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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()) { | |
142 | int wakeup; | |
143 | if (unlikely(!mm_slot_cache || !mm_slots_hash)) { | |
144 | err = -ENOMEM; | |
145 | goto out; | |
146 | } | |
147 | mutex_lock(&khugepaged_mutex); | |
148 | if (!khugepaged_thread) | |
149 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
150 | "khugepaged"); | |
151 | if (unlikely(IS_ERR(khugepaged_thread))) { | |
152 | printk(KERN_ERR | |
153 | "khugepaged: kthread_run(khugepaged) failed\n"); | |
154 | err = PTR_ERR(khugepaged_thread); | |
155 | khugepaged_thread = NULL; | |
156 | } | |
157 | wakeup = !list_empty(&khugepaged_scan.mm_head); | |
158 | mutex_unlock(&khugepaged_mutex); | |
159 | if (wakeup) | |
160 | wake_up_interruptible(&khugepaged_wait); | |
f000565a AA |
161 | |
162 | set_recommended_min_free_kbytes(); | |
ba76149f AA |
163 | } else |
164 | /* wakeup to exit */ | |
165 | wake_up_interruptible(&khugepaged_wait); | |
166 | out: | |
167 | return err; | |
168 | } | |
71e3aac0 AA |
169 | |
170 | #ifdef CONFIG_SYSFS | |
ba76149f | 171 | |
71e3aac0 AA |
172 | static ssize_t double_flag_show(struct kobject *kobj, |
173 | struct kobj_attribute *attr, char *buf, | |
174 | enum transparent_hugepage_flag enabled, | |
175 | enum transparent_hugepage_flag req_madv) | |
176 | { | |
177 | if (test_bit(enabled, &transparent_hugepage_flags)) { | |
178 | VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags)); | |
179 | return sprintf(buf, "[always] madvise never\n"); | |
180 | } else if (test_bit(req_madv, &transparent_hugepage_flags)) | |
181 | return sprintf(buf, "always [madvise] never\n"); | |
182 | else | |
183 | return sprintf(buf, "always madvise [never]\n"); | |
184 | } | |
185 | static ssize_t double_flag_store(struct kobject *kobj, | |
186 | struct kobj_attribute *attr, | |
187 | const char *buf, size_t count, | |
188 | enum transparent_hugepage_flag enabled, | |
189 | enum transparent_hugepage_flag req_madv) | |
190 | { | |
191 | if (!memcmp("always", buf, | |
192 | min(sizeof("always")-1, count))) { | |
193 | set_bit(enabled, &transparent_hugepage_flags); | |
194 | clear_bit(req_madv, &transparent_hugepage_flags); | |
195 | } else if (!memcmp("madvise", buf, | |
196 | min(sizeof("madvise")-1, count))) { | |
197 | clear_bit(enabled, &transparent_hugepage_flags); | |
198 | set_bit(req_madv, &transparent_hugepage_flags); | |
199 | } else if (!memcmp("never", buf, | |
200 | min(sizeof("never")-1, count))) { | |
201 | clear_bit(enabled, &transparent_hugepage_flags); | |
202 | clear_bit(req_madv, &transparent_hugepage_flags); | |
203 | } else | |
204 | return -EINVAL; | |
205 | ||
206 | return count; | |
207 | } | |
208 | ||
209 | static ssize_t enabled_show(struct kobject *kobj, | |
210 | struct kobj_attribute *attr, char *buf) | |
211 | { | |
212 | return double_flag_show(kobj, attr, buf, | |
213 | TRANSPARENT_HUGEPAGE_FLAG, | |
214 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
215 | } | |
216 | static ssize_t enabled_store(struct kobject *kobj, | |
217 | struct kobj_attribute *attr, | |
218 | const char *buf, size_t count) | |
219 | { | |
ba76149f AA |
220 | ssize_t ret; |
221 | ||
222 | ret = double_flag_store(kobj, attr, buf, count, | |
223 | TRANSPARENT_HUGEPAGE_FLAG, | |
224 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
225 | ||
226 | if (ret > 0) { | |
227 | int err = start_khugepaged(); | |
228 | if (err) | |
229 | ret = err; | |
230 | } | |
231 | ||
f000565a AA |
232 | if (ret > 0 && |
233 | (test_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
234 | &transparent_hugepage_flags) || | |
235 | test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
236 | &transparent_hugepage_flags))) | |
237 | set_recommended_min_free_kbytes(); | |
238 | ||
ba76149f | 239 | return ret; |
71e3aac0 AA |
240 | } |
241 | static struct kobj_attribute enabled_attr = | |
242 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
243 | ||
244 | static ssize_t single_flag_show(struct kobject *kobj, | |
245 | struct kobj_attribute *attr, char *buf, | |
246 | enum transparent_hugepage_flag flag) | |
247 | { | |
e27e6151 BH |
248 | return sprintf(buf, "%d\n", |
249 | !!test_bit(flag, &transparent_hugepage_flags)); | |
71e3aac0 | 250 | } |
e27e6151 | 251 | |
71e3aac0 AA |
252 | static ssize_t single_flag_store(struct kobject *kobj, |
253 | struct kobj_attribute *attr, | |
254 | const char *buf, size_t count, | |
255 | enum transparent_hugepage_flag flag) | |
256 | { | |
e27e6151 BH |
257 | unsigned long value; |
258 | int ret; | |
259 | ||
260 | ret = kstrtoul(buf, 10, &value); | |
261 | if (ret < 0) | |
262 | return ret; | |
263 | if (value > 1) | |
264 | return -EINVAL; | |
265 | ||
266 | if (value) | |
71e3aac0 | 267 | set_bit(flag, &transparent_hugepage_flags); |
e27e6151 | 268 | else |
71e3aac0 | 269 | clear_bit(flag, &transparent_hugepage_flags); |
71e3aac0 AA |
270 | |
271 | return count; | |
272 | } | |
273 | ||
274 | /* | |
275 | * Currently defrag only disables __GFP_NOWAIT for allocation. A blind | |
276 | * __GFP_REPEAT is too aggressive, it's never worth swapping tons of | |
277 | * memory just to allocate one more hugepage. | |
278 | */ | |
279 | static ssize_t defrag_show(struct kobject *kobj, | |
280 | struct kobj_attribute *attr, char *buf) | |
281 | { | |
282 | return double_flag_show(kobj, attr, buf, | |
283 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
284 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
285 | } | |
286 | static ssize_t defrag_store(struct kobject *kobj, | |
287 | struct kobj_attribute *attr, | |
288 | const char *buf, size_t count) | |
289 | { | |
290 | return double_flag_store(kobj, attr, buf, count, | |
291 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
292 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
293 | } | |
294 | static struct kobj_attribute defrag_attr = | |
295 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
296 | ||
297 | #ifdef CONFIG_DEBUG_VM | |
298 | static ssize_t debug_cow_show(struct kobject *kobj, | |
299 | struct kobj_attribute *attr, char *buf) | |
300 | { | |
301 | return single_flag_show(kobj, attr, buf, | |
302 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
303 | } | |
304 | static ssize_t debug_cow_store(struct kobject *kobj, | |
305 | struct kobj_attribute *attr, | |
306 | const char *buf, size_t count) | |
307 | { | |
308 | return single_flag_store(kobj, attr, buf, count, | |
309 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
310 | } | |
311 | static struct kobj_attribute debug_cow_attr = | |
312 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
313 | #endif /* CONFIG_DEBUG_VM */ | |
314 | ||
315 | static struct attribute *hugepage_attr[] = { | |
316 | &enabled_attr.attr, | |
317 | &defrag_attr.attr, | |
318 | #ifdef CONFIG_DEBUG_VM | |
319 | &debug_cow_attr.attr, | |
320 | #endif | |
321 | NULL, | |
322 | }; | |
323 | ||
324 | static struct attribute_group hugepage_attr_group = { | |
325 | .attrs = hugepage_attr, | |
ba76149f AA |
326 | }; |
327 | ||
328 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, | |
329 | struct kobj_attribute *attr, | |
330 | char *buf) | |
331 | { | |
332 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
333 | } | |
334 | ||
335 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
336 | struct kobj_attribute *attr, | |
337 | const char *buf, size_t count) | |
338 | { | |
339 | unsigned long msecs; | |
340 | int err; | |
341 | ||
342 | err = strict_strtoul(buf, 10, &msecs); | |
343 | if (err || msecs > UINT_MAX) | |
344 | return -EINVAL; | |
345 | ||
346 | khugepaged_scan_sleep_millisecs = msecs; | |
347 | wake_up_interruptible(&khugepaged_wait); | |
348 | ||
349 | return count; | |
350 | } | |
351 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
352 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
353 | scan_sleep_millisecs_store); | |
354 | ||
355 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
356 | struct kobj_attribute *attr, | |
357 | char *buf) | |
358 | { | |
359 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
360 | } | |
361 | ||
362 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
363 | struct kobj_attribute *attr, | |
364 | const char *buf, size_t count) | |
365 | { | |
366 | unsigned long msecs; | |
367 | int err; | |
368 | ||
369 | err = strict_strtoul(buf, 10, &msecs); | |
370 | if (err || msecs > UINT_MAX) | |
371 | return -EINVAL; | |
372 | ||
373 | khugepaged_alloc_sleep_millisecs = msecs; | |
374 | wake_up_interruptible(&khugepaged_wait); | |
375 | ||
376 | return count; | |
377 | } | |
378 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
379 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
380 | alloc_sleep_millisecs_store); | |
381 | ||
382 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
383 | struct kobj_attribute *attr, | |
384 | char *buf) | |
385 | { | |
386 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
387 | } | |
388 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
389 | struct kobj_attribute *attr, | |
390 | const char *buf, size_t count) | |
391 | { | |
392 | int err; | |
393 | unsigned long pages; | |
394 | ||
395 | err = strict_strtoul(buf, 10, &pages); | |
396 | if (err || !pages || pages > UINT_MAX) | |
397 | return -EINVAL; | |
398 | ||
399 | khugepaged_pages_to_scan = pages; | |
400 | ||
401 | return count; | |
402 | } | |
403 | static struct kobj_attribute pages_to_scan_attr = | |
404 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
405 | pages_to_scan_store); | |
406 | ||
407 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
408 | struct kobj_attribute *attr, | |
409 | char *buf) | |
410 | { | |
411 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
412 | } | |
413 | static struct kobj_attribute pages_collapsed_attr = | |
414 | __ATTR_RO(pages_collapsed); | |
415 | ||
416 | static ssize_t full_scans_show(struct kobject *kobj, | |
417 | struct kobj_attribute *attr, | |
418 | char *buf) | |
419 | { | |
420 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
421 | } | |
422 | static struct kobj_attribute full_scans_attr = | |
423 | __ATTR_RO(full_scans); | |
424 | ||
425 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
426 | struct kobj_attribute *attr, char *buf) | |
427 | { | |
428 | return single_flag_show(kobj, attr, buf, | |
429 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
430 | } | |
431 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
432 | struct kobj_attribute *attr, | |
433 | const char *buf, size_t count) | |
434 | { | |
435 | return single_flag_store(kobj, attr, buf, count, | |
436 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
437 | } | |
438 | static struct kobj_attribute khugepaged_defrag_attr = | |
439 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
440 | khugepaged_defrag_store); | |
441 | ||
442 | /* | |
443 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
444 | * any unmapped ptes in turn potentially increasing the memory | |
445 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
446 | * reduce the available free memory in the system as it | |
447 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
448 | * free memory in the system during the khugepaged scan. | |
449 | */ | |
450 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
451 | struct kobj_attribute *attr, | |
452 | char *buf) | |
453 | { | |
454 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
455 | } | |
456 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
457 | struct kobj_attribute *attr, | |
458 | const char *buf, size_t count) | |
459 | { | |
460 | int err; | |
461 | unsigned long max_ptes_none; | |
462 | ||
463 | err = strict_strtoul(buf, 10, &max_ptes_none); | |
464 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
465 | return -EINVAL; | |
466 | ||
467 | khugepaged_max_ptes_none = max_ptes_none; | |
468 | ||
469 | return count; | |
470 | } | |
471 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
472 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
473 | khugepaged_max_ptes_none_store); | |
474 | ||
475 | static struct attribute *khugepaged_attr[] = { | |
476 | &khugepaged_defrag_attr.attr, | |
477 | &khugepaged_max_ptes_none_attr.attr, | |
478 | &pages_to_scan_attr.attr, | |
479 | &pages_collapsed_attr.attr, | |
480 | &full_scans_attr.attr, | |
481 | &scan_sleep_millisecs_attr.attr, | |
482 | &alloc_sleep_millisecs_attr.attr, | |
483 | NULL, | |
484 | }; | |
485 | ||
486 | static struct attribute_group khugepaged_attr_group = { | |
487 | .attrs = khugepaged_attr, | |
488 | .name = "khugepaged", | |
71e3aac0 | 489 | }; |
71e3aac0 | 490 | |
569e5590 | 491 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
71e3aac0 | 492 | { |
71e3aac0 AA |
493 | int err; |
494 | ||
569e5590 SL |
495 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); |
496 | if (unlikely(!*hugepage_kobj)) { | |
ba76149f | 497 | printk(KERN_ERR "hugepage: failed kobject create\n"); |
569e5590 | 498 | return -ENOMEM; |
ba76149f AA |
499 | } |
500 | ||
569e5590 | 501 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); |
ba76149f AA |
502 | if (err) { |
503 | printk(KERN_ERR "hugepage: failed register hugeage group\n"); | |
569e5590 | 504 | goto delete_obj; |
ba76149f AA |
505 | } |
506 | ||
569e5590 | 507 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); |
ba76149f AA |
508 | if (err) { |
509 | printk(KERN_ERR "hugepage: failed register hugeage group\n"); | |
569e5590 | 510 | goto remove_hp_group; |
ba76149f | 511 | } |
569e5590 SL |
512 | |
513 | return 0; | |
514 | ||
515 | remove_hp_group: | |
516 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
517 | delete_obj: | |
518 | kobject_put(*hugepage_kobj); | |
519 | return err; | |
520 | } | |
521 | ||
522 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
523 | { | |
524 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
525 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
526 | kobject_put(hugepage_kobj); | |
527 | } | |
528 | #else | |
529 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
530 | { | |
531 | return 0; | |
532 | } | |
533 | ||
534 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
535 | { | |
536 | } | |
537 | #endif /* CONFIG_SYSFS */ | |
538 | ||
539 | static int __init hugepage_init(void) | |
540 | { | |
541 | int err; | |
542 | struct kobject *hugepage_kobj; | |
543 | ||
544 | if (!has_transparent_hugepage()) { | |
545 | transparent_hugepage_flags = 0; | |
546 | return -EINVAL; | |
547 | } | |
548 | ||
549 | err = hugepage_init_sysfs(&hugepage_kobj); | |
550 | if (err) | |
551 | return err; | |
ba76149f AA |
552 | |
553 | err = khugepaged_slab_init(); | |
554 | if (err) | |
555 | goto out; | |
556 | ||
557 | err = mm_slots_hash_init(); | |
558 | if (err) { | |
559 | khugepaged_slab_free(); | |
560 | goto out; | |
561 | } | |
562 | ||
97562cd2 RR |
563 | /* |
564 | * By default disable transparent hugepages on smaller systems, | |
565 | * where the extra memory used could hurt more than TLB overhead | |
566 | * is likely to save. The admin can still enable it through /sys. | |
567 | */ | |
568 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) | |
569 | transparent_hugepage_flags = 0; | |
570 | ||
ba76149f AA |
571 | start_khugepaged(); |
572 | ||
f000565a AA |
573 | set_recommended_min_free_kbytes(); |
574 | ||
569e5590 | 575 | return 0; |
ba76149f | 576 | out: |
569e5590 | 577 | hugepage_exit_sysfs(hugepage_kobj); |
ba76149f | 578 | return err; |
71e3aac0 AA |
579 | } |
580 | module_init(hugepage_init) | |
581 | ||
582 | static int __init setup_transparent_hugepage(char *str) | |
583 | { | |
584 | int ret = 0; | |
585 | if (!str) | |
586 | goto out; | |
587 | if (!strcmp(str, "always")) { | |
588 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
589 | &transparent_hugepage_flags); | |
590 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
591 | &transparent_hugepage_flags); | |
592 | ret = 1; | |
593 | } else if (!strcmp(str, "madvise")) { | |
594 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
595 | &transparent_hugepage_flags); | |
596 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
597 | &transparent_hugepage_flags); | |
598 | ret = 1; | |
599 | } else if (!strcmp(str, "never")) { | |
600 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
601 | &transparent_hugepage_flags); | |
602 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
603 | &transparent_hugepage_flags); | |
604 | ret = 1; | |
605 | } | |
606 | out: | |
607 | if (!ret) | |
608 | printk(KERN_WARNING | |
609 | "transparent_hugepage= cannot parse, ignored\n"); | |
610 | return ret; | |
611 | } | |
612 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
613 | ||
614 | static void prepare_pmd_huge_pte(pgtable_t pgtable, | |
615 | struct mm_struct *mm) | |
616 | { | |
617 | assert_spin_locked(&mm->page_table_lock); | |
618 | ||
619 | /* FIFO */ | |
620 | if (!mm->pmd_huge_pte) | |
621 | INIT_LIST_HEAD(&pgtable->lru); | |
622 | else | |
623 | list_add(&pgtable->lru, &mm->pmd_huge_pte->lru); | |
624 | mm->pmd_huge_pte = pgtable; | |
625 | } | |
626 | ||
627 | static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) | |
628 | { | |
629 | if (likely(vma->vm_flags & VM_WRITE)) | |
630 | pmd = pmd_mkwrite(pmd); | |
631 | return pmd; | |
632 | } | |
633 | ||
634 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, | |
635 | struct vm_area_struct *vma, | |
636 | unsigned long haddr, pmd_t *pmd, | |
637 | struct page *page) | |
638 | { | |
71e3aac0 AA |
639 | pgtable_t pgtable; |
640 | ||
641 | VM_BUG_ON(!PageCompound(page)); | |
642 | pgtable = pte_alloc_one(mm, haddr); | |
edad9d2c | 643 | if (unlikely(!pgtable)) |
71e3aac0 | 644 | return VM_FAULT_OOM; |
71e3aac0 AA |
645 | |
646 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
647 | __SetPageUptodate(page); | |
648 | ||
649 | spin_lock(&mm->page_table_lock); | |
650 | if (unlikely(!pmd_none(*pmd))) { | |
651 | spin_unlock(&mm->page_table_lock); | |
b9bbfbe3 | 652 | mem_cgroup_uncharge_page(page); |
71e3aac0 AA |
653 | put_page(page); |
654 | pte_free(mm, pgtable); | |
655 | } else { | |
656 | pmd_t entry; | |
657 | entry = mk_pmd(page, vma->vm_page_prot); | |
658 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
659 | entry = pmd_mkhuge(entry); | |
660 | /* | |
661 | * The spinlocking to take the lru_lock inside | |
662 | * page_add_new_anon_rmap() acts as a full memory | |
663 | * barrier to be sure clear_huge_page writes become | |
664 | * visible after the set_pmd_at() write. | |
665 | */ | |
666 | page_add_new_anon_rmap(page, vma, haddr); | |
667 | set_pmd_at(mm, haddr, pmd, entry); | |
668 | prepare_pmd_huge_pte(pgtable, mm); | |
669 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
1c641e84 | 670 | mm->nr_ptes++; |
71e3aac0 AA |
671 | spin_unlock(&mm->page_table_lock); |
672 | } | |
673 | ||
aa2e878e | 674 | return 0; |
71e3aac0 AA |
675 | } |
676 | ||
cc5d462f | 677 | static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp) |
0bbbc0b3 | 678 | { |
cc5d462f | 679 | return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp; |
0bbbc0b3 AA |
680 | } |
681 | ||
682 | static inline struct page *alloc_hugepage_vma(int defrag, | |
683 | struct vm_area_struct *vma, | |
cc5d462f AK |
684 | unsigned long haddr, int nd, |
685 | gfp_t extra_gfp) | |
0bbbc0b3 | 686 | { |
cc5d462f | 687 | return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp), |
5c4b4be3 | 688 | HPAGE_PMD_ORDER, vma, haddr, nd); |
0bbbc0b3 AA |
689 | } |
690 | ||
691 | #ifndef CONFIG_NUMA | |
71e3aac0 AA |
692 | static inline struct page *alloc_hugepage(int defrag) |
693 | { | |
cc5d462f | 694 | return alloc_pages(alloc_hugepage_gfpmask(defrag, 0), |
71e3aac0 AA |
695 | HPAGE_PMD_ORDER); |
696 | } | |
0bbbc0b3 | 697 | #endif |
71e3aac0 AA |
698 | |
699 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
700 | unsigned long address, pmd_t *pmd, | |
701 | unsigned int flags) | |
702 | { | |
703 | struct page *page; | |
704 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
705 | pte_t *pte; | |
706 | ||
707 | if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) { | |
708 | if (unlikely(anon_vma_prepare(vma))) | |
709 | return VM_FAULT_OOM; | |
ba76149f AA |
710 | if (unlikely(khugepaged_enter(vma))) |
711 | return VM_FAULT_OOM; | |
0bbbc0b3 | 712 | page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
cc5d462f | 713 | vma, haddr, numa_node_id(), 0); |
81ab4201 AK |
714 | if (unlikely(!page)) { |
715 | count_vm_event(THP_FAULT_FALLBACK); | |
71e3aac0 | 716 | goto out; |
81ab4201 AK |
717 | } |
718 | count_vm_event(THP_FAULT_ALLOC); | |
b9bbfbe3 AA |
719 | if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) { |
720 | put_page(page); | |
721 | goto out; | |
722 | } | |
edad9d2c DR |
723 | if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, |
724 | page))) { | |
725 | mem_cgroup_uncharge_page(page); | |
726 | put_page(page); | |
727 | goto out; | |
728 | } | |
71e3aac0 | 729 | |
edad9d2c | 730 | return 0; |
71e3aac0 AA |
731 | } |
732 | out: | |
733 | /* | |
734 | * Use __pte_alloc instead of pte_alloc_map, because we can't | |
735 | * run pte_offset_map on the pmd, if an huge pmd could | |
736 | * materialize from under us from a different thread. | |
737 | */ | |
738 | if (unlikely(__pte_alloc(mm, vma, pmd, address))) | |
739 | return VM_FAULT_OOM; | |
740 | /* if an huge pmd materialized from under us just retry later */ | |
741 | if (unlikely(pmd_trans_huge(*pmd))) | |
742 | return 0; | |
743 | /* | |
744 | * A regular pmd is established and it can't morph into a huge pmd | |
745 | * from under us anymore at this point because we hold the mmap_sem | |
746 | * read mode and khugepaged takes it in write mode. So now it's | |
747 | * safe to run pte_offset_map(). | |
748 | */ | |
749 | pte = pte_offset_map(pmd, address); | |
750 | return handle_pte_fault(mm, vma, address, pte, pmd, flags); | |
751 | } | |
752 | ||
753 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, | |
754 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
755 | struct vm_area_struct *vma) | |
756 | { | |
757 | struct page *src_page; | |
758 | pmd_t pmd; | |
759 | pgtable_t pgtable; | |
760 | int ret; | |
761 | ||
762 | ret = -ENOMEM; | |
763 | pgtable = pte_alloc_one(dst_mm, addr); | |
764 | if (unlikely(!pgtable)) | |
765 | goto out; | |
766 | ||
767 | spin_lock(&dst_mm->page_table_lock); | |
768 | spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING); | |
769 | ||
770 | ret = -EAGAIN; | |
771 | pmd = *src_pmd; | |
772 | if (unlikely(!pmd_trans_huge(pmd))) { | |
773 | pte_free(dst_mm, pgtable); | |
774 | goto out_unlock; | |
775 | } | |
776 | if (unlikely(pmd_trans_splitting(pmd))) { | |
777 | /* split huge page running from under us */ | |
778 | spin_unlock(&src_mm->page_table_lock); | |
779 | spin_unlock(&dst_mm->page_table_lock); | |
780 | pte_free(dst_mm, pgtable); | |
781 | ||
782 | wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */ | |
783 | goto out; | |
784 | } | |
785 | src_page = pmd_page(pmd); | |
786 | VM_BUG_ON(!PageHead(src_page)); | |
787 | get_page(src_page); | |
788 | page_dup_rmap(src_page); | |
789 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
790 | ||
791 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
792 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
793 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
794 | prepare_pmd_huge_pte(pgtable, dst_mm); | |
1c641e84 | 795 | dst_mm->nr_ptes++; |
71e3aac0 AA |
796 | |
797 | ret = 0; | |
798 | out_unlock: | |
799 | spin_unlock(&src_mm->page_table_lock); | |
800 | spin_unlock(&dst_mm->page_table_lock); | |
801 | out: | |
802 | return ret; | |
803 | } | |
804 | ||
805 | /* no "address" argument so destroys page coloring of some arch */ | |
806 | pgtable_t get_pmd_huge_pte(struct mm_struct *mm) | |
807 | { | |
808 | pgtable_t pgtable; | |
809 | ||
810 | assert_spin_locked(&mm->page_table_lock); | |
811 | ||
812 | /* FIFO */ | |
813 | pgtable = mm->pmd_huge_pte; | |
814 | if (list_empty(&pgtable->lru)) | |
815 | mm->pmd_huge_pte = NULL; | |
816 | else { | |
817 | mm->pmd_huge_pte = list_entry(pgtable->lru.next, | |
818 | struct page, lru); | |
819 | list_del(&pgtable->lru); | |
820 | } | |
821 | return pgtable; | |
822 | } | |
823 | ||
824 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, | |
825 | struct vm_area_struct *vma, | |
826 | unsigned long address, | |
827 | pmd_t *pmd, pmd_t orig_pmd, | |
828 | struct page *page, | |
829 | unsigned long haddr) | |
830 | { | |
831 | pgtable_t pgtable; | |
832 | pmd_t _pmd; | |
833 | int ret = 0, i; | |
834 | struct page **pages; | |
835 | ||
836 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
837 | GFP_KERNEL); | |
838 | if (unlikely(!pages)) { | |
839 | ret |= VM_FAULT_OOM; | |
840 | goto out; | |
841 | } | |
842 | ||
843 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
cc5d462f AK |
844 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE | |
845 | __GFP_OTHER_NODE, | |
19ee151e | 846 | vma, address, page_to_nid(page)); |
b9bbfbe3 AA |
847 | if (unlikely(!pages[i] || |
848 | mem_cgroup_newpage_charge(pages[i], mm, | |
849 | GFP_KERNEL))) { | |
850 | if (pages[i]) | |
71e3aac0 | 851 | put_page(pages[i]); |
b9bbfbe3 AA |
852 | mem_cgroup_uncharge_start(); |
853 | while (--i >= 0) { | |
854 | mem_cgroup_uncharge_page(pages[i]); | |
855 | put_page(pages[i]); | |
856 | } | |
857 | mem_cgroup_uncharge_end(); | |
71e3aac0 AA |
858 | kfree(pages); |
859 | ret |= VM_FAULT_OOM; | |
860 | goto out; | |
861 | } | |
862 | } | |
863 | ||
864 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
865 | copy_user_highpage(pages[i], page + i, | |
0089e485 | 866 | haddr + PAGE_SIZE * i, vma); |
71e3aac0 AA |
867 | __SetPageUptodate(pages[i]); |
868 | cond_resched(); | |
869 | } | |
870 | ||
871 | spin_lock(&mm->page_table_lock); | |
872 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
873 | goto out_free_pages; | |
874 | VM_BUG_ON(!PageHead(page)); | |
875 | ||
876 | pmdp_clear_flush_notify(vma, haddr, pmd); | |
877 | /* leave pmd empty until pte is filled */ | |
878 | ||
879 | pgtable = get_pmd_huge_pte(mm); | |
880 | pmd_populate(mm, &_pmd, pgtable); | |
881 | ||
882 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
883 | pte_t *pte, entry; | |
884 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
885 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
886 | page_add_new_anon_rmap(pages[i], vma, haddr); | |
887 | pte = pte_offset_map(&_pmd, haddr); | |
888 | VM_BUG_ON(!pte_none(*pte)); | |
889 | set_pte_at(mm, haddr, pte, entry); | |
890 | pte_unmap(pte); | |
891 | } | |
892 | kfree(pages); | |
893 | ||
71e3aac0 AA |
894 | smp_wmb(); /* make pte visible before pmd */ |
895 | pmd_populate(mm, pmd, pgtable); | |
896 | page_remove_rmap(page); | |
897 | spin_unlock(&mm->page_table_lock); | |
898 | ||
899 | ret |= VM_FAULT_WRITE; | |
900 | put_page(page); | |
901 | ||
902 | out: | |
903 | return ret; | |
904 | ||
905 | out_free_pages: | |
906 | spin_unlock(&mm->page_table_lock); | |
b9bbfbe3 AA |
907 | mem_cgroup_uncharge_start(); |
908 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
909 | mem_cgroup_uncharge_page(pages[i]); | |
71e3aac0 | 910 | put_page(pages[i]); |
b9bbfbe3 AA |
911 | } |
912 | mem_cgroup_uncharge_end(); | |
71e3aac0 AA |
913 | kfree(pages); |
914 | goto out; | |
915 | } | |
916 | ||
917 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
918 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) | |
919 | { | |
920 | int ret = 0; | |
921 | struct page *page, *new_page; | |
922 | unsigned long haddr; | |
923 | ||
924 | VM_BUG_ON(!vma->anon_vma); | |
925 | spin_lock(&mm->page_table_lock); | |
926 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
927 | goto out_unlock; | |
928 | ||
929 | page = pmd_page(orig_pmd); | |
930 | VM_BUG_ON(!PageCompound(page) || !PageHead(page)); | |
931 | haddr = address & HPAGE_PMD_MASK; | |
932 | if (page_mapcount(page) == 1) { | |
933 | pmd_t entry; | |
934 | entry = pmd_mkyoung(orig_pmd); | |
935 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
936 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) | |
937 | update_mmu_cache(vma, address, entry); | |
938 | ret |= VM_FAULT_WRITE; | |
939 | goto out_unlock; | |
940 | } | |
941 | get_page(page); | |
942 | spin_unlock(&mm->page_table_lock); | |
943 | ||
944 | if (transparent_hugepage_enabled(vma) && | |
945 | !transparent_hugepage_debug_cow()) | |
0bbbc0b3 | 946 | new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
cc5d462f | 947 | vma, haddr, numa_node_id(), 0); |
71e3aac0 AA |
948 | else |
949 | new_page = NULL; | |
950 | ||
951 | if (unlikely(!new_page)) { | |
81ab4201 | 952 | count_vm_event(THP_FAULT_FALLBACK); |
71e3aac0 AA |
953 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, |
954 | pmd, orig_pmd, page, haddr); | |
1f1d06c3 DR |
955 | if (ret & VM_FAULT_OOM) |
956 | split_huge_page(page); | |
71e3aac0 AA |
957 | put_page(page); |
958 | goto out; | |
959 | } | |
81ab4201 | 960 | count_vm_event(THP_FAULT_ALLOC); |
71e3aac0 | 961 | |
b9bbfbe3 AA |
962 | if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) { |
963 | put_page(new_page); | |
1f1d06c3 | 964 | split_huge_page(page); |
b9bbfbe3 AA |
965 | put_page(page); |
966 | ret |= VM_FAULT_OOM; | |
967 | goto out; | |
968 | } | |
969 | ||
71e3aac0 AA |
970 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); |
971 | __SetPageUptodate(new_page); | |
972 | ||
973 | spin_lock(&mm->page_table_lock); | |
974 | put_page(page); | |
b9bbfbe3 AA |
975 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { |
976 | mem_cgroup_uncharge_page(new_page); | |
71e3aac0 | 977 | put_page(new_page); |
b9bbfbe3 | 978 | } else { |
71e3aac0 AA |
979 | pmd_t entry; |
980 | VM_BUG_ON(!PageHead(page)); | |
981 | entry = mk_pmd(new_page, vma->vm_page_prot); | |
982 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
983 | entry = pmd_mkhuge(entry); | |
984 | pmdp_clear_flush_notify(vma, haddr, pmd); | |
985 | page_add_new_anon_rmap(new_page, vma, haddr); | |
986 | set_pmd_at(mm, haddr, pmd, entry); | |
987 | update_mmu_cache(vma, address, entry); | |
988 | page_remove_rmap(page); | |
989 | put_page(page); | |
990 | ret |= VM_FAULT_WRITE; | |
991 | } | |
992 | out_unlock: | |
993 | spin_unlock(&mm->page_table_lock); | |
994 | out: | |
995 | return ret; | |
996 | } | |
997 | ||
998 | struct page *follow_trans_huge_pmd(struct mm_struct *mm, | |
999 | unsigned long addr, | |
1000 | pmd_t *pmd, | |
1001 | unsigned int flags) | |
1002 | { | |
1003 | struct page *page = NULL; | |
1004 | ||
1005 | assert_spin_locked(&mm->page_table_lock); | |
1006 | ||
1007 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1008 | goto out; | |
1009 | ||
1010 | page = pmd_page(*pmd); | |
1011 | VM_BUG_ON(!PageHead(page)); | |
1012 | if (flags & FOLL_TOUCH) { | |
1013 | pmd_t _pmd; | |
1014 | /* | |
1015 | * We should set the dirty bit only for FOLL_WRITE but | |
1016 | * for now the dirty bit in the pmd is meaningless. | |
1017 | * And if the dirty bit will become meaningful and | |
1018 | * we'll only set it with FOLL_WRITE, an atomic | |
1019 | * set_bit will be required on the pmd to set the | |
1020 | * young bit, instead of the current set_pmd_at. | |
1021 | */ | |
1022 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
1023 | set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd); | |
1024 | } | |
1025 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; | |
1026 | VM_BUG_ON(!PageCompound(page)); | |
1027 | if (flags & FOLL_GET) | |
70b50f94 | 1028 | get_page_foll(page); |
71e3aac0 AA |
1029 | |
1030 | out: | |
1031 | return page; | |
1032 | } | |
1033 | ||
1034 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, | |
f21760b1 | 1035 | pmd_t *pmd, unsigned long addr) |
71e3aac0 AA |
1036 | { |
1037 | int ret = 0; | |
1038 | ||
025c5b24 NH |
1039 | if (__pmd_trans_huge_lock(pmd, vma) == 1) { |
1040 | struct page *page; | |
1041 | pgtable_t pgtable; | |
1042 | pgtable = get_pmd_huge_pte(tlb->mm); | |
1043 | page = pmd_page(*pmd); | |
1044 | pmd_clear(pmd); | |
1045 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1046 | page_remove_rmap(page); | |
1047 | VM_BUG_ON(page_mapcount(page) < 0); | |
1048 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1049 | VM_BUG_ON(!PageHead(page)); | |
1050 | tlb->mm->nr_ptes--; | |
71e3aac0 | 1051 | spin_unlock(&tlb->mm->page_table_lock); |
025c5b24 NH |
1052 | tlb_remove_page(tlb, page); |
1053 | pte_free(tlb->mm, pgtable); | |
1054 | ret = 1; | |
1055 | } | |
71e3aac0 AA |
1056 | return ret; |
1057 | } | |
1058 | ||
0ca1634d JW |
1059 | int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
1060 | unsigned long addr, unsigned long end, | |
1061 | unsigned char *vec) | |
1062 | { | |
1063 | int ret = 0; | |
1064 | ||
025c5b24 NH |
1065 | if (__pmd_trans_huge_lock(pmd, vma) == 1) { |
1066 | /* | |
1067 | * All logical pages in the range are present | |
1068 | * if backed by a huge page. | |
1069 | */ | |
0ca1634d | 1070 | spin_unlock(&vma->vm_mm->page_table_lock); |
025c5b24 NH |
1071 | memset(vec, 1, (end - addr) >> PAGE_SHIFT); |
1072 | ret = 1; | |
1073 | } | |
0ca1634d JW |
1074 | |
1075 | return ret; | |
1076 | } | |
1077 | ||
37a1c49a AA |
1078 | int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, |
1079 | unsigned long old_addr, | |
1080 | unsigned long new_addr, unsigned long old_end, | |
1081 | pmd_t *old_pmd, pmd_t *new_pmd) | |
1082 | { | |
1083 | int ret = 0; | |
1084 | pmd_t pmd; | |
1085 | ||
1086 | struct mm_struct *mm = vma->vm_mm; | |
1087 | ||
1088 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1089 | (new_addr & ~HPAGE_PMD_MASK) || | |
1090 | old_end - old_addr < HPAGE_PMD_SIZE || | |
1091 | (new_vma->vm_flags & VM_NOHUGEPAGE)) | |
1092 | goto out; | |
1093 | ||
1094 | /* | |
1095 | * The destination pmd shouldn't be established, free_pgtables() | |
1096 | * should have release it. | |
1097 | */ | |
1098 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1099 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
1100 | goto out; | |
1101 | } | |
1102 | ||
025c5b24 NH |
1103 | ret = __pmd_trans_huge_lock(old_pmd, vma); |
1104 | if (ret == 1) { | |
1105 | pmd = pmdp_get_and_clear(mm, old_addr, old_pmd); | |
1106 | VM_BUG_ON(!pmd_none(*new_pmd)); | |
1107 | set_pmd_at(mm, new_addr, new_pmd, pmd); | |
37a1c49a AA |
1108 | spin_unlock(&mm->page_table_lock); |
1109 | } | |
1110 | out: | |
1111 | return ret; | |
1112 | } | |
1113 | ||
cd7548ab JW |
1114 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
1115 | unsigned long addr, pgprot_t newprot) | |
1116 | { | |
1117 | struct mm_struct *mm = vma->vm_mm; | |
1118 | int ret = 0; | |
1119 | ||
025c5b24 NH |
1120 | if (__pmd_trans_huge_lock(pmd, vma) == 1) { |
1121 | pmd_t entry; | |
1122 | entry = pmdp_get_and_clear(mm, addr, pmd); | |
1123 | entry = pmd_modify(entry, newprot); | |
1124 | set_pmd_at(mm, addr, pmd, entry); | |
1125 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1126 | ret = 1; | |
1127 | } | |
1128 | ||
1129 | return ret; | |
1130 | } | |
1131 | ||
1132 | /* | |
1133 | * Returns 1 if a given pmd maps a stable (not under splitting) thp. | |
1134 | * Returns -1 if it maps a thp under splitting. Returns 0 otherwise. | |
1135 | * | |
1136 | * Note that if it returns 1, this routine returns without unlocking page | |
1137 | * table locks. So callers must unlock them. | |
1138 | */ | |
1139 | int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) | |
1140 | { | |
1141 | spin_lock(&vma->vm_mm->page_table_lock); | |
cd7548ab JW |
1142 | if (likely(pmd_trans_huge(*pmd))) { |
1143 | if (unlikely(pmd_trans_splitting(*pmd))) { | |
025c5b24 | 1144 | spin_unlock(&vma->vm_mm->page_table_lock); |
cd7548ab | 1145 | wait_split_huge_page(vma->anon_vma, pmd); |
025c5b24 | 1146 | return -1; |
cd7548ab | 1147 | } else { |
025c5b24 NH |
1148 | /* Thp mapped by 'pmd' is stable, so we can |
1149 | * handle it as it is. */ | |
1150 | return 1; | |
cd7548ab | 1151 | } |
025c5b24 NH |
1152 | } |
1153 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1154 | return 0; | |
cd7548ab JW |
1155 | } |
1156 | ||
71e3aac0 AA |
1157 | pmd_t *page_check_address_pmd(struct page *page, |
1158 | struct mm_struct *mm, | |
1159 | unsigned long address, | |
1160 | enum page_check_address_pmd_flag flag) | |
1161 | { | |
1162 | pgd_t *pgd; | |
1163 | pud_t *pud; | |
1164 | pmd_t *pmd, *ret = NULL; | |
1165 | ||
1166 | if (address & ~HPAGE_PMD_MASK) | |
1167 | goto out; | |
1168 | ||
1169 | pgd = pgd_offset(mm, address); | |
1170 | if (!pgd_present(*pgd)) | |
1171 | goto out; | |
1172 | ||
1173 | pud = pud_offset(pgd, address); | |
1174 | if (!pud_present(*pud)) | |
1175 | goto out; | |
1176 | ||
1177 | pmd = pmd_offset(pud, address); | |
1178 | if (pmd_none(*pmd)) | |
1179 | goto out; | |
1180 | if (pmd_page(*pmd) != page) | |
1181 | goto out; | |
94fcc585 AA |
1182 | /* |
1183 | * split_vma() may create temporary aliased mappings. There is | |
1184 | * no risk as long as all huge pmd are found and have their | |
1185 | * splitting bit set before __split_huge_page_refcount | |
1186 | * runs. Finding the same huge pmd more than once during the | |
1187 | * same rmap walk is not a problem. | |
1188 | */ | |
1189 | if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG && | |
1190 | pmd_trans_splitting(*pmd)) | |
1191 | goto out; | |
71e3aac0 AA |
1192 | if (pmd_trans_huge(*pmd)) { |
1193 | VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG && | |
1194 | !pmd_trans_splitting(*pmd)); | |
1195 | ret = pmd; | |
1196 | } | |
1197 | out: | |
1198 | return ret; | |
1199 | } | |
1200 | ||
1201 | static int __split_huge_page_splitting(struct page *page, | |
1202 | struct vm_area_struct *vma, | |
1203 | unsigned long address) | |
1204 | { | |
1205 | struct mm_struct *mm = vma->vm_mm; | |
1206 | pmd_t *pmd; | |
1207 | int ret = 0; | |
1208 | ||
1209 | spin_lock(&mm->page_table_lock); | |
1210 | pmd = page_check_address_pmd(page, mm, address, | |
1211 | PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG); | |
1212 | if (pmd) { | |
1213 | /* | |
1214 | * We can't temporarily set the pmd to null in order | |
1215 | * to split it, the pmd must remain marked huge at all | |
1216 | * times or the VM won't take the pmd_trans_huge paths | |
2b575eb6 | 1217 | * and it won't wait on the anon_vma->root->mutex to |
71e3aac0 AA |
1218 | * serialize against split_huge_page*. |
1219 | */ | |
1220 | pmdp_splitting_flush_notify(vma, address, pmd); | |
1221 | ret = 1; | |
1222 | } | |
1223 | spin_unlock(&mm->page_table_lock); | |
1224 | ||
1225 | return ret; | |
1226 | } | |
1227 | ||
1228 | static void __split_huge_page_refcount(struct page *page) | |
1229 | { | |
1230 | int i; | |
71e3aac0 | 1231 | struct zone *zone = page_zone(page); |
70b50f94 | 1232 | int tail_count = 0; |
71e3aac0 AA |
1233 | |
1234 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
1235 | spin_lock_irq(&zone->lru_lock); | |
1236 | compound_lock(page); | |
e94c8a9c KH |
1237 | /* complete memcg works before add pages to LRU */ |
1238 | mem_cgroup_split_huge_fixup(page); | |
71e3aac0 | 1239 | |
45676885 | 1240 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { |
71e3aac0 AA |
1241 | struct page *page_tail = page + i; |
1242 | ||
70b50f94 AA |
1243 | /* tail_page->_mapcount cannot change */ |
1244 | BUG_ON(page_mapcount(page_tail) < 0); | |
1245 | tail_count += page_mapcount(page_tail); | |
1246 | /* check for overflow */ | |
1247 | BUG_ON(tail_count < 0); | |
1248 | BUG_ON(atomic_read(&page_tail->_count) != 0); | |
1249 | /* | |
1250 | * tail_page->_count is zero and not changing from | |
1251 | * under us. But get_page_unless_zero() may be running | |
1252 | * from under us on the tail_page. If we used | |
1253 | * atomic_set() below instead of atomic_add(), we | |
1254 | * would then run atomic_set() concurrently with | |
1255 | * get_page_unless_zero(), and atomic_set() is | |
1256 | * implemented in C not using locked ops. spin_unlock | |
1257 | * on x86 sometime uses locked ops because of PPro | |
1258 | * errata 66, 92, so unless somebody can guarantee | |
1259 | * atomic_set() here would be safe on all archs (and | |
1260 | * not only on x86), it's safer to use atomic_add(). | |
1261 | */ | |
1262 | atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1, | |
1263 | &page_tail->_count); | |
71e3aac0 AA |
1264 | |
1265 | /* after clearing PageTail the gup refcount can be released */ | |
1266 | smp_mb(); | |
1267 | ||
a6d30ddd JD |
1268 | /* |
1269 | * retain hwpoison flag of the poisoned tail page: | |
1270 | * fix for the unsuitable process killed on Guest Machine(KVM) | |
1271 | * by the memory-failure. | |
1272 | */ | |
1273 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON; | |
71e3aac0 AA |
1274 | page_tail->flags |= (page->flags & |
1275 | ((1L << PG_referenced) | | |
1276 | (1L << PG_swapbacked) | | |
1277 | (1L << PG_mlocked) | | |
1278 | (1L << PG_uptodate))); | |
1279 | page_tail->flags |= (1L << PG_dirty); | |
1280 | ||
70b50f94 | 1281 | /* clear PageTail before overwriting first_page */ |
71e3aac0 AA |
1282 | smp_wmb(); |
1283 | ||
1284 | /* | |
1285 | * __split_huge_page_splitting() already set the | |
1286 | * splitting bit in all pmd that could map this | |
1287 | * hugepage, that will ensure no CPU can alter the | |
1288 | * mapcount on the head page. The mapcount is only | |
1289 | * accounted in the head page and it has to be | |
1290 | * transferred to all tail pages in the below code. So | |
1291 | * for this code to be safe, the split the mapcount | |
1292 | * can't change. But that doesn't mean userland can't | |
1293 | * keep changing and reading the page contents while | |
1294 | * we transfer the mapcount, so the pmd splitting | |
1295 | * status is achieved setting a reserved bit in the | |
1296 | * pmd, not by clearing the present bit. | |
1297 | */ | |
71e3aac0 AA |
1298 | page_tail->_mapcount = page->_mapcount; |
1299 | ||
1300 | BUG_ON(page_tail->mapping); | |
1301 | page_tail->mapping = page->mapping; | |
1302 | ||
45676885 | 1303 | page_tail->index = page->index + i; |
71e3aac0 AA |
1304 | |
1305 | BUG_ON(!PageAnon(page_tail)); | |
1306 | BUG_ON(!PageUptodate(page_tail)); | |
1307 | BUG_ON(!PageDirty(page_tail)); | |
1308 | BUG_ON(!PageSwapBacked(page_tail)); | |
1309 | ||
ca3e0214 | 1310 | |
71e3aac0 AA |
1311 | lru_add_page_tail(zone, page, page_tail); |
1312 | } | |
70b50f94 AA |
1313 | atomic_sub(tail_count, &page->_count); |
1314 | BUG_ON(atomic_read(&page->_count) <= 0); | |
71e3aac0 | 1315 | |
79134171 AA |
1316 | __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); |
1317 | __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR); | |
1318 | ||
71e3aac0 AA |
1319 | ClearPageCompound(page); |
1320 | compound_unlock(page); | |
1321 | spin_unlock_irq(&zone->lru_lock); | |
1322 | ||
1323 | for (i = 1; i < HPAGE_PMD_NR; i++) { | |
1324 | struct page *page_tail = page + i; | |
1325 | BUG_ON(page_count(page_tail) <= 0); | |
1326 | /* | |
1327 | * Tail pages may be freed if there wasn't any mapping | |
1328 | * like if add_to_swap() is running on a lru page that | |
1329 | * had its mapping zapped. And freeing these pages | |
1330 | * requires taking the lru_lock so we do the put_page | |
1331 | * of the tail pages after the split is complete. | |
1332 | */ | |
1333 | put_page(page_tail); | |
1334 | } | |
1335 | ||
1336 | /* | |
1337 | * Only the head page (now become a regular page) is required | |
1338 | * to be pinned by the caller. | |
1339 | */ | |
1340 | BUG_ON(page_count(page) <= 0); | |
1341 | } | |
1342 | ||
1343 | static int __split_huge_page_map(struct page *page, | |
1344 | struct vm_area_struct *vma, | |
1345 | unsigned long address) | |
1346 | { | |
1347 | struct mm_struct *mm = vma->vm_mm; | |
1348 | pmd_t *pmd, _pmd; | |
1349 | int ret = 0, i; | |
1350 | pgtable_t pgtable; | |
1351 | unsigned long haddr; | |
1352 | ||
1353 | spin_lock(&mm->page_table_lock); | |
1354 | pmd = page_check_address_pmd(page, mm, address, | |
1355 | PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG); | |
1356 | if (pmd) { | |
1357 | pgtable = get_pmd_huge_pte(mm); | |
1358 | pmd_populate(mm, &_pmd, pgtable); | |
1359 | ||
1360 | for (i = 0, haddr = address; i < HPAGE_PMD_NR; | |
1361 | i++, haddr += PAGE_SIZE) { | |
1362 | pte_t *pte, entry; | |
1363 | BUG_ON(PageCompound(page+i)); | |
1364 | entry = mk_pte(page + i, vma->vm_page_prot); | |
1365 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
1366 | if (!pmd_write(*pmd)) | |
1367 | entry = pte_wrprotect(entry); | |
1368 | else | |
1369 | BUG_ON(page_mapcount(page) != 1); | |
1370 | if (!pmd_young(*pmd)) | |
1371 | entry = pte_mkold(entry); | |
1372 | pte = pte_offset_map(&_pmd, haddr); | |
1373 | BUG_ON(!pte_none(*pte)); | |
1374 | set_pte_at(mm, haddr, pte, entry); | |
1375 | pte_unmap(pte); | |
1376 | } | |
1377 | ||
71e3aac0 AA |
1378 | smp_wmb(); /* make pte visible before pmd */ |
1379 | /* | |
1380 | * Up to this point the pmd is present and huge and | |
1381 | * userland has the whole access to the hugepage | |
1382 | * during the split (which happens in place). If we | |
1383 | * overwrite the pmd with the not-huge version | |
1384 | * pointing to the pte here (which of course we could | |
1385 | * if all CPUs were bug free), userland could trigger | |
1386 | * a small page size TLB miss on the small sized TLB | |
1387 | * while the hugepage TLB entry is still established | |
1388 | * in the huge TLB. Some CPU doesn't like that. See | |
1389 | * http://support.amd.com/us/Processor_TechDocs/41322.pdf, | |
1390 | * Erratum 383 on page 93. Intel should be safe but is | |
1391 | * also warns that it's only safe if the permission | |
1392 | * and cache attributes of the two entries loaded in | |
1393 | * the two TLB is identical (which should be the case | |
1394 | * here). But it is generally safer to never allow | |
1395 | * small and huge TLB entries for the same virtual | |
1396 | * address to be loaded simultaneously. So instead of | |
1397 | * doing "pmd_populate(); flush_tlb_range();" we first | |
1398 | * mark the current pmd notpresent (atomically because | |
1399 | * here the pmd_trans_huge and pmd_trans_splitting | |
1400 | * must remain set at all times on the pmd until the | |
1401 | * split is complete for this pmd), then we flush the | |
1402 | * SMP TLB and finally we write the non-huge version | |
1403 | * of the pmd entry with pmd_populate. | |
1404 | */ | |
1405 | set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd)); | |
1406 | flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); | |
1407 | pmd_populate(mm, pmd, pgtable); | |
1408 | ret = 1; | |
1409 | } | |
1410 | spin_unlock(&mm->page_table_lock); | |
1411 | ||
1412 | return ret; | |
1413 | } | |
1414 | ||
2b575eb6 | 1415 | /* must be called with anon_vma->root->mutex hold */ |
71e3aac0 AA |
1416 | static void __split_huge_page(struct page *page, |
1417 | struct anon_vma *anon_vma) | |
1418 | { | |
1419 | int mapcount, mapcount2; | |
1420 | struct anon_vma_chain *avc; | |
1421 | ||
1422 | BUG_ON(!PageHead(page)); | |
1423 | BUG_ON(PageTail(page)); | |
1424 | ||
1425 | mapcount = 0; | |
1426 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { | |
1427 | struct vm_area_struct *vma = avc->vma; | |
1428 | unsigned long addr = vma_address(page, vma); | |
1429 | BUG_ON(is_vma_temporary_stack(vma)); | |
1430 | if (addr == -EFAULT) | |
1431 | continue; | |
1432 | mapcount += __split_huge_page_splitting(page, vma, addr); | |
1433 | } | |
05759d38 AA |
1434 | /* |
1435 | * It is critical that new vmas are added to the tail of the | |
1436 | * anon_vma list. This guarantes that if copy_huge_pmd() runs | |
1437 | * and establishes a child pmd before | |
1438 | * __split_huge_page_splitting() freezes the parent pmd (so if | |
1439 | * we fail to prevent copy_huge_pmd() from running until the | |
1440 | * whole __split_huge_page() is complete), we will still see | |
1441 | * the newly established pmd of the child later during the | |
1442 | * walk, to be able to set it as pmd_trans_splitting too. | |
1443 | */ | |
1444 | if (mapcount != page_mapcount(page)) | |
1445 | printk(KERN_ERR "mapcount %d page_mapcount %d\n", | |
1446 | mapcount, page_mapcount(page)); | |
71e3aac0 AA |
1447 | BUG_ON(mapcount != page_mapcount(page)); |
1448 | ||
1449 | __split_huge_page_refcount(page); | |
1450 | ||
1451 | mapcount2 = 0; | |
1452 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { | |
1453 | struct vm_area_struct *vma = avc->vma; | |
1454 | unsigned long addr = vma_address(page, vma); | |
1455 | BUG_ON(is_vma_temporary_stack(vma)); | |
1456 | if (addr == -EFAULT) | |
1457 | continue; | |
1458 | mapcount2 += __split_huge_page_map(page, vma, addr); | |
1459 | } | |
05759d38 AA |
1460 | if (mapcount != mapcount2) |
1461 | printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n", | |
1462 | mapcount, mapcount2, page_mapcount(page)); | |
71e3aac0 AA |
1463 | BUG_ON(mapcount != mapcount2); |
1464 | } | |
1465 | ||
1466 | int split_huge_page(struct page *page) | |
1467 | { | |
1468 | struct anon_vma *anon_vma; | |
1469 | int ret = 1; | |
1470 | ||
1471 | BUG_ON(!PageAnon(page)); | |
1472 | anon_vma = page_lock_anon_vma(page); | |
1473 | if (!anon_vma) | |
1474 | goto out; | |
1475 | ret = 0; | |
1476 | if (!PageCompound(page)) | |
1477 | goto out_unlock; | |
1478 | ||
1479 | BUG_ON(!PageSwapBacked(page)); | |
1480 | __split_huge_page(page, anon_vma); | |
81ab4201 | 1481 | count_vm_event(THP_SPLIT); |
71e3aac0 AA |
1482 | |
1483 | BUG_ON(PageCompound(page)); | |
1484 | out_unlock: | |
1485 | page_unlock_anon_vma(anon_vma); | |
1486 | out: | |
1487 | return ret; | |
1488 | } | |
1489 | ||
78f11a25 AA |
1490 | #define VM_NO_THP (VM_SPECIAL|VM_INSERTPAGE|VM_MIXEDMAP|VM_SAO| \ |
1491 | VM_HUGETLB|VM_SHARED|VM_MAYSHARE) | |
1492 | ||
60ab3244 AA |
1493 | int hugepage_madvise(struct vm_area_struct *vma, |
1494 | unsigned long *vm_flags, int advice) | |
0af4e98b | 1495 | { |
a664b2d8 AA |
1496 | switch (advice) { |
1497 | case MADV_HUGEPAGE: | |
1498 | /* | |
1499 | * Be somewhat over-protective like KSM for now! | |
1500 | */ | |
78f11a25 | 1501 | if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP)) |
a664b2d8 AA |
1502 | return -EINVAL; |
1503 | *vm_flags &= ~VM_NOHUGEPAGE; | |
1504 | *vm_flags |= VM_HUGEPAGE; | |
60ab3244 AA |
1505 | /* |
1506 | * If the vma become good for khugepaged to scan, | |
1507 | * register it here without waiting a page fault that | |
1508 | * may not happen any time soon. | |
1509 | */ | |
1510 | if (unlikely(khugepaged_enter_vma_merge(vma))) | |
1511 | return -ENOMEM; | |
a664b2d8 AA |
1512 | break; |
1513 | case MADV_NOHUGEPAGE: | |
1514 | /* | |
1515 | * Be somewhat over-protective like KSM for now! | |
1516 | */ | |
78f11a25 | 1517 | if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP)) |
a664b2d8 AA |
1518 | return -EINVAL; |
1519 | *vm_flags &= ~VM_HUGEPAGE; | |
1520 | *vm_flags |= VM_NOHUGEPAGE; | |
60ab3244 AA |
1521 | /* |
1522 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
1523 | * this vma even if we leave the mm registered in khugepaged if | |
1524 | * it got registered before VM_NOHUGEPAGE was set. | |
1525 | */ | |
a664b2d8 AA |
1526 | break; |
1527 | } | |
0af4e98b AA |
1528 | |
1529 | return 0; | |
1530 | } | |
1531 | ||
ba76149f AA |
1532 | static int __init khugepaged_slab_init(void) |
1533 | { | |
1534 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
1535 | sizeof(struct mm_slot), | |
1536 | __alignof__(struct mm_slot), 0, NULL); | |
1537 | if (!mm_slot_cache) | |
1538 | return -ENOMEM; | |
1539 | ||
1540 | return 0; | |
1541 | } | |
1542 | ||
1543 | static void __init khugepaged_slab_free(void) | |
1544 | { | |
1545 | kmem_cache_destroy(mm_slot_cache); | |
1546 | mm_slot_cache = NULL; | |
1547 | } | |
1548 | ||
1549 | static inline struct mm_slot *alloc_mm_slot(void) | |
1550 | { | |
1551 | if (!mm_slot_cache) /* initialization failed */ | |
1552 | return NULL; | |
1553 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
1554 | } | |
1555 | ||
1556 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
1557 | { | |
1558 | kmem_cache_free(mm_slot_cache, mm_slot); | |
1559 | } | |
1560 | ||
1561 | static int __init mm_slots_hash_init(void) | |
1562 | { | |
1563 | mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head), | |
1564 | GFP_KERNEL); | |
1565 | if (!mm_slots_hash) | |
1566 | return -ENOMEM; | |
1567 | return 0; | |
1568 | } | |
1569 | ||
1570 | #if 0 | |
1571 | static void __init mm_slots_hash_free(void) | |
1572 | { | |
1573 | kfree(mm_slots_hash); | |
1574 | mm_slots_hash = NULL; | |
1575 | } | |
1576 | #endif | |
1577 | ||
1578 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
1579 | { | |
1580 | struct mm_slot *mm_slot; | |
1581 | struct hlist_head *bucket; | |
1582 | struct hlist_node *node; | |
1583 | ||
1584 | bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct)) | |
1585 | % MM_SLOTS_HASH_HEADS]; | |
1586 | hlist_for_each_entry(mm_slot, node, bucket, hash) { | |
1587 | if (mm == mm_slot->mm) | |
1588 | return mm_slot; | |
1589 | } | |
1590 | return NULL; | |
1591 | } | |
1592 | ||
1593 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
1594 | struct mm_slot *mm_slot) | |
1595 | { | |
1596 | struct hlist_head *bucket; | |
1597 | ||
1598 | bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct)) | |
1599 | % MM_SLOTS_HASH_HEADS]; | |
1600 | mm_slot->mm = mm; | |
1601 | hlist_add_head(&mm_slot->hash, bucket); | |
1602 | } | |
1603 | ||
1604 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
1605 | { | |
1606 | return atomic_read(&mm->mm_users) == 0; | |
1607 | } | |
1608 | ||
1609 | int __khugepaged_enter(struct mm_struct *mm) | |
1610 | { | |
1611 | struct mm_slot *mm_slot; | |
1612 | int wakeup; | |
1613 | ||
1614 | mm_slot = alloc_mm_slot(); | |
1615 | if (!mm_slot) | |
1616 | return -ENOMEM; | |
1617 | ||
1618 | /* __khugepaged_exit() must not run from under us */ | |
1619 | VM_BUG_ON(khugepaged_test_exit(mm)); | |
1620 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { | |
1621 | free_mm_slot(mm_slot); | |
1622 | return 0; | |
1623 | } | |
1624 | ||
1625 | spin_lock(&khugepaged_mm_lock); | |
1626 | insert_to_mm_slots_hash(mm, mm_slot); | |
1627 | /* | |
1628 | * Insert just behind the scanning cursor, to let the area settle | |
1629 | * down a little. | |
1630 | */ | |
1631 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
1632 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
1633 | spin_unlock(&khugepaged_mm_lock); | |
1634 | ||
1635 | atomic_inc(&mm->mm_count); | |
1636 | if (wakeup) | |
1637 | wake_up_interruptible(&khugepaged_wait); | |
1638 | ||
1639 | return 0; | |
1640 | } | |
1641 | ||
1642 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma) | |
1643 | { | |
1644 | unsigned long hstart, hend; | |
1645 | if (!vma->anon_vma) | |
1646 | /* | |
1647 | * Not yet faulted in so we will register later in the | |
1648 | * page fault if needed. | |
1649 | */ | |
1650 | return 0; | |
78f11a25 | 1651 | if (vma->vm_ops) |
ba76149f AA |
1652 | /* khugepaged not yet working on file or special mappings */ |
1653 | return 0; | |
78f11a25 AA |
1654 | /* |
1655 | * If is_pfn_mapping() is true is_learn_pfn_mapping() must be | |
1656 | * true too, verify it here. | |
1657 | */ | |
1658 | VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP); | |
ba76149f AA |
1659 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
1660 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1661 | if (hstart < hend) | |
1662 | return khugepaged_enter(vma); | |
1663 | return 0; | |
1664 | } | |
1665 | ||
1666 | void __khugepaged_exit(struct mm_struct *mm) | |
1667 | { | |
1668 | struct mm_slot *mm_slot; | |
1669 | int free = 0; | |
1670 | ||
1671 | spin_lock(&khugepaged_mm_lock); | |
1672 | mm_slot = get_mm_slot(mm); | |
1673 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
1674 | hlist_del(&mm_slot->hash); | |
1675 | list_del(&mm_slot->mm_node); | |
1676 | free = 1; | |
1677 | } | |
d788e80a | 1678 | spin_unlock(&khugepaged_mm_lock); |
ba76149f AA |
1679 | |
1680 | if (free) { | |
ba76149f AA |
1681 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); |
1682 | free_mm_slot(mm_slot); | |
1683 | mmdrop(mm); | |
1684 | } else if (mm_slot) { | |
ba76149f AA |
1685 | /* |
1686 | * This is required to serialize against | |
1687 | * khugepaged_test_exit() (which is guaranteed to run | |
1688 | * under mmap sem read mode). Stop here (after we | |
1689 | * return all pagetables will be destroyed) until | |
1690 | * khugepaged has finished working on the pagetables | |
1691 | * under the mmap_sem. | |
1692 | */ | |
1693 | down_write(&mm->mmap_sem); | |
1694 | up_write(&mm->mmap_sem); | |
d788e80a | 1695 | } |
ba76149f AA |
1696 | } |
1697 | ||
1698 | static void release_pte_page(struct page *page) | |
1699 | { | |
1700 | /* 0 stands for page_is_file_cache(page) == false */ | |
1701 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
1702 | unlock_page(page); | |
1703 | putback_lru_page(page); | |
1704 | } | |
1705 | ||
1706 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
1707 | { | |
1708 | while (--_pte >= pte) { | |
1709 | pte_t pteval = *_pte; | |
1710 | if (!pte_none(pteval)) | |
1711 | release_pte_page(pte_page(pteval)); | |
1712 | } | |
1713 | } | |
1714 | ||
1715 | static void release_all_pte_pages(pte_t *pte) | |
1716 | { | |
1717 | release_pte_pages(pte, pte + HPAGE_PMD_NR); | |
1718 | } | |
1719 | ||
1720 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, | |
1721 | unsigned long address, | |
1722 | pte_t *pte) | |
1723 | { | |
1724 | struct page *page; | |
1725 | pte_t *_pte; | |
1726 | int referenced = 0, isolated = 0, none = 0; | |
1727 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1728 | _pte++, address += PAGE_SIZE) { | |
1729 | pte_t pteval = *_pte; | |
1730 | if (pte_none(pteval)) { | |
1731 | if (++none <= khugepaged_max_ptes_none) | |
1732 | continue; | |
1733 | else { | |
1734 | release_pte_pages(pte, _pte); | |
1735 | goto out; | |
1736 | } | |
1737 | } | |
1738 | if (!pte_present(pteval) || !pte_write(pteval)) { | |
1739 | release_pte_pages(pte, _pte); | |
1740 | goto out; | |
1741 | } | |
1742 | page = vm_normal_page(vma, address, pteval); | |
1743 | if (unlikely(!page)) { | |
1744 | release_pte_pages(pte, _pte); | |
1745 | goto out; | |
1746 | } | |
1747 | VM_BUG_ON(PageCompound(page)); | |
1748 | BUG_ON(!PageAnon(page)); | |
1749 | VM_BUG_ON(!PageSwapBacked(page)); | |
1750 | ||
1751 | /* cannot use mapcount: can't collapse if there's a gup pin */ | |
1752 | if (page_count(page) != 1) { | |
1753 | release_pte_pages(pte, _pte); | |
1754 | goto out; | |
1755 | } | |
1756 | /* | |
1757 | * We can do it before isolate_lru_page because the | |
1758 | * page can't be freed from under us. NOTE: PG_lock | |
1759 | * is needed to serialize against split_huge_page | |
1760 | * when invoked from the VM. | |
1761 | */ | |
1762 | if (!trylock_page(page)) { | |
1763 | release_pte_pages(pte, _pte); | |
1764 | goto out; | |
1765 | } | |
1766 | /* | |
1767 | * Isolate the page to avoid collapsing an hugepage | |
1768 | * currently in use by the VM. | |
1769 | */ | |
1770 | if (isolate_lru_page(page)) { | |
1771 | unlock_page(page); | |
1772 | release_pte_pages(pte, _pte); | |
1773 | goto out; | |
1774 | } | |
1775 | /* 0 stands for page_is_file_cache(page) == false */ | |
1776 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
1777 | VM_BUG_ON(!PageLocked(page)); | |
1778 | VM_BUG_ON(PageLRU(page)); | |
1779 | ||
1780 | /* If there is no mapped pte young don't collapse the page */ | |
8ee53820 AA |
1781 | if (pte_young(pteval) || PageReferenced(page) || |
1782 | mmu_notifier_test_young(vma->vm_mm, address)) | |
ba76149f AA |
1783 | referenced = 1; |
1784 | } | |
1785 | if (unlikely(!referenced)) | |
1786 | release_all_pte_pages(pte); | |
1787 | else | |
1788 | isolated = 1; | |
1789 | out: | |
1790 | return isolated; | |
1791 | } | |
1792 | ||
1793 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
1794 | struct vm_area_struct *vma, | |
1795 | unsigned long address, | |
1796 | spinlock_t *ptl) | |
1797 | { | |
1798 | pte_t *_pte; | |
1799 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { | |
1800 | pte_t pteval = *_pte; | |
1801 | struct page *src_page; | |
1802 | ||
1803 | if (pte_none(pteval)) { | |
1804 | clear_user_highpage(page, address); | |
1805 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
1806 | } else { | |
1807 | src_page = pte_page(pteval); | |
1808 | copy_user_highpage(page, src_page, address, vma); | |
1809 | VM_BUG_ON(page_mapcount(src_page) != 1); | |
1810 | VM_BUG_ON(page_count(src_page) != 2); | |
1811 | release_pte_page(src_page); | |
1812 | /* | |
1813 | * ptl mostly unnecessary, but preempt has to | |
1814 | * be disabled to update the per-cpu stats | |
1815 | * inside page_remove_rmap(). | |
1816 | */ | |
1817 | spin_lock(ptl); | |
1818 | /* | |
1819 | * paravirt calls inside pte_clear here are | |
1820 | * superfluous. | |
1821 | */ | |
1822 | pte_clear(vma->vm_mm, address, _pte); | |
1823 | page_remove_rmap(src_page); | |
1824 | spin_unlock(ptl); | |
1825 | free_page_and_swap_cache(src_page); | |
1826 | } | |
1827 | ||
1828 | address += PAGE_SIZE; | |
1829 | page++; | |
1830 | } | |
1831 | } | |
1832 | ||
1833 | static void collapse_huge_page(struct mm_struct *mm, | |
1834 | unsigned long address, | |
ce83d217 | 1835 | struct page **hpage, |
5c4b4be3 AK |
1836 | struct vm_area_struct *vma, |
1837 | int node) | |
ba76149f | 1838 | { |
ba76149f AA |
1839 | pgd_t *pgd; |
1840 | pud_t *pud; | |
1841 | pmd_t *pmd, _pmd; | |
1842 | pte_t *pte; | |
1843 | pgtable_t pgtable; | |
1844 | struct page *new_page; | |
1845 | spinlock_t *ptl; | |
1846 | int isolated; | |
1847 | unsigned long hstart, hend; | |
1848 | ||
1849 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
0bbbc0b3 | 1850 | #ifndef CONFIG_NUMA |
692e0b35 | 1851 | up_read(&mm->mmap_sem); |
ba76149f | 1852 | VM_BUG_ON(!*hpage); |
ce83d217 | 1853 | new_page = *hpage; |
0bbbc0b3 AA |
1854 | #else |
1855 | VM_BUG_ON(*hpage); | |
ce83d217 AA |
1856 | /* |
1857 | * Allocate the page while the vma is still valid and under | |
1858 | * the mmap_sem read mode so there is no memory allocation | |
1859 | * later when we take the mmap_sem in write mode. This is more | |
1860 | * friendly behavior (OTOH it may actually hide bugs) to | |
1861 | * filesystems in userland with daemons allocating memory in | |
1862 | * the userland I/O paths. Allocating memory with the | |
1863 | * mmap_sem in read mode is good idea also to allow greater | |
1864 | * scalability. | |
1865 | */ | |
5c4b4be3 | 1866 | new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address, |
cc5d462f | 1867 | node, __GFP_OTHER_NODE); |
692e0b35 AA |
1868 | |
1869 | /* | |
1870 | * After allocating the hugepage, release the mmap_sem read lock in | |
1871 | * preparation for taking it in write mode. | |
1872 | */ | |
1873 | up_read(&mm->mmap_sem); | |
ce83d217 | 1874 | if (unlikely(!new_page)) { |
81ab4201 | 1875 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); |
ce83d217 AA |
1876 | *hpage = ERR_PTR(-ENOMEM); |
1877 | return; | |
1878 | } | |
692e0b35 AA |
1879 | #endif |
1880 | ||
81ab4201 | 1881 | count_vm_event(THP_COLLAPSE_ALLOC); |
ce83d217 | 1882 | if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) { |
692e0b35 | 1883 | #ifdef CONFIG_NUMA |
ce83d217 | 1884 | put_page(new_page); |
692e0b35 | 1885 | #endif |
ce83d217 AA |
1886 | return; |
1887 | } | |
ba76149f AA |
1888 | |
1889 | /* | |
1890 | * Prevent all access to pagetables with the exception of | |
1891 | * gup_fast later hanlded by the ptep_clear_flush and the VM | |
1892 | * handled by the anon_vma lock + PG_lock. | |
1893 | */ | |
1894 | down_write(&mm->mmap_sem); | |
1895 | if (unlikely(khugepaged_test_exit(mm))) | |
1896 | goto out; | |
1897 | ||
1898 | vma = find_vma(mm, address); | |
1899 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
1900 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1901 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
1902 | goto out; | |
1903 | ||
60ab3244 AA |
1904 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || |
1905 | (vma->vm_flags & VM_NOHUGEPAGE)) | |
ba76149f AA |
1906 | goto out; |
1907 | ||
78f11a25 | 1908 | if (!vma->anon_vma || vma->vm_ops) |
ba76149f | 1909 | goto out; |
a7d6e4ec AA |
1910 | if (is_vma_temporary_stack(vma)) |
1911 | goto out; | |
78f11a25 AA |
1912 | /* |
1913 | * If is_pfn_mapping() is true is_learn_pfn_mapping() must be | |
1914 | * true too, verify it here. | |
1915 | */ | |
1916 | VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP); | |
ba76149f AA |
1917 | |
1918 | pgd = pgd_offset(mm, address); | |
1919 | if (!pgd_present(*pgd)) | |
1920 | goto out; | |
1921 | ||
1922 | pud = pud_offset(pgd, address); | |
1923 | if (!pud_present(*pud)) | |
1924 | goto out; | |
1925 | ||
1926 | pmd = pmd_offset(pud, address); | |
1927 | /* pmd can't go away or become huge under us */ | |
1928 | if (!pmd_present(*pmd) || pmd_trans_huge(*pmd)) | |
1929 | goto out; | |
1930 | ||
ba76149f AA |
1931 | anon_vma_lock(vma->anon_vma); |
1932 | ||
1933 | pte = pte_offset_map(pmd, address); | |
1934 | ptl = pte_lockptr(mm, pmd); | |
1935 | ||
1936 | spin_lock(&mm->page_table_lock); /* probably unnecessary */ | |
1937 | /* | |
1938 | * After this gup_fast can't run anymore. This also removes | |
1939 | * any huge TLB entry from the CPU so we won't allow | |
1940 | * huge and small TLB entries for the same virtual address | |
1941 | * to avoid the risk of CPU bugs in that area. | |
1942 | */ | |
1943 | _pmd = pmdp_clear_flush_notify(vma, address, pmd); | |
1944 | spin_unlock(&mm->page_table_lock); | |
1945 | ||
1946 | spin_lock(ptl); | |
1947 | isolated = __collapse_huge_page_isolate(vma, address, pte); | |
1948 | spin_unlock(ptl); | |
ba76149f AA |
1949 | |
1950 | if (unlikely(!isolated)) { | |
453c7192 | 1951 | pte_unmap(pte); |
ba76149f AA |
1952 | spin_lock(&mm->page_table_lock); |
1953 | BUG_ON(!pmd_none(*pmd)); | |
1954 | set_pmd_at(mm, address, pmd, _pmd); | |
1955 | spin_unlock(&mm->page_table_lock); | |
1956 | anon_vma_unlock(vma->anon_vma); | |
ce83d217 | 1957 | goto out; |
ba76149f AA |
1958 | } |
1959 | ||
1960 | /* | |
1961 | * All pages are isolated and locked so anon_vma rmap | |
1962 | * can't run anymore. | |
1963 | */ | |
1964 | anon_vma_unlock(vma->anon_vma); | |
1965 | ||
1966 | __collapse_huge_page_copy(pte, new_page, vma, address, ptl); | |
453c7192 | 1967 | pte_unmap(pte); |
ba76149f AA |
1968 | __SetPageUptodate(new_page); |
1969 | pgtable = pmd_pgtable(_pmd); | |
1970 | VM_BUG_ON(page_count(pgtable) != 1); | |
1971 | VM_BUG_ON(page_mapcount(pgtable) != 0); | |
1972 | ||
1973 | _pmd = mk_pmd(new_page, vma->vm_page_prot); | |
1974 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); | |
1975 | _pmd = pmd_mkhuge(_pmd); | |
1976 | ||
1977 | /* | |
1978 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
1979 | * this is needed to avoid the copy_huge_page writes to become | |
1980 | * visible after the set_pmd_at() write. | |
1981 | */ | |
1982 | smp_wmb(); | |
1983 | ||
1984 | spin_lock(&mm->page_table_lock); | |
1985 | BUG_ON(!pmd_none(*pmd)); | |
1986 | page_add_new_anon_rmap(new_page, vma, address); | |
1987 | set_pmd_at(mm, address, pmd, _pmd); | |
35d8c7ad | 1988 | update_mmu_cache(vma, address, _pmd); |
ba76149f | 1989 | prepare_pmd_huge_pte(pgtable, mm); |
ba76149f AA |
1990 | spin_unlock(&mm->page_table_lock); |
1991 | ||
0bbbc0b3 | 1992 | #ifndef CONFIG_NUMA |
ba76149f | 1993 | *hpage = NULL; |
0bbbc0b3 | 1994 | #endif |
ba76149f | 1995 | khugepaged_pages_collapsed++; |
ce83d217 | 1996 | out_up_write: |
ba76149f | 1997 | up_write(&mm->mmap_sem); |
0bbbc0b3 AA |
1998 | return; |
1999 | ||
ce83d217 | 2000 | out: |
678ff896 | 2001 | mem_cgroup_uncharge_page(new_page); |
0bbbc0b3 AA |
2002 | #ifdef CONFIG_NUMA |
2003 | put_page(new_page); | |
2004 | #endif | |
ce83d217 | 2005 | goto out_up_write; |
ba76149f AA |
2006 | } |
2007 | ||
2008 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
2009 | struct vm_area_struct *vma, | |
2010 | unsigned long address, | |
2011 | struct page **hpage) | |
2012 | { | |
2013 | pgd_t *pgd; | |
2014 | pud_t *pud; | |
2015 | pmd_t *pmd; | |
2016 | pte_t *pte, *_pte; | |
2017 | int ret = 0, referenced = 0, none = 0; | |
2018 | struct page *page; | |
2019 | unsigned long _address; | |
2020 | spinlock_t *ptl; | |
5c4b4be3 | 2021 | int node = -1; |
ba76149f AA |
2022 | |
2023 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2024 | ||
2025 | pgd = pgd_offset(mm, address); | |
2026 | if (!pgd_present(*pgd)) | |
2027 | goto out; | |
2028 | ||
2029 | pud = pud_offset(pgd, address); | |
2030 | if (!pud_present(*pud)) | |
2031 | goto out; | |
2032 | ||
2033 | pmd = pmd_offset(pud, address); | |
2034 | if (!pmd_present(*pmd) || pmd_trans_huge(*pmd)) | |
2035 | goto out; | |
2036 | ||
2037 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
2038 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
2039 | _pte++, _address += PAGE_SIZE) { | |
2040 | pte_t pteval = *_pte; | |
2041 | if (pte_none(pteval)) { | |
2042 | if (++none <= khugepaged_max_ptes_none) | |
2043 | continue; | |
2044 | else | |
2045 | goto out_unmap; | |
2046 | } | |
2047 | if (!pte_present(pteval) || !pte_write(pteval)) | |
2048 | goto out_unmap; | |
2049 | page = vm_normal_page(vma, _address, pteval); | |
2050 | if (unlikely(!page)) | |
2051 | goto out_unmap; | |
5c4b4be3 AK |
2052 | /* |
2053 | * Chose the node of the first page. This could | |
2054 | * be more sophisticated and look at more pages, | |
2055 | * but isn't for now. | |
2056 | */ | |
2057 | if (node == -1) | |
2058 | node = page_to_nid(page); | |
ba76149f AA |
2059 | VM_BUG_ON(PageCompound(page)); |
2060 | if (!PageLRU(page) || PageLocked(page) || !PageAnon(page)) | |
2061 | goto out_unmap; | |
2062 | /* cannot use mapcount: can't collapse if there's a gup pin */ | |
2063 | if (page_count(page) != 1) | |
2064 | goto out_unmap; | |
8ee53820 AA |
2065 | if (pte_young(pteval) || PageReferenced(page) || |
2066 | mmu_notifier_test_young(vma->vm_mm, address)) | |
ba76149f AA |
2067 | referenced = 1; |
2068 | } | |
2069 | if (referenced) | |
2070 | ret = 1; | |
2071 | out_unmap: | |
2072 | pte_unmap_unlock(pte, ptl); | |
ce83d217 AA |
2073 | if (ret) |
2074 | /* collapse_huge_page will return with the mmap_sem released */ | |
5c4b4be3 | 2075 | collapse_huge_page(mm, address, hpage, vma, node); |
ba76149f AA |
2076 | out: |
2077 | return ret; | |
2078 | } | |
2079 | ||
2080 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
2081 | { | |
2082 | struct mm_struct *mm = mm_slot->mm; | |
2083 | ||
b9980cdc | 2084 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2085 | |
2086 | if (khugepaged_test_exit(mm)) { | |
2087 | /* free mm_slot */ | |
2088 | hlist_del(&mm_slot->hash); | |
2089 | list_del(&mm_slot->mm_node); | |
2090 | ||
2091 | /* | |
2092 | * Not strictly needed because the mm exited already. | |
2093 | * | |
2094 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
2095 | */ | |
2096 | ||
2097 | /* khugepaged_mm_lock actually not necessary for the below */ | |
2098 | free_mm_slot(mm_slot); | |
2099 | mmdrop(mm); | |
2100 | } | |
2101 | } | |
2102 | ||
2103 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
2104 | struct page **hpage) | |
2f1da642 HS |
2105 | __releases(&khugepaged_mm_lock) |
2106 | __acquires(&khugepaged_mm_lock) | |
ba76149f AA |
2107 | { |
2108 | struct mm_slot *mm_slot; | |
2109 | struct mm_struct *mm; | |
2110 | struct vm_area_struct *vma; | |
2111 | int progress = 0; | |
2112 | ||
2113 | VM_BUG_ON(!pages); | |
b9980cdc | 2114 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); |
ba76149f AA |
2115 | |
2116 | if (khugepaged_scan.mm_slot) | |
2117 | mm_slot = khugepaged_scan.mm_slot; | |
2118 | else { | |
2119 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2120 | struct mm_slot, mm_node); | |
2121 | khugepaged_scan.address = 0; | |
2122 | khugepaged_scan.mm_slot = mm_slot; | |
2123 | } | |
2124 | spin_unlock(&khugepaged_mm_lock); | |
2125 | ||
2126 | mm = mm_slot->mm; | |
2127 | down_read(&mm->mmap_sem); | |
2128 | if (unlikely(khugepaged_test_exit(mm))) | |
2129 | vma = NULL; | |
2130 | else | |
2131 | vma = find_vma(mm, khugepaged_scan.address); | |
2132 | ||
2133 | progress++; | |
2134 | for (; vma; vma = vma->vm_next) { | |
2135 | unsigned long hstart, hend; | |
2136 | ||
2137 | cond_resched(); | |
2138 | if (unlikely(khugepaged_test_exit(mm))) { | |
2139 | progress++; | |
2140 | break; | |
2141 | } | |
2142 | ||
60ab3244 AA |
2143 | if ((!(vma->vm_flags & VM_HUGEPAGE) && |
2144 | !khugepaged_always()) || | |
2145 | (vma->vm_flags & VM_NOHUGEPAGE)) { | |
a7d6e4ec | 2146 | skip: |
ba76149f AA |
2147 | progress++; |
2148 | continue; | |
2149 | } | |
78f11a25 | 2150 | if (!vma->anon_vma || vma->vm_ops) |
a7d6e4ec AA |
2151 | goto skip; |
2152 | if (is_vma_temporary_stack(vma)) | |
2153 | goto skip; | |
78f11a25 AA |
2154 | /* |
2155 | * If is_pfn_mapping() is true is_learn_pfn_mapping() | |
2156 | * must be true too, verify it here. | |
2157 | */ | |
2158 | VM_BUG_ON(is_linear_pfn_mapping(vma) || | |
2159 | vma->vm_flags & VM_NO_THP); | |
ba76149f AA |
2160 | |
2161 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2162 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
a7d6e4ec AA |
2163 | if (hstart >= hend) |
2164 | goto skip; | |
2165 | if (khugepaged_scan.address > hend) | |
2166 | goto skip; | |
ba76149f AA |
2167 | if (khugepaged_scan.address < hstart) |
2168 | khugepaged_scan.address = hstart; | |
a7d6e4ec | 2169 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); |
ba76149f AA |
2170 | |
2171 | while (khugepaged_scan.address < hend) { | |
2172 | int ret; | |
2173 | cond_resched(); | |
2174 | if (unlikely(khugepaged_test_exit(mm))) | |
2175 | goto breakouterloop; | |
2176 | ||
2177 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2178 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2179 | hend); | |
2180 | ret = khugepaged_scan_pmd(mm, vma, | |
2181 | khugepaged_scan.address, | |
2182 | hpage); | |
2183 | /* move to next address */ | |
2184 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2185 | progress += HPAGE_PMD_NR; | |
2186 | if (ret) | |
2187 | /* we released mmap_sem so break loop */ | |
2188 | goto breakouterloop_mmap_sem; | |
2189 | if (progress >= pages) | |
2190 | goto breakouterloop; | |
2191 | } | |
2192 | } | |
2193 | breakouterloop: | |
2194 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2195 | breakouterloop_mmap_sem: | |
2196 | ||
2197 | spin_lock(&khugepaged_mm_lock); | |
a7d6e4ec | 2198 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); |
ba76149f AA |
2199 | /* |
2200 | * Release the current mm_slot if this mm is about to die, or | |
2201 | * if we scanned all vmas of this mm. | |
2202 | */ | |
2203 | if (khugepaged_test_exit(mm) || !vma) { | |
2204 | /* | |
2205 | * Make sure that if mm_users is reaching zero while | |
2206 | * khugepaged runs here, khugepaged_exit will find | |
2207 | * mm_slot not pointing to the exiting mm. | |
2208 | */ | |
2209 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2210 | khugepaged_scan.mm_slot = list_entry( | |
2211 | mm_slot->mm_node.next, | |
2212 | struct mm_slot, mm_node); | |
2213 | khugepaged_scan.address = 0; | |
2214 | } else { | |
2215 | khugepaged_scan.mm_slot = NULL; | |
2216 | khugepaged_full_scans++; | |
2217 | } | |
2218 | ||
2219 | collect_mm_slot(mm_slot); | |
2220 | } | |
2221 | ||
2222 | return progress; | |
2223 | } | |
2224 | ||
2225 | static int khugepaged_has_work(void) | |
2226 | { | |
2227 | return !list_empty(&khugepaged_scan.mm_head) && | |
2228 | khugepaged_enabled(); | |
2229 | } | |
2230 | ||
2231 | static int khugepaged_wait_event(void) | |
2232 | { | |
2233 | return !list_empty(&khugepaged_scan.mm_head) || | |
2234 | !khugepaged_enabled(); | |
2235 | } | |
2236 | ||
2237 | static void khugepaged_do_scan(struct page **hpage) | |
2238 | { | |
2239 | unsigned int progress = 0, pass_through_head = 0; | |
2240 | unsigned int pages = khugepaged_pages_to_scan; | |
2241 | ||
2242 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2243 | ||
2244 | while (progress < pages) { | |
2245 | cond_resched(); | |
2246 | ||
0bbbc0b3 | 2247 | #ifndef CONFIG_NUMA |
ba76149f AA |
2248 | if (!*hpage) { |
2249 | *hpage = alloc_hugepage(khugepaged_defrag()); | |
81ab4201 AK |
2250 | if (unlikely(!*hpage)) { |
2251 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
ba76149f | 2252 | break; |
81ab4201 AK |
2253 | } |
2254 | count_vm_event(THP_COLLAPSE_ALLOC); | |
ba76149f | 2255 | } |
0bbbc0b3 AA |
2256 | #else |
2257 | if (IS_ERR(*hpage)) | |
2258 | break; | |
2259 | #endif | |
ba76149f | 2260 | |
878aee7d AA |
2261 | if (unlikely(kthread_should_stop() || freezing(current))) |
2262 | break; | |
2263 | ||
ba76149f AA |
2264 | spin_lock(&khugepaged_mm_lock); |
2265 | if (!khugepaged_scan.mm_slot) | |
2266 | pass_through_head++; | |
2267 | if (khugepaged_has_work() && | |
2268 | pass_through_head < 2) | |
2269 | progress += khugepaged_scan_mm_slot(pages - progress, | |
2270 | hpage); | |
2271 | else | |
2272 | progress = pages; | |
2273 | spin_unlock(&khugepaged_mm_lock); | |
2274 | } | |
2275 | } | |
2276 | ||
0bbbc0b3 AA |
2277 | static void khugepaged_alloc_sleep(void) |
2278 | { | |
1dfb059b AA |
2279 | wait_event_freezable_timeout(khugepaged_wait, false, |
2280 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
0bbbc0b3 AA |
2281 | } |
2282 | ||
2283 | #ifndef CONFIG_NUMA | |
ba76149f AA |
2284 | static struct page *khugepaged_alloc_hugepage(void) |
2285 | { | |
2286 | struct page *hpage; | |
2287 | ||
2288 | do { | |
2289 | hpage = alloc_hugepage(khugepaged_defrag()); | |
81ab4201 AK |
2290 | if (!hpage) { |
2291 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
0bbbc0b3 | 2292 | khugepaged_alloc_sleep(); |
81ab4201 AK |
2293 | } else |
2294 | count_vm_event(THP_COLLAPSE_ALLOC); | |
ba76149f AA |
2295 | } while (unlikely(!hpage) && |
2296 | likely(khugepaged_enabled())); | |
2297 | return hpage; | |
2298 | } | |
0bbbc0b3 | 2299 | #endif |
ba76149f AA |
2300 | |
2301 | static void khugepaged_loop(void) | |
2302 | { | |
2303 | struct page *hpage; | |
2304 | ||
0bbbc0b3 AA |
2305 | #ifdef CONFIG_NUMA |
2306 | hpage = NULL; | |
2307 | #endif | |
ba76149f | 2308 | while (likely(khugepaged_enabled())) { |
0bbbc0b3 | 2309 | #ifndef CONFIG_NUMA |
ba76149f | 2310 | hpage = khugepaged_alloc_hugepage(); |
f300ea49 | 2311 | if (unlikely(!hpage)) |
ba76149f | 2312 | break; |
0bbbc0b3 AA |
2313 | #else |
2314 | if (IS_ERR(hpage)) { | |
2315 | khugepaged_alloc_sleep(); | |
2316 | hpage = NULL; | |
2317 | } | |
2318 | #endif | |
ba76149f AA |
2319 | |
2320 | khugepaged_do_scan(&hpage); | |
0bbbc0b3 | 2321 | #ifndef CONFIG_NUMA |
ba76149f AA |
2322 | if (hpage) |
2323 | put_page(hpage); | |
0bbbc0b3 | 2324 | #endif |
878aee7d AA |
2325 | try_to_freeze(); |
2326 | if (unlikely(kthread_should_stop())) | |
2327 | break; | |
ba76149f | 2328 | if (khugepaged_has_work()) { |
ba76149f AA |
2329 | if (!khugepaged_scan_sleep_millisecs) |
2330 | continue; | |
1dfb059b AA |
2331 | wait_event_freezable_timeout(khugepaged_wait, false, |
2332 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs)); | |
ba76149f | 2333 | } else if (khugepaged_enabled()) |
878aee7d AA |
2334 | wait_event_freezable(khugepaged_wait, |
2335 | khugepaged_wait_event()); | |
ba76149f AA |
2336 | } |
2337 | } | |
2338 | ||
2339 | static int khugepaged(void *none) | |
2340 | { | |
2341 | struct mm_slot *mm_slot; | |
2342 | ||
878aee7d | 2343 | set_freezable(); |
ba76149f AA |
2344 | set_user_nice(current, 19); |
2345 | ||
2346 | /* serialize with start_khugepaged() */ | |
2347 | mutex_lock(&khugepaged_mutex); | |
2348 | ||
2349 | for (;;) { | |
2350 | mutex_unlock(&khugepaged_mutex); | |
a7d6e4ec | 2351 | VM_BUG_ON(khugepaged_thread != current); |
ba76149f | 2352 | khugepaged_loop(); |
a7d6e4ec | 2353 | VM_BUG_ON(khugepaged_thread != current); |
ba76149f AA |
2354 | |
2355 | mutex_lock(&khugepaged_mutex); | |
2356 | if (!khugepaged_enabled()) | |
2357 | break; | |
878aee7d AA |
2358 | if (unlikely(kthread_should_stop())) |
2359 | break; | |
ba76149f AA |
2360 | } |
2361 | ||
2362 | spin_lock(&khugepaged_mm_lock); | |
2363 | mm_slot = khugepaged_scan.mm_slot; | |
2364 | khugepaged_scan.mm_slot = NULL; | |
2365 | if (mm_slot) | |
2366 | collect_mm_slot(mm_slot); | |
2367 | spin_unlock(&khugepaged_mm_lock); | |
2368 | ||
2369 | khugepaged_thread = NULL; | |
2370 | mutex_unlock(&khugepaged_mutex); | |
2371 | ||
2372 | return 0; | |
2373 | } | |
2374 | ||
71e3aac0 AA |
2375 | void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd) |
2376 | { | |
2377 | struct page *page; | |
2378 | ||
2379 | spin_lock(&mm->page_table_lock); | |
2380 | if (unlikely(!pmd_trans_huge(*pmd))) { | |
2381 | spin_unlock(&mm->page_table_lock); | |
2382 | return; | |
2383 | } | |
2384 | page = pmd_page(*pmd); | |
2385 | VM_BUG_ON(!page_count(page)); | |
2386 | get_page(page); | |
2387 | spin_unlock(&mm->page_table_lock); | |
2388 | ||
2389 | split_huge_page(page); | |
2390 | ||
2391 | put_page(page); | |
2392 | BUG_ON(pmd_trans_huge(*pmd)); | |
2393 | } | |
94fcc585 AA |
2394 | |
2395 | static void split_huge_page_address(struct mm_struct *mm, | |
2396 | unsigned long address) | |
2397 | { | |
2398 | pgd_t *pgd; | |
2399 | pud_t *pud; | |
2400 | pmd_t *pmd; | |
2401 | ||
2402 | VM_BUG_ON(!(address & ~HPAGE_PMD_MASK)); | |
2403 | ||
2404 | pgd = pgd_offset(mm, address); | |
2405 | if (!pgd_present(*pgd)) | |
2406 | return; | |
2407 | ||
2408 | pud = pud_offset(pgd, address); | |
2409 | if (!pud_present(*pud)) | |
2410 | return; | |
2411 | ||
2412 | pmd = pmd_offset(pud, address); | |
2413 | if (!pmd_present(*pmd)) | |
2414 | return; | |
2415 | /* | |
2416 | * Caller holds the mmap_sem write mode, so a huge pmd cannot | |
2417 | * materialize from under us. | |
2418 | */ | |
2419 | split_huge_page_pmd(mm, pmd); | |
2420 | } | |
2421 | ||
2422 | void __vma_adjust_trans_huge(struct vm_area_struct *vma, | |
2423 | unsigned long start, | |
2424 | unsigned long end, | |
2425 | long adjust_next) | |
2426 | { | |
2427 | /* | |
2428 | * If the new start address isn't hpage aligned and it could | |
2429 | * previously contain an hugepage: check if we need to split | |
2430 | * an huge pmd. | |
2431 | */ | |
2432 | if (start & ~HPAGE_PMD_MASK && | |
2433 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
2434 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2435 | split_huge_page_address(vma->vm_mm, start); | |
2436 | ||
2437 | /* | |
2438 | * If the new end address isn't hpage aligned and it could | |
2439 | * previously contain an hugepage: check if we need to split | |
2440 | * an huge pmd. | |
2441 | */ | |
2442 | if (end & ~HPAGE_PMD_MASK && | |
2443 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
2444 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2445 | split_huge_page_address(vma->vm_mm, end); | |
2446 | ||
2447 | /* | |
2448 | * If we're also updating the vma->vm_next->vm_start, if the new | |
2449 | * vm_next->vm_start isn't page aligned and it could previously | |
2450 | * contain an hugepage: check if we need to split an huge pmd. | |
2451 | */ | |
2452 | if (adjust_next > 0) { | |
2453 | struct vm_area_struct *next = vma->vm_next; | |
2454 | unsigned long nstart = next->vm_start; | |
2455 | nstart += adjust_next << PAGE_SHIFT; | |
2456 | if (nstart & ~HPAGE_PMD_MASK && | |
2457 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
2458 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
2459 | split_huge_page_address(next->vm_mm, nstart); | |
2460 | } | |
2461 | } |