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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> |
15 | #include <linux/mm_inline.h> |
16 | #include <linux/kthread.h> |
17 | #include <linux/khugepaged.h> |
18 | #include <linux/freezer.h> |
19 | #include <linux/mman.h> |
20 | #include <asm/tlb.h> |
21 | #include <asm/pgalloc.h> |
22 | #include "internal.h" |
23 | |
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 | */ |
31 | unsigned long transparent_hugepage_flags __read_mostly = |
32 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS |
33 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| |
34 | #endif |
35 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE |
36 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| |
37 | #endif |
38 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)| |
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 | |
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 | |
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); |
160 | |
161 | set_recommended_min_free_kbytes(); |
162 | } else |
163 | /* wakeup to exit */ |
164 | wake_up_interruptible(&khugepaged_wait); |
165 | out: |
166 | return err; |
167 | } |
168 | |
169 | #ifdef CONFIG_SYSFS |
170 | |
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 | { |
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 | |
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 | |
238 | return ret; |
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 | return sprintf(buf, "%d\n", |
248 | !!test_bit(flag, &transparent_hugepage_flags)); |
249 | } |
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 | unsigned long value; |
257 | int ret; |
258 | |
259 | ret = kstrtoul(buf, 10, &value); |
260 | if (ret < 0) |
261 | return ret; |
262 | if (value > 1) |
263 | return -EINVAL; |
264 | |
265 | if (value) |
266 | set_bit(flag, &transparent_hugepage_flags); |
267 | else |
268 | clear_bit(flag, &transparent_hugepage_flags); |
269 | |
270 | return count; |
271 | } |
272 | |
273 | /* |
274 | * Currently defrag only disables __GFP_NOWAIT for allocation. A blind |
275 | * __GFP_REPEAT is too aggressive, it's never worth swapping tons of |
276 | * memory just to allocate one more hugepage. |
277 | */ |
278 | static ssize_t defrag_show(struct kobject *kobj, |
279 | struct kobj_attribute *attr, char *buf) |
280 | { |
281 | return double_flag_show(kobj, attr, buf, |
282 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, |
283 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); |
284 | } |
285 | static ssize_t defrag_store(struct kobject *kobj, |
286 | struct kobj_attribute *attr, |
287 | const char *buf, size_t count) |
288 | { |
289 | return double_flag_store(kobj, attr, buf, count, |
290 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, |
291 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); |
292 | } |
293 | static struct kobj_attribute defrag_attr = |
294 | __ATTR(defrag, 0644, defrag_show, defrag_store); |
295 | |
296 | #ifdef CONFIG_DEBUG_VM |
297 | static ssize_t debug_cow_show(struct kobject *kobj, |
298 | struct kobj_attribute *attr, char *buf) |
299 | { |
300 | return single_flag_show(kobj, attr, buf, |
301 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); |
302 | } |
303 | static ssize_t debug_cow_store(struct kobject *kobj, |
304 | struct kobj_attribute *attr, |
305 | const char *buf, size_t count) |
306 | { |
307 | return single_flag_store(kobj, attr, buf, count, |
308 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); |
309 | } |
310 | static struct kobj_attribute debug_cow_attr = |
311 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); |
312 | #endif /* CONFIG_DEBUG_VM */ |
313 | |
314 | static struct attribute *hugepage_attr[] = { |
315 | &enabled_attr.attr, |
316 | &defrag_attr.attr, |
317 | #ifdef CONFIG_DEBUG_VM |
318 | &debug_cow_attr.attr, |
319 | #endif |
320 | NULL, |
321 | }; |
322 | |
323 | static struct attribute_group hugepage_attr_group = { |
324 | .attrs = hugepage_attr, |
325 | }; |
326 | |
327 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, |
328 | struct kobj_attribute *attr, |
329 | char *buf) |
330 | { |
331 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); |
332 | } |
333 | |
334 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, |
335 | struct kobj_attribute *attr, |
336 | const char *buf, size_t count) |
337 | { |
338 | unsigned long msecs; |
339 | int err; |
340 | |
341 | err = strict_strtoul(buf, 10, &msecs); |
342 | if (err || msecs > UINT_MAX) |
343 | return -EINVAL; |
344 | |
345 | khugepaged_scan_sleep_millisecs = msecs; |
346 | wake_up_interruptible(&khugepaged_wait); |
347 | |
348 | return count; |
349 | } |
350 | static struct kobj_attribute scan_sleep_millisecs_attr = |
351 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, |
352 | scan_sleep_millisecs_store); |
353 | |
354 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, |
355 | struct kobj_attribute *attr, |
356 | char *buf) |
357 | { |
358 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); |
359 | } |
360 | |
361 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, |
362 | struct kobj_attribute *attr, |
363 | const char *buf, size_t count) |
364 | { |
365 | unsigned long msecs; |
366 | int err; |
367 | |
368 | err = strict_strtoul(buf, 10, &msecs); |
369 | if (err || msecs > UINT_MAX) |
370 | return -EINVAL; |
371 | |
372 | khugepaged_alloc_sleep_millisecs = msecs; |
373 | wake_up_interruptible(&khugepaged_wait); |
374 | |
375 | return count; |
376 | } |
377 | static struct kobj_attribute alloc_sleep_millisecs_attr = |
378 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, |
379 | alloc_sleep_millisecs_store); |
380 | |
381 | static ssize_t pages_to_scan_show(struct kobject *kobj, |
382 | struct kobj_attribute *attr, |
383 | char *buf) |
384 | { |
385 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); |
386 | } |
387 | static ssize_t pages_to_scan_store(struct kobject *kobj, |
388 | struct kobj_attribute *attr, |
389 | const char *buf, size_t count) |
390 | { |
391 | int err; |
392 | unsigned long pages; |
393 | |
394 | err = strict_strtoul(buf, 10, &pages); |
395 | if (err || !pages || pages > UINT_MAX) |
396 | return -EINVAL; |
397 | |
398 | khugepaged_pages_to_scan = pages; |
399 | |
400 | return count; |
401 | } |
402 | static struct kobj_attribute pages_to_scan_attr = |
403 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, |
404 | pages_to_scan_store); |
405 | |
406 | static ssize_t pages_collapsed_show(struct kobject *kobj, |
407 | struct kobj_attribute *attr, |
408 | char *buf) |
409 | { |
410 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); |
411 | } |
412 | static struct kobj_attribute pages_collapsed_attr = |
413 | __ATTR_RO(pages_collapsed); |
414 | |
415 | static ssize_t full_scans_show(struct kobject *kobj, |
416 | struct kobj_attribute *attr, |
417 | char *buf) |
418 | { |
419 | return sprintf(buf, "%u\n", khugepaged_full_scans); |
420 | } |
421 | static struct kobj_attribute full_scans_attr = |
422 | __ATTR_RO(full_scans); |
423 | |
424 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, |
425 | struct kobj_attribute *attr, char *buf) |
426 | { |
427 | return single_flag_show(kobj, attr, buf, |
428 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); |
429 | } |
430 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, |
431 | struct kobj_attribute *attr, |
432 | const char *buf, size_t count) |
433 | { |
434 | return single_flag_store(kobj, attr, buf, count, |
435 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); |
436 | } |
437 | static struct kobj_attribute khugepaged_defrag_attr = |
438 | __ATTR(defrag, 0644, khugepaged_defrag_show, |
439 | khugepaged_defrag_store); |
440 | |
441 | /* |
442 | * max_ptes_none controls if khugepaged should collapse hugepages over |
443 | * any unmapped ptes in turn potentially increasing the memory |
444 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not |
445 | * reduce the available free memory in the system as it |
446 | * runs. Increasing max_ptes_none will instead potentially reduce the |
447 | * free memory in the system during the khugepaged scan. |
448 | */ |
449 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, |
450 | struct kobj_attribute *attr, |
451 | char *buf) |
452 | { |
453 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); |
454 | } |
455 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, |
456 | struct kobj_attribute *attr, |
457 | const char *buf, size_t count) |
458 | { |
459 | int err; |
460 | unsigned long max_ptes_none; |
461 | |
462 | err = strict_strtoul(buf, 10, &max_ptes_none); |
463 | if (err || max_ptes_none > HPAGE_PMD_NR-1) |
464 | return -EINVAL; |
465 | |
466 | khugepaged_max_ptes_none = max_ptes_none; |
467 | |
468 | return count; |
469 | } |
470 | static struct kobj_attribute khugepaged_max_ptes_none_attr = |
471 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, |
472 | khugepaged_max_ptes_none_store); |
473 | |
474 | static struct attribute *khugepaged_attr[] = { |
475 | &khugepaged_defrag_attr.attr, |
476 | &khugepaged_max_ptes_none_attr.attr, |
477 | &pages_to_scan_attr.attr, |
478 | &pages_collapsed_attr.attr, |
479 | &full_scans_attr.attr, |
480 | &scan_sleep_millisecs_attr.attr, |
481 | &alloc_sleep_millisecs_attr.attr, |
482 | NULL, |
483 | }; |
484 | |
485 | static struct attribute_group khugepaged_attr_group = { |
486 | .attrs = khugepaged_attr, |
487 | .name = "khugepaged", |
488 | }; |
489 | #endif /* CONFIG_SYSFS */ |
490 | |
491 | static int __init hugepage_init(void) |
492 | { |
493 | int err; |
494 | #ifdef CONFIG_SYSFS |
495 | static struct kobject *hugepage_kobj; |
496 | #endif |
497 | |
498 | err = -EINVAL; |
499 | if (!has_transparent_hugepage()) { |
500 | transparent_hugepage_flags = 0; |
501 | goto out; |
502 | } |
503 | |
504 | #ifdef CONFIG_SYSFS |
505 | err = -ENOMEM; |
506 | hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); |
507 | if (unlikely(!hugepage_kobj)) { |
508 | printk(KERN_ERR "hugepage: failed kobject create\n"); |
509 | goto out; |
510 | } |
511 | |
512 | err = sysfs_create_group(hugepage_kobj, &hugepage_attr_group); |
513 | if (err) { |
514 | printk(KERN_ERR "hugepage: failed register hugeage group\n"); |
515 | goto out; |
516 | } |
517 | |
518 | err = sysfs_create_group(hugepage_kobj, &khugepaged_attr_group); |
519 | if (err) { |
520 | printk(KERN_ERR "hugepage: failed register hugeage group\n"); |
521 | goto out; |
522 | } |
523 | #endif |
524 | |
525 | err = khugepaged_slab_init(); |
526 | if (err) |
527 | goto out; |
528 | |
529 | err = mm_slots_hash_init(); |
530 | if (err) { |
531 | khugepaged_slab_free(); |
532 | goto out; |
533 | } |
534 | |
535 | /* |
536 | * By default disable transparent hugepages on smaller systems, |
537 | * where the extra memory used could hurt more than TLB overhead |
538 | * is likely to save. The admin can still enable it through /sys. |
539 | */ |
540 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) |
541 | transparent_hugepage_flags = 0; |
542 | |
543 | start_khugepaged(); |
544 | |
545 | set_recommended_min_free_kbytes(); |
546 | |
547 | out: |
548 | return err; |
549 | } |
550 | module_init(hugepage_init) |
551 | |
552 | static int __init setup_transparent_hugepage(char *str) |
553 | { |
554 | int ret = 0; |
555 | if (!str) |
556 | goto out; |
557 | if (!strcmp(str, "always")) { |
558 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, |
559 | &transparent_hugepage_flags); |
560 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, |
561 | &transparent_hugepage_flags); |
562 | ret = 1; |
563 | } else if (!strcmp(str, "madvise")) { |
564 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, |
565 | &transparent_hugepage_flags); |
566 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, |
567 | &transparent_hugepage_flags); |
568 | ret = 1; |
569 | } else if (!strcmp(str, "never")) { |
570 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, |
571 | &transparent_hugepage_flags); |
572 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, |
573 | &transparent_hugepage_flags); |
574 | ret = 1; |
575 | } |
576 | out: |
577 | if (!ret) |
578 | printk(KERN_WARNING |
579 | "transparent_hugepage= cannot parse, ignored\n"); |
580 | return ret; |
581 | } |
582 | __setup("transparent_hugepage=", setup_transparent_hugepage); |
583 | |
584 | static void prepare_pmd_huge_pte(pgtable_t pgtable, |
585 | struct mm_struct *mm) |
586 | { |
587 | assert_spin_locked(&mm->page_table_lock); |
588 | |
589 | /* FIFO */ |
590 | if (!mm->pmd_huge_pte) |
591 | INIT_LIST_HEAD(&pgtable->lru); |
592 | else |
593 | list_add(&pgtable->lru, &mm->pmd_huge_pte->lru); |
594 | mm->pmd_huge_pte = pgtable; |
595 | } |
596 | |
597 | static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) |
598 | { |
599 | if (likely(vma->vm_flags & VM_WRITE)) |
600 | pmd = pmd_mkwrite(pmd); |
601 | return pmd; |
602 | } |
603 | |
604 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, |
605 | struct vm_area_struct *vma, |
606 | unsigned long haddr, pmd_t *pmd, |
607 | struct page *page) |
608 | { |
609 | int ret = 0; |
610 | pgtable_t pgtable; |
611 | |
612 | VM_BUG_ON(!PageCompound(page)); |
613 | pgtable = pte_alloc_one(mm, haddr); |
614 | if (unlikely(!pgtable)) { |
615 | mem_cgroup_uncharge_page(page); |
616 | put_page(page); |
617 | return VM_FAULT_OOM; |
618 | } |
619 | |
620 | clear_huge_page(page, haddr, HPAGE_PMD_NR); |
621 | __SetPageUptodate(page); |
622 | |
623 | spin_lock(&mm->page_table_lock); |
624 | if (unlikely(!pmd_none(*pmd))) { |
625 | spin_unlock(&mm->page_table_lock); |
626 | mem_cgroup_uncharge_page(page); |
627 | put_page(page); |
628 | pte_free(mm, pgtable); |
629 | } else { |
630 | pmd_t entry; |
631 | entry = mk_pmd(page, vma->vm_page_prot); |
632 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); |
633 | entry = pmd_mkhuge(entry); |
634 | /* |
635 | * The spinlocking to take the lru_lock inside |
636 | * page_add_new_anon_rmap() acts as a full memory |
637 | * barrier to be sure clear_huge_page writes become |
638 | * visible after the set_pmd_at() write. |
639 | */ |
640 | page_add_new_anon_rmap(page, vma, haddr); |
641 | set_pmd_at(mm, haddr, pmd, entry); |
642 | prepare_pmd_huge_pte(pgtable, mm); |
643 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); |
644 | spin_unlock(&mm->page_table_lock); |
645 | } |
646 | |
647 | return ret; |
648 | } |
649 | |
650 | static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp) |
651 | { |
652 | return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp; |
653 | } |
654 | |
655 | static inline struct page *alloc_hugepage_vma(int defrag, |
656 | struct vm_area_struct *vma, |
657 | unsigned long haddr, int nd, |
658 | gfp_t extra_gfp) |
659 | { |
660 | return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp), |
661 | HPAGE_PMD_ORDER, vma, haddr, nd); |
662 | } |
663 | |
664 | #ifndef CONFIG_NUMA |
665 | static inline struct page *alloc_hugepage(int defrag) |
666 | { |
667 | return alloc_pages(alloc_hugepage_gfpmask(defrag, 0), |
668 | HPAGE_PMD_ORDER); |
669 | } |
670 | #endif |
671 | |
672 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, |
673 | unsigned long address, pmd_t *pmd, |
674 | unsigned int flags) |
675 | { |
676 | struct page *page; |
677 | unsigned long haddr = address & HPAGE_PMD_MASK; |
678 | pte_t *pte; |
679 | |
680 | if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) { |
681 | if (unlikely(anon_vma_prepare(vma))) |
682 | return VM_FAULT_OOM; |
683 | if (unlikely(khugepaged_enter(vma))) |
684 | return VM_FAULT_OOM; |
685 | page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
686 | vma, haddr, numa_node_id(), 0); |
687 | if (unlikely(!page)) { |
688 | count_vm_event(THP_FAULT_FALLBACK); |
689 | goto out; |
690 | } |
691 | count_vm_event(THP_FAULT_ALLOC); |
692 | if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) { |
693 | put_page(page); |
694 | goto out; |
695 | } |
696 | |
697 | return __do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page); |
698 | } |
699 | out: |
700 | /* |
701 | * Use __pte_alloc instead of pte_alloc_map, because we can't |
702 | * run pte_offset_map on the pmd, if an huge pmd could |
703 | * materialize from under us from a different thread. |
704 | */ |
705 | if (unlikely(__pte_alloc(mm, vma, pmd, address))) |
706 | return VM_FAULT_OOM; |
707 | /* if an huge pmd materialized from under us just retry later */ |
708 | if (unlikely(pmd_trans_huge(*pmd))) |
709 | return 0; |
710 | /* |
711 | * A regular pmd is established and it can't morph into a huge pmd |
712 | * from under us anymore at this point because we hold the mmap_sem |
713 | * read mode and khugepaged takes it in write mode. So now it's |
714 | * safe to run pte_offset_map(). |
715 | */ |
716 | pte = pte_offset_map(pmd, address); |
717 | return handle_pte_fault(mm, vma, address, pte, pmd, flags); |
718 | } |
719 | |
720 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
721 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, |
722 | struct vm_area_struct *vma) |
723 | { |
724 | struct page *src_page; |
725 | pmd_t pmd; |
726 | pgtable_t pgtable; |
727 | int ret; |
728 | |
729 | ret = -ENOMEM; |
730 | pgtable = pte_alloc_one(dst_mm, addr); |
731 | if (unlikely(!pgtable)) |
732 | goto out; |
733 | |
734 | spin_lock(&dst_mm->page_table_lock); |
735 | spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING); |
736 | |
737 | ret = -EAGAIN; |
738 | pmd = *src_pmd; |
739 | if (unlikely(!pmd_trans_huge(pmd))) { |
740 | pte_free(dst_mm, pgtable); |
741 | goto out_unlock; |
742 | } |
743 | if (unlikely(pmd_trans_splitting(pmd))) { |
744 | /* split huge page running from under us */ |
745 | spin_unlock(&src_mm->page_table_lock); |
746 | spin_unlock(&dst_mm->page_table_lock); |
747 | pte_free(dst_mm, pgtable); |
748 | |
749 | wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */ |
750 | goto out; |
751 | } |
752 | src_page = pmd_page(pmd); |
753 | VM_BUG_ON(!PageHead(src_page)); |
754 | get_page(src_page); |
755 | page_dup_rmap(src_page); |
756 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); |
757 | |
758 | pmdp_set_wrprotect(src_mm, addr, src_pmd); |
759 | pmd = pmd_mkold(pmd_wrprotect(pmd)); |
760 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); |
761 | prepare_pmd_huge_pte(pgtable, dst_mm); |
762 | |
763 | ret = 0; |
764 | out_unlock: |
765 | spin_unlock(&src_mm->page_table_lock); |
766 | spin_unlock(&dst_mm->page_table_lock); |
767 | out: |
768 | return ret; |
769 | } |
770 | |
771 | /* no "address" argument so destroys page coloring of some arch */ |
772 | pgtable_t get_pmd_huge_pte(struct mm_struct *mm) |
773 | { |
774 | pgtable_t pgtable; |
775 | |
776 | assert_spin_locked(&mm->page_table_lock); |
777 | |
778 | /* FIFO */ |
779 | pgtable = mm->pmd_huge_pte; |
780 | if (list_empty(&pgtable->lru)) |
781 | mm->pmd_huge_pte = NULL; |
782 | else { |
783 | mm->pmd_huge_pte = list_entry(pgtable->lru.next, |
784 | struct page, lru); |
785 | list_del(&pgtable->lru); |
786 | } |
787 | return pgtable; |
788 | } |
789 | |
790 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, |
791 | struct vm_area_struct *vma, |
792 | unsigned long address, |
793 | pmd_t *pmd, pmd_t orig_pmd, |
794 | struct page *page, |
795 | unsigned long haddr) |
796 | { |
797 | pgtable_t pgtable; |
798 | pmd_t _pmd; |
799 | int ret = 0, i; |
800 | struct page **pages; |
801 | |
802 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, |
803 | GFP_KERNEL); |
804 | if (unlikely(!pages)) { |
805 | ret |= VM_FAULT_OOM; |
806 | goto out; |
807 | } |
808 | |
809 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
810 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE | |
811 | __GFP_OTHER_NODE, |
812 | vma, address, page_to_nid(page)); |
813 | if (unlikely(!pages[i] || |
814 | mem_cgroup_newpage_charge(pages[i], mm, |
815 | GFP_KERNEL))) { |
816 | if (pages[i]) |
817 | put_page(pages[i]); |
818 | mem_cgroup_uncharge_start(); |
819 | while (--i >= 0) { |
820 | mem_cgroup_uncharge_page(pages[i]); |
821 | put_page(pages[i]); |
822 | } |
823 | mem_cgroup_uncharge_end(); |
824 | kfree(pages); |
825 | ret |= VM_FAULT_OOM; |
826 | goto out; |
827 | } |
828 | } |
829 | |
830 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
831 | copy_user_highpage(pages[i], page + i, |
832 | haddr + PAGE_SHIFT*i, vma); |
833 | __SetPageUptodate(pages[i]); |
834 | cond_resched(); |
835 | } |
836 | |
837 | spin_lock(&mm->page_table_lock); |
838 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
839 | goto out_free_pages; |
840 | VM_BUG_ON(!PageHead(page)); |
841 | |
842 | pmdp_clear_flush_notify(vma, haddr, pmd); |
843 | /* leave pmd empty until pte is filled */ |
844 | |
845 | pgtable = get_pmd_huge_pte(mm); |
846 | pmd_populate(mm, &_pmd, pgtable); |
847 | |
848 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { |
849 | pte_t *pte, entry; |
850 | entry = mk_pte(pages[i], vma->vm_page_prot); |
851 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
852 | page_add_new_anon_rmap(pages[i], vma, haddr); |
853 | pte = pte_offset_map(&_pmd, haddr); |
854 | VM_BUG_ON(!pte_none(*pte)); |
855 | set_pte_at(mm, haddr, pte, entry); |
856 | pte_unmap(pte); |
857 | } |
858 | kfree(pages); |
859 | |
860 | mm->nr_ptes++; |
861 | smp_wmb(); /* make pte visible before pmd */ |
862 | pmd_populate(mm, pmd, pgtable); |
863 | page_remove_rmap(page); |
864 | spin_unlock(&mm->page_table_lock); |
865 | |
866 | ret |= VM_FAULT_WRITE; |
867 | put_page(page); |
868 | |
869 | out: |
870 | return ret; |
871 | |
872 | out_free_pages: |
873 | spin_unlock(&mm->page_table_lock); |
874 | mem_cgroup_uncharge_start(); |
875 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
876 | mem_cgroup_uncharge_page(pages[i]); |
877 | put_page(pages[i]); |
878 | } |
879 | mem_cgroup_uncharge_end(); |
880 | kfree(pages); |
881 | goto out; |
882 | } |
883 | |
884 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, |
885 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) |
886 | { |
887 | int ret = 0; |
888 | struct page *page, *new_page; |
889 | unsigned long haddr; |
890 | |
891 | VM_BUG_ON(!vma->anon_vma); |
892 | spin_lock(&mm->page_table_lock); |
893 | if (unlikely(!pmd_same(*pmd, orig_pmd))) |
894 | goto out_unlock; |
895 | |
896 | page = pmd_page(orig_pmd); |
897 | VM_BUG_ON(!PageCompound(page) || !PageHead(page)); |
898 | haddr = address & HPAGE_PMD_MASK; |
899 | if (page_mapcount(page) == 1) { |
900 | pmd_t entry; |
901 | entry = pmd_mkyoung(orig_pmd); |
902 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); |
903 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) |
904 | update_mmu_cache(vma, address, entry); |
905 | ret |= VM_FAULT_WRITE; |
906 | goto out_unlock; |
907 | } |
908 | get_page(page); |
909 | spin_unlock(&mm->page_table_lock); |
910 | |
911 | if (transparent_hugepage_enabled(vma) && |
912 | !transparent_hugepage_debug_cow()) |
913 | new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
914 | vma, haddr, numa_node_id(), 0); |
915 | else |
916 | new_page = NULL; |
917 | |
918 | if (unlikely(!new_page)) { |
919 | count_vm_event(THP_FAULT_FALLBACK); |
920 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, |
921 | pmd, orig_pmd, page, haddr); |
922 | put_page(page); |
923 | goto out; |
924 | } |
925 | count_vm_event(THP_FAULT_ALLOC); |
926 | |
927 | if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) { |
928 | put_page(new_page); |
929 | put_page(page); |
930 | ret |= VM_FAULT_OOM; |
931 | goto out; |
932 | } |
933 | |
934 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); |
935 | __SetPageUptodate(new_page); |
936 | |
937 | spin_lock(&mm->page_table_lock); |
938 | put_page(page); |
939 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { |
940 | mem_cgroup_uncharge_page(new_page); |
941 | put_page(new_page); |
942 | } else { |
943 | pmd_t entry; |
944 | VM_BUG_ON(!PageHead(page)); |
945 | entry = mk_pmd(new_page, vma->vm_page_prot); |
946 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); |
947 | entry = pmd_mkhuge(entry); |
948 | pmdp_clear_flush_notify(vma, haddr, pmd); |
949 | page_add_new_anon_rmap(new_page, vma, haddr); |
950 | set_pmd_at(mm, haddr, pmd, entry); |
951 | update_mmu_cache(vma, address, entry); |
952 | page_remove_rmap(page); |
953 | put_page(page); |
954 | ret |= VM_FAULT_WRITE; |
955 | } |
956 | out_unlock: |
957 | spin_unlock(&mm->page_table_lock); |
958 | out: |
959 | return ret; |
960 | } |
961 | |
962 | struct page *follow_trans_huge_pmd(struct mm_struct *mm, |
963 | unsigned long addr, |
964 | pmd_t *pmd, |
965 | unsigned int flags) |
966 | { |
967 | struct page *page = NULL; |
968 | |
969 | assert_spin_locked(&mm->page_table_lock); |
970 | |
971 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) |
972 | goto out; |
973 | |
974 | page = pmd_page(*pmd); |
975 | VM_BUG_ON(!PageHead(page)); |
976 | if (flags & FOLL_TOUCH) { |
977 | pmd_t _pmd; |
978 | /* |
979 | * We should set the dirty bit only for FOLL_WRITE but |
980 | * for now the dirty bit in the pmd is meaningless. |
981 | * And if the dirty bit will become meaningful and |
982 | * we'll only set it with FOLL_WRITE, an atomic |
983 | * set_bit will be required on the pmd to set the |
984 | * young bit, instead of the current set_pmd_at. |
985 | */ |
986 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); |
987 | set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd); |
988 | } |
989 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
990 | VM_BUG_ON(!PageCompound(page)); |
991 | if (flags & FOLL_GET) |
992 | get_page(page); |
993 | |
994 | out: |
995 | return page; |
996 | } |
997 | |
998 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
999 | pmd_t *pmd) |
1000 | { |
1001 | int ret = 0; |
1002 | |
1003 | spin_lock(&tlb->mm->page_table_lock); |
1004 | if (likely(pmd_trans_huge(*pmd))) { |
1005 | if (unlikely(pmd_trans_splitting(*pmd))) { |
1006 | spin_unlock(&tlb->mm->page_table_lock); |
1007 | wait_split_huge_page(vma->anon_vma, |
1008 | pmd); |
1009 | } else { |
1010 | struct page *page; |
1011 | pgtable_t pgtable; |
1012 | pgtable = get_pmd_huge_pte(tlb->mm); |
1013 | page = pmd_page(*pmd); |
1014 | pmd_clear(pmd); |
1015 | page_remove_rmap(page); |
1016 | VM_BUG_ON(page_mapcount(page) < 0); |
1017 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); |
1018 | VM_BUG_ON(!PageHead(page)); |
1019 | spin_unlock(&tlb->mm->page_table_lock); |
1020 | tlb_remove_page(tlb, page); |
1021 | pte_free(tlb->mm, pgtable); |
1022 | ret = 1; |
1023 | } |
1024 | } else |
1025 | spin_unlock(&tlb->mm->page_table_lock); |
1026 | |
1027 | return ret; |
1028 | } |
1029 | |
1030 | int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
1031 | unsigned long addr, unsigned long end, |
1032 | unsigned char *vec) |
1033 | { |
1034 | int ret = 0; |
1035 | |
1036 | spin_lock(&vma->vm_mm->page_table_lock); |
1037 | if (likely(pmd_trans_huge(*pmd))) { |
1038 | ret = !pmd_trans_splitting(*pmd); |
1039 | spin_unlock(&vma->vm_mm->page_table_lock); |
1040 | if (unlikely(!ret)) |
1041 | wait_split_huge_page(vma->anon_vma, pmd); |
1042 | else { |
1043 | /* |
1044 | * All logical pages in the range are present |
1045 | * if backed by a huge page. |
1046 | */ |
1047 | memset(vec, 1, (end - addr) >> PAGE_SHIFT); |
1048 | } |
1049 | } else |
1050 | spin_unlock(&vma->vm_mm->page_table_lock); |
1051 | |
1052 | return ret; |
1053 | } |
1054 | |
1055 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
1056 | unsigned long addr, pgprot_t newprot) |
1057 | { |
1058 | struct mm_struct *mm = vma->vm_mm; |
1059 | int ret = 0; |
1060 | |
1061 | spin_lock(&mm->page_table_lock); |
1062 | if (likely(pmd_trans_huge(*pmd))) { |
1063 | if (unlikely(pmd_trans_splitting(*pmd))) { |
1064 | spin_unlock(&mm->page_table_lock); |
1065 | wait_split_huge_page(vma->anon_vma, pmd); |
1066 | } else { |
1067 | pmd_t entry; |
1068 | |
1069 | entry = pmdp_get_and_clear(mm, addr, pmd); |
1070 | entry = pmd_modify(entry, newprot); |
1071 | set_pmd_at(mm, addr, pmd, entry); |
1072 | spin_unlock(&vma->vm_mm->page_table_lock); |
1073 | flush_tlb_range(vma, addr, addr + HPAGE_PMD_SIZE); |
1074 | ret = 1; |
1075 | } |
1076 | } else |
1077 | spin_unlock(&vma->vm_mm->page_table_lock); |
1078 | |
1079 | return ret; |
1080 | } |
1081 | |
1082 | pmd_t *page_check_address_pmd(struct page *page, |
1083 | struct mm_struct *mm, |
1084 | unsigned long address, |
1085 | enum page_check_address_pmd_flag flag) |
1086 | { |
1087 | pgd_t *pgd; |
1088 | pud_t *pud; |
1089 | pmd_t *pmd, *ret = NULL; |
1090 | |
1091 | if (address & ~HPAGE_PMD_MASK) |
1092 | goto out; |
1093 | |
1094 | pgd = pgd_offset(mm, address); |
1095 | if (!pgd_present(*pgd)) |
1096 | goto out; |
1097 | |
1098 | pud = pud_offset(pgd, address); |
1099 | if (!pud_present(*pud)) |
1100 | goto out; |
1101 | |
1102 | pmd = pmd_offset(pud, address); |
1103 | if (pmd_none(*pmd)) |
1104 | goto out; |
1105 | if (pmd_page(*pmd) != page) |
1106 | goto out; |
1107 | /* |
1108 | * split_vma() may create temporary aliased mappings. There is |
1109 | * no risk as long as all huge pmd are found and have their |
1110 | * splitting bit set before __split_huge_page_refcount |
1111 | * runs. Finding the same huge pmd more than once during the |
1112 | * same rmap walk is not a problem. |
1113 | */ |
1114 | if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG && |
1115 | pmd_trans_splitting(*pmd)) |
1116 | goto out; |
1117 | if (pmd_trans_huge(*pmd)) { |
1118 | VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG && |
1119 | !pmd_trans_splitting(*pmd)); |
1120 | ret = pmd; |
1121 | } |
1122 | out: |
1123 | return ret; |
1124 | } |
1125 | |
1126 | static int __split_huge_page_splitting(struct page *page, |
1127 | struct vm_area_struct *vma, |
1128 | unsigned long address) |
1129 | { |
1130 | struct mm_struct *mm = vma->vm_mm; |
1131 | pmd_t *pmd; |
1132 | int ret = 0; |
1133 | |
1134 | spin_lock(&mm->page_table_lock); |
1135 | pmd = page_check_address_pmd(page, mm, address, |
1136 | PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG); |
1137 | if (pmd) { |
1138 | /* |
1139 | * We can't temporarily set the pmd to null in order |
1140 | * to split it, the pmd must remain marked huge at all |
1141 | * times or the VM won't take the pmd_trans_huge paths |
1142 | * and it won't wait on the anon_vma->root->mutex to |
1143 | * serialize against split_huge_page*. |
1144 | */ |
1145 | pmdp_splitting_flush_notify(vma, address, pmd); |
1146 | ret = 1; |
1147 | } |
1148 | spin_unlock(&mm->page_table_lock); |
1149 | |
1150 | return ret; |
1151 | } |
1152 | |
1153 | static void __split_huge_page_refcount(struct page *page) |
1154 | { |
1155 | int i; |
1156 | unsigned long head_index = page->index; |
1157 | struct zone *zone = page_zone(page); |
1158 | int zonestat; |
1159 | |
1160 | /* prevent PageLRU to go away from under us, and freeze lru stats */ |
1161 | spin_lock_irq(&zone->lru_lock); |
1162 | compound_lock(page); |
1163 | |
1164 | for (i = 1; i < HPAGE_PMD_NR; i++) { |
1165 | struct page *page_tail = page + i; |
1166 | |
1167 | /* tail_page->_count cannot change */ |
1168 | atomic_sub(atomic_read(&page_tail->_count), &page->_count); |
1169 | BUG_ON(page_count(page) <= 0); |
1170 | atomic_add(page_mapcount(page) + 1, &page_tail->_count); |
1171 | BUG_ON(atomic_read(&page_tail->_count) <= 0); |
1172 | |
1173 | /* after clearing PageTail the gup refcount can be released */ |
1174 | smp_mb(); |
1175 | |
1176 | /* |
1177 | * retain hwpoison flag of the poisoned tail page: |
1178 | * fix for the unsuitable process killed on Guest Machine(KVM) |
1179 | * by the memory-failure. |
1180 | */ |
1181 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON; |
1182 | page_tail->flags |= (page->flags & |
1183 | ((1L << PG_referenced) | |
1184 | (1L << PG_swapbacked) | |
1185 | (1L << PG_mlocked) | |
1186 | (1L << PG_uptodate))); |
1187 | page_tail->flags |= (1L << PG_dirty); |
1188 | |
1189 | /* |
1190 | * 1) clear PageTail before overwriting first_page |
1191 | * 2) clear PageTail before clearing PageHead for VM_BUG_ON |
1192 | */ |
1193 | smp_wmb(); |
1194 | |
1195 | /* |
1196 | * __split_huge_page_splitting() already set the |
1197 | * splitting bit in all pmd that could map this |
1198 | * hugepage, that will ensure no CPU can alter the |
1199 | * mapcount on the head page. The mapcount is only |
1200 | * accounted in the head page and it has to be |
1201 | * transferred to all tail pages in the below code. So |
1202 | * for this code to be safe, the split the mapcount |
1203 | * can't change. But that doesn't mean userland can't |
1204 | * keep changing and reading the page contents while |
1205 | * we transfer the mapcount, so the pmd splitting |
1206 | * status is achieved setting a reserved bit in the |
1207 | * pmd, not by clearing the present bit. |
1208 | */ |
1209 | BUG_ON(page_mapcount(page_tail)); |
1210 | page_tail->_mapcount = page->_mapcount; |
1211 | |
1212 | BUG_ON(page_tail->mapping); |
1213 | page_tail->mapping = page->mapping; |
1214 | |
1215 | page_tail->index = ++head_index; |
1216 | |
1217 | BUG_ON(!PageAnon(page_tail)); |
1218 | BUG_ON(!PageUptodate(page_tail)); |
1219 | BUG_ON(!PageDirty(page_tail)); |
1220 | BUG_ON(!PageSwapBacked(page_tail)); |
1221 | |
1222 | mem_cgroup_split_huge_fixup(page, page_tail); |
1223 | |
1224 | lru_add_page_tail(zone, page, page_tail); |
1225 | } |
1226 | |
1227 | __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); |
1228 | __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR); |
1229 | |
1230 | /* |
1231 | * A hugepage counts for HPAGE_PMD_NR pages on the LRU statistics, |
1232 | * so adjust those appropriately if this page is on the LRU. |
1233 | */ |
1234 | if (PageLRU(page)) { |
1235 | zonestat = NR_LRU_BASE + page_lru(page); |
1236 | __mod_zone_page_state(zone, zonestat, -(HPAGE_PMD_NR-1)); |
1237 | } |
1238 | |
1239 | ClearPageCompound(page); |
1240 | compound_unlock(page); |
1241 | spin_unlock_irq(&zone->lru_lock); |
1242 | |
1243 | for (i = 1; i < HPAGE_PMD_NR; i++) { |
1244 | struct page *page_tail = page + i; |
1245 | BUG_ON(page_count(page_tail) <= 0); |
1246 | /* |
1247 | * Tail pages may be freed if there wasn't any mapping |
1248 | * like if add_to_swap() is running on a lru page that |
1249 | * had its mapping zapped. And freeing these pages |
1250 | * requires taking the lru_lock so we do the put_page |
1251 | * of the tail pages after the split is complete. |
1252 | */ |
1253 | put_page(page_tail); |
1254 | } |
1255 | |
1256 | /* |
1257 | * Only the head page (now become a regular page) is required |
1258 | * to be pinned by the caller. |
1259 | */ |
1260 | BUG_ON(page_count(page) <= 0); |
1261 | } |
1262 | |
1263 | static int __split_huge_page_map(struct page *page, |
1264 | struct vm_area_struct *vma, |
1265 | unsigned long address) |
1266 | { |
1267 | struct mm_struct *mm = vma->vm_mm; |
1268 | pmd_t *pmd, _pmd; |
1269 | int ret = 0, i; |
1270 | pgtable_t pgtable; |
1271 | unsigned long haddr; |
1272 | |
1273 | spin_lock(&mm->page_table_lock); |
1274 | pmd = page_check_address_pmd(page, mm, address, |
1275 | PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG); |
1276 | if (pmd) { |
1277 | pgtable = get_pmd_huge_pte(mm); |
1278 | pmd_populate(mm, &_pmd, pgtable); |
1279 | |
1280 | for (i = 0, haddr = address; i < HPAGE_PMD_NR; |
1281 | i++, haddr += PAGE_SIZE) { |
1282 | pte_t *pte, entry; |
1283 | BUG_ON(PageCompound(page+i)); |
1284 | entry = mk_pte(page + i, vma->vm_page_prot); |
1285 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
1286 | if (!pmd_write(*pmd)) |
1287 | entry = pte_wrprotect(entry); |
1288 | else |
1289 | BUG_ON(page_mapcount(page) != 1); |
1290 | if (!pmd_young(*pmd)) |
1291 | entry = pte_mkold(entry); |
1292 | pte = pte_offset_map(&_pmd, haddr); |
1293 | BUG_ON(!pte_none(*pte)); |
1294 | set_pte_at(mm, haddr, pte, entry); |
1295 | pte_unmap(pte); |
1296 | } |
1297 | |
1298 | mm->nr_ptes++; |
1299 | smp_wmb(); /* make pte visible before pmd */ |
1300 | /* |
1301 | * Up to this point the pmd is present and huge and |
1302 | * userland has the whole access to the hugepage |
1303 | * during the split (which happens in place). If we |
1304 | * overwrite the pmd with the not-huge version |
1305 | * pointing to the pte here (which of course we could |
1306 | * if all CPUs were bug free), userland could trigger |
1307 | * a small page size TLB miss on the small sized TLB |
1308 | * while the hugepage TLB entry is still established |
1309 | * in the huge TLB. Some CPU doesn't like that. See |
1310 | * http://support.amd.com/us/Processor_TechDocs/41322.pdf, |
1311 | * Erratum 383 on page 93. Intel should be safe but is |
1312 | * also warns that it's only safe if the permission |
1313 | * and cache attributes of the two entries loaded in |
1314 | * the two TLB is identical (which should be the case |
1315 | * here). But it is generally safer to never allow |
1316 | * small and huge TLB entries for the same virtual |
1317 | * address to be loaded simultaneously. So instead of |
1318 | * doing "pmd_populate(); flush_tlb_range();" we first |
1319 | * mark the current pmd notpresent (atomically because |
1320 | * here the pmd_trans_huge and pmd_trans_splitting |
1321 | * must remain set at all times on the pmd until the |
1322 | * split is complete for this pmd), then we flush the |
1323 | * SMP TLB and finally we write the non-huge version |
1324 | * of the pmd entry with pmd_populate. |
1325 | */ |
1326 | set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd)); |
1327 | flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); |
1328 | pmd_populate(mm, pmd, pgtable); |
1329 | ret = 1; |
1330 | } |
1331 | spin_unlock(&mm->page_table_lock); |
1332 | |
1333 | return ret; |
1334 | } |
1335 | |
1336 | /* must be called with anon_vma->root->mutex hold */ |
1337 | static void __split_huge_page(struct page *page, |
1338 | struct anon_vma *anon_vma) |
1339 | { |
1340 | int mapcount, mapcount2; |
1341 | struct anon_vma_chain *avc; |
1342 | |
1343 | BUG_ON(!PageHead(page)); |
1344 | BUG_ON(PageTail(page)); |
1345 | |
1346 | mapcount = 0; |
1347 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { |
1348 | struct vm_area_struct *vma = avc->vma; |
1349 | unsigned long addr = vma_address(page, vma); |
1350 | BUG_ON(is_vma_temporary_stack(vma)); |
1351 | if (addr == -EFAULT) |
1352 | continue; |
1353 | mapcount += __split_huge_page_splitting(page, vma, addr); |
1354 | } |
1355 | /* |
1356 | * It is critical that new vmas are added to the tail of the |
1357 | * anon_vma list. This guarantes that if copy_huge_pmd() runs |
1358 | * and establishes a child pmd before |
1359 | * __split_huge_page_splitting() freezes the parent pmd (so if |
1360 | * we fail to prevent copy_huge_pmd() from running until the |
1361 | * whole __split_huge_page() is complete), we will still see |
1362 | * the newly established pmd of the child later during the |
1363 | * walk, to be able to set it as pmd_trans_splitting too. |
1364 | */ |
1365 | if (mapcount != page_mapcount(page)) |
1366 | printk(KERN_ERR "mapcount %d page_mapcount %d\n", |
1367 | mapcount, page_mapcount(page)); |
1368 | BUG_ON(mapcount != page_mapcount(page)); |
1369 | |
1370 | __split_huge_page_refcount(page); |
1371 | |
1372 | mapcount2 = 0; |
1373 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { |
1374 | struct vm_area_struct *vma = avc->vma; |
1375 | unsigned long addr = vma_address(page, vma); |
1376 | BUG_ON(is_vma_temporary_stack(vma)); |
1377 | if (addr == -EFAULT) |
1378 | continue; |
1379 | mapcount2 += __split_huge_page_map(page, vma, addr); |
1380 | } |
1381 | if (mapcount != mapcount2) |
1382 | printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n", |
1383 | mapcount, mapcount2, page_mapcount(page)); |
1384 | BUG_ON(mapcount != mapcount2); |
1385 | } |
1386 | |
1387 | int split_huge_page(struct page *page) |
1388 | { |
1389 | struct anon_vma *anon_vma; |
1390 | int ret = 1; |
1391 | |
1392 | BUG_ON(!PageAnon(page)); |
1393 | anon_vma = page_lock_anon_vma(page); |
1394 | if (!anon_vma) |
1395 | goto out; |
1396 | ret = 0; |
1397 | if (!PageCompound(page)) |
1398 | goto out_unlock; |
1399 | |
1400 | BUG_ON(!PageSwapBacked(page)); |
1401 | __split_huge_page(page, anon_vma); |
1402 | count_vm_event(THP_SPLIT); |
1403 | |
1404 | BUG_ON(PageCompound(page)); |
1405 | out_unlock: |
1406 | page_unlock_anon_vma(anon_vma); |
1407 | out: |
1408 | return ret; |
1409 | } |
1410 | |
1411 | #define VM_NO_THP (VM_SPECIAL|VM_INSERTPAGE|VM_MIXEDMAP|VM_SAO| \ |
1412 | VM_HUGETLB|VM_SHARED|VM_MAYSHARE) |
1413 | |
1414 | int hugepage_madvise(struct vm_area_struct *vma, |
1415 | unsigned long *vm_flags, int advice) |
1416 | { |
1417 | switch (advice) { |
1418 | case MADV_HUGEPAGE: |
1419 | /* |
1420 | * Be somewhat over-protective like KSM for now! |
1421 | */ |
1422 | if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP)) |
1423 | return -EINVAL; |
1424 | *vm_flags &= ~VM_NOHUGEPAGE; |
1425 | *vm_flags |= VM_HUGEPAGE; |
1426 | /* |
1427 | * If the vma become good for khugepaged to scan, |
1428 | * register it here without waiting a page fault that |
1429 | * may not happen any time soon. |
1430 | */ |
1431 | if (unlikely(khugepaged_enter_vma_merge(vma))) |
1432 | return -ENOMEM; |
1433 | break; |
1434 | case MADV_NOHUGEPAGE: |
1435 | /* |
1436 | * Be somewhat over-protective like KSM for now! |
1437 | */ |
1438 | if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP)) |
1439 | return -EINVAL; |
1440 | *vm_flags &= ~VM_HUGEPAGE; |
1441 | *vm_flags |= VM_NOHUGEPAGE; |
1442 | /* |
1443 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning |
1444 | * this vma even if we leave the mm registered in khugepaged if |
1445 | * it got registered before VM_NOHUGEPAGE was set. |
1446 | */ |
1447 | break; |
1448 | } |
1449 | |
1450 | return 0; |
1451 | } |
1452 | |
1453 | static int __init khugepaged_slab_init(void) |
1454 | { |
1455 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", |
1456 | sizeof(struct mm_slot), |
1457 | __alignof__(struct mm_slot), 0, NULL); |
1458 | if (!mm_slot_cache) |
1459 | return -ENOMEM; |
1460 | |
1461 | return 0; |
1462 | } |
1463 | |
1464 | static void __init khugepaged_slab_free(void) |
1465 | { |
1466 | kmem_cache_destroy(mm_slot_cache); |
1467 | mm_slot_cache = NULL; |
1468 | } |
1469 | |
1470 | static inline struct mm_slot *alloc_mm_slot(void) |
1471 | { |
1472 | if (!mm_slot_cache) /* initialization failed */ |
1473 | return NULL; |
1474 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); |
1475 | } |
1476 | |
1477 | static inline void free_mm_slot(struct mm_slot *mm_slot) |
1478 | { |
1479 | kmem_cache_free(mm_slot_cache, mm_slot); |
1480 | } |
1481 | |
1482 | static int __init mm_slots_hash_init(void) |
1483 | { |
1484 | mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head), |
1485 | GFP_KERNEL); |
1486 | if (!mm_slots_hash) |
1487 | return -ENOMEM; |
1488 | return 0; |
1489 | } |
1490 | |
1491 | #if 0 |
1492 | static void __init mm_slots_hash_free(void) |
1493 | { |
1494 | kfree(mm_slots_hash); |
1495 | mm_slots_hash = NULL; |
1496 | } |
1497 | #endif |
1498 | |
1499 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) |
1500 | { |
1501 | struct mm_slot *mm_slot; |
1502 | struct hlist_head *bucket; |
1503 | struct hlist_node *node; |
1504 | |
1505 | bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct)) |
1506 | % MM_SLOTS_HASH_HEADS]; |
1507 | hlist_for_each_entry(mm_slot, node, bucket, hash) { |
1508 | if (mm == mm_slot->mm) |
1509 | return mm_slot; |
1510 | } |
1511 | return NULL; |
1512 | } |
1513 | |
1514 | static void insert_to_mm_slots_hash(struct mm_struct *mm, |
1515 | struct mm_slot *mm_slot) |
1516 | { |
1517 | struct hlist_head *bucket; |
1518 | |
1519 | bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct)) |
1520 | % MM_SLOTS_HASH_HEADS]; |
1521 | mm_slot->mm = mm; |
1522 | hlist_add_head(&mm_slot->hash, bucket); |
1523 | } |
1524 | |
1525 | static inline int khugepaged_test_exit(struct mm_struct *mm) |
1526 | { |
1527 | return atomic_read(&mm->mm_users) == 0; |
1528 | } |
1529 | |
1530 | int __khugepaged_enter(struct mm_struct *mm) |
1531 | { |
1532 | struct mm_slot *mm_slot; |
1533 | int wakeup; |
1534 | |
1535 | mm_slot = alloc_mm_slot(); |
1536 | if (!mm_slot) |
1537 | return -ENOMEM; |
1538 | |
1539 | /* __khugepaged_exit() must not run from under us */ |
1540 | VM_BUG_ON(khugepaged_test_exit(mm)); |
1541 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { |
1542 | free_mm_slot(mm_slot); |
1543 | return 0; |
1544 | } |
1545 | |
1546 | spin_lock(&khugepaged_mm_lock); |
1547 | insert_to_mm_slots_hash(mm, mm_slot); |
1548 | /* |
1549 | * Insert just behind the scanning cursor, to let the area settle |
1550 | * down a little. |
1551 | */ |
1552 | wakeup = list_empty(&khugepaged_scan.mm_head); |
1553 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); |
1554 | spin_unlock(&khugepaged_mm_lock); |
1555 | |
1556 | atomic_inc(&mm->mm_count); |
1557 | if (wakeup) |
1558 | wake_up_interruptible(&khugepaged_wait); |
1559 | |
1560 | return 0; |
1561 | } |
1562 | |
1563 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma) |
1564 | { |
1565 | unsigned long hstart, hend; |
1566 | if (!vma->anon_vma) |
1567 | /* |
1568 | * Not yet faulted in so we will register later in the |
1569 | * page fault if needed. |
1570 | */ |
1571 | return 0; |
1572 | if (vma->vm_ops) |
1573 | /* khugepaged not yet working on file or special mappings */ |
1574 | return 0; |
1575 | /* |
1576 | * If is_pfn_mapping() is true is_learn_pfn_mapping() must be |
1577 | * true too, verify it here. |
1578 | */ |
1579 | VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP); |
1580 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
1581 | hend = vma->vm_end & HPAGE_PMD_MASK; |
1582 | if (hstart < hend) |
1583 | return khugepaged_enter(vma); |
1584 | return 0; |
1585 | } |
1586 | |
1587 | void __khugepaged_exit(struct mm_struct *mm) |
1588 | { |
1589 | struct mm_slot *mm_slot; |
1590 | int free = 0; |
1591 | |
1592 | spin_lock(&khugepaged_mm_lock); |
1593 | mm_slot = get_mm_slot(mm); |
1594 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { |
1595 | hlist_del(&mm_slot->hash); |
1596 | list_del(&mm_slot->mm_node); |
1597 | free = 1; |
1598 | } |
1599 | |
1600 | if (free) { |
1601 | spin_unlock(&khugepaged_mm_lock); |
1602 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); |
1603 | free_mm_slot(mm_slot); |
1604 | mmdrop(mm); |
1605 | } else if (mm_slot) { |
1606 | spin_unlock(&khugepaged_mm_lock); |
1607 | /* |
1608 | * This is required to serialize against |
1609 | * khugepaged_test_exit() (which is guaranteed to run |
1610 | * under mmap sem read mode). Stop here (after we |
1611 | * return all pagetables will be destroyed) until |
1612 | * khugepaged has finished working on the pagetables |
1613 | * under the mmap_sem. |
1614 | */ |
1615 | down_write(&mm->mmap_sem); |
1616 | up_write(&mm->mmap_sem); |
1617 | } else |
1618 | spin_unlock(&khugepaged_mm_lock); |
1619 | } |
1620 | |
1621 | static void release_pte_page(struct page *page) |
1622 | { |
1623 | /* 0 stands for page_is_file_cache(page) == false */ |
1624 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); |
1625 | unlock_page(page); |
1626 | putback_lru_page(page); |
1627 | } |
1628 | |
1629 | static void release_pte_pages(pte_t *pte, pte_t *_pte) |
1630 | { |
1631 | while (--_pte >= pte) { |
1632 | pte_t pteval = *_pte; |
1633 | if (!pte_none(pteval)) |
1634 | release_pte_page(pte_page(pteval)); |
1635 | } |
1636 | } |
1637 | |
1638 | static void release_all_pte_pages(pte_t *pte) |
1639 | { |
1640 | release_pte_pages(pte, pte + HPAGE_PMD_NR); |
1641 | } |
1642 | |
1643 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, |
1644 | unsigned long address, |
1645 | pte_t *pte) |
1646 | { |
1647 | struct page *page; |
1648 | pte_t *_pte; |
1649 | int referenced = 0, isolated = 0, none = 0; |
1650 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; |
1651 | _pte++, address += PAGE_SIZE) { |
1652 | pte_t pteval = *_pte; |
1653 | if (pte_none(pteval)) { |
1654 | if (++none <= khugepaged_max_ptes_none) |
1655 | continue; |
1656 | else { |
1657 | release_pte_pages(pte, _pte); |
1658 | goto out; |
1659 | } |
1660 | } |
1661 | if (!pte_present(pteval) || !pte_write(pteval)) { |
1662 | release_pte_pages(pte, _pte); |
1663 | goto out; |
1664 | } |
1665 | page = vm_normal_page(vma, address, pteval); |
1666 | if (unlikely(!page)) { |
1667 | release_pte_pages(pte, _pte); |
1668 | goto out; |
1669 | } |
1670 | VM_BUG_ON(PageCompound(page)); |
1671 | BUG_ON(!PageAnon(page)); |
1672 | VM_BUG_ON(!PageSwapBacked(page)); |
1673 | |
1674 | /* cannot use mapcount: can't collapse if there's a gup pin */ |
1675 | if (page_count(page) != 1) { |
1676 | release_pte_pages(pte, _pte); |
1677 | goto out; |
1678 | } |
1679 | /* |
1680 | * We can do it before isolate_lru_page because the |
1681 | * page can't be freed from under us. NOTE: PG_lock |
1682 | * is needed to serialize against split_huge_page |
1683 | * when invoked from the VM. |
1684 | */ |
1685 | if (!trylock_page(page)) { |
1686 | release_pte_pages(pte, _pte); |
1687 | goto out; |
1688 | } |
1689 | /* |
1690 | * Isolate the page to avoid collapsing an hugepage |
1691 | * currently in use by the VM. |
1692 | */ |
1693 | if (isolate_lru_page(page)) { |
1694 | unlock_page(page); |
1695 | release_pte_pages(pte, _pte); |
1696 | goto out; |
1697 | } |
1698 | /* 0 stands for page_is_file_cache(page) == false */ |
1699 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); |
1700 | VM_BUG_ON(!PageLocked(page)); |
1701 | VM_BUG_ON(PageLRU(page)); |
1702 | |
1703 | /* If there is no mapped pte young don't collapse the page */ |
1704 | if (pte_young(pteval) || PageReferenced(page) || |
1705 | mmu_notifier_test_young(vma->vm_mm, address)) |
1706 | referenced = 1; |
1707 | } |
1708 | if (unlikely(!referenced)) |
1709 | release_all_pte_pages(pte); |
1710 | else |
1711 | isolated = 1; |
1712 | out: |
1713 | return isolated; |
1714 | } |
1715 | |
1716 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, |
1717 | struct vm_area_struct *vma, |
1718 | unsigned long address, |
1719 | spinlock_t *ptl) |
1720 | { |
1721 | pte_t *_pte; |
1722 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { |
1723 | pte_t pteval = *_pte; |
1724 | struct page *src_page; |
1725 | |
1726 | if (pte_none(pteval)) { |
1727 | clear_user_highpage(page, address); |
1728 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); |
1729 | } else { |
1730 | src_page = pte_page(pteval); |
1731 | copy_user_highpage(page, src_page, address, vma); |
1732 | VM_BUG_ON(page_mapcount(src_page) != 1); |
1733 | VM_BUG_ON(page_count(src_page) != 2); |
1734 | release_pte_page(src_page); |
1735 | /* |
1736 | * ptl mostly unnecessary, but preempt has to |
1737 | * be disabled to update the per-cpu stats |
1738 | * inside page_remove_rmap(). |
1739 | */ |
1740 | spin_lock(ptl); |
1741 | /* |
1742 | * paravirt calls inside pte_clear here are |
1743 | * superfluous. |
1744 | */ |
1745 | pte_clear(vma->vm_mm, address, _pte); |
1746 | page_remove_rmap(src_page); |
1747 | spin_unlock(ptl); |
1748 | free_page_and_swap_cache(src_page); |
1749 | } |
1750 | |
1751 | address += PAGE_SIZE; |
1752 | page++; |
1753 | } |
1754 | } |
1755 | |
1756 | static void collapse_huge_page(struct mm_struct *mm, |
1757 | unsigned long address, |
1758 | struct page **hpage, |
1759 | struct vm_area_struct *vma, |
1760 | int node) |
1761 | { |
1762 | pgd_t *pgd; |
1763 | pud_t *pud; |
1764 | pmd_t *pmd, _pmd; |
1765 | pte_t *pte; |
1766 | pgtable_t pgtable; |
1767 | struct page *new_page; |
1768 | spinlock_t *ptl; |
1769 | int isolated; |
1770 | unsigned long hstart, hend; |
1771 | |
1772 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); |
1773 | #ifndef CONFIG_NUMA |
1774 | up_read(&mm->mmap_sem); |
1775 | VM_BUG_ON(!*hpage); |
1776 | new_page = *hpage; |
1777 | #else |
1778 | VM_BUG_ON(*hpage); |
1779 | /* |
1780 | * Allocate the page while the vma is still valid and under |
1781 | * the mmap_sem read mode so there is no memory allocation |
1782 | * later when we take the mmap_sem in write mode. This is more |
1783 | * friendly behavior (OTOH it may actually hide bugs) to |
1784 | * filesystems in userland with daemons allocating memory in |
1785 | * the userland I/O paths. Allocating memory with the |
1786 | * mmap_sem in read mode is good idea also to allow greater |
1787 | * scalability. |
1788 | */ |
1789 | new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address, |
1790 | node, __GFP_OTHER_NODE); |
1791 | |
1792 | /* |
1793 | * After allocating the hugepage, release the mmap_sem read lock in |
1794 | * preparation for taking it in write mode. |
1795 | */ |
1796 | up_read(&mm->mmap_sem); |
1797 | if (unlikely(!new_page)) { |
1798 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); |
1799 | *hpage = ERR_PTR(-ENOMEM); |
1800 | return; |
1801 | } |
1802 | #endif |
1803 | |
1804 | count_vm_event(THP_COLLAPSE_ALLOC); |
1805 | if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) { |
1806 | #ifdef CONFIG_NUMA |
1807 | put_page(new_page); |
1808 | #endif |
1809 | return; |
1810 | } |
1811 | |
1812 | /* |
1813 | * Prevent all access to pagetables with the exception of |
1814 | * gup_fast later hanlded by the ptep_clear_flush and the VM |
1815 | * handled by the anon_vma lock + PG_lock. |
1816 | */ |
1817 | down_write(&mm->mmap_sem); |
1818 | if (unlikely(khugepaged_test_exit(mm))) |
1819 | goto out; |
1820 | |
1821 | vma = find_vma(mm, address); |
1822 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
1823 | hend = vma->vm_end & HPAGE_PMD_MASK; |
1824 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) |
1825 | goto out; |
1826 | |
1827 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || |
1828 | (vma->vm_flags & VM_NOHUGEPAGE)) |
1829 | goto out; |
1830 | |
1831 | if (!vma->anon_vma || vma->vm_ops) |
1832 | goto out; |
1833 | if (is_vma_temporary_stack(vma)) |
1834 | goto out; |
1835 | /* |
1836 | * If is_pfn_mapping() is true is_learn_pfn_mapping() must be |
1837 | * true too, verify it here. |
1838 | */ |
1839 | VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP); |
1840 | |
1841 | pgd = pgd_offset(mm, address); |
1842 | if (!pgd_present(*pgd)) |
1843 | goto out; |
1844 | |
1845 | pud = pud_offset(pgd, address); |
1846 | if (!pud_present(*pud)) |
1847 | goto out; |
1848 | |
1849 | pmd = pmd_offset(pud, address); |
1850 | /* pmd can't go away or become huge under us */ |
1851 | if (!pmd_present(*pmd) || pmd_trans_huge(*pmd)) |
1852 | goto out; |
1853 | |
1854 | anon_vma_lock(vma->anon_vma); |
1855 | |
1856 | pte = pte_offset_map(pmd, address); |
1857 | ptl = pte_lockptr(mm, pmd); |
1858 | |
1859 | spin_lock(&mm->page_table_lock); /* probably unnecessary */ |
1860 | /* |
1861 | * After this gup_fast can't run anymore. This also removes |
1862 | * any huge TLB entry from the CPU so we won't allow |
1863 | * huge and small TLB entries for the same virtual address |
1864 | * to avoid the risk of CPU bugs in that area. |
1865 | */ |
1866 | _pmd = pmdp_clear_flush_notify(vma, address, pmd); |
1867 | spin_unlock(&mm->page_table_lock); |
1868 | |
1869 | spin_lock(ptl); |
1870 | isolated = __collapse_huge_page_isolate(vma, address, pte); |
1871 | spin_unlock(ptl); |
1872 | |
1873 | if (unlikely(!isolated)) { |
1874 | pte_unmap(pte); |
1875 | spin_lock(&mm->page_table_lock); |
1876 | BUG_ON(!pmd_none(*pmd)); |
1877 | set_pmd_at(mm, address, pmd, _pmd); |
1878 | spin_unlock(&mm->page_table_lock); |
1879 | anon_vma_unlock(vma->anon_vma); |
1880 | goto out; |
1881 | } |
1882 | |
1883 | /* |
1884 | * All pages are isolated and locked so anon_vma rmap |
1885 | * can't run anymore. |
1886 | */ |
1887 | anon_vma_unlock(vma->anon_vma); |
1888 | |
1889 | __collapse_huge_page_copy(pte, new_page, vma, address, ptl); |
1890 | pte_unmap(pte); |
1891 | __SetPageUptodate(new_page); |
1892 | pgtable = pmd_pgtable(_pmd); |
1893 | VM_BUG_ON(page_count(pgtable) != 1); |
1894 | VM_BUG_ON(page_mapcount(pgtable) != 0); |
1895 | |
1896 | _pmd = mk_pmd(new_page, vma->vm_page_prot); |
1897 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); |
1898 | _pmd = pmd_mkhuge(_pmd); |
1899 | |
1900 | /* |
1901 | * spin_lock() below is not the equivalent of smp_wmb(), so |
1902 | * this is needed to avoid the copy_huge_page writes to become |
1903 | * visible after the set_pmd_at() write. |
1904 | */ |
1905 | smp_wmb(); |
1906 | |
1907 | spin_lock(&mm->page_table_lock); |
1908 | BUG_ON(!pmd_none(*pmd)); |
1909 | page_add_new_anon_rmap(new_page, vma, address); |
1910 | set_pmd_at(mm, address, pmd, _pmd); |
1911 | update_mmu_cache(vma, address, entry); |
1912 | prepare_pmd_huge_pte(pgtable, mm); |
1913 | mm->nr_ptes--; |
1914 | spin_unlock(&mm->page_table_lock); |
1915 | |
1916 | #ifndef CONFIG_NUMA |
1917 | *hpage = NULL; |
1918 | #endif |
1919 | khugepaged_pages_collapsed++; |
1920 | out_up_write: |
1921 | up_write(&mm->mmap_sem); |
1922 | return; |
1923 | |
1924 | out: |
1925 | mem_cgroup_uncharge_page(new_page); |
1926 | #ifdef CONFIG_NUMA |
1927 | put_page(new_page); |
1928 | #endif |
1929 | goto out_up_write; |
1930 | } |
1931 | |
1932 | static int khugepaged_scan_pmd(struct mm_struct *mm, |
1933 | struct vm_area_struct *vma, |
1934 | unsigned long address, |
1935 | struct page **hpage) |
1936 | { |
1937 | pgd_t *pgd; |
1938 | pud_t *pud; |
1939 | pmd_t *pmd; |
1940 | pte_t *pte, *_pte; |
1941 | int ret = 0, referenced = 0, none = 0; |
1942 | struct page *page; |
1943 | unsigned long _address; |
1944 | spinlock_t *ptl; |
1945 | int node = -1; |
1946 | |
1947 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); |
1948 | |
1949 | pgd = pgd_offset(mm, address); |
1950 | if (!pgd_present(*pgd)) |
1951 | goto out; |
1952 | |
1953 | pud = pud_offset(pgd, address); |
1954 | if (!pud_present(*pud)) |
1955 | goto out; |
1956 | |
1957 | pmd = pmd_offset(pud, address); |
1958 | if (!pmd_present(*pmd) || pmd_trans_huge(*pmd)) |
1959 | goto out; |
1960 | |
1961 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
1962 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; |
1963 | _pte++, _address += PAGE_SIZE) { |
1964 | pte_t pteval = *_pte; |
1965 | if (pte_none(pteval)) { |
1966 | if (++none <= khugepaged_max_ptes_none) |
1967 | continue; |
1968 | else |
1969 | goto out_unmap; |
1970 | } |
1971 | if (!pte_present(pteval) || !pte_write(pteval)) |
1972 | goto out_unmap; |
1973 | page = vm_normal_page(vma, _address, pteval); |
1974 | if (unlikely(!page)) |
1975 | goto out_unmap; |
1976 | /* |
1977 | * Chose the node of the first page. This could |
1978 | * be more sophisticated and look at more pages, |
1979 | * but isn't for now. |
1980 | */ |
1981 | if (node == -1) |
1982 | node = page_to_nid(page); |
1983 | VM_BUG_ON(PageCompound(page)); |
1984 | if (!PageLRU(page) || PageLocked(page) || !PageAnon(page)) |
1985 | goto out_unmap; |
1986 | /* cannot use mapcount: can't collapse if there's a gup pin */ |
1987 | if (page_count(page) != 1) |
1988 | goto out_unmap; |
1989 | if (pte_young(pteval) || PageReferenced(page) || |
1990 | mmu_notifier_test_young(vma->vm_mm, address)) |
1991 | referenced = 1; |
1992 | } |
1993 | if (referenced) |
1994 | ret = 1; |
1995 | out_unmap: |
1996 | pte_unmap_unlock(pte, ptl); |
1997 | if (ret) |
1998 | /* collapse_huge_page will return with the mmap_sem released */ |
1999 | collapse_huge_page(mm, address, hpage, vma, node); |
2000 | out: |
2001 | return ret; |
2002 | } |
2003 | |
2004 | static void collect_mm_slot(struct mm_slot *mm_slot) |
2005 | { |
2006 | struct mm_struct *mm = mm_slot->mm; |
2007 | |
2008 | VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock)); |
2009 | |
2010 | if (khugepaged_test_exit(mm)) { |
2011 | /* free mm_slot */ |
2012 | hlist_del(&mm_slot->hash); |
2013 | list_del(&mm_slot->mm_node); |
2014 | |
2015 | /* |
2016 | * Not strictly needed because the mm exited already. |
2017 | * |
2018 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); |
2019 | */ |
2020 | |
2021 | /* khugepaged_mm_lock actually not necessary for the below */ |
2022 | free_mm_slot(mm_slot); |
2023 | mmdrop(mm); |
2024 | } |
2025 | } |
2026 | |
2027 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, |
2028 | struct page **hpage) |
2029 | { |
2030 | struct mm_slot *mm_slot; |
2031 | struct mm_struct *mm; |
2032 | struct vm_area_struct *vma; |
2033 | int progress = 0; |
2034 | |
2035 | VM_BUG_ON(!pages); |
2036 | VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock)); |
2037 | |
2038 | if (khugepaged_scan.mm_slot) |
2039 | mm_slot = khugepaged_scan.mm_slot; |
2040 | else { |
2041 | mm_slot = list_entry(khugepaged_scan.mm_head.next, |
2042 | struct mm_slot, mm_node); |
2043 | khugepaged_scan.address = 0; |
2044 | khugepaged_scan.mm_slot = mm_slot; |
2045 | } |
2046 | spin_unlock(&khugepaged_mm_lock); |
2047 | |
2048 | mm = mm_slot->mm; |
2049 | down_read(&mm->mmap_sem); |
2050 | if (unlikely(khugepaged_test_exit(mm))) |
2051 | vma = NULL; |
2052 | else |
2053 | vma = find_vma(mm, khugepaged_scan.address); |
2054 | |
2055 | progress++; |
2056 | for (; vma; vma = vma->vm_next) { |
2057 | unsigned long hstart, hend; |
2058 | |
2059 | cond_resched(); |
2060 | if (unlikely(khugepaged_test_exit(mm))) { |
2061 | progress++; |
2062 | break; |
2063 | } |
2064 | |
2065 | if ((!(vma->vm_flags & VM_HUGEPAGE) && |
2066 | !khugepaged_always()) || |
2067 | (vma->vm_flags & VM_NOHUGEPAGE)) { |
2068 | skip: |
2069 | progress++; |
2070 | continue; |
2071 | } |
2072 | if (!vma->anon_vma || vma->vm_ops) |
2073 | goto skip; |
2074 | if (is_vma_temporary_stack(vma)) |
2075 | goto skip; |
2076 | /* |
2077 | * If is_pfn_mapping() is true is_learn_pfn_mapping() |
2078 | * must be true too, verify it here. |
2079 | */ |
2080 | VM_BUG_ON(is_linear_pfn_mapping(vma) || |
2081 | vma->vm_flags & VM_NO_THP); |
2082 | |
2083 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
2084 | hend = vma->vm_end & HPAGE_PMD_MASK; |
2085 | if (hstart >= hend) |
2086 | goto skip; |
2087 | if (khugepaged_scan.address > hend) |
2088 | goto skip; |
2089 | if (khugepaged_scan.address < hstart) |
2090 | khugepaged_scan.address = hstart; |
2091 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); |
2092 | |
2093 | while (khugepaged_scan.address < hend) { |
2094 | int ret; |
2095 | cond_resched(); |
2096 | if (unlikely(khugepaged_test_exit(mm))) |
2097 | goto breakouterloop; |
2098 | |
2099 | VM_BUG_ON(khugepaged_scan.address < hstart || |
2100 | khugepaged_scan.address + HPAGE_PMD_SIZE > |
2101 | hend); |
2102 | ret = khugepaged_scan_pmd(mm, vma, |
2103 | khugepaged_scan.address, |
2104 | hpage); |
2105 | /* move to next address */ |
2106 | khugepaged_scan.address += HPAGE_PMD_SIZE; |
2107 | progress += HPAGE_PMD_NR; |
2108 | if (ret) |
2109 | /* we released mmap_sem so break loop */ |
2110 | goto breakouterloop_mmap_sem; |
2111 | if (progress >= pages) |
2112 | goto breakouterloop; |
2113 | } |
2114 | } |
2115 | breakouterloop: |
2116 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ |
2117 | breakouterloop_mmap_sem: |
2118 | |
2119 | spin_lock(&khugepaged_mm_lock); |
2120 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); |
2121 | /* |
2122 | * Release the current mm_slot if this mm is about to die, or |
2123 | * if we scanned all vmas of this mm. |
2124 | */ |
2125 | if (khugepaged_test_exit(mm) || !vma) { |
2126 | /* |
2127 | * Make sure that if mm_users is reaching zero while |
2128 | * khugepaged runs here, khugepaged_exit will find |
2129 | * mm_slot not pointing to the exiting mm. |
2130 | */ |
2131 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { |
2132 | khugepaged_scan.mm_slot = list_entry( |
2133 | mm_slot->mm_node.next, |
2134 | struct mm_slot, mm_node); |
2135 | khugepaged_scan.address = 0; |
2136 | } else { |
2137 | khugepaged_scan.mm_slot = NULL; |
2138 | khugepaged_full_scans++; |
2139 | } |
2140 | |
2141 | collect_mm_slot(mm_slot); |
2142 | } |
2143 | |
2144 | return progress; |
2145 | } |
2146 | |
2147 | static int khugepaged_has_work(void) |
2148 | { |
2149 | return !list_empty(&khugepaged_scan.mm_head) && |
2150 | khugepaged_enabled(); |
2151 | } |
2152 | |
2153 | static int khugepaged_wait_event(void) |
2154 | { |
2155 | return !list_empty(&khugepaged_scan.mm_head) || |
2156 | !khugepaged_enabled(); |
2157 | } |
2158 | |
2159 | static void khugepaged_do_scan(struct page **hpage) |
2160 | { |
2161 | unsigned int progress = 0, pass_through_head = 0; |
2162 | unsigned int pages = khugepaged_pages_to_scan; |
2163 | |
2164 | barrier(); /* write khugepaged_pages_to_scan to local stack */ |
2165 | |
2166 | while (progress < pages) { |
2167 | cond_resched(); |
2168 | |
2169 | #ifndef CONFIG_NUMA |
2170 | if (!*hpage) { |
2171 | *hpage = alloc_hugepage(khugepaged_defrag()); |
2172 | if (unlikely(!*hpage)) { |
2173 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); |
2174 | break; |
2175 | } |
2176 | count_vm_event(THP_COLLAPSE_ALLOC); |
2177 | } |
2178 | #else |
2179 | if (IS_ERR(*hpage)) |
2180 | break; |
2181 | #endif |
2182 | |
2183 | if (unlikely(kthread_should_stop() || freezing(current))) |
2184 | break; |
2185 | |
2186 | spin_lock(&khugepaged_mm_lock); |
2187 | if (!khugepaged_scan.mm_slot) |
2188 | pass_through_head++; |
2189 | if (khugepaged_has_work() && |
2190 | pass_through_head < 2) |
2191 | progress += khugepaged_scan_mm_slot(pages - progress, |
2192 | hpage); |
2193 | else |
2194 | progress = pages; |
2195 | spin_unlock(&khugepaged_mm_lock); |
2196 | } |
2197 | } |
2198 | |
2199 | static void khugepaged_alloc_sleep(void) |
2200 | { |
2201 | DEFINE_WAIT(wait); |
2202 | add_wait_queue(&khugepaged_wait, &wait); |
2203 | schedule_timeout_interruptible( |
2204 | msecs_to_jiffies( |
2205 | khugepaged_alloc_sleep_millisecs)); |
2206 | remove_wait_queue(&khugepaged_wait, &wait); |
2207 | } |
2208 | |
2209 | #ifndef CONFIG_NUMA |
2210 | static struct page *khugepaged_alloc_hugepage(void) |
2211 | { |
2212 | struct page *hpage; |
2213 | |
2214 | do { |
2215 | hpage = alloc_hugepage(khugepaged_defrag()); |
2216 | if (!hpage) { |
2217 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); |
2218 | khugepaged_alloc_sleep(); |
2219 | } else |
2220 | count_vm_event(THP_COLLAPSE_ALLOC); |
2221 | } while (unlikely(!hpage) && |
2222 | likely(khugepaged_enabled())); |
2223 | return hpage; |
2224 | } |
2225 | #endif |
2226 | |
2227 | static void khugepaged_loop(void) |
2228 | { |
2229 | struct page *hpage; |
2230 | |
2231 | #ifdef CONFIG_NUMA |
2232 | hpage = NULL; |
2233 | #endif |
2234 | while (likely(khugepaged_enabled())) { |
2235 | #ifndef CONFIG_NUMA |
2236 | hpage = khugepaged_alloc_hugepage(); |
2237 | if (unlikely(!hpage)) |
2238 | break; |
2239 | #else |
2240 | if (IS_ERR(hpage)) { |
2241 | khugepaged_alloc_sleep(); |
2242 | hpage = NULL; |
2243 | } |
2244 | #endif |
2245 | |
2246 | khugepaged_do_scan(&hpage); |
2247 | #ifndef CONFIG_NUMA |
2248 | if (hpage) |
2249 | put_page(hpage); |
2250 | #endif |
2251 | try_to_freeze(); |
2252 | if (unlikely(kthread_should_stop())) |
2253 | break; |
2254 | if (khugepaged_has_work()) { |
2255 | DEFINE_WAIT(wait); |
2256 | if (!khugepaged_scan_sleep_millisecs) |
2257 | continue; |
2258 | add_wait_queue(&khugepaged_wait, &wait); |
2259 | schedule_timeout_interruptible( |
2260 | msecs_to_jiffies( |
2261 | khugepaged_scan_sleep_millisecs)); |
2262 | remove_wait_queue(&khugepaged_wait, &wait); |
2263 | } else if (khugepaged_enabled()) |
2264 | wait_event_freezable(khugepaged_wait, |
2265 | khugepaged_wait_event()); |
2266 | } |
2267 | } |
2268 | |
2269 | static int khugepaged(void *none) |
2270 | { |
2271 | struct mm_slot *mm_slot; |
2272 | |
2273 | set_freezable(); |
2274 | set_user_nice(current, 19); |
2275 | |
2276 | /* serialize with start_khugepaged() */ |
2277 | mutex_lock(&khugepaged_mutex); |
2278 | |
2279 | for (;;) { |
2280 | mutex_unlock(&khugepaged_mutex); |
2281 | VM_BUG_ON(khugepaged_thread != current); |
2282 | khugepaged_loop(); |
2283 | VM_BUG_ON(khugepaged_thread != current); |
2284 | |
2285 | mutex_lock(&khugepaged_mutex); |
2286 | if (!khugepaged_enabled()) |
2287 | break; |
2288 | if (unlikely(kthread_should_stop())) |
2289 | break; |
2290 | } |
2291 | |
2292 | spin_lock(&khugepaged_mm_lock); |
2293 | mm_slot = khugepaged_scan.mm_slot; |
2294 | khugepaged_scan.mm_slot = NULL; |
2295 | if (mm_slot) |
2296 | collect_mm_slot(mm_slot); |
2297 | spin_unlock(&khugepaged_mm_lock); |
2298 | |
2299 | khugepaged_thread = NULL; |
2300 | mutex_unlock(&khugepaged_mutex); |
2301 | |
2302 | return 0; |
2303 | } |
2304 | |
2305 | void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd) |
2306 | { |
2307 | struct page *page; |
2308 | |
2309 | spin_lock(&mm->page_table_lock); |
2310 | if (unlikely(!pmd_trans_huge(*pmd))) { |
2311 | spin_unlock(&mm->page_table_lock); |
2312 | return; |
2313 | } |
2314 | page = pmd_page(*pmd); |
2315 | VM_BUG_ON(!page_count(page)); |
2316 | get_page(page); |
2317 | spin_unlock(&mm->page_table_lock); |
2318 | |
2319 | split_huge_page(page); |
2320 | |
2321 | put_page(page); |
2322 | BUG_ON(pmd_trans_huge(*pmd)); |
2323 | } |
2324 | |
2325 | static void split_huge_page_address(struct mm_struct *mm, |
2326 | unsigned long address) |
2327 | { |
2328 | pgd_t *pgd; |
2329 | pud_t *pud; |
2330 | pmd_t *pmd; |
2331 | |
2332 | VM_BUG_ON(!(address & ~HPAGE_PMD_MASK)); |
2333 | |
2334 | pgd = pgd_offset(mm, address); |
2335 | if (!pgd_present(*pgd)) |
2336 | return; |
2337 | |
2338 | pud = pud_offset(pgd, address); |
2339 | if (!pud_present(*pud)) |
2340 | return; |
2341 | |
2342 | pmd = pmd_offset(pud, address); |
2343 | if (!pmd_present(*pmd)) |
2344 | return; |
2345 | /* |
2346 | * Caller holds the mmap_sem write mode, so a huge pmd cannot |
2347 | * materialize from under us. |
2348 | */ |
2349 | split_huge_page_pmd(mm, pmd); |
2350 | } |
2351 | |
2352 | void __vma_adjust_trans_huge(struct vm_area_struct *vma, |
2353 | unsigned long start, |
2354 | unsigned long end, |
2355 | long adjust_next) |
2356 | { |
2357 | /* |
2358 | * If the new start address isn't hpage aligned and it could |
2359 | * previously contain an hugepage: check if we need to split |
2360 | * an huge pmd. |
2361 | */ |
2362 | if (start & ~HPAGE_PMD_MASK && |
2363 | (start & HPAGE_PMD_MASK) >= vma->vm_start && |
2364 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) |
2365 | split_huge_page_address(vma->vm_mm, start); |
2366 | |
2367 | /* |
2368 | * If the new end address isn't hpage aligned and it could |
2369 | * previously contain an hugepage: check if we need to split |
2370 | * an huge pmd. |
2371 | */ |
2372 | if (end & ~HPAGE_PMD_MASK && |
2373 | (end & HPAGE_PMD_MASK) >= vma->vm_start && |
2374 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) |
2375 | split_huge_page_address(vma->vm_mm, end); |
2376 | |
2377 | /* |
2378 | * If we're also updating the vma->vm_next->vm_start, if the new |
2379 | * vm_next->vm_start isn't page aligned and it could previously |
2380 | * contain an hugepage: check if we need to split an huge pmd. |
2381 | */ |
2382 | if (adjust_next > 0) { |
2383 | struct vm_area_struct *next = vma->vm_next; |
2384 | unsigned long nstart = next->vm_start; |
2385 | nstart += adjust_next << PAGE_SHIFT; |
2386 | if (nstart & ~HPAGE_PMD_MASK && |
2387 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && |
2388 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) |
2389 | split_huge_page_address(next->vm_mm, nstart); |
2390 | } |
2391 | } |
2392 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
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jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9