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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, | |
31 | SCAN_PTE_NON_PRESENT, | |
32 | SCAN_PAGE_RO, | |
0db501f7 | 33 | SCAN_LACK_REFERENCED_PAGE, |
b46e756f KS |
34 | SCAN_PAGE_NULL, |
35 | SCAN_SCAN_ABORT, | |
36 | SCAN_PAGE_COUNT, | |
37 | SCAN_PAGE_LRU, | |
38 | SCAN_PAGE_LOCK, | |
39 | SCAN_PAGE_ANON, | |
40 | SCAN_PAGE_COMPOUND, | |
41 | SCAN_ANY_PROCESS, | |
42 | SCAN_VMA_NULL, | |
43 | SCAN_VMA_CHECK, | |
44 | SCAN_ADDRESS_RANGE, | |
45 | SCAN_SWAP_CACHE_PAGE, | |
46 | SCAN_DEL_PAGE_LRU, | |
47 | SCAN_ALLOC_HUGE_PAGE_FAIL, | |
48 | SCAN_CGROUP_CHARGE_FAIL, | |
f3f0e1d2 KS |
49 | SCAN_EXCEED_SWAP_PTE, |
50 | SCAN_TRUNCATED, | |
99cb0dbd | 51 | SCAN_PAGE_HAS_PRIVATE, |
b46e756f KS |
52 | }; |
53 | ||
54 | #define CREATE_TRACE_POINTS | |
55 | #include <trace/events/huge_memory.h> | |
56 | ||
e2c01fd0 VB |
57 | static struct task_struct *khugepaged_thread __read_mostly; |
58 | static DEFINE_MUTEX(khugepaged_mutex); | |
59 | ||
b46e756f KS |
60 | /* default scan 8*512 pte (or vmas) every 30 second */ |
61 | static unsigned int khugepaged_pages_to_scan __read_mostly; | |
62 | static unsigned int khugepaged_pages_collapsed; | |
63 | static unsigned int khugepaged_full_scans; | |
64 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
65 | /* during fragmentation poll the hugepage allocator once every minute */ | |
66 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
67 | static unsigned long khugepaged_sleep_expire; | |
68 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
69 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
70 | /* | |
71 | * default collapse hugepages if there is at least one pte mapped like | |
72 | * it would have happened if the vma was large enough during page | |
73 | * fault. | |
74 | */ | |
75 | static unsigned int khugepaged_max_ptes_none __read_mostly; | |
76 | static unsigned int khugepaged_max_ptes_swap __read_mostly; | |
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 | ||
296 | static struct attribute *khugepaged_attr[] = { | |
297 | &khugepaged_defrag_attr.attr, | |
298 | &khugepaged_max_ptes_none_attr.attr, | |
299 | &pages_to_scan_attr.attr, | |
300 | &pages_collapsed_attr.attr, | |
301 | &full_scans_attr.attr, | |
302 | &scan_sleep_millisecs_attr.attr, | |
303 | &alloc_sleep_millisecs_attr.attr, | |
304 | &khugepaged_max_ptes_swap_attr.attr, | |
305 | NULL, | |
306 | }; | |
307 | ||
308 | struct attribute_group khugepaged_attr_group = { | |
309 | .attrs = khugepaged_attr, | |
310 | .name = "khugepaged", | |
311 | }; | |
e1465d12 | 312 | #endif /* CONFIG_SYSFS */ |
b46e756f | 313 | |
f3f0e1d2 | 314 | #define VM_NO_KHUGEPAGED (VM_SPECIAL | VM_HUGETLB) |
b46e756f KS |
315 | |
316 | int hugepage_madvise(struct vm_area_struct *vma, | |
317 | unsigned long *vm_flags, int advice) | |
318 | { | |
319 | switch (advice) { | |
320 | case MADV_HUGEPAGE: | |
321 | #ifdef CONFIG_S390 | |
322 | /* | |
323 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
324 | * can't handle this properly after s390_enable_sie, so we simply | |
325 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
326 | */ | |
327 | if (mm_has_pgste(vma->vm_mm)) | |
328 | return 0; | |
329 | #endif | |
330 | *vm_flags &= ~VM_NOHUGEPAGE; | |
331 | *vm_flags |= VM_HUGEPAGE; | |
332 | /* | |
333 | * If the vma become good for khugepaged to scan, | |
334 | * register it here without waiting a page fault that | |
335 | * may not happen any time soon. | |
336 | */ | |
337 | if (!(*vm_flags & VM_NO_KHUGEPAGED) && | |
338 | khugepaged_enter_vma_merge(vma, *vm_flags)) | |
339 | return -ENOMEM; | |
340 | break; | |
341 | case MADV_NOHUGEPAGE: | |
342 | *vm_flags &= ~VM_HUGEPAGE; | |
343 | *vm_flags |= VM_NOHUGEPAGE; | |
344 | /* | |
345 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
346 | * this vma even if we leave the mm registered in khugepaged if | |
347 | * it got registered before VM_NOHUGEPAGE was set. | |
348 | */ | |
349 | break; | |
350 | } | |
351 | ||
352 | return 0; | |
353 | } | |
354 | ||
355 | int __init khugepaged_init(void) | |
356 | { | |
357 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
358 | sizeof(struct mm_slot), | |
359 | __alignof__(struct mm_slot), 0, NULL); | |
360 | if (!mm_slot_cache) | |
361 | return -ENOMEM; | |
362 | ||
363 | khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; | |
364 | khugepaged_max_ptes_none = HPAGE_PMD_NR - 1; | |
365 | khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8; | |
366 | ||
367 | return 0; | |
368 | } | |
369 | ||
370 | void __init khugepaged_destroy(void) | |
371 | { | |
372 | kmem_cache_destroy(mm_slot_cache); | |
373 | } | |
374 | ||
375 | static inline struct mm_slot *alloc_mm_slot(void) | |
376 | { | |
377 | if (!mm_slot_cache) /* initialization failed */ | |
378 | return NULL; | |
379 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
380 | } | |
381 | ||
382 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
383 | { | |
384 | kmem_cache_free(mm_slot_cache, mm_slot); | |
385 | } | |
386 | ||
387 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
388 | { | |
389 | struct mm_slot *mm_slot; | |
390 | ||
391 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) | |
392 | if (mm == mm_slot->mm) | |
393 | return mm_slot; | |
394 | ||
395 | return NULL; | |
396 | } | |
397 | ||
398 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
399 | struct mm_slot *mm_slot) | |
400 | { | |
401 | mm_slot->mm = mm; | |
402 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); | |
403 | } | |
404 | ||
405 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
406 | { | |
05592859 | 407 | return atomic_read(&mm->mm_users) == 0 || !mmget_still_valid(mm); |
b46e756f KS |
408 | } |
409 | ||
50f8b92f SL |
410 | static bool hugepage_vma_check(struct vm_area_struct *vma, |
411 | unsigned long vm_flags) | |
c2231020 | 412 | { |
50f8b92f SL |
413 | if ((!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || |
414 | (vm_flags & VM_NOHUGEPAGE) || | |
c2231020 YS |
415 | test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) |
416 | return false; | |
99cb0dbd SL |
417 | |
418 | if (shmem_file(vma->vm_file) || | |
419 | (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && | |
420 | vma->vm_file && | |
421 | (vm_flags & VM_DENYWRITE))) { | |
c2231020 YS |
422 | if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) |
423 | return false; | |
424 | return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, | |
425 | HPAGE_PMD_NR); | |
426 | } | |
427 | if (!vma->anon_vma || vma->vm_ops) | |
428 | return false; | |
429 | if (is_vma_temporary_stack(vma)) | |
430 | return false; | |
50f8b92f | 431 | return !(vm_flags & VM_NO_KHUGEPAGED); |
c2231020 YS |
432 | } |
433 | ||
b46e756f KS |
434 | int __khugepaged_enter(struct mm_struct *mm) |
435 | { | |
436 | struct mm_slot *mm_slot; | |
437 | int wakeup; | |
438 | ||
439 | mm_slot = alloc_mm_slot(); | |
440 | if (!mm_slot) | |
441 | return -ENOMEM; | |
442 | ||
443 | /* __khugepaged_exit() must not run from under us */ | |
db919cd0 | 444 | VM_BUG_ON_MM(atomic_read(&mm->mm_users) == 0, mm); |
b46e756f KS |
445 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { |
446 | free_mm_slot(mm_slot); | |
447 | return 0; | |
448 | } | |
449 | ||
450 | spin_lock(&khugepaged_mm_lock); | |
451 | insert_to_mm_slots_hash(mm, mm_slot); | |
452 | /* | |
453 | * Insert just behind the scanning cursor, to let the area settle | |
454 | * down a little. | |
455 | */ | |
456 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
457 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
458 | spin_unlock(&khugepaged_mm_lock); | |
459 | ||
f1f10076 | 460 | mmgrab(mm); |
b46e756f KS |
461 | if (wakeup) |
462 | wake_up_interruptible(&khugepaged_wait); | |
463 | ||
464 | return 0; | |
465 | } | |
466 | ||
467 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, | |
468 | unsigned long vm_flags) | |
469 | { | |
470 | unsigned long hstart, hend; | |
c2231020 YS |
471 | |
472 | /* | |
99cb0dbd SL |
473 | * khugepaged only supports read-only files for non-shmem files. |
474 | * khugepaged does not yet work on special mappings. And | |
475 | * file-private shmem THP is not supported. | |
c2231020 | 476 | */ |
50f8b92f | 477 | if (!hugepage_vma_check(vma, vm_flags)) |
b46e756f | 478 | return 0; |
c2231020 | 479 | |
b46e756f KS |
480 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
481 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
482 | if (hstart < hend) | |
483 | return khugepaged_enter(vma, vm_flags); | |
484 | return 0; | |
485 | } | |
486 | ||
487 | void __khugepaged_exit(struct mm_struct *mm) | |
488 | { | |
489 | struct mm_slot *mm_slot; | |
490 | int free = 0; | |
491 | ||
492 | spin_lock(&khugepaged_mm_lock); | |
493 | mm_slot = get_mm_slot(mm); | |
494 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
495 | hash_del(&mm_slot->hash); | |
496 | list_del(&mm_slot->mm_node); | |
497 | free = 1; | |
498 | } | |
499 | spin_unlock(&khugepaged_mm_lock); | |
500 | ||
501 | if (free) { | |
502 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
503 | free_mm_slot(mm_slot); | |
504 | mmdrop(mm); | |
505 | } else if (mm_slot) { | |
506 | /* | |
507 | * This is required to serialize against | |
508 | * khugepaged_test_exit() (which is guaranteed to run | |
509 | * under mmap sem read mode). Stop here (after we | |
510 | * return all pagetables will be destroyed) until | |
511 | * khugepaged has finished working on the pagetables | |
512 | * under the mmap_sem. | |
513 | */ | |
514 | down_write(&mm->mmap_sem); | |
515 | up_write(&mm->mmap_sem); | |
516 | } | |
517 | } | |
518 | ||
519 | static void release_pte_page(struct page *page) | |
520 | { | |
d44d363f | 521 | dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); |
b46e756f KS |
522 | unlock_page(page); |
523 | putback_lru_page(page); | |
524 | } | |
525 | ||
526 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
527 | { | |
528 | while (--_pte >= pte) { | |
529 | pte_t pteval = *_pte; | |
530 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) | |
531 | release_pte_page(pte_page(pteval)); | |
532 | } | |
533 | } | |
534 | ||
535 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, | |
536 | unsigned long address, | |
537 | pte_t *pte) | |
538 | { | |
539 | struct page *page = NULL; | |
540 | pte_t *_pte; | |
0db501f7 EA |
541 | int none_or_zero = 0, result = 0, referenced = 0; |
542 | bool writable = false; | |
b46e756f KS |
543 | |
544 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
545 | _pte++, address += PAGE_SIZE) { | |
546 | pte_t pteval = *_pte; | |
547 | if (pte_none(pteval) || (pte_present(pteval) && | |
548 | is_zero_pfn(pte_pfn(pteval)))) { | |
549 | if (!userfaultfd_armed(vma) && | |
550 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
551 | continue; | |
552 | } else { | |
553 | result = SCAN_EXCEED_NONE_PTE; | |
554 | goto out; | |
555 | } | |
556 | } | |
557 | if (!pte_present(pteval)) { | |
558 | result = SCAN_PTE_NON_PRESENT; | |
559 | goto out; | |
560 | } | |
561 | page = vm_normal_page(vma, address, pteval); | |
562 | if (unlikely(!page)) { | |
563 | result = SCAN_PAGE_NULL; | |
564 | goto out; | |
565 | } | |
566 | ||
fece2029 KS |
567 | /* TODO: teach khugepaged to collapse THP mapped with pte */ |
568 | if (PageCompound(page)) { | |
569 | result = SCAN_PAGE_COMPOUND; | |
570 | goto out; | |
571 | } | |
572 | ||
b46e756f | 573 | VM_BUG_ON_PAGE(!PageAnon(page), page); |
b46e756f KS |
574 | |
575 | /* | |
576 | * We can do it before isolate_lru_page because the | |
577 | * page can't be freed from under us. NOTE: PG_lock | |
578 | * is needed to serialize against split_huge_page | |
579 | * when invoked from the VM. | |
580 | */ | |
581 | if (!trylock_page(page)) { | |
582 | result = SCAN_PAGE_LOCK; | |
583 | goto out; | |
584 | } | |
585 | ||
586 | /* | |
587 | * cannot use mapcount: can't collapse if there's a gup pin. | |
588 | * The page must only be referenced by the scanned process | |
589 | * and page swap cache. | |
590 | */ | |
2948be5a | 591 | if (page_count(page) != 1 + PageSwapCache(page)) { |
b46e756f KS |
592 | unlock_page(page); |
593 | result = SCAN_PAGE_COUNT; | |
594 | goto out; | |
595 | } | |
596 | if (pte_write(pteval)) { | |
597 | writable = true; | |
598 | } else { | |
599 | if (PageSwapCache(page) && | |
600 | !reuse_swap_page(page, NULL)) { | |
601 | unlock_page(page); | |
602 | result = SCAN_SWAP_CACHE_PAGE; | |
603 | goto out; | |
604 | } | |
605 | /* | |
606 | * Page is not in the swap cache. It can be collapsed | |
607 | * into a THP. | |
608 | */ | |
609 | } | |
610 | ||
611 | /* | |
612 | * Isolate the page to avoid collapsing an hugepage | |
613 | * currently in use by the VM. | |
614 | */ | |
615 | if (isolate_lru_page(page)) { | |
616 | unlock_page(page); | |
617 | result = SCAN_DEL_PAGE_LRU; | |
618 | goto out; | |
619 | } | |
d44d363f SL |
620 | inc_node_page_state(page, |
621 | NR_ISOLATED_ANON + page_is_file_cache(page)); | |
b46e756f KS |
622 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
623 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
624 | ||
0db501f7 | 625 | /* There should be enough young pte to collapse the page */ |
b46e756f KS |
626 | if (pte_young(pteval) || |
627 | page_is_young(page) || PageReferenced(page) || | |
628 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 629 | referenced++; |
b46e756f | 630 | } |
87a1f0f0 ML |
631 | |
632 | if (unlikely(!writable)) { | |
b46e756f | 633 | result = SCAN_PAGE_RO; |
87a1f0f0 ML |
634 | } else if (unlikely(!referenced)) { |
635 | result = SCAN_LACK_REFERENCED_PAGE; | |
636 | } else { | |
637 | result = SCAN_SUCCEED; | |
638 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, | |
639 | referenced, writable, result); | |
640 | return 1; | |
b46e756f | 641 | } |
b46e756f KS |
642 | out: |
643 | release_pte_pages(pte, _pte); | |
644 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, | |
645 | referenced, writable, result); | |
646 | return 0; | |
647 | } | |
648 | ||
649 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
650 | struct vm_area_struct *vma, | |
651 | unsigned long address, | |
652 | spinlock_t *ptl) | |
653 | { | |
654 | pte_t *_pte; | |
338a16ba DR |
655 | for (_pte = pte; _pte < pte + HPAGE_PMD_NR; |
656 | _pte++, page++, address += PAGE_SIZE) { | |
b46e756f KS |
657 | pte_t pteval = *_pte; |
658 | struct page *src_page; | |
659 | ||
660 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
661 | clear_user_highpage(page, address); | |
662 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
663 | if (is_zero_pfn(pte_pfn(pteval))) { | |
664 | /* | |
665 | * ptl mostly unnecessary. | |
666 | */ | |
667 | spin_lock(ptl); | |
668 | /* | |
669 | * paravirt calls inside pte_clear here are | |
670 | * superfluous. | |
671 | */ | |
672 | pte_clear(vma->vm_mm, address, _pte); | |
673 | spin_unlock(ptl); | |
674 | } | |
675 | } else { | |
676 | src_page = pte_page(pteval); | |
677 | copy_user_highpage(page, src_page, address, vma); | |
678 | VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page); | |
679 | release_pte_page(src_page); | |
680 | /* | |
681 | * ptl mostly unnecessary, but preempt has to | |
682 | * be disabled to update the per-cpu stats | |
683 | * inside page_remove_rmap(). | |
684 | */ | |
685 | spin_lock(ptl); | |
686 | /* | |
687 | * paravirt calls inside pte_clear here are | |
688 | * superfluous. | |
689 | */ | |
690 | pte_clear(vma->vm_mm, address, _pte); | |
691 | page_remove_rmap(src_page, false); | |
692 | spin_unlock(ptl); | |
693 | free_page_and_swap_cache(src_page); | |
694 | } | |
b46e756f KS |
695 | } |
696 | } | |
697 | ||
698 | static void khugepaged_alloc_sleep(void) | |
699 | { | |
700 | DEFINE_WAIT(wait); | |
701 | ||
702 | add_wait_queue(&khugepaged_wait, &wait); | |
703 | freezable_schedule_timeout_interruptible( | |
704 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
705 | remove_wait_queue(&khugepaged_wait, &wait); | |
706 | } | |
707 | ||
708 | static int khugepaged_node_load[MAX_NUMNODES]; | |
709 | ||
710 | static bool khugepaged_scan_abort(int nid) | |
711 | { | |
712 | int i; | |
713 | ||
714 | /* | |
a5f5f91d | 715 | * If node_reclaim_mode is disabled, then no extra effort is made to |
b46e756f KS |
716 | * allocate memory locally. |
717 | */ | |
a5f5f91d | 718 | if (!node_reclaim_mode) |
b46e756f KS |
719 | return false; |
720 | ||
721 | /* If there is a count for this node already, it must be acceptable */ | |
722 | if (khugepaged_node_load[nid]) | |
723 | return false; | |
724 | ||
725 | for (i = 0; i < MAX_NUMNODES; i++) { | |
726 | if (!khugepaged_node_load[i]) | |
727 | continue; | |
a55c7454 | 728 | if (node_distance(nid, i) > node_reclaim_distance) |
b46e756f KS |
729 | return true; |
730 | } | |
731 | return false; | |
732 | } | |
733 | ||
734 | /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */ | |
735 | static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void) | |
736 | { | |
25160354 | 737 | return khugepaged_defrag() ? GFP_TRANSHUGE : GFP_TRANSHUGE_LIGHT; |
b46e756f KS |
738 | } |
739 | ||
740 | #ifdef CONFIG_NUMA | |
741 | static int khugepaged_find_target_node(void) | |
742 | { | |
743 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
744 | int nid, target_node = 0, max_value = 0; | |
745 | ||
746 | /* find first node with max normal pages hit */ | |
747 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
748 | if (khugepaged_node_load[nid] > max_value) { | |
749 | max_value = khugepaged_node_load[nid]; | |
750 | target_node = nid; | |
751 | } | |
752 | ||
753 | /* do some balance if several nodes have the same hit record */ | |
754 | if (target_node <= last_khugepaged_target_node) | |
755 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
756 | nid++) | |
757 | if (max_value == khugepaged_node_load[nid]) { | |
758 | target_node = nid; | |
759 | break; | |
760 | } | |
761 | ||
762 | last_khugepaged_target_node = target_node; | |
763 | return target_node; | |
764 | } | |
765 | ||
766 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
767 | { | |
768 | if (IS_ERR(*hpage)) { | |
769 | if (!*wait) | |
770 | return false; | |
771 | ||
772 | *wait = false; | |
773 | *hpage = NULL; | |
774 | khugepaged_alloc_sleep(); | |
775 | } else if (*hpage) { | |
776 | put_page(*hpage); | |
777 | *hpage = NULL; | |
778 | } | |
779 | ||
780 | return true; | |
781 | } | |
782 | ||
783 | static struct page * | |
988ddb71 | 784 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f KS |
785 | { |
786 | VM_BUG_ON_PAGE(*hpage, *hpage); | |
787 | ||
b46e756f KS |
788 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); |
789 | if (unlikely(!*hpage)) { | |
790 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
791 | *hpage = ERR_PTR(-ENOMEM); | |
792 | return NULL; | |
793 | } | |
794 | ||
795 | prep_transhuge_page(*hpage); | |
796 | count_vm_event(THP_COLLAPSE_ALLOC); | |
797 | return *hpage; | |
798 | } | |
799 | #else | |
800 | static int khugepaged_find_target_node(void) | |
801 | { | |
802 | return 0; | |
803 | } | |
804 | ||
805 | static inline struct page *alloc_khugepaged_hugepage(void) | |
806 | { | |
807 | struct page *page; | |
808 | ||
809 | page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(), | |
810 | HPAGE_PMD_ORDER); | |
811 | if (page) | |
812 | prep_transhuge_page(page); | |
813 | return page; | |
814 | } | |
815 | ||
816 | static struct page *khugepaged_alloc_hugepage(bool *wait) | |
817 | { | |
818 | struct page *hpage; | |
819 | ||
820 | do { | |
821 | hpage = alloc_khugepaged_hugepage(); | |
822 | if (!hpage) { | |
823 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
824 | if (!*wait) | |
825 | return NULL; | |
826 | ||
827 | *wait = false; | |
828 | khugepaged_alloc_sleep(); | |
829 | } else | |
830 | count_vm_event(THP_COLLAPSE_ALLOC); | |
831 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
832 | ||
833 | return hpage; | |
834 | } | |
835 | ||
836 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
837 | { | |
65acc81d HD |
838 | /* |
839 | * If the hpage allocated earlier was briefly exposed in page cache | |
840 | * before collapse_file() failed, it is possible that racing lookups | |
841 | * have not yet completed, and would then be unpleasantly surprised by | |
842 | * finding the hpage reused for the same mapping at a different offset. | |
843 | * Just release the previous allocation if there is any danger of that. | |
844 | */ | |
845 | if (*hpage && page_count(*hpage) > 1) { | |
846 | put_page(*hpage); | |
847 | *hpage = NULL; | |
848 | } | |
849 | ||
b46e756f KS |
850 | if (!*hpage) |
851 | *hpage = khugepaged_alloc_hugepage(wait); | |
852 | ||
853 | if (unlikely(!*hpage)) | |
854 | return false; | |
855 | ||
856 | return true; | |
857 | } | |
858 | ||
859 | static struct page * | |
988ddb71 | 860 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f | 861 | { |
b46e756f KS |
862 | VM_BUG_ON(!*hpage); |
863 | ||
864 | return *hpage; | |
865 | } | |
866 | #endif | |
867 | ||
b46e756f KS |
868 | /* |
869 | * If mmap_sem temporarily dropped, revalidate vma | |
870 | * before taking mmap_sem. | |
871 | * Return 0 if succeeds, otherwise return none-zero | |
872 | * value (scan code). | |
873 | */ | |
874 | ||
c131f751 KS |
875 | static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, |
876 | struct vm_area_struct **vmap) | |
b46e756f KS |
877 | { |
878 | struct vm_area_struct *vma; | |
879 | unsigned long hstart, hend; | |
880 | ||
881 | if (unlikely(khugepaged_test_exit(mm))) | |
882 | return SCAN_ANY_PROCESS; | |
883 | ||
c131f751 | 884 | *vmap = vma = find_vma(mm, address); |
b46e756f KS |
885 | if (!vma) |
886 | return SCAN_VMA_NULL; | |
887 | ||
888 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
889 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
890 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
891 | return SCAN_ADDRESS_RANGE; | |
50f8b92f | 892 | if (!hugepage_vma_check(vma, vma->vm_flags)) |
b46e756f | 893 | return SCAN_VMA_CHECK; |
538689b7 KS |
894 | /* Anon VMA expected */ |
895 | if (!vma->anon_vma || vma->vm_ops) | |
896 | return SCAN_VMA_CHECK; | |
b46e756f KS |
897 | return 0; |
898 | } | |
899 | ||
900 | /* | |
901 | * Bring missing pages in from swap, to complete THP collapse. | |
902 | * Only done if khugepaged_scan_pmd believes it is worthwhile. | |
903 | * | |
904 | * Called and returns without pte mapped or spinlocks held, | |
905 | * but with mmap_sem held to protect against vma changes. | |
906 | */ | |
907 | ||
908 | static bool __collapse_huge_page_swapin(struct mm_struct *mm, | |
909 | struct vm_area_struct *vma, | |
0db501f7 EA |
910 | unsigned long address, pmd_t *pmd, |
911 | int referenced) | |
b46e756f | 912 | { |
2b740303 SJ |
913 | int swapped_in = 0; |
914 | vm_fault_t ret = 0; | |
82b0f8c3 | 915 | struct vm_fault vmf = { |
b46e756f KS |
916 | .vma = vma, |
917 | .address = address, | |
918 | .flags = FAULT_FLAG_ALLOW_RETRY, | |
919 | .pmd = pmd, | |
0721ec8b | 920 | .pgoff = linear_page_index(vma, address), |
b46e756f KS |
921 | }; |
922 | ||
982785c6 EA |
923 | /* we only decide to swapin, if there is enough young ptes */ |
924 | if (referenced < HPAGE_PMD_NR/2) { | |
925 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); | |
926 | return false; | |
927 | } | |
82b0f8c3 JK |
928 | vmf.pte = pte_offset_map(pmd, address); |
929 | for (; vmf.address < address + HPAGE_PMD_NR*PAGE_SIZE; | |
930 | vmf.pte++, vmf.address += PAGE_SIZE) { | |
2994302b JK |
931 | vmf.orig_pte = *vmf.pte; |
932 | if (!is_swap_pte(vmf.orig_pte)) | |
b46e756f KS |
933 | continue; |
934 | swapped_in++; | |
2994302b | 935 | ret = do_swap_page(&vmf); |
0db501f7 | 936 | |
b46e756f KS |
937 | /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */ |
938 | if (ret & VM_FAULT_RETRY) { | |
939 | down_read(&mm->mmap_sem); | |
82b0f8c3 | 940 | if (hugepage_vma_revalidate(mm, address, &vmf.vma)) { |
47f863ea | 941 | /* vma is no longer available, don't continue to swapin */ |
0db501f7 | 942 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f | 943 | return false; |
47f863ea | 944 | } |
b46e756f | 945 | /* check if the pmd is still valid */ |
835152a2 SP |
946 | if (mm_find_pmd(mm, address) != pmd) { |
947 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); | |
b46e756f | 948 | return false; |
835152a2 | 949 | } |
b46e756f KS |
950 | } |
951 | if (ret & VM_FAULT_ERROR) { | |
0db501f7 | 952 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f KS |
953 | return false; |
954 | } | |
955 | /* pte is unmapped now, we need to map it */ | |
82b0f8c3 | 956 | vmf.pte = pte_offset_map(pmd, vmf.address); |
b46e756f | 957 | } |
82b0f8c3 JK |
958 | vmf.pte--; |
959 | pte_unmap(vmf.pte); | |
0db501f7 | 960 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1); |
b46e756f KS |
961 | return true; |
962 | } | |
963 | ||
964 | static void collapse_huge_page(struct mm_struct *mm, | |
965 | unsigned long address, | |
966 | struct page **hpage, | |
0db501f7 | 967 | int node, int referenced) |
b46e756f KS |
968 | { |
969 | pmd_t *pmd, _pmd; | |
970 | pte_t *pte; | |
971 | pgtable_t pgtable; | |
972 | struct page *new_page; | |
973 | spinlock_t *pmd_ptl, *pte_ptl; | |
974 | int isolated = 0, result = 0; | |
975 | struct mem_cgroup *memcg; | |
c131f751 | 976 | struct vm_area_struct *vma; |
ac46d4f3 | 977 | struct mmu_notifier_range range; |
b46e756f KS |
978 | gfp_t gfp; |
979 | ||
980 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
981 | ||
982 | /* Only allocate from the target node */ | |
41b6167e | 983 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
b46e756f | 984 | |
988ddb71 KS |
985 | /* |
986 | * Before allocating the hugepage, release the mmap_sem read lock. | |
987 | * The allocation can take potentially a long time if it involves | |
988 | * sync compaction, and we do not need to hold the mmap_sem during | |
989 | * that. We will recheck the vma after taking it again in write mode. | |
990 | */ | |
991 | up_read(&mm->mmap_sem); | |
992 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
b46e756f KS |
993 | if (!new_page) { |
994 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
995 | goto out_nolock; | |
996 | } | |
997 | ||
2a70f6a7 | 998 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { |
b46e756f KS |
999 | result = SCAN_CGROUP_CHARGE_FAIL; |
1000 | goto out_nolock; | |
1001 | } | |
1002 | ||
1003 | down_read(&mm->mmap_sem); | |
c131f751 | 1004 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f KS |
1005 | if (result) { |
1006 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1007 | up_read(&mm->mmap_sem); | |
1008 | goto out_nolock; | |
1009 | } | |
1010 | ||
1011 | pmd = mm_find_pmd(mm, address); | |
1012 | if (!pmd) { | |
1013 | result = SCAN_PMD_NULL; | |
1014 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1015 | up_read(&mm->mmap_sem); | |
1016 | goto out_nolock; | |
1017 | } | |
1018 | ||
1019 | /* | |
1020 | * __collapse_huge_page_swapin always returns with mmap_sem locked. | |
47f863ea | 1021 | * If it fails, we release mmap_sem and jump out_nolock. |
b46e756f KS |
1022 | * Continuing to collapse causes inconsistency. |
1023 | */ | |
0db501f7 | 1024 | if (!__collapse_huge_page_swapin(mm, vma, address, pmd, referenced)) { |
b46e756f KS |
1025 | mem_cgroup_cancel_charge(new_page, memcg, true); |
1026 | up_read(&mm->mmap_sem); | |
1027 | goto out_nolock; | |
1028 | } | |
1029 | ||
1030 | up_read(&mm->mmap_sem); | |
1031 | /* | |
1032 | * Prevent all access to pagetables with the exception of | |
1033 | * gup_fast later handled by the ptep_clear_flush and the VM | |
1034 | * handled by the anon_vma lock + PG_lock. | |
1035 | */ | |
1036 | down_write(&mm->mmap_sem); | |
c131f751 | 1037 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f KS |
1038 | if (result) |
1039 | goto out; | |
1040 | /* check if the pmd is still valid */ | |
1041 | if (mm_find_pmd(mm, address) != pmd) | |
1042 | goto out; | |
1043 | ||
1044 | anon_vma_lock_write(vma->anon_vma); | |
1045 | ||
7269f999 | 1046 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, |
6f4f13e8 | 1047 | address, address + HPAGE_PMD_SIZE); |
ac46d4f3 | 1048 | mmu_notifier_invalidate_range_start(&range); |
ec649c9d VS |
1049 | |
1050 | pte = pte_offset_map(pmd, address); | |
1051 | pte_ptl = pte_lockptr(mm, pmd); | |
1052 | ||
b46e756f KS |
1053 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
1054 | /* | |
1055 | * After this gup_fast can't run anymore. This also removes | |
1056 | * any huge TLB entry from the CPU so we won't allow | |
1057 | * huge and small TLB entries for the same virtual address | |
1058 | * to avoid the risk of CPU bugs in that area. | |
1059 | */ | |
1060 | _pmd = pmdp_collapse_flush(vma, address, pmd); | |
1061 | spin_unlock(pmd_ptl); | |
ac46d4f3 | 1062 | mmu_notifier_invalidate_range_end(&range); |
b46e756f KS |
1063 | |
1064 | spin_lock(pte_ptl); | |
1065 | isolated = __collapse_huge_page_isolate(vma, address, pte); | |
1066 | spin_unlock(pte_ptl); | |
1067 | ||
1068 | if (unlikely(!isolated)) { | |
1069 | pte_unmap(pte); | |
1070 | spin_lock(pmd_ptl); | |
1071 | BUG_ON(!pmd_none(*pmd)); | |
1072 | /* | |
1073 | * We can only use set_pmd_at when establishing | |
1074 | * hugepmds and never for establishing regular pmds that | |
1075 | * points to regular pagetables. Use pmd_populate for that | |
1076 | */ | |
1077 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
1078 | spin_unlock(pmd_ptl); | |
1079 | anon_vma_unlock_write(vma->anon_vma); | |
1080 | result = SCAN_FAIL; | |
1081 | goto out; | |
1082 | } | |
1083 | ||
1084 | /* | |
1085 | * All pages are isolated and locked so anon_vma rmap | |
1086 | * can't run anymore. | |
1087 | */ | |
1088 | anon_vma_unlock_write(vma->anon_vma); | |
1089 | ||
1090 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); | |
1091 | pte_unmap(pte); | |
1092 | __SetPageUptodate(new_page); | |
1093 | pgtable = pmd_pgtable(_pmd); | |
1094 | ||
1095 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); | |
f55e1014 | 1096 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); |
b46e756f KS |
1097 | |
1098 | /* | |
1099 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
1100 | * this is needed to avoid the copy_huge_page writes to become | |
1101 | * visible after the set_pmd_at() write. | |
1102 | */ | |
1103 | smp_wmb(); | |
1104 | ||
1105 | spin_lock(pmd_ptl); | |
1106 | BUG_ON(!pmd_none(*pmd)); | |
1107 | page_add_new_anon_rmap(new_page, vma, address, true); | |
1108 | mem_cgroup_commit_charge(new_page, memcg, false, true); | |
1ff9e6e1 | 1109 | count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1); |
b46e756f KS |
1110 | lru_cache_add_active_or_unevictable(new_page, vma); |
1111 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
1112 | set_pmd_at(mm, address, pmd, _pmd); | |
1113 | update_mmu_cache_pmd(vma, address, pmd); | |
1114 | spin_unlock(pmd_ptl); | |
1115 | ||
1116 | *hpage = NULL; | |
1117 | ||
1118 | khugepaged_pages_collapsed++; | |
1119 | result = SCAN_SUCCEED; | |
1120 | out_up_write: | |
1121 | up_write(&mm->mmap_sem); | |
1122 | out_nolock: | |
1123 | trace_mm_collapse_huge_page(mm, isolated, result); | |
1124 | return; | |
1125 | out: | |
1126 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1127 | goto out_up_write; | |
1128 | } | |
1129 | ||
1130 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
1131 | struct vm_area_struct *vma, | |
1132 | unsigned long address, | |
1133 | struct page **hpage) | |
1134 | { | |
1135 | pmd_t *pmd; | |
1136 | pte_t *pte, *_pte; | |
0db501f7 | 1137 | int ret = 0, none_or_zero = 0, result = 0, referenced = 0; |
b46e756f KS |
1138 | struct page *page = NULL; |
1139 | unsigned long _address; | |
1140 | spinlock_t *ptl; | |
1141 | int node = NUMA_NO_NODE, unmapped = 0; | |
0db501f7 | 1142 | bool writable = false; |
b46e756f KS |
1143 | |
1144 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1145 | ||
1146 | pmd = mm_find_pmd(mm, address); | |
1147 | if (!pmd) { | |
1148 | result = SCAN_PMD_NULL; | |
1149 | goto out; | |
1150 | } | |
1151 | ||
1152 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1153 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1154 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1155 | _pte++, _address += PAGE_SIZE) { | |
1156 | pte_t pteval = *_pte; | |
1157 | if (is_swap_pte(pteval)) { | |
1158 | if (++unmapped <= khugepaged_max_ptes_swap) { | |
1159 | continue; | |
1160 | } else { | |
1161 | result = SCAN_EXCEED_SWAP_PTE; | |
1162 | goto out_unmap; | |
1163 | } | |
1164 | } | |
1165 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
1166 | if (!userfaultfd_armed(vma) && | |
1167 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
1168 | continue; | |
1169 | } else { | |
1170 | result = SCAN_EXCEED_NONE_PTE; | |
1171 | goto out_unmap; | |
1172 | } | |
1173 | } | |
1174 | if (!pte_present(pteval)) { | |
1175 | result = SCAN_PTE_NON_PRESENT; | |
1176 | goto out_unmap; | |
1177 | } | |
1178 | if (pte_write(pteval)) | |
1179 | writable = true; | |
1180 | ||
1181 | page = vm_normal_page(vma, _address, pteval); | |
1182 | if (unlikely(!page)) { | |
1183 | result = SCAN_PAGE_NULL; | |
1184 | goto out_unmap; | |
1185 | } | |
1186 | ||
1187 | /* TODO: teach khugepaged to collapse THP mapped with pte */ | |
1188 | if (PageCompound(page)) { | |
1189 | result = SCAN_PAGE_COMPOUND; | |
1190 | goto out_unmap; | |
1191 | } | |
1192 | ||
1193 | /* | |
1194 | * Record which node the original page is from and save this | |
1195 | * information to khugepaged_node_load[]. | |
1196 | * Khupaged will allocate hugepage from the node has the max | |
1197 | * hit record. | |
1198 | */ | |
1199 | node = page_to_nid(page); | |
1200 | if (khugepaged_scan_abort(node)) { | |
1201 | result = SCAN_SCAN_ABORT; | |
1202 | goto out_unmap; | |
1203 | } | |
1204 | khugepaged_node_load[node]++; | |
1205 | if (!PageLRU(page)) { | |
1206 | result = SCAN_PAGE_LRU; | |
1207 | goto out_unmap; | |
1208 | } | |
1209 | if (PageLocked(page)) { | |
1210 | result = SCAN_PAGE_LOCK; | |
1211 | goto out_unmap; | |
1212 | } | |
1213 | if (!PageAnon(page)) { | |
1214 | result = SCAN_PAGE_ANON; | |
1215 | goto out_unmap; | |
1216 | } | |
1217 | ||
1218 | /* | |
1219 | * cannot use mapcount: can't collapse if there's a gup pin. | |
1220 | * The page must only be referenced by the scanned process | |
1221 | * and page swap cache. | |
1222 | */ | |
2948be5a | 1223 | if (page_count(page) != 1 + PageSwapCache(page)) { |
b46e756f KS |
1224 | result = SCAN_PAGE_COUNT; |
1225 | goto out_unmap; | |
1226 | } | |
1227 | if (pte_young(pteval) || | |
1228 | page_is_young(page) || PageReferenced(page) || | |
1229 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 1230 | referenced++; |
b46e756f KS |
1231 | } |
1232 | if (writable) { | |
1233 | if (referenced) { | |
1234 | result = SCAN_SUCCEED; | |
1235 | ret = 1; | |
1236 | } else { | |
0db501f7 | 1237 | result = SCAN_LACK_REFERENCED_PAGE; |
b46e756f KS |
1238 | } |
1239 | } else { | |
1240 | result = SCAN_PAGE_RO; | |
1241 | } | |
1242 | out_unmap: | |
1243 | pte_unmap_unlock(pte, ptl); | |
1244 | if (ret) { | |
1245 | node = khugepaged_find_target_node(); | |
1246 | /* collapse_huge_page will return with the mmap_sem released */ | |
c131f751 | 1247 | collapse_huge_page(mm, address, hpage, node, referenced); |
b46e756f KS |
1248 | } |
1249 | out: | |
1250 | trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, | |
1251 | none_or_zero, result, unmapped); | |
1252 | return ret; | |
1253 | } | |
1254 | ||
1255 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
1256 | { | |
1257 | struct mm_struct *mm = mm_slot->mm; | |
1258 | ||
35f3aa39 | 1259 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
1260 | |
1261 | if (khugepaged_test_exit(mm)) { | |
1262 | /* free mm_slot */ | |
1263 | hash_del(&mm_slot->hash); | |
1264 | list_del(&mm_slot->mm_node); | |
1265 | ||
1266 | /* | |
1267 | * Not strictly needed because the mm exited already. | |
1268 | * | |
1269 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1270 | */ | |
1271 | ||
1272 | /* khugepaged_mm_lock actually not necessary for the below */ | |
1273 | free_mm_slot(mm_slot); | |
1274 | mmdrop(mm); | |
1275 | } | |
1276 | } | |
1277 | ||
e496cf3d | 1278 | #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) |
27e1f827 SL |
1279 | /* |
1280 | * Notify khugepaged that given addr of the mm is pte-mapped THP. Then | |
1281 | * khugepaged should try to collapse the page table. | |
1282 | */ | |
1283 | static int khugepaged_add_pte_mapped_thp(struct mm_struct *mm, | |
1284 | unsigned long addr) | |
1285 | { | |
1286 | struct mm_slot *mm_slot; | |
1287 | ||
1288 | VM_BUG_ON(addr & ~HPAGE_PMD_MASK); | |
1289 | ||
1290 | spin_lock(&khugepaged_mm_lock); | |
1291 | mm_slot = get_mm_slot(mm); | |
1292 | if (likely(mm_slot && mm_slot->nr_pte_mapped_thp < MAX_PTE_MAPPED_THP)) | |
1293 | mm_slot->pte_mapped_thp[mm_slot->nr_pte_mapped_thp++] = addr; | |
1294 | spin_unlock(&khugepaged_mm_lock); | |
1295 | return 0; | |
1296 | } | |
1297 | ||
1298 | /** | |
1299 | * Try to collapse a pte-mapped THP for mm at address haddr. | |
1300 | * | |
1301 | * This function checks whether all the PTEs in the PMD are pointing to the | |
1302 | * right THP. If so, retract the page table so the THP can refault in with | |
1303 | * as pmd-mapped. | |
1304 | */ | |
1305 | void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) | |
1306 | { | |
1307 | unsigned long haddr = addr & HPAGE_PMD_MASK; | |
1308 | struct vm_area_struct *vma = find_vma(mm, haddr); | |
4a9892d7 | 1309 | struct page *hpage; |
27e1f827 SL |
1310 | pte_t *start_pte, *pte; |
1311 | pmd_t *pmd, _pmd; | |
1312 | spinlock_t *ptl; | |
1313 | int count = 0; | |
1314 | int i; | |
1315 | ||
1316 | if (!vma || !vma->vm_file || | |
1317 | vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE) | |
1318 | return; | |
1319 | ||
1320 | /* | |
1321 | * This vm_flags may not have VM_HUGEPAGE if the page was not | |
1322 | * collapsed by this mm. But we can still collapse if the page is | |
1323 | * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check() | |
1324 | * will not fail the vma for missing VM_HUGEPAGE | |
1325 | */ | |
1326 | if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE)) | |
1327 | return; | |
1328 | ||
4a9892d7 HD |
1329 | hpage = find_lock_page(vma->vm_file->f_mapping, |
1330 | linear_page_index(vma, haddr)); | |
1331 | if (!hpage) | |
1332 | return; | |
1333 | ||
1334 | if (!PageHead(hpage)) | |
1335 | goto drop_hpage; | |
1336 | ||
27e1f827 SL |
1337 | pmd = mm_find_pmd(mm, haddr); |
1338 | if (!pmd) | |
4a9892d7 | 1339 | goto drop_hpage; |
27e1f827 SL |
1340 | |
1341 | start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl); | |
1342 | ||
1343 | /* step 1: check all mapped PTEs are to the right huge page */ | |
1344 | for (i = 0, addr = haddr, pte = start_pte; | |
1345 | i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) { | |
1346 | struct page *page; | |
1347 | ||
1348 | /* empty pte, skip */ | |
1349 | if (pte_none(*pte)) | |
1350 | continue; | |
1351 | ||
1352 | /* page swapped out, abort */ | |
1353 | if (!pte_present(*pte)) | |
1354 | goto abort; | |
1355 | ||
1356 | page = vm_normal_page(vma, addr, *pte); | |
1357 | ||
27e1f827 | 1358 | /* |
4a9892d7 HD |
1359 | * Note that uprobe, debugger, or MAP_PRIVATE may change the |
1360 | * page table, but the new page will not be a subpage of hpage. | |
27e1f827 | 1361 | */ |
4a9892d7 | 1362 | if (hpage + i != page) |
27e1f827 SL |
1363 | goto abort; |
1364 | count++; | |
1365 | } | |
1366 | ||
1367 | /* step 2: adjust rmap */ | |
1368 | for (i = 0, addr = haddr, pte = start_pte; | |
1369 | i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) { | |
1370 | struct page *page; | |
1371 | ||
1372 | if (pte_none(*pte)) | |
1373 | continue; | |
1374 | page = vm_normal_page(vma, addr, *pte); | |
1375 | page_remove_rmap(page, false); | |
1376 | } | |
1377 | ||
1378 | pte_unmap_unlock(start_pte, ptl); | |
1379 | ||
1380 | /* step 3: set proper refcount and mm_counters. */ | |
4a9892d7 | 1381 | if (count) { |
27e1f827 SL |
1382 | page_ref_sub(hpage, count); |
1383 | add_mm_counter(vma->vm_mm, mm_counter_file(hpage), -count); | |
1384 | } | |
1385 | ||
1386 | /* step 4: collapse pmd */ | |
1387 | ptl = pmd_lock(vma->vm_mm, pmd); | |
1eaeb33f | 1388 | _pmd = pmdp_collapse_flush(vma, haddr, pmd); |
27e1f827 SL |
1389 | spin_unlock(ptl); |
1390 | mm_dec_nr_ptes(mm); | |
1391 | pte_free(mm, pmd_pgtable(_pmd)); | |
4a9892d7 HD |
1392 | |
1393 | drop_hpage: | |
1394 | unlock_page(hpage); | |
1395 | put_page(hpage); | |
27e1f827 SL |
1396 | return; |
1397 | ||
1398 | abort: | |
1399 | pte_unmap_unlock(start_pte, ptl); | |
4a9892d7 | 1400 | goto drop_hpage; |
27e1f827 SL |
1401 | } |
1402 | ||
1403 | static int khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) | |
1404 | { | |
1405 | struct mm_struct *mm = mm_slot->mm; | |
1406 | int i; | |
1407 | ||
1408 | if (likely(mm_slot->nr_pte_mapped_thp == 0)) | |
1409 | return 0; | |
1410 | ||
1411 | if (!down_write_trylock(&mm->mmap_sem)) | |
1412 | return -EBUSY; | |
1413 | ||
1414 | if (unlikely(khugepaged_test_exit(mm))) | |
1415 | goto out; | |
1416 | ||
1417 | for (i = 0; i < mm_slot->nr_pte_mapped_thp; i++) | |
1418 | collapse_pte_mapped_thp(mm, mm_slot->pte_mapped_thp[i]); | |
1419 | ||
1420 | out: | |
1421 | mm_slot->nr_pte_mapped_thp = 0; | |
1422 | up_write(&mm->mmap_sem); | |
1423 | return 0; | |
1424 | } | |
1425 | ||
f3f0e1d2 KS |
1426 | static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) |
1427 | { | |
1428 | struct vm_area_struct *vma; | |
3442c064 | 1429 | struct mm_struct *mm; |
f3f0e1d2 KS |
1430 | unsigned long addr; |
1431 | pmd_t *pmd, _pmd; | |
1432 | ||
1433 | i_mmap_lock_write(mapping); | |
1434 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { | |
27e1f827 SL |
1435 | /* |
1436 | * Check vma->anon_vma to exclude MAP_PRIVATE mappings that | |
1437 | * got written to. These VMAs are likely not worth investing | |
1438 | * down_write(mmap_sem) as PMD-mapping is likely to be split | |
1439 | * later. | |
1440 | * | |
1441 | * Not that vma->anon_vma check is racy: it can be set up after | |
1442 | * the check but before we took mmap_sem by the fault path. | |
1443 | * But page lock would prevent establishing any new ptes of the | |
1444 | * page, so we are safe. | |
1445 | * | |
1446 | * An alternative would be drop the check, but check that page | |
1447 | * table is clear before calling pmdp_collapse_flush() under | |
1448 | * ptl. It has higher chance to recover THP for the VMA, but | |
1449 | * has higher cost too. | |
1450 | */ | |
f3f0e1d2 KS |
1451 | if (vma->anon_vma) |
1452 | continue; | |
1453 | addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
1454 | if (addr & ~HPAGE_PMD_MASK) | |
1455 | continue; | |
1456 | if (vma->vm_end < addr + HPAGE_PMD_SIZE) | |
1457 | continue; | |
3442c064 HD |
1458 | mm = vma->vm_mm; |
1459 | pmd = mm_find_pmd(mm, addr); | |
f3f0e1d2 KS |
1460 | if (!pmd) |
1461 | continue; | |
1462 | /* | |
1463 | * We need exclusive mmap_sem to retract page table. | |
27e1f827 SL |
1464 | * |
1465 | * We use trylock due to lock inversion: we need to acquire | |
1466 | * mmap_sem while holding page lock. Fault path does it in | |
1467 | * reverse order. Trylock is a way to avoid deadlock. | |
f3f0e1d2 | 1468 | */ |
3442c064 HD |
1469 | if (down_write_trylock(&mm->mmap_sem)) { |
1470 | if (!khugepaged_test_exit(mm)) { | |
1471 | spinlock_t *ptl = pmd_lock(mm, pmd); | |
1472 | /* assume page table is clear */ | |
1473 | _pmd = pmdp_collapse_flush(vma, addr, pmd); | |
1474 | spin_unlock(ptl); | |
1475 | mm_dec_nr_ptes(mm); | |
1476 | pte_free(mm, pmd_pgtable(_pmd)); | |
1477 | } | |
1478 | up_write(&mm->mmap_sem); | |
27e1f827 SL |
1479 | } else { |
1480 | /* Try again later */ | |
3442c064 | 1481 | khugepaged_add_pte_mapped_thp(mm, addr); |
f3f0e1d2 KS |
1482 | } |
1483 | } | |
1484 | i_mmap_unlock_write(mapping); | |
1485 | } | |
1486 | ||
1487 | /** | |
99cb0dbd | 1488 | * collapse_file - collapse filemap/tmpfs/shmem pages into huge one. |
f3f0e1d2 KS |
1489 | * |
1490 | * Basic scheme is simple, details are more complex: | |
87c460a0 | 1491 | * - allocate and lock a new huge page; |
77da9389 | 1492 | * - scan page cache replacing old pages with the new one |
99cb0dbd | 1493 | * + swap/gup in pages if necessary; |
f3f0e1d2 | 1494 | * + fill in gaps; |
77da9389 MW |
1495 | * + keep old pages around in case rollback is required; |
1496 | * - if replacing succeeds: | |
f3f0e1d2 KS |
1497 | * + copy data over; |
1498 | * + free old pages; | |
87c460a0 | 1499 | * + unlock huge page; |
f3f0e1d2 KS |
1500 | * - if replacing failed; |
1501 | * + put all pages back and unfreeze them; | |
77da9389 | 1502 | * + restore gaps in the page cache; |
87c460a0 | 1503 | * + unlock and free huge page; |
f3f0e1d2 | 1504 | */ |
579c571e SL |
1505 | static void collapse_file(struct mm_struct *mm, |
1506 | struct file *file, pgoff_t start, | |
f3f0e1d2 KS |
1507 | struct page **hpage, int node) |
1508 | { | |
579c571e | 1509 | struct address_space *mapping = file->f_mapping; |
f3f0e1d2 | 1510 | gfp_t gfp; |
77da9389 | 1511 | struct page *new_page; |
f3f0e1d2 KS |
1512 | struct mem_cgroup *memcg; |
1513 | pgoff_t index, end = start + HPAGE_PMD_NR; | |
1514 | LIST_HEAD(pagelist); | |
77da9389 | 1515 | XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); |
f3f0e1d2 | 1516 | int nr_none = 0, result = SCAN_SUCCEED; |
99cb0dbd | 1517 | bool is_shmem = shmem_file(file); |
f3f0e1d2 | 1518 | |
99cb0dbd | 1519 | VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); |
f3f0e1d2 KS |
1520 | VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); |
1521 | ||
1522 | /* Only allocate from the target node */ | |
41b6167e | 1523 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
f3f0e1d2 KS |
1524 | |
1525 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
1526 | if (!new_page) { | |
1527 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
1528 | goto out; | |
1529 | } | |
1530 | ||
2a70f6a7 | 1531 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { |
f3f0e1d2 KS |
1532 | result = SCAN_CGROUP_CHARGE_FAIL; |
1533 | goto out; | |
1534 | } | |
1535 | ||
95feeabb HD |
1536 | /* This will be less messy when we use multi-index entries */ |
1537 | do { | |
1538 | xas_lock_irq(&xas); | |
1539 | xas_create_range(&xas); | |
1540 | if (!xas_error(&xas)) | |
1541 | break; | |
1542 | xas_unlock_irq(&xas); | |
1543 | if (!xas_nomem(&xas, GFP_KERNEL)) { | |
1544 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1545 | result = SCAN_FAIL; | |
1546 | goto out; | |
1547 | } | |
1548 | } while (1); | |
1549 | ||
042a3082 | 1550 | __SetPageLocked(new_page); |
99cb0dbd SL |
1551 | if (is_shmem) |
1552 | __SetPageSwapBacked(new_page); | |
f3f0e1d2 KS |
1553 | new_page->index = start; |
1554 | new_page->mapping = mapping; | |
f3f0e1d2 | 1555 | |
f3f0e1d2 | 1556 | /* |
87c460a0 HD |
1557 | * At this point the new_page is locked and not up-to-date. |
1558 | * It's safe to insert it into the page cache, because nobody would | |
1559 | * be able to map it or use it in another way until we unlock it. | |
f3f0e1d2 KS |
1560 | */ |
1561 | ||
77da9389 MW |
1562 | xas_set(&xas, start); |
1563 | for (index = start; index < end; index++) { | |
1564 | struct page *page = xas_next(&xas); | |
1565 | ||
1566 | VM_BUG_ON(index != xas.xa_index); | |
99cb0dbd SL |
1567 | if (is_shmem) { |
1568 | if (!page) { | |
1569 | /* | |
1570 | * Stop if extent has been truncated or | |
1571 | * hole-punched, and is now completely | |
1572 | * empty. | |
1573 | */ | |
1574 | if (index == start) { | |
1575 | if (!xas_next_entry(&xas, end - 1)) { | |
1576 | result = SCAN_TRUNCATED; | |
1577 | goto xa_locked; | |
1578 | } | |
1579 | xas_set(&xas, index); | |
1580 | } | |
1581 | if (!shmem_charge(mapping->host, 1)) { | |
1582 | result = SCAN_FAIL; | |
042a3082 | 1583 | goto xa_locked; |
701270fa | 1584 | } |
99cb0dbd SL |
1585 | xas_store(&xas, new_page); |
1586 | nr_none++; | |
1587 | continue; | |
701270fa | 1588 | } |
99cb0dbd SL |
1589 | |
1590 | if (xa_is_value(page) || !PageUptodate(page)) { | |
1591 | xas_unlock_irq(&xas); | |
1592 | /* swap in or instantiate fallocated page */ | |
1593 | if (shmem_getpage(mapping->host, index, &page, | |
1594 | SGP_NOHUGE)) { | |
1595 | result = SCAN_FAIL; | |
1596 | goto xa_unlocked; | |
1597 | } | |
1598 | } else if (trylock_page(page)) { | |
1599 | get_page(page); | |
1600 | xas_unlock_irq(&xas); | |
1601 | } else { | |
1602 | result = SCAN_PAGE_LOCK; | |
042a3082 | 1603 | goto xa_locked; |
77da9389 | 1604 | } |
99cb0dbd SL |
1605 | } else { /* !is_shmem */ |
1606 | if (!page || xa_is_value(page)) { | |
1607 | xas_unlock_irq(&xas); | |
1608 | page_cache_sync_readahead(mapping, &file->f_ra, | |
1609 | file, index, | |
5b42bfe0 | 1610 | end - index); |
99cb0dbd SL |
1611 | /* drain pagevecs to help isolate_lru_page() */ |
1612 | lru_add_drain(); | |
1613 | page = find_lock_page(mapping, index); | |
1614 | if (unlikely(page == NULL)) { | |
1615 | result = SCAN_FAIL; | |
1616 | goto xa_unlocked; | |
1617 | } | |
99cb0dbd SL |
1618 | } else if (trylock_page(page)) { |
1619 | get_page(page); | |
1620 | xas_unlock_irq(&xas); | |
1621 | } else { | |
1622 | result = SCAN_PAGE_LOCK; | |
1623 | goto xa_locked; | |
f3f0e1d2 | 1624 | } |
f3f0e1d2 KS |
1625 | } |
1626 | ||
1627 | /* | |
b93b0163 | 1628 | * The page must be locked, so we can drop the i_pages lock |
f3f0e1d2 KS |
1629 | * without racing with truncate. |
1630 | */ | |
1631 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
4655e5e5 SL |
1632 | |
1633 | /* make sure the page is up to date */ | |
1634 | if (unlikely(!PageUptodate(page))) { | |
1635 | result = SCAN_FAIL; | |
1636 | goto out_unlock; | |
1637 | } | |
06a5e126 HD |
1638 | |
1639 | /* | |
1640 | * If file was truncated then extended, or hole-punched, before | |
1641 | * we locked the first page, then a THP might be there already. | |
1642 | */ | |
1643 | if (PageTransCompound(page)) { | |
1644 | result = SCAN_PAGE_COMPOUND; | |
1645 | goto out_unlock; | |
1646 | } | |
f3f0e1d2 KS |
1647 | |
1648 | if (page_mapping(page) != mapping) { | |
1649 | result = SCAN_TRUNCATED; | |
1650 | goto out_unlock; | |
1651 | } | |
f3f0e1d2 | 1652 | |
4655e5e5 SL |
1653 | if (!is_shmem && PageDirty(page)) { |
1654 | /* | |
1655 | * khugepaged only works on read-only fd, so this | |
1656 | * page is dirty because it hasn't been flushed | |
1657 | * since first write. | |
1658 | */ | |
1659 | result = SCAN_FAIL; | |
1660 | goto out_unlock; | |
1661 | } | |
1662 | ||
f3f0e1d2 KS |
1663 | if (isolate_lru_page(page)) { |
1664 | result = SCAN_DEL_PAGE_LRU; | |
042a3082 | 1665 | goto out_unlock; |
f3f0e1d2 KS |
1666 | } |
1667 | ||
99cb0dbd SL |
1668 | if (page_has_private(page) && |
1669 | !try_to_release_page(page, GFP_KERNEL)) { | |
1670 | result = SCAN_PAGE_HAS_PRIVATE; | |
725e6db0 | 1671 | putback_lru_page(page); |
99cb0dbd SL |
1672 | goto out_unlock; |
1673 | } | |
1674 | ||
f3f0e1d2 | 1675 | if (page_mapped(page)) |
977fbdcd | 1676 | unmap_mapping_pages(mapping, index, 1, false); |
f3f0e1d2 | 1677 | |
77da9389 MW |
1678 | xas_lock_irq(&xas); |
1679 | xas_set(&xas, index); | |
f3f0e1d2 | 1680 | |
77da9389 | 1681 | VM_BUG_ON_PAGE(page != xas_load(&xas), page); |
f3f0e1d2 KS |
1682 | VM_BUG_ON_PAGE(page_mapped(page), page); |
1683 | ||
1684 | /* | |
1685 | * The page is expected to have page_count() == 3: | |
1686 | * - we hold a pin on it; | |
77da9389 | 1687 | * - one reference from page cache; |
f3f0e1d2 KS |
1688 | * - one from isolate_lru_page; |
1689 | */ | |
1690 | if (!page_ref_freeze(page, 3)) { | |
1691 | result = SCAN_PAGE_COUNT; | |
042a3082 HD |
1692 | xas_unlock_irq(&xas); |
1693 | putback_lru_page(page); | |
1694 | goto out_unlock; | |
f3f0e1d2 KS |
1695 | } |
1696 | ||
1697 | /* | |
1698 | * Add the page to the list to be able to undo the collapse if | |
1699 | * something go wrong. | |
1700 | */ | |
1701 | list_add_tail(&page->lru, &pagelist); | |
1702 | ||
1703 | /* Finally, replace with the new page. */ | |
4101196b | 1704 | xas_store(&xas, new_page); |
f3f0e1d2 | 1705 | continue; |
f3f0e1d2 KS |
1706 | out_unlock: |
1707 | unlock_page(page); | |
1708 | put_page(page); | |
042a3082 | 1709 | goto xa_unlocked; |
f3f0e1d2 KS |
1710 | } |
1711 | ||
99cb0dbd SL |
1712 | if (is_shmem) |
1713 | __inc_node_page_state(new_page, NR_SHMEM_THPS); | |
09d91cda | 1714 | else { |
99cb0dbd | 1715 | __inc_node_page_state(new_page, NR_FILE_THPS); |
09d91cda SL |
1716 | filemap_nr_thps_inc(mapping); |
1717 | } | |
99cb0dbd | 1718 | |
042a3082 HD |
1719 | if (nr_none) { |
1720 | struct zone *zone = page_zone(new_page); | |
1721 | ||
1722 | __mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none); | |
99cb0dbd SL |
1723 | if (is_shmem) |
1724 | __mod_node_page_state(zone->zone_pgdat, | |
1725 | NR_SHMEM, nr_none); | |
042a3082 HD |
1726 | } |
1727 | ||
1728 | xa_locked: | |
1729 | xas_unlock_irq(&xas); | |
77da9389 | 1730 | xa_unlocked: |
042a3082 | 1731 | |
f3f0e1d2 | 1732 | if (result == SCAN_SUCCEED) { |
77da9389 | 1733 | struct page *page, *tmp; |
f3f0e1d2 KS |
1734 | |
1735 | /* | |
77da9389 MW |
1736 | * Replacing old pages with new one has succeeded, now we |
1737 | * need to copy the content and free the old pages. | |
f3f0e1d2 | 1738 | */ |
2af8ff29 | 1739 | index = start; |
f3f0e1d2 | 1740 | list_for_each_entry_safe(page, tmp, &pagelist, lru) { |
2af8ff29 HD |
1741 | while (index < page->index) { |
1742 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1743 | index++; | |
1744 | } | |
f3f0e1d2 KS |
1745 | copy_highpage(new_page + (page->index % HPAGE_PMD_NR), |
1746 | page); | |
1747 | list_del(&page->lru); | |
f3f0e1d2 | 1748 | page->mapping = NULL; |
042a3082 | 1749 | page_ref_unfreeze(page, 1); |
f3f0e1d2 KS |
1750 | ClearPageActive(page); |
1751 | ClearPageUnevictable(page); | |
042a3082 | 1752 | unlock_page(page); |
f3f0e1d2 | 1753 | put_page(page); |
2af8ff29 HD |
1754 | index++; |
1755 | } | |
1756 | while (index < end) { | |
1757 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1758 | index++; | |
f3f0e1d2 KS |
1759 | } |
1760 | ||
f3f0e1d2 | 1761 | SetPageUptodate(new_page); |
87c460a0 | 1762 | page_ref_add(new_page, HPAGE_PMD_NR - 1); |
f3f0e1d2 | 1763 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
99cb0dbd SL |
1764 | |
1765 | if (is_shmem) { | |
1766 | set_page_dirty(new_page); | |
1767 | lru_cache_add_anon(new_page); | |
1768 | } else { | |
1769 | lru_cache_add_file(new_page); | |
1770 | } | |
1ff9e6e1 | 1771 | count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1); |
f3f0e1d2 | 1772 | |
042a3082 HD |
1773 | /* |
1774 | * Remove pte page tables, so we can re-fault the page as huge. | |
1775 | */ | |
1776 | retract_page_tables(mapping, start); | |
f3f0e1d2 | 1777 | *hpage = NULL; |
87aa7529 YS |
1778 | |
1779 | khugepaged_pages_collapsed++; | |
f3f0e1d2 | 1780 | } else { |
77da9389 | 1781 | struct page *page; |
aaa52e34 | 1782 | |
77da9389 | 1783 | /* Something went wrong: roll back page cache changes */ |
77da9389 | 1784 | xas_lock_irq(&xas); |
aaa52e34 | 1785 | mapping->nrpages -= nr_none; |
99cb0dbd SL |
1786 | |
1787 | if (is_shmem) | |
1788 | shmem_uncharge(mapping->host, nr_none); | |
aaa52e34 | 1789 | |
77da9389 MW |
1790 | xas_set(&xas, start); |
1791 | xas_for_each(&xas, page, end - 1) { | |
f3f0e1d2 KS |
1792 | page = list_first_entry_or_null(&pagelist, |
1793 | struct page, lru); | |
77da9389 | 1794 | if (!page || xas.xa_index < page->index) { |
f3f0e1d2 KS |
1795 | if (!nr_none) |
1796 | break; | |
f3f0e1d2 | 1797 | nr_none--; |
59749e6c | 1798 | /* Put holes back where they were */ |
77da9389 | 1799 | xas_store(&xas, NULL); |
f3f0e1d2 KS |
1800 | continue; |
1801 | } | |
1802 | ||
77da9389 | 1803 | VM_BUG_ON_PAGE(page->index != xas.xa_index, page); |
f3f0e1d2 KS |
1804 | |
1805 | /* Unfreeze the page. */ | |
1806 | list_del(&page->lru); | |
1807 | page_ref_unfreeze(page, 2); | |
77da9389 MW |
1808 | xas_store(&xas, page); |
1809 | xas_pause(&xas); | |
1810 | xas_unlock_irq(&xas); | |
f3f0e1d2 | 1811 | unlock_page(page); |
042a3082 | 1812 | putback_lru_page(page); |
77da9389 | 1813 | xas_lock_irq(&xas); |
f3f0e1d2 KS |
1814 | } |
1815 | VM_BUG_ON(nr_none); | |
77da9389 | 1816 | xas_unlock_irq(&xas); |
f3f0e1d2 | 1817 | |
f3f0e1d2 | 1818 | mem_cgroup_cancel_charge(new_page, memcg, true); |
f3f0e1d2 KS |
1819 | new_page->mapping = NULL; |
1820 | } | |
042a3082 HD |
1821 | |
1822 | unlock_page(new_page); | |
f3f0e1d2 KS |
1823 | out: |
1824 | VM_BUG_ON(!list_empty(&pagelist)); | |
1825 | /* TODO: tracepoints */ | |
1826 | } | |
1827 | ||
579c571e SL |
1828 | static void khugepaged_scan_file(struct mm_struct *mm, |
1829 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
1830 | { |
1831 | struct page *page = NULL; | |
579c571e | 1832 | struct address_space *mapping = file->f_mapping; |
85b392db | 1833 | XA_STATE(xas, &mapping->i_pages, start); |
f3f0e1d2 KS |
1834 | int present, swap; |
1835 | int node = NUMA_NO_NODE; | |
1836 | int result = SCAN_SUCCEED; | |
1837 | ||
1838 | present = 0; | |
1839 | swap = 0; | |
1840 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1841 | rcu_read_lock(); | |
85b392db MW |
1842 | xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) { |
1843 | if (xas_retry(&xas, page)) | |
f3f0e1d2 | 1844 | continue; |
f3f0e1d2 | 1845 | |
85b392db | 1846 | if (xa_is_value(page)) { |
f3f0e1d2 KS |
1847 | if (++swap > khugepaged_max_ptes_swap) { |
1848 | result = SCAN_EXCEED_SWAP_PTE; | |
1849 | break; | |
1850 | } | |
1851 | continue; | |
1852 | } | |
1853 | ||
1854 | if (PageTransCompound(page)) { | |
1855 | result = SCAN_PAGE_COMPOUND; | |
1856 | break; | |
1857 | } | |
1858 | ||
1859 | node = page_to_nid(page); | |
1860 | if (khugepaged_scan_abort(node)) { | |
1861 | result = SCAN_SCAN_ABORT; | |
1862 | break; | |
1863 | } | |
1864 | khugepaged_node_load[node]++; | |
1865 | ||
1866 | if (!PageLRU(page)) { | |
1867 | result = SCAN_PAGE_LRU; | |
1868 | break; | |
1869 | } | |
1870 | ||
99cb0dbd SL |
1871 | if (page_count(page) != |
1872 | 1 + page_mapcount(page) + page_has_private(page)) { | |
f3f0e1d2 KS |
1873 | result = SCAN_PAGE_COUNT; |
1874 | break; | |
1875 | } | |
1876 | ||
1877 | /* | |
1878 | * We probably should check if the page is referenced here, but | |
1879 | * nobody would transfer pte_young() to PageReferenced() for us. | |
1880 | * And rmap walk here is just too costly... | |
1881 | */ | |
1882 | ||
1883 | present++; | |
1884 | ||
1885 | if (need_resched()) { | |
85b392db | 1886 | xas_pause(&xas); |
f3f0e1d2 | 1887 | cond_resched_rcu(); |
f3f0e1d2 KS |
1888 | } |
1889 | } | |
1890 | rcu_read_unlock(); | |
1891 | ||
1892 | if (result == SCAN_SUCCEED) { | |
1893 | if (present < HPAGE_PMD_NR - khugepaged_max_ptes_none) { | |
1894 | result = SCAN_EXCEED_NONE_PTE; | |
1895 | } else { | |
1896 | node = khugepaged_find_target_node(); | |
579c571e | 1897 | collapse_file(mm, file, start, hpage, node); |
f3f0e1d2 KS |
1898 | } |
1899 | } | |
1900 | ||
1901 | /* TODO: tracepoints */ | |
1902 | } | |
1903 | #else | |
579c571e SL |
1904 | static void khugepaged_scan_file(struct mm_struct *mm, |
1905 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
1906 | { |
1907 | BUILD_BUG(); | |
1908 | } | |
27e1f827 SL |
1909 | |
1910 | static int khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) | |
1911 | { | |
1912 | return 0; | |
1913 | } | |
f3f0e1d2 KS |
1914 | #endif |
1915 | ||
b46e756f KS |
1916 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, |
1917 | struct page **hpage) | |
1918 | __releases(&khugepaged_mm_lock) | |
1919 | __acquires(&khugepaged_mm_lock) | |
1920 | { | |
1921 | struct mm_slot *mm_slot; | |
1922 | struct mm_struct *mm; | |
1923 | struct vm_area_struct *vma; | |
1924 | int progress = 0; | |
1925 | ||
1926 | VM_BUG_ON(!pages); | |
35f3aa39 | 1927 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
1928 | |
1929 | if (khugepaged_scan.mm_slot) | |
1930 | mm_slot = khugepaged_scan.mm_slot; | |
1931 | else { | |
1932 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
1933 | struct mm_slot, mm_node); | |
1934 | khugepaged_scan.address = 0; | |
1935 | khugepaged_scan.mm_slot = mm_slot; | |
1936 | } | |
1937 | spin_unlock(&khugepaged_mm_lock); | |
27e1f827 | 1938 | khugepaged_collapse_pte_mapped_thps(mm_slot); |
b46e756f KS |
1939 | |
1940 | mm = mm_slot->mm; | |
3b454ad3 YS |
1941 | /* |
1942 | * Don't wait for semaphore (to avoid long wait times). Just move to | |
1943 | * the next mm on the list. | |
1944 | */ | |
1945 | vma = NULL; | |
1946 | if (unlikely(!down_read_trylock(&mm->mmap_sem))) | |
1947 | goto breakouterloop_mmap_sem; | |
1948 | if (likely(!khugepaged_test_exit(mm))) | |
b46e756f KS |
1949 | vma = find_vma(mm, khugepaged_scan.address); |
1950 | ||
1951 | progress++; | |
1952 | for (; vma; vma = vma->vm_next) { | |
1953 | unsigned long hstart, hend; | |
1954 | ||
1955 | cond_resched(); | |
1956 | if (unlikely(khugepaged_test_exit(mm))) { | |
1957 | progress++; | |
1958 | break; | |
1959 | } | |
50f8b92f | 1960 | if (!hugepage_vma_check(vma, vma->vm_flags)) { |
b46e756f KS |
1961 | skip: |
1962 | progress++; | |
1963 | continue; | |
1964 | } | |
1965 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
1966 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1967 | if (hstart >= hend) | |
1968 | goto skip; | |
1969 | if (khugepaged_scan.address > hend) | |
1970 | goto skip; | |
1971 | if (khugepaged_scan.address < hstart) | |
1972 | khugepaged_scan.address = hstart; | |
1973 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); | |
1974 | ||
1975 | while (khugepaged_scan.address < hend) { | |
1976 | int ret; | |
1977 | cond_resched(); | |
1978 | if (unlikely(khugepaged_test_exit(mm))) | |
1979 | goto breakouterloop; | |
1980 | ||
1981 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
1982 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
1983 | hend); | |
99cb0dbd | 1984 | if (IS_ENABLED(CONFIG_SHMEM) && vma->vm_file) { |
e496cf3d | 1985 | struct file *file; |
f3f0e1d2 KS |
1986 | pgoff_t pgoff = linear_page_index(vma, |
1987 | khugepaged_scan.address); | |
99cb0dbd SL |
1988 | |
1989 | if (shmem_file(vma->vm_file) | |
1990 | && !shmem_huge_enabled(vma)) | |
e496cf3d KS |
1991 | goto skip; |
1992 | file = get_file(vma->vm_file); | |
f3f0e1d2 KS |
1993 | up_read(&mm->mmap_sem); |
1994 | ret = 1; | |
579c571e | 1995 | khugepaged_scan_file(mm, file, pgoff, hpage); |
f3f0e1d2 KS |
1996 | fput(file); |
1997 | } else { | |
1998 | ret = khugepaged_scan_pmd(mm, vma, | |
1999 | khugepaged_scan.address, | |
2000 | hpage); | |
2001 | } | |
b46e756f KS |
2002 | /* move to next address */ |
2003 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2004 | progress += HPAGE_PMD_NR; | |
2005 | if (ret) | |
2006 | /* we released mmap_sem so break loop */ | |
2007 | goto breakouterloop_mmap_sem; | |
2008 | if (progress >= pages) | |
2009 | goto breakouterloop; | |
2010 | } | |
2011 | } | |
2012 | breakouterloop: | |
2013 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2014 | breakouterloop_mmap_sem: | |
2015 | ||
2016 | spin_lock(&khugepaged_mm_lock); | |
2017 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); | |
2018 | /* | |
2019 | * Release the current mm_slot if this mm is about to die, or | |
2020 | * if we scanned all vmas of this mm. | |
2021 | */ | |
2022 | if (khugepaged_test_exit(mm) || !vma) { | |
2023 | /* | |
2024 | * Make sure that if mm_users is reaching zero while | |
2025 | * khugepaged runs here, khugepaged_exit will find | |
2026 | * mm_slot not pointing to the exiting mm. | |
2027 | */ | |
2028 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2029 | khugepaged_scan.mm_slot = list_entry( | |
2030 | mm_slot->mm_node.next, | |
2031 | struct mm_slot, mm_node); | |
2032 | khugepaged_scan.address = 0; | |
2033 | } else { | |
2034 | khugepaged_scan.mm_slot = NULL; | |
2035 | khugepaged_full_scans++; | |
2036 | } | |
2037 | ||
2038 | collect_mm_slot(mm_slot); | |
2039 | } | |
2040 | ||
2041 | return progress; | |
2042 | } | |
2043 | ||
2044 | static int khugepaged_has_work(void) | |
2045 | { | |
2046 | return !list_empty(&khugepaged_scan.mm_head) && | |
2047 | khugepaged_enabled(); | |
2048 | } | |
2049 | ||
2050 | static int khugepaged_wait_event(void) | |
2051 | { | |
2052 | return !list_empty(&khugepaged_scan.mm_head) || | |
2053 | kthread_should_stop(); | |
2054 | } | |
2055 | ||
2056 | static void khugepaged_do_scan(void) | |
2057 | { | |
2058 | struct page *hpage = NULL; | |
2059 | unsigned int progress = 0, pass_through_head = 0; | |
2060 | unsigned int pages = khugepaged_pages_to_scan; | |
2061 | bool wait = true; | |
2062 | ||
2063 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2064 | ||
2065 | while (progress < pages) { | |
2066 | if (!khugepaged_prealloc_page(&hpage, &wait)) | |
2067 | break; | |
2068 | ||
2069 | cond_resched(); | |
2070 | ||
2071 | if (unlikely(kthread_should_stop() || try_to_freeze())) | |
2072 | break; | |
2073 | ||
2074 | spin_lock(&khugepaged_mm_lock); | |
2075 | if (!khugepaged_scan.mm_slot) | |
2076 | pass_through_head++; | |
2077 | if (khugepaged_has_work() && | |
2078 | pass_through_head < 2) | |
2079 | progress += khugepaged_scan_mm_slot(pages - progress, | |
2080 | &hpage); | |
2081 | else | |
2082 | progress = pages; | |
2083 | spin_unlock(&khugepaged_mm_lock); | |
2084 | } | |
2085 | ||
2086 | if (!IS_ERR_OR_NULL(hpage)) | |
2087 | put_page(hpage); | |
2088 | } | |
2089 | ||
2090 | static bool khugepaged_should_wakeup(void) | |
2091 | { | |
2092 | return kthread_should_stop() || | |
2093 | time_after_eq(jiffies, khugepaged_sleep_expire); | |
2094 | } | |
2095 | ||
2096 | static void khugepaged_wait_work(void) | |
2097 | { | |
2098 | if (khugepaged_has_work()) { | |
2099 | const unsigned long scan_sleep_jiffies = | |
2100 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs); | |
2101 | ||
2102 | if (!scan_sleep_jiffies) | |
2103 | return; | |
2104 | ||
2105 | khugepaged_sleep_expire = jiffies + scan_sleep_jiffies; | |
2106 | wait_event_freezable_timeout(khugepaged_wait, | |
2107 | khugepaged_should_wakeup(), | |
2108 | scan_sleep_jiffies); | |
2109 | return; | |
2110 | } | |
2111 | ||
2112 | if (khugepaged_enabled()) | |
2113 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2114 | } | |
2115 | ||
2116 | static int khugepaged(void *none) | |
2117 | { | |
2118 | struct mm_slot *mm_slot; | |
2119 | ||
2120 | set_freezable(); | |
2121 | set_user_nice(current, MAX_NICE); | |
2122 | ||
2123 | while (!kthread_should_stop()) { | |
2124 | khugepaged_do_scan(); | |
2125 | khugepaged_wait_work(); | |
2126 | } | |
2127 | ||
2128 | spin_lock(&khugepaged_mm_lock); | |
2129 | mm_slot = khugepaged_scan.mm_slot; | |
2130 | khugepaged_scan.mm_slot = NULL; | |
2131 | if (mm_slot) | |
2132 | collect_mm_slot(mm_slot); | |
2133 | spin_unlock(&khugepaged_mm_lock); | |
2134 | return 0; | |
2135 | } | |
2136 | ||
2137 | static void set_recommended_min_free_kbytes(void) | |
2138 | { | |
2139 | struct zone *zone; | |
2140 | int nr_zones = 0; | |
2141 | unsigned long recommended_min; | |
2142 | ||
b7d349c7 JK |
2143 | for_each_populated_zone(zone) { |
2144 | /* | |
2145 | * We don't need to worry about fragmentation of | |
2146 | * ZONE_MOVABLE since it only has movable pages. | |
2147 | */ | |
2148 | if (zone_idx(zone) > gfp_zone(GFP_USER)) | |
2149 | continue; | |
2150 | ||
b46e756f | 2151 | nr_zones++; |
b7d349c7 | 2152 | } |
b46e756f KS |
2153 | |
2154 | /* Ensure 2 pageblocks are free to assist fragmentation avoidance */ | |
2155 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
2156 | ||
2157 | /* | |
2158 | * Make sure that on average at least two pageblocks are almost free | |
2159 | * of another type, one for a migratetype to fall back to and a | |
2160 | * second to avoid subsequent fallbacks of other types There are 3 | |
2161 | * MIGRATE_TYPES we care about. | |
2162 | */ | |
2163 | recommended_min += pageblock_nr_pages * nr_zones * | |
2164 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
2165 | ||
2166 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
2167 | recommended_min = min(recommended_min, | |
2168 | (unsigned long) nr_free_buffer_pages() / 20); | |
2169 | recommended_min <<= (PAGE_SHIFT-10); | |
2170 | ||
2171 | if (recommended_min > min_free_kbytes) { | |
2172 | if (user_min_free_kbytes >= 0) | |
2173 | pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n", | |
2174 | min_free_kbytes, recommended_min); | |
2175 | ||
2176 | min_free_kbytes = recommended_min; | |
2177 | } | |
2178 | setup_per_zone_wmarks(); | |
2179 | } | |
2180 | ||
2181 | int start_stop_khugepaged(void) | |
2182 | { | |
b46e756f KS |
2183 | int err = 0; |
2184 | ||
2185 | mutex_lock(&khugepaged_mutex); | |
2186 | if (khugepaged_enabled()) { | |
2187 | if (!khugepaged_thread) | |
2188 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
2189 | "khugepaged"); | |
2190 | if (IS_ERR(khugepaged_thread)) { | |
2191 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); | |
2192 | err = PTR_ERR(khugepaged_thread); | |
2193 | khugepaged_thread = NULL; | |
2194 | goto fail; | |
2195 | } | |
2196 | ||
2197 | if (!list_empty(&khugepaged_scan.mm_head)) | |
2198 | wake_up_interruptible(&khugepaged_wait); | |
2199 | ||
2200 | set_recommended_min_free_kbytes(); | |
2201 | } else if (khugepaged_thread) { | |
2202 | kthread_stop(khugepaged_thread); | |
2203 | khugepaged_thread = NULL; | |
2204 | } | |
2205 | fail: | |
2206 | mutex_unlock(&khugepaged_mutex); | |
2207 | return err; | |
2208 | } | |
e2c01fd0 VB |
2209 | |
2210 | void khugepaged_min_free_kbytes_update(void) | |
2211 | { | |
2212 | mutex_lock(&khugepaged_mutex); | |
2213 | if (khugepaged_enabled() && khugepaged_thread) | |
2214 | set_recommended_min_free_kbytes(); | |
2215 | mutex_unlock(&khugepaged_mutex); | |
2216 | } |