1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2009 Red Hat, Inc.
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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/dax.h>
22 #include <linux/khugepaged.h>
23 #include <linux/freezer.h>
24 #include <linux/pfn_t.h>
25 #include <linux/mman.h>
26 #include <linux/memremap.h>
27 #include <linux/pagemap.h>
28 #include <linux/debugfs.h>
29 #include <linux/migrate.h>
30 #include <linux/hashtable.h>
31 #include <linux/userfaultfd_k.h>
32 #include <linux/page_idle.h>
33 #include <linux/shmem_fs.h>
34 #include <linux/oom.h>
35 #include <linux/numa.h>
36 #include <linux/page_owner.h>
39 #include <asm/pgalloc.h>
43 * By default, transparent hugepage support is disabled in order to avoid
44 * risking an increased memory footprint for applications that are not
45 * guaranteed to benefit from it. When transparent hugepage support is
46 * enabled, it is for all mappings, and khugepaged scans all mappings.
47 * Defrag is invoked by khugepaged hugepage allocations and by page faults
48 * for all hugepage allocations.
50 unsigned long transparent_hugepage_flags __read_mostly =
51 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
52 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
54 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
55 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
58 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
59 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
61 static struct shrinker deferred_split_shrinker;
63 static atomic_t huge_zero_refcount;
64 struct page *huge_zero_page __read_mostly;
65 unsigned long huge_zero_pfn __read_mostly = ~0UL;
67 static inline bool file_thp_enabled(struct vm_area_struct *vma)
69 return transhuge_vma_enabled(vma, vma->vm_flags) && vma->vm_file &&
70 !inode_is_open_for_write(vma->vm_file->f_inode) &&
71 (vma->vm_flags & VM_EXEC);
74 bool transparent_hugepage_active(struct vm_area_struct *vma)
76 /* The addr is used to check if the vma size fits */
77 unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE;
79 if (!transhuge_vma_suitable(vma, addr))
81 if (vma_is_anonymous(vma))
82 return __transparent_hugepage_enabled(vma);
83 if (vma_is_shmem(vma))
84 return shmem_huge_enabled(vma);
85 if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS))
86 return file_thp_enabled(vma);
91 static bool get_huge_zero_page(void)
93 struct page *zero_page;
95 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
98 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
101 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
104 count_vm_event(THP_ZERO_PAGE_ALLOC);
106 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
108 __free_pages(zero_page, compound_order(zero_page));
111 WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page));
113 /* We take additional reference here. It will be put back by shrinker */
114 atomic_set(&huge_zero_refcount, 2);
119 static void put_huge_zero_page(void)
122 * Counter should never go to zero here. Only shrinker can put
125 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
128 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
130 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
131 return READ_ONCE(huge_zero_page);
133 if (!get_huge_zero_page())
136 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
137 put_huge_zero_page();
139 return READ_ONCE(huge_zero_page);
142 void mm_put_huge_zero_page(struct mm_struct *mm)
144 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
145 put_huge_zero_page();
148 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
149 struct shrink_control *sc)
151 /* we can free zero page only if last reference remains */
152 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
155 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
156 struct shrink_control *sc)
158 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
159 struct page *zero_page = xchg(&huge_zero_page, NULL);
160 BUG_ON(zero_page == NULL);
161 WRITE_ONCE(huge_zero_pfn, ~0UL);
162 __free_pages(zero_page, compound_order(zero_page));
169 static struct shrinker huge_zero_page_shrinker = {
170 .count_objects = shrink_huge_zero_page_count,
171 .scan_objects = shrink_huge_zero_page_scan,
172 .seeks = DEFAULT_SEEKS,
176 static ssize_t enabled_show(struct kobject *kobj,
177 struct kobj_attribute *attr, char *buf)
181 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
182 output = "[always] madvise never";
183 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
184 &transparent_hugepage_flags))
185 output = "always [madvise] never";
187 output = "always madvise [never]";
189 return sysfs_emit(buf, "%s\n", output);
192 static ssize_t enabled_store(struct kobject *kobj,
193 struct kobj_attribute *attr,
194 const char *buf, size_t count)
198 if (sysfs_streq(buf, "always")) {
199 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
200 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
201 } else if (sysfs_streq(buf, "madvise")) {
202 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
203 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
204 } else if (sysfs_streq(buf, "never")) {
205 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
206 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
211 int err = start_stop_khugepaged();
217 static struct kobj_attribute enabled_attr =
218 __ATTR(enabled, 0644, enabled_show, enabled_store);
220 ssize_t single_hugepage_flag_show(struct kobject *kobj,
221 struct kobj_attribute *attr, char *buf,
222 enum transparent_hugepage_flag flag)
224 return sysfs_emit(buf, "%d\n",
225 !!test_bit(flag, &transparent_hugepage_flags));
228 ssize_t single_hugepage_flag_store(struct kobject *kobj,
229 struct kobj_attribute *attr,
230 const char *buf, size_t count,
231 enum transparent_hugepage_flag flag)
236 ret = kstrtoul(buf, 10, &value);
243 set_bit(flag, &transparent_hugepage_flags);
245 clear_bit(flag, &transparent_hugepage_flags);
250 static ssize_t defrag_show(struct kobject *kobj,
251 struct kobj_attribute *attr, char *buf)
255 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
256 &transparent_hugepage_flags))
257 output = "[always] defer defer+madvise madvise never";
258 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
259 &transparent_hugepage_flags))
260 output = "always [defer] defer+madvise madvise never";
261 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
262 &transparent_hugepage_flags))
263 output = "always defer [defer+madvise] madvise never";
264 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
265 &transparent_hugepage_flags))
266 output = "always defer defer+madvise [madvise] never";
268 output = "always defer defer+madvise madvise [never]";
270 return sysfs_emit(buf, "%s\n", output);
273 static ssize_t defrag_store(struct kobject *kobj,
274 struct kobj_attribute *attr,
275 const char *buf, size_t count)
277 if (sysfs_streq(buf, "always")) {
278 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
279 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
280 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
281 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
282 } else if (sysfs_streq(buf, "defer+madvise")) {
283 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
284 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
285 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
286 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
287 } else if (sysfs_streq(buf, "defer")) {
288 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
289 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
290 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
291 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
292 } else if (sysfs_streq(buf, "madvise")) {
293 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
294 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
295 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
296 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
297 } else if (sysfs_streq(buf, "never")) {
298 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
299 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
300 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
301 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
307 static struct kobj_attribute defrag_attr =
308 __ATTR(defrag, 0644, defrag_show, defrag_store);
310 static ssize_t use_zero_page_show(struct kobject *kobj,
311 struct kobj_attribute *attr, char *buf)
313 return single_hugepage_flag_show(kobj, attr, buf,
314 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
316 static ssize_t use_zero_page_store(struct kobject *kobj,
317 struct kobj_attribute *attr, const char *buf, size_t count)
319 return single_hugepage_flag_store(kobj, attr, buf, count,
320 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
322 static struct kobj_attribute use_zero_page_attr =
323 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
325 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
326 struct kobj_attribute *attr, char *buf)
328 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE);
330 static struct kobj_attribute hpage_pmd_size_attr =
331 __ATTR_RO(hpage_pmd_size);
333 static struct attribute *hugepage_attr[] = {
336 &use_zero_page_attr.attr,
337 &hpage_pmd_size_attr.attr,
339 &shmem_enabled_attr.attr,
344 static const struct attribute_group hugepage_attr_group = {
345 .attrs = hugepage_attr,
348 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
352 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
353 if (unlikely(!*hugepage_kobj)) {
354 pr_err("failed to create transparent hugepage kobject\n");
358 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
360 pr_err("failed to register transparent hugepage group\n");
364 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
366 pr_err("failed to register transparent hugepage group\n");
367 goto remove_hp_group;
373 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
375 kobject_put(*hugepage_kobj);
379 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
381 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
382 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
383 kobject_put(hugepage_kobj);
386 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
391 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
394 #endif /* CONFIG_SYSFS */
396 static int __init hugepage_init(void)
399 struct kobject *hugepage_kobj;
401 if (!has_transparent_hugepage()) {
403 * Hardware doesn't support hugepages, hence disable
406 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX;
411 * hugepages can't be allocated by the buddy allocator
413 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
415 * we use page->mapping and page->index in second tail page
416 * as list_head: assuming THP order >= 2
418 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
420 err = hugepage_init_sysfs(&hugepage_kobj);
424 err = khugepaged_init();
428 err = register_shrinker(&huge_zero_page_shrinker);
430 goto err_hzp_shrinker;
431 err = register_shrinker(&deferred_split_shrinker);
433 goto err_split_shrinker;
436 * By default disable transparent hugepages on smaller systems,
437 * where the extra memory used could hurt more than TLB overhead
438 * is likely to save. The admin can still enable it through /sys.
440 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
441 transparent_hugepage_flags = 0;
445 err = start_stop_khugepaged();
451 unregister_shrinker(&deferred_split_shrinker);
453 unregister_shrinker(&huge_zero_page_shrinker);
455 khugepaged_destroy();
457 hugepage_exit_sysfs(hugepage_kobj);
461 subsys_initcall(hugepage_init);
463 static int __init setup_transparent_hugepage(char *str)
468 if (!strcmp(str, "always")) {
469 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
470 &transparent_hugepage_flags);
471 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
472 &transparent_hugepage_flags);
474 } else if (!strcmp(str, "madvise")) {
475 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
476 &transparent_hugepage_flags);
477 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
478 &transparent_hugepage_flags);
480 } else if (!strcmp(str, "never")) {
481 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
482 &transparent_hugepage_flags);
483 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
484 &transparent_hugepage_flags);
489 pr_warn("transparent_hugepage= cannot parse, ignored\n");
492 __setup("transparent_hugepage=", setup_transparent_hugepage);
494 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
496 if (likely(vma->vm_flags & VM_WRITE))
497 pmd = pmd_mkwrite(pmd);
502 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
504 struct mem_cgroup *memcg = page_memcg(compound_head(page));
505 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
508 return &memcg->deferred_split_queue;
510 return &pgdat->deferred_split_queue;
513 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
515 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
517 return &pgdat->deferred_split_queue;
521 void prep_transhuge_page(struct page *page)
524 * we use page->mapping and page->indexlru in second tail page
525 * as list_head: assuming THP order >= 2
528 INIT_LIST_HEAD(page_deferred_list(page));
529 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
532 bool is_transparent_hugepage(struct page *page)
534 if (!PageCompound(page))
537 page = compound_head(page);
538 return is_huge_zero_page(page) ||
539 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR;
541 EXPORT_SYMBOL_GPL(is_transparent_hugepage);
543 static unsigned long __thp_get_unmapped_area(struct file *filp,
544 unsigned long addr, unsigned long len,
545 loff_t off, unsigned long flags, unsigned long size)
547 loff_t off_end = off + len;
548 loff_t off_align = round_up(off, size);
549 unsigned long len_pad, ret;
551 if (off_end <= off_align || (off_end - off_align) < size)
554 len_pad = len + size;
555 if (len_pad < len || (off + len_pad) < off)
558 ret = current->mm->get_unmapped_area(filp, addr, len_pad,
559 off >> PAGE_SHIFT, flags);
562 * The failure might be due to length padding. The caller will retry
563 * without the padding.
565 if (IS_ERR_VALUE(ret))
569 * Do not try to align to THP boundary if allocation at the address
575 ret += (off - ret) & (size - 1);
579 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
580 unsigned long len, unsigned long pgoff, unsigned long flags)
583 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
585 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
588 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
592 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
594 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
596 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
597 struct page *page, gfp_t gfp)
599 struct vm_area_struct *vma = vmf->vma;
601 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
604 VM_BUG_ON_PAGE(!PageCompound(page), page);
606 if (mem_cgroup_charge(page_folio(page), vma->vm_mm, gfp)) {
608 count_vm_event(THP_FAULT_FALLBACK);
609 count_vm_event(THP_FAULT_FALLBACK_CHARGE);
610 return VM_FAULT_FALLBACK;
612 cgroup_throttle_swaprate(page, gfp);
614 pgtable = pte_alloc_one(vma->vm_mm);
615 if (unlikely(!pgtable)) {
620 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
622 * The memory barrier inside __SetPageUptodate makes sure that
623 * clear_huge_page writes become visible before the set_pmd_at()
626 __SetPageUptodate(page);
628 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
629 if (unlikely(!pmd_none(*vmf->pmd))) {
634 ret = check_stable_address_space(vma->vm_mm);
638 /* Deliver the page fault to userland */
639 if (userfaultfd_missing(vma)) {
640 spin_unlock(vmf->ptl);
642 pte_free(vma->vm_mm, pgtable);
643 ret = handle_userfault(vmf, VM_UFFD_MISSING);
644 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
648 entry = mk_huge_pmd(page, vma->vm_page_prot);
649 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
650 page_add_new_anon_rmap(page, vma, haddr, true);
651 lru_cache_add_inactive_or_unevictable(page, vma);
652 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
653 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
654 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
655 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
656 mm_inc_nr_ptes(vma->vm_mm);
657 spin_unlock(vmf->ptl);
658 count_vm_event(THP_FAULT_ALLOC);
659 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
664 spin_unlock(vmf->ptl);
667 pte_free(vma->vm_mm, pgtable);
674 * always: directly stall for all thp allocations
675 * defer: wake kswapd and fail if not immediately available
676 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
677 * fail if not immediately available
678 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
680 * never: never stall for any thp allocation
682 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma)
684 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE);
686 /* Always do synchronous compaction */
687 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
688 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
690 /* Kick kcompactd and fail quickly */
691 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
692 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
694 /* Synchronous compaction if madvised, otherwise kick kcompactd */
695 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
696 return GFP_TRANSHUGE_LIGHT |
697 (vma_madvised ? __GFP_DIRECT_RECLAIM :
698 __GFP_KSWAPD_RECLAIM);
700 /* Only do synchronous compaction if madvised */
701 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
702 return GFP_TRANSHUGE_LIGHT |
703 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
705 return GFP_TRANSHUGE_LIGHT;
708 /* Caller must hold page table lock. */
709 static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
710 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
711 struct page *zero_page)
716 entry = mk_pmd(zero_page, vma->vm_page_prot);
717 entry = pmd_mkhuge(entry);
719 pgtable_trans_huge_deposit(mm, pmd, pgtable);
720 set_pmd_at(mm, haddr, pmd, entry);
724 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
726 struct vm_area_struct *vma = vmf->vma;
729 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
731 if (!transhuge_vma_suitable(vma, haddr))
732 return VM_FAULT_FALLBACK;
733 if (unlikely(anon_vma_prepare(vma)))
735 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
737 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
738 !mm_forbids_zeropage(vma->vm_mm) &&
739 transparent_hugepage_use_zero_page()) {
741 struct page *zero_page;
743 pgtable = pte_alloc_one(vma->vm_mm);
744 if (unlikely(!pgtable))
746 zero_page = mm_get_huge_zero_page(vma->vm_mm);
747 if (unlikely(!zero_page)) {
748 pte_free(vma->vm_mm, pgtable);
749 count_vm_event(THP_FAULT_FALLBACK);
750 return VM_FAULT_FALLBACK;
752 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
754 if (pmd_none(*vmf->pmd)) {
755 ret = check_stable_address_space(vma->vm_mm);
757 spin_unlock(vmf->ptl);
758 pte_free(vma->vm_mm, pgtable);
759 } else if (userfaultfd_missing(vma)) {
760 spin_unlock(vmf->ptl);
761 pte_free(vma->vm_mm, pgtable);
762 ret = handle_userfault(vmf, VM_UFFD_MISSING);
763 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
765 set_huge_zero_page(pgtable, vma->vm_mm, vma,
766 haddr, vmf->pmd, zero_page);
767 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
768 spin_unlock(vmf->ptl);
771 spin_unlock(vmf->ptl);
772 pte_free(vma->vm_mm, pgtable);
776 gfp = vma_thp_gfp_mask(vma);
777 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
778 if (unlikely(!page)) {
779 count_vm_event(THP_FAULT_FALLBACK);
780 return VM_FAULT_FALLBACK;
782 prep_transhuge_page(page);
783 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
786 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
787 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
790 struct mm_struct *mm = vma->vm_mm;
794 ptl = pmd_lock(mm, pmd);
795 if (!pmd_none(*pmd)) {
797 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
798 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
801 entry = pmd_mkyoung(*pmd);
802 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
803 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
804 update_mmu_cache_pmd(vma, addr, pmd);
810 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
811 if (pfn_t_devmap(pfn))
812 entry = pmd_mkdevmap(entry);
814 entry = pmd_mkyoung(pmd_mkdirty(entry));
815 entry = maybe_pmd_mkwrite(entry, vma);
819 pgtable_trans_huge_deposit(mm, pmd, pgtable);
824 set_pmd_at(mm, addr, pmd, entry);
825 update_mmu_cache_pmd(vma, addr, pmd);
830 pte_free(mm, pgtable);
834 * vmf_insert_pfn_pmd_prot - insert a pmd size pfn
835 * @vmf: Structure describing the fault
836 * @pfn: pfn to insert
837 * @pgprot: page protection to use
838 * @write: whether it's a write fault
840 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and
841 * also consult the vmf_insert_mixed_prot() documentation when
842 * @pgprot != @vmf->vma->vm_page_prot.
844 * Return: vm_fault_t value.
846 vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
847 pgprot_t pgprot, bool write)
849 unsigned long addr = vmf->address & PMD_MASK;
850 struct vm_area_struct *vma = vmf->vma;
851 pgtable_t pgtable = NULL;
854 * If we had pmd_special, we could avoid all these restrictions,
855 * but we need to be consistent with PTEs and architectures that
856 * can't support a 'special' bit.
858 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
860 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
861 (VM_PFNMAP|VM_MIXEDMAP));
862 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
864 if (addr < vma->vm_start || addr >= vma->vm_end)
865 return VM_FAULT_SIGBUS;
867 if (arch_needs_pgtable_deposit()) {
868 pgtable = pte_alloc_one(vma->vm_mm);
873 track_pfn_insert(vma, &pgprot, pfn);
875 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
876 return VM_FAULT_NOPAGE;
878 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot);
880 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
881 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
883 if (likely(vma->vm_flags & VM_WRITE))
884 pud = pud_mkwrite(pud);
888 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
889 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
891 struct mm_struct *mm = vma->vm_mm;
895 ptl = pud_lock(mm, pud);
896 if (!pud_none(*pud)) {
898 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
899 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
902 entry = pud_mkyoung(*pud);
903 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
904 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
905 update_mmu_cache_pud(vma, addr, pud);
910 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
911 if (pfn_t_devmap(pfn))
912 entry = pud_mkdevmap(entry);
914 entry = pud_mkyoung(pud_mkdirty(entry));
915 entry = maybe_pud_mkwrite(entry, vma);
917 set_pud_at(mm, addr, pud, entry);
918 update_mmu_cache_pud(vma, addr, pud);
925 * vmf_insert_pfn_pud_prot - insert a pud size pfn
926 * @vmf: Structure describing the fault
927 * @pfn: pfn to insert
928 * @pgprot: page protection to use
929 * @write: whether it's a write fault
931 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and
932 * also consult the vmf_insert_mixed_prot() documentation when
933 * @pgprot != @vmf->vma->vm_page_prot.
935 * Return: vm_fault_t value.
937 vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn,
938 pgprot_t pgprot, bool write)
940 unsigned long addr = vmf->address & PUD_MASK;
941 struct vm_area_struct *vma = vmf->vma;
944 * If we had pud_special, we could avoid all these restrictions,
945 * but we need to be consistent with PTEs and architectures that
946 * can't support a 'special' bit.
948 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
950 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
951 (VM_PFNMAP|VM_MIXEDMAP));
952 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
954 if (addr < vma->vm_start || addr >= vma->vm_end)
955 return VM_FAULT_SIGBUS;
957 track_pfn_insert(vma, &pgprot, pfn);
959 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
960 return VM_FAULT_NOPAGE;
962 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot);
963 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
965 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
966 pmd_t *pmd, int flags)
970 _pmd = pmd_mkyoung(*pmd);
971 if (flags & FOLL_WRITE)
972 _pmd = pmd_mkdirty(_pmd);
973 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
974 pmd, _pmd, flags & FOLL_WRITE))
975 update_mmu_cache_pmd(vma, addr, pmd);
978 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
979 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
981 unsigned long pfn = pmd_pfn(*pmd);
982 struct mm_struct *mm = vma->vm_mm;
985 assert_spin_locked(pmd_lockptr(mm, pmd));
988 * When we COW a devmap PMD entry, we split it into PTEs, so we should
989 * not be in this function with `flags & FOLL_COW` set.
991 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
993 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
994 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
995 (FOLL_PIN | FOLL_GET)))
998 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1001 if (pmd_present(*pmd) && pmd_devmap(*pmd))
1006 if (flags & FOLL_TOUCH)
1007 touch_pmd(vma, addr, pmd, flags);
1010 * device mapped pages can only be returned if the
1011 * caller will manage the page reference count.
1013 if (!(flags & (FOLL_GET | FOLL_PIN)))
1014 return ERR_PTR(-EEXIST);
1016 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
1017 *pgmap = get_dev_pagemap(pfn, *pgmap);
1019 return ERR_PTR(-EFAULT);
1020 page = pfn_to_page(pfn);
1021 if (!try_grab_page(page, flags))
1022 page = ERR_PTR(-ENOMEM);
1027 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1028 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1029 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1031 spinlock_t *dst_ptl, *src_ptl;
1032 struct page *src_page;
1034 pgtable_t pgtable = NULL;
1037 /* Skip if can be re-fill on fault */
1038 if (!vma_is_anonymous(dst_vma))
1041 pgtable = pte_alloc_one(dst_mm);
1042 if (unlikely(!pgtable))
1045 dst_ptl = pmd_lock(dst_mm, dst_pmd);
1046 src_ptl = pmd_lockptr(src_mm, src_pmd);
1047 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1052 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1053 if (unlikely(is_swap_pmd(pmd))) {
1054 swp_entry_t entry = pmd_to_swp_entry(pmd);
1056 VM_BUG_ON(!is_pmd_migration_entry(pmd));
1057 if (is_writable_migration_entry(entry)) {
1058 entry = make_readable_migration_entry(
1060 pmd = swp_entry_to_pmd(entry);
1061 if (pmd_swp_soft_dirty(*src_pmd))
1062 pmd = pmd_swp_mksoft_dirty(pmd);
1063 if (pmd_swp_uffd_wp(*src_pmd))
1064 pmd = pmd_swp_mkuffd_wp(pmd);
1065 set_pmd_at(src_mm, addr, src_pmd, pmd);
1067 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1068 mm_inc_nr_ptes(dst_mm);
1069 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1070 if (!userfaultfd_wp(dst_vma))
1071 pmd = pmd_swp_clear_uffd_wp(pmd);
1072 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1078 if (unlikely(!pmd_trans_huge(pmd))) {
1079 pte_free(dst_mm, pgtable);
1083 * When page table lock is held, the huge zero pmd should not be
1084 * under splitting since we don't split the page itself, only pmd to
1087 if (is_huge_zero_pmd(pmd)) {
1089 * get_huge_zero_page() will never allocate a new page here,
1090 * since we already have a zero page to copy. It just takes a
1093 mm_get_huge_zero_page(dst_mm);
1097 src_page = pmd_page(pmd);
1098 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1101 * If this page is a potentially pinned page, split and retry the fault
1102 * with smaller page size. Normally this should not happen because the
1103 * userspace should use MADV_DONTFORK upon pinned regions. This is a
1104 * best effort that the pinned pages won't be replaced by another
1105 * random page during the coming copy-on-write.
1107 if (unlikely(page_needs_cow_for_dma(src_vma, src_page))) {
1108 pte_free(dst_mm, pgtable);
1109 spin_unlock(src_ptl);
1110 spin_unlock(dst_ptl);
1111 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL);
1116 page_dup_rmap(src_page, true);
1117 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1119 mm_inc_nr_ptes(dst_mm);
1120 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1121 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1122 if (!userfaultfd_wp(dst_vma))
1123 pmd = pmd_clear_uffd_wp(pmd);
1124 pmd = pmd_mkold(pmd_wrprotect(pmd));
1125 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1129 spin_unlock(src_ptl);
1130 spin_unlock(dst_ptl);
1135 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1136 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1137 pud_t *pud, int flags)
1141 _pud = pud_mkyoung(*pud);
1142 if (flags & FOLL_WRITE)
1143 _pud = pud_mkdirty(_pud);
1144 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1145 pud, _pud, flags & FOLL_WRITE))
1146 update_mmu_cache_pud(vma, addr, pud);
1149 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1150 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1152 unsigned long pfn = pud_pfn(*pud);
1153 struct mm_struct *mm = vma->vm_mm;
1156 assert_spin_locked(pud_lockptr(mm, pud));
1158 if (flags & FOLL_WRITE && !pud_write(*pud))
1161 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
1162 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
1163 (FOLL_PIN | FOLL_GET)))
1166 if (pud_present(*pud) && pud_devmap(*pud))
1171 if (flags & FOLL_TOUCH)
1172 touch_pud(vma, addr, pud, flags);
1175 * device mapped pages can only be returned if the
1176 * caller will manage the page reference count.
1178 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here:
1180 if (!(flags & (FOLL_GET | FOLL_PIN)))
1181 return ERR_PTR(-EEXIST);
1183 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1184 *pgmap = get_dev_pagemap(pfn, *pgmap);
1186 return ERR_PTR(-EFAULT);
1187 page = pfn_to_page(pfn);
1188 if (!try_grab_page(page, flags))
1189 page = ERR_PTR(-ENOMEM);
1194 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1195 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1196 struct vm_area_struct *vma)
1198 spinlock_t *dst_ptl, *src_ptl;
1202 dst_ptl = pud_lock(dst_mm, dst_pud);
1203 src_ptl = pud_lockptr(src_mm, src_pud);
1204 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1208 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1212 * When page table lock is held, the huge zero pud should not be
1213 * under splitting since we don't split the page itself, only pud to
1216 if (is_huge_zero_pud(pud)) {
1217 /* No huge zero pud yet */
1220 /* Please refer to comments in copy_huge_pmd() */
1221 if (unlikely(page_needs_cow_for_dma(vma, pud_page(pud)))) {
1222 spin_unlock(src_ptl);
1223 spin_unlock(dst_ptl);
1224 __split_huge_pud(vma, src_pud, addr);
1228 pudp_set_wrprotect(src_mm, addr, src_pud);
1229 pud = pud_mkold(pud_wrprotect(pud));
1230 set_pud_at(dst_mm, addr, dst_pud, pud);
1234 spin_unlock(src_ptl);
1235 spin_unlock(dst_ptl);
1239 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1242 unsigned long haddr;
1243 bool write = vmf->flags & FAULT_FLAG_WRITE;
1245 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1246 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1249 entry = pud_mkyoung(orig_pud);
1251 entry = pud_mkdirty(entry);
1252 haddr = vmf->address & HPAGE_PUD_MASK;
1253 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1254 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1257 spin_unlock(vmf->ptl);
1259 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1261 void huge_pmd_set_accessed(struct vm_fault *vmf)
1264 unsigned long haddr;
1265 bool write = vmf->flags & FAULT_FLAG_WRITE;
1266 pmd_t orig_pmd = vmf->orig_pmd;
1268 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1269 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1272 entry = pmd_mkyoung(orig_pmd);
1274 entry = pmd_mkdirty(entry);
1275 haddr = vmf->address & HPAGE_PMD_MASK;
1276 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1277 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1280 spin_unlock(vmf->ptl);
1283 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf)
1285 struct vm_area_struct *vma = vmf->vma;
1287 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1288 pmd_t orig_pmd = vmf->orig_pmd;
1290 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1291 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1293 if (is_huge_zero_pmd(orig_pmd))
1296 spin_lock(vmf->ptl);
1298 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1299 spin_unlock(vmf->ptl);
1303 page = pmd_page(orig_pmd);
1304 VM_BUG_ON_PAGE(!PageHead(page), page);
1306 /* Lock page for reuse_swap_page() */
1307 if (!trylock_page(page)) {
1309 spin_unlock(vmf->ptl);
1311 spin_lock(vmf->ptl);
1312 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1313 spin_unlock(vmf->ptl);
1322 * We can only reuse the page if nobody else maps the huge page or it's
1325 if (reuse_swap_page(page)) {
1327 entry = pmd_mkyoung(orig_pmd);
1328 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1329 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1330 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1332 spin_unlock(vmf->ptl);
1333 return VM_FAULT_WRITE;
1337 spin_unlock(vmf->ptl);
1339 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
1340 return VM_FAULT_FALLBACK;
1344 * FOLL_FORCE can write to even unwritable pmd's, but only
1345 * after we've gone through a COW cycle and they are dirty.
1347 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1349 return pmd_write(pmd) ||
1350 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1353 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1358 struct mm_struct *mm = vma->vm_mm;
1359 struct page *page = NULL;
1361 assert_spin_locked(pmd_lockptr(mm, pmd));
1363 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1366 /* Avoid dumping huge zero page */
1367 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1368 return ERR_PTR(-EFAULT);
1370 /* Full NUMA hinting faults to serialise migration in fault paths */
1371 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1374 page = pmd_page(*pmd);
1375 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1377 if (!try_grab_page(page, flags))
1378 return ERR_PTR(-ENOMEM);
1380 if (flags & FOLL_TOUCH)
1381 touch_pmd(vma, addr, pmd, flags);
1383 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1385 * We don't mlock() pte-mapped THPs. This way we can avoid
1386 * leaking mlocked pages into non-VM_LOCKED VMAs.
1390 * In most cases the pmd is the only mapping of the page as we
1391 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1392 * writable private mappings in populate_vma_page_range().
1394 * The only scenario when we have the page shared here is if we
1395 * mlocking read-only mapping shared over fork(). We skip
1396 * mlocking such pages.
1400 * We can expect PageDoubleMap() to be stable under page lock:
1401 * for file pages we set it in page_add_file_rmap(), which
1402 * requires page to be locked.
1405 if (PageAnon(page) && compound_mapcount(page) != 1)
1407 if (PageDoubleMap(page) || !page->mapping)
1409 if (!trylock_page(page))
1411 if (page->mapping && !PageDoubleMap(page))
1412 mlock_vma_page(page);
1416 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1417 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1423 /* NUMA hinting page fault entry point for trans huge pmds */
1424 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
1426 struct vm_area_struct *vma = vmf->vma;
1427 pmd_t oldpmd = vmf->orig_pmd;
1430 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1431 int page_nid = NUMA_NO_NODE;
1432 int target_nid, last_cpupid = -1;
1433 bool migrated = false;
1434 bool was_writable = pmd_savedwrite(oldpmd);
1437 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1438 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
1439 spin_unlock(vmf->ptl);
1443 pmd = pmd_modify(oldpmd, vma->vm_page_prot);
1444 page = vm_normal_page_pmd(vma, haddr, pmd);
1448 /* See similar comment in do_numa_page for explanation */
1450 flags |= TNF_NO_GROUP;
1452 page_nid = page_to_nid(page);
1453 last_cpupid = page_cpupid_last(page);
1454 target_nid = numa_migrate_prep(page, vma, haddr, page_nid,
1457 if (target_nid == NUMA_NO_NODE) {
1462 spin_unlock(vmf->ptl);
1464 migrated = migrate_misplaced_page(page, vma, target_nid);
1466 flags |= TNF_MIGRATED;
1467 page_nid = target_nid;
1469 flags |= TNF_MIGRATE_FAIL;
1470 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1471 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
1472 spin_unlock(vmf->ptl);
1479 if (page_nid != NUMA_NO_NODE)
1480 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1486 /* Restore the PMD */
1487 pmd = pmd_modify(oldpmd, vma->vm_page_prot);
1488 pmd = pmd_mkyoung(pmd);
1490 pmd = pmd_mkwrite(pmd);
1491 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1492 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1493 spin_unlock(vmf->ptl);
1498 * Return true if we do MADV_FREE successfully on entire pmd page.
1499 * Otherwise, return false.
1501 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1502 pmd_t *pmd, unsigned long addr, unsigned long next)
1507 struct mm_struct *mm = tlb->mm;
1510 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1512 ptl = pmd_trans_huge_lock(pmd, vma);
1517 if (is_huge_zero_pmd(orig_pmd))
1520 if (unlikely(!pmd_present(orig_pmd))) {
1521 VM_BUG_ON(thp_migration_supported() &&
1522 !is_pmd_migration_entry(orig_pmd));
1526 page = pmd_page(orig_pmd);
1528 * If other processes are mapping this page, we couldn't discard
1529 * the page unless they all do MADV_FREE so let's skip the page.
1531 if (total_mapcount(page) != 1)
1534 if (!trylock_page(page))
1538 * If user want to discard part-pages of THP, split it so MADV_FREE
1539 * will deactivate only them.
1541 if (next - addr != HPAGE_PMD_SIZE) {
1544 split_huge_page(page);
1550 if (PageDirty(page))
1551 ClearPageDirty(page);
1554 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1555 pmdp_invalidate(vma, addr, pmd);
1556 orig_pmd = pmd_mkold(orig_pmd);
1557 orig_pmd = pmd_mkclean(orig_pmd);
1559 set_pmd_at(mm, addr, pmd, orig_pmd);
1560 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1563 mark_page_lazyfree(page);
1571 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1575 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1576 pte_free(mm, pgtable);
1580 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1581 pmd_t *pmd, unsigned long addr)
1586 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1588 ptl = __pmd_trans_huge_lock(pmd, vma);
1592 * For architectures like ppc64 we look at deposited pgtable
1593 * when calling pmdp_huge_get_and_clear. So do the
1594 * pgtable_trans_huge_withdraw after finishing pmdp related
1597 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd,
1599 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1600 if (vma_is_special_huge(vma)) {
1601 if (arch_needs_pgtable_deposit())
1602 zap_deposited_table(tlb->mm, pmd);
1604 } else if (is_huge_zero_pmd(orig_pmd)) {
1605 zap_deposited_table(tlb->mm, pmd);
1608 struct page *page = NULL;
1609 int flush_needed = 1;
1611 if (pmd_present(orig_pmd)) {
1612 page = pmd_page(orig_pmd);
1613 page_remove_rmap(page, true);
1614 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1615 VM_BUG_ON_PAGE(!PageHead(page), page);
1616 } else if (thp_migration_supported()) {
1619 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1620 entry = pmd_to_swp_entry(orig_pmd);
1621 page = pfn_swap_entry_to_page(entry);
1624 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1626 if (PageAnon(page)) {
1627 zap_deposited_table(tlb->mm, pmd);
1628 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1630 if (arch_needs_pgtable_deposit())
1631 zap_deposited_table(tlb->mm, pmd);
1632 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1637 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1642 #ifndef pmd_move_must_withdraw
1643 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1644 spinlock_t *old_pmd_ptl,
1645 struct vm_area_struct *vma)
1648 * With split pmd lock we also need to move preallocated
1649 * PTE page table if new_pmd is on different PMD page table.
1651 * We also don't deposit and withdraw tables for file pages.
1653 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1657 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1659 #ifdef CONFIG_MEM_SOFT_DIRTY
1660 if (unlikely(is_pmd_migration_entry(pmd)))
1661 pmd = pmd_swp_mksoft_dirty(pmd);
1662 else if (pmd_present(pmd))
1663 pmd = pmd_mksoft_dirty(pmd);
1668 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1669 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
1671 spinlock_t *old_ptl, *new_ptl;
1673 struct mm_struct *mm = vma->vm_mm;
1674 bool force_flush = false;
1677 * The destination pmd shouldn't be established, free_pgtables()
1678 * should have release it.
1680 if (WARN_ON(!pmd_none(*new_pmd))) {
1681 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1686 * We don't have to worry about the ordering of src and dst
1687 * ptlocks because exclusive mmap_lock prevents deadlock.
1689 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1691 new_ptl = pmd_lockptr(mm, new_pmd);
1692 if (new_ptl != old_ptl)
1693 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1694 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1695 if (pmd_present(pmd))
1697 VM_BUG_ON(!pmd_none(*new_pmd));
1699 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1701 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1702 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1704 pmd = move_soft_dirty_pmd(pmd);
1705 set_pmd_at(mm, new_addr, new_pmd, pmd);
1707 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1708 if (new_ptl != old_ptl)
1709 spin_unlock(new_ptl);
1710 spin_unlock(old_ptl);
1718 * - 0 if PMD could not be locked
1719 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary
1720 * or if prot_numa but THP migration is not supported
1721 * - HPAGE_PMD_NR if protections changed and TLB flush necessary
1723 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1724 unsigned long addr, pgprot_t newprot, unsigned long cp_flags)
1726 struct mm_struct *mm = vma->vm_mm;
1729 bool preserve_write;
1731 bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
1732 bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
1733 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
1735 if (prot_numa && !thp_migration_supported())
1738 ptl = __pmd_trans_huge_lock(pmd, vma);
1742 preserve_write = prot_numa && pmd_write(*pmd);
1745 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1746 if (is_swap_pmd(*pmd)) {
1747 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1749 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1750 if (is_writable_migration_entry(entry)) {
1753 * A protection check is difficult so
1754 * just be safe and disable write
1756 entry = make_readable_migration_entry(
1758 newpmd = swp_entry_to_pmd(entry);
1759 if (pmd_swp_soft_dirty(*pmd))
1760 newpmd = pmd_swp_mksoft_dirty(newpmd);
1761 if (pmd_swp_uffd_wp(*pmd))
1762 newpmd = pmd_swp_mkuffd_wp(newpmd);
1763 set_pmd_at(mm, addr, pmd, newpmd);
1770 * Avoid trapping faults against the zero page. The read-only
1771 * data is likely to be read-cached on the local CPU and
1772 * local/remote hits to the zero page are not interesting.
1774 if (prot_numa && is_huge_zero_pmd(*pmd))
1777 if (prot_numa && pmd_protnone(*pmd))
1781 * In case prot_numa, we are under mmap_read_lock(mm). It's critical
1782 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1783 * which is also under mmap_read_lock(mm):
1786 * change_huge_pmd(prot_numa=1)
1787 * pmdp_huge_get_and_clear_notify()
1788 * madvise_dontneed()
1790 * pmd_trans_huge(*pmd) == 0 (without ptl)
1793 * // pmd is re-established
1795 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1796 * which may break userspace.
1798 * pmdp_invalidate() is required to make sure we don't miss
1799 * dirty/young flags set by hardware.
1801 entry = pmdp_invalidate(vma, addr, pmd);
1803 entry = pmd_modify(entry, newprot);
1805 entry = pmd_mk_savedwrite(entry);
1807 entry = pmd_wrprotect(entry);
1808 entry = pmd_mkuffd_wp(entry);
1809 } else if (uffd_wp_resolve) {
1811 * Leave the write bit to be handled by PF interrupt
1812 * handler, then things like COW could be properly
1815 entry = pmd_clear_uffd_wp(entry);
1818 set_pmd_at(mm, addr, pmd, entry);
1819 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1826 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1828 * Note that if it returns page table lock pointer, this routine returns without
1829 * unlocking page table lock. So callers must unlock it.
1831 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1834 ptl = pmd_lock(vma->vm_mm, pmd);
1835 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1843 * Returns true if a given pud maps a thp, false otherwise.
1845 * Note that if it returns true, this routine returns without unlocking page
1846 * table lock. So callers must unlock it.
1848 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1852 ptl = pud_lock(vma->vm_mm, pud);
1853 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1859 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1860 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1861 pud_t *pud, unsigned long addr)
1865 ptl = __pud_trans_huge_lock(pud, vma);
1869 * For architectures like ppc64 we look at deposited pgtable
1870 * when calling pudp_huge_get_and_clear. So do the
1871 * pgtable_trans_huge_withdraw after finishing pudp related
1874 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
1875 tlb_remove_pud_tlb_entry(tlb, pud, addr);
1876 if (vma_is_special_huge(vma)) {
1878 /* No zero page support yet */
1880 /* No support for anonymous PUD pages yet */
1886 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
1887 unsigned long haddr)
1889 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
1890 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1891 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
1892 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
1894 count_vm_event(THP_SPLIT_PUD);
1896 pudp_huge_clear_flush_notify(vma, haddr, pud);
1899 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
1900 unsigned long address)
1903 struct mmu_notifier_range range;
1905 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1906 address & HPAGE_PUD_MASK,
1907 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
1908 mmu_notifier_invalidate_range_start(&range);
1909 ptl = pud_lock(vma->vm_mm, pud);
1910 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
1912 __split_huge_pud_locked(vma, pud, range.start);
1917 * No need to double call mmu_notifier->invalidate_range() callback as
1918 * the above pudp_huge_clear_flush_notify() did already call it.
1920 mmu_notifier_invalidate_range_only_end(&range);
1922 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1924 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
1925 unsigned long haddr, pmd_t *pmd)
1927 struct mm_struct *mm = vma->vm_mm;
1933 * Leave pmd empty until pte is filled note that it is fine to delay
1934 * notification until mmu_notifier_invalidate_range_end() as we are
1935 * replacing a zero pmd write protected page with a zero pte write
1938 * See Documentation/vm/mmu_notifier.rst
1940 pmdp_huge_clear_flush(vma, haddr, pmd);
1942 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1943 pmd_populate(mm, &_pmd, pgtable);
1945 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1947 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
1948 entry = pte_mkspecial(entry);
1949 pte = pte_offset_map(&_pmd, haddr);
1950 VM_BUG_ON(!pte_none(*pte));
1951 set_pte_at(mm, haddr, pte, entry);
1954 smp_wmb(); /* make pte visible before pmd */
1955 pmd_populate(mm, pmd, pgtable);
1958 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
1959 unsigned long haddr, bool freeze)
1961 struct mm_struct *mm = vma->vm_mm;
1964 pmd_t old_pmd, _pmd;
1965 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
1969 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
1970 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1971 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
1972 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
1973 && !pmd_devmap(*pmd));
1975 count_vm_event(THP_SPLIT_PMD);
1977 if (!vma_is_anonymous(vma)) {
1978 old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
1980 * We are going to unmap this huge page. So
1981 * just go ahead and zap it
1983 if (arch_needs_pgtable_deposit())
1984 zap_deposited_table(mm, pmd);
1985 if (vma_is_special_huge(vma))
1987 if (unlikely(is_pmd_migration_entry(old_pmd))) {
1990 entry = pmd_to_swp_entry(old_pmd);
1991 page = pfn_swap_entry_to_page(entry);
1993 page = pmd_page(old_pmd);
1994 if (!PageDirty(page) && pmd_dirty(old_pmd))
1995 set_page_dirty(page);
1996 if (!PageReferenced(page) && pmd_young(old_pmd))
1997 SetPageReferenced(page);
1998 page_remove_rmap(page, true);
2001 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2005 if (is_huge_zero_pmd(*pmd)) {
2007 * FIXME: Do we want to invalidate secondary mmu by calling
2008 * mmu_notifier_invalidate_range() see comments below inside
2009 * __split_huge_pmd() ?
2011 * We are going from a zero huge page write protected to zero
2012 * small page also write protected so it does not seems useful
2013 * to invalidate secondary mmu at this time.
2015 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2019 * Up to this point the pmd is present and huge and userland has the
2020 * whole access to the hugepage during the split (which happens in
2021 * place). If we overwrite the pmd with the not-huge version pointing
2022 * to the pte here (which of course we could if all CPUs were bug
2023 * free), userland could trigger a small page size TLB miss on the
2024 * small sized TLB while the hugepage TLB entry is still established in
2025 * the huge TLB. Some CPU doesn't like that.
2026 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum
2027 * 383 on page 105. Intel should be safe but is also warns that it's
2028 * only safe if the permission and cache attributes of the two entries
2029 * loaded in the two TLB is identical (which should be the case here).
2030 * But it is generally safer to never allow small and huge TLB entries
2031 * for the same virtual address to be loaded simultaneously. So instead
2032 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2033 * current pmd notpresent (atomically because here the pmd_trans_huge
2034 * must remain set at all times on the pmd until the split is complete
2035 * for this pmd), then we flush the SMP TLB and finally we write the
2036 * non-huge version of the pmd entry with pmd_populate.
2038 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2040 pmd_migration = is_pmd_migration_entry(old_pmd);
2041 if (unlikely(pmd_migration)) {
2044 entry = pmd_to_swp_entry(old_pmd);
2045 page = pfn_swap_entry_to_page(entry);
2046 write = is_writable_migration_entry(entry);
2048 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2049 uffd_wp = pmd_swp_uffd_wp(old_pmd);
2051 page = pmd_page(old_pmd);
2052 if (pmd_dirty(old_pmd))
2054 write = pmd_write(old_pmd);
2055 young = pmd_young(old_pmd);
2056 soft_dirty = pmd_soft_dirty(old_pmd);
2057 uffd_wp = pmd_uffd_wp(old_pmd);
2059 VM_BUG_ON_PAGE(!page_count(page), page);
2060 page_ref_add(page, HPAGE_PMD_NR - 1);
2063 * Withdraw the table only after we mark the pmd entry invalid.
2064 * This's critical for some architectures (Power).
2066 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2067 pmd_populate(mm, &_pmd, pgtable);
2069 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2072 * Note that NUMA hinting access restrictions are not
2073 * transferred to avoid any possibility of altering
2074 * permissions across VMAs.
2076 if (freeze || pmd_migration) {
2077 swp_entry_t swp_entry;
2079 swp_entry = make_writable_migration_entry(
2080 page_to_pfn(page + i));
2082 swp_entry = make_readable_migration_entry(
2083 page_to_pfn(page + i));
2084 entry = swp_entry_to_pte(swp_entry);
2086 entry = pte_swp_mksoft_dirty(entry);
2088 entry = pte_swp_mkuffd_wp(entry);
2090 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2091 entry = maybe_mkwrite(entry, vma);
2093 entry = pte_wrprotect(entry);
2095 entry = pte_mkold(entry);
2097 entry = pte_mksoft_dirty(entry);
2099 entry = pte_mkuffd_wp(entry);
2101 pte = pte_offset_map(&_pmd, addr);
2102 BUG_ON(!pte_none(*pte));
2103 set_pte_at(mm, addr, pte, entry);
2105 atomic_inc(&page[i]._mapcount);
2109 if (!pmd_migration) {
2111 * Set PG_double_map before dropping compound_mapcount to avoid
2112 * false-negative page_mapped().
2114 if (compound_mapcount(page) > 1 &&
2115 !TestSetPageDoubleMap(page)) {
2116 for (i = 0; i < HPAGE_PMD_NR; i++)
2117 atomic_inc(&page[i]._mapcount);
2120 lock_page_memcg(page);
2121 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2122 /* Last compound_mapcount is gone. */
2123 __mod_lruvec_page_state(page, NR_ANON_THPS,
2125 if (TestClearPageDoubleMap(page)) {
2126 /* No need in mapcount reference anymore */
2127 for (i = 0; i < HPAGE_PMD_NR; i++)
2128 atomic_dec(&page[i]._mapcount);
2131 unlock_page_memcg(page);
2134 smp_wmb(); /* make pte visible before pmd */
2135 pmd_populate(mm, pmd, pgtable);
2138 for (i = 0; i < HPAGE_PMD_NR; i++) {
2139 page_remove_rmap(page + i, false);
2145 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2146 unsigned long address, bool freeze, struct page *page)
2149 struct mmu_notifier_range range;
2150 bool do_unlock_page = false;
2153 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2154 address & HPAGE_PMD_MASK,
2155 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2156 mmu_notifier_invalidate_range_start(&range);
2157 ptl = pmd_lock(vma->vm_mm, pmd);
2160 * If caller asks to setup a migration entries, we need a page to check
2161 * pmd against. Otherwise we can end up replacing wrong page.
2163 VM_BUG_ON(freeze && !page);
2165 VM_WARN_ON_ONCE(!PageLocked(page));
2166 if (page != pmd_page(*pmd))
2171 if (pmd_trans_huge(*pmd)) {
2173 page = pmd_page(*pmd);
2175 * An anonymous page must be locked, to ensure that a
2176 * concurrent reuse_swap_page() sees stable mapcount;
2177 * but reuse_swap_page() is not used on shmem or file,
2178 * and page lock must not be taken when zap_pmd_range()
2179 * calls __split_huge_pmd() while i_mmap_lock is held.
2181 if (PageAnon(page)) {
2182 if (unlikely(!trylock_page(page))) {
2188 if (unlikely(!pmd_same(*pmd, _pmd))) {
2196 do_unlock_page = true;
2199 if (PageMlocked(page))
2200 clear_page_mlock(page);
2201 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2203 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2209 * No need to double call mmu_notifier->invalidate_range() callback.
2210 * They are 3 cases to consider inside __split_huge_pmd_locked():
2211 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2212 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2213 * fault will trigger a flush_notify before pointing to a new page
2214 * (it is fine if the secondary mmu keeps pointing to the old zero
2215 * page in the meantime)
2216 * 3) Split a huge pmd into pte pointing to the same page. No need
2217 * to invalidate secondary tlb entry they are all still valid.
2218 * any further changes to individual pte will notify. So no need
2219 * to call mmu_notifier->invalidate_range()
2221 mmu_notifier_invalidate_range_only_end(&range);
2224 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2225 bool freeze, struct page *page)
2232 pgd = pgd_offset(vma->vm_mm, address);
2233 if (!pgd_present(*pgd))
2236 p4d = p4d_offset(pgd, address);
2237 if (!p4d_present(*p4d))
2240 pud = pud_offset(p4d, address);
2241 if (!pud_present(*pud))
2244 pmd = pmd_offset(pud, address);
2246 __split_huge_pmd(vma, pmd, address, freeze, page);
2249 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address)
2252 * If the new address isn't hpage aligned and it could previously
2253 * contain an hugepage: check if we need to split an huge pmd.
2255 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) &&
2256 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE),
2257 ALIGN(address, HPAGE_PMD_SIZE)))
2258 split_huge_pmd_address(vma, address, false, NULL);
2261 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2262 unsigned long start,
2266 /* Check if we need to split start first. */
2267 split_huge_pmd_if_needed(vma, start);
2269 /* Check if we need to split end next. */
2270 split_huge_pmd_if_needed(vma, end);
2273 * If we're also updating the vma->vm_next->vm_start,
2274 * check if we need to split it.
2276 if (adjust_next > 0) {
2277 struct vm_area_struct *next = vma->vm_next;
2278 unsigned long nstart = next->vm_start;
2279 nstart += adjust_next;
2280 split_huge_pmd_if_needed(next, nstart);
2284 static void unmap_page(struct page *page)
2286 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD |
2289 VM_BUG_ON_PAGE(!PageHead(page), page);
2292 * Anon pages need migration entries to preserve them, but file
2293 * pages can simply be left unmapped, then faulted back on demand.
2294 * If that is ever changed (perhaps for mlock), update remap_page().
2297 try_to_migrate(page, ttu_flags);
2299 try_to_unmap(page, ttu_flags | TTU_IGNORE_MLOCK);
2301 VM_WARN_ON_ONCE_PAGE(page_mapped(page), page);
2304 static void remap_page(struct page *page, unsigned int nr)
2308 /* If unmap_page() uses try_to_migrate() on file, remove this check */
2309 if (!PageAnon(page))
2311 if (PageTransHuge(page)) {
2312 remove_migration_ptes(page, page, true);
2314 for (i = 0; i < nr; i++)
2315 remove_migration_ptes(page + i, page + i, true);
2319 static void lru_add_page_tail(struct page *head, struct page *tail,
2320 struct lruvec *lruvec, struct list_head *list)
2322 VM_BUG_ON_PAGE(!PageHead(head), head);
2323 VM_BUG_ON_PAGE(PageCompound(tail), head);
2324 VM_BUG_ON_PAGE(PageLRU(tail), head);
2325 lockdep_assert_held(&lruvec->lru_lock);
2328 /* page reclaim is reclaiming a huge page */
2329 VM_WARN_ON(PageLRU(head));
2331 list_add_tail(&tail->lru, list);
2333 /* head is still on lru (and we have it frozen) */
2334 VM_WARN_ON(!PageLRU(head));
2336 list_add_tail(&tail->lru, &head->lru);
2340 static void __split_huge_page_tail(struct page *head, int tail,
2341 struct lruvec *lruvec, struct list_head *list)
2343 struct page *page_tail = head + tail;
2345 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2348 * Clone page flags before unfreezing refcount.
2350 * After successful get_page_unless_zero() might follow flags change,
2351 * for example lock_page() which set PG_waiters.
2353 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2354 page_tail->flags |= (head->flags &
2355 ((1L << PG_referenced) |
2356 (1L << PG_swapbacked) |
2357 (1L << PG_swapcache) |
2358 (1L << PG_mlocked) |
2359 (1L << PG_uptodate) |
2361 (1L << PG_workingset) |
2363 (1L << PG_unevictable) |
2369 /* ->mapping in first tail page is compound_mapcount */
2370 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2372 page_tail->mapping = head->mapping;
2373 page_tail->index = head->index + tail;
2375 /* Page flags must be visible before we make the page non-compound. */
2379 * Clear PageTail before unfreezing page refcount.
2381 * After successful get_page_unless_zero() might follow put_page()
2382 * which needs correct compound_head().
2384 clear_compound_head(page_tail);
2386 /* Finally unfreeze refcount. Additional reference from page cache. */
2387 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2388 PageSwapCache(head)));
2390 if (page_is_young(head))
2391 set_page_young(page_tail);
2392 if (page_is_idle(head))
2393 set_page_idle(page_tail);
2395 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2398 * always add to the tail because some iterators expect new
2399 * pages to show after the currently processed elements - e.g.
2402 lru_add_page_tail(head, page_tail, lruvec, list);
2405 static void __split_huge_page(struct page *page, struct list_head *list,
2408 struct folio *folio = page_folio(page);
2409 struct page *head = &folio->page;
2410 struct lruvec *lruvec;
2411 struct address_space *swap_cache = NULL;
2412 unsigned long offset = 0;
2413 unsigned int nr = thp_nr_pages(head);
2416 /* complete memcg works before add pages to LRU */
2417 split_page_memcg(head, nr);
2419 if (PageAnon(head) && PageSwapCache(head)) {
2420 swp_entry_t entry = { .val = page_private(head) };
2422 offset = swp_offset(entry);
2423 swap_cache = swap_address_space(entry);
2424 xa_lock(&swap_cache->i_pages);
2427 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
2428 lruvec = folio_lruvec_lock(folio);
2430 ClearPageHasHWPoisoned(head);
2432 for (i = nr - 1; i >= 1; i--) {
2433 __split_huge_page_tail(head, i, lruvec, list);
2434 /* Some pages can be beyond EOF: drop them from page cache */
2435 if (head[i].index >= end) {
2436 ClearPageDirty(head + i);
2437 __delete_from_page_cache(head + i, NULL);
2438 if (shmem_mapping(head->mapping))
2439 shmem_uncharge(head->mapping->host, 1);
2441 } else if (!PageAnon(page)) {
2442 __xa_store(&head->mapping->i_pages, head[i].index,
2444 } else if (swap_cache) {
2445 __xa_store(&swap_cache->i_pages, offset + i,
2450 ClearPageCompound(head);
2451 unlock_page_lruvec(lruvec);
2452 /* Caller disabled irqs, so they are still disabled here */
2454 split_page_owner(head, nr);
2456 /* See comment in __split_huge_page_tail() */
2457 if (PageAnon(head)) {
2458 /* Additional pin to swap cache */
2459 if (PageSwapCache(head)) {
2460 page_ref_add(head, 2);
2461 xa_unlock(&swap_cache->i_pages);
2466 /* Additional pin to page cache */
2467 page_ref_add(head, 2);
2468 xa_unlock(&head->mapping->i_pages);
2472 remap_page(head, nr);
2474 if (PageSwapCache(head)) {
2475 swp_entry_t entry = { .val = page_private(head) };
2477 split_swap_cluster(entry);
2480 for (i = 0; i < nr; i++) {
2481 struct page *subpage = head + i;
2482 if (subpage == page)
2484 unlock_page(subpage);
2487 * Subpages may be freed if there wasn't any mapping
2488 * like if add_to_swap() is running on a lru page that
2489 * had its mapping zapped. And freeing these pages
2490 * requires taking the lru_lock so we do the put_page
2491 * of the tail pages after the split is complete.
2497 int total_mapcount(struct page *page)
2499 int i, compound, nr, ret;
2501 VM_BUG_ON_PAGE(PageTail(page), page);
2503 if (likely(!PageCompound(page)))
2504 return atomic_read(&page->_mapcount) + 1;
2506 compound = compound_mapcount(page);
2507 nr = compound_nr(page);
2511 for (i = 0; i < nr; i++)
2512 ret += atomic_read(&page[i]._mapcount) + 1;
2513 /* File pages has compound_mapcount included in _mapcount */
2514 if (!PageAnon(page))
2515 return ret - compound * nr;
2516 if (PageDoubleMap(page))
2522 * This calculates accurately how many mappings a transparent hugepage
2523 * has (unlike page_mapcount() which isn't fully accurate). This full
2524 * accuracy is primarily needed to know if copy-on-write faults can
2525 * reuse the page and change the mapping to read-write instead of
2526 * copying them. At the same time this returns the total_mapcount too.
2528 * The function returns the highest mapcount any one of the subpages
2529 * has. If the return value is one, even if different processes are
2530 * mapping different subpages of the transparent hugepage, they can
2531 * all reuse it, because each process is reusing a different subpage.
2533 * The total_mapcount is instead counting all virtual mappings of the
2534 * subpages. If the total_mapcount is equal to "one", it tells the
2535 * caller all mappings belong to the same "mm" and in turn the
2536 * anon_vma of the transparent hugepage can become the vma->anon_vma
2537 * local one as no other process may be mapping any of the subpages.
2539 * It would be more accurate to replace page_mapcount() with
2540 * page_trans_huge_mapcount(), however we only use
2541 * page_trans_huge_mapcount() in the copy-on-write faults where we
2542 * need full accuracy to avoid breaking page pinning, because
2543 * page_trans_huge_mapcount() is slower than page_mapcount().
2545 int page_trans_huge_mapcount(struct page *page)
2549 /* hugetlbfs shouldn't call it */
2550 VM_BUG_ON_PAGE(PageHuge(page), page);
2552 if (likely(!PageTransCompound(page)))
2553 return atomic_read(&page->_mapcount) + 1;
2555 page = compound_head(page);
2558 for (i = 0; i < thp_nr_pages(page); i++) {
2559 int mapcount = atomic_read(&page[i]._mapcount) + 1;
2560 ret = max(ret, mapcount);
2563 if (PageDoubleMap(page))
2566 return ret + compound_mapcount(page);
2569 /* Racy check whether the huge page can be split */
2570 bool can_split_huge_page(struct page *page, int *pextra_pins)
2574 /* Additional pins from page cache */
2576 extra_pins = PageSwapCache(page) ? thp_nr_pages(page) : 0;
2578 extra_pins = thp_nr_pages(page);
2580 *pextra_pins = extra_pins;
2581 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2585 * This function splits huge page into normal pages. @page can point to any
2586 * subpage of huge page to split. Split doesn't change the position of @page.
2588 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2589 * The huge page must be locked.
2591 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2593 * Both head page and tail pages will inherit mapping, flags, and so on from
2596 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2597 * they are not mapped.
2599 * Returns 0 if the hugepage is split successfully.
2600 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2603 int split_huge_page_to_list(struct page *page, struct list_head *list)
2605 struct page *head = compound_head(page);
2606 struct deferred_split *ds_queue = get_deferred_split_queue(head);
2607 struct anon_vma *anon_vma = NULL;
2608 struct address_space *mapping = NULL;
2609 int extra_pins, ret;
2612 VM_BUG_ON_PAGE(is_huge_zero_page(head), head);
2613 VM_BUG_ON_PAGE(!PageLocked(head), head);
2614 VM_BUG_ON_PAGE(!PageCompound(head), head);
2616 if (PageWriteback(head))
2619 if (PageAnon(head)) {
2621 * The caller does not necessarily hold an mmap_lock that would
2622 * prevent the anon_vma disappearing so we first we take a
2623 * reference to it and then lock the anon_vma for write. This
2624 * is similar to page_lock_anon_vma_read except the write lock
2625 * is taken to serialise against parallel split or collapse
2628 anon_vma = page_get_anon_vma(head);
2635 anon_vma_lock_write(anon_vma);
2637 mapping = head->mapping;
2646 i_mmap_lock_read(mapping);
2649 *__split_huge_page() may need to trim off pages beyond EOF:
2650 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2651 * which cannot be nested inside the page tree lock. So note
2652 * end now: i_size itself may be changed at any moment, but
2653 * head page lock is good enough to serialize the trimming.
2655 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2656 if (shmem_mapping(mapping))
2657 end = shmem_fallocend(mapping->host, end);
2661 * Racy check if we can split the page, before unmap_page() will
2664 if (!can_split_huge_page(head, &extra_pins)) {
2671 /* block interrupt reentry in xa_lock and spinlock */
2672 local_irq_disable();
2674 XA_STATE(xas, &mapping->i_pages, page_index(head));
2677 * Check if the head page is present in page cache.
2678 * We assume all tail are present too, if head is there.
2680 xa_lock(&mapping->i_pages);
2681 if (xas_load(&xas) != head)
2685 /* Prevent deferred_split_scan() touching ->_refcount */
2686 spin_lock(&ds_queue->split_queue_lock);
2687 if (page_ref_freeze(head, 1 + extra_pins)) {
2688 if (!list_empty(page_deferred_list(head))) {
2689 ds_queue->split_queue_len--;
2690 list_del(page_deferred_list(head));
2692 spin_unlock(&ds_queue->split_queue_lock);
2694 int nr = thp_nr_pages(head);
2696 if (PageSwapBacked(head)) {
2697 __mod_lruvec_page_state(head, NR_SHMEM_THPS,
2700 __mod_lruvec_page_state(head, NR_FILE_THPS,
2702 filemap_nr_thps_dec(mapping);
2706 __split_huge_page(page, list, end);
2709 spin_unlock(&ds_queue->split_queue_lock);
2712 xa_unlock(&mapping->i_pages);
2714 remap_page(head, thp_nr_pages(head));
2720 anon_vma_unlock_write(anon_vma);
2721 put_anon_vma(anon_vma);
2724 i_mmap_unlock_read(mapping);
2726 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2730 void free_transhuge_page(struct page *page)
2732 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2733 unsigned long flags;
2735 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2736 if (!list_empty(page_deferred_list(page))) {
2737 ds_queue->split_queue_len--;
2738 list_del(page_deferred_list(page));
2740 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2741 free_compound_page(page);
2744 void deferred_split_huge_page(struct page *page)
2746 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2748 struct mem_cgroup *memcg = page_memcg(compound_head(page));
2750 unsigned long flags;
2752 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2755 * The try_to_unmap() in page reclaim path might reach here too,
2756 * this may cause a race condition to corrupt deferred split queue.
2757 * And, if page reclaim is already handling the same page, it is
2758 * unnecessary to handle it again in shrinker.
2760 * Check PageSwapCache to determine if the page is being
2761 * handled by page reclaim since THP swap would add the page into
2762 * swap cache before calling try_to_unmap().
2764 if (PageSwapCache(page))
2767 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2768 if (list_empty(page_deferred_list(page))) {
2769 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2770 list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
2771 ds_queue->split_queue_len++;
2774 set_shrinker_bit(memcg, page_to_nid(page),
2775 deferred_split_shrinker.id);
2778 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2781 static unsigned long deferred_split_count(struct shrinker *shrink,
2782 struct shrink_control *sc)
2784 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2785 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2789 ds_queue = &sc->memcg->deferred_split_queue;
2791 return READ_ONCE(ds_queue->split_queue_len);
2794 static unsigned long deferred_split_scan(struct shrinker *shrink,
2795 struct shrink_control *sc)
2797 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2798 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2799 unsigned long flags;
2800 LIST_HEAD(list), *pos, *next;
2806 ds_queue = &sc->memcg->deferred_split_queue;
2809 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2810 /* Take pin on all head pages to avoid freeing them under us */
2811 list_for_each_safe(pos, next, &ds_queue->split_queue) {
2812 page = list_entry((void *)pos, struct page, deferred_list);
2813 page = compound_head(page);
2814 if (get_page_unless_zero(page)) {
2815 list_move(page_deferred_list(page), &list);
2817 /* We lost race with put_compound_page() */
2818 list_del_init(page_deferred_list(page));
2819 ds_queue->split_queue_len--;
2821 if (!--sc->nr_to_scan)
2824 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2826 list_for_each_safe(pos, next, &list) {
2827 page = list_entry((void *)pos, struct page, deferred_list);
2828 if (!trylock_page(page))
2830 /* split_huge_page() removes page from list on success */
2831 if (!split_huge_page(page))
2838 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2839 list_splice_tail(&list, &ds_queue->split_queue);
2840 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2843 * Stop shrinker if we didn't split any page, but the queue is empty.
2844 * This can happen if pages were freed under us.
2846 if (!split && list_empty(&ds_queue->split_queue))
2851 static struct shrinker deferred_split_shrinker = {
2852 .count_objects = deferred_split_count,
2853 .scan_objects = deferred_split_scan,
2854 .seeks = DEFAULT_SEEKS,
2855 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
2859 #ifdef CONFIG_DEBUG_FS
2860 static void split_huge_pages_all(void)
2864 unsigned long pfn, max_zone_pfn;
2865 unsigned long total = 0, split = 0;
2867 pr_debug("Split all THPs\n");
2868 for_each_populated_zone(zone) {
2869 max_zone_pfn = zone_end_pfn(zone);
2870 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2871 if (!pfn_valid(pfn))
2874 page = pfn_to_page(pfn);
2875 if (!get_page_unless_zero(page))
2878 if (zone != page_zone(page))
2881 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2886 if (!split_huge_page(page))
2895 pr_debug("%lu of %lu THP split\n", split, total);
2898 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma)
2900 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) ||
2901 is_vm_hugetlb_page(vma);
2904 static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
2905 unsigned long vaddr_end)
2908 struct task_struct *task;
2909 struct mm_struct *mm;
2910 unsigned long total = 0, split = 0;
2913 vaddr_start &= PAGE_MASK;
2914 vaddr_end &= PAGE_MASK;
2916 /* Find the task_struct from pid */
2918 task = find_task_by_vpid(pid);
2924 get_task_struct(task);
2927 /* Find the mm_struct */
2928 mm = get_task_mm(task);
2929 put_task_struct(task);
2936 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n",
2937 pid, vaddr_start, vaddr_end);
2941 * always increase addr by PAGE_SIZE, since we could have a PTE page
2942 * table filled with PTE-mapped THPs, each of which is distinct.
2944 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) {
2945 struct vm_area_struct *vma = find_vma(mm, addr);
2946 unsigned int follflags;
2949 if (!vma || addr < vma->vm_start)
2952 /* skip special VMA and hugetlb VMA */
2953 if (vma_not_suitable_for_thp_split(vma)) {
2958 /* FOLL_DUMP to ignore special (like zero) pages */
2959 follflags = FOLL_GET | FOLL_DUMP;
2960 page = follow_page(vma, addr, follflags);
2967 if (!is_transparent_hugepage(page))
2971 if (!can_split_huge_page(compound_head(page), NULL))
2974 if (!trylock_page(page))
2977 if (!split_huge_page(page))
2985 mmap_read_unlock(mm);
2988 pr_debug("%lu of %lu THP split\n", split, total);
2994 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
2997 struct filename *file;
2998 struct file *candidate;
2999 struct address_space *mapping;
3003 unsigned long total = 0, split = 0;
3005 file = getname_kernel(file_path);
3009 candidate = file_open_name(file, O_RDONLY, 0);
3010 if (IS_ERR(candidate))
3013 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n",
3014 file_path, off_start, off_end);
3016 mapping = candidate->f_mapping;
3018 for (index = off_start; index < off_end; index += nr_pages) {
3019 struct page *fpage = pagecache_get_page(mapping, index,
3020 FGP_ENTRY | FGP_HEAD, 0);
3023 if (xa_is_value(fpage) || !fpage)
3026 if (!is_transparent_hugepage(fpage))
3030 nr_pages = thp_nr_pages(fpage);
3032 if (!trylock_page(fpage))
3035 if (!split_huge_page(fpage))
3044 filp_close(candidate, NULL);
3047 pr_debug("%lu of %lu file-backed THP split\n", split, total);
3053 #define MAX_INPUT_BUF_SZ 255
3055 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
3056 size_t count, loff_t *ppops)
3058 static DEFINE_MUTEX(split_debug_mutex);
3060 /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */
3061 char input_buf[MAX_INPUT_BUF_SZ];
3063 unsigned long vaddr_start, vaddr_end;
3065 ret = mutex_lock_interruptible(&split_debug_mutex);
3071 memset(input_buf, 0, MAX_INPUT_BUF_SZ);
3072 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ)))
3075 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0';
3077 if (input_buf[0] == '/') {
3079 char *buf = input_buf;
3080 char file_path[MAX_INPUT_BUF_SZ];
3081 pgoff_t off_start = 0, off_end = 0;
3082 size_t input_len = strlen(input_buf);
3084 tok = strsep(&buf, ",");
3086 strcpy(file_path, tok);
3092 ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end);
3097 ret = split_huge_pages_in_file(file_path, off_start, off_end);
3104 ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end);
3105 if (ret == 1 && pid == 1) {
3106 split_huge_pages_all();
3107 ret = strlen(input_buf);
3109 } else if (ret != 3) {
3114 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end);
3116 ret = strlen(input_buf);
3118 mutex_unlock(&split_debug_mutex);
3123 static const struct file_operations split_huge_pages_fops = {
3124 .owner = THIS_MODULE,
3125 .write = split_huge_pages_write,
3126 .llseek = no_llseek,
3129 static int __init split_huge_pages_debugfs(void)
3131 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
3132 &split_huge_pages_fops);
3135 late_initcall(split_huge_pages_debugfs);
3138 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
3139 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
3142 struct vm_area_struct *vma = pvmw->vma;
3143 struct mm_struct *mm = vma->vm_mm;
3144 unsigned long address = pvmw->address;
3149 if (!(pvmw->pmd && !pvmw->pte))
3152 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
3153 pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
3154 if (pmd_dirty(pmdval))
3155 set_page_dirty(page);
3156 if (pmd_write(pmdval))
3157 entry = make_writable_migration_entry(page_to_pfn(page));
3159 entry = make_readable_migration_entry(page_to_pfn(page));
3160 pmdswp = swp_entry_to_pmd(entry);
3161 if (pmd_soft_dirty(pmdval))
3162 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
3163 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
3164 page_remove_rmap(page, true);
3168 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
3170 struct vm_area_struct *vma = pvmw->vma;
3171 struct mm_struct *mm = vma->vm_mm;
3172 unsigned long address = pvmw->address;
3173 unsigned long mmun_start = address & HPAGE_PMD_MASK;
3177 if (!(pvmw->pmd && !pvmw->pte))
3180 entry = pmd_to_swp_entry(*pvmw->pmd);
3182 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
3183 if (pmd_swp_soft_dirty(*pvmw->pmd))
3184 pmde = pmd_mksoft_dirty(pmde);
3185 if (is_writable_migration_entry(entry))
3186 pmde = maybe_pmd_mkwrite(pmde, vma);
3187 if (pmd_swp_uffd_wp(*pvmw->pmd))
3188 pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde));
3190 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
3192 page_add_anon_rmap(new, vma, mmun_start, true);
3194 page_add_file_rmap(new, true);
3195 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
3196 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
3197 mlock_vma_page(new);
3198 update_mmu_cache_pmd(vma, address, pvmw->pmd);