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 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1384 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1390 /* NUMA hinting page fault entry point for trans huge pmds */
1391 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
1393 struct vm_area_struct *vma = vmf->vma;
1394 pmd_t oldpmd = vmf->orig_pmd;
1397 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1398 int page_nid = NUMA_NO_NODE;
1399 int target_nid, last_cpupid = -1;
1400 bool migrated = false;
1401 bool was_writable = pmd_savedwrite(oldpmd);
1404 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1405 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
1406 spin_unlock(vmf->ptl);
1410 pmd = pmd_modify(oldpmd, vma->vm_page_prot);
1411 page = vm_normal_page_pmd(vma, haddr, pmd);
1415 /* See similar comment in do_numa_page for explanation */
1417 flags |= TNF_NO_GROUP;
1419 page_nid = page_to_nid(page);
1420 last_cpupid = page_cpupid_last(page);
1421 target_nid = numa_migrate_prep(page, vma, haddr, page_nid,
1424 if (target_nid == NUMA_NO_NODE) {
1429 spin_unlock(vmf->ptl);
1431 migrated = migrate_misplaced_page(page, vma, target_nid);
1433 flags |= TNF_MIGRATED;
1434 page_nid = target_nid;
1436 flags |= TNF_MIGRATE_FAIL;
1437 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1438 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
1439 spin_unlock(vmf->ptl);
1446 if (page_nid != NUMA_NO_NODE)
1447 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1453 /* Restore the PMD */
1454 pmd = pmd_modify(oldpmd, vma->vm_page_prot);
1455 pmd = pmd_mkyoung(pmd);
1457 pmd = pmd_mkwrite(pmd);
1458 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1459 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1460 spin_unlock(vmf->ptl);
1465 * Return true if we do MADV_FREE successfully on entire pmd page.
1466 * Otherwise, return false.
1468 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1469 pmd_t *pmd, unsigned long addr, unsigned long next)
1474 struct mm_struct *mm = tlb->mm;
1477 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1479 ptl = pmd_trans_huge_lock(pmd, vma);
1484 if (is_huge_zero_pmd(orig_pmd))
1487 if (unlikely(!pmd_present(orig_pmd))) {
1488 VM_BUG_ON(thp_migration_supported() &&
1489 !is_pmd_migration_entry(orig_pmd));
1493 page = pmd_page(orig_pmd);
1495 * If other processes are mapping this page, we couldn't discard
1496 * the page unless they all do MADV_FREE so let's skip the page.
1498 if (total_mapcount(page) != 1)
1501 if (!trylock_page(page))
1505 * If user want to discard part-pages of THP, split it so MADV_FREE
1506 * will deactivate only them.
1508 if (next - addr != HPAGE_PMD_SIZE) {
1511 split_huge_page(page);
1517 if (PageDirty(page))
1518 ClearPageDirty(page);
1521 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1522 pmdp_invalidate(vma, addr, pmd);
1523 orig_pmd = pmd_mkold(orig_pmd);
1524 orig_pmd = pmd_mkclean(orig_pmd);
1526 set_pmd_at(mm, addr, pmd, orig_pmd);
1527 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1530 mark_page_lazyfree(page);
1538 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1542 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1543 pte_free(mm, pgtable);
1547 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1548 pmd_t *pmd, unsigned long addr)
1553 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1555 ptl = __pmd_trans_huge_lock(pmd, vma);
1559 * For architectures like ppc64 we look at deposited pgtable
1560 * when calling pmdp_huge_get_and_clear. So do the
1561 * pgtable_trans_huge_withdraw after finishing pmdp related
1564 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd,
1566 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1567 if (vma_is_special_huge(vma)) {
1568 if (arch_needs_pgtable_deposit())
1569 zap_deposited_table(tlb->mm, pmd);
1571 } else if (is_huge_zero_pmd(orig_pmd)) {
1572 zap_deposited_table(tlb->mm, pmd);
1575 struct page *page = NULL;
1576 int flush_needed = 1;
1578 if (pmd_present(orig_pmd)) {
1579 page = pmd_page(orig_pmd);
1580 page_remove_rmap(page, true);
1581 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1582 VM_BUG_ON_PAGE(!PageHead(page), page);
1583 } else if (thp_migration_supported()) {
1586 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1587 entry = pmd_to_swp_entry(orig_pmd);
1588 page = pfn_swap_entry_to_page(entry);
1591 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1593 if (PageAnon(page)) {
1594 zap_deposited_table(tlb->mm, pmd);
1595 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1597 if (arch_needs_pgtable_deposit())
1598 zap_deposited_table(tlb->mm, pmd);
1599 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1604 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1609 #ifndef pmd_move_must_withdraw
1610 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1611 spinlock_t *old_pmd_ptl,
1612 struct vm_area_struct *vma)
1615 * With split pmd lock we also need to move preallocated
1616 * PTE page table if new_pmd is on different PMD page table.
1618 * We also don't deposit and withdraw tables for file pages.
1620 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1624 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1626 #ifdef CONFIG_MEM_SOFT_DIRTY
1627 if (unlikely(is_pmd_migration_entry(pmd)))
1628 pmd = pmd_swp_mksoft_dirty(pmd);
1629 else if (pmd_present(pmd))
1630 pmd = pmd_mksoft_dirty(pmd);
1635 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1636 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
1638 spinlock_t *old_ptl, *new_ptl;
1640 struct mm_struct *mm = vma->vm_mm;
1641 bool force_flush = false;
1644 * The destination pmd shouldn't be established, free_pgtables()
1645 * should have release it.
1647 if (WARN_ON(!pmd_none(*new_pmd))) {
1648 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1653 * We don't have to worry about the ordering of src and dst
1654 * ptlocks because exclusive mmap_lock prevents deadlock.
1656 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1658 new_ptl = pmd_lockptr(mm, new_pmd);
1659 if (new_ptl != old_ptl)
1660 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1661 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1662 if (pmd_present(pmd))
1664 VM_BUG_ON(!pmd_none(*new_pmd));
1666 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1668 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1669 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1671 pmd = move_soft_dirty_pmd(pmd);
1672 set_pmd_at(mm, new_addr, new_pmd, pmd);
1674 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1675 if (new_ptl != old_ptl)
1676 spin_unlock(new_ptl);
1677 spin_unlock(old_ptl);
1685 * - 0 if PMD could not be locked
1686 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary
1687 * or if prot_numa but THP migration is not supported
1688 * - HPAGE_PMD_NR if protections changed and TLB flush necessary
1690 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1691 unsigned long addr, pgprot_t newprot, unsigned long cp_flags)
1693 struct mm_struct *mm = vma->vm_mm;
1696 bool preserve_write;
1698 bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
1699 bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
1700 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
1702 if (prot_numa && !thp_migration_supported())
1705 ptl = __pmd_trans_huge_lock(pmd, vma);
1709 preserve_write = prot_numa && pmd_write(*pmd);
1712 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1713 if (is_swap_pmd(*pmd)) {
1714 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1716 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1717 if (is_writable_migration_entry(entry)) {
1720 * A protection check is difficult so
1721 * just be safe and disable write
1723 entry = make_readable_migration_entry(
1725 newpmd = swp_entry_to_pmd(entry);
1726 if (pmd_swp_soft_dirty(*pmd))
1727 newpmd = pmd_swp_mksoft_dirty(newpmd);
1728 if (pmd_swp_uffd_wp(*pmd))
1729 newpmd = pmd_swp_mkuffd_wp(newpmd);
1730 set_pmd_at(mm, addr, pmd, newpmd);
1737 * Avoid trapping faults against the zero page. The read-only
1738 * data is likely to be read-cached on the local CPU and
1739 * local/remote hits to the zero page are not interesting.
1741 if (prot_numa && is_huge_zero_pmd(*pmd))
1744 if (prot_numa && pmd_protnone(*pmd))
1748 * In case prot_numa, we are under mmap_read_lock(mm). It's critical
1749 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1750 * which is also under mmap_read_lock(mm):
1753 * change_huge_pmd(prot_numa=1)
1754 * pmdp_huge_get_and_clear_notify()
1755 * madvise_dontneed()
1757 * pmd_trans_huge(*pmd) == 0 (without ptl)
1760 * // pmd is re-established
1762 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1763 * which may break userspace.
1765 * pmdp_invalidate() is required to make sure we don't miss
1766 * dirty/young flags set by hardware.
1768 entry = pmdp_invalidate(vma, addr, pmd);
1770 entry = pmd_modify(entry, newprot);
1772 entry = pmd_mk_savedwrite(entry);
1774 entry = pmd_wrprotect(entry);
1775 entry = pmd_mkuffd_wp(entry);
1776 } else if (uffd_wp_resolve) {
1778 * Leave the write bit to be handled by PF interrupt
1779 * handler, then things like COW could be properly
1782 entry = pmd_clear_uffd_wp(entry);
1785 set_pmd_at(mm, addr, pmd, entry);
1786 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1793 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1795 * Note that if it returns page table lock pointer, this routine returns without
1796 * unlocking page table lock. So callers must unlock it.
1798 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1801 ptl = pmd_lock(vma->vm_mm, pmd);
1802 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1810 * Returns true if a given pud maps a thp, false otherwise.
1812 * Note that if it returns true, this routine returns without unlocking page
1813 * table lock. So callers must unlock it.
1815 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1819 ptl = pud_lock(vma->vm_mm, pud);
1820 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1826 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1827 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1828 pud_t *pud, unsigned long addr)
1832 ptl = __pud_trans_huge_lock(pud, vma);
1836 * For architectures like ppc64 we look at deposited pgtable
1837 * when calling pudp_huge_get_and_clear. So do the
1838 * pgtable_trans_huge_withdraw after finishing pudp related
1841 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
1842 tlb_remove_pud_tlb_entry(tlb, pud, addr);
1843 if (vma_is_special_huge(vma)) {
1845 /* No zero page support yet */
1847 /* No support for anonymous PUD pages yet */
1853 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
1854 unsigned long haddr)
1856 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
1857 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1858 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
1859 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
1861 count_vm_event(THP_SPLIT_PUD);
1863 pudp_huge_clear_flush_notify(vma, haddr, pud);
1866 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
1867 unsigned long address)
1870 struct mmu_notifier_range range;
1872 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1873 address & HPAGE_PUD_MASK,
1874 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
1875 mmu_notifier_invalidate_range_start(&range);
1876 ptl = pud_lock(vma->vm_mm, pud);
1877 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
1879 __split_huge_pud_locked(vma, pud, range.start);
1884 * No need to double call mmu_notifier->invalidate_range() callback as
1885 * the above pudp_huge_clear_flush_notify() did already call it.
1887 mmu_notifier_invalidate_range_only_end(&range);
1889 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1891 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
1892 unsigned long haddr, pmd_t *pmd)
1894 struct mm_struct *mm = vma->vm_mm;
1900 * Leave pmd empty until pte is filled note that it is fine to delay
1901 * notification until mmu_notifier_invalidate_range_end() as we are
1902 * replacing a zero pmd write protected page with a zero pte write
1905 * See Documentation/vm/mmu_notifier.rst
1907 pmdp_huge_clear_flush(vma, haddr, pmd);
1909 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1910 pmd_populate(mm, &_pmd, pgtable);
1912 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1914 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
1915 entry = pte_mkspecial(entry);
1916 pte = pte_offset_map(&_pmd, haddr);
1917 VM_BUG_ON(!pte_none(*pte));
1918 set_pte_at(mm, haddr, pte, entry);
1921 smp_wmb(); /* make pte visible before pmd */
1922 pmd_populate(mm, pmd, pgtable);
1925 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
1926 unsigned long haddr, bool freeze)
1928 struct mm_struct *mm = vma->vm_mm;
1931 pmd_t old_pmd, _pmd;
1932 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
1936 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
1937 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1938 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
1939 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
1940 && !pmd_devmap(*pmd));
1942 count_vm_event(THP_SPLIT_PMD);
1944 if (!vma_is_anonymous(vma)) {
1945 old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
1947 * We are going to unmap this huge page. So
1948 * just go ahead and zap it
1950 if (arch_needs_pgtable_deposit())
1951 zap_deposited_table(mm, pmd);
1952 if (vma_is_special_huge(vma))
1954 if (unlikely(is_pmd_migration_entry(old_pmd))) {
1957 entry = pmd_to_swp_entry(old_pmd);
1958 page = pfn_swap_entry_to_page(entry);
1960 page = pmd_page(old_pmd);
1961 if (!PageDirty(page) && pmd_dirty(old_pmd))
1962 set_page_dirty(page);
1963 if (!PageReferenced(page) && pmd_young(old_pmd))
1964 SetPageReferenced(page);
1965 page_remove_rmap(page, true);
1968 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
1972 if (is_huge_zero_pmd(*pmd)) {
1974 * FIXME: Do we want to invalidate secondary mmu by calling
1975 * mmu_notifier_invalidate_range() see comments below inside
1976 * __split_huge_pmd() ?
1978 * We are going from a zero huge page write protected to zero
1979 * small page also write protected so it does not seems useful
1980 * to invalidate secondary mmu at this time.
1982 return __split_huge_zero_page_pmd(vma, haddr, pmd);
1986 * Up to this point the pmd is present and huge and userland has the
1987 * whole access to the hugepage during the split (which happens in
1988 * place). If we overwrite the pmd with the not-huge version pointing
1989 * to the pte here (which of course we could if all CPUs were bug
1990 * free), userland could trigger a small page size TLB miss on the
1991 * small sized TLB while the hugepage TLB entry is still established in
1992 * the huge TLB. Some CPU doesn't like that.
1993 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum
1994 * 383 on page 105. Intel should be safe but is also warns that it's
1995 * only safe if the permission and cache attributes of the two entries
1996 * loaded in the two TLB is identical (which should be the case here).
1997 * But it is generally safer to never allow small and huge TLB entries
1998 * for the same virtual address to be loaded simultaneously. So instead
1999 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2000 * current pmd notpresent (atomically because here the pmd_trans_huge
2001 * must remain set at all times on the pmd until the split is complete
2002 * for this pmd), then we flush the SMP TLB and finally we write the
2003 * non-huge version of the pmd entry with pmd_populate.
2005 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2007 pmd_migration = is_pmd_migration_entry(old_pmd);
2008 if (unlikely(pmd_migration)) {
2011 entry = pmd_to_swp_entry(old_pmd);
2012 page = pfn_swap_entry_to_page(entry);
2013 write = is_writable_migration_entry(entry);
2015 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2016 uffd_wp = pmd_swp_uffd_wp(old_pmd);
2018 page = pmd_page(old_pmd);
2019 if (pmd_dirty(old_pmd))
2021 write = pmd_write(old_pmd);
2022 young = pmd_young(old_pmd);
2023 soft_dirty = pmd_soft_dirty(old_pmd);
2024 uffd_wp = pmd_uffd_wp(old_pmd);
2026 VM_BUG_ON_PAGE(!page_count(page), page);
2027 page_ref_add(page, HPAGE_PMD_NR - 1);
2030 * Withdraw the table only after we mark the pmd entry invalid.
2031 * This's critical for some architectures (Power).
2033 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2034 pmd_populate(mm, &_pmd, pgtable);
2036 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2039 * Note that NUMA hinting access restrictions are not
2040 * transferred to avoid any possibility of altering
2041 * permissions across VMAs.
2043 if (freeze || pmd_migration) {
2044 swp_entry_t swp_entry;
2046 swp_entry = make_writable_migration_entry(
2047 page_to_pfn(page + i));
2049 swp_entry = make_readable_migration_entry(
2050 page_to_pfn(page + i));
2051 entry = swp_entry_to_pte(swp_entry);
2053 entry = pte_swp_mksoft_dirty(entry);
2055 entry = pte_swp_mkuffd_wp(entry);
2057 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2058 entry = maybe_mkwrite(entry, vma);
2060 entry = pte_wrprotect(entry);
2062 entry = pte_mkold(entry);
2064 entry = pte_mksoft_dirty(entry);
2066 entry = pte_mkuffd_wp(entry);
2068 pte = pte_offset_map(&_pmd, addr);
2069 BUG_ON(!pte_none(*pte));
2070 set_pte_at(mm, addr, pte, entry);
2072 atomic_inc(&page[i]._mapcount);
2076 if (!pmd_migration) {
2078 * Set PG_double_map before dropping compound_mapcount to avoid
2079 * false-negative page_mapped().
2081 if (compound_mapcount(page) > 1 &&
2082 !TestSetPageDoubleMap(page)) {
2083 for (i = 0; i < HPAGE_PMD_NR; i++)
2084 atomic_inc(&page[i]._mapcount);
2087 lock_page_memcg(page);
2088 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2089 /* Last compound_mapcount is gone. */
2090 __mod_lruvec_page_state(page, NR_ANON_THPS,
2092 if (TestClearPageDoubleMap(page)) {
2093 /* No need in mapcount reference anymore */
2094 for (i = 0; i < HPAGE_PMD_NR; i++)
2095 atomic_dec(&page[i]._mapcount);
2098 unlock_page_memcg(page);
2101 smp_wmb(); /* make pte visible before pmd */
2102 pmd_populate(mm, pmd, pgtable);
2105 for (i = 0; i < HPAGE_PMD_NR; i++) {
2106 page_remove_rmap(page + i, false);
2112 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2113 unsigned long address, bool freeze, struct page *page)
2116 struct mmu_notifier_range range;
2117 bool do_unlock_page = false;
2120 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2121 address & HPAGE_PMD_MASK,
2122 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2123 mmu_notifier_invalidate_range_start(&range);
2124 ptl = pmd_lock(vma->vm_mm, pmd);
2127 * If caller asks to setup a migration entries, we need a page to check
2128 * pmd against. Otherwise we can end up replacing wrong page.
2130 VM_BUG_ON(freeze && !page);
2132 VM_WARN_ON_ONCE(!PageLocked(page));
2133 if (page != pmd_page(*pmd))
2138 if (pmd_trans_huge(*pmd)) {
2140 page = pmd_page(*pmd);
2142 * An anonymous page must be locked, to ensure that a
2143 * concurrent reuse_swap_page() sees stable mapcount;
2144 * but reuse_swap_page() is not used on shmem or file,
2145 * and page lock must not be taken when zap_pmd_range()
2146 * calls __split_huge_pmd() while i_mmap_lock is held.
2148 if (PageAnon(page)) {
2149 if (unlikely(!trylock_page(page))) {
2155 if (unlikely(!pmd_same(*pmd, _pmd))) {
2163 do_unlock_page = true;
2166 if (PageMlocked(page))
2167 clear_page_mlock(page);
2168 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2170 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2176 * No need to double call mmu_notifier->invalidate_range() callback.
2177 * They are 3 cases to consider inside __split_huge_pmd_locked():
2178 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2179 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2180 * fault will trigger a flush_notify before pointing to a new page
2181 * (it is fine if the secondary mmu keeps pointing to the old zero
2182 * page in the meantime)
2183 * 3) Split a huge pmd into pte pointing to the same page. No need
2184 * to invalidate secondary tlb entry they are all still valid.
2185 * any further changes to individual pte will notify. So no need
2186 * to call mmu_notifier->invalidate_range()
2188 mmu_notifier_invalidate_range_only_end(&range);
2191 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2192 bool freeze, struct page *page)
2199 pgd = pgd_offset(vma->vm_mm, address);
2200 if (!pgd_present(*pgd))
2203 p4d = p4d_offset(pgd, address);
2204 if (!p4d_present(*p4d))
2207 pud = pud_offset(p4d, address);
2208 if (!pud_present(*pud))
2211 pmd = pmd_offset(pud, address);
2213 __split_huge_pmd(vma, pmd, address, freeze, page);
2216 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address)
2219 * If the new address isn't hpage aligned and it could previously
2220 * contain an hugepage: check if we need to split an huge pmd.
2222 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) &&
2223 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE),
2224 ALIGN(address, HPAGE_PMD_SIZE)))
2225 split_huge_pmd_address(vma, address, false, NULL);
2228 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2229 unsigned long start,
2233 /* Check if we need to split start first. */
2234 split_huge_pmd_if_needed(vma, start);
2236 /* Check if we need to split end next. */
2237 split_huge_pmd_if_needed(vma, end);
2240 * If we're also updating the vma->vm_next->vm_start,
2241 * check if we need to split it.
2243 if (adjust_next > 0) {
2244 struct vm_area_struct *next = vma->vm_next;
2245 unsigned long nstart = next->vm_start;
2246 nstart += adjust_next;
2247 split_huge_pmd_if_needed(next, nstart);
2251 static void unmap_page(struct page *page)
2253 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD |
2256 VM_BUG_ON_PAGE(!PageHead(page), page);
2259 * Anon pages need migration entries to preserve them, but file
2260 * pages can simply be left unmapped, then faulted back on demand.
2261 * If that is ever changed (perhaps for mlock), update remap_page().
2264 try_to_migrate(page, ttu_flags);
2266 try_to_unmap(page, ttu_flags | TTU_IGNORE_MLOCK);
2268 VM_WARN_ON_ONCE_PAGE(page_mapped(page), page);
2271 static void remap_page(struct page *page, unsigned int nr)
2275 /* If unmap_page() uses try_to_migrate() on file, remove this check */
2276 if (!PageAnon(page))
2278 if (PageTransHuge(page)) {
2279 remove_migration_ptes(page, page, true);
2281 for (i = 0; i < nr; i++)
2282 remove_migration_ptes(page + i, page + i, true);
2286 static void lru_add_page_tail(struct page *head, struct page *tail,
2287 struct lruvec *lruvec, struct list_head *list)
2289 VM_BUG_ON_PAGE(!PageHead(head), head);
2290 VM_BUG_ON_PAGE(PageCompound(tail), head);
2291 VM_BUG_ON_PAGE(PageLRU(tail), head);
2292 lockdep_assert_held(&lruvec->lru_lock);
2295 /* page reclaim is reclaiming a huge page */
2296 VM_WARN_ON(PageLRU(head));
2298 list_add_tail(&tail->lru, list);
2300 /* head is still on lru (and we have it frozen) */
2301 VM_WARN_ON(!PageLRU(head));
2303 list_add_tail(&tail->lru, &head->lru);
2307 static void __split_huge_page_tail(struct page *head, int tail,
2308 struct lruvec *lruvec, struct list_head *list)
2310 struct page *page_tail = head + tail;
2312 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2315 * Clone page flags before unfreezing refcount.
2317 * After successful get_page_unless_zero() might follow flags change,
2318 * for example lock_page() which set PG_waiters.
2320 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2321 page_tail->flags |= (head->flags &
2322 ((1L << PG_referenced) |
2323 (1L << PG_swapbacked) |
2324 (1L << PG_swapcache) |
2325 (1L << PG_mlocked) |
2326 (1L << PG_uptodate) |
2328 (1L << PG_workingset) |
2330 (1L << PG_unevictable) |
2336 /* ->mapping in first tail page is compound_mapcount */
2337 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2339 page_tail->mapping = head->mapping;
2340 page_tail->index = head->index + tail;
2342 /* Page flags must be visible before we make the page non-compound. */
2346 * Clear PageTail before unfreezing page refcount.
2348 * After successful get_page_unless_zero() might follow put_page()
2349 * which needs correct compound_head().
2351 clear_compound_head(page_tail);
2353 /* Finally unfreeze refcount. Additional reference from page cache. */
2354 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2355 PageSwapCache(head)));
2357 if (page_is_young(head))
2358 set_page_young(page_tail);
2359 if (page_is_idle(head))
2360 set_page_idle(page_tail);
2362 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2365 * always add to the tail because some iterators expect new
2366 * pages to show after the currently processed elements - e.g.
2369 lru_add_page_tail(head, page_tail, lruvec, list);
2372 static void __split_huge_page(struct page *page, struct list_head *list,
2375 struct folio *folio = page_folio(page);
2376 struct page *head = &folio->page;
2377 struct lruvec *lruvec;
2378 struct address_space *swap_cache = NULL;
2379 unsigned long offset = 0;
2380 unsigned int nr = thp_nr_pages(head);
2383 /* complete memcg works before add pages to LRU */
2384 split_page_memcg(head, nr);
2386 if (PageAnon(head) && PageSwapCache(head)) {
2387 swp_entry_t entry = { .val = page_private(head) };
2389 offset = swp_offset(entry);
2390 swap_cache = swap_address_space(entry);
2391 xa_lock(&swap_cache->i_pages);
2394 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
2395 lruvec = folio_lruvec_lock(folio);
2397 ClearPageHasHWPoisoned(head);
2399 for (i = nr - 1; i >= 1; i--) {
2400 __split_huge_page_tail(head, i, lruvec, list);
2401 /* Some pages can be beyond EOF: drop them from page cache */
2402 if (head[i].index >= end) {
2403 ClearPageDirty(head + i);
2404 __delete_from_page_cache(head + i, NULL);
2405 if (shmem_mapping(head->mapping))
2406 shmem_uncharge(head->mapping->host, 1);
2408 } else if (!PageAnon(page)) {
2409 __xa_store(&head->mapping->i_pages, head[i].index,
2411 } else if (swap_cache) {
2412 __xa_store(&swap_cache->i_pages, offset + i,
2417 ClearPageCompound(head);
2418 unlock_page_lruvec(lruvec);
2419 /* Caller disabled irqs, so they are still disabled here */
2421 split_page_owner(head, nr);
2423 /* See comment in __split_huge_page_tail() */
2424 if (PageAnon(head)) {
2425 /* Additional pin to swap cache */
2426 if (PageSwapCache(head)) {
2427 page_ref_add(head, 2);
2428 xa_unlock(&swap_cache->i_pages);
2433 /* Additional pin to page cache */
2434 page_ref_add(head, 2);
2435 xa_unlock(&head->mapping->i_pages);
2439 remap_page(head, nr);
2441 if (PageSwapCache(head)) {
2442 swp_entry_t entry = { .val = page_private(head) };
2444 split_swap_cluster(entry);
2447 for (i = 0; i < nr; i++) {
2448 struct page *subpage = head + i;
2449 if (subpage == page)
2451 unlock_page(subpage);
2454 * Subpages may be freed if there wasn't any mapping
2455 * like if add_to_swap() is running on a lru page that
2456 * had its mapping zapped. And freeing these pages
2457 * requires taking the lru_lock so we do the put_page
2458 * of the tail pages after the split is complete.
2464 int total_mapcount(struct page *page)
2466 int i, compound, nr, ret;
2468 VM_BUG_ON_PAGE(PageTail(page), page);
2470 if (likely(!PageCompound(page)))
2471 return atomic_read(&page->_mapcount) + 1;
2473 compound = compound_mapcount(page);
2474 nr = compound_nr(page);
2478 for (i = 0; i < nr; i++)
2479 ret += atomic_read(&page[i]._mapcount) + 1;
2480 /* File pages has compound_mapcount included in _mapcount */
2481 if (!PageAnon(page))
2482 return ret - compound * nr;
2483 if (PageDoubleMap(page))
2489 * This calculates accurately how many mappings a transparent hugepage
2490 * has (unlike page_mapcount() which isn't fully accurate). This full
2491 * accuracy is primarily needed to know if copy-on-write faults can
2492 * reuse the page and change the mapping to read-write instead of
2493 * copying them. At the same time this returns the total_mapcount too.
2495 * The function returns the highest mapcount any one of the subpages
2496 * has. If the return value is one, even if different processes are
2497 * mapping different subpages of the transparent hugepage, they can
2498 * all reuse it, because each process is reusing a different subpage.
2500 * The total_mapcount is instead counting all virtual mappings of the
2501 * subpages. If the total_mapcount is equal to "one", it tells the
2502 * caller all mappings belong to the same "mm" and in turn the
2503 * anon_vma of the transparent hugepage can become the vma->anon_vma
2504 * local one as no other process may be mapping any of the subpages.
2506 * It would be more accurate to replace page_mapcount() with
2507 * page_trans_huge_mapcount(), however we only use
2508 * page_trans_huge_mapcount() in the copy-on-write faults where we
2509 * need full accuracy to avoid breaking page pinning, because
2510 * page_trans_huge_mapcount() is slower than page_mapcount().
2512 int page_trans_huge_mapcount(struct page *page)
2516 /* hugetlbfs shouldn't call it */
2517 VM_BUG_ON_PAGE(PageHuge(page), page);
2519 if (likely(!PageTransCompound(page)))
2520 return atomic_read(&page->_mapcount) + 1;
2522 page = compound_head(page);
2525 for (i = 0; i < thp_nr_pages(page); i++) {
2526 int mapcount = atomic_read(&page[i]._mapcount) + 1;
2527 ret = max(ret, mapcount);
2530 if (PageDoubleMap(page))
2533 return ret + compound_mapcount(page);
2536 /* Racy check whether the huge page can be split */
2537 bool can_split_huge_page(struct page *page, int *pextra_pins)
2541 /* Additional pins from page cache */
2543 extra_pins = PageSwapCache(page) ? thp_nr_pages(page) : 0;
2545 extra_pins = thp_nr_pages(page);
2547 *pextra_pins = extra_pins;
2548 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2552 * This function splits huge page into normal pages. @page can point to any
2553 * subpage of huge page to split. Split doesn't change the position of @page.
2555 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2556 * The huge page must be locked.
2558 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2560 * Both head page and tail pages will inherit mapping, flags, and so on from
2563 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2564 * they are not mapped.
2566 * Returns 0 if the hugepage is split successfully.
2567 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2570 int split_huge_page_to_list(struct page *page, struct list_head *list)
2572 struct page *head = compound_head(page);
2573 struct deferred_split *ds_queue = get_deferred_split_queue(head);
2574 XA_STATE(xas, &head->mapping->i_pages, head->index);
2575 struct anon_vma *anon_vma = NULL;
2576 struct address_space *mapping = NULL;
2577 int extra_pins, ret;
2580 VM_BUG_ON_PAGE(is_huge_zero_page(head), head);
2581 VM_BUG_ON_PAGE(!PageLocked(head), head);
2582 VM_BUG_ON_PAGE(!PageCompound(head), head);
2584 if (PageWriteback(head))
2587 if (PageAnon(head)) {
2589 * The caller does not necessarily hold an mmap_lock that would
2590 * prevent the anon_vma disappearing so we first we take a
2591 * reference to it and then lock the anon_vma for write. This
2592 * is similar to page_lock_anon_vma_read except the write lock
2593 * is taken to serialise against parallel split or collapse
2596 anon_vma = page_get_anon_vma(head);
2603 anon_vma_lock_write(anon_vma);
2605 mapping = head->mapping;
2613 xas_split_alloc(&xas, head, compound_order(head),
2614 mapping_gfp_mask(mapping) & GFP_RECLAIM_MASK);
2615 if (xas_error(&xas)) {
2616 ret = xas_error(&xas);
2621 i_mmap_lock_read(mapping);
2624 *__split_huge_page() may need to trim off pages beyond EOF:
2625 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2626 * which cannot be nested inside the page tree lock. So note
2627 * end now: i_size itself may be changed at any moment, but
2628 * head page lock is good enough to serialize the trimming.
2630 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2631 if (shmem_mapping(mapping))
2632 end = shmem_fallocend(mapping->host, end);
2636 * Racy check if we can split the page, before unmap_page() will
2639 if (!can_split_huge_page(head, &extra_pins)) {
2646 /* block interrupt reentry in xa_lock and spinlock */
2647 local_irq_disable();
2650 * Check if the head page is present in page cache.
2651 * We assume all tail are present too, if head is there.
2655 if (xas_load(&xas) != head)
2659 /* Prevent deferred_split_scan() touching ->_refcount */
2660 spin_lock(&ds_queue->split_queue_lock);
2661 if (page_ref_freeze(head, 1 + extra_pins)) {
2662 if (!list_empty(page_deferred_list(head))) {
2663 ds_queue->split_queue_len--;
2664 list_del(page_deferred_list(head));
2666 spin_unlock(&ds_queue->split_queue_lock);
2668 int nr = thp_nr_pages(head);
2670 xas_split(&xas, head, thp_order(head));
2671 if (PageSwapBacked(head)) {
2672 __mod_lruvec_page_state(head, NR_SHMEM_THPS,
2675 __mod_lruvec_page_state(head, NR_FILE_THPS,
2677 filemap_nr_thps_dec(mapping);
2681 __split_huge_page(page, list, end);
2684 spin_unlock(&ds_queue->split_queue_lock);
2689 remap_page(head, thp_nr_pages(head));
2695 anon_vma_unlock_write(anon_vma);
2696 put_anon_vma(anon_vma);
2699 i_mmap_unlock_read(mapping);
2701 /* Free any memory we didn't use */
2703 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2707 void free_transhuge_page(struct page *page)
2709 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2710 unsigned long flags;
2712 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2713 if (!list_empty(page_deferred_list(page))) {
2714 ds_queue->split_queue_len--;
2715 list_del(page_deferred_list(page));
2717 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2718 free_compound_page(page);
2721 void deferred_split_huge_page(struct page *page)
2723 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2725 struct mem_cgroup *memcg = page_memcg(compound_head(page));
2727 unsigned long flags;
2729 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2732 * The try_to_unmap() in page reclaim path might reach here too,
2733 * this may cause a race condition to corrupt deferred split queue.
2734 * And, if page reclaim is already handling the same page, it is
2735 * unnecessary to handle it again in shrinker.
2737 * Check PageSwapCache to determine if the page is being
2738 * handled by page reclaim since THP swap would add the page into
2739 * swap cache before calling try_to_unmap().
2741 if (PageSwapCache(page))
2744 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2745 if (list_empty(page_deferred_list(page))) {
2746 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2747 list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
2748 ds_queue->split_queue_len++;
2751 set_shrinker_bit(memcg, page_to_nid(page),
2752 deferred_split_shrinker.id);
2755 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2758 static unsigned long deferred_split_count(struct shrinker *shrink,
2759 struct shrink_control *sc)
2761 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2762 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2766 ds_queue = &sc->memcg->deferred_split_queue;
2768 return READ_ONCE(ds_queue->split_queue_len);
2771 static unsigned long deferred_split_scan(struct shrinker *shrink,
2772 struct shrink_control *sc)
2774 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2775 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2776 unsigned long flags;
2777 LIST_HEAD(list), *pos, *next;
2783 ds_queue = &sc->memcg->deferred_split_queue;
2786 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2787 /* Take pin on all head pages to avoid freeing them under us */
2788 list_for_each_safe(pos, next, &ds_queue->split_queue) {
2789 page = list_entry((void *)pos, struct page, deferred_list);
2790 page = compound_head(page);
2791 if (get_page_unless_zero(page)) {
2792 list_move(page_deferred_list(page), &list);
2794 /* We lost race with put_compound_page() */
2795 list_del_init(page_deferred_list(page));
2796 ds_queue->split_queue_len--;
2798 if (!--sc->nr_to_scan)
2801 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2803 list_for_each_safe(pos, next, &list) {
2804 page = list_entry((void *)pos, struct page, deferred_list);
2805 if (!trylock_page(page))
2807 /* split_huge_page() removes page from list on success */
2808 if (!split_huge_page(page))
2815 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2816 list_splice_tail(&list, &ds_queue->split_queue);
2817 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2820 * Stop shrinker if we didn't split any page, but the queue is empty.
2821 * This can happen if pages were freed under us.
2823 if (!split && list_empty(&ds_queue->split_queue))
2828 static struct shrinker deferred_split_shrinker = {
2829 .count_objects = deferred_split_count,
2830 .scan_objects = deferred_split_scan,
2831 .seeks = DEFAULT_SEEKS,
2832 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
2836 #ifdef CONFIG_DEBUG_FS
2837 static void split_huge_pages_all(void)
2841 unsigned long pfn, max_zone_pfn;
2842 unsigned long total = 0, split = 0;
2844 pr_debug("Split all THPs\n");
2845 for_each_populated_zone(zone) {
2846 max_zone_pfn = zone_end_pfn(zone);
2847 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2848 if (!pfn_valid(pfn))
2851 page = pfn_to_page(pfn);
2852 if (!get_page_unless_zero(page))
2855 if (zone != page_zone(page))
2858 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2863 if (!split_huge_page(page))
2872 pr_debug("%lu of %lu THP split\n", split, total);
2875 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma)
2877 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) ||
2878 is_vm_hugetlb_page(vma);
2881 static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
2882 unsigned long vaddr_end)
2885 struct task_struct *task;
2886 struct mm_struct *mm;
2887 unsigned long total = 0, split = 0;
2890 vaddr_start &= PAGE_MASK;
2891 vaddr_end &= PAGE_MASK;
2893 /* Find the task_struct from pid */
2895 task = find_task_by_vpid(pid);
2901 get_task_struct(task);
2904 /* Find the mm_struct */
2905 mm = get_task_mm(task);
2906 put_task_struct(task);
2913 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n",
2914 pid, vaddr_start, vaddr_end);
2918 * always increase addr by PAGE_SIZE, since we could have a PTE page
2919 * table filled with PTE-mapped THPs, each of which is distinct.
2921 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) {
2922 struct vm_area_struct *vma = find_vma(mm, addr);
2923 unsigned int follflags;
2926 if (!vma || addr < vma->vm_start)
2929 /* skip special VMA and hugetlb VMA */
2930 if (vma_not_suitable_for_thp_split(vma)) {
2935 /* FOLL_DUMP to ignore special (like zero) pages */
2936 follflags = FOLL_GET | FOLL_DUMP;
2937 page = follow_page(vma, addr, follflags);
2944 if (!is_transparent_hugepage(page))
2948 if (!can_split_huge_page(compound_head(page), NULL))
2951 if (!trylock_page(page))
2954 if (!split_huge_page(page))
2962 mmap_read_unlock(mm);
2965 pr_debug("%lu of %lu THP split\n", split, total);
2971 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
2974 struct filename *file;
2975 struct file *candidate;
2976 struct address_space *mapping;
2980 unsigned long total = 0, split = 0;
2982 file = getname_kernel(file_path);
2986 candidate = file_open_name(file, O_RDONLY, 0);
2987 if (IS_ERR(candidate))
2990 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n",
2991 file_path, off_start, off_end);
2993 mapping = candidate->f_mapping;
2995 for (index = off_start; index < off_end; index += nr_pages) {
2996 struct page *fpage = pagecache_get_page(mapping, index,
2997 FGP_ENTRY | FGP_HEAD, 0);
3000 if (xa_is_value(fpage) || !fpage)
3003 if (!is_transparent_hugepage(fpage))
3007 nr_pages = thp_nr_pages(fpage);
3009 if (!trylock_page(fpage))
3012 if (!split_huge_page(fpage))
3021 filp_close(candidate, NULL);
3024 pr_debug("%lu of %lu file-backed THP split\n", split, total);
3030 #define MAX_INPUT_BUF_SZ 255
3032 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
3033 size_t count, loff_t *ppops)
3035 static DEFINE_MUTEX(split_debug_mutex);
3037 /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */
3038 char input_buf[MAX_INPUT_BUF_SZ];
3040 unsigned long vaddr_start, vaddr_end;
3042 ret = mutex_lock_interruptible(&split_debug_mutex);
3048 memset(input_buf, 0, MAX_INPUT_BUF_SZ);
3049 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ)))
3052 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0';
3054 if (input_buf[0] == '/') {
3056 char *buf = input_buf;
3057 char file_path[MAX_INPUT_BUF_SZ];
3058 pgoff_t off_start = 0, off_end = 0;
3059 size_t input_len = strlen(input_buf);
3061 tok = strsep(&buf, ",");
3063 strcpy(file_path, tok);
3069 ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end);
3074 ret = split_huge_pages_in_file(file_path, off_start, off_end);
3081 ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end);
3082 if (ret == 1 && pid == 1) {
3083 split_huge_pages_all();
3084 ret = strlen(input_buf);
3086 } else if (ret != 3) {
3091 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end);
3093 ret = strlen(input_buf);
3095 mutex_unlock(&split_debug_mutex);
3100 static const struct file_operations split_huge_pages_fops = {
3101 .owner = THIS_MODULE,
3102 .write = split_huge_pages_write,
3103 .llseek = no_llseek,
3106 static int __init split_huge_pages_debugfs(void)
3108 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
3109 &split_huge_pages_fops);
3112 late_initcall(split_huge_pages_debugfs);
3115 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
3116 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
3119 struct vm_area_struct *vma = pvmw->vma;
3120 struct mm_struct *mm = vma->vm_mm;
3121 unsigned long address = pvmw->address;
3126 if (!(pvmw->pmd && !pvmw->pte))
3129 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
3130 pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
3131 if (pmd_dirty(pmdval))
3132 set_page_dirty(page);
3133 if (pmd_write(pmdval))
3134 entry = make_writable_migration_entry(page_to_pfn(page));
3136 entry = make_readable_migration_entry(page_to_pfn(page));
3137 pmdswp = swp_entry_to_pmd(entry);
3138 if (pmd_soft_dirty(pmdval))
3139 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
3140 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
3141 page_remove_rmap(page, true);
3145 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
3147 struct vm_area_struct *vma = pvmw->vma;
3148 struct mm_struct *mm = vma->vm_mm;
3149 unsigned long address = pvmw->address;
3150 unsigned long mmun_start = address & HPAGE_PMD_MASK;
3154 if (!(pvmw->pmd && !pvmw->pte))
3157 entry = pmd_to_swp_entry(*pvmw->pmd);
3159 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
3160 if (pmd_swp_soft_dirty(*pvmw->pmd))
3161 pmde = pmd_mksoft_dirty(pmde);
3162 if (is_writable_migration_entry(entry))
3163 pmde = maybe_pmd_mkwrite(pmde, vma);
3164 if (pmd_swp_uffd_wp(*pvmw->pmd))
3165 pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde));
3167 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
3169 page_add_anon_rmap(new, vma, mmun_start, true);
3171 page_add_file_rmap(new, true);
3172 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
3173 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
3174 mlock_vma_page(new);
3175 update_mmu_cache_pmd(vma, address, pvmw->pmd);