pmd_lock(vma->vm_mm, pmd); | |
5c7fb56e | 1831 | if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd))) |
b6ec57f4 KS |
1832 | return ptl; |
1833 | spin_unlock(ptl); | |
1834 | return NULL; | |
cd7548ab JW |
1835 | } |
1836 | ||
9050d7eb | 1837 | #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE) |
78f11a25 | 1838 | |
60ab3244 AA |
1839 | int hugepage_madvise(struct vm_area_struct *vma, |
1840 | unsigned long *vm_flags, int advice) | |
0af4e98b | 1841 | { |
a664b2d8 AA |
1842 | switch (advice) { |
1843 | case MADV_HUGEPAGE: | |
1e1836e8 AT |
1844 | #ifdef CONFIG_S390 |
1845 | /* | |
1846 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
1847 | * can't handle this properly after s390_enable_sie, so we simply | |
1848 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
1849 | */ | |
1850 | if (mm_has_pgste(vma->vm_mm)) | |
1851 | return 0; | |
1852 | #endif | |
a664b2d8 AA |
1853 | /* |
1854 | * Be somewhat over-protective like KSM for now! | |
1855 | */ | |
1a763615 | 1856 | if (*vm_flags & VM_NO_THP) |
a664b2d8 AA |
1857 | return -EINVAL; |
1858 | *vm_flags &= ~VM_NOHUGEPAGE; | |
1859 | *vm_flags |= VM_HUGEPAGE; | |
60ab3244 AA |
1860 | /* |
1861 | * If the vma become good for khugepaged to scan, | |
1862 | * register it here without waiting a page fault that | |
1863 | * may not happen any time soon. | |
1864 | */ | |
6d50e60c | 1865 | if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags))) |
60ab3244 | 1866 | return -ENOMEM; |
a664b2d8 AA |
1867 | break; |
1868 | case MADV_NOHUGEPAGE: | |
1869 | /* | |
1870 | * Be somewhat over-protective like KSM for now! | |
1871 | */ | |
1a763615 | 1872 | if (*vm_flags & VM_NO_THP) |
a664b2d8 AA |
1873 | return -EINVAL; |
1874 | *vm_flags &= ~VM_HUGEPAGE; | |
1875 | *vm_flags |= VM_NOHUGEPAGE; | |
60ab3244 AA |
1876 | /* |
1877 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
1878 | * this vma even if we leave the mm registered in khugepaged if | |
1879 | * it got registered before VM_NOHUGEPAGE was set. | |
1880 | */ | |
a664b2d8 AA |
1881 | break; |
1882 | } | |
0af4e98b AA |
1883 | |
1884 | return 0; | |
1885 | } | |
1886 | ||
ba76149f AA |
1887 | static int __init khugepaged_slab_init(void) |
1888 | { | |
1889 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
1890 | sizeof(struct mm_slot), | |
1891 | __alignof__(struct mm_slot), 0, NULL); | |
1892 | if (!mm_slot_cache) | |
1893 | return -ENOMEM; | |
1894 | ||
1895 | return 0; | |
1896 | } | |
1897 | ||
65ebb64f KS |
1898 | static void __init khugepaged_slab_exit(void) |
1899 | { | |
1900 | kmem_cache_destroy(mm_slot_cache); | |
1901 | } | |
1902 | ||
ba76149f AA |
1903 | static inline struct mm_slot *alloc_mm_slot(void) |
1904 | { | |
1905 | if (!mm_slot_cache) /* initialization failed */ | |
1906 | return NULL; | |
1907 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
1908 | } | |
1909 | ||
1910 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
1911 | { | |
1912 | kmem_cache_free(mm_slot_cache, mm_slot); | |
1913 | } | |
1914 | ||
ba76149f AA |
1915 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) |
1916 | { | |
1917 | struct mm_slot *mm_slot; | |
ba76149f | 1918 | |
b67bfe0d | 1919 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) |
ba76149f AA |
1920 | if (mm == mm_slot->mm) |
1921 | return mm_slot; | |
43b5fbbd | 1922 | |
ba76149f AA |
1923 | return NULL; |
1924 | } | |
1925 | ||
1926 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
1927 | struct mm_slot *mm_slot) | |
1928 | { | |
ba76149f | 1929 | mm_slot->mm = mm; |
43b5fbbd | 1930 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); |
ba76149f AA |
1931 | } |
1932 | ||
1933 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
1934 | { | |
1935 | return atomic_read(&mm->mm_users) == 0; | |
1936 | } | |
1937 | ||
1938 | int __khugepaged_enter(struct mm_struct *mm) | |
1939 | { | |
1940 | struct mm_slot *mm_slot; | |
1941 | int wakeup; | |
1942 | ||
1943 | mm_slot = alloc_mm_slot(); | |
1944 | if (!mm_slot) | |
1945 | return -ENOMEM; | |
1946 | ||
1947 | /* __khugepaged_exit() must not run from under us */ | |
96dad67f | 1948 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); |
ba76149f AA |
1949 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { |
1950 | free_mm_slot(mm_slot); | |
1951 | return 0; | |
1952 | } | |
1953 | ||
1954 | spin_lock(&khugepaged_mm_lock); | |
1955 | insert_to_mm_slots_hash(mm, mm_slot); | |
1956 | /* | |
1957 | * Insert just behind the scanning cursor, to let the area settle | |
1958 | * down a little. | |
1959 | */ | |
1960 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
1961 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
1962 | spin_unlock(&khugepaged_mm_lock); | |
1963 | ||
1964 | atomic_inc(&mm->mm_count); | |
1965 | if (wakeup) | |
1966 | wake_up_interruptible(&khugepaged_wait); | |
1967 | ||
1968 | return 0; | |
1969 | } | |
1970 | ||
6d50e60c DR |
1971 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, |
1972 | unsigned long vm_flags) | |
ba76149f AA |
1973 | { |
1974 | unsigned long hstart, hend; | |
1975 | if (!vma->anon_vma) | |
1976 | /* | |
1977 | * Not yet faulted in so we will register later in the | |
1978 | * page fault if needed. | |
1979 | */ | |
1980 | return 0; | |
3486b85a | 1981 | if (vma->vm_ops || (vm_flags & VM_NO_THP)) |
ba76149f AA |
1982 | /* khugepaged not yet working on file or special mappings */ |
1983 | return 0; | |
ba76149f AA |
1984 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
1985 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1986 | if (hstart < hend) | |
6d50e60c | 1987 | return khugepaged_enter(vma, vm_flags); |
ba76149f AA |
1988 | return 0; |
1989 | } | |
1990 | ||
1991 | void __khugepaged_exit(struct mm_struct *mm) | |
1992 | { | |
1993 | struct mm_slot *mm_slot; | |
1994 | int free = 0; | |
1995 | ||
1996 | spin_lock(&khugepaged_mm_lock); | |
1997 | mm_slot = get_mm_slot(mm); | |
1998 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
43b5fbbd | 1999 | hash_del(&mm_slot->hash); |
ba76149f AA |
2000 | list_del(&mm_slot->mm_node); |
2001 | free = 1; | |
2002 | } | |
d788e80a | 2003 | spin_unlock(&khugepaged_mm_lock); |
ba76149f AA |
2004 | |
2005 | if (free) { | |
ba76149f AA |
2006 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); |
2007 | free_mm_slot(mm_slot); | |
2008 | mmdrop(mm); | |
2009 | } else if (mm_slot) { | |
ba76149f AA |
2010 | /* |
2011 | * This is required to serialize against | |
2012 | * khugepaged_test_exit() (which is guaranteed to run | |
2013 | * under mmap sem read mode). Stop here (after we | |
2014 | * return all pagetables will be destroyed) until | |
2015 | * khugepaged has finished working on the pagetables | |
2016 | * under the mmap_sem. | |
2017 | */ | |
2018 | down_write(&mm->mmap_sem); | |
2019 | up_write(&mm->mmap_sem); | |
d788e80a | 2020 | } |
ba76149f AA |
2021 | } |
2022 | ||
2023 | static void release_pte_page(struct page *page) | |
2024 | { | |
2025 | /* 0 stands for page_is_file_cache(page) == false */ | |
2026 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
2027 | unlock_page(page); | |
2028 | putback_lru_page(page); | |
2029 | } | |
2030 | ||
2031 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
2032 | { | |
2033 | while (--_pte >= pte) { | |
2034 | pte_t pteval = *_pte; | |
ca0984ca | 2035 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) |
ba76149f AA |
2036 | release_pte_page(pte_page(pteval)); |
2037 | } | |
2038 | } | |
2039 | ||
ba76149f AA |
2040 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, |
2041 | unsigned long address, | |
2042 | pte_t *pte) | |
2043 | { | |
7d2eba05 | 2044 | struct page *page = NULL; |
ba76149f | 2045 | pte_t *_pte; |
7d2eba05 | 2046 | int none_or_zero = 0, result = 0; |
10359213 | 2047 | bool referenced = false, writable = false; |
7d2eba05 | 2048 | |
ba76149f AA |
2049 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; |
2050 | _pte++, address += PAGE_SIZE) { | |
2051 | pte_t pteval = *_pte; | |
47aee4d8 MK |
2052 | if (pte_none(pteval) || (pte_present(pteval) && |
2053 | is_zero_pfn(pte_pfn(pteval)))) { | |
c1294d05 | 2054 | if (!userfaultfd_armed(vma) && |
7d2eba05 | 2055 | ++none_or_zero <= khugepaged_max_ptes_none) { |
ba76149f | 2056 | continue; |
7d2eba05 EA |
2057 | } else { |
2058 | result = SCAN_EXCEED_NONE_PTE; | |
ba76149f | 2059 | goto out; |
7d2eba05 | 2060 | } |
ba76149f | 2061 | } |
7d2eba05 EA |
2062 | if (!pte_present(pteval)) { |
2063 | result = SCAN_PTE_NON_PRESENT; | |
ba76149f | 2064 | goto out; |
7d2eba05 | 2065 | } |
ba76149f | 2066 | page = vm_normal_page(vma, address, pteval); |
7d2eba05 EA |
2067 | if (unlikely(!page)) { |
2068 | result = SCAN_PAGE_NULL; | |
ba76149f | 2069 | goto out; |
7d2eba05 | 2070 | } |
344aa35c | 2071 | |
309381fe SL |
2072 | VM_BUG_ON_PAGE(PageCompound(page), page); |
2073 | VM_BUG_ON_PAGE(!PageAnon(page), page); | |
2074 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
ba76149f | 2075 | |
ba76149f AA |
2076 | /* |
2077 | * We can do it before isolate_lru_page because the | |
2078 | * page can't be freed from under us. NOTE: PG_lock | |
2079 | * is needed to serialize against split_huge_page | |
2080 | * when invoked from the VM. | |
2081 | */ | |
7d2eba05 EA |
2082 | if (!trylock_page(page)) { |
2083 | result = SCAN_PAGE_LOCK; | |
ba76149f | 2084 | goto out; |
7d2eba05 | 2085 | } |
10359213 EA |
2086 | |
2087 | /* | |
2088 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2089 | * The page must only be referenced by the scanned process | |
2090 | * and page swap cache. | |
2091 | */ | |
2092 | if (page_count(page) != 1 + !!PageSwapCache(page)) { | |
2093 | unlock_page(page); | |
7d2eba05 | 2094 | result = SCAN_PAGE_COUNT; |
10359213 EA |
2095 | goto out; |
2096 | } | |
2097 | if (pte_write(pteval)) { | |
2098 | writable = true; | |
2099 | } else { | |
6d0a07ed AA |
2100 | if (PageSwapCache(page) && |
2101 | !reuse_swap_page(page, NULL)) { | |
10359213 | 2102 | unlock_page(page); |
7d2eba05 | 2103 | result = SCAN_SWAP_CACHE_PAGE; |
10359213 EA |
2104 | goto out; |
2105 | } | |
2106 | /* | |
2107 | * Page is not in the swap cache. It can be collapsed | |
2108 | * into a THP. | |
2109 | */ | |
2110 | } | |
2111 | ||
ba76149f AA |
2112 | /* |
2113 | * Isolate the page to avoid collapsing an hugepage | |
2114 | * currently in use by the VM. | |
2115 | */ | |
2116 | if (isolate_lru_page(page)) { | |
2117 | unlock_page(page); | |
7d2eba05 | 2118 | result = SCAN_DEL_PAGE_LRU; |
ba76149f AA |
2119 | goto out; |
2120 | } | |
2121 | /* 0 stands for page_is_file_cache(page) == false */ | |
2122 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
309381fe SL |
2123 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
2124 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
ba76149f AA |
2125 | |
2126 | /* If there is no mapped pte young don't collapse the page */ | |
33c3fc71 VD |
2127 | if (pte_young(pteval) || |
2128 | page_is_young(page) || PageReferenced(page) || | |
8ee53820 | 2129 | mmu_notifier_test_young(vma->vm_mm, address)) |
10359213 | 2130 | referenced = true; |
ba76149f | 2131 | } |
7d2eba05 EA |
2132 | if (likely(writable)) { |
2133 | if (likely(referenced)) { | |
2134 | result = SCAN_SUCCEED; | |
16fd0fe4 | 2135 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, |
7d2eba05 EA |
2136 | referenced, writable, result); |
2137 | return 1; | |
2138 | } | |
2139 | } else { | |
2140 | result = SCAN_PAGE_RO; | |
2141 | } | |
2142 | ||
ba76149f | 2143 | out: |
344aa35c | 2144 | release_pte_pages(pte, _pte); |
16fd0fe4 | 2145 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, |
7d2eba05 | 2146 | referenced, writable, result); |
344aa35c | 2147 | return 0; |
ba76149f AA |
2148 | } |
2149 | ||
2150 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
2151 | struct vm_area_struct *vma, | |
2152 | unsigned long address, | |
2153 | spinlock_t *ptl) | |
2154 | { | |
2155 | pte_t *_pte; | |
2156 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { | |
2157 | pte_t pteval = *_pte; | |
2158 | struct page *src_page; | |
2159 | ||
ca0984ca | 2160 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
ba76149f AA |
2161 | clear_user_highpage(page, address); |
2162 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
ca0984ca EA |
2163 | if (is_zero_pfn(pte_pfn(pteval))) { |
2164 | /* | |
2165 | * ptl mostly unnecessary. | |
2166 | */ | |
2167 | spin_lock(ptl); | |
2168 | /* | |
2169 | * paravirt calls inside pte_clear here are | |
2170 | * superfluous. | |
2171 | */ | |
2172 | pte_clear(vma->vm_mm, address, _pte); | |
2173 | spin_unlock(ptl); | |
2174 | } | |
ba76149f AA |
2175 | } else { |
2176 | src_page = pte_page(pteval); | |
2177 | copy_user_highpage(page, src_page, address, vma); | |
309381fe | 2178 | VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page); |
ba76149f AA |
2179 | release_pte_page(src_page); |
2180 | /* | |
2181 | * ptl mostly unnecessary, but preempt has to | |
2182 | * be disabled to update the per-cpu stats | |
2183 | * inside page_remove_rmap(). | |
2184 | */ | |
2185 | spin_lock(ptl); | |
2186 | /* | |
2187 | * paravirt calls inside pte_clear here are | |
2188 | * superfluous. | |
2189 | */ | |
2190 | pte_clear(vma->vm_mm, address, _pte); | |
d281ee61 | 2191 | page_remove_rmap(src_page, false); |
ba76149f AA |
2192 | spin_unlock(ptl); |
2193 | free_page_and_swap_cache(src_page); | |
2194 | } | |
2195 | ||
2196 | address += PAGE_SIZE; | |
2197 | page++; | |
2198 | } | |
2199 | } | |
2200 | ||
26234f36 | 2201 | static void khugepaged_alloc_sleep(void) |
ba76149f | 2202 | { |
bde43c6c PM |
2203 | DEFINE_WAIT(wait); |
2204 | ||
2205 | add_wait_queue(&khugepaged_wait, &wait); | |
2206 | freezable_schedule_timeout_interruptible( | |
2207 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
2208 | remove_wait_queue(&khugepaged_wait, &wait); | |
26234f36 | 2209 | } |
ba76149f | 2210 | |
9f1b868a BL |
2211 | static int khugepaged_node_load[MAX_NUMNODES]; |
2212 | ||
14a4e214 DR |
2213 | static bool khugepaged_scan_abort(int nid) |
2214 | { | |
2215 | int i; | |
2216 | ||
2217 | /* | |
2218 | * If zone_reclaim_mode is disabled, then no extra effort is made to | |
2219 | * allocate memory locally. | |
2220 | */ | |
2221 | if (!zone_reclaim_mode) | |
2222 | return false; | |
2223 | ||
2224 | /* If there is a count for this node already, it must be acceptable */ | |
2225 | if (khugepaged_node_load[nid]) | |
2226 | return false; | |
2227 | ||
2228 | for (i = 0; i < MAX_NUMNODES; i++) { | |
2229 | if (!khugepaged_node_load[i]) | |
2230 | continue; | |
2231 | if (node_distance(nid, i) > RECLAIM_DISTANCE) | |
2232 | return true; | |
2233 | } | |
2234 | return false; | |
2235 | } | |
2236 | ||
26234f36 | 2237 | #ifdef CONFIG_NUMA |
9f1b868a BL |
2238 | static int khugepaged_find_target_node(void) |
2239 | { | |
2240 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
2241 | int nid, target_node = 0, max_value = 0; | |
2242 | ||
2243 | /* find first node with max normal pages hit */ | |
2244 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
2245 | if (khugepaged_node_load[nid] > max_value) { | |
2246 | max_value = khugepaged_node_load[nid]; | |
2247 | target_node = nid; | |
2248 | } | |
2249 | ||
2250 | /* do some balance if several nodes have the same hit record */ | |
2251 | if (target_node <= last_khugepaged_target_node) | |
2252 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
2253 | nid++) | |
2254 | if (max_value == khugepaged_node_load[nid]) { | |
2255 | target_node = nid; | |
2256 | break; | |
2257 | } | |
2258 | ||
2259 | last_khugepaged_target_node = target_node; | |
2260 | return target_node; | |
2261 | } | |
2262 | ||
26234f36 XG |
2263 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) |
2264 | { | |
2265 | if (IS_ERR(*hpage)) { | |
2266 | if (!*wait) | |
2267 | return false; | |
2268 | ||
2269 | *wait = false; | |
e3b4126c | 2270 | *hpage = NULL; |
26234f36 XG |
2271 | khugepaged_alloc_sleep(); |
2272 | } else if (*hpage) { | |
2273 | put_page(*hpage); | |
2274 | *hpage = NULL; | |
2275 | } | |
2276 | ||
2277 | return true; | |
2278 | } | |
2279 | ||
3b363692 MH |
2280 | static struct page * |
2281 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
d6669d68 | 2282 | unsigned long address, int node) |
26234f36 | 2283 | { |
309381fe | 2284 | VM_BUG_ON_PAGE(*hpage, *hpage); |
8b164568 | 2285 | |
ce83d217 | 2286 | /* |
8b164568 VB |
2287 | * Before allocating the hugepage, release the mmap_sem read lock. |
2288 | * The allocation can take potentially a long time if it involves | |
2289 | * sync compaction, and we do not need to hold the mmap_sem during | |
2290 | * that. We will recheck the vma after taking it again in write mode. | |
ce83d217 | 2291 | */ |
8b164568 VB |
2292 | up_read(&mm->mmap_sem); |
2293 | ||
96db800f | 2294 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); |
26234f36 | 2295 | if (unlikely(!*hpage)) { |
81ab4201 | 2296 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); |
ce83d217 | 2297 | *hpage = ERR_PTR(-ENOMEM); |
26234f36 | 2298 | return NULL; |
ce83d217 | 2299 | } |
26234f36 | 2300 | |
9a982250 | 2301 | prep_transhuge_page(*hpage); |
65b3c07b | 2302 | count_vm_event(THP_COLLAPSE_ALLOC); |
26234f36 XG |
2303 | return *hpage; |
2304 | } | |
2305 | #else | |
9f1b868a BL |
2306 | static int khugepaged_find_target_node(void) |
2307 | { | |
2308 | return 0; | |
2309 | } | |
2310 | ||
444eb2a4 | 2311 | static inline struct page *alloc_khugepaged_hugepage(void) |
10dc4155 | 2312 | { |
9a982250 KS |
2313 | struct page *page; |
2314 | ||
444eb2a4 MG |
2315 | page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(), |
2316 | HPAGE_PMD_ORDER); | |
9a982250 KS |
2317 | if (page) |
2318 | prep_transhuge_page(page); | |
2319 | return page; | |
10dc4155 BL |
2320 | } |
2321 | ||
26234f36 XG |
2322 | static struct page *khugepaged_alloc_hugepage(bool *wait) |
2323 | { | |
2324 | struct page *hpage; | |
2325 | ||
2326 | do { | |
444eb2a4 | 2327 | hpage = alloc_khugepaged_hugepage(); |
26234f36 XG |
2328 | if (!hpage) { |
2329 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
2330 | if (!*wait) | |
2331 | return NULL; | |
2332 | ||
2333 | *wait = false; | |
2334 | khugepaged_alloc_sleep(); | |
2335 | } else | |
2336 | count_vm_event(THP_COLLAPSE_ALLOC); | |
2337 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
2338 | ||
2339 | return hpage; | |
2340 | } | |
2341 | ||
2342 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
2343 | { | |
2344 | if (!*hpage) | |
2345 | *hpage = khugepaged_alloc_hugepage(wait); | |
2346 | ||
2347 | if (unlikely(!*hpage)) | |
2348 | return false; | |
2349 | ||
2350 | return true; | |
2351 | } | |
2352 | ||
3b363692 MH |
2353 | static struct page * |
2354 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
d6669d68 | 2355 | unsigned long address, int node) |
26234f36 XG |
2356 | { |
2357 | up_read(&mm->mmap_sem); | |
2358 | VM_BUG_ON(!*hpage); | |
3b363692 | 2359 | |
26234f36 XG |
2360 | return *hpage; |
2361 | } | |
692e0b35 AA |
2362 | #endif |
2363 | ||
fa475e51 BL |
2364 | static bool hugepage_vma_check(struct vm_area_struct *vma) |
2365 | { | |
2366 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || | |
2367 | (vma->vm_flags & VM_NOHUGEPAGE)) | |
2368 | return false; | |
fa475e51 BL |
2369 | if (!vma->anon_vma || vma->vm_ops) |
2370 | return false; | |
2371 | if (is_vma_temporary_stack(vma)) | |
2372 | return false; | |
3486b85a | 2373 | return !(vma->vm_flags & VM_NO_THP); |
fa475e51 BL |
2374 | } |
2375 | ||
72695862 EA |
2376 | /* |
2377 | * If mmap_sem temporarily dropped, revalidate vma | |
2378 | * before taking mmap_sem. | |
2379 | * Return 0 if succeeds, otherwise return none-zero | |
2380 | * value (scan code). | |
2381 | */ | |
2382 | ||
2383 | static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address) | |
2384 | { | |
2385 | struct vm_area_struct *vma; | |
2386 | unsigned long hstart, hend; | |
2387 | ||
2388 | if (unlikely(khugepaged_test_exit(mm))) | |
2389 | return SCAN_ANY_PROCESS; | |
2390 | ||
2391 | vma = find_vma(mm, address); | |
2392 | if (!vma) | |
2393 | return SCAN_VMA_NULL; | |
2394 | ||
2395 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2396 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2397 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
2398 | return SCAN_ADDRESS_RANGE; | |
2399 | if (!hugepage_vma_check(vma)) | |
2400 | return SCAN_VMA_CHECK; | |
2401 | return 0; | |
2402 | } | |
2403 | ||
8a966ed7 EA |
2404 | /* |
2405 | * Bring missing pages in from swap, to complete THP collapse. | |
2406 | * Only done if khugepaged_scan_pmd believes it is worthwhile. | |
2407 | * | |
2408 | * Called and returns without pte mapped or spinlocks held, | |
2409 | * but with mmap_sem held to protect against vma changes. | |
2410 | */ | |
2411 | ||
72695862 | 2412 | static bool __collapse_huge_page_swapin(struct mm_struct *mm, |
8a966ed7 EA |
2413 | struct vm_area_struct *vma, |
2414 | unsigned long address, pmd_t *pmd) | |
2415 | { | |
2416 | unsigned long _address; | |
2417 | pte_t *pte, pteval; | |
2418 | int swapped_in = 0, ret = 0; | |
2419 | ||
2420 | pte = pte_offset_map(pmd, address); | |
2421 | for (_address = address; _address < address + HPAGE_PMD_NR*PAGE_SIZE; | |
2422 | pte++, _address += PAGE_SIZE) { | |
2423 | pteval = *pte; | |
2424 | if (!is_swap_pte(pteval)) | |
2425 | continue; | |
2426 | swapped_in++; | |
2427 | ret = do_swap_page(mm, vma, _address, pte, pmd, | |
72695862 | 2428 | FAULT_FLAG_ALLOW_RETRY, |
8a966ed7 | 2429 | pteval); |
72695862 EA |
2430 | /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */ |
2431 | if (ret & VM_FAULT_RETRY) { | |
2432 | down_read(&mm->mmap_sem); | |
2433 | /* vma is no longer available, don't continue to swapin */ | |
2434 | if (hugepage_vma_revalidate(mm, address)) | |
2435 | return false; | |
1f52e67e KS |
2436 | /* check if the pmd is still valid */ |
2437 | if (mm_find_pmd(mm, address) != pmd) | |
2438 | return false; | |
72695862 | 2439 | } |
8a966ed7 EA |
2440 | if (ret & VM_FAULT_ERROR) { |
2441 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, 0); | |
72695862 | 2442 | return false; |
8a966ed7 EA |
2443 | } |
2444 | /* pte is unmapped now, we need to map it */ | |
2445 | pte = pte_offset_map(pmd, _address); | |
2446 | } | |
2447 | pte--; | |
2448 | pte_unmap(pte); | |
2449 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, 1); | |
72695862 | 2450 | return true; |
8a966ed7 EA |
2451 | } |
2452 | ||
26234f36 XG |
2453 | static void collapse_huge_page(struct mm_struct *mm, |
2454 | unsigned long address, | |
2455 | struct page **hpage, | |
2456 | struct vm_area_struct *vma, | |
2457 | int node) | |
2458 | { | |
26234f36 XG |
2459 | pmd_t *pmd, _pmd; |
2460 | pte_t *pte; | |
2461 | pgtable_t pgtable; | |
2462 | struct page *new_page; | |
c4088ebd | 2463 | spinlock_t *pmd_ptl, *pte_ptl; |
629d9d1c | 2464 | int isolated = 0, result = 0; |
00501b53 | 2465 | struct mem_cgroup *memcg; |
2ec74c3e SG |
2466 | unsigned long mmun_start; /* For mmu_notifiers */ |
2467 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 2468 | gfp_t gfp; |
26234f36 XG |
2469 | |
2470 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2471 | ||
3b363692 | 2472 | /* Only allocate from the target node */ |
444eb2a4 | 2473 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_OTHER_NODE | __GFP_THISNODE; |
3b363692 | 2474 | |
26234f36 | 2475 | /* release the mmap_sem read lock. */ |
d6669d68 | 2476 | new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node); |
7d2eba05 EA |
2477 | if (!new_page) { |
2478 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
2479 | goto out_nolock; | |
2480 | } | |
26234f36 | 2481 | |
f627c2f5 | 2482 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { |
7d2eba05 EA |
2483 | result = SCAN_CGROUP_CHARGE_FAIL; |
2484 | goto out_nolock; | |
2485 | } | |
ba76149f | 2486 | |
72695862 EA |
2487 | down_read(&mm->mmap_sem); |
2488 | result = hugepage_vma_revalidate(mm, address); | |
8024ee2a EA |
2489 | if (result) { |
2490 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
2491 | up_read(&mm->mmap_sem); | |
2492 | goto out_nolock; | |
2493 | } | |
ba76149f | 2494 | |
6219049a | 2495 | pmd = mm_find_pmd(mm, address); |
7d2eba05 EA |
2496 | if (!pmd) { |
2497 | result = SCAN_PMD_NULL; | |
8024ee2a EA |
2498 | mem_cgroup_cancel_charge(new_page, memcg, true); |
2499 | up_read(&mm->mmap_sem); | |
2500 | goto out_nolock; | |
7d2eba05 | 2501 | } |
ba76149f | 2502 | |
72695862 EA |
2503 | /* |
2504 | * __collapse_huge_page_swapin always returns with mmap_sem locked. | |
2505 | * If it fails, release mmap_sem and jump directly out. | |
2506 | * Continuing to collapse causes inconsistency. | |
2507 | */ | |
2508 | if (!__collapse_huge_page_swapin(mm, vma, address, pmd)) { | |
8024ee2a | 2509 | mem_cgroup_cancel_charge(new_page, memcg, true); |
72695862 | 2510 | up_read(&mm->mmap_sem); |
8024ee2a | 2511 | goto out_nolock; |
72695862 EA |
2512 | } |
2513 | ||
2514 | up_read(&mm->mmap_sem); | |
2515 | /* | |
2516 | * Prevent all access to pagetables with the exception of | |
2517 | * gup_fast later handled by the ptep_clear_flush and the VM | |
2518 | * handled by the anon_vma lock + PG_lock. | |
2519 | */ | |
2520 | down_write(&mm->mmap_sem); | |
2521 | result = hugepage_vma_revalidate(mm, address); | |
2522 | if (result) | |
2523 | goto out; | |
1f52e67e KS |
2524 | /* check if the pmd is still valid */ |
2525 | if (mm_find_pmd(mm, address) != pmd) | |
2526 | goto out; | |
8a966ed7 | 2527 | |
4fc3f1d6 | 2528 | anon_vma_lock_write(vma->anon_vma); |
ba76149f AA |
2529 | |
2530 | pte = pte_offset_map(pmd, address); | |
c4088ebd | 2531 | pte_ptl = pte_lockptr(mm, pmd); |
ba76149f | 2532 | |
2ec74c3e SG |
2533 | mmun_start = address; |
2534 | mmun_end = address + HPAGE_PMD_SIZE; | |
2535 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
c4088ebd | 2536 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
ba76149f AA |
2537 | /* |
2538 | * After this gup_fast can't run anymore. This also removes | |
2539 | * any huge TLB entry from the CPU so we won't allow | |
2540 | * huge and small TLB entries for the same virtual address | |
2541 | * to avoid the risk of CPU bugs in that area. | |
2542 | */ | |
15a25b2e | 2543 | _pmd = pmdp_collapse_flush(vma, address, pmd); |
c4088ebd | 2544 | spin_unlock(pmd_ptl); |
2ec74c3e | 2545 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
ba76149f | 2546 | |
c4088ebd | 2547 | spin_lock(pte_ptl); |
ba76149f | 2548 | isolated = __collapse_huge_page_isolate(vma, address, pte); |
c4088ebd | 2549 | spin_unlock(pte_ptl); |
ba76149f AA |
2550 | |
2551 | if (unlikely(!isolated)) { | |
453c7192 | 2552 | pte_unmap(pte); |
c4088ebd | 2553 | spin_lock(pmd_ptl); |
ba76149f | 2554 | BUG_ON(!pmd_none(*pmd)); |
7c342512 AK |
2555 | /* |
2556 | * We can only use set_pmd_at when establishing | |
2557 | * hugepmds and never for establishing regular pmds that | |
2558 | * points to regular pagetables. Use pmd_populate for that | |
2559 | */ | |
2560 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
c4088ebd | 2561 | spin_unlock(pmd_ptl); |
08b52706 | 2562 | anon_vma_unlock_write(vma->anon_vma); |
7d2eba05 | 2563 | result = SCAN_FAIL; |
ce83d217 | 2564 | goto out; |
ba76149f AA |
2565 | } |
2566 | ||
2567 | /* | |
2568 | * All pages are isolated and locked so anon_vma rmap | |
2569 | * can't run anymore. | |
2570 | */ | |
08b52706 | 2571 | anon_vma_unlock_write(vma->anon_vma); |
ba76149f | 2572 | |
c4088ebd | 2573 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); |
453c7192 | 2574 | pte_unmap(pte); |
ba76149f AA |
2575 | __SetPageUptodate(new_page); |
2576 | pgtable = pmd_pgtable(_pmd); | |
ba76149f | 2577 | |
3122359a KS |
2578 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); |
2579 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); | |
ba76149f AA |
2580 | |
2581 | /* | |
2582 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
2583 | * this is needed to avoid the copy_huge_page writes to become | |
2584 | * visible after the set_pmd_at() write. | |
2585 | */ | |
2586 | smp_wmb(); | |
2587 | ||
c4088ebd | 2588 | spin_lock(pmd_ptl); |
ba76149f | 2589 | BUG_ON(!pmd_none(*pmd)); |
d281ee61 | 2590 | page_add_new_anon_rmap(new_page, vma, address, true); |
f627c2f5 | 2591 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
00501b53 | 2592 | lru_cache_add_active_or_unevictable(new_page, vma); |
fce144b4 | 2593 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
ba76149f | 2594 | set_pmd_at(mm, address, pmd, _pmd); |
b113da65 | 2595 | update_mmu_cache_pmd(vma, address, pmd); |
c4088ebd | 2596 | spin_unlock(pmd_ptl); |
ba76149f AA |
2597 | |
2598 | *hpage = NULL; | |
420256ef | 2599 | |
ba76149f | 2600 | khugepaged_pages_collapsed++; |
7d2eba05 | 2601 | result = SCAN_SUCCEED; |
ce83d217 | 2602 | out_up_write: |
ba76149f | 2603 | up_write(&mm->mmap_sem); |
7d2eba05 EA |
2604 | out_nolock: |
2605 | trace_mm_collapse_huge_page(mm, isolated, result); | |
2606 | return; | |
ce83d217 | 2607 | out: |
f627c2f5 | 2608 | mem_cgroup_cancel_charge(new_page, memcg, true); |
ce83d217 | 2609 | goto out_up_write; |
ba76149f AA |
2610 | } |
2611 | ||
2612 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
2613 | struct vm_area_struct *vma, | |
2614 | unsigned long address, | |
2615 | struct page **hpage) | |
2616 | { | |
ba76149f AA |
2617 | pmd_t *pmd; |
2618 | pte_t *pte, *_pte; | |
7d2eba05 EA |
2619 | int ret = 0, none_or_zero = 0, result = 0; |
2620 | struct page *page = NULL; | |
ba76149f AA |
2621 | unsigned long _address; |
2622 | spinlock_t *ptl; | |
70652f6e | 2623 | int node = NUMA_NO_NODE, unmapped = 0; |
10359213 | 2624 | bool writable = false, referenced = false; |
ba76149f AA |
2625 | |
2626 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2627 | ||
6219049a | 2628 | pmd = mm_find_pmd(mm, address); |
7d2eba05 EA |
2629 | if (!pmd) { |
2630 | result = SCAN_PMD_NULL; | |
ba76149f | 2631 | goto out; |
7d2eba05 | 2632 | } |
ba76149f | 2633 | |
9f1b868a | 2634 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); |
ba76149f AA |
2635 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
2636 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
2637 | _pte++, _address += PAGE_SIZE) { | |
2638 | pte_t pteval = *_pte; | |
70652f6e EA |
2639 | if (is_swap_pte(pteval)) { |
2640 | if (++unmapped <= khugepaged_max_ptes_swap) { | |
2641 | continue; | |
2642 | } else { | |
2643 | result = SCAN_EXCEED_SWAP_PTE; | |
2644 | goto out_unmap; | |
2645 | } | |
2646 | } | |
ca0984ca | 2647 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
c1294d05 | 2648 | if (!userfaultfd_armed(vma) && |
7d2eba05 | 2649 | ++none_or_zero <= khugepaged_max_ptes_none) { |
ba76149f | 2650 | continue; |
7d2eba05 EA |
2651 | } else { |
2652 | result = SCAN_EXCEED_NONE_PTE; | |
ba76149f | 2653 | goto out_unmap; |
7d2eba05 | 2654 | } |
ba76149f | 2655 | } |
7d2eba05 EA |
2656 | if (!pte_present(pteval)) { |
2657 | result = SCAN_PTE_NON_PRESENT; | |
ba76149f | 2658 | goto out_unmap; |
7d2eba05 | 2659 | } |
10359213 EA |
2660 | if (pte_write(pteval)) |
2661 | writable = true; | |
2662 | ||
ba76149f | 2663 | page = vm_normal_page(vma, _address, pteval); |
7d2eba05 EA |
2664 | if (unlikely(!page)) { |
2665 | result = SCAN_PAGE_NULL; | |
ba76149f | 2666 | goto out_unmap; |
7d2eba05 | 2667 | } |
b1caa957 KS |
2668 | |
2669 | /* TODO: teach khugepaged to collapse THP mapped with pte */ | |
2670 | if (PageCompound(page)) { | |
2671 | result = SCAN_PAGE_COMPOUND; | |
2672 | goto out_unmap; | |
2673 | } | |
2674 | ||
5c4b4be3 | 2675 | /* |
9f1b868a BL |
2676 | * Record which node the original page is from and save this |
2677 | * information to khugepaged_node_load[]. | |
2678 | * Khupaged will allocate hugepage from the node has the max | |
2679 | * hit record. | |
5c4b4be3 | 2680 | */ |
9f1b868a | 2681 | node = page_to_nid(page); |
7d2eba05 EA |
2682 | if (khugepaged_scan_abort(node)) { |
2683 | result = SCAN_SCAN_ABORT; | |
14a4e214 | 2684 | goto out_unmap; |
7d2eba05 | 2685 | } |
9f1b868a | 2686 | khugepaged_node_load[node]++; |
7d2eba05 | 2687 | if (!PageLRU(page)) { |
0fda2788 | 2688 | result = SCAN_PAGE_LRU; |
7d2eba05 EA |
2689 | goto out_unmap; |
2690 | } | |
2691 | if (PageLocked(page)) { | |
2692 | result = SCAN_PAGE_LOCK; | |
ba76149f | 2693 | goto out_unmap; |
7d2eba05 EA |
2694 | } |
2695 | if (!PageAnon(page)) { | |
2696 | result = SCAN_PAGE_ANON; | |
2697 | goto out_unmap; | |
2698 | } | |
2699 | ||
10359213 EA |
2700 | /* |
2701 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2702 | * The page must only be referenced by the scanned process | |
2703 | * and page swap cache. | |
2704 | */ | |
7d2eba05 EA |
2705 | if (page_count(page) != 1 + !!PageSwapCache(page)) { |
2706 | result = SCAN_PAGE_COUNT; | |
ba76149f | 2707 | goto out_unmap; |
7d2eba05 | 2708 | } |
33c3fc71 VD |
2709 | if (pte_young(pteval) || |
2710 | page_is_young(page) || PageReferenced(page) || | |
8ee53820 | 2711 | mmu_notifier_test_young(vma->vm_mm, address)) |
10359213 | 2712 | referenced = true; |
ba76149f | 2713 | } |
7d2eba05 EA |
2714 | if (writable) { |
2715 | if (referenced) { | |
2716 | result = SCAN_SUCCEED; | |
2717 | ret = 1; | |
2718 | } else { | |
2719 | result = SCAN_NO_REFERENCED_PAGE; | |
2720 | } | |
2721 | } else { | |
2722 | result = SCAN_PAGE_RO; | |
2723 | } | |
ba76149f AA |
2724 | out_unmap: |
2725 | pte_unmap_unlock(pte, ptl); | |
9f1b868a BL |
2726 | if (ret) { |
2727 | node = khugepaged_find_target_node(); | |
ce83d217 | 2728 | /* collapse_huge_page will return with the mmap_sem released */ |
5c4b4be3 | 2729 | collapse_huge_page(mm, address, hpage, vma, node); |
9f1b868a | 2730 | } |
ba76149f | 2731 | out: |
16fd0fe4 | 2732 | trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, |
70652f6e | 2733 | none_or_zero, result, unmapped); |
ba76149f AA |
2734 | return ret; |
2735 | } | |
2736 | ||
2737 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
2738 | { | |
2739 | struct mm_struct *mm = mm_slot->mm; | |
2740 | ||
b9980cdc | 2741 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2742 | |
2743 | if (khugepaged_test_exit(mm)) { | |
2744 | /* free mm_slot */ | |
43b5fbbd | 2745 | hash_del(&mm_slot->hash); |
ba76149f AA |
2746 | list_del(&mm_slot->mm_node); |
2747 | ||
2748 | /* | |
2749 | * Not strictly needed because the mm exited already. | |
2750 | * | |
2751 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
2752 | */ | |
2753 | ||
2754 | /* khugepaged_mm_lock actually not necessary for the below */ | |
2755 | free_mm_slot(mm_slot); | |
2756 | mmdrop(mm); | |
2757 | } | |
2758 | } | |
2759 | ||
2760 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
2761 | struct page **hpage) | |
2f1da642 HS |
2762 | __releases(&khugepaged_mm_lock) |
2763 | __acquires(&khugepaged_mm_lock) | |
ba76149f AA |
2764 | { |
2765 | struct mm_slot *mm_slot; | |
2766 | struct mm_struct *mm; | |
2767 | struct vm_area_struct *vma; | |
2768 | int progress = 0; | |
2769 | ||
2770 | VM_BUG_ON(!pages); | |
b9980cdc | 2771 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2772 | |
2773 | if (khugepaged_scan.mm_slot) | |
2774 | mm_slot = khugepaged_scan.mm_slot; | |
2775 | else { | |
2776 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2777 | struct mm_slot, mm_node); | |
2778 | khugepaged_scan.address = 0; | |
2779 | khugepaged_scan.mm_slot = mm_slot; | |
2780 | } | |
2781 | spin_unlock(&khugepaged_mm_lock); | |
2782 | ||
2783 | mm = mm_slot->mm; | |
2784 | down_read(&mm->mmap_sem); | |
2785 | if (unlikely(khugepaged_test_exit(mm))) | |
2786 | vma = NULL; | |
2787 | else | |
2788 | vma = find_vma(mm, khugepaged_scan.address); | |
2789 | ||
2790 | progress++; | |
2791 | for (; vma; vma = vma->vm_next) { | |
2792 | unsigned long hstart, hend; | |
2793 | ||
2794 | cond_resched(); | |
2795 | if (unlikely(khugepaged_test_exit(mm))) { | |
2796 | progress++; | |
2797 | break; | |
2798 | } | |
fa475e51 BL |
2799 | if (!hugepage_vma_check(vma)) { |
2800 | skip: | |
ba76149f AA |
2801 | progress++; |
2802 | continue; | |
2803 | } | |
ba76149f AA |
2804 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2805 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
a7d6e4ec AA |
2806 | if (hstart >= hend) |
2807 | goto skip; | |
2808 | if (khugepaged_scan.address > hend) | |
2809 | goto skip; | |
ba76149f AA |
2810 | if (khugepaged_scan.address < hstart) |
2811 | khugepaged_scan.address = hstart; | |
a7d6e4ec | 2812 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); |
ba76149f AA |
2813 | |
2814 | while (khugepaged_scan.address < hend) { | |
2815 | int ret; | |
2816 | cond_resched(); | |
2817 | if (unlikely(khugepaged_test_exit(mm))) | |
2818 | goto breakouterloop; | |
2819 | ||
2820 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2821 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2822 | hend); | |
2823 | ret = khugepaged_scan_pmd(mm, vma, | |
2824 | khugepaged_scan.address, | |
2825 | hpage); | |
2826 | /* move to next address */ | |
2827 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2828 | progress += HPAGE_PMD_NR; | |
2829 | if (ret) | |
2830 | /* we released mmap_sem so break loop */ | |
2831 | goto breakouterloop_mmap_sem; | |
2832 | if (progress >= pages) | |
2833 | goto breakouterloop; | |
2834 | } | |
2835 | } | |
2836 | breakouterloop: | |
2837 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2838 | breakouterloop_mmap_sem: | |
2839 | ||
2840 | spin_lock(&khugepaged_mm_lock); | |
a7d6e4ec | 2841 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); |
ba76149f AA |
2842 | /* |
2843 | * Release the current mm_slot if this mm is about to die, or | |
2844 | * if we scanned all vmas of this mm. | |
2845 | */ | |
2846 | if (khugepaged_test_exit(mm) || !vma) { | |
2847 | /* | |
2848 | * Make sure that if mm_users is reaching zero while | |
2849 | * khugepaged runs here, khugepaged_exit will find | |
2850 | * mm_slot not pointing to the exiting mm. | |
2851 | */ | |
2852 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2853 | khugepaged_scan.mm_slot = list_entry( | |
2854 | mm_slot->mm_node.next, | |
2855 | struct mm_slot, mm_node); | |
2856 | khugepaged_scan.address = 0; | |
2857 | } else { | |
2858 | khugepaged_scan.mm_slot = NULL; | |
2859 | khugepaged_full_scans++; | |
2860 | } | |
2861 | ||
2862 | collect_mm_slot(mm_slot); | |
2863 | } | |
2864 | ||
2865 | return progress; | |
2866 | } | |
2867 | ||
2868 | static int khugepaged_has_work(void) | |
2869 | { | |
2870 | return !list_empty(&khugepaged_scan.mm_head) && | |
2871 | khugepaged_enabled(); | |
2872 | } | |
2873 | ||
2874 | static int khugepaged_wait_event(void) | |
2875 | { | |
2876 | return !list_empty(&khugepaged_scan.mm_head) || | |
2017c0bf | 2877 | kthread_should_stop(); |
ba76149f AA |
2878 | } |
2879 | ||
d516904b | 2880 | static void khugepaged_do_scan(void) |
ba76149f | 2881 | { |
d516904b | 2882 | struct page *hpage = NULL; |
ba76149f AA |
2883 | unsigned int progress = 0, pass_through_head = 0; |
2884 | unsigned int pages = khugepaged_pages_to_scan; | |
d516904b | 2885 | bool wait = true; |
ba76149f AA |
2886 | |
2887 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2888 | ||
2889 | while (progress < pages) { | |
26234f36 | 2890 | if (!khugepaged_prealloc_page(&hpage, &wait)) |
d516904b | 2891 | break; |
26234f36 | 2892 | |
420256ef | 2893 | cond_resched(); |
ba76149f | 2894 | |
cd092411 | 2895 | if (unlikely(kthread_should_stop() || try_to_freeze())) |
878aee7d AA |
2896 | break; |
2897 | ||
ba76149f AA |
2898 | spin_lock(&khugepaged_mm_lock); |
2899 | if (!khugepaged_scan.mm_slot) | |
2900 | pass_through_head++; | |
2901 | if (khugepaged_has_work() && | |
2902 | pass_through_head < 2) | |
2903 | progress += khugepaged_scan_mm_slot(pages - progress, | |
d516904b | 2904 | &hpage); |
ba76149f AA |
2905 | else |
2906 | progress = pages; | |
2907 | spin_unlock(&khugepaged_mm_lock); | |
2908 | } | |
ba76149f | 2909 | |
d516904b XG |
2910 | if (!IS_ERR_OR_NULL(hpage)) |
2911 | put_page(hpage); | |
0bbbc0b3 AA |
2912 | } |
2913 | ||
f0508977 DR |
2914 | static bool khugepaged_should_wakeup(void) |
2915 | { | |
2916 | return kthread_should_stop() || | |
2917 | time_after_eq(jiffies, khugepaged_sleep_expire); | |
2918 | } | |
2919 | ||
2017c0bf XG |
2920 | static void khugepaged_wait_work(void) |
2921 | { | |
2017c0bf | 2922 | if (khugepaged_has_work()) { |
f0508977 DR |
2923 | const unsigned long scan_sleep_jiffies = |
2924 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs); | |
2925 | ||
2926 | if (!scan_sleep_jiffies) | |
2017c0bf XG |
2927 | return; |
2928 | ||
f0508977 | 2929 | khugepaged_sleep_expire = jiffies + scan_sleep_jiffies; |
2017c0bf | 2930 | wait_event_freezable_timeout(khugepaged_wait, |
f0508977 DR |
2931 | khugepaged_should_wakeup(), |
2932 | scan_sleep_jiffies); | |
2017c0bf XG |
2933 | return; |
2934 | } | |
2935 | ||
2936 | if (khugepaged_enabled()) | |
2937 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2938 | } | |
2939 | ||
ba76149f AA |
2940 | static int khugepaged(void *none) |
2941 | { | |
2942 | struct mm_slot *mm_slot; | |
2943 | ||
878aee7d | 2944 | set_freezable(); |
8698a745 | 2945 | set_user_nice(current, MAX_NICE); |
ba76149f | 2946 | |
b7231789 XG |
2947 | while (!kthread_should_stop()) { |
2948 | khugepaged_do_scan(); | |
2949 | khugepaged_wait_work(); | |
2950 | } | |
ba76149f AA |
2951 | |
2952 | spin_lock(&khugepaged_mm_lock); | |
2953 | mm_slot = khugepaged_scan.mm_slot; | |
2954 | khugepaged_scan.mm_slot = NULL; | |
2955 | if (mm_slot) | |
2956 | collect_mm_slot(mm_slot); | |
2957 | spin_unlock(&khugepaged_mm_lock); | |
ba76149f AA |
2958 | return 0; |
2959 | } | |
2960 | ||
eef1b3ba KS |
2961 | static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, |
2962 | unsigned long haddr, pmd_t *pmd) | |
2963 | { | |
2964 | struct mm_struct *mm = vma->vm_mm; | |
2965 | pgtable_t pgtable; | |
2966 | pmd_t _pmd; | |
2967 | int i; | |
2968 | ||
2969 | /* leave pmd empty until pte is filled */ | |
2970 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
2971 | ||
2972 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); | |
2973 | pmd_populate(mm, &_pmd, pgtable); | |
2974 | ||
2975 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
2976 | pte_t *pte, entry; | |
2977 | entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); | |
2978 | entry = pte_mkspecial(entry); | |
2979 | pte = pte_offset_map(&_pmd, haddr); | |
2980 | VM_BUG_ON(!pte_none(*pte)); | |
2981 | set_pte_at(mm, haddr, pte, entry); | |
2982 | pte_unmap(pte); | |
2983 | } | |
2984 | smp_wmb(); /* make pte visible before pmd */ | |
2985 | pmd_populate(mm, pmd, pgtable); | |
2986 | put_huge_zero_page(); | |
2987 | } | |
2988 | ||
2989 | static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, | |
ba988280 | 2990 | unsigned long haddr, bool freeze) |
eef1b3ba KS |
2991 | { |
2992 | struct mm_struct *mm = vma->vm_mm; | |
2993 | struct page *page; | |
2994 | pgtable_t pgtable; | |
2995 | pmd_t _pmd; | |
b8d3c4c3 | 2996 | bool young, write, dirty; |
2ac015e2 | 2997 | unsigned long addr; |
eef1b3ba KS |
2998 | int i; |
2999 | ||
3000 | VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); | |
3001 | VM_BUG_ON_VMA(vma->vm_start > haddr, vma); | |
3002 | VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); | |
5c7fb56e | 3003 | VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)); |
eef1b3ba KS |
3004 | |
3005 | count_vm_event(THP_SPLIT_PMD); | |
3006 | ||
3007 | if (vma_is_dax(vma)) { | |
3008 | pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
3009 | if (is_huge_zero_pmd(_pmd)) | |
3010 | put_huge_zero_page(); | |
3011 | return; | |
3012 | } else if (is_huge_zero_pmd(*pmd)) { | |
3013 | return __split_huge_zero_page_pmd(vma, haddr, pmd); | |
3014 | } | |
3015 | ||
3016 | page = pmd_page(*pmd); | |
3017 | VM_BUG_ON_PAGE(!page_count(page), page); | |
fe896d18 | 3018 | page_ref_add(page, HPAGE_PMD_NR - 1); |
eef1b3ba KS |
3019 | write = pmd_write(*pmd); |
3020 | young = pmd_young(*pmd); | |
b8d3c4c3 | 3021 | dirty = pmd_dirty(*pmd); |
eef1b3ba | 3022 | |
c777e2a8 | 3023 | pmdp_huge_split_prepare(vma, haddr, pmd); |
eef1b3ba KS |
3024 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
3025 | pmd_populate(mm, &_pmd, pgtable); | |
3026 | ||
2ac015e2 | 3027 | for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { |
eef1b3ba KS |
3028 | pte_t entry, *pte; |
3029 | /* | |
3030 | * Note that NUMA hinting access restrictions are not | |
3031 | * transferred to avoid any possibility of altering | |
3032 | * permissions across VMAs. | |
3033 | */ | |
ba988280 KS |
3034 | if (freeze) { |
3035 | swp_entry_t swp_entry; | |
3036 | swp_entry = make_migration_entry(page + i, write); | |
3037 | entry = swp_entry_to_pte(swp_entry); | |
3038 | } else { | |
3039 | entry = mk_pte(page + i, vma->vm_page_prot); | |
b8d3c4c3 | 3040 | entry = maybe_mkwrite(entry, vma); |
ba988280 KS |
3041 | if (!write) |
3042 | entry = pte_wrprotect(entry); | |
3043 | if (!young) | |
3044 | entry = pte_mkold(entry); | |
3045 | } | |
b8d3c4c3 MK |
3046 | if (dirty) |
3047 | SetPageDirty(page + i); | |
2ac015e2 | 3048 | pte = pte_offset_map(&_pmd, addr); |
eef1b3ba | 3049 | BUG_ON(!pte_none(*pte)); |
2ac015e2 | 3050 | set_pte_at(mm, addr, pte, entry); |
eef1b3ba KS |
3051 | atomic_inc(&page[i]._mapcount); |
3052 | pte_unmap(pte); | |
3053 | } | |
3054 | ||
3055 | /* | |
3056 | * Set PG_double_map before dropping compound_mapcount to avoid | |
3057 | * false-negative page_mapped(). | |
3058 | */ | |
3059 | if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { | |
3060 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
3061 | atomic_inc(&page[i]._mapcount); | |
3062 | } | |
3063 | ||
3064 | if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { | |
3065 | /* Last compound_mapcount is gone. */ | |
3066 | __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); | |
3067 | if (TestClearPageDoubleMap(page)) { | |
3068 | /* No need in mapcount reference anymore */ | |
3069 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
3070 | atomic_dec(&page[i]._mapcount); | |
3071 | } | |
3072 | } | |
3073 | ||
3074 | smp_wmb(); /* make pte visible before pmd */ | |
e9b61f19 KS |
3075 | /* |
3076 | * Up to this point the pmd is present and huge and userland has the | |
3077 | * whole access to the hugepage during the split (which happens in | |
3078 | * place). If we overwrite the pmd with the not-huge version pointing | |
3079 | * to the pte here (which of course we could if all CPUs were bug | |
3080 | * free), userland could trigger a small page size TLB miss on the | |
3081 | * small sized TLB while the hugepage TLB entry is still established in | |
3082 | * the huge TLB. Some CPU doesn't like that. | |
3083 | * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum | |
3084 | * 383 on page 93. Intel should be safe but is also warns that it's | |
3085 | * only safe if the permission and cache attributes of the two entries | |
3086 | * loaded in the two TLB is identical (which should be the case here). | |
3087 | * But it is generally safer to never allow small and huge TLB entries | |
3088 | * for the same virtual address to be loaded simultaneously. So instead | |
3089 | * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the | |
3090 | * current pmd notpresent (atomically because here the pmd_trans_huge | |
3091 | * and pmd_trans_splitting must remain set at all times on the pmd | |
3092 | * until the split is complete for this pmd), then we flush the SMP TLB | |
3093 | * and finally we write the non-huge version of the pmd entry with | |
3094 | * pmd_populate. | |
3095 | */ | |
3096 | pmdp_invalidate(vma, haddr, pmd); | |
eef1b3ba | 3097 | pmd_populate(mm, pmd, pgtable); |
e9b61f19 KS |
3098 | |
3099 | if (freeze) { | |
2ac015e2 | 3100 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
e9b61f19 KS |
3101 | page_remove_rmap(page + i, false); |
3102 | put_page(page + i); | |
3103 | } | |
3104 | } | |
eef1b3ba KS |
3105 | } |
3106 | ||
3107 | void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, | |
33f4751e | 3108 | unsigned long address, bool freeze, struct page *page) |
eef1b3ba KS |
3109 | { |
3110 | spinlock_t *ptl; | |
3111 | struct mm_struct *mm = vma->vm_mm; | |
3112 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
3113 | ||
3114 | mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE); | |
3115 | ptl = pmd_lock(mm, pmd); | |
33f4751e NH |
3116 | |
3117 | /* | |
3118 | * If caller asks to setup a migration entries, we need a page to check | |
3119 | * pmd against. Otherwise we can end up replacing wrong page. | |
3120 | */ | |
3121 | VM_BUG_ON(freeze && !page); | |
3122 | if (page && page != pmd_page(*pmd)) | |
3123 | goto out; | |
3124 | ||
5c7fb56e | 3125 | if (pmd_trans_huge(*pmd)) { |
33f4751e | 3126 | page = pmd_page(*pmd); |
5c7fb56e | 3127 | if (PageMlocked(page)) |
5f737714 | 3128 | clear_page_mlock(page); |
5c7fb56e | 3129 | } else if (!pmd_devmap(*pmd)) |
e90309c9 | 3130 | goto out; |
fec89c10 | 3131 | __split_huge_pmd_locked(vma, pmd, haddr, freeze); |
e90309c9 | 3132 | out: |
eef1b3ba KS |
3133 | spin_unlock(ptl); |
3134 | mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE); | |
3135 | } | |
3136 | ||
fec89c10 KS |
3137 | void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, |
3138 | bool freeze, struct page *page) | |
94fcc585 | 3139 | { |
f72e7dcd HD |
3140 | pgd_t *pgd; |
3141 | pud_t *pud; | |
94fcc585 AA |
3142 | pmd_t *pmd; |
3143 | ||
78ddc534 | 3144 | pgd = pgd_offset(vma->vm_mm, address); |
f72e7dcd HD |
3145 | if (!pgd_present(*pgd)) |
3146 | return; | |
3147 | ||
3148 | pud = pud_offset(pgd, address); | |
3149 | if (!pud_present(*pud)) | |
3150 | return; | |
3151 | ||
3152 | pmd = pmd_offset(pud, address); | |
fec89c10 | 3153 | |
33f4751e | 3154 | __split_huge_pmd(vma, pmd, address, freeze, page); |
94fcc585 AA |
3155 | } |
3156 | ||
e1b9996b | 3157 | void vma_adjust_trans_huge(struct vm_area_struct *vma, |
94fcc585 AA |
3158 | unsigned long start, |
3159 | unsigned long end, | |
3160 | long adjust_next) | |
3161 | { | |
3162 | /* | |
3163 | * If the new start address isn't hpage aligned and it could | |
3164 | * previously contain an hugepage: check if we need to split | |
3165 | * an huge pmd. | |
3166 | */ | |
3167 | if (start & ~HPAGE_PMD_MASK && | |
3168 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
3169 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
fec89c10 | 3170 | split_huge_pmd_address(vma, start, false, NULL); |
94fcc585 AA |
3171 | |
3172 | /* | |
3173 | * If the new end address isn't hpage aligned and it could | |
3174 | * previously contain an hugepage: check if we need to split | |
3175 | * an huge pmd. | |
3176 | */ | |
3177 | if (end & ~HPAGE_PMD_MASK && | |
3178 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
3179 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
fec89c10 | 3180 | split_huge_pmd_address(vma, end, false, NULL); |
94fcc585 AA |
3181 | |
3182 | /* | |
3183 | * If we're also updating the vma->vm_next->vm_start, if the new | |
3184 | * vm_next->vm_start isn't page aligned and it could previously | |
3185 | * contain an hugepage: check if we need to split an huge pmd. | |
3186 | */ | |
3187 | if (adjust_next > 0) { | |
3188 | struct vm_area_struct *next = vma->vm_next; | |
3189 | unsigned long nstart = next->vm_start; | |
3190 | nstart += adjust_next << PAGE_SHIFT; | |
3191 | if (nstart & ~HPAGE_PMD_MASK && | |
3192 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
3193 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
fec89c10 | 3194 | split_huge_pmd_address(next, nstart, false, NULL); |
94fcc585 AA |
3195 | } |
3196 | } | |
e9b61f19 | 3197 | |
fec89c10 | 3198 | static void freeze_page(struct page *page) |
e9b61f19 | 3199 | { |
fec89c10 KS |
3200 | enum ttu_flags ttu_flags = TTU_MIGRATION | TTU_IGNORE_MLOCK | |
3201 | TTU_IGNORE_ACCESS | TTU_RMAP_LOCKED; | |
3202 | int i, ret; | |
e9b61f19 KS |
3203 | |
3204 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
3205 | ||
fec89c10 KS |
3206 | /* We only need TTU_SPLIT_HUGE_PMD once */ |
3207 | ret = try_to_unmap(page, ttu_flags | TTU_SPLIT_HUGE_PMD); | |
3208 | for (i = 1; !ret && i < HPAGE_PMD_NR; i++) { | |
3209 | /* Cut short if the page is unmapped */ | |
3210 | if (page_count(page) == 1) | |
3211 | return; | |
e9b61f19 | 3212 | |
fec89c10 | 3213 | ret = try_to_unmap(page + i, ttu_flags); |
e9b61f19 | 3214 | } |
fec89c10 | 3215 | VM_BUG_ON(ret); |
e9b61f19 KS |
3216 | } |
3217 | ||
fec89c10 | 3218 | static void unfreeze_page(struct page *page) |
e9b61f19 | 3219 | { |
fec89c10 | 3220 | int i; |
e9b61f19 | 3221 | |
fec89c10 KS |
3222 | for (i = 0; i < HPAGE_PMD_NR; i++) |
3223 | remove_migration_ptes(page + i, page + i, true); | |
e9b61f19 KS |
3224 | } |
3225 | ||
8df651c7 | 3226 | static void __split_huge_page_tail(struct page *head, int tail, |
e9b61f19 KS |
3227 | struct lruvec *lruvec, struct list_head *list) |
3228 | { | |
e9b61f19 KS |
3229 | struct page *page_tail = head + tail; |
3230 | ||
8df651c7 | 3231 | VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); |
fe896d18 | 3232 | VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail); |
e9b61f19 KS |
3233 | |
3234 | /* | |
0139aa7b | 3235 | * tail_page->_refcount is zero and not changing from under us. But |
e9b61f19 | 3236 | * get_page_unless_zero() may be running from under us on the |
8df651c7 | 3237 | * tail_page. If we used atomic_set() below instead of atomic_inc(), we |
e9b61f19 KS |
3238 | * would then run atomic_set() concurrently with |
3239 | * get_page_unless_zero(), and atomic_set() is implemented in C not | |
3240 | * using locked ops. spin_unlock on x86 sometime uses locked ops | |
3241 | * because of PPro errata 66, 92, so unless somebody can guarantee | |
3242 | * atomic_set() here would be safe on all archs (and not only on x86), | |
8df651c7 | 3243 | * it's safer to use atomic_inc(). |
e9b61f19 | 3244 | */ |
fe896d18 | 3245 | page_ref_inc(page_tail); |
e9b61f19 KS |
3246 | |
3247 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; | |
3248 | page_tail->flags |= (head->flags & | |
3249 | ((1L << PG_referenced) | | |
3250 | (1L << PG_swapbacked) | | |
3251 | (1L << PG_mlocked) | | |
3252 | (1L << PG_uptodate) | | |
3253 | (1L << PG_active) | | |
3254 | (1L << PG_locked) | | |
b8d3c4c3 MK |
3255 | (1L << PG_unevictable) | |
3256 | (1L << PG_dirty))); | |
e9b61f19 KS |
3257 | |
3258 | /* | |
3259 | * After clearing PageTail the gup refcount can be released. | |
3260 | * Page flags also must be visible before we make the page non-compound. | |
3261 | */ | |
3262 | smp_wmb(); | |
3263 | ||
3264 | clear_compound_head(page_tail); | |
3265 | ||
3266 | if (page_is_young(head)) | |
3267 | set_page_young(page_tail); | |
3268 | if (page_is_idle(head)) | |
3269 | set_page_idle(page_tail); | |
3270 | ||
3271 | /* ->mapping in first tail page is compound_mapcount */ | |
9a982250 | 3272 | VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, |
e9b61f19 KS |
3273 | page_tail); |
3274 | page_tail->mapping = head->mapping; | |
3275 | ||
3276 | page_tail->index = head->index + tail; | |
3277 | page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); | |
3278 | lru_add_page_tail(head, page_tail, lruvec, list); | |
e9b61f19 KS |
3279 | } |
3280 | ||
3281 | static void __split_huge_page(struct page *page, struct list_head *list) | |
3282 | { | |
3283 | struct page *head = compound_head(page); | |
3284 | struct zone *zone = page_zone(head); | |
3285 | struct lruvec *lruvec; | |
8df651c7 | 3286 | int i; |
e9b61f19 KS |
3287 | |
3288 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
3289 | spin_lock_irq(&zone->lru_lock); | |
3290 | lruvec = mem_cgroup_page_lruvec(head, zone); | |
3291 | ||
3292 | /* complete memcg works before add pages to LRU */ | |
3293 | mem_cgroup_split_huge_fixup(head); | |
3294 | ||
e9b61f19 | 3295 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) |
8df651c7 | 3296 | __split_huge_page_tail(head, i, lruvec, list); |
e9b61f19 KS |
3297 | |
3298 | ClearPageCompound(head); | |
3299 | spin_unlock_irq(&zone->lru_lock); | |
3300 | ||
fec89c10 | 3301 | unfreeze_page(head); |
e9b61f19 KS |
3302 | |
3303 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
3304 | struct page *subpage = head + i; | |
3305 | if (subpage == page) | |
3306 | continue; | |
3307 | unlock_page(subpage); | |
3308 | ||
3309 | /* | |
3310 | * Subpages may be freed if there wasn't any mapping | |
3311 | * like if add_to_swap() is running on a lru page that | |
3312 | * had its mapping zapped. And freeing these pages | |
3313 | * requires taking the lru_lock so we do the put_page | |
3314 | * of the tail pages after the split is complete. | |
3315 | */ | |
3316 | put_page(subpage); | |
3317 | } | |
3318 | } | |
3319 | ||
b20ce5e0 KS |
3320 | int total_mapcount(struct page *page) |
3321 | { | |
3322 | int i, ret; | |
3323 | ||
3324 | VM_BUG_ON_PAGE(PageTail(page), page); | |
3325 | ||
3326 | if (likely(!PageCompound(page))) | |
3327 | return atomic_read(&page->_mapcount) + 1; | |
3328 | ||
3329 | ret = compound_mapcount(page); | |
3330 | if (PageHuge(page)) | |
3331 | return ret; | |
3332 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
3333 | ret += atomic_read(&page[i]._mapcount) + 1; | |
3334 | if (PageDoubleMap(page)) | |
3335 | ret -= HPAGE_PMD_NR; | |
3336 | return ret; | |
3337 | } | |
3338 | ||
6d0a07ed AA |
3339 | /* |
3340 | * This calculates accurately how many mappings a transparent hugepage | |
3341 | * has (unlike page_mapcount() which isn't fully accurate). This full | |
3342 | * accuracy is primarily needed to know if copy-on-write faults can | |
3343 | * reuse the page and change the mapping to read-write instead of | |
3344 | * copying them. At the same time this returns the total_mapcount too. | |
3345 | * | |
3346 | * The function returns the highest mapcount any one of the subpages | |
3347 | * has. If the return value is one, even if different processes are | |
3348 | * mapping different subpages of the transparent hugepage, they can | |
3349 | * all reuse it, because each process is reusing a different subpage. | |
3350 | * | |
3351 | * The total_mapcount is instead counting all virtual mappings of the | |
3352 | * subpages. If the total_mapcount is equal to "one", it tells the | |
3353 | * caller all mappings belong to the same "mm" and in turn the | |
3354 | * anon_vma of the transparent hugepage can become the vma->anon_vma | |
3355 | * local one as no other process may be mapping any of the subpages. | |
3356 | * | |
3357 | * It would be more accurate to replace page_mapcount() with | |
3358 | * page_trans_huge_mapcount(), however we only use | |
3359 | * page_trans_huge_mapcount() in the copy-on-write faults where we | |
3360 | * need full accuracy to avoid breaking page pinning, because | |
3361 | * page_trans_huge_mapcount() is slower than page_mapcount(). | |
3362 | */ | |
3363 | int page_trans_huge_mapcount(struct page *page, int *total_mapcount) | |
3364 | { | |
3365 | int i, ret, _total_mapcount, mapcount; | |
3366 | ||
3367 | /* hugetlbfs shouldn't call it */ | |
3368 | VM_BUG_ON_PAGE(PageHuge(page), page); | |
3369 | ||
3370 | if (likely(!PageTransCompound(page))) { | |
3371 | mapcount = atomic_read(&page->_mapcount) + 1; | |
3372 | if (total_mapcount) | |
3373 | *total_mapcount = mapcount; | |
3374 | return mapcount; | |
3375 | } | |
3376 | ||
3377 | page = compound_head(page); | |
3378 | ||
3379 | _total_mapcount = ret = 0; | |
3380 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
3381 | mapcount = atomic_read(&page[i]._mapcount) + 1; | |
3382 | ret = max(ret, mapcount); | |
3383 | _total_mapcount += mapcount; | |
3384 | } | |
3385 | if (PageDoubleMap(page)) { | |
3386 | ret -= 1; | |
3387 | _total_mapcount -= HPAGE_PMD_NR; | |
3388 | } | |
3389 | mapcount = compound_mapcount(page); | |
3390 | ret += mapcount; | |
3391 | _total_mapcount += mapcount; | |
3392 | if (total_mapcount) | |
3393 | *total_mapcount = _total_mapcount; | |
3394 | return ret; | |
3395 | } | |
3396 | ||
e9b61f19 KS |
3397 | /* |
3398 | * This function splits huge page into normal pages. @page can point to any | |
3399 | * subpage of huge page to split. Split doesn't change the position of @page. | |
3400 | * | |
3401 | * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. | |
3402 | * The huge page must be locked. | |
3403 | * | |
3404 | * If @list is null, tail pages will be added to LRU list, otherwise, to @list. | |
3405 | * | |
3406 | * Both head page and tail pages will inherit mapping, flags, and so on from | |
3407 | * the hugepage. | |
3408 | * | |
3409 | * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if | |
3410 | * they are not mapped. | |
3411 | * | |
3412 | * Returns 0 if the hugepage is split successfully. | |
3413 | * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under | |
3414 | * us. | |
3415 | */ | |
3416 | int split_huge_page_to_list(struct page *page, struct list_head *list) | |
3417 | { | |
3418 | struct page *head = compound_head(page); | |
a3d0a918 | 3419 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); |
e9b61f19 KS |
3420 | struct anon_vma *anon_vma; |
3421 | int count, mapcount, ret; | |
d9654322 | 3422 | bool mlocked; |
0b9b6fff | 3423 | unsigned long flags; |
e9b61f19 KS |
3424 | |
3425 | VM_BUG_ON_PAGE(is_huge_zero_page(page), page); | |
3426 | VM_BUG_ON_PAGE(!PageAnon(page), page); | |
3427 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
3428 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
3429 | VM_BUG_ON_PAGE(!PageCompound(page), page); | |
3430 | ||
3431 | /* | |
3432 | * The caller does not necessarily hold an mmap_sem that would prevent | |
3433 | * the anon_vma disappearing so we first we take a reference to it | |
3434 | * and then lock the anon_vma for write. This is similar to | |
3435 | * page_lock_anon_vma_read except the write lock is taken to serialise | |
3436 | * against parallel split or collapse operations. | |
3437 | */ | |
3438 | anon_vma = page_get_anon_vma(head); | |
3439 | if (!anon_vma) { | |
3440 | ret = -EBUSY; | |
3441 | goto out; | |
3442 | } | |
3443 | anon_vma_lock_write(anon_vma); | |
3444 | ||
3445 | /* | |
3446 | * Racy check if we can split the page, before freeze_page() will | |
3447 | * split PMDs | |
3448 | */ | |
3449 | if (total_mapcount(head) != page_count(head) - 1) { | |
3450 | ret = -EBUSY; | |
3451 | goto out_unlock; | |
3452 | } | |
3453 | ||
d9654322 | 3454 | mlocked = PageMlocked(page); |
fec89c10 | 3455 | freeze_page(head); |
e9b61f19 KS |
3456 | VM_BUG_ON_PAGE(compound_mapcount(head), head); |
3457 | ||
d9654322 KS |
3458 | /* Make sure the page is not on per-CPU pagevec as it takes pin */ |
3459 | if (mlocked) | |
3460 | lru_add_drain(); | |
3461 | ||
0139aa7b | 3462 | /* Prevent deferred_split_scan() touching ->_refcount */ |
a3d0a918 | 3463 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
e9b61f19 KS |
3464 | count = page_count(head); |
3465 | mapcount = total_mapcount(head); | |
bd56086f | 3466 | if (!mapcount && count == 1) { |
9a982250 | 3467 | if (!list_empty(page_deferred_list(head))) { |
a3d0a918 | 3468 | pgdata->split_queue_len--; |
9a982250 KS |
3469 | list_del(page_deferred_list(head)); |
3470 | } | |
a3d0a918 | 3471 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
e9b61f19 KS |
3472 | __split_huge_page(page, list); |
3473 | ret = 0; | |
bd56086f | 3474 | } else if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { |
a3d0a918 | 3475 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
e9b61f19 KS |
3476 | pr_alert("total_mapcount: %u, page_count(): %u\n", |
3477 | mapcount, count); | |
3478 | if (PageTail(page)) | |
3479 | dump_page(head, NULL); | |
bd56086f | 3480 | dump_page(page, "total_mapcount(head) > 0"); |
e9b61f19 KS |
3481 | BUG(); |
3482 | } else { | |
a3d0a918 | 3483 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
fec89c10 | 3484 | unfreeze_page(head); |
e9b61f19 KS |
3485 | ret = -EBUSY; |
3486 | } | |
3487 | ||
3488 | out_unlock: | |
3489 | anon_vma_unlock_write(anon_vma); | |
3490 | put_anon_vma(anon_vma); | |
3491 | out: | |
3492 | count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); | |
3493 | return ret; | |
3494 | } | |
9a982250 KS |
3495 | |
3496 | void free_transhuge_page(struct page *page) | |
3497 | { | |
a3d0a918 | 3498 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); |
9a982250 KS |
3499 | unsigned long flags; |
3500 | ||
a3d0a918 | 3501 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 3502 | if (!list_empty(page_deferred_list(page))) { |
a3d0a918 | 3503 | pgdata->split_queue_len--; |
9a982250 KS |
3504 | list_del(page_deferred_list(page)); |
3505 | } | |
a3d0a918 | 3506 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
3507 | free_compound_page(page); |
3508 | } | |
3509 | ||
3510 | void deferred_split_huge_page(struct page *page) | |
3511 | { | |
a3d0a918 | 3512 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); |
9a982250 KS |
3513 | unsigned long flags; |
3514 | ||
3515 | VM_BUG_ON_PAGE(!PageTransHuge(page), page); | |
3516 | ||
a3d0a918 | 3517 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 3518 | if (list_empty(page_deferred_list(page))) { |
f9719a03 | 3519 | count_vm_event(THP_DEFERRED_SPLIT_PAGE); |
a3d0a918 KS |
3520 | list_add_tail(page_deferred_list(page), &pgdata->split_queue); |
3521 | pgdata->split_queue_len++; | |
9a982250 | 3522 | } |
a3d0a918 | 3523 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
3524 | } |
3525 | ||
3526 | static unsigned long deferred_split_count(struct shrinker *shrink, | |
3527 | struct shrink_control *sc) | |
3528 | { | |
a3d0a918 | 3529 | struct pglist_data *pgdata = NODE_DATA(sc->nid); |
cb8d68ec | 3530 | return ACCESS_ONCE(pgdata->split_queue_len); |
9a982250 KS |
3531 | } |
3532 | ||
3533 | static unsigned long deferred_split_scan(struct shrinker *shrink, | |
3534 | struct shrink_control *sc) | |
3535 | { | |
a3d0a918 | 3536 | struct pglist_data *pgdata = NODE_DATA(sc->nid); |
9a982250 KS |
3537 | unsigned long flags; |
3538 | LIST_HEAD(list), *pos, *next; | |
3539 | struct page *page; | |
3540 | int split = 0; | |
3541 | ||
a3d0a918 | 3542 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 3543 | /* Take pin on all head pages to avoid freeing them under us */ |
ae026204 | 3544 | list_for_each_safe(pos, next, &pgdata->split_queue) { |
9a982250 KS |
3545 | page = list_entry((void *)pos, struct page, mapping); |
3546 | page = compound_head(page); | |
e3ae1953 KS |
3547 | if (get_page_unless_zero(page)) { |
3548 | list_move(page_deferred_list(page), &list); | |
3549 | } else { | |
3550 | /* We lost race with put_compound_page() */ | |
9a982250 | 3551 | list_del_init(page_deferred_list(page)); |
a3d0a918 | 3552 | pgdata->split_queue_len--; |
9a982250 | 3553 | } |
e3ae1953 KS |
3554 | if (!--sc->nr_to_scan) |
3555 | break; | |
9a982250 | 3556 | } |
a3d0a918 | 3557 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
3558 | |
3559 | list_for_each_safe(pos, next, &list) { | |
3560 | page = list_entry((void *)pos, struct page, mapping); | |
3561 | lock_page(page); | |
3562 | /* split_huge_page() removes page from list on success */ | |
3563 | if (!split_huge_page(page)) | |
3564 | split++; | |
3565 | unlock_page(page); | |
3566 | put_page(page); | |
3567 | } | |
3568 | ||
a3d0a918 KS |
3569 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
3570 | list_splice_tail(&list, &pgdata->split_queue); | |
3571 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); | |
9a982250 | 3572 | |
cb8d68ec KS |
3573 | /* |
3574 | * Stop shrinker if we didn't split any page, but the queue is empty. | |
3575 | * This can happen if pages were freed under us. | |
3576 | */ | |
3577 | if (!split && list_empty(&pgdata->split_queue)) | |
3578 | return SHRINK_STOP; | |
3579 | return split; | |
9a982250 KS |
3580 | } |
3581 | ||
3582 | static struct shrinker deferred_split_shrinker = { | |
3583 | .count_objects = deferred_split_count, | |
3584 | .scan_objects = deferred_split_scan, | |
3585 | .seeks = DEFAULT_SEEKS, | |
a3d0a918 | 3586 | .flags = SHRINKER_NUMA_AWARE, |
9a982250 | 3587 | }; |
49071d43 KS |
3588 | |
3589 | #ifdef CONFIG_DEBUG_FS | |
3590 | static int split_huge_pages_set(void *data, u64 val) | |
3591 | { | |
3592 | struct zone *zone; | |
3593 | struct page *page; | |
3594 | unsigned long pfn, max_zone_pfn; | |
3595 | unsigned long total = 0, split = 0; | |
3596 | ||
3597 | if (val != 1) | |
3598 | return -EINVAL; | |
3599 | ||
3600 | for_each_populated_zone(zone) { | |
3601 | max_zone_pfn = zone_end_pfn(zone); | |
3602 | for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { | |
3603 | if (!pfn_valid(pfn)) | |
3604 | continue; | |
3605 | ||
3606 | page = pfn_to_page(pfn); | |
3607 | if (!get_page_unless_zero(page)) | |
3608 | continue; | |
3609 | ||
3610 | if (zone != page_zone(page)) | |
3611 | goto next; | |
3612 | ||
3613 | if (!PageHead(page) || !PageAnon(page) || | |
3614 | PageHuge(page)) | |
3615 | goto next; | |
3616 | ||
3617 | total++; | |
3618 | lock_page(page); | |
3619 | if (!split_huge_page(page)) | |
3620 | split++; | |
3621 | unlock_page(page); | |
3622 | next: | |
3623 | put_page(page); | |
3624 | } | |
3625 | } | |
3626 | ||
145bdaa1 | 3627 | pr_info("%lu of %lu THP split\n", split, total); |
49071d43 KS |
3628 | |
3629 | return 0; | |
3630 | } | |
3631 | DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, | |
3632 | "%llu\n"); | |
3633 | ||
3634 | static int __init split_huge_pages_debugfs(void) | |
3635 | { | |
3636 | void *ret; | |
3637 | ||
145bdaa1 | 3638 | ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL, |
49071d43 KS |
3639 | &split_huge_pages_fops); |
3640 | if (!ret) | |
3641 | pr_warn("Failed to create split_huge_pages in debugfs"); | |
3642 | return 0; | |
3643 | } | |
3644 | late_initcall(split_huge_pages_debugfs); | |
3645 | #endif |