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Commit | Line | Data |
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71e3aac0 AA |
1 | /* |
2 | * Copyright (C) 2009 Red Hat, Inc. | |
3 | * | |
4 | * This work is licensed under the terms of the GNU GPL, version 2. See | |
5 | * the COPYING file in the top-level directory. | |
6 | */ | |
7 | ||
ae3a8c1c AM |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
9 | ||
71e3aac0 AA |
10 | #include <linux/mm.h> |
11 | #include <linux/sched.h> | |
12 | #include <linux/highmem.h> | |
13 | #include <linux/hugetlb.h> | |
14 | #include <linux/mmu_notifier.h> | |
15 | #include <linux/rmap.h> | |
16 | #include <linux/swap.h> | |
97ae1749 | 17 | #include <linux/shrinker.h> |
ba76149f | 18 | #include <linux/mm_inline.h> |
e9b61f19 | 19 | #include <linux/swapops.h> |
4897c765 | 20 | #include <linux/dax.h> |
ba76149f AA |
21 | #include <linux/kthread.h> |
22 | #include <linux/khugepaged.h> | |
878aee7d | 23 | #include <linux/freezer.h> |
f25748e3 | 24 | #include <linux/pfn_t.h> |
a664b2d8 | 25 | #include <linux/mman.h> |
3565fce3 | 26 | #include <linux/memremap.h> |
325adeb5 | 27 | #include <linux/pagemap.h> |
49071d43 | 28 | #include <linux/debugfs.h> |
4daae3b4 | 29 | #include <linux/migrate.h> |
43b5fbbd | 30 | #include <linux/hashtable.h> |
6b251fc9 | 31 | #include <linux/userfaultfd_k.h> |
33c3fc71 | 32 | #include <linux/page_idle.h> |
97ae1749 | 33 | |
71e3aac0 AA |
34 | #include <asm/tlb.h> |
35 | #include <asm/pgalloc.h> | |
36 | #include "internal.h" | |
37 | ||
7d2eba05 EA |
38 | enum scan_result { |
39 | SCAN_FAIL, | |
40 | SCAN_SUCCEED, | |
41 | SCAN_PMD_NULL, | |
42 | SCAN_EXCEED_NONE_PTE, | |
43 | SCAN_PTE_NON_PRESENT, | |
44 | SCAN_PAGE_RO, | |
45 | SCAN_NO_REFERENCED_PAGE, | |
46 | SCAN_PAGE_NULL, | |
47 | SCAN_SCAN_ABORT, | |
48 | SCAN_PAGE_COUNT, | |
49 | SCAN_PAGE_LRU, | |
50 | SCAN_PAGE_LOCK, | |
51 | SCAN_PAGE_ANON, | |
b1caa957 | 52 | SCAN_PAGE_COMPOUND, |
7d2eba05 EA |
53 | SCAN_ANY_PROCESS, |
54 | SCAN_VMA_NULL, | |
55 | SCAN_VMA_CHECK, | |
56 | SCAN_ADDRESS_RANGE, | |
57 | SCAN_SWAP_CACHE_PAGE, | |
58 | SCAN_DEL_PAGE_LRU, | |
59 | SCAN_ALLOC_HUGE_PAGE_FAIL, | |
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 | |
d39d33c3 | 81 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_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 */ | |
86 | static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8; | |
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; | |
92 | static struct task_struct *khugepaged_thread __read_mostly; | |
93 | static DEFINE_MUTEX(khugepaged_mutex); | |
94 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
95 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
96 | /* | |
97 | * default collapse hugepages if there is at least one pte mapped like | |
98 | * it would have happened if the vma was large enough during page | |
99 | * fault. | |
100 | */ | |
101 | static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1; | |
102 | ||
103 | static int khugepaged(void *none); | |
ba76149f | 104 | static int khugepaged_slab_init(void); |
65ebb64f | 105 | static void khugepaged_slab_exit(void); |
ba76149f | 106 | |
43b5fbbd SL |
107 | #define MM_SLOTS_HASH_BITS 10 |
108 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
109 | ||
ba76149f AA |
110 | static struct kmem_cache *mm_slot_cache __read_mostly; |
111 | ||
112 | /** | |
113 | * struct mm_slot - hash lookup from mm to mm_slot | |
114 | * @hash: hash collision list | |
115 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
116 | * @mm: the mm that this information is valid for | |
117 | */ | |
118 | struct mm_slot { | |
119 | struct hlist_node hash; | |
120 | struct list_head mm_node; | |
121 | struct mm_struct *mm; | |
122 | }; | |
123 | ||
124 | /** | |
125 | * struct khugepaged_scan - cursor for scanning | |
126 | * @mm_head: the head of the mm list to scan | |
127 | * @mm_slot: the current mm_slot we are scanning | |
128 | * @address: the next address inside that to be scanned | |
129 | * | |
130 | * There is only the one khugepaged_scan instance of this cursor structure. | |
131 | */ | |
132 | struct khugepaged_scan { | |
133 | struct list_head mm_head; | |
134 | struct mm_slot *mm_slot; | |
135 | unsigned long address; | |
2f1da642 HS |
136 | }; |
137 | static struct khugepaged_scan khugepaged_scan = { | |
ba76149f AA |
138 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), |
139 | }; | |
140 | ||
9a982250 KS |
141 | static DEFINE_SPINLOCK(split_queue_lock); |
142 | static LIST_HEAD(split_queue); | |
143 | static unsigned long split_queue_len; | |
144 | static struct shrinker deferred_split_shrinker; | |
f000565a | 145 | |
2c0b80d4 | 146 | static void set_recommended_min_free_kbytes(void) |
f000565a AA |
147 | { |
148 | struct zone *zone; | |
149 | int nr_zones = 0; | |
150 | unsigned long recommended_min; | |
f000565a | 151 | |
f000565a AA |
152 | for_each_populated_zone(zone) |
153 | nr_zones++; | |
154 | ||
974a786e | 155 | /* Ensure 2 pageblocks are free to assist fragmentation avoidance */ |
f000565a AA |
156 | recommended_min = pageblock_nr_pages * nr_zones * 2; |
157 | ||
158 | /* | |
159 | * Make sure that on average at least two pageblocks are almost free | |
160 | * of another type, one for a migratetype to fall back to and a | |
161 | * second to avoid subsequent fallbacks of other types There are 3 | |
162 | * MIGRATE_TYPES we care about. | |
163 | */ | |
164 | recommended_min += pageblock_nr_pages * nr_zones * | |
165 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
166 | ||
167 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
168 | recommended_min = min(recommended_min, | |
169 | (unsigned long) nr_free_buffer_pages() / 20); | |
170 | recommended_min <<= (PAGE_SHIFT-10); | |
171 | ||
42aa83cb HP |
172 | if (recommended_min > min_free_kbytes) { |
173 | if (user_min_free_kbytes >= 0) | |
174 | pr_info("raising min_free_kbytes from %d to %lu " | |
175 | "to help transparent hugepage allocations\n", | |
176 | min_free_kbytes, recommended_min); | |
177 | ||
f000565a | 178 | min_free_kbytes = recommended_min; |
42aa83cb | 179 | } |
f000565a | 180 | setup_per_zone_wmarks(); |
f000565a | 181 | } |
f000565a | 182 | |
79553da2 | 183 | static int start_stop_khugepaged(void) |
ba76149f AA |
184 | { |
185 | int err = 0; | |
186 | if (khugepaged_enabled()) { | |
ba76149f AA |
187 | if (!khugepaged_thread) |
188 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
189 | "khugepaged"); | |
18e8e5c7 | 190 | if (IS_ERR(khugepaged_thread)) { |
ae3a8c1c | 191 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); |
ba76149f AA |
192 | err = PTR_ERR(khugepaged_thread); |
193 | khugepaged_thread = NULL; | |
79553da2 | 194 | goto fail; |
ba76149f | 195 | } |
911891af XG |
196 | |
197 | if (!list_empty(&khugepaged_scan.mm_head)) | |
ba76149f | 198 | wake_up_interruptible(&khugepaged_wait); |
f000565a AA |
199 | |
200 | set_recommended_min_free_kbytes(); | |
911891af | 201 | } else if (khugepaged_thread) { |
911891af XG |
202 | kthread_stop(khugepaged_thread); |
203 | khugepaged_thread = NULL; | |
204 | } | |
79553da2 | 205 | fail: |
ba76149f AA |
206 | return err; |
207 | } | |
71e3aac0 | 208 | |
97ae1749 | 209 | static atomic_t huge_zero_refcount; |
56873f43 | 210 | struct page *huge_zero_page __read_mostly; |
4a6c1297 | 211 | |
fc437044 | 212 | struct page *get_huge_zero_page(void) |
97ae1749 KS |
213 | { |
214 | struct page *zero_page; | |
215 | retry: | |
216 | if (likely(atomic_inc_not_zero(&huge_zero_refcount))) | |
4db0c3c2 | 217 | return READ_ONCE(huge_zero_page); |
97ae1749 KS |
218 | |
219 | zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, | |
4a6c1297 | 220 | HPAGE_PMD_ORDER); |
d8a8e1f0 KS |
221 | if (!zero_page) { |
222 | count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); | |
5918d10a | 223 | return NULL; |
d8a8e1f0 KS |
224 | } |
225 | count_vm_event(THP_ZERO_PAGE_ALLOC); | |
97ae1749 | 226 | preempt_disable(); |
5918d10a | 227 | if (cmpxchg(&huge_zero_page, NULL, zero_page)) { |
97ae1749 | 228 | preempt_enable(); |
5ddacbe9 | 229 | __free_pages(zero_page, compound_order(zero_page)); |
97ae1749 KS |
230 | goto retry; |
231 | } | |
232 | ||
233 | /* We take additional reference here. It will be put back by shrinker */ | |
234 | atomic_set(&huge_zero_refcount, 2); | |
235 | preempt_enable(); | |
4db0c3c2 | 236 | return READ_ONCE(huge_zero_page); |
4a6c1297 KS |
237 | } |
238 | ||
97ae1749 | 239 | static void put_huge_zero_page(void) |
4a6c1297 | 240 | { |
97ae1749 KS |
241 | /* |
242 | * Counter should never go to zero here. Only shrinker can put | |
243 | * last reference. | |
244 | */ | |
245 | BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); | |
4a6c1297 KS |
246 | } |
247 | ||
48896466 GC |
248 | static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, |
249 | struct shrink_control *sc) | |
4a6c1297 | 250 | { |
48896466 GC |
251 | /* we can free zero page only if last reference remains */ |
252 | return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; | |
253 | } | |
97ae1749 | 254 | |
48896466 GC |
255 | static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, |
256 | struct shrink_control *sc) | |
257 | { | |
97ae1749 | 258 | if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { |
5918d10a KS |
259 | struct page *zero_page = xchg(&huge_zero_page, NULL); |
260 | BUG_ON(zero_page == NULL); | |
5ddacbe9 | 261 | __free_pages(zero_page, compound_order(zero_page)); |
48896466 | 262 | return HPAGE_PMD_NR; |
97ae1749 KS |
263 | } |
264 | ||
265 | return 0; | |
4a6c1297 KS |
266 | } |
267 | ||
97ae1749 | 268 | static struct shrinker huge_zero_page_shrinker = { |
48896466 GC |
269 | .count_objects = shrink_huge_zero_page_count, |
270 | .scan_objects = shrink_huge_zero_page_scan, | |
97ae1749 KS |
271 | .seeks = DEFAULT_SEEKS, |
272 | }; | |
273 | ||
71e3aac0 | 274 | #ifdef CONFIG_SYSFS |
ba76149f | 275 | |
71e3aac0 AA |
276 | static ssize_t double_flag_show(struct kobject *kobj, |
277 | struct kobj_attribute *attr, char *buf, | |
278 | enum transparent_hugepage_flag enabled, | |
279 | enum transparent_hugepage_flag req_madv) | |
280 | { | |
281 | if (test_bit(enabled, &transparent_hugepage_flags)) { | |
282 | VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags)); | |
283 | return sprintf(buf, "[always] madvise never\n"); | |
284 | } else if (test_bit(req_madv, &transparent_hugepage_flags)) | |
285 | return sprintf(buf, "always [madvise] never\n"); | |
286 | else | |
287 | return sprintf(buf, "always madvise [never]\n"); | |
288 | } | |
289 | static ssize_t double_flag_store(struct kobject *kobj, | |
290 | struct kobj_attribute *attr, | |
291 | const char *buf, size_t count, | |
292 | enum transparent_hugepage_flag enabled, | |
293 | enum transparent_hugepage_flag req_madv) | |
294 | { | |
295 | if (!memcmp("always", buf, | |
296 | min(sizeof("always")-1, count))) { | |
297 | set_bit(enabled, &transparent_hugepage_flags); | |
298 | clear_bit(req_madv, &transparent_hugepage_flags); | |
299 | } else if (!memcmp("madvise", buf, | |
300 | min(sizeof("madvise")-1, count))) { | |
301 | clear_bit(enabled, &transparent_hugepage_flags); | |
302 | set_bit(req_madv, &transparent_hugepage_flags); | |
303 | } else if (!memcmp("never", buf, | |
304 | min(sizeof("never")-1, count))) { | |
305 | clear_bit(enabled, &transparent_hugepage_flags); | |
306 | clear_bit(req_madv, &transparent_hugepage_flags); | |
307 | } else | |
308 | return -EINVAL; | |
309 | ||
310 | return count; | |
311 | } | |
312 | ||
313 | static ssize_t enabled_show(struct kobject *kobj, | |
314 | struct kobj_attribute *attr, char *buf) | |
315 | { | |
316 | return double_flag_show(kobj, attr, buf, | |
317 | TRANSPARENT_HUGEPAGE_FLAG, | |
318 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
319 | } | |
320 | static ssize_t enabled_store(struct kobject *kobj, | |
321 | struct kobj_attribute *attr, | |
322 | const char *buf, size_t count) | |
323 | { | |
ba76149f AA |
324 | ssize_t ret; |
325 | ||
326 | ret = double_flag_store(kobj, attr, buf, count, | |
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 | { | |
384 | return double_flag_show(kobj, attr, buf, | |
385 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
386 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
387 | } | |
388 | static ssize_t defrag_store(struct kobject *kobj, | |
389 | struct kobj_attribute *attr, | |
390 | const char *buf, size_t count) | |
391 | { | |
392 | return double_flag_store(kobj, attr, buf, count, | |
393 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
394 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
395 | } | |
396 | static struct kobj_attribute defrag_attr = | |
397 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
398 | ||
79da5407 KS |
399 | static ssize_t use_zero_page_show(struct kobject *kobj, |
400 | struct kobj_attribute *attr, char *buf) | |
401 | { | |
402 | return single_flag_show(kobj, attr, buf, | |
403 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
404 | } | |
405 | static ssize_t use_zero_page_store(struct kobject *kobj, | |
406 | struct kobj_attribute *attr, const char *buf, size_t count) | |
407 | { | |
408 | return single_flag_store(kobj, attr, buf, count, | |
409 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
410 | } | |
411 | static struct kobj_attribute use_zero_page_attr = | |
412 | __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); | |
71e3aac0 AA |
413 | #ifdef CONFIG_DEBUG_VM |
414 | static ssize_t debug_cow_show(struct kobject *kobj, | |
415 | struct kobj_attribute *attr, char *buf) | |
416 | { | |
417 | return single_flag_show(kobj, attr, buf, | |
418 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
419 | } | |
420 | static ssize_t debug_cow_store(struct kobject *kobj, | |
421 | struct kobj_attribute *attr, | |
422 | const char *buf, size_t count) | |
423 | { | |
424 | return single_flag_store(kobj, attr, buf, count, | |
425 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
426 | } | |
427 | static struct kobj_attribute debug_cow_attr = | |
428 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
429 | #endif /* CONFIG_DEBUG_VM */ | |
430 | ||
431 | static struct attribute *hugepage_attr[] = { | |
432 | &enabled_attr.attr, | |
433 | &defrag_attr.attr, | |
79da5407 | 434 | &use_zero_page_attr.attr, |
71e3aac0 AA |
435 | #ifdef CONFIG_DEBUG_VM |
436 | &debug_cow_attr.attr, | |
437 | #endif | |
438 | NULL, | |
439 | }; | |
440 | ||
441 | static struct attribute_group hugepage_attr_group = { | |
442 | .attrs = hugepage_attr, | |
ba76149f AA |
443 | }; |
444 | ||
445 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, | |
446 | struct kobj_attribute *attr, | |
447 | char *buf) | |
448 | { | |
449 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
450 | } | |
451 | ||
452 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
453 | struct kobj_attribute *attr, | |
454 | const char *buf, size_t count) | |
455 | { | |
456 | unsigned long msecs; | |
457 | int err; | |
458 | ||
3dbb95f7 | 459 | err = kstrtoul(buf, 10, &msecs); |
ba76149f AA |
460 | if (err || msecs > UINT_MAX) |
461 | return -EINVAL; | |
462 | ||
463 | khugepaged_scan_sleep_millisecs = msecs; | |
464 | wake_up_interruptible(&khugepaged_wait); | |
465 | ||
466 | return count; | |
467 | } | |
468 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
469 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
470 | scan_sleep_millisecs_store); | |
471 | ||
472 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
473 | struct kobj_attribute *attr, | |
474 | char *buf) | |
475 | { | |
476 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
477 | } | |
478 | ||
479 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
480 | struct kobj_attribute *attr, | |
481 | const char *buf, size_t count) | |
482 | { | |
483 | unsigned long msecs; | |
484 | int err; | |
485 | ||
3dbb95f7 | 486 | err = kstrtoul(buf, 10, &msecs); |
ba76149f AA |
487 | if (err || msecs > UINT_MAX) |
488 | return -EINVAL; | |
489 | ||
490 | khugepaged_alloc_sleep_millisecs = msecs; | |
491 | wake_up_interruptible(&khugepaged_wait); | |
492 | ||
493 | return count; | |
494 | } | |
495 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
496 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
497 | alloc_sleep_millisecs_store); | |
498 | ||
499 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
500 | struct kobj_attribute *attr, | |
501 | char *buf) | |
502 | { | |
503 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
504 | } | |
505 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
506 | struct kobj_attribute *attr, | |
507 | const char *buf, size_t count) | |
508 | { | |
509 | int err; | |
510 | unsigned long pages; | |
511 | ||
3dbb95f7 | 512 | err = kstrtoul(buf, 10, &pages); |
ba76149f AA |
513 | if (err || !pages || pages > UINT_MAX) |
514 | return -EINVAL; | |
515 | ||
516 | khugepaged_pages_to_scan = pages; | |
517 | ||
518 | return count; | |
519 | } | |
520 | static struct kobj_attribute pages_to_scan_attr = | |
521 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
522 | pages_to_scan_store); | |
523 | ||
524 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
525 | struct kobj_attribute *attr, | |
526 | char *buf) | |
527 | { | |
528 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
529 | } | |
530 | static struct kobj_attribute pages_collapsed_attr = | |
531 | __ATTR_RO(pages_collapsed); | |
532 | ||
533 | static ssize_t full_scans_show(struct kobject *kobj, | |
534 | struct kobj_attribute *attr, | |
535 | char *buf) | |
536 | { | |
537 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
538 | } | |
539 | static struct kobj_attribute full_scans_attr = | |
540 | __ATTR_RO(full_scans); | |
541 | ||
542 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
543 | struct kobj_attribute *attr, char *buf) | |
544 | { | |
545 | return single_flag_show(kobj, attr, buf, | |
546 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
547 | } | |
548 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
549 | struct kobj_attribute *attr, | |
550 | const char *buf, size_t count) | |
551 | { | |
552 | return single_flag_store(kobj, attr, buf, count, | |
553 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
554 | } | |
555 | static struct kobj_attribute khugepaged_defrag_attr = | |
556 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
557 | khugepaged_defrag_store); | |
558 | ||
559 | /* | |
560 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
561 | * any unmapped ptes in turn potentially increasing the memory | |
562 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
563 | * reduce the available free memory in the system as it | |
564 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
565 | * free memory in the system during the khugepaged scan. | |
566 | */ | |
567 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
568 | struct kobj_attribute *attr, | |
569 | char *buf) | |
570 | { | |
571 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
572 | } | |
573 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
574 | struct kobj_attribute *attr, | |
575 | const char *buf, size_t count) | |
576 | { | |
577 | int err; | |
578 | unsigned long max_ptes_none; | |
579 | ||
3dbb95f7 | 580 | err = kstrtoul(buf, 10, &max_ptes_none); |
ba76149f AA |
581 | if (err || max_ptes_none > HPAGE_PMD_NR-1) |
582 | return -EINVAL; | |
583 | ||
584 | khugepaged_max_ptes_none = max_ptes_none; | |
585 | ||
586 | return count; | |
587 | } | |
588 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
589 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
590 | khugepaged_max_ptes_none_store); | |
591 | ||
592 | static struct attribute *khugepaged_attr[] = { | |
593 | &khugepaged_defrag_attr.attr, | |
594 | &khugepaged_max_ptes_none_attr.attr, | |
595 | &pages_to_scan_attr.attr, | |
596 | &pages_collapsed_attr.attr, | |
597 | &full_scans_attr.attr, | |
598 | &scan_sleep_millisecs_attr.attr, | |
599 | &alloc_sleep_millisecs_attr.attr, | |
600 | NULL, | |
601 | }; | |
602 | ||
603 | static struct attribute_group khugepaged_attr_group = { | |
604 | .attrs = khugepaged_attr, | |
605 | .name = "khugepaged", | |
71e3aac0 | 606 | }; |
71e3aac0 | 607 | |
569e5590 | 608 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
71e3aac0 | 609 | { |
71e3aac0 AA |
610 | int err; |
611 | ||
569e5590 SL |
612 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); |
613 | if (unlikely(!*hugepage_kobj)) { | |
ae3a8c1c | 614 | pr_err("failed to create transparent hugepage kobject\n"); |
569e5590 | 615 | return -ENOMEM; |
ba76149f AA |
616 | } |
617 | ||
569e5590 | 618 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); |
ba76149f | 619 | if (err) { |
ae3a8c1c | 620 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 621 | goto delete_obj; |
ba76149f AA |
622 | } |
623 | ||
569e5590 | 624 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); |
ba76149f | 625 | if (err) { |
ae3a8c1c | 626 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 627 | goto remove_hp_group; |
ba76149f | 628 | } |
569e5590 SL |
629 | |
630 | return 0; | |
631 | ||
632 | remove_hp_group: | |
633 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
634 | delete_obj: | |
635 | kobject_put(*hugepage_kobj); | |
636 | return err; | |
637 | } | |
638 | ||
639 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
640 | { | |
641 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
642 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
643 | kobject_put(hugepage_kobj); | |
644 | } | |
645 | #else | |
646 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
647 | { | |
648 | return 0; | |
649 | } | |
650 | ||
651 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
652 | { | |
653 | } | |
654 | #endif /* CONFIG_SYSFS */ | |
655 | ||
656 | static int __init hugepage_init(void) | |
657 | { | |
658 | int err; | |
659 | struct kobject *hugepage_kobj; | |
660 | ||
661 | if (!has_transparent_hugepage()) { | |
662 | transparent_hugepage_flags = 0; | |
663 | return -EINVAL; | |
664 | } | |
665 | ||
666 | err = hugepage_init_sysfs(&hugepage_kobj); | |
667 | if (err) | |
65ebb64f | 668 | goto err_sysfs; |
ba76149f AA |
669 | |
670 | err = khugepaged_slab_init(); | |
671 | if (err) | |
65ebb64f | 672 | goto err_slab; |
ba76149f | 673 | |
65ebb64f KS |
674 | err = register_shrinker(&huge_zero_page_shrinker); |
675 | if (err) | |
676 | goto err_hzp_shrinker; | |
9a982250 KS |
677 | err = register_shrinker(&deferred_split_shrinker); |
678 | if (err) | |
679 | goto err_split_shrinker; | |
97ae1749 | 680 | |
97562cd2 RR |
681 | /* |
682 | * By default disable transparent hugepages on smaller systems, | |
683 | * where the extra memory used could hurt more than TLB overhead | |
684 | * is likely to save. The admin can still enable it through /sys. | |
685 | */ | |
79553da2 | 686 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) { |
97562cd2 | 687 | transparent_hugepage_flags = 0; |
79553da2 KS |
688 | return 0; |
689 | } | |
97562cd2 | 690 | |
79553da2 | 691 | err = start_stop_khugepaged(); |
65ebb64f KS |
692 | if (err) |
693 | goto err_khugepaged; | |
ba76149f | 694 | |
569e5590 | 695 | return 0; |
65ebb64f | 696 | err_khugepaged: |
9a982250 KS |
697 | unregister_shrinker(&deferred_split_shrinker); |
698 | err_split_shrinker: | |
65ebb64f KS |
699 | unregister_shrinker(&huge_zero_page_shrinker); |
700 | err_hzp_shrinker: | |
701 | khugepaged_slab_exit(); | |
702 | err_slab: | |
569e5590 | 703 | hugepage_exit_sysfs(hugepage_kobj); |
65ebb64f | 704 | err_sysfs: |
ba76149f | 705 | return err; |
71e3aac0 | 706 | } |
a64fb3cd | 707 | subsys_initcall(hugepage_init); |
71e3aac0 AA |
708 | |
709 | static int __init setup_transparent_hugepage(char *str) | |
710 | { | |
711 | int ret = 0; | |
712 | if (!str) | |
713 | goto out; | |
714 | if (!strcmp(str, "always")) { | |
715 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
716 | &transparent_hugepage_flags); | |
717 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
718 | &transparent_hugepage_flags); | |
719 | ret = 1; | |
720 | } else if (!strcmp(str, "madvise")) { | |
721 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
722 | &transparent_hugepage_flags); | |
723 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
724 | &transparent_hugepage_flags); | |
725 | ret = 1; | |
726 | } else if (!strcmp(str, "never")) { | |
727 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
728 | &transparent_hugepage_flags); | |
729 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
730 | &transparent_hugepage_flags); | |
731 | ret = 1; | |
732 | } | |
733 | out: | |
734 | if (!ret) | |
ae3a8c1c | 735 | pr_warn("transparent_hugepage= cannot parse, ignored\n"); |
71e3aac0 AA |
736 | return ret; |
737 | } | |
738 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
739 | ||
b32967ff | 740 | pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) |
71e3aac0 AA |
741 | { |
742 | if (likely(vma->vm_flags & VM_WRITE)) | |
743 | pmd = pmd_mkwrite(pmd); | |
744 | return pmd; | |
745 | } | |
746 | ||
3122359a | 747 | static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot) |
b3092b3b BL |
748 | { |
749 | pmd_t entry; | |
3122359a | 750 | entry = mk_pmd(page, prot); |
b3092b3b BL |
751 | entry = pmd_mkhuge(entry); |
752 | return entry; | |
753 | } | |
754 | ||
9a982250 KS |
755 | static inline struct list_head *page_deferred_list(struct page *page) |
756 | { | |
757 | /* | |
758 | * ->lru in the tail pages is occupied by compound_head. | |
759 | * Let's use ->mapping + ->index in the second tail page as list_head. | |
760 | */ | |
761 | return (struct list_head *)&page[2].mapping; | |
762 | } | |
763 | ||
764 | void prep_transhuge_page(struct page *page) | |
765 | { | |
766 | /* | |
767 | * we use page->mapping and page->indexlru in second tail page | |
768 | * as list_head: assuming THP order >= 2 | |
769 | */ | |
770 | BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); | |
771 | ||
772 | INIT_LIST_HEAD(page_deferred_list(page)); | |
773 | set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); | |
774 | } | |
775 | ||
71e3aac0 AA |
776 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, |
777 | struct vm_area_struct *vma, | |
230c92a8 | 778 | unsigned long address, pmd_t *pmd, |
6b251fc9 AA |
779 | struct page *page, gfp_t gfp, |
780 | unsigned int flags) | |
71e3aac0 | 781 | { |
00501b53 | 782 | struct mem_cgroup *memcg; |
71e3aac0 | 783 | pgtable_t pgtable; |
c4088ebd | 784 | spinlock_t *ptl; |
230c92a8 | 785 | unsigned long haddr = address & HPAGE_PMD_MASK; |
71e3aac0 | 786 | |
309381fe | 787 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
00501b53 | 788 | |
f627c2f5 | 789 | if (mem_cgroup_try_charge(page, mm, gfp, &memcg, true)) { |
6b251fc9 AA |
790 | put_page(page); |
791 | count_vm_event(THP_FAULT_FALLBACK); | |
792 | return VM_FAULT_FALLBACK; | |
793 | } | |
00501b53 | 794 | |
71e3aac0 | 795 | pgtable = pte_alloc_one(mm, haddr); |
00501b53 | 796 | if (unlikely(!pgtable)) { |
f627c2f5 | 797 | mem_cgroup_cancel_charge(page, memcg, true); |
6b251fc9 | 798 | put_page(page); |
71e3aac0 | 799 | return VM_FAULT_OOM; |
00501b53 | 800 | } |
71e3aac0 AA |
801 | |
802 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
52f37629 MK |
803 | /* |
804 | * The memory barrier inside __SetPageUptodate makes sure that | |
805 | * clear_huge_page writes become visible before the set_pmd_at() | |
806 | * write. | |
807 | */ | |
71e3aac0 AA |
808 | __SetPageUptodate(page); |
809 | ||
c4088ebd | 810 | ptl = pmd_lock(mm, pmd); |
71e3aac0 | 811 | if (unlikely(!pmd_none(*pmd))) { |
c4088ebd | 812 | spin_unlock(ptl); |
f627c2f5 | 813 | mem_cgroup_cancel_charge(page, memcg, true); |
71e3aac0 AA |
814 | put_page(page); |
815 | pte_free(mm, pgtable); | |
816 | } else { | |
817 | pmd_t entry; | |
6b251fc9 AA |
818 | |
819 | /* Deliver the page fault to userland */ | |
820 | if (userfaultfd_missing(vma)) { | |
821 | int ret; | |
822 | ||
823 | spin_unlock(ptl); | |
f627c2f5 | 824 | mem_cgroup_cancel_charge(page, memcg, true); |
6b251fc9 AA |
825 | put_page(page); |
826 | pte_free(mm, pgtable); | |
230c92a8 | 827 | ret = handle_userfault(vma, address, flags, |
6b251fc9 AA |
828 | VM_UFFD_MISSING); |
829 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
830 | return ret; | |
831 | } | |
832 | ||
3122359a KS |
833 | entry = mk_huge_pmd(page, vma->vm_page_prot); |
834 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
d281ee61 | 835 | page_add_new_anon_rmap(page, vma, haddr, true); |
f627c2f5 | 836 | mem_cgroup_commit_charge(page, memcg, false, true); |
00501b53 | 837 | lru_cache_add_active_or_unevictable(page, vma); |
6b0b50b0 | 838 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
71e3aac0 | 839 | set_pmd_at(mm, haddr, pmd, entry); |
71e3aac0 | 840 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
e1f56c89 | 841 | atomic_long_inc(&mm->nr_ptes); |
c4088ebd | 842 | spin_unlock(ptl); |
6b251fc9 | 843 | count_vm_event(THP_FAULT_ALLOC); |
71e3aac0 AA |
844 | } |
845 | ||
aa2e878e | 846 | return 0; |
71e3aac0 AA |
847 | } |
848 | ||
cc5d462f | 849 | static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp) |
0bbbc0b3 | 850 | { |
71baba4b | 851 | return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_RECLAIM)) | extra_gfp; |
0bbbc0b3 AA |
852 | } |
853 | ||
c4088ebd | 854 | /* Caller must hold page table lock. */ |
d295e341 | 855 | static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, |
97ae1749 | 856 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, |
5918d10a | 857 | struct page *zero_page) |
fc9fe822 KS |
858 | { |
859 | pmd_t entry; | |
7c414164 AM |
860 | if (!pmd_none(*pmd)) |
861 | return false; | |
5918d10a | 862 | entry = mk_pmd(zero_page, vma->vm_page_prot); |
fc9fe822 | 863 | entry = pmd_mkhuge(entry); |
6b0b50b0 | 864 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
fc9fe822 | 865 | set_pmd_at(mm, haddr, pmd, entry); |
e1f56c89 | 866 | atomic_long_inc(&mm->nr_ptes); |
7c414164 | 867 | return true; |
fc9fe822 KS |
868 | } |
869 | ||
71e3aac0 AA |
870 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, |
871 | unsigned long address, pmd_t *pmd, | |
872 | unsigned int flags) | |
873 | { | |
077fcf11 | 874 | gfp_t gfp; |
71e3aac0 AA |
875 | struct page *page; |
876 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
71e3aac0 | 877 | |
128ec037 | 878 | if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) |
c0292554 | 879 | return VM_FAULT_FALLBACK; |
128ec037 KS |
880 | if (unlikely(anon_vma_prepare(vma))) |
881 | return VM_FAULT_OOM; | |
6d50e60c | 882 | if (unlikely(khugepaged_enter(vma, vma->vm_flags))) |
128ec037 | 883 | return VM_FAULT_OOM; |
593befa6 | 884 | if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) && |
128ec037 | 885 | transparent_hugepage_use_zero_page()) { |
c4088ebd | 886 | spinlock_t *ptl; |
128ec037 KS |
887 | pgtable_t pgtable; |
888 | struct page *zero_page; | |
889 | bool set; | |
6b251fc9 | 890 | int ret; |
128ec037 KS |
891 | pgtable = pte_alloc_one(mm, haddr); |
892 | if (unlikely(!pgtable)) | |
ba76149f | 893 | return VM_FAULT_OOM; |
128ec037 KS |
894 | zero_page = get_huge_zero_page(); |
895 | if (unlikely(!zero_page)) { | |
896 | pte_free(mm, pgtable); | |
81ab4201 | 897 | count_vm_event(THP_FAULT_FALLBACK); |
c0292554 | 898 | return VM_FAULT_FALLBACK; |
b9bbfbe3 | 899 | } |
c4088ebd | 900 | ptl = pmd_lock(mm, pmd); |
6b251fc9 AA |
901 | ret = 0; |
902 | set = false; | |
903 | if (pmd_none(*pmd)) { | |
904 | if (userfaultfd_missing(vma)) { | |
905 | spin_unlock(ptl); | |
230c92a8 | 906 | ret = handle_userfault(vma, address, flags, |
6b251fc9 AA |
907 | VM_UFFD_MISSING); |
908 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
909 | } else { | |
910 | set_huge_zero_page(pgtable, mm, vma, | |
911 | haddr, pmd, | |
912 | zero_page); | |
913 | spin_unlock(ptl); | |
914 | set = true; | |
915 | } | |
916 | } else | |
917 | spin_unlock(ptl); | |
128ec037 KS |
918 | if (!set) { |
919 | pte_free(mm, pgtable); | |
920 | put_huge_zero_page(); | |
edad9d2c | 921 | } |
6b251fc9 | 922 | return ret; |
71e3aac0 | 923 | } |
077fcf11 AK |
924 | gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0); |
925 | page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); | |
128ec037 KS |
926 | if (unlikely(!page)) { |
927 | count_vm_event(THP_FAULT_FALLBACK); | |
c0292554 | 928 | return VM_FAULT_FALLBACK; |
128ec037 | 929 | } |
9a982250 | 930 | prep_transhuge_page(page); |
230c92a8 AA |
931 | return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp, |
932 | flags); | |
71e3aac0 AA |
933 | } |
934 | ||
ae18d6dc | 935 | static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, |
f25748e3 | 936 | pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write) |
5cad465d MW |
937 | { |
938 | struct mm_struct *mm = vma->vm_mm; | |
939 | pmd_t entry; | |
940 | spinlock_t *ptl; | |
941 | ||
942 | ptl = pmd_lock(mm, pmd); | |
f25748e3 DW |
943 | entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); |
944 | if (pfn_t_devmap(pfn)) | |
945 | entry = pmd_mkdevmap(entry); | |
01871e59 RZ |
946 | if (write) { |
947 | entry = pmd_mkyoung(pmd_mkdirty(entry)); | |
948 | entry = maybe_pmd_mkwrite(entry, vma); | |
5cad465d | 949 | } |
01871e59 RZ |
950 | set_pmd_at(mm, addr, pmd, entry); |
951 | update_mmu_cache_pmd(vma, addr, pmd); | |
5cad465d | 952 | spin_unlock(ptl); |
5cad465d MW |
953 | } |
954 | ||
955 | int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, | |
f25748e3 | 956 | pmd_t *pmd, pfn_t pfn, bool write) |
5cad465d MW |
957 | { |
958 | pgprot_t pgprot = vma->vm_page_prot; | |
959 | /* | |
960 | * If we had pmd_special, we could avoid all these restrictions, | |
961 | * but we need to be consistent with PTEs and architectures that | |
962 | * can't support a 'special' bit. | |
963 | */ | |
964 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); | |
965 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == | |
966 | (VM_PFNMAP|VM_MIXEDMAP)); | |
967 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); | |
f25748e3 | 968 | BUG_ON(!pfn_t_devmap(pfn)); |
5cad465d MW |
969 | |
970 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
971 | return VM_FAULT_SIGBUS; | |
972 | if (track_pfn_insert(vma, &pgprot, pfn)) | |
973 | return VM_FAULT_SIGBUS; | |
ae18d6dc MW |
974 | insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write); |
975 | return VM_FAULT_NOPAGE; | |
5cad465d MW |
976 | } |
977 | ||
3565fce3 DW |
978 | static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, |
979 | pmd_t *pmd) | |
980 | { | |
981 | pmd_t _pmd; | |
982 | ||
983 | /* | |
984 | * We should set the dirty bit only for FOLL_WRITE but for now | |
985 | * the dirty bit in the pmd is meaningless. And if the dirty | |
986 | * bit will become meaningful and we'll only set it with | |
987 | * FOLL_WRITE, an atomic set_bit will be required on the pmd to | |
988 | * set the young bit, instead of the current set_pmd_at. | |
989 | */ | |
990 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
991 | if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, | |
992 | pmd, _pmd, 1)) | |
993 | update_mmu_cache_pmd(vma, addr, pmd); | |
994 | } | |
995 | ||
996 | struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, | |
997 | pmd_t *pmd, int flags) | |
998 | { | |
999 | unsigned long pfn = pmd_pfn(*pmd); | |
1000 | struct mm_struct *mm = vma->vm_mm; | |
1001 | struct dev_pagemap *pgmap; | |
1002 | struct page *page; | |
1003 | ||
1004 | assert_spin_locked(pmd_lockptr(mm, pmd)); | |
1005 | ||
1006 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1007 | return NULL; | |
1008 | ||
1009 | if (pmd_present(*pmd) && pmd_devmap(*pmd)) | |
1010 | /* pass */; | |
1011 | else | |
1012 | return NULL; | |
1013 | ||
1014 | if (flags & FOLL_TOUCH) | |
1015 | touch_pmd(vma, addr, pmd); | |
1016 | ||
1017 | /* | |
1018 | * device mapped pages can only be returned if the | |
1019 | * caller will manage the page reference count. | |
1020 | */ | |
1021 | if (!(flags & FOLL_GET)) | |
1022 | return ERR_PTR(-EEXIST); | |
1023 | ||
1024 | pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; | |
1025 | pgmap = get_dev_pagemap(pfn, NULL); | |
1026 | if (!pgmap) | |
1027 | return ERR_PTR(-EFAULT); | |
1028 | page = pfn_to_page(pfn); | |
1029 | get_page(page); | |
1030 | put_dev_pagemap(pgmap); | |
1031 | ||
1032 | return page; | |
1033 | } | |
1034 | ||
71e3aac0 AA |
1035 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
1036 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
1037 | struct vm_area_struct *vma) | |
1038 | { | |
c4088ebd | 1039 | spinlock_t *dst_ptl, *src_ptl; |
71e3aac0 AA |
1040 | struct page *src_page; |
1041 | pmd_t pmd; | |
1042 | pgtable_t pgtable; | |
1043 | int ret; | |
1044 | ||
1045 | ret = -ENOMEM; | |
1046 | pgtable = pte_alloc_one(dst_mm, addr); | |
1047 | if (unlikely(!pgtable)) | |
1048 | goto out; | |
1049 | ||
c4088ebd KS |
1050 | dst_ptl = pmd_lock(dst_mm, dst_pmd); |
1051 | src_ptl = pmd_lockptr(src_mm, src_pmd); | |
1052 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
71e3aac0 AA |
1053 | |
1054 | ret = -EAGAIN; | |
1055 | pmd = *src_pmd; | |
5c7fb56e | 1056 | if (unlikely(!pmd_trans_huge(pmd) && !pmd_devmap(pmd))) { |
71e3aac0 AA |
1057 | pte_free(dst_mm, pgtable); |
1058 | goto out_unlock; | |
1059 | } | |
fc9fe822 | 1060 | /* |
c4088ebd | 1061 | * When page table lock is held, the huge zero pmd should not be |
fc9fe822 KS |
1062 | * under splitting since we don't split the page itself, only pmd to |
1063 | * a page table. | |
1064 | */ | |
1065 | if (is_huge_zero_pmd(pmd)) { | |
5918d10a | 1066 | struct page *zero_page; |
97ae1749 KS |
1067 | /* |
1068 | * get_huge_zero_page() will never allocate a new page here, | |
1069 | * since we already have a zero page to copy. It just takes a | |
1070 | * reference. | |
1071 | */ | |
5918d10a | 1072 | zero_page = get_huge_zero_page(); |
6b251fc9 | 1073 | set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, |
5918d10a | 1074 | zero_page); |
fc9fe822 KS |
1075 | ret = 0; |
1076 | goto out_unlock; | |
1077 | } | |
de466bd6 | 1078 | |
5c7fb56e DW |
1079 | if (pmd_trans_huge(pmd)) { |
1080 | /* thp accounting separate from pmd_devmap accounting */ | |
1081 | src_page = pmd_page(pmd); | |
1082 | VM_BUG_ON_PAGE(!PageHead(src_page), src_page); | |
1083 | get_page(src_page); | |
1084 | page_dup_rmap(src_page, true); | |
1085 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
1086 | atomic_long_inc(&dst_mm->nr_ptes); | |
1087 | pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); | |
1088 | } | |
71e3aac0 AA |
1089 | |
1090 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
1091 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
1092 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
71e3aac0 AA |
1093 | |
1094 | ret = 0; | |
1095 | out_unlock: | |
c4088ebd KS |
1096 | spin_unlock(src_ptl); |
1097 | spin_unlock(dst_ptl); | |
71e3aac0 AA |
1098 | out: |
1099 | return ret; | |
1100 | } | |
1101 | ||
a1dd450b WD |
1102 | void huge_pmd_set_accessed(struct mm_struct *mm, |
1103 | struct vm_area_struct *vma, | |
1104 | unsigned long address, | |
1105 | pmd_t *pmd, pmd_t orig_pmd, | |
1106 | int dirty) | |
1107 | { | |
c4088ebd | 1108 | spinlock_t *ptl; |
a1dd450b WD |
1109 | pmd_t entry; |
1110 | unsigned long haddr; | |
1111 | ||
c4088ebd | 1112 | ptl = pmd_lock(mm, pmd); |
a1dd450b WD |
1113 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1114 | goto unlock; | |
1115 | ||
1116 | entry = pmd_mkyoung(orig_pmd); | |
1117 | haddr = address & HPAGE_PMD_MASK; | |
1118 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty)) | |
1119 | update_mmu_cache_pmd(vma, address, pmd); | |
1120 | ||
1121 | unlock: | |
c4088ebd | 1122 | spin_unlock(ptl); |
a1dd450b WD |
1123 | } |
1124 | ||
71e3aac0 AA |
1125 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, |
1126 | struct vm_area_struct *vma, | |
1127 | unsigned long address, | |
1128 | pmd_t *pmd, pmd_t orig_pmd, | |
1129 | struct page *page, | |
1130 | unsigned long haddr) | |
1131 | { | |
00501b53 | 1132 | struct mem_cgroup *memcg; |
c4088ebd | 1133 | spinlock_t *ptl; |
71e3aac0 AA |
1134 | pgtable_t pgtable; |
1135 | pmd_t _pmd; | |
1136 | int ret = 0, i; | |
1137 | struct page **pages; | |
2ec74c3e SG |
1138 | unsigned long mmun_start; /* For mmu_notifiers */ |
1139 | unsigned long mmun_end; /* For mmu_notifiers */ | |
71e3aac0 AA |
1140 | |
1141 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
1142 | GFP_KERNEL); | |
1143 | if (unlikely(!pages)) { | |
1144 | ret |= VM_FAULT_OOM; | |
1145 | goto out; | |
1146 | } | |
1147 | ||
1148 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
cc5d462f AK |
1149 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE | |
1150 | __GFP_OTHER_NODE, | |
19ee151e | 1151 | vma, address, page_to_nid(page)); |
b9bbfbe3 | 1152 | if (unlikely(!pages[i] || |
00501b53 | 1153 | mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL, |
f627c2f5 | 1154 | &memcg, false))) { |
b9bbfbe3 | 1155 | if (pages[i]) |
71e3aac0 | 1156 | put_page(pages[i]); |
b9bbfbe3 | 1157 | while (--i >= 0) { |
00501b53 JW |
1158 | memcg = (void *)page_private(pages[i]); |
1159 | set_page_private(pages[i], 0); | |
f627c2f5 KS |
1160 | mem_cgroup_cancel_charge(pages[i], memcg, |
1161 | false); | |
b9bbfbe3 AA |
1162 | put_page(pages[i]); |
1163 | } | |
71e3aac0 AA |
1164 | kfree(pages); |
1165 | ret |= VM_FAULT_OOM; | |
1166 | goto out; | |
1167 | } | |
00501b53 | 1168 | set_page_private(pages[i], (unsigned long)memcg); |
71e3aac0 AA |
1169 | } |
1170 | ||
1171 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1172 | copy_user_highpage(pages[i], page + i, | |
0089e485 | 1173 | haddr + PAGE_SIZE * i, vma); |
71e3aac0 AA |
1174 | __SetPageUptodate(pages[i]); |
1175 | cond_resched(); | |
1176 | } | |
1177 | ||
2ec74c3e SG |
1178 | mmun_start = haddr; |
1179 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1180 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1181 | ||
c4088ebd | 1182 | ptl = pmd_lock(mm, pmd); |
71e3aac0 AA |
1183 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1184 | goto out_free_pages; | |
309381fe | 1185 | VM_BUG_ON_PAGE(!PageHead(page), page); |
71e3aac0 | 1186 | |
8809aa2d | 1187 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
71e3aac0 AA |
1188 | /* leave pmd empty until pte is filled */ |
1189 | ||
6b0b50b0 | 1190 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
71e3aac0 AA |
1191 | pmd_populate(mm, &_pmd, pgtable); |
1192 | ||
1193 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
1194 | pte_t *pte, entry; | |
1195 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
1196 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
00501b53 JW |
1197 | memcg = (void *)page_private(pages[i]); |
1198 | set_page_private(pages[i], 0); | |
d281ee61 | 1199 | page_add_new_anon_rmap(pages[i], vma, haddr, false); |
f627c2f5 | 1200 | mem_cgroup_commit_charge(pages[i], memcg, false, false); |
00501b53 | 1201 | lru_cache_add_active_or_unevictable(pages[i], vma); |
71e3aac0 AA |
1202 | pte = pte_offset_map(&_pmd, haddr); |
1203 | VM_BUG_ON(!pte_none(*pte)); | |
1204 | set_pte_at(mm, haddr, pte, entry); | |
1205 | pte_unmap(pte); | |
1206 | } | |
1207 | kfree(pages); | |
1208 | ||
71e3aac0 AA |
1209 | smp_wmb(); /* make pte visible before pmd */ |
1210 | pmd_populate(mm, pmd, pgtable); | |
d281ee61 | 1211 | page_remove_rmap(page, true); |
c4088ebd | 1212 | spin_unlock(ptl); |
71e3aac0 | 1213 | |
2ec74c3e SG |
1214 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
1215 | ||
71e3aac0 AA |
1216 | ret |= VM_FAULT_WRITE; |
1217 | put_page(page); | |
1218 | ||
1219 | out: | |
1220 | return ret; | |
1221 | ||
1222 | out_free_pages: | |
c4088ebd | 1223 | spin_unlock(ptl); |
2ec74c3e | 1224 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
b9bbfbe3 | 1225 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
00501b53 JW |
1226 | memcg = (void *)page_private(pages[i]); |
1227 | set_page_private(pages[i], 0); | |
f627c2f5 | 1228 | mem_cgroup_cancel_charge(pages[i], memcg, false); |
71e3aac0 | 1229 | put_page(pages[i]); |
b9bbfbe3 | 1230 | } |
71e3aac0 AA |
1231 | kfree(pages); |
1232 | goto out; | |
1233 | } | |
1234 | ||
1235 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
1236 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) | |
1237 | { | |
c4088ebd | 1238 | spinlock_t *ptl; |
71e3aac0 | 1239 | int ret = 0; |
93b4796d | 1240 | struct page *page = NULL, *new_page; |
00501b53 | 1241 | struct mem_cgroup *memcg; |
71e3aac0 | 1242 | unsigned long haddr; |
2ec74c3e SG |
1243 | unsigned long mmun_start; /* For mmu_notifiers */ |
1244 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 1245 | gfp_t huge_gfp; /* for allocation and charge */ |
71e3aac0 | 1246 | |
c4088ebd | 1247 | ptl = pmd_lockptr(mm, pmd); |
81d1b09c | 1248 | VM_BUG_ON_VMA(!vma->anon_vma, vma); |
93b4796d KS |
1249 | haddr = address & HPAGE_PMD_MASK; |
1250 | if (is_huge_zero_pmd(orig_pmd)) | |
1251 | goto alloc; | |
c4088ebd | 1252 | spin_lock(ptl); |
71e3aac0 AA |
1253 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
1254 | goto out_unlock; | |
1255 | ||
1256 | page = pmd_page(orig_pmd); | |
309381fe | 1257 | VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); |
1f25fe20 KS |
1258 | /* |
1259 | * We can only reuse the page if nobody else maps the huge page or it's | |
1260 | * part. We can do it by checking page_mapcount() on each sub-page, but | |
1261 | * it's expensive. | |
1262 | * The cheaper way is to check page_count() to be equal 1: every | |
1263 | * mapcount takes page reference reference, so this way we can | |
1264 | * guarantee, that the PMD is the only mapping. | |
1265 | * This can give false negative if somebody pinned the page, but that's | |
1266 | * fine. | |
1267 | */ | |
1268 | if (page_mapcount(page) == 1 && page_count(page) == 1) { | |
71e3aac0 AA |
1269 | pmd_t entry; |
1270 | entry = pmd_mkyoung(orig_pmd); | |
1271 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
1272 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) | |
b113da65 | 1273 | update_mmu_cache_pmd(vma, address, pmd); |
71e3aac0 AA |
1274 | ret |= VM_FAULT_WRITE; |
1275 | goto out_unlock; | |
1276 | } | |
ddc58f27 | 1277 | get_page(page); |
c4088ebd | 1278 | spin_unlock(ptl); |
93b4796d | 1279 | alloc: |
71e3aac0 | 1280 | if (transparent_hugepage_enabled(vma) && |
077fcf11 | 1281 | !transparent_hugepage_debug_cow()) { |
3b363692 MH |
1282 | huge_gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0); |
1283 | new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); | |
077fcf11 | 1284 | } else |
71e3aac0 AA |
1285 | new_page = NULL; |
1286 | ||
9a982250 KS |
1287 | if (likely(new_page)) { |
1288 | prep_transhuge_page(new_page); | |
1289 | } else { | |
eecc1e42 | 1290 | if (!page) { |
78ddc534 | 1291 | split_huge_pmd(vma, pmd, address); |
e9b71ca9 | 1292 | ret |= VM_FAULT_FALLBACK; |
93b4796d KS |
1293 | } else { |
1294 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, | |
1295 | pmd, orig_pmd, page, haddr); | |
9845cbbd | 1296 | if (ret & VM_FAULT_OOM) { |
78ddc534 | 1297 | split_huge_pmd(vma, pmd, address); |
9845cbbd KS |
1298 | ret |= VM_FAULT_FALLBACK; |
1299 | } | |
ddc58f27 | 1300 | put_page(page); |
93b4796d | 1301 | } |
17766dde | 1302 | count_vm_event(THP_FAULT_FALLBACK); |
71e3aac0 AA |
1303 | goto out; |
1304 | } | |
1305 | ||
f627c2f5 KS |
1306 | if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg, |
1307 | true))) { | |
b9bbfbe3 | 1308 | put_page(new_page); |
93b4796d | 1309 | if (page) { |
78ddc534 | 1310 | split_huge_pmd(vma, pmd, address); |
ddc58f27 | 1311 | put_page(page); |
9845cbbd | 1312 | } else |
78ddc534 | 1313 | split_huge_pmd(vma, pmd, address); |
9845cbbd | 1314 | ret |= VM_FAULT_FALLBACK; |
17766dde | 1315 | count_vm_event(THP_FAULT_FALLBACK); |
b9bbfbe3 AA |
1316 | goto out; |
1317 | } | |
1318 | ||
17766dde DR |
1319 | count_vm_event(THP_FAULT_ALLOC); |
1320 | ||
eecc1e42 | 1321 | if (!page) |
93b4796d KS |
1322 | clear_huge_page(new_page, haddr, HPAGE_PMD_NR); |
1323 | else | |
1324 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); | |
71e3aac0 AA |
1325 | __SetPageUptodate(new_page); |
1326 | ||
2ec74c3e SG |
1327 | mmun_start = haddr; |
1328 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1329 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1330 | ||
c4088ebd | 1331 | spin_lock(ptl); |
93b4796d | 1332 | if (page) |
ddc58f27 | 1333 | put_page(page); |
b9bbfbe3 | 1334 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { |
c4088ebd | 1335 | spin_unlock(ptl); |
f627c2f5 | 1336 | mem_cgroup_cancel_charge(new_page, memcg, true); |
71e3aac0 | 1337 | put_page(new_page); |
2ec74c3e | 1338 | goto out_mn; |
b9bbfbe3 | 1339 | } else { |
71e3aac0 | 1340 | pmd_t entry; |
3122359a KS |
1341 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); |
1342 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
8809aa2d | 1343 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
d281ee61 | 1344 | page_add_new_anon_rmap(new_page, vma, haddr, true); |
f627c2f5 | 1345 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
00501b53 | 1346 | lru_cache_add_active_or_unevictable(new_page, vma); |
71e3aac0 | 1347 | set_pmd_at(mm, haddr, pmd, entry); |
b113da65 | 1348 | update_mmu_cache_pmd(vma, address, pmd); |
eecc1e42 | 1349 | if (!page) { |
93b4796d | 1350 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
97ae1749 KS |
1351 | put_huge_zero_page(); |
1352 | } else { | |
309381fe | 1353 | VM_BUG_ON_PAGE(!PageHead(page), page); |
d281ee61 | 1354 | page_remove_rmap(page, true); |
93b4796d KS |
1355 | put_page(page); |
1356 | } | |
71e3aac0 AA |
1357 | ret |= VM_FAULT_WRITE; |
1358 | } | |
c4088ebd | 1359 | spin_unlock(ptl); |
2ec74c3e SG |
1360 | out_mn: |
1361 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
71e3aac0 AA |
1362 | out: |
1363 | return ret; | |
2ec74c3e | 1364 | out_unlock: |
c4088ebd | 1365 | spin_unlock(ptl); |
2ec74c3e | 1366 | return ret; |
71e3aac0 AA |
1367 | } |
1368 | ||
b676b293 | 1369 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, |
71e3aac0 AA |
1370 | unsigned long addr, |
1371 | pmd_t *pmd, | |
1372 | unsigned int flags) | |
1373 | { | |
b676b293 | 1374 | struct mm_struct *mm = vma->vm_mm; |
71e3aac0 AA |
1375 | struct page *page = NULL; |
1376 | ||
c4088ebd | 1377 | assert_spin_locked(pmd_lockptr(mm, pmd)); |
71e3aac0 AA |
1378 | |
1379 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1380 | goto out; | |
1381 | ||
85facf25 KS |
1382 | /* Avoid dumping huge zero page */ |
1383 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) | |
1384 | return ERR_PTR(-EFAULT); | |
1385 | ||
2b4847e7 | 1386 | /* Full NUMA hinting faults to serialise migration in fault paths */ |
8a0516ed | 1387 | if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) |
2b4847e7 MG |
1388 | goto out; |
1389 | ||
71e3aac0 | 1390 | page = pmd_page(*pmd); |
309381fe | 1391 | VM_BUG_ON_PAGE(!PageHead(page), page); |
3565fce3 DW |
1392 | if (flags & FOLL_TOUCH) |
1393 | touch_pmd(vma, addr, pmd); | |
de60f5f1 | 1394 | if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { |
e90309c9 KS |
1395 | /* |
1396 | * We don't mlock() pte-mapped THPs. This way we can avoid | |
1397 | * leaking mlocked pages into non-VM_LOCKED VMAs. | |
1398 | * | |
1399 | * In most cases the pmd is the only mapping of the page as we | |
1400 | * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for | |
1401 | * writable private mappings in populate_vma_page_range(). | |
1402 | * | |
1403 | * The only scenario when we have the page shared here is if we | |
1404 | * mlocking read-only mapping shared over fork(). We skip | |
1405 | * mlocking such pages. | |
1406 | */ | |
1407 | if (compound_mapcount(page) == 1 && !PageDoubleMap(page) && | |
1408 | page->mapping && trylock_page(page)) { | |
b676b293 DR |
1409 | lru_add_drain(); |
1410 | if (page->mapping) | |
1411 | mlock_vma_page(page); | |
1412 | unlock_page(page); | |
1413 | } | |
1414 | } | |
71e3aac0 | 1415 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
309381fe | 1416 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
71e3aac0 | 1417 | if (flags & FOLL_GET) |
ddc58f27 | 1418 | get_page(page); |
71e3aac0 AA |
1419 | |
1420 | out: | |
1421 | return page; | |
1422 | } | |
1423 | ||
d10e63f2 | 1424 | /* NUMA hinting page fault entry point for trans huge pmds */ |
4daae3b4 MG |
1425 | int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, |
1426 | unsigned long addr, pmd_t pmd, pmd_t *pmdp) | |
d10e63f2 | 1427 | { |
c4088ebd | 1428 | spinlock_t *ptl; |
b8916634 | 1429 | struct anon_vma *anon_vma = NULL; |
b32967ff | 1430 | struct page *page; |
d10e63f2 | 1431 | unsigned long haddr = addr & HPAGE_PMD_MASK; |
8191acbd | 1432 | int page_nid = -1, this_nid = numa_node_id(); |
90572890 | 1433 | int target_nid, last_cpupid = -1; |
8191acbd MG |
1434 | bool page_locked; |
1435 | bool migrated = false; | |
b191f9b1 | 1436 | bool was_writable; |
6688cc05 | 1437 | int flags = 0; |
d10e63f2 | 1438 | |
c0e7cad9 MG |
1439 | /* A PROT_NONE fault should not end up here */ |
1440 | BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))); | |
1441 | ||
c4088ebd | 1442 | ptl = pmd_lock(mm, pmdp); |
d10e63f2 MG |
1443 | if (unlikely(!pmd_same(pmd, *pmdp))) |
1444 | goto out_unlock; | |
1445 | ||
de466bd6 MG |
1446 | /* |
1447 | * If there are potential migrations, wait for completion and retry | |
1448 | * without disrupting NUMA hinting information. Do not relock and | |
1449 | * check_same as the page may no longer be mapped. | |
1450 | */ | |
1451 | if (unlikely(pmd_trans_migrating(*pmdp))) { | |
5d833062 | 1452 | page = pmd_page(*pmdp); |
de466bd6 | 1453 | spin_unlock(ptl); |
5d833062 | 1454 | wait_on_page_locked(page); |
de466bd6 MG |
1455 | goto out; |
1456 | } | |
1457 | ||
d10e63f2 | 1458 | page = pmd_page(pmd); |
a1a46184 | 1459 | BUG_ON(is_huge_zero_page(page)); |
8191acbd | 1460 | page_nid = page_to_nid(page); |
90572890 | 1461 | last_cpupid = page_cpupid_last(page); |
03c5a6e1 | 1462 | count_vm_numa_event(NUMA_HINT_FAULTS); |
04bb2f94 | 1463 | if (page_nid == this_nid) { |
03c5a6e1 | 1464 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
04bb2f94 RR |
1465 | flags |= TNF_FAULT_LOCAL; |
1466 | } | |
4daae3b4 | 1467 | |
bea66fbd MG |
1468 | /* See similar comment in do_numa_page for explanation */ |
1469 | if (!(vma->vm_flags & VM_WRITE)) | |
6688cc05 PZ |
1470 | flags |= TNF_NO_GROUP; |
1471 | ||
ff9042b1 MG |
1472 | /* |
1473 | * Acquire the page lock to serialise THP migrations but avoid dropping | |
1474 | * page_table_lock if at all possible | |
1475 | */ | |
b8916634 MG |
1476 | page_locked = trylock_page(page); |
1477 | target_nid = mpol_misplaced(page, vma, haddr); | |
1478 | if (target_nid == -1) { | |
1479 | /* If the page was locked, there are no parallel migrations */ | |
a54a407f | 1480 | if (page_locked) |
b8916634 | 1481 | goto clear_pmdnuma; |
2b4847e7 | 1482 | } |
4daae3b4 | 1483 | |
de466bd6 | 1484 | /* Migration could have started since the pmd_trans_migrating check */ |
2b4847e7 | 1485 | if (!page_locked) { |
c4088ebd | 1486 | spin_unlock(ptl); |
b8916634 | 1487 | wait_on_page_locked(page); |
a54a407f | 1488 | page_nid = -1; |
b8916634 MG |
1489 | goto out; |
1490 | } | |
1491 | ||
2b4847e7 MG |
1492 | /* |
1493 | * Page is misplaced. Page lock serialises migrations. Acquire anon_vma | |
1494 | * to serialises splits | |
1495 | */ | |
b8916634 | 1496 | get_page(page); |
c4088ebd | 1497 | spin_unlock(ptl); |
b8916634 | 1498 | anon_vma = page_lock_anon_vma_read(page); |
4daae3b4 | 1499 | |
c69307d5 | 1500 | /* Confirm the PMD did not change while page_table_lock was released */ |
c4088ebd | 1501 | spin_lock(ptl); |
b32967ff MG |
1502 | if (unlikely(!pmd_same(pmd, *pmdp))) { |
1503 | unlock_page(page); | |
1504 | put_page(page); | |
a54a407f | 1505 | page_nid = -1; |
4daae3b4 | 1506 | goto out_unlock; |
b32967ff | 1507 | } |
ff9042b1 | 1508 | |
c3a489ca MG |
1509 | /* Bail if we fail to protect against THP splits for any reason */ |
1510 | if (unlikely(!anon_vma)) { | |
1511 | put_page(page); | |
1512 | page_nid = -1; | |
1513 | goto clear_pmdnuma; | |
1514 | } | |
1515 | ||
a54a407f MG |
1516 | /* |
1517 | * Migrate the THP to the requested node, returns with page unlocked | |
8a0516ed | 1518 | * and access rights restored. |
a54a407f | 1519 | */ |
c4088ebd | 1520 | spin_unlock(ptl); |
b32967ff | 1521 | migrated = migrate_misplaced_transhuge_page(mm, vma, |
340ef390 | 1522 | pmdp, pmd, addr, page, target_nid); |
6688cc05 PZ |
1523 | if (migrated) { |
1524 | flags |= TNF_MIGRATED; | |
8191acbd | 1525 | page_nid = target_nid; |
074c2381 MG |
1526 | } else |
1527 | flags |= TNF_MIGRATE_FAIL; | |
b32967ff | 1528 | |
8191acbd | 1529 | goto out; |
b32967ff | 1530 | clear_pmdnuma: |
a54a407f | 1531 | BUG_ON(!PageLocked(page)); |
b191f9b1 | 1532 | was_writable = pmd_write(pmd); |
4d942466 | 1533 | pmd = pmd_modify(pmd, vma->vm_page_prot); |
b7b04004 | 1534 | pmd = pmd_mkyoung(pmd); |
b191f9b1 MG |
1535 | if (was_writable) |
1536 | pmd = pmd_mkwrite(pmd); | |
d10e63f2 | 1537 | set_pmd_at(mm, haddr, pmdp, pmd); |
d10e63f2 | 1538 | update_mmu_cache_pmd(vma, addr, pmdp); |
a54a407f | 1539 | unlock_page(page); |
d10e63f2 | 1540 | out_unlock: |
c4088ebd | 1541 | spin_unlock(ptl); |
b8916634 MG |
1542 | |
1543 | out: | |
1544 | if (anon_vma) | |
1545 | page_unlock_anon_vma_read(anon_vma); | |
1546 | ||
8191acbd | 1547 | if (page_nid != -1) |
6688cc05 | 1548 | task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags); |
8191acbd | 1549 | |
d10e63f2 MG |
1550 | return 0; |
1551 | } | |
1552 | ||
b8d3c4c3 MK |
1553 | int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
1554 | pmd_t *pmd, unsigned long addr, unsigned long next) | |
1555 | ||
1556 | { | |
1557 | spinlock_t *ptl; | |
1558 | pmd_t orig_pmd; | |
1559 | struct page *page; | |
1560 | struct mm_struct *mm = tlb->mm; | |
1561 | int ret = 0; | |
1562 | ||
1563 | if (!pmd_trans_huge_lock(pmd, vma, &ptl)) | |
25eedabe | 1564 | goto out_unlocked; |
b8d3c4c3 MK |
1565 | |
1566 | orig_pmd = *pmd; | |
1567 | if (is_huge_zero_pmd(orig_pmd)) { | |
1568 | ret = 1; | |
1569 | goto out; | |
1570 | } | |
1571 | ||
1572 | page = pmd_page(orig_pmd); | |
1573 | /* | |
1574 | * If other processes are mapping this page, we couldn't discard | |
1575 | * the page unless they all do MADV_FREE so let's skip the page. | |
1576 | */ | |
1577 | if (page_mapcount(page) != 1) | |
1578 | goto out; | |
1579 | ||
1580 | if (!trylock_page(page)) | |
1581 | goto out; | |
1582 | ||
1583 | /* | |
1584 | * If user want to discard part-pages of THP, split it so MADV_FREE | |
1585 | * will deactivate only them. | |
1586 | */ | |
1587 | if (next - addr != HPAGE_PMD_SIZE) { | |
1588 | get_page(page); | |
1589 | spin_unlock(ptl); | |
1590 | if (split_huge_page(page)) { | |
1591 | put_page(page); | |
1592 | unlock_page(page); | |
1593 | goto out_unlocked; | |
1594 | } | |
1595 | put_page(page); | |
1596 | unlock_page(page); | |
1597 | ret = 1; | |
1598 | goto out_unlocked; | |
1599 | } | |
1600 | ||
1601 | if (PageDirty(page)) | |
1602 | ClearPageDirty(page); | |
1603 | unlock_page(page); | |
1604 | ||
1605 | if (PageActive(page)) | |
1606 | deactivate_page(page); | |
1607 | ||
1608 | if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { | |
1609 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1610 | tlb->fullmm); | |
1611 | orig_pmd = pmd_mkold(orig_pmd); | |
1612 | orig_pmd = pmd_mkclean(orig_pmd); | |
1613 | ||
1614 | set_pmd_at(mm, addr, pmd, orig_pmd); | |
1615 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1616 | } | |
1617 | ret = 1; | |
1618 | out: | |
1619 | spin_unlock(ptl); | |
1620 | out_unlocked: | |
1621 | return ret; | |
1622 | } | |
1623 | ||
71e3aac0 | 1624 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
f21760b1 | 1625 | pmd_t *pmd, unsigned long addr) |
71e3aac0 | 1626 | { |
da146769 | 1627 | pmd_t orig_pmd; |
bf929152 | 1628 | spinlock_t *ptl; |
71e3aac0 | 1629 | |
4b471e88 | 1630 | if (!__pmd_trans_huge_lock(pmd, vma, &ptl)) |
da146769 KS |
1631 | return 0; |
1632 | /* | |
1633 | * For architectures like ppc64 we look at deposited pgtable | |
1634 | * when calling pmdp_huge_get_and_clear. So do the | |
1635 | * pgtable_trans_huge_withdraw after finishing pmdp related | |
1636 | * operations. | |
1637 | */ | |
1638 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1639 | tlb->fullmm); | |
1640 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1641 | if (vma_is_dax(vma)) { | |
1642 | spin_unlock(ptl); | |
1643 | if (is_huge_zero_pmd(orig_pmd)) | |
97ae1749 | 1644 | put_huge_zero_page(); |
da146769 KS |
1645 | } else if (is_huge_zero_pmd(orig_pmd)) { |
1646 | pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); | |
1647 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1648 | spin_unlock(ptl); | |
1649 | put_huge_zero_page(); | |
1650 | } else { | |
1651 | struct page *page = pmd_page(orig_pmd); | |
d281ee61 | 1652 | page_remove_rmap(page, true); |
da146769 KS |
1653 | VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); |
1654 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1655 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
1656 | pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); | |
1657 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1658 | spin_unlock(ptl); | |
1659 | tlb_remove_page(tlb, page); | |
025c5b24 | 1660 | } |
da146769 | 1661 | return 1; |
71e3aac0 AA |
1662 | } |
1663 | ||
4b471e88 | 1664 | bool move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, |
37a1c49a AA |
1665 | unsigned long old_addr, |
1666 | unsigned long new_addr, unsigned long old_end, | |
1667 | pmd_t *old_pmd, pmd_t *new_pmd) | |
1668 | { | |
bf929152 | 1669 | spinlock_t *old_ptl, *new_ptl; |
37a1c49a AA |
1670 | pmd_t pmd; |
1671 | ||
1672 | struct mm_struct *mm = vma->vm_mm; | |
1673 | ||
1674 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1675 | (new_addr & ~HPAGE_PMD_MASK) || | |
1676 | old_end - old_addr < HPAGE_PMD_SIZE || | |
1677 | (new_vma->vm_flags & VM_NOHUGEPAGE)) | |
4b471e88 | 1678 | return false; |
37a1c49a AA |
1679 | |
1680 | /* | |
1681 | * The destination pmd shouldn't be established, free_pgtables() | |
1682 | * should have release it. | |
1683 | */ | |
1684 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1685 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
4b471e88 | 1686 | return false; |
37a1c49a AA |
1687 | } |
1688 | ||
bf929152 KS |
1689 | /* |
1690 | * We don't have to worry about the ordering of src and dst | |
1691 | * ptlocks because exclusive mmap_sem prevents deadlock. | |
1692 | */ | |
4b471e88 | 1693 | if (__pmd_trans_huge_lock(old_pmd, vma, &old_ptl)) { |
bf929152 KS |
1694 | new_ptl = pmd_lockptr(mm, new_pmd); |
1695 | if (new_ptl != old_ptl) | |
1696 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); | |
8809aa2d | 1697 | pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); |
025c5b24 | 1698 | VM_BUG_ON(!pmd_none(*new_pmd)); |
3592806c | 1699 | |
b3084f4d AK |
1700 | if (pmd_move_must_withdraw(new_ptl, old_ptl)) { |
1701 | pgtable_t pgtable; | |
3592806c KS |
1702 | pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); |
1703 | pgtable_trans_huge_deposit(mm, new_pmd, pgtable); | |
3592806c | 1704 | } |
b3084f4d AK |
1705 | set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); |
1706 | if (new_ptl != old_ptl) | |
1707 | spin_unlock(new_ptl); | |
bf929152 | 1708 | spin_unlock(old_ptl); |
4b471e88 | 1709 | return true; |
37a1c49a | 1710 | } |
4b471e88 | 1711 | return false; |
37a1c49a AA |
1712 | } |
1713 | ||
f123d74a MG |
1714 | /* |
1715 | * Returns | |
1716 | * - 0 if PMD could not be locked | |
1717 | * - 1 if PMD was locked but protections unchange and TLB flush unnecessary | |
1718 | * - HPAGE_PMD_NR is protections changed and TLB flush necessary | |
1719 | */ | |
cd7548ab | 1720 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
e944fd67 | 1721 | unsigned long addr, pgprot_t newprot, int prot_numa) |
cd7548ab JW |
1722 | { |
1723 | struct mm_struct *mm = vma->vm_mm; | |
bf929152 | 1724 | spinlock_t *ptl; |
cd7548ab JW |
1725 | int ret = 0; |
1726 | ||
4b471e88 | 1727 | if (__pmd_trans_huge_lock(pmd, vma, &ptl)) { |
025c5b24 | 1728 | pmd_t entry; |
b191f9b1 | 1729 | bool preserve_write = prot_numa && pmd_write(*pmd); |
ba68bc01 | 1730 | ret = 1; |
e944fd67 MG |
1731 | |
1732 | /* | |
1733 | * Avoid trapping faults against the zero page. The read-only | |
1734 | * data is likely to be read-cached on the local CPU and | |
1735 | * local/remote hits to the zero page are not interesting. | |
1736 | */ | |
1737 | if (prot_numa && is_huge_zero_pmd(*pmd)) { | |
1738 | spin_unlock(ptl); | |
ba68bc01 | 1739 | return ret; |
e944fd67 MG |
1740 | } |
1741 | ||
10c1045f | 1742 | if (!prot_numa || !pmd_protnone(*pmd)) { |
8809aa2d | 1743 | entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd); |
10c1045f | 1744 | entry = pmd_modify(entry, newprot); |
b191f9b1 MG |
1745 | if (preserve_write) |
1746 | entry = pmd_mkwrite(entry); | |
10c1045f MG |
1747 | ret = HPAGE_PMD_NR; |
1748 | set_pmd_at(mm, addr, pmd, entry); | |
b191f9b1 | 1749 | BUG_ON(!preserve_write && pmd_write(entry)); |
10c1045f | 1750 | } |
bf929152 | 1751 | spin_unlock(ptl); |
025c5b24 NH |
1752 | } |
1753 | ||
1754 | return ret; | |
1755 | } | |
1756 | ||
1757 | /* | |
4b471e88 | 1758 | * Returns true if a given pmd maps a thp, false otherwise. |
025c5b24 | 1759 | * |
4b471e88 KS |
1760 | * Note that if it returns true, this routine returns without unlocking page |
1761 | * table lock. So callers must unlock it. | |
025c5b24 | 1762 | */ |
4b471e88 | 1763 | bool __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma, |
bf929152 | 1764 | spinlock_t **ptl) |
025c5b24 | 1765 | { |
bf929152 | 1766 | *ptl = pmd_lock(vma->vm_mm, pmd); |
5c7fb56e | 1767 | if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd))) |
4b471e88 | 1768 | return true; |
bf929152 | 1769 | spin_unlock(*ptl); |
4b471e88 | 1770 | return false; |
cd7548ab JW |
1771 | } |
1772 | ||
9050d7eb | 1773 | #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE) |
78f11a25 | 1774 | |
60ab3244 AA |
1775 | int hugepage_madvise(struct vm_area_struct *vma, |
1776 | unsigned long *vm_flags, int advice) | |
0af4e98b | 1777 | { |
a664b2d8 AA |
1778 | switch (advice) { |
1779 | case MADV_HUGEPAGE: | |
1e1836e8 AT |
1780 | #ifdef CONFIG_S390 |
1781 | /* | |
1782 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
1783 | * can't handle this properly after s390_enable_sie, so we simply | |
1784 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
1785 | */ | |
1786 | if (mm_has_pgste(vma->vm_mm)) | |
1787 | return 0; | |
1788 | #endif | |
a664b2d8 AA |
1789 | /* |
1790 | * Be somewhat over-protective like KSM for now! | |
1791 | */ | |
1a763615 | 1792 | if (*vm_flags & VM_NO_THP) |
a664b2d8 AA |
1793 | return -EINVAL; |
1794 | *vm_flags &= ~VM_NOHUGEPAGE; | |
1795 | *vm_flags |= VM_HUGEPAGE; | |
60ab3244 AA |
1796 | /* |
1797 | * If the vma become good for khugepaged to scan, | |
1798 | * register it here without waiting a page fault that | |
1799 | * may not happen any time soon. | |
1800 | */ | |
6d50e60c | 1801 | if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags))) |
60ab3244 | 1802 | return -ENOMEM; |
a664b2d8 AA |
1803 | break; |
1804 | case MADV_NOHUGEPAGE: | |
1805 | /* | |
1806 | * Be somewhat over-protective like KSM for now! | |
1807 | */ | |
1a763615 | 1808 | if (*vm_flags & VM_NO_THP) |
a664b2d8 AA |
1809 | return -EINVAL; |
1810 | *vm_flags &= ~VM_HUGEPAGE; | |
1811 | *vm_flags |= VM_NOHUGEPAGE; | |
60ab3244 AA |
1812 | /* |
1813 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
1814 | * this vma even if we leave the mm registered in khugepaged if | |
1815 | * it got registered before VM_NOHUGEPAGE was set. | |
1816 | */ | |
a664b2d8 AA |
1817 | break; |
1818 | } | |
0af4e98b AA |
1819 | |
1820 | return 0; | |
1821 | } | |
1822 | ||
ba76149f AA |
1823 | static int __init khugepaged_slab_init(void) |
1824 | { | |
1825 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
1826 | sizeof(struct mm_slot), | |
1827 | __alignof__(struct mm_slot), 0, NULL); | |
1828 | if (!mm_slot_cache) | |
1829 | return -ENOMEM; | |
1830 | ||
1831 | return 0; | |
1832 | } | |
1833 | ||
65ebb64f KS |
1834 | static void __init khugepaged_slab_exit(void) |
1835 | { | |
1836 | kmem_cache_destroy(mm_slot_cache); | |
1837 | } | |
1838 | ||
ba76149f AA |
1839 | static inline struct mm_slot *alloc_mm_slot(void) |
1840 | { | |
1841 | if (!mm_slot_cache) /* initialization failed */ | |
1842 | return NULL; | |
1843 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
1844 | } | |
1845 | ||
1846 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
1847 | { | |
1848 | kmem_cache_free(mm_slot_cache, mm_slot); | |
1849 | } | |
1850 | ||
ba76149f AA |
1851 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) |
1852 | { | |
1853 | struct mm_slot *mm_slot; | |
ba76149f | 1854 | |
b67bfe0d | 1855 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) |
ba76149f AA |
1856 | if (mm == mm_slot->mm) |
1857 | return mm_slot; | |
43b5fbbd | 1858 | |
ba76149f AA |
1859 | return NULL; |
1860 | } | |
1861 | ||
1862 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
1863 | struct mm_slot *mm_slot) | |
1864 | { | |
ba76149f | 1865 | mm_slot->mm = mm; |
43b5fbbd | 1866 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); |
ba76149f AA |
1867 | } |
1868 | ||
1869 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
1870 | { | |
1871 | return atomic_read(&mm->mm_users) == 0; | |
1872 | } | |
1873 | ||
1874 | int __khugepaged_enter(struct mm_struct *mm) | |
1875 | { | |
1876 | struct mm_slot *mm_slot; | |
1877 | int wakeup; | |
1878 | ||
1879 | mm_slot = alloc_mm_slot(); | |
1880 | if (!mm_slot) | |
1881 | return -ENOMEM; | |
1882 | ||
1883 | /* __khugepaged_exit() must not run from under us */ | |
96dad67f | 1884 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); |
ba76149f AA |
1885 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { |
1886 | free_mm_slot(mm_slot); | |
1887 | return 0; | |
1888 | } | |
1889 | ||
1890 | spin_lock(&khugepaged_mm_lock); | |
1891 | insert_to_mm_slots_hash(mm, mm_slot); | |
1892 | /* | |
1893 | * Insert just behind the scanning cursor, to let the area settle | |
1894 | * down a little. | |
1895 | */ | |
1896 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
1897 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
1898 | spin_unlock(&khugepaged_mm_lock); | |
1899 | ||
1900 | atomic_inc(&mm->mm_count); | |
1901 | if (wakeup) | |
1902 | wake_up_interruptible(&khugepaged_wait); | |
1903 | ||
1904 | return 0; | |
1905 | } | |
1906 | ||
6d50e60c DR |
1907 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, |
1908 | unsigned long vm_flags) | |
ba76149f AA |
1909 | { |
1910 | unsigned long hstart, hend; | |
1911 | if (!vma->anon_vma) | |
1912 | /* | |
1913 | * Not yet faulted in so we will register later in the | |
1914 | * page fault if needed. | |
1915 | */ | |
1916 | return 0; | |
78f11a25 | 1917 | if (vma->vm_ops) |
ba76149f AA |
1918 | /* khugepaged not yet working on file or special mappings */ |
1919 | return 0; | |
6d50e60c | 1920 | VM_BUG_ON_VMA(vm_flags & VM_NO_THP, vma); |
ba76149f AA |
1921 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
1922 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1923 | if (hstart < hend) | |
6d50e60c | 1924 | return khugepaged_enter(vma, vm_flags); |
ba76149f AA |
1925 | return 0; |
1926 | } | |
1927 | ||
1928 | void __khugepaged_exit(struct mm_struct *mm) | |
1929 | { | |
1930 | struct mm_slot *mm_slot; | |
1931 | int free = 0; | |
1932 | ||
1933 | spin_lock(&khugepaged_mm_lock); | |
1934 | mm_slot = get_mm_slot(mm); | |
1935 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
43b5fbbd | 1936 | hash_del(&mm_slot->hash); |
ba76149f AA |
1937 | list_del(&mm_slot->mm_node); |
1938 | free = 1; | |
1939 | } | |
d788e80a | 1940 | spin_unlock(&khugepaged_mm_lock); |
ba76149f AA |
1941 | |
1942 | if (free) { | |
ba76149f AA |
1943 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); |
1944 | free_mm_slot(mm_slot); | |
1945 | mmdrop(mm); | |
1946 | } else if (mm_slot) { | |
ba76149f AA |
1947 | /* |
1948 | * This is required to serialize against | |
1949 | * khugepaged_test_exit() (which is guaranteed to run | |
1950 | * under mmap sem read mode). Stop here (after we | |
1951 | * return all pagetables will be destroyed) until | |
1952 | * khugepaged has finished working on the pagetables | |
1953 | * under the mmap_sem. | |
1954 | */ | |
1955 | down_write(&mm->mmap_sem); | |
1956 | up_write(&mm->mmap_sem); | |
d788e80a | 1957 | } |
ba76149f AA |
1958 | } |
1959 | ||
1960 | static void release_pte_page(struct page *page) | |
1961 | { | |
1962 | /* 0 stands for page_is_file_cache(page) == false */ | |
1963 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
1964 | unlock_page(page); | |
1965 | putback_lru_page(page); | |
1966 | } | |
1967 | ||
1968 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
1969 | { | |
1970 | while (--_pte >= pte) { | |
1971 | pte_t pteval = *_pte; | |
ca0984ca | 1972 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) |
ba76149f AA |
1973 | release_pte_page(pte_page(pteval)); |
1974 | } | |
1975 | } | |
1976 | ||
ba76149f AA |
1977 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, |
1978 | unsigned long address, | |
1979 | pte_t *pte) | |
1980 | { | |
7d2eba05 | 1981 | struct page *page = NULL; |
ba76149f | 1982 | pte_t *_pte; |
7d2eba05 | 1983 | int none_or_zero = 0, result = 0; |
10359213 | 1984 | bool referenced = false, writable = false; |
7d2eba05 | 1985 | |
ba76149f AA |
1986 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; |
1987 | _pte++, address += PAGE_SIZE) { | |
1988 | pte_t pteval = *_pte; | |
47aee4d8 MK |
1989 | if (pte_none(pteval) || (pte_present(pteval) && |
1990 | is_zero_pfn(pte_pfn(pteval)))) { | |
c1294d05 | 1991 | if (!userfaultfd_armed(vma) && |
7d2eba05 | 1992 | ++none_or_zero <= khugepaged_max_ptes_none) { |
ba76149f | 1993 | continue; |
7d2eba05 EA |
1994 | } else { |
1995 | result = SCAN_EXCEED_NONE_PTE; | |
ba76149f | 1996 | goto out; |
7d2eba05 | 1997 | } |
ba76149f | 1998 | } |
7d2eba05 EA |
1999 | if (!pte_present(pteval)) { |
2000 | result = SCAN_PTE_NON_PRESENT; | |
ba76149f | 2001 | goto out; |
7d2eba05 | 2002 | } |
ba76149f | 2003 | page = vm_normal_page(vma, address, pteval); |
7d2eba05 EA |
2004 | if (unlikely(!page)) { |
2005 | result = SCAN_PAGE_NULL; | |
ba76149f | 2006 | goto out; |
7d2eba05 | 2007 | } |
344aa35c | 2008 | |
309381fe SL |
2009 | VM_BUG_ON_PAGE(PageCompound(page), page); |
2010 | VM_BUG_ON_PAGE(!PageAnon(page), page); | |
2011 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
ba76149f | 2012 | |
ba76149f AA |
2013 | /* |
2014 | * We can do it before isolate_lru_page because the | |
2015 | * page can't be freed from under us. NOTE: PG_lock | |
2016 | * is needed to serialize against split_huge_page | |
2017 | * when invoked from the VM. | |
2018 | */ | |
7d2eba05 EA |
2019 | if (!trylock_page(page)) { |
2020 | result = SCAN_PAGE_LOCK; | |
ba76149f | 2021 | goto out; |
7d2eba05 | 2022 | } |
10359213 EA |
2023 | |
2024 | /* | |
2025 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2026 | * The page must only be referenced by the scanned process | |
2027 | * and page swap cache. | |
2028 | */ | |
2029 | if (page_count(page) != 1 + !!PageSwapCache(page)) { | |
2030 | unlock_page(page); | |
7d2eba05 | 2031 | result = SCAN_PAGE_COUNT; |
10359213 EA |
2032 | goto out; |
2033 | } | |
2034 | if (pte_write(pteval)) { | |
2035 | writable = true; | |
2036 | } else { | |
2037 | if (PageSwapCache(page) && !reuse_swap_page(page)) { | |
2038 | unlock_page(page); | |
7d2eba05 | 2039 | result = SCAN_SWAP_CACHE_PAGE; |
10359213 EA |
2040 | goto out; |
2041 | } | |
2042 | /* | |
2043 | * Page is not in the swap cache. It can be collapsed | |
2044 | * into a THP. | |
2045 | */ | |
2046 | } | |
2047 | ||
ba76149f AA |
2048 | /* |
2049 | * Isolate the page to avoid collapsing an hugepage | |
2050 | * currently in use by the VM. | |
2051 | */ | |
2052 | if (isolate_lru_page(page)) { | |
2053 | unlock_page(page); | |
7d2eba05 | 2054 | result = SCAN_DEL_PAGE_LRU; |
ba76149f AA |
2055 | goto out; |
2056 | } | |
2057 | /* 0 stands for page_is_file_cache(page) == false */ | |
2058 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
309381fe SL |
2059 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
2060 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
ba76149f AA |
2061 | |
2062 | /* If there is no mapped pte young don't collapse the page */ | |
33c3fc71 VD |
2063 | if (pte_young(pteval) || |
2064 | page_is_young(page) || PageReferenced(page) || | |
8ee53820 | 2065 | mmu_notifier_test_young(vma->vm_mm, address)) |
10359213 | 2066 | referenced = true; |
ba76149f | 2067 | } |
7d2eba05 EA |
2068 | if (likely(writable)) { |
2069 | if (likely(referenced)) { | |
2070 | result = SCAN_SUCCEED; | |
2071 | trace_mm_collapse_huge_page_isolate(page_to_pfn(page), none_or_zero, | |
2072 | referenced, writable, result); | |
2073 | return 1; | |
2074 | } | |
2075 | } else { | |
2076 | result = SCAN_PAGE_RO; | |
2077 | } | |
2078 | ||
ba76149f | 2079 | out: |
344aa35c | 2080 | release_pte_pages(pte, _pte); |
7d2eba05 EA |
2081 | trace_mm_collapse_huge_page_isolate(page_to_pfn(page), none_or_zero, |
2082 | referenced, writable, result); | |
344aa35c | 2083 | return 0; |
ba76149f AA |
2084 | } |
2085 | ||
2086 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
2087 | struct vm_area_struct *vma, | |
2088 | unsigned long address, | |
2089 | spinlock_t *ptl) | |
2090 | { | |
2091 | pte_t *_pte; | |
2092 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { | |
2093 | pte_t pteval = *_pte; | |
2094 | struct page *src_page; | |
2095 | ||
ca0984ca | 2096 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
ba76149f AA |
2097 | clear_user_highpage(page, address); |
2098 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
ca0984ca EA |
2099 | if (is_zero_pfn(pte_pfn(pteval))) { |
2100 | /* | |
2101 | * ptl mostly unnecessary. | |
2102 | */ | |
2103 | spin_lock(ptl); | |
2104 | /* | |
2105 | * paravirt calls inside pte_clear here are | |
2106 | * superfluous. | |
2107 | */ | |
2108 | pte_clear(vma->vm_mm, address, _pte); | |
2109 | spin_unlock(ptl); | |
2110 | } | |
ba76149f AA |
2111 | } else { |
2112 | src_page = pte_page(pteval); | |
2113 | copy_user_highpage(page, src_page, address, vma); | |
309381fe | 2114 | VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page); |
ba76149f AA |
2115 | release_pte_page(src_page); |
2116 | /* | |
2117 | * ptl mostly unnecessary, but preempt has to | |
2118 | * be disabled to update the per-cpu stats | |
2119 | * inside page_remove_rmap(). | |
2120 | */ | |
2121 | spin_lock(ptl); | |
2122 | /* | |
2123 | * paravirt calls inside pte_clear here are | |
2124 | * superfluous. | |
2125 | */ | |
2126 | pte_clear(vma->vm_mm, address, _pte); | |
d281ee61 | 2127 | page_remove_rmap(src_page, false); |
ba76149f AA |
2128 | spin_unlock(ptl); |
2129 | free_page_and_swap_cache(src_page); | |
2130 | } | |
2131 | ||
2132 | address += PAGE_SIZE; | |
2133 | page++; | |
2134 | } | |
2135 | } | |
2136 | ||
26234f36 | 2137 | static void khugepaged_alloc_sleep(void) |
ba76149f | 2138 | { |
bde43c6c PM |
2139 | DEFINE_WAIT(wait); |
2140 | ||
2141 | add_wait_queue(&khugepaged_wait, &wait); | |
2142 | freezable_schedule_timeout_interruptible( | |
2143 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
2144 | remove_wait_queue(&khugepaged_wait, &wait); | |
26234f36 | 2145 | } |
ba76149f | 2146 | |
9f1b868a BL |
2147 | static int khugepaged_node_load[MAX_NUMNODES]; |
2148 | ||
14a4e214 DR |
2149 | static bool khugepaged_scan_abort(int nid) |
2150 | { | |
2151 | int i; | |
2152 | ||
2153 | /* | |
2154 | * If zone_reclaim_mode is disabled, then no extra effort is made to | |
2155 | * allocate memory locally. | |
2156 | */ | |
2157 | if (!zone_reclaim_mode) | |
2158 | return false; | |
2159 | ||
2160 | /* If there is a count for this node already, it must be acceptable */ | |
2161 | if (khugepaged_node_load[nid]) | |
2162 | return false; | |
2163 | ||
2164 | for (i = 0; i < MAX_NUMNODES; i++) { | |
2165 | if (!khugepaged_node_load[i]) | |
2166 | continue; | |
2167 | if (node_distance(nid, i) > RECLAIM_DISTANCE) | |
2168 | return true; | |
2169 | } | |
2170 | return false; | |
2171 | } | |
2172 | ||
26234f36 | 2173 | #ifdef CONFIG_NUMA |
9f1b868a BL |
2174 | static int khugepaged_find_target_node(void) |
2175 | { | |
2176 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
2177 | int nid, target_node = 0, max_value = 0; | |
2178 | ||
2179 | /* find first node with max normal pages hit */ | |
2180 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
2181 | if (khugepaged_node_load[nid] > max_value) { | |
2182 | max_value = khugepaged_node_load[nid]; | |
2183 | target_node = nid; | |
2184 | } | |
2185 | ||
2186 | /* do some balance if several nodes have the same hit record */ | |
2187 | if (target_node <= last_khugepaged_target_node) | |
2188 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
2189 | nid++) | |
2190 | if (max_value == khugepaged_node_load[nid]) { | |
2191 | target_node = nid; | |
2192 | break; | |
2193 | } | |
2194 | ||
2195 | last_khugepaged_target_node = target_node; | |
2196 | return target_node; | |
2197 | } | |
2198 | ||
26234f36 XG |
2199 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) |
2200 | { | |
2201 | if (IS_ERR(*hpage)) { | |
2202 | if (!*wait) | |
2203 | return false; | |
2204 | ||
2205 | *wait = false; | |
e3b4126c | 2206 | *hpage = NULL; |
26234f36 XG |
2207 | khugepaged_alloc_sleep(); |
2208 | } else if (*hpage) { | |
2209 | put_page(*hpage); | |
2210 | *hpage = NULL; | |
2211 | } | |
2212 | ||
2213 | return true; | |
2214 | } | |
2215 | ||
3b363692 MH |
2216 | static struct page * |
2217 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
d6669d68 | 2218 | unsigned long address, int node) |
26234f36 | 2219 | { |
309381fe | 2220 | VM_BUG_ON_PAGE(*hpage, *hpage); |
8b164568 | 2221 | |
ce83d217 | 2222 | /* |
8b164568 VB |
2223 | * Before allocating the hugepage, release the mmap_sem read lock. |
2224 | * The allocation can take potentially a long time if it involves | |
2225 | * sync compaction, and we do not need to hold the mmap_sem during | |
2226 | * that. We will recheck the vma after taking it again in write mode. | |
ce83d217 | 2227 | */ |
8b164568 VB |
2228 | up_read(&mm->mmap_sem); |
2229 | ||
96db800f | 2230 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); |
26234f36 | 2231 | if (unlikely(!*hpage)) { |
81ab4201 | 2232 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); |
ce83d217 | 2233 | *hpage = ERR_PTR(-ENOMEM); |
26234f36 | 2234 | return NULL; |
ce83d217 | 2235 | } |
26234f36 | 2236 | |
9a982250 | 2237 | prep_transhuge_page(*hpage); |
65b3c07b | 2238 | count_vm_event(THP_COLLAPSE_ALLOC); |
26234f36 XG |
2239 | return *hpage; |
2240 | } | |
2241 | #else | |
9f1b868a BL |
2242 | static int khugepaged_find_target_node(void) |
2243 | { | |
2244 | return 0; | |
2245 | } | |
2246 | ||
10dc4155 BL |
2247 | static inline struct page *alloc_hugepage(int defrag) |
2248 | { | |
9a982250 KS |
2249 | struct page *page; |
2250 | ||
2251 | page = alloc_pages(alloc_hugepage_gfpmask(defrag, 0), HPAGE_PMD_ORDER); | |
2252 | if (page) | |
2253 | prep_transhuge_page(page); | |
2254 | return page; | |
10dc4155 BL |
2255 | } |
2256 | ||
26234f36 XG |
2257 | static struct page *khugepaged_alloc_hugepage(bool *wait) |
2258 | { | |
2259 | struct page *hpage; | |
2260 | ||
2261 | do { | |
2262 | hpage = alloc_hugepage(khugepaged_defrag()); | |
2263 | if (!hpage) { | |
2264 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
2265 | if (!*wait) | |
2266 | return NULL; | |
2267 | ||
2268 | *wait = false; | |
2269 | khugepaged_alloc_sleep(); | |
2270 | } else | |
2271 | count_vm_event(THP_COLLAPSE_ALLOC); | |
2272 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
2273 | ||
2274 | return hpage; | |
2275 | } | |
2276 | ||
2277 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
2278 | { | |
2279 | if (!*hpage) | |
2280 | *hpage = khugepaged_alloc_hugepage(wait); | |
2281 | ||
2282 | if (unlikely(!*hpage)) | |
2283 | return false; | |
2284 | ||
2285 | return true; | |
2286 | } | |
2287 | ||
3b363692 MH |
2288 | static struct page * |
2289 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
d6669d68 | 2290 | unsigned long address, int node) |
26234f36 XG |
2291 | { |
2292 | up_read(&mm->mmap_sem); | |
2293 | VM_BUG_ON(!*hpage); | |
3b363692 | 2294 | |
26234f36 XG |
2295 | return *hpage; |
2296 | } | |
692e0b35 AA |
2297 | #endif |
2298 | ||
fa475e51 BL |
2299 | static bool hugepage_vma_check(struct vm_area_struct *vma) |
2300 | { | |
2301 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || | |
2302 | (vma->vm_flags & VM_NOHUGEPAGE)) | |
2303 | return false; | |
fa475e51 BL |
2304 | if (!vma->anon_vma || vma->vm_ops) |
2305 | return false; | |
2306 | if (is_vma_temporary_stack(vma)) | |
2307 | return false; | |
81d1b09c | 2308 | VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma); |
fa475e51 BL |
2309 | return true; |
2310 | } | |
2311 | ||
26234f36 XG |
2312 | static void collapse_huge_page(struct mm_struct *mm, |
2313 | unsigned long address, | |
2314 | struct page **hpage, | |
2315 | struct vm_area_struct *vma, | |
2316 | int node) | |
2317 | { | |
26234f36 XG |
2318 | pmd_t *pmd, _pmd; |
2319 | pte_t *pte; | |
2320 | pgtable_t pgtable; | |
2321 | struct page *new_page; | |
c4088ebd | 2322 | spinlock_t *pmd_ptl, *pte_ptl; |
629d9d1c | 2323 | int isolated = 0, result = 0; |
26234f36 | 2324 | unsigned long hstart, hend; |
00501b53 | 2325 | struct mem_cgroup *memcg; |
2ec74c3e SG |
2326 | unsigned long mmun_start; /* For mmu_notifiers */ |
2327 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 2328 | gfp_t gfp; |
26234f36 XG |
2329 | |
2330 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2331 | ||
3b363692 MH |
2332 | /* Only allocate from the target node */ |
2333 | gfp = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) | | |
2334 | __GFP_THISNODE; | |
2335 | ||
26234f36 | 2336 | /* release the mmap_sem read lock. */ |
d6669d68 | 2337 | new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node); |
7d2eba05 EA |
2338 | if (!new_page) { |
2339 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
2340 | goto out_nolock; | |
2341 | } | |
26234f36 | 2342 | |
f627c2f5 | 2343 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { |
7d2eba05 EA |
2344 | result = SCAN_CGROUP_CHARGE_FAIL; |
2345 | goto out_nolock; | |
2346 | } | |
ba76149f AA |
2347 | |
2348 | /* | |
2349 | * Prevent all access to pagetables with the exception of | |
2350 | * gup_fast later hanlded by the ptep_clear_flush and the VM | |
2351 | * handled by the anon_vma lock + PG_lock. | |
2352 | */ | |
2353 | down_write(&mm->mmap_sem); | |
7d2eba05 EA |
2354 | if (unlikely(khugepaged_test_exit(mm))) { |
2355 | result = SCAN_ANY_PROCESS; | |
ba76149f | 2356 | goto out; |
7d2eba05 | 2357 | } |
ba76149f AA |
2358 | |
2359 | vma = find_vma(mm, address); | |
7d2eba05 EA |
2360 | if (!vma) { |
2361 | result = SCAN_VMA_NULL; | |
a8f531eb | 2362 | goto out; |
7d2eba05 | 2363 | } |
ba76149f AA |
2364 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2365 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
7d2eba05 EA |
2366 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) { |
2367 | result = SCAN_ADDRESS_RANGE; | |
ba76149f | 2368 | goto out; |
7d2eba05 EA |
2369 | } |
2370 | if (!hugepage_vma_check(vma)) { | |
2371 | result = SCAN_VMA_CHECK; | |
a7d6e4ec | 2372 | goto out; |
7d2eba05 | 2373 | } |
6219049a | 2374 | pmd = mm_find_pmd(mm, address); |
7d2eba05 EA |
2375 | if (!pmd) { |
2376 | result = SCAN_PMD_NULL; | |
ba76149f | 2377 | goto out; |
7d2eba05 | 2378 | } |
ba76149f | 2379 | |
4fc3f1d6 | 2380 | anon_vma_lock_write(vma->anon_vma); |
ba76149f AA |
2381 | |
2382 | pte = pte_offset_map(pmd, address); | |
c4088ebd | 2383 | pte_ptl = pte_lockptr(mm, pmd); |
ba76149f | 2384 | |
2ec74c3e SG |
2385 | mmun_start = address; |
2386 | mmun_end = address + HPAGE_PMD_SIZE; | |
2387 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
c4088ebd | 2388 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
ba76149f AA |
2389 | /* |
2390 | * After this gup_fast can't run anymore. This also removes | |
2391 | * any huge TLB entry from the CPU so we won't allow | |
2392 | * huge and small TLB entries for the same virtual address | |
2393 | * to avoid the risk of CPU bugs in that area. | |
2394 | */ | |
15a25b2e | 2395 | _pmd = pmdp_collapse_flush(vma, address, pmd); |
c4088ebd | 2396 | spin_unlock(pmd_ptl); |
2ec74c3e | 2397 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
ba76149f | 2398 | |
c4088ebd | 2399 | spin_lock(pte_ptl); |
ba76149f | 2400 | isolated = __collapse_huge_page_isolate(vma, address, pte); |
c4088ebd | 2401 | spin_unlock(pte_ptl); |
ba76149f AA |
2402 | |
2403 | if (unlikely(!isolated)) { | |
453c7192 | 2404 | pte_unmap(pte); |
c4088ebd | 2405 | spin_lock(pmd_ptl); |
ba76149f | 2406 | BUG_ON(!pmd_none(*pmd)); |
7c342512 AK |
2407 | /* |
2408 | * We can only use set_pmd_at when establishing | |
2409 | * hugepmds and never for establishing regular pmds that | |
2410 | * points to regular pagetables. Use pmd_populate for that | |
2411 | */ | |
2412 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
c4088ebd | 2413 | spin_unlock(pmd_ptl); |
08b52706 | 2414 | anon_vma_unlock_write(vma->anon_vma); |
7d2eba05 | 2415 | result = SCAN_FAIL; |
ce83d217 | 2416 | goto out; |
ba76149f AA |
2417 | } |
2418 | ||
2419 | /* | |
2420 | * All pages are isolated and locked so anon_vma rmap | |
2421 | * can't run anymore. | |
2422 | */ | |
08b52706 | 2423 | anon_vma_unlock_write(vma->anon_vma); |
ba76149f | 2424 | |
c4088ebd | 2425 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); |
453c7192 | 2426 | pte_unmap(pte); |
ba76149f AA |
2427 | __SetPageUptodate(new_page); |
2428 | pgtable = pmd_pgtable(_pmd); | |
ba76149f | 2429 | |
3122359a KS |
2430 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); |
2431 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); | |
ba76149f AA |
2432 | |
2433 | /* | |
2434 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
2435 | * this is needed to avoid the copy_huge_page writes to become | |
2436 | * visible after the set_pmd_at() write. | |
2437 | */ | |
2438 | smp_wmb(); | |
2439 | ||
c4088ebd | 2440 | spin_lock(pmd_ptl); |
ba76149f | 2441 | BUG_ON(!pmd_none(*pmd)); |
d281ee61 | 2442 | page_add_new_anon_rmap(new_page, vma, address, true); |
f627c2f5 | 2443 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
00501b53 | 2444 | lru_cache_add_active_or_unevictable(new_page, vma); |
fce144b4 | 2445 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
ba76149f | 2446 | set_pmd_at(mm, address, pmd, _pmd); |
b113da65 | 2447 | update_mmu_cache_pmd(vma, address, pmd); |
c4088ebd | 2448 | spin_unlock(pmd_ptl); |
ba76149f AA |
2449 | |
2450 | *hpage = NULL; | |
420256ef | 2451 | |
ba76149f | 2452 | khugepaged_pages_collapsed++; |
7d2eba05 | 2453 | result = SCAN_SUCCEED; |
ce83d217 | 2454 | out_up_write: |
ba76149f | 2455 | up_write(&mm->mmap_sem); |
7d2eba05 | 2456 | trace_mm_collapse_huge_page(mm, isolated, result); |
0bbbc0b3 AA |
2457 | return; |
2458 | ||
7d2eba05 EA |
2459 | out_nolock: |
2460 | trace_mm_collapse_huge_page(mm, isolated, result); | |
2461 | return; | |
ce83d217 | 2462 | out: |
f627c2f5 | 2463 | mem_cgroup_cancel_charge(new_page, memcg, true); |
ce83d217 | 2464 | goto out_up_write; |
ba76149f AA |
2465 | } |
2466 | ||
2467 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
2468 | struct vm_area_struct *vma, | |
2469 | unsigned long address, | |
2470 | struct page **hpage) | |
2471 | { | |
ba76149f AA |
2472 | pmd_t *pmd; |
2473 | pte_t *pte, *_pte; | |
7d2eba05 EA |
2474 | int ret = 0, none_or_zero = 0, result = 0; |
2475 | struct page *page = NULL; | |
ba76149f AA |
2476 | unsigned long _address; |
2477 | spinlock_t *ptl; | |
00ef2d2f | 2478 | int node = NUMA_NO_NODE; |
10359213 | 2479 | bool writable = false, referenced = false; |
ba76149f AA |
2480 | |
2481 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2482 | ||
6219049a | 2483 | pmd = mm_find_pmd(mm, address); |
7d2eba05 EA |
2484 | if (!pmd) { |
2485 | result = SCAN_PMD_NULL; | |
ba76149f | 2486 | goto out; |
7d2eba05 | 2487 | } |
ba76149f | 2488 | |
9f1b868a | 2489 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); |
ba76149f AA |
2490 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
2491 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
2492 | _pte++, _address += PAGE_SIZE) { | |
2493 | pte_t pteval = *_pte; | |
ca0984ca | 2494 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { |
c1294d05 | 2495 | if (!userfaultfd_armed(vma) && |
7d2eba05 | 2496 | ++none_or_zero <= khugepaged_max_ptes_none) { |
ba76149f | 2497 | continue; |
7d2eba05 EA |
2498 | } else { |
2499 | result = SCAN_EXCEED_NONE_PTE; | |
ba76149f | 2500 | goto out_unmap; |
7d2eba05 | 2501 | } |
ba76149f | 2502 | } |
7d2eba05 EA |
2503 | if (!pte_present(pteval)) { |
2504 | result = SCAN_PTE_NON_PRESENT; | |
ba76149f | 2505 | goto out_unmap; |
7d2eba05 | 2506 | } |
10359213 EA |
2507 | if (pte_write(pteval)) |
2508 | writable = true; | |
2509 | ||
ba76149f | 2510 | page = vm_normal_page(vma, _address, pteval); |
7d2eba05 EA |
2511 | if (unlikely(!page)) { |
2512 | result = SCAN_PAGE_NULL; | |
ba76149f | 2513 | goto out_unmap; |
7d2eba05 | 2514 | } |
b1caa957 KS |
2515 | |
2516 | /* TODO: teach khugepaged to collapse THP mapped with pte */ | |
2517 | if (PageCompound(page)) { | |
2518 | result = SCAN_PAGE_COMPOUND; | |
2519 | goto out_unmap; | |
2520 | } | |
2521 | ||
5c4b4be3 | 2522 | /* |
9f1b868a BL |
2523 | * Record which node the original page is from and save this |
2524 | * information to khugepaged_node_load[]. | |
2525 | * Khupaged will allocate hugepage from the node has the max | |
2526 | * hit record. | |
5c4b4be3 | 2527 | */ |
9f1b868a | 2528 | node = page_to_nid(page); |
7d2eba05 EA |
2529 | if (khugepaged_scan_abort(node)) { |
2530 | result = SCAN_SCAN_ABORT; | |
14a4e214 | 2531 | goto out_unmap; |
7d2eba05 | 2532 | } |
9f1b868a | 2533 | khugepaged_node_load[node]++; |
7d2eba05 EA |
2534 | if (!PageLRU(page)) { |
2535 | result = SCAN_SCAN_ABORT; | |
2536 | goto out_unmap; | |
2537 | } | |
2538 | if (PageLocked(page)) { | |
2539 | result = SCAN_PAGE_LOCK; | |
ba76149f | 2540 | goto out_unmap; |
7d2eba05 EA |
2541 | } |
2542 | if (!PageAnon(page)) { | |
2543 | result = SCAN_PAGE_ANON; | |
2544 | goto out_unmap; | |
2545 | } | |
2546 | ||
10359213 EA |
2547 | /* |
2548 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2549 | * The page must only be referenced by the scanned process | |
2550 | * and page swap cache. | |
2551 | */ | |
7d2eba05 EA |
2552 | if (page_count(page) != 1 + !!PageSwapCache(page)) { |
2553 | result = SCAN_PAGE_COUNT; | |
ba76149f | 2554 | goto out_unmap; |
7d2eba05 | 2555 | } |
33c3fc71 VD |
2556 | if (pte_young(pteval) || |
2557 | page_is_young(page) || PageReferenced(page) || | |
8ee53820 | 2558 | mmu_notifier_test_young(vma->vm_mm, address)) |
10359213 | 2559 | referenced = true; |
ba76149f | 2560 | } |
7d2eba05 EA |
2561 | if (writable) { |
2562 | if (referenced) { | |
2563 | result = SCAN_SUCCEED; | |
2564 | ret = 1; | |
2565 | } else { | |
2566 | result = SCAN_NO_REFERENCED_PAGE; | |
2567 | } | |
2568 | } else { | |
2569 | result = SCAN_PAGE_RO; | |
2570 | } | |
ba76149f AA |
2571 | out_unmap: |
2572 | pte_unmap_unlock(pte, ptl); | |
9f1b868a BL |
2573 | if (ret) { |
2574 | node = khugepaged_find_target_node(); | |
ce83d217 | 2575 | /* collapse_huge_page will return with the mmap_sem released */ |
5c4b4be3 | 2576 | collapse_huge_page(mm, address, hpage, vma, node); |
9f1b868a | 2577 | } |
ba76149f | 2578 | out: |
7d2eba05 EA |
2579 | trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced, |
2580 | none_or_zero, result); | |
ba76149f AA |
2581 | return ret; |
2582 | } | |
2583 | ||
2584 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
2585 | { | |
2586 | struct mm_struct *mm = mm_slot->mm; | |
2587 | ||
b9980cdc | 2588 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2589 | |
2590 | if (khugepaged_test_exit(mm)) { | |
2591 | /* free mm_slot */ | |
43b5fbbd | 2592 | hash_del(&mm_slot->hash); |
ba76149f AA |
2593 | list_del(&mm_slot->mm_node); |
2594 | ||
2595 | /* | |
2596 | * Not strictly needed because the mm exited already. | |
2597 | * | |
2598 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
2599 | */ | |
2600 | ||
2601 | /* khugepaged_mm_lock actually not necessary for the below */ | |
2602 | free_mm_slot(mm_slot); | |
2603 | mmdrop(mm); | |
2604 | } | |
2605 | } | |
2606 | ||
2607 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
2608 | struct page **hpage) | |
2f1da642 HS |
2609 | __releases(&khugepaged_mm_lock) |
2610 | __acquires(&khugepaged_mm_lock) | |
ba76149f AA |
2611 | { |
2612 | struct mm_slot *mm_slot; | |
2613 | struct mm_struct *mm; | |
2614 | struct vm_area_struct *vma; | |
2615 | int progress = 0; | |
2616 | ||
2617 | VM_BUG_ON(!pages); | |
b9980cdc | 2618 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2619 | |
2620 | if (khugepaged_scan.mm_slot) | |
2621 | mm_slot = khugepaged_scan.mm_slot; | |
2622 | else { | |
2623 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2624 | struct mm_slot, mm_node); | |
2625 | khugepaged_scan.address = 0; | |
2626 | khugepaged_scan.mm_slot = mm_slot; | |
2627 | } | |
2628 | spin_unlock(&khugepaged_mm_lock); | |
2629 | ||
2630 | mm = mm_slot->mm; | |
2631 | down_read(&mm->mmap_sem); | |
2632 | if (unlikely(khugepaged_test_exit(mm))) | |
2633 | vma = NULL; | |
2634 | else | |
2635 | vma = find_vma(mm, khugepaged_scan.address); | |
2636 | ||
2637 | progress++; | |
2638 | for (; vma; vma = vma->vm_next) { | |
2639 | unsigned long hstart, hend; | |
2640 | ||
2641 | cond_resched(); | |
2642 | if (unlikely(khugepaged_test_exit(mm))) { | |
2643 | progress++; | |
2644 | break; | |
2645 | } | |
fa475e51 BL |
2646 | if (!hugepage_vma_check(vma)) { |
2647 | skip: | |
ba76149f AA |
2648 | progress++; |
2649 | continue; | |
2650 | } | |
ba76149f AA |
2651 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2652 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
a7d6e4ec AA |
2653 | if (hstart >= hend) |
2654 | goto skip; | |
2655 | if (khugepaged_scan.address > hend) | |
2656 | goto skip; | |
ba76149f AA |
2657 | if (khugepaged_scan.address < hstart) |
2658 | khugepaged_scan.address = hstart; | |
a7d6e4ec | 2659 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); |
ba76149f AA |
2660 | |
2661 | while (khugepaged_scan.address < hend) { | |
2662 | int ret; | |
2663 | cond_resched(); | |
2664 | if (unlikely(khugepaged_test_exit(mm))) | |
2665 | goto breakouterloop; | |
2666 | ||
2667 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2668 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2669 | hend); | |
2670 | ret = khugepaged_scan_pmd(mm, vma, | |
2671 | khugepaged_scan.address, | |
2672 | hpage); | |
2673 | /* move to next address */ | |
2674 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2675 | progress += HPAGE_PMD_NR; | |
2676 | if (ret) | |
2677 | /* we released mmap_sem so break loop */ | |
2678 | goto breakouterloop_mmap_sem; | |
2679 | if (progress >= pages) | |
2680 | goto breakouterloop; | |
2681 | } | |
2682 | } | |
2683 | breakouterloop: | |
2684 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2685 | breakouterloop_mmap_sem: | |
2686 | ||
2687 | spin_lock(&khugepaged_mm_lock); | |
a7d6e4ec | 2688 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); |
ba76149f AA |
2689 | /* |
2690 | * Release the current mm_slot if this mm is about to die, or | |
2691 | * if we scanned all vmas of this mm. | |
2692 | */ | |
2693 | if (khugepaged_test_exit(mm) || !vma) { | |
2694 | /* | |
2695 | * Make sure that if mm_users is reaching zero while | |
2696 | * khugepaged runs here, khugepaged_exit will find | |
2697 | * mm_slot not pointing to the exiting mm. | |
2698 | */ | |
2699 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2700 | khugepaged_scan.mm_slot = list_entry( | |
2701 | mm_slot->mm_node.next, | |
2702 | struct mm_slot, mm_node); | |
2703 | khugepaged_scan.address = 0; | |
2704 | } else { | |
2705 | khugepaged_scan.mm_slot = NULL; | |
2706 | khugepaged_full_scans++; | |
2707 | } | |
2708 | ||
2709 | collect_mm_slot(mm_slot); | |
2710 | } | |
2711 | ||
2712 | return progress; | |
2713 | } | |
2714 | ||
2715 | static int khugepaged_has_work(void) | |
2716 | { | |
2717 | return !list_empty(&khugepaged_scan.mm_head) && | |
2718 | khugepaged_enabled(); | |
2719 | } | |
2720 | ||
2721 | static int khugepaged_wait_event(void) | |
2722 | { | |
2723 | return !list_empty(&khugepaged_scan.mm_head) || | |
2017c0bf | 2724 | kthread_should_stop(); |
ba76149f AA |
2725 | } |
2726 | ||
d516904b | 2727 | static void khugepaged_do_scan(void) |
ba76149f | 2728 | { |
d516904b | 2729 | struct page *hpage = NULL; |
ba76149f AA |
2730 | unsigned int progress = 0, pass_through_head = 0; |
2731 | unsigned int pages = khugepaged_pages_to_scan; | |
d516904b | 2732 | bool wait = true; |
ba76149f AA |
2733 | |
2734 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2735 | ||
2736 | while (progress < pages) { | |
26234f36 | 2737 | if (!khugepaged_prealloc_page(&hpage, &wait)) |
d516904b | 2738 | break; |
26234f36 | 2739 | |
420256ef | 2740 | cond_resched(); |
ba76149f | 2741 | |
cd092411 | 2742 | if (unlikely(kthread_should_stop() || try_to_freeze())) |
878aee7d AA |
2743 | break; |
2744 | ||
ba76149f AA |
2745 | spin_lock(&khugepaged_mm_lock); |
2746 | if (!khugepaged_scan.mm_slot) | |
2747 | pass_through_head++; | |
2748 | if (khugepaged_has_work() && | |
2749 | pass_through_head < 2) | |
2750 | progress += khugepaged_scan_mm_slot(pages - progress, | |
d516904b | 2751 | &hpage); |
ba76149f AA |
2752 | else |
2753 | progress = pages; | |
2754 | spin_unlock(&khugepaged_mm_lock); | |
2755 | } | |
ba76149f | 2756 | |
d516904b XG |
2757 | if (!IS_ERR_OR_NULL(hpage)) |
2758 | put_page(hpage); | |
0bbbc0b3 AA |
2759 | } |
2760 | ||
2017c0bf XG |
2761 | static void khugepaged_wait_work(void) |
2762 | { | |
2017c0bf XG |
2763 | if (khugepaged_has_work()) { |
2764 | if (!khugepaged_scan_sleep_millisecs) | |
2765 | return; | |
2766 | ||
2767 | wait_event_freezable_timeout(khugepaged_wait, | |
2768 | kthread_should_stop(), | |
2769 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs)); | |
2770 | return; | |
2771 | } | |
2772 | ||
2773 | if (khugepaged_enabled()) | |
2774 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2775 | } | |
2776 | ||
ba76149f AA |
2777 | static int khugepaged(void *none) |
2778 | { | |
2779 | struct mm_slot *mm_slot; | |
2780 | ||
878aee7d | 2781 | set_freezable(); |
8698a745 | 2782 | set_user_nice(current, MAX_NICE); |
ba76149f | 2783 | |
b7231789 XG |
2784 | while (!kthread_should_stop()) { |
2785 | khugepaged_do_scan(); | |
2786 | khugepaged_wait_work(); | |
2787 | } | |
ba76149f AA |
2788 | |
2789 | spin_lock(&khugepaged_mm_lock); | |
2790 | mm_slot = khugepaged_scan.mm_slot; | |
2791 | khugepaged_scan.mm_slot = NULL; | |
2792 | if (mm_slot) | |
2793 | collect_mm_slot(mm_slot); | |
2794 | spin_unlock(&khugepaged_mm_lock); | |
ba76149f AA |
2795 | return 0; |
2796 | } | |
2797 | ||
eef1b3ba KS |
2798 | static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, |
2799 | unsigned long haddr, pmd_t *pmd) | |
2800 | { | |
2801 | struct mm_struct *mm = vma->vm_mm; | |
2802 | pgtable_t pgtable; | |
2803 | pmd_t _pmd; | |
2804 | int i; | |
2805 | ||
2806 | /* leave pmd empty until pte is filled */ | |
2807 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
2808 | ||
2809 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); | |
2810 | pmd_populate(mm, &_pmd, pgtable); | |
2811 | ||
2812 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
2813 | pte_t *pte, entry; | |
2814 | entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); | |
2815 | entry = pte_mkspecial(entry); | |
2816 | pte = pte_offset_map(&_pmd, haddr); | |
2817 | VM_BUG_ON(!pte_none(*pte)); | |
2818 | set_pte_at(mm, haddr, pte, entry); | |
2819 | pte_unmap(pte); | |
2820 | } | |
2821 | smp_wmb(); /* make pte visible before pmd */ | |
2822 | pmd_populate(mm, pmd, pgtable); | |
2823 | put_huge_zero_page(); | |
2824 | } | |
2825 | ||
2826 | static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, | |
ba988280 | 2827 | unsigned long haddr, bool freeze) |
eef1b3ba KS |
2828 | { |
2829 | struct mm_struct *mm = vma->vm_mm; | |
2830 | struct page *page; | |
2831 | pgtable_t pgtable; | |
2832 | pmd_t _pmd; | |
b8d3c4c3 | 2833 | bool young, write, dirty; |
eef1b3ba KS |
2834 | int i; |
2835 | ||
2836 | VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); | |
2837 | VM_BUG_ON_VMA(vma->vm_start > haddr, vma); | |
2838 | VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); | |
5c7fb56e | 2839 | VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)); |
eef1b3ba KS |
2840 | |
2841 | count_vm_event(THP_SPLIT_PMD); | |
2842 | ||
2843 | if (vma_is_dax(vma)) { | |
2844 | pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
2845 | if (is_huge_zero_pmd(_pmd)) | |
2846 | put_huge_zero_page(); | |
2847 | return; | |
2848 | } else if (is_huge_zero_pmd(*pmd)) { | |
2849 | return __split_huge_zero_page_pmd(vma, haddr, pmd); | |
2850 | } | |
2851 | ||
2852 | page = pmd_page(*pmd); | |
2853 | VM_BUG_ON_PAGE(!page_count(page), page); | |
2854 | atomic_add(HPAGE_PMD_NR - 1, &page->_count); | |
2855 | write = pmd_write(*pmd); | |
2856 | young = pmd_young(*pmd); | |
b8d3c4c3 | 2857 | dirty = pmd_dirty(*pmd); |
eef1b3ba | 2858 | |
eef1b3ba KS |
2859 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
2860 | pmd_populate(mm, &_pmd, pgtable); | |
2861 | ||
2862 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
2863 | pte_t entry, *pte; | |
2864 | /* | |
2865 | * Note that NUMA hinting access restrictions are not | |
2866 | * transferred to avoid any possibility of altering | |
2867 | * permissions across VMAs. | |
2868 | */ | |
ba988280 KS |
2869 | if (freeze) { |
2870 | swp_entry_t swp_entry; | |
2871 | swp_entry = make_migration_entry(page + i, write); | |
2872 | entry = swp_entry_to_pte(swp_entry); | |
2873 | } else { | |
2874 | entry = mk_pte(page + i, vma->vm_page_prot); | |
b8d3c4c3 | 2875 | entry = maybe_mkwrite(entry, vma); |
ba988280 KS |
2876 | if (!write) |
2877 | entry = pte_wrprotect(entry); | |
2878 | if (!young) | |
2879 | entry = pte_mkold(entry); | |
2880 | } | |
b8d3c4c3 MK |
2881 | if (dirty) |
2882 | SetPageDirty(page + i); | |
eef1b3ba KS |
2883 | pte = pte_offset_map(&_pmd, haddr); |
2884 | BUG_ON(!pte_none(*pte)); | |
2885 | set_pte_at(mm, haddr, pte, entry); | |
2886 | atomic_inc(&page[i]._mapcount); | |
2887 | pte_unmap(pte); | |
2888 | } | |
2889 | ||
2890 | /* | |
2891 | * Set PG_double_map before dropping compound_mapcount to avoid | |
2892 | * false-negative page_mapped(). | |
2893 | */ | |
2894 | if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { | |
2895 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
2896 | atomic_inc(&page[i]._mapcount); | |
2897 | } | |
2898 | ||
2899 | if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { | |
2900 | /* Last compound_mapcount is gone. */ | |
2901 | __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); | |
2902 | if (TestClearPageDoubleMap(page)) { | |
2903 | /* No need in mapcount reference anymore */ | |
2904 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
2905 | atomic_dec(&page[i]._mapcount); | |
2906 | } | |
2907 | } | |
2908 | ||
2909 | smp_wmb(); /* make pte visible before pmd */ | |
e9b61f19 KS |
2910 | /* |
2911 | * Up to this point the pmd is present and huge and userland has the | |
2912 | * whole access to the hugepage during the split (which happens in | |
2913 | * place). If we overwrite the pmd with the not-huge version pointing | |
2914 | * to the pte here (which of course we could if all CPUs were bug | |
2915 | * free), userland could trigger a small page size TLB miss on the | |
2916 | * small sized TLB while the hugepage TLB entry is still established in | |
2917 | * the huge TLB. Some CPU doesn't like that. | |
2918 | * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum | |
2919 | * 383 on page 93. Intel should be safe but is also warns that it's | |
2920 | * only safe if the permission and cache attributes of the two entries | |
2921 | * loaded in the two TLB is identical (which should be the case here). | |
2922 | * But it is generally safer to never allow small and huge TLB entries | |
2923 | * for the same virtual address to be loaded simultaneously. So instead | |
2924 | * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the | |
2925 | * current pmd notpresent (atomically because here the pmd_trans_huge | |
2926 | * and pmd_trans_splitting must remain set at all times on the pmd | |
2927 | * until the split is complete for this pmd), then we flush the SMP TLB | |
2928 | * and finally we write the non-huge version of the pmd entry with | |
2929 | * pmd_populate. | |
2930 | */ | |
2931 | pmdp_invalidate(vma, haddr, pmd); | |
eef1b3ba | 2932 | pmd_populate(mm, pmd, pgtable); |
e9b61f19 KS |
2933 | |
2934 | if (freeze) { | |
2935 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
2936 | page_remove_rmap(page + i, false); | |
2937 | put_page(page + i); | |
2938 | } | |
2939 | } | |
eef1b3ba KS |
2940 | } |
2941 | ||
2942 | void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, | |
2943 | unsigned long address) | |
2944 | { | |
2945 | spinlock_t *ptl; | |
2946 | struct mm_struct *mm = vma->vm_mm; | |
e90309c9 | 2947 | struct page *page = NULL; |
eef1b3ba KS |
2948 | unsigned long haddr = address & HPAGE_PMD_MASK; |
2949 | ||
2950 | mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE); | |
2951 | ptl = pmd_lock(mm, pmd); | |
5c7fb56e DW |
2952 | if (pmd_trans_huge(*pmd)) { |
2953 | page = pmd_page(*pmd); | |
2954 | if (PageMlocked(page)) | |
2955 | get_page(page); | |
2956 | else | |
2957 | page = NULL; | |
2958 | } else if (!pmd_devmap(*pmd)) | |
e90309c9 | 2959 | goto out; |
e90309c9 | 2960 | __split_huge_pmd_locked(vma, pmd, haddr, false); |
e90309c9 | 2961 | out: |
eef1b3ba KS |
2962 | spin_unlock(ptl); |
2963 | mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE); | |
e90309c9 KS |
2964 | if (page) { |
2965 | lock_page(page); | |
2966 | munlock_vma_page(page); | |
2967 | unlock_page(page); | |
2968 | put_page(page); | |
2969 | } | |
eef1b3ba KS |
2970 | } |
2971 | ||
78ddc534 | 2972 | static void split_huge_pmd_address(struct vm_area_struct *vma, |
94fcc585 AA |
2973 | unsigned long address) |
2974 | { | |
f72e7dcd HD |
2975 | pgd_t *pgd; |
2976 | pud_t *pud; | |
94fcc585 AA |
2977 | pmd_t *pmd; |
2978 | ||
2979 | VM_BUG_ON(!(address & ~HPAGE_PMD_MASK)); | |
2980 | ||
78ddc534 | 2981 | pgd = pgd_offset(vma->vm_mm, address); |
f72e7dcd HD |
2982 | if (!pgd_present(*pgd)) |
2983 | return; | |
2984 | ||
2985 | pud = pud_offset(pgd, address); | |
2986 | if (!pud_present(*pud)) | |
2987 | return; | |
2988 | ||
2989 | pmd = pmd_offset(pud, address); | |
5c7fb56e | 2990 | if (!pmd_present(*pmd) || (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd))) |
94fcc585 AA |
2991 | return; |
2992 | /* | |
2993 | * Caller holds the mmap_sem write mode, so a huge pmd cannot | |
2994 | * materialize from under us. | |
2995 | */ | |
ad0bed24 | 2996 | split_huge_pmd(vma, pmd, address); |
94fcc585 AA |
2997 | } |
2998 | ||
e1b9996b | 2999 | void vma_adjust_trans_huge(struct vm_area_struct *vma, |
94fcc585 AA |
3000 | unsigned long start, |
3001 | unsigned long end, | |
3002 | long adjust_next) | |
3003 | { | |
3004 | /* | |
3005 | * If the new start address isn't hpage aligned and it could | |
3006 | * previously contain an hugepage: check if we need to split | |
3007 | * an huge pmd. | |
3008 | */ | |
3009 | if (start & ~HPAGE_PMD_MASK && | |
3010 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
3011 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
78ddc534 | 3012 | split_huge_pmd_address(vma, start); |
94fcc585 AA |
3013 | |
3014 | /* | |
3015 | * If the new end address isn't hpage aligned and it could | |
3016 | * previously contain an hugepage: check if we need to split | |
3017 | * an huge pmd. | |
3018 | */ | |
3019 | if (end & ~HPAGE_PMD_MASK && | |
3020 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
3021 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
78ddc534 | 3022 | split_huge_pmd_address(vma, end); |
94fcc585 AA |
3023 | |
3024 | /* | |
3025 | * If we're also updating the vma->vm_next->vm_start, if the new | |
3026 | * vm_next->vm_start isn't page aligned and it could previously | |
3027 | * contain an hugepage: check if we need to split an huge pmd. | |
3028 | */ | |
3029 | if (adjust_next > 0) { | |
3030 | struct vm_area_struct *next = vma->vm_next; | |
3031 | unsigned long nstart = next->vm_start; | |
3032 | nstart += adjust_next << PAGE_SHIFT; | |
3033 | if (nstart & ~HPAGE_PMD_MASK && | |
3034 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
3035 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
78ddc534 | 3036 | split_huge_pmd_address(next, nstart); |
94fcc585 AA |
3037 | } |
3038 | } | |
e9b61f19 KS |
3039 | |
3040 | static void freeze_page_vma(struct vm_area_struct *vma, struct page *page, | |
3041 | unsigned long address) | |
3042 | { | |
bd56086f | 3043 | unsigned long haddr = address & HPAGE_PMD_MASK; |
e9b61f19 KS |
3044 | spinlock_t *ptl; |
3045 | pgd_t *pgd; | |
3046 | pud_t *pud; | |
3047 | pmd_t *pmd; | |
3048 | pte_t *pte; | |
3049 | int i, nr = HPAGE_PMD_NR; | |
3050 | ||
3051 | /* Skip pages which doesn't belong to the VMA */ | |
3052 | if (address < vma->vm_start) { | |
3053 | int off = (vma->vm_start - address) >> PAGE_SHIFT; | |
3054 | page += off; | |
3055 | nr -= off; | |
3056 | address = vma->vm_start; | |
3057 | } | |
3058 | ||
3059 | pgd = pgd_offset(vma->vm_mm, address); | |
3060 | if (!pgd_present(*pgd)) | |
3061 | return; | |
3062 | pud = pud_offset(pgd, address); | |
3063 | if (!pud_present(*pud)) | |
3064 | return; | |
3065 | pmd = pmd_offset(pud, address); | |
3066 | ptl = pmd_lock(vma->vm_mm, pmd); | |
3067 | if (!pmd_present(*pmd)) { | |
3068 | spin_unlock(ptl); | |
3069 | return; | |
3070 | } | |
3071 | if (pmd_trans_huge(*pmd)) { | |
3072 | if (page == pmd_page(*pmd)) | |
bd56086f | 3073 | __split_huge_pmd_locked(vma, pmd, haddr, true); |
e9b61f19 KS |
3074 | spin_unlock(ptl); |
3075 | return; | |
3076 | } | |
3077 | spin_unlock(ptl); | |
3078 | ||
3079 | pte = pte_offset_map_lock(vma->vm_mm, pmd, address, &ptl); | |
bd56086f | 3080 | for (i = 0; i < nr; i++, address += PAGE_SIZE, page++, pte++) { |
e9b61f19 KS |
3081 | pte_t entry, swp_pte; |
3082 | swp_entry_t swp_entry; | |
3083 | ||
bd56086f KS |
3084 | /* |
3085 | * We've just crossed page table boundary: need to map next one. | |
3086 | * It can happen if THP was mremaped to non PMD-aligned address. | |
3087 | */ | |
3088 | if (unlikely(address == haddr + HPAGE_PMD_SIZE)) { | |
3089 | pte_unmap_unlock(pte - 1, ptl); | |
3090 | pmd = mm_find_pmd(vma->vm_mm, address); | |
3091 | if (!pmd) | |
3092 | return; | |
3093 | pte = pte_offset_map_lock(vma->vm_mm, pmd, | |
3094 | address, &ptl); | |
3095 | } | |
3096 | ||
3097 | if (!pte_present(*pte)) | |
e9b61f19 | 3098 | continue; |
bd56086f | 3099 | if (page_to_pfn(page) != pte_pfn(*pte)) |
e9b61f19 KS |
3100 | continue; |
3101 | flush_cache_page(vma, address, page_to_pfn(page)); | |
bd56086f | 3102 | entry = ptep_clear_flush(vma, address, pte); |
b8d3c4c3 MK |
3103 | if (pte_dirty(entry)) |
3104 | SetPageDirty(page); | |
e9b61f19 KS |
3105 | swp_entry = make_migration_entry(page, pte_write(entry)); |
3106 | swp_pte = swp_entry_to_pte(swp_entry); | |
3107 | if (pte_soft_dirty(entry)) | |
3108 | swp_pte = pte_swp_mksoft_dirty(swp_pte); | |
bd56086f | 3109 | set_pte_at(vma->vm_mm, address, pte, swp_pte); |
e9b61f19 KS |
3110 | page_remove_rmap(page, false); |
3111 | put_page(page); | |
3112 | } | |
bd56086f | 3113 | pte_unmap_unlock(pte - 1, ptl); |
e9b61f19 KS |
3114 | } |
3115 | ||
3116 | static void freeze_page(struct anon_vma *anon_vma, struct page *page) | |
3117 | { | |
3118 | struct anon_vma_chain *avc; | |
3119 | pgoff_t pgoff = page_to_pgoff(page); | |
3120 | ||
3121 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
3122 | ||
3123 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, | |
3124 | pgoff + HPAGE_PMD_NR - 1) { | |
bd56086f | 3125 | unsigned long address = __vma_address(page, avc->vma); |
e9b61f19 | 3126 | |
e9b61f19 | 3127 | mmu_notifier_invalidate_range_start(avc->vma->vm_mm, |
bd56086f KS |
3128 | address, address + HPAGE_PMD_SIZE); |
3129 | freeze_page_vma(avc->vma, page, address); | |
e9b61f19 | 3130 | mmu_notifier_invalidate_range_end(avc->vma->vm_mm, |
bd56086f | 3131 | address, address + HPAGE_PMD_SIZE); |
e9b61f19 KS |
3132 | } |
3133 | } | |
3134 | ||
3135 | static void unfreeze_page_vma(struct vm_area_struct *vma, struct page *page, | |
3136 | unsigned long address) | |
3137 | { | |
3138 | spinlock_t *ptl; | |
3139 | pmd_t *pmd; | |
3140 | pte_t *pte, entry; | |
3141 | swp_entry_t swp_entry; | |
bd56086f | 3142 | unsigned long haddr = address & HPAGE_PMD_MASK; |
e9b61f19 KS |
3143 | int i, nr = HPAGE_PMD_NR; |
3144 | ||
3145 | /* Skip pages which doesn't belong to the VMA */ | |
3146 | if (address < vma->vm_start) { | |
3147 | int off = (vma->vm_start - address) >> PAGE_SHIFT; | |
3148 | page += off; | |
3149 | nr -= off; | |
3150 | address = vma->vm_start; | |
3151 | } | |
3152 | ||
3153 | pmd = mm_find_pmd(vma->vm_mm, address); | |
3154 | if (!pmd) | |
3155 | return; | |
bd56086f | 3156 | |
e9b61f19 | 3157 | pte = pte_offset_map_lock(vma->vm_mm, pmd, address, &ptl); |
bd56086f KS |
3158 | for (i = 0; i < nr; i++, address += PAGE_SIZE, page++, pte++) { |
3159 | /* | |
3160 | * We've just crossed page table boundary: need to map next one. | |
3161 | * It can happen if THP was mremaped to non-PMD aligned address. | |
3162 | */ | |
3163 | if (unlikely(address == haddr + HPAGE_PMD_SIZE)) { | |
3164 | pte_unmap_unlock(pte - 1, ptl); | |
3165 | pmd = mm_find_pmd(vma->vm_mm, address); | |
3166 | if (!pmd) | |
3167 | return; | |
3168 | pte = pte_offset_map_lock(vma->vm_mm, pmd, | |
3169 | address, &ptl); | |
3170 | } | |
3171 | ||
3172 | if (!is_swap_pte(*pte)) | |
e9b61f19 KS |
3173 | continue; |
3174 | ||
bd56086f | 3175 | swp_entry = pte_to_swp_entry(*pte); |
e9b61f19 KS |
3176 | if (!is_migration_entry(swp_entry)) |
3177 | continue; | |
3178 | if (migration_entry_to_page(swp_entry) != page) | |
3179 | continue; | |
3180 | ||
3181 | get_page(page); | |
3182 | page_add_anon_rmap(page, vma, address, false); | |
3183 | ||
3184 | entry = pte_mkold(mk_pte(page, vma->vm_page_prot)); | |
b8d3c4c3 MK |
3185 | if (PageDirty(page)) |
3186 | entry = pte_mkdirty(entry); | |
e9b61f19 KS |
3187 | if (is_write_migration_entry(swp_entry)) |
3188 | entry = maybe_mkwrite(entry, vma); | |
3189 | ||
3190 | flush_dcache_page(page); | |
bd56086f | 3191 | set_pte_at(vma->vm_mm, address, pte, entry); |
e9b61f19 KS |
3192 | |
3193 | /* No need to invalidate - it was non-present before */ | |
bd56086f | 3194 | update_mmu_cache(vma, address, pte); |
e9b61f19 | 3195 | } |
bd56086f | 3196 | pte_unmap_unlock(pte - 1, ptl); |
e9b61f19 KS |
3197 | } |
3198 | ||
3199 | static void unfreeze_page(struct anon_vma *anon_vma, struct page *page) | |
3200 | { | |
3201 | struct anon_vma_chain *avc; | |
3202 | pgoff_t pgoff = page_to_pgoff(page); | |
3203 | ||
3204 | anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, | |
3205 | pgoff, pgoff + HPAGE_PMD_NR - 1) { | |
3206 | unsigned long address = __vma_address(page, avc->vma); | |
3207 | ||
3208 | mmu_notifier_invalidate_range_start(avc->vma->vm_mm, | |
3209 | address, address + HPAGE_PMD_SIZE); | |
3210 | unfreeze_page_vma(avc->vma, page, address); | |
3211 | mmu_notifier_invalidate_range_end(avc->vma->vm_mm, | |
3212 | address, address + HPAGE_PMD_SIZE); | |
3213 | } | |
3214 | } | |
3215 | ||
e9b61f19 KS |
3216 | static int __split_huge_page_tail(struct page *head, int tail, |
3217 | struct lruvec *lruvec, struct list_head *list) | |
3218 | { | |
3219 | int mapcount; | |
3220 | struct page *page_tail = head + tail; | |
3221 | ||
3222 | mapcount = atomic_read(&page_tail->_mapcount) + 1; | |
3223 | VM_BUG_ON_PAGE(atomic_read(&page_tail->_count) != 0, page_tail); | |
3224 | ||
3225 | /* | |
3226 | * tail_page->_count is zero and not changing from under us. But | |
3227 | * get_page_unless_zero() may be running from under us on the | |
3228 | * tail_page. If we used atomic_set() below instead of atomic_add(), we | |
3229 | * would then run atomic_set() concurrently with | |
3230 | * get_page_unless_zero(), and atomic_set() is implemented in C not | |
3231 | * using locked ops. spin_unlock on x86 sometime uses locked ops | |
3232 | * because of PPro errata 66, 92, so unless somebody can guarantee | |
3233 | * atomic_set() here would be safe on all archs (and not only on x86), | |
3234 | * it's safer to use atomic_add(). | |
3235 | */ | |
3236 | atomic_add(mapcount + 1, &page_tail->_count); | |
3237 | ||
3238 | ||
3239 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; | |
3240 | page_tail->flags |= (head->flags & | |
3241 | ((1L << PG_referenced) | | |
3242 | (1L << PG_swapbacked) | | |
3243 | (1L << PG_mlocked) | | |
3244 | (1L << PG_uptodate) | | |
3245 | (1L << PG_active) | | |
3246 | (1L << PG_locked) | | |
b8d3c4c3 MK |
3247 | (1L << PG_unevictable) | |
3248 | (1L << PG_dirty))); | |
e9b61f19 KS |
3249 | |
3250 | /* | |
3251 | * After clearing PageTail the gup refcount can be released. | |
3252 | * Page flags also must be visible before we make the page non-compound. | |
3253 | */ | |
3254 | smp_wmb(); | |
3255 | ||
3256 | clear_compound_head(page_tail); | |
3257 | ||
3258 | if (page_is_young(head)) | |
3259 | set_page_young(page_tail); | |
3260 | if (page_is_idle(head)) | |
3261 | set_page_idle(page_tail); | |
3262 | ||
3263 | /* ->mapping in first tail page is compound_mapcount */ | |
9a982250 | 3264 | VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, |
e9b61f19 KS |
3265 | page_tail); |
3266 | page_tail->mapping = head->mapping; | |
3267 | ||
3268 | page_tail->index = head->index + tail; | |
3269 | page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); | |
3270 | lru_add_page_tail(head, page_tail, lruvec, list); | |
3271 | ||
3272 | return mapcount; | |
3273 | } | |
3274 | ||
3275 | static void __split_huge_page(struct page *page, struct list_head *list) | |
3276 | { | |
3277 | struct page *head = compound_head(page); | |
3278 | struct zone *zone = page_zone(head); | |
3279 | struct lruvec *lruvec; | |
3280 | int i, tail_mapcount; | |
3281 | ||
3282 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
3283 | spin_lock_irq(&zone->lru_lock); | |
3284 | lruvec = mem_cgroup_page_lruvec(head, zone); | |
3285 | ||
3286 | /* complete memcg works before add pages to LRU */ | |
3287 | mem_cgroup_split_huge_fixup(head); | |
3288 | ||
3289 | tail_mapcount = 0; | |
3290 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) | |
3291 | tail_mapcount += __split_huge_page_tail(head, i, lruvec, list); | |
3292 | atomic_sub(tail_mapcount, &head->_count); | |
3293 | ||
3294 | ClearPageCompound(head); | |
3295 | spin_unlock_irq(&zone->lru_lock); | |
3296 | ||
3297 | unfreeze_page(page_anon_vma(head), head); | |
3298 | ||
3299 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
3300 | struct page *subpage = head + i; | |
3301 | if (subpage == page) | |
3302 | continue; | |
3303 | unlock_page(subpage); | |
3304 | ||
3305 | /* | |
3306 | * Subpages may be freed if there wasn't any mapping | |
3307 | * like if add_to_swap() is running on a lru page that | |
3308 | * had its mapping zapped. And freeing these pages | |
3309 | * requires taking the lru_lock so we do the put_page | |
3310 | * of the tail pages after the split is complete. | |
3311 | */ | |
3312 | put_page(subpage); | |
3313 | } | |
3314 | } | |
3315 | ||
b20ce5e0 KS |
3316 | int total_mapcount(struct page *page) |
3317 | { | |
3318 | int i, ret; | |
3319 | ||
3320 | VM_BUG_ON_PAGE(PageTail(page), page); | |
3321 | ||
3322 | if (likely(!PageCompound(page))) | |
3323 | return atomic_read(&page->_mapcount) + 1; | |
3324 | ||
3325 | ret = compound_mapcount(page); | |
3326 | if (PageHuge(page)) | |
3327 | return ret; | |
3328 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
3329 | ret += atomic_read(&page[i]._mapcount) + 1; | |
3330 | if (PageDoubleMap(page)) | |
3331 | ret -= HPAGE_PMD_NR; | |
3332 | return ret; | |
3333 | } | |
3334 | ||
e9b61f19 KS |
3335 | /* |
3336 | * This function splits huge page into normal pages. @page can point to any | |
3337 | * subpage of huge page to split. Split doesn't change the position of @page. | |
3338 | * | |
3339 | * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. | |
3340 | * The huge page must be locked. | |
3341 | * | |
3342 | * If @list is null, tail pages will be added to LRU list, otherwise, to @list. | |
3343 | * | |
3344 | * Both head page and tail pages will inherit mapping, flags, and so on from | |
3345 | * the hugepage. | |
3346 | * | |
3347 | * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if | |
3348 | * they are not mapped. | |
3349 | * | |
3350 | * Returns 0 if the hugepage is split successfully. | |
3351 | * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under | |
3352 | * us. | |
3353 | */ | |
3354 | int split_huge_page_to_list(struct page *page, struct list_head *list) | |
3355 | { | |
3356 | struct page *head = compound_head(page); | |
3357 | struct anon_vma *anon_vma; | |
3358 | int count, mapcount, ret; | |
d9654322 | 3359 | bool mlocked; |
0b9b6fff | 3360 | unsigned long flags; |
e9b61f19 KS |
3361 | |
3362 | VM_BUG_ON_PAGE(is_huge_zero_page(page), page); | |
3363 | VM_BUG_ON_PAGE(!PageAnon(page), page); | |
3364 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
3365 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
3366 | VM_BUG_ON_PAGE(!PageCompound(page), page); | |
3367 | ||
3368 | /* | |
3369 | * The caller does not necessarily hold an mmap_sem that would prevent | |
3370 | * the anon_vma disappearing so we first we take a reference to it | |
3371 | * and then lock the anon_vma for write. This is similar to | |
3372 | * page_lock_anon_vma_read except the write lock is taken to serialise | |
3373 | * against parallel split or collapse operations. | |
3374 | */ | |
3375 | anon_vma = page_get_anon_vma(head); | |
3376 | if (!anon_vma) { | |
3377 | ret = -EBUSY; | |
3378 | goto out; | |
3379 | } | |
3380 | anon_vma_lock_write(anon_vma); | |
3381 | ||
3382 | /* | |
3383 | * Racy check if we can split the page, before freeze_page() will | |
3384 | * split PMDs | |
3385 | */ | |
3386 | if (total_mapcount(head) != page_count(head) - 1) { | |
3387 | ret = -EBUSY; | |
3388 | goto out_unlock; | |
3389 | } | |
3390 | ||
d9654322 | 3391 | mlocked = PageMlocked(page); |
e9b61f19 KS |
3392 | freeze_page(anon_vma, head); |
3393 | VM_BUG_ON_PAGE(compound_mapcount(head), head); | |
3394 | ||
d9654322 KS |
3395 | /* Make sure the page is not on per-CPU pagevec as it takes pin */ |
3396 | if (mlocked) | |
3397 | lru_add_drain(); | |
3398 | ||
9a982250 | 3399 | /* Prevent deferred_split_scan() touching ->_count */ |
0b9b6fff | 3400 | spin_lock_irqsave(&split_queue_lock, flags); |
e9b61f19 KS |
3401 | count = page_count(head); |
3402 | mapcount = total_mapcount(head); | |
bd56086f | 3403 | if (!mapcount && count == 1) { |
9a982250 KS |
3404 | if (!list_empty(page_deferred_list(head))) { |
3405 | split_queue_len--; | |
3406 | list_del(page_deferred_list(head)); | |
3407 | } | |
0b9b6fff | 3408 | spin_unlock_irqrestore(&split_queue_lock, flags); |
e9b61f19 KS |
3409 | __split_huge_page(page, list); |
3410 | ret = 0; | |
bd56086f | 3411 | } else if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { |
0b9b6fff | 3412 | spin_unlock_irqrestore(&split_queue_lock, flags); |
e9b61f19 KS |
3413 | pr_alert("total_mapcount: %u, page_count(): %u\n", |
3414 | mapcount, count); | |
3415 | if (PageTail(page)) | |
3416 | dump_page(head, NULL); | |
bd56086f | 3417 | dump_page(page, "total_mapcount(head) > 0"); |
e9b61f19 KS |
3418 | BUG(); |
3419 | } else { | |
0b9b6fff | 3420 | spin_unlock_irqrestore(&split_queue_lock, flags); |
e9b61f19 KS |
3421 | unfreeze_page(anon_vma, head); |
3422 | ret = -EBUSY; | |
3423 | } | |
3424 | ||
3425 | out_unlock: | |
3426 | anon_vma_unlock_write(anon_vma); | |
3427 | put_anon_vma(anon_vma); | |
3428 | out: | |
3429 | count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); | |
3430 | return ret; | |
3431 | } | |
9a982250 KS |
3432 | |
3433 | void free_transhuge_page(struct page *page) | |
3434 | { | |
3435 | unsigned long flags; | |
3436 | ||
3437 | spin_lock_irqsave(&split_queue_lock, flags); | |
3438 | if (!list_empty(page_deferred_list(page))) { | |
3439 | split_queue_len--; | |
3440 | list_del(page_deferred_list(page)); | |
3441 | } | |
3442 | spin_unlock_irqrestore(&split_queue_lock, flags); | |
3443 | free_compound_page(page); | |
3444 | } | |
3445 | ||
3446 | void deferred_split_huge_page(struct page *page) | |
3447 | { | |
3448 | unsigned long flags; | |
3449 | ||
3450 | VM_BUG_ON_PAGE(!PageTransHuge(page), page); | |
3451 | ||
3452 | spin_lock_irqsave(&split_queue_lock, flags); | |
3453 | if (list_empty(page_deferred_list(page))) { | |
3454 | list_add_tail(page_deferred_list(page), &split_queue); | |
3455 | split_queue_len++; | |
3456 | } | |
3457 | spin_unlock_irqrestore(&split_queue_lock, flags); | |
3458 | } | |
3459 | ||
3460 | static unsigned long deferred_split_count(struct shrinker *shrink, | |
3461 | struct shrink_control *sc) | |
3462 | { | |
3463 | /* | |
3464 | * Split a page from split_queue will free up at least one page, | |
3465 | * at most HPAGE_PMD_NR - 1. We don't track exact number. | |
3466 | * Let's use HPAGE_PMD_NR / 2 as ballpark. | |
3467 | */ | |
3468 | return ACCESS_ONCE(split_queue_len) * HPAGE_PMD_NR / 2; | |
3469 | } | |
3470 | ||
3471 | static unsigned long deferred_split_scan(struct shrinker *shrink, | |
3472 | struct shrink_control *sc) | |
3473 | { | |
3474 | unsigned long flags; | |
3475 | LIST_HEAD(list), *pos, *next; | |
3476 | struct page *page; | |
3477 | int split = 0; | |
3478 | ||
3479 | spin_lock_irqsave(&split_queue_lock, flags); | |
3480 | list_splice_init(&split_queue, &list); | |
3481 | ||
3482 | /* Take pin on all head pages to avoid freeing them under us */ | |
3483 | list_for_each_safe(pos, next, &list) { | |
3484 | page = list_entry((void *)pos, struct page, mapping); | |
3485 | page = compound_head(page); | |
3486 | /* race with put_compound_page() */ | |
3487 | if (!get_page_unless_zero(page)) { | |
3488 | list_del_init(page_deferred_list(page)); | |
3489 | split_queue_len--; | |
3490 | } | |
3491 | } | |
3492 | spin_unlock_irqrestore(&split_queue_lock, flags); | |
3493 | ||
3494 | list_for_each_safe(pos, next, &list) { | |
3495 | page = list_entry((void *)pos, struct page, mapping); | |
3496 | lock_page(page); | |
3497 | /* split_huge_page() removes page from list on success */ | |
3498 | if (!split_huge_page(page)) | |
3499 | split++; | |
3500 | unlock_page(page); | |
3501 | put_page(page); | |
3502 | } | |
3503 | ||
3504 | spin_lock_irqsave(&split_queue_lock, flags); | |
3505 | list_splice_tail(&list, &split_queue); | |
3506 | spin_unlock_irqrestore(&split_queue_lock, flags); | |
3507 | ||
3508 | return split * HPAGE_PMD_NR / 2; | |
3509 | } | |
3510 | ||
3511 | static struct shrinker deferred_split_shrinker = { | |
3512 | .count_objects = deferred_split_count, | |
3513 | .scan_objects = deferred_split_scan, | |
3514 | .seeks = DEFAULT_SEEKS, | |
3515 | }; | |
49071d43 KS |
3516 | |
3517 | #ifdef CONFIG_DEBUG_FS | |
3518 | static int split_huge_pages_set(void *data, u64 val) | |
3519 | { | |
3520 | struct zone *zone; | |
3521 | struct page *page; | |
3522 | unsigned long pfn, max_zone_pfn; | |
3523 | unsigned long total = 0, split = 0; | |
3524 | ||
3525 | if (val != 1) | |
3526 | return -EINVAL; | |
3527 | ||
3528 | for_each_populated_zone(zone) { | |
3529 | max_zone_pfn = zone_end_pfn(zone); | |
3530 | for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { | |
3531 | if (!pfn_valid(pfn)) | |
3532 | continue; | |
3533 | ||
3534 | page = pfn_to_page(pfn); | |
3535 | if (!get_page_unless_zero(page)) | |
3536 | continue; | |
3537 | ||
3538 | if (zone != page_zone(page)) | |
3539 | goto next; | |
3540 | ||
3541 | if (!PageHead(page) || !PageAnon(page) || | |
3542 | PageHuge(page)) | |
3543 | goto next; | |
3544 | ||
3545 | total++; | |
3546 | lock_page(page); | |
3547 | if (!split_huge_page(page)) | |
3548 | split++; | |
3549 | unlock_page(page); | |
3550 | next: | |
3551 | put_page(page); | |
3552 | } | |
3553 | } | |
3554 | ||
3555 | pr_info("%lu of %lu THP split", split, total); | |
3556 | ||
3557 | return 0; | |
3558 | } | |
3559 | DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, | |
3560 | "%llu\n"); | |
3561 | ||
3562 | static int __init split_huge_pages_debugfs(void) | |
3563 | { | |
3564 | void *ret; | |
3565 | ||
3566 | ret = debugfs_create_file("split_huge_pages", 0644, NULL, NULL, | |
3567 | &split_huge_pages_fops); | |
3568 | if (!ret) | |
3569 | pr_warn("Failed to create split_huge_pages in debugfs"); | |
3570 | return 0; | |
3571 | } | |
3572 | late_initcall(split_huge_pages_debugfs); | |
3573 | #endif |