]>
Commit | Line | Data |
---|---|---|
71e3aac0 AA |
1 | /* |
2 | * Copyright (C) 2009 Red Hat, Inc. | |
3 | * | |
4 | * This work is licensed under the terms of the GNU GPL, version 2. See | |
5 | * the COPYING file in the top-level directory. | |
6 | */ | |
7 | ||
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> |
71e3aac0 AA |
19 | #include <asm/tlb.h> |
20 | #include <asm/pgalloc.h> | |
21 | #include "internal.h" | |
22 | ||
ba76149f AA |
23 | /* |
24 | * By default transparent hugepage support is enabled for all mappings | |
25 | * and khugepaged scans all mappings. Defrag is only invoked by | |
26 | * khugepaged hugepage allocations and by page faults inside | |
27 | * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived | |
28 | * allocations. | |
29 | */ | |
71e3aac0 | 30 | unsigned long transparent_hugepage_flags __read_mostly = |
13ece886 | 31 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS |
ba76149f | 32 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| |
13ece886 AA |
33 | #endif |
34 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE | |
35 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| | |
36 | #endif | |
d39d33c3 | 37 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)| |
ba76149f AA |
38 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); |
39 | ||
40 | /* default scan 8*512 pte (or vmas) every 30 second */ | |
41 | static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8; | |
42 | static unsigned int khugepaged_pages_collapsed; | |
43 | static unsigned int khugepaged_full_scans; | |
44 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
45 | /* during fragmentation poll the hugepage allocator once every minute */ | |
46 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
47 | static struct task_struct *khugepaged_thread __read_mostly; | |
48 | static DEFINE_MUTEX(khugepaged_mutex); | |
49 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
50 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
51 | /* | |
52 | * default collapse hugepages if there is at least one pte mapped like | |
53 | * it would have happened if the vma was large enough during page | |
54 | * fault. | |
55 | */ | |
56 | static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1; | |
57 | ||
58 | static int khugepaged(void *none); | |
59 | static int mm_slots_hash_init(void); | |
60 | static int khugepaged_slab_init(void); | |
61 | static void khugepaged_slab_free(void); | |
62 | ||
63 | #define MM_SLOTS_HASH_HEADS 1024 | |
64 | static struct hlist_head *mm_slots_hash __read_mostly; | |
65 | static struct kmem_cache *mm_slot_cache __read_mostly; | |
66 | ||
67 | /** | |
68 | * struct mm_slot - hash lookup from mm to mm_slot | |
69 | * @hash: hash collision list | |
70 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
71 | * @mm: the mm that this information is valid for | |
72 | */ | |
73 | struct mm_slot { | |
74 | struct hlist_node hash; | |
75 | struct list_head mm_node; | |
76 | struct mm_struct *mm; | |
77 | }; | |
78 | ||
79 | /** | |
80 | * struct khugepaged_scan - cursor for scanning | |
81 | * @mm_head: the head of the mm list to scan | |
82 | * @mm_slot: the current mm_slot we are scanning | |
83 | * @address: the next address inside that to be scanned | |
84 | * | |
85 | * There is only the one khugepaged_scan instance of this cursor structure. | |
86 | */ | |
87 | struct khugepaged_scan { | |
88 | struct list_head mm_head; | |
89 | struct mm_slot *mm_slot; | |
90 | unsigned long address; | |
91 | } khugepaged_scan = { | |
92 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), | |
93 | }; | |
94 | ||
f000565a AA |
95 | |
96 | static int set_recommended_min_free_kbytes(void) | |
97 | { | |
98 | struct zone *zone; | |
99 | int nr_zones = 0; | |
100 | unsigned long recommended_min; | |
101 | extern int min_free_kbytes; | |
102 | ||
103 | if (!test_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
104 | &transparent_hugepage_flags) && | |
105 | !test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
106 | &transparent_hugepage_flags)) | |
107 | return 0; | |
108 | ||
109 | for_each_populated_zone(zone) | |
110 | nr_zones++; | |
111 | ||
112 | /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */ | |
113 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
114 | ||
115 | /* | |
116 | * Make sure that on average at least two pageblocks are almost free | |
117 | * of another type, one for a migratetype to fall back to and a | |
118 | * second to avoid subsequent fallbacks of other types There are 3 | |
119 | * MIGRATE_TYPES we care about. | |
120 | */ | |
121 | recommended_min += pageblock_nr_pages * nr_zones * | |
122 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
123 | ||
124 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
125 | recommended_min = min(recommended_min, | |
126 | (unsigned long) nr_free_buffer_pages() / 20); | |
127 | recommended_min <<= (PAGE_SHIFT-10); | |
128 | ||
129 | if (recommended_min > min_free_kbytes) | |
130 | min_free_kbytes = recommended_min; | |
131 | setup_per_zone_wmarks(); | |
132 | return 0; | |
133 | } | |
134 | late_initcall(set_recommended_min_free_kbytes); | |
135 | ||
ba76149f AA |
136 | static int start_khugepaged(void) |
137 | { | |
138 | int err = 0; | |
139 | if (khugepaged_enabled()) { | |
140 | int wakeup; | |
141 | if (unlikely(!mm_slot_cache || !mm_slots_hash)) { | |
142 | err = -ENOMEM; | |
143 | goto out; | |
144 | } | |
145 | mutex_lock(&khugepaged_mutex); | |
146 | if (!khugepaged_thread) | |
147 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
148 | "khugepaged"); | |
149 | if (unlikely(IS_ERR(khugepaged_thread))) { | |
150 | printk(KERN_ERR | |
151 | "khugepaged: kthread_run(khugepaged) failed\n"); | |
152 | err = PTR_ERR(khugepaged_thread); | |
153 | khugepaged_thread = NULL; | |
154 | } | |
155 | wakeup = !list_empty(&khugepaged_scan.mm_head); | |
156 | mutex_unlock(&khugepaged_mutex); | |
157 | if (wakeup) | |
158 | wake_up_interruptible(&khugepaged_wait); | |
f000565a AA |
159 | |
160 | set_recommended_min_free_kbytes(); | |
ba76149f AA |
161 | } else |
162 | /* wakeup to exit */ | |
163 | wake_up_interruptible(&khugepaged_wait); | |
164 | out: | |
165 | return err; | |
166 | } | |
71e3aac0 AA |
167 | |
168 | #ifdef CONFIG_SYSFS | |
ba76149f | 169 | |
71e3aac0 AA |
170 | static ssize_t double_flag_show(struct kobject *kobj, |
171 | struct kobj_attribute *attr, char *buf, | |
172 | enum transparent_hugepage_flag enabled, | |
173 | enum transparent_hugepage_flag req_madv) | |
174 | { | |
175 | if (test_bit(enabled, &transparent_hugepage_flags)) { | |
176 | VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags)); | |
177 | return sprintf(buf, "[always] madvise never\n"); | |
178 | } else if (test_bit(req_madv, &transparent_hugepage_flags)) | |
179 | return sprintf(buf, "always [madvise] never\n"); | |
180 | else | |
181 | return sprintf(buf, "always madvise [never]\n"); | |
182 | } | |
183 | static ssize_t double_flag_store(struct kobject *kobj, | |
184 | struct kobj_attribute *attr, | |
185 | const char *buf, size_t count, | |
186 | enum transparent_hugepage_flag enabled, | |
187 | enum transparent_hugepage_flag req_madv) | |
188 | { | |
189 | if (!memcmp("always", buf, | |
190 | min(sizeof("always")-1, count))) { | |
191 | set_bit(enabled, &transparent_hugepage_flags); | |
192 | clear_bit(req_madv, &transparent_hugepage_flags); | |
193 | } else if (!memcmp("madvise", buf, | |
194 | min(sizeof("madvise")-1, count))) { | |
195 | clear_bit(enabled, &transparent_hugepage_flags); | |
196 | set_bit(req_madv, &transparent_hugepage_flags); | |
197 | } else if (!memcmp("never", buf, | |
198 | min(sizeof("never")-1, count))) { | |
199 | clear_bit(enabled, &transparent_hugepage_flags); | |
200 | clear_bit(req_madv, &transparent_hugepage_flags); | |
201 | } else | |
202 | return -EINVAL; | |
203 | ||
204 | return count; | |
205 | } | |
206 | ||
207 | static ssize_t enabled_show(struct kobject *kobj, | |
208 | struct kobj_attribute *attr, char *buf) | |
209 | { | |
210 | return double_flag_show(kobj, attr, buf, | |
211 | TRANSPARENT_HUGEPAGE_FLAG, | |
212 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
213 | } | |
214 | static ssize_t enabled_store(struct kobject *kobj, | |
215 | struct kobj_attribute *attr, | |
216 | const char *buf, size_t count) | |
217 | { | |
ba76149f AA |
218 | ssize_t ret; |
219 | ||
220 | ret = double_flag_store(kobj, attr, buf, count, | |
221 | TRANSPARENT_HUGEPAGE_FLAG, | |
222 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
223 | ||
224 | if (ret > 0) { | |
225 | int err = start_khugepaged(); | |
226 | if (err) | |
227 | ret = err; | |
228 | } | |
229 | ||
f000565a AA |
230 | if (ret > 0 && |
231 | (test_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
232 | &transparent_hugepage_flags) || | |
233 | test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
234 | &transparent_hugepage_flags))) | |
235 | set_recommended_min_free_kbytes(); | |
236 | ||
ba76149f | 237 | return ret; |
71e3aac0 AA |
238 | } |
239 | static struct kobj_attribute enabled_attr = | |
240 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
241 | ||
242 | static ssize_t single_flag_show(struct kobject *kobj, | |
243 | struct kobj_attribute *attr, char *buf, | |
244 | enum transparent_hugepage_flag flag) | |
245 | { | |
246 | if (test_bit(flag, &transparent_hugepage_flags)) | |
247 | return sprintf(buf, "[yes] no\n"); | |
248 | else | |
249 | return sprintf(buf, "yes [no]\n"); | |
250 | } | |
251 | static ssize_t single_flag_store(struct kobject *kobj, | |
252 | struct kobj_attribute *attr, | |
253 | const char *buf, size_t count, | |
254 | enum transparent_hugepage_flag flag) | |
255 | { | |
256 | if (!memcmp("yes", buf, | |
257 | min(sizeof("yes")-1, count))) { | |
258 | set_bit(flag, &transparent_hugepage_flags); | |
259 | } else if (!memcmp("no", buf, | |
260 | min(sizeof("no")-1, count))) { | |
261 | clear_bit(flag, &transparent_hugepage_flags); | |
262 | } else | |
263 | return -EINVAL; | |
264 | ||
265 | return count; | |
266 | } | |
267 | ||
268 | /* | |
269 | * Currently defrag only disables __GFP_NOWAIT for allocation. A blind | |
270 | * __GFP_REPEAT is too aggressive, it's never worth swapping tons of | |
271 | * memory just to allocate one more hugepage. | |
272 | */ | |
273 | static ssize_t defrag_show(struct kobject *kobj, | |
274 | struct kobj_attribute *attr, char *buf) | |
275 | { | |
276 | return double_flag_show(kobj, attr, buf, | |
277 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
278 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
279 | } | |
280 | static ssize_t defrag_store(struct kobject *kobj, | |
281 | struct kobj_attribute *attr, | |
282 | const char *buf, size_t count) | |
283 | { | |
284 | return double_flag_store(kobj, attr, buf, count, | |
285 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
286 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
287 | } | |
288 | static struct kobj_attribute defrag_attr = | |
289 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
290 | ||
291 | #ifdef CONFIG_DEBUG_VM | |
292 | static ssize_t debug_cow_show(struct kobject *kobj, | |
293 | struct kobj_attribute *attr, char *buf) | |
294 | { | |
295 | return single_flag_show(kobj, attr, buf, | |
296 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
297 | } | |
298 | static ssize_t debug_cow_store(struct kobject *kobj, | |
299 | struct kobj_attribute *attr, | |
300 | const char *buf, size_t count) | |
301 | { | |
302 | return single_flag_store(kobj, attr, buf, count, | |
303 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
304 | } | |
305 | static struct kobj_attribute debug_cow_attr = | |
306 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
307 | #endif /* CONFIG_DEBUG_VM */ | |
308 | ||
309 | static struct attribute *hugepage_attr[] = { | |
310 | &enabled_attr.attr, | |
311 | &defrag_attr.attr, | |
312 | #ifdef CONFIG_DEBUG_VM | |
313 | &debug_cow_attr.attr, | |
314 | #endif | |
315 | NULL, | |
316 | }; | |
317 | ||
318 | static struct attribute_group hugepage_attr_group = { | |
319 | .attrs = hugepage_attr, | |
ba76149f AA |
320 | }; |
321 | ||
322 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, | |
323 | struct kobj_attribute *attr, | |
324 | char *buf) | |
325 | { | |
326 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
327 | } | |
328 | ||
329 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
330 | struct kobj_attribute *attr, | |
331 | const char *buf, size_t count) | |
332 | { | |
333 | unsigned long msecs; | |
334 | int err; | |
335 | ||
336 | err = strict_strtoul(buf, 10, &msecs); | |
337 | if (err || msecs > UINT_MAX) | |
338 | return -EINVAL; | |
339 | ||
340 | khugepaged_scan_sleep_millisecs = msecs; | |
341 | wake_up_interruptible(&khugepaged_wait); | |
342 | ||
343 | return count; | |
344 | } | |
345 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
346 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
347 | scan_sleep_millisecs_store); | |
348 | ||
349 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
350 | struct kobj_attribute *attr, | |
351 | char *buf) | |
352 | { | |
353 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
354 | } | |
355 | ||
356 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
357 | struct kobj_attribute *attr, | |
358 | const char *buf, size_t count) | |
359 | { | |
360 | unsigned long msecs; | |
361 | int err; | |
362 | ||
363 | err = strict_strtoul(buf, 10, &msecs); | |
364 | if (err || msecs > UINT_MAX) | |
365 | return -EINVAL; | |
366 | ||
367 | khugepaged_alloc_sleep_millisecs = msecs; | |
368 | wake_up_interruptible(&khugepaged_wait); | |
369 | ||
370 | return count; | |
371 | } | |
372 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
373 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
374 | alloc_sleep_millisecs_store); | |
375 | ||
376 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
377 | struct kobj_attribute *attr, | |
378 | char *buf) | |
379 | { | |
380 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
381 | } | |
382 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
383 | struct kobj_attribute *attr, | |
384 | const char *buf, size_t count) | |
385 | { | |
386 | int err; | |
387 | unsigned long pages; | |
388 | ||
389 | err = strict_strtoul(buf, 10, &pages); | |
390 | if (err || !pages || pages > UINT_MAX) | |
391 | return -EINVAL; | |
392 | ||
393 | khugepaged_pages_to_scan = pages; | |
394 | ||
395 | return count; | |
396 | } | |
397 | static struct kobj_attribute pages_to_scan_attr = | |
398 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
399 | pages_to_scan_store); | |
400 | ||
401 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
402 | struct kobj_attribute *attr, | |
403 | char *buf) | |
404 | { | |
405 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
406 | } | |
407 | static struct kobj_attribute pages_collapsed_attr = | |
408 | __ATTR_RO(pages_collapsed); | |
409 | ||
410 | static ssize_t full_scans_show(struct kobject *kobj, | |
411 | struct kobj_attribute *attr, | |
412 | char *buf) | |
413 | { | |
414 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
415 | } | |
416 | static struct kobj_attribute full_scans_attr = | |
417 | __ATTR_RO(full_scans); | |
418 | ||
419 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
420 | struct kobj_attribute *attr, char *buf) | |
421 | { | |
422 | return single_flag_show(kobj, attr, buf, | |
423 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
424 | } | |
425 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
426 | struct kobj_attribute *attr, | |
427 | const char *buf, size_t count) | |
428 | { | |
429 | return single_flag_store(kobj, attr, buf, count, | |
430 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
431 | } | |
432 | static struct kobj_attribute khugepaged_defrag_attr = | |
433 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
434 | khugepaged_defrag_store); | |
435 | ||
436 | /* | |
437 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
438 | * any unmapped ptes in turn potentially increasing the memory | |
439 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
440 | * reduce the available free memory in the system as it | |
441 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
442 | * free memory in the system during the khugepaged scan. | |
443 | */ | |
444 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
445 | struct kobj_attribute *attr, | |
446 | char *buf) | |
447 | { | |
448 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
449 | } | |
450 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
451 | struct kobj_attribute *attr, | |
452 | const char *buf, size_t count) | |
453 | { | |
454 | int err; | |
455 | unsigned long max_ptes_none; | |
456 | ||
457 | err = strict_strtoul(buf, 10, &max_ptes_none); | |
458 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
459 | return -EINVAL; | |
460 | ||
461 | khugepaged_max_ptes_none = max_ptes_none; | |
462 | ||
463 | return count; | |
464 | } | |
465 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
466 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
467 | khugepaged_max_ptes_none_store); | |
468 | ||
469 | static struct attribute *khugepaged_attr[] = { | |
470 | &khugepaged_defrag_attr.attr, | |
471 | &khugepaged_max_ptes_none_attr.attr, | |
472 | &pages_to_scan_attr.attr, | |
473 | &pages_collapsed_attr.attr, | |
474 | &full_scans_attr.attr, | |
475 | &scan_sleep_millisecs_attr.attr, | |
476 | &alloc_sleep_millisecs_attr.attr, | |
477 | NULL, | |
478 | }; | |
479 | ||
480 | static struct attribute_group khugepaged_attr_group = { | |
481 | .attrs = khugepaged_attr, | |
482 | .name = "khugepaged", | |
71e3aac0 AA |
483 | }; |
484 | #endif /* CONFIG_SYSFS */ | |
485 | ||
486 | static int __init hugepage_init(void) | |
487 | { | |
71e3aac0 | 488 | int err; |
ba76149f AA |
489 | #ifdef CONFIG_SYSFS |
490 | static struct kobject *hugepage_kobj; | |
4b7167b9 | 491 | #endif |
71e3aac0 | 492 | |
4b7167b9 AA |
493 | err = -EINVAL; |
494 | if (!has_transparent_hugepage()) { | |
495 | transparent_hugepage_flags = 0; | |
496 | goto out; | |
497 | } | |
498 | ||
499 | #ifdef CONFIG_SYSFS | |
ba76149f AA |
500 | err = -ENOMEM; |
501 | hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); | |
502 | if (unlikely(!hugepage_kobj)) { | |
503 | printk(KERN_ERR "hugepage: failed kobject create\n"); | |
504 | goto out; | |
505 | } | |
506 | ||
507 | err = sysfs_create_group(hugepage_kobj, &hugepage_attr_group); | |
508 | if (err) { | |
509 | printk(KERN_ERR "hugepage: failed register hugeage group\n"); | |
510 | goto out; | |
511 | } | |
512 | ||
513 | err = sysfs_create_group(hugepage_kobj, &khugepaged_attr_group); | |
514 | if (err) { | |
515 | printk(KERN_ERR "hugepage: failed register hugeage group\n"); | |
516 | goto out; | |
517 | } | |
71e3aac0 | 518 | #endif |
ba76149f AA |
519 | |
520 | err = khugepaged_slab_init(); | |
521 | if (err) | |
522 | goto out; | |
523 | ||
524 | err = mm_slots_hash_init(); | |
525 | if (err) { | |
526 | khugepaged_slab_free(); | |
527 | goto out; | |
528 | } | |
529 | ||
97562cd2 RR |
530 | /* |
531 | * By default disable transparent hugepages on smaller systems, | |
532 | * where the extra memory used could hurt more than TLB overhead | |
533 | * is likely to save. The admin can still enable it through /sys. | |
534 | */ | |
535 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) | |
536 | transparent_hugepage_flags = 0; | |
537 | ||
ba76149f AA |
538 | start_khugepaged(); |
539 | ||
f000565a AA |
540 | set_recommended_min_free_kbytes(); |
541 | ||
ba76149f AA |
542 | out: |
543 | return err; | |
71e3aac0 AA |
544 | } |
545 | module_init(hugepage_init) | |
546 | ||
547 | static int __init setup_transparent_hugepage(char *str) | |
548 | { | |
549 | int ret = 0; | |
550 | if (!str) | |
551 | goto out; | |
552 | if (!strcmp(str, "always")) { | |
553 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
554 | &transparent_hugepage_flags); | |
555 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
556 | &transparent_hugepage_flags); | |
557 | ret = 1; | |
558 | } else if (!strcmp(str, "madvise")) { | |
559 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
560 | &transparent_hugepage_flags); | |
561 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
562 | &transparent_hugepage_flags); | |
563 | ret = 1; | |
564 | } else if (!strcmp(str, "never")) { | |
565 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
566 | &transparent_hugepage_flags); | |
567 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
568 | &transparent_hugepage_flags); | |
569 | ret = 1; | |
570 | } | |
571 | out: | |
572 | if (!ret) | |
573 | printk(KERN_WARNING | |
574 | "transparent_hugepage= cannot parse, ignored\n"); | |
575 | return ret; | |
576 | } | |
577 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
578 | ||
579 | static void prepare_pmd_huge_pte(pgtable_t pgtable, | |
580 | struct mm_struct *mm) | |
581 | { | |
582 | assert_spin_locked(&mm->page_table_lock); | |
583 | ||
584 | /* FIFO */ | |
585 | if (!mm->pmd_huge_pte) | |
586 | INIT_LIST_HEAD(&pgtable->lru); | |
587 | else | |
588 | list_add(&pgtable->lru, &mm->pmd_huge_pte->lru); | |
589 | mm->pmd_huge_pte = pgtable; | |
590 | } | |
591 | ||
592 | static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) | |
593 | { | |
594 | if (likely(vma->vm_flags & VM_WRITE)) | |
595 | pmd = pmd_mkwrite(pmd); | |
596 | return pmd; | |
597 | } | |
598 | ||
599 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, | |
600 | struct vm_area_struct *vma, | |
601 | unsigned long haddr, pmd_t *pmd, | |
602 | struct page *page) | |
603 | { | |
604 | int ret = 0; | |
605 | pgtable_t pgtable; | |
606 | ||
607 | VM_BUG_ON(!PageCompound(page)); | |
608 | pgtable = pte_alloc_one(mm, haddr); | |
609 | if (unlikely(!pgtable)) { | |
b9bbfbe3 | 610 | mem_cgroup_uncharge_page(page); |
71e3aac0 AA |
611 | put_page(page); |
612 | return VM_FAULT_OOM; | |
613 | } | |
614 | ||
615 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
616 | __SetPageUptodate(page); | |
617 | ||
618 | spin_lock(&mm->page_table_lock); | |
619 | if (unlikely(!pmd_none(*pmd))) { | |
620 | spin_unlock(&mm->page_table_lock); | |
b9bbfbe3 | 621 | mem_cgroup_uncharge_page(page); |
71e3aac0 AA |
622 | put_page(page); |
623 | pte_free(mm, pgtable); | |
624 | } else { | |
625 | pmd_t entry; | |
626 | entry = mk_pmd(page, vma->vm_page_prot); | |
627 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
628 | entry = pmd_mkhuge(entry); | |
629 | /* | |
630 | * The spinlocking to take the lru_lock inside | |
631 | * page_add_new_anon_rmap() acts as a full memory | |
632 | * barrier to be sure clear_huge_page writes become | |
633 | * visible after the set_pmd_at() write. | |
634 | */ | |
635 | page_add_new_anon_rmap(page, vma, haddr); | |
636 | set_pmd_at(mm, haddr, pmd, entry); | |
637 | prepare_pmd_huge_pte(pgtable, mm); | |
638 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
639 | spin_unlock(&mm->page_table_lock); | |
640 | } | |
641 | ||
642 | return ret; | |
643 | } | |
644 | ||
0bbbc0b3 AA |
645 | static inline gfp_t alloc_hugepage_gfpmask(int defrag) |
646 | { | |
647 | return GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT); | |
648 | } | |
649 | ||
650 | static inline struct page *alloc_hugepage_vma(int defrag, | |
651 | struct vm_area_struct *vma, | |
652 | unsigned long haddr) | |
653 | { | |
654 | return alloc_pages_vma(alloc_hugepage_gfpmask(defrag), | |
655 | HPAGE_PMD_ORDER, vma, haddr); | |
656 | } | |
657 | ||
658 | #ifndef CONFIG_NUMA | |
71e3aac0 AA |
659 | static inline struct page *alloc_hugepage(int defrag) |
660 | { | |
0bbbc0b3 | 661 | return alloc_pages(alloc_hugepage_gfpmask(defrag), |
71e3aac0 AA |
662 | HPAGE_PMD_ORDER); |
663 | } | |
0bbbc0b3 | 664 | #endif |
71e3aac0 AA |
665 | |
666 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
667 | unsigned long address, pmd_t *pmd, | |
668 | unsigned int flags) | |
669 | { | |
670 | struct page *page; | |
671 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
672 | pte_t *pte; | |
673 | ||
674 | if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) { | |
675 | if (unlikely(anon_vma_prepare(vma))) | |
676 | return VM_FAULT_OOM; | |
ba76149f AA |
677 | if (unlikely(khugepaged_enter(vma))) |
678 | return VM_FAULT_OOM; | |
0bbbc0b3 AA |
679 | page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
680 | vma, haddr); | |
71e3aac0 AA |
681 | if (unlikely(!page)) |
682 | goto out; | |
b9bbfbe3 AA |
683 | if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) { |
684 | put_page(page); | |
685 | goto out; | |
686 | } | |
71e3aac0 AA |
687 | |
688 | return __do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page); | |
689 | } | |
690 | out: | |
691 | /* | |
692 | * Use __pte_alloc instead of pte_alloc_map, because we can't | |
693 | * run pte_offset_map on the pmd, if an huge pmd could | |
694 | * materialize from under us from a different thread. | |
695 | */ | |
696 | if (unlikely(__pte_alloc(mm, vma, pmd, address))) | |
697 | return VM_FAULT_OOM; | |
698 | /* if an huge pmd materialized from under us just retry later */ | |
699 | if (unlikely(pmd_trans_huge(*pmd))) | |
700 | return 0; | |
701 | /* | |
702 | * A regular pmd is established and it can't morph into a huge pmd | |
703 | * from under us anymore at this point because we hold the mmap_sem | |
704 | * read mode and khugepaged takes it in write mode. So now it's | |
705 | * safe to run pte_offset_map(). | |
706 | */ | |
707 | pte = pte_offset_map(pmd, address); | |
708 | return handle_pte_fault(mm, vma, address, pte, pmd, flags); | |
709 | } | |
710 | ||
711 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, | |
712 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
713 | struct vm_area_struct *vma) | |
714 | { | |
715 | struct page *src_page; | |
716 | pmd_t pmd; | |
717 | pgtable_t pgtable; | |
718 | int ret; | |
719 | ||
720 | ret = -ENOMEM; | |
721 | pgtable = pte_alloc_one(dst_mm, addr); | |
722 | if (unlikely(!pgtable)) | |
723 | goto out; | |
724 | ||
725 | spin_lock(&dst_mm->page_table_lock); | |
726 | spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING); | |
727 | ||
728 | ret = -EAGAIN; | |
729 | pmd = *src_pmd; | |
730 | if (unlikely(!pmd_trans_huge(pmd))) { | |
731 | pte_free(dst_mm, pgtable); | |
732 | goto out_unlock; | |
733 | } | |
734 | if (unlikely(pmd_trans_splitting(pmd))) { | |
735 | /* split huge page running from under us */ | |
736 | spin_unlock(&src_mm->page_table_lock); | |
737 | spin_unlock(&dst_mm->page_table_lock); | |
738 | pte_free(dst_mm, pgtable); | |
739 | ||
740 | wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */ | |
741 | goto out; | |
742 | } | |
743 | src_page = pmd_page(pmd); | |
744 | VM_BUG_ON(!PageHead(src_page)); | |
745 | get_page(src_page); | |
746 | page_dup_rmap(src_page); | |
747 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
748 | ||
749 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
750 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
751 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
752 | prepare_pmd_huge_pte(pgtable, dst_mm); | |
753 | ||
754 | ret = 0; | |
755 | out_unlock: | |
756 | spin_unlock(&src_mm->page_table_lock); | |
757 | spin_unlock(&dst_mm->page_table_lock); | |
758 | out: | |
759 | return ret; | |
760 | } | |
761 | ||
762 | /* no "address" argument so destroys page coloring of some arch */ | |
763 | pgtable_t get_pmd_huge_pte(struct mm_struct *mm) | |
764 | { | |
765 | pgtable_t pgtable; | |
766 | ||
767 | assert_spin_locked(&mm->page_table_lock); | |
768 | ||
769 | /* FIFO */ | |
770 | pgtable = mm->pmd_huge_pte; | |
771 | if (list_empty(&pgtable->lru)) | |
772 | mm->pmd_huge_pte = NULL; | |
773 | else { | |
774 | mm->pmd_huge_pte = list_entry(pgtable->lru.next, | |
775 | struct page, lru); | |
776 | list_del(&pgtable->lru); | |
777 | } | |
778 | return pgtable; | |
779 | } | |
780 | ||
781 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, | |
782 | struct vm_area_struct *vma, | |
783 | unsigned long address, | |
784 | pmd_t *pmd, pmd_t orig_pmd, | |
785 | struct page *page, | |
786 | unsigned long haddr) | |
787 | { | |
788 | pgtable_t pgtable; | |
789 | pmd_t _pmd; | |
790 | int ret = 0, i; | |
791 | struct page **pages; | |
792 | ||
793 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
794 | GFP_KERNEL); | |
795 | if (unlikely(!pages)) { | |
796 | ret |= VM_FAULT_OOM; | |
797 | goto out; | |
798 | } | |
799 | ||
800 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
801 | pages[i] = alloc_page_vma(GFP_HIGHUSER_MOVABLE, | |
802 | vma, address); | |
b9bbfbe3 AA |
803 | if (unlikely(!pages[i] || |
804 | mem_cgroup_newpage_charge(pages[i], mm, | |
805 | GFP_KERNEL))) { | |
806 | if (pages[i]) | |
71e3aac0 | 807 | put_page(pages[i]); |
b9bbfbe3 AA |
808 | mem_cgroup_uncharge_start(); |
809 | while (--i >= 0) { | |
810 | mem_cgroup_uncharge_page(pages[i]); | |
811 | put_page(pages[i]); | |
812 | } | |
813 | mem_cgroup_uncharge_end(); | |
71e3aac0 AA |
814 | kfree(pages); |
815 | ret |= VM_FAULT_OOM; | |
816 | goto out; | |
817 | } | |
818 | } | |
819 | ||
820 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
821 | copy_user_highpage(pages[i], page + i, | |
822 | haddr + PAGE_SHIFT*i, vma); | |
823 | __SetPageUptodate(pages[i]); | |
824 | cond_resched(); | |
825 | } | |
826 | ||
827 | spin_lock(&mm->page_table_lock); | |
828 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
829 | goto out_free_pages; | |
830 | VM_BUG_ON(!PageHead(page)); | |
831 | ||
832 | pmdp_clear_flush_notify(vma, haddr, pmd); | |
833 | /* leave pmd empty until pte is filled */ | |
834 | ||
835 | pgtable = get_pmd_huge_pte(mm); | |
836 | pmd_populate(mm, &_pmd, pgtable); | |
837 | ||
838 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
839 | pte_t *pte, entry; | |
840 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
841 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
842 | page_add_new_anon_rmap(pages[i], vma, haddr); | |
843 | pte = pte_offset_map(&_pmd, haddr); | |
844 | VM_BUG_ON(!pte_none(*pte)); | |
845 | set_pte_at(mm, haddr, pte, entry); | |
846 | pte_unmap(pte); | |
847 | } | |
848 | kfree(pages); | |
849 | ||
850 | mm->nr_ptes++; | |
851 | smp_wmb(); /* make pte visible before pmd */ | |
852 | pmd_populate(mm, pmd, pgtable); | |
853 | page_remove_rmap(page); | |
854 | spin_unlock(&mm->page_table_lock); | |
855 | ||
856 | ret |= VM_FAULT_WRITE; | |
857 | put_page(page); | |
858 | ||
859 | out: | |
860 | return ret; | |
861 | ||
862 | out_free_pages: | |
863 | spin_unlock(&mm->page_table_lock); | |
b9bbfbe3 AA |
864 | mem_cgroup_uncharge_start(); |
865 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
866 | mem_cgroup_uncharge_page(pages[i]); | |
71e3aac0 | 867 | put_page(pages[i]); |
b9bbfbe3 AA |
868 | } |
869 | mem_cgroup_uncharge_end(); | |
71e3aac0 AA |
870 | kfree(pages); |
871 | goto out; | |
872 | } | |
873 | ||
874 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
875 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) | |
876 | { | |
877 | int ret = 0; | |
878 | struct page *page, *new_page; | |
879 | unsigned long haddr; | |
880 | ||
881 | VM_BUG_ON(!vma->anon_vma); | |
882 | spin_lock(&mm->page_table_lock); | |
883 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
884 | goto out_unlock; | |
885 | ||
886 | page = pmd_page(orig_pmd); | |
887 | VM_BUG_ON(!PageCompound(page) || !PageHead(page)); | |
888 | haddr = address & HPAGE_PMD_MASK; | |
889 | if (page_mapcount(page) == 1) { | |
890 | pmd_t entry; | |
891 | entry = pmd_mkyoung(orig_pmd); | |
892 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
893 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) | |
894 | update_mmu_cache(vma, address, entry); | |
895 | ret |= VM_FAULT_WRITE; | |
896 | goto out_unlock; | |
897 | } | |
898 | get_page(page); | |
899 | spin_unlock(&mm->page_table_lock); | |
900 | ||
901 | if (transparent_hugepage_enabled(vma) && | |
902 | !transparent_hugepage_debug_cow()) | |
0bbbc0b3 AA |
903 | new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
904 | vma, haddr); | |
71e3aac0 AA |
905 | else |
906 | new_page = NULL; | |
907 | ||
908 | if (unlikely(!new_page)) { | |
909 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, | |
910 | pmd, orig_pmd, page, haddr); | |
911 | put_page(page); | |
912 | goto out; | |
913 | } | |
914 | ||
b9bbfbe3 AA |
915 | if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) { |
916 | put_page(new_page); | |
917 | put_page(page); | |
918 | ret |= VM_FAULT_OOM; | |
919 | goto out; | |
920 | } | |
921 | ||
71e3aac0 AA |
922 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); |
923 | __SetPageUptodate(new_page); | |
924 | ||
925 | spin_lock(&mm->page_table_lock); | |
926 | put_page(page); | |
b9bbfbe3 AA |
927 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { |
928 | mem_cgroup_uncharge_page(new_page); | |
71e3aac0 | 929 | put_page(new_page); |
b9bbfbe3 | 930 | } else { |
71e3aac0 AA |
931 | pmd_t entry; |
932 | VM_BUG_ON(!PageHead(page)); | |
933 | entry = mk_pmd(new_page, vma->vm_page_prot); | |
934 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
935 | entry = pmd_mkhuge(entry); | |
936 | pmdp_clear_flush_notify(vma, haddr, pmd); | |
937 | page_add_new_anon_rmap(new_page, vma, haddr); | |
938 | set_pmd_at(mm, haddr, pmd, entry); | |
939 | update_mmu_cache(vma, address, entry); | |
940 | page_remove_rmap(page); | |
941 | put_page(page); | |
942 | ret |= VM_FAULT_WRITE; | |
943 | } | |
944 | out_unlock: | |
945 | spin_unlock(&mm->page_table_lock); | |
946 | out: | |
947 | return ret; | |
948 | } | |
949 | ||
950 | struct page *follow_trans_huge_pmd(struct mm_struct *mm, | |
951 | unsigned long addr, | |
952 | pmd_t *pmd, | |
953 | unsigned int flags) | |
954 | { | |
955 | struct page *page = NULL; | |
956 | ||
957 | assert_spin_locked(&mm->page_table_lock); | |
958 | ||
959 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
960 | goto out; | |
961 | ||
962 | page = pmd_page(*pmd); | |
963 | VM_BUG_ON(!PageHead(page)); | |
964 | if (flags & FOLL_TOUCH) { | |
965 | pmd_t _pmd; | |
966 | /* | |
967 | * We should set the dirty bit only for FOLL_WRITE but | |
968 | * for now the dirty bit in the pmd is meaningless. | |
969 | * And if the dirty bit will become meaningful and | |
970 | * we'll only set it with FOLL_WRITE, an atomic | |
971 | * set_bit will be required on the pmd to set the | |
972 | * young bit, instead of the current set_pmd_at. | |
973 | */ | |
974 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
975 | set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd); | |
976 | } | |
977 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; | |
978 | VM_BUG_ON(!PageCompound(page)); | |
979 | if (flags & FOLL_GET) | |
980 | get_page(page); | |
981 | ||
982 | out: | |
983 | return page; | |
984 | } | |
985 | ||
986 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, | |
987 | pmd_t *pmd) | |
988 | { | |
989 | int ret = 0; | |
990 | ||
991 | spin_lock(&tlb->mm->page_table_lock); | |
992 | if (likely(pmd_trans_huge(*pmd))) { | |
993 | if (unlikely(pmd_trans_splitting(*pmd))) { | |
994 | spin_unlock(&tlb->mm->page_table_lock); | |
995 | wait_split_huge_page(vma->anon_vma, | |
996 | pmd); | |
997 | } else { | |
998 | struct page *page; | |
999 | pgtable_t pgtable; | |
1000 | pgtable = get_pmd_huge_pte(tlb->mm); | |
1001 | page = pmd_page(*pmd); | |
1002 | pmd_clear(pmd); | |
1003 | page_remove_rmap(page); | |
1004 | VM_BUG_ON(page_mapcount(page) < 0); | |
1005 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1006 | VM_BUG_ON(!PageHead(page)); | |
1007 | spin_unlock(&tlb->mm->page_table_lock); | |
1008 | tlb_remove_page(tlb, page); | |
1009 | pte_free(tlb->mm, pgtable); | |
1010 | ret = 1; | |
1011 | } | |
1012 | } else | |
1013 | spin_unlock(&tlb->mm->page_table_lock); | |
1014 | ||
1015 | return ret; | |
1016 | } | |
1017 | ||
0ca1634d JW |
1018 | int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
1019 | unsigned long addr, unsigned long end, | |
1020 | unsigned char *vec) | |
1021 | { | |
1022 | int ret = 0; | |
1023 | ||
1024 | spin_lock(&vma->vm_mm->page_table_lock); | |
1025 | if (likely(pmd_trans_huge(*pmd))) { | |
1026 | ret = !pmd_trans_splitting(*pmd); | |
1027 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1028 | if (unlikely(!ret)) | |
1029 | wait_split_huge_page(vma->anon_vma, pmd); | |
1030 | else { | |
1031 | /* | |
1032 | * All logical pages in the range are present | |
1033 | * if backed by a huge page. | |
1034 | */ | |
1035 | memset(vec, 1, (end - addr) >> PAGE_SHIFT); | |
1036 | } | |
1037 | } else | |
1038 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1039 | ||
1040 | return ret; | |
1041 | } | |
1042 | ||
cd7548ab JW |
1043 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
1044 | unsigned long addr, pgprot_t newprot) | |
1045 | { | |
1046 | struct mm_struct *mm = vma->vm_mm; | |
1047 | int ret = 0; | |
1048 | ||
1049 | spin_lock(&mm->page_table_lock); | |
1050 | if (likely(pmd_trans_huge(*pmd))) { | |
1051 | if (unlikely(pmd_trans_splitting(*pmd))) { | |
1052 | spin_unlock(&mm->page_table_lock); | |
1053 | wait_split_huge_page(vma->anon_vma, pmd); | |
1054 | } else { | |
1055 | pmd_t entry; | |
1056 | ||
1057 | entry = pmdp_get_and_clear(mm, addr, pmd); | |
1058 | entry = pmd_modify(entry, newprot); | |
1059 | set_pmd_at(mm, addr, pmd, entry); | |
1060 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1061 | flush_tlb_range(vma, addr, addr + HPAGE_PMD_SIZE); | |
1062 | ret = 1; | |
1063 | } | |
1064 | } else | |
1065 | spin_unlock(&vma->vm_mm->page_table_lock); | |
1066 | ||
1067 | return ret; | |
1068 | } | |
1069 | ||
71e3aac0 AA |
1070 | pmd_t *page_check_address_pmd(struct page *page, |
1071 | struct mm_struct *mm, | |
1072 | unsigned long address, | |
1073 | enum page_check_address_pmd_flag flag) | |
1074 | { | |
1075 | pgd_t *pgd; | |
1076 | pud_t *pud; | |
1077 | pmd_t *pmd, *ret = NULL; | |
1078 | ||
1079 | if (address & ~HPAGE_PMD_MASK) | |
1080 | goto out; | |
1081 | ||
1082 | pgd = pgd_offset(mm, address); | |
1083 | if (!pgd_present(*pgd)) | |
1084 | goto out; | |
1085 | ||
1086 | pud = pud_offset(pgd, address); | |
1087 | if (!pud_present(*pud)) | |
1088 | goto out; | |
1089 | ||
1090 | pmd = pmd_offset(pud, address); | |
1091 | if (pmd_none(*pmd)) | |
1092 | goto out; | |
1093 | if (pmd_page(*pmd) != page) | |
1094 | goto out; | |
94fcc585 AA |
1095 | /* |
1096 | * split_vma() may create temporary aliased mappings. There is | |
1097 | * no risk as long as all huge pmd are found and have their | |
1098 | * splitting bit set before __split_huge_page_refcount | |
1099 | * runs. Finding the same huge pmd more than once during the | |
1100 | * same rmap walk is not a problem. | |
1101 | */ | |
1102 | if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG && | |
1103 | pmd_trans_splitting(*pmd)) | |
1104 | goto out; | |
71e3aac0 AA |
1105 | if (pmd_trans_huge(*pmd)) { |
1106 | VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG && | |
1107 | !pmd_trans_splitting(*pmd)); | |
1108 | ret = pmd; | |
1109 | } | |
1110 | out: | |
1111 | return ret; | |
1112 | } | |
1113 | ||
1114 | static int __split_huge_page_splitting(struct page *page, | |
1115 | struct vm_area_struct *vma, | |
1116 | unsigned long address) | |
1117 | { | |
1118 | struct mm_struct *mm = vma->vm_mm; | |
1119 | pmd_t *pmd; | |
1120 | int ret = 0; | |
1121 | ||
1122 | spin_lock(&mm->page_table_lock); | |
1123 | pmd = page_check_address_pmd(page, mm, address, | |
1124 | PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG); | |
1125 | if (pmd) { | |
1126 | /* | |
1127 | * We can't temporarily set the pmd to null in order | |
1128 | * to split it, the pmd must remain marked huge at all | |
1129 | * times or the VM won't take the pmd_trans_huge paths | |
1130 | * and it won't wait on the anon_vma->root->lock to | |
1131 | * serialize against split_huge_page*. | |
1132 | */ | |
1133 | pmdp_splitting_flush_notify(vma, address, pmd); | |
1134 | ret = 1; | |
1135 | } | |
1136 | spin_unlock(&mm->page_table_lock); | |
1137 | ||
1138 | return ret; | |
1139 | } | |
1140 | ||
1141 | static void __split_huge_page_refcount(struct page *page) | |
1142 | { | |
1143 | int i; | |
1144 | unsigned long head_index = page->index; | |
1145 | struct zone *zone = page_zone(page); | |
2c888cfb | 1146 | int zonestat; |
71e3aac0 AA |
1147 | |
1148 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
1149 | spin_lock_irq(&zone->lru_lock); | |
1150 | compound_lock(page); | |
1151 | ||
1152 | for (i = 1; i < HPAGE_PMD_NR; i++) { | |
1153 | struct page *page_tail = page + i; | |
1154 | ||
1155 | /* tail_page->_count cannot change */ | |
1156 | atomic_sub(atomic_read(&page_tail->_count), &page->_count); | |
1157 | BUG_ON(page_count(page) <= 0); | |
1158 | atomic_add(page_mapcount(page) + 1, &page_tail->_count); | |
1159 | BUG_ON(atomic_read(&page_tail->_count) <= 0); | |
1160 | ||
1161 | /* after clearing PageTail the gup refcount can be released */ | |
1162 | smp_mb(); | |
1163 | ||
1164 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; | |
1165 | page_tail->flags |= (page->flags & | |
1166 | ((1L << PG_referenced) | | |
1167 | (1L << PG_swapbacked) | | |
1168 | (1L << PG_mlocked) | | |
1169 | (1L << PG_uptodate))); | |
1170 | page_tail->flags |= (1L << PG_dirty); | |
1171 | ||
1172 | /* | |
1173 | * 1) clear PageTail before overwriting first_page | |
1174 | * 2) clear PageTail before clearing PageHead for VM_BUG_ON | |
1175 | */ | |
1176 | smp_wmb(); | |
1177 | ||
1178 | /* | |
1179 | * __split_huge_page_splitting() already set the | |
1180 | * splitting bit in all pmd that could map this | |
1181 | * hugepage, that will ensure no CPU can alter the | |
1182 | * mapcount on the head page. The mapcount is only | |
1183 | * accounted in the head page and it has to be | |
1184 | * transferred to all tail pages in the below code. So | |
1185 | * for this code to be safe, the split the mapcount | |
1186 | * can't change. But that doesn't mean userland can't | |
1187 | * keep changing and reading the page contents while | |
1188 | * we transfer the mapcount, so the pmd splitting | |
1189 | * status is achieved setting a reserved bit in the | |
1190 | * pmd, not by clearing the present bit. | |
1191 | */ | |
1192 | BUG_ON(page_mapcount(page_tail)); | |
1193 | page_tail->_mapcount = page->_mapcount; | |
1194 | ||
1195 | BUG_ON(page_tail->mapping); | |
1196 | page_tail->mapping = page->mapping; | |
1197 | ||
1198 | page_tail->index = ++head_index; | |
1199 | ||
1200 | BUG_ON(!PageAnon(page_tail)); | |
1201 | BUG_ON(!PageUptodate(page_tail)); | |
1202 | BUG_ON(!PageDirty(page_tail)); | |
1203 | BUG_ON(!PageSwapBacked(page_tail)); | |
1204 | ||
1205 | lru_add_page_tail(zone, page, page_tail); | |
1206 | } | |
1207 | ||
79134171 AA |
1208 | __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); |
1209 | __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR); | |
1210 | ||
2c888cfb RR |
1211 | /* |
1212 | * A hugepage counts for HPAGE_PMD_NR pages on the LRU statistics, | |
1213 | * so adjust those appropriately if this page is on the LRU. | |
1214 | */ | |
1215 | if (PageLRU(page)) { | |
1216 | zonestat = NR_LRU_BASE + page_lru(page); | |
1217 | __mod_zone_page_state(zone, zonestat, -(HPAGE_PMD_NR-1)); | |
1218 | } | |
1219 | ||
71e3aac0 AA |
1220 | ClearPageCompound(page); |
1221 | compound_unlock(page); | |
1222 | spin_unlock_irq(&zone->lru_lock); | |
1223 | ||
1224 | for (i = 1; i < HPAGE_PMD_NR; i++) { | |
1225 | struct page *page_tail = page + i; | |
1226 | BUG_ON(page_count(page_tail) <= 0); | |
1227 | /* | |
1228 | * Tail pages may be freed if there wasn't any mapping | |
1229 | * like if add_to_swap() is running on a lru page that | |
1230 | * had its mapping zapped. And freeing these pages | |
1231 | * requires taking the lru_lock so we do the put_page | |
1232 | * of the tail pages after the split is complete. | |
1233 | */ | |
1234 | put_page(page_tail); | |
1235 | } | |
1236 | ||
1237 | /* | |
1238 | * Only the head page (now become a regular page) is required | |
1239 | * to be pinned by the caller. | |
1240 | */ | |
1241 | BUG_ON(page_count(page) <= 0); | |
1242 | } | |
1243 | ||
1244 | static int __split_huge_page_map(struct page *page, | |
1245 | struct vm_area_struct *vma, | |
1246 | unsigned long address) | |
1247 | { | |
1248 | struct mm_struct *mm = vma->vm_mm; | |
1249 | pmd_t *pmd, _pmd; | |
1250 | int ret = 0, i; | |
1251 | pgtable_t pgtable; | |
1252 | unsigned long haddr; | |
1253 | ||
1254 | spin_lock(&mm->page_table_lock); | |
1255 | pmd = page_check_address_pmd(page, mm, address, | |
1256 | PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG); | |
1257 | if (pmd) { | |
1258 | pgtable = get_pmd_huge_pte(mm); | |
1259 | pmd_populate(mm, &_pmd, pgtable); | |
1260 | ||
1261 | for (i = 0, haddr = address; i < HPAGE_PMD_NR; | |
1262 | i++, haddr += PAGE_SIZE) { | |
1263 | pte_t *pte, entry; | |
1264 | BUG_ON(PageCompound(page+i)); | |
1265 | entry = mk_pte(page + i, vma->vm_page_prot); | |
1266 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
1267 | if (!pmd_write(*pmd)) | |
1268 | entry = pte_wrprotect(entry); | |
1269 | else | |
1270 | BUG_ON(page_mapcount(page) != 1); | |
1271 | if (!pmd_young(*pmd)) | |
1272 | entry = pte_mkold(entry); | |
1273 | pte = pte_offset_map(&_pmd, haddr); | |
1274 | BUG_ON(!pte_none(*pte)); | |
1275 | set_pte_at(mm, haddr, pte, entry); | |
1276 | pte_unmap(pte); | |
1277 | } | |
1278 | ||
1279 | mm->nr_ptes++; | |
1280 | smp_wmb(); /* make pte visible before pmd */ | |
1281 | /* | |
1282 | * Up to this point the pmd is present and huge and | |
1283 | * userland has the whole access to the hugepage | |
1284 | * during the split (which happens in place). If we | |
1285 | * overwrite the pmd with the not-huge version | |
1286 | * pointing to the pte here (which of course we could | |
1287 | * if all CPUs were bug free), userland could trigger | |
1288 | * a small page size TLB miss on the small sized TLB | |
1289 | * while the hugepage TLB entry is still established | |
1290 | * in the huge TLB. Some CPU doesn't like that. See | |
1291 | * http://support.amd.com/us/Processor_TechDocs/41322.pdf, | |
1292 | * Erratum 383 on page 93. Intel should be safe but is | |
1293 | * also warns that it's only safe if the permission | |
1294 | * and cache attributes of the two entries loaded in | |
1295 | * the two TLB is identical (which should be the case | |
1296 | * here). But it is generally safer to never allow | |
1297 | * small and huge TLB entries for the same virtual | |
1298 | * address to be loaded simultaneously. So instead of | |
1299 | * doing "pmd_populate(); flush_tlb_range();" we first | |
1300 | * mark the current pmd notpresent (atomically because | |
1301 | * here the pmd_trans_huge and pmd_trans_splitting | |
1302 | * must remain set at all times on the pmd until the | |
1303 | * split is complete for this pmd), then we flush the | |
1304 | * SMP TLB and finally we write the non-huge version | |
1305 | * of the pmd entry with pmd_populate. | |
1306 | */ | |
1307 | set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd)); | |
1308 | flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); | |
1309 | pmd_populate(mm, pmd, pgtable); | |
1310 | ret = 1; | |
1311 | } | |
1312 | spin_unlock(&mm->page_table_lock); | |
1313 | ||
1314 | return ret; | |
1315 | } | |
1316 | ||
1317 | /* must be called with anon_vma->root->lock hold */ | |
1318 | static void __split_huge_page(struct page *page, | |
1319 | struct anon_vma *anon_vma) | |
1320 | { | |
1321 | int mapcount, mapcount2; | |
1322 | struct anon_vma_chain *avc; | |
1323 | ||
1324 | BUG_ON(!PageHead(page)); | |
1325 | BUG_ON(PageTail(page)); | |
1326 | ||
1327 | mapcount = 0; | |
1328 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { | |
1329 | struct vm_area_struct *vma = avc->vma; | |
1330 | unsigned long addr = vma_address(page, vma); | |
1331 | BUG_ON(is_vma_temporary_stack(vma)); | |
1332 | if (addr == -EFAULT) | |
1333 | continue; | |
1334 | mapcount += __split_huge_page_splitting(page, vma, addr); | |
1335 | } | |
05759d38 AA |
1336 | /* |
1337 | * It is critical that new vmas are added to the tail of the | |
1338 | * anon_vma list. This guarantes that if copy_huge_pmd() runs | |
1339 | * and establishes a child pmd before | |
1340 | * __split_huge_page_splitting() freezes the parent pmd (so if | |
1341 | * we fail to prevent copy_huge_pmd() from running until the | |
1342 | * whole __split_huge_page() is complete), we will still see | |
1343 | * the newly established pmd of the child later during the | |
1344 | * walk, to be able to set it as pmd_trans_splitting too. | |
1345 | */ | |
1346 | if (mapcount != page_mapcount(page)) | |
1347 | printk(KERN_ERR "mapcount %d page_mapcount %d\n", | |
1348 | mapcount, page_mapcount(page)); | |
71e3aac0 AA |
1349 | BUG_ON(mapcount != page_mapcount(page)); |
1350 | ||
1351 | __split_huge_page_refcount(page); | |
1352 | ||
1353 | mapcount2 = 0; | |
1354 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { | |
1355 | struct vm_area_struct *vma = avc->vma; | |
1356 | unsigned long addr = vma_address(page, vma); | |
1357 | BUG_ON(is_vma_temporary_stack(vma)); | |
1358 | if (addr == -EFAULT) | |
1359 | continue; | |
1360 | mapcount2 += __split_huge_page_map(page, vma, addr); | |
1361 | } | |
05759d38 AA |
1362 | if (mapcount != mapcount2) |
1363 | printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n", | |
1364 | mapcount, mapcount2, page_mapcount(page)); | |
71e3aac0 AA |
1365 | BUG_ON(mapcount != mapcount2); |
1366 | } | |
1367 | ||
1368 | int split_huge_page(struct page *page) | |
1369 | { | |
1370 | struct anon_vma *anon_vma; | |
1371 | int ret = 1; | |
1372 | ||
1373 | BUG_ON(!PageAnon(page)); | |
1374 | anon_vma = page_lock_anon_vma(page); | |
1375 | if (!anon_vma) | |
1376 | goto out; | |
1377 | ret = 0; | |
1378 | if (!PageCompound(page)) | |
1379 | goto out_unlock; | |
1380 | ||
1381 | BUG_ON(!PageSwapBacked(page)); | |
1382 | __split_huge_page(page, anon_vma); | |
1383 | ||
1384 | BUG_ON(PageCompound(page)); | |
1385 | out_unlock: | |
1386 | page_unlock_anon_vma(anon_vma); | |
1387 | out: | |
1388 | return ret; | |
1389 | } | |
1390 | ||
0af4e98b AA |
1391 | int hugepage_madvise(unsigned long *vm_flags) |
1392 | { | |
1393 | /* | |
1394 | * Be somewhat over-protective like KSM for now! | |
1395 | */ | |
1396 | if (*vm_flags & (VM_HUGEPAGE | VM_SHARED | VM_MAYSHARE | | |
1397 | VM_PFNMAP | VM_IO | VM_DONTEXPAND | | |
1398 | VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE | | |
1399 | VM_MIXEDMAP | VM_SAO)) | |
1400 | return -EINVAL; | |
1401 | ||
1402 | *vm_flags |= VM_HUGEPAGE; | |
1403 | ||
1404 | return 0; | |
1405 | } | |
1406 | ||
ba76149f AA |
1407 | static int __init khugepaged_slab_init(void) |
1408 | { | |
1409 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
1410 | sizeof(struct mm_slot), | |
1411 | __alignof__(struct mm_slot), 0, NULL); | |
1412 | if (!mm_slot_cache) | |
1413 | return -ENOMEM; | |
1414 | ||
1415 | return 0; | |
1416 | } | |
1417 | ||
1418 | static void __init khugepaged_slab_free(void) | |
1419 | { | |
1420 | kmem_cache_destroy(mm_slot_cache); | |
1421 | mm_slot_cache = NULL; | |
1422 | } | |
1423 | ||
1424 | static inline struct mm_slot *alloc_mm_slot(void) | |
1425 | { | |
1426 | if (!mm_slot_cache) /* initialization failed */ | |
1427 | return NULL; | |
1428 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
1429 | } | |
1430 | ||
1431 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
1432 | { | |
1433 | kmem_cache_free(mm_slot_cache, mm_slot); | |
1434 | } | |
1435 | ||
1436 | static int __init mm_slots_hash_init(void) | |
1437 | { | |
1438 | mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head), | |
1439 | GFP_KERNEL); | |
1440 | if (!mm_slots_hash) | |
1441 | return -ENOMEM; | |
1442 | return 0; | |
1443 | } | |
1444 | ||
1445 | #if 0 | |
1446 | static void __init mm_slots_hash_free(void) | |
1447 | { | |
1448 | kfree(mm_slots_hash); | |
1449 | mm_slots_hash = NULL; | |
1450 | } | |
1451 | #endif | |
1452 | ||
1453 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
1454 | { | |
1455 | struct mm_slot *mm_slot; | |
1456 | struct hlist_head *bucket; | |
1457 | struct hlist_node *node; | |
1458 | ||
1459 | bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct)) | |
1460 | % MM_SLOTS_HASH_HEADS]; | |
1461 | hlist_for_each_entry(mm_slot, node, bucket, hash) { | |
1462 | if (mm == mm_slot->mm) | |
1463 | return mm_slot; | |
1464 | } | |
1465 | return NULL; | |
1466 | } | |
1467 | ||
1468 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
1469 | struct mm_slot *mm_slot) | |
1470 | { | |
1471 | struct hlist_head *bucket; | |
1472 | ||
1473 | bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct)) | |
1474 | % MM_SLOTS_HASH_HEADS]; | |
1475 | mm_slot->mm = mm; | |
1476 | hlist_add_head(&mm_slot->hash, bucket); | |
1477 | } | |
1478 | ||
1479 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
1480 | { | |
1481 | return atomic_read(&mm->mm_users) == 0; | |
1482 | } | |
1483 | ||
1484 | int __khugepaged_enter(struct mm_struct *mm) | |
1485 | { | |
1486 | struct mm_slot *mm_slot; | |
1487 | int wakeup; | |
1488 | ||
1489 | mm_slot = alloc_mm_slot(); | |
1490 | if (!mm_slot) | |
1491 | return -ENOMEM; | |
1492 | ||
1493 | /* __khugepaged_exit() must not run from under us */ | |
1494 | VM_BUG_ON(khugepaged_test_exit(mm)); | |
1495 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { | |
1496 | free_mm_slot(mm_slot); | |
1497 | return 0; | |
1498 | } | |
1499 | ||
1500 | spin_lock(&khugepaged_mm_lock); | |
1501 | insert_to_mm_slots_hash(mm, mm_slot); | |
1502 | /* | |
1503 | * Insert just behind the scanning cursor, to let the area settle | |
1504 | * down a little. | |
1505 | */ | |
1506 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
1507 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
1508 | spin_unlock(&khugepaged_mm_lock); | |
1509 | ||
1510 | atomic_inc(&mm->mm_count); | |
1511 | if (wakeup) | |
1512 | wake_up_interruptible(&khugepaged_wait); | |
1513 | ||
1514 | return 0; | |
1515 | } | |
1516 | ||
1517 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma) | |
1518 | { | |
1519 | unsigned long hstart, hend; | |
1520 | if (!vma->anon_vma) | |
1521 | /* | |
1522 | * Not yet faulted in so we will register later in the | |
1523 | * page fault if needed. | |
1524 | */ | |
1525 | return 0; | |
1526 | if (vma->vm_file || vma->vm_ops) | |
1527 | /* khugepaged not yet working on file or special mappings */ | |
1528 | return 0; | |
1529 | VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma)); | |
1530 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
1531 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1532 | if (hstart < hend) | |
1533 | return khugepaged_enter(vma); | |
1534 | return 0; | |
1535 | } | |
1536 | ||
1537 | void __khugepaged_exit(struct mm_struct *mm) | |
1538 | { | |
1539 | struct mm_slot *mm_slot; | |
1540 | int free = 0; | |
1541 | ||
1542 | spin_lock(&khugepaged_mm_lock); | |
1543 | mm_slot = get_mm_slot(mm); | |
1544 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
1545 | hlist_del(&mm_slot->hash); | |
1546 | list_del(&mm_slot->mm_node); | |
1547 | free = 1; | |
1548 | } | |
1549 | ||
1550 | if (free) { | |
1551 | spin_unlock(&khugepaged_mm_lock); | |
1552 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1553 | free_mm_slot(mm_slot); | |
1554 | mmdrop(mm); | |
1555 | } else if (mm_slot) { | |
1556 | spin_unlock(&khugepaged_mm_lock); | |
1557 | /* | |
1558 | * This is required to serialize against | |
1559 | * khugepaged_test_exit() (which is guaranteed to run | |
1560 | * under mmap sem read mode). Stop here (after we | |
1561 | * return all pagetables will be destroyed) until | |
1562 | * khugepaged has finished working on the pagetables | |
1563 | * under the mmap_sem. | |
1564 | */ | |
1565 | down_write(&mm->mmap_sem); | |
1566 | up_write(&mm->mmap_sem); | |
1567 | } else | |
1568 | spin_unlock(&khugepaged_mm_lock); | |
1569 | } | |
1570 | ||
1571 | static void release_pte_page(struct page *page) | |
1572 | { | |
1573 | /* 0 stands for page_is_file_cache(page) == false */ | |
1574 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
1575 | unlock_page(page); | |
1576 | putback_lru_page(page); | |
1577 | } | |
1578 | ||
1579 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
1580 | { | |
1581 | while (--_pte >= pte) { | |
1582 | pte_t pteval = *_pte; | |
1583 | if (!pte_none(pteval)) | |
1584 | release_pte_page(pte_page(pteval)); | |
1585 | } | |
1586 | } | |
1587 | ||
1588 | static void release_all_pte_pages(pte_t *pte) | |
1589 | { | |
1590 | release_pte_pages(pte, pte + HPAGE_PMD_NR); | |
1591 | } | |
1592 | ||
1593 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, | |
1594 | unsigned long address, | |
1595 | pte_t *pte) | |
1596 | { | |
1597 | struct page *page; | |
1598 | pte_t *_pte; | |
1599 | int referenced = 0, isolated = 0, none = 0; | |
1600 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1601 | _pte++, address += PAGE_SIZE) { | |
1602 | pte_t pteval = *_pte; | |
1603 | if (pte_none(pteval)) { | |
1604 | if (++none <= khugepaged_max_ptes_none) | |
1605 | continue; | |
1606 | else { | |
1607 | release_pte_pages(pte, _pte); | |
1608 | goto out; | |
1609 | } | |
1610 | } | |
1611 | if (!pte_present(pteval) || !pte_write(pteval)) { | |
1612 | release_pte_pages(pte, _pte); | |
1613 | goto out; | |
1614 | } | |
1615 | page = vm_normal_page(vma, address, pteval); | |
1616 | if (unlikely(!page)) { | |
1617 | release_pte_pages(pte, _pte); | |
1618 | goto out; | |
1619 | } | |
1620 | VM_BUG_ON(PageCompound(page)); | |
1621 | BUG_ON(!PageAnon(page)); | |
1622 | VM_BUG_ON(!PageSwapBacked(page)); | |
1623 | ||
1624 | /* cannot use mapcount: can't collapse if there's a gup pin */ | |
1625 | if (page_count(page) != 1) { | |
1626 | release_pte_pages(pte, _pte); | |
1627 | goto out; | |
1628 | } | |
1629 | /* | |
1630 | * We can do it before isolate_lru_page because the | |
1631 | * page can't be freed from under us. NOTE: PG_lock | |
1632 | * is needed to serialize against split_huge_page | |
1633 | * when invoked from the VM. | |
1634 | */ | |
1635 | if (!trylock_page(page)) { | |
1636 | release_pte_pages(pte, _pte); | |
1637 | goto out; | |
1638 | } | |
1639 | /* | |
1640 | * Isolate the page to avoid collapsing an hugepage | |
1641 | * currently in use by the VM. | |
1642 | */ | |
1643 | if (isolate_lru_page(page)) { | |
1644 | unlock_page(page); | |
1645 | release_pte_pages(pte, _pte); | |
1646 | goto out; | |
1647 | } | |
1648 | /* 0 stands for page_is_file_cache(page) == false */ | |
1649 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
1650 | VM_BUG_ON(!PageLocked(page)); | |
1651 | VM_BUG_ON(PageLRU(page)); | |
1652 | ||
1653 | /* If there is no mapped pte young don't collapse the page */ | |
8ee53820 AA |
1654 | if (pte_young(pteval) || PageReferenced(page) || |
1655 | mmu_notifier_test_young(vma->vm_mm, address)) | |
ba76149f AA |
1656 | referenced = 1; |
1657 | } | |
1658 | if (unlikely(!referenced)) | |
1659 | release_all_pte_pages(pte); | |
1660 | else | |
1661 | isolated = 1; | |
1662 | out: | |
1663 | return isolated; | |
1664 | } | |
1665 | ||
1666 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
1667 | struct vm_area_struct *vma, | |
1668 | unsigned long address, | |
1669 | spinlock_t *ptl) | |
1670 | { | |
1671 | pte_t *_pte; | |
1672 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { | |
1673 | pte_t pteval = *_pte; | |
1674 | struct page *src_page; | |
1675 | ||
1676 | if (pte_none(pteval)) { | |
1677 | clear_user_highpage(page, address); | |
1678 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
1679 | } else { | |
1680 | src_page = pte_page(pteval); | |
1681 | copy_user_highpage(page, src_page, address, vma); | |
1682 | VM_BUG_ON(page_mapcount(src_page) != 1); | |
1683 | VM_BUG_ON(page_count(src_page) != 2); | |
1684 | release_pte_page(src_page); | |
1685 | /* | |
1686 | * ptl mostly unnecessary, but preempt has to | |
1687 | * be disabled to update the per-cpu stats | |
1688 | * inside page_remove_rmap(). | |
1689 | */ | |
1690 | spin_lock(ptl); | |
1691 | /* | |
1692 | * paravirt calls inside pte_clear here are | |
1693 | * superfluous. | |
1694 | */ | |
1695 | pte_clear(vma->vm_mm, address, _pte); | |
1696 | page_remove_rmap(src_page); | |
1697 | spin_unlock(ptl); | |
1698 | free_page_and_swap_cache(src_page); | |
1699 | } | |
1700 | ||
1701 | address += PAGE_SIZE; | |
1702 | page++; | |
1703 | } | |
1704 | } | |
1705 | ||
1706 | static void collapse_huge_page(struct mm_struct *mm, | |
1707 | unsigned long address, | |
ce83d217 AA |
1708 | struct page **hpage, |
1709 | struct vm_area_struct *vma) | |
ba76149f | 1710 | { |
ba76149f AA |
1711 | pgd_t *pgd; |
1712 | pud_t *pud; | |
1713 | pmd_t *pmd, _pmd; | |
1714 | pte_t *pte; | |
1715 | pgtable_t pgtable; | |
1716 | struct page *new_page; | |
1717 | spinlock_t *ptl; | |
1718 | int isolated; | |
1719 | unsigned long hstart, hend; | |
1720 | ||
1721 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
0bbbc0b3 | 1722 | #ifndef CONFIG_NUMA |
ba76149f | 1723 | VM_BUG_ON(!*hpage); |
ce83d217 | 1724 | new_page = *hpage; |
0bbbc0b3 AA |
1725 | #else |
1726 | VM_BUG_ON(*hpage); | |
ce83d217 AA |
1727 | /* |
1728 | * Allocate the page while the vma is still valid and under | |
1729 | * the mmap_sem read mode so there is no memory allocation | |
1730 | * later when we take the mmap_sem in write mode. This is more | |
1731 | * friendly behavior (OTOH it may actually hide bugs) to | |
1732 | * filesystems in userland with daemons allocating memory in | |
1733 | * the userland I/O paths. Allocating memory with the | |
1734 | * mmap_sem in read mode is good idea also to allow greater | |
1735 | * scalability. | |
1736 | */ | |
1737 | new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address); | |
1738 | if (unlikely(!new_page)) { | |
1739 | up_read(&mm->mmap_sem); | |
1740 | *hpage = ERR_PTR(-ENOMEM); | |
1741 | return; | |
1742 | } | |
0bbbc0b3 | 1743 | #endif |
ce83d217 AA |
1744 | if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) { |
1745 | up_read(&mm->mmap_sem); | |
1746 | put_page(new_page); | |
1747 | return; | |
1748 | } | |
1749 | ||
1750 | /* after allocating the hugepage upgrade to mmap_sem write mode */ | |
1751 | up_read(&mm->mmap_sem); | |
ba76149f AA |
1752 | |
1753 | /* | |
1754 | * Prevent all access to pagetables with the exception of | |
1755 | * gup_fast later hanlded by the ptep_clear_flush and the VM | |
1756 | * handled by the anon_vma lock + PG_lock. | |
1757 | */ | |
1758 | down_write(&mm->mmap_sem); | |
1759 | if (unlikely(khugepaged_test_exit(mm))) | |
1760 | goto out; | |
1761 | ||
1762 | vma = find_vma(mm, address); | |
1763 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
1764 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1765 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
1766 | goto out; | |
1767 | ||
1768 | if (!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) | |
1769 | goto out; | |
1770 | ||
1771 | /* VM_PFNMAP vmas may have vm_ops null but vm_file set */ | |
1772 | if (!vma->anon_vma || vma->vm_ops || vma->vm_file) | |
1773 | goto out; | |
1774 | VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma)); | |
1775 | ||
1776 | pgd = pgd_offset(mm, address); | |
1777 | if (!pgd_present(*pgd)) | |
1778 | goto out; | |
1779 | ||
1780 | pud = pud_offset(pgd, address); | |
1781 | if (!pud_present(*pud)) | |
1782 | goto out; | |
1783 | ||
1784 | pmd = pmd_offset(pud, address); | |
1785 | /* pmd can't go away or become huge under us */ | |
1786 | if (!pmd_present(*pmd) || pmd_trans_huge(*pmd)) | |
1787 | goto out; | |
1788 | ||
ba76149f AA |
1789 | anon_vma_lock(vma->anon_vma); |
1790 | ||
1791 | pte = pte_offset_map(pmd, address); | |
1792 | ptl = pte_lockptr(mm, pmd); | |
1793 | ||
1794 | spin_lock(&mm->page_table_lock); /* probably unnecessary */ | |
1795 | /* | |
1796 | * After this gup_fast can't run anymore. This also removes | |
1797 | * any huge TLB entry from the CPU so we won't allow | |
1798 | * huge and small TLB entries for the same virtual address | |
1799 | * to avoid the risk of CPU bugs in that area. | |
1800 | */ | |
1801 | _pmd = pmdp_clear_flush_notify(vma, address, pmd); | |
1802 | spin_unlock(&mm->page_table_lock); | |
1803 | ||
1804 | spin_lock(ptl); | |
1805 | isolated = __collapse_huge_page_isolate(vma, address, pte); | |
1806 | spin_unlock(ptl); | |
1807 | pte_unmap(pte); | |
1808 | ||
1809 | if (unlikely(!isolated)) { | |
1810 | spin_lock(&mm->page_table_lock); | |
1811 | BUG_ON(!pmd_none(*pmd)); | |
1812 | set_pmd_at(mm, address, pmd, _pmd); | |
1813 | spin_unlock(&mm->page_table_lock); | |
1814 | anon_vma_unlock(vma->anon_vma); | |
1815 | mem_cgroup_uncharge_page(new_page); | |
ce83d217 | 1816 | goto out; |
ba76149f AA |
1817 | } |
1818 | ||
1819 | /* | |
1820 | * All pages are isolated and locked so anon_vma rmap | |
1821 | * can't run anymore. | |
1822 | */ | |
1823 | anon_vma_unlock(vma->anon_vma); | |
1824 | ||
1825 | __collapse_huge_page_copy(pte, new_page, vma, address, ptl); | |
1826 | __SetPageUptodate(new_page); | |
1827 | pgtable = pmd_pgtable(_pmd); | |
1828 | VM_BUG_ON(page_count(pgtable) != 1); | |
1829 | VM_BUG_ON(page_mapcount(pgtable) != 0); | |
1830 | ||
1831 | _pmd = mk_pmd(new_page, vma->vm_page_prot); | |
1832 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); | |
1833 | _pmd = pmd_mkhuge(_pmd); | |
1834 | ||
1835 | /* | |
1836 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
1837 | * this is needed to avoid the copy_huge_page writes to become | |
1838 | * visible after the set_pmd_at() write. | |
1839 | */ | |
1840 | smp_wmb(); | |
1841 | ||
1842 | spin_lock(&mm->page_table_lock); | |
1843 | BUG_ON(!pmd_none(*pmd)); | |
1844 | page_add_new_anon_rmap(new_page, vma, address); | |
1845 | set_pmd_at(mm, address, pmd, _pmd); | |
1846 | update_mmu_cache(vma, address, entry); | |
1847 | prepare_pmd_huge_pte(pgtable, mm); | |
1848 | mm->nr_ptes--; | |
1849 | spin_unlock(&mm->page_table_lock); | |
1850 | ||
0bbbc0b3 | 1851 | #ifndef CONFIG_NUMA |
ba76149f | 1852 | *hpage = NULL; |
0bbbc0b3 | 1853 | #endif |
ba76149f | 1854 | khugepaged_pages_collapsed++; |
ce83d217 | 1855 | out_up_write: |
ba76149f | 1856 | up_write(&mm->mmap_sem); |
0bbbc0b3 AA |
1857 | return; |
1858 | ||
ce83d217 | 1859 | out: |
0bbbc0b3 AA |
1860 | #ifdef CONFIG_NUMA |
1861 | put_page(new_page); | |
1862 | #endif | |
ce83d217 | 1863 | goto out_up_write; |
ba76149f AA |
1864 | } |
1865 | ||
1866 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
1867 | struct vm_area_struct *vma, | |
1868 | unsigned long address, | |
1869 | struct page **hpage) | |
1870 | { | |
1871 | pgd_t *pgd; | |
1872 | pud_t *pud; | |
1873 | pmd_t *pmd; | |
1874 | pte_t *pte, *_pte; | |
1875 | int ret = 0, referenced = 0, none = 0; | |
1876 | struct page *page; | |
1877 | unsigned long _address; | |
1878 | spinlock_t *ptl; | |
1879 | ||
1880 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1881 | ||
1882 | pgd = pgd_offset(mm, address); | |
1883 | if (!pgd_present(*pgd)) | |
1884 | goto out; | |
1885 | ||
1886 | pud = pud_offset(pgd, address); | |
1887 | if (!pud_present(*pud)) | |
1888 | goto out; | |
1889 | ||
1890 | pmd = pmd_offset(pud, address); | |
1891 | if (!pmd_present(*pmd) || pmd_trans_huge(*pmd)) | |
1892 | goto out; | |
1893 | ||
1894 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1895 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1896 | _pte++, _address += PAGE_SIZE) { | |
1897 | pte_t pteval = *_pte; | |
1898 | if (pte_none(pteval)) { | |
1899 | if (++none <= khugepaged_max_ptes_none) | |
1900 | continue; | |
1901 | else | |
1902 | goto out_unmap; | |
1903 | } | |
1904 | if (!pte_present(pteval) || !pte_write(pteval)) | |
1905 | goto out_unmap; | |
1906 | page = vm_normal_page(vma, _address, pteval); | |
1907 | if (unlikely(!page)) | |
1908 | goto out_unmap; | |
1909 | VM_BUG_ON(PageCompound(page)); | |
1910 | if (!PageLRU(page) || PageLocked(page) || !PageAnon(page)) | |
1911 | goto out_unmap; | |
1912 | /* cannot use mapcount: can't collapse if there's a gup pin */ | |
1913 | if (page_count(page) != 1) | |
1914 | goto out_unmap; | |
8ee53820 AA |
1915 | if (pte_young(pteval) || PageReferenced(page) || |
1916 | mmu_notifier_test_young(vma->vm_mm, address)) | |
ba76149f AA |
1917 | referenced = 1; |
1918 | } | |
1919 | if (referenced) | |
1920 | ret = 1; | |
1921 | out_unmap: | |
1922 | pte_unmap_unlock(pte, ptl); | |
ce83d217 AA |
1923 | if (ret) |
1924 | /* collapse_huge_page will return with the mmap_sem released */ | |
1925 | collapse_huge_page(mm, address, hpage, vma); | |
ba76149f AA |
1926 | out: |
1927 | return ret; | |
1928 | } | |
1929 | ||
1930 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
1931 | { | |
1932 | struct mm_struct *mm = mm_slot->mm; | |
1933 | ||
1934 | VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock)); | |
1935 | ||
1936 | if (khugepaged_test_exit(mm)) { | |
1937 | /* free mm_slot */ | |
1938 | hlist_del(&mm_slot->hash); | |
1939 | list_del(&mm_slot->mm_node); | |
1940 | ||
1941 | /* | |
1942 | * Not strictly needed because the mm exited already. | |
1943 | * | |
1944 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1945 | */ | |
1946 | ||
1947 | /* khugepaged_mm_lock actually not necessary for the below */ | |
1948 | free_mm_slot(mm_slot); | |
1949 | mmdrop(mm); | |
1950 | } | |
1951 | } | |
1952 | ||
1953 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
1954 | struct page **hpage) | |
1955 | { | |
1956 | struct mm_slot *mm_slot; | |
1957 | struct mm_struct *mm; | |
1958 | struct vm_area_struct *vma; | |
1959 | int progress = 0; | |
1960 | ||
1961 | VM_BUG_ON(!pages); | |
1962 | VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock)); | |
1963 | ||
1964 | if (khugepaged_scan.mm_slot) | |
1965 | mm_slot = khugepaged_scan.mm_slot; | |
1966 | else { | |
1967 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
1968 | struct mm_slot, mm_node); | |
1969 | khugepaged_scan.address = 0; | |
1970 | khugepaged_scan.mm_slot = mm_slot; | |
1971 | } | |
1972 | spin_unlock(&khugepaged_mm_lock); | |
1973 | ||
1974 | mm = mm_slot->mm; | |
1975 | down_read(&mm->mmap_sem); | |
1976 | if (unlikely(khugepaged_test_exit(mm))) | |
1977 | vma = NULL; | |
1978 | else | |
1979 | vma = find_vma(mm, khugepaged_scan.address); | |
1980 | ||
1981 | progress++; | |
1982 | for (; vma; vma = vma->vm_next) { | |
1983 | unsigned long hstart, hend; | |
1984 | ||
1985 | cond_resched(); | |
1986 | if (unlikely(khugepaged_test_exit(mm))) { | |
1987 | progress++; | |
1988 | break; | |
1989 | } | |
1990 | ||
1991 | if (!(vma->vm_flags & VM_HUGEPAGE) && | |
1992 | !khugepaged_always()) { | |
1993 | progress++; | |
1994 | continue; | |
1995 | } | |
1996 | ||
1997 | /* VM_PFNMAP vmas may have vm_ops null but vm_file set */ | |
1998 | if (!vma->anon_vma || vma->vm_ops || vma->vm_file) { | |
1999 | khugepaged_scan.address = vma->vm_end; | |
2000 | progress++; | |
2001 | continue; | |
2002 | } | |
2003 | VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma)); | |
2004 | ||
2005 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2006 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2007 | if (hstart >= hend) { | |
2008 | progress++; | |
2009 | continue; | |
2010 | } | |
2011 | if (khugepaged_scan.address < hstart) | |
2012 | khugepaged_scan.address = hstart; | |
2013 | if (khugepaged_scan.address > hend) { | |
2014 | khugepaged_scan.address = hend + HPAGE_PMD_SIZE; | |
2015 | progress++; | |
2016 | continue; | |
2017 | } | |
2018 | BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); | |
2019 | ||
2020 | while (khugepaged_scan.address < hend) { | |
2021 | int ret; | |
2022 | cond_resched(); | |
2023 | if (unlikely(khugepaged_test_exit(mm))) | |
2024 | goto breakouterloop; | |
2025 | ||
2026 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2027 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2028 | hend); | |
2029 | ret = khugepaged_scan_pmd(mm, vma, | |
2030 | khugepaged_scan.address, | |
2031 | hpage); | |
2032 | /* move to next address */ | |
2033 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2034 | progress += HPAGE_PMD_NR; | |
2035 | if (ret) | |
2036 | /* we released mmap_sem so break loop */ | |
2037 | goto breakouterloop_mmap_sem; | |
2038 | if (progress >= pages) | |
2039 | goto breakouterloop; | |
2040 | } | |
2041 | } | |
2042 | breakouterloop: | |
2043 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2044 | breakouterloop_mmap_sem: | |
2045 | ||
2046 | spin_lock(&khugepaged_mm_lock); | |
2047 | BUG_ON(khugepaged_scan.mm_slot != mm_slot); | |
2048 | /* | |
2049 | * Release the current mm_slot if this mm is about to die, or | |
2050 | * if we scanned all vmas of this mm. | |
2051 | */ | |
2052 | if (khugepaged_test_exit(mm) || !vma) { | |
2053 | /* | |
2054 | * Make sure that if mm_users is reaching zero while | |
2055 | * khugepaged runs here, khugepaged_exit will find | |
2056 | * mm_slot not pointing to the exiting mm. | |
2057 | */ | |
2058 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2059 | khugepaged_scan.mm_slot = list_entry( | |
2060 | mm_slot->mm_node.next, | |
2061 | struct mm_slot, mm_node); | |
2062 | khugepaged_scan.address = 0; | |
2063 | } else { | |
2064 | khugepaged_scan.mm_slot = NULL; | |
2065 | khugepaged_full_scans++; | |
2066 | } | |
2067 | ||
2068 | collect_mm_slot(mm_slot); | |
2069 | } | |
2070 | ||
2071 | return progress; | |
2072 | } | |
2073 | ||
2074 | static int khugepaged_has_work(void) | |
2075 | { | |
2076 | return !list_empty(&khugepaged_scan.mm_head) && | |
2077 | khugepaged_enabled(); | |
2078 | } | |
2079 | ||
2080 | static int khugepaged_wait_event(void) | |
2081 | { | |
2082 | return !list_empty(&khugepaged_scan.mm_head) || | |
2083 | !khugepaged_enabled(); | |
2084 | } | |
2085 | ||
2086 | static void khugepaged_do_scan(struct page **hpage) | |
2087 | { | |
2088 | unsigned int progress = 0, pass_through_head = 0; | |
2089 | unsigned int pages = khugepaged_pages_to_scan; | |
2090 | ||
2091 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2092 | ||
2093 | while (progress < pages) { | |
2094 | cond_resched(); | |
2095 | ||
0bbbc0b3 | 2096 | #ifndef CONFIG_NUMA |
ba76149f AA |
2097 | if (!*hpage) { |
2098 | *hpage = alloc_hugepage(khugepaged_defrag()); | |
2099 | if (unlikely(!*hpage)) | |
2100 | break; | |
2101 | } | |
0bbbc0b3 AA |
2102 | #else |
2103 | if (IS_ERR(*hpage)) | |
2104 | break; | |
2105 | #endif | |
ba76149f | 2106 | |
878aee7d AA |
2107 | if (unlikely(kthread_should_stop() || freezing(current))) |
2108 | break; | |
2109 | ||
ba76149f AA |
2110 | spin_lock(&khugepaged_mm_lock); |
2111 | if (!khugepaged_scan.mm_slot) | |
2112 | pass_through_head++; | |
2113 | if (khugepaged_has_work() && | |
2114 | pass_through_head < 2) | |
2115 | progress += khugepaged_scan_mm_slot(pages - progress, | |
2116 | hpage); | |
2117 | else | |
2118 | progress = pages; | |
2119 | spin_unlock(&khugepaged_mm_lock); | |
2120 | } | |
2121 | } | |
2122 | ||
0bbbc0b3 AA |
2123 | static void khugepaged_alloc_sleep(void) |
2124 | { | |
2125 | DEFINE_WAIT(wait); | |
2126 | add_wait_queue(&khugepaged_wait, &wait); | |
2127 | schedule_timeout_interruptible( | |
2128 | msecs_to_jiffies( | |
2129 | khugepaged_alloc_sleep_millisecs)); | |
2130 | remove_wait_queue(&khugepaged_wait, &wait); | |
2131 | } | |
2132 | ||
2133 | #ifndef CONFIG_NUMA | |
ba76149f AA |
2134 | static struct page *khugepaged_alloc_hugepage(void) |
2135 | { | |
2136 | struct page *hpage; | |
2137 | ||
2138 | do { | |
2139 | hpage = alloc_hugepage(khugepaged_defrag()); | |
0bbbc0b3 AA |
2140 | if (!hpage) |
2141 | khugepaged_alloc_sleep(); | |
ba76149f AA |
2142 | } while (unlikely(!hpage) && |
2143 | likely(khugepaged_enabled())); | |
2144 | return hpage; | |
2145 | } | |
0bbbc0b3 | 2146 | #endif |
ba76149f AA |
2147 | |
2148 | static void khugepaged_loop(void) | |
2149 | { | |
2150 | struct page *hpage; | |
2151 | ||
0bbbc0b3 AA |
2152 | #ifdef CONFIG_NUMA |
2153 | hpage = NULL; | |
2154 | #endif | |
ba76149f | 2155 | while (likely(khugepaged_enabled())) { |
0bbbc0b3 | 2156 | #ifndef CONFIG_NUMA |
ba76149f AA |
2157 | hpage = khugepaged_alloc_hugepage(); |
2158 | if (unlikely(!hpage)) | |
2159 | break; | |
0bbbc0b3 AA |
2160 | #else |
2161 | if (IS_ERR(hpage)) { | |
2162 | khugepaged_alloc_sleep(); | |
2163 | hpage = NULL; | |
2164 | } | |
2165 | #endif | |
ba76149f AA |
2166 | |
2167 | khugepaged_do_scan(&hpage); | |
0bbbc0b3 | 2168 | #ifndef CONFIG_NUMA |
ba76149f AA |
2169 | if (hpage) |
2170 | put_page(hpage); | |
0bbbc0b3 | 2171 | #endif |
878aee7d AA |
2172 | try_to_freeze(); |
2173 | if (unlikely(kthread_should_stop())) | |
2174 | break; | |
ba76149f AA |
2175 | if (khugepaged_has_work()) { |
2176 | DEFINE_WAIT(wait); | |
2177 | if (!khugepaged_scan_sleep_millisecs) | |
2178 | continue; | |
2179 | add_wait_queue(&khugepaged_wait, &wait); | |
2180 | schedule_timeout_interruptible( | |
2181 | msecs_to_jiffies( | |
2182 | khugepaged_scan_sleep_millisecs)); | |
2183 | remove_wait_queue(&khugepaged_wait, &wait); | |
2184 | } else if (khugepaged_enabled()) | |
878aee7d AA |
2185 | wait_event_freezable(khugepaged_wait, |
2186 | khugepaged_wait_event()); | |
ba76149f AA |
2187 | } |
2188 | } | |
2189 | ||
2190 | static int khugepaged(void *none) | |
2191 | { | |
2192 | struct mm_slot *mm_slot; | |
2193 | ||
878aee7d | 2194 | set_freezable(); |
ba76149f AA |
2195 | set_user_nice(current, 19); |
2196 | ||
2197 | /* serialize with start_khugepaged() */ | |
2198 | mutex_lock(&khugepaged_mutex); | |
2199 | ||
2200 | for (;;) { | |
2201 | mutex_unlock(&khugepaged_mutex); | |
2202 | BUG_ON(khugepaged_thread != current); | |
2203 | khugepaged_loop(); | |
2204 | BUG_ON(khugepaged_thread != current); | |
2205 | ||
2206 | mutex_lock(&khugepaged_mutex); | |
2207 | if (!khugepaged_enabled()) | |
2208 | break; | |
878aee7d AA |
2209 | if (unlikely(kthread_should_stop())) |
2210 | break; | |
ba76149f AA |
2211 | } |
2212 | ||
2213 | spin_lock(&khugepaged_mm_lock); | |
2214 | mm_slot = khugepaged_scan.mm_slot; | |
2215 | khugepaged_scan.mm_slot = NULL; | |
2216 | if (mm_slot) | |
2217 | collect_mm_slot(mm_slot); | |
2218 | spin_unlock(&khugepaged_mm_lock); | |
2219 | ||
2220 | khugepaged_thread = NULL; | |
2221 | mutex_unlock(&khugepaged_mutex); | |
2222 | ||
2223 | return 0; | |
2224 | } | |
2225 | ||
71e3aac0 AA |
2226 | void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd) |
2227 | { | |
2228 | struct page *page; | |
2229 | ||
2230 | spin_lock(&mm->page_table_lock); | |
2231 | if (unlikely(!pmd_trans_huge(*pmd))) { | |
2232 | spin_unlock(&mm->page_table_lock); | |
2233 | return; | |
2234 | } | |
2235 | page = pmd_page(*pmd); | |
2236 | VM_BUG_ON(!page_count(page)); | |
2237 | get_page(page); | |
2238 | spin_unlock(&mm->page_table_lock); | |
2239 | ||
2240 | split_huge_page(page); | |
2241 | ||
2242 | put_page(page); | |
2243 | BUG_ON(pmd_trans_huge(*pmd)); | |
2244 | } | |
94fcc585 AA |
2245 | |
2246 | static void split_huge_page_address(struct mm_struct *mm, | |
2247 | unsigned long address) | |
2248 | { | |
2249 | pgd_t *pgd; | |
2250 | pud_t *pud; | |
2251 | pmd_t *pmd; | |
2252 | ||
2253 | VM_BUG_ON(!(address & ~HPAGE_PMD_MASK)); | |
2254 | ||
2255 | pgd = pgd_offset(mm, address); | |
2256 | if (!pgd_present(*pgd)) | |
2257 | return; | |
2258 | ||
2259 | pud = pud_offset(pgd, address); | |
2260 | if (!pud_present(*pud)) | |
2261 | return; | |
2262 | ||
2263 | pmd = pmd_offset(pud, address); | |
2264 | if (!pmd_present(*pmd)) | |
2265 | return; | |
2266 | /* | |
2267 | * Caller holds the mmap_sem write mode, so a huge pmd cannot | |
2268 | * materialize from under us. | |
2269 | */ | |
2270 | split_huge_page_pmd(mm, pmd); | |
2271 | } | |
2272 | ||
2273 | void __vma_adjust_trans_huge(struct vm_area_struct *vma, | |
2274 | unsigned long start, | |
2275 | unsigned long end, | |
2276 | long adjust_next) | |
2277 | { | |
2278 | /* | |
2279 | * If the new start address isn't hpage aligned and it could | |
2280 | * previously contain an hugepage: check if we need to split | |
2281 | * an huge pmd. | |
2282 | */ | |
2283 | if (start & ~HPAGE_PMD_MASK && | |
2284 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
2285 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2286 | split_huge_page_address(vma->vm_mm, start); | |
2287 | ||
2288 | /* | |
2289 | * If the new end address isn't hpage aligned and it could | |
2290 | * previously contain an hugepage: check if we need to split | |
2291 | * an huge pmd. | |
2292 | */ | |
2293 | if (end & ~HPAGE_PMD_MASK && | |
2294 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
2295 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2296 | split_huge_page_address(vma->vm_mm, end); | |
2297 | ||
2298 | /* | |
2299 | * If we're also updating the vma->vm_next->vm_start, if the new | |
2300 | * vm_next->vm_start isn't page aligned and it could previously | |
2301 | * contain an hugepage: check if we need to split an huge pmd. | |
2302 | */ | |
2303 | if (adjust_next > 0) { | |
2304 | struct vm_area_struct *next = vma->vm_next; | |
2305 | unsigned long nstart = next->vm_start; | |
2306 | nstart += adjust_next << PAGE_SHIFT; | |
2307 | if (nstart & ~HPAGE_PMD_MASK && | |
2308 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
2309 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
2310 | split_huge_page_address(next->vm_mm, nstart); | |
2311 | } | |
2312 | } |