1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright (C) 2009 Red Hat, Inc. |
4 | */ |
5 | |
6 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
7 | |
8 | #include <linux/mm.h> |
9 | #include <linux/sched.h> |
10 | #include <linux/sched/mm.h> |
11 | #include <linux/sched/coredump.h> |
12 | #include <linux/sched/numa_balancing.h> |
13 | #include <linux/highmem.h> |
14 | #include <linux/hugetlb.h> |
15 | #include <linux/mmu_notifier.h> |
16 | #include <linux/rmap.h> |
17 | #include <linux/swap.h> |
18 | #include <linux/shrinker.h> |
19 | #include <linux/mm_inline.h> |
20 | #include <linux/swapops.h> |
21 | #include <linux/backing-dev.h> |
22 | #include <linux/dax.h> |
23 | #include <linux/khugepaged.h> |
24 | #include <linux/freezer.h> |
25 | #include <linux/pfn_t.h> |
26 | #include <linux/mman.h> |
27 | #include <linux/memremap.h> |
28 | #include <linux/pagemap.h> |
29 | #include <linux/debugfs.h> |
30 | #include <linux/migrate.h> |
31 | #include <linux/hashtable.h> |
32 | #include <linux/userfaultfd_k.h> |
33 | #include <linux/page_idle.h> |
34 | #include <linux/shmem_fs.h> |
35 | #include <linux/oom.h> |
36 | #include <linux/numa.h> |
37 | #include <linux/page_owner.h> |
38 | #include <linux/sched/sysctl.h> |
39 | #include <linux/memory-tiers.h> |
40 | |
41 | #include <asm/tlb.h> |
42 | #include <asm/pgalloc.h> |
43 | #include "internal.h" |
44 | #include "swap.h" |
45 | |
46 | #define CREATE_TRACE_POINTS |
47 | #include <trace/events/thp.h> |
48 | |
49 | /* |
50 | * By default, transparent hugepage support is disabled in order to avoid |
51 | * risking an increased memory footprint for applications that are not |
52 | * guaranteed to benefit from it. When transparent hugepage support is |
53 | * enabled, it is for all mappings, and khugepaged scans all mappings. |
54 | * Defrag is invoked by khugepaged hugepage allocations and by page faults |
55 | * for all hugepage allocations. |
56 | */ |
57 | unsigned long transparent_hugepage_flags __read_mostly = |
58 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS |
59 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| |
60 | #endif |
61 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE |
62 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| |
63 | #endif |
64 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| |
65 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| |
66 | (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); |
67 | |
68 | static struct shrinker *deferred_split_shrinker; |
69 | static unsigned long deferred_split_count(struct shrinker *shrink, |
70 | struct shrink_control *sc); |
71 | static unsigned long deferred_split_scan(struct shrinker *shrink, |
72 | struct shrink_control *sc); |
73 | |
74 | static atomic_t huge_zero_refcount; |
75 | struct page *huge_zero_page __read_mostly; |
76 | unsigned long huge_zero_pfn __read_mostly = ~0UL; |
77 | |
78 | bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags, |
79 | bool smaps, bool in_pf, bool enforce_sysfs) |
80 | { |
81 | if (!vma->vm_mm) /* vdso */ |
82 | return false; |
83 | |
84 | /* |
85 | * Explicitly disabled through madvise or prctl, or some |
86 | * architectures may disable THP for some mappings, for |
87 | * example, s390 kvm. |
88 | * */ |
89 | if ((vm_flags & VM_NOHUGEPAGE) || |
90 | test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) |
91 | return false; |
92 | /* |
93 | * If the hardware/firmware marked hugepage support disabled. |
94 | */ |
95 | if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED)) |
96 | return false; |
97 | |
98 | /* khugepaged doesn't collapse DAX vma, but page fault is fine. */ |
99 | if (vma_is_dax(vma)) |
100 | return in_pf; |
101 | |
102 | /* |
103 | * khugepaged special VMA and hugetlb VMA. |
104 | * Must be checked after dax since some dax mappings may have |
105 | * VM_MIXEDMAP set. |
106 | */ |
107 | if (!in_pf && !smaps && (vm_flags & VM_NO_KHUGEPAGED)) |
108 | return false; |
109 | |
110 | /* |
111 | * Check alignment for file vma and size for both file and anon vma. |
112 | * |
113 | * Skip the check for page fault. Huge fault does the check in fault |
114 | * handlers. And this check is not suitable for huge PUD fault. |
115 | */ |
116 | if (!in_pf && |
117 | !transhuge_vma_suitable(vma, addr: (vma->vm_end - HPAGE_PMD_SIZE))) |
118 | return false; |
119 | |
120 | /* |
121 | * Enabled via shmem mount options or sysfs settings. |
122 | * Must be done before hugepage flags check since shmem has its |
123 | * own flags. |
124 | */ |
125 | if (!in_pf && shmem_file(file: vma->vm_file)) |
126 | return shmem_is_huge(inode: file_inode(f: vma->vm_file), index: vma->vm_pgoff, |
127 | shmem_huge_force: !enforce_sysfs, mm: vma->vm_mm, vm_flags); |
128 | |
129 | /* Enforce sysfs THP requirements as necessary */ |
130 | if (enforce_sysfs && |
131 | (!hugepage_flags_enabled() || (!(vm_flags & VM_HUGEPAGE) && |
132 | !hugepage_flags_always()))) |
133 | return false; |
134 | |
135 | if (!vma_is_anonymous(vma)) { |
136 | /* |
137 | * Trust that ->huge_fault() handlers know what they are doing |
138 | * in fault path. |
139 | */ |
140 | if (((in_pf || smaps)) && vma->vm_ops->huge_fault) |
141 | return true; |
142 | /* Only regular file is valid in collapse path */ |
143 | if (((!in_pf || smaps)) && file_thp_enabled(vma)) |
144 | return true; |
145 | return false; |
146 | } |
147 | |
148 | if (vma_is_temporary_stack(vma)) |
149 | return false; |
150 | |
151 | /* |
152 | * THPeligible bit of smaps should show 1 for proper VMAs even |
153 | * though anon_vma is not initialized yet. |
154 | * |
155 | * Allow page fault since anon_vma may be not initialized until |
156 | * the first page fault. |
157 | */ |
158 | if (!vma->anon_vma) |
159 | return (smaps || in_pf); |
160 | |
161 | return true; |
162 | } |
163 | |
164 | static bool get_huge_zero_page(void) |
165 | { |
166 | struct page *zero_page; |
167 | retry: |
168 | if (likely(atomic_inc_not_zero(&huge_zero_refcount))) |
169 | return true; |
170 | |
171 | zero_page = alloc_pages(gfp: (GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, |
172 | HPAGE_PMD_ORDER); |
173 | if (!zero_page) { |
174 | count_vm_event(item: THP_ZERO_PAGE_ALLOC_FAILED); |
175 | return false; |
176 | } |
177 | preempt_disable(); |
178 | if (cmpxchg(&huge_zero_page, NULL, zero_page)) { |
179 | preempt_enable(); |
180 | __free_pages(page: zero_page, order: compound_order(page: zero_page)); |
181 | goto retry; |
182 | } |
183 | WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page)); |
184 | |
185 | /* We take additional reference here. It will be put back by shrinker */ |
186 | atomic_set(v: &huge_zero_refcount, i: 2); |
187 | preempt_enable(); |
188 | count_vm_event(item: THP_ZERO_PAGE_ALLOC); |
189 | return true; |
190 | } |
191 | |
192 | static void put_huge_zero_page(void) |
193 | { |
194 | /* |
195 | * Counter should never go to zero here. Only shrinker can put |
196 | * last reference. |
197 | */ |
198 | BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); |
199 | } |
200 | |
201 | struct page *mm_get_huge_zero_page(struct mm_struct *mm) |
202 | { |
203 | if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) |
204 | return READ_ONCE(huge_zero_page); |
205 | |
206 | if (!get_huge_zero_page()) |
207 | return NULL; |
208 | |
209 | if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, addr: &mm->flags)) |
210 | put_huge_zero_page(); |
211 | |
212 | return READ_ONCE(huge_zero_page); |
213 | } |
214 | |
215 | void mm_put_huge_zero_page(struct mm_struct *mm) |
216 | { |
217 | if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) |
218 | put_huge_zero_page(); |
219 | } |
220 | |
221 | static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, |
222 | struct shrink_control *sc) |
223 | { |
224 | /* we can free zero page only if last reference remains */ |
225 | return atomic_read(v: &huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; |
226 | } |
227 | |
228 | static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, |
229 | struct shrink_control *sc) |
230 | { |
231 | if (atomic_cmpxchg(v: &huge_zero_refcount, old: 1, new: 0) == 1) { |
232 | struct page *zero_page = xchg(&huge_zero_page, NULL); |
233 | BUG_ON(zero_page == NULL); |
234 | WRITE_ONCE(huge_zero_pfn, ~0UL); |
235 | __free_pages(page: zero_page, order: compound_order(page: zero_page)); |
236 | return HPAGE_PMD_NR; |
237 | } |
238 | |
239 | return 0; |
240 | } |
241 | |
242 | static struct shrinker *huge_zero_page_shrinker; |
243 | |
244 | #ifdef CONFIG_SYSFS |
245 | static ssize_t enabled_show(struct kobject *kobj, |
246 | struct kobj_attribute *attr, char *buf) |
247 | { |
248 | const char *output; |
249 | |
250 | if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) |
251 | output = "[always] madvise never" ; |
252 | else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, |
253 | &transparent_hugepage_flags)) |
254 | output = "always [madvise] never" ; |
255 | else |
256 | output = "always madvise [never]" ; |
257 | |
258 | return sysfs_emit(buf, fmt: "%s\n" , output); |
259 | } |
260 | |
261 | static ssize_t enabled_store(struct kobject *kobj, |
262 | struct kobj_attribute *attr, |
263 | const char *buf, size_t count) |
264 | { |
265 | ssize_t ret = count; |
266 | |
267 | if (sysfs_streq(s1: buf, s2: "always" )) { |
268 | clear_bit(nr: TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, addr: &transparent_hugepage_flags); |
269 | set_bit(nr: TRANSPARENT_HUGEPAGE_FLAG, addr: &transparent_hugepage_flags); |
270 | } else if (sysfs_streq(s1: buf, s2: "madvise" )) { |
271 | clear_bit(nr: TRANSPARENT_HUGEPAGE_FLAG, addr: &transparent_hugepage_flags); |
272 | set_bit(nr: TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, addr: &transparent_hugepage_flags); |
273 | } else if (sysfs_streq(s1: buf, s2: "never" )) { |
274 | clear_bit(nr: TRANSPARENT_HUGEPAGE_FLAG, addr: &transparent_hugepage_flags); |
275 | clear_bit(nr: TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, addr: &transparent_hugepage_flags); |
276 | } else |
277 | ret = -EINVAL; |
278 | |
279 | if (ret > 0) { |
280 | int err = start_stop_khugepaged(); |
281 | if (err) |
282 | ret = err; |
283 | } |
284 | return ret; |
285 | } |
286 | |
287 | static struct kobj_attribute enabled_attr = __ATTR_RW(enabled); |
288 | |
289 | ssize_t single_hugepage_flag_show(struct kobject *kobj, |
290 | struct kobj_attribute *attr, char *buf, |
291 | enum transparent_hugepage_flag flag) |
292 | { |
293 | return sysfs_emit(buf, fmt: "%d\n" , |
294 | !!test_bit(flag, &transparent_hugepage_flags)); |
295 | } |
296 | |
297 | ssize_t single_hugepage_flag_store(struct kobject *kobj, |
298 | struct kobj_attribute *attr, |
299 | const char *buf, size_t count, |
300 | enum transparent_hugepage_flag flag) |
301 | { |
302 | unsigned long value; |
303 | int ret; |
304 | |
305 | ret = kstrtoul(s: buf, base: 10, res: &value); |
306 | if (ret < 0) |
307 | return ret; |
308 | if (value > 1) |
309 | return -EINVAL; |
310 | |
311 | if (value) |
312 | set_bit(nr: flag, addr: &transparent_hugepage_flags); |
313 | else |
314 | clear_bit(nr: flag, addr: &transparent_hugepage_flags); |
315 | |
316 | return count; |
317 | } |
318 | |
319 | static ssize_t defrag_show(struct kobject *kobj, |
320 | struct kobj_attribute *attr, char *buf) |
321 | { |
322 | const char *output; |
323 | |
324 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, |
325 | &transparent_hugepage_flags)) |
326 | output = "[always] defer defer+madvise madvise never" ; |
327 | else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, |
328 | &transparent_hugepage_flags)) |
329 | output = "always [defer] defer+madvise madvise never" ; |
330 | else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, |
331 | &transparent_hugepage_flags)) |
332 | output = "always defer [defer+madvise] madvise never" ; |
333 | else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, |
334 | &transparent_hugepage_flags)) |
335 | output = "always defer defer+madvise [madvise] never" ; |
336 | else |
337 | output = "always defer defer+madvise madvise [never]" ; |
338 | |
339 | return sysfs_emit(buf, fmt: "%s\n" , output); |
340 | } |
341 | |
342 | static ssize_t defrag_store(struct kobject *kobj, |
343 | struct kobj_attribute *attr, |
344 | const char *buf, size_t count) |
345 | { |
346 | if (sysfs_streq(s1: buf, s2: "always" )) { |
347 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, addr: &transparent_hugepage_flags); |
348 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, addr: &transparent_hugepage_flags); |
349 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, addr: &transparent_hugepage_flags); |
350 | set_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, addr: &transparent_hugepage_flags); |
351 | } else if (sysfs_streq(s1: buf, s2: "defer+madvise" )) { |
352 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, addr: &transparent_hugepage_flags); |
353 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, addr: &transparent_hugepage_flags); |
354 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, addr: &transparent_hugepage_flags); |
355 | set_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, addr: &transparent_hugepage_flags); |
356 | } else if (sysfs_streq(s1: buf, s2: "defer" )) { |
357 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, addr: &transparent_hugepage_flags); |
358 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, addr: &transparent_hugepage_flags); |
359 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, addr: &transparent_hugepage_flags); |
360 | set_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, addr: &transparent_hugepage_flags); |
361 | } else if (sysfs_streq(s1: buf, s2: "madvise" )) { |
362 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, addr: &transparent_hugepage_flags); |
363 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, addr: &transparent_hugepage_flags); |
364 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, addr: &transparent_hugepage_flags); |
365 | set_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, addr: &transparent_hugepage_flags); |
366 | } else if (sysfs_streq(s1: buf, s2: "never" )) { |
367 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, addr: &transparent_hugepage_flags); |
368 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, addr: &transparent_hugepage_flags); |
369 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, addr: &transparent_hugepage_flags); |
370 | clear_bit(nr: TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, addr: &transparent_hugepage_flags); |
371 | } else |
372 | return -EINVAL; |
373 | |
374 | return count; |
375 | } |
376 | static struct kobj_attribute defrag_attr = __ATTR_RW(defrag); |
377 | |
378 | static ssize_t use_zero_page_show(struct kobject *kobj, |
379 | struct kobj_attribute *attr, char *buf) |
380 | { |
381 | return single_hugepage_flag_show(kobj, attr, buf, |
382 | flag: TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); |
383 | } |
384 | static ssize_t use_zero_page_store(struct kobject *kobj, |
385 | struct kobj_attribute *attr, const char *buf, size_t count) |
386 | { |
387 | return single_hugepage_flag_store(kobj, attr, buf, count, |
388 | flag: TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); |
389 | } |
390 | static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page); |
391 | |
392 | static ssize_t hpage_pmd_size_show(struct kobject *kobj, |
393 | struct kobj_attribute *attr, char *buf) |
394 | { |
395 | return sysfs_emit(buf, fmt: "%lu\n" , HPAGE_PMD_SIZE); |
396 | } |
397 | static struct kobj_attribute hpage_pmd_size_attr = |
398 | __ATTR_RO(hpage_pmd_size); |
399 | |
400 | static struct attribute *hugepage_attr[] = { |
401 | &enabled_attr.attr, |
402 | &defrag_attr.attr, |
403 | &use_zero_page_attr.attr, |
404 | &hpage_pmd_size_attr.attr, |
405 | #ifdef CONFIG_SHMEM |
406 | &shmem_enabled_attr.attr, |
407 | #endif |
408 | NULL, |
409 | }; |
410 | |
411 | static const struct attribute_group hugepage_attr_group = { |
412 | .attrs = hugepage_attr, |
413 | }; |
414 | |
415 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
416 | { |
417 | int err; |
418 | |
419 | *hugepage_kobj = kobject_create_and_add(name: "transparent_hugepage" , parent: mm_kobj); |
420 | if (unlikely(!*hugepage_kobj)) { |
421 | pr_err("failed to create transparent hugepage kobject\n" ); |
422 | return -ENOMEM; |
423 | } |
424 | |
425 | err = sysfs_create_group(kobj: *hugepage_kobj, grp: &hugepage_attr_group); |
426 | if (err) { |
427 | pr_err("failed to register transparent hugepage group\n" ); |
428 | goto delete_obj; |
429 | } |
430 | |
431 | err = sysfs_create_group(kobj: *hugepage_kobj, grp: &khugepaged_attr_group); |
432 | if (err) { |
433 | pr_err("failed to register transparent hugepage group\n" ); |
434 | goto remove_hp_group; |
435 | } |
436 | |
437 | return 0; |
438 | |
439 | remove_hp_group: |
440 | sysfs_remove_group(kobj: *hugepage_kobj, grp: &hugepage_attr_group); |
441 | delete_obj: |
442 | kobject_put(kobj: *hugepage_kobj); |
443 | return err; |
444 | } |
445 | |
446 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) |
447 | { |
448 | sysfs_remove_group(kobj: hugepage_kobj, grp: &khugepaged_attr_group); |
449 | sysfs_remove_group(kobj: hugepage_kobj, grp: &hugepage_attr_group); |
450 | kobject_put(kobj: hugepage_kobj); |
451 | } |
452 | #else |
453 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) |
454 | { |
455 | return 0; |
456 | } |
457 | |
458 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) |
459 | { |
460 | } |
461 | #endif /* CONFIG_SYSFS */ |
462 | |
463 | static int __init thp_shrinker_init(void) |
464 | { |
465 | huge_zero_page_shrinker = shrinker_alloc(flags: 0, fmt: "thp-zero" ); |
466 | if (!huge_zero_page_shrinker) |
467 | return -ENOMEM; |
468 | |
469 | deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE | |
470 | SHRINKER_MEMCG_AWARE | |
471 | SHRINKER_NONSLAB, |
472 | fmt: "thp-deferred_split" ); |
473 | if (!deferred_split_shrinker) { |
474 | shrinker_free(shrinker: huge_zero_page_shrinker); |
475 | return -ENOMEM; |
476 | } |
477 | |
478 | huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count; |
479 | huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan; |
480 | shrinker_register(shrinker: huge_zero_page_shrinker); |
481 | |
482 | deferred_split_shrinker->count_objects = deferred_split_count; |
483 | deferred_split_shrinker->scan_objects = deferred_split_scan; |
484 | shrinker_register(shrinker: deferred_split_shrinker); |
485 | |
486 | return 0; |
487 | } |
488 | |
489 | static void __init thp_shrinker_exit(void) |
490 | { |
491 | shrinker_free(shrinker: huge_zero_page_shrinker); |
492 | shrinker_free(shrinker: deferred_split_shrinker); |
493 | } |
494 | |
495 | static int __init hugepage_init(void) |
496 | { |
497 | int err; |
498 | struct kobject *hugepage_kobj; |
499 | |
500 | if (!has_transparent_hugepage()) { |
501 | transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED; |
502 | return -EINVAL; |
503 | } |
504 | |
505 | /* |
506 | * hugepages can't be allocated by the buddy allocator |
507 | */ |
508 | MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER > MAX_ORDER); |
509 | /* |
510 | * we use page->mapping and page->index in second tail page |
511 | * as list_head: assuming THP order >= 2 |
512 | */ |
513 | MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); |
514 | |
515 | err = hugepage_init_sysfs(hugepage_kobj: &hugepage_kobj); |
516 | if (err) |
517 | goto err_sysfs; |
518 | |
519 | err = khugepaged_init(); |
520 | if (err) |
521 | goto err_slab; |
522 | |
523 | err = thp_shrinker_init(); |
524 | if (err) |
525 | goto err_shrinker; |
526 | |
527 | /* |
528 | * By default disable transparent hugepages on smaller systems, |
529 | * where the extra memory used could hurt more than TLB overhead |
530 | * is likely to save. The admin can still enable it through /sys. |
531 | */ |
532 | if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { |
533 | transparent_hugepage_flags = 0; |
534 | return 0; |
535 | } |
536 | |
537 | err = start_stop_khugepaged(); |
538 | if (err) |
539 | goto err_khugepaged; |
540 | |
541 | return 0; |
542 | err_khugepaged: |
543 | thp_shrinker_exit(); |
544 | err_shrinker: |
545 | khugepaged_destroy(); |
546 | err_slab: |
547 | hugepage_exit_sysfs(hugepage_kobj); |
548 | err_sysfs: |
549 | return err; |
550 | } |
551 | subsys_initcall(hugepage_init); |
552 | |
553 | static int __init setup_transparent_hugepage(char *str) |
554 | { |
555 | int ret = 0; |
556 | if (!str) |
557 | goto out; |
558 | if (!strcmp(str, "always" )) { |
559 | set_bit(nr: TRANSPARENT_HUGEPAGE_FLAG, |
560 | addr: &transparent_hugepage_flags); |
561 | clear_bit(nr: TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, |
562 | addr: &transparent_hugepage_flags); |
563 | ret = 1; |
564 | } else if (!strcmp(str, "madvise" )) { |
565 | clear_bit(nr: TRANSPARENT_HUGEPAGE_FLAG, |
566 | addr: &transparent_hugepage_flags); |
567 | set_bit(nr: TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, |
568 | addr: &transparent_hugepage_flags); |
569 | ret = 1; |
570 | } else if (!strcmp(str, "never" )) { |
571 | clear_bit(nr: TRANSPARENT_HUGEPAGE_FLAG, |
572 | addr: &transparent_hugepage_flags); |
573 | clear_bit(nr: TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, |
574 | addr: &transparent_hugepage_flags); |
575 | ret = 1; |
576 | } |
577 | out: |
578 | if (!ret) |
579 | pr_warn("transparent_hugepage= cannot parse, ignored\n" ); |
580 | return ret; |
581 | } |
582 | __setup("transparent_hugepage=" , setup_transparent_hugepage); |
583 | |
584 | pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) |
585 | { |
586 | if (likely(vma->vm_flags & VM_WRITE)) |
587 | pmd = pmd_mkwrite(pmd, vma); |
588 | return pmd; |
589 | } |
590 | |
591 | #ifdef CONFIG_MEMCG |
592 | static inline |
593 | struct deferred_split *get_deferred_split_queue(struct folio *folio) |
594 | { |
595 | struct mem_cgroup *memcg = folio_memcg(folio); |
596 | struct pglist_data *pgdat = NODE_DATA(folio_nid(folio)); |
597 | |
598 | if (memcg) |
599 | return &memcg->deferred_split_queue; |
600 | else |
601 | return &pgdat->deferred_split_queue; |
602 | } |
603 | #else |
604 | static inline |
605 | struct deferred_split *get_deferred_split_queue(struct folio *folio) |
606 | { |
607 | struct pglist_data *pgdat = NODE_DATA(folio_nid(folio)); |
608 | |
609 | return &pgdat->deferred_split_queue; |
610 | } |
611 | #endif |
612 | |
613 | void folio_prep_large_rmappable(struct folio *folio) |
614 | { |
615 | VM_BUG_ON_FOLIO(folio_order(folio) < 2, folio); |
616 | INIT_LIST_HEAD(list: &folio->_deferred_list); |
617 | folio_set_large_rmappable(folio); |
618 | } |
619 | |
620 | static inline bool is_transparent_hugepage(struct folio *folio) |
621 | { |
622 | if (!folio_test_large(folio)) |
623 | return false; |
624 | |
625 | return is_huge_zero_page(page: &folio->page) || |
626 | folio_test_large_rmappable(folio); |
627 | } |
628 | |
629 | static unsigned long __thp_get_unmapped_area(struct file *filp, |
630 | unsigned long addr, unsigned long len, |
631 | loff_t off, unsigned long flags, unsigned long size) |
632 | { |
633 | loff_t off_end = off + len; |
634 | loff_t off_align = round_up(off, size); |
635 | unsigned long len_pad, ret; |
636 | |
637 | if (off_end <= off_align || (off_end - off_align) < size) |
638 | return 0; |
639 | |
640 | len_pad = len + size; |
641 | if (len_pad < len || (off + len_pad) < off) |
642 | return 0; |
643 | |
644 | ret = current->mm->get_unmapped_area(filp, addr, len_pad, |
645 | off >> PAGE_SHIFT, flags); |
646 | |
647 | /* |
648 | * The failure might be due to length padding. The caller will retry |
649 | * without the padding. |
650 | */ |
651 | if (IS_ERR_VALUE(ret)) |
652 | return 0; |
653 | |
654 | /* |
655 | * Do not try to align to THP boundary if allocation at the address |
656 | * hint succeeds. |
657 | */ |
658 | if (ret == addr) |
659 | return addr; |
660 | |
661 | ret += (off - ret) & (size - 1); |
662 | return ret; |
663 | } |
664 | |
665 | unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, |
666 | unsigned long len, unsigned long pgoff, unsigned long flags) |
667 | { |
668 | unsigned long ret; |
669 | loff_t off = (loff_t)pgoff << PAGE_SHIFT; |
670 | |
671 | ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE); |
672 | if (ret) |
673 | return ret; |
674 | |
675 | return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); |
676 | } |
677 | EXPORT_SYMBOL_GPL(thp_get_unmapped_area); |
678 | |
679 | static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, |
680 | struct page *page, gfp_t gfp) |
681 | { |
682 | struct vm_area_struct *vma = vmf->vma; |
683 | struct folio *folio = page_folio(page); |
684 | pgtable_t pgtable; |
685 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
686 | vm_fault_t ret = 0; |
687 | |
688 | VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); |
689 | |
690 | if (mem_cgroup_charge(folio, mm: vma->vm_mm, gfp)) { |
691 | folio_put(folio); |
692 | count_vm_event(item: THP_FAULT_FALLBACK); |
693 | count_vm_event(item: THP_FAULT_FALLBACK_CHARGE); |
694 | return VM_FAULT_FALLBACK; |
695 | } |
696 | folio_throttle_swaprate(folio, gfp); |
697 | |
698 | pgtable = pte_alloc_one(vma->vm_mm); |
699 | if (unlikely(!pgtable)) { |
700 | ret = VM_FAULT_OOM; |
701 | goto release; |
702 | } |
703 | |
704 | clear_huge_page(page, addr_hint: vmf->address, HPAGE_PMD_NR); |
705 | /* |
706 | * The memory barrier inside __folio_mark_uptodate makes sure that |
707 | * clear_huge_page writes become visible before the set_pmd_at() |
708 | * write. |
709 | */ |
710 | __folio_mark_uptodate(folio); |
711 | |
712 | vmf->ptl = pmd_lock(mm: vma->vm_mm, pmd: vmf->pmd); |
713 | if (unlikely(!pmd_none(*vmf->pmd))) { |
714 | goto unlock_release; |
715 | } else { |
716 | pmd_t entry; |
717 | |
718 | ret = check_stable_address_space(mm: vma->vm_mm); |
719 | if (ret) |
720 | goto unlock_release; |
721 | |
722 | /* Deliver the page fault to userland */ |
723 | if (userfaultfd_missing(vma)) { |
724 | spin_unlock(lock: vmf->ptl); |
725 | folio_put(folio); |
726 | pte_free(mm: vma->vm_mm, pte_page: pgtable); |
727 | ret = handle_userfault(vmf, VM_UFFD_MISSING); |
728 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); |
729 | return ret; |
730 | } |
731 | |
732 | entry = mk_huge_pmd(page, vma->vm_page_prot); |
733 | entry = maybe_pmd_mkwrite(pmd: pmd_mkdirty(pmd: entry), vma); |
734 | folio_add_new_anon_rmap(folio, vma, address: haddr); |
735 | folio_add_lru_vma(folio, vma); |
736 | pgtable_trans_huge_deposit(mm: vma->vm_mm, pmdp: vmf->pmd, pgtable); |
737 | set_pmd_at(mm: vma->vm_mm, addr: haddr, pmdp: vmf->pmd, pmd: entry); |
738 | update_mmu_cache_pmd(vma, addr: vmf->address, pmd: vmf->pmd); |
739 | add_mm_counter(mm: vma->vm_mm, member: MM_ANONPAGES, HPAGE_PMD_NR); |
740 | mm_inc_nr_ptes(mm: vma->vm_mm); |
741 | spin_unlock(lock: vmf->ptl); |
742 | count_vm_event(item: THP_FAULT_ALLOC); |
743 | count_memcg_event_mm(mm: vma->vm_mm, idx: THP_FAULT_ALLOC); |
744 | } |
745 | |
746 | return 0; |
747 | unlock_release: |
748 | spin_unlock(lock: vmf->ptl); |
749 | release: |
750 | if (pgtable) |
751 | pte_free(mm: vma->vm_mm, pte_page: pgtable); |
752 | folio_put(folio); |
753 | return ret; |
754 | |
755 | } |
756 | |
757 | /* |
758 | * always: directly stall for all thp allocations |
759 | * defer: wake kswapd and fail if not immediately available |
760 | * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise |
761 | * fail if not immediately available |
762 | * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately |
763 | * available |
764 | * never: never stall for any thp allocation |
765 | */ |
766 | gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma) |
767 | { |
768 | const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE); |
769 | |
770 | /* Always do synchronous compaction */ |
771 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) |
772 | return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); |
773 | |
774 | /* Kick kcompactd and fail quickly */ |
775 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) |
776 | return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; |
777 | |
778 | /* Synchronous compaction if madvised, otherwise kick kcompactd */ |
779 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) |
780 | return GFP_TRANSHUGE_LIGHT | |
781 | (vma_madvised ? __GFP_DIRECT_RECLAIM : |
782 | __GFP_KSWAPD_RECLAIM); |
783 | |
784 | /* Only do synchronous compaction if madvised */ |
785 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) |
786 | return GFP_TRANSHUGE_LIGHT | |
787 | (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); |
788 | |
789 | return GFP_TRANSHUGE_LIGHT; |
790 | } |
791 | |
792 | /* Caller must hold page table lock. */ |
793 | static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, |
794 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, |
795 | struct page *zero_page) |
796 | { |
797 | pmd_t entry; |
798 | if (!pmd_none(pmd: *pmd)) |
799 | return; |
800 | entry = mk_pmd(zero_page, vma->vm_page_prot); |
801 | entry = pmd_mkhuge(pmd: entry); |
802 | pgtable_trans_huge_deposit(mm, pmdp: pmd, pgtable); |
803 | set_pmd_at(mm, addr: haddr, pmdp: pmd, pmd: entry); |
804 | mm_inc_nr_ptes(mm); |
805 | } |
806 | |
807 | vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) |
808 | { |
809 | struct vm_area_struct *vma = vmf->vma; |
810 | gfp_t gfp; |
811 | struct folio *folio; |
812 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
813 | |
814 | if (!transhuge_vma_suitable(vma, addr: haddr)) |
815 | return VM_FAULT_FALLBACK; |
816 | if (unlikely(anon_vma_prepare(vma))) |
817 | return VM_FAULT_OOM; |
818 | khugepaged_enter_vma(vma, vm_flags: vma->vm_flags); |
819 | |
820 | if (!(vmf->flags & FAULT_FLAG_WRITE) && |
821 | !mm_forbids_zeropage(vma->vm_mm) && |
822 | transparent_hugepage_use_zero_page()) { |
823 | pgtable_t pgtable; |
824 | struct page *zero_page; |
825 | vm_fault_t ret; |
826 | pgtable = pte_alloc_one(vma->vm_mm); |
827 | if (unlikely(!pgtable)) |
828 | return VM_FAULT_OOM; |
829 | zero_page = mm_get_huge_zero_page(mm: vma->vm_mm); |
830 | if (unlikely(!zero_page)) { |
831 | pte_free(mm: vma->vm_mm, pte_page: pgtable); |
832 | count_vm_event(item: THP_FAULT_FALLBACK); |
833 | return VM_FAULT_FALLBACK; |
834 | } |
835 | vmf->ptl = pmd_lock(mm: vma->vm_mm, pmd: vmf->pmd); |
836 | ret = 0; |
837 | if (pmd_none(pmd: *vmf->pmd)) { |
838 | ret = check_stable_address_space(mm: vma->vm_mm); |
839 | if (ret) { |
840 | spin_unlock(lock: vmf->ptl); |
841 | pte_free(mm: vma->vm_mm, pte_page: pgtable); |
842 | } else if (userfaultfd_missing(vma)) { |
843 | spin_unlock(lock: vmf->ptl); |
844 | pte_free(mm: vma->vm_mm, pte_page: pgtable); |
845 | ret = handle_userfault(vmf, VM_UFFD_MISSING); |
846 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); |
847 | } else { |
848 | set_huge_zero_page(pgtable, mm: vma->vm_mm, vma, |
849 | haddr, pmd: vmf->pmd, zero_page); |
850 | update_mmu_cache_pmd(vma, addr: vmf->address, pmd: vmf->pmd); |
851 | spin_unlock(lock: vmf->ptl); |
852 | } |
853 | } else { |
854 | spin_unlock(lock: vmf->ptl); |
855 | pte_free(mm: vma->vm_mm, pte_page: pgtable); |
856 | } |
857 | return ret; |
858 | } |
859 | gfp = vma_thp_gfp_mask(vma); |
860 | folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, addr: haddr, hugepage: true); |
861 | if (unlikely(!folio)) { |
862 | count_vm_event(item: THP_FAULT_FALLBACK); |
863 | return VM_FAULT_FALLBACK; |
864 | } |
865 | return __do_huge_pmd_anonymous_page(vmf, page: &folio->page, gfp); |
866 | } |
867 | |
868 | static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, |
869 | pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, |
870 | pgtable_t pgtable) |
871 | { |
872 | struct mm_struct *mm = vma->vm_mm; |
873 | pmd_t entry; |
874 | spinlock_t *ptl; |
875 | |
876 | ptl = pmd_lock(mm, pmd); |
877 | if (!pmd_none(pmd: *pmd)) { |
878 | if (write) { |
879 | if (pmd_pfn(pmd: *pmd) != pfn_t_to_pfn(pfn)) { |
880 | WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); |
881 | goto out_unlock; |
882 | } |
883 | entry = pmd_mkyoung(pmd: *pmd); |
884 | entry = maybe_pmd_mkwrite(pmd: pmd_mkdirty(pmd: entry), vma); |
885 | if (pmdp_set_access_flags(vma, address: addr, pmdp: pmd, entry, dirty: 1)) |
886 | update_mmu_cache_pmd(vma, addr, pmd); |
887 | } |
888 | |
889 | goto out_unlock; |
890 | } |
891 | |
892 | entry = pmd_mkhuge(pmd: pfn_t_pmd(pfn, pgprot: prot)); |
893 | if (pfn_t_devmap(pfn)) |
894 | entry = pmd_mkdevmap(pmd: entry); |
895 | if (write) { |
896 | entry = pmd_mkyoung(pmd: pmd_mkdirty(pmd: entry)); |
897 | entry = maybe_pmd_mkwrite(pmd: entry, vma); |
898 | } |
899 | |
900 | if (pgtable) { |
901 | pgtable_trans_huge_deposit(mm, pmdp: pmd, pgtable); |
902 | mm_inc_nr_ptes(mm); |
903 | pgtable = NULL; |
904 | } |
905 | |
906 | set_pmd_at(mm, addr, pmdp: pmd, pmd: entry); |
907 | update_mmu_cache_pmd(vma, addr, pmd); |
908 | |
909 | out_unlock: |
910 | spin_unlock(lock: ptl); |
911 | if (pgtable) |
912 | pte_free(mm, pte_page: pgtable); |
913 | } |
914 | |
915 | /** |
916 | * vmf_insert_pfn_pmd - insert a pmd size pfn |
917 | * @vmf: Structure describing the fault |
918 | * @pfn: pfn to insert |
919 | * @write: whether it's a write fault |
920 | * |
921 | * Insert a pmd size pfn. See vmf_insert_pfn() for additional info. |
922 | * |
923 | * Return: vm_fault_t value. |
924 | */ |
925 | vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write) |
926 | { |
927 | unsigned long addr = vmf->address & PMD_MASK; |
928 | struct vm_area_struct *vma = vmf->vma; |
929 | pgprot_t pgprot = vma->vm_page_prot; |
930 | pgtable_t pgtable = NULL; |
931 | |
932 | /* |
933 | * If we had pmd_special, we could avoid all these restrictions, |
934 | * but we need to be consistent with PTEs and architectures that |
935 | * can't support a 'special' bit. |
936 | */ |
937 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && |
938 | !pfn_t_devmap(pfn)); |
939 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == |
940 | (VM_PFNMAP|VM_MIXEDMAP)); |
941 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); |
942 | |
943 | if (addr < vma->vm_start || addr >= vma->vm_end) |
944 | return VM_FAULT_SIGBUS; |
945 | |
946 | if (arch_needs_pgtable_deposit()) { |
947 | pgtable = pte_alloc_one(vma->vm_mm); |
948 | if (!pgtable) |
949 | return VM_FAULT_OOM; |
950 | } |
951 | |
952 | track_pfn_insert(vma, prot: &pgprot, pfn); |
953 | |
954 | insert_pfn_pmd(vma, addr, pmd: vmf->pmd, pfn, prot: pgprot, write, pgtable); |
955 | return VM_FAULT_NOPAGE; |
956 | } |
957 | EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); |
958 | |
959 | #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD |
960 | static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) |
961 | { |
962 | if (likely(vma->vm_flags & VM_WRITE)) |
963 | pud = pud_mkwrite(pud); |
964 | return pud; |
965 | } |
966 | |
967 | static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, |
968 | pud_t *pud, pfn_t pfn, bool write) |
969 | { |
970 | struct mm_struct *mm = vma->vm_mm; |
971 | pgprot_t prot = vma->vm_page_prot; |
972 | pud_t entry; |
973 | spinlock_t *ptl; |
974 | |
975 | ptl = pud_lock(mm, pud); |
976 | if (!pud_none(pud: *pud)) { |
977 | if (write) { |
978 | if (pud_pfn(pud: *pud) != pfn_t_to_pfn(pfn)) { |
979 | WARN_ON_ONCE(!is_huge_zero_pud(*pud)); |
980 | goto out_unlock; |
981 | } |
982 | entry = pud_mkyoung(pud: *pud); |
983 | entry = maybe_pud_mkwrite(pud: pud_mkdirty(pud: entry), vma); |
984 | if (pudp_set_access_flags(vma, address: addr, pudp: pud, entry, dirty: 1)) |
985 | update_mmu_cache_pud(vma, addr, pud); |
986 | } |
987 | goto out_unlock; |
988 | } |
989 | |
990 | entry = pud_mkhuge(pud: pfn_t_pud(pfn, pgprot: prot)); |
991 | if (pfn_t_devmap(pfn)) |
992 | entry = pud_mkdevmap(pud: entry); |
993 | if (write) { |
994 | entry = pud_mkyoung(pud: pud_mkdirty(pud: entry)); |
995 | entry = maybe_pud_mkwrite(pud: entry, vma); |
996 | } |
997 | set_pud_at(mm, addr, pudp: pud, pud: entry); |
998 | update_mmu_cache_pud(vma, addr, pud); |
999 | |
1000 | out_unlock: |
1001 | spin_unlock(lock: ptl); |
1002 | } |
1003 | |
1004 | /** |
1005 | * vmf_insert_pfn_pud - insert a pud size pfn |
1006 | * @vmf: Structure describing the fault |
1007 | * @pfn: pfn to insert |
1008 | * @write: whether it's a write fault |
1009 | * |
1010 | * Insert a pud size pfn. See vmf_insert_pfn() for additional info. |
1011 | * |
1012 | * Return: vm_fault_t value. |
1013 | */ |
1014 | vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write) |
1015 | { |
1016 | unsigned long addr = vmf->address & PUD_MASK; |
1017 | struct vm_area_struct *vma = vmf->vma; |
1018 | pgprot_t pgprot = vma->vm_page_prot; |
1019 | |
1020 | /* |
1021 | * If we had pud_special, we could avoid all these restrictions, |
1022 | * but we need to be consistent with PTEs and architectures that |
1023 | * can't support a 'special' bit. |
1024 | */ |
1025 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && |
1026 | !pfn_t_devmap(pfn)); |
1027 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == |
1028 | (VM_PFNMAP|VM_MIXEDMAP)); |
1029 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); |
1030 | |
1031 | if (addr < vma->vm_start || addr >= vma->vm_end) |
1032 | return VM_FAULT_SIGBUS; |
1033 | |
1034 | track_pfn_insert(vma, prot: &pgprot, pfn); |
1035 | |
1036 | insert_pfn_pud(vma, addr, pud: vmf->pud, pfn, write); |
1037 | return VM_FAULT_NOPAGE; |
1038 | } |
1039 | EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); |
1040 | #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ |
1041 | |
1042 | static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, |
1043 | pmd_t *pmd, bool write) |
1044 | { |
1045 | pmd_t _pmd; |
1046 | |
1047 | _pmd = pmd_mkyoung(pmd: *pmd); |
1048 | if (write) |
1049 | _pmd = pmd_mkdirty(pmd: _pmd); |
1050 | if (pmdp_set_access_flags(vma, address: addr & HPAGE_PMD_MASK, |
1051 | pmdp: pmd, entry: _pmd, dirty: write)) |
1052 | update_mmu_cache_pmd(vma, addr, pmd); |
1053 | } |
1054 | |
1055 | struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, |
1056 | pmd_t *pmd, int flags, struct dev_pagemap **pgmap) |
1057 | { |
1058 | unsigned long pfn = pmd_pfn(pmd: *pmd); |
1059 | struct mm_struct *mm = vma->vm_mm; |
1060 | struct page *page; |
1061 | int ret; |
1062 | |
1063 | assert_spin_locked(pmd_lockptr(mm, pmd)); |
1064 | |
1065 | if (flags & FOLL_WRITE && !pmd_write(pmd: *pmd)) |
1066 | return NULL; |
1067 | |
1068 | if (pmd_present(pmd: *pmd) && pmd_devmap(pmd: *pmd)) |
1069 | /* pass */; |
1070 | else |
1071 | return NULL; |
1072 | |
1073 | if (flags & FOLL_TOUCH) |
1074 | touch_pmd(vma, addr, pmd, write: flags & FOLL_WRITE); |
1075 | |
1076 | /* |
1077 | * device mapped pages can only be returned if the |
1078 | * caller will manage the page reference count. |
1079 | */ |
1080 | if (!(flags & (FOLL_GET | FOLL_PIN))) |
1081 | return ERR_PTR(error: -EEXIST); |
1082 | |
1083 | pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; |
1084 | *pgmap = get_dev_pagemap(pfn, pgmap: *pgmap); |
1085 | if (!*pgmap) |
1086 | return ERR_PTR(error: -EFAULT); |
1087 | page = pfn_to_page(pfn); |
1088 | ret = try_grab_page(page, flags); |
1089 | if (ret) |
1090 | page = ERR_PTR(error: ret); |
1091 | |
1092 | return page; |
1093 | } |
1094 | |
1095 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
1096 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, |
1097 | struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) |
1098 | { |
1099 | spinlock_t *dst_ptl, *src_ptl; |
1100 | struct page *src_page; |
1101 | pmd_t pmd; |
1102 | pgtable_t pgtable = NULL; |
1103 | int ret = -ENOMEM; |
1104 | |
1105 | /* Skip if can be re-fill on fault */ |
1106 | if (!vma_is_anonymous(vma: dst_vma)) |
1107 | return 0; |
1108 | |
1109 | pgtable = pte_alloc_one(dst_mm); |
1110 | if (unlikely(!pgtable)) |
1111 | goto out; |
1112 | |
1113 | dst_ptl = pmd_lock(mm: dst_mm, pmd: dst_pmd); |
1114 | src_ptl = pmd_lockptr(mm: src_mm, pmd: src_pmd); |
1115 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); |
1116 | |
1117 | ret = -EAGAIN; |
1118 | pmd = *src_pmd; |
1119 | |
1120 | #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION |
1121 | if (unlikely(is_swap_pmd(pmd))) { |
1122 | swp_entry_t entry = pmd_to_swp_entry(pmd); |
1123 | |
1124 | VM_BUG_ON(!is_pmd_migration_entry(pmd)); |
1125 | if (!is_readable_migration_entry(entry)) { |
1126 | entry = make_readable_migration_entry( |
1127 | offset: swp_offset(entry)); |
1128 | pmd = swp_entry_to_pmd(entry); |
1129 | if (pmd_swp_soft_dirty(pmd: *src_pmd)) |
1130 | pmd = pmd_swp_mksoft_dirty(pmd); |
1131 | if (pmd_swp_uffd_wp(pmd: *src_pmd)) |
1132 | pmd = pmd_swp_mkuffd_wp(pmd); |
1133 | set_pmd_at(mm: src_mm, addr, pmdp: src_pmd, pmd); |
1134 | } |
1135 | add_mm_counter(mm: dst_mm, member: MM_ANONPAGES, HPAGE_PMD_NR); |
1136 | mm_inc_nr_ptes(mm: dst_mm); |
1137 | pgtable_trans_huge_deposit(mm: dst_mm, pmdp: dst_pmd, pgtable); |
1138 | if (!userfaultfd_wp(vma: dst_vma)) |
1139 | pmd = pmd_swp_clear_uffd_wp(pmd); |
1140 | set_pmd_at(mm: dst_mm, addr, pmdp: dst_pmd, pmd); |
1141 | ret = 0; |
1142 | goto out_unlock; |
1143 | } |
1144 | #endif |
1145 | |
1146 | if (unlikely(!pmd_trans_huge(pmd))) { |
1147 | pte_free(mm: dst_mm, pte_page: pgtable); |
1148 | goto out_unlock; |
1149 | } |
1150 | /* |
1151 | * When page table lock is held, the huge zero pmd should not be |
1152 | * under splitting since we don't split the page itself, only pmd to |
1153 | * a page table. |
1154 | */ |
1155 | if (is_huge_zero_pmd(pmd)) { |
1156 | /* |
1157 | * get_huge_zero_page() will never allocate a new page here, |
1158 | * since we already have a zero page to copy. It just takes a |
1159 | * reference. |
1160 | */ |
1161 | mm_get_huge_zero_page(mm: dst_mm); |
1162 | goto out_zero_page; |
1163 | } |
1164 | |
1165 | src_page = pmd_page(pmd); |
1166 | VM_BUG_ON_PAGE(!PageHead(src_page), src_page); |
1167 | |
1168 | get_page(page: src_page); |
1169 | if (unlikely(page_try_dup_anon_rmap(src_page, true, src_vma))) { |
1170 | /* Page maybe pinned: split and retry the fault on PTEs. */ |
1171 | put_page(page: src_page); |
1172 | pte_free(mm: dst_mm, pte_page: pgtable); |
1173 | spin_unlock(lock: src_ptl); |
1174 | spin_unlock(lock: dst_ptl); |
1175 | __split_huge_pmd(vma: src_vma, pmd: src_pmd, address: addr, freeze: false, NULL); |
1176 | return -EAGAIN; |
1177 | } |
1178 | add_mm_counter(mm: dst_mm, member: MM_ANONPAGES, HPAGE_PMD_NR); |
1179 | out_zero_page: |
1180 | mm_inc_nr_ptes(mm: dst_mm); |
1181 | pgtable_trans_huge_deposit(mm: dst_mm, pmdp: dst_pmd, pgtable); |
1182 | pmdp_set_wrprotect(mm: src_mm, addr, pmdp: src_pmd); |
1183 | if (!userfaultfd_wp(vma: dst_vma)) |
1184 | pmd = pmd_clear_uffd_wp(pmd); |
1185 | pmd = pmd_mkold(pmd: pmd_wrprotect(pmd)); |
1186 | set_pmd_at(mm: dst_mm, addr, pmdp: dst_pmd, pmd); |
1187 | |
1188 | ret = 0; |
1189 | out_unlock: |
1190 | spin_unlock(lock: src_ptl); |
1191 | spin_unlock(lock: dst_ptl); |
1192 | out: |
1193 | return ret; |
1194 | } |
1195 | |
1196 | #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD |
1197 | static void touch_pud(struct vm_area_struct *vma, unsigned long addr, |
1198 | pud_t *pud, bool write) |
1199 | { |
1200 | pud_t _pud; |
1201 | |
1202 | _pud = pud_mkyoung(pud: *pud); |
1203 | if (write) |
1204 | _pud = pud_mkdirty(pud: _pud); |
1205 | if (pudp_set_access_flags(vma, address: addr & HPAGE_PUD_MASK, |
1206 | pudp: pud, entry: _pud, dirty: write)) |
1207 | update_mmu_cache_pud(vma, addr, pud); |
1208 | } |
1209 | |
1210 | struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, |
1211 | pud_t *pud, int flags, struct dev_pagemap **pgmap) |
1212 | { |
1213 | unsigned long pfn = pud_pfn(pud: *pud); |
1214 | struct mm_struct *mm = vma->vm_mm; |
1215 | struct page *page; |
1216 | int ret; |
1217 | |
1218 | assert_spin_locked(pud_lockptr(mm, pud)); |
1219 | |
1220 | if (flags & FOLL_WRITE && !pud_write(pud: *pud)) |
1221 | return NULL; |
1222 | |
1223 | if (pud_present(pud: *pud) && pud_devmap(pud: *pud)) |
1224 | /* pass */; |
1225 | else |
1226 | return NULL; |
1227 | |
1228 | if (flags & FOLL_TOUCH) |
1229 | touch_pud(vma, addr, pud, write: flags & FOLL_WRITE); |
1230 | |
1231 | /* |
1232 | * device mapped pages can only be returned if the |
1233 | * caller will manage the page reference count. |
1234 | * |
1235 | * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here: |
1236 | */ |
1237 | if (!(flags & (FOLL_GET | FOLL_PIN))) |
1238 | return ERR_PTR(error: -EEXIST); |
1239 | |
1240 | pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; |
1241 | *pgmap = get_dev_pagemap(pfn, pgmap: *pgmap); |
1242 | if (!*pgmap) |
1243 | return ERR_PTR(error: -EFAULT); |
1244 | page = pfn_to_page(pfn); |
1245 | |
1246 | ret = try_grab_page(page, flags); |
1247 | if (ret) |
1248 | page = ERR_PTR(error: ret); |
1249 | |
1250 | return page; |
1251 | } |
1252 | |
1253 | int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
1254 | pud_t *dst_pud, pud_t *src_pud, unsigned long addr, |
1255 | struct vm_area_struct *vma) |
1256 | { |
1257 | spinlock_t *dst_ptl, *src_ptl; |
1258 | pud_t pud; |
1259 | int ret; |
1260 | |
1261 | dst_ptl = pud_lock(mm: dst_mm, pud: dst_pud); |
1262 | src_ptl = pud_lockptr(mm: src_mm, pud: src_pud); |
1263 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); |
1264 | |
1265 | ret = -EAGAIN; |
1266 | pud = *src_pud; |
1267 | if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) |
1268 | goto out_unlock; |
1269 | |
1270 | /* |
1271 | * When page table lock is held, the huge zero pud should not be |
1272 | * under splitting since we don't split the page itself, only pud to |
1273 | * a page table. |
1274 | */ |
1275 | if (is_huge_zero_pud(pud)) { |
1276 | /* No huge zero pud yet */ |
1277 | } |
1278 | |
1279 | /* |
1280 | * TODO: once we support anonymous pages, use page_try_dup_anon_rmap() |
1281 | * and split if duplicating fails. |
1282 | */ |
1283 | pudp_set_wrprotect(mm: src_mm, address: addr, pudp: src_pud); |
1284 | pud = pud_mkold(pud: pud_wrprotect(pud)); |
1285 | set_pud_at(mm: dst_mm, addr, pudp: dst_pud, pud); |
1286 | |
1287 | ret = 0; |
1288 | out_unlock: |
1289 | spin_unlock(lock: src_ptl); |
1290 | spin_unlock(lock: dst_ptl); |
1291 | return ret; |
1292 | } |
1293 | |
1294 | void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) |
1295 | { |
1296 | bool write = vmf->flags & FAULT_FLAG_WRITE; |
1297 | |
1298 | vmf->ptl = pud_lock(mm: vmf->vma->vm_mm, pud: vmf->pud); |
1299 | if (unlikely(!pud_same(*vmf->pud, orig_pud))) |
1300 | goto unlock; |
1301 | |
1302 | touch_pud(vma: vmf->vma, addr: vmf->address, pud: vmf->pud, write); |
1303 | unlock: |
1304 | spin_unlock(lock: vmf->ptl); |
1305 | } |
1306 | #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ |
1307 | |
1308 | void huge_pmd_set_accessed(struct vm_fault *vmf) |
1309 | { |
1310 | bool write = vmf->flags & FAULT_FLAG_WRITE; |
1311 | |
1312 | vmf->ptl = pmd_lock(mm: vmf->vma->vm_mm, pmd: vmf->pmd); |
1313 | if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) |
1314 | goto unlock; |
1315 | |
1316 | touch_pmd(vma: vmf->vma, addr: vmf->address, pmd: vmf->pmd, write); |
1317 | |
1318 | unlock: |
1319 | spin_unlock(lock: vmf->ptl); |
1320 | } |
1321 | |
1322 | vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) |
1323 | { |
1324 | const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; |
1325 | struct vm_area_struct *vma = vmf->vma; |
1326 | struct folio *folio; |
1327 | struct page *page; |
1328 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
1329 | pmd_t orig_pmd = vmf->orig_pmd; |
1330 | |
1331 | vmf->ptl = pmd_lockptr(mm: vma->vm_mm, pmd: vmf->pmd); |
1332 | VM_BUG_ON_VMA(!vma->anon_vma, vma); |
1333 | |
1334 | if (is_huge_zero_pmd(pmd: orig_pmd)) |
1335 | goto fallback; |
1336 | |
1337 | spin_lock(lock: vmf->ptl); |
1338 | |
1339 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { |
1340 | spin_unlock(lock: vmf->ptl); |
1341 | return 0; |
1342 | } |
1343 | |
1344 | page = pmd_page(orig_pmd); |
1345 | folio = page_folio(page); |
1346 | VM_BUG_ON_PAGE(!PageHead(page), page); |
1347 | |
1348 | /* Early check when only holding the PT lock. */ |
1349 | if (PageAnonExclusive(page)) |
1350 | goto reuse; |
1351 | |
1352 | if (!folio_trylock(folio)) { |
1353 | folio_get(folio); |
1354 | spin_unlock(lock: vmf->ptl); |
1355 | folio_lock(folio); |
1356 | spin_lock(lock: vmf->ptl); |
1357 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { |
1358 | spin_unlock(lock: vmf->ptl); |
1359 | folio_unlock(folio); |
1360 | folio_put(folio); |
1361 | return 0; |
1362 | } |
1363 | folio_put(folio); |
1364 | } |
1365 | |
1366 | /* Recheck after temporarily dropping the PT lock. */ |
1367 | if (PageAnonExclusive(page)) { |
1368 | folio_unlock(folio); |
1369 | goto reuse; |
1370 | } |
1371 | |
1372 | /* |
1373 | * See do_wp_page(): we can only reuse the folio exclusively if |
1374 | * there are no additional references. Note that we always drain |
1375 | * the LRU cache immediately after adding a THP. |
1376 | */ |
1377 | if (folio_ref_count(folio) > |
1378 | 1 + folio_test_swapcache(folio) * folio_nr_pages(folio)) |
1379 | goto unlock_fallback; |
1380 | if (folio_test_swapcache(folio)) |
1381 | folio_free_swap(folio); |
1382 | if (folio_ref_count(folio) == 1) { |
1383 | pmd_t entry; |
1384 | |
1385 | folio_move_anon_rmap(folio, vma); |
1386 | SetPageAnonExclusive(page); |
1387 | folio_unlock(folio); |
1388 | reuse: |
1389 | if (unlikely(unshare)) { |
1390 | spin_unlock(lock: vmf->ptl); |
1391 | return 0; |
1392 | } |
1393 | entry = pmd_mkyoung(pmd: orig_pmd); |
1394 | entry = maybe_pmd_mkwrite(pmd: pmd_mkdirty(pmd: entry), vma); |
1395 | if (pmdp_set_access_flags(vma, address: haddr, pmdp: vmf->pmd, entry, dirty: 1)) |
1396 | update_mmu_cache_pmd(vma, addr: vmf->address, pmd: vmf->pmd); |
1397 | spin_unlock(lock: vmf->ptl); |
1398 | return 0; |
1399 | } |
1400 | |
1401 | unlock_fallback: |
1402 | folio_unlock(folio); |
1403 | spin_unlock(lock: vmf->ptl); |
1404 | fallback: |
1405 | __split_huge_pmd(vma, pmd: vmf->pmd, address: vmf->address, freeze: false, NULL); |
1406 | return VM_FAULT_FALLBACK; |
1407 | } |
1408 | |
1409 | static inline bool can_change_pmd_writable(struct vm_area_struct *vma, |
1410 | unsigned long addr, pmd_t pmd) |
1411 | { |
1412 | struct page *page; |
1413 | |
1414 | if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) |
1415 | return false; |
1416 | |
1417 | /* Don't touch entries that are not even readable (NUMA hinting). */ |
1418 | if (pmd_protnone(pmd)) |
1419 | return false; |
1420 | |
1421 | /* Do we need write faults for softdirty tracking? */ |
1422 | if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd)) |
1423 | return false; |
1424 | |
1425 | /* Do we need write faults for uffd-wp tracking? */ |
1426 | if (userfaultfd_huge_pmd_wp(vma, pmd)) |
1427 | return false; |
1428 | |
1429 | if (!(vma->vm_flags & VM_SHARED)) { |
1430 | /* See can_change_pte_writable(). */ |
1431 | page = vm_normal_page_pmd(vma, addr, pmd); |
1432 | return page && PageAnon(page) && PageAnonExclusive(page); |
1433 | } |
1434 | |
1435 | /* See can_change_pte_writable(). */ |
1436 | return pmd_dirty(pmd); |
1437 | } |
1438 | |
1439 | /* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */ |
1440 | static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page, |
1441 | struct vm_area_struct *vma, |
1442 | unsigned int flags) |
1443 | { |
1444 | /* If the pmd is writable, we can write to the page. */ |
1445 | if (pmd_write(pmd)) |
1446 | return true; |
1447 | |
1448 | /* Maybe FOLL_FORCE is set to override it? */ |
1449 | if (!(flags & FOLL_FORCE)) |
1450 | return false; |
1451 | |
1452 | /* But FOLL_FORCE has no effect on shared mappings */ |
1453 | if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED)) |
1454 | return false; |
1455 | |
1456 | /* ... or read-only private ones */ |
1457 | if (!(vma->vm_flags & VM_MAYWRITE)) |
1458 | return false; |
1459 | |
1460 | /* ... or already writable ones that just need to take a write fault */ |
1461 | if (vma->vm_flags & VM_WRITE) |
1462 | return false; |
1463 | |
1464 | /* |
1465 | * See can_change_pte_writable(): we broke COW and could map the page |
1466 | * writable if we have an exclusive anonymous page ... |
1467 | */ |
1468 | if (!page || !PageAnon(page) || !PageAnonExclusive(page)) |
1469 | return false; |
1470 | |
1471 | /* ... and a write-fault isn't required for other reasons. */ |
1472 | if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd)) |
1473 | return false; |
1474 | return !userfaultfd_huge_pmd_wp(vma, pmd); |
1475 | } |
1476 | |
1477 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, |
1478 | unsigned long addr, |
1479 | pmd_t *pmd, |
1480 | unsigned int flags) |
1481 | { |
1482 | struct mm_struct *mm = vma->vm_mm; |
1483 | struct page *page; |
1484 | int ret; |
1485 | |
1486 | assert_spin_locked(pmd_lockptr(mm, pmd)); |
1487 | |
1488 | page = pmd_page(*pmd); |
1489 | VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); |
1490 | |
1491 | if ((flags & FOLL_WRITE) && |
1492 | !can_follow_write_pmd(pmd: *pmd, page, vma, flags)) |
1493 | return NULL; |
1494 | |
1495 | /* Avoid dumping huge zero page */ |
1496 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(pmd: *pmd)) |
1497 | return ERR_PTR(error: -EFAULT); |
1498 | |
1499 | if (pmd_protnone(pmd: *pmd) && !gup_can_follow_protnone(vma, flags)) |
1500 | return NULL; |
1501 | |
1502 | if (!pmd_write(pmd: *pmd) && gup_must_unshare(vma, flags, page)) |
1503 | return ERR_PTR(error: -EMLINK); |
1504 | |
1505 | VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) && |
1506 | !PageAnonExclusive(page), page); |
1507 | |
1508 | ret = try_grab_page(page, flags); |
1509 | if (ret) |
1510 | return ERR_PTR(error: ret); |
1511 | |
1512 | if (flags & FOLL_TOUCH) |
1513 | touch_pmd(vma, addr, pmd, write: flags & FOLL_WRITE); |
1514 | |
1515 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
1516 | VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); |
1517 | |
1518 | return page; |
1519 | } |
1520 | |
1521 | /* NUMA hinting page fault entry point for trans huge pmds */ |
1522 | vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) |
1523 | { |
1524 | struct vm_area_struct *vma = vmf->vma; |
1525 | pmd_t oldpmd = vmf->orig_pmd; |
1526 | pmd_t pmd; |
1527 | struct folio *folio; |
1528 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
1529 | int nid = NUMA_NO_NODE; |
1530 | int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK); |
1531 | bool migrated = false, writable = false; |
1532 | int flags = 0; |
1533 | |
1534 | vmf->ptl = pmd_lock(mm: vma->vm_mm, pmd: vmf->pmd); |
1535 | if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { |
1536 | spin_unlock(lock: vmf->ptl); |
1537 | goto out; |
1538 | } |
1539 | |
1540 | pmd = pmd_modify(pmd: oldpmd, newprot: vma->vm_page_prot); |
1541 | |
1542 | /* |
1543 | * Detect now whether the PMD could be writable; this information |
1544 | * is only valid while holding the PT lock. |
1545 | */ |
1546 | writable = pmd_write(pmd); |
1547 | if (!writable && vma_wants_manual_pte_write_upgrade(vma) && |
1548 | can_change_pmd_writable(vma, addr: vmf->address, pmd)) |
1549 | writable = true; |
1550 | |
1551 | folio = vm_normal_folio_pmd(vma, addr: haddr, pmd); |
1552 | if (!folio) |
1553 | goto out_map; |
1554 | |
1555 | /* See similar comment in do_numa_page for explanation */ |
1556 | if (!writable) |
1557 | flags |= TNF_NO_GROUP; |
1558 | |
1559 | nid = folio_nid(folio); |
1560 | /* |
1561 | * For memory tiering mode, cpupid of slow memory page is used |
1562 | * to record page access time. So use default value. |
1563 | */ |
1564 | if (node_is_toptier(node: nid)) |
1565 | last_cpupid = folio_last_cpupid(folio); |
1566 | target_nid = numa_migrate_prep(folio, vma, addr: haddr, page_nid: nid, flags: &flags); |
1567 | if (target_nid == NUMA_NO_NODE) { |
1568 | folio_put(folio); |
1569 | goto out_map; |
1570 | } |
1571 | |
1572 | spin_unlock(lock: vmf->ptl); |
1573 | writable = false; |
1574 | |
1575 | migrated = migrate_misplaced_folio(folio, vma, node: target_nid); |
1576 | if (migrated) { |
1577 | flags |= TNF_MIGRATED; |
1578 | nid = target_nid; |
1579 | } else { |
1580 | flags |= TNF_MIGRATE_FAIL; |
1581 | vmf->ptl = pmd_lock(mm: vma->vm_mm, pmd: vmf->pmd); |
1582 | if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { |
1583 | spin_unlock(lock: vmf->ptl); |
1584 | goto out; |
1585 | } |
1586 | goto out_map; |
1587 | } |
1588 | |
1589 | out: |
1590 | if (nid != NUMA_NO_NODE) |
1591 | task_numa_fault(last_node: last_cpupid, node: nid, HPAGE_PMD_NR, flags); |
1592 | |
1593 | return 0; |
1594 | |
1595 | out_map: |
1596 | /* Restore the PMD */ |
1597 | pmd = pmd_modify(pmd: oldpmd, newprot: vma->vm_page_prot); |
1598 | pmd = pmd_mkyoung(pmd); |
1599 | if (writable) |
1600 | pmd = pmd_mkwrite(pmd, vma); |
1601 | set_pmd_at(mm: vma->vm_mm, addr: haddr, pmdp: vmf->pmd, pmd); |
1602 | update_mmu_cache_pmd(vma, addr: vmf->address, pmd: vmf->pmd); |
1603 | spin_unlock(lock: vmf->ptl); |
1604 | goto out; |
1605 | } |
1606 | |
1607 | /* |
1608 | * Return true if we do MADV_FREE successfully on entire pmd page. |
1609 | * Otherwise, return false. |
1610 | */ |
1611 | bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
1612 | pmd_t *pmd, unsigned long addr, unsigned long next) |
1613 | { |
1614 | spinlock_t *ptl; |
1615 | pmd_t orig_pmd; |
1616 | struct folio *folio; |
1617 | struct mm_struct *mm = tlb->mm; |
1618 | bool ret = false; |
1619 | |
1620 | tlb_change_page_size(tlb, HPAGE_PMD_SIZE); |
1621 | |
1622 | ptl = pmd_trans_huge_lock(pmd, vma); |
1623 | if (!ptl) |
1624 | goto out_unlocked; |
1625 | |
1626 | orig_pmd = *pmd; |
1627 | if (is_huge_zero_pmd(pmd: orig_pmd)) |
1628 | goto out; |
1629 | |
1630 | if (unlikely(!pmd_present(orig_pmd))) { |
1631 | VM_BUG_ON(thp_migration_supported() && |
1632 | !is_pmd_migration_entry(orig_pmd)); |
1633 | goto out; |
1634 | } |
1635 | |
1636 | folio = pfn_folio(pfn: pmd_pfn(pmd: orig_pmd)); |
1637 | /* |
1638 | * If other processes are mapping this folio, we couldn't discard |
1639 | * the folio unless they all do MADV_FREE so let's skip the folio. |
1640 | */ |
1641 | if (folio_estimated_sharers(folio) != 1) |
1642 | goto out; |
1643 | |
1644 | if (!folio_trylock(folio)) |
1645 | goto out; |
1646 | |
1647 | /* |
1648 | * If user want to discard part-pages of THP, split it so MADV_FREE |
1649 | * will deactivate only them. |
1650 | */ |
1651 | if (next - addr != HPAGE_PMD_SIZE) { |
1652 | folio_get(folio); |
1653 | spin_unlock(lock: ptl); |
1654 | split_folio(folio); |
1655 | folio_unlock(folio); |
1656 | folio_put(folio); |
1657 | goto out_unlocked; |
1658 | } |
1659 | |
1660 | if (folio_test_dirty(folio)) |
1661 | folio_clear_dirty(folio); |
1662 | folio_unlock(folio); |
1663 | |
1664 | if (pmd_young(pmd: orig_pmd) || pmd_dirty(pmd: orig_pmd)) { |
1665 | pmdp_invalidate(vma, address: addr, pmdp: pmd); |
1666 | orig_pmd = pmd_mkold(pmd: orig_pmd); |
1667 | orig_pmd = pmd_mkclean(pmd: orig_pmd); |
1668 | |
1669 | set_pmd_at(mm, addr, pmdp: pmd, pmd: orig_pmd); |
1670 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); |
1671 | } |
1672 | |
1673 | folio_mark_lazyfree(folio); |
1674 | ret = true; |
1675 | out: |
1676 | spin_unlock(lock: ptl); |
1677 | out_unlocked: |
1678 | return ret; |
1679 | } |
1680 | |
1681 | static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) |
1682 | { |
1683 | pgtable_t pgtable; |
1684 | |
1685 | pgtable = pgtable_trans_huge_withdraw(mm, pmdp: pmd); |
1686 | pte_free(mm, pte_page: pgtable); |
1687 | mm_dec_nr_ptes(mm); |
1688 | } |
1689 | |
1690 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
1691 | pmd_t *pmd, unsigned long addr) |
1692 | { |
1693 | pmd_t orig_pmd; |
1694 | spinlock_t *ptl; |
1695 | |
1696 | tlb_change_page_size(tlb, HPAGE_PMD_SIZE); |
1697 | |
1698 | ptl = __pmd_trans_huge_lock(pmd, vma); |
1699 | if (!ptl) |
1700 | return 0; |
1701 | /* |
1702 | * For architectures like ppc64 we look at deposited pgtable |
1703 | * when calling pmdp_huge_get_and_clear. So do the |
1704 | * pgtable_trans_huge_withdraw after finishing pmdp related |
1705 | * operations. |
1706 | */ |
1707 | orig_pmd = pmdp_huge_get_and_clear_full(vma, address: addr, pmdp: pmd, |
1708 | full: tlb->fullmm); |
1709 | arch_check_zapped_pmd(vma, pmd: orig_pmd); |
1710 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); |
1711 | if (vma_is_special_huge(vma)) { |
1712 | if (arch_needs_pgtable_deposit()) |
1713 | zap_deposited_table(mm: tlb->mm, pmd); |
1714 | spin_unlock(lock: ptl); |
1715 | } else if (is_huge_zero_pmd(pmd: orig_pmd)) { |
1716 | zap_deposited_table(mm: tlb->mm, pmd); |
1717 | spin_unlock(lock: ptl); |
1718 | } else { |
1719 | struct page *page = NULL; |
1720 | int flush_needed = 1; |
1721 | |
1722 | if (pmd_present(pmd: orig_pmd)) { |
1723 | page = pmd_page(orig_pmd); |
1724 | page_remove_rmap(page, vma, compound: true); |
1725 | VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); |
1726 | VM_BUG_ON_PAGE(!PageHead(page), page); |
1727 | } else if (thp_migration_supported()) { |
1728 | swp_entry_t entry; |
1729 | |
1730 | VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); |
1731 | entry = pmd_to_swp_entry(pmd: orig_pmd); |
1732 | page = pfn_swap_entry_to_page(entry); |
1733 | flush_needed = 0; |
1734 | } else |
1735 | WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!" ); |
1736 | |
1737 | if (PageAnon(page)) { |
1738 | zap_deposited_table(mm: tlb->mm, pmd); |
1739 | add_mm_counter(mm: tlb->mm, member: MM_ANONPAGES, value: -HPAGE_PMD_NR); |
1740 | } else { |
1741 | if (arch_needs_pgtable_deposit()) |
1742 | zap_deposited_table(mm: tlb->mm, pmd); |
1743 | add_mm_counter(mm: tlb->mm, member: mm_counter_file(page), value: -HPAGE_PMD_NR); |
1744 | } |
1745 | |
1746 | spin_unlock(lock: ptl); |
1747 | if (flush_needed) |
1748 | tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); |
1749 | } |
1750 | return 1; |
1751 | } |
1752 | |
1753 | #ifndef pmd_move_must_withdraw |
1754 | static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, |
1755 | spinlock_t *old_pmd_ptl, |
1756 | struct vm_area_struct *vma) |
1757 | { |
1758 | /* |
1759 | * With split pmd lock we also need to move preallocated |
1760 | * PTE page table if new_pmd is on different PMD page table. |
1761 | * |
1762 | * We also don't deposit and withdraw tables for file pages. |
1763 | */ |
1764 | return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); |
1765 | } |
1766 | #endif |
1767 | |
1768 | static pmd_t move_soft_dirty_pmd(pmd_t pmd) |
1769 | { |
1770 | #ifdef CONFIG_MEM_SOFT_DIRTY |
1771 | if (unlikely(is_pmd_migration_entry(pmd))) |
1772 | pmd = pmd_swp_mksoft_dirty(pmd); |
1773 | else if (pmd_present(pmd)) |
1774 | pmd = pmd_mksoft_dirty(pmd); |
1775 | #endif |
1776 | return pmd; |
1777 | } |
1778 | |
1779 | bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, |
1780 | unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) |
1781 | { |
1782 | spinlock_t *old_ptl, *new_ptl; |
1783 | pmd_t pmd; |
1784 | struct mm_struct *mm = vma->vm_mm; |
1785 | bool force_flush = false; |
1786 | |
1787 | /* |
1788 | * The destination pmd shouldn't be established, free_pgtables() |
1789 | * should have released it; but move_page_tables() might have already |
1790 | * inserted a page table, if racing against shmem/file collapse. |
1791 | */ |
1792 | if (!pmd_none(pmd: *new_pmd)) { |
1793 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); |
1794 | return false; |
1795 | } |
1796 | |
1797 | /* |
1798 | * We don't have to worry about the ordering of src and dst |
1799 | * ptlocks because exclusive mmap_lock prevents deadlock. |
1800 | */ |
1801 | old_ptl = __pmd_trans_huge_lock(pmd: old_pmd, vma); |
1802 | if (old_ptl) { |
1803 | new_ptl = pmd_lockptr(mm, pmd: new_pmd); |
1804 | if (new_ptl != old_ptl) |
1805 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); |
1806 | pmd = pmdp_huge_get_and_clear(mm, addr: old_addr, pmdp: old_pmd); |
1807 | if (pmd_present(pmd)) |
1808 | force_flush = true; |
1809 | VM_BUG_ON(!pmd_none(*new_pmd)); |
1810 | |
1811 | if (pmd_move_must_withdraw(new_pmd_ptl: new_ptl, old_pmd_ptl: old_ptl, vma)) { |
1812 | pgtable_t pgtable; |
1813 | pgtable = pgtable_trans_huge_withdraw(mm, pmdp: old_pmd); |
1814 | pgtable_trans_huge_deposit(mm, pmdp: new_pmd, pgtable); |
1815 | } |
1816 | pmd = move_soft_dirty_pmd(pmd); |
1817 | set_pmd_at(mm, addr: new_addr, pmdp: new_pmd, pmd); |
1818 | if (force_flush) |
1819 | flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); |
1820 | if (new_ptl != old_ptl) |
1821 | spin_unlock(lock: new_ptl); |
1822 | spin_unlock(lock: old_ptl); |
1823 | return true; |
1824 | } |
1825 | return false; |
1826 | } |
1827 | |
1828 | /* |
1829 | * Returns |
1830 | * - 0 if PMD could not be locked |
1831 | * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary |
1832 | * or if prot_numa but THP migration is not supported |
1833 | * - HPAGE_PMD_NR if protections changed and TLB flush necessary |
1834 | */ |
1835 | int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
1836 | pmd_t *pmd, unsigned long addr, pgprot_t newprot, |
1837 | unsigned long cp_flags) |
1838 | { |
1839 | struct mm_struct *mm = vma->vm_mm; |
1840 | spinlock_t *ptl; |
1841 | pmd_t oldpmd, entry; |
1842 | bool prot_numa = cp_flags & MM_CP_PROT_NUMA; |
1843 | bool uffd_wp = cp_flags & MM_CP_UFFD_WP; |
1844 | bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; |
1845 | int ret = 1; |
1846 | |
1847 | tlb_change_page_size(tlb, HPAGE_PMD_SIZE); |
1848 | |
1849 | if (prot_numa && !thp_migration_supported()) |
1850 | return 1; |
1851 | |
1852 | ptl = __pmd_trans_huge_lock(pmd, vma); |
1853 | if (!ptl) |
1854 | return 0; |
1855 | |
1856 | #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION |
1857 | if (is_swap_pmd(pmd: *pmd)) { |
1858 | swp_entry_t entry = pmd_to_swp_entry(pmd: *pmd); |
1859 | struct folio *folio = page_folio(pfn_swap_entry_to_page(entry)); |
1860 | pmd_t newpmd; |
1861 | |
1862 | VM_BUG_ON(!is_pmd_migration_entry(*pmd)); |
1863 | if (is_writable_migration_entry(entry)) { |
1864 | /* |
1865 | * A protection check is difficult so |
1866 | * just be safe and disable write |
1867 | */ |
1868 | if (folio_test_anon(folio)) |
1869 | entry = make_readable_exclusive_migration_entry(offset: swp_offset(entry)); |
1870 | else |
1871 | entry = make_readable_migration_entry(offset: swp_offset(entry)); |
1872 | newpmd = swp_entry_to_pmd(entry); |
1873 | if (pmd_swp_soft_dirty(pmd: *pmd)) |
1874 | newpmd = pmd_swp_mksoft_dirty(pmd: newpmd); |
1875 | } else { |
1876 | newpmd = *pmd; |
1877 | } |
1878 | |
1879 | if (uffd_wp) |
1880 | newpmd = pmd_swp_mkuffd_wp(pmd: newpmd); |
1881 | else if (uffd_wp_resolve) |
1882 | newpmd = pmd_swp_clear_uffd_wp(pmd: newpmd); |
1883 | if (!pmd_same(pmd_a: *pmd, pmd_b: newpmd)) |
1884 | set_pmd_at(mm, addr, pmdp: pmd, pmd: newpmd); |
1885 | goto unlock; |
1886 | } |
1887 | #endif |
1888 | |
1889 | if (prot_numa) { |
1890 | struct folio *folio; |
1891 | bool toptier; |
1892 | /* |
1893 | * Avoid trapping faults against the zero page. The read-only |
1894 | * data is likely to be read-cached on the local CPU and |
1895 | * local/remote hits to the zero page are not interesting. |
1896 | */ |
1897 | if (is_huge_zero_pmd(pmd: *pmd)) |
1898 | goto unlock; |
1899 | |
1900 | if (pmd_protnone(pmd: *pmd)) |
1901 | goto unlock; |
1902 | |
1903 | folio = page_folio(pmd_page(*pmd)); |
1904 | toptier = node_is_toptier(node: folio_nid(folio)); |
1905 | /* |
1906 | * Skip scanning top tier node if normal numa |
1907 | * balancing is disabled |
1908 | */ |
1909 | if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && |
1910 | toptier) |
1911 | goto unlock; |
1912 | |
1913 | if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING && |
1914 | !toptier) |
1915 | folio_xchg_access_time(folio, |
1916 | time: jiffies_to_msecs(j: jiffies)); |
1917 | } |
1918 | /* |
1919 | * In case prot_numa, we are under mmap_read_lock(mm). It's critical |
1920 | * to not clear pmd intermittently to avoid race with MADV_DONTNEED |
1921 | * which is also under mmap_read_lock(mm): |
1922 | * |
1923 | * CPU0: CPU1: |
1924 | * change_huge_pmd(prot_numa=1) |
1925 | * pmdp_huge_get_and_clear_notify() |
1926 | * madvise_dontneed() |
1927 | * zap_pmd_range() |
1928 | * pmd_trans_huge(*pmd) == 0 (without ptl) |
1929 | * // skip the pmd |
1930 | * set_pmd_at(); |
1931 | * // pmd is re-established |
1932 | * |
1933 | * The race makes MADV_DONTNEED miss the huge pmd and don't clear it |
1934 | * which may break userspace. |
1935 | * |
1936 | * pmdp_invalidate_ad() is required to make sure we don't miss |
1937 | * dirty/young flags set by hardware. |
1938 | */ |
1939 | oldpmd = pmdp_invalidate_ad(vma, address: addr, pmdp: pmd); |
1940 | |
1941 | entry = pmd_modify(pmd: oldpmd, newprot); |
1942 | if (uffd_wp) |
1943 | entry = pmd_mkuffd_wp(pmd: entry); |
1944 | else if (uffd_wp_resolve) |
1945 | /* |
1946 | * Leave the write bit to be handled by PF interrupt |
1947 | * handler, then things like COW could be properly |
1948 | * handled. |
1949 | */ |
1950 | entry = pmd_clear_uffd_wp(pmd: entry); |
1951 | |
1952 | /* See change_pte_range(). */ |
1953 | if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(pmd: entry) && |
1954 | can_change_pmd_writable(vma, addr, pmd: entry)) |
1955 | entry = pmd_mkwrite(pmd: entry, vma); |
1956 | |
1957 | ret = HPAGE_PMD_NR; |
1958 | set_pmd_at(mm, addr, pmdp: pmd, pmd: entry); |
1959 | |
1960 | if (huge_pmd_needs_flush(oldpmd, newpmd: entry)) |
1961 | tlb_flush_pmd_range(tlb, address: addr, HPAGE_PMD_SIZE); |
1962 | unlock: |
1963 | spin_unlock(lock: ptl); |
1964 | return ret; |
1965 | } |
1966 | |
1967 | /* |
1968 | * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. |
1969 | * |
1970 | * Note that if it returns page table lock pointer, this routine returns without |
1971 | * unlocking page table lock. So callers must unlock it. |
1972 | */ |
1973 | spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) |
1974 | { |
1975 | spinlock_t *ptl; |
1976 | ptl = pmd_lock(mm: vma->vm_mm, pmd); |
1977 | if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || |
1978 | pmd_devmap(*pmd))) |
1979 | return ptl; |
1980 | spin_unlock(lock: ptl); |
1981 | return NULL; |
1982 | } |
1983 | |
1984 | /* |
1985 | * Returns page table lock pointer if a given pud maps a thp, NULL otherwise. |
1986 | * |
1987 | * Note that if it returns page table lock pointer, this routine returns without |
1988 | * unlocking page table lock. So callers must unlock it. |
1989 | */ |
1990 | spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) |
1991 | { |
1992 | spinlock_t *ptl; |
1993 | |
1994 | ptl = pud_lock(mm: vma->vm_mm, pud); |
1995 | if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) |
1996 | return ptl; |
1997 | spin_unlock(lock: ptl); |
1998 | return NULL; |
1999 | } |
2000 | |
2001 | #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD |
2002 | int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, |
2003 | pud_t *pud, unsigned long addr) |
2004 | { |
2005 | spinlock_t *ptl; |
2006 | |
2007 | ptl = __pud_trans_huge_lock(pud, vma); |
2008 | if (!ptl) |
2009 | return 0; |
2010 | |
2011 | pudp_huge_get_and_clear_full(vma, address: addr, pudp: pud, full: tlb->fullmm); |
2012 | tlb_remove_pud_tlb_entry(tlb, pud, addr); |
2013 | if (vma_is_special_huge(vma)) { |
2014 | spin_unlock(lock: ptl); |
2015 | /* No zero page support yet */ |
2016 | } else { |
2017 | /* No support for anonymous PUD pages yet */ |
2018 | BUG(); |
2019 | } |
2020 | return 1; |
2021 | } |
2022 | |
2023 | static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, |
2024 | unsigned long haddr) |
2025 | { |
2026 | VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); |
2027 | VM_BUG_ON_VMA(vma->vm_start > haddr, vma); |
2028 | VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); |
2029 | VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); |
2030 | |
2031 | count_vm_event(item: THP_SPLIT_PUD); |
2032 | |
2033 | pudp_huge_clear_flush(vma, address: haddr, pudp: pud); |
2034 | } |
2035 | |
2036 | void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, |
2037 | unsigned long address) |
2038 | { |
2039 | spinlock_t *ptl; |
2040 | struct mmu_notifier_range range; |
2041 | |
2042 | mmu_notifier_range_init(range: &range, event: MMU_NOTIFY_CLEAR, flags: 0, mm: vma->vm_mm, |
2043 | start: address & HPAGE_PUD_MASK, |
2044 | end: (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); |
2045 | mmu_notifier_invalidate_range_start(range: &range); |
2046 | ptl = pud_lock(mm: vma->vm_mm, pud); |
2047 | if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) |
2048 | goto out; |
2049 | __split_huge_pud_locked(vma, pud, haddr: range.start); |
2050 | |
2051 | out: |
2052 | spin_unlock(lock: ptl); |
2053 | mmu_notifier_invalidate_range_end(range: &range); |
2054 | } |
2055 | #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ |
2056 | |
2057 | static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, |
2058 | unsigned long haddr, pmd_t *pmd) |
2059 | { |
2060 | struct mm_struct *mm = vma->vm_mm; |
2061 | pgtable_t pgtable; |
2062 | pmd_t _pmd, old_pmd; |
2063 | unsigned long addr; |
2064 | pte_t *pte; |
2065 | int i; |
2066 | |
2067 | /* |
2068 | * Leave pmd empty until pte is filled note that it is fine to delay |
2069 | * notification until mmu_notifier_invalidate_range_end() as we are |
2070 | * replacing a zero pmd write protected page with a zero pte write |
2071 | * protected page. |
2072 | * |
2073 | * See Documentation/mm/mmu_notifier.rst |
2074 | */ |
2075 | old_pmd = pmdp_huge_clear_flush(vma, address: haddr, pmdp: pmd); |
2076 | |
2077 | pgtable = pgtable_trans_huge_withdraw(mm, pmdp: pmd); |
2078 | pmd_populate(mm, pmd: &_pmd, pte: pgtable); |
2079 | |
2080 | pte = pte_offset_map(pmd: &_pmd, addr: haddr); |
2081 | VM_BUG_ON(!pte); |
2082 | for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { |
2083 | pte_t entry; |
2084 | |
2085 | entry = pfn_pte(page_nr: my_zero_pfn(addr), pgprot: vma->vm_page_prot); |
2086 | entry = pte_mkspecial(pte: entry); |
2087 | if (pmd_uffd_wp(pmd: old_pmd)) |
2088 | entry = pte_mkuffd_wp(pte: entry); |
2089 | VM_BUG_ON(!pte_none(ptep_get(pte))); |
2090 | set_pte_at(mm, addr, pte, entry); |
2091 | pte++; |
2092 | } |
2093 | pte_unmap(pte: pte - 1); |
2094 | smp_wmb(); /* make pte visible before pmd */ |
2095 | pmd_populate(mm, pmd, pte: pgtable); |
2096 | } |
2097 | |
2098 | static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, |
2099 | unsigned long haddr, bool freeze) |
2100 | { |
2101 | struct mm_struct *mm = vma->vm_mm; |
2102 | struct page *page; |
2103 | pgtable_t pgtable; |
2104 | pmd_t old_pmd, _pmd; |
2105 | bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; |
2106 | bool anon_exclusive = false, dirty = false; |
2107 | unsigned long addr; |
2108 | pte_t *pte; |
2109 | int i; |
2110 | |
2111 | VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); |
2112 | VM_BUG_ON_VMA(vma->vm_start > haddr, vma); |
2113 | VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); |
2114 | VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) |
2115 | && !pmd_devmap(*pmd)); |
2116 | |
2117 | count_vm_event(item: THP_SPLIT_PMD); |
2118 | |
2119 | if (!vma_is_anonymous(vma)) { |
2120 | old_pmd = pmdp_huge_clear_flush(vma, address: haddr, pmdp: pmd); |
2121 | /* |
2122 | * We are going to unmap this huge page. So |
2123 | * just go ahead and zap it |
2124 | */ |
2125 | if (arch_needs_pgtable_deposit()) |
2126 | zap_deposited_table(mm, pmd); |
2127 | if (vma_is_special_huge(vma)) |
2128 | return; |
2129 | if (unlikely(is_pmd_migration_entry(old_pmd))) { |
2130 | swp_entry_t entry; |
2131 | |
2132 | entry = pmd_to_swp_entry(pmd: old_pmd); |
2133 | page = pfn_swap_entry_to_page(entry); |
2134 | } else { |
2135 | page = pmd_page(old_pmd); |
2136 | if (!PageDirty(page) && pmd_dirty(pmd: old_pmd)) |
2137 | set_page_dirty(page); |
2138 | if (!PageReferenced(page) && pmd_young(pmd: old_pmd)) |
2139 | SetPageReferenced(page); |
2140 | page_remove_rmap(page, vma, compound: true); |
2141 | put_page(page); |
2142 | } |
2143 | add_mm_counter(mm, member: mm_counter_file(page), value: -HPAGE_PMD_NR); |
2144 | return; |
2145 | } |
2146 | |
2147 | if (is_huge_zero_pmd(pmd: *pmd)) { |
2148 | /* |
2149 | * FIXME: Do we want to invalidate secondary mmu by calling |
2150 | * mmu_notifier_arch_invalidate_secondary_tlbs() see comments below |
2151 | * inside __split_huge_pmd() ? |
2152 | * |
2153 | * We are going from a zero huge page write protected to zero |
2154 | * small page also write protected so it does not seems useful |
2155 | * to invalidate secondary mmu at this time. |
2156 | */ |
2157 | return __split_huge_zero_page_pmd(vma, haddr, pmd); |
2158 | } |
2159 | |
2160 | /* |
2161 | * Up to this point the pmd is present and huge and userland has the |
2162 | * whole access to the hugepage during the split (which happens in |
2163 | * place). If we overwrite the pmd with the not-huge version pointing |
2164 | * to the pte here (which of course we could if all CPUs were bug |
2165 | * free), userland could trigger a small page size TLB miss on the |
2166 | * small sized TLB while the hugepage TLB entry is still established in |
2167 | * the huge TLB. Some CPU doesn't like that. |
2168 | * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum |
2169 | * 383 on page 105. Intel should be safe but is also warns that it's |
2170 | * only safe if the permission and cache attributes of the two entries |
2171 | * loaded in the two TLB is identical (which should be the case here). |
2172 | * But it is generally safer to never allow small and huge TLB entries |
2173 | * for the same virtual address to be loaded simultaneously. So instead |
2174 | * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the |
2175 | * current pmd notpresent (atomically because here the pmd_trans_huge |
2176 | * must remain set at all times on the pmd until the split is complete |
2177 | * for this pmd), then we flush the SMP TLB and finally we write the |
2178 | * non-huge version of the pmd entry with pmd_populate. |
2179 | */ |
2180 | old_pmd = pmdp_invalidate(vma, address: haddr, pmdp: pmd); |
2181 | |
2182 | pmd_migration = is_pmd_migration_entry(pmd: old_pmd); |
2183 | if (unlikely(pmd_migration)) { |
2184 | swp_entry_t entry; |
2185 | |
2186 | entry = pmd_to_swp_entry(pmd: old_pmd); |
2187 | page = pfn_swap_entry_to_page(entry); |
2188 | write = is_writable_migration_entry(entry); |
2189 | if (PageAnon(page)) |
2190 | anon_exclusive = is_readable_exclusive_migration_entry(entry); |
2191 | young = is_migration_entry_young(entry); |
2192 | dirty = is_migration_entry_dirty(entry); |
2193 | soft_dirty = pmd_swp_soft_dirty(pmd: old_pmd); |
2194 | uffd_wp = pmd_swp_uffd_wp(pmd: old_pmd); |
2195 | } else { |
2196 | page = pmd_page(old_pmd); |
2197 | if (pmd_dirty(pmd: old_pmd)) { |
2198 | dirty = true; |
2199 | SetPageDirty(page); |
2200 | } |
2201 | write = pmd_write(pmd: old_pmd); |
2202 | young = pmd_young(pmd: old_pmd); |
2203 | soft_dirty = pmd_soft_dirty(pmd: old_pmd); |
2204 | uffd_wp = pmd_uffd_wp(pmd: old_pmd); |
2205 | |
2206 | VM_BUG_ON_PAGE(!page_count(page), page); |
2207 | |
2208 | /* |
2209 | * Without "freeze", we'll simply split the PMD, propagating the |
2210 | * PageAnonExclusive() flag for each PTE by setting it for |
2211 | * each subpage -- no need to (temporarily) clear. |
2212 | * |
2213 | * With "freeze" we want to replace mapped pages by |
2214 | * migration entries right away. This is only possible if we |
2215 | * managed to clear PageAnonExclusive() -- see |
2216 | * set_pmd_migration_entry(). |
2217 | * |
2218 | * In case we cannot clear PageAnonExclusive(), split the PMD |
2219 | * only and let try_to_migrate_one() fail later. |
2220 | * |
2221 | * See page_try_share_anon_rmap(): invalidate PMD first. |
2222 | */ |
2223 | anon_exclusive = PageAnon(page) && PageAnonExclusive(page); |
2224 | if (freeze && anon_exclusive && page_try_share_anon_rmap(page)) |
2225 | freeze = false; |
2226 | if (!freeze) |
2227 | page_ref_add(page, HPAGE_PMD_NR - 1); |
2228 | } |
2229 | |
2230 | /* |
2231 | * Withdraw the table only after we mark the pmd entry invalid. |
2232 | * This's critical for some architectures (Power). |
2233 | */ |
2234 | pgtable = pgtable_trans_huge_withdraw(mm, pmdp: pmd); |
2235 | pmd_populate(mm, pmd: &_pmd, pte: pgtable); |
2236 | |
2237 | pte = pte_offset_map(pmd: &_pmd, addr: haddr); |
2238 | VM_BUG_ON(!pte); |
2239 | for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { |
2240 | pte_t entry; |
2241 | /* |
2242 | * Note that NUMA hinting access restrictions are not |
2243 | * transferred to avoid any possibility of altering |
2244 | * permissions across VMAs. |
2245 | */ |
2246 | if (freeze || pmd_migration) { |
2247 | swp_entry_t swp_entry; |
2248 | if (write) |
2249 | swp_entry = make_writable_migration_entry( |
2250 | page_to_pfn(page + i)); |
2251 | else if (anon_exclusive) |
2252 | swp_entry = make_readable_exclusive_migration_entry( |
2253 | page_to_pfn(page + i)); |
2254 | else |
2255 | swp_entry = make_readable_migration_entry( |
2256 | page_to_pfn(page + i)); |
2257 | if (young) |
2258 | swp_entry = make_migration_entry_young(entry: swp_entry); |
2259 | if (dirty) |
2260 | swp_entry = make_migration_entry_dirty(entry: swp_entry); |
2261 | entry = swp_entry_to_pte(entry: swp_entry); |
2262 | if (soft_dirty) |
2263 | entry = pte_swp_mksoft_dirty(pte: entry); |
2264 | if (uffd_wp) |
2265 | entry = pte_swp_mkuffd_wp(pte: entry); |
2266 | } else { |
2267 | entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); |
2268 | if (write) |
2269 | entry = pte_mkwrite(pte: entry, vma); |
2270 | if (anon_exclusive) |
2271 | SetPageAnonExclusive(page + i); |
2272 | if (!young) |
2273 | entry = pte_mkold(pte: entry); |
2274 | /* NOTE: this may set soft-dirty too on some archs */ |
2275 | if (dirty) |
2276 | entry = pte_mkdirty(pte: entry); |
2277 | if (soft_dirty) |
2278 | entry = pte_mksoft_dirty(pte: entry); |
2279 | if (uffd_wp) |
2280 | entry = pte_mkuffd_wp(pte: entry); |
2281 | page_add_anon_rmap(page + i, vma, address: addr, RMAP_NONE); |
2282 | } |
2283 | VM_BUG_ON(!pte_none(ptep_get(pte))); |
2284 | set_pte_at(mm, addr, pte, entry); |
2285 | pte++; |
2286 | } |
2287 | pte_unmap(pte: pte - 1); |
2288 | |
2289 | if (!pmd_migration) |
2290 | page_remove_rmap(page, vma, compound: true); |
2291 | if (freeze) |
2292 | put_page(page); |
2293 | |
2294 | smp_wmb(); /* make pte visible before pmd */ |
2295 | pmd_populate(mm, pmd, pte: pgtable); |
2296 | } |
2297 | |
2298 | void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
2299 | unsigned long address, bool freeze, struct folio *folio) |
2300 | { |
2301 | spinlock_t *ptl; |
2302 | struct mmu_notifier_range range; |
2303 | |
2304 | mmu_notifier_range_init(range: &range, event: MMU_NOTIFY_CLEAR, flags: 0, mm: vma->vm_mm, |
2305 | start: address & HPAGE_PMD_MASK, |
2306 | end: (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); |
2307 | mmu_notifier_invalidate_range_start(range: &range); |
2308 | ptl = pmd_lock(mm: vma->vm_mm, pmd); |
2309 | |
2310 | /* |
2311 | * If caller asks to setup a migration entry, we need a folio to check |
2312 | * pmd against. Otherwise we can end up replacing wrong folio. |
2313 | */ |
2314 | VM_BUG_ON(freeze && !folio); |
2315 | VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); |
2316 | |
2317 | if (pmd_trans_huge(pmd: *pmd) || pmd_devmap(pmd: *pmd) || |
2318 | is_pmd_migration_entry(pmd: *pmd)) { |
2319 | /* |
2320 | * It's safe to call pmd_page when folio is set because it's |
2321 | * guaranteed that pmd is present. |
2322 | */ |
2323 | if (folio && folio != page_folio(pmd_page(*pmd))) |
2324 | goto out; |
2325 | __split_huge_pmd_locked(vma, pmd, haddr: range.start, freeze); |
2326 | } |
2327 | |
2328 | out: |
2329 | spin_unlock(lock: ptl); |
2330 | mmu_notifier_invalidate_range_end(range: &range); |
2331 | } |
2332 | |
2333 | void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, |
2334 | bool freeze, struct folio *folio) |
2335 | { |
2336 | pmd_t *pmd = mm_find_pmd(mm: vma->vm_mm, address); |
2337 | |
2338 | if (!pmd) |
2339 | return; |
2340 | |
2341 | __split_huge_pmd(vma, pmd, address, freeze, folio); |
2342 | } |
2343 | |
2344 | static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) |
2345 | { |
2346 | /* |
2347 | * If the new address isn't hpage aligned and it could previously |
2348 | * contain an hugepage: check if we need to split an huge pmd. |
2349 | */ |
2350 | if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && |
2351 | range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), |
2352 | ALIGN(address, HPAGE_PMD_SIZE))) |
2353 | split_huge_pmd_address(vma, address, freeze: false, NULL); |
2354 | } |
2355 | |
2356 | void vma_adjust_trans_huge(struct vm_area_struct *vma, |
2357 | unsigned long start, |
2358 | unsigned long end, |
2359 | long adjust_next) |
2360 | { |
2361 | /* Check if we need to split start first. */ |
2362 | split_huge_pmd_if_needed(vma, address: start); |
2363 | |
2364 | /* Check if we need to split end next. */ |
2365 | split_huge_pmd_if_needed(vma, address: end); |
2366 | |
2367 | /* |
2368 | * If we're also updating the next vma vm_start, |
2369 | * check if we need to split it. |
2370 | */ |
2371 | if (adjust_next > 0) { |
2372 | struct vm_area_struct *next = find_vma(mm: vma->vm_mm, addr: vma->vm_end); |
2373 | unsigned long nstart = next->vm_start; |
2374 | nstart += adjust_next; |
2375 | split_huge_pmd_if_needed(vma: next, address: nstart); |
2376 | } |
2377 | } |
2378 | |
2379 | static void unmap_folio(struct folio *folio) |
2380 | { |
2381 | enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | |
2382 | TTU_SYNC; |
2383 | |
2384 | VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); |
2385 | |
2386 | /* |
2387 | * Anon pages need migration entries to preserve them, but file |
2388 | * pages can simply be left unmapped, then faulted back on demand. |
2389 | * If that is ever changed (perhaps for mlock), update remap_page(). |
2390 | */ |
2391 | if (folio_test_anon(folio)) |
2392 | try_to_migrate(folio, flags: ttu_flags); |
2393 | else |
2394 | try_to_unmap(folio, flags: ttu_flags | TTU_IGNORE_MLOCK); |
2395 | } |
2396 | |
2397 | static void remap_page(struct folio *folio, unsigned long nr) |
2398 | { |
2399 | int i = 0; |
2400 | |
2401 | /* If unmap_folio() uses try_to_migrate() on file, remove this check */ |
2402 | if (!folio_test_anon(folio)) |
2403 | return; |
2404 | for (;;) { |
2405 | remove_migration_ptes(src: folio, dst: folio, locked: true); |
2406 | i += folio_nr_pages(folio); |
2407 | if (i >= nr) |
2408 | break; |
2409 | folio = folio_next(folio); |
2410 | } |
2411 | } |
2412 | |
2413 | static void lru_add_page_tail(struct page *head, struct page *tail, |
2414 | struct lruvec *lruvec, struct list_head *list) |
2415 | { |
2416 | VM_BUG_ON_PAGE(!PageHead(head), head); |
2417 | VM_BUG_ON_PAGE(PageCompound(tail), head); |
2418 | VM_BUG_ON_PAGE(PageLRU(tail), head); |
2419 | lockdep_assert_held(&lruvec->lru_lock); |
2420 | |
2421 | if (list) { |
2422 | /* page reclaim is reclaiming a huge page */ |
2423 | VM_WARN_ON(PageLRU(head)); |
2424 | get_page(page: tail); |
2425 | list_add_tail(new: &tail->lru, head: list); |
2426 | } else { |
2427 | /* head is still on lru (and we have it frozen) */ |
2428 | VM_WARN_ON(!PageLRU(head)); |
2429 | if (PageUnevictable(page: tail)) |
2430 | tail->mlock_count = 0; |
2431 | else |
2432 | list_add_tail(new: &tail->lru, head: &head->lru); |
2433 | SetPageLRU(tail); |
2434 | } |
2435 | } |
2436 | |
2437 | static void __split_huge_page_tail(struct folio *folio, int tail, |
2438 | struct lruvec *lruvec, struct list_head *list) |
2439 | { |
2440 | struct page *head = &folio->page; |
2441 | struct page *page_tail = head + tail; |
2442 | /* |
2443 | * Careful: new_folio is not a "real" folio before we cleared PageTail. |
2444 | * Don't pass it around before clear_compound_head(). |
2445 | */ |
2446 | struct folio *new_folio = (struct folio *)page_tail; |
2447 | |
2448 | VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); |
2449 | |
2450 | /* |
2451 | * Clone page flags before unfreezing refcount. |
2452 | * |
2453 | * After successful get_page_unless_zero() might follow flags change, |
2454 | * for example lock_page() which set PG_waiters. |
2455 | * |
2456 | * Note that for mapped sub-pages of an anonymous THP, |
2457 | * PG_anon_exclusive has been cleared in unmap_folio() and is stored in |
2458 | * the migration entry instead from where remap_page() will restore it. |
2459 | * We can still have PG_anon_exclusive set on effectively unmapped and |
2460 | * unreferenced sub-pages of an anonymous THP: we can simply drop |
2461 | * PG_anon_exclusive (-> PG_mappedtodisk) for these here. |
2462 | */ |
2463 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; |
2464 | page_tail->flags |= (head->flags & |
2465 | ((1L << PG_referenced) | |
2466 | (1L << PG_swapbacked) | |
2467 | (1L << PG_swapcache) | |
2468 | (1L << PG_mlocked) | |
2469 | (1L << PG_uptodate) | |
2470 | (1L << PG_active) | |
2471 | (1L << PG_workingset) | |
2472 | (1L << PG_locked) | |
2473 | (1L << PG_unevictable) | |
2474 | #ifdef CONFIG_ARCH_USES_PG_ARCH_X |
2475 | (1L << PG_arch_2) | |
2476 | (1L << PG_arch_3) | |
2477 | #endif |
2478 | (1L << PG_dirty) | |
2479 | LRU_GEN_MASK | LRU_REFS_MASK)); |
2480 | |
2481 | /* ->mapping in first and second tail page is replaced by other uses */ |
2482 | VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, |
2483 | page_tail); |
2484 | page_tail->mapping = head->mapping; |
2485 | page_tail->index = head->index + tail; |
2486 | |
2487 | /* |
2488 | * page->private should not be set in tail pages. Fix up and warn once |
2489 | * if private is unexpectedly set. |
2490 | */ |
2491 | if (unlikely(page_tail->private)) { |
2492 | VM_WARN_ON_ONCE_PAGE(true, page_tail); |
2493 | page_tail->private = 0; |
2494 | } |
2495 | if (folio_test_swapcache(folio)) |
2496 | new_folio->swap.val = folio->swap.val + tail; |
2497 | |
2498 | /* Page flags must be visible before we make the page non-compound. */ |
2499 | smp_wmb(); |
2500 | |
2501 | /* |
2502 | * Clear PageTail before unfreezing page refcount. |
2503 | * |
2504 | * After successful get_page_unless_zero() might follow put_page() |
2505 | * which needs correct compound_head(). |
2506 | */ |
2507 | clear_compound_head(page: page_tail); |
2508 | |
2509 | /* Finally unfreeze refcount. Additional reference from page cache. */ |
2510 | page_ref_unfreeze(page: page_tail, count: 1 + (!PageAnon(page: head) || |
2511 | PageSwapCache(page: head))); |
2512 | |
2513 | if (page_is_young(page: head)) |
2514 | set_page_young(page_tail); |
2515 | if (page_is_idle(page: head)) |
2516 | set_page_idle(page_tail); |
2517 | |
2518 | folio_xchg_last_cpupid(folio: new_folio, cpupid: folio_last_cpupid(folio)); |
2519 | |
2520 | /* |
2521 | * always add to the tail because some iterators expect new |
2522 | * pages to show after the currently processed elements - e.g. |
2523 | * migrate_pages |
2524 | */ |
2525 | lru_add_page_tail(head, tail: page_tail, lruvec, list); |
2526 | } |
2527 | |
2528 | static void __split_huge_page(struct page *page, struct list_head *list, |
2529 | pgoff_t end) |
2530 | { |
2531 | struct folio *folio = page_folio(page); |
2532 | struct page *head = &folio->page; |
2533 | struct lruvec *lruvec; |
2534 | struct address_space *swap_cache = NULL; |
2535 | unsigned long offset = 0; |
2536 | unsigned int nr = thp_nr_pages(page: head); |
2537 | int i, nr_dropped = 0; |
2538 | |
2539 | /* complete memcg works before add pages to LRU */ |
2540 | split_page_memcg(head, nr); |
2541 | |
2542 | if (folio_test_anon(folio) && folio_test_swapcache(folio)) { |
2543 | offset = swp_offset(entry: folio->swap); |
2544 | swap_cache = swap_address_space(folio->swap); |
2545 | xa_lock(&swap_cache->i_pages); |
2546 | } |
2547 | |
2548 | /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ |
2549 | lruvec = folio_lruvec_lock(folio); |
2550 | |
2551 | ClearPageHasHWPoisoned(page: head); |
2552 | |
2553 | for (i = nr - 1; i >= 1; i--) { |
2554 | __split_huge_page_tail(folio, tail: i, lruvec, list); |
2555 | /* Some pages can be beyond EOF: drop them from page cache */ |
2556 | if (head[i].index >= end) { |
2557 | struct folio *tail = page_folio(head + i); |
2558 | |
2559 | if (shmem_mapping(mapping: head->mapping)) |
2560 | nr_dropped++; |
2561 | else if (folio_test_clear_dirty(folio: tail)) |
2562 | folio_account_cleaned(folio: tail, |
2563 | wb: inode_to_wb(inode: folio->mapping->host)); |
2564 | __filemap_remove_folio(folio: tail, NULL); |
2565 | folio_put(folio: tail); |
2566 | } else if (!PageAnon(page)) { |
2567 | __xa_store(&head->mapping->i_pages, index: head[i].index, |
2568 | entry: head + i, 0); |
2569 | } else if (swap_cache) { |
2570 | __xa_store(&swap_cache->i_pages, index: offset + i, |
2571 | entry: head + i, 0); |
2572 | } |
2573 | } |
2574 | |
2575 | ClearPageCompound(page: head); |
2576 | unlock_page_lruvec(lruvec); |
2577 | /* Caller disabled irqs, so they are still disabled here */ |
2578 | |
2579 | split_page_owner(page: head, nr); |
2580 | |
2581 | /* See comment in __split_huge_page_tail() */ |
2582 | if (PageAnon(page: head)) { |
2583 | /* Additional pin to swap cache */ |
2584 | if (PageSwapCache(page: head)) { |
2585 | page_ref_add(page: head, nr: 2); |
2586 | xa_unlock(&swap_cache->i_pages); |
2587 | } else { |
2588 | page_ref_inc(page: head); |
2589 | } |
2590 | } else { |
2591 | /* Additional pin to page cache */ |
2592 | page_ref_add(page: head, nr: 2); |
2593 | xa_unlock(&head->mapping->i_pages); |
2594 | } |
2595 | local_irq_enable(); |
2596 | |
2597 | if (nr_dropped) |
2598 | shmem_uncharge(inode: head->mapping->host, pages: nr_dropped); |
2599 | remap_page(folio, nr); |
2600 | |
2601 | if (folio_test_swapcache(folio)) |
2602 | split_swap_cluster(entry: folio->swap); |
2603 | |
2604 | for (i = 0; i < nr; i++) { |
2605 | struct page *subpage = head + i; |
2606 | if (subpage == page) |
2607 | continue; |
2608 | unlock_page(page: subpage); |
2609 | |
2610 | /* |
2611 | * Subpages may be freed if there wasn't any mapping |
2612 | * like if add_to_swap() is running on a lru page that |
2613 | * had its mapping zapped. And freeing these pages |
2614 | * requires taking the lru_lock so we do the put_page |
2615 | * of the tail pages after the split is complete. |
2616 | */ |
2617 | free_page_and_swap_cache(subpage); |
2618 | } |
2619 | } |
2620 | |
2621 | /* Racy check whether the huge page can be split */ |
2622 | bool can_split_folio(struct folio *folio, int *) |
2623 | { |
2624 | int ; |
2625 | |
2626 | /* Additional pins from page cache */ |
2627 | if (folio_test_anon(folio)) |
2628 | extra_pins = folio_test_swapcache(folio) ? |
2629 | folio_nr_pages(folio) : 0; |
2630 | else |
2631 | extra_pins = folio_nr_pages(folio); |
2632 | if (pextra_pins) |
2633 | *pextra_pins = extra_pins; |
2634 | return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1; |
2635 | } |
2636 | |
2637 | /* |
2638 | * This function splits huge page into normal pages. @page can point to any |
2639 | * subpage of huge page to split. Split doesn't change the position of @page. |
2640 | * |
2641 | * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. |
2642 | * The huge page must be locked. |
2643 | * |
2644 | * If @list is null, tail pages will be added to LRU list, otherwise, to @list. |
2645 | * |
2646 | * Both head page and tail pages will inherit mapping, flags, and so on from |
2647 | * the hugepage. |
2648 | * |
2649 | * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if |
2650 | * they are not mapped. |
2651 | * |
2652 | * Returns 0 if the hugepage is split successfully. |
2653 | * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under |
2654 | * us. |
2655 | */ |
2656 | int split_huge_page_to_list(struct page *page, struct list_head *list) |
2657 | { |
2658 | struct folio *folio = page_folio(page); |
2659 | struct deferred_split *ds_queue = get_deferred_split_queue(folio); |
2660 | XA_STATE(xas, &folio->mapping->i_pages, folio->index); |
2661 | struct anon_vma *anon_vma = NULL; |
2662 | struct address_space *mapping = NULL; |
2663 | int , ret; |
2664 | pgoff_t end; |
2665 | bool is_hzp; |
2666 | |
2667 | VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); |
2668 | VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); |
2669 | |
2670 | is_hzp = is_huge_zero_page(page: &folio->page); |
2671 | if (is_hzp) { |
2672 | pr_warn_ratelimited("Called split_huge_page for huge zero page\n" ); |
2673 | return -EBUSY; |
2674 | } |
2675 | |
2676 | if (folio_test_writeback(folio)) |
2677 | return -EBUSY; |
2678 | |
2679 | if (folio_test_anon(folio)) { |
2680 | /* |
2681 | * The caller does not necessarily hold an mmap_lock that would |
2682 | * prevent the anon_vma disappearing so we first we take a |
2683 | * reference to it and then lock the anon_vma for write. This |
2684 | * is similar to folio_lock_anon_vma_read except the write lock |
2685 | * is taken to serialise against parallel split or collapse |
2686 | * operations. |
2687 | */ |
2688 | anon_vma = folio_get_anon_vma(folio); |
2689 | if (!anon_vma) { |
2690 | ret = -EBUSY; |
2691 | goto out; |
2692 | } |
2693 | end = -1; |
2694 | mapping = NULL; |
2695 | anon_vma_lock_write(anon_vma); |
2696 | } else { |
2697 | gfp_t gfp; |
2698 | |
2699 | mapping = folio->mapping; |
2700 | |
2701 | /* Truncated ? */ |
2702 | if (!mapping) { |
2703 | ret = -EBUSY; |
2704 | goto out; |
2705 | } |
2706 | |
2707 | gfp = current_gfp_context(flags: mapping_gfp_mask(mapping) & |
2708 | GFP_RECLAIM_MASK); |
2709 | |
2710 | if (!filemap_release_folio(folio, gfp)) { |
2711 | ret = -EBUSY; |
2712 | goto out; |
2713 | } |
2714 | |
2715 | xas_split_alloc(&xas, entry: folio, order: folio_order(folio), gfp); |
2716 | if (xas_error(xas: &xas)) { |
2717 | ret = xas_error(xas: &xas); |
2718 | goto out; |
2719 | } |
2720 | |
2721 | anon_vma = NULL; |
2722 | i_mmap_lock_read(mapping); |
2723 | |
2724 | /* |
2725 | *__split_huge_page() may need to trim off pages beyond EOF: |
2726 | * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, |
2727 | * which cannot be nested inside the page tree lock. So note |
2728 | * end now: i_size itself may be changed at any moment, but |
2729 | * folio lock is good enough to serialize the trimming. |
2730 | */ |
2731 | end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); |
2732 | if (shmem_mapping(mapping)) |
2733 | end = shmem_fallocend(inode: mapping->host, eof: end); |
2734 | } |
2735 | |
2736 | /* |
2737 | * Racy check if we can split the page, before unmap_folio() will |
2738 | * split PMDs |
2739 | */ |
2740 | if (!can_split_folio(folio, pextra_pins: &extra_pins)) { |
2741 | ret = -EAGAIN; |
2742 | goto out_unlock; |
2743 | } |
2744 | |
2745 | unmap_folio(folio); |
2746 | |
2747 | /* block interrupt reentry in xa_lock and spinlock */ |
2748 | local_irq_disable(); |
2749 | if (mapping) { |
2750 | /* |
2751 | * Check if the folio is present in page cache. |
2752 | * We assume all tail are present too, if folio is there. |
2753 | */ |
2754 | xas_lock(&xas); |
2755 | xas_reset(xas: &xas); |
2756 | if (xas_load(&xas) != folio) |
2757 | goto fail; |
2758 | } |
2759 | |
2760 | /* Prevent deferred_split_scan() touching ->_refcount */ |
2761 | spin_lock(lock: &ds_queue->split_queue_lock); |
2762 | if (folio_ref_freeze(folio, count: 1 + extra_pins)) { |
2763 | if (!list_empty(head: &folio->_deferred_list)) { |
2764 | ds_queue->split_queue_len--; |
2765 | list_del(entry: &folio->_deferred_list); |
2766 | } |
2767 | spin_unlock(lock: &ds_queue->split_queue_lock); |
2768 | if (mapping) { |
2769 | int nr = folio_nr_pages(folio); |
2770 | |
2771 | xas_split(&xas, entry: folio, order: folio_order(folio)); |
2772 | if (folio_test_swapbacked(folio)) { |
2773 | __lruvec_stat_mod_folio(folio, idx: NR_SHMEM_THPS, |
2774 | val: -nr); |
2775 | } else { |
2776 | __lruvec_stat_mod_folio(folio, idx: NR_FILE_THPS, |
2777 | val: -nr); |
2778 | filemap_nr_thps_dec(mapping); |
2779 | } |
2780 | } |
2781 | |
2782 | __split_huge_page(page, list, end); |
2783 | ret = 0; |
2784 | } else { |
2785 | spin_unlock(lock: &ds_queue->split_queue_lock); |
2786 | fail: |
2787 | if (mapping) |
2788 | xas_unlock(&xas); |
2789 | local_irq_enable(); |
2790 | remap_page(folio, nr: folio_nr_pages(folio)); |
2791 | ret = -EAGAIN; |
2792 | } |
2793 | |
2794 | out_unlock: |
2795 | if (anon_vma) { |
2796 | anon_vma_unlock_write(anon_vma); |
2797 | put_anon_vma(anon_vma); |
2798 | } |
2799 | if (mapping) |
2800 | i_mmap_unlock_read(mapping); |
2801 | out: |
2802 | xas_destroy(&xas); |
2803 | count_vm_event(item: !ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); |
2804 | return ret; |
2805 | } |
2806 | |
2807 | void folio_undo_large_rmappable(struct folio *folio) |
2808 | { |
2809 | struct deferred_split *ds_queue; |
2810 | unsigned long flags; |
2811 | |
2812 | /* |
2813 | * At this point, there is no one trying to add the folio to |
2814 | * deferred_list. If folio is not in deferred_list, it's safe |
2815 | * to check without acquiring the split_queue_lock. |
2816 | */ |
2817 | if (data_race(list_empty(&folio->_deferred_list))) |
2818 | return; |
2819 | |
2820 | ds_queue = get_deferred_split_queue(folio); |
2821 | spin_lock_irqsave(&ds_queue->split_queue_lock, flags); |
2822 | if (!list_empty(head: &folio->_deferred_list)) { |
2823 | ds_queue->split_queue_len--; |
2824 | list_del(entry: &folio->_deferred_list); |
2825 | } |
2826 | spin_unlock_irqrestore(lock: &ds_queue->split_queue_lock, flags); |
2827 | } |
2828 | |
2829 | void deferred_split_folio(struct folio *folio) |
2830 | { |
2831 | struct deferred_split *ds_queue = get_deferred_split_queue(folio); |
2832 | #ifdef CONFIG_MEMCG |
2833 | struct mem_cgroup *memcg = folio_memcg(folio); |
2834 | #endif |
2835 | unsigned long flags; |
2836 | |
2837 | VM_BUG_ON_FOLIO(folio_order(folio) < 2, folio); |
2838 | |
2839 | /* |
2840 | * The try_to_unmap() in page reclaim path might reach here too, |
2841 | * this may cause a race condition to corrupt deferred split queue. |
2842 | * And, if page reclaim is already handling the same folio, it is |
2843 | * unnecessary to handle it again in shrinker. |
2844 | * |
2845 | * Check the swapcache flag to determine if the folio is being |
2846 | * handled by page reclaim since THP swap would add the folio into |
2847 | * swap cache before calling try_to_unmap(). |
2848 | */ |
2849 | if (folio_test_swapcache(folio)) |
2850 | return; |
2851 | |
2852 | if (!list_empty(head: &folio->_deferred_list)) |
2853 | return; |
2854 | |
2855 | spin_lock_irqsave(&ds_queue->split_queue_lock, flags); |
2856 | if (list_empty(head: &folio->_deferred_list)) { |
2857 | count_vm_event(item: THP_DEFERRED_SPLIT_PAGE); |
2858 | list_add_tail(new: &folio->_deferred_list, head: &ds_queue->split_queue); |
2859 | ds_queue->split_queue_len++; |
2860 | #ifdef CONFIG_MEMCG |
2861 | if (memcg) |
2862 | set_shrinker_bit(memcg, nid: folio_nid(folio), |
2863 | shrinker_id: deferred_split_shrinker->id); |
2864 | #endif |
2865 | } |
2866 | spin_unlock_irqrestore(lock: &ds_queue->split_queue_lock, flags); |
2867 | } |
2868 | |
2869 | static unsigned long deferred_split_count(struct shrinker *shrink, |
2870 | struct shrink_control *sc) |
2871 | { |
2872 | struct pglist_data *pgdata = NODE_DATA(sc->nid); |
2873 | struct deferred_split *ds_queue = &pgdata->deferred_split_queue; |
2874 | |
2875 | #ifdef CONFIG_MEMCG |
2876 | if (sc->memcg) |
2877 | ds_queue = &sc->memcg->deferred_split_queue; |
2878 | #endif |
2879 | return READ_ONCE(ds_queue->split_queue_len); |
2880 | } |
2881 | |
2882 | static unsigned long deferred_split_scan(struct shrinker *shrink, |
2883 | struct shrink_control *sc) |
2884 | { |
2885 | struct pglist_data *pgdata = NODE_DATA(sc->nid); |
2886 | struct deferred_split *ds_queue = &pgdata->deferred_split_queue; |
2887 | unsigned long flags; |
2888 | LIST_HEAD(list); |
2889 | struct folio *folio, *next; |
2890 | int split = 0; |
2891 | |
2892 | #ifdef CONFIG_MEMCG |
2893 | if (sc->memcg) |
2894 | ds_queue = &sc->memcg->deferred_split_queue; |
2895 | #endif |
2896 | |
2897 | spin_lock_irqsave(&ds_queue->split_queue_lock, flags); |
2898 | /* Take pin on all head pages to avoid freeing them under us */ |
2899 | list_for_each_entry_safe(folio, next, &ds_queue->split_queue, |
2900 | _deferred_list) { |
2901 | if (folio_try_get(folio)) { |
2902 | list_move(list: &folio->_deferred_list, head: &list); |
2903 | } else { |
2904 | /* We lost race with folio_put() */ |
2905 | list_del_init(entry: &folio->_deferred_list); |
2906 | ds_queue->split_queue_len--; |
2907 | } |
2908 | if (!--sc->nr_to_scan) |
2909 | break; |
2910 | } |
2911 | spin_unlock_irqrestore(lock: &ds_queue->split_queue_lock, flags); |
2912 | |
2913 | list_for_each_entry_safe(folio, next, &list, _deferred_list) { |
2914 | if (!folio_trylock(folio)) |
2915 | goto next; |
2916 | /* split_huge_page() removes page from list on success */ |
2917 | if (!split_folio(folio)) |
2918 | split++; |
2919 | folio_unlock(folio); |
2920 | next: |
2921 | folio_put(folio); |
2922 | } |
2923 | |
2924 | spin_lock_irqsave(&ds_queue->split_queue_lock, flags); |
2925 | list_splice_tail(list: &list, head: &ds_queue->split_queue); |
2926 | spin_unlock_irqrestore(lock: &ds_queue->split_queue_lock, flags); |
2927 | |
2928 | /* |
2929 | * Stop shrinker if we didn't split any page, but the queue is empty. |
2930 | * This can happen if pages were freed under us. |
2931 | */ |
2932 | if (!split && list_empty(head: &ds_queue->split_queue)) |
2933 | return SHRINK_STOP; |
2934 | return split; |
2935 | } |
2936 | |
2937 | #ifdef CONFIG_DEBUG_FS |
2938 | static void split_huge_pages_all(void) |
2939 | { |
2940 | struct zone *zone; |
2941 | struct page *page; |
2942 | struct folio *folio; |
2943 | unsigned long pfn, max_zone_pfn; |
2944 | unsigned long total = 0, split = 0; |
2945 | |
2946 | pr_debug("Split all THPs\n" ); |
2947 | for_each_zone(zone) { |
2948 | if (!managed_zone(zone)) |
2949 | continue; |
2950 | max_zone_pfn = zone_end_pfn(zone); |
2951 | for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { |
2952 | int nr_pages; |
2953 | |
2954 | page = pfn_to_online_page(pfn); |
2955 | if (!page || PageTail(page)) |
2956 | continue; |
2957 | folio = page_folio(page); |
2958 | if (!folio_try_get(folio)) |
2959 | continue; |
2960 | |
2961 | if (unlikely(page_folio(page) != folio)) |
2962 | goto next; |
2963 | |
2964 | if (zone != folio_zone(folio)) |
2965 | goto next; |
2966 | |
2967 | if (!folio_test_large(folio) |
2968 | || folio_test_hugetlb(folio) |
2969 | || !folio_test_lru(folio)) |
2970 | goto next; |
2971 | |
2972 | total++; |
2973 | folio_lock(folio); |
2974 | nr_pages = folio_nr_pages(folio); |
2975 | if (!split_folio(folio)) |
2976 | split++; |
2977 | pfn += nr_pages - 1; |
2978 | folio_unlock(folio); |
2979 | next: |
2980 | folio_put(folio); |
2981 | cond_resched(); |
2982 | } |
2983 | } |
2984 | |
2985 | pr_debug("%lu of %lu THP split\n" , split, total); |
2986 | } |
2987 | |
2988 | static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) |
2989 | { |
2990 | return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || |
2991 | is_vm_hugetlb_page(vma); |
2992 | } |
2993 | |
2994 | static int split_huge_pages_pid(int pid, unsigned long vaddr_start, |
2995 | unsigned long vaddr_end) |
2996 | { |
2997 | int ret = 0; |
2998 | struct task_struct *task; |
2999 | struct mm_struct *mm; |
3000 | unsigned long total = 0, split = 0; |
3001 | unsigned long addr; |
3002 | |
3003 | vaddr_start &= PAGE_MASK; |
3004 | vaddr_end &= PAGE_MASK; |
3005 | |
3006 | /* Find the task_struct from pid */ |
3007 | rcu_read_lock(); |
3008 | task = find_task_by_vpid(nr: pid); |
3009 | if (!task) { |
3010 | rcu_read_unlock(); |
3011 | ret = -ESRCH; |
3012 | goto out; |
3013 | } |
3014 | get_task_struct(t: task); |
3015 | rcu_read_unlock(); |
3016 | |
3017 | /* Find the mm_struct */ |
3018 | mm = get_task_mm(task); |
3019 | put_task_struct(t: task); |
3020 | |
3021 | if (!mm) { |
3022 | ret = -EINVAL; |
3023 | goto out; |
3024 | } |
3025 | |
3026 | pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n" , |
3027 | pid, vaddr_start, vaddr_end); |
3028 | |
3029 | mmap_read_lock(mm); |
3030 | /* |
3031 | * always increase addr by PAGE_SIZE, since we could have a PTE page |
3032 | * table filled with PTE-mapped THPs, each of which is distinct. |
3033 | */ |
3034 | for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { |
3035 | struct vm_area_struct *vma = vma_lookup(mm, addr); |
3036 | struct page *page; |
3037 | struct folio *folio; |
3038 | |
3039 | if (!vma) |
3040 | break; |
3041 | |
3042 | /* skip special VMA and hugetlb VMA */ |
3043 | if (vma_not_suitable_for_thp_split(vma)) { |
3044 | addr = vma->vm_end; |
3045 | continue; |
3046 | } |
3047 | |
3048 | /* FOLL_DUMP to ignore special (like zero) pages */ |
3049 | page = follow_page(vma, address: addr, foll_flags: FOLL_GET | FOLL_DUMP); |
3050 | |
3051 | if (IS_ERR_OR_NULL(ptr: page)) |
3052 | continue; |
3053 | |
3054 | folio = page_folio(page); |
3055 | if (!is_transparent_hugepage(folio)) |
3056 | goto next; |
3057 | |
3058 | total++; |
3059 | if (!can_split_folio(folio, NULL)) |
3060 | goto next; |
3061 | |
3062 | if (!folio_trylock(folio)) |
3063 | goto next; |
3064 | |
3065 | if (!split_folio(folio)) |
3066 | split++; |
3067 | |
3068 | folio_unlock(folio); |
3069 | next: |
3070 | folio_put(folio); |
3071 | cond_resched(); |
3072 | } |
3073 | mmap_read_unlock(mm); |
3074 | mmput(mm); |
3075 | |
3076 | pr_debug("%lu of %lu THP split\n" , split, total); |
3077 | |
3078 | out: |
3079 | return ret; |
3080 | } |
3081 | |
3082 | static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, |
3083 | pgoff_t off_end) |
3084 | { |
3085 | struct filename *file; |
3086 | struct file *candidate; |
3087 | struct address_space *mapping; |
3088 | int ret = -EINVAL; |
3089 | pgoff_t index; |
3090 | int nr_pages = 1; |
3091 | unsigned long total = 0, split = 0; |
3092 | |
3093 | file = getname_kernel(file_path); |
3094 | if (IS_ERR(ptr: file)) |
3095 | return ret; |
3096 | |
3097 | candidate = file_open_name(file, O_RDONLY, 0); |
3098 | if (IS_ERR(ptr: candidate)) |
3099 | goto out; |
3100 | |
3101 | pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n" , |
3102 | file_path, off_start, off_end); |
3103 | |
3104 | mapping = candidate->f_mapping; |
3105 | |
3106 | for (index = off_start; index < off_end; index += nr_pages) { |
3107 | struct folio *folio = filemap_get_folio(mapping, index); |
3108 | |
3109 | nr_pages = 1; |
3110 | if (IS_ERR(ptr: folio)) |
3111 | continue; |
3112 | |
3113 | if (!folio_test_large(folio)) |
3114 | goto next; |
3115 | |
3116 | total++; |
3117 | nr_pages = folio_nr_pages(folio); |
3118 | |
3119 | if (!folio_trylock(folio)) |
3120 | goto next; |
3121 | |
3122 | if (!split_folio(folio)) |
3123 | split++; |
3124 | |
3125 | folio_unlock(folio); |
3126 | next: |
3127 | folio_put(folio); |
3128 | cond_resched(); |
3129 | } |
3130 | |
3131 | filp_close(candidate, NULL); |
3132 | ret = 0; |
3133 | |
3134 | pr_debug("%lu of %lu file-backed THP split\n" , split, total); |
3135 | out: |
3136 | putname(name: file); |
3137 | return ret; |
3138 | } |
3139 | |
3140 | #define MAX_INPUT_BUF_SZ 255 |
3141 | |
3142 | static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, |
3143 | size_t count, loff_t *ppops) |
3144 | { |
3145 | static DEFINE_MUTEX(split_debug_mutex); |
3146 | ssize_t ret; |
3147 | /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */ |
3148 | char input_buf[MAX_INPUT_BUF_SZ]; |
3149 | int pid; |
3150 | unsigned long vaddr_start, vaddr_end; |
3151 | |
3152 | ret = mutex_lock_interruptible(&split_debug_mutex); |
3153 | if (ret) |
3154 | return ret; |
3155 | |
3156 | ret = -EFAULT; |
3157 | |
3158 | memset(input_buf, 0, MAX_INPUT_BUF_SZ); |
3159 | if (copy_from_user(to: input_buf, from: buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) |
3160 | goto out; |
3161 | |
3162 | input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; |
3163 | |
3164 | if (input_buf[0] == '/') { |
3165 | char *tok; |
3166 | char *buf = input_buf; |
3167 | char file_path[MAX_INPUT_BUF_SZ]; |
3168 | pgoff_t off_start = 0, off_end = 0; |
3169 | size_t input_len = strlen(input_buf); |
3170 | |
3171 | tok = strsep(&buf, "," ); |
3172 | if (tok) { |
3173 | strcpy(p: file_path, q: tok); |
3174 | } else { |
3175 | ret = -EINVAL; |
3176 | goto out; |
3177 | } |
3178 | |
3179 | ret = sscanf(buf, "0x%lx,0x%lx" , &off_start, &off_end); |
3180 | if (ret != 2) { |
3181 | ret = -EINVAL; |
3182 | goto out; |
3183 | } |
3184 | ret = split_huge_pages_in_file(file_path, off_start, off_end); |
3185 | if (!ret) |
3186 | ret = input_len; |
3187 | |
3188 | goto out; |
3189 | } |
3190 | |
3191 | ret = sscanf(input_buf, "%d,0x%lx,0x%lx" , &pid, &vaddr_start, &vaddr_end); |
3192 | if (ret == 1 && pid == 1) { |
3193 | split_huge_pages_all(); |
3194 | ret = strlen(input_buf); |
3195 | goto out; |
3196 | } else if (ret != 3) { |
3197 | ret = -EINVAL; |
3198 | goto out; |
3199 | } |
3200 | |
3201 | ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end); |
3202 | if (!ret) |
3203 | ret = strlen(input_buf); |
3204 | out: |
3205 | mutex_unlock(lock: &split_debug_mutex); |
3206 | return ret; |
3207 | |
3208 | } |
3209 | |
3210 | static const struct file_operations split_huge_pages_fops = { |
3211 | .owner = THIS_MODULE, |
3212 | .write = split_huge_pages_write, |
3213 | .llseek = no_llseek, |
3214 | }; |
3215 | |
3216 | static int __init split_huge_pages_debugfs(void) |
3217 | { |
3218 | debugfs_create_file(name: "split_huge_pages" , mode: 0200, NULL, NULL, |
3219 | fops: &split_huge_pages_fops); |
3220 | return 0; |
3221 | } |
3222 | late_initcall(split_huge_pages_debugfs); |
3223 | #endif |
3224 | |
3225 | #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION |
3226 | int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, |
3227 | struct page *page) |
3228 | { |
3229 | struct vm_area_struct *vma = pvmw->vma; |
3230 | struct mm_struct *mm = vma->vm_mm; |
3231 | unsigned long address = pvmw->address; |
3232 | bool anon_exclusive; |
3233 | pmd_t pmdval; |
3234 | swp_entry_t entry; |
3235 | pmd_t pmdswp; |
3236 | |
3237 | if (!(pvmw->pmd && !pvmw->pte)) |
3238 | return 0; |
3239 | |
3240 | flush_cache_range(vma, start: address, end: address + HPAGE_PMD_SIZE); |
3241 | pmdval = pmdp_invalidate(vma, address, pmdp: pvmw->pmd); |
3242 | |
3243 | /* See page_try_share_anon_rmap(): invalidate PMD first. */ |
3244 | anon_exclusive = PageAnon(page) && PageAnonExclusive(page); |
3245 | if (anon_exclusive && page_try_share_anon_rmap(page)) { |
3246 | set_pmd_at(mm, addr: address, pmdp: pvmw->pmd, pmd: pmdval); |
3247 | return -EBUSY; |
3248 | } |
3249 | |
3250 | if (pmd_dirty(pmd: pmdval)) |
3251 | set_page_dirty(page); |
3252 | if (pmd_write(pmd: pmdval)) |
3253 | entry = make_writable_migration_entry(page_to_pfn(page)); |
3254 | else if (anon_exclusive) |
3255 | entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); |
3256 | else |
3257 | entry = make_readable_migration_entry(page_to_pfn(page)); |
3258 | if (pmd_young(pmd: pmdval)) |
3259 | entry = make_migration_entry_young(entry); |
3260 | if (pmd_dirty(pmd: pmdval)) |
3261 | entry = make_migration_entry_dirty(entry); |
3262 | pmdswp = swp_entry_to_pmd(entry); |
3263 | if (pmd_soft_dirty(pmd: pmdval)) |
3264 | pmdswp = pmd_swp_mksoft_dirty(pmd: pmdswp); |
3265 | if (pmd_uffd_wp(pmd: pmdval)) |
3266 | pmdswp = pmd_swp_mkuffd_wp(pmd: pmdswp); |
3267 | set_pmd_at(mm, addr: address, pmdp: pvmw->pmd, pmd: pmdswp); |
3268 | page_remove_rmap(page, vma, compound: true); |
3269 | put_page(page); |
3270 | trace_set_migration_pmd(addr: address, pmd: pmd_val(pmd: pmdswp)); |
3271 | |
3272 | return 0; |
3273 | } |
3274 | |
3275 | void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) |
3276 | { |
3277 | struct vm_area_struct *vma = pvmw->vma; |
3278 | struct mm_struct *mm = vma->vm_mm; |
3279 | unsigned long address = pvmw->address; |
3280 | unsigned long haddr = address & HPAGE_PMD_MASK; |
3281 | pmd_t pmde; |
3282 | swp_entry_t entry; |
3283 | |
3284 | if (!(pvmw->pmd && !pvmw->pte)) |
3285 | return; |
3286 | |
3287 | entry = pmd_to_swp_entry(pmd: *pvmw->pmd); |
3288 | get_page(page: new); |
3289 | pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot)); |
3290 | if (pmd_swp_soft_dirty(pmd: *pvmw->pmd)) |
3291 | pmde = pmd_mksoft_dirty(pmd: pmde); |
3292 | if (is_writable_migration_entry(entry)) |
3293 | pmde = pmd_mkwrite(pmd: pmde, vma); |
3294 | if (pmd_swp_uffd_wp(pmd: *pvmw->pmd)) |
3295 | pmde = pmd_mkuffd_wp(pmd: pmde); |
3296 | if (!is_migration_entry_young(entry)) |
3297 | pmde = pmd_mkold(pmd: pmde); |
3298 | /* NOTE: this may contain setting soft-dirty on some archs */ |
3299 | if (PageDirty(page: new) && is_migration_entry_dirty(entry)) |
3300 | pmde = pmd_mkdirty(pmd: pmde); |
3301 | |
3302 | if (PageAnon(page: new)) { |
3303 | rmap_t rmap_flags = RMAP_COMPOUND; |
3304 | |
3305 | if (!is_readable_migration_entry(entry)) |
3306 | rmap_flags |= RMAP_EXCLUSIVE; |
3307 | |
3308 | page_add_anon_rmap(new, vma, address: haddr, flags: rmap_flags); |
3309 | } else { |
3310 | page_add_file_rmap(new, vma, compound: true); |
3311 | } |
3312 | VM_BUG_ON(pmd_write(pmde) && PageAnon(new) && !PageAnonExclusive(new)); |
3313 | set_pmd_at(mm, addr: haddr, pmdp: pvmw->pmd, pmd: pmde); |
3314 | |
3315 | /* No need to invalidate - it was non-present before */ |
3316 | update_mmu_cache_pmd(vma, addr: address, pmd: pvmw->pmd); |
3317 | trace_remove_migration_pmd(addr: address, pmd: pmd_val(pmd: pmde)); |
3318 | } |
3319 | #endif |
3320 | |