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