add debugging code
[cor.git] / mm / huge_memory.c
blob41a0fbddc96bb27a0717e4033bbbaa511aac4899
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2009 Red Hat, Inc.
4 */
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8 #include <linux/mm.h>
9 #include <linux/sched.h>
10 #include <linux/sched/coredump.h>
11 #include <linux/sched/numa_balancing.h>
12 #include <linux/highmem.h>
13 #include <linux/hugetlb.h>
14 #include <linux/mmu_notifier.h>
15 #include <linux/rmap.h>
16 #include <linux/swap.h>
17 #include <linux/shrinker.h>
18 #include <linux/mm_inline.h>
19 #include <linux/swapops.h>
20 #include <linux/dax.h>
21 #include <linux/khugepaged.h>
22 #include <linux/freezer.h>
23 #include <linux/pfn_t.h>
24 #include <linux/mman.h>
25 #include <linux/memremap.h>
26 #include <linux/pagemap.h>
27 #include <linux/debugfs.h>
28 #include <linux/migrate.h>
29 #include <linux/hashtable.h>
30 #include <linux/userfaultfd_k.h>
31 #include <linux/page_idle.h>
32 #include <linux/shmem_fs.h>
33 #include <linux/oom.h>
34 #include <linux/numa.h>
35 #include <linux/page_owner.h>
37 #include <asm/tlb.h>
38 #include <asm/pgalloc.h>
39 #include "internal.h"
42 * By default, transparent hugepage support is disabled in order to avoid
43 * risking an increased memory footprint for applications that are not
44 * guaranteed to benefit from it. When transparent hugepage support is
45 * enabled, it is for all mappings, and khugepaged scans all mappings.
46 * Defrag is invoked by khugepaged hugepage allocations and by page faults
47 * for all hugepage allocations.
49 unsigned long transparent_hugepage_flags __read_mostly =
50 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
51 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
52 #endif
53 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
54 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
55 #endif
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
58 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
60 static struct shrinker deferred_split_shrinker;
62 static atomic_t huge_zero_refcount;
63 struct page *huge_zero_page __read_mostly;
65 bool transparent_hugepage_enabled(struct vm_area_struct *vma)
67 /* The addr is used to check if the vma size fits */
68 unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE;
70 if (!transhuge_vma_suitable(vma, addr))
71 return false;
72 if (vma_is_anonymous(vma))
73 return __transparent_hugepage_enabled(vma);
74 if (vma_is_shmem(vma))
75 return shmem_huge_enabled(vma);
77 return false;
80 static struct page *get_huge_zero_page(void)
82 struct page *zero_page;
83 retry:
84 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
85 return READ_ONCE(huge_zero_page);
87 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
88 HPAGE_PMD_ORDER);
89 if (!zero_page) {
90 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
91 return NULL;
93 count_vm_event(THP_ZERO_PAGE_ALLOC);
94 preempt_disable();
95 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
96 preempt_enable();
97 __free_pages(zero_page, compound_order(zero_page));
98 goto retry;
101 /* We take additional reference here. It will be put back by shrinker */
102 atomic_set(&huge_zero_refcount, 2);
103 preempt_enable();
104 return READ_ONCE(huge_zero_page);
107 static void put_huge_zero_page(void)
110 * Counter should never go to zero here. Only shrinker can put
111 * last reference.
113 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
116 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
118 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
119 return READ_ONCE(huge_zero_page);
121 if (!get_huge_zero_page())
122 return NULL;
124 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
125 put_huge_zero_page();
127 return READ_ONCE(huge_zero_page);
130 void mm_put_huge_zero_page(struct mm_struct *mm)
132 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
133 put_huge_zero_page();
136 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
137 struct shrink_control *sc)
139 /* we can free zero page only if last reference remains */
140 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
143 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
144 struct shrink_control *sc)
146 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
147 struct page *zero_page = xchg(&huge_zero_page, NULL);
148 BUG_ON(zero_page == NULL);
149 __free_pages(zero_page, compound_order(zero_page));
150 return HPAGE_PMD_NR;
153 return 0;
156 static struct shrinker huge_zero_page_shrinker = {
157 .count_objects = shrink_huge_zero_page_count,
158 .scan_objects = shrink_huge_zero_page_scan,
159 .seeks = DEFAULT_SEEKS,
162 #ifdef CONFIG_SYSFS
163 static ssize_t enabled_show(struct kobject *kobj,
164 struct kobj_attribute *attr, char *buf)
166 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
167 return sprintf(buf, "[always] madvise never\n");
168 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
169 return sprintf(buf, "always [madvise] never\n");
170 else
171 return sprintf(buf, "always madvise [never]\n");
174 static ssize_t enabled_store(struct kobject *kobj,
175 struct kobj_attribute *attr,
176 const char *buf, size_t count)
178 ssize_t ret = count;
180 if (!memcmp("always", buf,
181 min(sizeof("always")-1, count))) {
182 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
183 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
184 } else if (!memcmp("madvise", buf,
185 min(sizeof("madvise")-1, count))) {
186 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
187 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
188 } else if (!memcmp("never", buf,
189 min(sizeof("never")-1, count))) {
190 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
191 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
192 } else
193 ret = -EINVAL;
195 if (ret > 0) {
196 int err = start_stop_khugepaged();
197 if (err)
198 ret = err;
200 return ret;
202 static struct kobj_attribute enabled_attr =
203 __ATTR(enabled, 0644, enabled_show, enabled_store);
205 ssize_t single_hugepage_flag_show(struct kobject *kobj,
206 struct kobj_attribute *attr, char *buf,
207 enum transparent_hugepage_flag flag)
209 return sprintf(buf, "%d\n",
210 !!test_bit(flag, &transparent_hugepage_flags));
213 ssize_t single_hugepage_flag_store(struct kobject *kobj,
214 struct kobj_attribute *attr,
215 const char *buf, size_t count,
216 enum transparent_hugepage_flag flag)
218 unsigned long value;
219 int ret;
221 ret = kstrtoul(buf, 10, &value);
222 if (ret < 0)
223 return ret;
224 if (value > 1)
225 return -EINVAL;
227 if (value)
228 set_bit(flag, &transparent_hugepage_flags);
229 else
230 clear_bit(flag, &transparent_hugepage_flags);
232 return count;
235 static ssize_t defrag_show(struct kobject *kobj,
236 struct kobj_attribute *attr, char *buf)
238 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
239 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
240 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
241 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
242 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
243 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
244 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
245 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
246 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
249 static ssize_t defrag_store(struct kobject *kobj,
250 struct kobj_attribute *attr,
251 const char *buf, size_t count)
253 if (!memcmp("always", buf,
254 min(sizeof("always")-1, count))) {
255 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
256 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
258 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
259 } else if (!memcmp("defer+madvise", buf,
260 min(sizeof("defer+madvise")-1, count))) {
261 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
262 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
264 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
265 } else if (!memcmp("defer", buf,
266 min(sizeof("defer")-1, count))) {
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
268 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
269 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
270 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
271 } else if (!memcmp("madvise", buf,
272 min(sizeof("madvise")-1, count))) {
273 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
274 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
275 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
276 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
277 } else if (!memcmp("never", buf,
278 min(sizeof("never")-1, count))) {
279 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
280 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
281 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
282 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
283 } else
284 return -EINVAL;
286 return count;
288 static struct kobj_attribute defrag_attr =
289 __ATTR(defrag, 0644, defrag_show, defrag_store);
291 static ssize_t use_zero_page_show(struct kobject *kobj,
292 struct kobj_attribute *attr, char *buf)
294 return single_hugepage_flag_show(kobj, attr, buf,
295 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
297 static ssize_t use_zero_page_store(struct kobject *kobj,
298 struct kobj_attribute *attr, const char *buf, size_t count)
300 return single_hugepage_flag_store(kobj, attr, buf, count,
301 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
303 static struct kobj_attribute use_zero_page_attr =
304 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
306 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
307 struct kobj_attribute *attr, char *buf)
309 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
311 static struct kobj_attribute hpage_pmd_size_attr =
312 __ATTR_RO(hpage_pmd_size);
314 #ifdef CONFIG_DEBUG_VM
315 static ssize_t debug_cow_show(struct kobject *kobj,
316 struct kobj_attribute *attr, char *buf)
318 return single_hugepage_flag_show(kobj, attr, buf,
319 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
321 static ssize_t debug_cow_store(struct kobject *kobj,
322 struct kobj_attribute *attr,
323 const char *buf, size_t count)
325 return single_hugepage_flag_store(kobj, attr, buf, count,
326 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
328 static struct kobj_attribute debug_cow_attr =
329 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
330 #endif /* CONFIG_DEBUG_VM */
332 static struct attribute *hugepage_attr[] = {
333 &enabled_attr.attr,
334 &defrag_attr.attr,
335 &use_zero_page_attr.attr,
336 &hpage_pmd_size_attr.attr,
337 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
338 &shmem_enabled_attr.attr,
339 #endif
340 #ifdef CONFIG_DEBUG_VM
341 &debug_cow_attr.attr,
342 #endif
343 NULL,
346 static const struct attribute_group hugepage_attr_group = {
347 .attrs = hugepage_attr,
350 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
352 int err;
354 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
355 if (unlikely(!*hugepage_kobj)) {
356 pr_err("failed to create transparent hugepage kobject\n");
357 return -ENOMEM;
360 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
361 if (err) {
362 pr_err("failed to register transparent hugepage group\n");
363 goto delete_obj;
366 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
367 if (err) {
368 pr_err("failed to register transparent hugepage group\n");
369 goto remove_hp_group;
372 return 0;
374 remove_hp_group:
375 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
376 delete_obj:
377 kobject_put(*hugepage_kobj);
378 return err;
381 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
383 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
384 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
385 kobject_put(hugepage_kobj);
387 #else
388 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
390 return 0;
393 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
396 #endif /* CONFIG_SYSFS */
398 static int __init hugepage_init(void)
400 int err;
401 struct kobject *hugepage_kobj;
403 if (!has_transparent_hugepage()) {
404 transparent_hugepage_flags = 0;
405 return -EINVAL;
409 * hugepages can't be allocated by the buddy allocator
411 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
413 * we use page->mapping and page->index in second tail page
414 * as list_head: assuming THP order >= 2
416 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
418 err = hugepage_init_sysfs(&hugepage_kobj);
419 if (err)
420 goto err_sysfs;
422 err = khugepaged_init();
423 if (err)
424 goto err_slab;
426 err = register_shrinker(&huge_zero_page_shrinker);
427 if (err)
428 goto err_hzp_shrinker;
429 err = register_shrinker(&deferred_split_shrinker);
430 if (err)
431 goto err_split_shrinker;
434 * By default disable transparent hugepages on smaller systems,
435 * where the extra memory used could hurt more than TLB overhead
436 * is likely to save. The admin can still enable it through /sys.
438 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
439 transparent_hugepage_flags = 0;
440 return 0;
443 err = start_stop_khugepaged();
444 if (err)
445 goto err_khugepaged;
447 return 0;
448 err_khugepaged:
449 unregister_shrinker(&deferred_split_shrinker);
450 err_split_shrinker:
451 unregister_shrinker(&huge_zero_page_shrinker);
452 err_hzp_shrinker:
453 khugepaged_destroy();
454 err_slab:
455 hugepage_exit_sysfs(hugepage_kobj);
456 err_sysfs:
457 return err;
459 subsys_initcall(hugepage_init);
461 static int __init setup_transparent_hugepage(char *str)
463 int ret = 0;
464 if (!str)
465 goto out;
466 if (!strcmp(str, "always")) {
467 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
468 &transparent_hugepage_flags);
469 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
470 &transparent_hugepage_flags);
471 ret = 1;
472 } else if (!strcmp(str, "madvise")) {
473 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
474 &transparent_hugepage_flags);
475 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
476 &transparent_hugepage_flags);
477 ret = 1;
478 } else if (!strcmp(str, "never")) {
479 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
480 &transparent_hugepage_flags);
481 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
482 &transparent_hugepage_flags);
483 ret = 1;
485 out:
486 if (!ret)
487 pr_warn("transparent_hugepage= cannot parse, ignored\n");
488 return ret;
490 __setup("transparent_hugepage=", setup_transparent_hugepage);
492 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
494 if (likely(vma->vm_flags & VM_WRITE))
495 pmd = pmd_mkwrite(pmd);
496 return pmd;
499 #ifdef CONFIG_MEMCG
500 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
502 struct mem_cgroup *memcg = compound_head(page)->mem_cgroup;
503 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
505 if (memcg)
506 return &memcg->deferred_split_queue;
507 else
508 return &pgdat->deferred_split_queue;
510 #else
511 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
513 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
515 return &pgdat->deferred_split_queue;
517 #endif
519 void prep_transhuge_page(struct page *page)
522 * we use page->mapping and page->indexlru in second tail page
523 * as list_head: assuming THP order >= 2
526 INIT_LIST_HEAD(page_deferred_list(page));
527 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
530 static unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
531 loff_t off, unsigned long flags, unsigned long size)
533 unsigned long addr;
534 loff_t off_end = off + len;
535 loff_t off_align = round_up(off, size);
536 unsigned long len_pad;
538 if (off_end <= off_align || (off_end - off_align) < size)
539 return 0;
541 len_pad = len + size;
542 if (len_pad < len || (off + len_pad) < off)
543 return 0;
545 addr = current->mm->get_unmapped_area(filp, 0, len_pad,
546 off >> PAGE_SHIFT, flags);
547 if (IS_ERR_VALUE(addr))
548 return 0;
550 addr += (off - addr) & (size - 1);
551 return addr;
554 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
555 unsigned long len, unsigned long pgoff, unsigned long flags)
557 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
559 if (addr)
560 goto out;
561 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
562 goto out;
564 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
565 if (addr)
566 return addr;
568 out:
569 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
571 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
573 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
574 struct page *page, gfp_t gfp)
576 struct vm_area_struct *vma = vmf->vma;
577 struct mem_cgroup *memcg;
578 pgtable_t pgtable;
579 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
580 vm_fault_t ret = 0;
582 VM_BUG_ON_PAGE(!PageCompound(page), page);
584 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) {
585 put_page(page);
586 count_vm_event(THP_FAULT_FALLBACK);
587 return VM_FAULT_FALLBACK;
590 pgtable = pte_alloc_one(vma->vm_mm);
591 if (unlikely(!pgtable)) {
592 ret = VM_FAULT_OOM;
593 goto release;
596 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
598 * The memory barrier inside __SetPageUptodate makes sure that
599 * clear_huge_page writes become visible before the set_pmd_at()
600 * write.
602 __SetPageUptodate(page);
604 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
605 if (unlikely(!pmd_none(*vmf->pmd))) {
606 goto unlock_release;
607 } else {
608 pmd_t entry;
610 ret = check_stable_address_space(vma->vm_mm);
611 if (ret)
612 goto unlock_release;
614 /* Deliver the page fault to userland */
615 if (userfaultfd_missing(vma)) {
616 vm_fault_t ret2;
618 spin_unlock(vmf->ptl);
619 mem_cgroup_cancel_charge(page, memcg, true);
620 put_page(page);
621 pte_free(vma->vm_mm, pgtable);
622 ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
623 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK);
624 return ret2;
627 entry = mk_huge_pmd(page, vma->vm_page_prot);
628 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
629 page_add_new_anon_rmap(page, vma, haddr, true);
630 mem_cgroup_commit_charge(page, memcg, false, true);
631 lru_cache_add_active_or_unevictable(page, vma);
632 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
633 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
634 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
635 mm_inc_nr_ptes(vma->vm_mm);
636 spin_unlock(vmf->ptl);
637 count_vm_event(THP_FAULT_ALLOC);
638 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
641 return 0;
642 unlock_release:
643 spin_unlock(vmf->ptl);
644 release:
645 if (pgtable)
646 pte_free(vma->vm_mm, pgtable);
647 mem_cgroup_cancel_charge(page, memcg, true);
648 put_page(page);
649 return ret;
654 * always: directly stall for all thp allocations
655 * defer: wake kswapd and fail if not immediately available
656 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
657 * fail if not immediately available
658 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
659 * available
660 * never: never stall for any thp allocation
662 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
664 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
666 /* Always do synchronous compaction */
667 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
668 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
670 /* Kick kcompactd and fail quickly */
671 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
672 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
674 /* Synchronous compaction if madvised, otherwise kick kcompactd */
675 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
676 return GFP_TRANSHUGE_LIGHT |
677 (vma_madvised ? __GFP_DIRECT_RECLAIM :
678 __GFP_KSWAPD_RECLAIM);
680 /* Only do synchronous compaction if madvised */
681 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
682 return GFP_TRANSHUGE_LIGHT |
683 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
685 return GFP_TRANSHUGE_LIGHT;
688 /* Caller must hold page table lock. */
689 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
690 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
691 struct page *zero_page)
693 pmd_t entry;
694 if (!pmd_none(*pmd))
695 return false;
696 entry = mk_pmd(zero_page, vma->vm_page_prot);
697 entry = pmd_mkhuge(entry);
698 if (pgtable)
699 pgtable_trans_huge_deposit(mm, pmd, pgtable);
700 set_pmd_at(mm, haddr, pmd, entry);
701 mm_inc_nr_ptes(mm);
702 return true;
705 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
707 struct vm_area_struct *vma = vmf->vma;
708 gfp_t gfp;
709 struct page *page;
710 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
712 if (!transhuge_vma_suitable(vma, haddr))
713 return VM_FAULT_FALLBACK;
714 if (unlikely(anon_vma_prepare(vma)))
715 return VM_FAULT_OOM;
716 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
717 return VM_FAULT_OOM;
718 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
719 !mm_forbids_zeropage(vma->vm_mm) &&
720 transparent_hugepage_use_zero_page()) {
721 pgtable_t pgtable;
722 struct page *zero_page;
723 bool set;
724 vm_fault_t ret;
725 pgtable = pte_alloc_one(vma->vm_mm);
726 if (unlikely(!pgtable))
727 return VM_FAULT_OOM;
728 zero_page = mm_get_huge_zero_page(vma->vm_mm);
729 if (unlikely(!zero_page)) {
730 pte_free(vma->vm_mm, pgtable);
731 count_vm_event(THP_FAULT_FALLBACK);
732 return VM_FAULT_FALLBACK;
734 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
735 ret = 0;
736 set = false;
737 if (pmd_none(*vmf->pmd)) {
738 ret = check_stable_address_space(vma->vm_mm);
739 if (ret) {
740 spin_unlock(vmf->ptl);
741 } else if (userfaultfd_missing(vma)) {
742 spin_unlock(vmf->ptl);
743 ret = handle_userfault(vmf, VM_UFFD_MISSING);
744 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
745 } else {
746 set_huge_zero_page(pgtable, vma->vm_mm, vma,
747 haddr, vmf->pmd, zero_page);
748 spin_unlock(vmf->ptl);
749 set = true;
751 } else
752 spin_unlock(vmf->ptl);
753 if (!set)
754 pte_free(vma->vm_mm, pgtable);
755 return ret;
757 gfp = alloc_hugepage_direct_gfpmask(vma);
758 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
759 if (unlikely(!page)) {
760 count_vm_event(THP_FAULT_FALLBACK);
761 return VM_FAULT_FALLBACK;
763 prep_transhuge_page(page);
764 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
767 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
768 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
769 pgtable_t pgtable)
771 struct mm_struct *mm = vma->vm_mm;
772 pmd_t entry;
773 spinlock_t *ptl;
775 ptl = pmd_lock(mm, pmd);
776 if (!pmd_none(*pmd)) {
777 if (write) {
778 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
779 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
780 goto out_unlock;
782 entry = pmd_mkyoung(*pmd);
783 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
784 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
785 update_mmu_cache_pmd(vma, addr, pmd);
788 goto out_unlock;
791 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
792 if (pfn_t_devmap(pfn))
793 entry = pmd_mkdevmap(entry);
794 if (write) {
795 entry = pmd_mkyoung(pmd_mkdirty(entry));
796 entry = maybe_pmd_mkwrite(entry, vma);
799 if (pgtable) {
800 pgtable_trans_huge_deposit(mm, pmd, pgtable);
801 mm_inc_nr_ptes(mm);
802 pgtable = NULL;
805 set_pmd_at(mm, addr, pmd, entry);
806 update_mmu_cache_pmd(vma, addr, pmd);
808 out_unlock:
809 spin_unlock(ptl);
810 if (pgtable)
811 pte_free(mm, pgtable);
814 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
816 unsigned long addr = vmf->address & PMD_MASK;
817 struct vm_area_struct *vma = vmf->vma;
818 pgprot_t pgprot = vma->vm_page_prot;
819 pgtable_t pgtable = NULL;
822 * If we had pmd_special, we could avoid all these restrictions,
823 * but we need to be consistent with PTEs and architectures that
824 * can't support a 'special' bit.
826 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
827 !pfn_t_devmap(pfn));
828 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
829 (VM_PFNMAP|VM_MIXEDMAP));
830 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
832 if (addr < vma->vm_start || addr >= vma->vm_end)
833 return VM_FAULT_SIGBUS;
835 if (arch_needs_pgtable_deposit()) {
836 pgtable = pte_alloc_one(vma->vm_mm);
837 if (!pgtable)
838 return VM_FAULT_OOM;
841 track_pfn_insert(vma, &pgprot, pfn);
843 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
844 return VM_FAULT_NOPAGE;
846 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
848 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
849 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
851 if (likely(vma->vm_flags & VM_WRITE))
852 pud = pud_mkwrite(pud);
853 return pud;
856 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
857 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
859 struct mm_struct *mm = vma->vm_mm;
860 pud_t entry;
861 spinlock_t *ptl;
863 ptl = pud_lock(mm, pud);
864 if (!pud_none(*pud)) {
865 if (write) {
866 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
867 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
868 goto out_unlock;
870 entry = pud_mkyoung(*pud);
871 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
872 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
873 update_mmu_cache_pud(vma, addr, pud);
875 goto out_unlock;
878 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
879 if (pfn_t_devmap(pfn))
880 entry = pud_mkdevmap(entry);
881 if (write) {
882 entry = pud_mkyoung(pud_mkdirty(entry));
883 entry = maybe_pud_mkwrite(entry, vma);
885 set_pud_at(mm, addr, pud, entry);
886 update_mmu_cache_pud(vma, addr, pud);
888 out_unlock:
889 spin_unlock(ptl);
892 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
894 unsigned long addr = vmf->address & PUD_MASK;
895 struct vm_area_struct *vma = vmf->vma;
896 pgprot_t pgprot = vma->vm_page_prot;
899 * If we had pud_special, we could avoid all these restrictions,
900 * but we need to be consistent with PTEs and architectures that
901 * can't support a 'special' bit.
903 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
904 !pfn_t_devmap(pfn));
905 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
906 (VM_PFNMAP|VM_MIXEDMAP));
907 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
909 if (addr < vma->vm_start || addr >= vma->vm_end)
910 return VM_FAULT_SIGBUS;
912 track_pfn_insert(vma, &pgprot, pfn);
914 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
915 return VM_FAULT_NOPAGE;
917 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
918 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
920 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
921 pmd_t *pmd, int flags)
923 pmd_t _pmd;
925 _pmd = pmd_mkyoung(*pmd);
926 if (flags & FOLL_WRITE)
927 _pmd = pmd_mkdirty(_pmd);
928 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
929 pmd, _pmd, flags & FOLL_WRITE))
930 update_mmu_cache_pmd(vma, addr, pmd);
933 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
934 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
936 unsigned long pfn = pmd_pfn(*pmd);
937 struct mm_struct *mm = vma->vm_mm;
938 struct page *page;
940 assert_spin_locked(pmd_lockptr(mm, pmd));
943 * When we COW a devmap PMD entry, we split it into PTEs, so we should
944 * not be in this function with `flags & FOLL_COW` set.
946 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
948 if (flags & FOLL_WRITE && !pmd_write(*pmd))
949 return NULL;
951 if (pmd_present(*pmd) && pmd_devmap(*pmd))
952 /* pass */;
953 else
954 return NULL;
956 if (flags & FOLL_TOUCH)
957 touch_pmd(vma, addr, pmd, flags);
960 * device mapped pages can only be returned if the
961 * caller will manage the page reference count.
963 if (!(flags & FOLL_GET))
964 return ERR_PTR(-EEXIST);
966 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
967 *pgmap = get_dev_pagemap(pfn, *pgmap);
968 if (!*pgmap)
969 return ERR_PTR(-EFAULT);
970 page = pfn_to_page(pfn);
971 get_page(page);
973 return page;
976 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
977 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
978 struct vm_area_struct *vma)
980 spinlock_t *dst_ptl, *src_ptl;
981 struct page *src_page;
982 pmd_t pmd;
983 pgtable_t pgtable = NULL;
984 int ret = -ENOMEM;
986 /* Skip if can be re-fill on fault */
987 if (!vma_is_anonymous(vma))
988 return 0;
990 pgtable = pte_alloc_one(dst_mm);
991 if (unlikely(!pgtable))
992 goto out;
994 dst_ptl = pmd_lock(dst_mm, dst_pmd);
995 src_ptl = pmd_lockptr(src_mm, src_pmd);
996 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
998 ret = -EAGAIN;
999 pmd = *src_pmd;
1001 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1002 if (unlikely(is_swap_pmd(pmd))) {
1003 swp_entry_t entry = pmd_to_swp_entry(pmd);
1005 VM_BUG_ON(!is_pmd_migration_entry(pmd));
1006 if (is_write_migration_entry(entry)) {
1007 make_migration_entry_read(&entry);
1008 pmd = swp_entry_to_pmd(entry);
1009 if (pmd_swp_soft_dirty(*src_pmd))
1010 pmd = pmd_swp_mksoft_dirty(pmd);
1011 set_pmd_at(src_mm, addr, src_pmd, pmd);
1013 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1014 mm_inc_nr_ptes(dst_mm);
1015 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1016 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1017 ret = 0;
1018 goto out_unlock;
1020 #endif
1022 if (unlikely(!pmd_trans_huge(pmd))) {
1023 pte_free(dst_mm, pgtable);
1024 goto out_unlock;
1027 * When page table lock is held, the huge zero pmd should not be
1028 * under splitting since we don't split the page itself, only pmd to
1029 * a page table.
1031 if (is_huge_zero_pmd(pmd)) {
1032 struct page *zero_page;
1034 * get_huge_zero_page() will never allocate a new page here,
1035 * since we already have a zero page to copy. It just takes a
1036 * reference.
1038 zero_page = mm_get_huge_zero_page(dst_mm);
1039 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
1040 zero_page);
1041 ret = 0;
1042 goto out_unlock;
1045 src_page = pmd_page(pmd);
1046 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1047 get_page(src_page);
1048 page_dup_rmap(src_page, true);
1049 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1050 mm_inc_nr_ptes(dst_mm);
1051 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1053 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1054 pmd = pmd_mkold(pmd_wrprotect(pmd));
1055 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1057 ret = 0;
1058 out_unlock:
1059 spin_unlock(src_ptl);
1060 spin_unlock(dst_ptl);
1061 out:
1062 return ret;
1065 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1066 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1067 pud_t *pud, int flags)
1069 pud_t _pud;
1071 _pud = pud_mkyoung(*pud);
1072 if (flags & FOLL_WRITE)
1073 _pud = pud_mkdirty(_pud);
1074 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1075 pud, _pud, flags & FOLL_WRITE))
1076 update_mmu_cache_pud(vma, addr, pud);
1079 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1080 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1082 unsigned long pfn = pud_pfn(*pud);
1083 struct mm_struct *mm = vma->vm_mm;
1084 struct page *page;
1086 assert_spin_locked(pud_lockptr(mm, pud));
1088 if (flags & FOLL_WRITE && !pud_write(*pud))
1089 return NULL;
1091 if (pud_present(*pud) && pud_devmap(*pud))
1092 /* pass */;
1093 else
1094 return NULL;
1096 if (flags & FOLL_TOUCH)
1097 touch_pud(vma, addr, pud, flags);
1100 * device mapped pages can only be returned if the
1101 * caller will manage the page reference count.
1103 if (!(flags & FOLL_GET))
1104 return ERR_PTR(-EEXIST);
1106 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1107 *pgmap = get_dev_pagemap(pfn, *pgmap);
1108 if (!*pgmap)
1109 return ERR_PTR(-EFAULT);
1110 page = pfn_to_page(pfn);
1111 get_page(page);
1113 return page;
1116 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1117 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1118 struct vm_area_struct *vma)
1120 spinlock_t *dst_ptl, *src_ptl;
1121 pud_t pud;
1122 int ret;
1124 dst_ptl = pud_lock(dst_mm, dst_pud);
1125 src_ptl = pud_lockptr(src_mm, src_pud);
1126 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1128 ret = -EAGAIN;
1129 pud = *src_pud;
1130 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1131 goto out_unlock;
1134 * When page table lock is held, the huge zero pud should not be
1135 * under splitting since we don't split the page itself, only pud to
1136 * a page table.
1138 if (is_huge_zero_pud(pud)) {
1139 /* No huge zero pud yet */
1142 pudp_set_wrprotect(src_mm, addr, src_pud);
1143 pud = pud_mkold(pud_wrprotect(pud));
1144 set_pud_at(dst_mm, addr, dst_pud, pud);
1146 ret = 0;
1147 out_unlock:
1148 spin_unlock(src_ptl);
1149 spin_unlock(dst_ptl);
1150 return ret;
1153 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1155 pud_t entry;
1156 unsigned long haddr;
1157 bool write = vmf->flags & FAULT_FLAG_WRITE;
1159 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1160 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1161 goto unlock;
1163 entry = pud_mkyoung(orig_pud);
1164 if (write)
1165 entry = pud_mkdirty(entry);
1166 haddr = vmf->address & HPAGE_PUD_MASK;
1167 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1168 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1170 unlock:
1171 spin_unlock(vmf->ptl);
1173 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1175 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1177 pmd_t entry;
1178 unsigned long haddr;
1179 bool write = vmf->flags & FAULT_FLAG_WRITE;
1181 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1182 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1183 goto unlock;
1185 entry = pmd_mkyoung(orig_pmd);
1186 if (write)
1187 entry = pmd_mkdirty(entry);
1188 haddr = vmf->address & HPAGE_PMD_MASK;
1189 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1190 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1192 unlock:
1193 spin_unlock(vmf->ptl);
1196 static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf,
1197 pmd_t orig_pmd, struct page *page)
1199 struct vm_area_struct *vma = vmf->vma;
1200 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1201 struct mem_cgroup *memcg;
1202 pgtable_t pgtable;
1203 pmd_t _pmd;
1204 int i;
1205 vm_fault_t ret = 0;
1206 struct page **pages;
1207 struct mmu_notifier_range range;
1209 pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *),
1210 GFP_KERNEL);
1211 if (unlikely(!pages)) {
1212 ret |= VM_FAULT_OOM;
1213 goto out;
1216 for (i = 0; i < HPAGE_PMD_NR; i++) {
1217 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1218 vmf->address, page_to_nid(page));
1219 if (unlikely(!pages[i] ||
1220 mem_cgroup_try_charge_delay(pages[i], vma->vm_mm,
1221 GFP_KERNEL, &memcg, false))) {
1222 if (pages[i])
1223 put_page(pages[i]);
1224 while (--i >= 0) {
1225 memcg = (void *)page_private(pages[i]);
1226 set_page_private(pages[i], 0);
1227 mem_cgroup_cancel_charge(pages[i], memcg,
1228 false);
1229 put_page(pages[i]);
1231 kfree(pages);
1232 ret |= VM_FAULT_OOM;
1233 goto out;
1235 set_page_private(pages[i], (unsigned long)memcg);
1238 for (i = 0; i < HPAGE_PMD_NR; i++) {
1239 copy_user_highpage(pages[i], page + i,
1240 haddr + PAGE_SIZE * i, vma);
1241 __SetPageUptodate(pages[i]);
1242 cond_resched();
1245 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1246 haddr, haddr + HPAGE_PMD_SIZE);
1247 mmu_notifier_invalidate_range_start(&range);
1249 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1250 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1251 goto out_free_pages;
1252 VM_BUG_ON_PAGE(!PageHead(page), page);
1255 * Leave pmd empty until pte is filled note we must notify here as
1256 * concurrent CPU thread might write to new page before the call to
1257 * mmu_notifier_invalidate_range_end() happens which can lead to a
1258 * device seeing memory write in different order than CPU.
1260 * See Documentation/vm/mmu_notifier.rst
1262 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1264 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1265 pmd_populate(vma->vm_mm, &_pmd, pgtable);
1267 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1268 pte_t entry;
1269 entry = mk_pte(pages[i], vma->vm_page_prot);
1270 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1271 memcg = (void *)page_private(pages[i]);
1272 set_page_private(pages[i], 0);
1273 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1274 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1275 lru_cache_add_active_or_unevictable(pages[i], vma);
1276 vmf->pte = pte_offset_map(&_pmd, haddr);
1277 VM_BUG_ON(!pte_none(*vmf->pte));
1278 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1279 pte_unmap(vmf->pte);
1281 kfree(pages);
1283 smp_wmb(); /* make pte visible before pmd */
1284 pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1285 page_remove_rmap(page, true);
1286 spin_unlock(vmf->ptl);
1289 * No need to double call mmu_notifier->invalidate_range() callback as
1290 * the above pmdp_huge_clear_flush_notify() did already call it.
1292 mmu_notifier_invalidate_range_only_end(&range);
1294 ret |= VM_FAULT_WRITE;
1295 put_page(page);
1297 out:
1298 return ret;
1300 out_free_pages:
1301 spin_unlock(vmf->ptl);
1302 mmu_notifier_invalidate_range_end(&range);
1303 for (i = 0; i < HPAGE_PMD_NR; i++) {
1304 memcg = (void *)page_private(pages[i]);
1305 set_page_private(pages[i], 0);
1306 mem_cgroup_cancel_charge(pages[i], memcg, false);
1307 put_page(pages[i]);
1309 kfree(pages);
1310 goto out;
1313 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1315 struct vm_area_struct *vma = vmf->vma;
1316 struct page *page = NULL, *new_page;
1317 struct mem_cgroup *memcg;
1318 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1319 struct mmu_notifier_range range;
1320 gfp_t huge_gfp; /* for allocation and charge */
1321 vm_fault_t ret = 0;
1323 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1324 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1325 if (is_huge_zero_pmd(orig_pmd))
1326 goto alloc;
1327 spin_lock(vmf->ptl);
1328 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1329 goto out_unlock;
1331 page = pmd_page(orig_pmd);
1332 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1334 * We can only reuse the page if nobody else maps the huge page or it's
1335 * part.
1337 if (!trylock_page(page)) {
1338 get_page(page);
1339 spin_unlock(vmf->ptl);
1340 lock_page(page);
1341 spin_lock(vmf->ptl);
1342 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1343 unlock_page(page);
1344 put_page(page);
1345 goto out_unlock;
1347 put_page(page);
1349 if (reuse_swap_page(page, NULL)) {
1350 pmd_t entry;
1351 entry = pmd_mkyoung(orig_pmd);
1352 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1353 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1354 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1355 ret |= VM_FAULT_WRITE;
1356 unlock_page(page);
1357 goto out_unlock;
1359 unlock_page(page);
1360 get_page(page);
1361 spin_unlock(vmf->ptl);
1362 alloc:
1363 if (__transparent_hugepage_enabled(vma) &&
1364 !transparent_hugepage_debug_cow()) {
1365 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1366 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1367 } else
1368 new_page = NULL;
1370 if (likely(new_page)) {
1371 prep_transhuge_page(new_page);
1372 } else {
1373 if (!page) {
1374 split_huge_pmd(vma, vmf->pmd, vmf->address);
1375 ret |= VM_FAULT_FALLBACK;
1376 } else {
1377 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1378 if (ret & VM_FAULT_OOM) {
1379 split_huge_pmd(vma, vmf->pmd, vmf->address);
1380 ret |= VM_FAULT_FALLBACK;
1382 put_page(page);
1384 count_vm_event(THP_FAULT_FALLBACK);
1385 goto out;
1388 if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm,
1389 huge_gfp, &memcg, true))) {
1390 put_page(new_page);
1391 split_huge_pmd(vma, vmf->pmd, vmf->address);
1392 if (page)
1393 put_page(page);
1394 ret |= VM_FAULT_FALLBACK;
1395 count_vm_event(THP_FAULT_FALLBACK);
1396 goto out;
1399 count_vm_event(THP_FAULT_ALLOC);
1400 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
1402 if (!page)
1403 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1404 else
1405 copy_user_huge_page(new_page, page, vmf->address,
1406 vma, HPAGE_PMD_NR);
1407 __SetPageUptodate(new_page);
1409 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1410 haddr, haddr + HPAGE_PMD_SIZE);
1411 mmu_notifier_invalidate_range_start(&range);
1413 spin_lock(vmf->ptl);
1414 if (page)
1415 put_page(page);
1416 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1417 spin_unlock(vmf->ptl);
1418 mem_cgroup_cancel_charge(new_page, memcg, true);
1419 put_page(new_page);
1420 goto out_mn;
1421 } else {
1422 pmd_t entry;
1423 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1424 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1425 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1426 page_add_new_anon_rmap(new_page, vma, haddr, true);
1427 mem_cgroup_commit_charge(new_page, memcg, false, true);
1428 lru_cache_add_active_or_unevictable(new_page, vma);
1429 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1430 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1431 if (!page) {
1432 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1433 } else {
1434 VM_BUG_ON_PAGE(!PageHead(page), page);
1435 page_remove_rmap(page, true);
1436 put_page(page);
1438 ret |= VM_FAULT_WRITE;
1440 spin_unlock(vmf->ptl);
1441 out_mn:
1443 * No need to double call mmu_notifier->invalidate_range() callback as
1444 * the above pmdp_huge_clear_flush_notify() did already call it.
1446 mmu_notifier_invalidate_range_only_end(&range);
1447 out:
1448 return ret;
1449 out_unlock:
1450 spin_unlock(vmf->ptl);
1451 return ret;
1455 * FOLL_FORCE can write to even unwritable pmd's, but only
1456 * after we've gone through a COW cycle and they are dirty.
1458 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1460 return pmd_write(pmd) ||
1461 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1464 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1465 unsigned long addr,
1466 pmd_t *pmd,
1467 unsigned int flags)
1469 struct mm_struct *mm = vma->vm_mm;
1470 struct page *page = NULL;
1472 assert_spin_locked(pmd_lockptr(mm, pmd));
1474 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1475 goto out;
1477 /* Avoid dumping huge zero page */
1478 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1479 return ERR_PTR(-EFAULT);
1481 /* Full NUMA hinting faults to serialise migration in fault paths */
1482 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1483 goto out;
1485 page = pmd_page(*pmd);
1486 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1487 if (flags & FOLL_TOUCH)
1488 touch_pmd(vma, addr, pmd, flags);
1489 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1491 * We don't mlock() pte-mapped THPs. This way we can avoid
1492 * leaking mlocked pages into non-VM_LOCKED VMAs.
1494 * For anon THP:
1496 * In most cases the pmd is the only mapping of the page as we
1497 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1498 * writable private mappings in populate_vma_page_range().
1500 * The only scenario when we have the page shared here is if we
1501 * mlocking read-only mapping shared over fork(). We skip
1502 * mlocking such pages.
1504 * For file THP:
1506 * We can expect PageDoubleMap() to be stable under page lock:
1507 * for file pages we set it in page_add_file_rmap(), which
1508 * requires page to be locked.
1511 if (PageAnon(page) && compound_mapcount(page) != 1)
1512 goto skip_mlock;
1513 if (PageDoubleMap(page) || !page->mapping)
1514 goto skip_mlock;
1515 if (!trylock_page(page))
1516 goto skip_mlock;
1517 lru_add_drain();
1518 if (page->mapping && !PageDoubleMap(page))
1519 mlock_vma_page(page);
1520 unlock_page(page);
1522 skip_mlock:
1523 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1524 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1525 if (flags & FOLL_GET)
1526 get_page(page);
1528 out:
1529 return page;
1532 /* NUMA hinting page fault entry point for trans huge pmds */
1533 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1535 struct vm_area_struct *vma = vmf->vma;
1536 struct anon_vma *anon_vma = NULL;
1537 struct page *page;
1538 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1539 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id();
1540 int target_nid, last_cpupid = -1;
1541 bool page_locked;
1542 bool migrated = false;
1543 bool was_writable;
1544 int flags = 0;
1546 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1547 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1548 goto out_unlock;
1551 * If there are potential migrations, wait for completion and retry
1552 * without disrupting NUMA hinting information. Do not relock and
1553 * check_same as the page may no longer be mapped.
1555 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1556 page = pmd_page(*vmf->pmd);
1557 if (!get_page_unless_zero(page))
1558 goto out_unlock;
1559 spin_unlock(vmf->ptl);
1560 put_and_wait_on_page_locked(page);
1561 goto out;
1564 page = pmd_page(pmd);
1565 BUG_ON(is_huge_zero_page(page));
1566 page_nid = page_to_nid(page);
1567 last_cpupid = page_cpupid_last(page);
1568 count_vm_numa_event(NUMA_HINT_FAULTS);
1569 if (page_nid == this_nid) {
1570 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1571 flags |= TNF_FAULT_LOCAL;
1574 /* See similar comment in do_numa_page for explanation */
1575 if (!pmd_savedwrite(pmd))
1576 flags |= TNF_NO_GROUP;
1579 * Acquire the page lock to serialise THP migrations but avoid dropping
1580 * page_table_lock if at all possible
1582 page_locked = trylock_page(page);
1583 target_nid = mpol_misplaced(page, vma, haddr);
1584 if (target_nid == NUMA_NO_NODE) {
1585 /* If the page was locked, there are no parallel migrations */
1586 if (page_locked)
1587 goto clear_pmdnuma;
1590 /* Migration could have started since the pmd_trans_migrating check */
1591 if (!page_locked) {
1592 page_nid = NUMA_NO_NODE;
1593 if (!get_page_unless_zero(page))
1594 goto out_unlock;
1595 spin_unlock(vmf->ptl);
1596 put_and_wait_on_page_locked(page);
1597 goto out;
1601 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1602 * to serialises splits
1604 get_page(page);
1605 spin_unlock(vmf->ptl);
1606 anon_vma = page_lock_anon_vma_read(page);
1608 /* Confirm the PMD did not change while page_table_lock was released */
1609 spin_lock(vmf->ptl);
1610 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1611 unlock_page(page);
1612 put_page(page);
1613 page_nid = NUMA_NO_NODE;
1614 goto out_unlock;
1617 /* Bail if we fail to protect against THP splits for any reason */
1618 if (unlikely(!anon_vma)) {
1619 put_page(page);
1620 page_nid = NUMA_NO_NODE;
1621 goto clear_pmdnuma;
1625 * Since we took the NUMA fault, we must have observed the !accessible
1626 * bit. Make sure all other CPUs agree with that, to avoid them
1627 * modifying the page we're about to migrate.
1629 * Must be done under PTL such that we'll observe the relevant
1630 * inc_tlb_flush_pending().
1632 * We are not sure a pending tlb flush here is for a huge page
1633 * mapping or not. Hence use the tlb range variant
1635 if (mm_tlb_flush_pending(vma->vm_mm)) {
1636 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1638 * change_huge_pmd() released the pmd lock before
1639 * invalidating the secondary MMUs sharing the primary
1640 * MMU pagetables (with ->invalidate_range()). The
1641 * mmu_notifier_invalidate_range_end() (which
1642 * internally calls ->invalidate_range()) in
1643 * change_pmd_range() will run after us, so we can't
1644 * rely on it here and we need an explicit invalidate.
1646 mmu_notifier_invalidate_range(vma->vm_mm, haddr,
1647 haddr + HPAGE_PMD_SIZE);
1651 * Migrate the THP to the requested node, returns with page unlocked
1652 * and access rights restored.
1654 spin_unlock(vmf->ptl);
1656 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1657 vmf->pmd, pmd, vmf->address, page, target_nid);
1658 if (migrated) {
1659 flags |= TNF_MIGRATED;
1660 page_nid = target_nid;
1661 } else
1662 flags |= TNF_MIGRATE_FAIL;
1664 goto out;
1665 clear_pmdnuma:
1666 BUG_ON(!PageLocked(page));
1667 was_writable = pmd_savedwrite(pmd);
1668 pmd = pmd_modify(pmd, vma->vm_page_prot);
1669 pmd = pmd_mkyoung(pmd);
1670 if (was_writable)
1671 pmd = pmd_mkwrite(pmd);
1672 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1673 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1674 unlock_page(page);
1675 out_unlock:
1676 spin_unlock(vmf->ptl);
1678 out:
1679 if (anon_vma)
1680 page_unlock_anon_vma_read(anon_vma);
1682 if (page_nid != NUMA_NO_NODE)
1683 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1684 flags);
1686 return 0;
1690 * Return true if we do MADV_FREE successfully on entire pmd page.
1691 * Otherwise, return false.
1693 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1694 pmd_t *pmd, unsigned long addr, unsigned long next)
1696 spinlock_t *ptl;
1697 pmd_t orig_pmd;
1698 struct page *page;
1699 struct mm_struct *mm = tlb->mm;
1700 bool ret = false;
1702 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1704 ptl = pmd_trans_huge_lock(pmd, vma);
1705 if (!ptl)
1706 goto out_unlocked;
1708 orig_pmd = *pmd;
1709 if (is_huge_zero_pmd(orig_pmd))
1710 goto out;
1712 if (unlikely(!pmd_present(orig_pmd))) {
1713 VM_BUG_ON(thp_migration_supported() &&
1714 !is_pmd_migration_entry(orig_pmd));
1715 goto out;
1718 page = pmd_page(orig_pmd);
1720 * If other processes are mapping this page, we couldn't discard
1721 * the page unless they all do MADV_FREE so let's skip the page.
1723 if (page_mapcount(page) != 1)
1724 goto out;
1726 if (!trylock_page(page))
1727 goto out;
1730 * If user want to discard part-pages of THP, split it so MADV_FREE
1731 * will deactivate only them.
1733 if (next - addr != HPAGE_PMD_SIZE) {
1734 get_page(page);
1735 spin_unlock(ptl);
1736 split_huge_page(page);
1737 unlock_page(page);
1738 put_page(page);
1739 goto out_unlocked;
1742 if (PageDirty(page))
1743 ClearPageDirty(page);
1744 unlock_page(page);
1746 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1747 pmdp_invalidate(vma, addr, pmd);
1748 orig_pmd = pmd_mkold(orig_pmd);
1749 orig_pmd = pmd_mkclean(orig_pmd);
1751 set_pmd_at(mm, addr, pmd, orig_pmd);
1752 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1755 mark_page_lazyfree(page);
1756 ret = true;
1757 out:
1758 spin_unlock(ptl);
1759 out_unlocked:
1760 return ret;
1763 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1765 pgtable_t pgtable;
1767 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1768 pte_free(mm, pgtable);
1769 mm_dec_nr_ptes(mm);
1772 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1773 pmd_t *pmd, unsigned long addr)
1775 pmd_t orig_pmd;
1776 spinlock_t *ptl;
1778 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1780 ptl = __pmd_trans_huge_lock(pmd, vma);
1781 if (!ptl)
1782 return 0;
1784 * For architectures like ppc64 we look at deposited pgtable
1785 * when calling pmdp_huge_get_and_clear. So do the
1786 * pgtable_trans_huge_withdraw after finishing pmdp related
1787 * operations.
1789 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1790 tlb->fullmm);
1791 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1792 if (vma_is_dax(vma)) {
1793 if (arch_needs_pgtable_deposit())
1794 zap_deposited_table(tlb->mm, pmd);
1795 spin_unlock(ptl);
1796 if (is_huge_zero_pmd(orig_pmd))
1797 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1798 } else if (is_huge_zero_pmd(orig_pmd)) {
1799 zap_deposited_table(tlb->mm, pmd);
1800 spin_unlock(ptl);
1801 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1802 } else {
1803 struct page *page = NULL;
1804 int flush_needed = 1;
1806 if (pmd_present(orig_pmd)) {
1807 page = pmd_page(orig_pmd);
1808 page_remove_rmap(page, true);
1809 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1810 VM_BUG_ON_PAGE(!PageHead(page), page);
1811 } else if (thp_migration_supported()) {
1812 swp_entry_t entry;
1814 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1815 entry = pmd_to_swp_entry(orig_pmd);
1816 page = pfn_to_page(swp_offset(entry));
1817 flush_needed = 0;
1818 } else
1819 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1821 if (PageAnon(page)) {
1822 zap_deposited_table(tlb->mm, pmd);
1823 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1824 } else {
1825 if (arch_needs_pgtable_deposit())
1826 zap_deposited_table(tlb->mm, pmd);
1827 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1830 spin_unlock(ptl);
1831 if (flush_needed)
1832 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1834 return 1;
1837 #ifndef pmd_move_must_withdraw
1838 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1839 spinlock_t *old_pmd_ptl,
1840 struct vm_area_struct *vma)
1843 * With split pmd lock we also need to move preallocated
1844 * PTE page table if new_pmd is on different PMD page table.
1846 * We also don't deposit and withdraw tables for file pages.
1848 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1850 #endif
1852 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1854 #ifdef CONFIG_MEM_SOFT_DIRTY
1855 if (unlikely(is_pmd_migration_entry(pmd)))
1856 pmd = pmd_swp_mksoft_dirty(pmd);
1857 else if (pmd_present(pmd))
1858 pmd = pmd_mksoft_dirty(pmd);
1859 #endif
1860 return pmd;
1863 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1864 unsigned long new_addr, unsigned long old_end,
1865 pmd_t *old_pmd, pmd_t *new_pmd)
1867 spinlock_t *old_ptl, *new_ptl;
1868 pmd_t pmd;
1869 struct mm_struct *mm = vma->vm_mm;
1870 bool force_flush = false;
1872 if ((old_addr & ~HPAGE_PMD_MASK) ||
1873 (new_addr & ~HPAGE_PMD_MASK) ||
1874 old_end - old_addr < HPAGE_PMD_SIZE)
1875 return false;
1878 * The destination pmd shouldn't be established, free_pgtables()
1879 * should have release it.
1881 if (WARN_ON(!pmd_none(*new_pmd))) {
1882 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1883 return false;
1887 * We don't have to worry about the ordering of src and dst
1888 * ptlocks because exclusive mmap_sem prevents deadlock.
1890 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1891 if (old_ptl) {
1892 new_ptl = pmd_lockptr(mm, new_pmd);
1893 if (new_ptl != old_ptl)
1894 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1895 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1896 if (pmd_present(pmd))
1897 force_flush = true;
1898 VM_BUG_ON(!pmd_none(*new_pmd));
1900 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1901 pgtable_t pgtable;
1902 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1903 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1905 pmd = move_soft_dirty_pmd(pmd);
1906 set_pmd_at(mm, new_addr, new_pmd, pmd);
1907 if (force_flush)
1908 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1909 if (new_ptl != old_ptl)
1910 spin_unlock(new_ptl);
1911 spin_unlock(old_ptl);
1912 return true;
1914 return false;
1918 * Returns
1919 * - 0 if PMD could not be locked
1920 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1921 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1923 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1924 unsigned long addr, pgprot_t newprot, int prot_numa)
1926 struct mm_struct *mm = vma->vm_mm;
1927 spinlock_t *ptl;
1928 pmd_t entry;
1929 bool preserve_write;
1930 int ret;
1932 ptl = __pmd_trans_huge_lock(pmd, vma);
1933 if (!ptl)
1934 return 0;
1936 preserve_write = prot_numa && pmd_write(*pmd);
1937 ret = 1;
1939 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1940 if (is_swap_pmd(*pmd)) {
1941 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1943 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1944 if (is_write_migration_entry(entry)) {
1945 pmd_t newpmd;
1947 * A protection check is difficult so
1948 * just be safe and disable write
1950 make_migration_entry_read(&entry);
1951 newpmd = swp_entry_to_pmd(entry);
1952 if (pmd_swp_soft_dirty(*pmd))
1953 newpmd = pmd_swp_mksoft_dirty(newpmd);
1954 set_pmd_at(mm, addr, pmd, newpmd);
1956 goto unlock;
1958 #endif
1961 * Avoid trapping faults against the zero page. The read-only
1962 * data is likely to be read-cached on the local CPU and
1963 * local/remote hits to the zero page are not interesting.
1965 if (prot_numa && is_huge_zero_pmd(*pmd))
1966 goto unlock;
1968 if (prot_numa && pmd_protnone(*pmd))
1969 goto unlock;
1972 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1973 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1974 * which is also under down_read(mmap_sem):
1976 * CPU0: CPU1:
1977 * change_huge_pmd(prot_numa=1)
1978 * pmdp_huge_get_and_clear_notify()
1979 * madvise_dontneed()
1980 * zap_pmd_range()
1981 * pmd_trans_huge(*pmd) == 0 (without ptl)
1982 * // skip the pmd
1983 * set_pmd_at();
1984 * // pmd is re-established
1986 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1987 * which may break userspace.
1989 * pmdp_invalidate() is required to make sure we don't miss
1990 * dirty/young flags set by hardware.
1992 entry = pmdp_invalidate(vma, addr, pmd);
1994 entry = pmd_modify(entry, newprot);
1995 if (preserve_write)
1996 entry = pmd_mk_savedwrite(entry);
1997 ret = HPAGE_PMD_NR;
1998 set_pmd_at(mm, addr, pmd, entry);
1999 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
2000 unlock:
2001 spin_unlock(ptl);
2002 return ret;
2006 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
2008 * Note that if it returns page table lock pointer, this routine returns without
2009 * unlocking page table lock. So callers must unlock it.
2011 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
2013 spinlock_t *ptl;
2014 ptl = pmd_lock(vma->vm_mm, pmd);
2015 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
2016 pmd_devmap(*pmd)))
2017 return ptl;
2018 spin_unlock(ptl);
2019 return NULL;
2023 * Returns true if a given pud maps a thp, false otherwise.
2025 * Note that if it returns true, this routine returns without unlocking page
2026 * table lock. So callers must unlock it.
2028 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
2030 spinlock_t *ptl;
2032 ptl = pud_lock(vma->vm_mm, pud);
2033 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
2034 return ptl;
2035 spin_unlock(ptl);
2036 return NULL;
2039 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
2040 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
2041 pud_t *pud, unsigned long addr)
2043 spinlock_t *ptl;
2045 ptl = __pud_trans_huge_lock(pud, vma);
2046 if (!ptl)
2047 return 0;
2049 * For architectures like ppc64 we look at deposited pgtable
2050 * when calling pudp_huge_get_and_clear. So do the
2051 * pgtable_trans_huge_withdraw after finishing pudp related
2052 * operations.
2054 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
2055 tlb_remove_pud_tlb_entry(tlb, pud, addr);
2056 if (vma_is_dax(vma)) {
2057 spin_unlock(ptl);
2058 /* No zero page support yet */
2059 } else {
2060 /* No support for anonymous PUD pages yet */
2061 BUG();
2063 return 1;
2066 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2067 unsigned long haddr)
2069 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2070 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2071 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2072 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2074 count_vm_event(THP_SPLIT_PUD);
2076 pudp_huge_clear_flush_notify(vma, haddr, pud);
2079 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2080 unsigned long address)
2082 spinlock_t *ptl;
2083 struct mmu_notifier_range range;
2085 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2086 address & HPAGE_PUD_MASK,
2087 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
2088 mmu_notifier_invalidate_range_start(&range);
2089 ptl = pud_lock(vma->vm_mm, pud);
2090 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2091 goto out;
2092 __split_huge_pud_locked(vma, pud, range.start);
2094 out:
2095 spin_unlock(ptl);
2097 * No need to double call mmu_notifier->invalidate_range() callback as
2098 * the above pudp_huge_clear_flush_notify() did already call it.
2100 mmu_notifier_invalidate_range_only_end(&range);
2102 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2104 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2105 unsigned long haddr, pmd_t *pmd)
2107 struct mm_struct *mm = vma->vm_mm;
2108 pgtable_t pgtable;
2109 pmd_t _pmd;
2110 int i;
2113 * Leave pmd empty until pte is filled note that it is fine to delay
2114 * notification until mmu_notifier_invalidate_range_end() as we are
2115 * replacing a zero pmd write protected page with a zero pte write
2116 * protected page.
2118 * See Documentation/vm/mmu_notifier.rst
2120 pmdp_huge_clear_flush(vma, haddr, pmd);
2122 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2123 pmd_populate(mm, &_pmd, pgtable);
2125 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2126 pte_t *pte, entry;
2127 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2128 entry = pte_mkspecial(entry);
2129 pte = pte_offset_map(&_pmd, haddr);
2130 VM_BUG_ON(!pte_none(*pte));
2131 set_pte_at(mm, haddr, pte, entry);
2132 pte_unmap(pte);
2134 smp_wmb(); /* make pte visible before pmd */
2135 pmd_populate(mm, pmd, pgtable);
2138 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2139 unsigned long haddr, bool freeze)
2141 struct mm_struct *mm = vma->vm_mm;
2142 struct page *page;
2143 pgtable_t pgtable;
2144 pmd_t old_pmd, _pmd;
2145 bool young, write, soft_dirty, pmd_migration = false;
2146 unsigned long addr;
2147 int i;
2149 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2150 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2151 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2152 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2153 && !pmd_devmap(*pmd));
2155 count_vm_event(THP_SPLIT_PMD);
2157 if (!vma_is_anonymous(vma)) {
2158 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2160 * We are going to unmap this huge page. So
2161 * just go ahead and zap it
2163 if (arch_needs_pgtable_deposit())
2164 zap_deposited_table(mm, pmd);
2165 if (vma_is_dax(vma))
2166 return;
2167 page = pmd_page(_pmd);
2168 if (!PageDirty(page) && pmd_dirty(_pmd))
2169 set_page_dirty(page);
2170 if (!PageReferenced(page) && pmd_young(_pmd))
2171 SetPageReferenced(page);
2172 page_remove_rmap(page, true);
2173 put_page(page);
2174 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2175 return;
2176 } else if (is_huge_zero_pmd(*pmd)) {
2178 * FIXME: Do we want to invalidate secondary mmu by calling
2179 * mmu_notifier_invalidate_range() see comments below inside
2180 * __split_huge_pmd() ?
2182 * We are going from a zero huge page write protected to zero
2183 * small page also write protected so it does not seems useful
2184 * to invalidate secondary mmu at this time.
2186 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2190 * Up to this point the pmd is present and huge and userland has the
2191 * whole access to the hugepage during the split (which happens in
2192 * place). If we overwrite the pmd with the not-huge version pointing
2193 * to the pte here (which of course we could if all CPUs were bug
2194 * free), userland could trigger a small page size TLB miss on the
2195 * small sized TLB while the hugepage TLB entry is still established in
2196 * the huge TLB. Some CPU doesn't like that.
2197 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2198 * 383 on page 93. Intel should be safe but is also warns that it's
2199 * only safe if the permission and cache attributes of the two entries
2200 * loaded in the two TLB is identical (which should be the case here).
2201 * But it is generally safer to never allow small and huge TLB entries
2202 * for the same virtual address to be loaded simultaneously. So instead
2203 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2204 * current pmd notpresent (atomically because here the pmd_trans_huge
2205 * must remain set at all times on the pmd until the split is complete
2206 * for this pmd), then we flush the SMP TLB and finally we write the
2207 * non-huge version of the pmd entry with pmd_populate.
2209 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2211 pmd_migration = is_pmd_migration_entry(old_pmd);
2212 if (unlikely(pmd_migration)) {
2213 swp_entry_t entry;
2215 entry = pmd_to_swp_entry(old_pmd);
2216 page = pfn_to_page(swp_offset(entry));
2217 write = is_write_migration_entry(entry);
2218 young = false;
2219 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2220 } else {
2221 page = pmd_page(old_pmd);
2222 if (pmd_dirty(old_pmd))
2223 SetPageDirty(page);
2224 write = pmd_write(old_pmd);
2225 young = pmd_young(old_pmd);
2226 soft_dirty = pmd_soft_dirty(old_pmd);
2228 VM_BUG_ON_PAGE(!page_count(page), page);
2229 page_ref_add(page, HPAGE_PMD_NR - 1);
2232 * Withdraw the table only after we mark the pmd entry invalid.
2233 * This's critical for some architectures (Power).
2235 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2236 pmd_populate(mm, &_pmd, pgtable);
2238 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2239 pte_t entry, *pte;
2241 * Note that NUMA hinting access restrictions are not
2242 * transferred to avoid any possibility of altering
2243 * permissions across VMAs.
2245 if (freeze || pmd_migration) {
2246 swp_entry_t swp_entry;
2247 swp_entry = make_migration_entry(page + i, write);
2248 entry = swp_entry_to_pte(swp_entry);
2249 if (soft_dirty)
2250 entry = pte_swp_mksoft_dirty(entry);
2251 } else {
2252 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2253 entry = maybe_mkwrite(entry, vma);
2254 if (!write)
2255 entry = pte_wrprotect(entry);
2256 if (!young)
2257 entry = pte_mkold(entry);
2258 if (soft_dirty)
2259 entry = pte_mksoft_dirty(entry);
2261 pte = pte_offset_map(&_pmd, addr);
2262 BUG_ON(!pte_none(*pte));
2263 set_pte_at(mm, addr, pte, entry);
2264 atomic_inc(&page[i]._mapcount);
2265 pte_unmap(pte);
2269 * Set PG_double_map before dropping compound_mapcount to avoid
2270 * false-negative page_mapped().
2272 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2273 for (i = 0; i < HPAGE_PMD_NR; i++)
2274 atomic_inc(&page[i]._mapcount);
2277 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2278 /* Last compound_mapcount is gone. */
2279 __dec_node_page_state(page, NR_ANON_THPS);
2280 if (TestClearPageDoubleMap(page)) {
2281 /* No need in mapcount reference anymore */
2282 for (i = 0; i < HPAGE_PMD_NR; i++)
2283 atomic_dec(&page[i]._mapcount);
2287 smp_wmb(); /* make pte visible before pmd */
2288 pmd_populate(mm, pmd, pgtable);
2290 if (freeze) {
2291 for (i = 0; i < HPAGE_PMD_NR; i++) {
2292 page_remove_rmap(page + i, false);
2293 put_page(page + i);
2298 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2299 unsigned long address, bool freeze, struct page *page)
2301 spinlock_t *ptl;
2302 struct mmu_notifier_range range;
2304 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2305 address & HPAGE_PMD_MASK,
2306 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2307 mmu_notifier_invalidate_range_start(&range);
2308 ptl = pmd_lock(vma->vm_mm, pmd);
2311 * If caller asks to setup a migration entries, we need a page to check
2312 * pmd against. Otherwise we can end up replacing wrong page.
2314 VM_BUG_ON(freeze && !page);
2315 if (page && page != pmd_page(*pmd))
2316 goto out;
2318 if (pmd_trans_huge(*pmd)) {
2319 page = pmd_page(*pmd);
2320 if (PageMlocked(page))
2321 clear_page_mlock(page);
2322 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2323 goto out;
2324 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2325 out:
2326 spin_unlock(ptl);
2328 * No need to double call mmu_notifier->invalidate_range() callback.
2329 * They are 3 cases to consider inside __split_huge_pmd_locked():
2330 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2331 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2332 * fault will trigger a flush_notify before pointing to a new page
2333 * (it is fine if the secondary mmu keeps pointing to the old zero
2334 * page in the meantime)
2335 * 3) Split a huge pmd into pte pointing to the same page. No need
2336 * to invalidate secondary tlb entry they are all still valid.
2337 * any further changes to individual pte will notify. So no need
2338 * to call mmu_notifier->invalidate_range()
2340 mmu_notifier_invalidate_range_only_end(&range);
2343 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2344 bool freeze, struct page *page)
2346 pgd_t *pgd;
2347 p4d_t *p4d;
2348 pud_t *pud;
2349 pmd_t *pmd;
2351 pgd = pgd_offset(vma->vm_mm, address);
2352 if (!pgd_present(*pgd))
2353 return;
2355 p4d = p4d_offset(pgd, address);
2356 if (!p4d_present(*p4d))
2357 return;
2359 pud = pud_offset(p4d, address);
2360 if (!pud_present(*pud))
2361 return;
2363 pmd = pmd_offset(pud, address);
2365 __split_huge_pmd(vma, pmd, address, freeze, page);
2368 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2369 unsigned long start,
2370 unsigned long end,
2371 long adjust_next)
2374 * If the new start address isn't hpage aligned and it could
2375 * previously contain an hugepage: check if we need to split
2376 * an huge pmd.
2378 if (start & ~HPAGE_PMD_MASK &&
2379 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2380 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2381 split_huge_pmd_address(vma, start, false, NULL);
2384 * If the new end address isn't hpage aligned and it could
2385 * previously contain an hugepage: check if we need to split
2386 * an huge pmd.
2388 if (end & ~HPAGE_PMD_MASK &&
2389 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2390 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2391 split_huge_pmd_address(vma, end, false, NULL);
2394 * If we're also updating the vma->vm_next->vm_start, if the new
2395 * vm_next->vm_start isn't page aligned and it could previously
2396 * contain an hugepage: check if we need to split an huge pmd.
2398 if (adjust_next > 0) {
2399 struct vm_area_struct *next = vma->vm_next;
2400 unsigned long nstart = next->vm_start;
2401 nstart += adjust_next << PAGE_SHIFT;
2402 if (nstart & ~HPAGE_PMD_MASK &&
2403 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2404 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2405 split_huge_pmd_address(next, nstart, false, NULL);
2409 static void unmap_page(struct page *page)
2411 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2412 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2413 bool unmap_success;
2415 VM_BUG_ON_PAGE(!PageHead(page), page);
2417 if (PageAnon(page))
2418 ttu_flags |= TTU_SPLIT_FREEZE;
2420 unmap_success = try_to_unmap(page, ttu_flags);
2421 VM_BUG_ON_PAGE(!unmap_success, page);
2424 static void remap_page(struct page *page)
2426 int i;
2427 if (PageTransHuge(page)) {
2428 remove_migration_ptes(page, page, true);
2429 } else {
2430 for (i = 0; i < HPAGE_PMD_NR; i++)
2431 remove_migration_ptes(page + i, page + i, true);
2435 static void __split_huge_page_tail(struct page *head, int tail,
2436 struct lruvec *lruvec, struct list_head *list)
2438 struct page *page_tail = head + tail;
2440 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2443 * Clone page flags before unfreezing refcount.
2445 * After successful get_page_unless_zero() might follow flags change,
2446 * for exmaple lock_page() which set PG_waiters.
2448 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2449 page_tail->flags |= (head->flags &
2450 ((1L << PG_referenced) |
2451 (1L << PG_swapbacked) |
2452 (1L << PG_swapcache) |
2453 (1L << PG_mlocked) |
2454 (1L << PG_uptodate) |
2455 (1L << PG_active) |
2456 (1L << PG_workingset) |
2457 (1L << PG_locked) |
2458 (1L << PG_unevictable) |
2459 (1L << PG_dirty)));
2461 /* ->mapping in first tail page is compound_mapcount */
2462 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2463 page_tail);
2464 page_tail->mapping = head->mapping;
2465 page_tail->index = head->index + tail;
2467 /* Page flags must be visible before we make the page non-compound. */
2468 smp_wmb();
2471 * Clear PageTail before unfreezing page refcount.
2473 * After successful get_page_unless_zero() might follow put_page()
2474 * which needs correct compound_head().
2476 clear_compound_head(page_tail);
2478 /* Finally unfreeze refcount. Additional reference from page cache. */
2479 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2480 PageSwapCache(head)));
2482 if (page_is_young(head))
2483 set_page_young(page_tail);
2484 if (page_is_idle(head))
2485 set_page_idle(page_tail);
2487 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2490 * always add to the tail because some iterators expect new
2491 * pages to show after the currently processed elements - e.g.
2492 * migrate_pages
2494 lru_add_page_tail(head, page_tail, lruvec, list);
2497 static void __split_huge_page(struct page *page, struct list_head *list,
2498 pgoff_t end, unsigned long flags)
2500 struct page *head = compound_head(page);
2501 pg_data_t *pgdat = page_pgdat(head);
2502 struct lruvec *lruvec;
2503 struct address_space *swap_cache = NULL;
2504 unsigned long offset = 0;
2505 int i;
2507 lruvec = mem_cgroup_page_lruvec(head, pgdat);
2509 /* complete memcg works before add pages to LRU */
2510 mem_cgroup_split_huge_fixup(head);
2512 if (PageAnon(head) && PageSwapCache(head)) {
2513 swp_entry_t entry = { .val = page_private(head) };
2515 offset = swp_offset(entry);
2516 swap_cache = swap_address_space(entry);
2517 xa_lock(&swap_cache->i_pages);
2520 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2521 __split_huge_page_tail(head, i, lruvec, list);
2522 /* Some pages can be beyond i_size: drop them from page cache */
2523 if (head[i].index >= end) {
2524 ClearPageDirty(head + i);
2525 __delete_from_page_cache(head + i, NULL);
2526 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2527 shmem_uncharge(head->mapping->host, 1);
2528 put_page(head + i);
2529 } else if (!PageAnon(page)) {
2530 __xa_store(&head->mapping->i_pages, head[i].index,
2531 head + i, 0);
2532 } else if (swap_cache) {
2533 __xa_store(&swap_cache->i_pages, offset + i,
2534 head + i, 0);
2538 ClearPageCompound(head);
2540 split_page_owner(head, HPAGE_PMD_ORDER);
2542 /* See comment in __split_huge_page_tail() */
2543 if (PageAnon(head)) {
2544 /* Additional pin to swap cache */
2545 if (PageSwapCache(head)) {
2546 page_ref_add(head, 2);
2547 xa_unlock(&swap_cache->i_pages);
2548 } else {
2549 page_ref_inc(head);
2551 } else {
2552 /* Additional pin to page cache */
2553 page_ref_add(head, 2);
2554 xa_unlock(&head->mapping->i_pages);
2557 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
2559 remap_page(head);
2561 for (i = 0; i < HPAGE_PMD_NR; i++) {
2562 struct page *subpage = head + i;
2563 if (subpage == page)
2564 continue;
2565 unlock_page(subpage);
2568 * Subpages may be freed if there wasn't any mapping
2569 * like if add_to_swap() is running on a lru page that
2570 * had its mapping zapped. And freeing these pages
2571 * requires taking the lru_lock so we do the put_page
2572 * of the tail pages after the split is complete.
2574 put_page(subpage);
2578 int total_mapcount(struct page *page)
2580 int i, compound, ret;
2582 VM_BUG_ON_PAGE(PageTail(page), page);
2584 if (likely(!PageCompound(page)))
2585 return atomic_read(&page->_mapcount) + 1;
2587 compound = compound_mapcount(page);
2588 if (PageHuge(page))
2589 return compound;
2590 ret = compound;
2591 for (i = 0; i < HPAGE_PMD_NR; i++)
2592 ret += atomic_read(&page[i]._mapcount) + 1;
2593 /* File pages has compound_mapcount included in _mapcount */
2594 if (!PageAnon(page))
2595 return ret - compound * HPAGE_PMD_NR;
2596 if (PageDoubleMap(page))
2597 ret -= HPAGE_PMD_NR;
2598 return ret;
2602 * This calculates accurately how many mappings a transparent hugepage
2603 * has (unlike page_mapcount() which isn't fully accurate). This full
2604 * accuracy is primarily needed to know if copy-on-write faults can
2605 * reuse the page and change the mapping to read-write instead of
2606 * copying them. At the same time this returns the total_mapcount too.
2608 * The function returns the highest mapcount any one of the subpages
2609 * has. If the return value is one, even if different processes are
2610 * mapping different subpages of the transparent hugepage, they can
2611 * all reuse it, because each process is reusing a different subpage.
2613 * The total_mapcount is instead counting all virtual mappings of the
2614 * subpages. If the total_mapcount is equal to "one", it tells the
2615 * caller all mappings belong to the same "mm" and in turn the
2616 * anon_vma of the transparent hugepage can become the vma->anon_vma
2617 * local one as no other process may be mapping any of the subpages.
2619 * It would be more accurate to replace page_mapcount() with
2620 * page_trans_huge_mapcount(), however we only use
2621 * page_trans_huge_mapcount() in the copy-on-write faults where we
2622 * need full accuracy to avoid breaking page pinning, because
2623 * page_trans_huge_mapcount() is slower than page_mapcount().
2625 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2627 int i, ret, _total_mapcount, mapcount;
2629 /* hugetlbfs shouldn't call it */
2630 VM_BUG_ON_PAGE(PageHuge(page), page);
2632 if (likely(!PageTransCompound(page))) {
2633 mapcount = atomic_read(&page->_mapcount) + 1;
2634 if (total_mapcount)
2635 *total_mapcount = mapcount;
2636 return mapcount;
2639 page = compound_head(page);
2641 _total_mapcount = ret = 0;
2642 for (i = 0; i < HPAGE_PMD_NR; i++) {
2643 mapcount = atomic_read(&page[i]._mapcount) + 1;
2644 ret = max(ret, mapcount);
2645 _total_mapcount += mapcount;
2647 if (PageDoubleMap(page)) {
2648 ret -= 1;
2649 _total_mapcount -= HPAGE_PMD_NR;
2651 mapcount = compound_mapcount(page);
2652 ret += mapcount;
2653 _total_mapcount += mapcount;
2654 if (total_mapcount)
2655 *total_mapcount = _total_mapcount;
2656 return ret;
2659 /* Racy check whether the huge page can be split */
2660 bool can_split_huge_page(struct page *page, int *pextra_pins)
2662 int extra_pins;
2664 /* Additional pins from page cache */
2665 if (PageAnon(page))
2666 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2667 else
2668 extra_pins = HPAGE_PMD_NR;
2669 if (pextra_pins)
2670 *pextra_pins = extra_pins;
2671 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2675 * This function splits huge page into normal pages. @page can point to any
2676 * subpage of huge page to split. Split doesn't change the position of @page.
2678 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2679 * The huge page must be locked.
2681 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2683 * Both head page and tail pages will inherit mapping, flags, and so on from
2684 * the hugepage.
2686 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2687 * they are not mapped.
2689 * Returns 0 if the hugepage is split successfully.
2690 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2691 * us.
2693 int split_huge_page_to_list(struct page *page, struct list_head *list)
2695 struct page *head = compound_head(page);
2696 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2697 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2698 struct anon_vma *anon_vma = NULL;
2699 struct address_space *mapping = NULL;
2700 int count, mapcount, extra_pins, ret;
2701 bool mlocked;
2702 unsigned long flags;
2703 pgoff_t end;
2705 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2706 VM_BUG_ON_PAGE(!PageLocked(page), page);
2707 VM_BUG_ON_PAGE(!PageCompound(page), page);
2709 if (PageWriteback(page))
2710 return -EBUSY;
2712 if (PageAnon(head)) {
2714 * The caller does not necessarily hold an mmap_sem that would
2715 * prevent the anon_vma disappearing so we first we take a
2716 * reference to it and then lock the anon_vma for write. This
2717 * is similar to page_lock_anon_vma_read except the write lock
2718 * is taken to serialise against parallel split or collapse
2719 * operations.
2721 anon_vma = page_get_anon_vma(head);
2722 if (!anon_vma) {
2723 ret = -EBUSY;
2724 goto out;
2726 end = -1;
2727 mapping = NULL;
2728 anon_vma_lock_write(anon_vma);
2729 } else {
2730 mapping = head->mapping;
2732 /* Truncated ? */
2733 if (!mapping) {
2734 ret = -EBUSY;
2735 goto out;
2738 anon_vma = NULL;
2739 i_mmap_lock_read(mapping);
2742 *__split_huge_page() may need to trim off pages beyond EOF:
2743 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2744 * which cannot be nested inside the page tree lock. So note
2745 * end now: i_size itself may be changed at any moment, but
2746 * head page lock is good enough to serialize the trimming.
2748 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2752 * Racy check if we can split the page, before unmap_page() will
2753 * split PMDs
2755 if (!can_split_huge_page(head, &extra_pins)) {
2756 ret = -EBUSY;
2757 goto out_unlock;
2760 mlocked = PageMlocked(page);
2761 unmap_page(head);
2762 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2764 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2765 if (mlocked)
2766 lru_add_drain();
2768 /* prevent PageLRU to go away from under us, and freeze lru stats */
2769 spin_lock_irqsave(&pgdata->lru_lock, flags);
2771 if (mapping) {
2772 XA_STATE(xas, &mapping->i_pages, page_index(head));
2775 * Check if the head page is present in page cache.
2776 * We assume all tail are present too, if head is there.
2778 xa_lock(&mapping->i_pages);
2779 if (xas_load(&xas) != head)
2780 goto fail;
2783 /* Prevent deferred_split_scan() touching ->_refcount */
2784 spin_lock(&ds_queue->split_queue_lock);
2785 count = page_count(head);
2786 mapcount = total_mapcount(head);
2787 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2788 if (!list_empty(page_deferred_list(head))) {
2789 ds_queue->split_queue_len--;
2790 list_del(page_deferred_list(head));
2792 if (mapping) {
2793 if (PageSwapBacked(page))
2794 __dec_node_page_state(page, NR_SHMEM_THPS);
2795 else
2796 __dec_node_page_state(page, NR_FILE_THPS);
2799 spin_unlock(&ds_queue->split_queue_lock);
2800 __split_huge_page(page, list, end, flags);
2801 if (PageSwapCache(head)) {
2802 swp_entry_t entry = { .val = page_private(head) };
2804 ret = split_swap_cluster(entry);
2805 } else
2806 ret = 0;
2807 } else {
2808 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2809 pr_alert("total_mapcount: %u, page_count(): %u\n",
2810 mapcount, count);
2811 if (PageTail(page))
2812 dump_page(head, NULL);
2813 dump_page(page, "total_mapcount(head) > 0");
2814 BUG();
2816 spin_unlock(&ds_queue->split_queue_lock);
2817 fail: if (mapping)
2818 xa_unlock(&mapping->i_pages);
2819 spin_unlock_irqrestore(&pgdata->lru_lock, flags);
2820 remap_page(head);
2821 ret = -EBUSY;
2824 out_unlock:
2825 if (anon_vma) {
2826 anon_vma_unlock_write(anon_vma);
2827 put_anon_vma(anon_vma);
2829 if (mapping)
2830 i_mmap_unlock_read(mapping);
2831 out:
2832 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2833 return ret;
2836 void free_transhuge_page(struct page *page)
2838 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2839 unsigned long flags;
2841 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2842 if (!list_empty(page_deferred_list(page))) {
2843 ds_queue->split_queue_len--;
2844 list_del(page_deferred_list(page));
2846 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2847 free_compound_page(page);
2850 void deferred_split_huge_page(struct page *page)
2852 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2853 #ifdef CONFIG_MEMCG
2854 struct mem_cgroup *memcg = compound_head(page)->mem_cgroup;
2855 #endif
2856 unsigned long flags;
2858 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2861 * The try_to_unmap() in page reclaim path might reach here too,
2862 * this may cause a race condition to corrupt deferred split queue.
2863 * And, if page reclaim is already handling the same page, it is
2864 * unnecessary to handle it again in shrinker.
2866 * Check PageSwapCache to determine if the page is being
2867 * handled by page reclaim since THP swap would add the page into
2868 * swap cache before calling try_to_unmap().
2870 if (PageSwapCache(page))
2871 return;
2873 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2874 if (list_empty(page_deferred_list(page))) {
2875 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2876 list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
2877 ds_queue->split_queue_len++;
2878 #ifdef CONFIG_MEMCG
2879 if (memcg)
2880 memcg_set_shrinker_bit(memcg, page_to_nid(page),
2881 deferred_split_shrinker.id);
2882 #endif
2884 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2887 static unsigned long deferred_split_count(struct shrinker *shrink,
2888 struct shrink_control *sc)
2890 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2891 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2893 #ifdef CONFIG_MEMCG
2894 if (sc->memcg)
2895 ds_queue = &sc->memcg->deferred_split_queue;
2896 #endif
2897 return READ_ONCE(ds_queue->split_queue_len);
2900 static unsigned long deferred_split_scan(struct shrinker *shrink,
2901 struct shrink_control *sc)
2903 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2904 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2905 unsigned long flags;
2906 LIST_HEAD(list), *pos, *next;
2907 struct page *page;
2908 int split = 0;
2910 #ifdef CONFIG_MEMCG
2911 if (sc->memcg)
2912 ds_queue = &sc->memcg->deferred_split_queue;
2913 #endif
2915 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2916 /* Take pin on all head pages to avoid freeing them under us */
2917 list_for_each_safe(pos, next, &ds_queue->split_queue) {
2918 page = list_entry((void *)pos, struct page, mapping);
2919 page = compound_head(page);
2920 if (get_page_unless_zero(page)) {
2921 list_move(page_deferred_list(page), &list);
2922 } else {
2923 /* We lost race with put_compound_page() */
2924 list_del_init(page_deferred_list(page));
2925 ds_queue->split_queue_len--;
2927 if (!--sc->nr_to_scan)
2928 break;
2930 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2932 list_for_each_safe(pos, next, &list) {
2933 page = list_entry((void *)pos, struct page, mapping);
2934 if (!trylock_page(page))
2935 goto next;
2936 /* split_huge_page() removes page from list on success */
2937 if (!split_huge_page(page))
2938 split++;
2939 unlock_page(page);
2940 next:
2941 put_page(page);
2944 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2945 list_splice_tail(&list, &ds_queue->split_queue);
2946 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2949 * Stop shrinker if we didn't split any page, but the queue is empty.
2950 * This can happen if pages were freed under us.
2952 if (!split && list_empty(&ds_queue->split_queue))
2953 return SHRINK_STOP;
2954 return split;
2957 static struct shrinker deferred_split_shrinker = {
2958 .count_objects = deferred_split_count,
2959 .scan_objects = deferred_split_scan,
2960 .seeks = DEFAULT_SEEKS,
2961 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
2962 SHRINKER_NONSLAB,
2965 #ifdef CONFIG_DEBUG_FS
2966 static int split_huge_pages_set(void *data, u64 val)
2968 struct zone *zone;
2969 struct page *page;
2970 unsigned long pfn, max_zone_pfn;
2971 unsigned long total = 0, split = 0;
2973 if (val != 1)
2974 return -EINVAL;
2976 for_each_populated_zone(zone) {
2977 max_zone_pfn = zone_end_pfn(zone);
2978 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2979 if (!pfn_valid(pfn))
2980 continue;
2982 page = pfn_to_page(pfn);
2983 if (!get_page_unless_zero(page))
2984 continue;
2986 if (zone != page_zone(page))
2987 goto next;
2989 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2990 goto next;
2992 total++;
2993 lock_page(page);
2994 if (!split_huge_page(page))
2995 split++;
2996 unlock_page(page);
2997 next:
2998 put_page(page);
3002 pr_info("%lu of %lu THP split\n", split, total);
3004 return 0;
3006 DEFINE_DEBUGFS_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
3007 "%llu\n");
3009 static int __init split_huge_pages_debugfs(void)
3011 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
3012 &split_huge_pages_fops);
3013 return 0;
3015 late_initcall(split_huge_pages_debugfs);
3016 #endif
3018 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
3019 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
3020 struct page *page)
3022 struct vm_area_struct *vma = pvmw->vma;
3023 struct mm_struct *mm = vma->vm_mm;
3024 unsigned long address = pvmw->address;
3025 pmd_t pmdval;
3026 swp_entry_t entry;
3027 pmd_t pmdswp;
3029 if (!(pvmw->pmd && !pvmw->pte))
3030 return;
3032 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
3033 pmdval = *pvmw->pmd;
3034 pmdp_invalidate(vma, address, pvmw->pmd);
3035 if (pmd_dirty(pmdval))
3036 set_page_dirty(page);
3037 entry = make_migration_entry(page, pmd_write(pmdval));
3038 pmdswp = swp_entry_to_pmd(entry);
3039 if (pmd_soft_dirty(pmdval))
3040 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
3041 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
3042 page_remove_rmap(page, true);
3043 put_page(page);
3046 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
3048 struct vm_area_struct *vma = pvmw->vma;
3049 struct mm_struct *mm = vma->vm_mm;
3050 unsigned long address = pvmw->address;
3051 unsigned long mmun_start = address & HPAGE_PMD_MASK;
3052 pmd_t pmde;
3053 swp_entry_t entry;
3055 if (!(pvmw->pmd && !pvmw->pte))
3056 return;
3058 entry = pmd_to_swp_entry(*pvmw->pmd);
3059 get_page(new);
3060 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
3061 if (pmd_swp_soft_dirty(*pvmw->pmd))
3062 pmde = pmd_mksoft_dirty(pmde);
3063 if (is_write_migration_entry(entry))
3064 pmde = maybe_pmd_mkwrite(pmde, vma);
3066 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
3067 if (PageAnon(new))
3068 page_add_anon_rmap(new, vma, mmun_start, true);
3069 else
3070 page_add_file_rmap(new, true);
3071 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
3072 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
3073 mlock_vma_page(new);
3074 update_mmu_cache_pmd(vma, address, pvmw->pmd);
3076 #endif