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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> | |
80110bbf | 19 | #include <linux/page_table_check.h> |
b46e756f | 20 | #include <linux/swapops.h> |
f3f0e1d2 | 21 | #include <linux/shmem_fs.h> |
b46e756f KS |
22 | |
23 | #include <asm/tlb.h> | |
24 | #include <asm/pgalloc.h> | |
25 | #include "internal.h" | |
26 | ||
27 | enum scan_result { | |
28 | SCAN_FAIL, | |
29 | SCAN_SUCCEED, | |
30 | SCAN_PMD_NULL, | |
31 | SCAN_EXCEED_NONE_PTE, | |
71a2c112 KS |
32 | SCAN_EXCEED_SWAP_PTE, |
33 | SCAN_EXCEED_SHARED_PTE, | |
b46e756f | 34 | SCAN_PTE_NON_PRESENT, |
e1e267c7 | 35 | SCAN_PTE_UFFD_WP, |
b46e756f | 36 | SCAN_PAGE_RO, |
0db501f7 | 37 | SCAN_LACK_REFERENCED_PAGE, |
b46e756f KS |
38 | SCAN_PAGE_NULL, |
39 | SCAN_SCAN_ABORT, | |
40 | SCAN_PAGE_COUNT, | |
41 | SCAN_PAGE_LRU, | |
42 | SCAN_PAGE_LOCK, | |
43 | SCAN_PAGE_ANON, | |
44 | SCAN_PAGE_COMPOUND, | |
45 | SCAN_ANY_PROCESS, | |
46 | SCAN_VMA_NULL, | |
47 | SCAN_VMA_CHECK, | |
48 | SCAN_ADDRESS_RANGE, | |
49 | SCAN_SWAP_CACHE_PAGE, | |
50 | SCAN_DEL_PAGE_LRU, | |
51 | SCAN_ALLOC_HUGE_PAGE_FAIL, | |
52 | SCAN_CGROUP_CHARGE_FAIL, | |
f3f0e1d2 | 53 | SCAN_TRUNCATED, |
99cb0dbd | 54 | SCAN_PAGE_HAS_PRIVATE, |
b46e756f KS |
55 | }; |
56 | ||
57 | #define CREATE_TRACE_POINTS | |
58 | #include <trace/events/huge_memory.h> | |
59 | ||
4aab2be0 VB |
60 | static struct task_struct *khugepaged_thread __read_mostly; |
61 | static DEFINE_MUTEX(khugepaged_mutex); | |
62 | ||
b46e756f KS |
63 | /* default scan 8*512 pte (or vmas) every 30 second */ |
64 | static unsigned int khugepaged_pages_to_scan __read_mostly; | |
65 | static unsigned int khugepaged_pages_collapsed; | |
66 | static unsigned int khugepaged_full_scans; | |
67 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
68 | /* during fragmentation poll the hugepage allocator once every minute */ | |
69 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
70 | static unsigned long khugepaged_sleep_expire; | |
71 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
72 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
73 | /* | |
74 | * default collapse hugepages if there is at least one pte mapped like | |
75 | * it would have happened if the vma was large enough during page | |
76 | * fault. | |
77 | */ | |
78 | static unsigned int khugepaged_max_ptes_none __read_mostly; | |
79 | static unsigned int khugepaged_max_ptes_swap __read_mostly; | |
71a2c112 | 80 | static unsigned int khugepaged_max_ptes_shared __read_mostly; |
b46e756f KS |
81 | |
82 | #define MM_SLOTS_HASH_BITS 10 | |
83 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
84 | ||
85 | static struct kmem_cache *mm_slot_cache __read_mostly; | |
86 | ||
27e1f827 SL |
87 | #define MAX_PTE_MAPPED_THP 8 |
88 | ||
b46e756f KS |
89 | /** |
90 | * struct mm_slot - hash lookup from mm to mm_slot | |
91 | * @hash: hash collision list | |
92 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
93 | * @mm: the mm that this information is valid for | |
336e6b53 AS |
94 | * @nr_pte_mapped_thp: number of pte mapped THP |
95 | * @pte_mapped_thp: address array corresponding pte mapped THP | |
b46e756f KS |
96 | */ |
97 | struct mm_slot { | |
98 | struct hlist_node hash; | |
99 | struct list_head mm_node; | |
100 | struct mm_struct *mm; | |
27e1f827 SL |
101 | |
102 | /* pte-mapped THP in this mm */ | |
103 | int nr_pte_mapped_thp; | |
104 | unsigned long pte_mapped_thp[MAX_PTE_MAPPED_THP]; | |
b46e756f KS |
105 | }; |
106 | ||
107 | /** | |
108 | * struct khugepaged_scan - cursor for scanning | |
109 | * @mm_head: the head of the mm list to scan | |
110 | * @mm_slot: the current mm_slot we are scanning | |
111 | * @address: the next address inside that to be scanned | |
112 | * | |
113 | * There is only the one khugepaged_scan instance of this cursor structure. | |
114 | */ | |
115 | struct khugepaged_scan { | |
116 | struct list_head mm_head; | |
117 | struct mm_slot *mm_slot; | |
118 | unsigned long address; | |
119 | }; | |
120 | ||
121 | static struct khugepaged_scan khugepaged_scan = { | |
122 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), | |
123 | }; | |
124 | ||
e1465d12 | 125 | #ifdef CONFIG_SYSFS |
b46e756f KS |
126 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, |
127 | struct kobj_attribute *attr, | |
128 | char *buf) | |
129 | { | |
ae7a927d | 130 | return sysfs_emit(buf, "%u\n", khugepaged_scan_sleep_millisecs); |
b46e756f KS |
131 | } |
132 | ||
133 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
134 | struct kobj_attribute *attr, | |
135 | const char *buf, size_t count) | |
136 | { | |
dfefd226 | 137 | unsigned int msecs; |
b46e756f KS |
138 | int err; |
139 | ||
dfefd226 AD |
140 | err = kstrtouint(buf, 10, &msecs); |
141 | if (err) | |
b46e756f KS |
142 | return -EINVAL; |
143 | ||
144 | khugepaged_scan_sleep_millisecs = msecs; | |
145 | khugepaged_sleep_expire = 0; | |
146 | wake_up_interruptible(&khugepaged_wait); | |
147 | ||
148 | return count; | |
149 | } | |
150 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
151 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
152 | scan_sleep_millisecs_store); | |
153 | ||
154 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
155 | struct kobj_attribute *attr, | |
156 | char *buf) | |
157 | { | |
ae7a927d | 158 | return sysfs_emit(buf, "%u\n", khugepaged_alloc_sleep_millisecs); |
b46e756f KS |
159 | } |
160 | ||
161 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
162 | struct kobj_attribute *attr, | |
163 | const char *buf, size_t count) | |
164 | { | |
dfefd226 | 165 | unsigned int msecs; |
b46e756f KS |
166 | int err; |
167 | ||
dfefd226 AD |
168 | err = kstrtouint(buf, 10, &msecs); |
169 | if (err) | |
b46e756f KS |
170 | return -EINVAL; |
171 | ||
172 | khugepaged_alloc_sleep_millisecs = msecs; | |
173 | khugepaged_sleep_expire = 0; | |
174 | wake_up_interruptible(&khugepaged_wait); | |
175 | ||
176 | return count; | |
177 | } | |
178 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
179 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
180 | alloc_sleep_millisecs_store); | |
181 | ||
182 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
183 | struct kobj_attribute *attr, | |
184 | char *buf) | |
185 | { | |
ae7a927d | 186 | return sysfs_emit(buf, "%u\n", khugepaged_pages_to_scan); |
b46e756f KS |
187 | } |
188 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
189 | struct kobj_attribute *attr, | |
190 | const char *buf, size_t count) | |
191 | { | |
dfefd226 | 192 | unsigned int pages; |
b46e756f | 193 | int err; |
b46e756f | 194 | |
dfefd226 AD |
195 | err = kstrtouint(buf, 10, &pages); |
196 | if (err || !pages) | |
b46e756f KS |
197 | return -EINVAL; |
198 | ||
199 | khugepaged_pages_to_scan = pages; | |
200 | ||
201 | return count; | |
202 | } | |
203 | static struct kobj_attribute pages_to_scan_attr = | |
204 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
205 | pages_to_scan_store); | |
206 | ||
207 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
208 | struct kobj_attribute *attr, | |
209 | char *buf) | |
210 | { | |
ae7a927d | 211 | return sysfs_emit(buf, "%u\n", khugepaged_pages_collapsed); |
b46e756f KS |
212 | } |
213 | static struct kobj_attribute pages_collapsed_attr = | |
214 | __ATTR_RO(pages_collapsed); | |
215 | ||
216 | static ssize_t full_scans_show(struct kobject *kobj, | |
217 | struct kobj_attribute *attr, | |
218 | char *buf) | |
219 | { | |
ae7a927d | 220 | return sysfs_emit(buf, "%u\n", khugepaged_full_scans); |
b46e756f KS |
221 | } |
222 | static struct kobj_attribute full_scans_attr = | |
223 | __ATTR_RO(full_scans); | |
224 | ||
225 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
226 | struct kobj_attribute *attr, char *buf) | |
227 | { | |
228 | return single_hugepage_flag_show(kobj, attr, buf, | |
ae7a927d | 229 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); |
b46e756f KS |
230 | } |
231 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
232 | struct kobj_attribute *attr, | |
233 | const char *buf, size_t count) | |
234 | { | |
235 | return single_hugepage_flag_store(kobj, attr, buf, count, | |
236 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
237 | } | |
238 | static struct kobj_attribute khugepaged_defrag_attr = | |
239 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
240 | khugepaged_defrag_store); | |
241 | ||
242 | /* | |
243 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
244 | * any unmapped ptes in turn potentially increasing the memory | |
245 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
246 | * reduce the available free memory in the system as it | |
247 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
248 | * free memory in the system during the khugepaged scan. | |
249 | */ | |
250 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
251 | struct kobj_attribute *attr, | |
252 | char *buf) | |
253 | { | |
ae7a927d | 254 | return sysfs_emit(buf, "%u\n", khugepaged_max_ptes_none); |
b46e756f KS |
255 | } |
256 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
257 | struct kobj_attribute *attr, | |
258 | const char *buf, size_t count) | |
259 | { | |
260 | int err; | |
261 | unsigned long max_ptes_none; | |
262 | ||
263 | err = kstrtoul(buf, 10, &max_ptes_none); | |
264 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
265 | return -EINVAL; | |
266 | ||
267 | khugepaged_max_ptes_none = max_ptes_none; | |
268 | ||
269 | return count; | |
270 | } | |
271 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
272 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
273 | khugepaged_max_ptes_none_store); | |
274 | ||
275 | static ssize_t khugepaged_max_ptes_swap_show(struct kobject *kobj, | |
276 | struct kobj_attribute *attr, | |
277 | char *buf) | |
278 | { | |
ae7a927d | 279 | return sysfs_emit(buf, "%u\n", khugepaged_max_ptes_swap); |
b46e756f KS |
280 | } |
281 | ||
282 | static ssize_t khugepaged_max_ptes_swap_store(struct kobject *kobj, | |
283 | struct kobj_attribute *attr, | |
284 | const char *buf, size_t count) | |
285 | { | |
286 | int err; | |
287 | unsigned long max_ptes_swap; | |
288 | ||
289 | err = kstrtoul(buf, 10, &max_ptes_swap); | |
290 | if (err || max_ptes_swap > HPAGE_PMD_NR-1) | |
291 | return -EINVAL; | |
292 | ||
293 | khugepaged_max_ptes_swap = max_ptes_swap; | |
294 | ||
295 | return count; | |
296 | } | |
297 | ||
298 | static struct kobj_attribute khugepaged_max_ptes_swap_attr = | |
299 | __ATTR(max_ptes_swap, 0644, khugepaged_max_ptes_swap_show, | |
300 | khugepaged_max_ptes_swap_store); | |
301 | ||
71a2c112 | 302 | static ssize_t khugepaged_max_ptes_shared_show(struct kobject *kobj, |
ae7a927d JP |
303 | struct kobj_attribute *attr, |
304 | char *buf) | |
71a2c112 | 305 | { |
ae7a927d | 306 | return sysfs_emit(buf, "%u\n", khugepaged_max_ptes_shared); |
71a2c112 KS |
307 | } |
308 | ||
309 | static ssize_t khugepaged_max_ptes_shared_store(struct kobject *kobj, | |
310 | struct kobj_attribute *attr, | |
311 | const char *buf, size_t count) | |
312 | { | |
313 | int err; | |
314 | unsigned long max_ptes_shared; | |
315 | ||
316 | err = kstrtoul(buf, 10, &max_ptes_shared); | |
317 | if (err || max_ptes_shared > HPAGE_PMD_NR-1) | |
318 | return -EINVAL; | |
319 | ||
320 | khugepaged_max_ptes_shared = max_ptes_shared; | |
321 | ||
322 | return count; | |
323 | } | |
324 | ||
325 | static struct kobj_attribute khugepaged_max_ptes_shared_attr = | |
326 | __ATTR(max_ptes_shared, 0644, khugepaged_max_ptes_shared_show, | |
327 | khugepaged_max_ptes_shared_store); | |
328 | ||
b46e756f KS |
329 | static struct attribute *khugepaged_attr[] = { |
330 | &khugepaged_defrag_attr.attr, | |
331 | &khugepaged_max_ptes_none_attr.attr, | |
71a2c112 KS |
332 | &khugepaged_max_ptes_swap_attr.attr, |
333 | &khugepaged_max_ptes_shared_attr.attr, | |
b46e756f KS |
334 | &pages_to_scan_attr.attr, |
335 | &pages_collapsed_attr.attr, | |
336 | &full_scans_attr.attr, | |
337 | &scan_sleep_millisecs_attr.attr, | |
338 | &alloc_sleep_millisecs_attr.attr, | |
b46e756f KS |
339 | NULL, |
340 | }; | |
341 | ||
342 | struct attribute_group khugepaged_attr_group = { | |
343 | .attrs = khugepaged_attr, | |
344 | .name = "khugepaged", | |
345 | }; | |
e1465d12 | 346 | #endif /* CONFIG_SYSFS */ |
b46e756f | 347 | |
b46e756f KS |
348 | int hugepage_madvise(struct vm_area_struct *vma, |
349 | unsigned long *vm_flags, int advice) | |
350 | { | |
351 | switch (advice) { | |
352 | case MADV_HUGEPAGE: | |
353 | #ifdef CONFIG_S390 | |
354 | /* | |
355 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
356 | * can't handle this properly after s390_enable_sie, so we simply | |
357 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
358 | */ | |
359 | if (mm_has_pgste(vma->vm_mm)) | |
360 | return 0; | |
361 | #endif | |
362 | *vm_flags &= ~VM_NOHUGEPAGE; | |
363 | *vm_flags |= VM_HUGEPAGE; | |
364 | /* | |
365 | * If the vma become good for khugepaged to scan, | |
366 | * register it here without waiting a page fault that | |
367 | * may not happen any time soon. | |
368 | */ | |
369 | if (!(*vm_flags & VM_NO_KHUGEPAGED) && | |
370 | khugepaged_enter_vma_merge(vma, *vm_flags)) | |
371 | return -ENOMEM; | |
372 | break; | |
373 | case MADV_NOHUGEPAGE: | |
374 | *vm_flags &= ~VM_HUGEPAGE; | |
375 | *vm_flags |= VM_NOHUGEPAGE; | |
376 | /* | |
377 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
378 | * this vma even if we leave the mm registered in khugepaged if | |
379 | * it got registered before VM_NOHUGEPAGE was set. | |
380 | */ | |
381 | break; | |
382 | } | |
383 | ||
384 | return 0; | |
385 | } | |
386 | ||
387 | int __init khugepaged_init(void) | |
388 | { | |
389 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
390 | sizeof(struct mm_slot), | |
391 | __alignof__(struct mm_slot), 0, NULL); | |
392 | if (!mm_slot_cache) | |
393 | return -ENOMEM; | |
394 | ||
395 | khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; | |
396 | khugepaged_max_ptes_none = HPAGE_PMD_NR - 1; | |
397 | khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8; | |
71a2c112 | 398 | khugepaged_max_ptes_shared = HPAGE_PMD_NR / 2; |
b46e756f KS |
399 | |
400 | return 0; | |
401 | } | |
402 | ||
403 | void __init khugepaged_destroy(void) | |
404 | { | |
405 | kmem_cache_destroy(mm_slot_cache); | |
406 | } | |
407 | ||
408 | static inline struct mm_slot *alloc_mm_slot(void) | |
409 | { | |
410 | if (!mm_slot_cache) /* initialization failed */ | |
411 | return NULL; | |
412 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
413 | } | |
414 | ||
415 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
416 | { | |
417 | kmem_cache_free(mm_slot_cache, mm_slot); | |
418 | } | |
419 | ||
420 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
421 | { | |
422 | struct mm_slot *mm_slot; | |
423 | ||
424 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) | |
425 | if (mm == mm_slot->mm) | |
426 | return mm_slot; | |
427 | ||
428 | return NULL; | |
429 | } | |
430 | ||
431 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
432 | struct mm_slot *mm_slot) | |
433 | { | |
434 | mm_slot->mm = mm; | |
435 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); | |
436 | } | |
437 | ||
438 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
439 | { | |
4d45e75a | 440 | return atomic_read(&mm->mm_users) == 0; |
b46e756f KS |
441 | } |
442 | ||
50f8b92f SL |
443 | static bool hugepage_vma_check(struct vm_area_struct *vma, |
444 | unsigned long vm_flags) | |
c2231020 | 445 | { |
e6be37b2 | 446 | if (!transhuge_vma_enabled(vma, vm_flags)) |
c2231020 | 447 | return false; |
99cb0dbd | 448 | |
a4aeaa06 YS |
449 | if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - |
450 | vma->vm_pgoff, HPAGE_PMD_NR)) | |
451 | return false; | |
452 | ||
cd89fb06 | 453 | /* Enabled via shmem mount options or sysfs settings. */ |
a4aeaa06 YS |
454 | if (shmem_file(vma->vm_file)) |
455 | return shmem_huge_enabled(vma); | |
cd89fb06 RR |
456 | |
457 | /* THP settings require madvise. */ | |
458 | if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) | |
459 | return false; | |
460 | ||
a4aeaa06 | 461 | /* Only regular file is valid */ |
cd89fb06 | 462 | if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && vma->vm_file && |
eb6ecbed | 463 | (vm_flags & VM_EXEC)) { |
a4aeaa06 YS |
464 | struct inode *inode = vma->vm_file->f_inode; |
465 | ||
466 | return !inode_is_open_for_write(inode) && | |
467 | S_ISREG(inode->i_mode); | |
cd89fb06 RR |
468 | } |
469 | ||
c2231020 YS |
470 | if (!vma->anon_vma || vma->vm_ops) |
471 | return false; | |
222100ee | 472 | if (vma_is_temporary_stack(vma)) |
c2231020 | 473 | return false; |
50f8b92f | 474 | return !(vm_flags & VM_NO_KHUGEPAGED); |
c2231020 YS |
475 | } |
476 | ||
b46e756f KS |
477 | int __khugepaged_enter(struct mm_struct *mm) |
478 | { | |
479 | struct mm_slot *mm_slot; | |
480 | int wakeup; | |
481 | ||
482 | mm_slot = alloc_mm_slot(); | |
483 | if (!mm_slot) | |
484 | return -ENOMEM; | |
485 | ||
486 | /* __khugepaged_exit() must not run from under us */ | |
28ff0a3c | 487 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); |
b46e756f KS |
488 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { |
489 | free_mm_slot(mm_slot); | |
490 | return 0; | |
491 | } | |
492 | ||
493 | spin_lock(&khugepaged_mm_lock); | |
494 | insert_to_mm_slots_hash(mm, mm_slot); | |
495 | /* | |
496 | * Insert just behind the scanning cursor, to let the area settle | |
497 | * down a little. | |
498 | */ | |
499 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
500 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
501 | spin_unlock(&khugepaged_mm_lock); | |
502 | ||
f1f10076 | 503 | mmgrab(mm); |
b46e756f KS |
504 | if (wakeup) |
505 | wake_up_interruptible(&khugepaged_wait); | |
506 | ||
507 | return 0; | |
508 | } | |
509 | ||
510 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, | |
511 | unsigned long vm_flags) | |
512 | { | |
513 | unsigned long hstart, hend; | |
c2231020 YS |
514 | |
515 | /* | |
99cb0dbd SL |
516 | * khugepaged only supports read-only files for non-shmem files. |
517 | * khugepaged does not yet work on special mappings. And | |
518 | * file-private shmem THP is not supported. | |
c2231020 | 519 | */ |
50f8b92f | 520 | if (!hugepage_vma_check(vma, vm_flags)) |
b46e756f | 521 | return 0; |
c2231020 | 522 | |
b46e756f KS |
523 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; |
524 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
525 | if (hstart < hend) | |
526 | return khugepaged_enter(vma, vm_flags); | |
527 | return 0; | |
528 | } | |
529 | ||
530 | void __khugepaged_exit(struct mm_struct *mm) | |
531 | { | |
532 | struct mm_slot *mm_slot; | |
533 | int free = 0; | |
534 | ||
535 | spin_lock(&khugepaged_mm_lock); | |
536 | mm_slot = get_mm_slot(mm); | |
537 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
538 | hash_del(&mm_slot->hash); | |
539 | list_del(&mm_slot->mm_node); | |
540 | free = 1; | |
541 | } | |
542 | spin_unlock(&khugepaged_mm_lock); | |
543 | ||
544 | if (free) { | |
545 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
546 | free_mm_slot(mm_slot); | |
547 | mmdrop(mm); | |
548 | } else if (mm_slot) { | |
549 | /* | |
550 | * This is required to serialize against | |
551 | * khugepaged_test_exit() (which is guaranteed to run | |
552 | * under mmap sem read mode). Stop here (after we | |
553 | * return all pagetables will be destroyed) until | |
554 | * khugepaged has finished working on the pagetables | |
c1e8d7c6 | 555 | * under the mmap_lock. |
b46e756f | 556 | */ |
d8ed45c5 ML |
557 | mmap_write_lock(mm); |
558 | mmap_write_unlock(mm); | |
b46e756f KS |
559 | } |
560 | } | |
561 | ||
562 | static void release_pte_page(struct page *page) | |
563 | { | |
5503fbf2 KS |
564 | mod_node_page_state(page_pgdat(page), |
565 | NR_ISOLATED_ANON + page_is_file_lru(page), | |
566 | -compound_nr(page)); | |
b46e756f KS |
567 | unlock_page(page); |
568 | putback_lru_page(page); | |
569 | } | |
570 | ||
5503fbf2 KS |
571 | static void release_pte_pages(pte_t *pte, pte_t *_pte, |
572 | struct list_head *compound_pagelist) | |
b46e756f | 573 | { |
5503fbf2 KS |
574 | struct page *page, *tmp; |
575 | ||
b46e756f KS |
576 | while (--_pte >= pte) { |
577 | pte_t pteval = *_pte; | |
5503fbf2 KS |
578 | |
579 | page = pte_page(pteval); | |
580 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)) && | |
581 | !PageCompound(page)) | |
582 | release_pte_page(page); | |
583 | } | |
584 | ||
585 | list_for_each_entry_safe(page, tmp, compound_pagelist, lru) { | |
586 | list_del(&page->lru); | |
587 | release_pte_page(page); | |
b46e756f KS |
588 | } |
589 | } | |
590 | ||
9445689f KS |
591 | static bool is_refcount_suitable(struct page *page) |
592 | { | |
593 | int expected_refcount; | |
594 | ||
595 | expected_refcount = total_mapcount(page); | |
596 | if (PageSwapCache(page)) | |
597 | expected_refcount += compound_nr(page); | |
598 | ||
599 | return page_count(page) == expected_refcount; | |
600 | } | |
601 | ||
b46e756f KS |
602 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, |
603 | unsigned long address, | |
5503fbf2 KS |
604 | pte_t *pte, |
605 | struct list_head *compound_pagelist) | |
b46e756f KS |
606 | { |
607 | struct page *page = NULL; | |
608 | pte_t *_pte; | |
71a2c112 | 609 | int none_or_zero = 0, shared = 0, result = 0, referenced = 0; |
0db501f7 | 610 | bool writable = false; |
b46e756f KS |
611 | |
612 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
613 | _pte++, address += PAGE_SIZE) { | |
614 | pte_t pteval = *_pte; | |
615 | if (pte_none(pteval) || (pte_present(pteval) && | |
616 | is_zero_pfn(pte_pfn(pteval)))) { | |
617 | if (!userfaultfd_armed(vma) && | |
618 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
619 | continue; | |
620 | } else { | |
621 | result = SCAN_EXCEED_NONE_PTE; | |
e9ea874a | 622 | count_vm_event(THP_SCAN_EXCEED_NONE_PTE); |
b46e756f KS |
623 | goto out; |
624 | } | |
625 | } | |
626 | if (!pte_present(pteval)) { | |
627 | result = SCAN_PTE_NON_PRESENT; | |
628 | goto out; | |
629 | } | |
630 | page = vm_normal_page(vma, address, pteval); | |
631 | if (unlikely(!page)) { | |
632 | result = SCAN_PAGE_NULL; | |
633 | goto out; | |
634 | } | |
635 | ||
5503fbf2 KS |
636 | VM_BUG_ON_PAGE(!PageAnon(page), page); |
637 | ||
71a2c112 KS |
638 | if (page_mapcount(page) > 1 && |
639 | ++shared > khugepaged_max_ptes_shared) { | |
640 | result = SCAN_EXCEED_SHARED_PTE; | |
e9ea874a | 641 | count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); |
71a2c112 KS |
642 | goto out; |
643 | } | |
644 | ||
fece2029 | 645 | if (PageCompound(page)) { |
5503fbf2 KS |
646 | struct page *p; |
647 | page = compound_head(page); | |
fece2029 | 648 | |
5503fbf2 KS |
649 | /* |
650 | * Check if we have dealt with the compound page | |
651 | * already | |
652 | */ | |
653 | list_for_each_entry(p, compound_pagelist, lru) { | |
654 | if (page == p) | |
655 | goto next; | |
656 | } | |
657 | } | |
b46e756f KS |
658 | |
659 | /* | |
660 | * We can do it before isolate_lru_page because the | |
661 | * page can't be freed from under us. NOTE: PG_lock | |
662 | * is needed to serialize against split_huge_page | |
663 | * when invoked from the VM. | |
664 | */ | |
665 | if (!trylock_page(page)) { | |
666 | result = SCAN_PAGE_LOCK; | |
667 | goto out; | |
668 | } | |
669 | ||
670 | /* | |
9445689f KS |
671 | * Check if the page has any GUP (or other external) pins. |
672 | * | |
673 | * The page table that maps the page has been already unlinked | |
674 | * from the page table tree and this process cannot get | |
f0953a1b | 675 | * an additional pin on the page. |
9445689f KS |
676 | * |
677 | * New pins can come later if the page is shared across fork, | |
678 | * but not from this process. The other process cannot write to | |
679 | * the page, only trigger CoW. | |
b46e756f | 680 | */ |
9445689f | 681 | if (!is_refcount_suitable(page)) { |
b46e756f KS |
682 | unlock_page(page); |
683 | result = SCAN_PAGE_COUNT; | |
684 | goto out; | |
685 | } | |
5503fbf2 | 686 | if (!pte_write(pteval) && PageSwapCache(page) && |
020e8765 | 687 | !reuse_swap_page(page)) { |
b46e756f | 688 | /* |
5503fbf2 KS |
689 | * Page is in the swap cache and cannot be re-used. |
690 | * It cannot be collapsed into a THP. | |
b46e756f | 691 | */ |
5503fbf2 KS |
692 | unlock_page(page); |
693 | result = SCAN_SWAP_CACHE_PAGE; | |
694 | goto out; | |
b46e756f KS |
695 | } |
696 | ||
697 | /* | |
698 | * Isolate the page to avoid collapsing an hugepage | |
699 | * currently in use by the VM. | |
700 | */ | |
701 | if (isolate_lru_page(page)) { | |
702 | unlock_page(page); | |
703 | result = SCAN_DEL_PAGE_LRU; | |
704 | goto out; | |
705 | } | |
5503fbf2 KS |
706 | mod_node_page_state(page_pgdat(page), |
707 | NR_ISOLATED_ANON + page_is_file_lru(page), | |
708 | compound_nr(page)); | |
b46e756f KS |
709 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
710 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
711 | ||
5503fbf2 KS |
712 | if (PageCompound(page)) |
713 | list_add_tail(&page->lru, compound_pagelist); | |
714 | next: | |
0db501f7 | 715 | /* There should be enough young pte to collapse the page */ |
b46e756f KS |
716 | if (pte_young(pteval) || |
717 | page_is_young(page) || PageReferenced(page) || | |
718 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 719 | referenced++; |
5503fbf2 KS |
720 | |
721 | if (pte_write(pteval)) | |
722 | writable = true; | |
b46e756f | 723 | } |
74e579bf ML |
724 | |
725 | if (unlikely(!writable)) { | |
b46e756f | 726 | result = SCAN_PAGE_RO; |
74e579bf ML |
727 | } else if (unlikely(!referenced)) { |
728 | result = SCAN_LACK_REFERENCED_PAGE; | |
729 | } else { | |
730 | result = SCAN_SUCCEED; | |
731 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, | |
732 | referenced, writable, result); | |
733 | return 1; | |
b46e756f | 734 | } |
b46e756f | 735 | out: |
5503fbf2 | 736 | release_pte_pages(pte, _pte, compound_pagelist); |
b46e756f KS |
737 | trace_mm_collapse_huge_page_isolate(page, none_or_zero, |
738 | referenced, writable, result); | |
739 | return 0; | |
740 | } | |
741 | ||
742 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
743 | struct vm_area_struct *vma, | |
744 | unsigned long address, | |
5503fbf2 KS |
745 | spinlock_t *ptl, |
746 | struct list_head *compound_pagelist) | |
b46e756f | 747 | { |
5503fbf2 | 748 | struct page *src_page, *tmp; |
b46e756f | 749 | pte_t *_pte; |
338a16ba DR |
750 | for (_pte = pte; _pte < pte + HPAGE_PMD_NR; |
751 | _pte++, page++, address += PAGE_SIZE) { | |
b46e756f | 752 | pte_t pteval = *_pte; |
b46e756f KS |
753 | |
754 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
755 | clear_user_highpage(page, address); | |
756 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
757 | if (is_zero_pfn(pte_pfn(pteval))) { | |
758 | /* | |
759 | * ptl mostly unnecessary. | |
760 | */ | |
761 | spin_lock(ptl); | |
08d5b29e | 762 | ptep_clear(vma->vm_mm, address, _pte); |
b46e756f KS |
763 | spin_unlock(ptl); |
764 | } | |
765 | } else { | |
766 | src_page = pte_page(pteval); | |
767 | copy_user_highpage(page, src_page, address, vma); | |
5503fbf2 KS |
768 | if (!PageCompound(src_page)) |
769 | release_pte_page(src_page); | |
b46e756f KS |
770 | /* |
771 | * ptl mostly unnecessary, but preempt has to | |
772 | * be disabled to update the per-cpu stats | |
773 | * inside page_remove_rmap(). | |
774 | */ | |
775 | spin_lock(ptl); | |
08d5b29e | 776 | ptep_clear(vma->vm_mm, address, _pte); |
b46e756f KS |
777 | page_remove_rmap(src_page, false); |
778 | spin_unlock(ptl); | |
779 | free_page_and_swap_cache(src_page); | |
780 | } | |
b46e756f | 781 | } |
5503fbf2 KS |
782 | |
783 | list_for_each_entry_safe(src_page, tmp, compound_pagelist, lru) { | |
784 | list_del(&src_page->lru); | |
785 | release_pte_page(src_page); | |
786 | } | |
b46e756f KS |
787 | } |
788 | ||
789 | static void khugepaged_alloc_sleep(void) | |
790 | { | |
791 | DEFINE_WAIT(wait); | |
792 | ||
793 | add_wait_queue(&khugepaged_wait, &wait); | |
794 | freezable_schedule_timeout_interruptible( | |
795 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
796 | remove_wait_queue(&khugepaged_wait, &wait); | |
797 | } | |
798 | ||
799 | static int khugepaged_node_load[MAX_NUMNODES]; | |
800 | ||
801 | static bool khugepaged_scan_abort(int nid) | |
802 | { | |
803 | int i; | |
804 | ||
805 | /* | |
a5f5f91d | 806 | * If node_reclaim_mode is disabled, then no extra effort is made to |
b46e756f KS |
807 | * allocate memory locally. |
808 | */ | |
202e35db | 809 | if (!node_reclaim_enabled()) |
b46e756f KS |
810 | return false; |
811 | ||
812 | /* If there is a count for this node already, it must be acceptable */ | |
813 | if (khugepaged_node_load[nid]) | |
814 | return false; | |
815 | ||
816 | for (i = 0; i < MAX_NUMNODES; i++) { | |
817 | if (!khugepaged_node_load[i]) | |
818 | continue; | |
a55c7454 | 819 | if (node_distance(nid, i) > node_reclaim_distance) |
b46e756f KS |
820 | return true; |
821 | } | |
822 | return false; | |
823 | } | |
824 | ||
825 | /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */ | |
826 | static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void) | |
827 | { | |
25160354 | 828 | return khugepaged_defrag() ? GFP_TRANSHUGE : GFP_TRANSHUGE_LIGHT; |
b46e756f KS |
829 | } |
830 | ||
831 | #ifdef CONFIG_NUMA | |
832 | static int khugepaged_find_target_node(void) | |
833 | { | |
834 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
835 | int nid, target_node = 0, max_value = 0; | |
836 | ||
837 | /* find first node with max normal pages hit */ | |
838 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
839 | if (khugepaged_node_load[nid] > max_value) { | |
840 | max_value = khugepaged_node_load[nid]; | |
841 | target_node = nid; | |
842 | } | |
843 | ||
844 | /* do some balance if several nodes have the same hit record */ | |
845 | if (target_node <= last_khugepaged_target_node) | |
846 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
847 | nid++) | |
848 | if (max_value == khugepaged_node_load[nid]) { | |
849 | target_node = nid; | |
850 | break; | |
851 | } | |
852 | ||
853 | last_khugepaged_target_node = target_node; | |
854 | return target_node; | |
855 | } | |
856 | ||
857 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
858 | { | |
859 | if (IS_ERR(*hpage)) { | |
860 | if (!*wait) | |
861 | return false; | |
862 | ||
863 | *wait = false; | |
864 | *hpage = NULL; | |
865 | khugepaged_alloc_sleep(); | |
866 | } else if (*hpage) { | |
867 | put_page(*hpage); | |
868 | *hpage = NULL; | |
869 | } | |
870 | ||
871 | return true; | |
872 | } | |
873 | ||
874 | static struct page * | |
988ddb71 | 875 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f KS |
876 | { |
877 | VM_BUG_ON_PAGE(*hpage, *hpage); | |
878 | ||
b46e756f KS |
879 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); |
880 | if (unlikely(!*hpage)) { | |
881 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
882 | *hpage = ERR_PTR(-ENOMEM); | |
883 | return NULL; | |
884 | } | |
885 | ||
886 | prep_transhuge_page(*hpage); | |
887 | count_vm_event(THP_COLLAPSE_ALLOC); | |
888 | return *hpage; | |
889 | } | |
890 | #else | |
891 | static int khugepaged_find_target_node(void) | |
892 | { | |
893 | return 0; | |
894 | } | |
895 | ||
896 | static inline struct page *alloc_khugepaged_hugepage(void) | |
897 | { | |
898 | struct page *page; | |
899 | ||
900 | page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(), | |
901 | HPAGE_PMD_ORDER); | |
902 | if (page) | |
903 | prep_transhuge_page(page); | |
904 | return page; | |
905 | } | |
906 | ||
907 | static struct page *khugepaged_alloc_hugepage(bool *wait) | |
908 | { | |
909 | struct page *hpage; | |
910 | ||
911 | do { | |
912 | hpage = alloc_khugepaged_hugepage(); | |
913 | if (!hpage) { | |
914 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
915 | if (!*wait) | |
916 | return NULL; | |
917 | ||
918 | *wait = false; | |
919 | khugepaged_alloc_sleep(); | |
920 | } else | |
921 | count_vm_event(THP_COLLAPSE_ALLOC); | |
922 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
923 | ||
924 | return hpage; | |
925 | } | |
926 | ||
927 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
928 | { | |
033b5d77 HD |
929 | /* |
930 | * If the hpage allocated earlier was briefly exposed in page cache | |
931 | * before collapse_file() failed, it is possible that racing lookups | |
932 | * have not yet completed, and would then be unpleasantly surprised by | |
933 | * finding the hpage reused for the same mapping at a different offset. | |
934 | * Just release the previous allocation if there is any danger of that. | |
935 | */ | |
936 | if (*hpage && page_count(*hpage) > 1) { | |
937 | put_page(*hpage); | |
938 | *hpage = NULL; | |
939 | } | |
940 | ||
b46e756f KS |
941 | if (!*hpage) |
942 | *hpage = khugepaged_alloc_hugepage(wait); | |
943 | ||
944 | if (unlikely(!*hpage)) | |
945 | return false; | |
946 | ||
947 | return true; | |
948 | } | |
949 | ||
950 | static struct page * | |
988ddb71 | 951 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) |
b46e756f | 952 | { |
b46e756f KS |
953 | VM_BUG_ON(!*hpage); |
954 | ||
955 | return *hpage; | |
956 | } | |
957 | #endif | |
958 | ||
b46e756f | 959 | /* |
c1e8d7c6 ML |
960 | * If mmap_lock temporarily dropped, revalidate vma |
961 | * before taking mmap_lock. | |
b46e756f KS |
962 | * Return 0 if succeeds, otherwise return none-zero |
963 | * value (scan code). | |
964 | */ | |
965 | ||
c131f751 KS |
966 | static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, |
967 | struct vm_area_struct **vmap) | |
b46e756f KS |
968 | { |
969 | struct vm_area_struct *vma; | |
970 | unsigned long hstart, hend; | |
971 | ||
972 | if (unlikely(khugepaged_test_exit(mm))) | |
973 | return SCAN_ANY_PROCESS; | |
974 | ||
c131f751 | 975 | *vmap = vma = find_vma(mm, address); |
b46e756f KS |
976 | if (!vma) |
977 | return SCAN_VMA_NULL; | |
978 | ||
979 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
980 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
981 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) | |
982 | return SCAN_ADDRESS_RANGE; | |
50f8b92f | 983 | if (!hugepage_vma_check(vma, vma->vm_flags)) |
b46e756f | 984 | return SCAN_VMA_CHECK; |
594cced1 KS |
985 | /* Anon VMA expected */ |
986 | if (!vma->anon_vma || vma->vm_ops) | |
987 | return SCAN_VMA_CHECK; | |
b46e756f KS |
988 | return 0; |
989 | } | |
990 | ||
991 | /* | |
992 | * Bring missing pages in from swap, to complete THP collapse. | |
993 | * Only done if khugepaged_scan_pmd believes it is worthwhile. | |
994 | * | |
995 | * Called and returns without pte mapped or spinlocks held, | |
c1e8d7c6 | 996 | * but with mmap_lock held to protect against vma changes. |
b46e756f KS |
997 | */ |
998 | ||
999 | static bool __collapse_huge_page_swapin(struct mm_struct *mm, | |
1000 | struct vm_area_struct *vma, | |
2b635dd3 | 1001 | unsigned long haddr, pmd_t *pmd, |
0db501f7 | 1002 | int referenced) |
b46e756f | 1003 | { |
2b740303 SJ |
1004 | int swapped_in = 0; |
1005 | vm_fault_t ret = 0; | |
2b635dd3 WD |
1006 | unsigned long address, end = haddr + (HPAGE_PMD_NR * PAGE_SIZE); |
1007 | ||
1008 | for (address = haddr; address < end; address += PAGE_SIZE) { | |
1009 | struct vm_fault vmf = { | |
1010 | .vma = vma, | |
1011 | .address = address, | |
1012 | .pgoff = linear_page_index(vma, haddr), | |
1013 | .flags = FAULT_FLAG_ALLOW_RETRY, | |
1014 | .pmd = pmd, | |
1015 | }; | |
1016 | ||
1017 | vmf.pte = pte_offset_map(pmd, address); | |
2994302b | 1018 | vmf.orig_pte = *vmf.pte; |
2b635dd3 WD |
1019 | if (!is_swap_pte(vmf.orig_pte)) { |
1020 | pte_unmap(vmf.pte); | |
b46e756f | 1021 | continue; |
2b635dd3 | 1022 | } |
b46e756f | 1023 | swapped_in++; |
2994302b | 1024 | ret = do_swap_page(&vmf); |
0db501f7 | 1025 | |
c1e8d7c6 | 1026 | /* do_swap_page returns VM_FAULT_RETRY with released mmap_lock */ |
b46e756f | 1027 | if (ret & VM_FAULT_RETRY) { |
d8ed45c5 | 1028 | mmap_read_lock(mm); |
2b635dd3 | 1029 | if (hugepage_vma_revalidate(mm, haddr, &vma)) { |
47f863ea | 1030 | /* vma is no longer available, don't continue to swapin */ |
0db501f7 | 1031 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f | 1032 | return false; |
47f863ea | 1033 | } |
b46e756f | 1034 | /* check if the pmd is still valid */ |
2b635dd3 | 1035 | if (mm_find_pmd(mm, haddr) != pmd) { |
835152a2 | 1036 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f | 1037 | return false; |
835152a2 | 1038 | } |
b46e756f KS |
1039 | } |
1040 | if (ret & VM_FAULT_ERROR) { | |
0db501f7 | 1041 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); |
b46e756f KS |
1042 | return false; |
1043 | } | |
b46e756f | 1044 | } |
ae2c5d80 KS |
1045 | |
1046 | /* Drain LRU add pagevec to remove extra pin on the swapped in pages */ | |
1047 | if (swapped_in) | |
1048 | lru_add_drain(); | |
1049 | ||
0db501f7 | 1050 | trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1); |
b46e756f KS |
1051 | return true; |
1052 | } | |
1053 | ||
1054 | static void collapse_huge_page(struct mm_struct *mm, | |
1055 | unsigned long address, | |
1056 | struct page **hpage, | |
ffe945e6 | 1057 | int node, int referenced, int unmapped) |
b46e756f | 1058 | { |
5503fbf2 | 1059 | LIST_HEAD(compound_pagelist); |
b46e756f KS |
1060 | pmd_t *pmd, _pmd; |
1061 | pte_t *pte; | |
1062 | pgtable_t pgtable; | |
1063 | struct page *new_page; | |
1064 | spinlock_t *pmd_ptl, *pte_ptl; | |
1065 | int isolated = 0, result = 0; | |
c131f751 | 1066 | struct vm_area_struct *vma; |
ac46d4f3 | 1067 | struct mmu_notifier_range range; |
b46e756f KS |
1068 | gfp_t gfp; |
1069 | ||
1070 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1071 | ||
1072 | /* Only allocate from the target node */ | |
41b6167e | 1073 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
b46e756f | 1074 | |
988ddb71 | 1075 | /* |
c1e8d7c6 | 1076 | * Before allocating the hugepage, release the mmap_lock read lock. |
988ddb71 | 1077 | * The allocation can take potentially a long time if it involves |
c1e8d7c6 | 1078 | * sync compaction, and we do not need to hold the mmap_lock during |
988ddb71 KS |
1079 | * that. We will recheck the vma after taking it again in write mode. |
1080 | */ | |
d8ed45c5 | 1081 | mmap_read_unlock(mm); |
988ddb71 | 1082 | new_page = khugepaged_alloc_page(hpage, gfp, node); |
b46e756f KS |
1083 | if (!new_page) { |
1084 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
1085 | goto out_nolock; | |
1086 | } | |
1087 | ||
8f425e4e | 1088 | if (unlikely(mem_cgroup_charge(page_folio(new_page), mm, gfp))) { |
b46e756f KS |
1089 | result = SCAN_CGROUP_CHARGE_FAIL; |
1090 | goto out_nolock; | |
1091 | } | |
9d82c694 | 1092 | count_memcg_page_event(new_page, THP_COLLAPSE_ALLOC); |
b46e756f | 1093 | |
d8ed45c5 | 1094 | mmap_read_lock(mm); |
c131f751 | 1095 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f | 1096 | if (result) { |
d8ed45c5 | 1097 | mmap_read_unlock(mm); |
b46e756f KS |
1098 | goto out_nolock; |
1099 | } | |
1100 | ||
1101 | pmd = mm_find_pmd(mm, address); | |
1102 | if (!pmd) { | |
1103 | result = SCAN_PMD_NULL; | |
d8ed45c5 | 1104 | mmap_read_unlock(mm); |
b46e756f KS |
1105 | goto out_nolock; |
1106 | } | |
1107 | ||
1108 | /* | |
c1e8d7c6 ML |
1109 | * __collapse_huge_page_swapin always returns with mmap_lock locked. |
1110 | * If it fails, we release mmap_lock and jump out_nolock. | |
b46e756f KS |
1111 | * Continuing to collapse causes inconsistency. |
1112 | */ | |
ffe945e6 KS |
1113 | if (unmapped && !__collapse_huge_page_swapin(mm, vma, address, |
1114 | pmd, referenced)) { | |
d8ed45c5 | 1115 | mmap_read_unlock(mm); |
b46e756f KS |
1116 | goto out_nolock; |
1117 | } | |
1118 | ||
d8ed45c5 | 1119 | mmap_read_unlock(mm); |
b46e756f KS |
1120 | /* |
1121 | * Prevent all access to pagetables with the exception of | |
1122 | * gup_fast later handled by the ptep_clear_flush and the VM | |
1123 | * handled by the anon_vma lock + PG_lock. | |
1124 | */ | |
d8ed45c5 | 1125 | mmap_write_lock(mm); |
c131f751 | 1126 | result = hugepage_vma_revalidate(mm, address, &vma); |
b46e756f | 1127 | if (result) |
18d24a7c | 1128 | goto out_up_write; |
b46e756f KS |
1129 | /* check if the pmd is still valid */ |
1130 | if (mm_find_pmd(mm, address) != pmd) | |
18d24a7c | 1131 | goto out_up_write; |
b46e756f KS |
1132 | |
1133 | anon_vma_lock_write(vma->anon_vma); | |
1134 | ||
7269f999 | 1135 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, |
6f4f13e8 | 1136 | address, address + HPAGE_PMD_SIZE); |
ac46d4f3 | 1137 | mmu_notifier_invalidate_range_start(&range); |
ec649c9d VS |
1138 | |
1139 | pte = pte_offset_map(pmd, address); | |
1140 | pte_ptl = pte_lockptr(mm, pmd); | |
1141 | ||
b46e756f KS |
1142 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ |
1143 | /* | |
1144 | * After this gup_fast can't run anymore. This also removes | |
1145 | * any huge TLB entry from the CPU so we won't allow | |
1146 | * huge and small TLB entries for the same virtual address | |
1147 | * to avoid the risk of CPU bugs in that area. | |
1148 | */ | |
1149 | _pmd = pmdp_collapse_flush(vma, address, pmd); | |
1150 | spin_unlock(pmd_ptl); | |
ac46d4f3 | 1151 | mmu_notifier_invalidate_range_end(&range); |
b46e756f KS |
1152 | |
1153 | spin_lock(pte_ptl); | |
5503fbf2 KS |
1154 | isolated = __collapse_huge_page_isolate(vma, address, pte, |
1155 | &compound_pagelist); | |
b46e756f KS |
1156 | spin_unlock(pte_ptl); |
1157 | ||
1158 | if (unlikely(!isolated)) { | |
1159 | pte_unmap(pte); | |
1160 | spin_lock(pmd_ptl); | |
1161 | BUG_ON(!pmd_none(*pmd)); | |
1162 | /* | |
1163 | * We can only use set_pmd_at when establishing | |
1164 | * hugepmds and never for establishing regular pmds that | |
1165 | * points to regular pagetables. Use pmd_populate for that | |
1166 | */ | |
1167 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
1168 | spin_unlock(pmd_ptl); | |
1169 | anon_vma_unlock_write(vma->anon_vma); | |
1170 | result = SCAN_FAIL; | |
18d24a7c | 1171 | goto out_up_write; |
b46e756f KS |
1172 | } |
1173 | ||
1174 | /* | |
1175 | * All pages are isolated and locked so anon_vma rmap | |
1176 | * can't run anymore. | |
1177 | */ | |
1178 | anon_vma_unlock_write(vma->anon_vma); | |
1179 | ||
5503fbf2 KS |
1180 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl, |
1181 | &compound_pagelist); | |
b46e756f | 1182 | pte_unmap(pte); |
588d01f9 ML |
1183 | /* |
1184 | * spin_lock() below is not the equivalent of smp_wmb(), but | |
1185 | * the smp_wmb() inside __SetPageUptodate() can be reused to | |
1186 | * avoid the copy_huge_page writes to become visible after | |
1187 | * the set_pmd_at() write. | |
1188 | */ | |
b46e756f KS |
1189 | __SetPageUptodate(new_page); |
1190 | pgtable = pmd_pgtable(_pmd); | |
1191 | ||
1192 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); | |
f55e1014 | 1193 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); |
b46e756f | 1194 | |
b46e756f KS |
1195 | spin_lock(pmd_ptl); |
1196 | BUG_ON(!pmd_none(*pmd)); | |
be5d0a74 | 1197 | page_add_new_anon_rmap(new_page, vma, address, true); |
b518154e | 1198 | lru_cache_add_inactive_or_unevictable(new_page, vma); |
b46e756f KS |
1199 | pgtable_trans_huge_deposit(mm, pmd, pgtable); |
1200 | set_pmd_at(mm, address, pmd, _pmd); | |
1201 | update_mmu_cache_pmd(vma, address, pmd); | |
1202 | spin_unlock(pmd_ptl); | |
1203 | ||
1204 | *hpage = NULL; | |
1205 | ||
1206 | khugepaged_pages_collapsed++; | |
1207 | result = SCAN_SUCCEED; | |
1208 | out_up_write: | |
d8ed45c5 | 1209 | mmap_write_unlock(mm); |
b46e756f | 1210 | out_nolock: |
9d82c694 | 1211 | if (!IS_ERR_OR_NULL(*hpage)) |
bbc6b703 | 1212 | mem_cgroup_uncharge(page_folio(*hpage)); |
b46e756f KS |
1213 | trace_mm_collapse_huge_page(mm, isolated, result); |
1214 | return; | |
b46e756f KS |
1215 | } |
1216 | ||
1217 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
1218 | struct vm_area_struct *vma, | |
1219 | unsigned long address, | |
1220 | struct page **hpage) | |
1221 | { | |
1222 | pmd_t *pmd; | |
1223 | pte_t *pte, *_pte; | |
71a2c112 KS |
1224 | int ret = 0, result = 0, referenced = 0; |
1225 | int none_or_zero = 0, shared = 0; | |
b46e756f KS |
1226 | struct page *page = NULL; |
1227 | unsigned long _address; | |
1228 | spinlock_t *ptl; | |
1229 | int node = NUMA_NO_NODE, unmapped = 0; | |
0db501f7 | 1230 | bool writable = false; |
b46e756f KS |
1231 | |
1232 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
1233 | ||
1234 | pmd = mm_find_pmd(mm, address); | |
1235 | if (!pmd) { | |
1236 | result = SCAN_PMD_NULL; | |
1237 | goto out; | |
1238 | } | |
1239 | ||
1240 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
1241 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1242 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1243 | _pte++, _address += PAGE_SIZE) { | |
1244 | pte_t pteval = *_pte; | |
1245 | if (is_swap_pte(pteval)) { | |
1246 | if (++unmapped <= khugepaged_max_ptes_swap) { | |
e1e267c7 PX |
1247 | /* |
1248 | * Always be strict with uffd-wp | |
1249 | * enabled swap entries. Please see | |
1250 | * comment below for pte_uffd_wp(). | |
1251 | */ | |
1252 | if (pte_swp_uffd_wp(pteval)) { | |
1253 | result = SCAN_PTE_UFFD_WP; | |
1254 | goto out_unmap; | |
1255 | } | |
b46e756f KS |
1256 | continue; |
1257 | } else { | |
1258 | result = SCAN_EXCEED_SWAP_PTE; | |
e9ea874a | 1259 | count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); |
b46e756f KS |
1260 | goto out_unmap; |
1261 | } | |
1262 | } | |
1263 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
1264 | if (!userfaultfd_armed(vma) && | |
1265 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
1266 | continue; | |
1267 | } else { | |
1268 | result = SCAN_EXCEED_NONE_PTE; | |
e9ea874a | 1269 | count_vm_event(THP_SCAN_EXCEED_NONE_PTE); |
b46e756f KS |
1270 | goto out_unmap; |
1271 | } | |
1272 | } | |
e1e267c7 PX |
1273 | if (pte_uffd_wp(pteval)) { |
1274 | /* | |
1275 | * Don't collapse the page if any of the small | |
1276 | * PTEs are armed with uffd write protection. | |
1277 | * Here we can also mark the new huge pmd as | |
1278 | * write protected if any of the small ones is | |
8958b249 | 1279 | * marked but that could bring unknown |
e1e267c7 PX |
1280 | * userfault messages that falls outside of |
1281 | * the registered range. So, just be simple. | |
1282 | */ | |
1283 | result = SCAN_PTE_UFFD_WP; | |
1284 | goto out_unmap; | |
1285 | } | |
b46e756f KS |
1286 | if (pte_write(pteval)) |
1287 | writable = true; | |
1288 | ||
1289 | page = vm_normal_page(vma, _address, pteval); | |
1290 | if (unlikely(!page)) { | |
1291 | result = SCAN_PAGE_NULL; | |
1292 | goto out_unmap; | |
1293 | } | |
1294 | ||
71a2c112 KS |
1295 | if (page_mapcount(page) > 1 && |
1296 | ++shared > khugepaged_max_ptes_shared) { | |
1297 | result = SCAN_EXCEED_SHARED_PTE; | |
e9ea874a | 1298 | count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); |
71a2c112 KS |
1299 | goto out_unmap; |
1300 | } | |
1301 | ||
5503fbf2 | 1302 | page = compound_head(page); |
b46e756f KS |
1303 | |
1304 | /* | |
1305 | * Record which node the original page is from and save this | |
1306 | * information to khugepaged_node_load[]. | |
0b8f0d87 | 1307 | * Khugepaged will allocate hugepage from the node has the max |
b46e756f KS |
1308 | * hit record. |
1309 | */ | |
1310 | node = page_to_nid(page); | |
1311 | if (khugepaged_scan_abort(node)) { | |
1312 | result = SCAN_SCAN_ABORT; | |
1313 | goto out_unmap; | |
1314 | } | |
1315 | khugepaged_node_load[node]++; | |
1316 | if (!PageLRU(page)) { | |
1317 | result = SCAN_PAGE_LRU; | |
1318 | goto out_unmap; | |
1319 | } | |
1320 | if (PageLocked(page)) { | |
1321 | result = SCAN_PAGE_LOCK; | |
1322 | goto out_unmap; | |
1323 | } | |
1324 | if (!PageAnon(page)) { | |
1325 | result = SCAN_PAGE_ANON; | |
1326 | goto out_unmap; | |
1327 | } | |
1328 | ||
1329 | /* | |
9445689f KS |
1330 | * Check if the page has any GUP (or other external) pins. |
1331 | * | |
1332 | * Here the check is racy it may see totmal_mapcount > refcount | |
1333 | * in some cases. | |
1334 | * For example, one process with one forked child process. | |
1335 | * The parent has the PMD split due to MADV_DONTNEED, then | |
1336 | * the child is trying unmap the whole PMD, but khugepaged | |
1337 | * may be scanning the parent between the child has | |
1338 | * PageDoubleMap flag cleared and dec the mapcount. So | |
1339 | * khugepaged may see total_mapcount > refcount. | |
1340 | * | |
1341 | * But such case is ephemeral we could always retry collapse | |
1342 | * later. However it may report false positive if the page | |
1343 | * has excessive GUP pins (i.e. 512). Anyway the same check | |
1344 | * will be done again later the risk seems low. | |
b46e756f | 1345 | */ |
9445689f | 1346 | if (!is_refcount_suitable(page)) { |
b46e756f KS |
1347 | result = SCAN_PAGE_COUNT; |
1348 | goto out_unmap; | |
1349 | } | |
1350 | if (pte_young(pteval) || | |
1351 | page_is_young(page) || PageReferenced(page) || | |
1352 | mmu_notifier_test_young(vma->vm_mm, address)) | |
0db501f7 | 1353 | referenced++; |
b46e756f | 1354 | } |
ffe945e6 | 1355 | if (!writable) { |
b46e756f | 1356 | result = SCAN_PAGE_RO; |
ffe945e6 KS |
1357 | } else if (!referenced || (unmapped && referenced < HPAGE_PMD_NR/2)) { |
1358 | result = SCAN_LACK_REFERENCED_PAGE; | |
1359 | } else { | |
1360 | result = SCAN_SUCCEED; | |
1361 | ret = 1; | |
b46e756f KS |
1362 | } |
1363 | out_unmap: | |
1364 | pte_unmap_unlock(pte, ptl); | |
1365 | if (ret) { | |
1366 | node = khugepaged_find_target_node(); | |
c1e8d7c6 | 1367 | /* collapse_huge_page will return with the mmap_lock released */ |
ffe945e6 KS |
1368 | collapse_huge_page(mm, address, hpage, node, |
1369 | referenced, unmapped); | |
b46e756f KS |
1370 | } |
1371 | out: | |
1372 | trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, | |
1373 | none_or_zero, result, unmapped); | |
1374 | return ret; | |
1375 | } | |
1376 | ||
1377 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
1378 | { | |
1379 | struct mm_struct *mm = mm_slot->mm; | |
1380 | ||
35f3aa39 | 1381 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
1382 | |
1383 | if (khugepaged_test_exit(mm)) { | |
1384 | /* free mm_slot */ | |
1385 | hash_del(&mm_slot->hash); | |
1386 | list_del(&mm_slot->mm_node); | |
1387 | ||
1388 | /* | |
1389 | * Not strictly needed because the mm exited already. | |
1390 | * | |
1391 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1392 | */ | |
1393 | ||
1394 | /* khugepaged_mm_lock actually not necessary for the below */ | |
1395 | free_mm_slot(mm_slot); | |
1396 | mmdrop(mm); | |
1397 | } | |
1398 | } | |
1399 | ||
396bcc52 | 1400 | #ifdef CONFIG_SHMEM |
27e1f827 SL |
1401 | /* |
1402 | * Notify khugepaged that given addr of the mm is pte-mapped THP. Then | |
1403 | * khugepaged should try to collapse the page table. | |
1404 | */ | |
1405 | static int khugepaged_add_pte_mapped_thp(struct mm_struct *mm, | |
1406 | unsigned long addr) | |
1407 | { | |
1408 | struct mm_slot *mm_slot; | |
1409 | ||
1410 | VM_BUG_ON(addr & ~HPAGE_PMD_MASK); | |
1411 | ||
1412 | spin_lock(&khugepaged_mm_lock); | |
1413 | mm_slot = get_mm_slot(mm); | |
1414 | if (likely(mm_slot && mm_slot->nr_pte_mapped_thp < MAX_PTE_MAPPED_THP)) | |
1415 | mm_slot->pte_mapped_thp[mm_slot->nr_pte_mapped_thp++] = addr; | |
1416 | spin_unlock(&khugepaged_mm_lock); | |
1417 | return 0; | |
1418 | } | |
1419 | ||
e59a47b8 PT |
1420 | static void collapse_and_free_pmd(struct mm_struct *mm, struct vm_area_struct *vma, |
1421 | unsigned long addr, pmd_t *pmdp) | |
1422 | { | |
1423 | spinlock_t *ptl; | |
1424 | pmd_t pmd; | |
1425 | ||
80110bbf | 1426 | mmap_assert_write_locked(mm); |
e59a47b8 PT |
1427 | ptl = pmd_lock(vma->vm_mm, pmdp); |
1428 | pmd = pmdp_collapse_flush(vma, addr, pmdp); | |
1429 | spin_unlock(ptl); | |
1430 | mm_dec_nr_ptes(mm); | |
80110bbf | 1431 | page_table_check_pte_clear_range(mm, addr, pmd); |
e59a47b8 PT |
1432 | pte_free(mm, pmd_pgtable(pmd)); |
1433 | } | |
1434 | ||
27e1f827 | 1435 | /** |
336e6b53 AS |
1436 | * collapse_pte_mapped_thp - Try to collapse a pte-mapped THP for mm at |
1437 | * address haddr. | |
1438 | * | |
1439 | * @mm: process address space where collapse happens | |
1440 | * @addr: THP collapse address | |
27e1f827 SL |
1441 | * |
1442 | * This function checks whether all the PTEs in the PMD are pointing to the | |
1443 | * right THP. If so, retract the page table so the THP can refault in with | |
1444 | * as pmd-mapped. | |
1445 | */ | |
1446 | void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) | |
1447 | { | |
1448 | unsigned long haddr = addr & HPAGE_PMD_MASK; | |
1449 | struct vm_area_struct *vma = find_vma(mm, haddr); | |
119a5fc1 | 1450 | struct page *hpage; |
27e1f827 | 1451 | pte_t *start_pte, *pte; |
e59a47b8 | 1452 | pmd_t *pmd; |
27e1f827 SL |
1453 | spinlock_t *ptl; |
1454 | int count = 0; | |
1455 | int i; | |
1456 | ||
1457 | if (!vma || !vma->vm_file || | |
fef792a4 | 1458 | !range_in_vma(vma, haddr, haddr + HPAGE_PMD_SIZE)) |
27e1f827 SL |
1459 | return; |
1460 | ||
1461 | /* | |
1462 | * This vm_flags may not have VM_HUGEPAGE if the page was not | |
1463 | * collapsed by this mm. But we can still collapse if the page is | |
1464 | * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check() | |
1465 | * will not fail the vma for missing VM_HUGEPAGE | |
1466 | */ | |
1467 | if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE)) | |
1468 | return; | |
1469 | ||
119a5fc1 HD |
1470 | hpage = find_lock_page(vma->vm_file->f_mapping, |
1471 | linear_page_index(vma, haddr)); | |
1472 | if (!hpage) | |
1473 | return; | |
1474 | ||
1475 | if (!PageHead(hpage)) | |
1476 | goto drop_hpage; | |
1477 | ||
27e1f827 SL |
1478 | pmd = mm_find_pmd(mm, haddr); |
1479 | if (!pmd) | |
119a5fc1 | 1480 | goto drop_hpage; |
27e1f827 SL |
1481 | |
1482 | start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl); | |
1483 | ||
1484 | /* step 1: check all mapped PTEs are to the right huge page */ | |
1485 | for (i = 0, addr = haddr, pte = start_pte; | |
1486 | i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) { | |
1487 | struct page *page; | |
1488 | ||
1489 | /* empty pte, skip */ | |
1490 | if (pte_none(*pte)) | |
1491 | continue; | |
1492 | ||
1493 | /* page swapped out, abort */ | |
1494 | if (!pte_present(*pte)) | |
1495 | goto abort; | |
1496 | ||
1497 | page = vm_normal_page(vma, addr, *pte); | |
1498 | ||
27e1f827 | 1499 | /* |
119a5fc1 HD |
1500 | * Note that uprobe, debugger, or MAP_PRIVATE may change the |
1501 | * page table, but the new page will not be a subpage of hpage. | |
27e1f827 | 1502 | */ |
119a5fc1 | 1503 | if (hpage + i != page) |
27e1f827 SL |
1504 | goto abort; |
1505 | count++; | |
1506 | } | |
1507 | ||
1508 | /* step 2: adjust rmap */ | |
1509 | for (i = 0, addr = haddr, pte = start_pte; | |
1510 | i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) { | |
1511 | struct page *page; | |
1512 | ||
1513 | if (pte_none(*pte)) | |
1514 | continue; | |
1515 | page = vm_normal_page(vma, addr, *pte); | |
1516 | page_remove_rmap(page, false); | |
1517 | } | |
1518 | ||
1519 | pte_unmap_unlock(start_pte, ptl); | |
1520 | ||
1521 | /* step 3: set proper refcount and mm_counters. */ | |
119a5fc1 | 1522 | if (count) { |
27e1f827 SL |
1523 | page_ref_sub(hpage, count); |
1524 | add_mm_counter(vma->vm_mm, mm_counter_file(hpage), -count); | |
1525 | } | |
1526 | ||
1527 | /* step 4: collapse pmd */ | |
e59a47b8 | 1528 | collapse_and_free_pmd(mm, vma, haddr, pmd); |
119a5fc1 HD |
1529 | drop_hpage: |
1530 | unlock_page(hpage); | |
1531 | put_page(hpage); | |
27e1f827 SL |
1532 | return; |
1533 | ||
1534 | abort: | |
1535 | pte_unmap_unlock(start_pte, ptl); | |
119a5fc1 | 1536 | goto drop_hpage; |
27e1f827 SL |
1537 | } |
1538 | ||
0edf61e5 | 1539 | static void khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) |
27e1f827 SL |
1540 | { |
1541 | struct mm_struct *mm = mm_slot->mm; | |
1542 | int i; | |
1543 | ||
1544 | if (likely(mm_slot->nr_pte_mapped_thp == 0)) | |
0edf61e5 | 1545 | return; |
27e1f827 | 1546 | |
d8ed45c5 | 1547 | if (!mmap_write_trylock(mm)) |
0edf61e5 | 1548 | return; |
27e1f827 SL |
1549 | |
1550 | if (unlikely(khugepaged_test_exit(mm))) | |
1551 | goto out; | |
1552 | ||
1553 | for (i = 0; i < mm_slot->nr_pte_mapped_thp; i++) | |
1554 | collapse_pte_mapped_thp(mm, mm_slot->pte_mapped_thp[i]); | |
1555 | ||
1556 | out: | |
1557 | mm_slot->nr_pte_mapped_thp = 0; | |
d8ed45c5 | 1558 | mmap_write_unlock(mm); |
27e1f827 SL |
1559 | } |
1560 | ||
f3f0e1d2 KS |
1561 | static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) |
1562 | { | |
1563 | struct vm_area_struct *vma; | |
18e77600 | 1564 | struct mm_struct *mm; |
f3f0e1d2 | 1565 | unsigned long addr; |
e59a47b8 | 1566 | pmd_t *pmd; |
f3f0e1d2 KS |
1567 | |
1568 | i_mmap_lock_write(mapping); | |
1569 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { | |
27e1f827 SL |
1570 | /* |
1571 | * Check vma->anon_vma to exclude MAP_PRIVATE mappings that | |
1572 | * got written to. These VMAs are likely not worth investing | |
3e4e28c5 | 1573 | * mmap_write_lock(mm) as PMD-mapping is likely to be split |
27e1f827 SL |
1574 | * later. |
1575 | * | |
1576 | * Not that vma->anon_vma check is racy: it can be set up after | |
c1e8d7c6 | 1577 | * the check but before we took mmap_lock by the fault path. |
27e1f827 SL |
1578 | * But page lock would prevent establishing any new ptes of the |
1579 | * page, so we are safe. | |
1580 | * | |
1581 | * An alternative would be drop the check, but check that page | |
1582 | * table is clear before calling pmdp_collapse_flush() under | |
1583 | * ptl. It has higher chance to recover THP for the VMA, but | |
1584 | * has higher cost too. | |
1585 | */ | |
f3f0e1d2 KS |
1586 | if (vma->anon_vma) |
1587 | continue; | |
1588 | addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
1589 | if (addr & ~HPAGE_PMD_MASK) | |
1590 | continue; | |
1591 | if (vma->vm_end < addr + HPAGE_PMD_SIZE) | |
1592 | continue; | |
18e77600 HD |
1593 | mm = vma->vm_mm; |
1594 | pmd = mm_find_pmd(mm, addr); | |
f3f0e1d2 KS |
1595 | if (!pmd) |
1596 | continue; | |
1597 | /* | |
c1e8d7c6 | 1598 | * We need exclusive mmap_lock to retract page table. |
27e1f827 SL |
1599 | * |
1600 | * We use trylock due to lock inversion: we need to acquire | |
c1e8d7c6 | 1601 | * mmap_lock while holding page lock. Fault path does it in |
27e1f827 | 1602 | * reverse order. Trylock is a way to avoid deadlock. |
f3f0e1d2 | 1603 | */ |
18e77600 | 1604 | if (mmap_write_trylock(mm)) { |
e59a47b8 PT |
1605 | if (!khugepaged_test_exit(mm)) |
1606 | collapse_and_free_pmd(mm, vma, addr, pmd); | |
18e77600 | 1607 | mmap_write_unlock(mm); |
27e1f827 SL |
1608 | } else { |
1609 | /* Try again later */ | |
18e77600 | 1610 | khugepaged_add_pte_mapped_thp(mm, addr); |
f3f0e1d2 KS |
1611 | } |
1612 | } | |
1613 | i_mmap_unlock_write(mapping); | |
1614 | } | |
1615 | ||
1616 | /** | |
99cb0dbd | 1617 | * collapse_file - collapse filemap/tmpfs/shmem pages into huge one. |
f3f0e1d2 | 1618 | * |
336e6b53 AS |
1619 | * @mm: process address space where collapse happens |
1620 | * @file: file that collapse on | |
1621 | * @start: collapse start address | |
1622 | * @hpage: new allocated huge page for collapse | |
1623 | * @node: appointed node the new huge page allocate from | |
1624 | * | |
f3f0e1d2 | 1625 | * Basic scheme is simple, details are more complex: |
87c460a0 | 1626 | * - allocate and lock a new huge page; |
77da9389 | 1627 | * - scan page cache replacing old pages with the new one |
99cb0dbd | 1628 | * + swap/gup in pages if necessary; |
f3f0e1d2 | 1629 | * + fill in gaps; |
77da9389 MW |
1630 | * + keep old pages around in case rollback is required; |
1631 | * - if replacing succeeds: | |
f3f0e1d2 KS |
1632 | * + copy data over; |
1633 | * + free old pages; | |
87c460a0 | 1634 | * + unlock huge page; |
f3f0e1d2 KS |
1635 | * - if replacing failed; |
1636 | * + put all pages back and unfreeze them; | |
77da9389 | 1637 | * + restore gaps in the page cache; |
87c460a0 | 1638 | * + unlock and free huge page; |
f3f0e1d2 | 1639 | */ |
579c571e SL |
1640 | static void collapse_file(struct mm_struct *mm, |
1641 | struct file *file, pgoff_t start, | |
f3f0e1d2 KS |
1642 | struct page **hpage, int node) |
1643 | { | |
579c571e | 1644 | struct address_space *mapping = file->f_mapping; |
f3f0e1d2 | 1645 | gfp_t gfp; |
77da9389 | 1646 | struct page *new_page; |
f3f0e1d2 KS |
1647 | pgoff_t index, end = start + HPAGE_PMD_NR; |
1648 | LIST_HEAD(pagelist); | |
77da9389 | 1649 | XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); |
f3f0e1d2 | 1650 | int nr_none = 0, result = SCAN_SUCCEED; |
99cb0dbd | 1651 | bool is_shmem = shmem_file(file); |
bf9ecead | 1652 | int nr; |
f3f0e1d2 | 1653 | |
99cb0dbd | 1654 | VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); |
f3f0e1d2 KS |
1655 | VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); |
1656 | ||
1657 | /* Only allocate from the target node */ | |
41b6167e | 1658 | gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE; |
f3f0e1d2 KS |
1659 | |
1660 | new_page = khugepaged_alloc_page(hpage, gfp, node); | |
1661 | if (!new_page) { | |
1662 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
1663 | goto out; | |
1664 | } | |
1665 | ||
8f425e4e | 1666 | if (unlikely(mem_cgroup_charge(page_folio(new_page), mm, gfp))) { |
f3f0e1d2 KS |
1667 | result = SCAN_CGROUP_CHARGE_FAIL; |
1668 | goto out; | |
1669 | } | |
9d82c694 | 1670 | count_memcg_page_event(new_page, THP_COLLAPSE_ALLOC); |
f3f0e1d2 | 1671 | |
6b24ca4a MWO |
1672 | /* |
1673 | * Ensure we have slots for all the pages in the range. This is | |
1674 | * almost certainly a no-op because most of the pages must be present | |
1675 | */ | |
95feeabb HD |
1676 | do { |
1677 | xas_lock_irq(&xas); | |
1678 | xas_create_range(&xas); | |
1679 | if (!xas_error(&xas)) | |
1680 | break; | |
1681 | xas_unlock_irq(&xas); | |
1682 | if (!xas_nomem(&xas, GFP_KERNEL)) { | |
95feeabb HD |
1683 | result = SCAN_FAIL; |
1684 | goto out; | |
1685 | } | |
1686 | } while (1); | |
1687 | ||
042a3082 | 1688 | __SetPageLocked(new_page); |
99cb0dbd SL |
1689 | if (is_shmem) |
1690 | __SetPageSwapBacked(new_page); | |
f3f0e1d2 KS |
1691 | new_page->index = start; |
1692 | new_page->mapping = mapping; | |
f3f0e1d2 | 1693 | |
f3f0e1d2 | 1694 | /* |
87c460a0 HD |
1695 | * At this point the new_page is locked and not up-to-date. |
1696 | * It's safe to insert it into the page cache, because nobody would | |
1697 | * be able to map it or use it in another way until we unlock it. | |
f3f0e1d2 KS |
1698 | */ |
1699 | ||
77da9389 MW |
1700 | xas_set(&xas, start); |
1701 | for (index = start; index < end; index++) { | |
1702 | struct page *page = xas_next(&xas); | |
1703 | ||
1704 | VM_BUG_ON(index != xas.xa_index); | |
99cb0dbd SL |
1705 | if (is_shmem) { |
1706 | if (!page) { | |
1707 | /* | |
1708 | * Stop if extent has been truncated or | |
1709 | * hole-punched, and is now completely | |
1710 | * empty. | |
1711 | */ | |
1712 | if (index == start) { | |
1713 | if (!xas_next_entry(&xas, end - 1)) { | |
1714 | result = SCAN_TRUNCATED; | |
1715 | goto xa_locked; | |
1716 | } | |
1717 | xas_set(&xas, index); | |
1718 | } | |
1719 | if (!shmem_charge(mapping->host, 1)) { | |
1720 | result = SCAN_FAIL; | |
042a3082 | 1721 | goto xa_locked; |
701270fa | 1722 | } |
99cb0dbd SL |
1723 | xas_store(&xas, new_page); |
1724 | nr_none++; | |
1725 | continue; | |
701270fa | 1726 | } |
99cb0dbd SL |
1727 | |
1728 | if (xa_is_value(page) || !PageUptodate(page)) { | |
1729 | xas_unlock_irq(&xas); | |
1730 | /* swap in or instantiate fallocated page */ | |
1731 | if (shmem_getpage(mapping->host, index, &page, | |
acdd9f8e | 1732 | SGP_NOALLOC)) { |
99cb0dbd SL |
1733 | result = SCAN_FAIL; |
1734 | goto xa_unlocked; | |
1735 | } | |
1736 | } else if (trylock_page(page)) { | |
1737 | get_page(page); | |
1738 | xas_unlock_irq(&xas); | |
1739 | } else { | |
1740 | result = SCAN_PAGE_LOCK; | |
042a3082 | 1741 | goto xa_locked; |
77da9389 | 1742 | } |
99cb0dbd SL |
1743 | } else { /* !is_shmem */ |
1744 | if (!page || xa_is_value(page)) { | |
1745 | xas_unlock_irq(&xas); | |
1746 | page_cache_sync_readahead(mapping, &file->f_ra, | |
1747 | file, index, | |
e5a59d30 | 1748 | end - index); |
99cb0dbd SL |
1749 | /* drain pagevecs to help isolate_lru_page() */ |
1750 | lru_add_drain(); | |
1751 | page = find_lock_page(mapping, index); | |
1752 | if (unlikely(page == NULL)) { | |
1753 | result = SCAN_FAIL; | |
1754 | goto xa_unlocked; | |
1755 | } | |
75f36069 SL |
1756 | } else if (PageDirty(page)) { |
1757 | /* | |
1758 | * khugepaged only works on read-only fd, | |
1759 | * so this page is dirty because it hasn't | |
1760 | * been flushed since first write. There | |
1761 | * won't be new dirty pages. | |
1762 | * | |
1763 | * Trigger async flush here and hope the | |
1764 | * writeback is done when khugepaged | |
1765 | * revisits this page. | |
1766 | * | |
1767 | * This is a one-off situation. We are not | |
1768 | * forcing writeback in loop. | |
1769 | */ | |
1770 | xas_unlock_irq(&xas); | |
1771 | filemap_flush(mapping); | |
1772 | result = SCAN_FAIL; | |
1773 | goto xa_unlocked; | |
74c42e1b RW |
1774 | } else if (PageWriteback(page)) { |
1775 | xas_unlock_irq(&xas); | |
1776 | result = SCAN_FAIL; | |
1777 | goto xa_unlocked; | |
99cb0dbd SL |
1778 | } else if (trylock_page(page)) { |
1779 | get_page(page); | |
1780 | xas_unlock_irq(&xas); | |
1781 | } else { | |
1782 | result = SCAN_PAGE_LOCK; | |
1783 | goto xa_locked; | |
f3f0e1d2 | 1784 | } |
f3f0e1d2 KS |
1785 | } |
1786 | ||
1787 | /* | |
b93b0163 | 1788 | * The page must be locked, so we can drop the i_pages lock |
f3f0e1d2 KS |
1789 | * without racing with truncate. |
1790 | */ | |
1791 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
4655e5e5 SL |
1792 | |
1793 | /* make sure the page is up to date */ | |
1794 | if (unlikely(!PageUptodate(page))) { | |
1795 | result = SCAN_FAIL; | |
1796 | goto out_unlock; | |
1797 | } | |
06a5e126 HD |
1798 | |
1799 | /* | |
1800 | * If file was truncated then extended, or hole-punched, before | |
1801 | * we locked the first page, then a THP might be there already. | |
1802 | */ | |
1803 | if (PageTransCompound(page)) { | |
1804 | result = SCAN_PAGE_COMPOUND; | |
1805 | goto out_unlock; | |
1806 | } | |
f3f0e1d2 KS |
1807 | |
1808 | if (page_mapping(page) != mapping) { | |
1809 | result = SCAN_TRUNCATED; | |
1810 | goto out_unlock; | |
1811 | } | |
f3f0e1d2 | 1812 | |
74c42e1b RW |
1813 | if (!is_shmem && (PageDirty(page) || |
1814 | PageWriteback(page))) { | |
4655e5e5 SL |
1815 | /* |
1816 | * khugepaged only works on read-only fd, so this | |
1817 | * page is dirty because it hasn't been flushed | |
1818 | * since first write. | |
1819 | */ | |
1820 | result = SCAN_FAIL; | |
1821 | goto out_unlock; | |
1822 | } | |
1823 | ||
f3f0e1d2 KS |
1824 | if (isolate_lru_page(page)) { |
1825 | result = SCAN_DEL_PAGE_LRU; | |
042a3082 | 1826 | goto out_unlock; |
f3f0e1d2 KS |
1827 | } |
1828 | ||
99cb0dbd SL |
1829 | if (page_has_private(page) && |
1830 | !try_to_release_page(page, GFP_KERNEL)) { | |
1831 | result = SCAN_PAGE_HAS_PRIVATE; | |
2f33a706 | 1832 | putback_lru_page(page); |
99cb0dbd SL |
1833 | goto out_unlock; |
1834 | } | |
1835 | ||
f3f0e1d2 | 1836 | if (page_mapped(page)) |
977fbdcd | 1837 | unmap_mapping_pages(mapping, index, 1, false); |
f3f0e1d2 | 1838 | |
77da9389 MW |
1839 | xas_lock_irq(&xas); |
1840 | xas_set(&xas, index); | |
f3f0e1d2 | 1841 | |
77da9389 | 1842 | VM_BUG_ON_PAGE(page != xas_load(&xas), page); |
f3f0e1d2 KS |
1843 | VM_BUG_ON_PAGE(page_mapped(page), page); |
1844 | ||
1845 | /* | |
1846 | * The page is expected to have page_count() == 3: | |
1847 | * - we hold a pin on it; | |
77da9389 | 1848 | * - one reference from page cache; |
f3f0e1d2 KS |
1849 | * - one from isolate_lru_page; |
1850 | */ | |
1851 | if (!page_ref_freeze(page, 3)) { | |
1852 | result = SCAN_PAGE_COUNT; | |
042a3082 HD |
1853 | xas_unlock_irq(&xas); |
1854 | putback_lru_page(page); | |
1855 | goto out_unlock; | |
f3f0e1d2 KS |
1856 | } |
1857 | ||
1858 | /* | |
1859 | * Add the page to the list to be able to undo the collapse if | |
1860 | * something go wrong. | |
1861 | */ | |
1862 | list_add_tail(&page->lru, &pagelist); | |
1863 | ||
1864 | /* Finally, replace with the new page. */ | |
4101196b | 1865 | xas_store(&xas, new_page); |
f3f0e1d2 | 1866 | continue; |
f3f0e1d2 KS |
1867 | out_unlock: |
1868 | unlock_page(page); | |
1869 | put_page(page); | |
042a3082 | 1870 | goto xa_unlocked; |
f3f0e1d2 | 1871 | } |
bf9ecead | 1872 | nr = thp_nr_pages(new_page); |
f3f0e1d2 | 1873 | |
99cb0dbd | 1874 | if (is_shmem) |
57b2847d | 1875 | __mod_lruvec_page_state(new_page, NR_SHMEM_THPS, nr); |
09d91cda | 1876 | else { |
bf9ecead | 1877 | __mod_lruvec_page_state(new_page, NR_FILE_THPS, nr); |
09d91cda | 1878 | filemap_nr_thps_inc(mapping); |
eb6ecbed CF |
1879 | /* |
1880 | * Paired with smp_mb() in do_dentry_open() to ensure | |
1881 | * i_writecount is up to date and the update to nr_thps is | |
1882 | * visible. Ensures the page cache will be truncated if the | |
1883 | * file is opened writable. | |
1884 | */ | |
1885 | smp_mb(); | |
1886 | if (inode_is_open_for_write(mapping->host)) { | |
1887 | result = SCAN_FAIL; | |
1888 | __mod_lruvec_page_state(new_page, NR_FILE_THPS, -nr); | |
1889 | filemap_nr_thps_dec(mapping); | |
1890 | goto xa_locked; | |
1891 | } | |
09d91cda | 1892 | } |
99cb0dbd | 1893 | |
042a3082 | 1894 | if (nr_none) { |
9d82c694 | 1895 | __mod_lruvec_page_state(new_page, NR_FILE_PAGES, nr_none); |
99cb0dbd | 1896 | if (is_shmem) |
9d82c694 | 1897 | __mod_lruvec_page_state(new_page, NR_SHMEM, nr_none); |
042a3082 HD |
1898 | } |
1899 | ||
6b24ca4a MWO |
1900 | /* Join all the small entries into a single multi-index entry */ |
1901 | xas_set_order(&xas, start, HPAGE_PMD_ORDER); | |
1902 | xas_store(&xas, new_page); | |
042a3082 HD |
1903 | xa_locked: |
1904 | xas_unlock_irq(&xas); | |
77da9389 | 1905 | xa_unlocked: |
042a3082 | 1906 | |
f3f0e1d2 | 1907 | if (result == SCAN_SUCCEED) { |
77da9389 | 1908 | struct page *page, *tmp; |
f3f0e1d2 KS |
1909 | |
1910 | /* | |
77da9389 MW |
1911 | * Replacing old pages with new one has succeeded, now we |
1912 | * need to copy the content and free the old pages. | |
f3f0e1d2 | 1913 | */ |
2af8ff29 | 1914 | index = start; |
f3f0e1d2 | 1915 | list_for_each_entry_safe(page, tmp, &pagelist, lru) { |
2af8ff29 HD |
1916 | while (index < page->index) { |
1917 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1918 | index++; | |
1919 | } | |
f3f0e1d2 KS |
1920 | copy_highpage(new_page + (page->index % HPAGE_PMD_NR), |
1921 | page); | |
1922 | list_del(&page->lru); | |
f3f0e1d2 | 1923 | page->mapping = NULL; |
042a3082 | 1924 | page_ref_unfreeze(page, 1); |
f3f0e1d2 KS |
1925 | ClearPageActive(page); |
1926 | ClearPageUnevictable(page); | |
042a3082 | 1927 | unlock_page(page); |
f3f0e1d2 | 1928 | put_page(page); |
2af8ff29 HD |
1929 | index++; |
1930 | } | |
1931 | while (index < end) { | |
1932 | clear_highpage(new_page + (index % HPAGE_PMD_NR)); | |
1933 | index++; | |
f3f0e1d2 KS |
1934 | } |
1935 | ||
f3f0e1d2 | 1936 | SetPageUptodate(new_page); |
87c460a0 | 1937 | page_ref_add(new_page, HPAGE_PMD_NR - 1); |
6058eaec | 1938 | if (is_shmem) |
99cb0dbd | 1939 | set_page_dirty(new_page); |
6058eaec | 1940 | lru_cache_add(new_page); |
f3f0e1d2 | 1941 | |
042a3082 HD |
1942 | /* |
1943 | * Remove pte page tables, so we can re-fault the page as huge. | |
1944 | */ | |
1945 | retract_page_tables(mapping, start); | |
f3f0e1d2 | 1946 | *hpage = NULL; |
87aa7529 YS |
1947 | |
1948 | khugepaged_pages_collapsed++; | |
f3f0e1d2 | 1949 | } else { |
77da9389 | 1950 | struct page *page; |
aaa52e34 | 1951 | |
77da9389 | 1952 | /* Something went wrong: roll back page cache changes */ |
77da9389 | 1953 | xas_lock_irq(&xas); |
aaa52e34 | 1954 | mapping->nrpages -= nr_none; |
99cb0dbd SL |
1955 | |
1956 | if (is_shmem) | |
1957 | shmem_uncharge(mapping->host, nr_none); | |
aaa52e34 | 1958 | |
77da9389 MW |
1959 | xas_set(&xas, start); |
1960 | xas_for_each(&xas, page, end - 1) { | |
f3f0e1d2 KS |
1961 | page = list_first_entry_or_null(&pagelist, |
1962 | struct page, lru); | |
77da9389 | 1963 | if (!page || xas.xa_index < page->index) { |
f3f0e1d2 KS |
1964 | if (!nr_none) |
1965 | break; | |
f3f0e1d2 | 1966 | nr_none--; |
59749e6c | 1967 | /* Put holes back where they were */ |
77da9389 | 1968 | xas_store(&xas, NULL); |
f3f0e1d2 KS |
1969 | continue; |
1970 | } | |
1971 | ||
77da9389 | 1972 | VM_BUG_ON_PAGE(page->index != xas.xa_index, page); |
f3f0e1d2 KS |
1973 | |
1974 | /* Unfreeze the page. */ | |
1975 | list_del(&page->lru); | |
1976 | page_ref_unfreeze(page, 2); | |
77da9389 MW |
1977 | xas_store(&xas, page); |
1978 | xas_pause(&xas); | |
1979 | xas_unlock_irq(&xas); | |
f3f0e1d2 | 1980 | unlock_page(page); |
042a3082 | 1981 | putback_lru_page(page); |
77da9389 | 1982 | xas_lock_irq(&xas); |
f3f0e1d2 KS |
1983 | } |
1984 | VM_BUG_ON(nr_none); | |
77da9389 | 1985 | xas_unlock_irq(&xas); |
f3f0e1d2 | 1986 | |
f3f0e1d2 KS |
1987 | new_page->mapping = NULL; |
1988 | } | |
042a3082 HD |
1989 | |
1990 | unlock_page(new_page); | |
f3f0e1d2 KS |
1991 | out: |
1992 | VM_BUG_ON(!list_empty(&pagelist)); | |
9d82c694 | 1993 | if (!IS_ERR_OR_NULL(*hpage)) |
bbc6b703 | 1994 | mem_cgroup_uncharge(page_folio(*hpage)); |
f3f0e1d2 KS |
1995 | /* TODO: tracepoints */ |
1996 | } | |
1997 | ||
579c571e SL |
1998 | static void khugepaged_scan_file(struct mm_struct *mm, |
1999 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
2000 | { |
2001 | struct page *page = NULL; | |
579c571e | 2002 | struct address_space *mapping = file->f_mapping; |
85b392db | 2003 | XA_STATE(xas, &mapping->i_pages, start); |
f3f0e1d2 KS |
2004 | int present, swap; |
2005 | int node = NUMA_NO_NODE; | |
2006 | int result = SCAN_SUCCEED; | |
2007 | ||
2008 | present = 0; | |
2009 | swap = 0; | |
2010 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
2011 | rcu_read_lock(); | |
85b392db MW |
2012 | xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) { |
2013 | if (xas_retry(&xas, page)) | |
f3f0e1d2 | 2014 | continue; |
f3f0e1d2 | 2015 | |
85b392db | 2016 | if (xa_is_value(page)) { |
f3f0e1d2 KS |
2017 | if (++swap > khugepaged_max_ptes_swap) { |
2018 | result = SCAN_EXCEED_SWAP_PTE; | |
e9ea874a | 2019 | count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); |
f3f0e1d2 KS |
2020 | break; |
2021 | } | |
2022 | continue; | |
2023 | } | |
2024 | ||
6b24ca4a MWO |
2025 | /* |
2026 | * XXX: khugepaged should compact smaller compound pages | |
2027 | * into a PMD sized page | |
2028 | */ | |
f3f0e1d2 KS |
2029 | if (PageTransCompound(page)) { |
2030 | result = SCAN_PAGE_COMPOUND; | |
2031 | break; | |
2032 | } | |
2033 | ||
2034 | node = page_to_nid(page); | |
2035 | if (khugepaged_scan_abort(node)) { | |
2036 | result = SCAN_SCAN_ABORT; | |
2037 | break; | |
2038 | } | |
2039 | khugepaged_node_load[node]++; | |
2040 | ||
2041 | if (!PageLRU(page)) { | |
2042 | result = SCAN_PAGE_LRU; | |
2043 | break; | |
2044 | } | |
2045 | ||
99cb0dbd SL |
2046 | if (page_count(page) != |
2047 | 1 + page_mapcount(page) + page_has_private(page)) { | |
f3f0e1d2 KS |
2048 | result = SCAN_PAGE_COUNT; |
2049 | break; | |
2050 | } | |
2051 | ||
2052 | /* | |
2053 | * We probably should check if the page is referenced here, but | |
2054 | * nobody would transfer pte_young() to PageReferenced() for us. | |
2055 | * And rmap walk here is just too costly... | |
2056 | */ | |
2057 | ||
2058 | present++; | |
2059 | ||
2060 | if (need_resched()) { | |
85b392db | 2061 | xas_pause(&xas); |
f3f0e1d2 | 2062 | cond_resched_rcu(); |
f3f0e1d2 KS |
2063 | } |
2064 | } | |
2065 | rcu_read_unlock(); | |
2066 | ||
2067 | if (result == SCAN_SUCCEED) { | |
2068 | if (present < HPAGE_PMD_NR - khugepaged_max_ptes_none) { | |
2069 | result = SCAN_EXCEED_NONE_PTE; | |
e9ea874a | 2070 | count_vm_event(THP_SCAN_EXCEED_NONE_PTE); |
f3f0e1d2 KS |
2071 | } else { |
2072 | node = khugepaged_find_target_node(); | |
579c571e | 2073 | collapse_file(mm, file, start, hpage, node); |
f3f0e1d2 KS |
2074 | } |
2075 | } | |
2076 | ||
2077 | /* TODO: tracepoints */ | |
2078 | } | |
2079 | #else | |
579c571e SL |
2080 | static void khugepaged_scan_file(struct mm_struct *mm, |
2081 | struct file *file, pgoff_t start, struct page **hpage) | |
f3f0e1d2 KS |
2082 | { |
2083 | BUILD_BUG(); | |
2084 | } | |
27e1f827 | 2085 | |
0edf61e5 | 2086 | static void khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) |
27e1f827 | 2087 | { |
27e1f827 | 2088 | } |
f3f0e1d2 KS |
2089 | #endif |
2090 | ||
b46e756f KS |
2091 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, |
2092 | struct page **hpage) | |
2093 | __releases(&khugepaged_mm_lock) | |
2094 | __acquires(&khugepaged_mm_lock) | |
2095 | { | |
2096 | struct mm_slot *mm_slot; | |
2097 | struct mm_struct *mm; | |
2098 | struct vm_area_struct *vma; | |
2099 | int progress = 0; | |
2100 | ||
2101 | VM_BUG_ON(!pages); | |
35f3aa39 | 2102 | lockdep_assert_held(&khugepaged_mm_lock); |
b46e756f KS |
2103 | |
2104 | if (khugepaged_scan.mm_slot) | |
2105 | mm_slot = khugepaged_scan.mm_slot; | |
2106 | else { | |
2107 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2108 | struct mm_slot, mm_node); | |
2109 | khugepaged_scan.address = 0; | |
2110 | khugepaged_scan.mm_slot = mm_slot; | |
2111 | } | |
2112 | spin_unlock(&khugepaged_mm_lock); | |
27e1f827 | 2113 | khugepaged_collapse_pte_mapped_thps(mm_slot); |
b46e756f KS |
2114 | |
2115 | mm = mm_slot->mm; | |
3b454ad3 YS |
2116 | /* |
2117 | * Don't wait for semaphore (to avoid long wait times). Just move to | |
2118 | * the next mm on the list. | |
2119 | */ | |
2120 | vma = NULL; | |
d8ed45c5 | 2121 | if (unlikely(!mmap_read_trylock(mm))) |
c1e8d7c6 | 2122 | goto breakouterloop_mmap_lock; |
3b454ad3 | 2123 | if (likely(!khugepaged_test_exit(mm))) |
b46e756f KS |
2124 | vma = find_vma(mm, khugepaged_scan.address); |
2125 | ||
2126 | progress++; | |
2127 | for (; vma; vma = vma->vm_next) { | |
2128 | unsigned long hstart, hend; | |
2129 | ||
2130 | cond_resched(); | |
2131 | if (unlikely(khugepaged_test_exit(mm))) { | |
2132 | progress++; | |
2133 | break; | |
2134 | } | |
50f8b92f | 2135 | if (!hugepage_vma_check(vma, vma->vm_flags)) { |
b46e756f KS |
2136 | skip: |
2137 | progress++; | |
2138 | continue; | |
2139 | } | |
2140 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2141 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2142 | if (hstart >= hend) | |
2143 | goto skip; | |
2144 | if (khugepaged_scan.address > hend) | |
2145 | goto skip; | |
2146 | if (khugepaged_scan.address < hstart) | |
2147 | khugepaged_scan.address = hstart; | |
2148 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); | |
396bcc52 MWO |
2149 | if (shmem_file(vma->vm_file) && !shmem_huge_enabled(vma)) |
2150 | goto skip; | |
b46e756f KS |
2151 | |
2152 | while (khugepaged_scan.address < hend) { | |
2153 | int ret; | |
2154 | cond_resched(); | |
2155 | if (unlikely(khugepaged_test_exit(mm))) | |
2156 | goto breakouterloop; | |
2157 | ||
2158 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2159 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2160 | hend); | |
99cb0dbd | 2161 | if (IS_ENABLED(CONFIG_SHMEM) && vma->vm_file) { |
396bcc52 | 2162 | struct file *file = get_file(vma->vm_file); |
f3f0e1d2 KS |
2163 | pgoff_t pgoff = linear_page_index(vma, |
2164 | khugepaged_scan.address); | |
99cb0dbd | 2165 | |
d8ed45c5 | 2166 | mmap_read_unlock(mm); |
f3f0e1d2 | 2167 | ret = 1; |
579c571e | 2168 | khugepaged_scan_file(mm, file, pgoff, hpage); |
f3f0e1d2 KS |
2169 | fput(file); |
2170 | } else { | |
2171 | ret = khugepaged_scan_pmd(mm, vma, | |
2172 | khugepaged_scan.address, | |
2173 | hpage); | |
2174 | } | |
b46e756f KS |
2175 | /* move to next address */ |
2176 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2177 | progress += HPAGE_PMD_NR; | |
2178 | if (ret) | |
c1e8d7c6 ML |
2179 | /* we released mmap_lock so break loop */ |
2180 | goto breakouterloop_mmap_lock; | |
b46e756f KS |
2181 | if (progress >= pages) |
2182 | goto breakouterloop; | |
2183 | } | |
2184 | } | |
2185 | breakouterloop: | |
d8ed45c5 | 2186 | mmap_read_unlock(mm); /* exit_mmap will destroy ptes after this */ |
c1e8d7c6 | 2187 | breakouterloop_mmap_lock: |
b46e756f KS |
2188 | |
2189 | spin_lock(&khugepaged_mm_lock); | |
2190 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); | |
2191 | /* | |
2192 | * Release the current mm_slot if this mm is about to die, or | |
2193 | * if we scanned all vmas of this mm. | |
2194 | */ | |
2195 | if (khugepaged_test_exit(mm) || !vma) { | |
2196 | /* | |
2197 | * Make sure that if mm_users is reaching zero while | |
2198 | * khugepaged runs here, khugepaged_exit will find | |
2199 | * mm_slot not pointing to the exiting mm. | |
2200 | */ | |
2201 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2202 | khugepaged_scan.mm_slot = list_entry( | |
2203 | mm_slot->mm_node.next, | |
2204 | struct mm_slot, mm_node); | |
2205 | khugepaged_scan.address = 0; | |
2206 | } else { | |
2207 | khugepaged_scan.mm_slot = NULL; | |
2208 | khugepaged_full_scans++; | |
2209 | } | |
2210 | ||
2211 | collect_mm_slot(mm_slot); | |
2212 | } | |
2213 | ||
2214 | return progress; | |
2215 | } | |
2216 | ||
2217 | static int khugepaged_has_work(void) | |
2218 | { | |
2219 | return !list_empty(&khugepaged_scan.mm_head) && | |
2220 | khugepaged_enabled(); | |
2221 | } | |
2222 | ||
2223 | static int khugepaged_wait_event(void) | |
2224 | { | |
2225 | return !list_empty(&khugepaged_scan.mm_head) || | |
2226 | kthread_should_stop(); | |
2227 | } | |
2228 | ||
2229 | static void khugepaged_do_scan(void) | |
2230 | { | |
2231 | struct page *hpage = NULL; | |
2232 | unsigned int progress = 0, pass_through_head = 0; | |
89dc6a96 | 2233 | unsigned int pages = READ_ONCE(khugepaged_pages_to_scan); |
b46e756f KS |
2234 | bool wait = true; |
2235 | ||
a980df33 KS |
2236 | lru_add_drain_all(); |
2237 | ||
b46e756f KS |
2238 | while (progress < pages) { |
2239 | if (!khugepaged_prealloc_page(&hpage, &wait)) | |
2240 | break; | |
2241 | ||
2242 | cond_resched(); | |
2243 | ||
2244 | if (unlikely(kthread_should_stop() || try_to_freeze())) | |
2245 | break; | |
2246 | ||
2247 | spin_lock(&khugepaged_mm_lock); | |
2248 | if (!khugepaged_scan.mm_slot) | |
2249 | pass_through_head++; | |
2250 | if (khugepaged_has_work() && | |
2251 | pass_through_head < 2) | |
2252 | progress += khugepaged_scan_mm_slot(pages - progress, | |
2253 | &hpage); | |
2254 | else | |
2255 | progress = pages; | |
2256 | spin_unlock(&khugepaged_mm_lock); | |
2257 | } | |
2258 | ||
2259 | if (!IS_ERR_OR_NULL(hpage)) | |
2260 | put_page(hpage); | |
2261 | } | |
2262 | ||
2263 | static bool khugepaged_should_wakeup(void) | |
2264 | { | |
2265 | return kthread_should_stop() || | |
2266 | time_after_eq(jiffies, khugepaged_sleep_expire); | |
2267 | } | |
2268 | ||
2269 | static void khugepaged_wait_work(void) | |
2270 | { | |
2271 | if (khugepaged_has_work()) { | |
2272 | const unsigned long scan_sleep_jiffies = | |
2273 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs); | |
2274 | ||
2275 | if (!scan_sleep_jiffies) | |
2276 | return; | |
2277 | ||
2278 | khugepaged_sleep_expire = jiffies + scan_sleep_jiffies; | |
2279 | wait_event_freezable_timeout(khugepaged_wait, | |
2280 | khugepaged_should_wakeup(), | |
2281 | scan_sleep_jiffies); | |
2282 | return; | |
2283 | } | |
2284 | ||
2285 | if (khugepaged_enabled()) | |
2286 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2287 | } | |
2288 | ||
2289 | static int khugepaged(void *none) | |
2290 | { | |
2291 | struct mm_slot *mm_slot; | |
2292 | ||
2293 | set_freezable(); | |
2294 | set_user_nice(current, MAX_NICE); | |
2295 | ||
2296 | while (!kthread_should_stop()) { | |
2297 | khugepaged_do_scan(); | |
2298 | khugepaged_wait_work(); | |
2299 | } | |
2300 | ||
2301 | spin_lock(&khugepaged_mm_lock); | |
2302 | mm_slot = khugepaged_scan.mm_slot; | |
2303 | khugepaged_scan.mm_slot = NULL; | |
2304 | if (mm_slot) | |
2305 | collect_mm_slot(mm_slot); | |
2306 | spin_unlock(&khugepaged_mm_lock); | |
2307 | return 0; | |
2308 | } | |
2309 | ||
2310 | static void set_recommended_min_free_kbytes(void) | |
2311 | { | |
2312 | struct zone *zone; | |
2313 | int nr_zones = 0; | |
2314 | unsigned long recommended_min; | |
2315 | ||
bd3400ea LF |
2316 | if (!khugepaged_enabled()) { |
2317 | calculate_min_free_kbytes(); | |
2318 | goto update_wmarks; | |
2319 | } | |
2320 | ||
b7d349c7 JK |
2321 | for_each_populated_zone(zone) { |
2322 | /* | |
2323 | * We don't need to worry about fragmentation of | |
2324 | * ZONE_MOVABLE since it only has movable pages. | |
2325 | */ | |
2326 | if (zone_idx(zone) > gfp_zone(GFP_USER)) | |
2327 | continue; | |
2328 | ||
b46e756f | 2329 | nr_zones++; |
b7d349c7 | 2330 | } |
b46e756f KS |
2331 | |
2332 | /* Ensure 2 pageblocks are free to assist fragmentation avoidance */ | |
2333 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
2334 | ||
2335 | /* | |
2336 | * Make sure that on average at least two pageblocks are almost free | |
2337 | * of another type, one for a migratetype to fall back to and a | |
2338 | * second to avoid subsequent fallbacks of other types There are 3 | |
2339 | * MIGRATE_TYPES we care about. | |
2340 | */ | |
2341 | recommended_min += pageblock_nr_pages * nr_zones * | |
2342 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
2343 | ||
2344 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
2345 | recommended_min = min(recommended_min, | |
2346 | (unsigned long) nr_free_buffer_pages() / 20); | |
2347 | recommended_min <<= (PAGE_SHIFT-10); | |
2348 | ||
2349 | if (recommended_min > min_free_kbytes) { | |
2350 | if (user_min_free_kbytes >= 0) | |
2351 | pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n", | |
2352 | min_free_kbytes, recommended_min); | |
2353 | ||
2354 | min_free_kbytes = recommended_min; | |
2355 | } | |
bd3400ea LF |
2356 | |
2357 | update_wmarks: | |
b46e756f KS |
2358 | setup_per_zone_wmarks(); |
2359 | } | |
2360 | ||
2361 | int start_stop_khugepaged(void) | |
2362 | { | |
b46e756f KS |
2363 | int err = 0; |
2364 | ||
2365 | mutex_lock(&khugepaged_mutex); | |
2366 | if (khugepaged_enabled()) { | |
2367 | if (!khugepaged_thread) | |
2368 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
2369 | "khugepaged"); | |
2370 | if (IS_ERR(khugepaged_thread)) { | |
2371 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); | |
2372 | err = PTR_ERR(khugepaged_thread); | |
2373 | khugepaged_thread = NULL; | |
2374 | goto fail; | |
2375 | } | |
2376 | ||
2377 | if (!list_empty(&khugepaged_scan.mm_head)) | |
2378 | wake_up_interruptible(&khugepaged_wait); | |
b46e756f KS |
2379 | } else if (khugepaged_thread) { |
2380 | kthread_stop(khugepaged_thread); | |
2381 | khugepaged_thread = NULL; | |
2382 | } | |
bd3400ea | 2383 | set_recommended_min_free_kbytes(); |
b46e756f KS |
2384 | fail: |
2385 | mutex_unlock(&khugepaged_mutex); | |
2386 | return err; | |
2387 | } | |
4aab2be0 VB |
2388 | |
2389 | void khugepaged_min_free_kbytes_update(void) | |
2390 | { | |
2391 | mutex_lock(&khugepaged_mutex); | |
2392 | if (khugepaged_enabled() && khugepaged_thread) | |
2393 | set_recommended_min_free_kbytes(); | |
2394 | mutex_unlock(&khugepaged_mutex); | |
2395 | } |