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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, | |
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 | ||
4aab2be0 VB |
59 | static struct task_struct *khugepaged_thread __read_mostly; |
60 | static DEFINE_MUTEX(khugepaged_mutex); | |
61 | ||
b46e756f KS |
62 | /* default scan 8*512 pte (or vmas) every 30 second */ |
63 | static unsigned int khugepaged_pages_to_scan __read_mostly; | |
64 | static unsigned int khugepaged_pages_collapsed; | |
65 | static unsigned int khugepaged_full_scans; | |
66 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
67 | /* during fragmentation poll the hugepage allocator once every minute */ | |
68 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
69 | static unsigned long khugepaged_sleep_expire; | |
70 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
71 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
72 | /* | |
73 | * default collapse hugepages if there is at least one pte mapped like | |
74 | * it would have happened if the vma was large enough during page | |
75 | * fault. | |
76 | */ | |
77 | static unsigned int khugepaged_max_ptes_none __read_mostly; | |
78 | static unsigned int khugepaged_max_ptes_swap __read_mostly; | |
71a2c112 | 79 | static unsigned int khugepaged_max_ptes_shared __read_mostly; |
b46e756f KS |
80 | |
81 | #define MM_SLOTS_HASH_BITS 10 | |
82 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
83 | ||
84 | static struct kmem_cache *mm_slot_cache __read_mostly; | |
85 | ||
27e1f827 SL |
86 | #define MAX_PTE_MAPPED_THP 8 |
87 | ||
b46e756f KS |
88 | /** |
89 | * struct mm_slot - hash lookup from mm to mm_slot | |
90 | * @hash: hash collision list | |
91 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
92 | * @mm: the mm that this information is valid for | |
336e6b53 AS |
93 | * @nr_pte_mapped_thp: number of pte mapped THP |
94 | * @pte_mapped_thp: address array corresponding pte mapped THP | |
b46e756f KS |
95 | */ |
96 | struct mm_slot { | |
97 | struct hlist_node hash; | |
98 | struct list_head mm_node; | |
99 | struct mm_struct *mm; | |
27e1f827 SL |
100 | |
101 | /* pte-mapped THP in this mm */ | |
102 | int nr_pte_mapped_thp; | |
103 | unsigned long pte_mapped_thp[MAX_PTE_MAPPED_THP]; | |
b46e756f KS |
104 | }; |
105 | ||
106 | /** | |
107 | * struct khugepaged_scan - cursor for scanning | |
108 | * @mm_head: the head of the mm list to scan | |
109 | * @mm_slot: the current mm_slot we are scanning | |
110 | * @address: the next address inside that to be scanned | |
111 | * | |
112 | * There is only the one khugepaged_scan instance of this cursor structure. | |
113 | */ | |
114 | struct khugepaged_scan { | |
115 | struct list_head mm_head; | |
116 | struct mm_slot *mm_slot; | |
117 | unsigned long address; | |
118 | }; | |
119 | ||
120 | static struct khugepaged_scan khugepaged_scan = { | |
121 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), | |
122 | }; | |
123 | ||
e1465d12 | 124 | #ifdef CONFIG_SYSFS |
b46e756f KS |
125 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, |
126 | struct kobj_attribute *attr, | |
127 | char *buf) | |
128 | { | |
ae7a927d | 129 | return sysfs_emit(buf, "%u\n", khugepaged_scan_sleep_millisecs); |
b46e756f KS |
130 | } |
131 | ||
132 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
133 | struct kobj_attribute *attr, | |
134 | const char *buf, size_t count) | |
135 | { | |
dfefd226 | 136 | unsigned int msecs; |
b46e756f KS |
137 | int err; |
138 | ||
dfefd226 AD |
139 | err = kstrtouint(buf, 10, &msecs); |
140 | if (err) | |
b46e756f KS |
141 | return -EINVAL; |
142 | ||
143 | khugepaged_scan_sleep_millisecs = msecs; | |
144 | khugepaged_sleep_expire = 0; | |
145 | wake_up_interruptible(&khugepaged_wait); | |
146 | ||
147 | return count; | |
148 | } | |
149 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
150 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
151 | scan_sleep_millisecs_store); | |
152 | ||
153 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
154 | struct kobj_attribute *attr, | |
155 | char *buf) | |
156 | { | |
ae7a927d | 157 | return sysfs_emit(buf, "%u\n", khugepaged_alloc_sleep_millisecs); |
b46e756f KS |
158 | } |
159 | ||
160 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
161 | struct kobj_attribute *attr, | |
162 | const char *buf, size_t count) | |
163 | { | |
dfefd226 | 164 | unsigned int msecs; |
b46e756f KS |
165 | int err; |
166 | ||
dfefd226 AD |
167 | err = kstrtouint(buf, 10, &msecs); |
168 | if (err) | |
b46e756f KS |
169 | return -EINVAL; |
170 | ||
171 | khugepaged_alloc_sleep_millisecs = msecs; | |
172 | khugepaged_sleep_expire = 0; | |
173 | wake_up_interruptible(&khugepaged_wait); | |
174 | ||
175 | return count; | |
176 | } | |
177 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
178 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
179 | alloc_sleep_millisecs_store); | |
180 | ||
181 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
182 | struct kobj_attribute *attr, | |
183 | char *buf) | |
184 | { | |
ae7a927d | 185 | return sysfs_emit(buf, "%u\n", khugepaged_pages_to_scan); |
b46e756f KS |
186 | } |
187 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
188 | struct kobj_attribute *attr, | |
189 | const char *buf, size_t count) | |
190 | { | |
dfefd226 | 191 | unsigned int pages; |
b46e756f | 192 | int err; |
b46e756f | 193 | |
dfefd226 AD |
194 | err = kstrtouint(buf, 10, &pages); |
195 | if (err || !pages) | |
b46e756f KS |
196 | return -EINVAL; |
197 | ||
198 | khugepaged_pages_to_scan = pages; | |
199 | ||
200 | return count; | |
201 | } | |
202 | static struct kobj_attribute pages_to_scan_attr = | |
203 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
204 | pages_to_scan_store); | |
205 | ||
206 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
207 | struct kobj_attribute *attr, | |
208 | char *buf) | |
209 | { | |
ae7a927d | 210 | return sysfs_emit(buf, "%u\n", khugepaged_pages_collapsed); |
b46e756f KS |
211 | } |
212 | static struct kobj_attribute pages_collapsed_attr = | |
213 | __ATTR_RO(pages_collapsed); | |
214 | ||
215 | static ssize_t full_scans_show(struct kobject *kobj, | |
216 | struct kobj_attribute *attr, | |
217 | char *buf) | |
218 | { | |
ae7a927d | 219 | return sysfs_emit(buf, "%u\n", khugepaged_full_scans); |
b46e756f KS |
220 | } |
221 | static struct kobj_attribute full_scans_attr = | |
222 | __ATTR_RO(full_scans); | |
223 | ||
224 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
225 | struct kobj_attribute *attr, char *buf) | |
226 | { | |
227 | return single_hugepage_flag_show(kobj, attr, buf, | |
ae7a927d | 228 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); |
b46e756f KS |
229 | } |
230 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
231 | struct kobj_attribute *attr, | |
232 | const char *buf, size_t count) | |
233 | { | |
234 | return single_hugepage_flag_store(kobj, attr, buf, count, | |
235 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
236 | } | |
237 | static struct kobj_attribute khugepaged_defrag_attr = | |
238 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
239 | khugepaged_defrag_store); | |
240 | ||
241 | /* | |
242 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
243 | * any unmapped ptes in turn potentially increasing the memory | |
244 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
245 | * reduce the available free memory in the system as it | |
246 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
247 | * free memory in the system during the khugepaged scan. | |
248 | */ | |
249 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
250 | struct kobj_attribute *attr, | |
251 | char *buf) | |
252 | { | |
ae7a927d | 253 | return sysfs_emit(buf, "%u\n", khugepaged_max_ptes_none); |
b46e756f KS |
254 | } |
255 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
256 | struct kobj_attribute *attr, | |
257 | const char *buf, size_t count) | |
258 | { | |
259 | int err; | |
260 | unsigned long max_ptes_none; | |
261 | ||
262 | err = kstrtoul(buf, 10, &max_ptes_none); | |
263 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
264 | return -EINVAL; | |
265 | ||
266 | khugepaged_max_ptes_none = max_ptes_none; | |
267 | ||
268 | return count; | |
269 | } | |
270 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
271 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
272 | khugepaged_max_ptes_none_store); | |
273 | ||
274 | static ssize_t khugepaged_max_ptes_swap_show(struct kobject *kobj, | |
275 | struct kobj_attribute *attr, | |
276 | char *buf) | |
277 | { | |
ae7a927d | 278 | return sysfs_emit(buf, "%u\n", khugepaged_max_ptes_swap); |
b46e756f KS |
279 | } |
280 | ||
281 | static ssize_t khugepaged_max_ptes_swap_store(struct kobject *kobj, | |
282 | struct kobj_attribute *attr, | |
283 | const char *buf, size_t count) | |
284 | { | |
285 | int err; | |
286 | unsigned long max_ptes_swap; | |
287 | ||
288 | err = kstrtoul(buf, 10, &max_ptes_swap); | |
289 | if (err || max_ptes_swap > HPAGE_PMD_NR-1) | |
290 | return -EINVAL; | |
291 | ||
292 | khugepaged_max_ptes_swap = max_ptes_swap; | |
293 | ||
294 | return count; | |
295 | } | |
296 | ||
297 | static struct kobj_attribute khugepaged_max_ptes_swap_attr = | |
298 | __ATTR(max_ptes_swap, 0644, khugepaged_max_ptes_swap_show, | |
299 | khugepaged_max_ptes_swap_store); | |
300 | ||
71a2c112 | 301 | static ssize_t khugepaged_max_ptes_shared_show(struct kobject *kobj, |
ae7a927d JP |
302 | struct kobj_attribute *attr, |
303 | char *buf) | |
71a2c112 | 304 | { |
ae7a927d | 305 | return sysfs_emit(buf, "%u\n", khugepaged_max_ptes_shared); |
71a2c112 KS |
306 | } |
307 | ||
308 | static ssize_t khugepaged_max_ptes_shared_store(struct kobject *kobj, | |
309 | struct kobj_attribute *attr, | |
310 | const char *buf, size_t count) | |
311 | { | |
312 | int err; | |
313 | unsigned long max_ptes_shared; | |
314 | ||
315 | err = kstrtoul(buf, 10, &max_ptes_shared); | |
316 | if (err || max_ptes_shared > HPAGE_PMD_NR-1) | |
317 | return -EINVAL; | |
318 | ||
319 | khugepaged_max_ptes_shared = max_ptes_shared; | |
320 | ||
321 | return count; | |
322 | } | |
323 | ||
324 | static struct kobj_attribute khugepaged_max_ptes_shared_attr = | |
325 | __ATTR(max_ptes_shared, 0644, khugepaged_max_ptes_shared_show, | |
326 | khugepaged_max_ptes_shared_store); | |
327 | ||
b46e756f KS |
328 | static struct attribute *khugepaged_attr[] = { |
329 | &khugepaged_defrag_attr.attr, | |
330 | &khugepaged_max_ptes_none_attr.attr, | |
71a2c112 KS |
331 | &khugepaged_max_ptes_swap_attr.attr, |
332 | &khugepaged_max_ptes_shared_attr.attr, | |
b46e756f KS |
333 | &pages_to_scan_attr.attr, |
334 | &pages_collapsed_attr.attr, | |
335 | &full_scans_attr.attr, | |
336 | &scan_sleep_millisecs_attr.attr, | |
337 | &alloc_sleep_millisecs_attr.attr, | |
b46e756f KS |
338 | NULL, |
339 | }; | |
340 | ||
341 | struct attribute_group khugepaged_attr_group = { | |
342 | .attrs = khugepaged_attr, | |
343 | .name = "khugepaged", | |
344 | }; | |
e1465d12 | 345 | #endif /* CONFIG_SYSFS */ |
b46e756f | 346 | |
b46e756f KS |
347 | int hugepage_madvise(struct vm_area_struct *vma, |
348 | unsigned long *vm_flags, int advice) | |
349 | { | |
350 | switch (advice) { | |
351 | case MADV_HUGEPAGE: | |
352 | #ifdef CONFIG_S390 | |
353 | /* | |
354 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
355 | * can't handle this properly after s390_enable_sie, so we simply | |
356 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
357 | */ | |
358 | if (mm_has_pgste(vma->vm_mm)) | |
359 | return 0; | |
360 | #endif | |
361 | *vm_flags &= ~VM_NOHUGEPAGE; | |
362 | *vm_flags |= VM_HUGEPAGE; | |
363 | /* | |
364 | * If the vma become good for khugepaged to scan, | |
365 | * register it here without waiting a page fault that | |
366 | * may not happen any time soon. | |
367 | */ | |
368 | if (!(*vm_flags & VM_NO_KHUGEPAGED) && | |
369 | khugepaged_enter_vma_merge(vma, *vm_flags)) | |
370 | return -ENOMEM; | |
371 | break; | |
372 | case MADV_NOHUGEPAGE: | |
373 | *vm_flags &= ~VM_HUGEPAGE; | |
374 | *vm_flags |= VM_NOHUGEPAGE; | |
375 | /* | |
376 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
377 | * this vma even if we leave the mm registered in khugepaged if | |
378 | * it got registered before VM_NOHUGEPAGE was set. | |
379 | */ | |
380 | break; | |
381 | } | |
382 | ||
383 | return 0; | |
384 | } | |
385 | ||
386 | int __init khugepaged_init(void) | |
387 | { | |
388 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
389 | sizeof(struct mm_slot), | |
390 | __alignof__(struct mm_slot), 0, NULL); | |
391 | if (!mm_slot_cache) | |
392 | return -ENOMEM; | |
393 | ||
394 | khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; | |
395 | khugepaged_max_ptes_none = HPAGE_PMD_NR - 1; | |
396 | khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8; | |
71a2c112 | 397 | khugepaged_max_ptes_shared = HPAGE_PMD_NR / 2; |
b46e756f KS |
398 | |
399 | return 0; | |
400 | } | |
401 | ||
402 | void __init khugepaged_destroy(void) | |
403 | { | |
404 | kmem_cache_destroy(mm_slot_cache); | |
405 | } | |
406 | ||
407 | static inline struct mm_slot *alloc_mm_slot(void) | |
408 | { | |
409 | if (!mm_slot_cache) /* initialization failed */ | |
410 | return NULL; | |
411 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
412 | } | |
413 | ||
414 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
415 | { | |
416 | kmem_cache_free(mm_slot_cache, mm_slot); | |
417 | } | |
418 | ||
419 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
420 | { | |
421 | struct mm_slot *mm_slot; | |
422 | ||
423 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) | |
424 | if (mm == mm_slot->mm) | |
425 | return mm_slot; | |
426 | ||
427 | return NULL; | |
428 | } | |
429 | ||
430 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
431 | struct mm_slot *mm_slot) | |
432 | { | |
433 | mm_slot->mm = mm; | |
434 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); | |
435 | } | |
436 | ||
437 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
438 | { | |
4d45e75a | 439 | return atomic_read(&mm->mm_users) == 0; |
b46e756f KS |
440 | } |
441 | ||
50f8b92f SL |
442 | static bool hugepage_vma_check(struct vm_area_struct *vma, |
443 | unsigned long vm_flags) | |
c2231020 | 444 | { |
cd89fb06 RR |
445 | /* Explicitly disabled through madvise. */ |
446 | if ((vm_flags & VM_NOHUGEPAGE) || | |
c2231020 YS |
447 | test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) |
448 | return false; | |
99cb0dbd | 449 | |
cd89fb06 RR |
450 | /* Enabled via shmem mount options or sysfs settings. */ |
451 | if (shmem_file(vma->vm_file) && shmem_huge_enabled(vma)) { | |
c2231020 YS |
452 | return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, |
453 | HPAGE_PMD_NR); | |
454 | } | |
cd89fb06 RR |
455 | |
456 | /* THP settings require madvise. */ | |
457 | if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) | |
458 | return false; | |
459 | ||
460 | /* Read-only file mappings need to be aligned for THP to work. */ | |
461 | if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && vma->vm_file && | |
462 | (vm_flags & VM_DENYWRITE)) { | |
463 | return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, | |
464 | HPAGE_PMD_NR); | |
465 | } | |
466 | ||
c2231020 YS |
467 | if (!vma->anon_vma || vma->vm_ops) |
468 | return false; | |
222100ee | 469 | if (vma_is_temporary_stack(vma)) |
c2231020 | 470 | return false; |
50f8b92f | 471 | return !(vm_flags & VM_NO_KHUGEPAGED); |
c2231020 YS |
472 | } |
473 | ||
b46e756f KS |
474 | int __khugepaged_enter(struct mm_struct *mm) |
475 | { | |
476 | struct mm_slot *mm_slot; | |
477 | int wakeup; | |
478 | ||
479 | mm_slot = alloc_mm_slot(); | |
480 | if (!mm_slot) | |
481 | return -ENOMEM; | |
482 | ||
483 | /* __khugepaged_exit() must not run from under us */ | |
f3f99d63 | 484 | VM_BUG_ON_MM(atomic_read(&mm->mm_users) == 0, mm); |
b46e756f KS |
485 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { |
486 | free_mm_slot(mm_slot); | |
487 | return 0; | |
488 | } | |
489 | ||
490 | spin_lock(&khugepaged_mm_lock); | |
491 | insert_to_mm_slots_hash(mm, mm_slot); | |
492 | /* | |
493 | * Insert just behind the scanning cursor, to let the area settle | |
494 | * down a little. | |
495 | */ | |
496 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
497 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
498 | spin_unlock(&khugepaged_mm_lock); | |
499 | ||
f1f10076 | 500 | mmgrab(mm); |
b46e756f KS |
501 | if (wakeup) |
502 | wake_up_interruptible(&khugepaged_wait); | |
503 | ||
504 | return 0; | |
505 | } | |
506 | ||
507 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, | |
508 | unsigned long vm_flags) | |
509 | { | |
510 | unsigned long hstart, hend; | |
c2231020 YS |
511 | |
512 | /* | |
99cb0dbd SL |
513 | * khugepaged only supports read-only files for non-shmem files. |
514 | * khugepaged does not yet work on special mappings. And | |
515 | * file-private shmem THP is not supported. | |
c2231020 | 516 | */ |
50f8b92f | 517 | if (!hugepage_vma_check(vma, vm_flags)) |
b46e756f | 518 | return 0; |
c2231020 | 519 | |
b46e756f KS |
520 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
521 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
522 | if (hstart < hend) | |
523 | return khugepaged_enter(vma, vm_flags); | |
524 | return 0; | |
525 | } | |
526 | ||
527 | void __khugepaged_exit(struct mm_struct *mm) | |
528 | { | |
529 | struct mm_slot *mm_slot; | |
530 | int free = 0; | |
531 | ||
532 | spin_lock(&khugepaged_mm_lock); | |
533 | mm_slot = get_mm_slot(mm); | |
534 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
535 | hash_del(&mm_slot->hash); | |
536 | list_del(&mm_slot->mm_node); | |
537 | free = 1; | |
538 | } | |
539 | spin_unlock(&khugepaged_mm_lock); | |
540 | ||
541 | if (free) { | |
542 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
543 | free_mm_slot(mm_slot); | |
544 | mmdrop(mm); | |
545 | } else if (mm_slot) { | |
546 | /* | |
547 | * This is required to serialize against | |
548 | * khugepaged_test_exit() (which is guaranteed to run | |
549 | * under mmap sem read mode). Stop here (after we | |
550 | * return all pagetables will be destroyed) until | |
551 | * khugepaged has finished working on the pagetables | |
c1e8d7c6 | 552 | * under the mmap_lock. |
b46e756f | 553 | */ |
d8ed45c5 ML |
554 | mmap_write_lock(mm); |
555 | mmap_write_unlock(mm); | |
b46e756f KS |
556 | } |
557 | } | |
558 | ||
559 | static void release_pte_page(struct page *page) | |
560 | { | |
5503fbf2 KS |
561 | mod_node_page_state(page_pgdat(page), |
562 | NR_ISOLATED_ANON + page_is_file_lru(page), | |
563 | -compound_nr(page)); | |
b46e756f KS |
564 | unlock_page(page); |
565 | putback_lru_page(page); | |
566 | } | |
567 | ||
5503fbf2 KS |
568 | static void release_pte_pages(pte_t *pte, pte_t *_pte, |
569 | struct list_head *compound_pagelist) | |
b46e756f | 570 | { |
5503fbf2 KS |
571 | struct page *page, *tmp; |
572 | ||
b46e756f KS |
573 | while (--_pte >= pte) { |
574 | pte_t pteval = *_pte; | |
5503fbf2 KS |
575 | |
576 | page = pte_page(pteval); | |
577 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)) && | |
578 | !PageCompound(page)) | |
579 | release_pte_page(page); | |
580 | } | |
581 | ||
582 | list_for_each_entry_safe(page, tmp, compound_pagelist, lru) { | |
583 | list_del(&page->lru); | |
584 | release_pte_page(page); | |
b46e756f KS |
585 | } |
586 | } | |
587 | ||
9445689f KS |
588 | static bool is_refcount_suitable(struct page *page) |
589 | { | |
590 | int expected_refcount; | |
591 | ||
592 | expected_refcount = total_mapcount(page); | |
593 | if (PageSwapCache(page)) | |
594 | expected_refcount += compound_nr(page); | |
595 | ||
596 | return page_count(page) == expected_refcount; | |
597 | } | |
598 | ||
b46e756f KS |
599 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, |
600 | unsigned long address, | |
5503fbf2 KS |
601 | pte_t *pte, |
602 | struct list_head *compound_pagelist) | |
b46e756f KS |
603 | { |
604 | struct page *page = NULL; | |
605 | pte_t *_pte; | |
71a2c112 | 606 | int none_or_zero = 0, shared = 0, result = 0, referenced = 0; |
0db501f7 | 607 | bool writable = false; |
b46e756f KS |
608 | |
609 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
610 | _pte++, address += PAGE_SIZE) { | |
611 | pte_t pteval = *_pte; | |
612 | if (pte_none(pteval) || (pte_present(pteval) && | |
613 | is_zero_pfn(pte_pfn(pteval)))) { | |
614 | if (!userfaultfd_armed(vma) && | |
615 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
616 | continue; | |
617 | } else { | |
618 | result = SCAN_EXCEED_NONE_PTE; | |
619 | goto out; | |
620 | } | |
621 | } | |
622 | if (!pte_present(pteval)) { | |
623 | result = SCAN_PTE_NON_PRESENT; | |
624 | goto out; | |
625 | } | |
626 | page = vm_normal_page(vma, address, pteval); | |
627 | if (unlikely(!page)) { | |
628 | result = SCAN_PAGE_NULL; | |
629 | goto out; | |
630 | } | |
631 | ||
5503fbf2 KS |
632 | VM_BUG_ON_PAGE(!PageAnon(page), page); |
633 | ||
71a2c112 KS |
634 | if (page_mapcount(page) > 1 && |
635 | ++shared > khugepaged_max_ptes_shared) { | |
636 | result = SCAN_EXCEED_SHARED_PTE; | |
637 | goto out; | |
638 | } | |
639 | ||
fece2029 | 640 | if (PageCompound(page)) { |
5503fbf2 KS |
641 | struct page *p; |
642 | page = compound_head(page); | |
fece2029 | 643 | |
5503fbf2 KS |
644 | /* |
645 | * Check if we have dealt with the compound page | |
646 | * already | |
647 | */ | |
648 | list_for_each_entry(p, compound_pagelist, lru) { | |
649 | if (page == p) | |
650 | goto next; | |
651 | } | |
652 | } | |
b46e756f KS |
653 | |
654 | /* | |
655 | * We can do it before isolate_lru_page because the | |
656 | * page can't be freed from under us. NOTE: PG_lock | |
657 | * is needed to serialize against split_huge_page | |
658 | * when invoked from the VM. | |
659 | */ | |
660 | if (!trylock_page(page)) { | |
661 | result = SCAN_PAGE_LOCK; | |
662 | goto out; | |
663 | } | |
664 | ||
665 | /* | |
9445689f KS |
666 | * Check if the page has any GUP (or other external) pins. |
667 | * | |
668 | * The page table that maps the page has been already unlinked | |
669 | * from the page table tree and this process cannot get | |
670 | * an additinal pin on the page. | |
671 | * | |
672 | * New pins can come later if the page is shared across fork, | |
673 | * but not from this process. The other process cannot write to | |
674 | * the page, only trigger CoW. | |
b46e756f | 675 | */ |
9445689f | 676 | if (!is_refcount_suitable(page)) { |
b46e756f KS |
677 | unlock_page(page); |
678 | result = SCAN_PAGE_COUNT; | |
679 | goto out; | |
680 | } | |
5503fbf2 KS |
681 | if (!pte_write(pteval) && PageSwapCache(page) && |
682 | !reuse_swap_page(page, NULL)) { | |
b46e756f | 683 | /* |
5503fbf2 KS |
684 | * Page is in the swap cache and cannot be re-used. |
685 | * It cannot be collapsed into a THP. | |
b46e756f | 686 | */ |
5503fbf2 KS |
687 | unlock_page(page); |
688 | result = SCAN_SWAP_CACHE_PAGE; | |
689 | goto out; | |
b46e756f KS |
690 | } |
691 | ||
692 | /* | |
693 | * Isolate the page to avoid collapsing an hugepage | |
694 | * currently in use by the VM. | |
695 | */ | |
696 | if (isolate_lru_page(page)) { | |
697 | unlock_page(page); | |
698 | result = SCAN_DEL_PAGE_LRU; | |
699 | goto out; | |
700 | } | |
5503fbf2 KS |
701 | mod_node_page_state(page_pgdat(page), |
702 | NR_ISOLATED_ANON + page_is_file_lru(page), | |
703 | compound_nr(page)); | |
b46e756f KS |
704 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
705 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
706 | ||
5503fbf2 KS |
707 | if (PageCompound(page)) |
708 | list_add_tail(&page->lru, compound_pagelist); | |
709 | next: | |
0db501f7 | 710 | /* There should be enough young pte to collapse the page */ |
b46e756f KS |
711 | if (pte_young(pteval) || |
712 | page_is_young(page) || PageReferenced(page) || | |
713 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 714 | referenced++; |
5503fbf2 KS |
715 | |
716 | if (pte_write(pteval)) | |
717 | writable = true; | |
b46e756f KS |
718 | } |
719 | if (likely(writable)) { | |
720 | if (likely(referenced)) { | |
721 | result = SCAN_SUCCEED; | |
722 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, | |
723 | referenced, writable, result); | |
724 | return 1; | |
725 | } | |
726 | } else { | |
727 | result = SCAN_PAGE_RO; | |
728 | } | |
729 | ||
730 | out: | |
5503fbf2 | 731 | release_pte_pages(pte, _pte, compound_pagelist); |
b46e756f KS |
732 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, |
733 | referenced, writable, result); | |
734 | return 0; | |
735 | } | |
736 | ||
737 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
738 | struct vm_area_struct *vma, | |
739 | unsigned long address, | |
5503fbf2 KS |
740 | spinlock_t *ptl, |
741 | struct list_head *compound_pagelist) | |
b46e756f | 742 | { |
5503fbf2 | 743 | struct page *src_page, *tmp; |
b46e756f | 744 | pte_t *_pte; |
338a16ba DR |
745 | for (_pte = pte; _pte < pte + HPAGE_PMD_NR; |
746 | _pte++, page++, address += PAGE_SIZE) { | |
b46e756f | 747 | pte_t pteval = *_pte; |
b46e756f KS |
748 | |
749 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
750 | clear_user_highpage(page, address); | |
751 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
752 | if (is_zero_pfn(pte_pfn(pteval))) { | |
753 | /* | |
754 | * ptl mostly unnecessary. | |
755 | */ | |
756 | spin_lock(ptl); | |
757 | /* | |
758 | * paravirt calls inside pte_clear here are | |
759 | * superfluous. | |
760 | */ | |
761 | pte_clear(vma->vm_mm, address, _pte); | |
762 | spin_unlock(ptl); | |
763 | } | |
764 | } else { | |
765 | src_page = pte_page(pteval); | |
766 | copy_user_highpage(page, src_page, address, vma); | |
5503fbf2 KS |
767 | if (!PageCompound(src_page)) |
768 | release_pte_page(src_page); | |
b46e756f KS |
769 | /* |
770 | * ptl mostly unnecessary, but preempt has to | |
771 | * be disabled to update the per-cpu stats | |
772 | * inside page_remove_rmap(). | |
773 | */ | |
774 | spin_lock(ptl); | |
775 | /* | |
776 | * paravirt calls inside pte_clear here are | |
777 | * superfluous. | |
778 | */ | |
779 | pte_clear(vma->vm_mm, address, _pte); | |
780 | page_remove_rmap(src_page, false); | |
781 | spin_unlock(ptl); | |
782 | free_page_and_swap_cache(src_page); | |
783 | } | |
b46e756f | 784 | } |
5503fbf2 KS |
785 | |
786 | list_for_each_entry_safe(src_page, tmp, compound_pagelist, lru) { | |
787 | list_del(&src_page->lru); | |
788 | release_pte_page(src_page); | |
789 | } | |
b46e756f KS |
790 | } |
791 | ||
792 | static void khugepaged_alloc_sleep(void) | |
793 | { | |
794 | DEFINE_WAIT(wait); | |
795 | ||
796 | add_wait_queue(&khugepaged_wait, &wait); | |
797 | freezable_schedule_timeout_interruptible( | |
798 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
799 | remove_wait_queue(&khugepaged_wait, &wait); | |
800 | } | |
801 | ||
802 | static int khugepaged_node_load[MAX_NUMNODES]; | |
803 | ||
804 | static bool khugepaged_scan_abort(int nid) | |
805 | { | |
806 | int i; | |
807 | ||
808 | /* | |
a5f5f91d | 809 | * If node_reclaim_mode is disabled, then no extra effort is made to |
b46e756f KS |
810 | * allocate memory locally. |
811 | */ | |
a5f5f91d | 812 | if (!node_reclaim_mode) |
b46e756f KS |
813 | return false; |
814 | ||
815 | /* If there is a count for this node already, it must be acceptable */ | |
816 | if (khugepaged_node_load[nid]) | |
817 | return false; | |
818 | ||
819 | for (i = 0; i < MAX_NUMNODES; i++) { | |
820 | if (!khugepaged_node_load[i]) | |
821 | continue; | |
a55c7454 | 822 | if (node_distance(nid, i) > node_reclaim_distance) |
b46e756f KS |
823 | return true; |
824 | } | |
825 | return false; | |
826 | } | |
827 | ||
828 | /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */ | |
829 | static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void) | |
830 | { | |
25160354 | 831 | return khugepaged_defrag() ? GFP_TRANSHUGE : GFP_TRANSHUGE_LIGHT; |
b46e756f KS |
832 | } |
833 | ||
834 | #ifdef CONFIG_NUMA | |
835 | static int khugepaged_find_target_node(void) | |
836 | { | |
837 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
838 | int nid, target_node = 0, max_value = 0; | |
839 | ||
840 | /* find first node with max normal pages hit */ | |
841 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
842 | if (khugepaged_node_load[nid] > max_value) { | |
843 | max_value = khugepaged_node_load[nid]; | |
844 | target_node = nid; | |
845 | } | |
846 | ||
847 | /* do some balance if several nodes have the same hit record */ | |
848 | if (target_node <= last_khugepaged_target_node) | |
849 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
850 | nid++) | |
851 | if (max_value == khugepaged_node_load[nid]) { | |
852 | target_node = nid; | |
853 | break; | |
854 | } | |
855 | ||
856 | last_khugepaged_target_node = target_node; | |
857 | return target_node; | |
858 | } | |
859 | ||
860 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
861 | { | |
862 | if (IS_ERR(*hpage)) { | |
863 | if (!*wait) | |
864 | return false; | |
865 | ||
866 | *wait = false; | |
867 | *hpage = NULL; | |
868 | khugepaged_alloc_sleep(); | |
869 | } else if (*hpage) { | |
870 | put_page(*hpage); | |
871 | *hpage = NULL; | |
872 | } | |
873 | ||
874 | return true; | |
875 | } | |
876 | ||
877 | static struct page * | |
988ddb71 | 878 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f KS |
879 | { |
880 | VM_BUG_ON_PAGE(*hpage, *hpage); | |
881 | ||
b46e756f KS |
882 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); |
883 | if (unlikely(!*hpage)) { | |
884 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
885 | *hpage = ERR_PTR(-ENOMEM); | |
886 | return NULL; | |
887 | } | |
888 | ||
889 | prep_transhuge_page(*hpage); | |
890 | count_vm_event(THP_COLLAPSE_ALLOC); | |
891 | return *hpage; | |
892 | } | |
893 | #else | |
894 | static int khugepaged_find_target_node(void) | |
895 | { | |
896 | return 0; | |
897 | } | |
898 | ||
899 | static inline struct page *alloc_khugepaged_hugepage(void) | |
900 | { | |
901 | struct page *page; | |
902 | ||
903 | page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(), | |
904 | HPAGE_PMD_ORDER); | |
905 | if (page) | |
906 | prep_transhuge_page(page); | |
907 | return page; | |
908 | } | |
909 | ||
910 | static struct page *khugepaged_alloc_hugepage(bool *wait) | |
911 | { | |
912 | struct page *hpage; | |
913 | ||
914 | do { | |
915 | hpage = alloc_khugepaged_hugepage(); | |
916 | if (!hpage) { | |
917 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
918 | if (!*wait) | |
919 | return NULL; | |
920 | ||
921 | *wait = false; | |
922 | khugepaged_alloc_sleep(); | |
923 | } else | |
924 | count_vm_event(THP_COLLAPSE_ALLOC); | |
925 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
926 | ||
927 | return hpage; | |
928 | } | |
929 | ||
930 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
931 | { | |
033b5d77 HD |
932 | /* |
933 | * If the hpage allocated earlier was briefly exposed in page cache | |
934 | * before collapse_file() failed, it is possible that racing lookups | |
935 | * have not yet completed, and would then be unpleasantly surprised by | |
936 | * finding the hpage reused for the same mapping at a different offset. | |
937 | * Just release the previous allocation if there is any danger of that. | |
938 | */ | |
939 | if (*hpage && page_count(*hpage) > 1) { | |
940 | put_page(*hpage); | |
941 | *hpage = NULL; | |
942 | } | |
943 | ||
b46e756f KS |
944 | if (!*hpage) |
945 | *hpage = khugepaged_alloc_hugepage(wait); | |
946 | ||
947 | if (unlikely(!*hpage)) | |
948 | return false; | |
949 | ||
950 | return true; | |
951 | } | |
952 | ||
953 | static struct page * | |
988ddb71 | 954 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f | 955 | { |
b46e756f KS |
956 | VM_BUG_ON(!*hpage); |
957 | ||
958 | return *hpage; | |
959 | } | |
960 | #endif | |
961 | ||
b46e756f | 962 | /* |
c1e8d7c6 ML |
963 | * If mmap_lock temporarily dropped, revalidate vma |
964 | * before taking mmap_lock. | |
b46e756f KS |
965 | * Return 0 if succeeds, otherwise return none-zero |
966 | * value (scan code). | |
967 | */ | |
968 | ||
c131f751 KS |
969 | static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, |
970 | struct vm_area_struct **vmap) | |
b46e756f KS |
971 | { |
972 | struct vm_area_struct *vma; | |
973 | unsigned long hstart, hend; | |
974 | ||
975 | if (unlikely(khugepaged_test_exit(mm))) | |
976 | return SCAN_ANY_PROCESS; | |
977 | ||
c131f751 | 978 | *vmap = vma = find_vma(mm, address); |
b46e756f KS |
979 | if (!vma) |
980 | return SCAN_VMA_NULL; | |
981 | ||
982 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
983 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
984 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
985 | return SCAN_ADDRESS_RANGE; | |
50f8b92f | 986 | if (!hugepage_vma_check(vma, vma->vm_flags)) |
b46e756f | 987 | return SCAN_VMA_CHECK; |
594cced1 KS |
988 | /* Anon VMA expected */ |
989 | if (!vma->anon_vma || vma->vm_ops) | |
990 | return SCAN_VMA_CHECK; | |
b46e756f KS |
991 | return 0; |
992 | } | |
993 | ||
994 | /* | |
995 | * Bring missing pages in from swap, to complete THP collapse. | |
996 | * Only done if khugepaged_scan_pmd believes it is worthwhile. | |
997 | * | |
998 | * Called and returns without pte mapped or spinlocks held, | |
c1e8d7c6 | 999 | * but with mmap_lock held to protect against vma changes. |
b46e756f KS |
1000 | */ |
1001 | ||
1002 | static bool __collapse_huge_page_swapin(struct mm_struct *mm, | |
1003 | struct vm_area_struct *vma, | |
2b635dd3 | 1004 | unsigned long haddr, pmd_t *pmd, |
0db501f7 | 1005 | int referenced) |
b46e756f | 1006 | { |
2b740303 SJ |
1007 | int swapped_in = 0; |
1008 | vm_fault_t ret = 0; | |
2b635dd3 WD |
1009 | unsigned long address, end = haddr + (HPAGE_PMD_NR * PAGE_SIZE); |
1010 | ||
1011 | for (address = haddr; address < end; address += PAGE_SIZE) { | |
1012 | struct vm_fault vmf = { | |
1013 | .vma = vma, | |
1014 | .address = address, | |
1015 | .pgoff = linear_page_index(vma, haddr), | |
1016 | .flags = FAULT_FLAG_ALLOW_RETRY, | |
1017 | .pmd = pmd, | |
1018 | }; | |
1019 | ||
1020 | vmf.pte = pte_offset_map(pmd, address); | |
2994302b | 1021 | vmf.orig_pte = *vmf.pte; |
2b635dd3 WD |
1022 | if (!is_swap_pte(vmf.orig_pte)) { |
1023 | pte_unmap(vmf.pte); | |
b46e756f | 1024 | continue; |
2b635dd3 | 1025 | } |
b46e756f | 1026 | swapped_in++; |
2994302b | 1027 | ret = do_swap_page(&vmf); |
0db501f7 | 1028 | |
c1e8d7c6 | 1029 | /* do_swap_page returns VM_FAULT_RETRY with released mmap_lock */ |
b46e756f | 1030 | if (ret & VM_FAULT_RETRY) { |
d8ed45c5 | 1031 | mmap_read_lock(mm); |
2b635dd3 | 1032 | if (hugepage_vma_revalidate(mm, haddr, &vma)) { |
47f863ea | 1033 | /* vma is no longer available, don't continue to swapin */ |
0db501f7 | 1034 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f | 1035 | return false; |
47f863ea | 1036 | } |
b46e756f | 1037 | /* check if the pmd is still valid */ |
2b635dd3 | 1038 | if (mm_find_pmd(mm, haddr) != pmd) { |
835152a2 | 1039 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f | 1040 | return false; |
835152a2 | 1041 | } |
b46e756f KS |
1042 | } |
1043 | if (ret & VM_FAULT_ERROR) { | |
0db501f7 | 1044 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f KS |
1045 | return false; |
1046 | } | |
b46e756f | 1047 | } |
ae2c5d80 KS |
1048 | |
1049 | /* Drain LRU add pagevec to remove extra pin on the swapped in pages */ | |
1050 | if (swapped_in) | |
1051 | lru_add_drain(); | |
1052 | ||
0db501f7 | 1053 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1); |
b46e756f KS |
1054 | return true; |
1055 | } | |
1056 | ||
1057 | static void collapse_huge_page(struct mm_struct *mm, | |
1058 | unsigned long address, | |
1059 | struct page **hpage, | |
ffe945e6 | 1060 | int node, int referenced, int unmapped) |
b46e756f | 1061 | { |
5503fbf2 | 1062 | LIST_HEAD(compound_pagelist); |
b46e756f KS |
1063 | pmd_t *pmd, _pmd; |
1064 | pte_t *pte; | |
1065 | pgtable_t pgtable; | |
1066 | struct page *new_page; | |
1067 | spinlock_t *pmd_ptl, *pte_ptl; | |
1068 | int isolated = 0, result = 0; | |
c131f751 | 1069 | struct vm_area_struct *vma; |
ac46d4f3 | 1070 | struct mmu_notifier_range range; |
b46e756f KS |
1071 | gfp_t gfp; |
1072 | ||
1073 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1074 | ||
1075 | /* Only allocate from the target node */ | |
41b6167e | 1076 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
b46e756f | 1077 | |
988ddb71 | 1078 | /* |
c1e8d7c6 | 1079 | * Before allocating the hugepage, release the mmap_lock read lock. |
988ddb71 | 1080 | * The allocation can take potentially a long time if it involves |
c1e8d7c6 | 1081 | * sync compaction, and we do not need to hold the mmap_lock during |
988ddb71 KS |
1082 | * that. We will recheck the vma after taking it again in write mode. |
1083 | */ | |
d8ed45c5 | 1084 | mmap_read_unlock(mm); |
988ddb71 | 1085 | new_page = khugepaged_alloc_page(hpage, gfp, node); |
b46e756f KS |
1086 | if (!new_page) { |
1087 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
1088 | goto out_nolock; | |
1089 | } | |
1090 | ||
d9eb1ea2 | 1091 | if (unlikely(mem_cgroup_charge(new_page, mm, gfp))) { |
b46e756f KS |
1092 | result = SCAN_CGROUP_CHARGE_FAIL; |
1093 | goto out_nolock; | |
1094 | } | |
9d82c694 | 1095 | count_memcg_page_event(new_page, THP_COLLAPSE_ALLOC); |
b46e756f | 1096 | |
d8ed45c5 | 1097 | mmap_read_lock(mm); |
c131f751 | 1098 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f | 1099 | if (result) { |
d8ed45c5 | 1100 | mmap_read_unlock(mm); |
b46e756f KS |
1101 | goto out_nolock; |
1102 | } | |
1103 | ||
1104 | pmd = mm_find_pmd(mm, address); | |
1105 | if (!pmd) { | |
1106 | result = SCAN_PMD_NULL; | |
d8ed45c5 | 1107 | mmap_read_unlock(mm); |
b46e756f KS |
1108 | goto out_nolock; |
1109 | } | |
1110 | ||
1111 | /* | |
c1e8d7c6 ML |
1112 | * __collapse_huge_page_swapin always returns with mmap_lock locked. |
1113 | * If it fails, we release mmap_lock and jump out_nolock. | |
b46e756f KS |
1114 | * Continuing to collapse causes inconsistency. |
1115 | */ | |
ffe945e6 KS |
1116 | if (unmapped && !__collapse_huge_page_swapin(mm, vma, address, |
1117 | pmd, referenced)) { | |
d8ed45c5 | 1118 | mmap_read_unlock(mm); |
b46e756f KS |
1119 | goto out_nolock; |
1120 | } | |
1121 | ||
d8ed45c5 | 1122 | mmap_read_unlock(mm); |
b46e756f KS |
1123 | /* |
1124 | * Prevent all access to pagetables with the exception of | |
1125 | * gup_fast later handled by the ptep_clear_flush and the VM | |
1126 | * handled by the anon_vma lock + PG_lock. | |
1127 | */ | |
d8ed45c5 | 1128 | mmap_write_lock(mm); |
c131f751 | 1129 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f KS |
1130 | if (result) |
1131 | goto out; | |
1132 | /* check if the pmd is still valid */ | |
1133 | if (mm_find_pmd(mm, address) != pmd) | |
1134 | goto out; | |
1135 | ||
1136 | anon_vma_lock_write(vma->anon_vma); | |
1137 | ||
7269f999 | 1138 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, |
6f4f13e8 | 1139 | address, address + HPAGE_PMD_SIZE); |
ac46d4f3 | 1140 | mmu_notifier_invalidate_range_start(&range); |
ec649c9d VS |
1141 | |
1142 | pte = pte_offset_map(pmd, address); | |
1143 | pte_ptl = pte_lockptr(mm, pmd); | |
1144 | ||
b46e756f KS |
1145 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
1146 | /* | |
1147 | * After this gup_fast can't run anymore. This also removes | |
1148 | * any huge TLB entry from the CPU so we won't allow | |
1149 | * huge and small TLB entries for the same virtual address | |
1150 | * to avoid the risk of CPU bugs in that area. | |
1151 | */ | |
1152 | _pmd = pmdp_collapse_flush(vma, address, pmd); | |
1153 | spin_unlock(pmd_ptl); | |
ac46d4f3 | 1154 | mmu_notifier_invalidate_range_end(&range); |
b46e756f KS |
1155 | |
1156 | spin_lock(pte_ptl); | |
5503fbf2 KS |
1157 | isolated = __collapse_huge_page_isolate(vma, address, pte, |
1158 | &compound_pagelist); | |
b46e756f KS |
1159 | spin_unlock(pte_ptl); |
1160 | ||
1161 | if (unlikely(!isolated)) { | |
1162 | pte_unmap(pte); | |
1163 | spin_lock(pmd_ptl); | |
1164 | BUG_ON(!pmd_none(*pmd)); | |
1165 | /* | |
1166 | * We can only use set_pmd_at when establishing | |
1167 | * hugepmds and never for establishing regular pmds that | |
1168 | * points to regular pagetables. Use pmd_populate for that | |
1169 | */ | |
1170 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
1171 | spin_unlock(pmd_ptl); | |
1172 | anon_vma_unlock_write(vma->anon_vma); | |
1173 | result = SCAN_FAIL; | |
1174 | goto out; | |
1175 | } | |
1176 | ||
1177 | /* | |
1178 | * All pages are isolated and locked so anon_vma rmap | |
1179 | * can't run anymore. | |
1180 | */ | |
1181 | anon_vma_unlock_write(vma->anon_vma); | |
1182 | ||
5503fbf2 KS |
1183 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl, |
1184 | &compound_pagelist); | |
b46e756f KS |
1185 | pte_unmap(pte); |
1186 | __SetPageUptodate(new_page); | |
1187 | pgtable = pmd_pgtable(_pmd); | |
1188 | ||
1189 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); | |
f55e1014 | 1190 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); |
b46e756f KS |
1191 | |
1192 | /* | |
1193 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
1194 | * this is needed to avoid the copy_huge_page writes to become | |
1195 | * visible after the set_pmd_at() write. | |
1196 | */ | |
1197 | smp_wmb(); | |
1198 | ||
1199 | spin_lock(pmd_ptl); | |
1200 | BUG_ON(!pmd_none(*pmd)); | |
be5d0a74 | 1201 | page_add_new_anon_rmap(new_page, vma, address, true); |
b518154e | 1202 | lru_cache_add_inactive_or_unevictable(new_page, vma); |
b46e756f KS |
1203 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
1204 | set_pmd_at(mm, address, pmd, _pmd); | |
1205 | update_mmu_cache_pmd(vma, address, pmd); | |
1206 | spin_unlock(pmd_ptl); | |
1207 | ||
1208 | *hpage = NULL; | |
1209 | ||
1210 | khugepaged_pages_collapsed++; | |
1211 | result = SCAN_SUCCEED; | |
1212 | out_up_write: | |
d8ed45c5 | 1213 | mmap_write_unlock(mm); |
b46e756f | 1214 | out_nolock: |
9d82c694 JW |
1215 | if (!IS_ERR_OR_NULL(*hpage)) |
1216 | mem_cgroup_uncharge(*hpage); | |
b46e756f KS |
1217 | trace_mm_collapse_huge_page(mm, isolated, result); |
1218 | return; | |
1219 | out: | |
b46e756f KS |
1220 | goto out_up_write; |
1221 | } | |
1222 | ||
1223 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
1224 | struct vm_area_struct *vma, | |
1225 | unsigned long address, | |
1226 | struct page **hpage) | |
1227 | { | |
1228 | pmd_t *pmd; | |
1229 | pte_t *pte, *_pte; | |
71a2c112 KS |
1230 | int ret = 0, result = 0, referenced = 0; |
1231 | int none_or_zero = 0, shared = 0; | |
b46e756f KS |
1232 | struct page *page = NULL; |
1233 | unsigned long _address; | |
1234 | spinlock_t *ptl; | |
1235 | int node = NUMA_NO_NODE, unmapped = 0; | |
0db501f7 | 1236 | bool writable = false; |
b46e756f KS |
1237 | |
1238 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1239 | ||
1240 | pmd = mm_find_pmd(mm, address); | |
1241 | if (!pmd) { | |
1242 | result = SCAN_PMD_NULL; | |
1243 | goto out; | |
1244 | } | |
1245 | ||
1246 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1247 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1248 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1249 | _pte++, _address += PAGE_SIZE) { | |
1250 | pte_t pteval = *_pte; | |
1251 | if (is_swap_pte(pteval)) { | |
1252 | if (++unmapped <= khugepaged_max_ptes_swap) { | |
e1e267c7 PX |
1253 | /* |
1254 | * Always be strict with uffd-wp | |
1255 | * enabled swap entries. Please see | |
1256 | * comment below for pte_uffd_wp(). | |
1257 | */ | |
1258 | if (pte_swp_uffd_wp(pteval)) { | |
1259 | result = SCAN_PTE_UFFD_WP; | |
1260 | goto out_unmap; | |
1261 | } | |
b46e756f KS |
1262 | continue; |
1263 | } else { | |
1264 | result = SCAN_EXCEED_SWAP_PTE; | |
1265 | goto out_unmap; | |
1266 | } | |
1267 | } | |
1268 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
1269 | if (!userfaultfd_armed(vma) && | |
1270 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
1271 | continue; | |
1272 | } else { | |
1273 | result = SCAN_EXCEED_NONE_PTE; | |
1274 | goto out_unmap; | |
1275 | } | |
1276 | } | |
1277 | if (!pte_present(pteval)) { | |
1278 | result = SCAN_PTE_NON_PRESENT; | |
1279 | goto out_unmap; | |
1280 | } | |
e1e267c7 PX |
1281 | if (pte_uffd_wp(pteval)) { |
1282 | /* | |
1283 | * Don't collapse the page if any of the small | |
1284 | * PTEs are armed with uffd write protection. | |
1285 | * Here we can also mark the new huge pmd as | |
1286 | * write protected if any of the small ones is | |
8958b249 | 1287 | * marked but that could bring unknown |
e1e267c7 PX |
1288 | * userfault messages that falls outside of |
1289 | * the registered range. So, just be simple. | |
1290 | */ | |
1291 | result = SCAN_PTE_UFFD_WP; | |
1292 | goto out_unmap; | |
1293 | } | |
b46e756f KS |
1294 | if (pte_write(pteval)) |
1295 | writable = true; | |
1296 | ||
1297 | page = vm_normal_page(vma, _address, pteval); | |
1298 | if (unlikely(!page)) { | |
1299 | result = SCAN_PAGE_NULL; | |
1300 | goto out_unmap; | |
1301 | } | |
1302 | ||
71a2c112 KS |
1303 | if (page_mapcount(page) > 1 && |
1304 | ++shared > khugepaged_max_ptes_shared) { | |
1305 | result = SCAN_EXCEED_SHARED_PTE; | |
1306 | goto out_unmap; | |
1307 | } | |
1308 | ||
5503fbf2 | 1309 | page = compound_head(page); |
b46e756f KS |
1310 | |
1311 | /* | |
1312 | * Record which node the original page is from and save this | |
1313 | * information to khugepaged_node_load[]. | |
1314 | * Khupaged will allocate hugepage from the node has the max | |
1315 | * hit record. | |
1316 | */ | |
1317 | node = page_to_nid(page); | |
1318 | if (khugepaged_scan_abort(node)) { | |
1319 | result = SCAN_SCAN_ABORT; | |
1320 | goto out_unmap; | |
1321 | } | |
1322 | khugepaged_node_load[node]++; | |
1323 | if (!PageLRU(page)) { | |
1324 | result = SCAN_PAGE_LRU; | |
1325 | goto out_unmap; | |
1326 | } | |
1327 | if (PageLocked(page)) { | |
1328 | result = SCAN_PAGE_LOCK; | |
1329 | goto out_unmap; | |
1330 | } | |
1331 | if (!PageAnon(page)) { | |
1332 | result = SCAN_PAGE_ANON; | |
1333 | goto out_unmap; | |
1334 | } | |
1335 | ||
1336 | /* | |
9445689f KS |
1337 | * Check if the page has any GUP (or other external) pins. |
1338 | * | |
1339 | * Here the check is racy it may see totmal_mapcount > refcount | |
1340 | * in some cases. | |
1341 | * For example, one process with one forked child process. | |
1342 | * The parent has the PMD split due to MADV_DONTNEED, then | |
1343 | * the child is trying unmap the whole PMD, but khugepaged | |
1344 | * may be scanning the parent between the child has | |
1345 | * PageDoubleMap flag cleared and dec the mapcount. So | |
1346 | * khugepaged may see total_mapcount > refcount. | |
1347 | * | |
1348 | * But such case is ephemeral we could always retry collapse | |
1349 | * later. However it may report false positive if the page | |
1350 | * has excessive GUP pins (i.e. 512). Anyway the same check | |
1351 | * will be done again later the risk seems low. | |
b46e756f | 1352 | */ |
9445689f | 1353 | if (!is_refcount_suitable(page)) { |
b46e756f KS |
1354 | result = SCAN_PAGE_COUNT; |
1355 | goto out_unmap; | |
1356 | } | |
1357 | if (pte_young(pteval) || | |
1358 | page_is_young(page) || PageReferenced(page) || | |
1359 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 1360 | referenced++; |
b46e756f | 1361 | } |
ffe945e6 | 1362 | if (!writable) { |
b46e756f | 1363 | result = SCAN_PAGE_RO; |
ffe945e6 KS |
1364 | } else if (!referenced || (unmapped && referenced < HPAGE_PMD_NR/2)) { |
1365 | result = SCAN_LACK_REFERENCED_PAGE; | |
1366 | } else { | |
1367 | result = SCAN_SUCCEED; | |
1368 | ret = 1; | |
b46e756f KS |
1369 | } |
1370 | out_unmap: | |
1371 | pte_unmap_unlock(pte, ptl); | |
1372 | if (ret) { | |
1373 | node = khugepaged_find_target_node(); | |
c1e8d7c6 | 1374 | /* collapse_huge_page will return with the mmap_lock released */ |
ffe945e6 KS |
1375 | collapse_huge_page(mm, address, hpage, node, |
1376 | referenced, unmapped); | |
b46e756f KS |
1377 | } |
1378 | out: | |
1379 | trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, | |
1380 | none_or_zero, result, unmapped); | |
1381 | return ret; | |
1382 | } | |
1383 | ||
1384 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
1385 | { | |
1386 | struct mm_struct *mm = mm_slot->mm; | |
1387 | ||
35f3aa39 | 1388 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
1389 | |
1390 | if (khugepaged_test_exit(mm)) { | |
1391 | /* free mm_slot */ | |
1392 | hash_del(&mm_slot->hash); | |
1393 | list_del(&mm_slot->mm_node); | |
1394 | ||
1395 | /* | |
1396 | * Not strictly needed because the mm exited already. | |
1397 | * | |
1398 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1399 | */ | |
1400 | ||
1401 | /* khugepaged_mm_lock actually not necessary for the below */ | |
1402 | free_mm_slot(mm_slot); | |
1403 | mmdrop(mm); | |
1404 | } | |
1405 | } | |
1406 | ||
396bcc52 | 1407 | #ifdef CONFIG_SHMEM |
27e1f827 SL |
1408 | /* |
1409 | * Notify khugepaged that given addr of the mm is pte-mapped THP. Then | |
1410 | * khugepaged should try to collapse the page table. | |
1411 | */ | |
1412 | static int khugepaged_add_pte_mapped_thp(struct mm_struct *mm, | |
1413 | unsigned long addr) | |
1414 | { | |
1415 | struct mm_slot *mm_slot; | |
1416 | ||
1417 | VM_BUG_ON(addr & ~HPAGE_PMD_MASK); | |
1418 | ||
1419 | spin_lock(&khugepaged_mm_lock); | |
1420 | mm_slot = get_mm_slot(mm); | |
1421 | if (likely(mm_slot && mm_slot->nr_pte_mapped_thp < MAX_PTE_MAPPED_THP)) | |
1422 | mm_slot->pte_mapped_thp[mm_slot->nr_pte_mapped_thp++] = addr; | |
1423 | spin_unlock(&khugepaged_mm_lock); | |
1424 | return 0; | |
1425 | } | |
1426 | ||
1427 | /** | |
336e6b53 AS |
1428 | * collapse_pte_mapped_thp - Try to collapse a pte-mapped THP for mm at |
1429 | * address haddr. | |
1430 | * | |
1431 | * @mm: process address space where collapse happens | |
1432 | * @addr: THP collapse address | |
27e1f827 SL |
1433 | * |
1434 | * This function checks whether all the PTEs in the PMD are pointing to the | |
1435 | * right THP. If so, retract the page table so the THP can refault in with | |
1436 | * as pmd-mapped. | |
1437 | */ | |
1438 | void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) | |
1439 | { | |
1440 | unsigned long haddr = addr & HPAGE_PMD_MASK; | |
1441 | struct vm_area_struct *vma = find_vma(mm, haddr); | |
119a5fc1 | 1442 | struct page *hpage; |
27e1f827 SL |
1443 | pte_t *start_pte, *pte; |
1444 | pmd_t *pmd, _pmd; | |
1445 | spinlock_t *ptl; | |
1446 | int count = 0; | |
1447 | int i; | |
1448 | ||
1449 | if (!vma || !vma->vm_file || | |
1450 | vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE) | |
1451 | return; | |
1452 | ||
1453 | /* | |
1454 | * This vm_flags may not have VM_HUGEPAGE if the page was not | |
1455 | * collapsed by this mm. But we can still collapse if the page is | |
1456 | * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check() | |
1457 | * will not fail the vma for missing VM_HUGEPAGE | |
1458 | */ | |
1459 | if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE)) | |
1460 | return; | |
1461 | ||
119a5fc1 HD |
1462 | hpage = find_lock_page(vma->vm_file->f_mapping, |
1463 | linear_page_index(vma, haddr)); | |
1464 | if (!hpage) | |
1465 | return; | |
1466 | ||
1467 | if (!PageHead(hpage)) | |
1468 | goto drop_hpage; | |
1469 | ||
27e1f827 SL |
1470 | pmd = mm_find_pmd(mm, haddr); |
1471 | if (!pmd) | |
119a5fc1 | 1472 | goto drop_hpage; |
27e1f827 SL |
1473 | |
1474 | start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl); | |
1475 | ||
1476 | /* step 1: check all mapped PTEs are to the right huge page */ | |
1477 | for (i = 0, addr = haddr, pte = start_pte; | |
1478 | i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) { | |
1479 | struct page *page; | |
1480 | ||
1481 | /* empty pte, skip */ | |
1482 | if (pte_none(*pte)) | |
1483 | continue; | |
1484 | ||
1485 | /* page swapped out, abort */ | |
1486 | if (!pte_present(*pte)) | |
1487 | goto abort; | |
1488 | ||
1489 | page = vm_normal_page(vma, addr, *pte); | |
1490 | ||
27e1f827 | 1491 | /* |
119a5fc1 HD |
1492 | * Note that uprobe, debugger, or MAP_PRIVATE may change the |
1493 | * page table, but the new page will not be a subpage of hpage. | |
27e1f827 | 1494 | */ |
119a5fc1 | 1495 | if (hpage + i != page) |
27e1f827 SL |
1496 | goto abort; |
1497 | count++; | |
1498 | } | |
1499 | ||
1500 | /* step 2: adjust rmap */ | |
1501 | for (i = 0, addr = haddr, pte = start_pte; | |
1502 | i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) { | |
1503 | struct page *page; | |
1504 | ||
1505 | if (pte_none(*pte)) | |
1506 | continue; | |
1507 | page = vm_normal_page(vma, addr, *pte); | |
1508 | page_remove_rmap(page, false); | |
1509 | } | |
1510 | ||
1511 | pte_unmap_unlock(start_pte, ptl); | |
1512 | ||
1513 | /* step 3: set proper refcount and mm_counters. */ | |
119a5fc1 | 1514 | if (count) { |
27e1f827 SL |
1515 | page_ref_sub(hpage, count); |
1516 | add_mm_counter(vma->vm_mm, mm_counter_file(hpage), -count); | |
1517 | } | |
1518 | ||
1519 | /* step 4: collapse pmd */ | |
1520 | ptl = pmd_lock(vma->vm_mm, pmd); | |
723a80da | 1521 | _pmd = pmdp_collapse_flush(vma, haddr, pmd); |
27e1f827 SL |
1522 | spin_unlock(ptl); |
1523 | mm_dec_nr_ptes(mm); | |
1524 | pte_free(mm, pmd_pgtable(_pmd)); | |
119a5fc1 HD |
1525 | |
1526 | drop_hpage: | |
1527 | unlock_page(hpage); | |
1528 | put_page(hpage); | |
27e1f827 SL |
1529 | return; |
1530 | ||
1531 | abort: | |
1532 | pte_unmap_unlock(start_pte, ptl); | |
119a5fc1 | 1533 | goto drop_hpage; |
27e1f827 SL |
1534 | } |
1535 | ||
1536 | static int khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) | |
1537 | { | |
1538 | struct mm_struct *mm = mm_slot->mm; | |
1539 | int i; | |
1540 | ||
1541 | if (likely(mm_slot->nr_pte_mapped_thp == 0)) | |
1542 | return 0; | |
1543 | ||
d8ed45c5 | 1544 | if (!mmap_write_trylock(mm)) |
27e1f827 SL |
1545 | return -EBUSY; |
1546 | ||
1547 | if (unlikely(khugepaged_test_exit(mm))) | |
1548 | goto out; | |
1549 | ||
1550 | for (i = 0; i < mm_slot->nr_pte_mapped_thp; i++) | |
1551 | collapse_pte_mapped_thp(mm, mm_slot->pte_mapped_thp[i]); | |
1552 | ||
1553 | out: | |
1554 | mm_slot->nr_pte_mapped_thp = 0; | |
d8ed45c5 | 1555 | mmap_write_unlock(mm); |
27e1f827 SL |
1556 | return 0; |
1557 | } | |
1558 | ||
f3f0e1d2 KS |
1559 | static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) |
1560 | { | |
1561 | struct vm_area_struct *vma; | |
18e77600 | 1562 | struct mm_struct *mm; |
f3f0e1d2 KS |
1563 | unsigned long addr; |
1564 | pmd_t *pmd, _pmd; | |
1565 | ||
1566 | i_mmap_lock_write(mapping); | |
1567 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { | |
27e1f827 SL |
1568 | /* |
1569 | * Check vma->anon_vma to exclude MAP_PRIVATE mappings that | |
1570 | * got written to. These VMAs are likely not worth investing | |
3e4e28c5 | 1571 | * mmap_write_lock(mm) as PMD-mapping is likely to be split |
27e1f827 SL |
1572 | * later. |
1573 | * | |
1574 | * Not that vma->anon_vma check is racy: it can be set up after | |
c1e8d7c6 | 1575 | * the check but before we took mmap_lock by the fault path. |
27e1f827 SL |
1576 | * But page lock would prevent establishing any new ptes of the |
1577 | * page, so we are safe. | |
1578 | * | |
1579 | * An alternative would be drop the check, but check that page | |
1580 | * table is clear before calling pmdp_collapse_flush() under | |
1581 | * ptl. It has higher chance to recover THP for the VMA, but | |
1582 | * has higher cost too. | |
1583 | */ | |
f3f0e1d2 KS |
1584 | if (vma->anon_vma) |
1585 | continue; | |
1586 | addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
1587 | if (addr & ~HPAGE_PMD_MASK) | |
1588 | continue; | |
1589 | if (vma->vm_end < addr + HPAGE_PMD_SIZE) | |
1590 | continue; | |
18e77600 HD |
1591 | mm = vma->vm_mm; |
1592 | pmd = mm_find_pmd(mm, addr); | |
f3f0e1d2 KS |
1593 | if (!pmd) |
1594 | continue; | |
1595 | /* | |
c1e8d7c6 | 1596 | * We need exclusive mmap_lock to retract page table. |
27e1f827 SL |
1597 | * |
1598 | * We use trylock due to lock inversion: we need to acquire | |
c1e8d7c6 | 1599 | * mmap_lock while holding page lock. Fault path does it in |
27e1f827 | 1600 | * reverse order. Trylock is a way to avoid deadlock. |
f3f0e1d2 | 1601 | */ |
18e77600 HD |
1602 | if (mmap_write_trylock(mm)) { |
1603 | if (!khugepaged_test_exit(mm)) { | |
1604 | spinlock_t *ptl = pmd_lock(mm, pmd); | |
1605 | /* assume page table is clear */ | |
1606 | _pmd = pmdp_collapse_flush(vma, addr, pmd); | |
1607 | spin_unlock(ptl); | |
1608 | mm_dec_nr_ptes(mm); | |
1609 | pte_free(mm, pmd_pgtable(_pmd)); | |
1610 | } | |
1611 | mmap_write_unlock(mm); | |
27e1f827 SL |
1612 | } else { |
1613 | /* Try again later */ | |
18e77600 | 1614 | khugepaged_add_pte_mapped_thp(mm, addr); |
f3f0e1d2 KS |
1615 | } |
1616 | } | |
1617 | i_mmap_unlock_write(mapping); | |
1618 | } | |
1619 | ||
1620 | /** | |
99cb0dbd | 1621 | * collapse_file - collapse filemap/tmpfs/shmem pages into huge one. |
f3f0e1d2 | 1622 | * |
336e6b53 AS |
1623 | * @mm: process address space where collapse happens |
1624 | * @file: file that collapse on | |
1625 | * @start: collapse start address | |
1626 | * @hpage: new allocated huge page for collapse | |
1627 | * @node: appointed node the new huge page allocate from | |
1628 | * | |
f3f0e1d2 | 1629 | * Basic scheme is simple, details are more complex: |
87c460a0 | 1630 | * - allocate and lock a new huge page; |
77da9389 | 1631 | * - scan page cache replacing old pages with the new one |
99cb0dbd | 1632 | * + swap/gup in pages if necessary; |
f3f0e1d2 | 1633 | * + fill in gaps; |
77da9389 MW |
1634 | * + keep old pages around in case rollback is required; |
1635 | * - if replacing succeeds: | |
f3f0e1d2 KS |
1636 | * + copy data over; |
1637 | * + free old pages; | |
87c460a0 | 1638 | * + unlock huge page; |
f3f0e1d2 KS |
1639 | * - if replacing failed; |
1640 | * + put all pages back and unfreeze them; | |
77da9389 | 1641 | * + restore gaps in the page cache; |
87c460a0 | 1642 | * + unlock and free huge page; |
f3f0e1d2 | 1643 | */ |
579c571e SL |
1644 | static void collapse_file(struct mm_struct *mm, |
1645 | struct file *file, pgoff_t start, | |
f3f0e1d2 KS |
1646 | struct page **hpage, int node) |
1647 | { | |
579c571e | 1648 | struct address_space *mapping = file->f_mapping; |
f3f0e1d2 | 1649 | gfp_t gfp; |
77da9389 | 1650 | struct page *new_page; |
f3f0e1d2 KS |
1651 | pgoff_t index, end = start + HPAGE_PMD_NR; |
1652 | LIST_HEAD(pagelist); | |
77da9389 | 1653 | XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); |
f3f0e1d2 | 1654 | int nr_none = 0, result = SCAN_SUCCEED; |
99cb0dbd | 1655 | bool is_shmem = shmem_file(file); |
bf9ecead | 1656 | int nr; |
f3f0e1d2 | 1657 | |
99cb0dbd | 1658 | VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); |
f3f0e1d2 KS |
1659 | VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); |
1660 | ||
1661 | /* Only allocate from the target node */ | |
41b6167e | 1662 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
f3f0e1d2 KS |
1663 | |
1664 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
1665 | if (!new_page) { | |
1666 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
1667 | goto out; | |
1668 | } | |
1669 | ||
d9eb1ea2 | 1670 | if (unlikely(mem_cgroup_charge(new_page, mm, gfp))) { |
f3f0e1d2 KS |
1671 | result = SCAN_CGROUP_CHARGE_FAIL; |
1672 | goto out; | |
1673 | } | |
9d82c694 | 1674 | count_memcg_page_event(new_page, THP_COLLAPSE_ALLOC); |
f3f0e1d2 | 1675 | |
95feeabb HD |
1676 | /* This will be less messy when we use multi-index entries */ |
1677 | do { | |
1678 | xas_lock_irq(&xas); | |
1679 | xas_create_range(&xas); | |
1680 | if (!xas_error(&xas)) | |
1681 | break; | |
1682 | xas_unlock_irq(&xas); | |
1683 | if (!xas_nomem(&xas, GFP_KERNEL)) { | |
95feeabb HD |
1684 | result = SCAN_FAIL; |
1685 | goto out; | |
1686 | } | |
1687 | } while (1); | |
1688 | ||
042a3082 | 1689 | __SetPageLocked(new_page); |
99cb0dbd SL |
1690 | if (is_shmem) |
1691 | __SetPageSwapBacked(new_page); | |
f3f0e1d2 KS |
1692 | new_page->index = start; |
1693 | new_page->mapping = mapping; | |
f3f0e1d2 | 1694 | |
f3f0e1d2 | 1695 | /* |
87c460a0 HD |
1696 | * At this point the new_page is locked and not up-to-date. |
1697 | * It's safe to insert it into the page cache, because nobody would | |
1698 | * be able to map it or use it in another way until we unlock it. | |
f3f0e1d2 KS |
1699 | */ |
1700 | ||
77da9389 MW |
1701 | xas_set(&xas, start); |
1702 | for (index = start; index < end; index++) { | |
1703 | struct page *page = xas_next(&xas); | |
1704 | ||
1705 | VM_BUG_ON(index != xas.xa_index); | |
99cb0dbd SL |
1706 | if (is_shmem) { |
1707 | if (!page) { | |
1708 | /* | |
1709 | * Stop if extent has been truncated or | |
1710 | * hole-punched, and is now completely | |
1711 | * empty. | |
1712 | */ | |
1713 | if (index == start) { | |
1714 | if (!xas_next_entry(&xas, end - 1)) { | |
1715 | result = SCAN_TRUNCATED; | |
1716 | goto xa_locked; | |
1717 | } | |
1718 | xas_set(&xas, index); | |
1719 | } | |
1720 | if (!shmem_charge(mapping->host, 1)) { | |
1721 | result = SCAN_FAIL; | |
042a3082 | 1722 | goto xa_locked; |
701270fa | 1723 | } |
99cb0dbd SL |
1724 | xas_store(&xas, new_page); |
1725 | nr_none++; | |
1726 | continue; | |
701270fa | 1727 | } |
99cb0dbd SL |
1728 | |
1729 | if (xa_is_value(page) || !PageUptodate(page)) { | |
1730 | xas_unlock_irq(&xas); | |
1731 | /* swap in or instantiate fallocated page */ | |
1732 | if (shmem_getpage(mapping->host, index, &page, | |
1733 | SGP_NOHUGE)) { | |
1734 | result = SCAN_FAIL; | |
1735 | goto xa_unlocked; | |
1736 | } | |
1737 | } else if (trylock_page(page)) { | |
1738 | get_page(page); | |
1739 | xas_unlock_irq(&xas); | |
1740 | } else { | |
1741 | result = SCAN_PAGE_LOCK; | |
042a3082 | 1742 | goto xa_locked; |
77da9389 | 1743 | } |
99cb0dbd SL |
1744 | } else { /* !is_shmem */ |
1745 | if (!page || xa_is_value(page)) { | |
1746 | xas_unlock_irq(&xas); | |
1747 | page_cache_sync_readahead(mapping, &file->f_ra, | |
1748 | file, index, | |
e5a59d30 | 1749 | end - index); |
99cb0dbd SL |
1750 | /* drain pagevecs to help isolate_lru_page() */ |
1751 | lru_add_drain(); | |
1752 | page = find_lock_page(mapping, index); | |
1753 | if (unlikely(page == NULL)) { | |
1754 | result = SCAN_FAIL; | |
1755 | goto xa_unlocked; | |
1756 | } | |
75f36069 SL |
1757 | } else if (PageDirty(page)) { |
1758 | /* | |
1759 | * khugepaged only works on read-only fd, | |
1760 | * so this page is dirty because it hasn't | |
1761 | * been flushed since first write. There | |
1762 | * won't be new dirty pages. | |
1763 | * | |
1764 | * Trigger async flush here and hope the | |
1765 | * writeback is done when khugepaged | |
1766 | * revisits this page. | |
1767 | * | |
1768 | * This is a one-off situation. We are not | |
1769 | * forcing writeback in loop. | |
1770 | */ | |
1771 | xas_unlock_irq(&xas); | |
1772 | filemap_flush(mapping); | |
1773 | result = SCAN_FAIL; | |
1774 | goto xa_unlocked; | |
99cb0dbd SL |
1775 | } else if (trylock_page(page)) { |
1776 | get_page(page); | |
1777 | xas_unlock_irq(&xas); | |
1778 | } else { | |
1779 | result = SCAN_PAGE_LOCK; | |
1780 | goto xa_locked; | |
f3f0e1d2 | 1781 | } |
f3f0e1d2 KS |
1782 | } |
1783 | ||
1784 | /* | |
b93b0163 | 1785 | * The page must be locked, so we can drop the i_pages lock |
f3f0e1d2 KS |
1786 | * without racing with truncate. |
1787 | */ | |
1788 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
4655e5e5 SL |
1789 | |
1790 | /* make sure the page is up to date */ | |
1791 | if (unlikely(!PageUptodate(page))) { | |
1792 | result = SCAN_FAIL; | |
1793 | goto out_unlock; | |
1794 | } | |
06a5e126 HD |
1795 | |
1796 | /* | |
1797 | * If file was truncated then extended, or hole-punched, before | |
1798 | * we locked the first page, then a THP might be there already. | |
1799 | */ | |
1800 | if (PageTransCompound(page)) { | |
1801 | result = SCAN_PAGE_COMPOUND; | |
1802 | goto out_unlock; | |
1803 | } | |
f3f0e1d2 KS |
1804 | |
1805 | if (page_mapping(page) != mapping) { | |
1806 | result = SCAN_TRUNCATED; | |
1807 | goto out_unlock; | |
1808 | } | |
f3f0e1d2 | 1809 | |
4655e5e5 SL |
1810 | if (!is_shmem && PageDirty(page)) { |
1811 | /* | |
1812 | * khugepaged only works on read-only fd, so this | |
1813 | * page is dirty because it hasn't been flushed | |
1814 | * since first write. | |
1815 | */ | |
1816 | result = SCAN_FAIL; | |
1817 | goto out_unlock; | |
1818 | } | |
1819 | ||
f3f0e1d2 KS |
1820 | if (isolate_lru_page(page)) { |
1821 | result = SCAN_DEL_PAGE_LRU; | |
042a3082 | 1822 | goto out_unlock; |
f3f0e1d2 KS |
1823 | } |
1824 | ||
99cb0dbd SL |
1825 | if (page_has_private(page) && |
1826 | !try_to_release_page(page, GFP_KERNEL)) { | |
1827 | result = SCAN_PAGE_HAS_PRIVATE; | |
2f33a706 | 1828 | putback_lru_page(page); |
99cb0dbd SL |
1829 | goto out_unlock; |
1830 | } | |
1831 | ||
f3f0e1d2 | 1832 | if (page_mapped(page)) |
977fbdcd | 1833 | unmap_mapping_pages(mapping, index, 1, false); |
f3f0e1d2 | 1834 | |
77da9389 MW |
1835 | xas_lock_irq(&xas); |
1836 | xas_set(&xas, index); | |
f3f0e1d2 | 1837 | |
77da9389 | 1838 | VM_BUG_ON_PAGE(page != xas_load(&xas), page); |
f3f0e1d2 KS |
1839 | VM_BUG_ON_PAGE(page_mapped(page), page); |
1840 | ||
1841 | /* | |
1842 | * The page is expected to have page_count() == 3: | |
1843 | * - we hold a pin on it; | |
77da9389 | 1844 | * - one reference from page cache; |
f3f0e1d2 KS |
1845 | * - one from isolate_lru_page; |
1846 | */ | |
1847 | if (!page_ref_freeze(page, 3)) { | |
1848 | result = SCAN_PAGE_COUNT; | |
042a3082 HD |
1849 | xas_unlock_irq(&xas); |
1850 | putback_lru_page(page); | |
1851 | goto out_unlock; | |
f3f0e1d2 KS |
1852 | } |
1853 | ||
1854 | /* | |
1855 | * Add the page to the list to be able to undo the collapse if | |
1856 | * something go wrong. | |
1857 | */ | |
1858 | list_add_tail(&page->lru, &pagelist); | |
1859 | ||
1860 | /* Finally, replace with the new page. */ | |
4101196b | 1861 | xas_store(&xas, new_page); |
f3f0e1d2 | 1862 | continue; |
f3f0e1d2 KS |
1863 | out_unlock: |
1864 | unlock_page(page); | |
1865 | put_page(page); | |
042a3082 | 1866 | goto xa_unlocked; |
f3f0e1d2 | 1867 | } |
bf9ecead | 1868 | nr = thp_nr_pages(new_page); |
f3f0e1d2 | 1869 | |
99cb0dbd | 1870 | if (is_shmem) |
57b2847d | 1871 | __mod_lruvec_page_state(new_page, NR_SHMEM_THPS, nr); |
09d91cda | 1872 | else { |
bf9ecead | 1873 | __mod_lruvec_page_state(new_page, NR_FILE_THPS, nr); |
09d91cda SL |
1874 | filemap_nr_thps_inc(mapping); |
1875 | } | |
99cb0dbd | 1876 | |
042a3082 | 1877 | if (nr_none) { |
9d82c694 | 1878 | __mod_lruvec_page_state(new_page, NR_FILE_PAGES, nr_none); |
99cb0dbd | 1879 | if (is_shmem) |
9d82c694 | 1880 | __mod_lruvec_page_state(new_page, NR_SHMEM, nr_none); |
042a3082 HD |
1881 | } |
1882 | ||
1883 | xa_locked: | |
1884 | xas_unlock_irq(&xas); | |
77da9389 | 1885 | xa_unlocked: |
042a3082 | 1886 | |
f3f0e1d2 | 1887 | if (result == SCAN_SUCCEED) { |
77da9389 | 1888 | struct page *page, *tmp; |
f3f0e1d2 KS |
1889 | |
1890 | /* | |
77da9389 MW |
1891 | * Replacing old pages with new one has succeeded, now we |
1892 | * need to copy the content and free the old pages. | |
f3f0e1d2 | 1893 | */ |
2af8ff29 | 1894 | index = start; |
f3f0e1d2 | 1895 | list_for_each_entry_safe(page, tmp, &pagelist, lru) { |
2af8ff29 HD |
1896 | while (index < page->index) { |
1897 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1898 | index++; | |
1899 | } | |
f3f0e1d2 KS |
1900 | copy_highpage(new_page + (page->index % HPAGE_PMD_NR), |
1901 | page); | |
1902 | list_del(&page->lru); | |
f3f0e1d2 | 1903 | page->mapping = NULL; |
042a3082 | 1904 | page_ref_unfreeze(page, 1); |
f3f0e1d2 KS |
1905 | ClearPageActive(page); |
1906 | ClearPageUnevictable(page); | |
042a3082 | 1907 | unlock_page(page); |
f3f0e1d2 | 1908 | put_page(page); |
2af8ff29 HD |
1909 | index++; |
1910 | } | |
1911 | while (index < end) { | |
1912 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1913 | index++; | |
f3f0e1d2 KS |
1914 | } |
1915 | ||
f3f0e1d2 | 1916 | SetPageUptodate(new_page); |
87c460a0 | 1917 | page_ref_add(new_page, HPAGE_PMD_NR - 1); |
6058eaec | 1918 | if (is_shmem) |
99cb0dbd | 1919 | set_page_dirty(new_page); |
6058eaec | 1920 | lru_cache_add(new_page); |
f3f0e1d2 | 1921 | |
042a3082 HD |
1922 | /* |
1923 | * Remove pte page tables, so we can re-fault the page as huge. | |
1924 | */ | |
1925 | retract_page_tables(mapping, start); | |
f3f0e1d2 | 1926 | *hpage = NULL; |
87aa7529 YS |
1927 | |
1928 | khugepaged_pages_collapsed++; | |
f3f0e1d2 | 1929 | } else { |
77da9389 | 1930 | struct page *page; |
aaa52e34 | 1931 | |
77da9389 | 1932 | /* Something went wrong: roll back page cache changes */ |
77da9389 | 1933 | xas_lock_irq(&xas); |
aaa52e34 | 1934 | mapping->nrpages -= nr_none; |
99cb0dbd SL |
1935 | |
1936 | if (is_shmem) | |
1937 | shmem_uncharge(mapping->host, nr_none); | |
aaa52e34 | 1938 | |
77da9389 MW |
1939 | xas_set(&xas, start); |
1940 | xas_for_each(&xas, page, end - 1) { | |
f3f0e1d2 KS |
1941 | page = list_first_entry_or_null(&pagelist, |
1942 | struct page, lru); | |
77da9389 | 1943 | if (!page || xas.xa_index < page->index) { |
f3f0e1d2 KS |
1944 | if (!nr_none) |
1945 | break; | |
f3f0e1d2 | 1946 | nr_none--; |
59749e6c | 1947 | /* Put holes back where they were */ |
77da9389 | 1948 | xas_store(&xas, NULL); |
f3f0e1d2 KS |
1949 | continue; |
1950 | } | |
1951 | ||
77da9389 | 1952 | VM_BUG_ON_PAGE(page->index != xas.xa_index, page); |
f3f0e1d2 KS |
1953 | |
1954 | /* Unfreeze the page. */ | |
1955 | list_del(&page->lru); | |
1956 | page_ref_unfreeze(page, 2); | |
77da9389 MW |
1957 | xas_store(&xas, page); |
1958 | xas_pause(&xas); | |
1959 | xas_unlock_irq(&xas); | |
f3f0e1d2 | 1960 | unlock_page(page); |
042a3082 | 1961 | putback_lru_page(page); |
77da9389 | 1962 | xas_lock_irq(&xas); |
f3f0e1d2 KS |
1963 | } |
1964 | VM_BUG_ON(nr_none); | |
77da9389 | 1965 | xas_unlock_irq(&xas); |
f3f0e1d2 | 1966 | |
f3f0e1d2 KS |
1967 | new_page->mapping = NULL; |
1968 | } | |
042a3082 HD |
1969 | |
1970 | unlock_page(new_page); | |
f3f0e1d2 KS |
1971 | out: |
1972 | VM_BUG_ON(!list_empty(&pagelist)); | |
9d82c694 JW |
1973 | if (!IS_ERR_OR_NULL(*hpage)) |
1974 | mem_cgroup_uncharge(*hpage); | |
f3f0e1d2 KS |
1975 | /* TODO: tracepoints */ |
1976 | } | |
1977 | ||
579c571e SL |
1978 | static void khugepaged_scan_file(struct mm_struct *mm, |
1979 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
1980 | { |
1981 | struct page *page = NULL; | |
579c571e | 1982 | struct address_space *mapping = file->f_mapping; |
85b392db | 1983 | XA_STATE(xas, &mapping->i_pages, start); |
f3f0e1d2 KS |
1984 | int present, swap; |
1985 | int node = NUMA_NO_NODE; | |
1986 | int result = SCAN_SUCCEED; | |
1987 | ||
1988 | present = 0; | |
1989 | swap = 0; | |
1990 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1991 | rcu_read_lock(); | |
85b392db MW |
1992 | xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) { |
1993 | if (xas_retry(&xas, page)) | |
f3f0e1d2 | 1994 | continue; |
f3f0e1d2 | 1995 | |
85b392db | 1996 | if (xa_is_value(page)) { |
f3f0e1d2 KS |
1997 | if (++swap > khugepaged_max_ptes_swap) { |
1998 | result = SCAN_EXCEED_SWAP_PTE; | |
1999 | break; | |
2000 | } | |
2001 | continue; | |
2002 | } | |
2003 | ||
2004 | if (PageTransCompound(page)) { | |
2005 | result = SCAN_PAGE_COMPOUND; | |
2006 | break; | |
2007 | } | |
2008 | ||
2009 | node = page_to_nid(page); | |
2010 | if (khugepaged_scan_abort(node)) { | |
2011 | result = SCAN_SCAN_ABORT; | |
2012 | break; | |
2013 | } | |
2014 | khugepaged_node_load[node]++; | |
2015 | ||
2016 | if (!PageLRU(page)) { | |
2017 | result = SCAN_PAGE_LRU; | |
2018 | break; | |
2019 | } | |
2020 | ||
99cb0dbd SL |
2021 | if (page_count(page) != |
2022 | 1 + page_mapcount(page) + page_has_private(page)) { | |
f3f0e1d2 KS |
2023 | result = SCAN_PAGE_COUNT; |
2024 | break; | |
2025 | } | |
2026 | ||
2027 | /* | |
2028 | * We probably should check if the page is referenced here, but | |
2029 | * nobody would transfer pte_young() to PageReferenced() for us. | |
2030 | * And rmap walk here is just too costly... | |
2031 | */ | |
2032 | ||
2033 | present++; | |
2034 | ||
2035 | if (need_resched()) { | |
85b392db | 2036 | xas_pause(&xas); |
f3f0e1d2 | 2037 | cond_resched_rcu(); |
f3f0e1d2 KS |
2038 | } |
2039 | } | |
2040 | rcu_read_unlock(); | |
2041 | ||
2042 | if (result == SCAN_SUCCEED) { | |
2043 | if (present < HPAGE_PMD_NR - khugepaged_max_ptes_none) { | |
2044 | result = SCAN_EXCEED_NONE_PTE; | |
2045 | } else { | |
2046 | node = khugepaged_find_target_node(); | |
579c571e | 2047 | collapse_file(mm, file, start, hpage, node); |
f3f0e1d2 KS |
2048 | } |
2049 | } | |
2050 | ||
2051 | /* TODO: tracepoints */ | |
2052 | } | |
2053 | #else | |
579c571e SL |
2054 | static void khugepaged_scan_file(struct mm_struct *mm, |
2055 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
2056 | { |
2057 | BUILD_BUG(); | |
2058 | } | |
27e1f827 SL |
2059 | |
2060 | static int khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) | |
2061 | { | |
2062 | return 0; | |
2063 | } | |
f3f0e1d2 KS |
2064 | #endif |
2065 | ||
b46e756f KS |
2066 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, |
2067 | struct page **hpage) | |
2068 | __releases(&khugepaged_mm_lock) | |
2069 | __acquires(&khugepaged_mm_lock) | |
2070 | { | |
2071 | struct mm_slot *mm_slot; | |
2072 | struct mm_struct *mm; | |
2073 | struct vm_area_struct *vma; | |
2074 | int progress = 0; | |
2075 | ||
2076 | VM_BUG_ON(!pages); | |
35f3aa39 | 2077 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
2078 | |
2079 | if (khugepaged_scan.mm_slot) | |
2080 | mm_slot = khugepaged_scan.mm_slot; | |
2081 | else { | |
2082 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2083 | struct mm_slot, mm_node); | |
2084 | khugepaged_scan.address = 0; | |
2085 | khugepaged_scan.mm_slot = mm_slot; | |
2086 | } | |
2087 | spin_unlock(&khugepaged_mm_lock); | |
27e1f827 | 2088 | khugepaged_collapse_pte_mapped_thps(mm_slot); |
b46e756f KS |
2089 | |
2090 | mm = mm_slot->mm; | |
3b454ad3 YS |
2091 | /* |
2092 | * Don't wait for semaphore (to avoid long wait times). Just move to | |
2093 | * the next mm on the list. | |
2094 | */ | |
2095 | vma = NULL; | |
d8ed45c5 | 2096 | if (unlikely(!mmap_read_trylock(mm))) |
c1e8d7c6 | 2097 | goto breakouterloop_mmap_lock; |
3b454ad3 | 2098 | if (likely(!khugepaged_test_exit(mm))) |
b46e756f KS |
2099 | vma = find_vma(mm, khugepaged_scan.address); |
2100 | ||
2101 | progress++; | |
2102 | for (; vma; vma = vma->vm_next) { | |
2103 | unsigned long hstart, hend; | |
2104 | ||
2105 | cond_resched(); | |
2106 | if (unlikely(khugepaged_test_exit(mm))) { | |
2107 | progress++; | |
2108 | break; | |
2109 | } | |
50f8b92f | 2110 | if (!hugepage_vma_check(vma, vma->vm_flags)) { |
b46e756f KS |
2111 | skip: |
2112 | progress++; | |
2113 | continue; | |
2114 | } | |
2115 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2116 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2117 | if (hstart >= hend) | |
2118 | goto skip; | |
2119 | if (khugepaged_scan.address > hend) | |
2120 | goto skip; | |
2121 | if (khugepaged_scan.address < hstart) | |
2122 | khugepaged_scan.address = hstart; | |
2123 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); | |
396bcc52 MWO |
2124 | if (shmem_file(vma->vm_file) && !shmem_huge_enabled(vma)) |
2125 | goto skip; | |
b46e756f KS |
2126 | |
2127 | while (khugepaged_scan.address < hend) { | |
2128 | int ret; | |
2129 | cond_resched(); | |
2130 | if (unlikely(khugepaged_test_exit(mm))) | |
2131 | goto breakouterloop; | |
2132 | ||
2133 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2134 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2135 | hend); | |
99cb0dbd | 2136 | if (IS_ENABLED(CONFIG_SHMEM) && vma->vm_file) { |
396bcc52 | 2137 | struct file *file = get_file(vma->vm_file); |
f3f0e1d2 KS |
2138 | pgoff_t pgoff = linear_page_index(vma, |
2139 | khugepaged_scan.address); | |
99cb0dbd | 2140 | |
d8ed45c5 | 2141 | mmap_read_unlock(mm); |
f3f0e1d2 | 2142 | ret = 1; |
579c571e | 2143 | khugepaged_scan_file(mm, file, pgoff, hpage); |
f3f0e1d2 KS |
2144 | fput(file); |
2145 | } else { | |
2146 | ret = khugepaged_scan_pmd(mm, vma, | |
2147 | khugepaged_scan.address, | |
2148 | hpage); | |
2149 | } | |
b46e756f KS |
2150 | /* move to next address */ |
2151 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2152 | progress += HPAGE_PMD_NR; | |
2153 | if (ret) | |
c1e8d7c6 ML |
2154 | /* we released mmap_lock so break loop */ |
2155 | goto breakouterloop_mmap_lock; | |
b46e756f KS |
2156 | if (progress >= pages) |
2157 | goto breakouterloop; | |
2158 | } | |
2159 | } | |
2160 | breakouterloop: | |
d8ed45c5 | 2161 | mmap_read_unlock(mm); /* exit_mmap will destroy ptes after this */ |
c1e8d7c6 | 2162 | breakouterloop_mmap_lock: |
b46e756f KS |
2163 | |
2164 | spin_lock(&khugepaged_mm_lock); | |
2165 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); | |
2166 | /* | |
2167 | * Release the current mm_slot if this mm is about to die, or | |
2168 | * if we scanned all vmas of this mm. | |
2169 | */ | |
2170 | if (khugepaged_test_exit(mm) || !vma) { | |
2171 | /* | |
2172 | * Make sure that if mm_users is reaching zero while | |
2173 | * khugepaged runs here, khugepaged_exit will find | |
2174 | * mm_slot not pointing to the exiting mm. | |
2175 | */ | |
2176 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2177 | khugepaged_scan.mm_slot = list_entry( | |
2178 | mm_slot->mm_node.next, | |
2179 | struct mm_slot, mm_node); | |
2180 | khugepaged_scan.address = 0; | |
2181 | } else { | |
2182 | khugepaged_scan.mm_slot = NULL; | |
2183 | khugepaged_full_scans++; | |
2184 | } | |
2185 | ||
2186 | collect_mm_slot(mm_slot); | |
2187 | } | |
2188 | ||
2189 | return progress; | |
2190 | } | |
2191 | ||
2192 | static int khugepaged_has_work(void) | |
2193 | { | |
2194 | return !list_empty(&khugepaged_scan.mm_head) && | |
2195 | khugepaged_enabled(); | |
2196 | } | |
2197 | ||
2198 | static int khugepaged_wait_event(void) | |
2199 | { | |
2200 | return !list_empty(&khugepaged_scan.mm_head) || | |
2201 | kthread_should_stop(); | |
2202 | } | |
2203 | ||
2204 | static void khugepaged_do_scan(void) | |
2205 | { | |
2206 | struct page *hpage = NULL; | |
2207 | unsigned int progress = 0, pass_through_head = 0; | |
2208 | unsigned int pages = khugepaged_pages_to_scan; | |
2209 | bool wait = true; | |
2210 | ||
2211 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2212 | ||
a980df33 KS |
2213 | lru_add_drain_all(); |
2214 | ||
b46e756f KS |
2215 | while (progress < pages) { |
2216 | if (!khugepaged_prealloc_page(&hpage, &wait)) | |
2217 | break; | |
2218 | ||
2219 | cond_resched(); | |
2220 | ||
2221 | if (unlikely(kthread_should_stop() || try_to_freeze())) | |
2222 | break; | |
2223 | ||
2224 | spin_lock(&khugepaged_mm_lock); | |
2225 | if (!khugepaged_scan.mm_slot) | |
2226 | pass_through_head++; | |
2227 | if (khugepaged_has_work() && | |
2228 | pass_through_head < 2) | |
2229 | progress += khugepaged_scan_mm_slot(pages - progress, | |
2230 | &hpage); | |
2231 | else | |
2232 | progress = pages; | |
2233 | spin_unlock(&khugepaged_mm_lock); | |
2234 | } | |
2235 | ||
2236 | if (!IS_ERR_OR_NULL(hpage)) | |
2237 | put_page(hpage); | |
2238 | } | |
2239 | ||
2240 | static bool khugepaged_should_wakeup(void) | |
2241 | { | |
2242 | return kthread_should_stop() || | |
2243 | time_after_eq(jiffies, khugepaged_sleep_expire); | |
2244 | } | |
2245 | ||
2246 | static void khugepaged_wait_work(void) | |
2247 | { | |
2248 | if (khugepaged_has_work()) { | |
2249 | const unsigned long scan_sleep_jiffies = | |
2250 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs); | |
2251 | ||
2252 | if (!scan_sleep_jiffies) | |
2253 | return; | |
2254 | ||
2255 | khugepaged_sleep_expire = jiffies + scan_sleep_jiffies; | |
2256 | wait_event_freezable_timeout(khugepaged_wait, | |
2257 | khugepaged_should_wakeup(), | |
2258 | scan_sleep_jiffies); | |
2259 | return; | |
2260 | } | |
2261 | ||
2262 | if (khugepaged_enabled()) | |
2263 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2264 | } | |
2265 | ||
2266 | static int khugepaged(void *none) | |
2267 | { | |
2268 | struct mm_slot *mm_slot; | |
2269 | ||
2270 | set_freezable(); | |
2271 | set_user_nice(current, MAX_NICE); | |
2272 | ||
2273 | while (!kthread_should_stop()) { | |
2274 | khugepaged_do_scan(); | |
2275 | khugepaged_wait_work(); | |
2276 | } | |
2277 | ||
2278 | spin_lock(&khugepaged_mm_lock); | |
2279 | mm_slot = khugepaged_scan.mm_slot; | |
2280 | khugepaged_scan.mm_slot = NULL; | |
2281 | if (mm_slot) | |
2282 | collect_mm_slot(mm_slot); | |
2283 | spin_unlock(&khugepaged_mm_lock); | |
2284 | return 0; | |
2285 | } | |
2286 | ||
2287 | static void set_recommended_min_free_kbytes(void) | |
2288 | { | |
2289 | struct zone *zone; | |
2290 | int nr_zones = 0; | |
2291 | unsigned long recommended_min; | |
2292 | ||
b7d349c7 JK |
2293 | for_each_populated_zone(zone) { |
2294 | /* | |
2295 | * We don't need to worry about fragmentation of | |
2296 | * ZONE_MOVABLE since it only has movable pages. | |
2297 | */ | |
2298 | if (zone_idx(zone) > gfp_zone(GFP_USER)) | |
2299 | continue; | |
2300 | ||
b46e756f | 2301 | nr_zones++; |
b7d349c7 | 2302 | } |
b46e756f KS |
2303 | |
2304 | /* Ensure 2 pageblocks are free to assist fragmentation avoidance */ | |
2305 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
2306 | ||
2307 | /* | |
2308 | * Make sure that on average at least two pageblocks are almost free | |
2309 | * of another type, one for a migratetype to fall back to and a | |
2310 | * second to avoid subsequent fallbacks of other types There are 3 | |
2311 | * MIGRATE_TYPES we care about. | |
2312 | */ | |
2313 | recommended_min += pageblock_nr_pages * nr_zones * | |
2314 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
2315 | ||
2316 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
2317 | recommended_min = min(recommended_min, | |
2318 | (unsigned long) nr_free_buffer_pages() / 20); | |
2319 | recommended_min <<= (PAGE_SHIFT-10); | |
2320 | ||
2321 | if (recommended_min > min_free_kbytes) { | |
2322 | if (user_min_free_kbytes >= 0) | |
2323 | pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n", | |
2324 | min_free_kbytes, recommended_min); | |
2325 | ||
2326 | min_free_kbytes = recommended_min; | |
2327 | } | |
2328 | setup_per_zone_wmarks(); | |
2329 | } | |
2330 | ||
2331 | int start_stop_khugepaged(void) | |
2332 | { | |
b46e756f KS |
2333 | int err = 0; |
2334 | ||
2335 | mutex_lock(&khugepaged_mutex); | |
2336 | if (khugepaged_enabled()) { | |
2337 | if (!khugepaged_thread) | |
2338 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
2339 | "khugepaged"); | |
2340 | if (IS_ERR(khugepaged_thread)) { | |
2341 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); | |
2342 | err = PTR_ERR(khugepaged_thread); | |
2343 | khugepaged_thread = NULL; | |
2344 | goto fail; | |
2345 | } | |
2346 | ||
2347 | if (!list_empty(&khugepaged_scan.mm_head)) | |
2348 | wake_up_interruptible(&khugepaged_wait); | |
2349 | ||
2350 | set_recommended_min_free_kbytes(); | |
2351 | } else if (khugepaged_thread) { | |
2352 | kthread_stop(khugepaged_thread); | |
2353 | khugepaged_thread = NULL; | |
2354 | } | |
2355 | fail: | |
2356 | mutex_unlock(&khugepaged_mutex); | |
2357 | return err; | |
2358 | } | |
4aab2be0 VB |
2359 | |
2360 | void khugepaged_min_free_kbytes_update(void) | |
2361 | { | |
2362 | mutex_lock(&khugepaged_mutex); | |
2363 | if (khugepaged_enabled() && khugepaged_thread) | |
2364 | set_recommended_min_free_kbytes(); | |
2365 | mutex_unlock(&khugepaged_mutex); | |
2366 | } |