]>
Commit | Line | Data |
---|---|---|
b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
b46e756f KS |
2 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
3 | ||
4 | #include <linux/mm.h> | |
5 | #include <linux/sched.h> | |
6e84f315 | 6 | #include <linux/sched/mm.h> |
f7ccbae4 | 7 | #include <linux/sched/coredump.h> |
b46e756f KS |
8 | #include <linux/mmu_notifier.h> |
9 | #include <linux/rmap.h> | |
10 | #include <linux/swap.h> | |
11 | #include <linux/mm_inline.h> | |
12 | #include <linux/kthread.h> | |
13 | #include <linux/khugepaged.h> | |
14 | #include <linux/freezer.h> | |
15 | #include <linux/mman.h> | |
16 | #include <linux/hashtable.h> | |
17 | #include <linux/userfaultfd_k.h> | |
18 | #include <linux/page_idle.h> | |
19 | #include <linux/swapops.h> | |
f3f0e1d2 | 20 | #include <linux/shmem_fs.h> |
b46e756f KS |
21 | |
22 | #include <asm/tlb.h> | |
23 | #include <asm/pgalloc.h> | |
24 | #include "internal.h" | |
25 | ||
26 | enum scan_result { | |
27 | SCAN_FAIL, | |
28 | SCAN_SUCCEED, | |
29 | SCAN_PMD_NULL, | |
30 | SCAN_EXCEED_NONE_PTE, | |
71a2c112 KS |
31 | SCAN_EXCEED_SWAP_PTE, |
32 | SCAN_EXCEED_SHARED_PTE, | |
b46e756f | 33 | SCAN_PTE_NON_PRESENT, |
e1e267c7 | 34 | SCAN_PTE_UFFD_WP, |
b46e756f | 35 | SCAN_PAGE_RO, |
0db501f7 | 36 | SCAN_LACK_REFERENCED_PAGE, |
b46e756f KS |
37 | SCAN_PAGE_NULL, |
38 | SCAN_SCAN_ABORT, | |
39 | SCAN_PAGE_COUNT, | |
40 | SCAN_PAGE_LRU, | |
41 | SCAN_PAGE_LOCK, | |
42 | SCAN_PAGE_ANON, | |
43 | SCAN_PAGE_COMPOUND, | |
44 | SCAN_ANY_PROCESS, | |
45 | SCAN_VMA_NULL, | |
46 | SCAN_VMA_CHECK, | |
47 | SCAN_ADDRESS_RANGE, | |
48 | SCAN_SWAP_CACHE_PAGE, | |
49 | SCAN_DEL_PAGE_LRU, | |
50 | SCAN_ALLOC_HUGE_PAGE_FAIL, | |
51 | SCAN_CGROUP_CHARGE_FAIL, | |
f3f0e1d2 | 52 | SCAN_TRUNCATED, |
99cb0dbd | 53 | SCAN_PAGE_HAS_PRIVATE, |
b46e756f KS |
54 | }; |
55 | ||
56 | #define CREATE_TRACE_POINTS | |
57 | #include <trace/events/huge_memory.h> | |
58 | ||
59 | /* default scan 8*512 pte (or vmas) every 30 second */ | |
60 | static unsigned int khugepaged_pages_to_scan __read_mostly; | |
61 | static unsigned int khugepaged_pages_collapsed; | |
62 | static unsigned int khugepaged_full_scans; | |
63 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
64 | /* during fragmentation poll the hugepage allocator once every minute */ | |
65 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
66 | static unsigned long khugepaged_sleep_expire; | |
67 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
68 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
69 | /* | |
70 | * default collapse hugepages if there is at least one pte mapped like | |
71 | * it would have happened if the vma was large enough during page | |
72 | * fault. | |
73 | */ | |
74 | static unsigned int khugepaged_max_ptes_none __read_mostly; | |
75 | static unsigned int khugepaged_max_ptes_swap __read_mostly; | |
71a2c112 | 76 | static unsigned int khugepaged_max_ptes_shared __read_mostly; |
b46e756f KS |
77 | |
78 | #define MM_SLOTS_HASH_BITS 10 | |
79 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
80 | ||
81 | static struct kmem_cache *mm_slot_cache __read_mostly; | |
82 | ||
27e1f827 SL |
83 | #define MAX_PTE_MAPPED_THP 8 |
84 | ||
b46e756f KS |
85 | /** |
86 | * struct mm_slot - hash lookup from mm to mm_slot | |
87 | * @hash: hash collision list | |
88 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
89 | * @mm: the mm that this information is valid for | |
90 | */ | |
91 | struct mm_slot { | |
92 | struct hlist_node hash; | |
93 | struct list_head mm_node; | |
94 | struct mm_struct *mm; | |
27e1f827 SL |
95 | |
96 | /* pte-mapped THP in this mm */ | |
97 | int nr_pte_mapped_thp; | |
98 | unsigned long pte_mapped_thp[MAX_PTE_MAPPED_THP]; | |
b46e756f KS |
99 | }; |
100 | ||
101 | /** | |
102 | * struct khugepaged_scan - cursor for scanning | |
103 | * @mm_head: the head of the mm list to scan | |
104 | * @mm_slot: the current mm_slot we are scanning | |
105 | * @address: the next address inside that to be scanned | |
106 | * | |
107 | * There is only the one khugepaged_scan instance of this cursor structure. | |
108 | */ | |
109 | struct khugepaged_scan { | |
110 | struct list_head mm_head; | |
111 | struct mm_slot *mm_slot; | |
112 | unsigned long address; | |
113 | }; | |
114 | ||
115 | static struct khugepaged_scan khugepaged_scan = { | |
116 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), | |
117 | }; | |
118 | ||
e1465d12 | 119 | #ifdef CONFIG_SYSFS |
b46e756f KS |
120 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, |
121 | struct kobj_attribute *attr, | |
122 | char *buf) | |
123 | { | |
124 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
125 | } | |
126 | ||
127 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
128 | struct kobj_attribute *attr, | |
129 | const char *buf, size_t count) | |
130 | { | |
131 | unsigned long msecs; | |
132 | int err; | |
133 | ||
134 | err = kstrtoul(buf, 10, &msecs); | |
135 | if (err || msecs > UINT_MAX) | |
136 | return -EINVAL; | |
137 | ||
138 | khugepaged_scan_sleep_millisecs = msecs; | |
139 | khugepaged_sleep_expire = 0; | |
140 | wake_up_interruptible(&khugepaged_wait); | |
141 | ||
142 | return count; | |
143 | } | |
144 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
145 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
146 | scan_sleep_millisecs_store); | |
147 | ||
148 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
149 | struct kobj_attribute *attr, | |
150 | char *buf) | |
151 | { | |
152 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
153 | } | |
154 | ||
155 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
156 | struct kobj_attribute *attr, | |
157 | const char *buf, size_t count) | |
158 | { | |
159 | unsigned long msecs; | |
160 | int err; | |
161 | ||
162 | err = kstrtoul(buf, 10, &msecs); | |
163 | if (err || msecs > UINT_MAX) | |
164 | return -EINVAL; | |
165 | ||
166 | khugepaged_alloc_sleep_millisecs = msecs; | |
167 | khugepaged_sleep_expire = 0; | |
168 | wake_up_interruptible(&khugepaged_wait); | |
169 | ||
170 | return count; | |
171 | } | |
172 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
173 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
174 | alloc_sleep_millisecs_store); | |
175 | ||
176 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
177 | struct kobj_attribute *attr, | |
178 | char *buf) | |
179 | { | |
180 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
181 | } | |
182 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
183 | struct kobj_attribute *attr, | |
184 | const char *buf, size_t count) | |
185 | { | |
186 | int err; | |
187 | unsigned long pages; | |
188 | ||
189 | err = kstrtoul(buf, 10, &pages); | |
190 | if (err || !pages || pages > UINT_MAX) | |
191 | return -EINVAL; | |
192 | ||
193 | khugepaged_pages_to_scan = pages; | |
194 | ||
195 | return count; | |
196 | } | |
197 | static struct kobj_attribute pages_to_scan_attr = | |
198 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
199 | pages_to_scan_store); | |
200 | ||
201 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
202 | struct kobj_attribute *attr, | |
203 | char *buf) | |
204 | { | |
205 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
206 | } | |
207 | static struct kobj_attribute pages_collapsed_attr = | |
208 | __ATTR_RO(pages_collapsed); | |
209 | ||
210 | static ssize_t full_scans_show(struct kobject *kobj, | |
211 | struct kobj_attribute *attr, | |
212 | char *buf) | |
213 | { | |
214 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
215 | } | |
216 | static struct kobj_attribute full_scans_attr = | |
217 | __ATTR_RO(full_scans); | |
218 | ||
219 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
220 | struct kobj_attribute *attr, char *buf) | |
221 | { | |
222 | return single_hugepage_flag_show(kobj, attr, buf, | |
223 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
224 | } | |
225 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
226 | struct kobj_attribute *attr, | |
227 | const char *buf, size_t count) | |
228 | { | |
229 | return single_hugepage_flag_store(kobj, attr, buf, count, | |
230 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
231 | } | |
232 | static struct kobj_attribute khugepaged_defrag_attr = | |
233 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
234 | khugepaged_defrag_store); | |
235 | ||
236 | /* | |
237 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
238 | * any unmapped ptes in turn potentially increasing the memory | |
239 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
240 | * reduce the available free memory in the system as it | |
241 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
242 | * free memory in the system during the khugepaged scan. | |
243 | */ | |
244 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
245 | struct kobj_attribute *attr, | |
246 | char *buf) | |
247 | { | |
248 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
249 | } | |
250 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
251 | struct kobj_attribute *attr, | |
252 | const char *buf, size_t count) | |
253 | { | |
254 | int err; | |
255 | unsigned long max_ptes_none; | |
256 | ||
257 | err = kstrtoul(buf, 10, &max_ptes_none); | |
258 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
259 | return -EINVAL; | |
260 | ||
261 | khugepaged_max_ptes_none = max_ptes_none; | |
262 | ||
263 | return count; | |
264 | } | |
265 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
266 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
267 | khugepaged_max_ptes_none_store); | |
268 | ||
269 | static ssize_t khugepaged_max_ptes_swap_show(struct kobject *kobj, | |
270 | struct kobj_attribute *attr, | |
271 | char *buf) | |
272 | { | |
273 | return sprintf(buf, "%u\n", khugepaged_max_ptes_swap); | |
274 | } | |
275 | ||
276 | static ssize_t khugepaged_max_ptes_swap_store(struct kobject *kobj, | |
277 | struct kobj_attribute *attr, | |
278 | const char *buf, size_t count) | |
279 | { | |
280 | int err; | |
281 | unsigned long max_ptes_swap; | |
282 | ||
283 | err = kstrtoul(buf, 10, &max_ptes_swap); | |
284 | if (err || max_ptes_swap > HPAGE_PMD_NR-1) | |
285 | return -EINVAL; | |
286 | ||
287 | khugepaged_max_ptes_swap = max_ptes_swap; | |
288 | ||
289 | return count; | |
290 | } | |
291 | ||
292 | static struct kobj_attribute khugepaged_max_ptes_swap_attr = | |
293 | __ATTR(max_ptes_swap, 0644, khugepaged_max_ptes_swap_show, | |
294 | khugepaged_max_ptes_swap_store); | |
295 | ||
71a2c112 KS |
296 | static ssize_t khugepaged_max_ptes_shared_show(struct kobject *kobj, |
297 | struct kobj_attribute *attr, | |
298 | char *buf) | |
299 | { | |
300 | return sprintf(buf, "%u\n", khugepaged_max_ptes_shared); | |
301 | } | |
302 | ||
303 | static ssize_t khugepaged_max_ptes_shared_store(struct kobject *kobj, | |
304 | struct kobj_attribute *attr, | |
305 | const char *buf, size_t count) | |
306 | { | |
307 | int err; | |
308 | unsigned long max_ptes_shared; | |
309 | ||
310 | err = kstrtoul(buf, 10, &max_ptes_shared); | |
311 | if (err || max_ptes_shared > HPAGE_PMD_NR-1) | |
312 | return -EINVAL; | |
313 | ||
314 | khugepaged_max_ptes_shared = max_ptes_shared; | |
315 | ||
316 | return count; | |
317 | } | |
318 | ||
319 | static struct kobj_attribute khugepaged_max_ptes_shared_attr = | |
320 | __ATTR(max_ptes_shared, 0644, khugepaged_max_ptes_shared_show, | |
321 | khugepaged_max_ptes_shared_store); | |
322 | ||
b46e756f KS |
323 | static struct attribute *khugepaged_attr[] = { |
324 | &khugepaged_defrag_attr.attr, | |
325 | &khugepaged_max_ptes_none_attr.attr, | |
71a2c112 KS |
326 | &khugepaged_max_ptes_swap_attr.attr, |
327 | &khugepaged_max_ptes_shared_attr.attr, | |
b46e756f KS |
328 | &pages_to_scan_attr.attr, |
329 | &pages_collapsed_attr.attr, | |
330 | &full_scans_attr.attr, | |
331 | &scan_sleep_millisecs_attr.attr, | |
332 | &alloc_sleep_millisecs_attr.attr, | |
b46e756f KS |
333 | NULL, |
334 | }; | |
335 | ||
336 | struct attribute_group khugepaged_attr_group = { | |
337 | .attrs = khugepaged_attr, | |
338 | .name = "khugepaged", | |
339 | }; | |
e1465d12 | 340 | #endif /* CONFIG_SYSFS */ |
b46e756f | 341 | |
b46e756f KS |
342 | int hugepage_madvise(struct vm_area_struct *vma, |
343 | unsigned long *vm_flags, int advice) | |
344 | { | |
345 | switch (advice) { | |
346 | case MADV_HUGEPAGE: | |
347 | #ifdef CONFIG_S390 | |
348 | /* | |
349 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
350 | * can't handle this properly after s390_enable_sie, so we simply | |
351 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
352 | */ | |
353 | if (mm_has_pgste(vma->vm_mm)) | |
354 | return 0; | |
355 | #endif | |
356 | *vm_flags &= ~VM_NOHUGEPAGE; | |
357 | *vm_flags |= VM_HUGEPAGE; | |
358 | /* | |
359 | * If the vma become good for khugepaged to scan, | |
360 | * register it here without waiting a page fault that | |
361 | * may not happen any time soon. | |
362 | */ | |
363 | if (!(*vm_flags & VM_NO_KHUGEPAGED) && | |
364 | khugepaged_enter_vma_merge(vma, *vm_flags)) | |
365 | return -ENOMEM; | |
366 | break; | |
367 | case MADV_NOHUGEPAGE: | |
368 | *vm_flags &= ~VM_HUGEPAGE; | |
369 | *vm_flags |= VM_NOHUGEPAGE; | |
370 | /* | |
371 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
372 | * this vma even if we leave the mm registered in khugepaged if | |
373 | * it got registered before VM_NOHUGEPAGE was set. | |
374 | */ | |
375 | break; | |
376 | } | |
377 | ||
378 | return 0; | |
379 | } | |
380 | ||
381 | int __init khugepaged_init(void) | |
382 | { | |
383 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
384 | sizeof(struct mm_slot), | |
385 | __alignof__(struct mm_slot), 0, NULL); | |
386 | if (!mm_slot_cache) | |
387 | return -ENOMEM; | |
388 | ||
389 | khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; | |
390 | khugepaged_max_ptes_none = HPAGE_PMD_NR - 1; | |
391 | khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8; | |
71a2c112 | 392 | khugepaged_max_ptes_shared = HPAGE_PMD_NR / 2; |
b46e756f KS |
393 | |
394 | return 0; | |
395 | } | |
396 | ||
397 | void __init khugepaged_destroy(void) | |
398 | { | |
399 | kmem_cache_destroy(mm_slot_cache); | |
400 | } | |
401 | ||
402 | static inline struct mm_slot *alloc_mm_slot(void) | |
403 | { | |
404 | if (!mm_slot_cache) /* initialization failed */ | |
405 | return NULL; | |
406 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
407 | } | |
408 | ||
409 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
410 | { | |
411 | kmem_cache_free(mm_slot_cache, mm_slot); | |
412 | } | |
413 | ||
414 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
415 | { | |
416 | struct mm_slot *mm_slot; | |
417 | ||
418 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) | |
419 | if (mm == mm_slot->mm) | |
420 | return mm_slot; | |
421 | ||
422 | return NULL; | |
423 | } | |
424 | ||
425 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
426 | struct mm_slot *mm_slot) | |
427 | { | |
428 | mm_slot->mm = mm; | |
429 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); | |
430 | } | |
431 | ||
432 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
433 | { | |
434 | return atomic_read(&mm->mm_users) == 0; | |
435 | } | |
436 | ||
50f8b92f SL |
437 | static bool hugepage_vma_check(struct vm_area_struct *vma, |
438 | unsigned long vm_flags) | |
c2231020 | 439 | { |
50f8b92f SL |
440 | if ((!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || |
441 | (vm_flags & VM_NOHUGEPAGE) || | |
c2231020 YS |
442 | test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) |
443 | return false; | |
99cb0dbd SL |
444 | |
445 | if (shmem_file(vma->vm_file) || | |
446 | (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && | |
447 | vma->vm_file && | |
448 | (vm_flags & VM_DENYWRITE))) { | |
c2231020 YS |
449 | return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, |
450 | HPAGE_PMD_NR); | |
451 | } | |
452 | if (!vma->anon_vma || vma->vm_ops) | |
453 | return false; | |
222100ee | 454 | if (vma_is_temporary_stack(vma)) |
c2231020 | 455 | return false; |
50f8b92f | 456 | return !(vm_flags & VM_NO_KHUGEPAGED); |
c2231020 YS |
457 | } |
458 | ||
b46e756f KS |
459 | int __khugepaged_enter(struct mm_struct *mm) |
460 | { | |
461 | struct mm_slot *mm_slot; | |
462 | int wakeup; | |
463 | ||
464 | mm_slot = alloc_mm_slot(); | |
465 | if (!mm_slot) | |
466 | return -ENOMEM; | |
467 | ||
468 | /* __khugepaged_exit() must not run from under us */ | |
469 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); | |
470 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { | |
471 | free_mm_slot(mm_slot); | |
472 | return 0; | |
473 | } | |
474 | ||
475 | spin_lock(&khugepaged_mm_lock); | |
476 | insert_to_mm_slots_hash(mm, mm_slot); | |
477 | /* | |
478 | * Insert just behind the scanning cursor, to let the area settle | |
479 | * down a little. | |
480 | */ | |
481 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
482 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
483 | spin_unlock(&khugepaged_mm_lock); | |
484 | ||
f1f10076 | 485 | mmgrab(mm); |
b46e756f KS |
486 | if (wakeup) |
487 | wake_up_interruptible(&khugepaged_wait); | |
488 | ||
489 | return 0; | |
490 | } | |
491 | ||
492 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, | |
493 | unsigned long vm_flags) | |
494 | { | |
495 | unsigned long hstart, hend; | |
c2231020 YS |
496 | |
497 | /* | |
99cb0dbd SL |
498 | * khugepaged only supports read-only files for non-shmem files. |
499 | * khugepaged does not yet work on special mappings. And | |
500 | * file-private shmem THP is not supported. | |
c2231020 | 501 | */ |
50f8b92f | 502 | if (!hugepage_vma_check(vma, vm_flags)) |
b46e756f | 503 | return 0; |
c2231020 | 504 | |
b46e756f KS |
505 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
506 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
507 | if (hstart < hend) | |
508 | return khugepaged_enter(vma, vm_flags); | |
509 | return 0; | |
510 | } | |
511 | ||
512 | void __khugepaged_exit(struct mm_struct *mm) | |
513 | { | |
514 | struct mm_slot *mm_slot; | |
515 | int free = 0; | |
516 | ||
517 | spin_lock(&khugepaged_mm_lock); | |
518 | mm_slot = get_mm_slot(mm); | |
519 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
520 | hash_del(&mm_slot->hash); | |
521 | list_del(&mm_slot->mm_node); | |
522 | free = 1; | |
523 | } | |
524 | spin_unlock(&khugepaged_mm_lock); | |
525 | ||
526 | if (free) { | |
527 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
528 | free_mm_slot(mm_slot); | |
529 | mmdrop(mm); | |
530 | } else if (mm_slot) { | |
531 | /* | |
532 | * This is required to serialize against | |
533 | * khugepaged_test_exit() (which is guaranteed to run | |
534 | * under mmap sem read mode). Stop here (after we | |
535 | * return all pagetables will be destroyed) until | |
536 | * khugepaged has finished working on the pagetables | |
537 | * under the mmap_sem. | |
538 | */ | |
539 | down_write(&mm->mmap_sem); | |
540 | up_write(&mm->mmap_sem); | |
541 | } | |
542 | } | |
543 | ||
544 | static void release_pte_page(struct page *page) | |
545 | { | |
5503fbf2 KS |
546 | mod_node_page_state(page_pgdat(page), |
547 | NR_ISOLATED_ANON + page_is_file_lru(page), | |
548 | -compound_nr(page)); | |
b46e756f KS |
549 | unlock_page(page); |
550 | putback_lru_page(page); | |
551 | } | |
552 | ||
5503fbf2 KS |
553 | static void release_pte_pages(pte_t *pte, pte_t *_pte, |
554 | struct list_head *compound_pagelist) | |
b46e756f | 555 | { |
5503fbf2 KS |
556 | struct page *page, *tmp; |
557 | ||
b46e756f KS |
558 | while (--_pte >= pte) { |
559 | pte_t pteval = *_pte; | |
5503fbf2 KS |
560 | |
561 | page = pte_page(pteval); | |
562 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)) && | |
563 | !PageCompound(page)) | |
564 | release_pte_page(page); | |
565 | } | |
566 | ||
567 | list_for_each_entry_safe(page, tmp, compound_pagelist, lru) { | |
568 | list_del(&page->lru); | |
569 | release_pte_page(page); | |
b46e756f KS |
570 | } |
571 | } | |
572 | ||
9445689f KS |
573 | static bool is_refcount_suitable(struct page *page) |
574 | { | |
575 | int expected_refcount; | |
576 | ||
577 | expected_refcount = total_mapcount(page); | |
578 | if (PageSwapCache(page)) | |
579 | expected_refcount += compound_nr(page); | |
580 | ||
581 | return page_count(page) == expected_refcount; | |
582 | } | |
583 | ||
b46e756f KS |
584 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, |
585 | unsigned long address, | |
5503fbf2 KS |
586 | pte_t *pte, |
587 | struct list_head *compound_pagelist) | |
b46e756f KS |
588 | { |
589 | struct page *page = NULL; | |
590 | pte_t *_pte; | |
71a2c112 | 591 | int none_or_zero = 0, shared = 0, result = 0, referenced = 0; |
0db501f7 | 592 | bool writable = false; |
b46e756f KS |
593 | |
594 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
595 | _pte++, address += PAGE_SIZE) { | |
596 | pte_t pteval = *_pte; | |
597 | if (pte_none(pteval) || (pte_present(pteval) && | |
598 | is_zero_pfn(pte_pfn(pteval)))) { | |
599 | if (!userfaultfd_armed(vma) && | |
600 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
601 | continue; | |
602 | } else { | |
603 | result = SCAN_EXCEED_NONE_PTE; | |
604 | goto out; | |
605 | } | |
606 | } | |
607 | if (!pte_present(pteval)) { | |
608 | result = SCAN_PTE_NON_PRESENT; | |
609 | goto out; | |
610 | } | |
611 | page = vm_normal_page(vma, address, pteval); | |
612 | if (unlikely(!page)) { | |
613 | result = SCAN_PAGE_NULL; | |
614 | goto out; | |
615 | } | |
616 | ||
5503fbf2 KS |
617 | VM_BUG_ON_PAGE(!PageAnon(page), page); |
618 | ||
71a2c112 KS |
619 | if (page_mapcount(page) > 1 && |
620 | ++shared > khugepaged_max_ptes_shared) { | |
621 | result = SCAN_EXCEED_SHARED_PTE; | |
622 | goto out; | |
623 | } | |
624 | ||
fece2029 | 625 | if (PageCompound(page)) { |
5503fbf2 KS |
626 | struct page *p; |
627 | page = compound_head(page); | |
fece2029 | 628 | |
5503fbf2 KS |
629 | /* |
630 | * Check if we have dealt with the compound page | |
631 | * already | |
632 | */ | |
633 | list_for_each_entry(p, compound_pagelist, lru) { | |
634 | if (page == p) | |
635 | goto next; | |
636 | } | |
637 | } | |
b46e756f KS |
638 | |
639 | /* | |
640 | * We can do it before isolate_lru_page because the | |
641 | * page can't be freed from under us. NOTE: PG_lock | |
642 | * is needed to serialize against split_huge_page | |
643 | * when invoked from the VM. | |
644 | */ | |
645 | if (!trylock_page(page)) { | |
646 | result = SCAN_PAGE_LOCK; | |
647 | goto out; | |
648 | } | |
649 | ||
650 | /* | |
9445689f KS |
651 | * Check if the page has any GUP (or other external) pins. |
652 | * | |
653 | * The page table that maps the page has been already unlinked | |
654 | * from the page table tree and this process cannot get | |
655 | * an additinal pin on the page. | |
656 | * | |
657 | * New pins can come later if the page is shared across fork, | |
658 | * but not from this process. The other process cannot write to | |
659 | * the page, only trigger CoW. | |
b46e756f | 660 | */ |
9445689f | 661 | if (!is_refcount_suitable(page)) { |
b46e756f KS |
662 | unlock_page(page); |
663 | result = SCAN_PAGE_COUNT; | |
664 | goto out; | |
665 | } | |
5503fbf2 KS |
666 | if (!pte_write(pteval) && PageSwapCache(page) && |
667 | !reuse_swap_page(page, NULL)) { | |
b46e756f | 668 | /* |
5503fbf2 KS |
669 | * Page is in the swap cache and cannot be re-used. |
670 | * It cannot be collapsed into a THP. | |
b46e756f | 671 | */ |
5503fbf2 KS |
672 | unlock_page(page); |
673 | result = SCAN_SWAP_CACHE_PAGE; | |
674 | goto out; | |
b46e756f KS |
675 | } |
676 | ||
677 | /* | |
678 | * Isolate the page to avoid collapsing an hugepage | |
679 | * currently in use by the VM. | |
680 | */ | |
681 | if (isolate_lru_page(page)) { | |
682 | unlock_page(page); | |
683 | result = SCAN_DEL_PAGE_LRU; | |
684 | goto out; | |
685 | } | |
5503fbf2 KS |
686 | mod_node_page_state(page_pgdat(page), |
687 | NR_ISOLATED_ANON + page_is_file_lru(page), | |
688 | compound_nr(page)); | |
b46e756f KS |
689 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
690 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
691 | ||
5503fbf2 KS |
692 | if (PageCompound(page)) |
693 | list_add_tail(&page->lru, compound_pagelist); | |
694 | next: | |
0db501f7 | 695 | /* There should be enough young pte to collapse the page */ |
b46e756f KS |
696 | if (pte_young(pteval) || |
697 | page_is_young(page) || PageReferenced(page) || | |
698 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 699 | referenced++; |
5503fbf2 KS |
700 | |
701 | if (pte_write(pteval)) | |
702 | writable = true; | |
b46e756f KS |
703 | } |
704 | if (likely(writable)) { | |
705 | if (likely(referenced)) { | |
706 | result = SCAN_SUCCEED; | |
707 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, | |
708 | referenced, writable, result); | |
709 | return 1; | |
710 | } | |
711 | } else { | |
712 | result = SCAN_PAGE_RO; | |
713 | } | |
714 | ||
715 | out: | |
5503fbf2 | 716 | release_pte_pages(pte, _pte, compound_pagelist); |
b46e756f KS |
717 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, |
718 | referenced, writable, result); | |
719 | return 0; | |
720 | } | |
721 | ||
722 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
723 | struct vm_area_struct *vma, | |
724 | unsigned long address, | |
5503fbf2 KS |
725 | spinlock_t *ptl, |
726 | struct list_head *compound_pagelist) | |
b46e756f | 727 | { |
5503fbf2 | 728 | struct page *src_page, *tmp; |
b46e756f | 729 | pte_t *_pte; |
338a16ba DR |
730 | for (_pte = pte; _pte < pte + HPAGE_PMD_NR; |
731 | _pte++, page++, address += PAGE_SIZE) { | |
b46e756f | 732 | pte_t pteval = *_pte; |
b46e756f KS |
733 | |
734 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
735 | clear_user_highpage(page, address); | |
736 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
737 | if (is_zero_pfn(pte_pfn(pteval))) { | |
738 | /* | |
739 | * ptl mostly unnecessary. | |
740 | */ | |
741 | spin_lock(ptl); | |
742 | /* | |
743 | * paravirt calls inside pte_clear here are | |
744 | * superfluous. | |
745 | */ | |
746 | pte_clear(vma->vm_mm, address, _pte); | |
747 | spin_unlock(ptl); | |
748 | } | |
749 | } else { | |
750 | src_page = pte_page(pteval); | |
751 | copy_user_highpage(page, src_page, address, vma); | |
5503fbf2 KS |
752 | if (!PageCompound(src_page)) |
753 | release_pte_page(src_page); | |
b46e756f KS |
754 | /* |
755 | * ptl mostly unnecessary, but preempt has to | |
756 | * be disabled to update the per-cpu stats | |
757 | * inside page_remove_rmap(). | |
758 | */ | |
759 | spin_lock(ptl); | |
760 | /* | |
761 | * paravirt calls inside pte_clear here are | |
762 | * superfluous. | |
763 | */ | |
764 | pte_clear(vma->vm_mm, address, _pte); | |
765 | page_remove_rmap(src_page, false); | |
766 | spin_unlock(ptl); | |
767 | free_page_and_swap_cache(src_page); | |
768 | } | |
b46e756f | 769 | } |
5503fbf2 KS |
770 | |
771 | list_for_each_entry_safe(src_page, tmp, compound_pagelist, lru) { | |
772 | list_del(&src_page->lru); | |
773 | release_pte_page(src_page); | |
774 | } | |
b46e756f KS |
775 | } |
776 | ||
777 | static void khugepaged_alloc_sleep(void) | |
778 | { | |
779 | DEFINE_WAIT(wait); | |
780 | ||
781 | add_wait_queue(&khugepaged_wait, &wait); | |
782 | freezable_schedule_timeout_interruptible( | |
783 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
784 | remove_wait_queue(&khugepaged_wait, &wait); | |
785 | } | |
786 | ||
787 | static int khugepaged_node_load[MAX_NUMNODES]; | |
788 | ||
789 | static bool khugepaged_scan_abort(int nid) | |
790 | { | |
791 | int i; | |
792 | ||
793 | /* | |
a5f5f91d | 794 | * If node_reclaim_mode is disabled, then no extra effort is made to |
b46e756f KS |
795 | * allocate memory locally. |
796 | */ | |
a5f5f91d | 797 | if (!node_reclaim_mode) |
b46e756f KS |
798 | return false; |
799 | ||
800 | /* If there is a count for this node already, it must be acceptable */ | |
801 | if (khugepaged_node_load[nid]) | |
802 | return false; | |
803 | ||
804 | for (i = 0; i < MAX_NUMNODES; i++) { | |
805 | if (!khugepaged_node_load[i]) | |
806 | continue; | |
a55c7454 | 807 | if (node_distance(nid, i) > node_reclaim_distance) |
b46e756f KS |
808 | return true; |
809 | } | |
810 | return false; | |
811 | } | |
812 | ||
813 | /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */ | |
814 | static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void) | |
815 | { | |
25160354 | 816 | return khugepaged_defrag() ? GFP_TRANSHUGE : GFP_TRANSHUGE_LIGHT; |
b46e756f KS |
817 | } |
818 | ||
819 | #ifdef CONFIG_NUMA | |
820 | static int khugepaged_find_target_node(void) | |
821 | { | |
822 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
823 | int nid, target_node = 0, max_value = 0; | |
824 | ||
825 | /* find first node with max normal pages hit */ | |
826 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
827 | if (khugepaged_node_load[nid] > max_value) { | |
828 | max_value = khugepaged_node_load[nid]; | |
829 | target_node = nid; | |
830 | } | |
831 | ||
832 | /* do some balance if several nodes have the same hit record */ | |
833 | if (target_node <= last_khugepaged_target_node) | |
834 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
835 | nid++) | |
836 | if (max_value == khugepaged_node_load[nid]) { | |
837 | target_node = nid; | |
838 | break; | |
839 | } | |
840 | ||
841 | last_khugepaged_target_node = target_node; | |
842 | return target_node; | |
843 | } | |
844 | ||
845 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
846 | { | |
847 | if (IS_ERR(*hpage)) { | |
848 | if (!*wait) | |
849 | return false; | |
850 | ||
851 | *wait = false; | |
852 | *hpage = NULL; | |
853 | khugepaged_alloc_sleep(); | |
854 | } else if (*hpage) { | |
855 | put_page(*hpage); | |
856 | *hpage = NULL; | |
857 | } | |
858 | ||
859 | return true; | |
860 | } | |
861 | ||
862 | static struct page * | |
988ddb71 | 863 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f KS |
864 | { |
865 | VM_BUG_ON_PAGE(*hpage, *hpage); | |
866 | ||
b46e756f KS |
867 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); |
868 | if (unlikely(!*hpage)) { | |
869 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
870 | *hpage = ERR_PTR(-ENOMEM); | |
871 | return NULL; | |
872 | } | |
873 | ||
874 | prep_transhuge_page(*hpage); | |
875 | count_vm_event(THP_COLLAPSE_ALLOC); | |
876 | return *hpage; | |
877 | } | |
878 | #else | |
879 | static int khugepaged_find_target_node(void) | |
880 | { | |
881 | return 0; | |
882 | } | |
883 | ||
884 | static inline struct page *alloc_khugepaged_hugepage(void) | |
885 | { | |
886 | struct page *page; | |
887 | ||
888 | page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(), | |
889 | HPAGE_PMD_ORDER); | |
890 | if (page) | |
891 | prep_transhuge_page(page); | |
892 | return page; | |
893 | } | |
894 | ||
895 | static struct page *khugepaged_alloc_hugepage(bool *wait) | |
896 | { | |
897 | struct page *hpage; | |
898 | ||
899 | do { | |
900 | hpage = alloc_khugepaged_hugepage(); | |
901 | if (!hpage) { | |
902 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
903 | if (!*wait) | |
904 | return NULL; | |
905 | ||
906 | *wait = false; | |
907 | khugepaged_alloc_sleep(); | |
908 | } else | |
909 | count_vm_event(THP_COLLAPSE_ALLOC); | |
910 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
911 | ||
912 | return hpage; | |
913 | } | |
914 | ||
915 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
916 | { | |
917 | if (!*hpage) | |
918 | *hpage = khugepaged_alloc_hugepage(wait); | |
919 | ||
920 | if (unlikely(!*hpage)) | |
921 | return false; | |
922 | ||
923 | return true; | |
924 | } | |
925 | ||
926 | static struct page * | |
988ddb71 | 927 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f | 928 | { |
b46e756f KS |
929 | VM_BUG_ON(!*hpage); |
930 | ||
931 | return *hpage; | |
932 | } | |
933 | #endif | |
934 | ||
b46e756f KS |
935 | /* |
936 | * If mmap_sem temporarily dropped, revalidate vma | |
937 | * before taking mmap_sem. | |
938 | * Return 0 if succeeds, otherwise return none-zero | |
939 | * value (scan code). | |
940 | */ | |
941 | ||
c131f751 KS |
942 | static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, |
943 | struct vm_area_struct **vmap) | |
b46e756f KS |
944 | { |
945 | struct vm_area_struct *vma; | |
946 | unsigned long hstart, hend; | |
947 | ||
948 | if (unlikely(khugepaged_test_exit(mm))) | |
949 | return SCAN_ANY_PROCESS; | |
950 | ||
c131f751 | 951 | *vmap = vma = find_vma(mm, address); |
b46e756f KS |
952 | if (!vma) |
953 | return SCAN_VMA_NULL; | |
954 | ||
955 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
956 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
957 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
958 | return SCAN_ADDRESS_RANGE; | |
50f8b92f | 959 | if (!hugepage_vma_check(vma, vma->vm_flags)) |
b46e756f KS |
960 | return SCAN_VMA_CHECK; |
961 | return 0; | |
962 | } | |
963 | ||
964 | /* | |
965 | * Bring missing pages in from swap, to complete THP collapse. | |
966 | * Only done if khugepaged_scan_pmd believes it is worthwhile. | |
967 | * | |
968 | * Called and returns without pte mapped or spinlocks held, | |
969 | * but with mmap_sem held to protect against vma changes. | |
970 | */ | |
971 | ||
972 | static bool __collapse_huge_page_swapin(struct mm_struct *mm, | |
973 | struct vm_area_struct *vma, | |
0db501f7 EA |
974 | unsigned long address, pmd_t *pmd, |
975 | int referenced) | |
b46e756f | 976 | { |
2b740303 SJ |
977 | int swapped_in = 0; |
978 | vm_fault_t ret = 0; | |
82b0f8c3 | 979 | struct vm_fault vmf = { |
b46e756f KS |
980 | .vma = vma, |
981 | .address = address, | |
982 | .flags = FAULT_FLAG_ALLOW_RETRY, | |
983 | .pmd = pmd, | |
0721ec8b | 984 | .pgoff = linear_page_index(vma, address), |
b46e756f KS |
985 | }; |
986 | ||
82b0f8c3 JK |
987 | vmf.pte = pte_offset_map(pmd, address); |
988 | for (; vmf.address < address + HPAGE_PMD_NR*PAGE_SIZE; | |
989 | vmf.pte++, vmf.address += PAGE_SIZE) { | |
2994302b JK |
990 | vmf.orig_pte = *vmf.pte; |
991 | if (!is_swap_pte(vmf.orig_pte)) | |
b46e756f KS |
992 | continue; |
993 | swapped_in++; | |
2994302b | 994 | ret = do_swap_page(&vmf); |
0db501f7 | 995 | |
b46e756f KS |
996 | /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */ |
997 | if (ret & VM_FAULT_RETRY) { | |
998 | down_read(&mm->mmap_sem); | |
82b0f8c3 | 999 | if (hugepage_vma_revalidate(mm, address, &vmf.vma)) { |
47f863ea | 1000 | /* vma is no longer available, don't continue to swapin */ |
0db501f7 | 1001 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f | 1002 | return false; |
47f863ea | 1003 | } |
b46e756f | 1004 | /* check if the pmd is still valid */ |
835152a2 SP |
1005 | if (mm_find_pmd(mm, address) != pmd) { |
1006 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); | |
b46e756f | 1007 | return false; |
835152a2 | 1008 | } |
b46e756f KS |
1009 | } |
1010 | if (ret & VM_FAULT_ERROR) { | |
0db501f7 | 1011 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f KS |
1012 | return false; |
1013 | } | |
1014 | /* pte is unmapped now, we need to map it */ | |
82b0f8c3 | 1015 | vmf.pte = pte_offset_map(pmd, vmf.address); |
b46e756f | 1016 | } |
82b0f8c3 JK |
1017 | vmf.pte--; |
1018 | pte_unmap(vmf.pte); | |
ae2c5d80 KS |
1019 | |
1020 | /* Drain LRU add pagevec to remove extra pin on the swapped in pages */ | |
1021 | if (swapped_in) | |
1022 | lru_add_drain(); | |
1023 | ||
0db501f7 | 1024 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1); |
b46e756f KS |
1025 | return true; |
1026 | } | |
1027 | ||
1028 | static void collapse_huge_page(struct mm_struct *mm, | |
1029 | unsigned long address, | |
1030 | struct page **hpage, | |
ffe945e6 | 1031 | int node, int referenced, int unmapped) |
b46e756f | 1032 | { |
5503fbf2 | 1033 | LIST_HEAD(compound_pagelist); |
b46e756f KS |
1034 | pmd_t *pmd, _pmd; |
1035 | pte_t *pte; | |
1036 | pgtable_t pgtable; | |
1037 | struct page *new_page; | |
1038 | spinlock_t *pmd_ptl, *pte_ptl; | |
1039 | int isolated = 0, result = 0; | |
1040 | struct mem_cgroup *memcg; | |
c131f751 | 1041 | struct vm_area_struct *vma; |
ac46d4f3 | 1042 | struct mmu_notifier_range range; |
b46e756f KS |
1043 | gfp_t gfp; |
1044 | ||
1045 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1046 | ||
1047 | /* Only allocate from the target node */ | |
41b6167e | 1048 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
b46e756f | 1049 | |
988ddb71 KS |
1050 | /* |
1051 | * Before allocating the hugepage, release the mmap_sem read lock. | |
1052 | * The allocation can take potentially a long time if it involves | |
1053 | * sync compaction, and we do not need to hold the mmap_sem during | |
1054 | * that. We will recheck the vma after taking it again in write mode. | |
1055 | */ | |
1056 | up_read(&mm->mmap_sem); | |
1057 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
b46e756f KS |
1058 | if (!new_page) { |
1059 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
1060 | goto out_nolock; | |
1061 | } | |
1062 | ||
3fba69a5 | 1063 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg))) { |
b46e756f KS |
1064 | result = SCAN_CGROUP_CHARGE_FAIL; |
1065 | goto out_nolock; | |
1066 | } | |
1067 | ||
1068 | down_read(&mm->mmap_sem); | |
c131f751 | 1069 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f | 1070 | if (result) { |
3fba69a5 | 1071 | mem_cgroup_cancel_charge(new_page, memcg); |
b46e756f KS |
1072 | up_read(&mm->mmap_sem); |
1073 | goto out_nolock; | |
1074 | } | |
1075 | ||
1076 | pmd = mm_find_pmd(mm, address); | |
1077 | if (!pmd) { | |
1078 | result = SCAN_PMD_NULL; | |
3fba69a5 | 1079 | mem_cgroup_cancel_charge(new_page, memcg); |
b46e756f KS |
1080 | up_read(&mm->mmap_sem); |
1081 | goto out_nolock; | |
1082 | } | |
1083 | ||
1084 | /* | |
1085 | * __collapse_huge_page_swapin always returns with mmap_sem locked. | |
47f863ea | 1086 | * If it fails, we release mmap_sem and jump out_nolock. |
b46e756f KS |
1087 | * Continuing to collapse causes inconsistency. |
1088 | */ | |
ffe945e6 KS |
1089 | if (unmapped && !__collapse_huge_page_swapin(mm, vma, address, |
1090 | pmd, referenced)) { | |
3fba69a5 | 1091 | mem_cgroup_cancel_charge(new_page, memcg); |
b46e756f KS |
1092 | up_read(&mm->mmap_sem); |
1093 | goto out_nolock; | |
1094 | } | |
1095 | ||
1096 | up_read(&mm->mmap_sem); | |
1097 | /* | |
1098 | * Prevent all access to pagetables with the exception of | |
1099 | * gup_fast later handled by the ptep_clear_flush and the VM | |
1100 | * handled by the anon_vma lock + PG_lock. | |
1101 | */ | |
1102 | down_write(&mm->mmap_sem); | |
59ea6d06 AA |
1103 | result = SCAN_ANY_PROCESS; |
1104 | if (!mmget_still_valid(mm)) | |
1105 | goto out; | |
c131f751 | 1106 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f KS |
1107 | if (result) |
1108 | goto out; | |
1109 | /* check if the pmd is still valid */ | |
1110 | if (mm_find_pmd(mm, address) != pmd) | |
1111 | goto out; | |
1112 | ||
1113 | anon_vma_lock_write(vma->anon_vma); | |
1114 | ||
7269f999 | 1115 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, |
6f4f13e8 | 1116 | address, address + HPAGE_PMD_SIZE); |
ac46d4f3 | 1117 | mmu_notifier_invalidate_range_start(&range); |
ec649c9d VS |
1118 | |
1119 | pte = pte_offset_map(pmd, address); | |
1120 | pte_ptl = pte_lockptr(mm, pmd); | |
1121 | ||
b46e756f KS |
1122 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
1123 | /* | |
1124 | * After this gup_fast can't run anymore. This also removes | |
1125 | * any huge TLB entry from the CPU so we won't allow | |
1126 | * huge and small TLB entries for the same virtual address | |
1127 | * to avoid the risk of CPU bugs in that area. | |
1128 | */ | |
1129 | _pmd = pmdp_collapse_flush(vma, address, pmd); | |
1130 | spin_unlock(pmd_ptl); | |
ac46d4f3 | 1131 | mmu_notifier_invalidate_range_end(&range); |
b46e756f KS |
1132 | |
1133 | spin_lock(pte_ptl); | |
5503fbf2 KS |
1134 | isolated = __collapse_huge_page_isolate(vma, address, pte, |
1135 | &compound_pagelist); | |
b46e756f KS |
1136 | spin_unlock(pte_ptl); |
1137 | ||
1138 | if (unlikely(!isolated)) { | |
1139 | pte_unmap(pte); | |
1140 | spin_lock(pmd_ptl); | |
1141 | BUG_ON(!pmd_none(*pmd)); | |
1142 | /* | |
1143 | * We can only use set_pmd_at when establishing | |
1144 | * hugepmds and never for establishing regular pmds that | |
1145 | * points to regular pagetables. Use pmd_populate for that | |
1146 | */ | |
1147 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
1148 | spin_unlock(pmd_ptl); | |
1149 | anon_vma_unlock_write(vma->anon_vma); | |
1150 | result = SCAN_FAIL; | |
1151 | goto out; | |
1152 | } | |
1153 | ||
1154 | /* | |
1155 | * All pages are isolated and locked so anon_vma rmap | |
1156 | * can't run anymore. | |
1157 | */ | |
1158 | anon_vma_unlock_write(vma->anon_vma); | |
1159 | ||
5503fbf2 KS |
1160 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl, |
1161 | &compound_pagelist); | |
b46e756f KS |
1162 | pte_unmap(pte); |
1163 | __SetPageUptodate(new_page); | |
1164 | pgtable = pmd_pgtable(_pmd); | |
1165 | ||
1166 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); | |
f55e1014 | 1167 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); |
b46e756f KS |
1168 | |
1169 | /* | |
1170 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
1171 | * this is needed to avoid the copy_huge_page writes to become | |
1172 | * visible after the set_pmd_at() write. | |
1173 | */ | |
1174 | smp_wmb(); | |
1175 | ||
1176 | spin_lock(pmd_ptl); | |
1177 | BUG_ON(!pmd_none(*pmd)); | |
1178 | page_add_new_anon_rmap(new_page, vma, address, true); | |
3fba69a5 | 1179 | mem_cgroup_commit_charge(new_page, memcg, false); |
1ff9e6e1 | 1180 | count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1); |
b46e756f KS |
1181 | lru_cache_add_active_or_unevictable(new_page, vma); |
1182 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
1183 | set_pmd_at(mm, address, pmd, _pmd); | |
1184 | update_mmu_cache_pmd(vma, address, pmd); | |
1185 | spin_unlock(pmd_ptl); | |
1186 | ||
1187 | *hpage = NULL; | |
1188 | ||
1189 | khugepaged_pages_collapsed++; | |
1190 | result = SCAN_SUCCEED; | |
1191 | out_up_write: | |
1192 | up_write(&mm->mmap_sem); | |
1193 | out_nolock: | |
1194 | trace_mm_collapse_huge_page(mm, isolated, result); | |
1195 | return; | |
1196 | out: | |
3fba69a5 | 1197 | mem_cgroup_cancel_charge(new_page, memcg); |
b46e756f KS |
1198 | goto out_up_write; |
1199 | } | |
1200 | ||
1201 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
1202 | struct vm_area_struct *vma, | |
1203 | unsigned long address, | |
1204 | struct page **hpage) | |
1205 | { | |
1206 | pmd_t *pmd; | |
1207 | pte_t *pte, *_pte; | |
71a2c112 KS |
1208 | int ret = 0, result = 0, referenced = 0; |
1209 | int none_or_zero = 0, shared = 0; | |
b46e756f KS |
1210 | struct page *page = NULL; |
1211 | unsigned long _address; | |
1212 | spinlock_t *ptl; | |
1213 | int node = NUMA_NO_NODE, unmapped = 0; | |
0db501f7 | 1214 | bool writable = false; |
b46e756f KS |
1215 | |
1216 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1217 | ||
1218 | pmd = mm_find_pmd(mm, address); | |
1219 | if (!pmd) { | |
1220 | result = SCAN_PMD_NULL; | |
1221 | goto out; | |
1222 | } | |
1223 | ||
1224 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1225 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1226 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1227 | _pte++, _address += PAGE_SIZE) { | |
1228 | pte_t pteval = *_pte; | |
1229 | if (is_swap_pte(pteval)) { | |
1230 | if (++unmapped <= khugepaged_max_ptes_swap) { | |
e1e267c7 PX |
1231 | /* |
1232 | * Always be strict with uffd-wp | |
1233 | * enabled swap entries. Please see | |
1234 | * comment below for pte_uffd_wp(). | |
1235 | */ | |
1236 | if (pte_swp_uffd_wp(pteval)) { | |
1237 | result = SCAN_PTE_UFFD_WP; | |
1238 | goto out_unmap; | |
1239 | } | |
b46e756f KS |
1240 | continue; |
1241 | } else { | |
1242 | result = SCAN_EXCEED_SWAP_PTE; | |
1243 | goto out_unmap; | |
1244 | } | |
1245 | } | |
1246 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
1247 | if (!userfaultfd_armed(vma) && | |
1248 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
1249 | continue; | |
1250 | } else { | |
1251 | result = SCAN_EXCEED_NONE_PTE; | |
1252 | goto out_unmap; | |
1253 | } | |
1254 | } | |
1255 | if (!pte_present(pteval)) { | |
1256 | result = SCAN_PTE_NON_PRESENT; | |
1257 | goto out_unmap; | |
1258 | } | |
e1e267c7 PX |
1259 | if (pte_uffd_wp(pteval)) { |
1260 | /* | |
1261 | * Don't collapse the page if any of the small | |
1262 | * PTEs are armed with uffd write protection. | |
1263 | * Here we can also mark the new huge pmd as | |
1264 | * write protected if any of the small ones is | |
1265 | * marked but that could bring uknown | |
1266 | * userfault messages that falls outside of | |
1267 | * the registered range. So, just be simple. | |
1268 | */ | |
1269 | result = SCAN_PTE_UFFD_WP; | |
1270 | goto out_unmap; | |
1271 | } | |
b46e756f KS |
1272 | if (pte_write(pteval)) |
1273 | writable = true; | |
1274 | ||
1275 | page = vm_normal_page(vma, _address, pteval); | |
1276 | if (unlikely(!page)) { | |
1277 | result = SCAN_PAGE_NULL; | |
1278 | goto out_unmap; | |
1279 | } | |
1280 | ||
71a2c112 KS |
1281 | if (page_mapcount(page) > 1 && |
1282 | ++shared > khugepaged_max_ptes_shared) { | |
1283 | result = SCAN_EXCEED_SHARED_PTE; | |
1284 | goto out_unmap; | |
1285 | } | |
1286 | ||
5503fbf2 | 1287 | page = compound_head(page); |
b46e756f KS |
1288 | |
1289 | /* | |
1290 | * Record which node the original page is from and save this | |
1291 | * information to khugepaged_node_load[]. | |
1292 | * Khupaged will allocate hugepage from the node has the max | |
1293 | * hit record. | |
1294 | */ | |
1295 | node = page_to_nid(page); | |
1296 | if (khugepaged_scan_abort(node)) { | |
1297 | result = SCAN_SCAN_ABORT; | |
1298 | goto out_unmap; | |
1299 | } | |
1300 | khugepaged_node_load[node]++; | |
1301 | if (!PageLRU(page)) { | |
1302 | result = SCAN_PAGE_LRU; | |
1303 | goto out_unmap; | |
1304 | } | |
1305 | if (PageLocked(page)) { | |
1306 | result = SCAN_PAGE_LOCK; | |
1307 | goto out_unmap; | |
1308 | } | |
1309 | if (!PageAnon(page)) { | |
1310 | result = SCAN_PAGE_ANON; | |
1311 | goto out_unmap; | |
1312 | } | |
1313 | ||
1314 | /* | |
9445689f KS |
1315 | * Check if the page has any GUP (or other external) pins. |
1316 | * | |
1317 | * Here the check is racy it may see totmal_mapcount > refcount | |
1318 | * in some cases. | |
1319 | * For example, one process with one forked child process. | |
1320 | * The parent has the PMD split due to MADV_DONTNEED, then | |
1321 | * the child is trying unmap the whole PMD, but khugepaged | |
1322 | * may be scanning the parent between the child has | |
1323 | * PageDoubleMap flag cleared and dec the mapcount. So | |
1324 | * khugepaged may see total_mapcount > refcount. | |
1325 | * | |
1326 | * But such case is ephemeral we could always retry collapse | |
1327 | * later. However it may report false positive if the page | |
1328 | * has excessive GUP pins (i.e. 512). Anyway the same check | |
1329 | * will be done again later the risk seems low. | |
b46e756f | 1330 | */ |
9445689f | 1331 | if (!is_refcount_suitable(page)) { |
b46e756f KS |
1332 | result = SCAN_PAGE_COUNT; |
1333 | goto out_unmap; | |
1334 | } | |
1335 | if (pte_young(pteval) || | |
1336 | page_is_young(page) || PageReferenced(page) || | |
1337 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 1338 | referenced++; |
b46e756f | 1339 | } |
ffe945e6 | 1340 | if (!writable) { |
b46e756f | 1341 | result = SCAN_PAGE_RO; |
ffe945e6 KS |
1342 | } else if (!referenced || (unmapped && referenced < HPAGE_PMD_NR/2)) { |
1343 | result = SCAN_LACK_REFERENCED_PAGE; | |
1344 | } else { | |
1345 | result = SCAN_SUCCEED; | |
1346 | ret = 1; | |
b46e756f KS |
1347 | } |
1348 | out_unmap: | |
1349 | pte_unmap_unlock(pte, ptl); | |
1350 | if (ret) { | |
1351 | node = khugepaged_find_target_node(); | |
1352 | /* collapse_huge_page will return with the mmap_sem released */ | |
ffe945e6 KS |
1353 | collapse_huge_page(mm, address, hpage, node, |
1354 | referenced, unmapped); | |
b46e756f KS |
1355 | } |
1356 | out: | |
1357 | trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, | |
1358 | none_or_zero, result, unmapped); | |
1359 | return ret; | |
1360 | } | |
1361 | ||
1362 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
1363 | { | |
1364 | struct mm_struct *mm = mm_slot->mm; | |
1365 | ||
35f3aa39 | 1366 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
1367 | |
1368 | if (khugepaged_test_exit(mm)) { | |
1369 | /* free mm_slot */ | |
1370 | hash_del(&mm_slot->hash); | |
1371 | list_del(&mm_slot->mm_node); | |
1372 | ||
1373 | /* | |
1374 | * Not strictly needed because the mm exited already. | |
1375 | * | |
1376 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1377 | */ | |
1378 | ||
1379 | /* khugepaged_mm_lock actually not necessary for the below */ | |
1380 | free_mm_slot(mm_slot); | |
1381 | mmdrop(mm); | |
1382 | } | |
1383 | } | |
1384 | ||
396bcc52 | 1385 | #ifdef CONFIG_SHMEM |
27e1f827 SL |
1386 | /* |
1387 | * Notify khugepaged that given addr of the mm is pte-mapped THP. Then | |
1388 | * khugepaged should try to collapse the page table. | |
1389 | */ | |
1390 | static int khugepaged_add_pte_mapped_thp(struct mm_struct *mm, | |
1391 | unsigned long addr) | |
1392 | { | |
1393 | struct mm_slot *mm_slot; | |
1394 | ||
1395 | VM_BUG_ON(addr & ~HPAGE_PMD_MASK); | |
1396 | ||
1397 | spin_lock(&khugepaged_mm_lock); | |
1398 | mm_slot = get_mm_slot(mm); | |
1399 | if (likely(mm_slot && mm_slot->nr_pte_mapped_thp < MAX_PTE_MAPPED_THP)) | |
1400 | mm_slot->pte_mapped_thp[mm_slot->nr_pte_mapped_thp++] = addr; | |
1401 | spin_unlock(&khugepaged_mm_lock); | |
1402 | return 0; | |
1403 | } | |
1404 | ||
1405 | /** | |
1406 | * Try to collapse a pte-mapped THP for mm at address haddr. | |
1407 | * | |
1408 | * This function checks whether all the PTEs in the PMD are pointing to the | |
1409 | * right THP. If so, retract the page table so the THP can refault in with | |
1410 | * as pmd-mapped. | |
1411 | */ | |
1412 | void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) | |
1413 | { | |
1414 | unsigned long haddr = addr & HPAGE_PMD_MASK; | |
1415 | struct vm_area_struct *vma = find_vma(mm, haddr); | |
1416 | struct page *hpage = NULL; | |
1417 | pte_t *start_pte, *pte; | |
1418 | pmd_t *pmd, _pmd; | |
1419 | spinlock_t *ptl; | |
1420 | int count = 0; | |
1421 | int i; | |
1422 | ||
1423 | if (!vma || !vma->vm_file || | |
1424 | vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE) | |
1425 | return; | |
1426 | ||
1427 | /* | |
1428 | * This vm_flags may not have VM_HUGEPAGE if the page was not | |
1429 | * collapsed by this mm. But we can still collapse if the page is | |
1430 | * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check() | |
1431 | * will not fail the vma for missing VM_HUGEPAGE | |
1432 | */ | |
1433 | if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE)) | |
1434 | return; | |
1435 | ||
1436 | pmd = mm_find_pmd(mm, haddr); | |
1437 | if (!pmd) | |
1438 | return; | |
1439 | ||
1440 | start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl); | |
1441 | ||
1442 | /* step 1: check all mapped PTEs are to the right huge page */ | |
1443 | for (i = 0, addr = haddr, pte = start_pte; | |
1444 | i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) { | |
1445 | struct page *page; | |
1446 | ||
1447 | /* empty pte, skip */ | |
1448 | if (pte_none(*pte)) | |
1449 | continue; | |
1450 | ||
1451 | /* page swapped out, abort */ | |
1452 | if (!pte_present(*pte)) | |
1453 | goto abort; | |
1454 | ||
1455 | page = vm_normal_page(vma, addr, *pte); | |
1456 | ||
1457 | if (!page || !PageCompound(page)) | |
1458 | goto abort; | |
1459 | ||
1460 | if (!hpage) { | |
1461 | hpage = compound_head(page); | |
1462 | /* | |
1463 | * The mapping of the THP should not change. | |
1464 | * | |
1465 | * Note that uprobe, debugger, or MAP_PRIVATE may | |
1466 | * change the page table, but the new page will | |
1467 | * not pass PageCompound() check. | |
1468 | */ | |
1469 | if (WARN_ON(hpage->mapping != vma->vm_file->f_mapping)) | |
1470 | goto abort; | |
1471 | } | |
1472 | ||
1473 | /* | |
1474 | * Confirm the page maps to the correct subpage. | |
1475 | * | |
1476 | * Note that uprobe, debugger, or MAP_PRIVATE may change | |
1477 | * the page table, but the new page will not pass | |
1478 | * PageCompound() check. | |
1479 | */ | |
1480 | if (WARN_ON(hpage + i != page)) | |
1481 | goto abort; | |
1482 | count++; | |
1483 | } | |
1484 | ||
1485 | /* step 2: adjust rmap */ | |
1486 | for (i = 0, addr = haddr, pte = start_pte; | |
1487 | i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) { | |
1488 | struct page *page; | |
1489 | ||
1490 | if (pte_none(*pte)) | |
1491 | continue; | |
1492 | page = vm_normal_page(vma, addr, *pte); | |
1493 | page_remove_rmap(page, false); | |
1494 | } | |
1495 | ||
1496 | pte_unmap_unlock(start_pte, ptl); | |
1497 | ||
1498 | /* step 3: set proper refcount and mm_counters. */ | |
1499 | if (hpage) { | |
1500 | page_ref_sub(hpage, count); | |
1501 | add_mm_counter(vma->vm_mm, mm_counter_file(hpage), -count); | |
1502 | } | |
1503 | ||
1504 | /* step 4: collapse pmd */ | |
1505 | ptl = pmd_lock(vma->vm_mm, pmd); | |
1506 | _pmd = pmdp_collapse_flush(vma, addr, pmd); | |
1507 | spin_unlock(ptl); | |
1508 | mm_dec_nr_ptes(mm); | |
1509 | pte_free(mm, pmd_pgtable(_pmd)); | |
1510 | return; | |
1511 | ||
1512 | abort: | |
1513 | pte_unmap_unlock(start_pte, ptl); | |
1514 | } | |
1515 | ||
1516 | static int khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) | |
1517 | { | |
1518 | struct mm_struct *mm = mm_slot->mm; | |
1519 | int i; | |
1520 | ||
1521 | if (likely(mm_slot->nr_pte_mapped_thp == 0)) | |
1522 | return 0; | |
1523 | ||
1524 | if (!down_write_trylock(&mm->mmap_sem)) | |
1525 | return -EBUSY; | |
1526 | ||
1527 | if (unlikely(khugepaged_test_exit(mm))) | |
1528 | goto out; | |
1529 | ||
1530 | for (i = 0; i < mm_slot->nr_pte_mapped_thp; i++) | |
1531 | collapse_pte_mapped_thp(mm, mm_slot->pte_mapped_thp[i]); | |
1532 | ||
1533 | out: | |
1534 | mm_slot->nr_pte_mapped_thp = 0; | |
1535 | up_write(&mm->mmap_sem); | |
1536 | return 0; | |
1537 | } | |
1538 | ||
f3f0e1d2 KS |
1539 | static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) |
1540 | { | |
1541 | struct vm_area_struct *vma; | |
1542 | unsigned long addr; | |
1543 | pmd_t *pmd, _pmd; | |
1544 | ||
1545 | i_mmap_lock_write(mapping); | |
1546 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { | |
27e1f827 SL |
1547 | /* |
1548 | * Check vma->anon_vma to exclude MAP_PRIVATE mappings that | |
1549 | * got written to. These VMAs are likely not worth investing | |
1550 | * down_write(mmap_sem) as PMD-mapping is likely to be split | |
1551 | * later. | |
1552 | * | |
1553 | * Not that vma->anon_vma check is racy: it can be set up after | |
1554 | * the check but before we took mmap_sem by the fault path. | |
1555 | * But page lock would prevent establishing any new ptes of the | |
1556 | * page, so we are safe. | |
1557 | * | |
1558 | * An alternative would be drop the check, but check that page | |
1559 | * table is clear before calling pmdp_collapse_flush() under | |
1560 | * ptl. It has higher chance to recover THP for the VMA, but | |
1561 | * has higher cost too. | |
1562 | */ | |
f3f0e1d2 KS |
1563 | if (vma->anon_vma) |
1564 | continue; | |
1565 | addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
1566 | if (addr & ~HPAGE_PMD_MASK) | |
1567 | continue; | |
1568 | if (vma->vm_end < addr + HPAGE_PMD_SIZE) | |
1569 | continue; | |
1570 | pmd = mm_find_pmd(vma->vm_mm, addr); | |
1571 | if (!pmd) | |
1572 | continue; | |
1573 | /* | |
1574 | * We need exclusive mmap_sem to retract page table. | |
27e1f827 SL |
1575 | * |
1576 | * We use trylock due to lock inversion: we need to acquire | |
1577 | * mmap_sem while holding page lock. Fault path does it in | |
1578 | * reverse order. Trylock is a way to avoid deadlock. | |
f3f0e1d2 KS |
1579 | */ |
1580 | if (down_write_trylock(&vma->vm_mm->mmap_sem)) { | |
1581 | spinlock_t *ptl = pmd_lock(vma->vm_mm, pmd); | |
1582 | /* assume page table is clear */ | |
1583 | _pmd = pmdp_collapse_flush(vma, addr, pmd); | |
1584 | spin_unlock(ptl); | |
1585 | up_write(&vma->vm_mm->mmap_sem); | |
c4812909 | 1586 | mm_dec_nr_ptes(vma->vm_mm); |
d670ffd8 | 1587 | pte_free(vma->vm_mm, pmd_pgtable(_pmd)); |
27e1f827 SL |
1588 | } else { |
1589 | /* Try again later */ | |
1590 | khugepaged_add_pte_mapped_thp(vma->vm_mm, addr); | |
f3f0e1d2 KS |
1591 | } |
1592 | } | |
1593 | i_mmap_unlock_write(mapping); | |
1594 | } | |
1595 | ||
1596 | /** | |
99cb0dbd | 1597 | * collapse_file - collapse filemap/tmpfs/shmem pages into huge one. |
f3f0e1d2 KS |
1598 | * |
1599 | * Basic scheme is simple, details are more complex: | |
87c460a0 | 1600 | * - allocate and lock a new huge page; |
77da9389 | 1601 | * - scan page cache replacing old pages with the new one |
99cb0dbd | 1602 | * + swap/gup in pages if necessary; |
f3f0e1d2 | 1603 | * + fill in gaps; |
77da9389 MW |
1604 | * + keep old pages around in case rollback is required; |
1605 | * - if replacing succeeds: | |
f3f0e1d2 KS |
1606 | * + copy data over; |
1607 | * + free old pages; | |
87c460a0 | 1608 | * + unlock huge page; |
f3f0e1d2 KS |
1609 | * - if replacing failed; |
1610 | * + put all pages back and unfreeze them; | |
77da9389 | 1611 | * + restore gaps in the page cache; |
87c460a0 | 1612 | * + unlock and free huge page; |
f3f0e1d2 | 1613 | */ |
579c571e SL |
1614 | static void collapse_file(struct mm_struct *mm, |
1615 | struct file *file, pgoff_t start, | |
f3f0e1d2 KS |
1616 | struct page **hpage, int node) |
1617 | { | |
579c571e | 1618 | struct address_space *mapping = file->f_mapping; |
f3f0e1d2 | 1619 | gfp_t gfp; |
77da9389 | 1620 | struct page *new_page; |
f3f0e1d2 KS |
1621 | struct mem_cgroup *memcg; |
1622 | pgoff_t index, end = start + HPAGE_PMD_NR; | |
1623 | LIST_HEAD(pagelist); | |
77da9389 | 1624 | XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); |
f3f0e1d2 | 1625 | int nr_none = 0, result = SCAN_SUCCEED; |
99cb0dbd | 1626 | bool is_shmem = shmem_file(file); |
f3f0e1d2 | 1627 | |
99cb0dbd | 1628 | VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); |
f3f0e1d2 KS |
1629 | VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); |
1630 | ||
1631 | /* Only allocate from the target node */ | |
41b6167e | 1632 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
f3f0e1d2 KS |
1633 | |
1634 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
1635 | if (!new_page) { | |
1636 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
1637 | goto out; | |
1638 | } | |
1639 | ||
3fba69a5 | 1640 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg))) { |
f3f0e1d2 KS |
1641 | result = SCAN_CGROUP_CHARGE_FAIL; |
1642 | goto out; | |
1643 | } | |
1644 | ||
95feeabb HD |
1645 | /* This will be less messy when we use multi-index entries */ |
1646 | do { | |
1647 | xas_lock_irq(&xas); | |
1648 | xas_create_range(&xas); | |
1649 | if (!xas_error(&xas)) | |
1650 | break; | |
1651 | xas_unlock_irq(&xas); | |
1652 | if (!xas_nomem(&xas, GFP_KERNEL)) { | |
3fba69a5 | 1653 | mem_cgroup_cancel_charge(new_page, memcg); |
95feeabb HD |
1654 | result = SCAN_FAIL; |
1655 | goto out; | |
1656 | } | |
1657 | } while (1); | |
1658 | ||
042a3082 | 1659 | __SetPageLocked(new_page); |
99cb0dbd SL |
1660 | if (is_shmem) |
1661 | __SetPageSwapBacked(new_page); | |
f3f0e1d2 KS |
1662 | new_page->index = start; |
1663 | new_page->mapping = mapping; | |
f3f0e1d2 | 1664 | |
f3f0e1d2 | 1665 | /* |
87c460a0 HD |
1666 | * At this point the new_page is locked and not up-to-date. |
1667 | * It's safe to insert it into the page cache, because nobody would | |
1668 | * be able to map it or use it in another way until we unlock it. | |
f3f0e1d2 KS |
1669 | */ |
1670 | ||
77da9389 MW |
1671 | xas_set(&xas, start); |
1672 | for (index = start; index < end; index++) { | |
1673 | struct page *page = xas_next(&xas); | |
1674 | ||
1675 | VM_BUG_ON(index != xas.xa_index); | |
99cb0dbd SL |
1676 | if (is_shmem) { |
1677 | if (!page) { | |
1678 | /* | |
1679 | * Stop if extent has been truncated or | |
1680 | * hole-punched, and is now completely | |
1681 | * empty. | |
1682 | */ | |
1683 | if (index == start) { | |
1684 | if (!xas_next_entry(&xas, end - 1)) { | |
1685 | result = SCAN_TRUNCATED; | |
1686 | goto xa_locked; | |
1687 | } | |
1688 | xas_set(&xas, index); | |
1689 | } | |
1690 | if (!shmem_charge(mapping->host, 1)) { | |
1691 | result = SCAN_FAIL; | |
042a3082 | 1692 | goto xa_locked; |
701270fa | 1693 | } |
99cb0dbd SL |
1694 | xas_store(&xas, new_page); |
1695 | nr_none++; | |
1696 | continue; | |
701270fa | 1697 | } |
99cb0dbd SL |
1698 | |
1699 | if (xa_is_value(page) || !PageUptodate(page)) { | |
1700 | xas_unlock_irq(&xas); | |
1701 | /* swap in or instantiate fallocated page */ | |
1702 | if (shmem_getpage(mapping->host, index, &page, | |
1703 | SGP_NOHUGE)) { | |
1704 | result = SCAN_FAIL; | |
1705 | goto xa_unlocked; | |
1706 | } | |
1707 | } else if (trylock_page(page)) { | |
1708 | get_page(page); | |
1709 | xas_unlock_irq(&xas); | |
1710 | } else { | |
1711 | result = SCAN_PAGE_LOCK; | |
042a3082 | 1712 | goto xa_locked; |
77da9389 | 1713 | } |
99cb0dbd SL |
1714 | } else { /* !is_shmem */ |
1715 | if (!page || xa_is_value(page)) { | |
1716 | xas_unlock_irq(&xas); | |
1717 | page_cache_sync_readahead(mapping, &file->f_ra, | |
1718 | file, index, | |
1719 | PAGE_SIZE); | |
1720 | /* drain pagevecs to help isolate_lru_page() */ | |
1721 | lru_add_drain(); | |
1722 | page = find_lock_page(mapping, index); | |
1723 | if (unlikely(page == NULL)) { | |
1724 | result = SCAN_FAIL; | |
1725 | goto xa_unlocked; | |
1726 | } | |
75f36069 SL |
1727 | } else if (PageDirty(page)) { |
1728 | /* | |
1729 | * khugepaged only works on read-only fd, | |
1730 | * so this page is dirty because it hasn't | |
1731 | * been flushed since first write. There | |
1732 | * won't be new dirty pages. | |
1733 | * | |
1734 | * Trigger async flush here and hope the | |
1735 | * writeback is done when khugepaged | |
1736 | * revisits this page. | |
1737 | * | |
1738 | * This is a one-off situation. We are not | |
1739 | * forcing writeback in loop. | |
1740 | */ | |
1741 | xas_unlock_irq(&xas); | |
1742 | filemap_flush(mapping); | |
1743 | result = SCAN_FAIL; | |
1744 | goto xa_unlocked; | |
99cb0dbd SL |
1745 | } else if (trylock_page(page)) { |
1746 | get_page(page); | |
1747 | xas_unlock_irq(&xas); | |
1748 | } else { | |
1749 | result = SCAN_PAGE_LOCK; | |
1750 | goto xa_locked; | |
f3f0e1d2 | 1751 | } |
f3f0e1d2 KS |
1752 | } |
1753 | ||
1754 | /* | |
b93b0163 | 1755 | * The page must be locked, so we can drop the i_pages lock |
f3f0e1d2 KS |
1756 | * without racing with truncate. |
1757 | */ | |
1758 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
4655e5e5 SL |
1759 | |
1760 | /* make sure the page is up to date */ | |
1761 | if (unlikely(!PageUptodate(page))) { | |
1762 | result = SCAN_FAIL; | |
1763 | goto out_unlock; | |
1764 | } | |
06a5e126 HD |
1765 | |
1766 | /* | |
1767 | * If file was truncated then extended, or hole-punched, before | |
1768 | * we locked the first page, then a THP might be there already. | |
1769 | */ | |
1770 | if (PageTransCompound(page)) { | |
1771 | result = SCAN_PAGE_COMPOUND; | |
1772 | goto out_unlock; | |
1773 | } | |
f3f0e1d2 KS |
1774 | |
1775 | if (page_mapping(page) != mapping) { | |
1776 | result = SCAN_TRUNCATED; | |
1777 | goto out_unlock; | |
1778 | } | |
f3f0e1d2 | 1779 | |
4655e5e5 SL |
1780 | if (!is_shmem && PageDirty(page)) { |
1781 | /* | |
1782 | * khugepaged only works on read-only fd, so this | |
1783 | * page is dirty because it hasn't been flushed | |
1784 | * since first write. | |
1785 | */ | |
1786 | result = SCAN_FAIL; | |
1787 | goto out_unlock; | |
1788 | } | |
1789 | ||
f3f0e1d2 KS |
1790 | if (isolate_lru_page(page)) { |
1791 | result = SCAN_DEL_PAGE_LRU; | |
042a3082 | 1792 | goto out_unlock; |
f3f0e1d2 KS |
1793 | } |
1794 | ||
99cb0dbd SL |
1795 | if (page_has_private(page) && |
1796 | !try_to_release_page(page, GFP_KERNEL)) { | |
1797 | result = SCAN_PAGE_HAS_PRIVATE; | |
2f33a706 | 1798 | putback_lru_page(page); |
99cb0dbd SL |
1799 | goto out_unlock; |
1800 | } | |
1801 | ||
f3f0e1d2 | 1802 | if (page_mapped(page)) |
977fbdcd | 1803 | unmap_mapping_pages(mapping, index, 1, false); |
f3f0e1d2 | 1804 | |
77da9389 MW |
1805 | xas_lock_irq(&xas); |
1806 | xas_set(&xas, index); | |
f3f0e1d2 | 1807 | |
77da9389 | 1808 | VM_BUG_ON_PAGE(page != xas_load(&xas), page); |
f3f0e1d2 KS |
1809 | VM_BUG_ON_PAGE(page_mapped(page), page); |
1810 | ||
1811 | /* | |
1812 | * The page is expected to have page_count() == 3: | |
1813 | * - we hold a pin on it; | |
77da9389 | 1814 | * - one reference from page cache; |
f3f0e1d2 KS |
1815 | * - one from isolate_lru_page; |
1816 | */ | |
1817 | if (!page_ref_freeze(page, 3)) { | |
1818 | result = SCAN_PAGE_COUNT; | |
042a3082 HD |
1819 | xas_unlock_irq(&xas); |
1820 | putback_lru_page(page); | |
1821 | goto out_unlock; | |
f3f0e1d2 KS |
1822 | } |
1823 | ||
1824 | /* | |
1825 | * Add the page to the list to be able to undo the collapse if | |
1826 | * something go wrong. | |
1827 | */ | |
1828 | list_add_tail(&page->lru, &pagelist); | |
1829 | ||
1830 | /* Finally, replace with the new page. */ | |
4101196b | 1831 | xas_store(&xas, new_page); |
f3f0e1d2 | 1832 | continue; |
f3f0e1d2 KS |
1833 | out_unlock: |
1834 | unlock_page(page); | |
1835 | put_page(page); | |
042a3082 | 1836 | goto xa_unlocked; |
f3f0e1d2 KS |
1837 | } |
1838 | ||
99cb0dbd SL |
1839 | if (is_shmem) |
1840 | __inc_node_page_state(new_page, NR_SHMEM_THPS); | |
09d91cda | 1841 | else { |
99cb0dbd | 1842 | __inc_node_page_state(new_page, NR_FILE_THPS); |
09d91cda SL |
1843 | filemap_nr_thps_inc(mapping); |
1844 | } | |
99cb0dbd | 1845 | |
042a3082 | 1846 | if (nr_none) { |
0d1c2072 JW |
1847 | struct lruvec *lruvec; |
1848 | /* | |
1849 | * XXX: We have started try_charge and pinned the | |
1850 | * memcg, but the page isn't committed yet so we | |
1851 | * cannot use mod_lruvec_page_state(). This hackery | |
1852 | * will be cleaned up when remove the page->mapping | |
1853 | * dependency from memcg and fully charge above. | |
1854 | */ | |
1855 | lruvec = mem_cgroup_lruvec(memcg, page_pgdat(new_page)); | |
1856 | __mod_lruvec_state(lruvec, NR_FILE_PAGES, nr_none); | |
99cb0dbd | 1857 | if (is_shmem) |
0d1c2072 | 1858 | __mod_lruvec_state(lruvec, NR_SHMEM, nr_none); |
042a3082 HD |
1859 | } |
1860 | ||
1861 | xa_locked: | |
1862 | xas_unlock_irq(&xas); | |
77da9389 | 1863 | xa_unlocked: |
042a3082 | 1864 | |
f3f0e1d2 | 1865 | if (result == SCAN_SUCCEED) { |
77da9389 | 1866 | struct page *page, *tmp; |
f3f0e1d2 KS |
1867 | |
1868 | /* | |
77da9389 MW |
1869 | * Replacing old pages with new one has succeeded, now we |
1870 | * need to copy the content and free the old pages. | |
f3f0e1d2 | 1871 | */ |
2af8ff29 | 1872 | index = start; |
f3f0e1d2 | 1873 | list_for_each_entry_safe(page, tmp, &pagelist, lru) { |
2af8ff29 HD |
1874 | while (index < page->index) { |
1875 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1876 | index++; | |
1877 | } | |
f3f0e1d2 KS |
1878 | copy_highpage(new_page + (page->index % HPAGE_PMD_NR), |
1879 | page); | |
1880 | list_del(&page->lru); | |
f3f0e1d2 | 1881 | page->mapping = NULL; |
042a3082 | 1882 | page_ref_unfreeze(page, 1); |
f3f0e1d2 KS |
1883 | ClearPageActive(page); |
1884 | ClearPageUnevictable(page); | |
042a3082 | 1885 | unlock_page(page); |
f3f0e1d2 | 1886 | put_page(page); |
2af8ff29 HD |
1887 | index++; |
1888 | } | |
1889 | while (index < end) { | |
1890 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1891 | index++; | |
f3f0e1d2 KS |
1892 | } |
1893 | ||
f3f0e1d2 | 1894 | SetPageUptodate(new_page); |
87c460a0 | 1895 | page_ref_add(new_page, HPAGE_PMD_NR - 1); |
3fba69a5 | 1896 | mem_cgroup_commit_charge(new_page, memcg, false); |
99cb0dbd SL |
1897 | |
1898 | if (is_shmem) { | |
1899 | set_page_dirty(new_page); | |
1900 | lru_cache_add_anon(new_page); | |
1901 | } else { | |
1902 | lru_cache_add_file(new_page); | |
1903 | } | |
1ff9e6e1 | 1904 | count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1); |
f3f0e1d2 | 1905 | |
042a3082 HD |
1906 | /* |
1907 | * Remove pte page tables, so we can re-fault the page as huge. | |
1908 | */ | |
1909 | retract_page_tables(mapping, start); | |
f3f0e1d2 | 1910 | *hpage = NULL; |
87aa7529 YS |
1911 | |
1912 | khugepaged_pages_collapsed++; | |
f3f0e1d2 | 1913 | } else { |
77da9389 | 1914 | struct page *page; |
aaa52e34 | 1915 | |
77da9389 | 1916 | /* Something went wrong: roll back page cache changes */ |
77da9389 | 1917 | xas_lock_irq(&xas); |
aaa52e34 | 1918 | mapping->nrpages -= nr_none; |
99cb0dbd SL |
1919 | |
1920 | if (is_shmem) | |
1921 | shmem_uncharge(mapping->host, nr_none); | |
aaa52e34 | 1922 | |
77da9389 MW |
1923 | xas_set(&xas, start); |
1924 | xas_for_each(&xas, page, end - 1) { | |
f3f0e1d2 KS |
1925 | page = list_first_entry_or_null(&pagelist, |
1926 | struct page, lru); | |
77da9389 | 1927 | if (!page || xas.xa_index < page->index) { |
f3f0e1d2 KS |
1928 | if (!nr_none) |
1929 | break; | |
f3f0e1d2 | 1930 | nr_none--; |
59749e6c | 1931 | /* Put holes back where they were */ |
77da9389 | 1932 | xas_store(&xas, NULL); |
f3f0e1d2 KS |
1933 | continue; |
1934 | } | |
1935 | ||
77da9389 | 1936 | VM_BUG_ON_PAGE(page->index != xas.xa_index, page); |
f3f0e1d2 KS |
1937 | |
1938 | /* Unfreeze the page. */ | |
1939 | list_del(&page->lru); | |
1940 | page_ref_unfreeze(page, 2); | |
77da9389 MW |
1941 | xas_store(&xas, page); |
1942 | xas_pause(&xas); | |
1943 | xas_unlock_irq(&xas); | |
f3f0e1d2 | 1944 | unlock_page(page); |
042a3082 | 1945 | putback_lru_page(page); |
77da9389 | 1946 | xas_lock_irq(&xas); |
f3f0e1d2 KS |
1947 | } |
1948 | VM_BUG_ON(nr_none); | |
77da9389 | 1949 | xas_unlock_irq(&xas); |
f3f0e1d2 | 1950 | |
3fba69a5 | 1951 | mem_cgroup_cancel_charge(new_page, memcg); |
f3f0e1d2 KS |
1952 | new_page->mapping = NULL; |
1953 | } | |
042a3082 HD |
1954 | |
1955 | unlock_page(new_page); | |
f3f0e1d2 KS |
1956 | out: |
1957 | VM_BUG_ON(!list_empty(&pagelist)); | |
1958 | /* TODO: tracepoints */ | |
1959 | } | |
1960 | ||
579c571e SL |
1961 | static void khugepaged_scan_file(struct mm_struct *mm, |
1962 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
1963 | { |
1964 | struct page *page = NULL; | |
579c571e | 1965 | struct address_space *mapping = file->f_mapping; |
85b392db | 1966 | XA_STATE(xas, &mapping->i_pages, start); |
f3f0e1d2 KS |
1967 | int present, swap; |
1968 | int node = NUMA_NO_NODE; | |
1969 | int result = SCAN_SUCCEED; | |
1970 | ||
1971 | present = 0; | |
1972 | swap = 0; | |
1973 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1974 | rcu_read_lock(); | |
85b392db MW |
1975 | xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) { |
1976 | if (xas_retry(&xas, page)) | |
f3f0e1d2 | 1977 | continue; |
f3f0e1d2 | 1978 | |
85b392db | 1979 | if (xa_is_value(page)) { |
f3f0e1d2 KS |
1980 | if (++swap > khugepaged_max_ptes_swap) { |
1981 | result = SCAN_EXCEED_SWAP_PTE; | |
1982 | break; | |
1983 | } | |
1984 | continue; | |
1985 | } | |
1986 | ||
1987 | if (PageTransCompound(page)) { | |
1988 | result = SCAN_PAGE_COMPOUND; | |
1989 | break; | |
1990 | } | |
1991 | ||
1992 | node = page_to_nid(page); | |
1993 | if (khugepaged_scan_abort(node)) { | |
1994 | result = SCAN_SCAN_ABORT; | |
1995 | break; | |
1996 | } | |
1997 | khugepaged_node_load[node]++; | |
1998 | ||
1999 | if (!PageLRU(page)) { | |
2000 | result = SCAN_PAGE_LRU; | |
2001 | break; | |
2002 | } | |
2003 | ||
99cb0dbd SL |
2004 | if (page_count(page) != |
2005 | 1 + page_mapcount(page) + page_has_private(page)) { | |
f3f0e1d2 KS |
2006 | result = SCAN_PAGE_COUNT; |
2007 | break; | |
2008 | } | |
2009 | ||
2010 | /* | |
2011 | * We probably should check if the page is referenced here, but | |
2012 | * nobody would transfer pte_young() to PageReferenced() for us. | |
2013 | * And rmap walk here is just too costly... | |
2014 | */ | |
2015 | ||
2016 | present++; | |
2017 | ||
2018 | if (need_resched()) { | |
85b392db | 2019 | xas_pause(&xas); |
f3f0e1d2 | 2020 | cond_resched_rcu(); |
f3f0e1d2 KS |
2021 | } |
2022 | } | |
2023 | rcu_read_unlock(); | |
2024 | ||
2025 | if (result == SCAN_SUCCEED) { | |
2026 | if (present < HPAGE_PMD_NR - khugepaged_max_ptes_none) { | |
2027 | result = SCAN_EXCEED_NONE_PTE; | |
2028 | } else { | |
2029 | node = khugepaged_find_target_node(); | |
579c571e | 2030 | collapse_file(mm, file, start, hpage, node); |
f3f0e1d2 KS |
2031 | } |
2032 | } | |
2033 | ||
2034 | /* TODO: tracepoints */ | |
2035 | } | |
2036 | #else | |
579c571e SL |
2037 | static void khugepaged_scan_file(struct mm_struct *mm, |
2038 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
2039 | { |
2040 | BUILD_BUG(); | |
2041 | } | |
27e1f827 SL |
2042 | |
2043 | static int khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) | |
2044 | { | |
2045 | return 0; | |
2046 | } | |
f3f0e1d2 KS |
2047 | #endif |
2048 | ||
b46e756f KS |
2049 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, |
2050 | struct page **hpage) | |
2051 | __releases(&khugepaged_mm_lock) | |
2052 | __acquires(&khugepaged_mm_lock) | |
2053 | { | |
2054 | struct mm_slot *mm_slot; | |
2055 | struct mm_struct *mm; | |
2056 | struct vm_area_struct *vma; | |
2057 | int progress = 0; | |
2058 | ||
2059 | VM_BUG_ON(!pages); | |
35f3aa39 | 2060 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
2061 | |
2062 | if (khugepaged_scan.mm_slot) | |
2063 | mm_slot = khugepaged_scan.mm_slot; | |
2064 | else { | |
2065 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2066 | struct mm_slot, mm_node); | |
2067 | khugepaged_scan.address = 0; | |
2068 | khugepaged_scan.mm_slot = mm_slot; | |
2069 | } | |
2070 | spin_unlock(&khugepaged_mm_lock); | |
27e1f827 | 2071 | khugepaged_collapse_pte_mapped_thps(mm_slot); |
b46e756f KS |
2072 | |
2073 | mm = mm_slot->mm; | |
3b454ad3 YS |
2074 | /* |
2075 | * Don't wait for semaphore (to avoid long wait times). Just move to | |
2076 | * the next mm on the list. | |
2077 | */ | |
2078 | vma = NULL; | |
2079 | if (unlikely(!down_read_trylock(&mm->mmap_sem))) | |
2080 | goto breakouterloop_mmap_sem; | |
2081 | if (likely(!khugepaged_test_exit(mm))) | |
b46e756f KS |
2082 | vma = find_vma(mm, khugepaged_scan.address); |
2083 | ||
2084 | progress++; | |
2085 | for (; vma; vma = vma->vm_next) { | |
2086 | unsigned long hstart, hend; | |
2087 | ||
2088 | cond_resched(); | |
2089 | if (unlikely(khugepaged_test_exit(mm))) { | |
2090 | progress++; | |
2091 | break; | |
2092 | } | |
50f8b92f | 2093 | if (!hugepage_vma_check(vma, vma->vm_flags)) { |
b46e756f KS |
2094 | skip: |
2095 | progress++; | |
2096 | continue; | |
2097 | } | |
2098 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2099 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2100 | if (hstart >= hend) | |
2101 | goto skip; | |
2102 | if (khugepaged_scan.address > hend) | |
2103 | goto skip; | |
2104 | if (khugepaged_scan.address < hstart) | |
2105 | khugepaged_scan.address = hstart; | |
2106 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); | |
396bcc52 MWO |
2107 | if (shmem_file(vma->vm_file) && !shmem_huge_enabled(vma)) |
2108 | goto skip; | |
b46e756f KS |
2109 | |
2110 | while (khugepaged_scan.address < hend) { | |
2111 | int ret; | |
2112 | cond_resched(); | |
2113 | if (unlikely(khugepaged_test_exit(mm))) | |
2114 | goto breakouterloop; | |
2115 | ||
2116 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2117 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2118 | hend); | |
99cb0dbd | 2119 | if (IS_ENABLED(CONFIG_SHMEM) && vma->vm_file) { |
396bcc52 | 2120 | struct file *file = get_file(vma->vm_file); |
f3f0e1d2 KS |
2121 | pgoff_t pgoff = linear_page_index(vma, |
2122 | khugepaged_scan.address); | |
99cb0dbd | 2123 | |
f3f0e1d2 KS |
2124 | up_read(&mm->mmap_sem); |
2125 | ret = 1; | |
579c571e | 2126 | khugepaged_scan_file(mm, file, pgoff, hpage); |
f3f0e1d2 KS |
2127 | fput(file); |
2128 | } else { | |
2129 | ret = khugepaged_scan_pmd(mm, vma, | |
2130 | khugepaged_scan.address, | |
2131 | hpage); | |
2132 | } | |
b46e756f KS |
2133 | /* move to next address */ |
2134 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2135 | progress += HPAGE_PMD_NR; | |
2136 | if (ret) | |
2137 | /* we released mmap_sem so break loop */ | |
2138 | goto breakouterloop_mmap_sem; | |
2139 | if (progress >= pages) | |
2140 | goto breakouterloop; | |
2141 | } | |
2142 | } | |
2143 | breakouterloop: | |
2144 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2145 | breakouterloop_mmap_sem: | |
2146 | ||
2147 | spin_lock(&khugepaged_mm_lock); | |
2148 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); | |
2149 | /* | |
2150 | * Release the current mm_slot if this mm is about to die, or | |
2151 | * if we scanned all vmas of this mm. | |
2152 | */ | |
2153 | if (khugepaged_test_exit(mm) || !vma) { | |
2154 | /* | |
2155 | * Make sure that if mm_users is reaching zero while | |
2156 | * khugepaged runs here, khugepaged_exit will find | |
2157 | * mm_slot not pointing to the exiting mm. | |
2158 | */ | |
2159 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2160 | khugepaged_scan.mm_slot = list_entry( | |
2161 | mm_slot->mm_node.next, | |
2162 | struct mm_slot, mm_node); | |
2163 | khugepaged_scan.address = 0; | |
2164 | } else { | |
2165 | khugepaged_scan.mm_slot = NULL; | |
2166 | khugepaged_full_scans++; | |
2167 | } | |
2168 | ||
2169 | collect_mm_slot(mm_slot); | |
2170 | } | |
2171 | ||
2172 | return progress; | |
2173 | } | |
2174 | ||
2175 | static int khugepaged_has_work(void) | |
2176 | { | |
2177 | return !list_empty(&khugepaged_scan.mm_head) && | |
2178 | khugepaged_enabled(); | |
2179 | } | |
2180 | ||
2181 | static int khugepaged_wait_event(void) | |
2182 | { | |
2183 | return !list_empty(&khugepaged_scan.mm_head) || | |
2184 | kthread_should_stop(); | |
2185 | } | |
2186 | ||
2187 | static void khugepaged_do_scan(void) | |
2188 | { | |
2189 | struct page *hpage = NULL; | |
2190 | unsigned int progress = 0, pass_through_head = 0; | |
2191 | unsigned int pages = khugepaged_pages_to_scan; | |
2192 | bool wait = true; | |
2193 | ||
2194 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2195 | ||
a980df33 KS |
2196 | lru_add_drain_all(); |
2197 | ||
b46e756f KS |
2198 | while (progress < pages) { |
2199 | if (!khugepaged_prealloc_page(&hpage, &wait)) | |
2200 | break; | |
2201 | ||
2202 | cond_resched(); | |
2203 | ||
2204 | if (unlikely(kthread_should_stop() || try_to_freeze())) | |
2205 | break; | |
2206 | ||
2207 | spin_lock(&khugepaged_mm_lock); | |
2208 | if (!khugepaged_scan.mm_slot) | |
2209 | pass_through_head++; | |
2210 | if (khugepaged_has_work() && | |
2211 | pass_through_head < 2) | |
2212 | progress += khugepaged_scan_mm_slot(pages - progress, | |
2213 | &hpage); | |
2214 | else | |
2215 | progress = pages; | |
2216 | spin_unlock(&khugepaged_mm_lock); | |
2217 | } | |
2218 | ||
2219 | if (!IS_ERR_OR_NULL(hpage)) | |
2220 | put_page(hpage); | |
2221 | } | |
2222 | ||
2223 | static bool khugepaged_should_wakeup(void) | |
2224 | { | |
2225 | return kthread_should_stop() || | |
2226 | time_after_eq(jiffies, khugepaged_sleep_expire); | |
2227 | } | |
2228 | ||
2229 | static void khugepaged_wait_work(void) | |
2230 | { | |
2231 | if (khugepaged_has_work()) { | |
2232 | const unsigned long scan_sleep_jiffies = | |
2233 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs); | |
2234 | ||
2235 | if (!scan_sleep_jiffies) | |
2236 | return; | |
2237 | ||
2238 | khugepaged_sleep_expire = jiffies + scan_sleep_jiffies; | |
2239 | wait_event_freezable_timeout(khugepaged_wait, | |
2240 | khugepaged_should_wakeup(), | |
2241 | scan_sleep_jiffies); | |
2242 | return; | |
2243 | } | |
2244 | ||
2245 | if (khugepaged_enabled()) | |
2246 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2247 | } | |
2248 | ||
2249 | static int khugepaged(void *none) | |
2250 | { | |
2251 | struct mm_slot *mm_slot; | |
2252 | ||
2253 | set_freezable(); | |
2254 | set_user_nice(current, MAX_NICE); | |
2255 | ||
2256 | while (!kthread_should_stop()) { | |
2257 | khugepaged_do_scan(); | |
2258 | khugepaged_wait_work(); | |
2259 | } | |
2260 | ||
2261 | spin_lock(&khugepaged_mm_lock); | |
2262 | mm_slot = khugepaged_scan.mm_slot; | |
2263 | khugepaged_scan.mm_slot = NULL; | |
2264 | if (mm_slot) | |
2265 | collect_mm_slot(mm_slot); | |
2266 | spin_unlock(&khugepaged_mm_lock); | |
2267 | return 0; | |
2268 | } | |
2269 | ||
2270 | static void set_recommended_min_free_kbytes(void) | |
2271 | { | |
2272 | struct zone *zone; | |
2273 | int nr_zones = 0; | |
2274 | unsigned long recommended_min; | |
2275 | ||
b7d349c7 JK |
2276 | for_each_populated_zone(zone) { |
2277 | /* | |
2278 | * We don't need to worry about fragmentation of | |
2279 | * ZONE_MOVABLE since it only has movable pages. | |
2280 | */ | |
2281 | if (zone_idx(zone) > gfp_zone(GFP_USER)) | |
2282 | continue; | |
2283 | ||
b46e756f | 2284 | nr_zones++; |
b7d349c7 | 2285 | } |
b46e756f KS |
2286 | |
2287 | /* Ensure 2 pageblocks are free to assist fragmentation avoidance */ | |
2288 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
2289 | ||
2290 | /* | |
2291 | * Make sure that on average at least two pageblocks are almost free | |
2292 | * of another type, one for a migratetype to fall back to and a | |
2293 | * second to avoid subsequent fallbacks of other types There are 3 | |
2294 | * MIGRATE_TYPES we care about. | |
2295 | */ | |
2296 | recommended_min += pageblock_nr_pages * nr_zones * | |
2297 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
2298 | ||
2299 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
2300 | recommended_min = min(recommended_min, | |
2301 | (unsigned long) nr_free_buffer_pages() / 20); | |
2302 | recommended_min <<= (PAGE_SHIFT-10); | |
2303 | ||
2304 | if (recommended_min > min_free_kbytes) { | |
2305 | if (user_min_free_kbytes >= 0) | |
2306 | pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n", | |
2307 | min_free_kbytes, recommended_min); | |
2308 | ||
2309 | min_free_kbytes = recommended_min; | |
2310 | } | |
2311 | setup_per_zone_wmarks(); | |
2312 | } | |
2313 | ||
2314 | int start_stop_khugepaged(void) | |
2315 | { | |
2316 | static struct task_struct *khugepaged_thread __read_mostly; | |
2317 | static DEFINE_MUTEX(khugepaged_mutex); | |
2318 | int err = 0; | |
2319 | ||
2320 | mutex_lock(&khugepaged_mutex); | |
2321 | if (khugepaged_enabled()) { | |
2322 | if (!khugepaged_thread) | |
2323 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
2324 | "khugepaged"); | |
2325 | if (IS_ERR(khugepaged_thread)) { | |
2326 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); | |
2327 | err = PTR_ERR(khugepaged_thread); | |
2328 | khugepaged_thread = NULL; | |
2329 | goto fail; | |
2330 | } | |
2331 | ||
2332 | if (!list_empty(&khugepaged_scan.mm_head)) | |
2333 | wake_up_interruptible(&khugepaged_wait); | |
2334 | ||
2335 | set_recommended_min_free_kbytes(); | |
2336 | } else if (khugepaged_thread) { | |
2337 | kthread_stop(khugepaged_thread); | |
2338 | khugepaged_thread = NULL; | |
2339 | } | |
2340 | fail: | |
2341 | mutex_unlock(&khugepaged_mutex); | |
2342 | return err; | |
2343 | } |