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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 | ||
9a982250 KS |
799 | static inline struct list_head *page_deferred_list(struct page *page) |
800 | { | |
801 | /* | |
802 | * ->lru in the tail pages is occupied by compound_head. | |
803 | * Let's use ->mapping + ->index in the second tail page as list_head. | |
804 | */ | |
805 | return (struct list_head *)&page[2].mapping; | |
806 | } | |
807 | ||
808 | void prep_transhuge_page(struct page *page) | |
809 | { | |
810 | /* | |
811 | * we use page->mapping and page->indexlru in second tail page | |
812 | * as list_head: assuming THP order >= 2 | |
813 | */ | |
9a982250 KS |
814 | |
815 | INIT_LIST_HEAD(page_deferred_list(page)); | |
816 | set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); | |
817 | } | |
818 | ||
bae473a4 KS |
819 | static int __do_huge_pmd_anonymous_page(struct fault_env *fe, struct page *page, |
820 | gfp_t gfp) | |
71e3aac0 | 821 | { |
bae473a4 | 822 | struct vm_area_struct *vma = fe->vma; |
00501b53 | 823 | struct mem_cgroup *memcg; |
71e3aac0 | 824 | pgtable_t pgtable; |
bae473a4 | 825 | unsigned long haddr = fe->address & HPAGE_PMD_MASK; |
71e3aac0 | 826 | |
309381fe | 827 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
00501b53 | 828 | |
bae473a4 | 829 | if (mem_cgroup_try_charge(page, vma->vm_mm, gfp, &memcg, true)) { |
6b251fc9 AA |
830 | put_page(page); |
831 | count_vm_event(THP_FAULT_FALLBACK); | |
832 | return VM_FAULT_FALLBACK; | |
833 | } | |
00501b53 | 834 | |
bae473a4 | 835 | pgtable = pte_alloc_one(vma->vm_mm, haddr); |
00501b53 | 836 | if (unlikely(!pgtable)) { |
f627c2f5 | 837 | mem_cgroup_cancel_charge(page, memcg, true); |
6b251fc9 | 838 | put_page(page); |
71e3aac0 | 839 | return VM_FAULT_OOM; |
00501b53 | 840 | } |
71e3aac0 AA |
841 | |
842 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
52f37629 MK |
843 | /* |
844 | * The memory barrier inside __SetPageUptodate makes sure that | |
845 | * clear_huge_page writes become visible before the set_pmd_at() | |
846 | * write. | |
847 | */ | |
71e3aac0 AA |
848 | __SetPageUptodate(page); |
849 | ||
bae473a4 KS |
850 | fe->ptl = pmd_lock(vma->vm_mm, fe->pmd); |
851 | if (unlikely(!pmd_none(*fe->pmd))) { | |
852 | spin_unlock(fe->ptl); | |
f627c2f5 | 853 | mem_cgroup_cancel_charge(page, memcg, true); |
71e3aac0 | 854 | put_page(page); |
bae473a4 | 855 | pte_free(vma->vm_mm, pgtable); |
71e3aac0 AA |
856 | } else { |
857 | pmd_t entry; | |
6b251fc9 AA |
858 | |
859 | /* Deliver the page fault to userland */ | |
860 | if (userfaultfd_missing(vma)) { | |
861 | int ret; | |
862 | ||
bae473a4 | 863 | spin_unlock(fe->ptl); |
f627c2f5 | 864 | mem_cgroup_cancel_charge(page, memcg, true); |
6b251fc9 | 865 | put_page(page); |
bae473a4 KS |
866 | pte_free(vma->vm_mm, pgtable); |
867 | ret = handle_userfault(fe, VM_UFFD_MISSING); | |
6b251fc9 AA |
868 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); |
869 | return ret; | |
870 | } | |
871 | ||
3122359a KS |
872 | entry = mk_huge_pmd(page, vma->vm_page_prot); |
873 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
d281ee61 | 874 | page_add_new_anon_rmap(page, vma, haddr, true); |
f627c2f5 | 875 | mem_cgroup_commit_charge(page, memcg, false, true); |
00501b53 | 876 | lru_cache_add_active_or_unevictable(page, vma); |
bae473a4 KS |
877 | pgtable_trans_huge_deposit(vma->vm_mm, fe->pmd, pgtable); |
878 | set_pmd_at(vma->vm_mm, haddr, fe->pmd, entry); | |
879 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
880 | atomic_long_inc(&vma->vm_mm->nr_ptes); | |
881 | spin_unlock(fe->ptl); | |
6b251fc9 | 882 | count_vm_event(THP_FAULT_ALLOC); |
71e3aac0 AA |
883 | } |
884 | ||
aa2e878e | 885 | return 0; |
71e3aac0 AA |
886 | } |
887 | ||
444eb2a4 MG |
888 | /* |
889 | * If THP is set to always then directly reclaim/compact as necessary | |
890 | * If set to defer then do no reclaim and defer to khugepaged | |
891 | * If set to madvise and the VMA is flagged then directly reclaim/compact | |
892 | */ | |
893 | static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma) | |
894 | { | |
895 | gfp_t reclaim_flags = 0; | |
896 | ||
897 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags) && | |
898 | (vma->vm_flags & VM_HUGEPAGE)) | |
899 | reclaim_flags = __GFP_DIRECT_RECLAIM; | |
900 | else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) | |
901 | reclaim_flags = __GFP_KSWAPD_RECLAIM; | |
902 | else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) | |
903 | reclaim_flags = __GFP_DIRECT_RECLAIM; | |
904 | ||
905 | return GFP_TRANSHUGE | reclaim_flags; | |
906 | } | |
907 | ||
908 | /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */ | |
909 | static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void) | |
0bbbc0b3 | 910 | { |
444eb2a4 | 911 | return GFP_TRANSHUGE | (khugepaged_defrag() ? __GFP_DIRECT_RECLAIM : 0); |
0bbbc0b3 AA |
912 | } |
913 | ||
c4088ebd | 914 | /* Caller must hold page table lock. */ |
d295e341 | 915 | static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, |
97ae1749 | 916 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, |
5918d10a | 917 | struct page *zero_page) |
fc9fe822 KS |
918 | { |
919 | pmd_t entry; | |
7c414164 AM |
920 | if (!pmd_none(*pmd)) |
921 | return false; | |
5918d10a | 922 | entry = mk_pmd(zero_page, vma->vm_page_prot); |
fc9fe822 | 923 | entry = pmd_mkhuge(entry); |
12c9d70b MW |
924 | if (pgtable) |
925 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
fc9fe822 | 926 | set_pmd_at(mm, haddr, pmd, entry); |
e1f56c89 | 927 | atomic_long_inc(&mm->nr_ptes); |
7c414164 | 928 | return true; |
fc9fe822 KS |
929 | } |
930 | ||
bae473a4 | 931 | int do_huge_pmd_anonymous_page(struct fault_env *fe) |
71e3aac0 | 932 | { |
bae473a4 | 933 | struct vm_area_struct *vma = fe->vma; |
077fcf11 | 934 | gfp_t gfp; |
71e3aac0 | 935 | struct page *page; |
bae473a4 | 936 | unsigned long haddr = fe->address & HPAGE_PMD_MASK; |
71e3aac0 | 937 | |
128ec037 | 938 | if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) |
c0292554 | 939 | return VM_FAULT_FALLBACK; |
128ec037 KS |
940 | if (unlikely(anon_vma_prepare(vma))) |
941 | return VM_FAULT_OOM; | |
6d50e60c | 942 | if (unlikely(khugepaged_enter(vma, vma->vm_flags))) |
128ec037 | 943 | return VM_FAULT_OOM; |
bae473a4 KS |
944 | if (!(fe->flags & FAULT_FLAG_WRITE) && |
945 | !mm_forbids_zeropage(vma->vm_mm) && | |
128ec037 KS |
946 | transparent_hugepage_use_zero_page()) { |
947 | pgtable_t pgtable; | |
948 | struct page *zero_page; | |
949 | bool set; | |
6b251fc9 | 950 | int ret; |
bae473a4 | 951 | pgtable = pte_alloc_one(vma->vm_mm, haddr); |
128ec037 | 952 | if (unlikely(!pgtable)) |
ba76149f | 953 | return VM_FAULT_OOM; |
128ec037 KS |
954 | zero_page = get_huge_zero_page(); |
955 | if (unlikely(!zero_page)) { | |
bae473a4 | 956 | pte_free(vma->vm_mm, pgtable); |
81ab4201 | 957 | count_vm_event(THP_FAULT_FALLBACK); |
c0292554 | 958 | return VM_FAULT_FALLBACK; |
b9bbfbe3 | 959 | } |
bae473a4 | 960 | fe->ptl = pmd_lock(vma->vm_mm, fe->pmd); |
6b251fc9 AA |
961 | ret = 0; |
962 | set = false; | |
bae473a4 | 963 | if (pmd_none(*fe->pmd)) { |
6b251fc9 | 964 | if (userfaultfd_missing(vma)) { |
bae473a4 KS |
965 | spin_unlock(fe->ptl); |
966 | ret = handle_userfault(fe, VM_UFFD_MISSING); | |
6b251fc9 AA |
967 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); |
968 | } else { | |
bae473a4 KS |
969 | set_huge_zero_page(pgtable, vma->vm_mm, vma, |
970 | haddr, fe->pmd, zero_page); | |
971 | spin_unlock(fe->ptl); | |
6b251fc9 AA |
972 | set = true; |
973 | } | |
974 | } else | |
bae473a4 | 975 | spin_unlock(fe->ptl); |
128ec037 | 976 | if (!set) { |
bae473a4 | 977 | pte_free(vma->vm_mm, pgtable); |
128ec037 | 978 | put_huge_zero_page(); |
edad9d2c | 979 | } |
6b251fc9 | 980 | return ret; |
71e3aac0 | 981 | } |
444eb2a4 | 982 | gfp = alloc_hugepage_direct_gfpmask(vma); |
077fcf11 | 983 | page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); |
128ec037 KS |
984 | if (unlikely(!page)) { |
985 | count_vm_event(THP_FAULT_FALLBACK); | |
c0292554 | 986 | return VM_FAULT_FALLBACK; |
128ec037 | 987 | } |
9a982250 | 988 | prep_transhuge_page(page); |
bae473a4 | 989 | return __do_huge_pmd_anonymous_page(fe, page, gfp); |
71e3aac0 AA |
990 | } |
991 | ||
ae18d6dc | 992 | static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, |
f25748e3 | 993 | pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write) |
5cad465d MW |
994 | { |
995 | struct mm_struct *mm = vma->vm_mm; | |
996 | pmd_t entry; | |
997 | spinlock_t *ptl; | |
998 | ||
999 | ptl = pmd_lock(mm, pmd); | |
f25748e3 DW |
1000 | entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); |
1001 | if (pfn_t_devmap(pfn)) | |
1002 | entry = pmd_mkdevmap(entry); | |
01871e59 RZ |
1003 | if (write) { |
1004 | entry = pmd_mkyoung(pmd_mkdirty(entry)); | |
1005 | entry = maybe_pmd_mkwrite(entry, vma); | |
5cad465d | 1006 | } |
01871e59 RZ |
1007 | set_pmd_at(mm, addr, pmd, entry); |
1008 | update_mmu_cache_pmd(vma, addr, pmd); | |
5cad465d | 1009 | spin_unlock(ptl); |
5cad465d MW |
1010 | } |
1011 | ||
1012 | int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, | |
f25748e3 | 1013 | pmd_t *pmd, pfn_t pfn, bool write) |
5cad465d MW |
1014 | { |
1015 | pgprot_t pgprot = vma->vm_page_prot; | |
1016 | /* | |
1017 | * If we had pmd_special, we could avoid all these restrictions, | |
1018 | * but we need to be consistent with PTEs and architectures that | |
1019 | * can't support a 'special' bit. | |
1020 | */ | |
1021 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); | |
1022 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == | |
1023 | (VM_PFNMAP|VM_MIXEDMAP)); | |
1024 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); | |
f25748e3 | 1025 | BUG_ON(!pfn_t_devmap(pfn)); |
5cad465d MW |
1026 | |
1027 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
1028 | return VM_FAULT_SIGBUS; | |
1029 | if (track_pfn_insert(vma, &pgprot, pfn)) | |
1030 | return VM_FAULT_SIGBUS; | |
ae18d6dc MW |
1031 | insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write); |
1032 | return VM_FAULT_NOPAGE; | |
5cad465d | 1033 | } |
dee41079 | 1034 | EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); |
5cad465d | 1035 | |
3565fce3 DW |
1036 | static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, |
1037 | pmd_t *pmd) | |
1038 | { | |
1039 | pmd_t _pmd; | |
1040 | ||
1041 | /* | |
1042 | * We should set the dirty bit only for FOLL_WRITE but for now | |
1043 | * the dirty bit in the pmd is meaningless. And if the dirty | |
1044 | * bit will become meaningful and we'll only set it with | |
1045 | * FOLL_WRITE, an atomic set_bit will be required on the pmd to | |
1046 | * set the young bit, instead of the current set_pmd_at. | |
1047 | */ | |
1048 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
1049 | if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, | |
1050 | pmd, _pmd, 1)) | |
1051 | update_mmu_cache_pmd(vma, addr, pmd); | |
1052 | } | |
1053 | ||
1054 | struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, | |
1055 | pmd_t *pmd, int flags) | |
1056 | { | |
1057 | unsigned long pfn = pmd_pfn(*pmd); | |
1058 | struct mm_struct *mm = vma->vm_mm; | |
1059 | struct dev_pagemap *pgmap; | |
1060 | struct page *page; | |
1061 | ||
1062 | assert_spin_locked(pmd_lockptr(mm, pmd)); | |
1063 | ||
1064 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1065 | return NULL; | |
1066 | ||
1067 | if (pmd_present(*pmd) && pmd_devmap(*pmd)) | |
1068 | /* pass */; | |
1069 | else | |
1070 | return NULL; | |
1071 | ||
1072 | if (flags & FOLL_TOUCH) | |
1073 | touch_pmd(vma, addr, pmd); | |
1074 | ||
1075 | /* | |
1076 | * device mapped pages can only be returned if the | |
1077 | * caller will manage the page reference count. | |
1078 | */ | |
1079 | if (!(flags & FOLL_GET)) | |
1080 | return ERR_PTR(-EEXIST); | |
1081 | ||
1082 | pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; | |
1083 | pgmap = get_dev_pagemap(pfn, NULL); | |
1084 | if (!pgmap) | |
1085 | return ERR_PTR(-EFAULT); | |
1086 | page = pfn_to_page(pfn); | |
1087 | get_page(page); | |
1088 | put_dev_pagemap(pgmap); | |
1089 | ||
1090 | return page; | |
1091 | } | |
1092 | ||
71e3aac0 AA |
1093 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
1094 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
1095 | struct vm_area_struct *vma) | |
1096 | { | |
c4088ebd | 1097 | spinlock_t *dst_ptl, *src_ptl; |
71e3aac0 AA |
1098 | struct page *src_page; |
1099 | pmd_t pmd; | |
12c9d70b | 1100 | pgtable_t pgtable = NULL; |
71e3aac0 AA |
1101 | int ret; |
1102 | ||
12c9d70b MW |
1103 | if (!vma_is_dax(vma)) { |
1104 | ret = -ENOMEM; | |
1105 | pgtable = pte_alloc_one(dst_mm, addr); | |
1106 | if (unlikely(!pgtable)) | |
1107 | goto out; | |
1108 | } | |
71e3aac0 | 1109 | |
c4088ebd KS |
1110 | dst_ptl = pmd_lock(dst_mm, dst_pmd); |
1111 | src_ptl = pmd_lockptr(src_mm, src_pmd); | |
1112 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
71e3aac0 AA |
1113 | |
1114 | ret = -EAGAIN; | |
1115 | pmd = *src_pmd; | |
5c7fb56e | 1116 | if (unlikely(!pmd_trans_huge(pmd) && !pmd_devmap(pmd))) { |
71e3aac0 AA |
1117 | pte_free(dst_mm, pgtable); |
1118 | goto out_unlock; | |
1119 | } | |
fc9fe822 | 1120 | /* |
c4088ebd | 1121 | * When page table lock is held, the huge zero pmd should not be |
fc9fe822 KS |
1122 | * under splitting since we don't split the page itself, only pmd to |
1123 | * a page table. | |
1124 | */ | |
1125 | if (is_huge_zero_pmd(pmd)) { | |
5918d10a | 1126 | struct page *zero_page; |
97ae1749 KS |
1127 | /* |
1128 | * get_huge_zero_page() will never allocate a new page here, | |
1129 | * since we already have a zero page to copy. It just takes a | |
1130 | * reference. | |
1131 | */ | |
5918d10a | 1132 | zero_page = get_huge_zero_page(); |
6b251fc9 | 1133 | set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, |
5918d10a | 1134 | zero_page); |
fc9fe822 KS |
1135 | ret = 0; |
1136 | goto out_unlock; | |
1137 | } | |
de466bd6 | 1138 | |
12c9d70b | 1139 | if (!vma_is_dax(vma)) { |
5c7fb56e DW |
1140 | /* thp accounting separate from pmd_devmap accounting */ |
1141 | src_page = pmd_page(pmd); | |
1142 | VM_BUG_ON_PAGE(!PageHead(src_page), src_page); | |
1143 | get_page(src_page); | |
1144 | page_dup_rmap(src_page, true); | |
1145 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
1146 | atomic_long_inc(&dst_mm->nr_ptes); | |
1147 | pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); | |
1148 | } | |
71e3aac0 AA |
1149 | |
1150 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
1151 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
1152 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
71e3aac0 AA |
1153 | |
1154 | ret = 0; | |
1155 | out_unlock: | |
c4088ebd KS |
1156 | spin_unlock(src_ptl); |
1157 | spin_unlock(dst_ptl); | |
71e3aac0 AA |
1158 | out: |
1159 | return ret; | |
1160 | } | |
1161 | ||
bae473a4 | 1162 | void huge_pmd_set_accessed(struct fault_env *fe, pmd_t orig_pmd) |
a1dd450b WD |
1163 | { |
1164 | pmd_t entry; | |
1165 | unsigned long haddr; | |
1166 | ||
bae473a4 KS |
1167 | fe->ptl = pmd_lock(fe->vma->vm_mm, fe->pmd); |
1168 | if (unlikely(!pmd_same(*fe->pmd, orig_pmd))) | |
a1dd450b WD |
1169 | goto unlock; |
1170 | ||
1171 | entry = pmd_mkyoung(orig_pmd); | |
bae473a4 KS |
1172 | haddr = fe->address & HPAGE_PMD_MASK; |
1173 | if (pmdp_set_access_flags(fe->vma, haddr, fe->pmd, entry, | |
1174 | fe->flags & FAULT_FLAG_WRITE)) | |
1175 | update_mmu_cache_pmd(fe->vma, fe->address, fe->pmd); | |
a1dd450b WD |
1176 | |
1177 | unlock: | |
bae473a4 | 1178 | spin_unlock(fe->ptl); |
a1dd450b WD |
1179 | } |
1180 | ||
bae473a4 KS |
1181 | static int do_huge_pmd_wp_page_fallback(struct fault_env *fe, pmd_t orig_pmd, |
1182 | struct page *page) | |
71e3aac0 | 1183 | { |
bae473a4 KS |
1184 | struct vm_area_struct *vma = fe->vma; |
1185 | unsigned long haddr = fe->address & HPAGE_PMD_MASK; | |
00501b53 | 1186 | struct mem_cgroup *memcg; |
71e3aac0 AA |
1187 | pgtable_t pgtable; |
1188 | pmd_t _pmd; | |
1189 | int ret = 0, i; | |
1190 | struct page **pages; | |
2ec74c3e SG |
1191 | unsigned long mmun_start; /* For mmu_notifiers */ |
1192 | unsigned long mmun_end; /* For mmu_notifiers */ | |
71e3aac0 AA |
1193 | |
1194 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
1195 | GFP_KERNEL); | |
1196 | if (unlikely(!pages)) { | |
1197 | ret |= VM_FAULT_OOM; | |
1198 | goto out; | |
1199 | } | |
1200 | ||
1201 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
cc5d462f | 1202 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE | |
bae473a4 KS |
1203 | __GFP_OTHER_NODE, vma, |
1204 | fe->address, page_to_nid(page)); | |
b9bbfbe3 | 1205 | if (unlikely(!pages[i] || |
bae473a4 KS |
1206 | mem_cgroup_try_charge(pages[i], vma->vm_mm, |
1207 | GFP_KERNEL, &memcg, false))) { | |
b9bbfbe3 | 1208 | if (pages[i]) |
71e3aac0 | 1209 | put_page(pages[i]); |
b9bbfbe3 | 1210 | while (--i >= 0) { |
00501b53 JW |
1211 | memcg = (void *)page_private(pages[i]); |
1212 | set_page_private(pages[i], 0); | |
f627c2f5 KS |
1213 | mem_cgroup_cancel_charge(pages[i], memcg, |
1214 | false); | |
b9bbfbe3 AA |
1215 | put_page(pages[i]); |
1216 | } | |
71e3aac0 AA |
1217 | kfree(pages); |
1218 | ret |= VM_FAULT_OOM; | |
1219 | goto out; | |
1220 | } | |
00501b53 | 1221 | set_page_private(pages[i], (unsigned long)memcg); |
71e3aac0 AA |
1222 | } |
1223 | ||
1224 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1225 | copy_user_highpage(pages[i], page + i, | |
0089e485 | 1226 | haddr + PAGE_SIZE * i, vma); |
71e3aac0 AA |
1227 | __SetPageUptodate(pages[i]); |
1228 | cond_resched(); | |
1229 | } | |
1230 | ||
2ec74c3e SG |
1231 | mmun_start = haddr; |
1232 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
bae473a4 | 1233 | mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end); |
2ec74c3e | 1234 | |
bae473a4 KS |
1235 | fe->ptl = pmd_lock(vma->vm_mm, fe->pmd); |
1236 | if (unlikely(!pmd_same(*fe->pmd, orig_pmd))) | |
71e3aac0 | 1237 | goto out_free_pages; |
309381fe | 1238 | VM_BUG_ON_PAGE(!PageHead(page), page); |
71e3aac0 | 1239 | |
bae473a4 | 1240 | pmdp_huge_clear_flush_notify(vma, haddr, fe->pmd); |
71e3aac0 AA |
1241 | /* leave pmd empty until pte is filled */ |
1242 | ||
bae473a4 KS |
1243 | pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, fe->pmd); |
1244 | pmd_populate(vma->vm_mm, &_pmd, pgtable); | |
71e3aac0 AA |
1245 | |
1246 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
bae473a4 | 1247 | pte_t entry; |
71e3aac0 AA |
1248 | entry = mk_pte(pages[i], vma->vm_page_prot); |
1249 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
00501b53 JW |
1250 | memcg = (void *)page_private(pages[i]); |
1251 | set_page_private(pages[i], 0); | |
bae473a4 | 1252 | page_add_new_anon_rmap(pages[i], fe->vma, haddr, false); |
f627c2f5 | 1253 | mem_cgroup_commit_charge(pages[i], memcg, false, false); |
00501b53 | 1254 | lru_cache_add_active_or_unevictable(pages[i], vma); |
bae473a4 KS |
1255 | fe->pte = pte_offset_map(&_pmd, haddr); |
1256 | VM_BUG_ON(!pte_none(*fe->pte)); | |
1257 | set_pte_at(vma->vm_mm, haddr, fe->pte, entry); | |
1258 | pte_unmap(fe->pte); | |
71e3aac0 AA |
1259 | } |
1260 | kfree(pages); | |
1261 | ||
71e3aac0 | 1262 | smp_wmb(); /* make pte visible before pmd */ |
bae473a4 | 1263 | pmd_populate(vma->vm_mm, fe->pmd, pgtable); |
d281ee61 | 1264 | page_remove_rmap(page, true); |
bae473a4 | 1265 | spin_unlock(fe->ptl); |
71e3aac0 | 1266 | |
bae473a4 | 1267 | mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end); |
2ec74c3e | 1268 | |
71e3aac0 AA |
1269 | ret |= VM_FAULT_WRITE; |
1270 | put_page(page); | |
1271 | ||
1272 | out: | |
1273 | return ret; | |
1274 | ||
1275 | out_free_pages: | |
bae473a4 KS |
1276 | spin_unlock(fe->ptl); |
1277 | mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end); | |
b9bbfbe3 | 1278 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
00501b53 JW |
1279 | memcg = (void *)page_private(pages[i]); |
1280 | set_page_private(pages[i], 0); | |
f627c2f5 | 1281 | mem_cgroup_cancel_charge(pages[i], memcg, false); |
71e3aac0 | 1282 | put_page(pages[i]); |
b9bbfbe3 | 1283 | } |
71e3aac0 AA |
1284 | kfree(pages); |
1285 | goto out; | |
1286 | } | |
1287 | ||
bae473a4 | 1288 | int do_huge_pmd_wp_page(struct fault_env *fe, pmd_t orig_pmd) |
71e3aac0 | 1289 | { |
bae473a4 | 1290 | struct vm_area_struct *vma = fe->vma; |
93b4796d | 1291 | struct page *page = NULL, *new_page; |
00501b53 | 1292 | struct mem_cgroup *memcg; |
bae473a4 | 1293 | unsigned long haddr = fe->address & HPAGE_PMD_MASK; |
2ec74c3e SG |
1294 | unsigned long mmun_start; /* For mmu_notifiers */ |
1295 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 1296 | gfp_t huge_gfp; /* for allocation and charge */ |
bae473a4 | 1297 | int ret = 0; |
71e3aac0 | 1298 | |
bae473a4 | 1299 | fe->ptl = pmd_lockptr(vma->vm_mm, fe->pmd); |
81d1b09c | 1300 | VM_BUG_ON_VMA(!vma->anon_vma, vma); |
93b4796d KS |
1301 | if (is_huge_zero_pmd(orig_pmd)) |
1302 | goto alloc; | |
bae473a4 KS |
1303 | spin_lock(fe->ptl); |
1304 | if (unlikely(!pmd_same(*fe->pmd, orig_pmd))) | |
71e3aac0 AA |
1305 | goto out_unlock; |
1306 | ||
1307 | page = pmd_page(orig_pmd); | |
309381fe | 1308 | VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); |
1f25fe20 KS |
1309 | /* |
1310 | * We can only reuse the page if nobody else maps the huge page or it's | |
6d0a07ed | 1311 | * part. |
1f25fe20 | 1312 | */ |
6d0a07ed | 1313 | if (page_trans_huge_mapcount(page, NULL) == 1) { |
71e3aac0 AA |
1314 | pmd_t entry; |
1315 | entry = pmd_mkyoung(orig_pmd); | |
1316 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
bae473a4 KS |
1317 | if (pmdp_set_access_flags(vma, haddr, fe->pmd, entry, 1)) |
1318 | update_mmu_cache_pmd(vma, fe->address, fe->pmd); | |
71e3aac0 AA |
1319 | ret |= VM_FAULT_WRITE; |
1320 | goto out_unlock; | |
1321 | } | |
ddc58f27 | 1322 | get_page(page); |
bae473a4 | 1323 | spin_unlock(fe->ptl); |
93b4796d | 1324 | alloc: |
71e3aac0 | 1325 | if (transparent_hugepage_enabled(vma) && |
077fcf11 | 1326 | !transparent_hugepage_debug_cow()) { |
444eb2a4 | 1327 | huge_gfp = alloc_hugepage_direct_gfpmask(vma); |
3b363692 | 1328 | new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); |
077fcf11 | 1329 | } else |
71e3aac0 AA |
1330 | new_page = NULL; |
1331 | ||
9a982250 KS |
1332 | if (likely(new_page)) { |
1333 | prep_transhuge_page(new_page); | |
1334 | } else { | |
eecc1e42 | 1335 | if (!page) { |
bae473a4 | 1336 | split_huge_pmd(vma, fe->pmd, fe->address); |
e9b71ca9 | 1337 | ret |= VM_FAULT_FALLBACK; |
93b4796d | 1338 | } else { |
bae473a4 | 1339 | ret = do_huge_pmd_wp_page_fallback(fe, orig_pmd, page); |
9845cbbd | 1340 | if (ret & VM_FAULT_OOM) { |
bae473a4 | 1341 | split_huge_pmd(vma, fe->pmd, fe->address); |
9845cbbd KS |
1342 | ret |= VM_FAULT_FALLBACK; |
1343 | } | |
ddc58f27 | 1344 | put_page(page); |
93b4796d | 1345 | } |
17766dde | 1346 | count_vm_event(THP_FAULT_FALLBACK); |
71e3aac0 AA |
1347 | goto out; |
1348 | } | |
1349 | ||
bae473a4 KS |
1350 | if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm, |
1351 | huge_gfp, &memcg, true))) { | |
b9bbfbe3 | 1352 | put_page(new_page); |
bae473a4 KS |
1353 | split_huge_pmd(vma, fe->pmd, fe->address); |
1354 | if (page) | |
ddc58f27 | 1355 | put_page(page); |
9845cbbd | 1356 | ret |= VM_FAULT_FALLBACK; |
17766dde | 1357 | count_vm_event(THP_FAULT_FALLBACK); |
b9bbfbe3 AA |
1358 | goto out; |
1359 | } | |
1360 | ||
17766dde DR |
1361 | count_vm_event(THP_FAULT_ALLOC); |
1362 | ||
eecc1e42 | 1363 | if (!page) |
93b4796d KS |
1364 | clear_huge_page(new_page, haddr, HPAGE_PMD_NR); |
1365 | else | |
1366 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); | |
71e3aac0 AA |
1367 | __SetPageUptodate(new_page); |
1368 | ||
2ec74c3e SG |
1369 | mmun_start = haddr; |
1370 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
bae473a4 | 1371 | mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end); |
2ec74c3e | 1372 | |
bae473a4 | 1373 | spin_lock(fe->ptl); |
93b4796d | 1374 | if (page) |
ddc58f27 | 1375 | put_page(page); |
bae473a4 KS |
1376 | if (unlikely(!pmd_same(*fe->pmd, orig_pmd))) { |
1377 | spin_unlock(fe->ptl); | |
f627c2f5 | 1378 | mem_cgroup_cancel_charge(new_page, memcg, true); |
71e3aac0 | 1379 | put_page(new_page); |
2ec74c3e | 1380 | goto out_mn; |
b9bbfbe3 | 1381 | } else { |
71e3aac0 | 1382 | pmd_t entry; |
3122359a KS |
1383 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); |
1384 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
bae473a4 | 1385 | pmdp_huge_clear_flush_notify(vma, haddr, fe->pmd); |
d281ee61 | 1386 | page_add_new_anon_rmap(new_page, vma, haddr, true); |
f627c2f5 | 1387 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
00501b53 | 1388 | lru_cache_add_active_or_unevictable(new_page, vma); |
bae473a4 KS |
1389 | set_pmd_at(vma->vm_mm, haddr, fe->pmd, entry); |
1390 | update_mmu_cache_pmd(vma, fe->address, fe->pmd); | |
eecc1e42 | 1391 | if (!page) { |
bae473a4 | 1392 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); |
97ae1749 KS |
1393 | put_huge_zero_page(); |
1394 | } else { | |
309381fe | 1395 | VM_BUG_ON_PAGE(!PageHead(page), page); |
d281ee61 | 1396 | page_remove_rmap(page, true); |
93b4796d KS |
1397 | put_page(page); |
1398 | } | |
71e3aac0 AA |
1399 | ret |= VM_FAULT_WRITE; |
1400 | } | |
bae473a4 | 1401 | spin_unlock(fe->ptl); |
2ec74c3e | 1402 | out_mn: |
bae473a4 | 1403 | mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end); |
71e3aac0 AA |
1404 | out: |
1405 | return ret; | |
2ec74c3e | 1406 | out_unlock: |
bae473a4 | 1407 | spin_unlock(fe->ptl); |
2ec74c3e | 1408 | return ret; |
71e3aac0 AA |
1409 | } |
1410 | ||
b676b293 | 1411 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, |
71e3aac0 AA |
1412 | unsigned long addr, |
1413 | pmd_t *pmd, | |
1414 | unsigned int flags) | |
1415 | { | |
b676b293 | 1416 | struct mm_struct *mm = vma->vm_mm; |
71e3aac0 AA |
1417 | struct page *page = NULL; |
1418 | ||
c4088ebd | 1419 | assert_spin_locked(pmd_lockptr(mm, pmd)); |
71e3aac0 AA |
1420 | |
1421 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1422 | goto out; | |
1423 | ||
85facf25 KS |
1424 | /* Avoid dumping huge zero page */ |
1425 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) | |
1426 | return ERR_PTR(-EFAULT); | |
1427 | ||
2b4847e7 | 1428 | /* Full NUMA hinting faults to serialise migration in fault paths */ |
8a0516ed | 1429 | if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) |
2b4847e7 MG |
1430 | goto out; |
1431 | ||
71e3aac0 | 1432 | page = pmd_page(*pmd); |
309381fe | 1433 | VM_BUG_ON_PAGE(!PageHead(page), page); |
3565fce3 DW |
1434 | if (flags & FOLL_TOUCH) |
1435 | touch_pmd(vma, addr, pmd); | |
de60f5f1 | 1436 | if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { |
e90309c9 KS |
1437 | /* |
1438 | * We don't mlock() pte-mapped THPs. This way we can avoid | |
1439 | * leaking mlocked pages into non-VM_LOCKED VMAs. | |
1440 | * | |
1441 | * In most cases the pmd is the only mapping of the page as we | |
1442 | * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for | |
1443 | * writable private mappings in populate_vma_page_range(). | |
1444 | * | |
1445 | * The only scenario when we have the page shared here is if we | |
1446 | * mlocking read-only mapping shared over fork(). We skip | |
1447 | * mlocking such pages. | |
1448 | */ | |
1449 | if (compound_mapcount(page) == 1 && !PageDoubleMap(page) && | |
1450 | page->mapping && trylock_page(page)) { | |
b676b293 DR |
1451 | lru_add_drain(); |
1452 | if (page->mapping) | |
1453 | mlock_vma_page(page); | |
1454 | unlock_page(page); | |
1455 | } | |
1456 | } | |
71e3aac0 | 1457 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
309381fe | 1458 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
71e3aac0 | 1459 | if (flags & FOLL_GET) |
ddc58f27 | 1460 | get_page(page); |
71e3aac0 AA |
1461 | |
1462 | out: | |
1463 | return page; | |
1464 | } | |
1465 | ||
d10e63f2 | 1466 | /* NUMA hinting page fault entry point for trans huge pmds */ |
bae473a4 | 1467 | int do_huge_pmd_numa_page(struct fault_env *fe, pmd_t pmd) |
d10e63f2 | 1468 | { |
bae473a4 | 1469 | struct vm_area_struct *vma = fe->vma; |
b8916634 | 1470 | struct anon_vma *anon_vma = NULL; |
b32967ff | 1471 | struct page *page; |
bae473a4 | 1472 | unsigned long haddr = fe->address & HPAGE_PMD_MASK; |
8191acbd | 1473 | int page_nid = -1, this_nid = numa_node_id(); |
90572890 | 1474 | int target_nid, last_cpupid = -1; |
8191acbd MG |
1475 | bool page_locked; |
1476 | bool migrated = false; | |
b191f9b1 | 1477 | bool was_writable; |
6688cc05 | 1478 | int flags = 0; |
d10e63f2 | 1479 | |
c0e7cad9 MG |
1480 | /* A PROT_NONE fault should not end up here */ |
1481 | BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))); | |
1482 | ||
bae473a4 KS |
1483 | fe->ptl = pmd_lock(vma->vm_mm, fe->pmd); |
1484 | if (unlikely(!pmd_same(pmd, *fe->pmd))) | |
d10e63f2 MG |
1485 | goto out_unlock; |
1486 | ||
de466bd6 MG |
1487 | /* |
1488 | * If there are potential migrations, wait for completion and retry | |
1489 | * without disrupting NUMA hinting information. Do not relock and | |
1490 | * check_same as the page may no longer be mapped. | |
1491 | */ | |
bae473a4 KS |
1492 | if (unlikely(pmd_trans_migrating(*fe->pmd))) { |
1493 | page = pmd_page(*fe->pmd); | |
1494 | spin_unlock(fe->ptl); | |
5d833062 | 1495 | wait_on_page_locked(page); |
de466bd6 MG |
1496 | goto out; |
1497 | } | |
1498 | ||
d10e63f2 | 1499 | page = pmd_page(pmd); |
a1a46184 | 1500 | BUG_ON(is_huge_zero_page(page)); |
8191acbd | 1501 | page_nid = page_to_nid(page); |
90572890 | 1502 | last_cpupid = page_cpupid_last(page); |
03c5a6e1 | 1503 | count_vm_numa_event(NUMA_HINT_FAULTS); |
04bb2f94 | 1504 | if (page_nid == this_nid) { |
03c5a6e1 | 1505 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
04bb2f94 RR |
1506 | flags |= TNF_FAULT_LOCAL; |
1507 | } | |
4daae3b4 | 1508 | |
bea66fbd MG |
1509 | /* See similar comment in do_numa_page for explanation */ |
1510 | if (!(vma->vm_flags & VM_WRITE)) | |
6688cc05 PZ |
1511 | flags |= TNF_NO_GROUP; |
1512 | ||
ff9042b1 MG |
1513 | /* |
1514 | * Acquire the page lock to serialise THP migrations but avoid dropping | |
1515 | * page_table_lock if at all possible | |
1516 | */ | |
b8916634 MG |
1517 | page_locked = trylock_page(page); |
1518 | target_nid = mpol_misplaced(page, vma, haddr); | |
1519 | if (target_nid == -1) { | |
1520 | /* If the page was locked, there are no parallel migrations */ | |
a54a407f | 1521 | if (page_locked) |
b8916634 | 1522 | goto clear_pmdnuma; |
2b4847e7 | 1523 | } |
4daae3b4 | 1524 | |
de466bd6 | 1525 | /* Migration could have started since the pmd_trans_migrating check */ |
2b4847e7 | 1526 | if (!page_locked) { |
bae473a4 | 1527 | spin_unlock(fe->ptl); |
b8916634 | 1528 | wait_on_page_locked(page); |
a54a407f | 1529 | page_nid = -1; |
b8916634 MG |
1530 | goto out; |
1531 | } | |
1532 | ||
2b4847e7 MG |
1533 | /* |
1534 | * Page is misplaced. Page lock serialises migrations. Acquire anon_vma | |
1535 | * to serialises splits | |
1536 | */ | |
b8916634 | 1537 | get_page(page); |
bae473a4 | 1538 | spin_unlock(fe->ptl); |
b8916634 | 1539 | anon_vma = page_lock_anon_vma_read(page); |
4daae3b4 | 1540 | |
c69307d5 | 1541 | /* Confirm the PMD did not change while page_table_lock was released */ |
bae473a4 KS |
1542 | spin_lock(fe->ptl); |
1543 | if (unlikely(!pmd_same(pmd, *fe->pmd))) { | |
b32967ff MG |
1544 | unlock_page(page); |
1545 | put_page(page); | |
a54a407f | 1546 | page_nid = -1; |
4daae3b4 | 1547 | goto out_unlock; |
b32967ff | 1548 | } |
ff9042b1 | 1549 | |
c3a489ca MG |
1550 | /* Bail if we fail to protect against THP splits for any reason */ |
1551 | if (unlikely(!anon_vma)) { | |
1552 | put_page(page); | |
1553 | page_nid = -1; | |
1554 | goto clear_pmdnuma; | |
1555 | } | |
1556 | ||
a54a407f MG |
1557 | /* |
1558 | * Migrate the THP to the requested node, returns with page unlocked | |
8a0516ed | 1559 | * and access rights restored. |
a54a407f | 1560 | */ |
bae473a4 KS |
1561 | spin_unlock(fe->ptl); |
1562 | migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma, | |
1563 | fe->pmd, pmd, fe->address, page, target_nid); | |
6688cc05 PZ |
1564 | if (migrated) { |
1565 | flags |= TNF_MIGRATED; | |
8191acbd | 1566 | page_nid = target_nid; |
074c2381 MG |
1567 | } else |
1568 | flags |= TNF_MIGRATE_FAIL; | |
b32967ff | 1569 | |
8191acbd | 1570 | goto out; |
b32967ff | 1571 | clear_pmdnuma: |
a54a407f | 1572 | BUG_ON(!PageLocked(page)); |
b191f9b1 | 1573 | was_writable = pmd_write(pmd); |
4d942466 | 1574 | pmd = pmd_modify(pmd, vma->vm_page_prot); |
b7b04004 | 1575 | pmd = pmd_mkyoung(pmd); |
b191f9b1 MG |
1576 | if (was_writable) |
1577 | pmd = pmd_mkwrite(pmd); | |
bae473a4 KS |
1578 | set_pmd_at(vma->vm_mm, haddr, fe->pmd, pmd); |
1579 | update_mmu_cache_pmd(vma, fe->address, fe->pmd); | |
a54a407f | 1580 | unlock_page(page); |
d10e63f2 | 1581 | out_unlock: |
bae473a4 | 1582 | spin_unlock(fe->ptl); |
b8916634 MG |
1583 | |
1584 | out: | |
1585 | if (anon_vma) | |
1586 | page_unlock_anon_vma_read(anon_vma); | |
1587 | ||
8191acbd | 1588 | if (page_nid != -1) |
bae473a4 | 1589 | task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, fe->flags); |
8191acbd | 1590 | |
d10e63f2 MG |
1591 | return 0; |
1592 | } | |
1593 | ||
b8d3c4c3 MK |
1594 | int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
1595 | pmd_t *pmd, unsigned long addr, unsigned long next) | |
1596 | ||
1597 | { | |
1598 | spinlock_t *ptl; | |
1599 | pmd_t orig_pmd; | |
1600 | struct page *page; | |
1601 | struct mm_struct *mm = tlb->mm; | |
1602 | int ret = 0; | |
1603 | ||
b6ec57f4 KS |
1604 | ptl = pmd_trans_huge_lock(pmd, vma); |
1605 | if (!ptl) | |
25eedabe | 1606 | goto out_unlocked; |
b8d3c4c3 MK |
1607 | |
1608 | orig_pmd = *pmd; | |
1609 | if (is_huge_zero_pmd(orig_pmd)) { | |
1610 | ret = 1; | |
1611 | goto out; | |
1612 | } | |
1613 | ||
1614 | page = pmd_page(orig_pmd); | |
1615 | /* | |
1616 | * If other processes are mapping this page, we couldn't discard | |
1617 | * the page unless they all do MADV_FREE so let's skip the page. | |
1618 | */ | |
1619 | if (page_mapcount(page) != 1) | |
1620 | goto out; | |
1621 | ||
1622 | if (!trylock_page(page)) | |
1623 | goto out; | |
1624 | ||
1625 | /* | |
1626 | * If user want to discard part-pages of THP, split it so MADV_FREE | |
1627 | * will deactivate only them. | |
1628 | */ | |
1629 | if (next - addr != HPAGE_PMD_SIZE) { | |
1630 | get_page(page); | |
1631 | spin_unlock(ptl); | |
9818b8cd | 1632 | split_huge_page(page); |
b8d3c4c3 MK |
1633 | put_page(page); |
1634 | unlock_page(page); | |
b8d3c4c3 MK |
1635 | goto out_unlocked; |
1636 | } | |
1637 | ||
1638 | if (PageDirty(page)) | |
1639 | ClearPageDirty(page); | |
1640 | unlock_page(page); | |
1641 | ||
1642 | if (PageActive(page)) | |
1643 | deactivate_page(page); | |
1644 | ||
1645 | if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { | |
1646 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1647 | tlb->fullmm); | |
1648 | orig_pmd = pmd_mkold(orig_pmd); | |
1649 | orig_pmd = pmd_mkclean(orig_pmd); | |
1650 | ||
1651 | set_pmd_at(mm, addr, pmd, orig_pmd); | |
1652 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1653 | } | |
1654 | ret = 1; | |
1655 | out: | |
1656 | spin_unlock(ptl); | |
1657 | out_unlocked: | |
1658 | return ret; | |
1659 | } | |
1660 | ||
71e3aac0 | 1661 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
f21760b1 | 1662 | pmd_t *pmd, unsigned long addr) |
71e3aac0 | 1663 | { |
da146769 | 1664 | pmd_t orig_pmd; |
bf929152 | 1665 | spinlock_t *ptl; |
71e3aac0 | 1666 | |
b6ec57f4 KS |
1667 | ptl = __pmd_trans_huge_lock(pmd, vma); |
1668 | if (!ptl) | |
da146769 KS |
1669 | return 0; |
1670 | /* | |
1671 | * For architectures like ppc64 we look at deposited pgtable | |
1672 | * when calling pmdp_huge_get_and_clear. So do the | |
1673 | * pgtable_trans_huge_withdraw after finishing pmdp related | |
1674 | * operations. | |
1675 | */ | |
1676 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1677 | tlb->fullmm); | |
1678 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1679 | if (vma_is_dax(vma)) { | |
1680 | spin_unlock(ptl); | |
1681 | if (is_huge_zero_pmd(orig_pmd)) | |
aa88b68c | 1682 | tlb_remove_page(tlb, pmd_page(orig_pmd)); |
da146769 KS |
1683 | } else if (is_huge_zero_pmd(orig_pmd)) { |
1684 | pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); | |
1685 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1686 | spin_unlock(ptl); | |
aa88b68c | 1687 | tlb_remove_page(tlb, pmd_page(orig_pmd)); |
da146769 KS |
1688 | } else { |
1689 | struct page *page = pmd_page(orig_pmd); | |
d281ee61 | 1690 | page_remove_rmap(page, true); |
da146769 KS |
1691 | VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); |
1692 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1693 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
1694 | pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); | |
1695 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1696 | spin_unlock(ptl); | |
e77b0852 | 1697 | tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); |
025c5b24 | 1698 | } |
da146769 | 1699 | return 1; |
71e3aac0 AA |
1700 | } |
1701 | ||
bf8616d5 | 1702 | bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, |
37a1c49a AA |
1703 | unsigned long new_addr, unsigned long old_end, |
1704 | pmd_t *old_pmd, pmd_t *new_pmd) | |
1705 | { | |
bf929152 | 1706 | spinlock_t *old_ptl, *new_ptl; |
37a1c49a | 1707 | pmd_t pmd; |
37a1c49a AA |
1708 | struct mm_struct *mm = vma->vm_mm; |
1709 | ||
1710 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1711 | (new_addr & ~HPAGE_PMD_MASK) || | |
bf8616d5 | 1712 | old_end - old_addr < HPAGE_PMD_SIZE) |
4b471e88 | 1713 | return false; |
37a1c49a AA |
1714 | |
1715 | /* | |
1716 | * The destination pmd shouldn't be established, free_pgtables() | |
1717 | * should have release it. | |
1718 | */ | |
1719 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1720 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
4b471e88 | 1721 | return false; |
37a1c49a AA |
1722 | } |
1723 | ||
bf929152 KS |
1724 | /* |
1725 | * We don't have to worry about the ordering of src and dst | |
1726 | * ptlocks because exclusive mmap_sem prevents deadlock. | |
1727 | */ | |
b6ec57f4 KS |
1728 | old_ptl = __pmd_trans_huge_lock(old_pmd, vma); |
1729 | if (old_ptl) { | |
bf929152 KS |
1730 | new_ptl = pmd_lockptr(mm, new_pmd); |
1731 | if (new_ptl != old_ptl) | |
1732 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); | |
8809aa2d | 1733 | pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); |
025c5b24 | 1734 | VM_BUG_ON(!pmd_none(*new_pmd)); |
3592806c | 1735 | |
69a8ec2d KS |
1736 | if (pmd_move_must_withdraw(new_ptl, old_ptl) && |
1737 | vma_is_anonymous(vma)) { | |
b3084f4d | 1738 | pgtable_t pgtable; |
3592806c KS |
1739 | pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); |
1740 | pgtable_trans_huge_deposit(mm, new_pmd, pgtable); | |
3592806c | 1741 | } |
b3084f4d AK |
1742 | set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); |
1743 | if (new_ptl != old_ptl) | |
1744 | spin_unlock(new_ptl); | |
bf929152 | 1745 | spin_unlock(old_ptl); |
4b471e88 | 1746 | return true; |
37a1c49a | 1747 | } |
4b471e88 | 1748 | return false; |
37a1c49a AA |
1749 | } |
1750 | ||
f123d74a MG |
1751 | /* |
1752 | * Returns | |
1753 | * - 0 if PMD could not be locked | |
1754 | * - 1 if PMD was locked but protections unchange and TLB flush unnecessary | |
1755 | * - HPAGE_PMD_NR is protections changed and TLB flush necessary | |
1756 | */ | |
cd7548ab | 1757 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
e944fd67 | 1758 | unsigned long addr, pgprot_t newprot, int prot_numa) |
cd7548ab JW |
1759 | { |
1760 | struct mm_struct *mm = vma->vm_mm; | |
bf929152 | 1761 | spinlock_t *ptl; |
cd7548ab JW |
1762 | int ret = 0; |
1763 | ||
b6ec57f4 KS |
1764 | ptl = __pmd_trans_huge_lock(pmd, vma); |
1765 | if (ptl) { | |
025c5b24 | 1766 | pmd_t entry; |
b191f9b1 | 1767 | bool preserve_write = prot_numa && pmd_write(*pmd); |
ba68bc01 | 1768 | ret = 1; |
e944fd67 MG |
1769 | |
1770 | /* | |
1771 | * Avoid trapping faults against the zero page. The read-only | |
1772 | * data is likely to be read-cached on the local CPU and | |
1773 | * local/remote hits to the zero page are not interesting. | |
1774 | */ | |
1775 | if (prot_numa && is_huge_zero_pmd(*pmd)) { | |
1776 | spin_unlock(ptl); | |
ba68bc01 | 1777 | return ret; |
e944fd67 MG |
1778 | } |
1779 | ||
10c1045f | 1780 | if (!prot_numa || !pmd_protnone(*pmd)) { |
8809aa2d | 1781 | entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd); |
10c1045f | 1782 | entry = pmd_modify(entry, newprot); |
b191f9b1 MG |
1783 | if (preserve_write) |
1784 | entry = pmd_mkwrite(entry); | |
10c1045f MG |
1785 | ret = HPAGE_PMD_NR; |
1786 | set_pmd_at(mm, addr, pmd, entry); | |
b191f9b1 | 1787 | BUG_ON(!preserve_write && pmd_write(entry)); |
10c1045f | 1788 | } |
bf929152 | 1789 | spin_unlock(ptl); |
025c5b24 NH |
1790 | } |
1791 | ||
1792 | return ret; | |
1793 | } | |
1794 | ||
1795 | /* | |
4b471e88 | 1796 | * Returns true if a given pmd maps a thp, false otherwise. |
025c5b24 | 1797 | * |
4b471e88 KS |
1798 | * Note that if it returns true, this routine returns without unlocking page |
1799 | * table lock. So callers must unlock it. | |
025c5b24 | 1800 | */ |
b6ec57f4 | 1801 | spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) |
025c5b24 | 1802 | { |
b6ec57f4 KS |
1803 | spinlock_t *ptl; |
1804 | ptl = pmd_lock(vma->vm_mm, pmd); | |
5c7fb56e | 1805 | if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd))) |
b6ec57f4 KS |
1806 | return ptl; |
1807 | spin_unlock(ptl); | |
1808 | return NULL; | |
cd7548ab JW |
1809 | } |
1810 | ||
9050d7eb | 1811 | #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE) |
78f11a25 | 1812 | |
60ab3244 AA |
1813 | int hugepage_madvise(struct vm_area_struct *vma, |
1814 | unsigned long *vm_flags, int advice) | |
0af4e98b | 1815 | { |
a664b2d8 AA |
1816 | switch (advice) { |
1817 | case MADV_HUGEPAGE: | |
1e1836e8 AT |
1818 | #ifdef CONFIG_S390 |
1819 | /* | |
1820 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
1821 | * can't handle this properly after s390_enable_sie, so we simply | |
1822 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
1823 | */ | |
1824 | if (mm_has_pgste(vma->vm_mm)) | |
1825 | return 0; | |
1826 | #endif | |
a664b2d8 AA |
1827 | /* |
1828 | * Be somewhat over-protective like KSM for now! | |
1829 | */ | |
1a763615 | 1830 | if (*vm_flags & VM_NO_THP) |
a664b2d8 AA |
1831 | return -EINVAL; |
1832 | *vm_flags &= ~VM_NOHUGEPAGE; | |
1833 | *vm_flags |= VM_HUGEPAGE; | |
60ab3244 AA |
1834 | /* |
1835 | * If the vma become good for khugepaged to scan, | |
1836 | * register it here without waiting a page fault that | |
1837 | * may not happen any time soon. | |
1838 | */ | |
6d50e60c | 1839 | if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags))) |
60ab3244 | 1840 | return -ENOMEM; |
a664b2d8 AA |
1841 | break; |
1842 | case MADV_NOHUGEPAGE: | |
1843 | /* | |
1844 | * Be somewhat over-protective like KSM for now! | |
1845 | */ | |
1a763615 | 1846 | if (*vm_flags & VM_NO_THP) |
a664b2d8 AA |
1847 | return -EINVAL; |
1848 | *vm_flags &= ~VM_HUGEPAGE; | |
1849 | *vm_flags |= VM_NOHUGEPAGE; | |
60ab3244 AA |
1850 | /* |
1851 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
1852 | * this vma even if we leave the mm registered in khugepaged if | |
1853 | * it got registered before VM_NOHUGEPAGE was set. | |
1854 | */ | |
a664b2d8 AA |
1855 | break; |
1856 | } | |
0af4e98b AA |
1857 | |
1858 | return 0; | |
1859 | } | |
1860 | ||
ba76149f AA |
1861 | static int __init khugepaged_slab_init(void) |
1862 | { | |
1863 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
1864 | sizeof(struct mm_slot), | |
1865 | __alignof__(struct mm_slot), 0, NULL); | |
1866 | if (!mm_slot_cache) | |
1867 | return -ENOMEM; | |
1868 | ||
1869 | return 0; | |
1870 | } | |
1871 | ||
65ebb64f KS |
1872 | static void __init khugepaged_slab_exit(void) |
1873 | { | |
1874 | kmem_cache_destroy(mm_slot_cache); | |
1875 | } | |
1876 | ||
ba76149f AA |
1877 | static inline struct mm_slot *alloc_mm_slot(void) |
1878 | { | |
1879 | if (!mm_slot_cache) /* initialization failed */ | |
1880 | return NULL; | |
1881 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
1882 | } | |
1883 | ||
1884 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
1885 | { | |
1886 | kmem_cache_free(mm_slot_cache, mm_slot); | |
1887 | } | |
1888 | ||
ba76149f AA |
1889 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) |
1890 | { | |
1891 | struct mm_slot *mm_slot; | |
ba76149f | 1892 | |
b67bfe0d | 1893 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) |
ba76149f AA |
1894 | if (mm == mm_slot->mm) |
1895 | return mm_slot; | |
43b5fbbd | 1896 | |
ba76149f AA |
1897 | return NULL; |
1898 | } | |
1899 | ||
1900 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
1901 | struct mm_slot *mm_slot) | |
1902 | { | |
ba76149f | 1903 | mm_slot->mm = mm; |
43b5fbbd | 1904 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); |
ba76149f AA |
1905 | } |
1906 | ||
1907 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
1908 | { | |
1909 | return atomic_read(&mm->mm_users) == 0; | |
1910 | } | |
1911 | ||
1912 | int __khugepaged_enter(struct mm_struct *mm) | |
1913 | { | |
1914 | struct mm_slot *mm_slot; | |
1915 | int wakeup; | |
1916 | ||
1917 | mm_slot = alloc_mm_slot(); | |
1918 | if (!mm_slot) | |
1919 | return -ENOMEM; | |
1920 | ||
1921 | /* __khugepaged_exit() must not run from under us */ | |
96dad67f | 1922 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); |
ba76149f AA |
1923 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { |
1924 | free_mm_slot(mm_slot); | |
1925 | return 0; | |
1926 | } | |
1927 | ||
1928 | spin_lock(&khugepaged_mm_lock); | |
1929 | insert_to_mm_slots_hash(mm, mm_slot); | |
1930 | /* | |
1931 | * Insert just behind the scanning cursor, to let the area settle | |
1932 | * down a little. | |
1933 | */ | |
1934 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
1935 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
1936 | spin_unlock(&khugepaged_mm_lock); | |
1937 | ||
1938 | atomic_inc(&mm->mm_count); | |
1939 | if (wakeup) | |
1940 | wake_up_interruptible(&khugepaged_wait); | |
1941 | ||
1942 | return 0; | |
1943 | } | |
1944 | ||
6d50e60c DR |
1945 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, |
1946 | unsigned long vm_flags) | |
ba76149f AA |
1947 | { |
1948 | unsigned long hstart, hend; | |
1949 | if (!vma->anon_vma) | |
1950 | /* | |
1951 | * Not yet faulted in so we will register later in the | |
1952 | * page fault if needed. | |
1953 | */ | |
1954 | return 0; | |
3486b85a | 1955 | if (vma->vm_ops || (vm_flags & VM_NO_THP)) |
ba76149f AA |
1956 | /* khugepaged not yet working on file or special mappings */ |
1957 | return 0; | |
ba76149f AA |
1958 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
1959 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1960 | if (hstart < hend) | |
6d50e60c | 1961 | return khugepaged_enter(vma, vm_flags); |
ba76149f AA |
1962 | return 0; |
1963 | } | |
1964 | ||
1965 | void __khugepaged_exit(struct mm_struct *mm) | |
1966 | { | |
1967 | struct mm_slot *mm_slot; | |
1968 | int free = 0; | |
1969 | ||
1970 | spin_lock(&khugepaged_mm_lock); | |
1971 | mm_slot = get_mm_slot(mm); | |
1972 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
43b5fbbd | 1973 | hash_del(&mm_slot->hash); |
ba76149f AA |
1974 | list_del(&mm_slot->mm_node); |
1975 | free = 1; | |
1976 | } | |
d788e80a | 1977 | spin_unlock(&khugepaged_mm_lock); |
ba76149f AA |
1978 | |
1979 | if (free) { | |
ba76149f AA |
1980 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); |
1981 | free_mm_slot(mm_slot); | |
1982 | mmdrop(mm); | |
1983 | } else if (mm_slot) { | |
ba76149f AA |
1984 | /* |
1985 | * This is required to serialize against | |
1986 | * khugepaged_test_exit() (which is guaranteed to run | |
1987 | * under mmap sem read mode). Stop here (after we | |
1988 | * return all pagetables will be destroyed) until | |
1989 | * khugepaged has finished working on the pagetables | |
1990 | * under the mmap_sem. | |
1991 | */ | |
1992 | down_write(&mm->mmap_sem); | |
1993 | up_write(&mm->mmap_sem); | |
d788e80a | 1994 | } |
ba76149f AA |
1995 | } |
1996 | ||
1997 | static void release_pte_page(struct page *page) | |
1998 | { | |
1999 | /* 0 stands for page_is_file_cache(page) == false */ | |
2000 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
2001 | unlock_page(page); | |
2002 | putback_lru_page(page); | |
2003 | } | |
2004 | ||
2005 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
2006 | { | |
2007 | while (--_pte >= pte) { | |
2008 | pte_t pteval = *_pte; | |
ca0984ca | 2009 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) |
ba76149f AA |
2010 | release_pte_page(pte_page(pteval)); |
2011 | } | |
2012 | } | |
2013 | ||
ba76149f AA |
2014 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, |
2015 | unsigned long address, | |
2016 | pte_t *pte) | |
2017 | { | |
7d2eba05 | 2018 | struct page *page = NULL; |
ba76149f | 2019 | pte_t *_pte; |
7d2eba05 | 2020 | int none_or_zero = 0, result = 0; |
10359213 | 2021 | bool referenced = false, writable = false; |
7d2eba05 | 2022 | |
ba76149f AA |
2023 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; |
2024 | _pte++, address += PAGE_SIZE) { | |
2025 | pte_t pteval = *_pte; | |
47aee4d8 MK |
2026 | if (pte_none(pteval) || (pte_present(pteval) && |
2027 | is_zero_pfn(pte_pfn(pteval)))) { | |
c1294d05 | 2028 | if (!userfaultfd_armed(vma) && |
7d2eba05 | 2029 | ++none_or_zero <= khugepaged_max_ptes_none) { |
ba76149f | 2030 | continue; |
7d2eba05 EA |
2031 | } else { |
2032 | result = SCAN_EXCEED_NONE_PTE; | |
ba76149f | 2033 | goto out; |
7d2eba05 | 2034 | } |
ba76149f | 2035 | } |
7d2eba05 EA |
2036 | if (!pte_present(pteval)) { |
2037 | result = SCAN_PTE_NON_PRESENT; | |
ba76149f | 2038 | goto out; |
7d2eba05 | 2039 | } |
ba76149f | 2040 | page = vm_normal_page(vma, address, pteval); |
7d2eba05 EA |
2041 | if (unlikely(!page)) { |
2042 | result = SCAN_PAGE_NULL; | |
ba76149f | 2043 | goto out; |
7d2eba05 | 2044 | } |
344aa35c | 2045 | |
309381fe SL |
2046 | VM_BUG_ON_PAGE(PageCompound(page), page); |
2047 | VM_BUG_ON_PAGE(!PageAnon(page), page); | |
2048 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
ba76149f | 2049 | |
ba76149f AA |
2050 | /* |
2051 | * We can do it before isolate_lru_page because the | |
2052 | * page can't be freed from under us. NOTE: PG_lock | |
2053 | * is needed to serialize against split_huge_page | |
2054 | * when invoked from the VM. | |
2055 | */ | |
7d2eba05 EA |
2056 | if (!trylock_page(page)) { |
2057 | result = SCAN_PAGE_LOCK; | |
ba76149f | 2058 | goto out; |
7d2eba05 | 2059 | } |
10359213 EA |
2060 | |
2061 | /* | |
2062 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2063 | * The page must only be referenced by the scanned process | |
2064 | * and page swap cache. | |
2065 | */ | |
2066 | if (page_count(page) != 1 + !!PageSwapCache(page)) { | |
2067 | unlock_page(page); | |
7d2eba05 | 2068 | result = SCAN_PAGE_COUNT; |
10359213 EA |
2069 | goto out; |
2070 | } | |
2071 | if (pte_write(pteval)) { | |
2072 | writable = true; | |
2073 | } else { | |
6d0a07ed AA |
2074 | if (PageSwapCache(page) && |
2075 | !reuse_swap_page(page, NULL)) { | |
10359213 | 2076 | unlock_page(page); |
7d2eba05 | 2077 | result = SCAN_SWAP_CACHE_PAGE; |
10359213 EA |
2078 | goto out; |
2079 | } | |
2080 | /* | |
2081 | * Page is not in the swap cache. It can be collapsed | |
2082 | * into a THP. | |
2083 | */ | |
2084 | } | |
2085 | ||
ba76149f AA |
2086 | /* |
2087 | * Isolate the page to avoid collapsing an hugepage | |
2088 | * currently in use by the VM. | |
2089 | */ | |
2090 | if (isolate_lru_page(page)) { | |
2091 | unlock_page(page); | |
7d2eba05 | 2092 | result = SCAN_DEL_PAGE_LRU; |
ba76149f AA |
2093 | goto out; |
2094 | } | |
2095 | /* 0 stands for page_is_file_cache(page) == false */ | |
2096 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
309381fe SL |
2097 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
2098 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
ba76149f AA |
2099 | |
2100 | /* If there is no mapped pte young don't collapse the page */ | |
33c3fc71 VD |
2101 | if (pte_young(pteval) || |
2102 | page_is_young(page) || PageReferenced(page) || | |
8ee53820 | 2103 | mmu_notifier_test_young(vma->vm_mm, address)) |
10359213 | 2104 | referenced = true; |
ba76149f | 2105 | } |
7d2eba05 EA |
2106 | if (likely(writable)) { |
2107 | if (likely(referenced)) { | |
2108 | result = SCAN_SUCCEED; | |
16fd0fe4 | 2109 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, |
7d2eba05 EA |
2110 | referenced, writable, result); |
2111 | return 1; | |
2112 | } | |
2113 | } else { | |
2114 | result = SCAN_PAGE_RO; | |
2115 | } | |
2116 | ||
ba76149f | 2117 | out: |
344aa35c | 2118 | release_pte_pages(pte, _pte); |
16fd0fe4 | 2119 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, |
7d2eba05 | 2120 | referenced, writable, result); |
344aa35c | 2121 | return 0; |
ba76149f AA |
2122 | } |
2123 | ||
2124 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
2125 | struct vm_area_struct *vma, | |
2126 | unsigned long address, | |
2127 | spinlock_t *ptl) | |
2128 | { | |
2129 | pte_t *_pte; | |
2130 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { | |
2131 | pte_t pteval = *_pte; | |
2132 | struct page *src_page; | |
2133 | ||
ca0984ca | 2134 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
ba76149f AA |
2135 | clear_user_highpage(page, address); |
2136 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
ca0984ca EA |
2137 | if (is_zero_pfn(pte_pfn(pteval))) { |
2138 | /* | |
2139 | * ptl mostly unnecessary. | |
2140 | */ | |
2141 | spin_lock(ptl); | |
2142 | /* | |
2143 | * paravirt calls inside pte_clear here are | |
2144 | * superfluous. | |
2145 | */ | |
2146 | pte_clear(vma->vm_mm, address, _pte); | |
2147 | spin_unlock(ptl); | |
2148 | } | |
ba76149f AA |
2149 | } else { |
2150 | src_page = pte_page(pteval); | |
2151 | copy_user_highpage(page, src_page, address, vma); | |
309381fe | 2152 | VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page); |
ba76149f AA |
2153 | release_pte_page(src_page); |
2154 | /* | |
2155 | * ptl mostly unnecessary, but preempt has to | |
2156 | * be disabled to update the per-cpu stats | |
2157 | * inside page_remove_rmap(). | |
2158 | */ | |
2159 | spin_lock(ptl); | |
2160 | /* | |
2161 | * paravirt calls inside pte_clear here are | |
2162 | * superfluous. | |
2163 | */ | |
2164 | pte_clear(vma->vm_mm, address, _pte); | |
d281ee61 | 2165 | page_remove_rmap(src_page, false); |
ba76149f AA |
2166 | spin_unlock(ptl); |
2167 | free_page_and_swap_cache(src_page); | |
2168 | } | |
2169 | ||
2170 | address += PAGE_SIZE; | |
2171 | page++; | |
2172 | } | |
2173 | } | |
2174 | ||
26234f36 | 2175 | static void khugepaged_alloc_sleep(void) |
ba76149f | 2176 | { |
bde43c6c PM |
2177 | DEFINE_WAIT(wait); |
2178 | ||
2179 | add_wait_queue(&khugepaged_wait, &wait); | |
2180 | freezable_schedule_timeout_interruptible( | |
2181 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
2182 | remove_wait_queue(&khugepaged_wait, &wait); | |
26234f36 | 2183 | } |
ba76149f | 2184 | |
9f1b868a BL |
2185 | static int khugepaged_node_load[MAX_NUMNODES]; |
2186 | ||
14a4e214 DR |
2187 | static bool khugepaged_scan_abort(int nid) |
2188 | { | |
2189 | int i; | |
2190 | ||
2191 | /* | |
2192 | * If zone_reclaim_mode is disabled, then no extra effort is made to | |
2193 | * allocate memory locally. | |
2194 | */ | |
2195 | if (!zone_reclaim_mode) | |
2196 | return false; | |
2197 | ||
2198 | /* If there is a count for this node already, it must be acceptable */ | |
2199 | if (khugepaged_node_load[nid]) | |
2200 | return false; | |
2201 | ||
2202 | for (i = 0; i < MAX_NUMNODES; i++) { | |
2203 | if (!khugepaged_node_load[i]) | |
2204 | continue; | |
2205 | if (node_distance(nid, i) > RECLAIM_DISTANCE) | |
2206 | return true; | |
2207 | } | |
2208 | return false; | |
2209 | } | |
2210 | ||
26234f36 | 2211 | #ifdef CONFIG_NUMA |
9f1b868a BL |
2212 | static int khugepaged_find_target_node(void) |
2213 | { | |
2214 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
2215 | int nid, target_node = 0, max_value = 0; | |
2216 | ||
2217 | /* find first node with max normal pages hit */ | |
2218 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
2219 | if (khugepaged_node_load[nid] > max_value) { | |
2220 | max_value = khugepaged_node_load[nid]; | |
2221 | target_node = nid; | |
2222 | } | |
2223 | ||
2224 | /* do some balance if several nodes have the same hit record */ | |
2225 | if (target_node <= last_khugepaged_target_node) | |
2226 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
2227 | nid++) | |
2228 | if (max_value == khugepaged_node_load[nid]) { | |
2229 | target_node = nid; | |
2230 | break; | |
2231 | } | |
2232 | ||
2233 | last_khugepaged_target_node = target_node; | |
2234 | return target_node; | |
2235 | } | |
2236 | ||
26234f36 XG |
2237 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) |
2238 | { | |
2239 | if (IS_ERR(*hpage)) { | |
2240 | if (!*wait) | |
2241 | return false; | |
2242 | ||
2243 | *wait = false; | |
e3b4126c | 2244 | *hpage = NULL; |
26234f36 XG |
2245 | khugepaged_alloc_sleep(); |
2246 | } else if (*hpage) { | |
2247 | put_page(*hpage); | |
2248 | *hpage = NULL; | |
2249 | } | |
2250 | ||
2251 | return true; | |
2252 | } | |
2253 | ||
3b363692 MH |
2254 | static struct page * |
2255 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
d6669d68 | 2256 | unsigned long address, int node) |
26234f36 | 2257 | { |
309381fe | 2258 | VM_BUG_ON_PAGE(*hpage, *hpage); |
8b164568 | 2259 | |
ce83d217 | 2260 | /* |
8b164568 VB |
2261 | * Before allocating the hugepage, release the mmap_sem read lock. |
2262 | * The allocation can take potentially a long time if it involves | |
2263 | * sync compaction, and we do not need to hold the mmap_sem during | |
2264 | * that. We will recheck the vma after taking it again in write mode. | |
ce83d217 | 2265 | */ |
8b164568 VB |
2266 | up_read(&mm->mmap_sem); |
2267 | ||
96db800f | 2268 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); |
26234f36 | 2269 | if (unlikely(!*hpage)) { |
81ab4201 | 2270 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); |
ce83d217 | 2271 | *hpage = ERR_PTR(-ENOMEM); |
26234f36 | 2272 | return NULL; |
ce83d217 | 2273 | } |
26234f36 | 2274 | |
9a982250 | 2275 | prep_transhuge_page(*hpage); |
65b3c07b | 2276 | count_vm_event(THP_COLLAPSE_ALLOC); |
26234f36 XG |
2277 | return *hpage; |
2278 | } | |
2279 | #else | |
9f1b868a BL |
2280 | static int khugepaged_find_target_node(void) |
2281 | { | |
2282 | return 0; | |
2283 | } | |
2284 | ||
444eb2a4 | 2285 | static inline struct page *alloc_khugepaged_hugepage(void) |
10dc4155 | 2286 | { |
9a982250 KS |
2287 | struct page *page; |
2288 | ||
444eb2a4 MG |
2289 | page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(), |
2290 | HPAGE_PMD_ORDER); | |
9a982250 KS |
2291 | if (page) |
2292 | prep_transhuge_page(page); | |
2293 | return page; | |
10dc4155 BL |
2294 | } |
2295 | ||
26234f36 XG |
2296 | static struct page *khugepaged_alloc_hugepage(bool *wait) |
2297 | { | |
2298 | struct page *hpage; | |
2299 | ||
2300 | do { | |
444eb2a4 | 2301 | hpage = alloc_khugepaged_hugepage(); |
26234f36 XG |
2302 | if (!hpage) { |
2303 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
2304 | if (!*wait) | |
2305 | return NULL; | |
2306 | ||
2307 | *wait = false; | |
2308 | khugepaged_alloc_sleep(); | |
2309 | } else | |
2310 | count_vm_event(THP_COLLAPSE_ALLOC); | |
2311 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
2312 | ||
2313 | return hpage; | |
2314 | } | |
2315 | ||
2316 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
2317 | { | |
2318 | if (!*hpage) | |
2319 | *hpage = khugepaged_alloc_hugepage(wait); | |
2320 | ||
2321 | if (unlikely(!*hpage)) | |
2322 | return false; | |
2323 | ||
2324 | return true; | |
2325 | } | |
2326 | ||
3b363692 MH |
2327 | static struct page * |
2328 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
d6669d68 | 2329 | unsigned long address, int node) |
26234f36 XG |
2330 | { |
2331 | up_read(&mm->mmap_sem); | |
2332 | VM_BUG_ON(!*hpage); | |
3b363692 | 2333 | |
26234f36 XG |
2334 | return *hpage; |
2335 | } | |
692e0b35 AA |
2336 | #endif |
2337 | ||
fa475e51 BL |
2338 | static bool hugepage_vma_check(struct vm_area_struct *vma) |
2339 | { | |
2340 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || | |
2341 | (vma->vm_flags & VM_NOHUGEPAGE)) | |
2342 | return false; | |
fa475e51 BL |
2343 | if (!vma->anon_vma || vma->vm_ops) |
2344 | return false; | |
2345 | if (is_vma_temporary_stack(vma)) | |
2346 | return false; | |
3486b85a | 2347 | return !(vma->vm_flags & VM_NO_THP); |
fa475e51 BL |
2348 | } |
2349 | ||
72695862 EA |
2350 | /* |
2351 | * If mmap_sem temporarily dropped, revalidate vma | |
2352 | * before taking mmap_sem. | |
2353 | * Return 0 if succeeds, otherwise return none-zero | |
2354 | * value (scan code). | |
2355 | */ | |
2356 | ||
2357 | static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address) | |
2358 | { | |
2359 | struct vm_area_struct *vma; | |
2360 | unsigned long hstart, hend; | |
2361 | ||
2362 | if (unlikely(khugepaged_test_exit(mm))) | |
2363 | return SCAN_ANY_PROCESS; | |
2364 | ||
2365 | vma = find_vma(mm, address); | |
2366 | if (!vma) | |
2367 | return SCAN_VMA_NULL; | |
2368 | ||
2369 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2370 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2371 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
2372 | return SCAN_ADDRESS_RANGE; | |
2373 | if (!hugepage_vma_check(vma)) | |
2374 | return SCAN_VMA_CHECK; | |
2375 | return 0; | |
2376 | } | |
2377 | ||
8a966ed7 EA |
2378 | /* |
2379 | * Bring missing pages in from swap, to complete THP collapse. | |
2380 | * Only done if khugepaged_scan_pmd believes it is worthwhile. | |
2381 | * | |
2382 | * Called and returns without pte mapped or spinlocks held, | |
2383 | * but with mmap_sem held to protect against vma changes. | |
2384 | */ | |
2385 | ||
72695862 | 2386 | static bool __collapse_huge_page_swapin(struct mm_struct *mm, |
8a966ed7 EA |
2387 | struct vm_area_struct *vma, |
2388 | unsigned long address, pmd_t *pmd) | |
2389 | { | |
bae473a4 | 2390 | pte_t pteval; |
8a966ed7 | 2391 | int swapped_in = 0, ret = 0; |
bae473a4 KS |
2392 | struct fault_env fe = { |
2393 | .vma = vma, | |
2394 | .address = address, | |
2395 | .flags = FAULT_FLAG_ALLOW_RETRY, | |
2396 | .pmd = pmd, | |
2397 | }; | |
2398 | ||
2399 | fe.pte = pte_offset_map(pmd, address); | |
2400 | for (; fe.address < address + HPAGE_PMD_NR*PAGE_SIZE; | |
2401 | fe.pte++, fe.address += PAGE_SIZE) { | |
2402 | pteval = *fe.pte; | |
8a966ed7 EA |
2403 | if (!is_swap_pte(pteval)) |
2404 | continue; | |
2405 | swapped_in++; | |
bae473a4 | 2406 | ret = do_swap_page(&fe, pteval); |
72695862 EA |
2407 | /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */ |
2408 | if (ret & VM_FAULT_RETRY) { | |
2409 | down_read(&mm->mmap_sem); | |
2410 | /* vma is no longer available, don't continue to swapin */ | |
2411 | if (hugepage_vma_revalidate(mm, address)) | |
2412 | return false; | |
1f52e67e KS |
2413 | /* check if the pmd is still valid */ |
2414 | if (mm_find_pmd(mm, address) != pmd) | |
2415 | return false; | |
72695862 | 2416 | } |
8a966ed7 EA |
2417 | if (ret & VM_FAULT_ERROR) { |
2418 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, 0); | |
72695862 | 2419 | return false; |
8a966ed7 EA |
2420 | } |
2421 | /* pte is unmapped now, we need to map it */ | |
bae473a4 | 2422 | fe.pte = pte_offset_map(pmd, fe.address); |
8a966ed7 | 2423 | } |
bae473a4 KS |
2424 | fe.pte--; |
2425 | pte_unmap(fe.pte); | |
8a966ed7 | 2426 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, 1); |
72695862 | 2427 | return true; |
8a966ed7 EA |
2428 | } |
2429 | ||
26234f36 XG |
2430 | static void collapse_huge_page(struct mm_struct *mm, |
2431 | unsigned long address, | |
2432 | struct page **hpage, | |
2433 | struct vm_area_struct *vma, | |
2434 | int node) | |
2435 | { | |
26234f36 XG |
2436 | pmd_t *pmd, _pmd; |
2437 | pte_t *pte; | |
2438 | pgtable_t pgtable; | |
2439 | struct page *new_page; | |
c4088ebd | 2440 | spinlock_t *pmd_ptl, *pte_ptl; |
629d9d1c | 2441 | int isolated = 0, result = 0; |
00501b53 | 2442 | struct mem_cgroup *memcg; |
2ec74c3e SG |
2443 | unsigned long mmun_start; /* For mmu_notifiers */ |
2444 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 2445 | gfp_t gfp; |
26234f36 XG |
2446 | |
2447 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2448 | ||
3b363692 | 2449 | /* Only allocate from the target node */ |
444eb2a4 | 2450 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_OTHER_NODE | __GFP_THISNODE; |
3b363692 | 2451 | |
26234f36 | 2452 | /* release the mmap_sem read lock. */ |
d6669d68 | 2453 | new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node); |
7d2eba05 EA |
2454 | if (!new_page) { |
2455 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
2456 | goto out_nolock; | |
2457 | } | |
26234f36 | 2458 | |
f627c2f5 | 2459 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { |
7d2eba05 EA |
2460 | result = SCAN_CGROUP_CHARGE_FAIL; |
2461 | goto out_nolock; | |
2462 | } | |
ba76149f | 2463 | |
72695862 EA |
2464 | down_read(&mm->mmap_sem); |
2465 | result = hugepage_vma_revalidate(mm, address); | |
8024ee2a EA |
2466 | if (result) { |
2467 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
2468 | up_read(&mm->mmap_sem); | |
2469 | goto out_nolock; | |
2470 | } | |
ba76149f | 2471 | |
6219049a | 2472 | pmd = mm_find_pmd(mm, address); |
7d2eba05 EA |
2473 | if (!pmd) { |
2474 | result = SCAN_PMD_NULL; | |
8024ee2a EA |
2475 | mem_cgroup_cancel_charge(new_page, memcg, true); |
2476 | up_read(&mm->mmap_sem); | |
2477 | goto out_nolock; | |
7d2eba05 | 2478 | } |
ba76149f | 2479 | |
72695862 EA |
2480 | /* |
2481 | * __collapse_huge_page_swapin always returns with mmap_sem locked. | |
2482 | * If it fails, release mmap_sem and jump directly out. | |
2483 | * Continuing to collapse causes inconsistency. | |
2484 | */ | |
2485 | if (!__collapse_huge_page_swapin(mm, vma, address, pmd)) { | |
8024ee2a | 2486 | mem_cgroup_cancel_charge(new_page, memcg, true); |
72695862 | 2487 | up_read(&mm->mmap_sem); |
8024ee2a | 2488 | goto out_nolock; |
72695862 EA |
2489 | } |
2490 | ||
2491 | up_read(&mm->mmap_sem); | |
2492 | /* | |
2493 | * Prevent all access to pagetables with the exception of | |
2494 | * gup_fast later handled by the ptep_clear_flush and the VM | |
2495 | * handled by the anon_vma lock + PG_lock. | |
2496 | */ | |
2497 | down_write(&mm->mmap_sem); | |
2498 | result = hugepage_vma_revalidate(mm, address); | |
2499 | if (result) | |
2500 | goto out; | |
1f52e67e KS |
2501 | /* check if the pmd is still valid */ |
2502 | if (mm_find_pmd(mm, address) != pmd) | |
2503 | goto out; | |
8a966ed7 | 2504 | |
4fc3f1d6 | 2505 | anon_vma_lock_write(vma->anon_vma); |
ba76149f AA |
2506 | |
2507 | pte = pte_offset_map(pmd, address); | |
c4088ebd | 2508 | pte_ptl = pte_lockptr(mm, pmd); |
ba76149f | 2509 | |
2ec74c3e SG |
2510 | mmun_start = address; |
2511 | mmun_end = address + HPAGE_PMD_SIZE; | |
2512 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
c4088ebd | 2513 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
ba76149f AA |
2514 | /* |
2515 | * After this gup_fast can't run anymore. This also removes | |
2516 | * any huge TLB entry from the CPU so we won't allow | |
2517 | * huge and small TLB entries for the same virtual address | |
2518 | * to avoid the risk of CPU bugs in that area. | |
2519 | */ | |
15a25b2e | 2520 | _pmd = pmdp_collapse_flush(vma, address, pmd); |
c4088ebd | 2521 | spin_unlock(pmd_ptl); |
2ec74c3e | 2522 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
ba76149f | 2523 | |
c4088ebd | 2524 | spin_lock(pte_ptl); |
ba76149f | 2525 | isolated = __collapse_huge_page_isolate(vma, address, pte); |
c4088ebd | 2526 | spin_unlock(pte_ptl); |
ba76149f AA |
2527 | |
2528 | if (unlikely(!isolated)) { | |
453c7192 | 2529 | pte_unmap(pte); |
c4088ebd | 2530 | spin_lock(pmd_ptl); |
ba76149f | 2531 | BUG_ON(!pmd_none(*pmd)); |
7c342512 AK |
2532 | /* |
2533 | * We can only use set_pmd_at when establishing | |
2534 | * hugepmds and never for establishing regular pmds that | |
2535 | * points to regular pagetables. Use pmd_populate for that | |
2536 | */ | |
2537 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
c4088ebd | 2538 | spin_unlock(pmd_ptl); |
08b52706 | 2539 | anon_vma_unlock_write(vma->anon_vma); |
7d2eba05 | 2540 | result = SCAN_FAIL; |
ce83d217 | 2541 | goto out; |
ba76149f AA |
2542 | } |
2543 | ||
2544 | /* | |
2545 | * All pages are isolated and locked so anon_vma rmap | |
2546 | * can't run anymore. | |
2547 | */ | |
08b52706 | 2548 | anon_vma_unlock_write(vma->anon_vma); |
ba76149f | 2549 | |
c4088ebd | 2550 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); |
453c7192 | 2551 | pte_unmap(pte); |
ba76149f AA |
2552 | __SetPageUptodate(new_page); |
2553 | pgtable = pmd_pgtable(_pmd); | |
ba76149f | 2554 | |
3122359a KS |
2555 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); |
2556 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); | |
ba76149f AA |
2557 | |
2558 | /* | |
2559 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
2560 | * this is needed to avoid the copy_huge_page writes to become | |
2561 | * visible after the set_pmd_at() write. | |
2562 | */ | |
2563 | smp_wmb(); | |
2564 | ||
c4088ebd | 2565 | spin_lock(pmd_ptl); |
ba76149f | 2566 | BUG_ON(!pmd_none(*pmd)); |
d281ee61 | 2567 | page_add_new_anon_rmap(new_page, vma, address, true); |
f627c2f5 | 2568 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
00501b53 | 2569 | lru_cache_add_active_or_unevictable(new_page, vma); |
fce144b4 | 2570 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
ba76149f | 2571 | set_pmd_at(mm, address, pmd, _pmd); |
b113da65 | 2572 | update_mmu_cache_pmd(vma, address, pmd); |
c4088ebd | 2573 | spin_unlock(pmd_ptl); |
ba76149f AA |
2574 | |
2575 | *hpage = NULL; | |
420256ef | 2576 | |
ba76149f | 2577 | khugepaged_pages_collapsed++; |
7d2eba05 | 2578 | result = SCAN_SUCCEED; |
ce83d217 | 2579 | out_up_write: |
ba76149f | 2580 | up_write(&mm->mmap_sem); |
7d2eba05 EA |
2581 | out_nolock: |
2582 | trace_mm_collapse_huge_page(mm, isolated, result); | |
2583 | return; | |
ce83d217 | 2584 | out: |
f627c2f5 | 2585 | mem_cgroup_cancel_charge(new_page, memcg, true); |
ce83d217 | 2586 | goto out_up_write; |
ba76149f AA |
2587 | } |
2588 | ||
2589 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
2590 | struct vm_area_struct *vma, | |
2591 | unsigned long address, | |
2592 | struct page **hpage) | |
2593 | { | |
ba76149f AA |
2594 | pmd_t *pmd; |
2595 | pte_t *pte, *_pte; | |
7d2eba05 EA |
2596 | int ret = 0, none_or_zero = 0, result = 0; |
2597 | struct page *page = NULL; | |
ba76149f AA |
2598 | unsigned long _address; |
2599 | spinlock_t *ptl; | |
70652f6e | 2600 | int node = NUMA_NO_NODE, unmapped = 0; |
10359213 | 2601 | bool writable = false, referenced = false; |
ba76149f AA |
2602 | |
2603 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2604 | ||
6219049a | 2605 | pmd = mm_find_pmd(mm, address); |
7d2eba05 EA |
2606 | if (!pmd) { |
2607 | result = SCAN_PMD_NULL; | |
ba76149f | 2608 | goto out; |
7d2eba05 | 2609 | } |
ba76149f | 2610 | |
9f1b868a | 2611 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); |
ba76149f AA |
2612 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
2613 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
2614 | _pte++, _address += PAGE_SIZE) { | |
2615 | pte_t pteval = *_pte; | |
70652f6e EA |
2616 | if (is_swap_pte(pteval)) { |
2617 | if (++unmapped <= khugepaged_max_ptes_swap) { | |
2618 | continue; | |
2619 | } else { | |
2620 | result = SCAN_EXCEED_SWAP_PTE; | |
2621 | goto out_unmap; | |
2622 | } | |
2623 | } | |
ca0984ca | 2624 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
c1294d05 | 2625 | if (!userfaultfd_armed(vma) && |
7d2eba05 | 2626 | ++none_or_zero <= khugepaged_max_ptes_none) { |
ba76149f | 2627 | continue; |
7d2eba05 EA |
2628 | } else { |
2629 | result = SCAN_EXCEED_NONE_PTE; | |
ba76149f | 2630 | goto out_unmap; |
7d2eba05 | 2631 | } |
ba76149f | 2632 | } |
7d2eba05 EA |
2633 | if (!pte_present(pteval)) { |
2634 | result = SCAN_PTE_NON_PRESENT; | |
ba76149f | 2635 | goto out_unmap; |
7d2eba05 | 2636 | } |
10359213 EA |
2637 | if (pte_write(pteval)) |
2638 | writable = true; | |
2639 | ||
ba76149f | 2640 | page = vm_normal_page(vma, _address, pteval); |
7d2eba05 EA |
2641 | if (unlikely(!page)) { |
2642 | result = SCAN_PAGE_NULL; | |
ba76149f | 2643 | goto out_unmap; |
7d2eba05 | 2644 | } |
b1caa957 KS |
2645 | |
2646 | /* TODO: teach khugepaged to collapse THP mapped with pte */ | |
2647 | if (PageCompound(page)) { | |
2648 | result = SCAN_PAGE_COMPOUND; | |
2649 | goto out_unmap; | |
2650 | } | |
2651 | ||
5c4b4be3 | 2652 | /* |
9f1b868a BL |
2653 | * Record which node the original page is from and save this |
2654 | * information to khugepaged_node_load[]. | |
2655 | * Khupaged will allocate hugepage from the node has the max | |
2656 | * hit record. | |
5c4b4be3 | 2657 | */ |
9f1b868a | 2658 | node = page_to_nid(page); |
7d2eba05 EA |
2659 | if (khugepaged_scan_abort(node)) { |
2660 | result = SCAN_SCAN_ABORT; | |
14a4e214 | 2661 | goto out_unmap; |
7d2eba05 | 2662 | } |
9f1b868a | 2663 | khugepaged_node_load[node]++; |
7d2eba05 | 2664 | if (!PageLRU(page)) { |
0fda2788 | 2665 | result = SCAN_PAGE_LRU; |
7d2eba05 EA |
2666 | goto out_unmap; |
2667 | } | |
2668 | if (PageLocked(page)) { | |
2669 | result = SCAN_PAGE_LOCK; | |
ba76149f | 2670 | goto out_unmap; |
7d2eba05 EA |
2671 | } |
2672 | if (!PageAnon(page)) { | |
2673 | result = SCAN_PAGE_ANON; | |
2674 | goto out_unmap; | |
2675 | } | |
2676 | ||
10359213 EA |
2677 | /* |
2678 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2679 | * The page must only be referenced by the scanned process | |
2680 | * and page swap cache. | |
2681 | */ | |
7d2eba05 EA |
2682 | if (page_count(page) != 1 + !!PageSwapCache(page)) { |
2683 | result = SCAN_PAGE_COUNT; | |
ba76149f | 2684 | goto out_unmap; |
7d2eba05 | 2685 | } |
33c3fc71 VD |
2686 | if (pte_young(pteval) || |
2687 | page_is_young(page) || PageReferenced(page) || | |
8ee53820 | 2688 | mmu_notifier_test_young(vma->vm_mm, address)) |
10359213 | 2689 | referenced = true; |
ba76149f | 2690 | } |
7d2eba05 EA |
2691 | if (writable) { |
2692 | if (referenced) { | |
2693 | result = SCAN_SUCCEED; | |
2694 | ret = 1; | |
2695 | } else { | |
2696 | result = SCAN_NO_REFERENCED_PAGE; | |
2697 | } | |
2698 | } else { | |
2699 | result = SCAN_PAGE_RO; | |
2700 | } | |
ba76149f AA |
2701 | out_unmap: |
2702 | pte_unmap_unlock(pte, ptl); | |
9f1b868a BL |
2703 | if (ret) { |
2704 | node = khugepaged_find_target_node(); | |
ce83d217 | 2705 | /* collapse_huge_page will return with the mmap_sem released */ |
5c4b4be3 | 2706 | collapse_huge_page(mm, address, hpage, vma, node); |
9f1b868a | 2707 | } |
ba76149f | 2708 | out: |
16fd0fe4 | 2709 | trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, |
70652f6e | 2710 | none_or_zero, result, unmapped); |
ba76149f AA |
2711 | return ret; |
2712 | } | |
2713 | ||
2714 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
2715 | { | |
2716 | struct mm_struct *mm = mm_slot->mm; | |
2717 | ||
b9980cdc | 2718 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2719 | |
2720 | if (khugepaged_test_exit(mm)) { | |
2721 | /* free mm_slot */ | |
43b5fbbd | 2722 | hash_del(&mm_slot->hash); |
ba76149f AA |
2723 | list_del(&mm_slot->mm_node); |
2724 | ||
2725 | /* | |
2726 | * Not strictly needed because the mm exited already. | |
2727 | * | |
2728 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
2729 | */ | |
2730 | ||
2731 | /* khugepaged_mm_lock actually not necessary for the below */ | |
2732 | free_mm_slot(mm_slot); | |
2733 | mmdrop(mm); | |
2734 | } | |
2735 | } | |
2736 | ||
2737 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
2738 | struct page **hpage) | |
2f1da642 HS |
2739 | __releases(&khugepaged_mm_lock) |
2740 | __acquires(&khugepaged_mm_lock) | |
ba76149f AA |
2741 | { |
2742 | struct mm_slot *mm_slot; | |
2743 | struct mm_struct *mm; | |
2744 | struct vm_area_struct *vma; | |
2745 | int progress = 0; | |
2746 | ||
2747 | VM_BUG_ON(!pages); | |
b9980cdc | 2748 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2749 | |
2750 | if (khugepaged_scan.mm_slot) | |
2751 | mm_slot = khugepaged_scan.mm_slot; | |
2752 | else { | |
2753 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2754 | struct mm_slot, mm_node); | |
2755 | khugepaged_scan.address = 0; | |
2756 | khugepaged_scan.mm_slot = mm_slot; | |
2757 | } | |
2758 | spin_unlock(&khugepaged_mm_lock); | |
2759 | ||
2760 | mm = mm_slot->mm; | |
2761 | down_read(&mm->mmap_sem); | |
2762 | if (unlikely(khugepaged_test_exit(mm))) | |
2763 | vma = NULL; | |
2764 | else | |
2765 | vma = find_vma(mm, khugepaged_scan.address); | |
2766 | ||
2767 | progress++; | |
2768 | for (; vma; vma = vma->vm_next) { | |
2769 | unsigned long hstart, hend; | |
2770 | ||
2771 | cond_resched(); | |
2772 | if (unlikely(khugepaged_test_exit(mm))) { | |
2773 | progress++; | |
2774 | break; | |
2775 | } | |
fa475e51 BL |
2776 | if (!hugepage_vma_check(vma)) { |
2777 | skip: | |
ba76149f AA |
2778 | progress++; |
2779 | continue; | |
2780 | } | |
ba76149f AA |
2781 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2782 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
a7d6e4ec AA |
2783 | if (hstart >= hend) |
2784 | goto skip; | |
2785 | if (khugepaged_scan.address > hend) | |
2786 | goto skip; | |
ba76149f AA |
2787 | if (khugepaged_scan.address < hstart) |
2788 | khugepaged_scan.address = hstart; | |
a7d6e4ec | 2789 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); |
ba76149f AA |
2790 | |
2791 | while (khugepaged_scan.address < hend) { | |
2792 | int ret; | |
2793 | cond_resched(); | |
2794 | if (unlikely(khugepaged_test_exit(mm))) | |
2795 | goto breakouterloop; | |
2796 | ||
2797 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2798 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2799 | hend); | |
2800 | ret = khugepaged_scan_pmd(mm, vma, | |
2801 | khugepaged_scan.address, | |
2802 | hpage); | |
2803 | /* move to next address */ | |
2804 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2805 | progress += HPAGE_PMD_NR; | |
2806 | if (ret) | |
2807 | /* we released mmap_sem so break loop */ | |
2808 | goto breakouterloop_mmap_sem; | |
2809 | if (progress >= pages) | |
2810 | goto breakouterloop; | |
2811 | } | |
2812 | } | |
2813 | breakouterloop: | |
2814 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2815 | breakouterloop_mmap_sem: | |
2816 | ||
2817 | spin_lock(&khugepaged_mm_lock); | |
a7d6e4ec | 2818 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); |
ba76149f AA |
2819 | /* |
2820 | * Release the current mm_slot if this mm is about to die, or | |
2821 | * if we scanned all vmas of this mm. | |
2822 | */ | |
2823 | if (khugepaged_test_exit(mm) || !vma) { | |
2824 | /* | |
2825 | * Make sure that if mm_users is reaching zero while | |
2826 | * khugepaged runs here, khugepaged_exit will find | |
2827 | * mm_slot not pointing to the exiting mm. | |
2828 | */ | |
2829 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2830 | khugepaged_scan.mm_slot = list_entry( | |
2831 | mm_slot->mm_node.next, | |
2832 | struct mm_slot, mm_node); | |
2833 | khugepaged_scan.address = 0; | |
2834 | } else { | |
2835 | khugepaged_scan.mm_slot = NULL; | |
2836 | khugepaged_full_scans++; | |
2837 | } | |
2838 | ||
2839 | collect_mm_slot(mm_slot); | |
2840 | } | |
2841 | ||
2842 | return progress; | |
2843 | } | |
2844 | ||
2845 | static int khugepaged_has_work(void) | |
2846 | { | |
2847 | return !list_empty(&khugepaged_scan.mm_head) && | |
2848 | khugepaged_enabled(); | |
2849 | } | |
2850 | ||
2851 | static int khugepaged_wait_event(void) | |
2852 | { | |
2853 | return !list_empty(&khugepaged_scan.mm_head) || | |
2017c0bf | 2854 | kthread_should_stop(); |
ba76149f AA |
2855 | } |
2856 | ||
d516904b | 2857 | static void khugepaged_do_scan(void) |
ba76149f | 2858 | { |
d516904b | 2859 | struct page *hpage = NULL; |
ba76149f AA |
2860 | unsigned int progress = 0, pass_through_head = 0; |
2861 | unsigned int pages = khugepaged_pages_to_scan; | |
d516904b | 2862 | bool wait = true; |
ba76149f AA |
2863 | |
2864 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2865 | ||
2866 | while (progress < pages) { | |
26234f36 | 2867 | if (!khugepaged_prealloc_page(&hpage, &wait)) |
d516904b | 2868 | break; |
26234f36 | 2869 | |
420256ef | 2870 | cond_resched(); |
ba76149f | 2871 | |
cd092411 | 2872 | if (unlikely(kthread_should_stop() || try_to_freeze())) |
878aee7d AA |
2873 | break; |
2874 | ||
ba76149f AA |
2875 | spin_lock(&khugepaged_mm_lock); |
2876 | if (!khugepaged_scan.mm_slot) | |
2877 | pass_through_head++; | |
2878 | if (khugepaged_has_work() && | |
2879 | pass_through_head < 2) | |
2880 | progress += khugepaged_scan_mm_slot(pages - progress, | |
d516904b | 2881 | &hpage); |
ba76149f AA |
2882 | else |
2883 | progress = pages; | |
2884 | spin_unlock(&khugepaged_mm_lock); | |
2885 | } | |
ba76149f | 2886 | |
d516904b XG |
2887 | if (!IS_ERR_OR_NULL(hpage)) |
2888 | put_page(hpage); | |
0bbbc0b3 AA |
2889 | } |
2890 | ||
f0508977 DR |
2891 | static bool khugepaged_should_wakeup(void) |
2892 | { | |
2893 | return kthread_should_stop() || | |
2894 | time_after_eq(jiffies, khugepaged_sleep_expire); | |
2895 | } | |
2896 | ||
2017c0bf XG |
2897 | static void khugepaged_wait_work(void) |
2898 | { | |
2017c0bf | 2899 | if (khugepaged_has_work()) { |
f0508977 DR |
2900 | const unsigned long scan_sleep_jiffies = |
2901 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs); | |
2902 | ||
2903 | if (!scan_sleep_jiffies) | |
2017c0bf XG |
2904 | return; |
2905 | ||
f0508977 | 2906 | khugepaged_sleep_expire = jiffies + scan_sleep_jiffies; |
2017c0bf | 2907 | wait_event_freezable_timeout(khugepaged_wait, |
f0508977 DR |
2908 | khugepaged_should_wakeup(), |
2909 | scan_sleep_jiffies); | |
2017c0bf XG |
2910 | return; |
2911 | } | |
2912 | ||
2913 | if (khugepaged_enabled()) | |
2914 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2915 | } | |
2916 | ||
ba76149f AA |
2917 | static int khugepaged(void *none) |
2918 | { | |
2919 | struct mm_slot *mm_slot; | |
2920 | ||
878aee7d | 2921 | set_freezable(); |
8698a745 | 2922 | set_user_nice(current, MAX_NICE); |
ba76149f | 2923 | |
b7231789 XG |
2924 | while (!kthread_should_stop()) { |
2925 | khugepaged_do_scan(); | |
2926 | khugepaged_wait_work(); | |
2927 | } | |
ba76149f AA |
2928 | |
2929 | spin_lock(&khugepaged_mm_lock); | |
2930 | mm_slot = khugepaged_scan.mm_slot; | |
2931 | khugepaged_scan.mm_slot = NULL; | |
2932 | if (mm_slot) | |
2933 | collect_mm_slot(mm_slot); | |
2934 | spin_unlock(&khugepaged_mm_lock); | |
ba76149f AA |
2935 | return 0; |
2936 | } | |
2937 | ||
eef1b3ba KS |
2938 | static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, |
2939 | unsigned long haddr, pmd_t *pmd) | |
2940 | { | |
2941 | struct mm_struct *mm = vma->vm_mm; | |
2942 | pgtable_t pgtable; | |
2943 | pmd_t _pmd; | |
2944 | int i; | |
2945 | ||
2946 | /* leave pmd empty until pte is filled */ | |
2947 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
2948 | ||
2949 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); | |
2950 | pmd_populate(mm, &_pmd, pgtable); | |
2951 | ||
2952 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
2953 | pte_t *pte, entry; | |
2954 | entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); | |
2955 | entry = pte_mkspecial(entry); | |
2956 | pte = pte_offset_map(&_pmd, haddr); | |
2957 | VM_BUG_ON(!pte_none(*pte)); | |
2958 | set_pte_at(mm, haddr, pte, entry); | |
2959 | pte_unmap(pte); | |
2960 | } | |
2961 | smp_wmb(); /* make pte visible before pmd */ | |
2962 | pmd_populate(mm, pmd, pgtable); | |
2963 | put_huge_zero_page(); | |
2964 | } | |
2965 | ||
2966 | static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, | |
ba988280 | 2967 | unsigned long haddr, bool freeze) |
eef1b3ba KS |
2968 | { |
2969 | struct mm_struct *mm = vma->vm_mm; | |
2970 | struct page *page; | |
2971 | pgtable_t pgtable; | |
2972 | pmd_t _pmd; | |
b8d3c4c3 | 2973 | bool young, write, dirty; |
2ac015e2 | 2974 | unsigned long addr; |
eef1b3ba KS |
2975 | int i; |
2976 | ||
2977 | VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); | |
2978 | VM_BUG_ON_VMA(vma->vm_start > haddr, vma); | |
2979 | VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); | |
5c7fb56e | 2980 | VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)); |
eef1b3ba KS |
2981 | |
2982 | count_vm_event(THP_SPLIT_PMD); | |
2983 | ||
2984 | if (vma_is_dax(vma)) { | |
2985 | pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
2986 | if (is_huge_zero_pmd(_pmd)) | |
2987 | put_huge_zero_page(); | |
2988 | return; | |
2989 | } else if (is_huge_zero_pmd(*pmd)) { | |
2990 | return __split_huge_zero_page_pmd(vma, haddr, pmd); | |
2991 | } | |
2992 | ||
2993 | page = pmd_page(*pmd); | |
2994 | VM_BUG_ON_PAGE(!page_count(page), page); | |
fe896d18 | 2995 | page_ref_add(page, HPAGE_PMD_NR - 1); |
eef1b3ba KS |
2996 | write = pmd_write(*pmd); |
2997 | young = pmd_young(*pmd); | |
b8d3c4c3 | 2998 | dirty = pmd_dirty(*pmd); |
eef1b3ba | 2999 | |
c777e2a8 | 3000 | pmdp_huge_split_prepare(vma, haddr, pmd); |
eef1b3ba KS |
3001 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
3002 | pmd_populate(mm, &_pmd, pgtable); | |
3003 | ||
2ac015e2 | 3004 | for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { |
eef1b3ba KS |
3005 | pte_t entry, *pte; |
3006 | /* | |
3007 | * Note that NUMA hinting access restrictions are not | |
3008 | * transferred to avoid any possibility of altering | |
3009 | * permissions across VMAs. | |
3010 | */ | |
ba988280 KS |
3011 | if (freeze) { |
3012 | swp_entry_t swp_entry; | |
3013 | swp_entry = make_migration_entry(page + i, write); | |
3014 | entry = swp_entry_to_pte(swp_entry); | |
3015 | } else { | |
3016 | entry = mk_pte(page + i, vma->vm_page_prot); | |
b8d3c4c3 | 3017 | entry = maybe_mkwrite(entry, vma); |
ba988280 KS |
3018 | if (!write) |
3019 | entry = pte_wrprotect(entry); | |
3020 | if (!young) | |
3021 | entry = pte_mkold(entry); | |
3022 | } | |
b8d3c4c3 MK |
3023 | if (dirty) |
3024 | SetPageDirty(page + i); | |
2ac015e2 | 3025 | pte = pte_offset_map(&_pmd, addr); |
eef1b3ba | 3026 | BUG_ON(!pte_none(*pte)); |
2ac015e2 | 3027 | set_pte_at(mm, addr, pte, entry); |
eef1b3ba KS |
3028 | atomic_inc(&page[i]._mapcount); |
3029 | pte_unmap(pte); | |
3030 | } | |
3031 | ||
3032 | /* | |
3033 | * Set PG_double_map before dropping compound_mapcount to avoid | |
3034 | * false-negative page_mapped(). | |
3035 | */ | |
3036 | if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { | |
3037 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
3038 | atomic_inc(&page[i]._mapcount); | |
3039 | } | |
3040 | ||
3041 | if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { | |
3042 | /* Last compound_mapcount is gone. */ | |
3043 | __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); | |
3044 | if (TestClearPageDoubleMap(page)) { | |
3045 | /* No need in mapcount reference anymore */ | |
3046 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
3047 | atomic_dec(&page[i]._mapcount); | |
3048 | } | |
3049 | } | |
3050 | ||
3051 | smp_wmb(); /* make pte visible before pmd */ | |
e9b61f19 KS |
3052 | /* |
3053 | * Up to this point the pmd is present and huge and userland has the | |
3054 | * whole access to the hugepage during the split (which happens in | |
3055 | * place). If we overwrite the pmd with the not-huge version pointing | |
3056 | * to the pte here (which of course we could if all CPUs were bug | |
3057 | * free), userland could trigger a small page size TLB miss on the | |
3058 | * small sized TLB while the hugepage TLB entry is still established in | |
3059 | * the huge TLB. Some CPU doesn't like that. | |
3060 | * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum | |
3061 | * 383 on page 93. Intel should be safe but is also warns that it's | |
3062 | * only safe if the permission and cache attributes of the two entries | |
3063 | * loaded in the two TLB is identical (which should be the case here). | |
3064 | * But it is generally safer to never allow small and huge TLB entries | |
3065 | * for the same virtual address to be loaded simultaneously. So instead | |
3066 | * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the | |
3067 | * current pmd notpresent (atomically because here the pmd_trans_huge | |
3068 | * and pmd_trans_splitting must remain set at all times on the pmd | |
3069 | * until the split is complete for this pmd), then we flush the SMP TLB | |
3070 | * and finally we write the non-huge version of the pmd entry with | |
3071 | * pmd_populate. | |
3072 | */ | |
3073 | pmdp_invalidate(vma, haddr, pmd); | |
eef1b3ba | 3074 | pmd_populate(mm, pmd, pgtable); |
e9b61f19 KS |
3075 | |
3076 | if (freeze) { | |
2ac015e2 | 3077 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
e9b61f19 KS |
3078 | page_remove_rmap(page + i, false); |
3079 | put_page(page + i); | |
3080 | } | |
3081 | } | |
eef1b3ba KS |
3082 | } |
3083 | ||
3084 | void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, | |
33f4751e | 3085 | unsigned long address, bool freeze, struct page *page) |
eef1b3ba KS |
3086 | { |
3087 | spinlock_t *ptl; | |
3088 | struct mm_struct *mm = vma->vm_mm; | |
3089 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
3090 | ||
3091 | mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE); | |
3092 | ptl = pmd_lock(mm, pmd); | |
33f4751e NH |
3093 | |
3094 | /* | |
3095 | * If caller asks to setup a migration entries, we need a page to check | |
3096 | * pmd against. Otherwise we can end up replacing wrong page. | |
3097 | */ | |
3098 | VM_BUG_ON(freeze && !page); | |
3099 | if (page && page != pmd_page(*pmd)) | |
3100 | goto out; | |
3101 | ||
5c7fb56e | 3102 | if (pmd_trans_huge(*pmd)) { |
33f4751e | 3103 | page = pmd_page(*pmd); |
5c7fb56e | 3104 | if (PageMlocked(page)) |
5f737714 | 3105 | clear_page_mlock(page); |
5c7fb56e | 3106 | } else if (!pmd_devmap(*pmd)) |
e90309c9 | 3107 | goto out; |
fec89c10 | 3108 | __split_huge_pmd_locked(vma, pmd, haddr, freeze); |
e90309c9 | 3109 | out: |
eef1b3ba KS |
3110 | spin_unlock(ptl); |
3111 | mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE); | |
3112 | } | |
3113 | ||
fec89c10 KS |
3114 | void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, |
3115 | bool freeze, struct page *page) | |
94fcc585 | 3116 | { |
f72e7dcd HD |
3117 | pgd_t *pgd; |
3118 | pud_t *pud; | |
94fcc585 AA |
3119 | pmd_t *pmd; |
3120 | ||
78ddc534 | 3121 | pgd = pgd_offset(vma->vm_mm, address); |
f72e7dcd HD |
3122 | if (!pgd_present(*pgd)) |
3123 | return; | |
3124 | ||
3125 | pud = pud_offset(pgd, address); | |
3126 | if (!pud_present(*pud)) | |
3127 | return; | |
3128 | ||
3129 | pmd = pmd_offset(pud, address); | |
fec89c10 | 3130 | |
33f4751e | 3131 | __split_huge_pmd(vma, pmd, address, freeze, page); |
94fcc585 AA |
3132 | } |
3133 | ||
e1b9996b | 3134 | void vma_adjust_trans_huge(struct vm_area_struct *vma, |
94fcc585 AA |
3135 | unsigned long start, |
3136 | unsigned long end, | |
3137 | long adjust_next) | |
3138 | { | |
3139 | /* | |
3140 | * If the new start address isn't hpage aligned and it could | |
3141 | * previously contain an hugepage: check if we need to split | |
3142 | * an huge pmd. | |
3143 | */ | |
3144 | if (start & ~HPAGE_PMD_MASK && | |
3145 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
3146 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
fec89c10 | 3147 | split_huge_pmd_address(vma, start, false, NULL); |
94fcc585 AA |
3148 | |
3149 | /* | |
3150 | * If the new end address isn't hpage aligned and it could | |
3151 | * previously contain an hugepage: check if we need to split | |
3152 | * an huge pmd. | |
3153 | */ | |
3154 | if (end & ~HPAGE_PMD_MASK && | |
3155 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
3156 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
fec89c10 | 3157 | split_huge_pmd_address(vma, end, false, NULL); |
94fcc585 AA |
3158 | |
3159 | /* | |
3160 | * If we're also updating the vma->vm_next->vm_start, if the new | |
3161 | * vm_next->vm_start isn't page aligned and it could previously | |
3162 | * contain an hugepage: check if we need to split an huge pmd. | |
3163 | */ | |
3164 | if (adjust_next > 0) { | |
3165 | struct vm_area_struct *next = vma->vm_next; | |
3166 | unsigned long nstart = next->vm_start; | |
3167 | nstart += adjust_next << PAGE_SHIFT; | |
3168 | if (nstart & ~HPAGE_PMD_MASK && | |
3169 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
3170 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
fec89c10 | 3171 | split_huge_pmd_address(next, nstart, false, NULL); |
94fcc585 AA |
3172 | } |
3173 | } | |
e9b61f19 | 3174 | |
fec89c10 | 3175 | static void freeze_page(struct page *page) |
e9b61f19 | 3176 | { |
fec89c10 KS |
3177 | enum ttu_flags ttu_flags = TTU_MIGRATION | TTU_IGNORE_MLOCK | |
3178 | TTU_IGNORE_ACCESS | TTU_RMAP_LOCKED; | |
3179 | int i, ret; | |
e9b61f19 KS |
3180 | |
3181 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
3182 | ||
fec89c10 KS |
3183 | /* We only need TTU_SPLIT_HUGE_PMD once */ |
3184 | ret = try_to_unmap(page, ttu_flags | TTU_SPLIT_HUGE_PMD); | |
3185 | for (i = 1; !ret && i < HPAGE_PMD_NR; i++) { | |
3186 | /* Cut short if the page is unmapped */ | |
3187 | if (page_count(page) == 1) | |
3188 | return; | |
e9b61f19 | 3189 | |
fec89c10 | 3190 | ret = try_to_unmap(page + i, ttu_flags); |
e9b61f19 | 3191 | } |
fec89c10 | 3192 | VM_BUG_ON(ret); |
e9b61f19 KS |
3193 | } |
3194 | ||
fec89c10 | 3195 | static void unfreeze_page(struct page *page) |
e9b61f19 | 3196 | { |
fec89c10 | 3197 | int i; |
e9b61f19 | 3198 | |
fec89c10 KS |
3199 | for (i = 0; i < HPAGE_PMD_NR; i++) |
3200 | remove_migration_ptes(page + i, page + i, true); | |
e9b61f19 KS |
3201 | } |
3202 | ||
8df651c7 | 3203 | static void __split_huge_page_tail(struct page *head, int tail, |
e9b61f19 KS |
3204 | struct lruvec *lruvec, struct list_head *list) |
3205 | { | |
e9b61f19 KS |
3206 | struct page *page_tail = head + tail; |
3207 | ||
8df651c7 | 3208 | VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); |
fe896d18 | 3209 | VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail); |
e9b61f19 KS |
3210 | |
3211 | /* | |
0139aa7b | 3212 | * tail_page->_refcount is zero and not changing from under us. But |
e9b61f19 | 3213 | * get_page_unless_zero() may be running from under us on the |
8df651c7 | 3214 | * tail_page. If we used atomic_set() below instead of atomic_inc(), we |
e9b61f19 KS |
3215 | * would then run atomic_set() concurrently with |
3216 | * get_page_unless_zero(), and atomic_set() is implemented in C not | |
3217 | * using locked ops. spin_unlock on x86 sometime uses locked ops | |
3218 | * because of PPro errata 66, 92, so unless somebody can guarantee | |
3219 | * atomic_set() here would be safe on all archs (and not only on x86), | |
8df651c7 | 3220 | * it's safer to use atomic_inc(). |
e9b61f19 | 3221 | */ |
fe896d18 | 3222 | page_ref_inc(page_tail); |
e9b61f19 KS |
3223 | |
3224 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; | |
3225 | page_tail->flags |= (head->flags & | |
3226 | ((1L << PG_referenced) | | |
3227 | (1L << PG_swapbacked) | | |
3228 | (1L << PG_mlocked) | | |
3229 | (1L << PG_uptodate) | | |
3230 | (1L << PG_active) | | |
3231 | (1L << PG_locked) | | |
b8d3c4c3 MK |
3232 | (1L << PG_unevictable) | |
3233 | (1L << PG_dirty))); | |
e9b61f19 KS |
3234 | |
3235 | /* | |
3236 | * After clearing PageTail the gup refcount can be released. | |
3237 | * Page flags also must be visible before we make the page non-compound. | |
3238 | */ | |
3239 | smp_wmb(); | |
3240 | ||
3241 | clear_compound_head(page_tail); | |
3242 | ||
3243 | if (page_is_young(head)) | |
3244 | set_page_young(page_tail); | |
3245 | if (page_is_idle(head)) | |
3246 | set_page_idle(page_tail); | |
3247 | ||
3248 | /* ->mapping in first tail page is compound_mapcount */ | |
9a982250 | 3249 | VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, |
e9b61f19 KS |
3250 | page_tail); |
3251 | page_tail->mapping = head->mapping; | |
3252 | ||
3253 | page_tail->index = head->index + tail; | |
3254 | page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); | |
3255 | lru_add_page_tail(head, page_tail, lruvec, list); | |
e9b61f19 KS |
3256 | } |
3257 | ||
3258 | static void __split_huge_page(struct page *page, struct list_head *list) | |
3259 | { | |
3260 | struct page *head = compound_head(page); | |
3261 | struct zone *zone = page_zone(head); | |
3262 | struct lruvec *lruvec; | |
8df651c7 | 3263 | int i; |
e9b61f19 KS |
3264 | |
3265 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
3266 | spin_lock_irq(&zone->lru_lock); | |
3267 | lruvec = mem_cgroup_page_lruvec(head, zone); | |
3268 | ||
3269 | /* complete memcg works before add pages to LRU */ | |
3270 | mem_cgroup_split_huge_fixup(head); | |
3271 | ||
e9b61f19 | 3272 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) |
8df651c7 | 3273 | __split_huge_page_tail(head, i, lruvec, list); |
e9b61f19 KS |
3274 | |
3275 | ClearPageCompound(head); | |
3276 | spin_unlock_irq(&zone->lru_lock); | |
3277 | ||
fec89c10 | 3278 | unfreeze_page(head); |
e9b61f19 KS |
3279 | |
3280 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
3281 | struct page *subpage = head + i; | |
3282 | if (subpage == page) | |
3283 | continue; | |
3284 | unlock_page(subpage); | |
3285 | ||
3286 | /* | |
3287 | * Subpages may be freed if there wasn't any mapping | |
3288 | * like if add_to_swap() is running on a lru page that | |
3289 | * had its mapping zapped. And freeing these pages | |
3290 | * requires taking the lru_lock so we do the put_page | |
3291 | * of the tail pages after the split is complete. | |
3292 | */ | |
3293 | put_page(subpage); | |
3294 | } | |
3295 | } | |
3296 | ||
b20ce5e0 KS |
3297 | int total_mapcount(struct page *page) |
3298 | { | |
dd78fedd | 3299 | int i, compound, ret; |
b20ce5e0 KS |
3300 | |
3301 | VM_BUG_ON_PAGE(PageTail(page), page); | |
3302 | ||
3303 | if (likely(!PageCompound(page))) | |
3304 | return atomic_read(&page->_mapcount) + 1; | |
3305 | ||
dd78fedd | 3306 | compound = compound_mapcount(page); |
b20ce5e0 | 3307 | if (PageHuge(page)) |
dd78fedd KS |
3308 | return compound; |
3309 | ret = compound; | |
b20ce5e0 KS |
3310 | for (i = 0; i < HPAGE_PMD_NR; i++) |
3311 | ret += atomic_read(&page[i]._mapcount) + 1; | |
dd78fedd KS |
3312 | /* File pages has compound_mapcount included in _mapcount */ |
3313 | if (!PageAnon(page)) | |
3314 | return ret - compound * HPAGE_PMD_NR; | |
b20ce5e0 KS |
3315 | if (PageDoubleMap(page)) |
3316 | ret -= HPAGE_PMD_NR; | |
3317 | return ret; | |
3318 | } | |
3319 | ||
6d0a07ed AA |
3320 | /* |
3321 | * This calculates accurately how many mappings a transparent hugepage | |
3322 | * has (unlike page_mapcount() which isn't fully accurate). This full | |
3323 | * accuracy is primarily needed to know if copy-on-write faults can | |
3324 | * reuse the page and change the mapping to read-write instead of | |
3325 | * copying them. At the same time this returns the total_mapcount too. | |
3326 | * | |
3327 | * The function returns the highest mapcount any one of the subpages | |
3328 | * has. If the return value is one, even if different processes are | |
3329 | * mapping different subpages of the transparent hugepage, they can | |
3330 | * all reuse it, because each process is reusing a different subpage. | |
3331 | * | |
3332 | * The total_mapcount is instead counting all virtual mappings of the | |
3333 | * subpages. If the total_mapcount is equal to "one", it tells the | |
3334 | * caller all mappings belong to the same "mm" and in turn the | |
3335 | * anon_vma of the transparent hugepage can become the vma->anon_vma | |
3336 | * local one as no other process may be mapping any of the subpages. | |
3337 | * | |
3338 | * It would be more accurate to replace page_mapcount() with | |
3339 | * page_trans_huge_mapcount(), however we only use | |
3340 | * page_trans_huge_mapcount() in the copy-on-write faults where we | |
3341 | * need full accuracy to avoid breaking page pinning, because | |
3342 | * page_trans_huge_mapcount() is slower than page_mapcount(). | |
3343 | */ | |
3344 | int page_trans_huge_mapcount(struct page *page, int *total_mapcount) | |
3345 | { | |
3346 | int i, ret, _total_mapcount, mapcount; | |
3347 | ||
3348 | /* hugetlbfs shouldn't call it */ | |
3349 | VM_BUG_ON_PAGE(PageHuge(page), page); | |
3350 | ||
3351 | if (likely(!PageTransCompound(page))) { | |
3352 | mapcount = atomic_read(&page->_mapcount) + 1; | |
3353 | if (total_mapcount) | |
3354 | *total_mapcount = mapcount; | |
3355 | return mapcount; | |
3356 | } | |
3357 | ||
3358 | page = compound_head(page); | |
3359 | ||
3360 | _total_mapcount = ret = 0; | |
3361 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
3362 | mapcount = atomic_read(&page[i]._mapcount) + 1; | |
3363 | ret = max(ret, mapcount); | |
3364 | _total_mapcount += mapcount; | |
3365 | } | |
3366 | if (PageDoubleMap(page)) { | |
3367 | ret -= 1; | |
3368 | _total_mapcount -= HPAGE_PMD_NR; | |
3369 | } | |
3370 | mapcount = compound_mapcount(page); | |
3371 | ret += mapcount; | |
3372 | _total_mapcount += mapcount; | |
3373 | if (total_mapcount) | |
3374 | *total_mapcount = _total_mapcount; | |
3375 | return ret; | |
3376 | } | |
3377 | ||
e9b61f19 KS |
3378 | /* |
3379 | * This function splits huge page into normal pages. @page can point to any | |
3380 | * subpage of huge page to split. Split doesn't change the position of @page. | |
3381 | * | |
3382 | * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. | |
3383 | * The huge page must be locked. | |
3384 | * | |
3385 | * If @list is null, tail pages will be added to LRU list, otherwise, to @list. | |
3386 | * | |
3387 | * Both head page and tail pages will inherit mapping, flags, and so on from | |
3388 | * the hugepage. | |
3389 | * | |
3390 | * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if | |
3391 | * they are not mapped. | |
3392 | * | |
3393 | * Returns 0 if the hugepage is split successfully. | |
3394 | * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under | |
3395 | * us. | |
3396 | */ | |
3397 | int split_huge_page_to_list(struct page *page, struct list_head *list) | |
3398 | { | |
3399 | struct page *head = compound_head(page); | |
a3d0a918 | 3400 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); |
e9b61f19 KS |
3401 | struct anon_vma *anon_vma; |
3402 | int count, mapcount, ret; | |
d9654322 | 3403 | bool mlocked; |
0b9b6fff | 3404 | unsigned long flags; |
e9b61f19 KS |
3405 | |
3406 | VM_BUG_ON_PAGE(is_huge_zero_page(page), page); | |
3407 | VM_BUG_ON_PAGE(!PageAnon(page), page); | |
3408 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
3409 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
3410 | VM_BUG_ON_PAGE(!PageCompound(page), page); | |
3411 | ||
3412 | /* | |
3413 | * The caller does not necessarily hold an mmap_sem that would prevent | |
3414 | * the anon_vma disappearing so we first we take a reference to it | |
3415 | * and then lock the anon_vma for write. This is similar to | |
3416 | * page_lock_anon_vma_read except the write lock is taken to serialise | |
3417 | * against parallel split or collapse operations. | |
3418 | */ | |
3419 | anon_vma = page_get_anon_vma(head); | |
3420 | if (!anon_vma) { | |
3421 | ret = -EBUSY; | |
3422 | goto out; | |
3423 | } | |
3424 | anon_vma_lock_write(anon_vma); | |
3425 | ||
3426 | /* | |
3427 | * Racy check if we can split the page, before freeze_page() will | |
3428 | * split PMDs | |
3429 | */ | |
3430 | if (total_mapcount(head) != page_count(head) - 1) { | |
3431 | ret = -EBUSY; | |
3432 | goto out_unlock; | |
3433 | } | |
3434 | ||
d9654322 | 3435 | mlocked = PageMlocked(page); |
fec89c10 | 3436 | freeze_page(head); |
e9b61f19 KS |
3437 | VM_BUG_ON_PAGE(compound_mapcount(head), head); |
3438 | ||
d9654322 KS |
3439 | /* Make sure the page is not on per-CPU pagevec as it takes pin */ |
3440 | if (mlocked) | |
3441 | lru_add_drain(); | |
3442 | ||
0139aa7b | 3443 | /* Prevent deferred_split_scan() touching ->_refcount */ |
a3d0a918 | 3444 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
e9b61f19 KS |
3445 | count = page_count(head); |
3446 | mapcount = total_mapcount(head); | |
bd56086f | 3447 | if (!mapcount && count == 1) { |
9a982250 | 3448 | if (!list_empty(page_deferred_list(head))) { |
a3d0a918 | 3449 | pgdata->split_queue_len--; |
9a982250 KS |
3450 | list_del(page_deferred_list(head)); |
3451 | } | |
a3d0a918 | 3452 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
e9b61f19 KS |
3453 | __split_huge_page(page, list); |
3454 | ret = 0; | |
bd56086f | 3455 | } else if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { |
a3d0a918 | 3456 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
e9b61f19 KS |
3457 | pr_alert("total_mapcount: %u, page_count(): %u\n", |
3458 | mapcount, count); | |
3459 | if (PageTail(page)) | |
3460 | dump_page(head, NULL); | |
bd56086f | 3461 | dump_page(page, "total_mapcount(head) > 0"); |
e9b61f19 KS |
3462 | BUG(); |
3463 | } else { | |
a3d0a918 | 3464 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
fec89c10 | 3465 | unfreeze_page(head); |
e9b61f19 KS |
3466 | ret = -EBUSY; |
3467 | } | |
3468 | ||
3469 | out_unlock: | |
3470 | anon_vma_unlock_write(anon_vma); | |
3471 | put_anon_vma(anon_vma); | |
3472 | out: | |
3473 | count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); | |
3474 | return ret; | |
3475 | } | |
9a982250 KS |
3476 | |
3477 | void free_transhuge_page(struct page *page) | |
3478 | { | |
a3d0a918 | 3479 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); |
9a982250 KS |
3480 | unsigned long flags; |
3481 | ||
a3d0a918 | 3482 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 3483 | if (!list_empty(page_deferred_list(page))) { |
a3d0a918 | 3484 | pgdata->split_queue_len--; |
9a982250 KS |
3485 | list_del(page_deferred_list(page)); |
3486 | } | |
a3d0a918 | 3487 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
3488 | free_compound_page(page); |
3489 | } | |
3490 | ||
3491 | void deferred_split_huge_page(struct page *page) | |
3492 | { | |
a3d0a918 | 3493 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); |
9a982250 KS |
3494 | unsigned long flags; |
3495 | ||
3496 | VM_BUG_ON_PAGE(!PageTransHuge(page), page); | |
3497 | ||
a3d0a918 | 3498 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 3499 | if (list_empty(page_deferred_list(page))) { |
f9719a03 | 3500 | count_vm_event(THP_DEFERRED_SPLIT_PAGE); |
a3d0a918 KS |
3501 | list_add_tail(page_deferred_list(page), &pgdata->split_queue); |
3502 | pgdata->split_queue_len++; | |
9a982250 | 3503 | } |
a3d0a918 | 3504 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
3505 | } |
3506 | ||
3507 | static unsigned long deferred_split_count(struct shrinker *shrink, | |
3508 | struct shrink_control *sc) | |
3509 | { | |
a3d0a918 | 3510 | struct pglist_data *pgdata = NODE_DATA(sc->nid); |
cb8d68ec | 3511 | return ACCESS_ONCE(pgdata->split_queue_len); |
9a982250 KS |
3512 | } |
3513 | ||
3514 | static unsigned long deferred_split_scan(struct shrinker *shrink, | |
3515 | struct shrink_control *sc) | |
3516 | { | |
a3d0a918 | 3517 | struct pglist_data *pgdata = NODE_DATA(sc->nid); |
9a982250 KS |
3518 | unsigned long flags; |
3519 | LIST_HEAD(list), *pos, *next; | |
3520 | struct page *page; | |
3521 | int split = 0; | |
3522 | ||
a3d0a918 | 3523 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 3524 | /* Take pin on all head pages to avoid freeing them under us */ |
ae026204 | 3525 | list_for_each_safe(pos, next, &pgdata->split_queue) { |
9a982250 KS |
3526 | page = list_entry((void *)pos, struct page, mapping); |
3527 | page = compound_head(page); | |
e3ae1953 KS |
3528 | if (get_page_unless_zero(page)) { |
3529 | list_move(page_deferred_list(page), &list); | |
3530 | } else { | |
3531 | /* We lost race with put_compound_page() */ | |
9a982250 | 3532 | list_del_init(page_deferred_list(page)); |
a3d0a918 | 3533 | pgdata->split_queue_len--; |
9a982250 | 3534 | } |
e3ae1953 KS |
3535 | if (!--sc->nr_to_scan) |
3536 | break; | |
9a982250 | 3537 | } |
a3d0a918 | 3538 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
3539 | |
3540 | list_for_each_safe(pos, next, &list) { | |
3541 | page = list_entry((void *)pos, struct page, mapping); | |
3542 | lock_page(page); | |
3543 | /* split_huge_page() removes page from list on success */ | |
3544 | if (!split_huge_page(page)) | |
3545 | split++; | |
3546 | unlock_page(page); | |
3547 | put_page(page); | |
3548 | } | |
3549 | ||
a3d0a918 KS |
3550 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
3551 | list_splice_tail(&list, &pgdata->split_queue); | |
3552 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); | |
9a982250 | 3553 | |
cb8d68ec KS |
3554 | /* |
3555 | * Stop shrinker if we didn't split any page, but the queue is empty. | |
3556 | * This can happen if pages were freed under us. | |
3557 | */ | |
3558 | if (!split && list_empty(&pgdata->split_queue)) | |
3559 | return SHRINK_STOP; | |
3560 | return split; | |
9a982250 KS |
3561 | } |
3562 | ||
3563 | static struct shrinker deferred_split_shrinker = { | |
3564 | .count_objects = deferred_split_count, | |
3565 | .scan_objects = deferred_split_scan, | |
3566 | .seeks = DEFAULT_SEEKS, | |
a3d0a918 | 3567 | .flags = SHRINKER_NUMA_AWARE, |
9a982250 | 3568 | }; |
49071d43 KS |
3569 | |
3570 | #ifdef CONFIG_DEBUG_FS | |
3571 | static int split_huge_pages_set(void *data, u64 val) | |
3572 | { | |
3573 | struct zone *zone; | |
3574 | struct page *page; | |
3575 | unsigned long pfn, max_zone_pfn; | |
3576 | unsigned long total = 0, split = 0; | |
3577 | ||
3578 | if (val != 1) | |
3579 | return -EINVAL; | |
3580 | ||
3581 | for_each_populated_zone(zone) { | |
3582 | max_zone_pfn = zone_end_pfn(zone); | |
3583 | for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { | |
3584 | if (!pfn_valid(pfn)) | |
3585 | continue; | |
3586 | ||
3587 | page = pfn_to_page(pfn); | |
3588 | if (!get_page_unless_zero(page)) | |
3589 | continue; | |
3590 | ||
3591 | if (zone != page_zone(page)) | |
3592 | goto next; | |
3593 | ||
3594 | if (!PageHead(page) || !PageAnon(page) || | |
3595 | PageHuge(page)) | |
3596 | goto next; | |
3597 | ||
3598 | total++; | |
3599 | lock_page(page); | |
3600 | if (!split_huge_page(page)) | |
3601 | split++; | |
3602 | unlock_page(page); | |
3603 | next: | |
3604 | put_page(page); | |
3605 | } | |
3606 | } | |
3607 | ||
145bdaa1 | 3608 | pr_info("%lu of %lu THP split\n", split, total); |
49071d43 KS |
3609 | |
3610 | return 0; | |
3611 | } | |
3612 | DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, | |
3613 | "%llu\n"); | |
3614 | ||
3615 | static int __init split_huge_pages_debugfs(void) | |
3616 | { | |
3617 | void *ret; | |
3618 | ||
145bdaa1 | 3619 | ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL, |
49071d43 KS |
3620 | &split_huge_pages_fops); |
3621 | if (!ret) | |
3622 | pr_warn("Failed to create split_huge_pages in debugfs"); | |
3623 | return 0; | |
3624 | } | |
3625 | late_initcall(split_huge_pages_debugfs); | |
3626 | #endif |