Commit | Line | Data |
---|---|---|
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, | |
60 | SCAN_CGROUP_CHARGE_FAIL | |
61 | }; | |
62 | ||
63 | #define CREATE_TRACE_POINTS | |
64 | #include <trace/events/huge_memory.h> | |
65 | ||
ba76149f | 66 | /* |
8bfa3f9a JW |
67 | * By default transparent hugepage support is disabled in order that avoid |
68 | * to risk increase the memory footprint of applications without a guaranteed | |
69 | * benefit. When transparent hugepage support is enabled, is for all mappings, | |
70 | * and khugepaged scans all mappings. | |
71 | * Defrag is invoked by khugepaged hugepage allocations and by page faults | |
72 | * for all hugepage allocations. | |
ba76149f | 73 | */ |
71e3aac0 | 74 | unsigned long transparent_hugepage_flags __read_mostly = |
13ece886 | 75 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS |
ba76149f | 76 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| |
13ece886 AA |
77 | #endif |
78 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE | |
79 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| | |
80 | #endif | |
444eb2a4 | 81 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| |
79da5407 KS |
82 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| |
83 | (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
ba76149f AA |
84 | |
85 | /* default scan 8*512 pte (or vmas) every 30 second */ | |
ff20c2e0 | 86 | static unsigned int khugepaged_pages_to_scan __read_mostly; |
ba76149f AA |
87 | static unsigned int khugepaged_pages_collapsed; |
88 | static unsigned int khugepaged_full_scans; | |
89 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
90 | /* during fragmentation poll the hugepage allocator once every minute */ | |
91 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
f0508977 | 92 | static unsigned long khugepaged_sleep_expire; |
ba76149f AA |
93 | static struct task_struct *khugepaged_thread __read_mostly; |
94 | static DEFINE_MUTEX(khugepaged_mutex); | |
95 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
96 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
97 | /* | |
98 | * default collapse hugepages if there is at least one pte mapped like | |
99 | * it would have happened if the vma was large enough during page | |
100 | * fault. | |
101 | */ | |
ff20c2e0 | 102 | static unsigned int khugepaged_max_ptes_none __read_mostly; |
ba76149f AA |
103 | |
104 | static int khugepaged(void *none); | |
ba76149f | 105 | static int khugepaged_slab_init(void); |
65ebb64f | 106 | static void khugepaged_slab_exit(void); |
ba76149f | 107 | |
43b5fbbd SL |
108 | #define MM_SLOTS_HASH_BITS 10 |
109 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
110 | ||
ba76149f AA |
111 | static struct kmem_cache *mm_slot_cache __read_mostly; |
112 | ||
113 | /** | |
114 | * struct mm_slot - hash lookup from mm to mm_slot | |
115 | * @hash: hash collision list | |
116 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
117 | * @mm: the mm that this information is valid for | |
118 | */ | |
119 | struct mm_slot { | |
120 | struct hlist_node hash; | |
121 | struct list_head mm_node; | |
122 | struct mm_struct *mm; | |
123 | }; | |
124 | ||
125 | /** | |
126 | * struct khugepaged_scan - cursor for scanning | |
127 | * @mm_head: the head of the mm list to scan | |
128 | * @mm_slot: the current mm_slot we are scanning | |
129 | * @address: the next address inside that to be scanned | |
130 | * | |
131 | * There is only the one khugepaged_scan instance of this cursor structure. | |
132 | */ | |
133 | struct khugepaged_scan { | |
134 | struct list_head mm_head; | |
135 | struct mm_slot *mm_slot; | |
136 | unsigned long address; | |
2f1da642 HS |
137 | }; |
138 | static struct khugepaged_scan khugepaged_scan = { | |
ba76149f AA |
139 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), |
140 | }; | |
141 | ||
9a982250 | 142 | static struct shrinker deferred_split_shrinker; |
f000565a | 143 | |
2c0b80d4 | 144 | static void set_recommended_min_free_kbytes(void) |
f000565a AA |
145 | { |
146 | struct zone *zone; | |
147 | int nr_zones = 0; | |
148 | unsigned long recommended_min; | |
f000565a | 149 | |
f000565a AA |
150 | for_each_populated_zone(zone) |
151 | nr_zones++; | |
152 | ||
974a786e | 153 | /* Ensure 2 pageblocks are free to assist fragmentation avoidance */ |
f000565a AA |
154 | recommended_min = pageblock_nr_pages * nr_zones * 2; |
155 | ||
156 | /* | |
157 | * Make sure that on average at least two pageblocks are almost free | |
158 | * of another type, one for a migratetype to fall back to and a | |
159 | * second to avoid subsequent fallbacks of other types There are 3 | |
160 | * MIGRATE_TYPES we care about. | |
161 | */ | |
162 | recommended_min += pageblock_nr_pages * nr_zones * | |
163 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
164 | ||
165 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
166 | recommended_min = min(recommended_min, | |
167 | (unsigned long) nr_free_buffer_pages() / 20); | |
168 | recommended_min <<= (PAGE_SHIFT-10); | |
169 | ||
42aa83cb HP |
170 | if (recommended_min > min_free_kbytes) { |
171 | if (user_min_free_kbytes >= 0) | |
756a025f | 172 | pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n", |
42aa83cb HP |
173 | min_free_kbytes, recommended_min); |
174 | ||
f000565a | 175 | min_free_kbytes = recommended_min; |
42aa83cb | 176 | } |
f000565a | 177 | setup_per_zone_wmarks(); |
f000565a | 178 | } |
f000565a | 179 | |
79553da2 | 180 | static int start_stop_khugepaged(void) |
ba76149f AA |
181 | { |
182 | int err = 0; | |
183 | if (khugepaged_enabled()) { | |
ba76149f AA |
184 | if (!khugepaged_thread) |
185 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
186 | "khugepaged"); | |
18e8e5c7 | 187 | if (IS_ERR(khugepaged_thread)) { |
ae3a8c1c | 188 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); |
ba76149f AA |
189 | err = PTR_ERR(khugepaged_thread); |
190 | khugepaged_thread = NULL; | |
79553da2 | 191 | goto fail; |
ba76149f | 192 | } |
911891af XG |
193 | |
194 | if (!list_empty(&khugepaged_scan.mm_head)) | |
ba76149f | 195 | wake_up_interruptible(&khugepaged_wait); |
f000565a AA |
196 | |
197 | set_recommended_min_free_kbytes(); | |
911891af | 198 | } else if (khugepaged_thread) { |
911891af XG |
199 | kthread_stop(khugepaged_thread); |
200 | khugepaged_thread = NULL; | |
201 | } | |
79553da2 | 202 | fail: |
ba76149f AA |
203 | return err; |
204 | } | |
71e3aac0 | 205 | |
97ae1749 | 206 | static atomic_t huge_zero_refcount; |
56873f43 | 207 | struct page *huge_zero_page __read_mostly; |
4a6c1297 | 208 | |
fc437044 | 209 | struct page *get_huge_zero_page(void) |
97ae1749 KS |
210 | { |
211 | struct page *zero_page; | |
212 | retry: | |
213 | if (likely(atomic_inc_not_zero(&huge_zero_refcount))) | |
4db0c3c2 | 214 | return READ_ONCE(huge_zero_page); |
97ae1749 KS |
215 | |
216 | zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, | |
4a6c1297 | 217 | HPAGE_PMD_ORDER); |
d8a8e1f0 KS |
218 | if (!zero_page) { |
219 | count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); | |
5918d10a | 220 | return NULL; |
d8a8e1f0 KS |
221 | } |
222 | count_vm_event(THP_ZERO_PAGE_ALLOC); | |
97ae1749 | 223 | preempt_disable(); |
5918d10a | 224 | if (cmpxchg(&huge_zero_page, NULL, zero_page)) { |
97ae1749 | 225 | preempt_enable(); |
5ddacbe9 | 226 | __free_pages(zero_page, compound_order(zero_page)); |
97ae1749 KS |
227 | goto retry; |
228 | } | |
229 | ||
230 | /* We take additional reference here. It will be put back by shrinker */ | |
231 | atomic_set(&huge_zero_refcount, 2); | |
232 | preempt_enable(); | |
4db0c3c2 | 233 | return READ_ONCE(huge_zero_page); |
4a6c1297 KS |
234 | } |
235 | ||
aa88b68c | 236 | void put_huge_zero_page(void) |
4a6c1297 | 237 | { |
97ae1749 KS |
238 | /* |
239 | * Counter should never go to zero here. Only shrinker can put | |
240 | * last reference. | |
241 | */ | |
242 | BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); | |
4a6c1297 KS |
243 | } |
244 | ||
48896466 GC |
245 | static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, |
246 | struct shrink_control *sc) | |
4a6c1297 | 247 | { |
48896466 GC |
248 | /* we can free zero page only if last reference remains */ |
249 | return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; | |
250 | } | |
97ae1749 | 251 | |
48896466 GC |
252 | static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, |
253 | struct shrink_control *sc) | |
254 | { | |
97ae1749 | 255 | if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { |
5918d10a KS |
256 | struct page *zero_page = xchg(&huge_zero_page, NULL); |
257 | BUG_ON(zero_page == NULL); | |
5ddacbe9 | 258 | __free_pages(zero_page, compound_order(zero_page)); |
48896466 | 259 | return HPAGE_PMD_NR; |
97ae1749 KS |
260 | } |
261 | ||
262 | return 0; | |
4a6c1297 KS |
263 | } |
264 | ||
97ae1749 | 265 | static struct shrinker huge_zero_page_shrinker = { |
48896466 GC |
266 | .count_objects = shrink_huge_zero_page_count, |
267 | .scan_objects = shrink_huge_zero_page_scan, | |
97ae1749 KS |
268 | .seeks = DEFAULT_SEEKS, |
269 | }; | |
270 | ||
71e3aac0 | 271 | #ifdef CONFIG_SYSFS |
ba76149f | 272 | |
444eb2a4 | 273 | static ssize_t triple_flag_store(struct kobject *kobj, |
71e3aac0 AA |
274 | struct kobj_attribute *attr, |
275 | const char *buf, size_t count, | |
276 | enum transparent_hugepage_flag enabled, | |
444eb2a4 | 277 | enum transparent_hugepage_flag deferred, |
71e3aac0 AA |
278 | enum transparent_hugepage_flag req_madv) |
279 | { | |
444eb2a4 MG |
280 | if (!memcmp("defer", buf, |
281 | min(sizeof("defer")-1, count))) { | |
282 | if (enabled == deferred) | |
283 | return -EINVAL; | |
284 | clear_bit(enabled, &transparent_hugepage_flags); | |
285 | clear_bit(req_madv, &transparent_hugepage_flags); | |
286 | set_bit(deferred, &transparent_hugepage_flags); | |
287 | } else if (!memcmp("always", buf, | |
71e3aac0 | 288 | min(sizeof("always")-1, count))) { |
444eb2a4 | 289 | clear_bit(deferred, &transparent_hugepage_flags); |
71e3aac0 | 290 | clear_bit(req_madv, &transparent_hugepage_flags); |
444eb2a4 | 291 | set_bit(enabled, &transparent_hugepage_flags); |
71e3aac0 AA |
292 | } else if (!memcmp("madvise", buf, |
293 | min(sizeof("madvise")-1, count))) { | |
294 | clear_bit(enabled, &transparent_hugepage_flags); | |
444eb2a4 | 295 | clear_bit(deferred, &transparent_hugepage_flags); |
71e3aac0 AA |
296 | set_bit(req_madv, &transparent_hugepage_flags); |
297 | } else if (!memcmp("never", buf, | |
298 | min(sizeof("never")-1, count))) { | |
299 | clear_bit(enabled, &transparent_hugepage_flags); | |
300 | clear_bit(req_madv, &transparent_hugepage_flags); | |
444eb2a4 | 301 | clear_bit(deferred, &transparent_hugepage_flags); |
71e3aac0 AA |
302 | } else |
303 | return -EINVAL; | |
304 | ||
305 | return count; | |
306 | } | |
307 | ||
308 | static ssize_t enabled_show(struct kobject *kobj, | |
309 | struct kobj_attribute *attr, char *buf) | |
310 | { | |
444eb2a4 MG |
311 | if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) |
312 | return sprintf(buf, "[always] madvise never\n"); | |
313 | else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
314 | return sprintf(buf, "always [madvise] never\n"); | |
315 | else | |
316 | return sprintf(buf, "always madvise [never]\n"); | |
71e3aac0 | 317 | } |
444eb2a4 | 318 | |
71e3aac0 AA |
319 | static ssize_t enabled_store(struct kobject *kobj, |
320 | struct kobj_attribute *attr, | |
321 | const char *buf, size_t count) | |
322 | { | |
ba76149f AA |
323 | ssize_t ret; |
324 | ||
444eb2a4 MG |
325 | ret = triple_flag_store(kobj, attr, buf, count, |
326 | TRANSPARENT_HUGEPAGE_FLAG, | |
ba76149f AA |
327 | TRANSPARENT_HUGEPAGE_FLAG, |
328 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
329 | ||
330 | if (ret > 0) { | |
911891af XG |
331 | int err; |
332 | ||
333 | mutex_lock(&khugepaged_mutex); | |
79553da2 | 334 | err = start_stop_khugepaged(); |
911891af XG |
335 | mutex_unlock(&khugepaged_mutex); |
336 | ||
ba76149f AA |
337 | if (err) |
338 | ret = err; | |
339 | } | |
340 | ||
341 | return ret; | |
71e3aac0 AA |
342 | } |
343 | static struct kobj_attribute enabled_attr = | |
344 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
345 | ||
346 | static ssize_t single_flag_show(struct kobject *kobj, | |
347 | struct kobj_attribute *attr, char *buf, | |
348 | enum transparent_hugepage_flag flag) | |
349 | { | |
e27e6151 BH |
350 | return sprintf(buf, "%d\n", |
351 | !!test_bit(flag, &transparent_hugepage_flags)); | |
71e3aac0 | 352 | } |
e27e6151 | 353 | |
71e3aac0 AA |
354 | static ssize_t single_flag_store(struct kobject *kobj, |
355 | struct kobj_attribute *attr, | |
356 | const char *buf, size_t count, | |
357 | enum transparent_hugepage_flag flag) | |
358 | { | |
e27e6151 BH |
359 | unsigned long value; |
360 | int ret; | |
361 | ||
362 | ret = kstrtoul(buf, 10, &value); | |
363 | if (ret < 0) | |
364 | return ret; | |
365 | if (value > 1) | |
366 | return -EINVAL; | |
367 | ||
368 | if (value) | |
71e3aac0 | 369 | set_bit(flag, &transparent_hugepage_flags); |
e27e6151 | 370 | else |
71e3aac0 | 371 | clear_bit(flag, &transparent_hugepage_flags); |
71e3aac0 AA |
372 | |
373 | return count; | |
374 | } | |
375 | ||
376 | /* | |
377 | * Currently defrag only disables __GFP_NOWAIT for allocation. A blind | |
378 | * __GFP_REPEAT is too aggressive, it's never worth swapping tons of | |
379 | * memory just to allocate one more hugepage. | |
380 | */ | |
381 | static ssize_t defrag_show(struct kobject *kobj, | |
382 | struct kobj_attribute *attr, char *buf) | |
383 | { | |
444eb2a4 MG |
384 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) |
385 | return sprintf(buf, "[always] defer madvise never\n"); | |
386 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) | |
387 | return sprintf(buf, "always [defer] madvise never\n"); | |
388 | else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
389 | return sprintf(buf, "always defer [madvise] never\n"); | |
390 | else | |
391 | return sprintf(buf, "always defer madvise [never]\n"); | |
392 | ||
71e3aac0 AA |
393 | } |
394 | static ssize_t defrag_store(struct kobject *kobj, | |
395 | struct kobj_attribute *attr, | |
396 | const char *buf, size_t count) | |
397 | { | |
444eb2a4 MG |
398 | return triple_flag_store(kobj, attr, buf, count, |
399 | TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, | |
400 | TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, | |
71e3aac0 AA |
401 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); |
402 | } | |
403 | static struct kobj_attribute defrag_attr = | |
404 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
405 | ||
79da5407 KS |
406 | static ssize_t use_zero_page_show(struct kobject *kobj, |
407 | struct kobj_attribute *attr, char *buf) | |
408 | { | |
409 | return single_flag_show(kobj, attr, buf, | |
410 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
411 | } | |
412 | static ssize_t use_zero_page_store(struct kobject *kobj, | |
413 | struct kobj_attribute *attr, const char *buf, size_t count) | |
414 | { | |
415 | return single_flag_store(kobj, attr, buf, count, | |
416 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
417 | } | |
418 | static struct kobj_attribute use_zero_page_attr = | |
419 | __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); | |
71e3aac0 AA |
420 | #ifdef CONFIG_DEBUG_VM |
421 | static ssize_t debug_cow_show(struct kobject *kobj, | |
422 | struct kobj_attribute *attr, char *buf) | |
423 | { | |
424 | return single_flag_show(kobj, attr, buf, | |
425 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
426 | } | |
427 | static ssize_t debug_cow_store(struct kobject *kobj, | |
428 | struct kobj_attribute *attr, | |
429 | const char *buf, size_t count) | |
430 | { | |
431 | return single_flag_store(kobj, attr, buf, count, | |
432 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
433 | } | |
434 | static struct kobj_attribute debug_cow_attr = | |
435 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
436 | #endif /* CONFIG_DEBUG_VM */ | |
437 | ||
438 | static struct attribute *hugepage_attr[] = { | |
439 | &enabled_attr.attr, | |
440 | &defrag_attr.attr, | |
79da5407 | 441 | &use_zero_page_attr.attr, |
71e3aac0 AA |
442 | #ifdef CONFIG_DEBUG_VM |
443 | &debug_cow_attr.attr, | |
444 | #endif | |
445 | NULL, | |
446 | }; | |
447 | ||
448 | static struct attribute_group hugepage_attr_group = { | |
449 | .attrs = hugepage_attr, | |
ba76149f AA |
450 | }; |
451 | ||
452 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, | |
453 | struct kobj_attribute *attr, | |
454 | char *buf) | |
455 | { | |
456 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
457 | } | |
458 | ||
459 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
460 | struct kobj_attribute *attr, | |
461 | const char *buf, size_t count) | |
462 | { | |
463 | unsigned long msecs; | |
464 | int err; | |
465 | ||
3dbb95f7 | 466 | err = kstrtoul(buf, 10, &msecs); |
ba76149f AA |
467 | if (err || msecs > UINT_MAX) |
468 | return -EINVAL; | |
469 | ||
470 | khugepaged_scan_sleep_millisecs = msecs; | |
f0508977 | 471 | khugepaged_sleep_expire = 0; |
ba76149f AA |
472 | wake_up_interruptible(&khugepaged_wait); |
473 | ||
474 | return count; | |
475 | } | |
476 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
477 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
478 | scan_sleep_millisecs_store); | |
479 | ||
480 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
481 | struct kobj_attribute *attr, | |
482 | char *buf) | |
483 | { | |
484 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
485 | } | |
486 | ||
487 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
488 | struct kobj_attribute *attr, | |
489 | const char *buf, size_t count) | |
490 | { | |
491 | unsigned long msecs; | |
492 | int err; | |
493 | ||
3dbb95f7 | 494 | err = kstrtoul(buf, 10, &msecs); |
ba76149f AA |
495 | if (err || msecs > UINT_MAX) |
496 | return -EINVAL; | |
497 | ||
498 | khugepaged_alloc_sleep_millisecs = msecs; | |
f0508977 | 499 | khugepaged_sleep_expire = 0; |
ba76149f AA |
500 | wake_up_interruptible(&khugepaged_wait); |
501 | ||
502 | return count; | |
503 | } | |
504 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
505 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
506 | alloc_sleep_millisecs_store); | |
507 | ||
508 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
509 | struct kobj_attribute *attr, | |
510 | char *buf) | |
511 | { | |
512 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
513 | } | |
514 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
515 | struct kobj_attribute *attr, | |
516 | const char *buf, size_t count) | |
517 | { | |
518 | int err; | |
519 | unsigned long pages; | |
520 | ||
3dbb95f7 | 521 | err = kstrtoul(buf, 10, &pages); |
ba76149f AA |
522 | if (err || !pages || pages > UINT_MAX) |
523 | return -EINVAL; | |
524 | ||
525 | khugepaged_pages_to_scan = pages; | |
526 | ||
527 | return count; | |
528 | } | |
529 | static struct kobj_attribute pages_to_scan_attr = | |
530 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
531 | pages_to_scan_store); | |
532 | ||
533 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
534 | struct kobj_attribute *attr, | |
535 | char *buf) | |
536 | { | |
537 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
538 | } | |
539 | static struct kobj_attribute pages_collapsed_attr = | |
540 | __ATTR_RO(pages_collapsed); | |
541 | ||
542 | static ssize_t full_scans_show(struct kobject *kobj, | |
543 | struct kobj_attribute *attr, | |
544 | char *buf) | |
545 | { | |
546 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
547 | } | |
548 | static struct kobj_attribute full_scans_attr = | |
549 | __ATTR_RO(full_scans); | |
550 | ||
551 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
552 | struct kobj_attribute *attr, char *buf) | |
553 | { | |
554 | return single_flag_show(kobj, attr, buf, | |
555 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
556 | } | |
557 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
558 | struct kobj_attribute *attr, | |
559 | const char *buf, size_t count) | |
560 | { | |
561 | return single_flag_store(kobj, attr, buf, count, | |
562 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
563 | } | |
564 | static struct kobj_attribute khugepaged_defrag_attr = | |
565 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
566 | khugepaged_defrag_store); | |
567 | ||
568 | /* | |
569 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
570 | * any unmapped ptes in turn potentially increasing the memory | |
571 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
572 | * reduce the available free memory in the system as it | |
573 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
574 | * free memory in the system during the khugepaged scan. | |
575 | */ | |
576 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
577 | struct kobj_attribute *attr, | |
578 | char *buf) | |
579 | { | |
580 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
581 | } | |
582 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
583 | struct kobj_attribute *attr, | |
584 | const char *buf, size_t count) | |
585 | { | |
586 | int err; | |
587 | unsigned long max_ptes_none; | |
588 | ||
3dbb95f7 | 589 | err = kstrtoul(buf, 10, &max_ptes_none); |
ba76149f AA |
590 | if (err || max_ptes_none > HPAGE_PMD_NR-1) |
591 | return -EINVAL; | |
592 | ||
593 | khugepaged_max_ptes_none = max_ptes_none; | |
594 | ||
595 | return count; | |
596 | } | |
597 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
598 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
599 | khugepaged_max_ptes_none_store); | |
600 | ||
601 | static struct attribute *khugepaged_attr[] = { | |
602 | &khugepaged_defrag_attr.attr, | |
603 | &khugepaged_max_ptes_none_attr.attr, | |
604 | &pages_to_scan_attr.attr, | |
605 | &pages_collapsed_attr.attr, | |
606 | &full_scans_attr.attr, | |
607 | &scan_sleep_millisecs_attr.attr, | |
608 | &alloc_sleep_millisecs_attr.attr, | |
609 | NULL, | |
610 | }; | |
611 | ||
612 | static struct attribute_group khugepaged_attr_group = { | |
613 | .attrs = khugepaged_attr, | |
614 | .name = "khugepaged", | |
71e3aac0 | 615 | }; |
71e3aac0 | 616 | |
569e5590 | 617 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
71e3aac0 | 618 | { |
71e3aac0 AA |
619 | int err; |
620 | ||
569e5590 SL |
621 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); |
622 | if (unlikely(!*hugepage_kobj)) { | |
ae3a8c1c | 623 | pr_err("failed to create transparent hugepage kobject\n"); |
569e5590 | 624 | return -ENOMEM; |
ba76149f AA |
625 | } |
626 | ||
569e5590 | 627 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); |
ba76149f | 628 | if (err) { |
ae3a8c1c | 629 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 630 | goto delete_obj; |
ba76149f AA |
631 | } |
632 | ||
569e5590 | 633 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); |
ba76149f | 634 | if (err) { |
ae3a8c1c | 635 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 636 | goto remove_hp_group; |
ba76149f | 637 | } |
569e5590 SL |
638 | |
639 | return 0; | |
640 | ||
641 | remove_hp_group: | |
642 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
643 | delete_obj: | |
644 | kobject_put(*hugepage_kobj); | |
645 | return err; | |
646 | } | |
647 | ||
648 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
649 | { | |
650 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
651 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
652 | kobject_put(hugepage_kobj); | |
653 | } | |
654 | #else | |
655 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
656 | { | |
657 | return 0; | |
658 | } | |
659 | ||
660 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
661 | { | |
662 | } | |
663 | #endif /* CONFIG_SYSFS */ | |
664 | ||
665 | static int __init hugepage_init(void) | |
666 | { | |
667 | int err; | |
668 | struct kobject *hugepage_kobj; | |
669 | ||
670 | if (!has_transparent_hugepage()) { | |
671 | transparent_hugepage_flags = 0; | |
672 | return -EINVAL; | |
673 | } | |
674 | ||
ff20c2e0 KS |
675 | khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; |
676 | khugepaged_max_ptes_none = HPAGE_PMD_NR - 1; | |
677 | /* | |
678 | * hugepages can't be allocated by the buddy allocator | |
679 | */ | |
680 | MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); | |
681 | /* | |
682 | * we use page->mapping and page->index in second tail page | |
683 | * as list_head: assuming THP order >= 2 | |
684 | */ | |
685 | MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); | |
686 | ||
569e5590 SL |
687 | err = hugepage_init_sysfs(&hugepage_kobj); |
688 | if (err) | |
65ebb64f | 689 | goto err_sysfs; |
ba76149f AA |
690 | |
691 | err = khugepaged_slab_init(); | |
692 | if (err) | |
65ebb64f | 693 | goto err_slab; |
ba76149f | 694 | |
65ebb64f KS |
695 | err = register_shrinker(&huge_zero_page_shrinker); |
696 | if (err) | |
697 | goto err_hzp_shrinker; | |
9a982250 KS |
698 | err = register_shrinker(&deferred_split_shrinker); |
699 | if (err) | |
700 | goto err_split_shrinker; | |
97ae1749 | 701 | |
97562cd2 RR |
702 | /* |
703 | * By default disable transparent hugepages on smaller systems, | |
704 | * where the extra memory used could hurt more than TLB overhead | |
705 | * is likely to save. The admin can still enable it through /sys. | |
706 | */ | |
79553da2 | 707 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) { |
97562cd2 | 708 | transparent_hugepage_flags = 0; |
79553da2 KS |
709 | return 0; |
710 | } | |
97562cd2 | 711 | |
79553da2 | 712 | err = start_stop_khugepaged(); |
65ebb64f KS |
713 | if (err) |
714 | goto err_khugepaged; | |
ba76149f | 715 | |
569e5590 | 716 | return 0; |
65ebb64f | 717 | err_khugepaged: |
9a982250 KS |
718 | unregister_shrinker(&deferred_split_shrinker); |
719 | err_split_shrinker: | |
65ebb64f KS |
720 | unregister_shrinker(&huge_zero_page_shrinker); |
721 | err_hzp_shrinker: | |
722 | khugepaged_slab_exit(); | |
723 | err_slab: | |
569e5590 | 724 | hugepage_exit_sysfs(hugepage_kobj); |
65ebb64f | 725 | err_sysfs: |
ba76149f | 726 | return err; |
71e3aac0 | 727 | } |
a64fb3cd | 728 | subsys_initcall(hugepage_init); |
71e3aac0 AA |
729 | |
730 | static int __init setup_transparent_hugepage(char *str) | |
731 | { | |
732 | int ret = 0; | |
733 | if (!str) | |
734 | goto out; | |
735 | if (!strcmp(str, "always")) { | |
736 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
737 | &transparent_hugepage_flags); | |
738 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
739 | &transparent_hugepage_flags); | |
740 | ret = 1; | |
741 | } else if (!strcmp(str, "madvise")) { | |
742 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
743 | &transparent_hugepage_flags); | |
744 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
745 | &transparent_hugepage_flags); | |
746 | ret = 1; | |
747 | } else if (!strcmp(str, "never")) { | |
748 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
749 | &transparent_hugepage_flags); | |
750 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
751 | &transparent_hugepage_flags); | |
752 | ret = 1; | |
753 | } | |
754 | out: | |
755 | if (!ret) | |
ae3a8c1c | 756 | pr_warn("transparent_hugepage= cannot parse, ignored\n"); |
71e3aac0 AA |
757 | return ret; |
758 | } | |
759 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
760 | ||
b32967ff | 761 | pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) |
71e3aac0 AA |
762 | { |
763 | if (likely(vma->vm_flags & VM_WRITE)) | |
764 | pmd = pmd_mkwrite(pmd); | |
765 | return pmd; | |
766 | } | |
767 | ||
3122359a | 768 | static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot) |
b3092b3b | 769 | { |
340a43be | 770 | return pmd_mkhuge(mk_pmd(page, prot)); |
b3092b3b BL |
771 | } |
772 | ||
9a982250 KS |
773 | static inline struct list_head *page_deferred_list(struct page *page) |
774 | { | |
775 | /* | |
776 | * ->lru in the tail pages is occupied by compound_head. | |
777 | * Let's use ->mapping + ->index in the second tail page as list_head. | |
778 | */ | |
779 | return (struct list_head *)&page[2].mapping; | |
780 | } | |
781 | ||
782 | void prep_transhuge_page(struct page *page) | |
783 | { | |
784 | /* | |
785 | * we use page->mapping and page->indexlru in second tail page | |
786 | * as list_head: assuming THP order >= 2 | |
787 | */ | |
9a982250 KS |
788 | |
789 | INIT_LIST_HEAD(page_deferred_list(page)); | |
790 | set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); | |
791 | } | |
792 | ||
71e3aac0 AA |
793 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, |
794 | struct vm_area_struct *vma, | |
230c92a8 | 795 | unsigned long address, pmd_t *pmd, |
6b251fc9 AA |
796 | struct page *page, gfp_t gfp, |
797 | unsigned int flags) | |
71e3aac0 | 798 | { |
00501b53 | 799 | struct mem_cgroup *memcg; |
71e3aac0 | 800 | pgtable_t pgtable; |
c4088ebd | 801 | spinlock_t *ptl; |
230c92a8 | 802 | unsigned long haddr = address & HPAGE_PMD_MASK; |
71e3aac0 | 803 | |
309381fe | 804 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
00501b53 | 805 | |
f627c2f5 | 806 | if (mem_cgroup_try_charge(page, mm, gfp, &memcg, true)) { |
6b251fc9 AA |
807 | put_page(page); |
808 | count_vm_event(THP_FAULT_FALLBACK); | |
809 | return VM_FAULT_FALLBACK; | |
810 | } | |
00501b53 | 811 | |
71e3aac0 | 812 | pgtable = pte_alloc_one(mm, haddr); |
00501b53 | 813 | if (unlikely(!pgtable)) { |
f627c2f5 | 814 | mem_cgroup_cancel_charge(page, memcg, true); |
6b251fc9 | 815 | put_page(page); |
71e3aac0 | 816 | return VM_FAULT_OOM; |
00501b53 | 817 | } |
71e3aac0 AA |
818 | |
819 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
52f37629 MK |
820 | /* |
821 | * The memory barrier inside __SetPageUptodate makes sure that | |
822 | * clear_huge_page writes become visible before the set_pmd_at() | |
823 | * write. | |
824 | */ | |
71e3aac0 AA |
825 | __SetPageUptodate(page); |
826 | ||
c4088ebd | 827 | ptl = pmd_lock(mm, pmd); |
71e3aac0 | 828 | if (unlikely(!pmd_none(*pmd))) { |
c4088ebd | 829 | spin_unlock(ptl); |
f627c2f5 | 830 | mem_cgroup_cancel_charge(page, memcg, true); |
71e3aac0 AA |
831 | put_page(page); |
832 | pte_free(mm, pgtable); | |
833 | } else { | |
834 | pmd_t entry; | |
6b251fc9 AA |
835 | |
836 | /* Deliver the page fault to userland */ | |
837 | if (userfaultfd_missing(vma)) { | |
838 | int ret; | |
839 | ||
840 | spin_unlock(ptl); | |
f627c2f5 | 841 | mem_cgroup_cancel_charge(page, memcg, true); |
6b251fc9 AA |
842 | put_page(page); |
843 | pte_free(mm, pgtable); | |
230c92a8 | 844 | ret = handle_userfault(vma, address, flags, |
6b251fc9 AA |
845 | VM_UFFD_MISSING); |
846 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
847 | return ret; | |
848 | } | |
849 | ||
3122359a KS |
850 | entry = mk_huge_pmd(page, vma->vm_page_prot); |
851 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
d281ee61 | 852 | page_add_new_anon_rmap(page, vma, haddr, true); |
f627c2f5 | 853 | mem_cgroup_commit_charge(page, memcg, false, true); |
00501b53 | 854 | lru_cache_add_active_or_unevictable(page, vma); |
6b0b50b0 | 855 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
71e3aac0 | 856 | set_pmd_at(mm, haddr, pmd, entry); |
71e3aac0 | 857 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
e1f56c89 | 858 | atomic_long_inc(&mm->nr_ptes); |
c4088ebd | 859 | spin_unlock(ptl); |
6b251fc9 | 860 | count_vm_event(THP_FAULT_ALLOC); |
71e3aac0 AA |
861 | } |
862 | ||
aa2e878e | 863 | return 0; |
71e3aac0 AA |
864 | } |
865 | ||
444eb2a4 MG |
866 | /* |
867 | * If THP is set to always then directly reclaim/compact as necessary | |
868 | * If set to defer then do no reclaim and defer to khugepaged | |
869 | * If set to madvise and the VMA is flagged then directly reclaim/compact | |
870 | */ | |
871 | static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma) | |
872 | { | |
873 | gfp_t reclaim_flags = 0; | |
874 | ||
875 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags) && | |
876 | (vma->vm_flags & VM_HUGEPAGE)) | |
877 | reclaim_flags = __GFP_DIRECT_RECLAIM; | |
878 | else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) | |
879 | reclaim_flags = __GFP_KSWAPD_RECLAIM; | |
880 | else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) | |
881 | reclaim_flags = __GFP_DIRECT_RECLAIM; | |
882 | ||
883 | return GFP_TRANSHUGE | reclaim_flags; | |
884 | } | |
885 | ||
886 | /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */ | |
887 | static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void) | |
0bbbc0b3 | 888 | { |
444eb2a4 | 889 | return GFP_TRANSHUGE | (khugepaged_defrag() ? __GFP_DIRECT_RECLAIM : 0); |
0bbbc0b3 AA |
890 | } |
891 | ||
c4088ebd | 892 | /* Caller must hold page table lock. */ |
d295e341 | 893 | static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, |
97ae1749 | 894 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, |
5918d10a | 895 | struct page *zero_page) |
fc9fe822 KS |
896 | { |
897 | pmd_t entry; | |
7c414164 AM |
898 | if (!pmd_none(*pmd)) |
899 | return false; | |
5918d10a | 900 | entry = mk_pmd(zero_page, vma->vm_page_prot); |
fc9fe822 | 901 | entry = pmd_mkhuge(entry); |
12c9d70b MW |
902 | if (pgtable) |
903 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
fc9fe822 | 904 | set_pmd_at(mm, haddr, pmd, entry); |
e1f56c89 | 905 | atomic_long_inc(&mm->nr_ptes); |
7c414164 | 906 | return true; |
fc9fe822 KS |
907 | } |
908 | ||
71e3aac0 AA |
909 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, |
910 | unsigned long address, pmd_t *pmd, | |
911 | unsigned int flags) | |
912 | { | |
077fcf11 | 913 | gfp_t gfp; |
71e3aac0 AA |
914 | struct page *page; |
915 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
71e3aac0 | 916 | |
128ec037 | 917 | if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) |
c0292554 | 918 | return VM_FAULT_FALLBACK; |
128ec037 KS |
919 | if (unlikely(anon_vma_prepare(vma))) |
920 | return VM_FAULT_OOM; | |
6d50e60c | 921 | if (unlikely(khugepaged_enter(vma, vma->vm_flags))) |
128ec037 | 922 | return VM_FAULT_OOM; |
593befa6 | 923 | if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) && |
128ec037 | 924 | transparent_hugepage_use_zero_page()) { |
c4088ebd | 925 | spinlock_t *ptl; |
128ec037 KS |
926 | pgtable_t pgtable; |
927 | struct page *zero_page; | |
928 | bool set; | |
6b251fc9 | 929 | int ret; |
128ec037 KS |
930 | pgtable = pte_alloc_one(mm, haddr); |
931 | if (unlikely(!pgtable)) | |
ba76149f | 932 | return VM_FAULT_OOM; |
128ec037 KS |
933 | zero_page = get_huge_zero_page(); |
934 | if (unlikely(!zero_page)) { | |
935 | pte_free(mm, pgtable); | |
81ab4201 | 936 | count_vm_event(THP_FAULT_FALLBACK); |
c0292554 | 937 | return VM_FAULT_FALLBACK; |
b9bbfbe3 | 938 | } |
c4088ebd | 939 | ptl = pmd_lock(mm, pmd); |
6b251fc9 AA |
940 | ret = 0; |
941 | set = false; | |
942 | if (pmd_none(*pmd)) { | |
943 | if (userfaultfd_missing(vma)) { | |
944 | spin_unlock(ptl); | |
230c92a8 | 945 | ret = handle_userfault(vma, address, flags, |
6b251fc9 AA |
946 | VM_UFFD_MISSING); |
947 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
948 | } else { | |
949 | set_huge_zero_page(pgtable, mm, vma, | |
950 | haddr, pmd, | |
951 | zero_page); | |
952 | spin_unlock(ptl); | |
953 | set = true; | |
954 | } | |
955 | } else | |
956 | spin_unlock(ptl); | |
128ec037 KS |
957 | if (!set) { |
958 | pte_free(mm, pgtable); | |
959 | put_huge_zero_page(); | |
edad9d2c | 960 | } |
6b251fc9 | 961 | return ret; |
71e3aac0 | 962 | } |
444eb2a4 | 963 | gfp = alloc_hugepage_direct_gfpmask(vma); |
077fcf11 | 964 | page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); |
128ec037 KS |
965 | if (unlikely(!page)) { |
966 | count_vm_event(THP_FAULT_FALLBACK); | |
c0292554 | 967 | return VM_FAULT_FALLBACK; |
128ec037 | 968 | } |
9a982250 | 969 | prep_transhuge_page(page); |
230c92a8 AA |
970 | return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp, |
971 | flags); | |
71e3aac0 AA |
972 | } |
973 | ||
ae18d6dc | 974 | static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, |
f25748e3 | 975 | pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write) |
5cad465d MW |
976 | { |
977 | struct mm_struct *mm = vma->vm_mm; | |
978 | pmd_t entry; | |
979 | spinlock_t *ptl; | |
980 | ||
981 | ptl = pmd_lock(mm, pmd); | |
f25748e3 DW |
982 | entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); |
983 | if (pfn_t_devmap(pfn)) | |
984 | entry = pmd_mkdevmap(entry); | |
01871e59 RZ |
985 | if (write) { |
986 | entry = pmd_mkyoung(pmd_mkdirty(entry)); | |
987 | entry = maybe_pmd_mkwrite(entry, vma); | |
5cad465d | 988 | } |
01871e59 RZ |
989 | set_pmd_at(mm, addr, pmd, entry); |
990 | update_mmu_cache_pmd(vma, addr, pmd); | |
5cad465d | 991 | spin_unlock(ptl); |
5cad465d MW |
992 | } |
993 | ||
994 | int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, | |
f25748e3 | 995 | pmd_t *pmd, pfn_t pfn, bool write) |
5cad465d MW |
996 | { |
997 | pgprot_t pgprot = vma->vm_page_prot; | |
998 | /* | |
999 | * If we had pmd_special, we could avoid all these restrictions, | |
1000 | * but we need to be consistent with PTEs and architectures that | |
1001 | * can't support a 'special' bit. | |
1002 | */ | |
1003 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); | |
1004 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == | |
1005 | (VM_PFNMAP|VM_MIXEDMAP)); | |
1006 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); | |
f25748e3 | 1007 | BUG_ON(!pfn_t_devmap(pfn)); |
5cad465d MW |
1008 | |
1009 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
1010 | return VM_FAULT_SIGBUS; | |
1011 | if (track_pfn_insert(vma, &pgprot, pfn)) | |
1012 | return VM_FAULT_SIGBUS; | |
ae18d6dc MW |
1013 | insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write); |
1014 | return VM_FAULT_NOPAGE; | |
5cad465d | 1015 | } |
dee41079 | 1016 | EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); |
5cad465d | 1017 | |
3565fce3 DW |
1018 | static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, |
1019 | pmd_t *pmd) | |
1020 | { | |
1021 | pmd_t _pmd; | |
1022 | ||
1023 | /* | |
1024 | * We should set the dirty bit only for FOLL_WRITE but for now | |
1025 | * the dirty bit in the pmd is meaningless. And if the dirty | |
1026 | * bit will become meaningful and we'll only set it with | |
1027 | * FOLL_WRITE, an atomic set_bit will be required on the pmd to | |
1028 | * set the young bit, instead of the current set_pmd_at. | |
1029 | */ | |
1030 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
1031 | if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, | |
1032 | pmd, _pmd, 1)) | |
1033 | update_mmu_cache_pmd(vma, addr, pmd); | |
1034 | } | |
1035 | ||
1036 | struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, | |
1037 | pmd_t *pmd, int flags) | |
1038 | { | |
1039 | unsigned long pfn = pmd_pfn(*pmd); | |
1040 | struct mm_struct *mm = vma->vm_mm; | |
1041 | struct dev_pagemap *pgmap; | |
1042 | struct page *page; | |
1043 | ||
1044 | assert_spin_locked(pmd_lockptr(mm, pmd)); | |
1045 | ||
1046 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1047 | return NULL; | |
1048 | ||
1049 | if (pmd_present(*pmd) && pmd_devmap(*pmd)) | |
1050 | /* pass */; | |
1051 | else | |
1052 | return NULL; | |
1053 | ||
1054 | if (flags & FOLL_TOUCH) | |
1055 | touch_pmd(vma, addr, pmd); | |
1056 | ||
1057 | /* | |
1058 | * device mapped pages can only be returned if the | |
1059 | * caller will manage the page reference count. | |
1060 | */ | |
1061 | if (!(flags & FOLL_GET)) | |
1062 | return ERR_PTR(-EEXIST); | |
1063 | ||
1064 | pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; | |
1065 | pgmap = get_dev_pagemap(pfn, NULL); | |
1066 | if (!pgmap) | |
1067 | return ERR_PTR(-EFAULT); | |
1068 | page = pfn_to_page(pfn); | |
1069 | get_page(page); | |
1070 | put_dev_pagemap(pgmap); | |
1071 | ||
1072 | return page; | |
1073 | } | |
1074 | ||
71e3aac0 AA |
1075 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
1076 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
1077 | struct vm_area_struct *vma) | |
1078 | { | |
c4088ebd | 1079 | spinlock_t *dst_ptl, *src_ptl; |
71e3aac0 AA |
1080 | struct page *src_page; |
1081 | pmd_t pmd; | |
12c9d70b | 1082 | pgtable_t pgtable = NULL; |
71e3aac0 AA |
1083 | int ret; |
1084 | ||
12c9d70b MW |
1085 | if (!vma_is_dax(vma)) { |
1086 | ret = -ENOMEM; | |
1087 | pgtable = pte_alloc_one(dst_mm, addr); | |
1088 | if (unlikely(!pgtable)) | |
1089 | goto out; | |
1090 | } | |
71e3aac0 | 1091 | |
c4088ebd KS |
1092 | dst_ptl = pmd_lock(dst_mm, dst_pmd); |
1093 | src_ptl = pmd_lockptr(src_mm, src_pmd); | |
1094 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
71e3aac0 AA |
1095 | |
1096 | ret = -EAGAIN; | |
1097 | pmd = *src_pmd; | |
5c7fb56e | 1098 | if (unlikely(!pmd_trans_huge(pmd) && !pmd_devmap(pmd))) { |
71e3aac0 AA |
1099 | pte_free(dst_mm, pgtable); |
1100 | goto out_unlock; | |
1101 | } | |
fc9fe822 | 1102 | /* |
c4088ebd | 1103 | * When page table lock is held, the huge zero pmd should not be |
fc9fe822 KS |
1104 | * under splitting since we don't split the page itself, only pmd to |
1105 | * a page table. | |
1106 | */ | |
1107 | if (is_huge_zero_pmd(pmd)) { | |
5918d10a | 1108 | struct page *zero_page; |
97ae1749 KS |
1109 | /* |
1110 | * get_huge_zero_page() will never allocate a new page here, | |
1111 | * since we already have a zero page to copy. It just takes a | |
1112 | * reference. | |
1113 | */ | |
5918d10a | 1114 | zero_page = get_huge_zero_page(); |
6b251fc9 | 1115 | set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, |
5918d10a | 1116 | zero_page); |
fc9fe822 KS |
1117 | ret = 0; |
1118 | goto out_unlock; | |
1119 | } | |
de466bd6 | 1120 | |
12c9d70b | 1121 | if (!vma_is_dax(vma)) { |
5c7fb56e DW |
1122 | /* thp accounting separate from pmd_devmap accounting */ |
1123 | src_page = pmd_page(pmd); | |
1124 | VM_BUG_ON_PAGE(!PageHead(src_page), src_page); | |
1125 | get_page(src_page); | |
1126 | page_dup_rmap(src_page, true); | |
1127 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
1128 | atomic_long_inc(&dst_mm->nr_ptes); | |
1129 | pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); | |
1130 | } | |
71e3aac0 AA |
1131 | |
1132 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
1133 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
1134 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
71e3aac0 AA |
1135 | |
1136 | ret = 0; | |
1137 | out_unlock: | |
c4088ebd KS |
1138 | spin_unlock(src_ptl); |
1139 | spin_unlock(dst_ptl); | |
71e3aac0 AA |
1140 | out: |
1141 | return ret; | |
1142 | } | |
1143 | ||
a1dd450b WD |
1144 | void huge_pmd_set_accessed(struct mm_struct *mm, |
1145 | struct vm_area_struct *vma, | |
1146 | unsigned long address, | |
1147 | pmd_t *pmd, pmd_t orig_pmd, | |
1148 | int dirty) | |
1149 | { | |
c4088ebd | 1150 | spinlock_t *ptl; |
a1dd450b WD |
1151 | pmd_t entry; |
1152 | unsigned long haddr; | |
1153 | ||
c4088ebd | 1154 | ptl = pmd_lock(mm, pmd); |
a1dd450b WD |
1155 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1156 | goto unlock; | |
1157 | ||
1158 | entry = pmd_mkyoung(orig_pmd); | |
1159 | haddr = address & HPAGE_PMD_MASK; | |
1160 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty)) | |
1161 | update_mmu_cache_pmd(vma, address, pmd); | |
1162 | ||
1163 | unlock: | |
c4088ebd | 1164 | spin_unlock(ptl); |
a1dd450b WD |
1165 | } |
1166 | ||
71e3aac0 AA |
1167 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, |
1168 | struct vm_area_struct *vma, | |
1169 | unsigned long address, | |
1170 | pmd_t *pmd, pmd_t orig_pmd, | |
1171 | struct page *page, | |
1172 | unsigned long haddr) | |
1173 | { | |
00501b53 | 1174 | struct mem_cgroup *memcg; |
c4088ebd | 1175 | spinlock_t *ptl; |
71e3aac0 AA |
1176 | pgtable_t pgtable; |
1177 | pmd_t _pmd; | |
1178 | int ret = 0, i; | |
1179 | struct page **pages; | |
2ec74c3e SG |
1180 | unsigned long mmun_start; /* For mmu_notifiers */ |
1181 | unsigned long mmun_end; /* For mmu_notifiers */ | |
71e3aac0 AA |
1182 | |
1183 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
1184 | GFP_KERNEL); | |
1185 | if (unlikely(!pages)) { | |
1186 | ret |= VM_FAULT_OOM; | |
1187 | goto out; | |
1188 | } | |
1189 | ||
1190 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
cc5d462f AK |
1191 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE | |
1192 | __GFP_OTHER_NODE, | |
19ee151e | 1193 | vma, address, page_to_nid(page)); |
b9bbfbe3 | 1194 | if (unlikely(!pages[i] || |
00501b53 | 1195 | mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL, |
f627c2f5 | 1196 | &memcg, false))) { |
b9bbfbe3 | 1197 | if (pages[i]) |
71e3aac0 | 1198 | put_page(pages[i]); |
b9bbfbe3 | 1199 | while (--i >= 0) { |
00501b53 JW |
1200 | memcg = (void *)page_private(pages[i]); |
1201 | set_page_private(pages[i], 0); | |
f627c2f5 KS |
1202 | mem_cgroup_cancel_charge(pages[i], memcg, |
1203 | false); | |
b9bbfbe3 AA |
1204 | put_page(pages[i]); |
1205 | } | |
71e3aac0 AA |
1206 | kfree(pages); |
1207 | ret |= VM_FAULT_OOM; | |
1208 | goto out; | |
1209 | } | |
00501b53 | 1210 | set_page_private(pages[i], (unsigned long)memcg); |
71e3aac0 AA |
1211 | } |
1212 | ||
1213 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1214 | copy_user_highpage(pages[i], page + i, | |
0089e485 | 1215 | haddr + PAGE_SIZE * i, vma); |
71e3aac0 AA |
1216 | __SetPageUptodate(pages[i]); |
1217 | cond_resched(); | |
1218 | } | |
1219 | ||
2ec74c3e SG |
1220 | mmun_start = haddr; |
1221 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1222 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1223 | ||
c4088ebd | 1224 | ptl = pmd_lock(mm, pmd); |
71e3aac0 AA |
1225 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1226 | goto out_free_pages; | |
309381fe | 1227 | VM_BUG_ON_PAGE(!PageHead(page), page); |
71e3aac0 | 1228 | |
8809aa2d | 1229 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
71e3aac0 AA |
1230 | /* leave pmd empty until pte is filled */ |
1231 | ||
6b0b50b0 | 1232 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
71e3aac0 AA |
1233 | pmd_populate(mm, &_pmd, pgtable); |
1234 | ||
1235 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
1236 | pte_t *pte, entry; | |
1237 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
1238 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
00501b53 JW |
1239 | memcg = (void *)page_private(pages[i]); |
1240 | set_page_private(pages[i], 0); | |
d281ee61 | 1241 | page_add_new_anon_rmap(pages[i], vma, haddr, false); |
f627c2f5 | 1242 | mem_cgroup_commit_charge(pages[i], memcg, false, false); |
00501b53 | 1243 | lru_cache_add_active_or_unevictable(pages[i], vma); |
71e3aac0 AA |
1244 | pte = pte_offset_map(&_pmd, haddr); |
1245 | VM_BUG_ON(!pte_none(*pte)); | |
1246 | set_pte_at(mm, haddr, pte, entry); | |
1247 | pte_unmap(pte); | |
1248 | } | |
1249 | kfree(pages); | |
1250 | ||
71e3aac0 AA |
1251 | smp_wmb(); /* make pte visible before pmd */ |
1252 | pmd_populate(mm, pmd, pgtable); | |
d281ee61 | 1253 | page_remove_rmap(page, true); |
c4088ebd | 1254 | spin_unlock(ptl); |
71e3aac0 | 1255 | |
2ec74c3e SG |
1256 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
1257 | ||
71e3aac0 AA |
1258 | ret |= VM_FAULT_WRITE; |
1259 | put_page(page); | |
1260 | ||
1261 | out: | |
1262 | return ret; | |
1263 | ||
1264 | out_free_pages: | |
c4088ebd | 1265 | spin_unlock(ptl); |
2ec74c3e | 1266 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
b9bbfbe3 | 1267 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
00501b53 JW |
1268 | memcg = (void *)page_private(pages[i]); |
1269 | set_page_private(pages[i], 0); | |
f627c2f5 | 1270 | mem_cgroup_cancel_charge(pages[i], memcg, false); |
71e3aac0 | 1271 | put_page(pages[i]); |
b9bbfbe3 | 1272 | } |
71e3aac0 AA |
1273 | kfree(pages); |
1274 | goto out; | |
1275 | } | |
1276 | ||
1277 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
1278 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) | |
1279 | { | |
c4088ebd | 1280 | spinlock_t *ptl; |
71e3aac0 | 1281 | int ret = 0; |
93b4796d | 1282 | struct page *page = NULL, *new_page; |
00501b53 | 1283 | struct mem_cgroup *memcg; |
71e3aac0 | 1284 | unsigned long haddr; |
2ec74c3e SG |
1285 | unsigned long mmun_start; /* For mmu_notifiers */ |
1286 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 1287 | gfp_t huge_gfp; /* for allocation and charge */ |
71e3aac0 | 1288 | |
c4088ebd | 1289 | ptl = pmd_lockptr(mm, pmd); |
81d1b09c | 1290 | VM_BUG_ON_VMA(!vma->anon_vma, vma); |
93b4796d KS |
1291 | haddr = address & HPAGE_PMD_MASK; |
1292 | if (is_huge_zero_pmd(orig_pmd)) | |
1293 | goto alloc; | |
c4088ebd | 1294 | spin_lock(ptl); |
71e3aac0 AA |
1295 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1296 | goto out_unlock; | |
1297 | ||
1298 | page = pmd_page(orig_pmd); | |
309381fe | 1299 | VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); |
1f25fe20 KS |
1300 | /* |
1301 | * We can only reuse the page if nobody else maps the huge page or it's | |
6d0a07ed | 1302 | * part. |
1f25fe20 | 1303 | */ |
6d0a07ed | 1304 | if (page_trans_huge_mapcount(page, NULL) == 1) { |
71e3aac0 AA |
1305 | pmd_t entry; |
1306 | entry = pmd_mkyoung(orig_pmd); | |
1307 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
1308 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) | |
b113da65 | 1309 | update_mmu_cache_pmd(vma, address, pmd); |
71e3aac0 AA |
1310 | ret |= VM_FAULT_WRITE; |
1311 | goto out_unlock; | |
1312 | } | |
ddc58f27 | 1313 | get_page(page); |
c4088ebd | 1314 | spin_unlock(ptl); |
93b4796d | 1315 | alloc: |
71e3aac0 | 1316 | if (transparent_hugepage_enabled(vma) && |
077fcf11 | 1317 | !transparent_hugepage_debug_cow()) { |
444eb2a4 | 1318 | huge_gfp = alloc_hugepage_direct_gfpmask(vma); |
3b363692 | 1319 | new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); |
077fcf11 | 1320 | } else |
71e3aac0 AA |
1321 | new_page = NULL; |
1322 | ||
9a982250 KS |
1323 | if (likely(new_page)) { |
1324 | prep_transhuge_page(new_page); | |
1325 | } else { | |
eecc1e42 | 1326 | if (!page) { |
78ddc534 | 1327 | split_huge_pmd(vma, pmd, address); |
e9b71ca9 | 1328 | ret |= VM_FAULT_FALLBACK; |
93b4796d KS |
1329 | } else { |
1330 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, | |
1331 | pmd, orig_pmd, page, haddr); | |
9845cbbd | 1332 | if (ret & VM_FAULT_OOM) { |
78ddc534 | 1333 | split_huge_pmd(vma, pmd, address); |
9845cbbd KS |
1334 | ret |= VM_FAULT_FALLBACK; |
1335 | } | |
ddc58f27 | 1336 | put_page(page); |
93b4796d | 1337 | } |
17766dde | 1338 | count_vm_event(THP_FAULT_FALLBACK); |
71e3aac0 AA |
1339 | goto out; |
1340 | } | |
1341 | ||
f627c2f5 KS |
1342 | if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg, |
1343 | true))) { | |
b9bbfbe3 | 1344 | put_page(new_page); |
93b4796d | 1345 | if (page) { |
78ddc534 | 1346 | split_huge_pmd(vma, pmd, address); |
ddc58f27 | 1347 | put_page(page); |
9845cbbd | 1348 | } else |
78ddc534 | 1349 | split_huge_pmd(vma, pmd, address); |
9845cbbd | 1350 | ret |= VM_FAULT_FALLBACK; |
17766dde | 1351 | count_vm_event(THP_FAULT_FALLBACK); |
b9bbfbe3 AA |
1352 | goto out; |
1353 | } | |
1354 | ||
17766dde DR |
1355 | count_vm_event(THP_FAULT_ALLOC); |
1356 | ||
eecc1e42 | 1357 | if (!page) |
93b4796d KS |
1358 | clear_huge_page(new_page, haddr, HPAGE_PMD_NR); |
1359 | else | |
1360 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); | |
71e3aac0 AA |
1361 | __SetPageUptodate(new_page); |
1362 | ||
2ec74c3e SG |
1363 | mmun_start = haddr; |
1364 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1365 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1366 | ||
c4088ebd | 1367 | spin_lock(ptl); |
93b4796d | 1368 | if (page) |
ddc58f27 | 1369 | put_page(page); |
b9bbfbe3 | 1370 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { |
c4088ebd | 1371 | spin_unlock(ptl); |
f627c2f5 | 1372 | mem_cgroup_cancel_charge(new_page, memcg, true); |
71e3aac0 | 1373 | put_page(new_page); |
2ec74c3e | 1374 | goto out_mn; |
b9bbfbe3 | 1375 | } else { |
71e3aac0 | 1376 | pmd_t entry; |
3122359a KS |
1377 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); |
1378 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
8809aa2d | 1379 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
d281ee61 | 1380 | page_add_new_anon_rmap(new_page, vma, haddr, true); |
f627c2f5 | 1381 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
00501b53 | 1382 | lru_cache_add_active_or_unevictable(new_page, vma); |
71e3aac0 | 1383 | set_pmd_at(mm, haddr, pmd, entry); |
b113da65 | 1384 | update_mmu_cache_pmd(vma, address, pmd); |
eecc1e42 | 1385 | if (!page) { |
93b4796d | 1386 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
97ae1749 KS |
1387 | put_huge_zero_page(); |
1388 | } else { | |
309381fe | 1389 | VM_BUG_ON_PAGE(!PageHead(page), page); |
d281ee61 | 1390 | page_remove_rmap(page, true); |
93b4796d KS |
1391 | put_page(page); |
1392 | } | |
71e3aac0 AA |
1393 | ret |= VM_FAULT_WRITE; |
1394 | } | |
c4088ebd | 1395 | spin_unlock(ptl); |
2ec74c3e SG |
1396 | out_mn: |
1397 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
71e3aac0 AA |
1398 | out: |
1399 | return ret; | |
2ec74c3e | 1400 | out_unlock: |
c4088ebd | 1401 | spin_unlock(ptl); |
2ec74c3e | 1402 | return ret; |
71e3aac0 AA |
1403 | } |
1404 | ||
b676b293 | 1405 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, |
71e3aac0 AA |
1406 | unsigned long addr, |
1407 | pmd_t *pmd, | |
1408 | unsigned int flags) | |
1409 | { | |
b676b293 | 1410 | struct mm_struct *mm = vma->vm_mm; |
71e3aac0 AA |
1411 | struct page *page = NULL; |
1412 | ||
c4088ebd | 1413 | assert_spin_locked(pmd_lockptr(mm, pmd)); |
71e3aac0 AA |
1414 | |
1415 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1416 | goto out; | |
1417 | ||
85facf25 KS |
1418 | /* Avoid dumping huge zero page */ |
1419 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) | |
1420 | return ERR_PTR(-EFAULT); | |
1421 | ||
2b4847e7 | 1422 | /* Full NUMA hinting faults to serialise migration in fault paths */ |
8a0516ed | 1423 | if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) |
2b4847e7 MG |
1424 | goto out; |
1425 | ||
71e3aac0 | 1426 | page = pmd_page(*pmd); |
309381fe | 1427 | VM_BUG_ON_PAGE(!PageHead(page), page); |
3565fce3 DW |
1428 | if (flags & FOLL_TOUCH) |
1429 | touch_pmd(vma, addr, pmd); | |
de60f5f1 | 1430 | if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { |
e90309c9 KS |
1431 | /* |
1432 | * We don't mlock() pte-mapped THPs. This way we can avoid | |
1433 | * leaking mlocked pages into non-VM_LOCKED VMAs. | |
1434 | * | |
1435 | * In most cases the pmd is the only mapping of the page as we | |
1436 | * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for | |
1437 | * writable private mappings in populate_vma_page_range(). | |
1438 | * | |
1439 | * The only scenario when we have the page shared here is if we | |
1440 | * mlocking read-only mapping shared over fork(). We skip | |
1441 | * mlocking such pages. | |
1442 | */ | |
1443 | if (compound_mapcount(page) == 1 && !PageDoubleMap(page) && | |
1444 | page->mapping && trylock_page(page)) { | |
b676b293 DR |
1445 | lru_add_drain(); |
1446 | if (page->mapping) | |
1447 | mlock_vma_page(page); | |
1448 | unlock_page(page); | |
1449 | } | |
1450 | } | |
71e3aac0 | 1451 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
309381fe | 1452 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
71e3aac0 | 1453 | if (flags & FOLL_GET) |
ddc58f27 | 1454 | get_page(page); |
71e3aac0 AA |
1455 | |
1456 | out: | |
1457 | return page; | |
1458 | } | |
1459 | ||
d10e63f2 | 1460 | /* NUMA hinting page fault entry point for trans huge pmds */ |
4daae3b4 MG |
1461 | int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, |
1462 | unsigned long addr, pmd_t pmd, pmd_t *pmdp) | |
d10e63f2 | 1463 | { |
c4088ebd | 1464 | spinlock_t *ptl; |
b8916634 | 1465 | struct anon_vma *anon_vma = NULL; |
b32967ff | 1466 | struct page *page; |
d10e63f2 | 1467 | unsigned long haddr = addr & HPAGE_PMD_MASK; |
8191acbd | 1468 | int page_nid = -1, this_nid = numa_node_id(); |
90572890 | 1469 | int target_nid, last_cpupid = -1; |
8191acbd MG |
1470 | bool page_locked; |
1471 | bool migrated = false; | |
b191f9b1 | 1472 | bool was_writable; |
6688cc05 | 1473 | int flags = 0; |
d10e63f2 | 1474 | |
c0e7cad9 MG |
1475 | /* A PROT_NONE fault should not end up here */ |
1476 | BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))); | |
1477 | ||
c4088ebd | 1478 | ptl = pmd_lock(mm, pmdp); |
d10e63f2 MG |
1479 | if (unlikely(!pmd_same(pmd, *pmdp))) |
1480 | goto out_unlock; | |
1481 | ||
de466bd6 MG |
1482 | /* |
1483 | * If there are potential migrations, wait for completion and retry | |
1484 | * without disrupting NUMA hinting information. Do not relock and | |
1485 | * check_same as the page may no longer be mapped. | |
1486 | */ | |
1487 | if (unlikely(pmd_trans_migrating(*pmdp))) { | |
5d833062 | 1488 | page = pmd_page(*pmdp); |
de466bd6 | 1489 | spin_unlock(ptl); |
5d833062 | 1490 | wait_on_page_locked(page); |
de466bd6 MG |
1491 | goto out; |
1492 | } | |
1493 | ||
d10e63f2 | 1494 | page = pmd_page(pmd); |
a1a46184 | 1495 | BUG_ON(is_huge_zero_page(page)); |
8191acbd | 1496 | page_nid = page_to_nid(page); |
90572890 | 1497 | last_cpupid = page_cpupid_last(page); |
03c5a6e1 | 1498 | count_vm_numa_event(NUMA_HINT_FAULTS); |
04bb2f94 | 1499 | if (page_nid == this_nid) { |
03c5a6e1 | 1500 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
04bb2f94 RR |
1501 | flags |= TNF_FAULT_LOCAL; |
1502 | } | |
4daae3b4 | 1503 | |
bea66fbd MG |
1504 | /* See similar comment in do_numa_page for explanation */ |
1505 | if (!(vma->vm_flags & VM_WRITE)) | |
6688cc05 PZ |
1506 | flags |= TNF_NO_GROUP; |
1507 | ||
ff9042b1 MG |
1508 | /* |
1509 | * Acquire the page lock to serialise THP migrations but avoid dropping | |
1510 | * page_table_lock if at all possible | |
1511 | */ | |
b8916634 MG |
1512 | page_locked = trylock_page(page); |
1513 | target_nid = mpol_misplaced(page, vma, haddr); | |
1514 | if (target_nid == -1) { | |
1515 | /* If the page was locked, there are no parallel migrations */ | |
a54a407f | 1516 | if (page_locked) |
b8916634 | 1517 | goto clear_pmdnuma; |
2b4847e7 | 1518 | } |
4daae3b4 | 1519 | |
de466bd6 | 1520 | /* Migration could have started since the pmd_trans_migrating check */ |
2b4847e7 | 1521 | if (!page_locked) { |
c4088ebd | 1522 | spin_unlock(ptl); |
b8916634 | 1523 | wait_on_page_locked(page); |
a54a407f | 1524 | page_nid = -1; |
b8916634 MG |
1525 | goto out; |
1526 | } | |
1527 | ||
2b4847e7 MG |
1528 | /* |
1529 | * Page is misplaced. Page lock serialises migrations. Acquire anon_vma | |
1530 | * to serialises splits | |
1531 | */ | |
b8916634 | 1532 | get_page(page); |
c4088ebd | 1533 | spin_unlock(ptl); |
b8916634 | 1534 | anon_vma = page_lock_anon_vma_read(page); |
4daae3b4 | 1535 | |
c69307d5 | 1536 | /* Confirm the PMD did not change while page_table_lock was released */ |
c4088ebd | 1537 | spin_lock(ptl); |
b32967ff MG |
1538 | if (unlikely(!pmd_same(pmd, *pmdp))) { |
1539 | unlock_page(page); | |
1540 | put_page(page); | |
a54a407f | 1541 | page_nid = -1; |
4daae3b4 | 1542 | goto out_unlock; |
b32967ff | 1543 | } |
ff9042b1 | 1544 | |
c3a489ca MG |
1545 | /* Bail if we fail to protect against THP splits for any reason */ |
1546 | if (unlikely(!anon_vma)) { | |
1547 | put_page(page); | |
1548 | page_nid = -1; | |
1549 | goto clear_pmdnuma; | |
1550 | } | |
1551 | ||
a54a407f MG |
1552 | /* |
1553 | * Migrate the THP to the requested node, returns with page unlocked | |
8a0516ed | 1554 | * and access rights restored. |
a54a407f | 1555 | */ |
c4088ebd | 1556 | spin_unlock(ptl); |
b32967ff | 1557 | migrated = migrate_misplaced_transhuge_page(mm, vma, |
340ef390 | 1558 | pmdp, pmd, addr, page, target_nid); |
6688cc05 PZ |
1559 | if (migrated) { |
1560 | flags |= TNF_MIGRATED; | |
8191acbd | 1561 | page_nid = target_nid; |
074c2381 MG |
1562 | } else |
1563 | flags |= TNF_MIGRATE_FAIL; | |
b32967ff | 1564 | |
8191acbd | 1565 | goto out; |
b32967ff | 1566 | clear_pmdnuma: |
a54a407f | 1567 | BUG_ON(!PageLocked(page)); |
b191f9b1 | 1568 | was_writable = pmd_write(pmd); |
4d942466 | 1569 | pmd = pmd_modify(pmd, vma->vm_page_prot); |
b7b04004 | 1570 | pmd = pmd_mkyoung(pmd); |
b191f9b1 MG |
1571 | if (was_writable) |
1572 | pmd = pmd_mkwrite(pmd); | |
d10e63f2 | 1573 | set_pmd_at(mm, haddr, pmdp, pmd); |
d10e63f2 | 1574 | update_mmu_cache_pmd(vma, addr, pmdp); |
a54a407f | 1575 | unlock_page(page); |
d10e63f2 | 1576 | out_unlock: |
c4088ebd | 1577 | spin_unlock(ptl); |
b8916634 MG |
1578 | |
1579 | out: | |
1580 | if (anon_vma) | |
1581 | page_unlock_anon_vma_read(anon_vma); | |
1582 | ||
8191acbd | 1583 | if (page_nid != -1) |
6688cc05 | 1584 | task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags); |
8191acbd | 1585 | |
d10e63f2 MG |
1586 | return 0; |
1587 | } | |
1588 | ||
b8d3c4c3 MK |
1589 | int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
1590 | pmd_t *pmd, unsigned long addr, unsigned long next) | |
1591 | ||
1592 | { | |
1593 | spinlock_t *ptl; | |
1594 | pmd_t orig_pmd; | |
1595 | struct page *page; | |
1596 | struct mm_struct *mm = tlb->mm; | |
1597 | int ret = 0; | |
1598 | ||
b6ec57f4 KS |
1599 | ptl = pmd_trans_huge_lock(pmd, vma); |
1600 | if (!ptl) | |
25eedabe | 1601 | goto out_unlocked; |
b8d3c4c3 MK |
1602 | |
1603 | orig_pmd = *pmd; | |
1604 | if (is_huge_zero_pmd(orig_pmd)) { | |
1605 | ret = 1; | |
1606 | goto out; | |
1607 | } | |
1608 | ||
1609 | page = pmd_page(orig_pmd); | |
1610 | /* | |
1611 | * If other processes are mapping this page, we couldn't discard | |
1612 | * the page unless they all do MADV_FREE so let's skip the page. | |
1613 | */ | |
1614 | if (page_mapcount(page) != 1) | |
1615 | goto out; | |
1616 | ||
1617 | if (!trylock_page(page)) | |
1618 | goto out; | |
1619 | ||
1620 | /* | |
1621 | * If user want to discard part-pages of THP, split it so MADV_FREE | |
1622 | * will deactivate only them. | |
1623 | */ | |
1624 | if (next - addr != HPAGE_PMD_SIZE) { | |
1625 | get_page(page); | |
1626 | spin_unlock(ptl); | |
1627 | if (split_huge_page(page)) { | |
1628 | put_page(page); | |
1629 | unlock_page(page); | |
1630 | goto out_unlocked; | |
1631 | } | |
1632 | put_page(page); | |
1633 | unlock_page(page); | |
1634 | ret = 1; | |
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); | |
1697 | tlb_remove_page(tlb, page); | |
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 | ||
26234f36 XG |
2350 | static void collapse_huge_page(struct mm_struct *mm, |
2351 | unsigned long address, | |
2352 | struct page **hpage, | |
2353 | struct vm_area_struct *vma, | |
2354 | int node) | |
2355 | { | |
26234f36 XG |
2356 | pmd_t *pmd, _pmd; |
2357 | pte_t *pte; | |
2358 | pgtable_t pgtable; | |
2359 | struct page *new_page; | |
c4088ebd | 2360 | spinlock_t *pmd_ptl, *pte_ptl; |
629d9d1c | 2361 | int isolated = 0, result = 0; |
26234f36 | 2362 | unsigned long hstart, hend; |
00501b53 | 2363 | struct mem_cgroup *memcg; |
2ec74c3e SG |
2364 | unsigned long mmun_start; /* For mmu_notifiers */ |
2365 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 2366 | gfp_t gfp; |
26234f36 XG |
2367 | |
2368 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2369 | ||
3b363692 | 2370 | /* Only allocate from the target node */ |
444eb2a4 | 2371 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_OTHER_NODE | __GFP_THISNODE; |
3b363692 | 2372 | |
26234f36 | 2373 | /* release the mmap_sem read lock. */ |
d6669d68 | 2374 | new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node); |
7d2eba05 EA |
2375 | if (!new_page) { |
2376 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
2377 | goto out_nolock; | |
2378 | } | |
26234f36 | 2379 | |
f627c2f5 | 2380 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { |
7d2eba05 EA |
2381 | result = SCAN_CGROUP_CHARGE_FAIL; |
2382 | goto out_nolock; | |
2383 | } | |
ba76149f AA |
2384 | |
2385 | /* | |
2386 | * Prevent all access to pagetables with the exception of | |
2387 | * gup_fast later hanlded by the ptep_clear_flush and the VM | |
2388 | * handled by the anon_vma lock + PG_lock. | |
2389 | */ | |
2390 | down_write(&mm->mmap_sem); | |
7d2eba05 EA |
2391 | if (unlikely(khugepaged_test_exit(mm))) { |
2392 | result = SCAN_ANY_PROCESS; | |
ba76149f | 2393 | goto out; |
7d2eba05 | 2394 | } |
ba76149f AA |
2395 | |
2396 | vma = find_vma(mm, address); | |
7d2eba05 EA |
2397 | if (!vma) { |
2398 | result = SCAN_VMA_NULL; | |
a8f531eb | 2399 | goto out; |
7d2eba05 | 2400 | } |
ba76149f AA |
2401 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2402 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
7d2eba05 EA |
2403 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) { |
2404 | result = SCAN_ADDRESS_RANGE; | |
ba76149f | 2405 | goto out; |
7d2eba05 EA |
2406 | } |
2407 | if (!hugepage_vma_check(vma)) { | |
2408 | result = SCAN_VMA_CHECK; | |
a7d6e4ec | 2409 | goto out; |
7d2eba05 | 2410 | } |
6219049a | 2411 | pmd = mm_find_pmd(mm, address); |
7d2eba05 EA |
2412 | if (!pmd) { |
2413 | result = SCAN_PMD_NULL; | |
ba76149f | 2414 | goto out; |
7d2eba05 | 2415 | } |
ba76149f | 2416 | |
4fc3f1d6 | 2417 | anon_vma_lock_write(vma->anon_vma); |
ba76149f AA |
2418 | |
2419 | pte = pte_offset_map(pmd, address); | |
c4088ebd | 2420 | pte_ptl = pte_lockptr(mm, pmd); |
ba76149f | 2421 | |
2ec74c3e SG |
2422 | mmun_start = address; |
2423 | mmun_end = address + HPAGE_PMD_SIZE; | |
2424 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
c4088ebd | 2425 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
ba76149f AA |
2426 | /* |
2427 | * After this gup_fast can't run anymore. This also removes | |
2428 | * any huge TLB entry from the CPU so we won't allow | |
2429 | * huge and small TLB entries for the same virtual address | |
2430 | * to avoid the risk of CPU bugs in that area. | |
2431 | */ | |
15a25b2e | 2432 | _pmd = pmdp_collapse_flush(vma, address, pmd); |
c4088ebd | 2433 | spin_unlock(pmd_ptl); |
2ec74c3e | 2434 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
ba76149f | 2435 | |
c4088ebd | 2436 | spin_lock(pte_ptl); |
ba76149f | 2437 | isolated = __collapse_huge_page_isolate(vma, address, pte); |
c4088ebd | 2438 | spin_unlock(pte_ptl); |
ba76149f AA |
2439 | |
2440 | if (unlikely(!isolated)) { | |
453c7192 | 2441 | pte_unmap(pte); |
c4088ebd | 2442 | spin_lock(pmd_ptl); |
ba76149f | 2443 | BUG_ON(!pmd_none(*pmd)); |
7c342512 AK |
2444 | /* |
2445 | * We can only use set_pmd_at when establishing | |
2446 | * hugepmds and never for establishing regular pmds that | |
2447 | * points to regular pagetables. Use pmd_populate for that | |
2448 | */ | |
2449 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
c4088ebd | 2450 | spin_unlock(pmd_ptl); |
08b52706 | 2451 | anon_vma_unlock_write(vma->anon_vma); |
7d2eba05 | 2452 | result = SCAN_FAIL; |
ce83d217 | 2453 | goto out; |
ba76149f AA |
2454 | } |
2455 | ||
2456 | /* | |
2457 | * All pages are isolated and locked so anon_vma rmap | |
2458 | * can't run anymore. | |
2459 | */ | |
08b52706 | 2460 | anon_vma_unlock_write(vma->anon_vma); |
ba76149f | 2461 | |
c4088ebd | 2462 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); |
453c7192 | 2463 | pte_unmap(pte); |
ba76149f AA |
2464 | __SetPageUptodate(new_page); |
2465 | pgtable = pmd_pgtable(_pmd); | |
ba76149f | 2466 | |
3122359a KS |
2467 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); |
2468 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); | |
ba76149f AA |
2469 | |
2470 | /* | |
2471 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
2472 | * this is needed to avoid the copy_huge_page writes to become | |
2473 | * visible after the set_pmd_at() write. | |
2474 | */ | |
2475 | smp_wmb(); | |
2476 | ||
c4088ebd | 2477 | spin_lock(pmd_ptl); |
ba76149f | 2478 | BUG_ON(!pmd_none(*pmd)); |
d281ee61 | 2479 | page_add_new_anon_rmap(new_page, vma, address, true); |
f627c2f5 | 2480 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
00501b53 | 2481 | lru_cache_add_active_or_unevictable(new_page, vma); |
fce144b4 | 2482 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
ba76149f | 2483 | set_pmd_at(mm, address, pmd, _pmd); |
b113da65 | 2484 | update_mmu_cache_pmd(vma, address, pmd); |
c4088ebd | 2485 | spin_unlock(pmd_ptl); |
ba76149f AA |
2486 | |
2487 | *hpage = NULL; | |
420256ef | 2488 | |
ba76149f | 2489 | khugepaged_pages_collapsed++; |
7d2eba05 | 2490 | result = SCAN_SUCCEED; |
ce83d217 | 2491 | out_up_write: |
ba76149f | 2492 | up_write(&mm->mmap_sem); |
7d2eba05 | 2493 | trace_mm_collapse_huge_page(mm, isolated, result); |
0bbbc0b3 AA |
2494 | return; |
2495 | ||
7d2eba05 EA |
2496 | out_nolock: |
2497 | trace_mm_collapse_huge_page(mm, isolated, result); | |
2498 | return; | |
ce83d217 | 2499 | out: |
f627c2f5 | 2500 | mem_cgroup_cancel_charge(new_page, memcg, true); |
ce83d217 | 2501 | goto out_up_write; |
ba76149f AA |
2502 | } |
2503 | ||
2504 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
2505 | struct vm_area_struct *vma, | |
2506 | unsigned long address, | |
2507 | struct page **hpage) | |
2508 | { | |
ba76149f AA |
2509 | pmd_t *pmd; |
2510 | pte_t *pte, *_pte; | |
7d2eba05 EA |
2511 | int ret = 0, none_or_zero = 0, result = 0; |
2512 | struct page *page = NULL; | |
ba76149f AA |
2513 | unsigned long _address; |
2514 | spinlock_t *ptl; | |
00ef2d2f | 2515 | int node = NUMA_NO_NODE; |
10359213 | 2516 | bool writable = false, referenced = false; |
ba76149f AA |
2517 | |
2518 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2519 | ||
6219049a | 2520 | pmd = mm_find_pmd(mm, address); |
7d2eba05 EA |
2521 | if (!pmd) { |
2522 | result = SCAN_PMD_NULL; | |
ba76149f | 2523 | goto out; |
7d2eba05 | 2524 | } |
ba76149f | 2525 | |
9f1b868a | 2526 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); |
ba76149f AA |
2527 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
2528 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
2529 | _pte++, _address += PAGE_SIZE) { | |
2530 | pte_t pteval = *_pte; | |
ca0984ca | 2531 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
c1294d05 | 2532 | if (!userfaultfd_armed(vma) && |
7d2eba05 | 2533 | ++none_or_zero <= khugepaged_max_ptes_none) { |
ba76149f | 2534 | continue; |
7d2eba05 EA |
2535 | } else { |
2536 | result = SCAN_EXCEED_NONE_PTE; | |
ba76149f | 2537 | goto out_unmap; |
7d2eba05 | 2538 | } |
ba76149f | 2539 | } |
7d2eba05 EA |
2540 | if (!pte_present(pteval)) { |
2541 | result = SCAN_PTE_NON_PRESENT; | |
ba76149f | 2542 | goto out_unmap; |
7d2eba05 | 2543 | } |
10359213 EA |
2544 | if (pte_write(pteval)) |
2545 | writable = true; | |
2546 | ||
ba76149f | 2547 | page = vm_normal_page(vma, _address, pteval); |
7d2eba05 EA |
2548 | if (unlikely(!page)) { |
2549 | result = SCAN_PAGE_NULL; | |
ba76149f | 2550 | goto out_unmap; |
7d2eba05 | 2551 | } |
b1caa957 KS |
2552 | |
2553 | /* TODO: teach khugepaged to collapse THP mapped with pte */ | |
2554 | if (PageCompound(page)) { | |
2555 | result = SCAN_PAGE_COMPOUND; | |
2556 | goto out_unmap; | |
2557 | } | |
2558 | ||
5c4b4be3 | 2559 | /* |
9f1b868a BL |
2560 | * Record which node the original page is from and save this |
2561 | * information to khugepaged_node_load[]. | |
2562 | * Khupaged will allocate hugepage from the node has the max | |
2563 | * hit record. | |
5c4b4be3 | 2564 | */ |
9f1b868a | 2565 | node = page_to_nid(page); |
7d2eba05 EA |
2566 | if (khugepaged_scan_abort(node)) { |
2567 | result = SCAN_SCAN_ABORT; | |
14a4e214 | 2568 | goto out_unmap; |
7d2eba05 | 2569 | } |
9f1b868a | 2570 | khugepaged_node_load[node]++; |
7d2eba05 | 2571 | if (!PageLRU(page)) { |
0fda2788 | 2572 | result = SCAN_PAGE_LRU; |
7d2eba05 EA |
2573 | goto out_unmap; |
2574 | } | |
2575 | if (PageLocked(page)) { | |
2576 | result = SCAN_PAGE_LOCK; | |
ba76149f | 2577 | goto out_unmap; |
7d2eba05 EA |
2578 | } |
2579 | if (!PageAnon(page)) { | |
2580 | result = SCAN_PAGE_ANON; | |
2581 | goto out_unmap; | |
2582 | } | |
2583 | ||
10359213 EA |
2584 | /* |
2585 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2586 | * The page must only be referenced by the scanned process | |
2587 | * and page swap cache. | |
2588 | */ | |
7d2eba05 EA |
2589 | if (page_count(page) != 1 + !!PageSwapCache(page)) { |
2590 | result = SCAN_PAGE_COUNT; | |
ba76149f | 2591 | goto out_unmap; |
7d2eba05 | 2592 | } |
33c3fc71 VD |
2593 | if (pte_young(pteval) || |
2594 | page_is_young(page) || PageReferenced(page) || | |
8ee53820 | 2595 | mmu_notifier_test_young(vma->vm_mm, address)) |
10359213 | 2596 | referenced = true; |
ba76149f | 2597 | } |
7d2eba05 EA |
2598 | if (writable) { |
2599 | if (referenced) { | |
2600 | result = SCAN_SUCCEED; | |
2601 | ret = 1; | |
2602 | } else { | |
2603 | result = SCAN_NO_REFERENCED_PAGE; | |
2604 | } | |
2605 | } else { | |
2606 | result = SCAN_PAGE_RO; | |
2607 | } | |
ba76149f AA |
2608 | out_unmap: |
2609 | pte_unmap_unlock(pte, ptl); | |
9f1b868a BL |
2610 | if (ret) { |
2611 | node = khugepaged_find_target_node(); | |
ce83d217 | 2612 | /* collapse_huge_page will return with the mmap_sem released */ |
5c4b4be3 | 2613 | collapse_huge_page(mm, address, hpage, vma, node); |
9f1b868a | 2614 | } |
ba76149f | 2615 | out: |
16fd0fe4 | 2616 | trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, |
7d2eba05 | 2617 | none_or_zero, result); |
ba76149f AA |
2618 | return ret; |
2619 | } | |
2620 | ||
2621 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
2622 | { | |
2623 | struct mm_struct *mm = mm_slot->mm; | |
2624 | ||
b9980cdc | 2625 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2626 | |
2627 | if (khugepaged_test_exit(mm)) { | |
2628 | /* free mm_slot */ | |
43b5fbbd | 2629 | hash_del(&mm_slot->hash); |
ba76149f AA |
2630 | list_del(&mm_slot->mm_node); |
2631 | ||
2632 | /* | |
2633 | * Not strictly needed because the mm exited already. | |
2634 | * | |
2635 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
2636 | */ | |
2637 | ||
2638 | /* khugepaged_mm_lock actually not necessary for the below */ | |
2639 | free_mm_slot(mm_slot); | |
2640 | mmdrop(mm); | |
2641 | } | |
2642 | } | |
2643 | ||
2644 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
2645 | struct page **hpage) | |
2f1da642 HS |
2646 | __releases(&khugepaged_mm_lock) |
2647 | __acquires(&khugepaged_mm_lock) | |
ba76149f AA |
2648 | { |
2649 | struct mm_slot *mm_slot; | |
2650 | struct mm_struct *mm; | |
2651 | struct vm_area_struct *vma; | |
2652 | int progress = 0; | |
2653 | ||
2654 | VM_BUG_ON(!pages); | |
b9980cdc | 2655 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2656 | |
2657 | if (khugepaged_scan.mm_slot) | |
2658 | mm_slot = khugepaged_scan.mm_slot; | |
2659 | else { | |
2660 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2661 | struct mm_slot, mm_node); | |
2662 | khugepaged_scan.address = 0; | |
2663 | khugepaged_scan.mm_slot = mm_slot; | |
2664 | } | |
2665 | spin_unlock(&khugepaged_mm_lock); | |
2666 | ||
2667 | mm = mm_slot->mm; | |
2668 | down_read(&mm->mmap_sem); | |
2669 | if (unlikely(khugepaged_test_exit(mm))) | |
2670 | vma = NULL; | |
2671 | else | |
2672 | vma = find_vma(mm, khugepaged_scan.address); | |
2673 | ||
2674 | progress++; | |
2675 | for (; vma; vma = vma->vm_next) { | |
2676 | unsigned long hstart, hend; | |
2677 | ||
2678 | cond_resched(); | |
2679 | if (unlikely(khugepaged_test_exit(mm))) { | |
2680 | progress++; | |
2681 | break; | |
2682 | } | |
fa475e51 BL |
2683 | if (!hugepage_vma_check(vma)) { |
2684 | skip: | |
ba76149f AA |
2685 | progress++; |
2686 | continue; | |
2687 | } | |
ba76149f AA |
2688 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2689 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
a7d6e4ec AA |
2690 | if (hstart >= hend) |
2691 | goto skip; | |
2692 | if (khugepaged_scan.address > hend) | |
2693 | goto skip; | |
ba76149f AA |
2694 | if (khugepaged_scan.address < hstart) |
2695 | khugepaged_scan.address = hstart; | |
a7d6e4ec | 2696 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); |
ba76149f AA |
2697 | |
2698 | while (khugepaged_scan.address < hend) { | |
2699 | int ret; | |
2700 | cond_resched(); | |
2701 | if (unlikely(khugepaged_test_exit(mm))) | |
2702 | goto breakouterloop; | |
2703 | ||
2704 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2705 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2706 | hend); | |
2707 | ret = khugepaged_scan_pmd(mm, vma, | |
2708 | khugepaged_scan.address, | |
2709 | hpage); | |
2710 | /* move to next address */ | |
2711 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2712 | progress += HPAGE_PMD_NR; | |
2713 | if (ret) | |
2714 | /* we released mmap_sem so break loop */ | |
2715 | goto breakouterloop_mmap_sem; | |
2716 | if (progress >= pages) | |
2717 | goto breakouterloop; | |
2718 | } | |
2719 | } | |
2720 | breakouterloop: | |
2721 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2722 | breakouterloop_mmap_sem: | |
2723 | ||
2724 | spin_lock(&khugepaged_mm_lock); | |
a7d6e4ec | 2725 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); |
ba76149f AA |
2726 | /* |
2727 | * Release the current mm_slot if this mm is about to die, or | |
2728 | * if we scanned all vmas of this mm. | |
2729 | */ | |
2730 | if (khugepaged_test_exit(mm) || !vma) { | |
2731 | /* | |
2732 | * Make sure that if mm_users is reaching zero while | |
2733 | * khugepaged runs here, khugepaged_exit will find | |
2734 | * mm_slot not pointing to the exiting mm. | |
2735 | */ | |
2736 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2737 | khugepaged_scan.mm_slot = list_entry( | |
2738 | mm_slot->mm_node.next, | |
2739 | struct mm_slot, mm_node); | |
2740 | khugepaged_scan.address = 0; | |
2741 | } else { | |
2742 | khugepaged_scan.mm_slot = NULL; | |
2743 | khugepaged_full_scans++; | |
2744 | } | |
2745 | ||
2746 | collect_mm_slot(mm_slot); | |
2747 | } | |
2748 | ||
2749 | return progress; | |
2750 | } | |
2751 | ||
2752 | static int khugepaged_has_work(void) | |
2753 | { | |
2754 | return !list_empty(&khugepaged_scan.mm_head) && | |
2755 | khugepaged_enabled(); | |
2756 | } | |
2757 | ||
2758 | static int khugepaged_wait_event(void) | |
2759 | { | |
2760 | return !list_empty(&khugepaged_scan.mm_head) || | |
2017c0bf | 2761 | kthread_should_stop(); |
ba76149f AA |
2762 | } |
2763 | ||
d516904b | 2764 | static void khugepaged_do_scan(void) |
ba76149f | 2765 | { |
d516904b | 2766 | struct page *hpage = NULL; |
ba76149f AA |
2767 | unsigned int progress = 0, pass_through_head = 0; |
2768 | unsigned int pages = khugepaged_pages_to_scan; | |
d516904b | 2769 | bool wait = true; |
ba76149f AA |
2770 | |
2771 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2772 | ||
2773 | while (progress < pages) { | |
26234f36 | 2774 | if (!khugepaged_prealloc_page(&hpage, &wait)) |
d516904b | 2775 | break; |
26234f36 | 2776 | |
420256ef | 2777 | cond_resched(); |
ba76149f | 2778 | |
cd092411 | 2779 | if (unlikely(kthread_should_stop() || try_to_freeze())) |
878aee7d AA |
2780 | break; |
2781 | ||
ba76149f AA |
2782 | spin_lock(&khugepaged_mm_lock); |
2783 | if (!khugepaged_scan.mm_slot) | |
2784 | pass_through_head++; | |
2785 | if (khugepaged_has_work() && | |
2786 | pass_through_head < 2) | |
2787 | progress += khugepaged_scan_mm_slot(pages - progress, | |
d516904b | 2788 | &hpage); |
ba76149f AA |
2789 | else |
2790 | progress = pages; | |
2791 | spin_unlock(&khugepaged_mm_lock); | |
2792 | } | |
ba76149f | 2793 | |
d516904b XG |
2794 | if (!IS_ERR_OR_NULL(hpage)) |
2795 | put_page(hpage); | |
0bbbc0b3 AA |
2796 | } |
2797 | ||
f0508977 DR |
2798 | static bool khugepaged_should_wakeup(void) |
2799 | { | |
2800 | return kthread_should_stop() || | |
2801 | time_after_eq(jiffies, khugepaged_sleep_expire); | |
2802 | } | |
2803 | ||
2017c0bf XG |
2804 | static void khugepaged_wait_work(void) |
2805 | { | |
2017c0bf | 2806 | if (khugepaged_has_work()) { |
f0508977 DR |
2807 | const unsigned long scan_sleep_jiffies = |
2808 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs); | |
2809 | ||
2810 | if (!scan_sleep_jiffies) | |
2017c0bf XG |
2811 | return; |
2812 | ||
f0508977 | 2813 | khugepaged_sleep_expire = jiffies + scan_sleep_jiffies; |
2017c0bf | 2814 | wait_event_freezable_timeout(khugepaged_wait, |
f0508977 DR |
2815 | khugepaged_should_wakeup(), |
2816 | scan_sleep_jiffies); | |
2017c0bf XG |
2817 | return; |
2818 | } | |
2819 | ||
2820 | if (khugepaged_enabled()) | |
2821 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2822 | } | |
2823 | ||
ba76149f AA |
2824 | static int khugepaged(void *none) |
2825 | { | |
2826 | struct mm_slot *mm_slot; | |
2827 | ||
878aee7d | 2828 | set_freezable(); |
8698a745 | 2829 | set_user_nice(current, MAX_NICE); |
ba76149f | 2830 | |
b7231789 XG |
2831 | while (!kthread_should_stop()) { |
2832 | khugepaged_do_scan(); | |
2833 | khugepaged_wait_work(); | |
2834 | } | |
ba76149f AA |
2835 | |
2836 | spin_lock(&khugepaged_mm_lock); | |
2837 | mm_slot = khugepaged_scan.mm_slot; | |
2838 | khugepaged_scan.mm_slot = NULL; | |
2839 | if (mm_slot) | |
2840 | collect_mm_slot(mm_slot); | |
2841 | spin_unlock(&khugepaged_mm_lock); | |
ba76149f AA |
2842 | return 0; |
2843 | } | |
2844 | ||
eef1b3ba KS |
2845 | static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, |
2846 | unsigned long haddr, pmd_t *pmd) | |
2847 | { | |
2848 | struct mm_struct *mm = vma->vm_mm; | |
2849 | pgtable_t pgtable; | |
2850 | pmd_t _pmd; | |
2851 | int i; | |
2852 | ||
2853 | /* leave pmd empty until pte is filled */ | |
2854 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
2855 | ||
2856 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); | |
2857 | pmd_populate(mm, &_pmd, pgtable); | |
2858 | ||
2859 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
2860 | pte_t *pte, entry; | |
2861 | entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); | |
2862 | entry = pte_mkspecial(entry); | |
2863 | pte = pte_offset_map(&_pmd, haddr); | |
2864 | VM_BUG_ON(!pte_none(*pte)); | |
2865 | set_pte_at(mm, haddr, pte, entry); | |
2866 | pte_unmap(pte); | |
2867 | } | |
2868 | smp_wmb(); /* make pte visible before pmd */ | |
2869 | pmd_populate(mm, pmd, pgtable); | |
2870 | put_huge_zero_page(); | |
2871 | } | |
2872 | ||
2873 | static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, | |
ba988280 | 2874 | unsigned long haddr, bool freeze) |
eef1b3ba KS |
2875 | { |
2876 | struct mm_struct *mm = vma->vm_mm; | |
2877 | struct page *page; | |
2878 | pgtable_t pgtable; | |
2879 | pmd_t _pmd; | |
b8d3c4c3 | 2880 | bool young, write, dirty; |
2ac015e2 | 2881 | unsigned long addr; |
eef1b3ba KS |
2882 | int i; |
2883 | ||
2884 | VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); | |
2885 | VM_BUG_ON_VMA(vma->vm_start > haddr, vma); | |
2886 | VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); | |
5c7fb56e | 2887 | VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)); |
eef1b3ba KS |
2888 | |
2889 | count_vm_event(THP_SPLIT_PMD); | |
2890 | ||
2891 | if (vma_is_dax(vma)) { | |
2892 | pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
2893 | if (is_huge_zero_pmd(_pmd)) | |
2894 | put_huge_zero_page(); | |
2895 | return; | |
2896 | } else if (is_huge_zero_pmd(*pmd)) { | |
2897 | return __split_huge_zero_page_pmd(vma, haddr, pmd); | |
2898 | } | |
2899 | ||
2900 | page = pmd_page(*pmd); | |
2901 | VM_BUG_ON_PAGE(!page_count(page), page); | |
fe896d18 | 2902 | page_ref_add(page, HPAGE_PMD_NR - 1); |
eef1b3ba KS |
2903 | write = pmd_write(*pmd); |
2904 | young = pmd_young(*pmd); | |
b8d3c4c3 | 2905 | dirty = pmd_dirty(*pmd); |
eef1b3ba | 2906 | |
c777e2a8 | 2907 | pmdp_huge_split_prepare(vma, haddr, pmd); |
eef1b3ba KS |
2908 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
2909 | pmd_populate(mm, &_pmd, pgtable); | |
2910 | ||
2ac015e2 | 2911 | for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { |
eef1b3ba KS |
2912 | pte_t entry, *pte; |
2913 | /* | |
2914 | * Note that NUMA hinting access restrictions are not | |
2915 | * transferred to avoid any possibility of altering | |
2916 | * permissions across VMAs. | |
2917 | */ | |
ba988280 KS |
2918 | if (freeze) { |
2919 | swp_entry_t swp_entry; | |
2920 | swp_entry = make_migration_entry(page + i, write); | |
2921 | entry = swp_entry_to_pte(swp_entry); | |
2922 | } else { | |
2923 | entry = mk_pte(page + i, vma->vm_page_prot); | |
b8d3c4c3 | 2924 | entry = maybe_mkwrite(entry, vma); |
ba988280 KS |
2925 | if (!write) |
2926 | entry = pte_wrprotect(entry); | |
2927 | if (!young) | |
2928 | entry = pte_mkold(entry); | |
2929 | } | |
b8d3c4c3 MK |
2930 | if (dirty) |
2931 | SetPageDirty(page + i); | |
2ac015e2 | 2932 | pte = pte_offset_map(&_pmd, addr); |
eef1b3ba | 2933 | BUG_ON(!pte_none(*pte)); |
2ac015e2 | 2934 | set_pte_at(mm, addr, pte, entry); |
eef1b3ba KS |
2935 | atomic_inc(&page[i]._mapcount); |
2936 | pte_unmap(pte); | |
2937 | } | |
2938 | ||
2939 | /* | |
2940 | * Set PG_double_map before dropping compound_mapcount to avoid | |
2941 | * false-negative page_mapped(). | |
2942 | */ | |
2943 | if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { | |
2944 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
2945 | atomic_inc(&page[i]._mapcount); | |
2946 | } | |
2947 | ||
2948 | if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { | |
2949 | /* Last compound_mapcount is gone. */ | |
2950 | __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); | |
2951 | if (TestClearPageDoubleMap(page)) { | |
2952 | /* No need in mapcount reference anymore */ | |
2953 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
2954 | atomic_dec(&page[i]._mapcount); | |
2955 | } | |
2956 | } | |
2957 | ||
2958 | smp_wmb(); /* make pte visible before pmd */ | |
e9b61f19 KS |
2959 | /* |
2960 | * Up to this point the pmd is present and huge and userland has the | |
2961 | * whole access to the hugepage during the split (which happens in | |
2962 | * place). If we overwrite the pmd with the not-huge version pointing | |
2963 | * to the pte here (which of course we could if all CPUs were bug | |
2964 | * free), userland could trigger a small page size TLB miss on the | |
2965 | * small sized TLB while the hugepage TLB entry is still established in | |
2966 | * the huge TLB. Some CPU doesn't like that. | |
2967 | * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum | |
2968 | * 383 on page 93. Intel should be safe but is also warns that it's | |
2969 | * only safe if the permission and cache attributes of the two entries | |
2970 | * loaded in the two TLB is identical (which should be the case here). | |
2971 | * But it is generally safer to never allow small and huge TLB entries | |
2972 | * for the same virtual address to be loaded simultaneously. So instead | |
2973 | * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the | |
2974 | * current pmd notpresent (atomically because here the pmd_trans_huge | |
2975 | * and pmd_trans_splitting must remain set at all times on the pmd | |
2976 | * until the split is complete for this pmd), then we flush the SMP TLB | |
2977 | * and finally we write the non-huge version of the pmd entry with | |
2978 | * pmd_populate. | |
2979 | */ | |
2980 | pmdp_invalidate(vma, haddr, pmd); | |
eef1b3ba | 2981 | pmd_populate(mm, pmd, pgtable); |
e9b61f19 KS |
2982 | |
2983 | if (freeze) { | |
2ac015e2 | 2984 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
e9b61f19 KS |
2985 | page_remove_rmap(page + i, false); |
2986 | put_page(page + i); | |
2987 | } | |
2988 | } | |
eef1b3ba KS |
2989 | } |
2990 | ||
2991 | void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, | |
fec89c10 | 2992 | unsigned long address, bool freeze) |
eef1b3ba KS |
2993 | { |
2994 | spinlock_t *ptl; | |
2995 | struct mm_struct *mm = vma->vm_mm; | |
2996 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
2997 | ||
2998 | mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE); | |
2999 | ptl = pmd_lock(mm, pmd); | |
5c7fb56e | 3000 | if (pmd_trans_huge(*pmd)) { |
5f737714 | 3001 | struct page *page = pmd_page(*pmd); |
5c7fb56e | 3002 | if (PageMlocked(page)) |
5f737714 | 3003 | clear_page_mlock(page); |
5c7fb56e | 3004 | } else if (!pmd_devmap(*pmd)) |
e90309c9 | 3005 | goto out; |
fec89c10 | 3006 | __split_huge_pmd_locked(vma, pmd, haddr, freeze); |
e90309c9 | 3007 | out: |
eef1b3ba KS |
3008 | spin_unlock(ptl); |
3009 | mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE); | |
3010 | } | |
3011 | ||
fec89c10 KS |
3012 | void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, |
3013 | bool freeze, struct page *page) | |
94fcc585 | 3014 | { |
f72e7dcd HD |
3015 | pgd_t *pgd; |
3016 | pud_t *pud; | |
94fcc585 AA |
3017 | pmd_t *pmd; |
3018 | ||
78ddc534 | 3019 | pgd = pgd_offset(vma->vm_mm, address); |
f72e7dcd HD |
3020 | if (!pgd_present(*pgd)) |
3021 | return; | |
3022 | ||
3023 | pud = pud_offset(pgd, address); | |
3024 | if (!pud_present(*pud)) | |
3025 | return; | |
3026 | ||
3027 | pmd = pmd_offset(pud, address); | |
5c7fb56e | 3028 | if (!pmd_present(*pmd) || (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd))) |
94fcc585 | 3029 | return; |
fec89c10 KS |
3030 | |
3031 | /* | |
3032 | * If caller asks to setup a migration entries, we need a page to check | |
3033 | * pmd against. Otherwise we can end up replacing wrong page. | |
3034 | */ | |
3035 | VM_BUG_ON(freeze && !page); | |
3036 | if (page && page != pmd_page(*pmd)) | |
3037 | return; | |
3038 | ||
94fcc585 | 3039 | /* |
d5ee7c3b AA |
3040 | * Caller holds the mmap_sem write mode or the anon_vma lock, |
3041 | * so a huge pmd cannot materialize from under us (khugepaged | |
3042 | * holds both the mmap_sem write mode and the anon_vma lock | |
3043 | * write mode). | |
94fcc585 | 3044 | */ |
fec89c10 | 3045 | __split_huge_pmd(vma, pmd, address, freeze); |
94fcc585 AA |
3046 | } |
3047 | ||
e1b9996b | 3048 | void vma_adjust_trans_huge(struct vm_area_struct *vma, |
94fcc585 AA |
3049 | unsigned long start, |
3050 | unsigned long end, | |
3051 | long adjust_next) | |
3052 | { | |
3053 | /* | |
3054 | * If the new start address isn't hpage aligned and it could | |
3055 | * previously contain an hugepage: check if we need to split | |
3056 | * an huge pmd. | |
3057 | */ | |
3058 | if (start & ~HPAGE_PMD_MASK && | |
3059 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
3060 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
fec89c10 | 3061 | split_huge_pmd_address(vma, start, false, NULL); |
94fcc585 AA |
3062 | |
3063 | /* | |
3064 | * If the new end address isn't hpage aligned and it could | |
3065 | * previously contain an hugepage: check if we need to split | |
3066 | * an huge pmd. | |
3067 | */ | |
3068 | if (end & ~HPAGE_PMD_MASK && | |
3069 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
3070 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
fec89c10 | 3071 | split_huge_pmd_address(vma, end, false, NULL); |
94fcc585 AA |
3072 | |
3073 | /* | |
3074 | * If we're also updating the vma->vm_next->vm_start, if the new | |
3075 | * vm_next->vm_start isn't page aligned and it could previously | |
3076 | * contain an hugepage: check if we need to split an huge pmd. | |
3077 | */ | |
3078 | if (adjust_next > 0) { | |
3079 | struct vm_area_struct *next = vma->vm_next; | |
3080 | unsigned long nstart = next->vm_start; | |
3081 | nstart += adjust_next << PAGE_SHIFT; | |
3082 | if (nstart & ~HPAGE_PMD_MASK && | |
3083 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
3084 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
fec89c10 | 3085 | split_huge_pmd_address(next, nstart, false, NULL); |
94fcc585 AA |
3086 | } |
3087 | } | |
e9b61f19 | 3088 | |
fec89c10 | 3089 | static void freeze_page(struct page *page) |
e9b61f19 | 3090 | { |
fec89c10 KS |
3091 | enum ttu_flags ttu_flags = TTU_MIGRATION | TTU_IGNORE_MLOCK | |
3092 | TTU_IGNORE_ACCESS | TTU_RMAP_LOCKED; | |
3093 | int i, ret; | |
e9b61f19 KS |
3094 | |
3095 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
3096 | ||
fec89c10 KS |
3097 | /* We only need TTU_SPLIT_HUGE_PMD once */ |
3098 | ret = try_to_unmap(page, ttu_flags | TTU_SPLIT_HUGE_PMD); | |
3099 | for (i = 1; !ret && i < HPAGE_PMD_NR; i++) { | |
3100 | /* Cut short if the page is unmapped */ | |
3101 | if (page_count(page) == 1) | |
3102 | return; | |
e9b61f19 | 3103 | |
fec89c10 | 3104 | ret = try_to_unmap(page + i, ttu_flags); |
e9b61f19 | 3105 | } |
fec89c10 | 3106 | VM_BUG_ON(ret); |
e9b61f19 KS |
3107 | } |
3108 | ||
fec89c10 | 3109 | static void unfreeze_page(struct page *page) |
e9b61f19 | 3110 | { |
fec89c10 | 3111 | int i; |
e9b61f19 | 3112 | |
fec89c10 KS |
3113 | for (i = 0; i < HPAGE_PMD_NR; i++) |
3114 | remove_migration_ptes(page + i, page + i, true); | |
e9b61f19 KS |
3115 | } |
3116 | ||
8df651c7 | 3117 | static void __split_huge_page_tail(struct page *head, int tail, |
e9b61f19 KS |
3118 | struct lruvec *lruvec, struct list_head *list) |
3119 | { | |
e9b61f19 KS |
3120 | struct page *page_tail = head + tail; |
3121 | ||
8df651c7 | 3122 | VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); |
fe896d18 | 3123 | VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail); |
e9b61f19 KS |
3124 | |
3125 | /* | |
0139aa7b | 3126 | * tail_page->_refcount is zero and not changing from under us. But |
e9b61f19 | 3127 | * get_page_unless_zero() may be running from under us on the |
8df651c7 | 3128 | * tail_page. If we used atomic_set() below instead of atomic_inc(), we |
e9b61f19 KS |
3129 | * would then run atomic_set() concurrently with |
3130 | * get_page_unless_zero(), and atomic_set() is implemented in C not | |
3131 | * using locked ops. spin_unlock on x86 sometime uses locked ops | |
3132 | * because of PPro errata 66, 92, so unless somebody can guarantee | |
3133 | * atomic_set() here would be safe on all archs (and not only on x86), | |
8df651c7 | 3134 | * it's safer to use atomic_inc(). |
e9b61f19 | 3135 | */ |
fe896d18 | 3136 | page_ref_inc(page_tail); |
e9b61f19 KS |
3137 | |
3138 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; | |
3139 | page_tail->flags |= (head->flags & | |
3140 | ((1L << PG_referenced) | | |
3141 | (1L << PG_swapbacked) | | |
3142 | (1L << PG_mlocked) | | |
3143 | (1L << PG_uptodate) | | |
3144 | (1L << PG_active) | | |
3145 | (1L << PG_locked) | | |
b8d3c4c3 MK |
3146 | (1L << PG_unevictable) | |
3147 | (1L << PG_dirty))); | |
e9b61f19 KS |
3148 | |
3149 | /* | |
3150 | * After clearing PageTail the gup refcount can be released. | |
3151 | * Page flags also must be visible before we make the page non-compound. | |
3152 | */ | |
3153 | smp_wmb(); | |
3154 | ||
3155 | clear_compound_head(page_tail); | |
3156 | ||
3157 | if (page_is_young(head)) | |
3158 | set_page_young(page_tail); | |
3159 | if (page_is_idle(head)) | |
3160 | set_page_idle(page_tail); | |
3161 | ||
3162 | /* ->mapping in first tail page is compound_mapcount */ | |
9a982250 | 3163 | VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, |
e9b61f19 KS |
3164 | page_tail); |
3165 | page_tail->mapping = head->mapping; | |
3166 | ||
3167 | page_tail->index = head->index + tail; | |
3168 | page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); | |
3169 | lru_add_page_tail(head, page_tail, lruvec, list); | |
e9b61f19 KS |
3170 | } |
3171 | ||
3172 | static void __split_huge_page(struct page *page, struct list_head *list) | |
3173 | { | |
3174 | struct page *head = compound_head(page); | |
3175 | struct zone *zone = page_zone(head); | |
3176 | struct lruvec *lruvec; | |
8df651c7 | 3177 | int i; |
e9b61f19 KS |
3178 | |
3179 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
3180 | spin_lock_irq(&zone->lru_lock); | |
3181 | lruvec = mem_cgroup_page_lruvec(head, zone); | |
3182 | ||
3183 | /* complete memcg works before add pages to LRU */ | |
3184 | mem_cgroup_split_huge_fixup(head); | |
3185 | ||
e9b61f19 | 3186 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) |
8df651c7 | 3187 | __split_huge_page_tail(head, i, lruvec, list); |
e9b61f19 KS |
3188 | |
3189 | ClearPageCompound(head); | |
3190 | spin_unlock_irq(&zone->lru_lock); | |
3191 | ||
fec89c10 | 3192 | unfreeze_page(head); |
e9b61f19 KS |
3193 | |
3194 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
3195 | struct page *subpage = head + i; | |
3196 | if (subpage == page) | |
3197 | continue; | |
3198 | unlock_page(subpage); | |
3199 | ||
3200 | /* | |
3201 | * Subpages may be freed if there wasn't any mapping | |
3202 | * like if add_to_swap() is running on a lru page that | |
3203 | * had its mapping zapped. And freeing these pages | |
3204 | * requires taking the lru_lock so we do the put_page | |
3205 | * of the tail pages after the split is complete. | |
3206 | */ | |
3207 | put_page(subpage); | |
3208 | } | |
3209 | } | |
3210 | ||
b20ce5e0 KS |
3211 | int total_mapcount(struct page *page) |
3212 | { | |
3213 | int i, ret; | |
3214 | ||
3215 | VM_BUG_ON_PAGE(PageTail(page), page); | |
3216 | ||
3217 | if (likely(!PageCompound(page))) | |
3218 | return atomic_read(&page->_mapcount) + 1; | |
3219 | ||
3220 | ret = compound_mapcount(page); | |
3221 | if (PageHuge(page)) | |
3222 | return ret; | |
3223 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
3224 | ret += atomic_read(&page[i]._mapcount) + 1; | |
3225 | if (PageDoubleMap(page)) | |
3226 | ret -= HPAGE_PMD_NR; | |
3227 | return ret; | |
3228 | } | |
3229 | ||
6d0a07ed AA |
3230 | /* |
3231 | * This calculates accurately how many mappings a transparent hugepage | |
3232 | * has (unlike page_mapcount() which isn't fully accurate). This full | |
3233 | * accuracy is primarily needed to know if copy-on-write faults can | |
3234 | * reuse the page and change the mapping to read-write instead of | |
3235 | * copying them. At the same time this returns the total_mapcount too. | |
3236 | * | |
3237 | * The function returns the highest mapcount any one of the subpages | |
3238 | * has. If the return value is one, even if different processes are | |
3239 | * mapping different subpages of the transparent hugepage, they can | |
3240 | * all reuse it, because each process is reusing a different subpage. | |
3241 | * | |
3242 | * The total_mapcount is instead counting all virtual mappings of the | |
3243 | * subpages. If the total_mapcount is equal to "one", it tells the | |
3244 | * caller all mappings belong to the same "mm" and in turn the | |
3245 | * anon_vma of the transparent hugepage can become the vma->anon_vma | |
3246 | * local one as no other process may be mapping any of the subpages. | |
3247 | * | |
3248 | * It would be more accurate to replace page_mapcount() with | |
3249 | * page_trans_huge_mapcount(), however we only use | |
3250 | * page_trans_huge_mapcount() in the copy-on-write faults where we | |
3251 | * need full accuracy to avoid breaking page pinning, because | |
3252 | * page_trans_huge_mapcount() is slower than page_mapcount(). | |
3253 | */ | |
3254 | int page_trans_huge_mapcount(struct page *page, int *total_mapcount) | |
3255 | { | |
3256 | int i, ret, _total_mapcount, mapcount; | |
3257 | ||
3258 | /* hugetlbfs shouldn't call it */ | |
3259 | VM_BUG_ON_PAGE(PageHuge(page), page); | |
3260 | ||
3261 | if (likely(!PageTransCompound(page))) { | |
3262 | mapcount = atomic_read(&page->_mapcount) + 1; | |
3263 | if (total_mapcount) | |
3264 | *total_mapcount = mapcount; | |
3265 | return mapcount; | |
3266 | } | |
3267 | ||
3268 | page = compound_head(page); | |
3269 | ||
3270 | _total_mapcount = ret = 0; | |
3271 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
3272 | mapcount = atomic_read(&page[i]._mapcount) + 1; | |
3273 | ret = max(ret, mapcount); | |
3274 | _total_mapcount += mapcount; | |
3275 | } | |
3276 | if (PageDoubleMap(page)) { | |
3277 | ret -= 1; | |
3278 | _total_mapcount -= HPAGE_PMD_NR; | |
3279 | } | |
3280 | mapcount = compound_mapcount(page); | |
3281 | ret += mapcount; | |
3282 | _total_mapcount += mapcount; | |
3283 | if (total_mapcount) | |
3284 | *total_mapcount = _total_mapcount; | |
3285 | return ret; | |
3286 | } | |
3287 | ||
e9b61f19 KS |
3288 | /* |
3289 | * This function splits huge page into normal pages. @page can point to any | |
3290 | * subpage of huge page to split. Split doesn't change the position of @page. | |
3291 | * | |
3292 | * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. | |
3293 | * The huge page must be locked. | |
3294 | * | |
3295 | * If @list is null, tail pages will be added to LRU list, otherwise, to @list. | |
3296 | * | |
3297 | * Both head page and tail pages will inherit mapping, flags, and so on from | |
3298 | * the hugepage. | |
3299 | * | |
3300 | * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if | |
3301 | * they are not mapped. | |
3302 | * | |
3303 | * Returns 0 if the hugepage is split successfully. | |
3304 | * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under | |
3305 | * us. | |
3306 | */ | |
3307 | int split_huge_page_to_list(struct page *page, struct list_head *list) | |
3308 | { | |
3309 | struct page *head = compound_head(page); | |
a3d0a918 | 3310 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); |
e9b61f19 KS |
3311 | struct anon_vma *anon_vma; |
3312 | int count, mapcount, ret; | |
d9654322 | 3313 | bool mlocked; |
0b9b6fff | 3314 | unsigned long flags; |
e9b61f19 KS |
3315 | |
3316 | VM_BUG_ON_PAGE(is_huge_zero_page(page), page); | |
3317 | VM_BUG_ON_PAGE(!PageAnon(page), page); | |
3318 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
3319 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
3320 | VM_BUG_ON_PAGE(!PageCompound(page), page); | |
3321 | ||
3322 | /* | |
3323 | * The caller does not necessarily hold an mmap_sem that would prevent | |
3324 | * the anon_vma disappearing so we first we take a reference to it | |
3325 | * and then lock the anon_vma for write. This is similar to | |
3326 | * page_lock_anon_vma_read except the write lock is taken to serialise | |
3327 | * against parallel split or collapse operations. | |
3328 | */ | |
3329 | anon_vma = page_get_anon_vma(head); | |
3330 | if (!anon_vma) { | |
3331 | ret = -EBUSY; | |
3332 | goto out; | |
3333 | } | |
3334 | anon_vma_lock_write(anon_vma); | |
3335 | ||
3336 | /* | |
3337 | * Racy check if we can split the page, before freeze_page() will | |
3338 | * split PMDs | |
3339 | */ | |
3340 | if (total_mapcount(head) != page_count(head) - 1) { | |
3341 | ret = -EBUSY; | |
3342 | goto out_unlock; | |
3343 | } | |
3344 | ||
d9654322 | 3345 | mlocked = PageMlocked(page); |
fec89c10 | 3346 | freeze_page(head); |
e9b61f19 KS |
3347 | VM_BUG_ON_PAGE(compound_mapcount(head), head); |
3348 | ||
d9654322 KS |
3349 | /* Make sure the page is not on per-CPU pagevec as it takes pin */ |
3350 | if (mlocked) | |
3351 | lru_add_drain(); | |
3352 | ||
0139aa7b | 3353 | /* Prevent deferred_split_scan() touching ->_refcount */ |
a3d0a918 | 3354 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
e9b61f19 KS |
3355 | count = page_count(head); |
3356 | mapcount = total_mapcount(head); | |
bd56086f | 3357 | if (!mapcount && count == 1) { |
9a982250 | 3358 | if (!list_empty(page_deferred_list(head))) { |
a3d0a918 | 3359 | pgdata->split_queue_len--; |
9a982250 KS |
3360 | list_del(page_deferred_list(head)); |
3361 | } | |
a3d0a918 | 3362 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
e9b61f19 KS |
3363 | __split_huge_page(page, list); |
3364 | ret = 0; | |
bd56086f | 3365 | } else if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { |
a3d0a918 | 3366 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
e9b61f19 KS |
3367 | pr_alert("total_mapcount: %u, page_count(): %u\n", |
3368 | mapcount, count); | |
3369 | if (PageTail(page)) | |
3370 | dump_page(head, NULL); | |
bd56086f | 3371 | dump_page(page, "total_mapcount(head) > 0"); |
e9b61f19 KS |
3372 | BUG(); |
3373 | } else { | |
a3d0a918 | 3374 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
fec89c10 | 3375 | unfreeze_page(head); |
e9b61f19 KS |
3376 | ret = -EBUSY; |
3377 | } | |
3378 | ||
3379 | out_unlock: | |
3380 | anon_vma_unlock_write(anon_vma); | |
3381 | put_anon_vma(anon_vma); | |
3382 | out: | |
3383 | count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); | |
3384 | return ret; | |
3385 | } | |
9a982250 KS |
3386 | |
3387 | void free_transhuge_page(struct page *page) | |
3388 | { | |
a3d0a918 | 3389 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); |
9a982250 KS |
3390 | unsigned long flags; |
3391 | ||
a3d0a918 | 3392 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 3393 | if (!list_empty(page_deferred_list(page))) { |
a3d0a918 | 3394 | pgdata->split_queue_len--; |
9a982250 KS |
3395 | list_del(page_deferred_list(page)); |
3396 | } | |
a3d0a918 | 3397 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
3398 | free_compound_page(page); |
3399 | } | |
3400 | ||
3401 | void deferred_split_huge_page(struct page *page) | |
3402 | { | |
a3d0a918 | 3403 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); |
9a982250 KS |
3404 | unsigned long flags; |
3405 | ||
3406 | VM_BUG_ON_PAGE(!PageTransHuge(page), page); | |
3407 | ||
a3d0a918 | 3408 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 3409 | if (list_empty(page_deferred_list(page))) { |
f9719a03 | 3410 | count_vm_event(THP_DEFERRED_SPLIT_PAGE); |
a3d0a918 KS |
3411 | list_add_tail(page_deferred_list(page), &pgdata->split_queue); |
3412 | pgdata->split_queue_len++; | |
9a982250 | 3413 | } |
a3d0a918 | 3414 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
3415 | } |
3416 | ||
3417 | static unsigned long deferred_split_count(struct shrinker *shrink, | |
3418 | struct shrink_control *sc) | |
3419 | { | |
a3d0a918 | 3420 | struct pglist_data *pgdata = NODE_DATA(sc->nid); |
cb8d68ec | 3421 | return ACCESS_ONCE(pgdata->split_queue_len); |
9a982250 KS |
3422 | } |
3423 | ||
3424 | static unsigned long deferred_split_scan(struct shrinker *shrink, | |
3425 | struct shrink_control *sc) | |
3426 | { | |
a3d0a918 | 3427 | struct pglist_data *pgdata = NODE_DATA(sc->nid); |
9a982250 KS |
3428 | unsigned long flags; |
3429 | LIST_HEAD(list), *pos, *next; | |
3430 | struct page *page; | |
3431 | int split = 0; | |
3432 | ||
a3d0a918 | 3433 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 3434 | /* Take pin on all head pages to avoid freeing them under us */ |
ae026204 | 3435 | list_for_each_safe(pos, next, &pgdata->split_queue) { |
9a982250 KS |
3436 | page = list_entry((void *)pos, struct page, mapping); |
3437 | page = compound_head(page); | |
e3ae1953 KS |
3438 | if (get_page_unless_zero(page)) { |
3439 | list_move(page_deferred_list(page), &list); | |
3440 | } else { | |
3441 | /* We lost race with put_compound_page() */ | |
9a982250 | 3442 | list_del_init(page_deferred_list(page)); |
a3d0a918 | 3443 | pgdata->split_queue_len--; |
9a982250 | 3444 | } |
e3ae1953 KS |
3445 | if (!--sc->nr_to_scan) |
3446 | break; | |
9a982250 | 3447 | } |
a3d0a918 | 3448 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
3449 | |
3450 | list_for_each_safe(pos, next, &list) { | |
3451 | page = list_entry((void *)pos, struct page, mapping); | |
3452 | lock_page(page); | |
3453 | /* split_huge_page() removes page from list on success */ | |
3454 | if (!split_huge_page(page)) | |
3455 | split++; | |
3456 | unlock_page(page); | |
3457 | put_page(page); | |
3458 | } | |
3459 | ||
a3d0a918 KS |
3460 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
3461 | list_splice_tail(&list, &pgdata->split_queue); | |
3462 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); | |
9a982250 | 3463 | |
cb8d68ec KS |
3464 | /* |
3465 | * Stop shrinker if we didn't split any page, but the queue is empty. | |
3466 | * This can happen if pages were freed under us. | |
3467 | */ | |
3468 | if (!split && list_empty(&pgdata->split_queue)) | |
3469 | return SHRINK_STOP; | |
3470 | return split; | |
9a982250 KS |
3471 | } |
3472 | ||
3473 | static struct shrinker deferred_split_shrinker = { | |
3474 | .count_objects = deferred_split_count, | |
3475 | .scan_objects = deferred_split_scan, | |
3476 | .seeks = DEFAULT_SEEKS, | |
a3d0a918 | 3477 | .flags = SHRINKER_NUMA_AWARE, |
9a982250 | 3478 | }; |
49071d43 KS |
3479 | |
3480 | #ifdef CONFIG_DEBUG_FS | |
3481 | static int split_huge_pages_set(void *data, u64 val) | |
3482 | { | |
3483 | struct zone *zone; | |
3484 | struct page *page; | |
3485 | unsigned long pfn, max_zone_pfn; | |
3486 | unsigned long total = 0, split = 0; | |
3487 | ||
3488 | if (val != 1) | |
3489 | return -EINVAL; | |
3490 | ||
3491 | for_each_populated_zone(zone) { | |
3492 | max_zone_pfn = zone_end_pfn(zone); | |
3493 | for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { | |
3494 | if (!pfn_valid(pfn)) | |
3495 | continue; | |
3496 | ||
3497 | page = pfn_to_page(pfn); | |
3498 | if (!get_page_unless_zero(page)) | |
3499 | continue; | |
3500 | ||
3501 | if (zone != page_zone(page)) | |
3502 | goto next; | |
3503 | ||
3504 | if (!PageHead(page) || !PageAnon(page) || | |
3505 | PageHuge(page)) | |
3506 | goto next; | |
3507 | ||
3508 | total++; | |
3509 | lock_page(page); | |
3510 | if (!split_huge_page(page)) | |
3511 | split++; | |
3512 | unlock_page(page); | |
3513 | next: | |
3514 | put_page(page); | |
3515 | } | |
3516 | } | |
3517 | ||
145bdaa1 | 3518 | pr_info("%lu of %lu THP split\n", split, total); |
49071d43 KS |
3519 | |
3520 | return 0; | |
3521 | } | |
3522 | DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, | |
3523 | "%llu\n"); | |
3524 | ||
3525 | static int __init split_huge_pages_debugfs(void) | |
3526 | { | |
3527 | void *ret; | |
3528 | ||
145bdaa1 | 3529 | ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL, |
49071d43 KS |
3530 | &split_huge_pages_fops); |
3531 | if (!ret) | |
3532 | pr_warn("Failed to create split_huge_pages in debugfs"); | |
3533 | return 0; | |
3534 | } | |
3535 | late_initcall(split_huge_pages_debugfs); | |
3536 | #endif |