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; | |
92 | } khugepaged_scan = { | |
93 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), | |
94 | }; | |
95 | ||
f000565a AA |
96 | |
97 | static int set_recommended_min_free_kbytes(void) | |
98 | { | |
99 | struct zone *zone; | |
100 | int nr_zones = 0; | |
101 | unsigned long recommended_min; | |
102 | extern int min_free_kbytes; | |
103 | ||
104 | if (!test_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
105 | &transparent_hugepage_flags) && | |
106 | !test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
107 | &transparent_hugepage_flags)) | |
108 | return 0; | |
109 | ||
110 | for_each_populated_zone(zone) | |
111 | nr_zones++; | |
112 | ||
113 | /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */ | |
114 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
115 | ||
116 | /* | |
117 | * Make sure that on average at least two pageblocks are almost free | |
118 | * of another type, one for a migratetype to fall back to and a | |
119 | * second to avoid subsequent fallbacks of other types There are 3 | |
120 | * MIGRATE_TYPES we care about. | |
121 | */ | |
122 | recommended_min += pageblock_nr_pages * nr_zones * | |
123 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
124 | ||
125 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
126 | recommended_min = min(recommended_min, | |
127 | (unsigned long) nr_free_buffer_pages() / 20); | |
128 | recommended_min <<= (PAGE_SHIFT-10); | |
129 | ||
130 | if (recommended_min > min_free_kbytes) | |
131 | min_free_kbytes = recommended_min; | |
132 | setup_per_zone_wmarks(); | |
133 | return 0; | |
134 | } | |
135 | late_initcall(set_recommended_min_free_kbytes); | |
136 | ||
ba76149f AA |
137 | static int start_khugepaged(void) |
138 | { | |
139 | int err = 0; | |
140 | if (khugepaged_enabled()) { | |
141 | int wakeup; | |
142 | if (unlikely(!mm_slot_cache || !mm_slots_hash)) { | |
143 | err = -ENOMEM; | |
144 | goto out; | |
145 | } | |
146 | mutex_lock(&khugepaged_mutex); | |
147 | if (!khugepaged_thread) | |
148 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
149 | "khugepaged"); | |
150 | if (unlikely(IS_ERR(khugepaged_thread))) { | |
151 | printk(KERN_ERR | |
152 | "khugepaged: kthread_run(khugepaged) failed\n"); | |
153 | err = PTR_ERR(khugepaged_thread); | |
154 | khugepaged_thread = NULL; | |
155 | } | |
156 | wakeup = !list_empty(&khugepaged_scan.mm_head); | |
157 | mutex_unlock(&khugepaged_mutex); | |
158 | if (wakeup) | |
159 | wake_up_interruptible(&khugepaged_wait); | |
f000565a AA |
160 | |
161 | set_recommended_min_free_kbytes(); | |
ba76149f AA |
162 | } else |
163 | /* wakeup to exit */ | |
164 | wake_up_interruptible(&khugepaged_wait); | |
165 | out: | |
166 | return err; | |
167 | } | |
71e3aac0 AA |
168 | |
169 | #ifdef CONFIG_SYSFS | |
ba76149f | 170 | |
71e3aac0 AA |
171 | static ssize_t double_flag_show(struct kobject *kobj, |
172 | struct kobj_attribute *attr, char *buf, | |
173 | enum transparent_hugepage_flag enabled, | |
174 | enum transparent_hugepage_flag req_madv) | |
175 | { | |
176 | if (test_bit(enabled, &transparent_hugepage_flags)) { | |
177 | VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags)); | |
178 | return sprintf(buf, "[always] madvise never\n"); | |
179 | } else if (test_bit(req_madv, &transparent_hugepage_flags)) | |
180 | return sprintf(buf, "always [madvise] never\n"); | |
181 | else | |
182 | return sprintf(buf, "always madvise [never]\n"); | |
183 | } | |
184 | static ssize_t double_flag_store(struct kobject *kobj, | |
185 | struct kobj_attribute *attr, | |
186 | const char *buf, size_t count, | |
187 | enum transparent_hugepage_flag enabled, | |
188 | enum transparent_hugepage_flag req_madv) | |
189 | { | |
190 | if (!memcmp("always", buf, | |
191 | min(sizeof("always")-1, count))) { | |
192 | set_bit(enabled, &transparent_hugepage_flags); | |
193 | clear_bit(req_madv, &transparent_hugepage_flags); | |
194 | } else if (!memcmp("madvise", buf, | |
195 | min(sizeof("madvise")-1, count))) { | |
196 | clear_bit(enabled, &transparent_hugepage_flags); | |
197 | set_bit(req_madv, &transparent_hugepage_flags); | |
198 | } else if (!memcmp("never", buf, | |
199 | min(sizeof("never")-1, count))) { | |
200 | clear_bit(enabled, &transparent_hugepage_flags); | |
201 | clear_bit(req_madv, &transparent_hugepage_flags); | |
202 | } else | |
203 | return -EINVAL; | |
204 | ||
205 | return count; | |
206 | } | |
207 | ||
208 | static ssize_t enabled_show(struct kobject *kobj, | |
209 | struct kobj_attribute *attr, char *buf) | |
210 | { | |
211 | return double_flag_show(kobj, attr, buf, | |
212 | TRANSPARENT_HUGEPAGE_FLAG, | |
213 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
214 | } | |
215 | static ssize_t enabled_store(struct kobject *kobj, | |
216 | struct kobj_attribute *attr, | |
217 | const char *buf, size_t count) | |
218 | { | |
ba76149f AA |
219 | ssize_t ret; |
220 | ||
221 | ret = double_flag_store(kobj, attr, buf, count, | |
222 | TRANSPARENT_HUGEPAGE_FLAG, | |
223 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
224 | ||
225 | if (ret > 0) { | |
226 | int err = start_khugepaged(); | |
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 | { | |
247 | if (test_bit(flag, &transparent_hugepage_flags)) | |
248 | return sprintf(buf, "[yes] no\n"); | |
249 | else | |
250 | return sprintf(buf, "yes [no]\n"); | |
251 | } | |
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 | { | |
257 | if (!memcmp("yes", buf, | |
258 | min(sizeof("yes")-1, count))) { | |
259 | set_bit(flag, &transparent_hugepage_flags); | |
260 | } else if (!memcmp("no", buf, | |
261 | min(sizeof("no")-1, count))) { | |
262 | clear_bit(flag, &transparent_hugepage_flags); | |
263 | } else | |
264 | return -EINVAL; | |
265 | ||
266 | return count; | |
267 | } | |
268 | ||
269 | /* | |
270 | * Currently defrag only disables __GFP_NOWAIT for allocation. A blind | |
271 | * __GFP_REPEAT is too aggressive, it's never worth swapping tons of | |
272 | * memory just to allocate one more hugepage. | |
273 | */ | |
274 | static ssize_t defrag_show(struct kobject *kobj, | |
275 | struct kobj_attribute *attr, char *buf) | |
276 | { | |
277 | return double_flag_show(kobj, attr, buf, | |
278 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
279 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
280 | } | |
281 | static ssize_t defrag_store(struct kobject *kobj, | |
282 | struct kobj_attribute *attr, | |
283 | const char *buf, size_t count) | |
284 | { | |
285 | return double_flag_store(kobj, attr, buf, count, | |
286 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
287 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
288 | } | |
289 | static struct kobj_attribute defrag_attr = | |
290 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
291 | ||
292 | #ifdef CONFIG_DEBUG_VM | |
293 | static ssize_t debug_cow_show(struct kobject *kobj, | |
294 | struct kobj_attribute *attr, char *buf) | |
295 | { | |
296 | return single_flag_show(kobj, attr, buf, | |
297 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
298 | } | |
299 | static ssize_t debug_cow_store(struct kobject *kobj, | |
300 | struct kobj_attribute *attr, | |
301 | const char *buf, size_t count) | |
302 | { | |
303 | return single_flag_store(kobj, attr, buf, count, | |
304 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
305 | } | |
306 | static struct kobj_attribute debug_cow_attr = | |
307 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
308 | #endif /* CONFIG_DEBUG_VM */ | |
309 | ||
310 | static struct attribute *hugepage_attr[] = { | |
311 | &enabled_attr.attr, | |
312 | &defrag_attr.attr, | |
313 | #ifdef CONFIG_DEBUG_VM | |
314 | &debug_cow_attr.attr, | |
315 | #endif | |
316 | NULL, | |
317 | }; | |
318 | ||
319 | static struct attribute_group hugepage_attr_group = { | |
320 | .attrs = hugepage_attr, | |
ba76149f AA |
321 | }; |
322 | ||
323 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, | |
324 | struct kobj_attribute *attr, | |
325 | char *buf) | |
326 | { | |
327 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
328 | } | |
329 | ||
330 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
331 | struct kobj_attribute *attr, | |
332 | const char *buf, size_t count) | |
333 | { | |
334 | unsigned long msecs; | |
335 | int err; | |
336 | ||
337 | err = strict_strtoul(buf, 10, &msecs); | |
338 | if (err || msecs > UINT_MAX) | |
339 | return -EINVAL; | |
340 | ||
341 | khugepaged_scan_sleep_millisecs = msecs; | |
342 | wake_up_interruptible(&khugepaged_wait); | |
343 | ||
344 | return count; | |
345 | } | |
346 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
347 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
348 | scan_sleep_millisecs_store); | |
349 | ||
350 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
351 | struct kobj_attribute *attr, | |
352 | char *buf) | |
353 | { | |
354 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
355 | } | |
356 | ||
357 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
358 | struct kobj_attribute *attr, | |
359 | const char *buf, size_t count) | |
360 | { | |
361 | unsigned long msecs; | |
362 | int err; | |
363 | ||
364 | err = strict_strtoul(buf, 10, &msecs); | |
365 | if (err || msecs > UINT_MAX) | |
366 | return -EINVAL; | |
367 | ||
368 | khugepaged_alloc_sleep_millisecs = msecs; | |
369 | wake_up_interruptible(&khugepaged_wait); | |
370 | ||
371 | return count; | |
372 | } | |
373 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
374 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
375 | alloc_sleep_millisecs_store); | |
376 | ||
377 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
378 | struct kobj_attribute *attr, | |
379 | char *buf) | |
380 | { | |
381 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
382 | } | |
383 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
384 | struct kobj_attribute *attr, | |
385 | const char *buf, size_t count) | |
386 | { | |
387 | int err; | |
388 | unsigned long pages; | |
389 | ||
390 | err = strict_strtoul(buf, 10, &pages); | |
391 | if (err || !pages || pages > UINT_MAX) | |
392 | return -EINVAL; | |
393 | ||
394 | khugepaged_pages_to_scan = pages; | |
395 | ||
396 | return count; | |
397 | } | |
398 | static struct kobj_attribute pages_to_scan_attr = | |
399 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
400 | pages_to_scan_store); | |
401 | ||
402 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
403 | struct kobj_attribute *attr, | |
404 | char *buf) | |
405 | { | |
406 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
407 | } | |
408 | static struct kobj_attribute pages_collapsed_attr = | |
409 | __ATTR_RO(pages_collapsed); | |
410 | ||
411 | static ssize_t full_scans_show(struct kobject *kobj, | |
412 | struct kobj_attribute *attr, | |
413 | char *buf) | |
414 | { | |
415 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
416 | } | |
417 | static struct kobj_attribute full_scans_attr = | |
418 | __ATTR_RO(full_scans); | |
419 | ||
420 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
421 | struct kobj_attribute *attr, char *buf) | |
422 | { | |
423 | return single_flag_show(kobj, attr, buf, | |
424 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
425 | } | |
426 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
427 | struct kobj_attribute *attr, | |
428 | const char *buf, size_t count) | |
429 | { | |
430 | return single_flag_store(kobj, attr, buf, count, | |
431 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
432 | } | |
433 | static struct kobj_attribute khugepaged_defrag_attr = | |
434 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
435 | khugepaged_defrag_store); | |
436 | ||
437 | /* | |
438 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
439 | * any unmapped ptes in turn potentially increasing the memory | |
440 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
441 | * reduce the available free memory in the system as it | |
442 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
443 | * free memory in the system during the khugepaged scan. | |
444 | */ | |
445 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
446 | struct kobj_attribute *attr, | |
447 | char *buf) | |
448 | { | |
449 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
450 | } | |
451 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
452 | struct kobj_attribute *attr, | |
453 | const char *buf, size_t count) | |
454 | { | |
455 | int err; | |
456 | unsigned long max_ptes_none; | |
457 | ||
458 | err = strict_strtoul(buf, 10, &max_ptes_none); | |
459 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
460 | return -EINVAL; | |
461 | ||
462 | khugepaged_max_ptes_none = max_ptes_none; | |
463 | ||
464 | return count; | |
465 | } | |
466 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
467 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
468 | khugepaged_max_ptes_none_store); | |
469 | ||
470 | static struct attribute *khugepaged_attr[] = { | |
471 | &khugepaged_defrag_attr.attr, | |
472 | &khugepaged_max_ptes_none_attr.attr, | |
473 | &pages_to_scan_attr.attr, | |
474 | &pages_collapsed_attr.attr, | |
475 | &full_scans_attr.attr, | |
476 | &scan_sleep_millisecs_attr.attr, | |
477 | &alloc_sleep_millisecs_attr.attr, | |
478 | NULL, | |
479 | }; | |
480 | ||
481 | static struct attribute_group khugepaged_attr_group = { | |
482 | .attrs = khugepaged_attr, | |
483 | .name = "khugepaged", | |
71e3aac0 AA |
484 | }; |
485 | #endif /* CONFIG_SYSFS */ | |
486 | ||
487 | static int __init hugepage_init(void) | |
488 | { | |
71e3aac0 | 489 | int err; |
ba76149f AA |
490 | #ifdef CONFIG_SYSFS |
491 | static struct kobject *hugepage_kobj; | |
4b7167b9 | 492 | #endif |
71e3aac0 | 493 | |
4b7167b9 AA |
494 | err = -EINVAL; |
495 | if (!has_transparent_hugepage()) { | |
496 | transparent_hugepage_flags = 0; | |
497 | goto out; | |
498 | } | |
499 | ||
500 | #ifdef CONFIG_SYSFS | |
ba76149f AA |
501 | err = -ENOMEM; |
502 | hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); | |
503 | if (unlikely(!hugepage_kobj)) { | |
504 | printk(KERN_ERR "hugepage: failed kobject create\n"); | |
505 | goto out; | |
506 | } | |
507 | ||
508 | err = sysfs_create_group(hugepage_kobj, &hugepage_attr_group); | |
509 | if (err) { | |
510 | printk(KERN_ERR "hugepage: failed register hugeage group\n"); | |
511 | goto out; | |
512 | } | |
513 | ||
514 | err = sysfs_create_group(hugepage_kobj, &khugepaged_attr_group); | |
515 | if (err) { | |
516 | printk(KERN_ERR "hugepage: failed register hugeage group\n"); | |
517 | goto out; | |
518 | } | |
71e3aac0 | 519 | #endif |
ba76149f AA |
520 | |
521 | err = khugepaged_slab_init(); | |
522 | if (err) | |
523 | goto out; | |
524 | ||
525 | err = mm_slots_hash_init(); | |
526 | if (err) { | |
527 | khugepaged_slab_free(); | |
528 | goto out; | |
529 | } | |
530 | ||
97562cd2 RR |
531 | /* |
532 | * By default disable transparent hugepages on smaller systems, | |
533 | * where the extra memory used could hurt more than TLB overhead | |
534 | * is likely to save. The admin can still enable it through /sys. | |
535 | */ | |
536 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) | |
537 | transparent_hugepage_flags = 0; | |
538 | ||
ba76149f AA |
539 | start_khugepaged(); |
540 | ||
f000565a AA |
541 | set_recommended_min_free_kbytes(); |
542 | ||
ba76149f AA |
543 | out: |
544 | return err; | |
71e3aac0 AA |
545 | } |
546 | module_init(hugepage_init) | |
547 | ||
548 | static int __init setup_transparent_hugepage(char *str) | |
549 | { | |
550 | int ret = 0; | |
551 | if (!str) | |
552 | goto out; | |
553 | if (!strcmp(str, "always")) { | |
554 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
555 | &transparent_hugepage_flags); | |
556 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
557 | &transparent_hugepage_flags); | |
558 | ret = 1; | |
559 | } else if (!strcmp(str, "madvise")) { | |
560 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
561 | &transparent_hugepage_flags); | |
562 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
563 | &transparent_hugepage_flags); | |
564 | ret = 1; | |
565 | } else if (!strcmp(str, "never")) { | |
566 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
567 | &transparent_hugepage_flags); | |
568 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
569 | &transparent_hugepage_flags); | |
570 | ret = 1; | |
571 | } | |
572 | out: | |
573 | if (!ret) | |
574 | printk(KERN_WARNING | |
575 | "transparent_hugepage= cannot parse, ignored\n"); | |
576 | return ret; | |
577 | } | |
578 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
579 | ||
580 | static void prepare_pmd_huge_pte(pgtable_t pgtable, | |
581 | struct mm_struct *mm) | |
582 | { | |
583 | assert_spin_locked(&mm->page_table_lock); | |
584 | ||
585 | /* FIFO */ | |
586 | if (!mm->pmd_huge_pte) | |
587 | INIT_LIST_HEAD(&pgtable->lru); | |
588 | else | |
589 | list_add(&pgtable->lru, &mm->pmd_huge_pte->lru); | |
590 | mm->pmd_huge_pte = pgtable; | |
591 | } | |
592 | ||
593 | static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) | |
594 | { | |
595 | if (likely(vma->vm_flags & VM_WRITE)) | |
596 | pmd = pmd_mkwrite(pmd); | |
597 | return pmd; | |
598 | } | |
599 | ||
600 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, | |
601 | struct vm_area_struct *vma, | |
602 | unsigned long haddr, pmd_t *pmd, | |
603 | struct page *page) | |
604 | { | |
605 | int ret = 0; | |
606 | pgtable_t pgtable; | |
607 | ||
608 | VM_BUG_ON(!PageCompound(page)); | |
609 | pgtable = pte_alloc_one(mm, haddr); | |
610 | if (unlikely(!pgtable)) { | |
b9bbfbe3 | 611 | mem_cgroup_uncharge_page(page); |
71e3aac0 AA |
612 | put_page(page); |
613 | return VM_FAULT_OOM; | |
614 | } | |
615 | ||
616 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
617 | __SetPageUptodate(page); | |
618 | ||
619 | spin_lock(&mm->page_table_lock); | |
620 | if (unlikely(!pmd_none(*pmd))) { | |
621 | spin_unlock(&mm->page_table_lock); | |
b9bbfbe3 | 622 | mem_cgroup_uncharge_page(page); |
71e3aac0 AA |
623 | put_page(page); |
624 | pte_free(mm, pgtable); | |
625 | } else { | |
626 | pmd_t entry; | |
627 | entry = mk_pmd(page, vma->vm_page_prot); | |
628 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
629 | entry = pmd_mkhuge(entry); | |
630 | /* | |
631 | * The spinlocking to take the lru_lock inside | |
632 | * page_add_new_anon_rmap() acts as a full memory | |
633 | * barrier to be sure clear_huge_page writes become | |
634 | * visible after the set_pmd_at() write. | |
635 | */ | |
636 | page_add_new_anon_rmap(page, vma, haddr); | |
637 | set_pmd_at(mm, haddr, pmd, entry); | |
638 | prepare_pmd_huge_pte(pgtable, mm); | |
639 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
640 | spin_unlock(&mm->page_table_lock); | |
641 | } | |
642 | ||
643 | return ret; | |
644 | } | |
645 | ||
0bbbc0b3 AA |
646 | static inline gfp_t alloc_hugepage_gfpmask(int defrag) |
647 | { | |
648 | return GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT); | |
649 | } | |
650 | ||
651 | static inline struct page *alloc_hugepage_vma(int defrag, | |
652 | struct vm_area_struct *vma, | |
5c4b4be3 | 653 | unsigned long haddr, int nd) |
0bbbc0b3 AA |
654 | { |
655 | return alloc_pages_vma(alloc_hugepage_gfpmask(defrag), | |
5c4b4be3 | 656 | HPAGE_PMD_ORDER, vma, haddr, nd); |
0bbbc0b3 AA |
657 | } |
658 | ||
659 | #ifndef CONFIG_NUMA | |
71e3aac0 AA |
660 | static inline struct page *alloc_hugepage(int defrag) |
661 | { | |
0bbbc0b3 | 662 | return alloc_pages(alloc_hugepage_gfpmask(defrag), |
71e3aac0 AA |
663 | HPAGE_PMD_ORDER); |
664 | } | |
0bbbc0b3 | 665 | #endif |
71e3aac0 AA |
666 | |
667 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
668 | unsigned long address, pmd_t *pmd, | |
669 | unsigned int flags) | |
670 | { | |
671 | struct page *page; | |
672 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
673 | pte_t *pte; | |
674 | ||
675 | if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) { | |
676 | if (unlikely(anon_vma_prepare(vma))) | |
677 | return VM_FAULT_OOM; | |
ba76149f AA |
678 | if (unlikely(khugepaged_enter(vma))) |
679 | return VM_FAULT_OOM; | |
0bbbc0b3 | 680 | page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
5c4b4be3 | 681 | vma, haddr, numa_node_id()); |
71e3aac0 AA |
682 | if (unlikely(!page)) |
683 | goto out; | |
b9bbfbe3 AA |
684 | if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) { |
685 | put_page(page); | |
686 | goto out; | |
687 | } | |
71e3aac0 AA |
688 | |
689 | return __do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page); | |
690 | } | |
691 | out: | |
692 | /* | |
693 | * Use __pte_alloc instead of pte_alloc_map, because we can't | |
694 | * run pte_offset_map on the pmd, if an huge pmd could | |
695 | * materialize from under us from a different thread. | |
696 | */ | |
697 | if (unlikely(__pte_alloc(mm, vma, pmd, address))) | |
698 | return VM_FAULT_OOM; | |
699 | /* if an huge pmd materialized from under us just retry later */ | |
700 | if (unlikely(pmd_trans_huge(*pmd))) | |
701 | return 0; | |
702 | /* | |
703 | * A regular pmd is established and it can't morph into a huge pmd | |
704 | * from under us anymore at this point because we hold the mmap_sem | |
705 | * read mode and khugepaged takes it in write mode. So now it's | |
706 | * safe to run pte_offset_map(). | |
707 | */ | |
708 | pte = pte_offset_map(pmd, address); | |
709 | return handle_pte_fault(mm, vma, address, pte, pmd, flags); | |
710 | } | |
711 | ||
712 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, | |
713 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
714 | struct vm_area_struct *vma) | |
715 | { | |
716 | struct page *src_page; | |
717 | pmd_t pmd; | |
718 | pgtable_t pgtable; | |
719 | int ret; | |
720 | ||
721 | ret = -ENOMEM; | |
722 | pgtable = pte_alloc_one(dst_mm, addr); | |
723 | if (unlikely(!pgtable)) | |
724 | goto out; | |
725 | ||
726 | spin_lock(&dst_mm->page_table_lock); | |
727 | spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING); | |
728 | ||
729 | ret = -EAGAIN; | |
730 | pmd = *src_pmd; | |
731 | if (unlikely(!pmd_trans_huge(pmd))) { | |
732 | pte_free(dst_mm, pgtable); | |
733 | goto out_unlock; | |
734 | } | |
735 | if (unlikely(pmd_trans_splitting(pmd))) { | |
736 | /* split huge page running from under us */ | |
737 | spin_unlock(&src_mm->page_table_lock); | |
738 | spin_unlock(&dst_mm->page_table_lock); | |
739 | pte_free(dst_mm, pgtable); | |
740 | ||
741 | wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */ | |
742 | goto out; | |
743 | } | |
744 | src_page = pmd_page(pmd); | |
745 | VM_BUG_ON(!PageHead(src_page)); | |
746 | get_page(src_page); | |
747 | page_dup_rmap(src_page); | |
748 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
749 | ||
750 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
751 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
752 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
753 | prepare_pmd_huge_pte(pgtable, dst_mm); | |
754 | ||
755 | ret = 0; | |
756 | out_unlock: | |
757 | spin_unlock(&src_mm->page_table_lock); | |
758 | spin_unlock(&dst_mm->page_table_lock); | |
759 | out: | |
760 | return ret; | |
761 | } | |
762 | ||
763 | /* no "address" argument so destroys page coloring of some arch */ | |
764 | pgtable_t get_pmd_huge_pte(struct mm_struct *mm) | |
765 | { | |
766 | pgtable_t pgtable; | |
767 | ||
768 | assert_spin_locked(&mm->page_table_lock); | |
769 | ||
770 | /* FIFO */ | |
771 | pgtable = mm->pmd_huge_pte; | |
772 | if (list_empty(&pgtable->lru)) | |
773 | mm->pmd_huge_pte = NULL; | |
774 | else { | |
775 | mm->pmd_huge_pte = list_entry(pgtable->lru.next, | |
776 | struct page, lru); | |
777 | list_del(&pgtable->lru); | |
778 | } | |
779 | return pgtable; | |
780 | } | |
781 | ||
782 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, | |
783 | struct vm_area_struct *vma, | |
784 | unsigned long address, | |
785 | pmd_t *pmd, pmd_t orig_pmd, | |
786 | struct page *page, | |
787 | unsigned long haddr) | |
788 | { | |
789 | pgtable_t pgtable; | |
790 | pmd_t _pmd; | |
791 | int ret = 0, i; | |
792 | struct page **pages; | |
793 | ||
794 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
795 | GFP_KERNEL); | |
796 | if (unlikely(!pages)) { | |
797 | ret |= VM_FAULT_OOM; | |
798 | goto out; | |
799 | } | |
800 | ||
801 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
19ee151e AK |
802 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, |
803 | vma, address, page_to_nid(page)); | |
b9bbfbe3 AA |
804 | if (unlikely(!pages[i] || |
805 | mem_cgroup_newpage_charge(pages[i], mm, | |
806 | GFP_KERNEL))) { | |
807 | if (pages[i]) | |
71e3aac0 | 808 | put_page(pages[i]); |
b9bbfbe3 AA |
809 | mem_cgroup_uncharge_start(); |
810 | while (--i >= 0) { | |
811 | mem_cgroup_uncharge_page(pages[i]); | |
812 | put_page(pages[i]); | |
813 | } | |
814 | mem_cgroup_uncharge_end(); | |
71e3aac0 AA |
815 | kfree(pages); |
816 | ret |= VM_FAULT_OOM; | |
817 | goto out; | |
818 | } | |
819 | } | |
820 | ||
821 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
822 | copy_user_highpage(pages[i], page + i, | |
823 | haddr + PAGE_SHIFT*i, vma); | |
824 | __SetPageUptodate(pages[i]); | |
825 | cond_resched(); | |
826 | } | |
827 | ||
828 | spin_lock(&mm->page_table_lock); | |
829 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
830 | goto out_free_pages; | |
831 | VM_BUG_ON(!PageHead(page)); | |
832 | ||
833 | pmdp_clear_flush_notify(vma, haddr, pmd); | |
834 | /* leave pmd empty until pte is filled */ | |
835 | ||
836 | pgtable = get_pmd_huge_pte(mm); | |
837 | pmd_populate(mm, &_pmd, pgtable); | |
838 | ||
839 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
840 | pte_t *pte, entry; | |
841 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
842 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
843 | page_add_new_anon_rmap(pages[i], vma, haddr); | |
844 | pte = pte_offset_map(&_pmd, haddr); | |
845 | VM_BUG_ON(!pte_none(*pte)); | |
846 | set_pte_at(mm, haddr, pte, entry); | |
847 | pte_unmap(pte); | |
848 | } | |
849 | kfree(pages); | |
850 | ||
851 | mm->nr_ptes++; | |
852 | smp_wmb(); /* make pte visible before pmd */ | |
853 | pmd_populate(mm, pmd, pgtable); | |
854 | page_remove_rmap(page); | |
855 | spin_unlock(&mm->page_table_lock); | |
856 | ||
857 | ret |= VM_FAULT_WRITE; | |
858 | put_page(page); | |
859 | ||
860 | out: | |
861 | return ret; | |
862 | ||
863 | out_free_pages: | |
864 | spin_unlock(&mm->page_table_lock); | |
b9bbfbe3 AA |
865 | mem_cgroup_uncharge_start(); |
866 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
867 | mem_cgroup_uncharge_page(pages[i]); | |
71e3aac0 | 868 | put_page(pages[i]); |
b9bbfbe3 AA |
869 | } |
870 | mem_cgroup_uncharge_end(); | |
71e3aac0 AA |
871 | kfree(pages); |
872 | goto out; | |
873 | } | |
874 | ||
875 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
876 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) | |
877 | { | |
878 | int ret = 0; | |
879 | struct page *page, *new_page; | |
880 | unsigned long haddr; | |
881 | ||
882 | VM_BUG_ON(!vma->anon_vma); | |
883 | spin_lock(&mm->page_table_lock); | |
884 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
885 | goto out_unlock; | |
886 | ||
887 | page = pmd_page(orig_pmd); | |
888 | VM_BUG_ON(!PageCompound(page) || !PageHead(page)); | |
889 | haddr = address & HPAGE_PMD_MASK; | |
890 | if (page_mapcount(page) == 1) { | |
891 | pmd_t entry; | |
892 | entry = pmd_mkyoung(orig_pmd); | |
893 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
894 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) | |
895 | update_mmu_cache(vma, address, entry); | |
896 | ret |= VM_FAULT_WRITE; | |
897 | goto out_unlock; | |
898 | } | |
899 | get_page(page); | |
900 | spin_unlock(&mm->page_table_lock); | |
901 | ||
902 | if (transparent_hugepage_enabled(vma) && | |
903 | !transparent_hugepage_debug_cow()) | |
0bbbc0b3 | 904 | new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
5c4b4be3 | 905 | vma, haddr, numa_node_id()); |
71e3aac0 AA |
906 | else |
907 | new_page = NULL; | |
908 | ||
909 | if (unlikely(!new_page)) { | |
910 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, | |
911 | pmd, orig_pmd, page, haddr); | |
912 | put_page(page); | |
913 | goto out; | |
914 | } | |
915 | ||
b9bbfbe3 AA |
916 | if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) { |
917 | put_page(new_page); | |
918 | put_page(page); | |
919 | ret |= VM_FAULT_OOM; | |
920 | goto out; | |
921 | } | |
922 | ||
71e3aac0 AA |
923 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); |
924 | __SetPageUptodate(new_page); | |
925 | ||
926 | spin_lock(&mm->page_table_lock); | |
927 | put_page(page); | |
b9bbfbe3 AA |
928 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { |
929 | mem_cgroup_uncharge_page(new_page); | |
71e3aac0 | 930 | put_page(new_page); |
b9bbfbe3 | 931 | } else { |
71e3aac0 AA |
932 | pmd_t entry; |
933 | VM_BUG_ON(!PageHead(page)); | |
934 | entry = mk_pmd(new_page, vma->vm_page_prot); | |
935 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
936 | entry = pmd_mkhuge(entry); | |
937 | pmdp_clear_flush_notify(vma, haddr, pmd); | |
938 | page_add_new_anon_rmap(new_page, vma, haddr); | |
939 | set_pmd_at(mm, haddr, pmd, entry); | |
940 | update_mmu_cache(vma, address, entry); | |
941 | page_remove_rmap(page); | |
942 | put_page(page); | |
943 | ret |= VM_FAULT_WRITE; | |
944 | } | |
945 | out_unlock: | |
946 | spin_unlock(&mm->page_table_lock); | |
947 | out: | |
948 | return ret; | |
949 | } | |
950 | ||
951 | struct page *follow_trans_huge_pmd(struct mm_struct *mm, | |
952 | unsigned long addr, | |
953 | pmd_t *pmd, | |
954 | unsigned int flags) | |
955 | { | |
956 | struct page *page = NULL; | |
957 | ||
958 | assert_spin_locked(&mm->page_table_lock); | |
959 | ||
960 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
961 | goto out; | |
962 | ||
963 | page = pmd_page(*pmd); | |
964 | VM_BUG_ON(!PageHead(page)); | |
965 | if (flags & FOLL_TOUCH) { | |
966 | pmd_t _pmd; | |
967 | /* | |
968 | * We should set the dirty bit only for FOLL_WRITE but | |
969 | * for now the dirty bit in the pmd is meaningless. | |
970 | * And if the dirty bit will become meaningful and | |
971 | * we'll only set it with FOLL_WRITE, an atomic | |
972 | * set_bit will be required on the pmd to set the | |
973 | * young bit, instead of the current set_pmd_at. | |
974 | */ | |
975 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
976 | set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd); | |
977 | } | |
978 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; | |
979 | VM_BUG_ON(!PageCompound(page)); | |
980 | if (flags & FOLL_GET) | |
981 | get_page(page); | |
982 | ||
983 | out: | |
984 | return page; | |
985 | } | |
986 | ||
987 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, | |
988 | pmd_t *pmd) | |
989 | { | |
990 | int ret = 0; | |
991 | ||
992 | spin_lock(&tlb->mm->page_table_lock); | |
993 | if (likely(pmd_trans_huge(*pmd))) { | |
994 | if (unlikely(pmd_trans_splitting(*pmd))) { | |
995 | spin_unlock(&tlb->mm->page_table_lock); | |
996 | wait_split_huge_page(vma->anon_vma, | |
997 | pmd); | |
998 | } else { | |
999 | struct page *page; | |
1000 | pgtable_t pgtable; | |
1001 | pgtable = get_pmd_huge_pte(tlb->mm); | |
1002 | page = pmd_page(*pmd); | |
1003 | pmd_clear(pmd); | |
1004 | page_remove_rmap(page); | |
1005 | VM_BUG_ON(page_mapcount(page) < 0); | |
1006 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1007 | VM_BUG_ON(!PageHead(page)); | |
1008 | spin_unlock(&tlb->mm->page_table_lock); | |
1009 | tlb_remove_page(tlb, page); | |
1010 | pte_free(tlb->mm, pgtable); | |
1011 | ret = 1; | |
1012 | } | |
1013 | } else | |
1014 | spin_unlock(&tlb->mm->page_table_lock); | |
1015 | ||
1016 | return ret; | |
1017 | } | |
1018 | ||
0ca1634d JW |
1019 | int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
1020 | unsigned long addr, unsigned long end, | |
1021 | unsigned char *vec) | |
1022 | { | |
1023 | int ret = 0; | |
1024 | ||
1025 | spin_lock(&vma->vm_mm->page_table_lock); | |
1026 | if (likely(pmd_trans_huge(*pmd))) { | |
1027 | ret = !pmd_trans_splitting(*pmd); | |
1028 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1029 | if (unlikely(!ret)) | |
1030 | wait_split_huge_page(vma->anon_vma, pmd); | |
1031 | else { | |
1032 | /* | |
1033 | * All logical pages in the range are present | |
1034 | * if backed by a huge page. | |
1035 | */ | |
1036 | memset(vec, 1, (end - addr) >> PAGE_SHIFT); | |
1037 | } | |
1038 | } else | |
1039 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1040 | ||
1041 | return ret; | |
1042 | } | |
1043 | ||
cd7548ab JW |
1044 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
1045 | unsigned long addr, pgprot_t newprot) | |
1046 | { | |
1047 | struct mm_struct *mm = vma->vm_mm; | |
1048 | int ret = 0; | |
1049 | ||
1050 | spin_lock(&mm->page_table_lock); | |
1051 | if (likely(pmd_trans_huge(*pmd))) { | |
1052 | if (unlikely(pmd_trans_splitting(*pmd))) { | |
1053 | spin_unlock(&mm->page_table_lock); | |
1054 | wait_split_huge_page(vma->anon_vma, pmd); | |
1055 | } else { | |
1056 | pmd_t entry; | |
1057 | ||
1058 | entry = pmdp_get_and_clear(mm, addr, pmd); | |
1059 | entry = pmd_modify(entry, newprot); | |
1060 | set_pmd_at(mm, addr, pmd, entry); | |
1061 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1062 | flush_tlb_range(vma, addr, addr + HPAGE_PMD_SIZE); | |
1063 | ret = 1; | |
1064 | } | |
1065 | } else | |
1066 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1067 | ||
1068 | return ret; | |
1069 | } | |
1070 | ||
71e3aac0 AA |
1071 | pmd_t *page_check_address_pmd(struct page *page, |
1072 | struct mm_struct *mm, | |
1073 | unsigned long address, | |
1074 | enum page_check_address_pmd_flag flag) | |
1075 | { | |
1076 | pgd_t *pgd; | |
1077 | pud_t *pud; | |
1078 | pmd_t *pmd, *ret = NULL; | |
1079 | ||
1080 | if (address & ~HPAGE_PMD_MASK) | |
1081 | goto out; | |
1082 | ||
1083 | pgd = pgd_offset(mm, address); | |
1084 | if (!pgd_present(*pgd)) | |
1085 | goto out; | |
1086 | ||
1087 | pud = pud_offset(pgd, address); | |
1088 | if (!pud_present(*pud)) | |
1089 | goto out; | |
1090 | ||
1091 | pmd = pmd_offset(pud, address); | |
1092 | if (pmd_none(*pmd)) | |
1093 | goto out; | |
1094 | if (pmd_page(*pmd) != page) | |
1095 | goto out; | |
94fcc585 AA |
1096 | /* |
1097 | * split_vma() may create temporary aliased mappings. There is | |
1098 | * no risk as long as all huge pmd are found and have their | |
1099 | * splitting bit set before __split_huge_page_refcount | |
1100 | * runs. Finding the same huge pmd more than once during the | |
1101 | * same rmap walk is not a problem. | |
1102 | */ | |
1103 | if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG && | |
1104 | pmd_trans_splitting(*pmd)) | |
1105 | goto out; | |
71e3aac0 AA |
1106 | if (pmd_trans_huge(*pmd)) { |
1107 | VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG && | |
1108 | !pmd_trans_splitting(*pmd)); | |
1109 | ret = pmd; | |
1110 | } | |
1111 | out: | |
1112 | return ret; | |
1113 | } | |
1114 | ||
1115 | static int __split_huge_page_splitting(struct page *page, | |
1116 | struct vm_area_struct *vma, | |
1117 | unsigned long address) | |
1118 | { | |
1119 | struct mm_struct *mm = vma->vm_mm; | |
1120 | pmd_t *pmd; | |
1121 | int ret = 0; | |
1122 | ||
1123 | spin_lock(&mm->page_table_lock); | |
1124 | pmd = page_check_address_pmd(page, mm, address, | |
1125 | PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG); | |
1126 | if (pmd) { | |
1127 | /* | |
1128 | * We can't temporarily set the pmd to null in order | |
1129 | * to split it, the pmd must remain marked huge at all | |
1130 | * times or the VM won't take the pmd_trans_huge paths | |
1131 | * and it won't wait on the anon_vma->root->lock to | |
1132 | * serialize against split_huge_page*. | |
1133 | */ | |
1134 | pmdp_splitting_flush_notify(vma, address, pmd); | |
1135 | ret = 1; | |
1136 | } | |
1137 | spin_unlock(&mm->page_table_lock); | |
1138 | ||
1139 | return ret; | |
1140 | } | |
1141 | ||
1142 | static void __split_huge_page_refcount(struct page *page) | |
1143 | { | |
1144 | int i; | |
1145 | unsigned long head_index = page->index; | |
1146 | struct zone *zone = page_zone(page); | |
2c888cfb | 1147 | int zonestat; |
71e3aac0 AA |
1148 | |
1149 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
1150 | spin_lock_irq(&zone->lru_lock); | |
1151 | compound_lock(page); | |
1152 | ||
1153 | for (i = 1; i < HPAGE_PMD_NR; i++) { | |
1154 | struct page *page_tail = page + i; | |
1155 | ||
1156 | /* tail_page->_count cannot change */ | |
1157 | atomic_sub(atomic_read(&page_tail->_count), &page->_count); | |
1158 | BUG_ON(page_count(page) <= 0); | |
1159 | atomic_add(page_mapcount(page) + 1, &page_tail->_count); | |
1160 | BUG_ON(atomic_read(&page_tail->_count) <= 0); | |
1161 | ||
1162 | /* after clearing PageTail the gup refcount can be released */ | |
1163 | smp_mb(); | |
1164 | ||
a6d30ddd JD |
1165 | /* |
1166 | * retain hwpoison flag of the poisoned tail page: | |
1167 | * fix for the unsuitable process killed on Guest Machine(KVM) | |
1168 | * by the memory-failure. | |
1169 | */ | |
1170 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON; | |
71e3aac0 AA |
1171 | page_tail->flags |= (page->flags & |
1172 | ((1L << PG_referenced) | | |
1173 | (1L << PG_swapbacked) | | |
1174 | (1L << PG_mlocked) | | |
1175 | (1L << PG_uptodate))); | |
1176 | page_tail->flags |= (1L << PG_dirty); | |
1177 | ||
1178 | /* | |
1179 | * 1) clear PageTail before overwriting first_page | |
1180 | * 2) clear PageTail before clearing PageHead for VM_BUG_ON | |
1181 | */ | |
1182 | smp_wmb(); | |
1183 | ||
1184 | /* | |
1185 | * __split_huge_page_splitting() already set the | |
1186 | * splitting bit in all pmd that could map this | |
1187 | * hugepage, that will ensure no CPU can alter the | |
1188 | * mapcount on the head page. The mapcount is only | |
1189 | * accounted in the head page and it has to be | |
1190 | * transferred to all tail pages in the below code. So | |
1191 | * for this code to be safe, the split the mapcount | |
1192 | * can't change. But that doesn't mean userland can't | |
1193 | * keep changing and reading the page contents while | |
1194 | * we transfer the mapcount, so the pmd splitting | |
1195 | * status is achieved setting a reserved bit in the | |
1196 | * pmd, not by clearing the present bit. | |
1197 | */ | |
1198 | BUG_ON(page_mapcount(page_tail)); | |
1199 | page_tail->_mapcount = page->_mapcount; | |
1200 | ||
1201 | BUG_ON(page_tail->mapping); | |
1202 | page_tail->mapping = page->mapping; | |
1203 | ||
1204 | page_tail->index = ++head_index; | |
1205 | ||
1206 | BUG_ON(!PageAnon(page_tail)); | |
1207 | BUG_ON(!PageUptodate(page_tail)); | |
1208 | BUG_ON(!PageDirty(page_tail)); | |
1209 | BUG_ON(!PageSwapBacked(page_tail)); | |
1210 | ||
ca3e0214 KH |
1211 | mem_cgroup_split_huge_fixup(page, page_tail); |
1212 | ||
71e3aac0 AA |
1213 | lru_add_page_tail(zone, page, page_tail); |
1214 | } | |
1215 | ||
79134171 AA |
1216 | __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); |
1217 | __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR); | |
1218 | ||
2c888cfb RR |
1219 | /* |
1220 | * A hugepage counts for HPAGE_PMD_NR pages on the LRU statistics, | |
1221 | * so adjust those appropriately if this page is on the LRU. | |
1222 | */ | |
1223 | if (PageLRU(page)) { | |
1224 | zonestat = NR_LRU_BASE + page_lru(page); | |
1225 | __mod_zone_page_state(zone, zonestat, -(HPAGE_PMD_NR-1)); | |
1226 | } | |
1227 | ||
71e3aac0 AA |
1228 | ClearPageCompound(page); |
1229 | compound_unlock(page); | |
1230 | spin_unlock_irq(&zone->lru_lock); | |
1231 | ||
1232 | for (i = 1; i < HPAGE_PMD_NR; i++) { | |
1233 | struct page *page_tail = page + i; | |
1234 | BUG_ON(page_count(page_tail) <= 0); | |
1235 | /* | |
1236 | * Tail pages may be freed if there wasn't any mapping | |
1237 | * like if add_to_swap() is running on a lru page that | |
1238 | * had its mapping zapped. And freeing these pages | |
1239 | * requires taking the lru_lock so we do the put_page | |
1240 | * of the tail pages after the split is complete. | |
1241 | */ | |
1242 | put_page(page_tail); | |
1243 | } | |
1244 | ||
1245 | /* | |
1246 | * Only the head page (now become a regular page) is required | |
1247 | * to be pinned by the caller. | |
1248 | */ | |
1249 | BUG_ON(page_count(page) <= 0); | |
1250 | } | |
1251 | ||
1252 | static int __split_huge_page_map(struct page *page, | |
1253 | struct vm_area_struct *vma, | |
1254 | unsigned long address) | |
1255 | { | |
1256 | struct mm_struct *mm = vma->vm_mm; | |
1257 | pmd_t *pmd, _pmd; | |
1258 | int ret = 0, i; | |
1259 | pgtable_t pgtable; | |
1260 | unsigned long haddr; | |
1261 | ||
1262 | spin_lock(&mm->page_table_lock); | |
1263 | pmd = page_check_address_pmd(page, mm, address, | |
1264 | PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG); | |
1265 | if (pmd) { | |
1266 | pgtable = get_pmd_huge_pte(mm); | |
1267 | pmd_populate(mm, &_pmd, pgtable); | |
1268 | ||
1269 | for (i = 0, haddr = address; i < HPAGE_PMD_NR; | |
1270 | i++, haddr += PAGE_SIZE) { | |
1271 | pte_t *pte, entry; | |
1272 | BUG_ON(PageCompound(page+i)); | |
1273 | entry = mk_pte(page + i, vma->vm_page_prot); | |
1274 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
1275 | if (!pmd_write(*pmd)) | |
1276 | entry = pte_wrprotect(entry); | |
1277 | else | |
1278 | BUG_ON(page_mapcount(page) != 1); | |
1279 | if (!pmd_young(*pmd)) | |
1280 | entry = pte_mkold(entry); | |
1281 | pte = pte_offset_map(&_pmd, haddr); | |
1282 | BUG_ON(!pte_none(*pte)); | |
1283 | set_pte_at(mm, haddr, pte, entry); | |
1284 | pte_unmap(pte); | |
1285 | } | |
1286 | ||
1287 | mm->nr_ptes++; | |
1288 | smp_wmb(); /* make pte visible before pmd */ | |
1289 | /* | |
1290 | * Up to this point the pmd is present and huge and | |
1291 | * userland has the whole access to the hugepage | |
1292 | * during the split (which happens in place). If we | |
1293 | * overwrite the pmd with the not-huge version | |
1294 | * pointing to the pte here (which of course we could | |
1295 | * if all CPUs were bug free), userland could trigger | |
1296 | * a small page size TLB miss on the small sized TLB | |
1297 | * while the hugepage TLB entry is still established | |
1298 | * in the huge TLB. Some CPU doesn't like that. See | |
1299 | * http://support.amd.com/us/Processor_TechDocs/41322.pdf, | |
1300 | * Erratum 383 on page 93. Intel should be safe but is | |
1301 | * also warns that it's only safe if the permission | |
1302 | * and cache attributes of the two entries loaded in | |
1303 | * the two TLB is identical (which should be the case | |
1304 | * here). But it is generally safer to never allow | |
1305 | * small and huge TLB entries for the same virtual | |
1306 | * address to be loaded simultaneously. So instead of | |
1307 | * doing "pmd_populate(); flush_tlb_range();" we first | |
1308 | * mark the current pmd notpresent (atomically because | |
1309 | * here the pmd_trans_huge and pmd_trans_splitting | |
1310 | * must remain set at all times on the pmd until the | |
1311 | * split is complete for this pmd), then we flush the | |
1312 | * SMP TLB and finally we write the non-huge version | |
1313 | * of the pmd entry with pmd_populate. | |
1314 | */ | |
1315 | set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd)); | |
1316 | flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); | |
1317 | pmd_populate(mm, pmd, pgtable); | |
1318 | ret = 1; | |
1319 | } | |
1320 | spin_unlock(&mm->page_table_lock); | |
1321 | ||
1322 | return ret; | |
1323 | } | |
1324 | ||
1325 | /* must be called with anon_vma->root->lock hold */ | |
1326 | static void __split_huge_page(struct page *page, | |
1327 | struct anon_vma *anon_vma) | |
1328 | { | |
1329 | int mapcount, mapcount2; | |
1330 | struct anon_vma_chain *avc; | |
1331 | ||
1332 | BUG_ON(!PageHead(page)); | |
1333 | BUG_ON(PageTail(page)); | |
1334 | ||
1335 | mapcount = 0; | |
1336 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { | |
1337 | struct vm_area_struct *vma = avc->vma; | |
1338 | unsigned long addr = vma_address(page, vma); | |
1339 | BUG_ON(is_vma_temporary_stack(vma)); | |
1340 | if (addr == -EFAULT) | |
1341 | continue; | |
1342 | mapcount += __split_huge_page_splitting(page, vma, addr); | |
1343 | } | |
05759d38 AA |
1344 | /* |
1345 | * It is critical that new vmas are added to the tail of the | |
1346 | * anon_vma list. This guarantes that if copy_huge_pmd() runs | |
1347 | * and establishes a child pmd before | |
1348 | * __split_huge_page_splitting() freezes the parent pmd (so if | |
1349 | * we fail to prevent copy_huge_pmd() from running until the | |
1350 | * whole __split_huge_page() is complete), we will still see | |
1351 | * the newly established pmd of the child later during the | |
1352 | * walk, to be able to set it as pmd_trans_splitting too. | |
1353 | */ | |
1354 | if (mapcount != page_mapcount(page)) | |
1355 | printk(KERN_ERR "mapcount %d page_mapcount %d\n", | |
1356 | mapcount, page_mapcount(page)); | |
71e3aac0 AA |
1357 | BUG_ON(mapcount != page_mapcount(page)); |
1358 | ||
1359 | __split_huge_page_refcount(page); | |
1360 | ||
1361 | mapcount2 = 0; | |
1362 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { | |
1363 | struct vm_area_struct *vma = avc->vma; | |
1364 | unsigned long addr = vma_address(page, vma); | |
1365 | BUG_ON(is_vma_temporary_stack(vma)); | |
1366 | if (addr == -EFAULT) | |
1367 | continue; | |
1368 | mapcount2 += __split_huge_page_map(page, vma, addr); | |
1369 | } | |
05759d38 AA |
1370 | if (mapcount != mapcount2) |
1371 | printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n", | |
1372 | mapcount, mapcount2, page_mapcount(page)); | |
71e3aac0 AA |
1373 | BUG_ON(mapcount != mapcount2); |
1374 | } | |
1375 | ||
1376 | int split_huge_page(struct page *page) | |
1377 | { | |
1378 | struct anon_vma *anon_vma; | |
1379 | int ret = 1; | |
1380 | ||
1381 | BUG_ON(!PageAnon(page)); | |
1382 | anon_vma = page_lock_anon_vma(page); | |
1383 | if (!anon_vma) | |
1384 | goto out; | |
1385 | ret = 0; | |
1386 | if (!PageCompound(page)) | |
1387 | goto out_unlock; | |
1388 | ||
1389 | BUG_ON(!PageSwapBacked(page)); | |
1390 | __split_huge_page(page, anon_vma); | |
1391 | ||
1392 | BUG_ON(PageCompound(page)); | |
1393 | out_unlock: | |
1394 | page_unlock_anon_vma(anon_vma); | |
1395 | out: | |
1396 | return ret; | |
1397 | } | |
1398 | ||
60ab3244 AA |
1399 | int hugepage_madvise(struct vm_area_struct *vma, |
1400 | unsigned long *vm_flags, int advice) | |
0af4e98b | 1401 | { |
a664b2d8 AA |
1402 | switch (advice) { |
1403 | case MADV_HUGEPAGE: | |
1404 | /* | |
1405 | * Be somewhat over-protective like KSM for now! | |
1406 | */ | |
1407 | if (*vm_flags & (VM_HUGEPAGE | | |
1408 | VM_SHARED | VM_MAYSHARE | | |
1409 | VM_PFNMAP | VM_IO | VM_DONTEXPAND | | |
1410 | VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE | | |
1411 | VM_MIXEDMAP | VM_SAO)) | |
1412 | return -EINVAL; | |
1413 | *vm_flags &= ~VM_NOHUGEPAGE; | |
1414 | *vm_flags |= VM_HUGEPAGE; | |
60ab3244 AA |
1415 | /* |
1416 | * If the vma become good for khugepaged to scan, | |
1417 | * register it here without waiting a page fault that | |
1418 | * may not happen any time soon. | |
1419 | */ | |
1420 | if (unlikely(khugepaged_enter_vma_merge(vma))) | |
1421 | return -ENOMEM; | |
a664b2d8 AA |
1422 | break; |
1423 | case MADV_NOHUGEPAGE: | |
1424 | /* | |
1425 | * Be somewhat over-protective like KSM for now! | |
1426 | */ | |
1427 | if (*vm_flags & (VM_NOHUGEPAGE | | |
1428 | VM_SHARED | VM_MAYSHARE | | |
1429 | VM_PFNMAP | VM_IO | VM_DONTEXPAND | | |
1430 | VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE | | |
1431 | VM_MIXEDMAP | VM_SAO)) | |
1432 | return -EINVAL; | |
1433 | *vm_flags &= ~VM_HUGEPAGE; | |
1434 | *vm_flags |= VM_NOHUGEPAGE; | |
60ab3244 AA |
1435 | /* |
1436 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
1437 | * this vma even if we leave the mm registered in khugepaged if | |
1438 | * it got registered before VM_NOHUGEPAGE was set. | |
1439 | */ | |
a664b2d8 AA |
1440 | break; |
1441 | } | |
0af4e98b AA |
1442 | |
1443 | return 0; | |
1444 | } | |
1445 | ||
ba76149f AA |
1446 | static int __init khugepaged_slab_init(void) |
1447 | { | |
1448 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
1449 | sizeof(struct mm_slot), | |
1450 | __alignof__(struct mm_slot), 0, NULL); | |
1451 | if (!mm_slot_cache) | |
1452 | return -ENOMEM; | |
1453 | ||
1454 | return 0; | |
1455 | } | |
1456 | ||
1457 | static void __init khugepaged_slab_free(void) | |
1458 | { | |
1459 | kmem_cache_destroy(mm_slot_cache); | |
1460 | mm_slot_cache = NULL; | |
1461 | } | |
1462 | ||
1463 | static inline struct mm_slot *alloc_mm_slot(void) | |
1464 | { | |
1465 | if (!mm_slot_cache) /* initialization failed */ | |
1466 | return NULL; | |
1467 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
1468 | } | |
1469 | ||
1470 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
1471 | { | |
1472 | kmem_cache_free(mm_slot_cache, mm_slot); | |
1473 | } | |
1474 | ||
1475 | static int __init mm_slots_hash_init(void) | |
1476 | { | |
1477 | mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head), | |
1478 | GFP_KERNEL); | |
1479 | if (!mm_slots_hash) | |
1480 | return -ENOMEM; | |
1481 | return 0; | |
1482 | } | |
1483 | ||
1484 | #if 0 | |
1485 | static void __init mm_slots_hash_free(void) | |
1486 | { | |
1487 | kfree(mm_slots_hash); | |
1488 | mm_slots_hash = NULL; | |
1489 | } | |
1490 | #endif | |
1491 | ||
1492 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
1493 | { | |
1494 | struct mm_slot *mm_slot; | |
1495 | struct hlist_head *bucket; | |
1496 | struct hlist_node *node; | |
1497 | ||
1498 | bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct)) | |
1499 | % MM_SLOTS_HASH_HEADS]; | |
1500 | hlist_for_each_entry(mm_slot, node, bucket, hash) { | |
1501 | if (mm == mm_slot->mm) | |
1502 | return mm_slot; | |
1503 | } | |
1504 | return NULL; | |
1505 | } | |
1506 | ||
1507 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
1508 | struct mm_slot *mm_slot) | |
1509 | { | |
1510 | struct hlist_head *bucket; | |
1511 | ||
1512 | bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct)) | |
1513 | % MM_SLOTS_HASH_HEADS]; | |
1514 | mm_slot->mm = mm; | |
1515 | hlist_add_head(&mm_slot->hash, bucket); | |
1516 | } | |
1517 | ||
1518 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
1519 | { | |
1520 | return atomic_read(&mm->mm_users) == 0; | |
1521 | } | |
1522 | ||
1523 | int __khugepaged_enter(struct mm_struct *mm) | |
1524 | { | |
1525 | struct mm_slot *mm_slot; | |
1526 | int wakeup; | |
1527 | ||
1528 | mm_slot = alloc_mm_slot(); | |
1529 | if (!mm_slot) | |
1530 | return -ENOMEM; | |
1531 | ||
1532 | /* __khugepaged_exit() must not run from under us */ | |
1533 | VM_BUG_ON(khugepaged_test_exit(mm)); | |
1534 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { | |
1535 | free_mm_slot(mm_slot); | |
1536 | return 0; | |
1537 | } | |
1538 | ||
1539 | spin_lock(&khugepaged_mm_lock); | |
1540 | insert_to_mm_slots_hash(mm, mm_slot); | |
1541 | /* | |
1542 | * Insert just behind the scanning cursor, to let the area settle | |
1543 | * down a little. | |
1544 | */ | |
1545 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
1546 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
1547 | spin_unlock(&khugepaged_mm_lock); | |
1548 | ||
1549 | atomic_inc(&mm->mm_count); | |
1550 | if (wakeup) | |
1551 | wake_up_interruptible(&khugepaged_wait); | |
1552 | ||
1553 | return 0; | |
1554 | } | |
1555 | ||
1556 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma) | |
1557 | { | |
1558 | unsigned long hstart, hend; | |
1559 | if (!vma->anon_vma) | |
1560 | /* | |
1561 | * Not yet faulted in so we will register later in the | |
1562 | * page fault if needed. | |
1563 | */ | |
1564 | return 0; | |
1565 | if (vma->vm_file || vma->vm_ops) | |
1566 | /* khugepaged not yet working on file or special mappings */ | |
1567 | return 0; | |
1568 | VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma)); | |
1569 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
1570 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1571 | if (hstart < hend) | |
1572 | return khugepaged_enter(vma); | |
1573 | return 0; | |
1574 | } | |
1575 | ||
1576 | void __khugepaged_exit(struct mm_struct *mm) | |
1577 | { | |
1578 | struct mm_slot *mm_slot; | |
1579 | int free = 0; | |
1580 | ||
1581 | spin_lock(&khugepaged_mm_lock); | |
1582 | mm_slot = get_mm_slot(mm); | |
1583 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
1584 | hlist_del(&mm_slot->hash); | |
1585 | list_del(&mm_slot->mm_node); | |
1586 | free = 1; | |
1587 | } | |
1588 | ||
1589 | if (free) { | |
1590 | spin_unlock(&khugepaged_mm_lock); | |
1591 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1592 | free_mm_slot(mm_slot); | |
1593 | mmdrop(mm); | |
1594 | } else if (mm_slot) { | |
1595 | spin_unlock(&khugepaged_mm_lock); | |
1596 | /* | |
1597 | * This is required to serialize against | |
1598 | * khugepaged_test_exit() (which is guaranteed to run | |
1599 | * under mmap sem read mode). Stop here (after we | |
1600 | * return all pagetables will be destroyed) until | |
1601 | * khugepaged has finished working on the pagetables | |
1602 | * under the mmap_sem. | |
1603 | */ | |
1604 | down_write(&mm->mmap_sem); | |
1605 | up_write(&mm->mmap_sem); | |
1606 | } else | |
1607 | spin_unlock(&khugepaged_mm_lock); | |
1608 | } | |
1609 | ||
1610 | static void release_pte_page(struct page *page) | |
1611 | { | |
1612 | /* 0 stands for page_is_file_cache(page) == false */ | |
1613 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
1614 | unlock_page(page); | |
1615 | putback_lru_page(page); | |
1616 | } | |
1617 | ||
1618 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
1619 | { | |
1620 | while (--_pte >= pte) { | |
1621 | pte_t pteval = *_pte; | |
1622 | if (!pte_none(pteval)) | |
1623 | release_pte_page(pte_page(pteval)); | |
1624 | } | |
1625 | } | |
1626 | ||
1627 | static void release_all_pte_pages(pte_t *pte) | |
1628 | { | |
1629 | release_pte_pages(pte, pte + HPAGE_PMD_NR); | |
1630 | } | |
1631 | ||
1632 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, | |
1633 | unsigned long address, | |
1634 | pte_t *pte) | |
1635 | { | |
1636 | struct page *page; | |
1637 | pte_t *_pte; | |
1638 | int referenced = 0, isolated = 0, none = 0; | |
1639 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1640 | _pte++, address += PAGE_SIZE) { | |
1641 | pte_t pteval = *_pte; | |
1642 | if (pte_none(pteval)) { | |
1643 | if (++none <= khugepaged_max_ptes_none) | |
1644 | continue; | |
1645 | else { | |
1646 | release_pte_pages(pte, _pte); | |
1647 | goto out; | |
1648 | } | |
1649 | } | |
1650 | if (!pte_present(pteval) || !pte_write(pteval)) { | |
1651 | release_pte_pages(pte, _pte); | |
1652 | goto out; | |
1653 | } | |
1654 | page = vm_normal_page(vma, address, pteval); | |
1655 | if (unlikely(!page)) { | |
1656 | release_pte_pages(pte, _pte); | |
1657 | goto out; | |
1658 | } | |
1659 | VM_BUG_ON(PageCompound(page)); | |
1660 | BUG_ON(!PageAnon(page)); | |
1661 | VM_BUG_ON(!PageSwapBacked(page)); | |
1662 | ||
1663 | /* cannot use mapcount: can't collapse if there's a gup pin */ | |
1664 | if (page_count(page) != 1) { | |
1665 | release_pte_pages(pte, _pte); | |
1666 | goto out; | |
1667 | } | |
1668 | /* | |
1669 | * We can do it before isolate_lru_page because the | |
1670 | * page can't be freed from under us. NOTE: PG_lock | |
1671 | * is needed to serialize against split_huge_page | |
1672 | * when invoked from the VM. | |
1673 | */ | |
1674 | if (!trylock_page(page)) { | |
1675 | release_pte_pages(pte, _pte); | |
1676 | goto out; | |
1677 | } | |
1678 | /* | |
1679 | * Isolate the page to avoid collapsing an hugepage | |
1680 | * currently in use by the VM. | |
1681 | */ | |
1682 | if (isolate_lru_page(page)) { | |
1683 | unlock_page(page); | |
1684 | release_pte_pages(pte, _pte); | |
1685 | goto out; | |
1686 | } | |
1687 | /* 0 stands for page_is_file_cache(page) == false */ | |
1688 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
1689 | VM_BUG_ON(!PageLocked(page)); | |
1690 | VM_BUG_ON(PageLRU(page)); | |
1691 | ||
1692 | /* If there is no mapped pte young don't collapse the page */ | |
8ee53820 AA |
1693 | if (pte_young(pteval) || PageReferenced(page) || |
1694 | mmu_notifier_test_young(vma->vm_mm, address)) | |
ba76149f AA |
1695 | referenced = 1; |
1696 | } | |
1697 | if (unlikely(!referenced)) | |
1698 | release_all_pte_pages(pte); | |
1699 | else | |
1700 | isolated = 1; | |
1701 | out: | |
1702 | return isolated; | |
1703 | } | |
1704 | ||
1705 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
1706 | struct vm_area_struct *vma, | |
1707 | unsigned long address, | |
1708 | spinlock_t *ptl) | |
1709 | { | |
1710 | pte_t *_pte; | |
1711 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { | |
1712 | pte_t pteval = *_pte; | |
1713 | struct page *src_page; | |
1714 | ||
1715 | if (pte_none(pteval)) { | |
1716 | clear_user_highpage(page, address); | |
1717 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
1718 | } else { | |
1719 | src_page = pte_page(pteval); | |
1720 | copy_user_highpage(page, src_page, address, vma); | |
1721 | VM_BUG_ON(page_mapcount(src_page) != 1); | |
1722 | VM_BUG_ON(page_count(src_page) != 2); | |
1723 | release_pte_page(src_page); | |
1724 | /* | |
1725 | * ptl mostly unnecessary, but preempt has to | |
1726 | * be disabled to update the per-cpu stats | |
1727 | * inside page_remove_rmap(). | |
1728 | */ | |
1729 | spin_lock(ptl); | |
1730 | /* | |
1731 | * paravirt calls inside pte_clear here are | |
1732 | * superfluous. | |
1733 | */ | |
1734 | pte_clear(vma->vm_mm, address, _pte); | |
1735 | page_remove_rmap(src_page); | |
1736 | spin_unlock(ptl); | |
1737 | free_page_and_swap_cache(src_page); | |
1738 | } | |
1739 | ||
1740 | address += PAGE_SIZE; | |
1741 | page++; | |
1742 | } | |
1743 | } | |
1744 | ||
1745 | static void collapse_huge_page(struct mm_struct *mm, | |
1746 | unsigned long address, | |
ce83d217 | 1747 | struct page **hpage, |
5c4b4be3 AK |
1748 | struct vm_area_struct *vma, |
1749 | int node) | |
ba76149f | 1750 | { |
ba76149f AA |
1751 | pgd_t *pgd; |
1752 | pud_t *pud; | |
1753 | pmd_t *pmd, _pmd; | |
1754 | pte_t *pte; | |
1755 | pgtable_t pgtable; | |
1756 | struct page *new_page; | |
1757 | spinlock_t *ptl; | |
1758 | int isolated; | |
1759 | unsigned long hstart, hend; | |
1760 | ||
1761 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
0bbbc0b3 | 1762 | #ifndef CONFIG_NUMA |
ba76149f | 1763 | VM_BUG_ON(!*hpage); |
ce83d217 | 1764 | new_page = *hpage; |
0bbbc0b3 AA |
1765 | #else |
1766 | VM_BUG_ON(*hpage); | |
ce83d217 AA |
1767 | /* |
1768 | * Allocate the page while the vma is still valid and under | |
1769 | * the mmap_sem read mode so there is no memory allocation | |
1770 | * later when we take the mmap_sem in write mode. This is more | |
1771 | * friendly behavior (OTOH it may actually hide bugs) to | |
1772 | * filesystems in userland with daemons allocating memory in | |
1773 | * the userland I/O paths. Allocating memory with the | |
1774 | * mmap_sem in read mode is good idea also to allow greater | |
1775 | * scalability. | |
1776 | */ | |
5c4b4be3 AK |
1777 | new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address, |
1778 | node); | |
ce83d217 AA |
1779 | if (unlikely(!new_page)) { |
1780 | up_read(&mm->mmap_sem); | |
1781 | *hpage = ERR_PTR(-ENOMEM); | |
1782 | return; | |
1783 | } | |
0bbbc0b3 | 1784 | #endif |
ce83d217 AA |
1785 | if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) { |
1786 | up_read(&mm->mmap_sem); | |
1787 | put_page(new_page); | |
1788 | return; | |
1789 | } | |
1790 | ||
1791 | /* after allocating the hugepage upgrade to mmap_sem write mode */ | |
1792 | up_read(&mm->mmap_sem); | |
ba76149f AA |
1793 | |
1794 | /* | |
1795 | * Prevent all access to pagetables with the exception of | |
1796 | * gup_fast later hanlded by the ptep_clear_flush and the VM | |
1797 | * handled by the anon_vma lock + PG_lock. | |
1798 | */ | |
1799 | down_write(&mm->mmap_sem); | |
1800 | if (unlikely(khugepaged_test_exit(mm))) | |
1801 | goto out; | |
1802 | ||
1803 | vma = find_vma(mm, address); | |
1804 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
1805 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1806 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
1807 | goto out; | |
1808 | ||
60ab3244 AA |
1809 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || |
1810 | (vma->vm_flags & VM_NOHUGEPAGE)) | |
ba76149f AA |
1811 | goto out; |
1812 | ||
1813 | /* VM_PFNMAP vmas may have vm_ops null but vm_file set */ | |
1814 | if (!vma->anon_vma || vma->vm_ops || vma->vm_file) | |
1815 | goto out; | |
a7d6e4ec AA |
1816 | if (is_vma_temporary_stack(vma)) |
1817 | goto out; | |
ba76149f AA |
1818 | VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma)); |
1819 | ||
1820 | pgd = pgd_offset(mm, address); | |
1821 | if (!pgd_present(*pgd)) | |
1822 | goto out; | |
1823 | ||
1824 | pud = pud_offset(pgd, address); | |
1825 | if (!pud_present(*pud)) | |
1826 | goto out; | |
1827 | ||
1828 | pmd = pmd_offset(pud, address); | |
1829 | /* pmd can't go away or become huge under us */ | |
1830 | if (!pmd_present(*pmd) || pmd_trans_huge(*pmd)) | |
1831 | goto out; | |
1832 | ||
ba76149f AA |
1833 | anon_vma_lock(vma->anon_vma); |
1834 | ||
1835 | pte = pte_offset_map(pmd, address); | |
1836 | ptl = pte_lockptr(mm, pmd); | |
1837 | ||
1838 | spin_lock(&mm->page_table_lock); /* probably unnecessary */ | |
1839 | /* | |
1840 | * After this gup_fast can't run anymore. This also removes | |
1841 | * any huge TLB entry from the CPU so we won't allow | |
1842 | * huge and small TLB entries for the same virtual address | |
1843 | * to avoid the risk of CPU bugs in that area. | |
1844 | */ | |
1845 | _pmd = pmdp_clear_flush_notify(vma, address, pmd); | |
1846 | spin_unlock(&mm->page_table_lock); | |
1847 | ||
1848 | spin_lock(ptl); | |
1849 | isolated = __collapse_huge_page_isolate(vma, address, pte); | |
1850 | spin_unlock(ptl); | |
ba76149f AA |
1851 | |
1852 | if (unlikely(!isolated)) { | |
453c7192 | 1853 | pte_unmap(pte); |
ba76149f AA |
1854 | spin_lock(&mm->page_table_lock); |
1855 | BUG_ON(!pmd_none(*pmd)); | |
1856 | set_pmd_at(mm, address, pmd, _pmd); | |
1857 | spin_unlock(&mm->page_table_lock); | |
1858 | anon_vma_unlock(vma->anon_vma); | |
ce83d217 | 1859 | goto out; |
ba76149f AA |
1860 | } |
1861 | ||
1862 | /* | |
1863 | * All pages are isolated and locked so anon_vma rmap | |
1864 | * can't run anymore. | |
1865 | */ | |
1866 | anon_vma_unlock(vma->anon_vma); | |
1867 | ||
1868 | __collapse_huge_page_copy(pte, new_page, vma, address, ptl); | |
453c7192 | 1869 | pte_unmap(pte); |
ba76149f AA |
1870 | __SetPageUptodate(new_page); |
1871 | pgtable = pmd_pgtable(_pmd); | |
1872 | VM_BUG_ON(page_count(pgtable) != 1); | |
1873 | VM_BUG_ON(page_mapcount(pgtable) != 0); | |
1874 | ||
1875 | _pmd = mk_pmd(new_page, vma->vm_page_prot); | |
1876 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); | |
1877 | _pmd = pmd_mkhuge(_pmd); | |
1878 | ||
1879 | /* | |
1880 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
1881 | * this is needed to avoid the copy_huge_page writes to become | |
1882 | * visible after the set_pmd_at() write. | |
1883 | */ | |
1884 | smp_wmb(); | |
1885 | ||
1886 | spin_lock(&mm->page_table_lock); | |
1887 | BUG_ON(!pmd_none(*pmd)); | |
1888 | page_add_new_anon_rmap(new_page, vma, address); | |
1889 | set_pmd_at(mm, address, pmd, _pmd); | |
1890 | update_mmu_cache(vma, address, entry); | |
1891 | prepare_pmd_huge_pte(pgtable, mm); | |
1892 | mm->nr_ptes--; | |
1893 | spin_unlock(&mm->page_table_lock); | |
1894 | ||
0bbbc0b3 | 1895 | #ifndef CONFIG_NUMA |
ba76149f | 1896 | *hpage = NULL; |
0bbbc0b3 | 1897 | #endif |
ba76149f | 1898 | khugepaged_pages_collapsed++; |
ce83d217 | 1899 | out_up_write: |
ba76149f | 1900 | up_write(&mm->mmap_sem); |
0bbbc0b3 AA |
1901 | return; |
1902 | ||
ce83d217 | 1903 | out: |
678ff896 | 1904 | mem_cgroup_uncharge_page(new_page); |
0bbbc0b3 AA |
1905 | #ifdef CONFIG_NUMA |
1906 | put_page(new_page); | |
1907 | #endif | |
ce83d217 | 1908 | goto out_up_write; |
ba76149f AA |
1909 | } |
1910 | ||
1911 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
1912 | struct vm_area_struct *vma, | |
1913 | unsigned long address, | |
1914 | struct page **hpage) | |
1915 | { | |
1916 | pgd_t *pgd; | |
1917 | pud_t *pud; | |
1918 | pmd_t *pmd; | |
1919 | pte_t *pte, *_pte; | |
1920 | int ret = 0, referenced = 0, none = 0; | |
1921 | struct page *page; | |
1922 | unsigned long _address; | |
1923 | spinlock_t *ptl; | |
5c4b4be3 | 1924 | int node = -1; |
ba76149f AA |
1925 | |
1926 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1927 | ||
1928 | pgd = pgd_offset(mm, address); | |
1929 | if (!pgd_present(*pgd)) | |
1930 | goto out; | |
1931 | ||
1932 | pud = pud_offset(pgd, address); | |
1933 | if (!pud_present(*pud)) | |
1934 | goto out; | |
1935 | ||
1936 | pmd = pmd_offset(pud, address); | |
1937 | if (!pmd_present(*pmd) || pmd_trans_huge(*pmd)) | |
1938 | goto out; | |
1939 | ||
1940 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1941 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1942 | _pte++, _address += PAGE_SIZE) { | |
1943 | pte_t pteval = *_pte; | |
1944 | if (pte_none(pteval)) { | |
1945 | if (++none <= khugepaged_max_ptes_none) | |
1946 | continue; | |
1947 | else | |
1948 | goto out_unmap; | |
1949 | } | |
1950 | if (!pte_present(pteval) || !pte_write(pteval)) | |
1951 | goto out_unmap; | |
1952 | page = vm_normal_page(vma, _address, pteval); | |
1953 | if (unlikely(!page)) | |
1954 | goto out_unmap; | |
5c4b4be3 AK |
1955 | /* |
1956 | * Chose the node of the first page. This could | |
1957 | * be more sophisticated and look at more pages, | |
1958 | * but isn't for now. | |
1959 | */ | |
1960 | if (node == -1) | |
1961 | node = page_to_nid(page); | |
ba76149f AA |
1962 | VM_BUG_ON(PageCompound(page)); |
1963 | if (!PageLRU(page) || PageLocked(page) || !PageAnon(page)) | |
1964 | goto out_unmap; | |
1965 | /* cannot use mapcount: can't collapse if there's a gup pin */ | |
1966 | if (page_count(page) != 1) | |
1967 | goto out_unmap; | |
8ee53820 AA |
1968 | if (pte_young(pteval) || PageReferenced(page) || |
1969 | mmu_notifier_test_young(vma->vm_mm, address)) | |
ba76149f AA |
1970 | referenced = 1; |
1971 | } | |
1972 | if (referenced) | |
1973 | ret = 1; | |
1974 | out_unmap: | |
1975 | pte_unmap_unlock(pte, ptl); | |
ce83d217 AA |
1976 | if (ret) |
1977 | /* collapse_huge_page will return with the mmap_sem released */ | |
5c4b4be3 | 1978 | collapse_huge_page(mm, address, hpage, vma, node); |
ba76149f AA |
1979 | out: |
1980 | return ret; | |
1981 | } | |
1982 | ||
1983 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
1984 | { | |
1985 | struct mm_struct *mm = mm_slot->mm; | |
1986 | ||
1987 | VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock)); | |
1988 | ||
1989 | if (khugepaged_test_exit(mm)) { | |
1990 | /* free mm_slot */ | |
1991 | hlist_del(&mm_slot->hash); | |
1992 | list_del(&mm_slot->mm_node); | |
1993 | ||
1994 | /* | |
1995 | * Not strictly needed because the mm exited already. | |
1996 | * | |
1997 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1998 | */ | |
1999 | ||
2000 | /* khugepaged_mm_lock actually not necessary for the below */ | |
2001 | free_mm_slot(mm_slot); | |
2002 | mmdrop(mm); | |
2003 | } | |
2004 | } | |
2005 | ||
2006 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
2007 | struct page **hpage) | |
2008 | { | |
2009 | struct mm_slot *mm_slot; | |
2010 | struct mm_struct *mm; | |
2011 | struct vm_area_struct *vma; | |
2012 | int progress = 0; | |
2013 | ||
2014 | VM_BUG_ON(!pages); | |
2015 | VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock)); | |
2016 | ||
2017 | if (khugepaged_scan.mm_slot) | |
2018 | mm_slot = khugepaged_scan.mm_slot; | |
2019 | else { | |
2020 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2021 | struct mm_slot, mm_node); | |
2022 | khugepaged_scan.address = 0; | |
2023 | khugepaged_scan.mm_slot = mm_slot; | |
2024 | } | |
2025 | spin_unlock(&khugepaged_mm_lock); | |
2026 | ||
2027 | mm = mm_slot->mm; | |
2028 | down_read(&mm->mmap_sem); | |
2029 | if (unlikely(khugepaged_test_exit(mm))) | |
2030 | vma = NULL; | |
2031 | else | |
2032 | vma = find_vma(mm, khugepaged_scan.address); | |
2033 | ||
2034 | progress++; | |
2035 | for (; vma; vma = vma->vm_next) { | |
2036 | unsigned long hstart, hend; | |
2037 | ||
2038 | cond_resched(); | |
2039 | if (unlikely(khugepaged_test_exit(mm))) { | |
2040 | progress++; | |
2041 | break; | |
2042 | } | |
2043 | ||
60ab3244 AA |
2044 | if ((!(vma->vm_flags & VM_HUGEPAGE) && |
2045 | !khugepaged_always()) || | |
2046 | (vma->vm_flags & VM_NOHUGEPAGE)) { | |
a7d6e4ec | 2047 | skip: |
ba76149f AA |
2048 | progress++; |
2049 | continue; | |
2050 | } | |
ba76149f | 2051 | /* VM_PFNMAP vmas may have vm_ops null but vm_file set */ |
a7d6e4ec AA |
2052 | if (!vma->anon_vma || vma->vm_ops || vma->vm_file) |
2053 | goto skip; | |
2054 | if (is_vma_temporary_stack(vma)) | |
2055 | goto skip; | |
2056 | ||
ba76149f AA |
2057 | VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma)); |
2058 | ||
2059 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2060 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
a7d6e4ec AA |
2061 | if (hstart >= hend) |
2062 | goto skip; | |
2063 | if (khugepaged_scan.address > hend) | |
2064 | goto skip; | |
ba76149f AA |
2065 | if (khugepaged_scan.address < hstart) |
2066 | khugepaged_scan.address = hstart; | |
a7d6e4ec | 2067 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); |
ba76149f AA |
2068 | |
2069 | while (khugepaged_scan.address < hend) { | |
2070 | int ret; | |
2071 | cond_resched(); | |
2072 | if (unlikely(khugepaged_test_exit(mm))) | |
2073 | goto breakouterloop; | |
2074 | ||
2075 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2076 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2077 | hend); | |
2078 | ret = khugepaged_scan_pmd(mm, vma, | |
2079 | khugepaged_scan.address, | |
2080 | hpage); | |
2081 | /* move to next address */ | |
2082 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2083 | progress += HPAGE_PMD_NR; | |
2084 | if (ret) | |
2085 | /* we released mmap_sem so break loop */ | |
2086 | goto breakouterloop_mmap_sem; | |
2087 | if (progress >= pages) | |
2088 | goto breakouterloop; | |
2089 | } | |
2090 | } | |
2091 | breakouterloop: | |
2092 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2093 | breakouterloop_mmap_sem: | |
2094 | ||
2095 | spin_lock(&khugepaged_mm_lock); | |
a7d6e4ec | 2096 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); |
ba76149f AA |
2097 | /* |
2098 | * Release the current mm_slot if this mm is about to die, or | |
2099 | * if we scanned all vmas of this mm. | |
2100 | */ | |
2101 | if (khugepaged_test_exit(mm) || !vma) { | |
2102 | /* | |
2103 | * Make sure that if mm_users is reaching zero while | |
2104 | * khugepaged runs here, khugepaged_exit will find | |
2105 | * mm_slot not pointing to the exiting mm. | |
2106 | */ | |
2107 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2108 | khugepaged_scan.mm_slot = list_entry( | |
2109 | mm_slot->mm_node.next, | |
2110 | struct mm_slot, mm_node); | |
2111 | khugepaged_scan.address = 0; | |
2112 | } else { | |
2113 | khugepaged_scan.mm_slot = NULL; | |
2114 | khugepaged_full_scans++; | |
2115 | } | |
2116 | ||
2117 | collect_mm_slot(mm_slot); | |
2118 | } | |
2119 | ||
2120 | return progress; | |
2121 | } | |
2122 | ||
2123 | static int khugepaged_has_work(void) | |
2124 | { | |
2125 | return !list_empty(&khugepaged_scan.mm_head) && | |
2126 | khugepaged_enabled(); | |
2127 | } | |
2128 | ||
2129 | static int khugepaged_wait_event(void) | |
2130 | { | |
2131 | return !list_empty(&khugepaged_scan.mm_head) || | |
2132 | !khugepaged_enabled(); | |
2133 | } | |
2134 | ||
2135 | static void khugepaged_do_scan(struct page **hpage) | |
2136 | { | |
2137 | unsigned int progress = 0, pass_through_head = 0; | |
2138 | unsigned int pages = khugepaged_pages_to_scan; | |
2139 | ||
2140 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2141 | ||
2142 | while (progress < pages) { | |
2143 | cond_resched(); | |
2144 | ||
0bbbc0b3 | 2145 | #ifndef CONFIG_NUMA |
ba76149f AA |
2146 | if (!*hpage) { |
2147 | *hpage = alloc_hugepage(khugepaged_defrag()); | |
2148 | if (unlikely(!*hpage)) | |
2149 | break; | |
2150 | } | |
0bbbc0b3 AA |
2151 | #else |
2152 | if (IS_ERR(*hpage)) | |
2153 | break; | |
2154 | #endif | |
ba76149f | 2155 | |
878aee7d AA |
2156 | if (unlikely(kthread_should_stop() || freezing(current))) |
2157 | break; | |
2158 | ||
ba76149f AA |
2159 | spin_lock(&khugepaged_mm_lock); |
2160 | if (!khugepaged_scan.mm_slot) | |
2161 | pass_through_head++; | |
2162 | if (khugepaged_has_work() && | |
2163 | pass_through_head < 2) | |
2164 | progress += khugepaged_scan_mm_slot(pages - progress, | |
2165 | hpage); | |
2166 | else | |
2167 | progress = pages; | |
2168 | spin_unlock(&khugepaged_mm_lock); | |
2169 | } | |
2170 | } | |
2171 | ||
0bbbc0b3 AA |
2172 | static void khugepaged_alloc_sleep(void) |
2173 | { | |
2174 | DEFINE_WAIT(wait); | |
2175 | add_wait_queue(&khugepaged_wait, &wait); | |
2176 | schedule_timeout_interruptible( | |
2177 | msecs_to_jiffies( | |
2178 | khugepaged_alloc_sleep_millisecs)); | |
2179 | remove_wait_queue(&khugepaged_wait, &wait); | |
2180 | } | |
2181 | ||
2182 | #ifndef CONFIG_NUMA | |
ba76149f AA |
2183 | static struct page *khugepaged_alloc_hugepage(void) |
2184 | { | |
2185 | struct page *hpage; | |
2186 | ||
2187 | do { | |
2188 | hpage = alloc_hugepage(khugepaged_defrag()); | |
0bbbc0b3 AA |
2189 | if (!hpage) |
2190 | khugepaged_alloc_sleep(); | |
ba76149f AA |
2191 | } while (unlikely(!hpage) && |
2192 | likely(khugepaged_enabled())); | |
2193 | return hpage; | |
2194 | } | |
0bbbc0b3 | 2195 | #endif |
ba76149f AA |
2196 | |
2197 | static void khugepaged_loop(void) | |
2198 | { | |
2199 | struct page *hpage; | |
2200 | ||
0bbbc0b3 AA |
2201 | #ifdef CONFIG_NUMA |
2202 | hpage = NULL; | |
2203 | #endif | |
ba76149f | 2204 | while (likely(khugepaged_enabled())) { |
0bbbc0b3 | 2205 | #ifndef CONFIG_NUMA |
ba76149f AA |
2206 | hpage = khugepaged_alloc_hugepage(); |
2207 | if (unlikely(!hpage)) | |
2208 | break; | |
0bbbc0b3 AA |
2209 | #else |
2210 | if (IS_ERR(hpage)) { | |
2211 | khugepaged_alloc_sleep(); | |
2212 | hpage = NULL; | |
2213 | } | |
2214 | #endif | |
ba76149f AA |
2215 | |
2216 | khugepaged_do_scan(&hpage); | |
0bbbc0b3 | 2217 | #ifndef CONFIG_NUMA |
ba76149f AA |
2218 | if (hpage) |
2219 | put_page(hpage); | |
0bbbc0b3 | 2220 | #endif |
878aee7d AA |
2221 | try_to_freeze(); |
2222 | if (unlikely(kthread_should_stop())) | |
2223 | break; | |
ba76149f AA |
2224 | if (khugepaged_has_work()) { |
2225 | DEFINE_WAIT(wait); | |
2226 | if (!khugepaged_scan_sleep_millisecs) | |
2227 | continue; | |
2228 | add_wait_queue(&khugepaged_wait, &wait); | |
2229 | schedule_timeout_interruptible( | |
2230 | msecs_to_jiffies( | |
2231 | khugepaged_scan_sleep_millisecs)); | |
2232 | remove_wait_queue(&khugepaged_wait, &wait); | |
2233 | } else if (khugepaged_enabled()) | |
878aee7d AA |
2234 | wait_event_freezable(khugepaged_wait, |
2235 | khugepaged_wait_event()); | |
ba76149f AA |
2236 | } |
2237 | } | |
2238 | ||
2239 | static int khugepaged(void *none) | |
2240 | { | |
2241 | struct mm_slot *mm_slot; | |
2242 | ||
878aee7d | 2243 | set_freezable(); |
ba76149f AA |
2244 | set_user_nice(current, 19); |
2245 | ||
2246 | /* serialize with start_khugepaged() */ | |
2247 | mutex_lock(&khugepaged_mutex); | |
2248 | ||
2249 | for (;;) { | |
2250 | mutex_unlock(&khugepaged_mutex); | |
a7d6e4ec | 2251 | VM_BUG_ON(khugepaged_thread != current); |
ba76149f | 2252 | khugepaged_loop(); |
a7d6e4ec | 2253 | VM_BUG_ON(khugepaged_thread != current); |
ba76149f AA |
2254 | |
2255 | mutex_lock(&khugepaged_mutex); | |
2256 | if (!khugepaged_enabled()) | |
2257 | break; | |
878aee7d AA |
2258 | if (unlikely(kthread_should_stop())) |
2259 | break; | |
ba76149f AA |
2260 | } |
2261 | ||
2262 | spin_lock(&khugepaged_mm_lock); | |
2263 | mm_slot = khugepaged_scan.mm_slot; | |
2264 | khugepaged_scan.mm_slot = NULL; | |
2265 | if (mm_slot) | |
2266 | collect_mm_slot(mm_slot); | |
2267 | spin_unlock(&khugepaged_mm_lock); | |
2268 | ||
2269 | khugepaged_thread = NULL; | |
2270 | mutex_unlock(&khugepaged_mutex); | |
2271 | ||
2272 | return 0; | |
2273 | } | |
2274 | ||
71e3aac0 AA |
2275 | void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd) |
2276 | { | |
2277 | struct page *page; | |
2278 | ||
2279 | spin_lock(&mm->page_table_lock); | |
2280 | if (unlikely(!pmd_trans_huge(*pmd))) { | |
2281 | spin_unlock(&mm->page_table_lock); | |
2282 | return; | |
2283 | } | |
2284 | page = pmd_page(*pmd); | |
2285 | VM_BUG_ON(!page_count(page)); | |
2286 | get_page(page); | |
2287 | spin_unlock(&mm->page_table_lock); | |
2288 | ||
2289 | split_huge_page(page); | |
2290 | ||
2291 | put_page(page); | |
2292 | BUG_ON(pmd_trans_huge(*pmd)); | |
2293 | } | |
94fcc585 AA |
2294 | |
2295 | static void split_huge_page_address(struct mm_struct *mm, | |
2296 | unsigned long address) | |
2297 | { | |
2298 | pgd_t *pgd; | |
2299 | pud_t *pud; | |
2300 | pmd_t *pmd; | |
2301 | ||
2302 | VM_BUG_ON(!(address & ~HPAGE_PMD_MASK)); | |
2303 | ||
2304 | pgd = pgd_offset(mm, address); | |
2305 | if (!pgd_present(*pgd)) | |
2306 | return; | |
2307 | ||
2308 | pud = pud_offset(pgd, address); | |
2309 | if (!pud_present(*pud)) | |
2310 | return; | |
2311 | ||
2312 | pmd = pmd_offset(pud, address); | |
2313 | if (!pmd_present(*pmd)) | |
2314 | return; | |
2315 | /* | |
2316 | * Caller holds the mmap_sem write mode, so a huge pmd cannot | |
2317 | * materialize from under us. | |
2318 | */ | |
2319 | split_huge_page_pmd(mm, pmd); | |
2320 | } | |
2321 | ||
2322 | void __vma_adjust_trans_huge(struct vm_area_struct *vma, | |
2323 | unsigned long start, | |
2324 | unsigned long end, | |
2325 | long adjust_next) | |
2326 | { | |
2327 | /* | |
2328 | * If the new start address isn't hpage aligned and it could | |
2329 | * previously contain an hugepage: check if we need to split | |
2330 | * an huge pmd. | |
2331 | */ | |
2332 | if (start & ~HPAGE_PMD_MASK && | |
2333 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
2334 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2335 | split_huge_page_address(vma->vm_mm, start); | |
2336 | ||
2337 | /* | |
2338 | * If the new end address isn't hpage aligned and it could | |
2339 | * previously contain an hugepage: check if we need to split | |
2340 | * an huge pmd. | |
2341 | */ | |
2342 | if (end & ~HPAGE_PMD_MASK && | |
2343 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
2344 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2345 | split_huge_page_address(vma->vm_mm, end); | |
2346 | ||
2347 | /* | |
2348 | * If we're also updating the vma->vm_next->vm_start, if the new | |
2349 | * vm_next->vm_start isn't page aligned and it could previously | |
2350 | * contain an hugepage: check if we need to split an huge pmd. | |
2351 | */ | |
2352 | if (adjust_next > 0) { | |
2353 | struct vm_area_struct *next = vma->vm_next; | |
2354 | unsigned long nstart = next->vm_start; | |
2355 | nstart += adjust_next << PAGE_SHIFT; | |
2356 | if (nstart & ~HPAGE_PMD_MASK && | |
2357 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
2358 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
2359 | split_huge_page_address(next->vm_mm, nstart); | |
2360 | } | |
2361 | } |