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 | ||
8 | #include <linux/mm.h> | |
9 | #include <linux/sched.h> | |
10 | #include <linux/highmem.h> | |
11 | #include <linux/hugetlb.h> | |
12 | #include <linux/mmu_notifier.h> | |
13 | #include <linux/rmap.h> | |
14 | #include <linux/swap.h> | |
ba76149f AA |
15 | #include <linux/mm_inline.h> |
16 | #include <linux/kthread.h> | |
17 | #include <linux/khugepaged.h> | |
878aee7d | 18 | #include <linux/freezer.h> |
a664b2d8 | 19 | #include <linux/mman.h> |
71e3aac0 AA |
20 | #include <asm/tlb.h> |
21 | #include <asm/pgalloc.h> | |
22 | #include "internal.h" | |
23 | ||
ba76149f AA |
24 | /* |
25 | * By default transparent hugepage support is enabled for all mappings | |
26 | * and khugepaged scans all mappings. Defrag is only invoked by | |
27 | * khugepaged hugepage allocations and by page faults inside | |
28 | * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived | |
29 | * allocations. | |
30 | */ | |
71e3aac0 | 31 | unsigned long transparent_hugepage_flags __read_mostly = |
13ece886 | 32 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS |
ba76149f | 33 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| |
13ece886 AA |
34 | #endif |
35 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE | |
36 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| | |
37 | #endif | |
d39d33c3 | 38 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)| |
ba76149f AA |
39 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); |
40 | ||
41 | /* default scan 8*512 pte (or vmas) every 30 second */ | |
42 | static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8; | |
43 | static unsigned int khugepaged_pages_collapsed; | |
44 | static unsigned int khugepaged_full_scans; | |
45 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
46 | /* during fragmentation poll the hugepage allocator once every minute */ | |
47 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
48 | static struct task_struct *khugepaged_thread __read_mostly; | |
49 | static DEFINE_MUTEX(khugepaged_mutex); | |
50 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
51 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
52 | /* | |
53 | * default collapse hugepages if there is at least one pte mapped like | |
54 | * it would have happened if the vma was large enough during page | |
55 | * fault. | |
56 | */ | |
57 | static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1; | |
58 | ||
59 | static int khugepaged(void *none); | |
60 | static int mm_slots_hash_init(void); | |
61 | static int khugepaged_slab_init(void); | |
62 | static void khugepaged_slab_free(void); | |
63 | ||
64 | #define MM_SLOTS_HASH_HEADS 1024 | |
65 | static struct hlist_head *mm_slots_hash __read_mostly; | |
66 | static struct kmem_cache *mm_slot_cache __read_mostly; | |
67 | ||
68 | /** | |
69 | * struct mm_slot - hash lookup from mm to mm_slot | |
70 | * @hash: hash collision list | |
71 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
72 | * @mm: the mm that this information is valid for | |
73 | */ | |
74 | struct mm_slot { | |
75 | struct hlist_node hash; | |
76 | struct list_head mm_node; | |
77 | struct mm_struct *mm; | |
78 | }; | |
79 | ||
80 | /** | |
81 | * struct khugepaged_scan - cursor for scanning | |
82 | * @mm_head: the head of the mm list to scan | |
83 | * @mm_slot: the current mm_slot we are scanning | |
84 | * @address: the next address inside that to be scanned | |
85 | * | |
86 | * There is only the one khugepaged_scan instance of this cursor structure. | |
87 | */ | |
88 | struct khugepaged_scan { | |
89 | struct list_head mm_head; | |
90 | struct mm_slot *mm_slot; | |
91 | unsigned long address; | |
2f1da642 HS |
92 | }; |
93 | static struct khugepaged_scan khugepaged_scan = { | |
ba76149f AA |
94 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), |
95 | }; | |
96 | ||
f000565a AA |
97 | |
98 | static int set_recommended_min_free_kbytes(void) | |
99 | { | |
100 | struct zone *zone; | |
101 | int nr_zones = 0; | |
102 | unsigned long recommended_min; | |
103 | extern int min_free_kbytes; | |
104 | ||
105 | if (!test_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
106 | &transparent_hugepage_flags) && | |
107 | !test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
108 | &transparent_hugepage_flags)) | |
109 | return 0; | |
110 | ||
111 | for_each_populated_zone(zone) | |
112 | nr_zones++; | |
113 | ||
114 | /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */ | |
115 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
116 | ||
117 | /* | |
118 | * Make sure that on average at least two pageblocks are almost free | |
119 | * of another type, one for a migratetype to fall back to and a | |
120 | * second to avoid subsequent fallbacks of other types There are 3 | |
121 | * MIGRATE_TYPES we care about. | |
122 | */ | |
123 | recommended_min += pageblock_nr_pages * nr_zones * | |
124 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
125 | ||
126 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
127 | recommended_min = min(recommended_min, | |
128 | (unsigned long) nr_free_buffer_pages() / 20); | |
129 | recommended_min <<= (PAGE_SHIFT-10); | |
130 | ||
131 | if (recommended_min > min_free_kbytes) | |
132 | min_free_kbytes = recommended_min; | |
133 | setup_per_zone_wmarks(); | |
134 | return 0; | |
135 | } | |
136 | late_initcall(set_recommended_min_free_kbytes); | |
137 | ||
ba76149f AA |
138 | static int start_khugepaged(void) |
139 | { | |
140 | int err = 0; | |
141 | if (khugepaged_enabled()) { | |
ba76149f AA |
142 | if (!khugepaged_thread) |
143 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
144 | "khugepaged"); | |
145 | if (unlikely(IS_ERR(khugepaged_thread))) { | |
146 | printk(KERN_ERR | |
147 | "khugepaged: kthread_run(khugepaged) failed\n"); | |
148 | err = PTR_ERR(khugepaged_thread); | |
149 | khugepaged_thread = NULL; | |
150 | } | |
911891af XG |
151 | |
152 | if (!list_empty(&khugepaged_scan.mm_head)) | |
ba76149f | 153 | wake_up_interruptible(&khugepaged_wait); |
f000565a AA |
154 | |
155 | set_recommended_min_free_kbytes(); | |
911891af | 156 | } else if (khugepaged_thread) { |
911891af XG |
157 | kthread_stop(khugepaged_thread); |
158 | khugepaged_thread = NULL; | |
159 | } | |
637e3a27 | 160 | |
ba76149f AA |
161 | return err; |
162 | } | |
71e3aac0 AA |
163 | |
164 | #ifdef CONFIG_SYSFS | |
ba76149f | 165 | |
71e3aac0 AA |
166 | static ssize_t double_flag_show(struct kobject *kobj, |
167 | struct kobj_attribute *attr, char *buf, | |
168 | enum transparent_hugepage_flag enabled, | |
169 | enum transparent_hugepage_flag req_madv) | |
170 | { | |
171 | if (test_bit(enabled, &transparent_hugepage_flags)) { | |
172 | VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags)); | |
173 | return sprintf(buf, "[always] madvise never\n"); | |
174 | } else if (test_bit(req_madv, &transparent_hugepage_flags)) | |
175 | return sprintf(buf, "always [madvise] never\n"); | |
176 | else | |
177 | return sprintf(buf, "always madvise [never]\n"); | |
178 | } | |
179 | static ssize_t double_flag_store(struct kobject *kobj, | |
180 | struct kobj_attribute *attr, | |
181 | const char *buf, size_t count, | |
182 | enum transparent_hugepage_flag enabled, | |
183 | enum transparent_hugepage_flag req_madv) | |
184 | { | |
185 | if (!memcmp("always", buf, | |
186 | min(sizeof("always")-1, count))) { | |
187 | set_bit(enabled, &transparent_hugepage_flags); | |
188 | clear_bit(req_madv, &transparent_hugepage_flags); | |
189 | } else if (!memcmp("madvise", buf, | |
190 | min(sizeof("madvise")-1, count))) { | |
191 | clear_bit(enabled, &transparent_hugepage_flags); | |
192 | set_bit(req_madv, &transparent_hugepage_flags); | |
193 | } else if (!memcmp("never", buf, | |
194 | min(sizeof("never")-1, count))) { | |
195 | clear_bit(enabled, &transparent_hugepage_flags); | |
196 | clear_bit(req_madv, &transparent_hugepage_flags); | |
197 | } else | |
198 | return -EINVAL; | |
199 | ||
200 | return count; | |
201 | } | |
202 | ||
203 | static ssize_t enabled_show(struct kobject *kobj, | |
204 | struct kobj_attribute *attr, char *buf) | |
205 | { | |
206 | return double_flag_show(kobj, attr, buf, | |
207 | TRANSPARENT_HUGEPAGE_FLAG, | |
208 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
209 | } | |
210 | static ssize_t enabled_store(struct kobject *kobj, | |
211 | struct kobj_attribute *attr, | |
212 | const char *buf, size_t count) | |
213 | { | |
ba76149f AA |
214 | ssize_t ret; |
215 | ||
216 | ret = double_flag_store(kobj, attr, buf, count, | |
217 | TRANSPARENT_HUGEPAGE_FLAG, | |
218 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
219 | ||
220 | if (ret > 0) { | |
911891af XG |
221 | int err; |
222 | ||
223 | mutex_lock(&khugepaged_mutex); | |
224 | err = start_khugepaged(); | |
225 | mutex_unlock(&khugepaged_mutex); | |
226 | ||
ba76149f AA |
227 | if (err) |
228 | ret = err; | |
229 | } | |
230 | ||
f000565a AA |
231 | if (ret > 0 && |
232 | (test_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
233 | &transparent_hugepage_flags) || | |
234 | test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
235 | &transparent_hugepage_flags))) | |
236 | set_recommended_min_free_kbytes(); | |
237 | ||
ba76149f | 238 | return ret; |
71e3aac0 AA |
239 | } |
240 | static struct kobj_attribute enabled_attr = | |
241 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
242 | ||
243 | static ssize_t single_flag_show(struct kobject *kobj, | |
244 | struct kobj_attribute *attr, char *buf, | |
245 | enum transparent_hugepage_flag flag) | |
246 | { | |
e27e6151 BH |
247 | return sprintf(buf, "%d\n", |
248 | !!test_bit(flag, &transparent_hugepage_flags)); | |
71e3aac0 | 249 | } |
e27e6151 | 250 | |
71e3aac0 AA |
251 | static ssize_t single_flag_store(struct kobject *kobj, |
252 | struct kobj_attribute *attr, | |
253 | const char *buf, size_t count, | |
254 | enum transparent_hugepage_flag flag) | |
255 | { | |
e27e6151 BH |
256 | unsigned long value; |
257 | int ret; | |
258 | ||
259 | ret = kstrtoul(buf, 10, &value); | |
260 | if (ret < 0) | |
261 | return ret; | |
262 | if (value > 1) | |
263 | return -EINVAL; | |
264 | ||
265 | if (value) | |
71e3aac0 | 266 | set_bit(flag, &transparent_hugepage_flags); |
e27e6151 | 267 | else |
71e3aac0 | 268 | clear_bit(flag, &transparent_hugepage_flags); |
71e3aac0 AA |
269 | |
270 | return count; | |
271 | } | |
272 | ||
273 | /* | |
274 | * Currently defrag only disables __GFP_NOWAIT for allocation. A blind | |
275 | * __GFP_REPEAT is too aggressive, it's never worth swapping tons of | |
276 | * memory just to allocate one more hugepage. | |
277 | */ | |
278 | static ssize_t defrag_show(struct kobject *kobj, | |
279 | struct kobj_attribute *attr, char *buf) | |
280 | { | |
281 | return double_flag_show(kobj, attr, buf, | |
282 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
283 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
284 | } | |
285 | static ssize_t defrag_store(struct kobject *kobj, | |
286 | struct kobj_attribute *attr, | |
287 | const char *buf, size_t count) | |
288 | { | |
289 | return double_flag_store(kobj, attr, buf, count, | |
290 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
291 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
292 | } | |
293 | static struct kobj_attribute defrag_attr = | |
294 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
295 | ||
296 | #ifdef CONFIG_DEBUG_VM | |
297 | static ssize_t debug_cow_show(struct kobject *kobj, | |
298 | struct kobj_attribute *attr, char *buf) | |
299 | { | |
300 | return single_flag_show(kobj, attr, buf, | |
301 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
302 | } | |
303 | static ssize_t debug_cow_store(struct kobject *kobj, | |
304 | struct kobj_attribute *attr, | |
305 | const char *buf, size_t count) | |
306 | { | |
307 | return single_flag_store(kobj, attr, buf, count, | |
308 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
309 | } | |
310 | static struct kobj_attribute debug_cow_attr = | |
311 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
312 | #endif /* CONFIG_DEBUG_VM */ | |
313 | ||
314 | static struct attribute *hugepage_attr[] = { | |
315 | &enabled_attr.attr, | |
316 | &defrag_attr.attr, | |
317 | #ifdef CONFIG_DEBUG_VM | |
318 | &debug_cow_attr.attr, | |
319 | #endif | |
320 | NULL, | |
321 | }; | |
322 | ||
323 | static struct attribute_group hugepage_attr_group = { | |
324 | .attrs = hugepage_attr, | |
ba76149f AA |
325 | }; |
326 | ||
327 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, | |
328 | struct kobj_attribute *attr, | |
329 | char *buf) | |
330 | { | |
331 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
332 | } | |
333 | ||
334 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
335 | struct kobj_attribute *attr, | |
336 | const char *buf, size_t count) | |
337 | { | |
338 | unsigned long msecs; | |
339 | int err; | |
340 | ||
341 | err = strict_strtoul(buf, 10, &msecs); | |
342 | if (err || msecs > UINT_MAX) | |
343 | return -EINVAL; | |
344 | ||
345 | khugepaged_scan_sleep_millisecs = msecs; | |
346 | wake_up_interruptible(&khugepaged_wait); | |
347 | ||
348 | return count; | |
349 | } | |
350 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
351 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
352 | scan_sleep_millisecs_store); | |
353 | ||
354 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
355 | struct kobj_attribute *attr, | |
356 | char *buf) | |
357 | { | |
358 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
359 | } | |
360 | ||
361 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
362 | struct kobj_attribute *attr, | |
363 | const char *buf, size_t count) | |
364 | { | |
365 | unsigned long msecs; | |
366 | int err; | |
367 | ||
368 | err = strict_strtoul(buf, 10, &msecs); | |
369 | if (err || msecs > UINT_MAX) | |
370 | return -EINVAL; | |
371 | ||
372 | khugepaged_alloc_sleep_millisecs = msecs; | |
373 | wake_up_interruptible(&khugepaged_wait); | |
374 | ||
375 | return count; | |
376 | } | |
377 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
378 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
379 | alloc_sleep_millisecs_store); | |
380 | ||
381 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
382 | struct kobj_attribute *attr, | |
383 | char *buf) | |
384 | { | |
385 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
386 | } | |
387 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
388 | struct kobj_attribute *attr, | |
389 | const char *buf, size_t count) | |
390 | { | |
391 | int err; | |
392 | unsigned long pages; | |
393 | ||
394 | err = strict_strtoul(buf, 10, &pages); | |
395 | if (err || !pages || pages > UINT_MAX) | |
396 | return -EINVAL; | |
397 | ||
398 | khugepaged_pages_to_scan = pages; | |
399 | ||
400 | return count; | |
401 | } | |
402 | static struct kobj_attribute pages_to_scan_attr = | |
403 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
404 | pages_to_scan_store); | |
405 | ||
406 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
407 | struct kobj_attribute *attr, | |
408 | char *buf) | |
409 | { | |
410 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
411 | } | |
412 | static struct kobj_attribute pages_collapsed_attr = | |
413 | __ATTR_RO(pages_collapsed); | |
414 | ||
415 | static ssize_t full_scans_show(struct kobject *kobj, | |
416 | struct kobj_attribute *attr, | |
417 | char *buf) | |
418 | { | |
419 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
420 | } | |
421 | static struct kobj_attribute full_scans_attr = | |
422 | __ATTR_RO(full_scans); | |
423 | ||
424 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
425 | struct kobj_attribute *attr, char *buf) | |
426 | { | |
427 | return single_flag_show(kobj, attr, buf, | |
428 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
429 | } | |
430 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
431 | struct kobj_attribute *attr, | |
432 | const char *buf, size_t count) | |
433 | { | |
434 | return single_flag_store(kobj, attr, buf, count, | |
435 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
436 | } | |
437 | static struct kobj_attribute khugepaged_defrag_attr = | |
438 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
439 | khugepaged_defrag_store); | |
440 | ||
441 | /* | |
442 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
443 | * any unmapped ptes in turn potentially increasing the memory | |
444 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
445 | * reduce the available free memory in the system as it | |
446 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
447 | * free memory in the system during the khugepaged scan. | |
448 | */ | |
449 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
450 | struct kobj_attribute *attr, | |
451 | char *buf) | |
452 | { | |
453 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
454 | } | |
455 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
456 | struct kobj_attribute *attr, | |
457 | const char *buf, size_t count) | |
458 | { | |
459 | int err; | |
460 | unsigned long max_ptes_none; | |
461 | ||
462 | err = strict_strtoul(buf, 10, &max_ptes_none); | |
463 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
464 | return -EINVAL; | |
465 | ||
466 | khugepaged_max_ptes_none = max_ptes_none; | |
467 | ||
468 | return count; | |
469 | } | |
470 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
471 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
472 | khugepaged_max_ptes_none_store); | |
473 | ||
474 | static struct attribute *khugepaged_attr[] = { | |
475 | &khugepaged_defrag_attr.attr, | |
476 | &khugepaged_max_ptes_none_attr.attr, | |
477 | &pages_to_scan_attr.attr, | |
478 | &pages_collapsed_attr.attr, | |
479 | &full_scans_attr.attr, | |
480 | &scan_sleep_millisecs_attr.attr, | |
481 | &alloc_sleep_millisecs_attr.attr, | |
482 | NULL, | |
483 | }; | |
484 | ||
485 | static struct attribute_group khugepaged_attr_group = { | |
486 | .attrs = khugepaged_attr, | |
487 | .name = "khugepaged", | |
71e3aac0 | 488 | }; |
71e3aac0 | 489 | |
569e5590 | 490 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
71e3aac0 | 491 | { |
71e3aac0 AA |
492 | int err; |
493 | ||
569e5590 SL |
494 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); |
495 | if (unlikely(!*hugepage_kobj)) { | |
ba76149f | 496 | printk(KERN_ERR "hugepage: failed kobject create\n"); |
569e5590 | 497 | return -ENOMEM; |
ba76149f AA |
498 | } |
499 | ||
569e5590 | 500 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); |
ba76149f AA |
501 | if (err) { |
502 | printk(KERN_ERR "hugepage: failed register hugeage group\n"); | |
569e5590 | 503 | goto delete_obj; |
ba76149f AA |
504 | } |
505 | ||
569e5590 | 506 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); |
ba76149f AA |
507 | if (err) { |
508 | printk(KERN_ERR "hugepage: failed register hugeage group\n"); | |
569e5590 | 509 | goto remove_hp_group; |
ba76149f | 510 | } |
569e5590 SL |
511 | |
512 | return 0; | |
513 | ||
514 | remove_hp_group: | |
515 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
516 | delete_obj: | |
517 | kobject_put(*hugepage_kobj); | |
518 | return err; | |
519 | } | |
520 | ||
521 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
522 | { | |
523 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
524 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
525 | kobject_put(hugepage_kobj); | |
526 | } | |
527 | #else | |
528 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
529 | { | |
530 | return 0; | |
531 | } | |
532 | ||
533 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
534 | { | |
535 | } | |
536 | #endif /* CONFIG_SYSFS */ | |
537 | ||
538 | static int __init hugepage_init(void) | |
539 | { | |
540 | int err; | |
541 | struct kobject *hugepage_kobj; | |
542 | ||
543 | if (!has_transparent_hugepage()) { | |
544 | transparent_hugepage_flags = 0; | |
545 | return -EINVAL; | |
546 | } | |
547 | ||
548 | err = hugepage_init_sysfs(&hugepage_kobj); | |
549 | if (err) | |
550 | return err; | |
ba76149f AA |
551 | |
552 | err = khugepaged_slab_init(); | |
553 | if (err) | |
554 | goto out; | |
555 | ||
556 | err = mm_slots_hash_init(); | |
557 | if (err) { | |
558 | khugepaged_slab_free(); | |
559 | goto out; | |
560 | } | |
561 | ||
97562cd2 RR |
562 | /* |
563 | * By default disable transparent hugepages on smaller systems, | |
564 | * where the extra memory used could hurt more than TLB overhead | |
565 | * is likely to save. The admin can still enable it through /sys. | |
566 | */ | |
567 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) | |
568 | transparent_hugepage_flags = 0; | |
569 | ||
ba76149f AA |
570 | start_khugepaged(); |
571 | ||
f000565a AA |
572 | set_recommended_min_free_kbytes(); |
573 | ||
569e5590 | 574 | return 0; |
ba76149f | 575 | out: |
569e5590 | 576 | hugepage_exit_sysfs(hugepage_kobj); |
ba76149f | 577 | return err; |
71e3aac0 AA |
578 | } |
579 | module_init(hugepage_init) | |
580 | ||
581 | static int __init setup_transparent_hugepage(char *str) | |
582 | { | |
583 | int ret = 0; | |
584 | if (!str) | |
585 | goto out; | |
586 | if (!strcmp(str, "always")) { | |
587 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
588 | &transparent_hugepage_flags); | |
589 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
590 | &transparent_hugepage_flags); | |
591 | ret = 1; | |
592 | } else if (!strcmp(str, "madvise")) { | |
593 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
594 | &transparent_hugepage_flags); | |
595 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
596 | &transparent_hugepage_flags); | |
597 | ret = 1; | |
598 | } else if (!strcmp(str, "never")) { | |
599 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
600 | &transparent_hugepage_flags); | |
601 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
602 | &transparent_hugepage_flags); | |
603 | ret = 1; | |
604 | } | |
605 | out: | |
606 | if (!ret) | |
607 | printk(KERN_WARNING | |
608 | "transparent_hugepage= cannot parse, ignored\n"); | |
609 | return ret; | |
610 | } | |
611 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
612 | ||
613 | static void prepare_pmd_huge_pte(pgtable_t pgtable, | |
614 | struct mm_struct *mm) | |
615 | { | |
616 | assert_spin_locked(&mm->page_table_lock); | |
617 | ||
618 | /* FIFO */ | |
619 | if (!mm->pmd_huge_pte) | |
620 | INIT_LIST_HEAD(&pgtable->lru); | |
621 | else | |
622 | list_add(&pgtable->lru, &mm->pmd_huge_pte->lru); | |
623 | mm->pmd_huge_pte = pgtable; | |
624 | } | |
625 | ||
626 | static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) | |
627 | { | |
628 | if (likely(vma->vm_flags & VM_WRITE)) | |
629 | pmd = pmd_mkwrite(pmd); | |
630 | return pmd; | |
631 | } | |
632 | ||
633 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, | |
634 | struct vm_area_struct *vma, | |
635 | unsigned long haddr, pmd_t *pmd, | |
636 | struct page *page) | |
637 | { | |
71e3aac0 AA |
638 | pgtable_t pgtable; |
639 | ||
640 | VM_BUG_ON(!PageCompound(page)); | |
641 | pgtable = pte_alloc_one(mm, haddr); | |
edad9d2c | 642 | if (unlikely(!pgtable)) |
71e3aac0 | 643 | return VM_FAULT_OOM; |
71e3aac0 AA |
644 | |
645 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
646 | __SetPageUptodate(page); | |
647 | ||
648 | spin_lock(&mm->page_table_lock); | |
649 | if (unlikely(!pmd_none(*pmd))) { | |
650 | spin_unlock(&mm->page_table_lock); | |
b9bbfbe3 | 651 | mem_cgroup_uncharge_page(page); |
71e3aac0 AA |
652 | put_page(page); |
653 | pte_free(mm, pgtable); | |
654 | } else { | |
655 | pmd_t entry; | |
656 | entry = mk_pmd(page, vma->vm_page_prot); | |
657 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
658 | entry = pmd_mkhuge(entry); | |
659 | /* | |
660 | * The spinlocking to take the lru_lock inside | |
661 | * page_add_new_anon_rmap() acts as a full memory | |
662 | * barrier to be sure clear_huge_page writes become | |
663 | * visible after the set_pmd_at() write. | |
664 | */ | |
665 | page_add_new_anon_rmap(page, vma, haddr); | |
666 | set_pmd_at(mm, haddr, pmd, entry); | |
667 | prepare_pmd_huge_pte(pgtable, mm); | |
668 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
1c641e84 | 669 | mm->nr_ptes++; |
71e3aac0 AA |
670 | spin_unlock(&mm->page_table_lock); |
671 | } | |
672 | ||
aa2e878e | 673 | return 0; |
71e3aac0 AA |
674 | } |
675 | ||
cc5d462f | 676 | static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp) |
0bbbc0b3 | 677 | { |
cc5d462f | 678 | return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp; |
0bbbc0b3 AA |
679 | } |
680 | ||
681 | static inline struct page *alloc_hugepage_vma(int defrag, | |
682 | struct vm_area_struct *vma, | |
cc5d462f AK |
683 | unsigned long haddr, int nd, |
684 | gfp_t extra_gfp) | |
0bbbc0b3 | 685 | { |
cc5d462f | 686 | return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp), |
5c4b4be3 | 687 | HPAGE_PMD_ORDER, vma, haddr, nd); |
0bbbc0b3 AA |
688 | } |
689 | ||
690 | #ifndef CONFIG_NUMA | |
71e3aac0 AA |
691 | static inline struct page *alloc_hugepage(int defrag) |
692 | { | |
cc5d462f | 693 | return alloc_pages(alloc_hugepage_gfpmask(defrag, 0), |
71e3aac0 AA |
694 | HPAGE_PMD_ORDER); |
695 | } | |
0bbbc0b3 | 696 | #endif |
71e3aac0 AA |
697 | |
698 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
699 | unsigned long address, pmd_t *pmd, | |
700 | unsigned int flags) | |
701 | { | |
702 | struct page *page; | |
703 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
704 | pte_t *pte; | |
705 | ||
706 | if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) { | |
707 | if (unlikely(anon_vma_prepare(vma))) | |
708 | return VM_FAULT_OOM; | |
ba76149f AA |
709 | if (unlikely(khugepaged_enter(vma))) |
710 | return VM_FAULT_OOM; | |
0bbbc0b3 | 711 | page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
cc5d462f | 712 | vma, haddr, numa_node_id(), 0); |
81ab4201 AK |
713 | if (unlikely(!page)) { |
714 | count_vm_event(THP_FAULT_FALLBACK); | |
71e3aac0 | 715 | goto out; |
81ab4201 AK |
716 | } |
717 | count_vm_event(THP_FAULT_ALLOC); | |
b9bbfbe3 AA |
718 | if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) { |
719 | put_page(page); | |
720 | goto out; | |
721 | } | |
edad9d2c DR |
722 | if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, |
723 | page))) { | |
724 | mem_cgroup_uncharge_page(page); | |
725 | put_page(page); | |
726 | goto out; | |
727 | } | |
71e3aac0 | 728 | |
edad9d2c | 729 | return 0; |
71e3aac0 AA |
730 | } |
731 | out: | |
732 | /* | |
733 | * Use __pte_alloc instead of pte_alloc_map, because we can't | |
734 | * run pte_offset_map on the pmd, if an huge pmd could | |
735 | * materialize from under us from a different thread. | |
736 | */ | |
737 | if (unlikely(__pte_alloc(mm, vma, pmd, address))) | |
738 | return VM_FAULT_OOM; | |
739 | /* if an huge pmd materialized from under us just retry later */ | |
740 | if (unlikely(pmd_trans_huge(*pmd))) | |
741 | return 0; | |
742 | /* | |
743 | * A regular pmd is established and it can't morph into a huge pmd | |
744 | * from under us anymore at this point because we hold the mmap_sem | |
745 | * read mode and khugepaged takes it in write mode. So now it's | |
746 | * safe to run pte_offset_map(). | |
747 | */ | |
748 | pte = pte_offset_map(pmd, address); | |
749 | return handle_pte_fault(mm, vma, address, pte, pmd, flags); | |
750 | } | |
751 | ||
752 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, | |
753 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
754 | struct vm_area_struct *vma) | |
755 | { | |
756 | struct page *src_page; | |
757 | pmd_t pmd; | |
758 | pgtable_t pgtable; | |
759 | int ret; | |
760 | ||
761 | ret = -ENOMEM; | |
762 | pgtable = pte_alloc_one(dst_mm, addr); | |
763 | if (unlikely(!pgtable)) | |
764 | goto out; | |
765 | ||
766 | spin_lock(&dst_mm->page_table_lock); | |
767 | spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING); | |
768 | ||
769 | ret = -EAGAIN; | |
770 | pmd = *src_pmd; | |
771 | if (unlikely(!pmd_trans_huge(pmd))) { | |
772 | pte_free(dst_mm, pgtable); | |
773 | goto out_unlock; | |
774 | } | |
775 | if (unlikely(pmd_trans_splitting(pmd))) { | |
776 | /* split huge page running from under us */ | |
777 | spin_unlock(&src_mm->page_table_lock); | |
778 | spin_unlock(&dst_mm->page_table_lock); | |
779 | pte_free(dst_mm, pgtable); | |
780 | ||
781 | wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */ | |
782 | goto out; | |
783 | } | |
784 | src_page = pmd_page(pmd); | |
785 | VM_BUG_ON(!PageHead(src_page)); | |
786 | get_page(src_page); | |
787 | page_dup_rmap(src_page); | |
788 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
789 | ||
790 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
791 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
792 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
793 | prepare_pmd_huge_pte(pgtable, dst_mm); | |
1c641e84 | 794 | dst_mm->nr_ptes++; |
71e3aac0 AA |
795 | |
796 | ret = 0; | |
797 | out_unlock: | |
798 | spin_unlock(&src_mm->page_table_lock); | |
799 | spin_unlock(&dst_mm->page_table_lock); | |
800 | out: | |
801 | return ret; | |
802 | } | |
803 | ||
804 | /* no "address" argument so destroys page coloring of some arch */ | |
805 | pgtable_t get_pmd_huge_pte(struct mm_struct *mm) | |
806 | { | |
807 | pgtable_t pgtable; | |
808 | ||
809 | assert_spin_locked(&mm->page_table_lock); | |
810 | ||
811 | /* FIFO */ | |
812 | pgtable = mm->pmd_huge_pte; | |
813 | if (list_empty(&pgtable->lru)) | |
814 | mm->pmd_huge_pte = NULL; | |
815 | else { | |
816 | mm->pmd_huge_pte = list_entry(pgtable->lru.next, | |
817 | struct page, lru); | |
818 | list_del(&pgtable->lru); | |
819 | } | |
820 | return pgtable; | |
821 | } | |
822 | ||
823 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, | |
824 | struct vm_area_struct *vma, | |
825 | unsigned long address, | |
826 | pmd_t *pmd, pmd_t orig_pmd, | |
827 | struct page *page, | |
828 | unsigned long haddr) | |
829 | { | |
830 | pgtable_t pgtable; | |
831 | pmd_t _pmd; | |
832 | int ret = 0, i; | |
833 | struct page **pages; | |
834 | ||
835 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
836 | GFP_KERNEL); | |
837 | if (unlikely(!pages)) { | |
838 | ret |= VM_FAULT_OOM; | |
839 | goto out; | |
840 | } | |
841 | ||
842 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
cc5d462f AK |
843 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE | |
844 | __GFP_OTHER_NODE, | |
19ee151e | 845 | vma, address, page_to_nid(page)); |
b9bbfbe3 AA |
846 | if (unlikely(!pages[i] || |
847 | mem_cgroup_newpage_charge(pages[i], mm, | |
848 | GFP_KERNEL))) { | |
849 | if (pages[i]) | |
71e3aac0 | 850 | put_page(pages[i]); |
b9bbfbe3 AA |
851 | mem_cgroup_uncharge_start(); |
852 | while (--i >= 0) { | |
853 | mem_cgroup_uncharge_page(pages[i]); | |
854 | put_page(pages[i]); | |
855 | } | |
856 | mem_cgroup_uncharge_end(); | |
71e3aac0 AA |
857 | kfree(pages); |
858 | ret |= VM_FAULT_OOM; | |
859 | goto out; | |
860 | } | |
861 | } | |
862 | ||
863 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
864 | copy_user_highpage(pages[i], page + i, | |
0089e485 | 865 | haddr + PAGE_SIZE * i, vma); |
71e3aac0 AA |
866 | __SetPageUptodate(pages[i]); |
867 | cond_resched(); | |
868 | } | |
869 | ||
870 | spin_lock(&mm->page_table_lock); | |
871 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
872 | goto out_free_pages; | |
873 | VM_BUG_ON(!PageHead(page)); | |
874 | ||
875 | pmdp_clear_flush_notify(vma, haddr, pmd); | |
876 | /* leave pmd empty until pte is filled */ | |
877 | ||
878 | pgtable = get_pmd_huge_pte(mm); | |
879 | pmd_populate(mm, &_pmd, pgtable); | |
880 | ||
881 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
882 | pte_t *pte, entry; | |
883 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
884 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
885 | page_add_new_anon_rmap(pages[i], vma, haddr); | |
886 | pte = pte_offset_map(&_pmd, haddr); | |
887 | VM_BUG_ON(!pte_none(*pte)); | |
888 | set_pte_at(mm, haddr, pte, entry); | |
889 | pte_unmap(pte); | |
890 | } | |
891 | kfree(pages); | |
892 | ||
71e3aac0 AA |
893 | smp_wmb(); /* make pte visible before pmd */ |
894 | pmd_populate(mm, pmd, pgtable); | |
895 | page_remove_rmap(page); | |
896 | spin_unlock(&mm->page_table_lock); | |
897 | ||
898 | ret |= VM_FAULT_WRITE; | |
899 | put_page(page); | |
900 | ||
901 | out: | |
902 | return ret; | |
903 | ||
904 | out_free_pages: | |
905 | spin_unlock(&mm->page_table_lock); | |
b9bbfbe3 AA |
906 | mem_cgroup_uncharge_start(); |
907 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
908 | mem_cgroup_uncharge_page(pages[i]); | |
71e3aac0 | 909 | put_page(pages[i]); |
b9bbfbe3 AA |
910 | } |
911 | mem_cgroup_uncharge_end(); | |
71e3aac0 AA |
912 | kfree(pages); |
913 | goto out; | |
914 | } | |
915 | ||
916 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
917 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) | |
918 | { | |
919 | int ret = 0; | |
920 | struct page *page, *new_page; | |
921 | unsigned long haddr; | |
922 | ||
923 | VM_BUG_ON(!vma->anon_vma); | |
924 | spin_lock(&mm->page_table_lock); | |
925 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
926 | goto out_unlock; | |
927 | ||
928 | page = pmd_page(orig_pmd); | |
929 | VM_BUG_ON(!PageCompound(page) || !PageHead(page)); | |
930 | haddr = address & HPAGE_PMD_MASK; | |
931 | if (page_mapcount(page) == 1) { | |
932 | pmd_t entry; | |
933 | entry = pmd_mkyoung(orig_pmd); | |
934 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
935 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) | |
936 | update_mmu_cache(vma, address, entry); | |
937 | ret |= VM_FAULT_WRITE; | |
938 | goto out_unlock; | |
939 | } | |
940 | get_page(page); | |
941 | spin_unlock(&mm->page_table_lock); | |
942 | ||
943 | if (transparent_hugepage_enabled(vma) && | |
944 | !transparent_hugepage_debug_cow()) | |
0bbbc0b3 | 945 | new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
cc5d462f | 946 | vma, haddr, numa_node_id(), 0); |
71e3aac0 AA |
947 | else |
948 | new_page = NULL; | |
949 | ||
950 | if (unlikely(!new_page)) { | |
81ab4201 | 951 | count_vm_event(THP_FAULT_FALLBACK); |
71e3aac0 AA |
952 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, |
953 | pmd, orig_pmd, page, haddr); | |
1f1d06c3 DR |
954 | if (ret & VM_FAULT_OOM) |
955 | split_huge_page(page); | |
71e3aac0 AA |
956 | put_page(page); |
957 | goto out; | |
958 | } | |
81ab4201 | 959 | count_vm_event(THP_FAULT_ALLOC); |
71e3aac0 | 960 | |
b9bbfbe3 AA |
961 | if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) { |
962 | put_page(new_page); | |
1f1d06c3 | 963 | split_huge_page(page); |
b9bbfbe3 AA |
964 | put_page(page); |
965 | ret |= VM_FAULT_OOM; | |
966 | goto out; | |
967 | } | |
968 | ||
71e3aac0 AA |
969 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); |
970 | __SetPageUptodate(new_page); | |
971 | ||
972 | spin_lock(&mm->page_table_lock); | |
973 | put_page(page); | |
b9bbfbe3 | 974 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { |
6f60b69d | 975 | spin_unlock(&mm->page_table_lock); |
b9bbfbe3 | 976 | mem_cgroup_uncharge_page(new_page); |
71e3aac0 | 977 | put_page(new_page); |
6f60b69d | 978 | goto out; |
b9bbfbe3 | 979 | } else { |
71e3aac0 AA |
980 | pmd_t entry; |
981 | VM_BUG_ON(!PageHead(page)); | |
982 | entry = mk_pmd(new_page, vma->vm_page_prot); | |
983 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
984 | entry = pmd_mkhuge(entry); | |
985 | pmdp_clear_flush_notify(vma, haddr, pmd); | |
986 | page_add_new_anon_rmap(new_page, vma, haddr); | |
987 | set_pmd_at(mm, haddr, pmd, entry); | |
988 | update_mmu_cache(vma, address, entry); | |
989 | page_remove_rmap(page); | |
990 | put_page(page); | |
991 | ret |= VM_FAULT_WRITE; | |
992 | } | |
993 | out_unlock: | |
994 | spin_unlock(&mm->page_table_lock); | |
995 | out: | |
996 | return ret; | |
997 | } | |
998 | ||
999 | struct page *follow_trans_huge_pmd(struct mm_struct *mm, | |
1000 | unsigned long addr, | |
1001 | pmd_t *pmd, | |
1002 | unsigned int flags) | |
1003 | { | |
1004 | struct page *page = NULL; | |
1005 | ||
1006 | assert_spin_locked(&mm->page_table_lock); | |
1007 | ||
1008 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1009 | goto out; | |
1010 | ||
1011 | page = pmd_page(*pmd); | |
1012 | VM_BUG_ON(!PageHead(page)); | |
1013 | if (flags & FOLL_TOUCH) { | |
1014 | pmd_t _pmd; | |
1015 | /* | |
1016 | * We should set the dirty bit only for FOLL_WRITE but | |
1017 | * for now the dirty bit in the pmd is meaningless. | |
1018 | * And if the dirty bit will become meaningful and | |
1019 | * we'll only set it with FOLL_WRITE, an atomic | |
1020 | * set_bit will be required on the pmd to set the | |
1021 | * young bit, instead of the current set_pmd_at. | |
1022 | */ | |
1023 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
1024 | set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd); | |
1025 | } | |
1026 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; | |
1027 | VM_BUG_ON(!PageCompound(page)); | |
1028 | if (flags & FOLL_GET) | |
70b50f94 | 1029 | get_page_foll(page); |
71e3aac0 AA |
1030 | |
1031 | out: | |
1032 | return page; | |
1033 | } | |
1034 | ||
1035 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, | |
f21760b1 | 1036 | pmd_t *pmd, unsigned long addr) |
71e3aac0 AA |
1037 | { |
1038 | int ret = 0; | |
1039 | ||
025c5b24 NH |
1040 | if (__pmd_trans_huge_lock(pmd, vma) == 1) { |
1041 | struct page *page; | |
1042 | pgtable_t pgtable; | |
1043 | pgtable = get_pmd_huge_pte(tlb->mm); | |
1044 | page = pmd_page(*pmd); | |
1045 | pmd_clear(pmd); | |
1046 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1047 | page_remove_rmap(page); | |
1048 | VM_BUG_ON(page_mapcount(page) < 0); | |
1049 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1050 | VM_BUG_ON(!PageHead(page)); | |
1051 | tlb->mm->nr_ptes--; | |
71e3aac0 | 1052 | spin_unlock(&tlb->mm->page_table_lock); |
025c5b24 NH |
1053 | tlb_remove_page(tlb, page); |
1054 | pte_free(tlb->mm, pgtable); | |
1055 | ret = 1; | |
1056 | } | |
71e3aac0 AA |
1057 | return ret; |
1058 | } | |
1059 | ||
0ca1634d JW |
1060 | int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
1061 | unsigned long addr, unsigned long end, | |
1062 | unsigned char *vec) | |
1063 | { | |
1064 | int ret = 0; | |
1065 | ||
025c5b24 NH |
1066 | if (__pmd_trans_huge_lock(pmd, vma) == 1) { |
1067 | /* | |
1068 | * All logical pages in the range are present | |
1069 | * if backed by a huge page. | |
1070 | */ | |
0ca1634d | 1071 | spin_unlock(&vma->vm_mm->page_table_lock); |
025c5b24 NH |
1072 | memset(vec, 1, (end - addr) >> PAGE_SHIFT); |
1073 | ret = 1; | |
1074 | } | |
0ca1634d JW |
1075 | |
1076 | return ret; | |
1077 | } | |
1078 | ||
37a1c49a AA |
1079 | int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, |
1080 | unsigned long old_addr, | |
1081 | unsigned long new_addr, unsigned long old_end, | |
1082 | pmd_t *old_pmd, pmd_t *new_pmd) | |
1083 | { | |
1084 | int ret = 0; | |
1085 | pmd_t pmd; | |
1086 | ||
1087 | struct mm_struct *mm = vma->vm_mm; | |
1088 | ||
1089 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1090 | (new_addr & ~HPAGE_PMD_MASK) || | |
1091 | old_end - old_addr < HPAGE_PMD_SIZE || | |
1092 | (new_vma->vm_flags & VM_NOHUGEPAGE)) | |
1093 | goto out; | |
1094 | ||
1095 | /* | |
1096 | * The destination pmd shouldn't be established, free_pgtables() | |
1097 | * should have release it. | |
1098 | */ | |
1099 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1100 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
1101 | goto out; | |
1102 | } | |
1103 | ||
025c5b24 NH |
1104 | ret = __pmd_trans_huge_lock(old_pmd, vma); |
1105 | if (ret == 1) { | |
1106 | pmd = pmdp_get_and_clear(mm, old_addr, old_pmd); | |
1107 | VM_BUG_ON(!pmd_none(*new_pmd)); | |
1108 | set_pmd_at(mm, new_addr, new_pmd, pmd); | |
37a1c49a AA |
1109 | spin_unlock(&mm->page_table_lock); |
1110 | } | |
1111 | out: | |
1112 | return ret; | |
1113 | } | |
1114 | ||
cd7548ab JW |
1115 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
1116 | unsigned long addr, pgprot_t newprot) | |
1117 | { | |
1118 | struct mm_struct *mm = vma->vm_mm; | |
1119 | int ret = 0; | |
1120 | ||
025c5b24 NH |
1121 | if (__pmd_trans_huge_lock(pmd, vma) == 1) { |
1122 | pmd_t entry; | |
1123 | entry = pmdp_get_and_clear(mm, addr, pmd); | |
1124 | entry = pmd_modify(entry, newprot); | |
1125 | set_pmd_at(mm, addr, pmd, entry); | |
1126 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1127 | ret = 1; | |
1128 | } | |
1129 | ||
1130 | return ret; | |
1131 | } | |
1132 | ||
1133 | /* | |
1134 | * Returns 1 if a given pmd maps a stable (not under splitting) thp. | |
1135 | * Returns -1 if it maps a thp under splitting. Returns 0 otherwise. | |
1136 | * | |
1137 | * Note that if it returns 1, this routine returns without unlocking page | |
1138 | * table locks. So callers must unlock them. | |
1139 | */ | |
1140 | int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) | |
1141 | { | |
1142 | spin_lock(&vma->vm_mm->page_table_lock); | |
cd7548ab JW |
1143 | if (likely(pmd_trans_huge(*pmd))) { |
1144 | if (unlikely(pmd_trans_splitting(*pmd))) { | |
025c5b24 | 1145 | spin_unlock(&vma->vm_mm->page_table_lock); |
cd7548ab | 1146 | wait_split_huge_page(vma->anon_vma, pmd); |
025c5b24 | 1147 | return -1; |
cd7548ab | 1148 | } else { |
025c5b24 NH |
1149 | /* Thp mapped by 'pmd' is stable, so we can |
1150 | * handle it as it is. */ | |
1151 | return 1; | |
cd7548ab | 1152 | } |
025c5b24 NH |
1153 | } |
1154 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1155 | return 0; | |
cd7548ab JW |
1156 | } |
1157 | ||
71e3aac0 AA |
1158 | pmd_t *page_check_address_pmd(struct page *page, |
1159 | struct mm_struct *mm, | |
1160 | unsigned long address, | |
1161 | enum page_check_address_pmd_flag flag) | |
1162 | { | |
1163 | pgd_t *pgd; | |
1164 | pud_t *pud; | |
1165 | pmd_t *pmd, *ret = NULL; | |
1166 | ||
1167 | if (address & ~HPAGE_PMD_MASK) | |
1168 | goto out; | |
1169 | ||
1170 | pgd = pgd_offset(mm, address); | |
1171 | if (!pgd_present(*pgd)) | |
1172 | goto out; | |
1173 | ||
1174 | pud = pud_offset(pgd, address); | |
1175 | if (!pud_present(*pud)) | |
1176 | goto out; | |
1177 | ||
1178 | pmd = pmd_offset(pud, address); | |
1179 | if (pmd_none(*pmd)) | |
1180 | goto out; | |
1181 | if (pmd_page(*pmd) != page) | |
1182 | goto out; | |
94fcc585 AA |
1183 | /* |
1184 | * split_vma() may create temporary aliased mappings. There is | |
1185 | * no risk as long as all huge pmd are found and have their | |
1186 | * splitting bit set before __split_huge_page_refcount | |
1187 | * runs. Finding the same huge pmd more than once during the | |
1188 | * same rmap walk is not a problem. | |
1189 | */ | |
1190 | if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG && | |
1191 | pmd_trans_splitting(*pmd)) | |
1192 | goto out; | |
71e3aac0 AA |
1193 | if (pmd_trans_huge(*pmd)) { |
1194 | VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG && | |
1195 | !pmd_trans_splitting(*pmd)); | |
1196 | ret = pmd; | |
1197 | } | |
1198 | out: | |
1199 | return ret; | |
1200 | } | |
1201 | ||
1202 | static int __split_huge_page_splitting(struct page *page, | |
1203 | struct vm_area_struct *vma, | |
1204 | unsigned long address) | |
1205 | { | |
1206 | struct mm_struct *mm = vma->vm_mm; | |
1207 | pmd_t *pmd; | |
1208 | int ret = 0; | |
1209 | ||
1210 | spin_lock(&mm->page_table_lock); | |
1211 | pmd = page_check_address_pmd(page, mm, address, | |
1212 | PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG); | |
1213 | if (pmd) { | |
1214 | /* | |
1215 | * We can't temporarily set the pmd to null in order | |
1216 | * to split it, the pmd must remain marked huge at all | |
1217 | * times or the VM won't take the pmd_trans_huge paths | |
2b575eb6 | 1218 | * and it won't wait on the anon_vma->root->mutex to |
71e3aac0 AA |
1219 | * serialize against split_huge_page*. |
1220 | */ | |
1221 | pmdp_splitting_flush_notify(vma, address, pmd); | |
1222 | ret = 1; | |
1223 | } | |
1224 | spin_unlock(&mm->page_table_lock); | |
1225 | ||
1226 | return ret; | |
1227 | } | |
1228 | ||
1229 | static void __split_huge_page_refcount(struct page *page) | |
1230 | { | |
1231 | int i; | |
71e3aac0 | 1232 | struct zone *zone = page_zone(page); |
fa9add64 | 1233 | struct lruvec *lruvec; |
70b50f94 | 1234 | int tail_count = 0; |
71e3aac0 AA |
1235 | |
1236 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
1237 | spin_lock_irq(&zone->lru_lock); | |
fa9add64 HD |
1238 | lruvec = mem_cgroup_page_lruvec(page, zone); |
1239 | ||
71e3aac0 | 1240 | compound_lock(page); |
e94c8a9c KH |
1241 | /* complete memcg works before add pages to LRU */ |
1242 | mem_cgroup_split_huge_fixup(page); | |
71e3aac0 | 1243 | |
45676885 | 1244 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { |
71e3aac0 AA |
1245 | struct page *page_tail = page + i; |
1246 | ||
70b50f94 AA |
1247 | /* tail_page->_mapcount cannot change */ |
1248 | BUG_ON(page_mapcount(page_tail) < 0); | |
1249 | tail_count += page_mapcount(page_tail); | |
1250 | /* check for overflow */ | |
1251 | BUG_ON(tail_count < 0); | |
1252 | BUG_ON(atomic_read(&page_tail->_count) != 0); | |
1253 | /* | |
1254 | * tail_page->_count is zero and not changing from | |
1255 | * under us. But get_page_unless_zero() may be running | |
1256 | * from under us on the tail_page. If we used | |
1257 | * atomic_set() below instead of atomic_add(), we | |
1258 | * would then run atomic_set() concurrently with | |
1259 | * get_page_unless_zero(), and atomic_set() is | |
1260 | * implemented in C not using locked ops. spin_unlock | |
1261 | * on x86 sometime uses locked ops because of PPro | |
1262 | * errata 66, 92, so unless somebody can guarantee | |
1263 | * atomic_set() here would be safe on all archs (and | |
1264 | * not only on x86), it's safer to use atomic_add(). | |
1265 | */ | |
1266 | atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1, | |
1267 | &page_tail->_count); | |
71e3aac0 AA |
1268 | |
1269 | /* after clearing PageTail the gup refcount can be released */ | |
1270 | smp_mb(); | |
1271 | ||
a6d30ddd JD |
1272 | /* |
1273 | * retain hwpoison flag of the poisoned tail page: | |
1274 | * fix for the unsuitable process killed on Guest Machine(KVM) | |
1275 | * by the memory-failure. | |
1276 | */ | |
1277 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON; | |
71e3aac0 AA |
1278 | page_tail->flags |= (page->flags & |
1279 | ((1L << PG_referenced) | | |
1280 | (1L << PG_swapbacked) | | |
1281 | (1L << PG_mlocked) | | |
1282 | (1L << PG_uptodate))); | |
1283 | page_tail->flags |= (1L << PG_dirty); | |
1284 | ||
70b50f94 | 1285 | /* clear PageTail before overwriting first_page */ |
71e3aac0 AA |
1286 | smp_wmb(); |
1287 | ||
1288 | /* | |
1289 | * __split_huge_page_splitting() already set the | |
1290 | * splitting bit in all pmd that could map this | |
1291 | * hugepage, that will ensure no CPU can alter the | |
1292 | * mapcount on the head page. The mapcount is only | |
1293 | * accounted in the head page and it has to be | |
1294 | * transferred to all tail pages in the below code. So | |
1295 | * for this code to be safe, the split the mapcount | |
1296 | * can't change. But that doesn't mean userland can't | |
1297 | * keep changing and reading the page contents while | |
1298 | * we transfer the mapcount, so the pmd splitting | |
1299 | * status is achieved setting a reserved bit in the | |
1300 | * pmd, not by clearing the present bit. | |
1301 | */ | |
71e3aac0 AA |
1302 | page_tail->_mapcount = page->_mapcount; |
1303 | ||
1304 | BUG_ON(page_tail->mapping); | |
1305 | page_tail->mapping = page->mapping; | |
1306 | ||
45676885 | 1307 | page_tail->index = page->index + i; |
71e3aac0 AA |
1308 | |
1309 | BUG_ON(!PageAnon(page_tail)); | |
1310 | BUG_ON(!PageUptodate(page_tail)); | |
1311 | BUG_ON(!PageDirty(page_tail)); | |
1312 | BUG_ON(!PageSwapBacked(page_tail)); | |
1313 | ||
fa9add64 | 1314 | lru_add_page_tail(page, page_tail, lruvec); |
71e3aac0 | 1315 | } |
70b50f94 AA |
1316 | atomic_sub(tail_count, &page->_count); |
1317 | BUG_ON(atomic_read(&page->_count) <= 0); | |
71e3aac0 | 1318 | |
fa9add64 | 1319 | __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1); |
79134171 AA |
1320 | __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR); |
1321 | ||
71e3aac0 AA |
1322 | ClearPageCompound(page); |
1323 | compound_unlock(page); | |
1324 | spin_unlock_irq(&zone->lru_lock); | |
1325 | ||
1326 | for (i = 1; i < HPAGE_PMD_NR; i++) { | |
1327 | struct page *page_tail = page + i; | |
1328 | BUG_ON(page_count(page_tail) <= 0); | |
1329 | /* | |
1330 | * Tail pages may be freed if there wasn't any mapping | |
1331 | * like if add_to_swap() is running on a lru page that | |
1332 | * had its mapping zapped. And freeing these pages | |
1333 | * requires taking the lru_lock so we do the put_page | |
1334 | * of the tail pages after the split is complete. | |
1335 | */ | |
1336 | put_page(page_tail); | |
1337 | } | |
1338 | ||
1339 | /* | |
1340 | * Only the head page (now become a regular page) is required | |
1341 | * to be pinned by the caller. | |
1342 | */ | |
1343 | BUG_ON(page_count(page) <= 0); | |
1344 | } | |
1345 | ||
1346 | static int __split_huge_page_map(struct page *page, | |
1347 | struct vm_area_struct *vma, | |
1348 | unsigned long address) | |
1349 | { | |
1350 | struct mm_struct *mm = vma->vm_mm; | |
1351 | pmd_t *pmd, _pmd; | |
1352 | int ret = 0, i; | |
1353 | pgtable_t pgtable; | |
1354 | unsigned long haddr; | |
1355 | ||
1356 | spin_lock(&mm->page_table_lock); | |
1357 | pmd = page_check_address_pmd(page, mm, address, | |
1358 | PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG); | |
1359 | if (pmd) { | |
1360 | pgtable = get_pmd_huge_pte(mm); | |
1361 | pmd_populate(mm, &_pmd, pgtable); | |
1362 | ||
1363 | for (i = 0, haddr = address; i < HPAGE_PMD_NR; | |
1364 | i++, haddr += PAGE_SIZE) { | |
1365 | pte_t *pte, entry; | |
1366 | BUG_ON(PageCompound(page+i)); | |
1367 | entry = mk_pte(page + i, vma->vm_page_prot); | |
1368 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
1369 | if (!pmd_write(*pmd)) | |
1370 | entry = pte_wrprotect(entry); | |
1371 | else | |
1372 | BUG_ON(page_mapcount(page) != 1); | |
1373 | if (!pmd_young(*pmd)) | |
1374 | entry = pte_mkold(entry); | |
1375 | pte = pte_offset_map(&_pmd, haddr); | |
1376 | BUG_ON(!pte_none(*pte)); | |
1377 | set_pte_at(mm, haddr, pte, entry); | |
1378 | pte_unmap(pte); | |
1379 | } | |
1380 | ||
71e3aac0 AA |
1381 | smp_wmb(); /* make pte visible before pmd */ |
1382 | /* | |
1383 | * Up to this point the pmd is present and huge and | |
1384 | * userland has the whole access to the hugepage | |
1385 | * during the split (which happens in place). If we | |
1386 | * overwrite the pmd with the not-huge version | |
1387 | * pointing to the pte here (which of course we could | |
1388 | * if all CPUs were bug free), userland could trigger | |
1389 | * a small page size TLB miss on the small sized TLB | |
1390 | * while the hugepage TLB entry is still established | |
1391 | * in the huge TLB. Some CPU doesn't like that. See | |
1392 | * http://support.amd.com/us/Processor_TechDocs/41322.pdf, | |
1393 | * Erratum 383 on page 93. Intel should be safe but is | |
1394 | * also warns that it's only safe if the permission | |
1395 | * and cache attributes of the two entries loaded in | |
1396 | * the two TLB is identical (which should be the case | |
1397 | * here). But it is generally safer to never allow | |
1398 | * small and huge TLB entries for the same virtual | |
1399 | * address to be loaded simultaneously. So instead of | |
1400 | * doing "pmd_populate(); flush_tlb_range();" we first | |
1401 | * mark the current pmd notpresent (atomically because | |
1402 | * here the pmd_trans_huge and pmd_trans_splitting | |
1403 | * must remain set at all times on the pmd until the | |
1404 | * split is complete for this pmd), then we flush the | |
1405 | * SMP TLB and finally we write the non-huge version | |
1406 | * of the pmd entry with pmd_populate. | |
1407 | */ | |
1408 | set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd)); | |
1409 | flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); | |
1410 | pmd_populate(mm, pmd, pgtable); | |
1411 | ret = 1; | |
1412 | } | |
1413 | spin_unlock(&mm->page_table_lock); | |
1414 | ||
1415 | return ret; | |
1416 | } | |
1417 | ||
2b575eb6 | 1418 | /* must be called with anon_vma->root->mutex hold */ |
71e3aac0 AA |
1419 | static void __split_huge_page(struct page *page, |
1420 | struct anon_vma *anon_vma) | |
1421 | { | |
1422 | int mapcount, mapcount2; | |
1423 | struct anon_vma_chain *avc; | |
1424 | ||
1425 | BUG_ON(!PageHead(page)); | |
1426 | BUG_ON(PageTail(page)); | |
1427 | ||
1428 | mapcount = 0; | |
1429 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { | |
1430 | struct vm_area_struct *vma = avc->vma; | |
1431 | unsigned long addr = vma_address(page, vma); | |
1432 | BUG_ON(is_vma_temporary_stack(vma)); | |
1433 | if (addr == -EFAULT) | |
1434 | continue; | |
1435 | mapcount += __split_huge_page_splitting(page, vma, addr); | |
1436 | } | |
05759d38 AA |
1437 | /* |
1438 | * It is critical that new vmas are added to the tail of the | |
1439 | * anon_vma list. This guarantes that if copy_huge_pmd() runs | |
1440 | * and establishes a child pmd before | |
1441 | * __split_huge_page_splitting() freezes the parent pmd (so if | |
1442 | * we fail to prevent copy_huge_pmd() from running until the | |
1443 | * whole __split_huge_page() is complete), we will still see | |
1444 | * the newly established pmd of the child later during the | |
1445 | * walk, to be able to set it as pmd_trans_splitting too. | |
1446 | */ | |
1447 | if (mapcount != page_mapcount(page)) | |
1448 | printk(KERN_ERR "mapcount %d page_mapcount %d\n", | |
1449 | mapcount, page_mapcount(page)); | |
71e3aac0 AA |
1450 | BUG_ON(mapcount != page_mapcount(page)); |
1451 | ||
1452 | __split_huge_page_refcount(page); | |
1453 | ||
1454 | mapcount2 = 0; | |
1455 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { | |
1456 | struct vm_area_struct *vma = avc->vma; | |
1457 | unsigned long addr = vma_address(page, vma); | |
1458 | BUG_ON(is_vma_temporary_stack(vma)); | |
1459 | if (addr == -EFAULT) | |
1460 | continue; | |
1461 | mapcount2 += __split_huge_page_map(page, vma, addr); | |
1462 | } | |
05759d38 AA |
1463 | if (mapcount != mapcount2) |
1464 | printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n", | |
1465 | mapcount, mapcount2, page_mapcount(page)); | |
71e3aac0 AA |
1466 | BUG_ON(mapcount != mapcount2); |
1467 | } | |
1468 | ||
1469 | int split_huge_page(struct page *page) | |
1470 | { | |
1471 | struct anon_vma *anon_vma; | |
1472 | int ret = 1; | |
1473 | ||
1474 | BUG_ON(!PageAnon(page)); | |
1475 | anon_vma = page_lock_anon_vma(page); | |
1476 | if (!anon_vma) | |
1477 | goto out; | |
1478 | ret = 0; | |
1479 | if (!PageCompound(page)) | |
1480 | goto out_unlock; | |
1481 | ||
1482 | BUG_ON(!PageSwapBacked(page)); | |
1483 | __split_huge_page(page, anon_vma); | |
81ab4201 | 1484 | count_vm_event(THP_SPLIT); |
71e3aac0 AA |
1485 | |
1486 | BUG_ON(PageCompound(page)); | |
1487 | out_unlock: | |
1488 | page_unlock_anon_vma(anon_vma); | |
1489 | out: | |
1490 | return ret; | |
1491 | } | |
1492 | ||
4b6e1e37 | 1493 | #define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE) |
78f11a25 | 1494 | |
60ab3244 AA |
1495 | int hugepage_madvise(struct vm_area_struct *vma, |
1496 | unsigned long *vm_flags, int advice) | |
0af4e98b | 1497 | { |
a664b2d8 AA |
1498 | switch (advice) { |
1499 | case MADV_HUGEPAGE: | |
1500 | /* | |
1501 | * Be somewhat over-protective like KSM for now! | |
1502 | */ | |
78f11a25 | 1503 | if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP)) |
a664b2d8 AA |
1504 | return -EINVAL; |
1505 | *vm_flags &= ~VM_NOHUGEPAGE; | |
1506 | *vm_flags |= VM_HUGEPAGE; | |
60ab3244 AA |
1507 | /* |
1508 | * If the vma become good for khugepaged to scan, | |
1509 | * register it here without waiting a page fault that | |
1510 | * may not happen any time soon. | |
1511 | */ | |
1512 | if (unlikely(khugepaged_enter_vma_merge(vma))) | |
1513 | return -ENOMEM; | |
a664b2d8 AA |
1514 | break; |
1515 | case MADV_NOHUGEPAGE: | |
1516 | /* | |
1517 | * Be somewhat over-protective like KSM for now! | |
1518 | */ | |
78f11a25 | 1519 | if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP)) |
a664b2d8 AA |
1520 | return -EINVAL; |
1521 | *vm_flags &= ~VM_HUGEPAGE; | |
1522 | *vm_flags |= VM_NOHUGEPAGE; | |
60ab3244 AA |
1523 | /* |
1524 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
1525 | * this vma even if we leave the mm registered in khugepaged if | |
1526 | * it got registered before VM_NOHUGEPAGE was set. | |
1527 | */ | |
a664b2d8 AA |
1528 | break; |
1529 | } | |
0af4e98b AA |
1530 | |
1531 | return 0; | |
1532 | } | |
1533 | ||
ba76149f AA |
1534 | static int __init khugepaged_slab_init(void) |
1535 | { | |
1536 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
1537 | sizeof(struct mm_slot), | |
1538 | __alignof__(struct mm_slot), 0, NULL); | |
1539 | if (!mm_slot_cache) | |
1540 | return -ENOMEM; | |
1541 | ||
1542 | return 0; | |
1543 | } | |
1544 | ||
1545 | static void __init khugepaged_slab_free(void) | |
1546 | { | |
1547 | kmem_cache_destroy(mm_slot_cache); | |
1548 | mm_slot_cache = NULL; | |
1549 | } | |
1550 | ||
1551 | static inline struct mm_slot *alloc_mm_slot(void) | |
1552 | { | |
1553 | if (!mm_slot_cache) /* initialization failed */ | |
1554 | return NULL; | |
1555 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
1556 | } | |
1557 | ||
1558 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
1559 | { | |
1560 | kmem_cache_free(mm_slot_cache, mm_slot); | |
1561 | } | |
1562 | ||
1563 | static int __init mm_slots_hash_init(void) | |
1564 | { | |
1565 | mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head), | |
1566 | GFP_KERNEL); | |
1567 | if (!mm_slots_hash) | |
1568 | return -ENOMEM; | |
1569 | return 0; | |
1570 | } | |
1571 | ||
1572 | #if 0 | |
1573 | static void __init mm_slots_hash_free(void) | |
1574 | { | |
1575 | kfree(mm_slots_hash); | |
1576 | mm_slots_hash = NULL; | |
1577 | } | |
1578 | #endif | |
1579 | ||
1580 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
1581 | { | |
1582 | struct mm_slot *mm_slot; | |
1583 | struct hlist_head *bucket; | |
1584 | struct hlist_node *node; | |
1585 | ||
1586 | bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct)) | |
1587 | % MM_SLOTS_HASH_HEADS]; | |
1588 | hlist_for_each_entry(mm_slot, node, bucket, hash) { | |
1589 | if (mm == mm_slot->mm) | |
1590 | return mm_slot; | |
1591 | } | |
1592 | return NULL; | |
1593 | } | |
1594 | ||
1595 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
1596 | struct mm_slot *mm_slot) | |
1597 | { | |
1598 | struct hlist_head *bucket; | |
1599 | ||
1600 | bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct)) | |
1601 | % MM_SLOTS_HASH_HEADS]; | |
1602 | mm_slot->mm = mm; | |
1603 | hlist_add_head(&mm_slot->hash, bucket); | |
1604 | } | |
1605 | ||
1606 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
1607 | { | |
1608 | return atomic_read(&mm->mm_users) == 0; | |
1609 | } | |
1610 | ||
1611 | int __khugepaged_enter(struct mm_struct *mm) | |
1612 | { | |
1613 | struct mm_slot *mm_slot; | |
1614 | int wakeup; | |
1615 | ||
1616 | mm_slot = alloc_mm_slot(); | |
1617 | if (!mm_slot) | |
1618 | return -ENOMEM; | |
1619 | ||
1620 | /* __khugepaged_exit() must not run from under us */ | |
1621 | VM_BUG_ON(khugepaged_test_exit(mm)); | |
1622 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { | |
1623 | free_mm_slot(mm_slot); | |
1624 | return 0; | |
1625 | } | |
1626 | ||
1627 | spin_lock(&khugepaged_mm_lock); | |
1628 | insert_to_mm_slots_hash(mm, mm_slot); | |
1629 | /* | |
1630 | * Insert just behind the scanning cursor, to let the area settle | |
1631 | * down a little. | |
1632 | */ | |
1633 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
1634 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
1635 | spin_unlock(&khugepaged_mm_lock); | |
1636 | ||
1637 | atomic_inc(&mm->mm_count); | |
1638 | if (wakeup) | |
1639 | wake_up_interruptible(&khugepaged_wait); | |
1640 | ||
1641 | return 0; | |
1642 | } | |
1643 | ||
1644 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma) | |
1645 | { | |
1646 | unsigned long hstart, hend; | |
1647 | if (!vma->anon_vma) | |
1648 | /* | |
1649 | * Not yet faulted in so we will register later in the | |
1650 | * page fault if needed. | |
1651 | */ | |
1652 | return 0; | |
78f11a25 | 1653 | if (vma->vm_ops) |
ba76149f AA |
1654 | /* khugepaged not yet working on file or special mappings */ |
1655 | return 0; | |
b3b9c293 | 1656 | VM_BUG_ON(vma->vm_flags & VM_NO_THP); |
ba76149f AA |
1657 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
1658 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1659 | if (hstart < hend) | |
1660 | return khugepaged_enter(vma); | |
1661 | return 0; | |
1662 | } | |
1663 | ||
1664 | void __khugepaged_exit(struct mm_struct *mm) | |
1665 | { | |
1666 | struct mm_slot *mm_slot; | |
1667 | int free = 0; | |
1668 | ||
1669 | spin_lock(&khugepaged_mm_lock); | |
1670 | mm_slot = get_mm_slot(mm); | |
1671 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
1672 | hlist_del(&mm_slot->hash); | |
1673 | list_del(&mm_slot->mm_node); | |
1674 | free = 1; | |
1675 | } | |
d788e80a | 1676 | spin_unlock(&khugepaged_mm_lock); |
ba76149f AA |
1677 | |
1678 | if (free) { | |
ba76149f AA |
1679 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); |
1680 | free_mm_slot(mm_slot); | |
1681 | mmdrop(mm); | |
1682 | } else if (mm_slot) { | |
ba76149f AA |
1683 | /* |
1684 | * This is required to serialize against | |
1685 | * khugepaged_test_exit() (which is guaranteed to run | |
1686 | * under mmap sem read mode). Stop here (after we | |
1687 | * return all pagetables will be destroyed) until | |
1688 | * khugepaged has finished working on the pagetables | |
1689 | * under the mmap_sem. | |
1690 | */ | |
1691 | down_write(&mm->mmap_sem); | |
1692 | up_write(&mm->mmap_sem); | |
d788e80a | 1693 | } |
ba76149f AA |
1694 | } |
1695 | ||
1696 | static void release_pte_page(struct page *page) | |
1697 | { | |
1698 | /* 0 stands for page_is_file_cache(page) == false */ | |
1699 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
1700 | unlock_page(page); | |
1701 | putback_lru_page(page); | |
1702 | } | |
1703 | ||
1704 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
1705 | { | |
1706 | while (--_pte >= pte) { | |
1707 | pte_t pteval = *_pte; | |
1708 | if (!pte_none(pteval)) | |
1709 | release_pte_page(pte_page(pteval)); | |
1710 | } | |
1711 | } | |
1712 | ||
1713 | static void release_all_pte_pages(pte_t *pte) | |
1714 | { | |
1715 | release_pte_pages(pte, pte + HPAGE_PMD_NR); | |
1716 | } | |
1717 | ||
1718 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, | |
1719 | unsigned long address, | |
1720 | pte_t *pte) | |
1721 | { | |
1722 | struct page *page; | |
1723 | pte_t *_pte; | |
1724 | int referenced = 0, isolated = 0, none = 0; | |
1725 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1726 | _pte++, address += PAGE_SIZE) { | |
1727 | pte_t pteval = *_pte; | |
1728 | if (pte_none(pteval)) { | |
1729 | if (++none <= khugepaged_max_ptes_none) | |
1730 | continue; | |
1731 | else { | |
1732 | release_pte_pages(pte, _pte); | |
1733 | goto out; | |
1734 | } | |
1735 | } | |
1736 | if (!pte_present(pteval) || !pte_write(pteval)) { | |
1737 | release_pte_pages(pte, _pte); | |
1738 | goto out; | |
1739 | } | |
1740 | page = vm_normal_page(vma, address, pteval); | |
1741 | if (unlikely(!page)) { | |
1742 | release_pte_pages(pte, _pte); | |
1743 | goto out; | |
1744 | } | |
1745 | VM_BUG_ON(PageCompound(page)); | |
1746 | BUG_ON(!PageAnon(page)); | |
1747 | VM_BUG_ON(!PageSwapBacked(page)); | |
1748 | ||
1749 | /* cannot use mapcount: can't collapse if there's a gup pin */ | |
1750 | if (page_count(page) != 1) { | |
1751 | release_pte_pages(pte, _pte); | |
1752 | goto out; | |
1753 | } | |
1754 | /* | |
1755 | * We can do it before isolate_lru_page because the | |
1756 | * page can't be freed from under us. NOTE: PG_lock | |
1757 | * is needed to serialize against split_huge_page | |
1758 | * when invoked from the VM. | |
1759 | */ | |
1760 | if (!trylock_page(page)) { | |
1761 | release_pte_pages(pte, _pte); | |
1762 | goto out; | |
1763 | } | |
1764 | /* | |
1765 | * Isolate the page to avoid collapsing an hugepage | |
1766 | * currently in use by the VM. | |
1767 | */ | |
1768 | if (isolate_lru_page(page)) { | |
1769 | unlock_page(page); | |
1770 | release_pte_pages(pte, _pte); | |
1771 | goto out; | |
1772 | } | |
1773 | /* 0 stands for page_is_file_cache(page) == false */ | |
1774 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
1775 | VM_BUG_ON(!PageLocked(page)); | |
1776 | VM_BUG_ON(PageLRU(page)); | |
1777 | ||
1778 | /* If there is no mapped pte young don't collapse the page */ | |
8ee53820 AA |
1779 | if (pte_young(pteval) || PageReferenced(page) || |
1780 | mmu_notifier_test_young(vma->vm_mm, address)) | |
ba76149f AA |
1781 | referenced = 1; |
1782 | } | |
1783 | if (unlikely(!referenced)) | |
1784 | release_all_pte_pages(pte); | |
1785 | else | |
1786 | isolated = 1; | |
1787 | out: | |
1788 | return isolated; | |
1789 | } | |
1790 | ||
1791 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
1792 | struct vm_area_struct *vma, | |
1793 | unsigned long address, | |
1794 | spinlock_t *ptl) | |
1795 | { | |
1796 | pte_t *_pte; | |
1797 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { | |
1798 | pte_t pteval = *_pte; | |
1799 | struct page *src_page; | |
1800 | ||
1801 | if (pte_none(pteval)) { | |
1802 | clear_user_highpage(page, address); | |
1803 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
1804 | } else { | |
1805 | src_page = pte_page(pteval); | |
1806 | copy_user_highpage(page, src_page, address, vma); | |
1807 | VM_BUG_ON(page_mapcount(src_page) != 1); | |
ba76149f AA |
1808 | release_pte_page(src_page); |
1809 | /* | |
1810 | * ptl mostly unnecessary, but preempt has to | |
1811 | * be disabled to update the per-cpu stats | |
1812 | * inside page_remove_rmap(). | |
1813 | */ | |
1814 | spin_lock(ptl); | |
1815 | /* | |
1816 | * paravirt calls inside pte_clear here are | |
1817 | * superfluous. | |
1818 | */ | |
1819 | pte_clear(vma->vm_mm, address, _pte); | |
1820 | page_remove_rmap(src_page); | |
1821 | spin_unlock(ptl); | |
1822 | free_page_and_swap_cache(src_page); | |
1823 | } | |
1824 | ||
1825 | address += PAGE_SIZE; | |
1826 | page++; | |
1827 | } | |
1828 | } | |
1829 | ||
26234f36 | 1830 | static void khugepaged_alloc_sleep(void) |
ba76149f | 1831 | { |
26234f36 XG |
1832 | wait_event_freezable_timeout(khugepaged_wait, false, |
1833 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
1834 | } | |
ba76149f | 1835 | |
26234f36 XG |
1836 | #ifdef CONFIG_NUMA |
1837 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
1838 | { | |
1839 | if (IS_ERR(*hpage)) { | |
1840 | if (!*wait) | |
1841 | return false; | |
1842 | ||
1843 | *wait = false; | |
1844 | khugepaged_alloc_sleep(); | |
1845 | } else if (*hpage) { | |
1846 | put_page(*hpage); | |
1847 | *hpage = NULL; | |
1848 | } | |
1849 | ||
1850 | return true; | |
1851 | } | |
1852 | ||
1853 | static struct page | |
1854 | *khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm, | |
1855 | struct vm_area_struct *vma, unsigned long address, | |
1856 | int node) | |
1857 | { | |
0bbbc0b3 | 1858 | VM_BUG_ON(*hpage); |
ce83d217 AA |
1859 | /* |
1860 | * Allocate the page while the vma is still valid and under | |
1861 | * the mmap_sem read mode so there is no memory allocation | |
1862 | * later when we take the mmap_sem in write mode. This is more | |
1863 | * friendly behavior (OTOH it may actually hide bugs) to | |
1864 | * filesystems in userland with daemons allocating memory in | |
1865 | * the userland I/O paths. Allocating memory with the | |
1866 | * mmap_sem in read mode is good idea also to allow greater | |
1867 | * scalability. | |
1868 | */ | |
26234f36 | 1869 | *hpage = alloc_hugepage_vma(khugepaged_defrag(), vma, address, |
cc5d462f | 1870 | node, __GFP_OTHER_NODE); |
692e0b35 AA |
1871 | |
1872 | /* | |
1873 | * After allocating the hugepage, release the mmap_sem read lock in | |
1874 | * preparation for taking it in write mode. | |
1875 | */ | |
1876 | up_read(&mm->mmap_sem); | |
26234f36 | 1877 | if (unlikely(!*hpage)) { |
81ab4201 | 1878 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); |
ce83d217 | 1879 | *hpage = ERR_PTR(-ENOMEM); |
26234f36 | 1880 | return NULL; |
ce83d217 | 1881 | } |
26234f36 | 1882 | |
65b3c07b | 1883 | count_vm_event(THP_COLLAPSE_ALLOC); |
26234f36 XG |
1884 | return *hpage; |
1885 | } | |
1886 | #else | |
1887 | static struct page *khugepaged_alloc_hugepage(bool *wait) | |
1888 | { | |
1889 | struct page *hpage; | |
1890 | ||
1891 | do { | |
1892 | hpage = alloc_hugepage(khugepaged_defrag()); | |
1893 | if (!hpage) { | |
1894 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
1895 | if (!*wait) | |
1896 | return NULL; | |
1897 | ||
1898 | *wait = false; | |
1899 | khugepaged_alloc_sleep(); | |
1900 | } else | |
1901 | count_vm_event(THP_COLLAPSE_ALLOC); | |
1902 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
1903 | ||
1904 | return hpage; | |
1905 | } | |
1906 | ||
1907 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
1908 | { | |
1909 | if (!*hpage) | |
1910 | *hpage = khugepaged_alloc_hugepage(wait); | |
1911 | ||
1912 | if (unlikely(!*hpage)) | |
1913 | return false; | |
1914 | ||
1915 | return true; | |
1916 | } | |
1917 | ||
1918 | static struct page | |
1919 | *khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm, | |
1920 | struct vm_area_struct *vma, unsigned long address, | |
1921 | int node) | |
1922 | { | |
1923 | up_read(&mm->mmap_sem); | |
1924 | VM_BUG_ON(!*hpage); | |
1925 | return *hpage; | |
1926 | } | |
692e0b35 AA |
1927 | #endif |
1928 | ||
26234f36 XG |
1929 | static void collapse_huge_page(struct mm_struct *mm, |
1930 | unsigned long address, | |
1931 | struct page **hpage, | |
1932 | struct vm_area_struct *vma, | |
1933 | int node) | |
1934 | { | |
1935 | pgd_t *pgd; | |
1936 | pud_t *pud; | |
1937 | pmd_t *pmd, _pmd; | |
1938 | pte_t *pte; | |
1939 | pgtable_t pgtable; | |
1940 | struct page *new_page; | |
1941 | spinlock_t *ptl; | |
1942 | int isolated; | |
1943 | unsigned long hstart, hend; | |
1944 | ||
1945 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1946 | ||
1947 | /* release the mmap_sem read lock. */ | |
1948 | new_page = khugepaged_alloc_page(hpage, mm, vma, address, node); | |
1949 | if (!new_page) | |
1950 | return; | |
1951 | ||
420256ef | 1952 | if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) |
ce83d217 | 1953 | return; |
ba76149f AA |
1954 | |
1955 | /* | |
1956 | * Prevent all access to pagetables with the exception of | |
1957 | * gup_fast later hanlded by the ptep_clear_flush and the VM | |
1958 | * handled by the anon_vma lock + PG_lock. | |
1959 | */ | |
1960 | down_write(&mm->mmap_sem); | |
1961 | if (unlikely(khugepaged_test_exit(mm))) | |
1962 | goto out; | |
1963 | ||
1964 | vma = find_vma(mm, address); | |
1965 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
1966 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1967 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
1968 | goto out; | |
1969 | ||
60ab3244 AA |
1970 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || |
1971 | (vma->vm_flags & VM_NOHUGEPAGE)) | |
ba76149f AA |
1972 | goto out; |
1973 | ||
78f11a25 | 1974 | if (!vma->anon_vma || vma->vm_ops) |
ba76149f | 1975 | goto out; |
a7d6e4ec AA |
1976 | if (is_vma_temporary_stack(vma)) |
1977 | goto out; | |
b3b9c293 | 1978 | VM_BUG_ON(vma->vm_flags & VM_NO_THP); |
ba76149f AA |
1979 | |
1980 | pgd = pgd_offset(mm, address); | |
1981 | if (!pgd_present(*pgd)) | |
1982 | goto out; | |
1983 | ||
1984 | pud = pud_offset(pgd, address); | |
1985 | if (!pud_present(*pud)) | |
1986 | goto out; | |
1987 | ||
1988 | pmd = pmd_offset(pud, address); | |
1989 | /* pmd can't go away or become huge under us */ | |
1990 | if (!pmd_present(*pmd) || pmd_trans_huge(*pmd)) | |
1991 | goto out; | |
1992 | ||
ba76149f AA |
1993 | anon_vma_lock(vma->anon_vma); |
1994 | ||
1995 | pte = pte_offset_map(pmd, address); | |
1996 | ptl = pte_lockptr(mm, pmd); | |
1997 | ||
1998 | spin_lock(&mm->page_table_lock); /* probably unnecessary */ | |
1999 | /* | |
2000 | * After this gup_fast can't run anymore. This also removes | |
2001 | * any huge TLB entry from the CPU so we won't allow | |
2002 | * huge and small TLB entries for the same virtual address | |
2003 | * to avoid the risk of CPU bugs in that area. | |
2004 | */ | |
2005 | _pmd = pmdp_clear_flush_notify(vma, address, pmd); | |
2006 | spin_unlock(&mm->page_table_lock); | |
2007 | ||
2008 | spin_lock(ptl); | |
2009 | isolated = __collapse_huge_page_isolate(vma, address, pte); | |
2010 | spin_unlock(ptl); | |
ba76149f AA |
2011 | |
2012 | if (unlikely(!isolated)) { | |
453c7192 | 2013 | pte_unmap(pte); |
ba76149f AA |
2014 | spin_lock(&mm->page_table_lock); |
2015 | BUG_ON(!pmd_none(*pmd)); | |
2016 | set_pmd_at(mm, address, pmd, _pmd); | |
2017 | spin_unlock(&mm->page_table_lock); | |
2018 | anon_vma_unlock(vma->anon_vma); | |
ce83d217 | 2019 | goto out; |
ba76149f AA |
2020 | } |
2021 | ||
2022 | /* | |
2023 | * All pages are isolated and locked so anon_vma rmap | |
2024 | * can't run anymore. | |
2025 | */ | |
2026 | anon_vma_unlock(vma->anon_vma); | |
2027 | ||
2028 | __collapse_huge_page_copy(pte, new_page, vma, address, ptl); | |
453c7192 | 2029 | pte_unmap(pte); |
ba76149f AA |
2030 | __SetPageUptodate(new_page); |
2031 | pgtable = pmd_pgtable(_pmd); | |
2032 | VM_BUG_ON(page_count(pgtable) != 1); | |
2033 | VM_BUG_ON(page_mapcount(pgtable) != 0); | |
2034 | ||
2035 | _pmd = mk_pmd(new_page, vma->vm_page_prot); | |
2036 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); | |
2037 | _pmd = pmd_mkhuge(_pmd); | |
2038 | ||
2039 | /* | |
2040 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
2041 | * this is needed to avoid the copy_huge_page writes to become | |
2042 | * visible after the set_pmd_at() write. | |
2043 | */ | |
2044 | smp_wmb(); | |
2045 | ||
2046 | spin_lock(&mm->page_table_lock); | |
2047 | BUG_ON(!pmd_none(*pmd)); | |
2048 | page_add_new_anon_rmap(new_page, vma, address); | |
2049 | set_pmd_at(mm, address, pmd, _pmd); | |
35d8c7ad | 2050 | update_mmu_cache(vma, address, _pmd); |
ba76149f | 2051 | prepare_pmd_huge_pte(pgtable, mm); |
ba76149f AA |
2052 | spin_unlock(&mm->page_table_lock); |
2053 | ||
2054 | *hpage = NULL; | |
420256ef | 2055 | |
ba76149f | 2056 | khugepaged_pages_collapsed++; |
ce83d217 | 2057 | out_up_write: |
ba76149f | 2058 | up_write(&mm->mmap_sem); |
0bbbc0b3 AA |
2059 | return; |
2060 | ||
ce83d217 | 2061 | out: |
678ff896 | 2062 | mem_cgroup_uncharge_page(new_page); |
ce83d217 | 2063 | goto out_up_write; |
ba76149f AA |
2064 | } |
2065 | ||
2066 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
2067 | struct vm_area_struct *vma, | |
2068 | unsigned long address, | |
2069 | struct page **hpage) | |
2070 | { | |
2071 | pgd_t *pgd; | |
2072 | pud_t *pud; | |
2073 | pmd_t *pmd; | |
2074 | pte_t *pte, *_pte; | |
2075 | int ret = 0, referenced = 0, none = 0; | |
2076 | struct page *page; | |
2077 | unsigned long _address; | |
2078 | spinlock_t *ptl; | |
5c4b4be3 | 2079 | int node = -1; |
ba76149f AA |
2080 | |
2081 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2082 | ||
2083 | pgd = pgd_offset(mm, address); | |
2084 | if (!pgd_present(*pgd)) | |
2085 | goto out; | |
2086 | ||
2087 | pud = pud_offset(pgd, address); | |
2088 | if (!pud_present(*pud)) | |
2089 | goto out; | |
2090 | ||
2091 | pmd = pmd_offset(pud, address); | |
2092 | if (!pmd_present(*pmd) || pmd_trans_huge(*pmd)) | |
2093 | goto out; | |
2094 | ||
2095 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
2096 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
2097 | _pte++, _address += PAGE_SIZE) { | |
2098 | pte_t pteval = *_pte; | |
2099 | if (pte_none(pteval)) { | |
2100 | if (++none <= khugepaged_max_ptes_none) | |
2101 | continue; | |
2102 | else | |
2103 | goto out_unmap; | |
2104 | } | |
2105 | if (!pte_present(pteval) || !pte_write(pteval)) | |
2106 | goto out_unmap; | |
2107 | page = vm_normal_page(vma, _address, pteval); | |
2108 | if (unlikely(!page)) | |
2109 | goto out_unmap; | |
5c4b4be3 AK |
2110 | /* |
2111 | * Chose the node of the first page. This could | |
2112 | * be more sophisticated and look at more pages, | |
2113 | * but isn't for now. | |
2114 | */ | |
2115 | if (node == -1) | |
2116 | node = page_to_nid(page); | |
ba76149f AA |
2117 | VM_BUG_ON(PageCompound(page)); |
2118 | if (!PageLRU(page) || PageLocked(page) || !PageAnon(page)) | |
2119 | goto out_unmap; | |
2120 | /* cannot use mapcount: can't collapse if there's a gup pin */ | |
2121 | if (page_count(page) != 1) | |
2122 | goto out_unmap; | |
8ee53820 AA |
2123 | if (pte_young(pteval) || PageReferenced(page) || |
2124 | mmu_notifier_test_young(vma->vm_mm, address)) | |
ba76149f AA |
2125 | referenced = 1; |
2126 | } | |
2127 | if (referenced) | |
2128 | ret = 1; | |
2129 | out_unmap: | |
2130 | pte_unmap_unlock(pte, ptl); | |
ce83d217 AA |
2131 | if (ret) |
2132 | /* collapse_huge_page will return with the mmap_sem released */ | |
5c4b4be3 | 2133 | collapse_huge_page(mm, address, hpage, vma, node); |
ba76149f AA |
2134 | out: |
2135 | return ret; | |
2136 | } | |
2137 | ||
2138 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
2139 | { | |
2140 | struct mm_struct *mm = mm_slot->mm; | |
2141 | ||
b9980cdc | 2142 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2143 | |
2144 | if (khugepaged_test_exit(mm)) { | |
2145 | /* free mm_slot */ | |
2146 | hlist_del(&mm_slot->hash); | |
2147 | list_del(&mm_slot->mm_node); | |
2148 | ||
2149 | /* | |
2150 | * Not strictly needed because the mm exited already. | |
2151 | * | |
2152 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
2153 | */ | |
2154 | ||
2155 | /* khugepaged_mm_lock actually not necessary for the below */ | |
2156 | free_mm_slot(mm_slot); | |
2157 | mmdrop(mm); | |
2158 | } | |
2159 | } | |
2160 | ||
2161 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
2162 | struct page **hpage) | |
2f1da642 HS |
2163 | __releases(&khugepaged_mm_lock) |
2164 | __acquires(&khugepaged_mm_lock) | |
ba76149f AA |
2165 | { |
2166 | struct mm_slot *mm_slot; | |
2167 | struct mm_struct *mm; | |
2168 | struct vm_area_struct *vma; | |
2169 | int progress = 0; | |
2170 | ||
2171 | VM_BUG_ON(!pages); | |
b9980cdc | 2172 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2173 | |
2174 | if (khugepaged_scan.mm_slot) | |
2175 | mm_slot = khugepaged_scan.mm_slot; | |
2176 | else { | |
2177 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2178 | struct mm_slot, mm_node); | |
2179 | khugepaged_scan.address = 0; | |
2180 | khugepaged_scan.mm_slot = mm_slot; | |
2181 | } | |
2182 | spin_unlock(&khugepaged_mm_lock); | |
2183 | ||
2184 | mm = mm_slot->mm; | |
2185 | down_read(&mm->mmap_sem); | |
2186 | if (unlikely(khugepaged_test_exit(mm))) | |
2187 | vma = NULL; | |
2188 | else | |
2189 | vma = find_vma(mm, khugepaged_scan.address); | |
2190 | ||
2191 | progress++; | |
2192 | for (; vma; vma = vma->vm_next) { | |
2193 | unsigned long hstart, hend; | |
2194 | ||
2195 | cond_resched(); | |
2196 | if (unlikely(khugepaged_test_exit(mm))) { | |
2197 | progress++; | |
2198 | break; | |
2199 | } | |
2200 | ||
60ab3244 AA |
2201 | if ((!(vma->vm_flags & VM_HUGEPAGE) && |
2202 | !khugepaged_always()) || | |
2203 | (vma->vm_flags & VM_NOHUGEPAGE)) { | |
a7d6e4ec | 2204 | skip: |
ba76149f AA |
2205 | progress++; |
2206 | continue; | |
2207 | } | |
78f11a25 | 2208 | if (!vma->anon_vma || vma->vm_ops) |
a7d6e4ec AA |
2209 | goto skip; |
2210 | if (is_vma_temporary_stack(vma)) | |
2211 | goto skip; | |
b3b9c293 | 2212 | VM_BUG_ON(vma->vm_flags & VM_NO_THP); |
ba76149f AA |
2213 | |
2214 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2215 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
a7d6e4ec AA |
2216 | if (hstart >= hend) |
2217 | goto skip; | |
2218 | if (khugepaged_scan.address > hend) | |
2219 | goto skip; | |
ba76149f AA |
2220 | if (khugepaged_scan.address < hstart) |
2221 | khugepaged_scan.address = hstart; | |
a7d6e4ec | 2222 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); |
ba76149f AA |
2223 | |
2224 | while (khugepaged_scan.address < hend) { | |
2225 | int ret; | |
2226 | cond_resched(); | |
2227 | if (unlikely(khugepaged_test_exit(mm))) | |
2228 | goto breakouterloop; | |
2229 | ||
2230 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2231 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2232 | hend); | |
2233 | ret = khugepaged_scan_pmd(mm, vma, | |
2234 | khugepaged_scan.address, | |
2235 | hpage); | |
2236 | /* move to next address */ | |
2237 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2238 | progress += HPAGE_PMD_NR; | |
2239 | if (ret) | |
2240 | /* we released mmap_sem so break loop */ | |
2241 | goto breakouterloop_mmap_sem; | |
2242 | if (progress >= pages) | |
2243 | goto breakouterloop; | |
2244 | } | |
2245 | } | |
2246 | breakouterloop: | |
2247 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2248 | breakouterloop_mmap_sem: | |
2249 | ||
2250 | spin_lock(&khugepaged_mm_lock); | |
a7d6e4ec | 2251 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); |
ba76149f AA |
2252 | /* |
2253 | * Release the current mm_slot if this mm is about to die, or | |
2254 | * if we scanned all vmas of this mm. | |
2255 | */ | |
2256 | if (khugepaged_test_exit(mm) || !vma) { | |
2257 | /* | |
2258 | * Make sure that if mm_users is reaching zero while | |
2259 | * khugepaged runs here, khugepaged_exit will find | |
2260 | * mm_slot not pointing to the exiting mm. | |
2261 | */ | |
2262 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2263 | khugepaged_scan.mm_slot = list_entry( | |
2264 | mm_slot->mm_node.next, | |
2265 | struct mm_slot, mm_node); | |
2266 | khugepaged_scan.address = 0; | |
2267 | } else { | |
2268 | khugepaged_scan.mm_slot = NULL; | |
2269 | khugepaged_full_scans++; | |
2270 | } | |
2271 | ||
2272 | collect_mm_slot(mm_slot); | |
2273 | } | |
2274 | ||
2275 | return progress; | |
2276 | } | |
2277 | ||
2278 | static int khugepaged_has_work(void) | |
2279 | { | |
2280 | return !list_empty(&khugepaged_scan.mm_head) && | |
2281 | khugepaged_enabled(); | |
2282 | } | |
2283 | ||
2284 | static int khugepaged_wait_event(void) | |
2285 | { | |
2286 | return !list_empty(&khugepaged_scan.mm_head) || | |
2017c0bf | 2287 | kthread_should_stop(); |
ba76149f AA |
2288 | } |
2289 | ||
d516904b | 2290 | static void khugepaged_do_scan(void) |
ba76149f | 2291 | { |
d516904b | 2292 | struct page *hpage = NULL; |
ba76149f AA |
2293 | unsigned int progress = 0, pass_through_head = 0; |
2294 | unsigned int pages = khugepaged_pages_to_scan; | |
d516904b | 2295 | bool wait = true; |
ba76149f AA |
2296 | |
2297 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2298 | ||
2299 | while (progress < pages) { | |
26234f36 | 2300 | if (!khugepaged_prealloc_page(&hpage, &wait)) |
d516904b | 2301 | break; |
26234f36 | 2302 | |
420256ef | 2303 | cond_resched(); |
ba76149f | 2304 | |
878aee7d AA |
2305 | if (unlikely(kthread_should_stop() || freezing(current))) |
2306 | break; | |
2307 | ||
ba76149f AA |
2308 | spin_lock(&khugepaged_mm_lock); |
2309 | if (!khugepaged_scan.mm_slot) | |
2310 | pass_through_head++; | |
2311 | if (khugepaged_has_work() && | |
2312 | pass_through_head < 2) | |
2313 | progress += khugepaged_scan_mm_slot(pages - progress, | |
d516904b | 2314 | &hpage); |
ba76149f AA |
2315 | else |
2316 | progress = pages; | |
2317 | spin_unlock(&khugepaged_mm_lock); | |
2318 | } | |
ba76149f | 2319 | |
d516904b XG |
2320 | if (!IS_ERR_OR_NULL(hpage)) |
2321 | put_page(hpage); | |
0bbbc0b3 AA |
2322 | } |
2323 | ||
2017c0bf XG |
2324 | static void khugepaged_wait_work(void) |
2325 | { | |
2326 | try_to_freeze(); | |
2327 | ||
2328 | if (khugepaged_has_work()) { | |
2329 | if (!khugepaged_scan_sleep_millisecs) | |
2330 | return; | |
2331 | ||
2332 | wait_event_freezable_timeout(khugepaged_wait, | |
2333 | kthread_should_stop(), | |
2334 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs)); | |
2335 | return; | |
2336 | } | |
2337 | ||
2338 | if (khugepaged_enabled()) | |
2339 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2340 | } | |
2341 | ||
ba76149f AA |
2342 | static int khugepaged(void *none) |
2343 | { | |
2344 | struct mm_slot *mm_slot; | |
2345 | ||
878aee7d | 2346 | set_freezable(); |
ba76149f AA |
2347 | set_user_nice(current, 19); |
2348 | ||
b7231789 XG |
2349 | while (!kthread_should_stop()) { |
2350 | khugepaged_do_scan(); | |
2351 | khugepaged_wait_work(); | |
2352 | } | |
ba76149f AA |
2353 | |
2354 | spin_lock(&khugepaged_mm_lock); | |
2355 | mm_slot = khugepaged_scan.mm_slot; | |
2356 | khugepaged_scan.mm_slot = NULL; | |
2357 | if (mm_slot) | |
2358 | collect_mm_slot(mm_slot); | |
2359 | spin_unlock(&khugepaged_mm_lock); | |
ba76149f AA |
2360 | return 0; |
2361 | } | |
2362 | ||
71e3aac0 AA |
2363 | void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd) |
2364 | { | |
2365 | struct page *page; | |
2366 | ||
2367 | spin_lock(&mm->page_table_lock); | |
2368 | if (unlikely(!pmd_trans_huge(*pmd))) { | |
2369 | spin_unlock(&mm->page_table_lock); | |
2370 | return; | |
2371 | } | |
2372 | page = pmd_page(*pmd); | |
2373 | VM_BUG_ON(!page_count(page)); | |
2374 | get_page(page); | |
2375 | spin_unlock(&mm->page_table_lock); | |
2376 | ||
2377 | split_huge_page(page); | |
2378 | ||
2379 | put_page(page); | |
2380 | BUG_ON(pmd_trans_huge(*pmd)); | |
2381 | } | |
94fcc585 AA |
2382 | |
2383 | static void split_huge_page_address(struct mm_struct *mm, | |
2384 | unsigned long address) | |
2385 | { | |
2386 | pgd_t *pgd; | |
2387 | pud_t *pud; | |
2388 | pmd_t *pmd; | |
2389 | ||
2390 | VM_BUG_ON(!(address & ~HPAGE_PMD_MASK)); | |
2391 | ||
2392 | pgd = pgd_offset(mm, address); | |
2393 | if (!pgd_present(*pgd)) | |
2394 | return; | |
2395 | ||
2396 | pud = pud_offset(pgd, address); | |
2397 | if (!pud_present(*pud)) | |
2398 | return; | |
2399 | ||
2400 | pmd = pmd_offset(pud, address); | |
2401 | if (!pmd_present(*pmd)) | |
2402 | return; | |
2403 | /* | |
2404 | * Caller holds the mmap_sem write mode, so a huge pmd cannot | |
2405 | * materialize from under us. | |
2406 | */ | |
2407 | split_huge_page_pmd(mm, pmd); | |
2408 | } | |
2409 | ||
2410 | void __vma_adjust_trans_huge(struct vm_area_struct *vma, | |
2411 | unsigned long start, | |
2412 | unsigned long end, | |
2413 | long adjust_next) | |
2414 | { | |
2415 | /* | |
2416 | * If the new start address isn't hpage aligned and it could | |
2417 | * previously contain an hugepage: check if we need to split | |
2418 | * an huge pmd. | |
2419 | */ | |
2420 | if (start & ~HPAGE_PMD_MASK && | |
2421 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
2422 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2423 | split_huge_page_address(vma->vm_mm, start); | |
2424 | ||
2425 | /* | |
2426 | * If the new end address isn't hpage aligned and it could | |
2427 | * previously contain an hugepage: check if we need to split | |
2428 | * an huge pmd. | |
2429 | */ | |
2430 | if (end & ~HPAGE_PMD_MASK && | |
2431 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
2432 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2433 | split_huge_page_address(vma->vm_mm, end); | |
2434 | ||
2435 | /* | |
2436 | * If we're also updating the vma->vm_next->vm_start, if the new | |
2437 | * vm_next->vm_start isn't page aligned and it could previously | |
2438 | * contain an hugepage: check if we need to split an huge pmd. | |
2439 | */ | |
2440 | if (adjust_next > 0) { | |
2441 | struct vm_area_struct *next = vma->vm_next; | |
2442 | unsigned long nstart = next->vm_start; | |
2443 | nstart += adjust_next << PAGE_SHIFT; | |
2444 | if (nstart & ~HPAGE_PMD_MASK && | |
2445 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
2446 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
2447 | split_huge_page_address(next->vm_mm, nstart); | |
2448 | } | |
2449 | } |