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/backing-dev.h>
22 #include <linux/dax.h>
23 #include <linux/khugepaged.h>
24 #include <linux/freezer.h>
25 #include <linux/pfn_t.h>
26 #include <linux/mman.h>
27 #include <linux/memremap.h>
28 #include <linux/pagemap.h>
29 #include <linux/debugfs.h>
30 #include <linux/migrate.h>
31 #include <linux/hashtable.h>
32 #include <linux/userfaultfd_k.h>
33 #include <linux/page_idle.h>
34 #include <linux/shmem_fs.h>
35 #include <linux/oom.h>
36 #include <linux/numa.h>
37 #include <linux/page_owner.h>
38 #include <linux/sched/sysctl.h>
39 #include <linux/memory-tiers.h>
42 #include <asm/pgalloc.h>
46 #define CREATE_TRACE_POINTS
47 #include <trace/events/thp.h>
50 * By default, transparent hugepage support is disabled in order to avoid
51 * risking an increased memory footprint for applications that are not
52 * guaranteed to benefit from it. When transparent hugepage support is
53 * enabled, it is for all mappings, and khugepaged scans all mappings.
54 * Defrag is invoked by khugepaged hugepage allocations and by page faults
55 * for all hugepage allocations.
57 unsigned long transparent_hugepage_flags __read_mostly =
58 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
59 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
61 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
62 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
64 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
65 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
66 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
68 static struct shrinker deferred_split_shrinker;
70 static atomic_t huge_zero_refcount;
71 struct page *huge_zero_page __read_mostly;
72 unsigned long huge_zero_pfn __read_mostly = ~0UL;
74 bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags,
75 bool smaps, bool in_pf, bool enforce_sysfs)
77 if (!vma->vm_mm) /* vdso */
81 * Explicitly disabled through madvise or prctl, or some
82 * architectures may disable THP for some mappings, for
85 if ((vm_flags & VM_NOHUGEPAGE) ||
86 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
89 * If the hardware/firmware marked hugepage support disabled.
91 if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_NEVER_DAX))
94 /* khugepaged doesn't collapse DAX vma, but page fault is fine. */
99 * Special VMA and hugetlb VMA.
100 * Must be checked after dax since some dax mappings may have
103 if (vm_flags & VM_NO_KHUGEPAGED)
107 * Check alignment for file vma and size for both file and anon vma.
109 * Skip the check for page fault. Huge fault does the check in fault
110 * handlers. And this check is not suitable for huge PUD fault.
113 !transhuge_vma_suitable(vma, (vma->vm_end - HPAGE_PMD_SIZE)))
117 * Enabled via shmem mount options or sysfs settings.
118 * Must be done before hugepage flags check since shmem has its
121 if (!in_pf && shmem_file(vma->vm_file))
122 return shmem_huge_enabled(vma, !enforce_sysfs);
124 /* Enforce sysfs THP requirements as necessary */
126 (!hugepage_flags_enabled() || (!(vm_flags & VM_HUGEPAGE) &&
127 !hugepage_flags_always())))
130 /* Only regular file is valid */
131 if (!in_pf && file_thp_enabled(vma))
134 if (!vma_is_anonymous(vma))
137 if (vma_is_temporary_stack(vma))
141 * THPeligible bit of smaps should show 1 for proper VMAs even
142 * though anon_vma is not initialized yet.
144 * Allow page fault since anon_vma may be not initialized until
145 * the first page fault.
148 return (smaps || in_pf);
153 static bool get_huge_zero_page(void)
155 struct page *zero_page;
157 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
160 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
163 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
167 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
169 __free_pages(zero_page, compound_order(zero_page));
172 WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page));
174 /* We take additional reference here. It will be put back by shrinker */
175 atomic_set(&huge_zero_refcount, 2);
177 count_vm_event(THP_ZERO_PAGE_ALLOC);
181 static void put_huge_zero_page(void)
184 * Counter should never go to zero here. Only shrinker can put
187 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
190 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
192 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
193 return READ_ONCE(huge_zero_page);
195 if (!get_huge_zero_page())
198 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
199 put_huge_zero_page();
201 return READ_ONCE(huge_zero_page);
204 void mm_put_huge_zero_page(struct mm_struct *mm)
206 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
207 put_huge_zero_page();
210 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
211 struct shrink_control *sc)
213 /* we can free zero page only if last reference remains */
214 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
217 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
218 struct shrink_control *sc)
220 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
221 struct page *zero_page = xchg(&huge_zero_page, NULL);
222 BUG_ON(zero_page == NULL);
223 WRITE_ONCE(huge_zero_pfn, ~0UL);
224 __free_pages(zero_page, compound_order(zero_page));
231 static struct shrinker huge_zero_page_shrinker = {
232 .count_objects = shrink_huge_zero_page_count,
233 .scan_objects = shrink_huge_zero_page_scan,
234 .seeks = DEFAULT_SEEKS,
238 static ssize_t enabled_show(struct kobject *kobj,
239 struct kobj_attribute *attr, char *buf)
243 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
244 output = "[always] madvise never";
245 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
246 &transparent_hugepage_flags))
247 output = "always [madvise] never";
249 output = "always madvise [never]";
251 return sysfs_emit(buf, "%s\n", output);
254 static ssize_t enabled_store(struct kobject *kobj,
255 struct kobj_attribute *attr,
256 const char *buf, size_t count)
260 if (sysfs_streq(buf, "always")) {
261 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
262 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
263 } else if (sysfs_streq(buf, "madvise")) {
264 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
265 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
266 } else if (sysfs_streq(buf, "never")) {
267 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
268 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
273 int err = start_stop_khugepaged();
280 static struct kobj_attribute enabled_attr = __ATTR_RW(enabled);
282 ssize_t single_hugepage_flag_show(struct kobject *kobj,
283 struct kobj_attribute *attr, char *buf,
284 enum transparent_hugepage_flag flag)
286 return sysfs_emit(buf, "%d\n",
287 !!test_bit(flag, &transparent_hugepage_flags));
290 ssize_t single_hugepage_flag_store(struct kobject *kobj,
291 struct kobj_attribute *attr,
292 const char *buf, size_t count,
293 enum transparent_hugepage_flag flag)
298 ret = kstrtoul(buf, 10, &value);
305 set_bit(flag, &transparent_hugepage_flags);
307 clear_bit(flag, &transparent_hugepage_flags);
312 static ssize_t defrag_show(struct kobject *kobj,
313 struct kobj_attribute *attr, char *buf)
317 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
318 &transparent_hugepage_flags))
319 output = "[always] defer defer+madvise madvise never";
320 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
321 &transparent_hugepage_flags))
322 output = "always [defer] defer+madvise madvise never";
323 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
324 &transparent_hugepage_flags))
325 output = "always defer [defer+madvise] madvise never";
326 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
327 &transparent_hugepage_flags))
328 output = "always defer defer+madvise [madvise] never";
330 output = "always defer defer+madvise madvise [never]";
332 return sysfs_emit(buf, "%s\n", output);
335 static ssize_t defrag_store(struct kobject *kobj,
336 struct kobj_attribute *attr,
337 const char *buf, size_t count)
339 if (sysfs_streq(buf, "always")) {
340 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
341 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
342 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
343 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
344 } else if (sysfs_streq(buf, "defer+madvise")) {
345 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
346 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
347 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
348 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
349 } else if (sysfs_streq(buf, "defer")) {
350 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
351 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
352 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
353 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
354 } else if (sysfs_streq(buf, "madvise")) {
355 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
356 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
357 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
358 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
359 } else if (sysfs_streq(buf, "never")) {
360 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
361 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
362 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
363 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
369 static struct kobj_attribute defrag_attr = __ATTR_RW(defrag);
371 static ssize_t use_zero_page_show(struct kobject *kobj,
372 struct kobj_attribute *attr, char *buf)
374 return single_hugepage_flag_show(kobj, attr, buf,
375 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
377 static ssize_t use_zero_page_store(struct kobject *kobj,
378 struct kobj_attribute *attr, const char *buf, size_t count)
380 return single_hugepage_flag_store(kobj, attr, buf, count,
381 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
383 static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page);
385 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
386 struct kobj_attribute *attr, char *buf)
388 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE);
390 static struct kobj_attribute hpage_pmd_size_attr =
391 __ATTR_RO(hpage_pmd_size);
393 static struct attribute *hugepage_attr[] = {
396 &use_zero_page_attr.attr,
397 &hpage_pmd_size_attr.attr,
399 &shmem_enabled_attr.attr,
404 static const struct attribute_group hugepage_attr_group = {
405 .attrs = hugepage_attr,
408 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
412 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
413 if (unlikely(!*hugepage_kobj)) {
414 pr_err("failed to create transparent hugepage kobject\n");
418 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
420 pr_err("failed to register transparent hugepage group\n");
424 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
426 pr_err("failed to register transparent hugepage group\n");
427 goto remove_hp_group;
433 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
435 kobject_put(*hugepage_kobj);
439 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
441 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
442 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
443 kobject_put(hugepage_kobj);
446 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
451 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
454 #endif /* CONFIG_SYSFS */
456 static int __init hugepage_init(void)
459 struct kobject *hugepage_kobj;
461 if (!has_transparent_hugepage()) {
463 * Hardware doesn't support hugepages, hence disable
466 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX;
471 * hugepages can't be allocated by the buddy allocator
473 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
475 * we use page->mapping and page->index in second tail page
476 * as list_head: assuming THP order >= 2
478 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
480 err = hugepage_init_sysfs(&hugepage_kobj);
484 err = khugepaged_init();
488 err = register_shrinker(&huge_zero_page_shrinker, "thp-zero");
490 goto err_hzp_shrinker;
491 err = register_shrinker(&deferred_split_shrinker, "thp-deferred_split");
493 goto err_split_shrinker;
496 * By default disable transparent hugepages on smaller systems,
497 * where the extra memory used could hurt more than TLB overhead
498 * is likely to save. The admin can still enable it through /sys.
500 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
501 transparent_hugepage_flags = 0;
505 err = start_stop_khugepaged();
511 unregister_shrinker(&deferred_split_shrinker);
513 unregister_shrinker(&huge_zero_page_shrinker);
515 khugepaged_destroy();
517 hugepage_exit_sysfs(hugepage_kobj);
521 subsys_initcall(hugepage_init);
523 static int __init setup_transparent_hugepage(char *str)
528 if (!strcmp(str, "always")) {
529 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
530 &transparent_hugepage_flags);
531 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
532 &transparent_hugepage_flags);
534 } else if (!strcmp(str, "madvise")) {
535 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
536 &transparent_hugepage_flags);
537 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
538 &transparent_hugepage_flags);
540 } else if (!strcmp(str, "never")) {
541 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
542 &transparent_hugepage_flags);
543 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
544 &transparent_hugepage_flags);
549 pr_warn("transparent_hugepage= cannot parse, ignored\n");
552 __setup("transparent_hugepage=", setup_transparent_hugepage);
554 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
556 if (likely(vma->vm_flags & VM_WRITE))
557 pmd = pmd_mkwrite(pmd);
562 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
564 struct mem_cgroup *memcg = page_memcg(compound_head(page));
565 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
568 return &memcg->deferred_split_queue;
570 return &pgdat->deferred_split_queue;
573 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
575 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
577 return &pgdat->deferred_split_queue;
581 void prep_transhuge_page(struct page *page)
584 * we use page->mapping and page->index in second tail page
585 * as list_head: assuming THP order >= 2
588 INIT_LIST_HEAD(page_deferred_list(page));
589 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
592 static inline bool is_transparent_hugepage(struct page *page)
594 if (!PageCompound(page))
597 page = compound_head(page);
598 return is_huge_zero_page(page) ||
599 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR;
602 static unsigned long __thp_get_unmapped_area(struct file *filp,
603 unsigned long addr, unsigned long len,
604 loff_t off, unsigned long flags, unsigned long size)
606 loff_t off_end = off + len;
607 loff_t off_align = round_up(off, size);
608 unsigned long len_pad, ret;
610 if (off_end <= off_align || (off_end - off_align) < size)
613 len_pad = len + size;
614 if (len_pad < len || (off + len_pad) < off)
617 ret = current->mm->get_unmapped_area(filp, addr, len_pad,
618 off >> PAGE_SHIFT, flags);
621 * The failure might be due to length padding. The caller will retry
622 * without the padding.
624 if (IS_ERR_VALUE(ret))
628 * Do not try to align to THP boundary if allocation at the address
634 ret += (off - ret) & (size - 1);
638 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
639 unsigned long len, unsigned long pgoff, unsigned long flags)
642 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
644 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
648 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
650 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
652 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
653 struct page *page, gfp_t gfp)
655 struct vm_area_struct *vma = vmf->vma;
657 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
660 VM_BUG_ON_PAGE(!PageCompound(page), page);
662 if (mem_cgroup_charge(page_folio(page), vma->vm_mm, gfp)) {
664 count_vm_event(THP_FAULT_FALLBACK);
665 count_vm_event(THP_FAULT_FALLBACK_CHARGE);
666 return VM_FAULT_FALLBACK;
668 cgroup_throttle_swaprate(page, gfp);
670 pgtable = pte_alloc_one(vma->vm_mm);
671 if (unlikely(!pgtable)) {
676 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
678 * The memory barrier inside __SetPageUptodate makes sure that
679 * clear_huge_page writes become visible before the set_pmd_at()
682 __SetPageUptodate(page);
684 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
685 if (unlikely(!pmd_none(*vmf->pmd))) {
690 ret = check_stable_address_space(vma->vm_mm);
694 /* Deliver the page fault to userland */
695 if (userfaultfd_missing(vma)) {
696 spin_unlock(vmf->ptl);
698 pte_free(vma->vm_mm, pgtable);
699 ret = handle_userfault(vmf, VM_UFFD_MISSING);
700 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
704 entry = mk_huge_pmd(page, vma->vm_page_prot);
705 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
706 page_add_new_anon_rmap(page, vma, haddr);
707 lru_cache_add_inactive_or_unevictable(page, vma);
708 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
709 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
710 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
711 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
712 mm_inc_nr_ptes(vma->vm_mm);
713 spin_unlock(vmf->ptl);
714 count_vm_event(THP_FAULT_ALLOC);
715 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
720 spin_unlock(vmf->ptl);
723 pte_free(vma->vm_mm, pgtable);
730 * always: directly stall for all thp allocations
731 * defer: wake kswapd and fail if not immediately available
732 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
733 * fail if not immediately available
734 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
736 * never: never stall for any thp allocation
738 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma)
740 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE);
742 /* Always do synchronous compaction */
743 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
744 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
746 /* Kick kcompactd and fail quickly */
747 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
748 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
750 /* Synchronous compaction if madvised, otherwise kick kcompactd */
751 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
752 return GFP_TRANSHUGE_LIGHT |
753 (vma_madvised ? __GFP_DIRECT_RECLAIM :
754 __GFP_KSWAPD_RECLAIM);
756 /* Only do synchronous compaction if madvised */
757 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
758 return GFP_TRANSHUGE_LIGHT |
759 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
761 return GFP_TRANSHUGE_LIGHT;
764 /* Caller must hold page table lock. */
765 static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
766 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
767 struct page *zero_page)
772 entry = mk_pmd(zero_page, vma->vm_page_prot);
773 entry = pmd_mkhuge(entry);
774 pgtable_trans_huge_deposit(mm, pmd, pgtable);
775 set_pmd_at(mm, haddr, pmd, entry);
779 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
781 struct vm_area_struct *vma = vmf->vma;
784 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
786 if (!transhuge_vma_suitable(vma, haddr))
787 return VM_FAULT_FALLBACK;
788 if (unlikely(anon_vma_prepare(vma)))
790 khugepaged_enter_vma(vma, vma->vm_flags);
792 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
793 !mm_forbids_zeropage(vma->vm_mm) &&
794 transparent_hugepage_use_zero_page()) {
796 struct page *zero_page;
798 pgtable = pte_alloc_one(vma->vm_mm);
799 if (unlikely(!pgtable))
801 zero_page = mm_get_huge_zero_page(vma->vm_mm);
802 if (unlikely(!zero_page)) {
803 pte_free(vma->vm_mm, pgtable);
804 count_vm_event(THP_FAULT_FALLBACK);
805 return VM_FAULT_FALLBACK;
807 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
809 if (pmd_none(*vmf->pmd)) {
810 ret = check_stable_address_space(vma->vm_mm);
812 spin_unlock(vmf->ptl);
813 pte_free(vma->vm_mm, pgtable);
814 } else if (userfaultfd_missing(vma)) {
815 spin_unlock(vmf->ptl);
816 pte_free(vma->vm_mm, pgtable);
817 ret = handle_userfault(vmf, VM_UFFD_MISSING);
818 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
820 set_huge_zero_page(pgtable, vma->vm_mm, vma,
821 haddr, vmf->pmd, zero_page);
822 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
823 spin_unlock(vmf->ptl);
826 spin_unlock(vmf->ptl);
827 pte_free(vma->vm_mm, pgtable);
831 gfp = vma_thp_gfp_mask(vma);
832 folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, haddr, true);
833 if (unlikely(!folio)) {
834 count_vm_event(THP_FAULT_FALLBACK);
835 return VM_FAULT_FALLBACK;
837 return __do_huge_pmd_anonymous_page(vmf, &folio->page, gfp);
840 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
841 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
844 struct mm_struct *mm = vma->vm_mm;
848 ptl = pmd_lock(mm, pmd);
849 if (!pmd_none(*pmd)) {
851 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
852 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
855 entry = pmd_mkyoung(*pmd);
856 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
857 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
858 update_mmu_cache_pmd(vma, addr, pmd);
864 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
865 if (pfn_t_devmap(pfn))
866 entry = pmd_mkdevmap(entry);
868 entry = pmd_mkyoung(pmd_mkdirty(entry));
869 entry = maybe_pmd_mkwrite(entry, vma);
873 pgtable_trans_huge_deposit(mm, pmd, pgtable);
878 set_pmd_at(mm, addr, pmd, entry);
879 update_mmu_cache_pmd(vma, addr, pmd);
884 pte_free(mm, pgtable);
888 * vmf_insert_pfn_pmd_prot - insert a pmd size pfn
889 * @vmf: Structure describing the fault
890 * @pfn: pfn to insert
891 * @pgprot: page protection to use
892 * @write: whether it's a write fault
894 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and
895 * also consult the vmf_insert_mixed_prot() documentation when
896 * @pgprot != @vmf->vma->vm_page_prot.
898 * Return: vm_fault_t value.
900 vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
901 pgprot_t pgprot, bool write)
903 unsigned long addr = vmf->address & PMD_MASK;
904 struct vm_area_struct *vma = vmf->vma;
905 pgtable_t pgtable = NULL;
908 * If we had pmd_special, we could avoid all these restrictions,
909 * but we need to be consistent with PTEs and architectures that
910 * can't support a 'special' bit.
912 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
914 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
915 (VM_PFNMAP|VM_MIXEDMAP));
916 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
918 if (addr < vma->vm_start || addr >= vma->vm_end)
919 return VM_FAULT_SIGBUS;
921 if (arch_needs_pgtable_deposit()) {
922 pgtable = pte_alloc_one(vma->vm_mm);
927 track_pfn_insert(vma, &pgprot, pfn);
929 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
930 return VM_FAULT_NOPAGE;
932 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot);
934 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
935 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
937 if (likely(vma->vm_flags & VM_WRITE))
938 pud = pud_mkwrite(pud);
942 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
943 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
945 struct mm_struct *mm = vma->vm_mm;
949 ptl = pud_lock(mm, pud);
950 if (!pud_none(*pud)) {
952 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
953 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
956 entry = pud_mkyoung(*pud);
957 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
958 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
959 update_mmu_cache_pud(vma, addr, pud);
964 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
965 if (pfn_t_devmap(pfn))
966 entry = pud_mkdevmap(entry);
968 entry = pud_mkyoung(pud_mkdirty(entry));
969 entry = maybe_pud_mkwrite(entry, vma);
971 set_pud_at(mm, addr, pud, entry);
972 update_mmu_cache_pud(vma, addr, pud);
979 * vmf_insert_pfn_pud_prot - insert a pud size pfn
980 * @vmf: Structure describing the fault
981 * @pfn: pfn to insert
982 * @pgprot: page protection to use
983 * @write: whether it's a write fault
985 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and
986 * also consult the vmf_insert_mixed_prot() documentation when
987 * @pgprot != @vmf->vma->vm_page_prot.
989 * Return: vm_fault_t value.
991 vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn,
992 pgprot_t pgprot, bool write)
994 unsigned long addr = vmf->address & PUD_MASK;
995 struct vm_area_struct *vma = vmf->vma;
998 * If we had pud_special, we could avoid all these restrictions,
999 * but we need to be consistent with PTEs and architectures that
1000 * can't support a 'special' bit.
1002 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
1003 !pfn_t_devmap(pfn));
1004 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1005 (VM_PFNMAP|VM_MIXEDMAP));
1006 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1008 if (addr < vma->vm_start || addr >= vma->vm_end)
1009 return VM_FAULT_SIGBUS;
1011 track_pfn_insert(vma, &pgprot, pfn);
1013 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
1014 return VM_FAULT_NOPAGE;
1016 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot);
1017 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1019 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
1020 pmd_t *pmd, bool write)
1024 _pmd = pmd_mkyoung(*pmd);
1026 _pmd = pmd_mkdirty(_pmd);
1027 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
1029 update_mmu_cache_pmd(vma, addr, pmd);
1032 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
1033 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
1035 unsigned long pfn = pmd_pfn(*pmd);
1036 struct mm_struct *mm = vma->vm_mm;
1040 assert_spin_locked(pmd_lockptr(mm, pmd));
1042 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
1043 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
1044 (FOLL_PIN | FOLL_GET)))
1047 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1050 if (pmd_present(*pmd) && pmd_devmap(*pmd))
1055 if (flags & FOLL_TOUCH)
1056 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE);
1059 * device mapped pages can only be returned if the
1060 * caller will manage the page reference count.
1062 if (!(flags & (FOLL_GET | FOLL_PIN)))
1063 return ERR_PTR(-EEXIST);
1065 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
1066 *pgmap = get_dev_pagemap(pfn, *pgmap);
1068 return ERR_PTR(-EFAULT);
1069 page = pfn_to_page(pfn);
1070 ret = try_grab_page(page, flags);
1072 page = ERR_PTR(ret);
1077 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1078 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1079 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1081 spinlock_t *dst_ptl, *src_ptl;
1082 struct page *src_page;
1084 pgtable_t pgtable = NULL;
1087 /* Skip if can be re-fill on fault */
1088 if (!vma_is_anonymous(dst_vma))
1091 pgtable = pte_alloc_one(dst_mm);
1092 if (unlikely(!pgtable))
1095 dst_ptl = pmd_lock(dst_mm, dst_pmd);
1096 src_ptl = pmd_lockptr(src_mm, src_pmd);
1097 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1102 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1103 if (unlikely(is_swap_pmd(pmd))) {
1104 swp_entry_t entry = pmd_to_swp_entry(pmd);
1106 VM_BUG_ON(!is_pmd_migration_entry(pmd));
1107 if (!is_readable_migration_entry(entry)) {
1108 entry = make_readable_migration_entry(
1110 pmd = swp_entry_to_pmd(entry);
1111 if (pmd_swp_soft_dirty(*src_pmd))
1112 pmd = pmd_swp_mksoft_dirty(pmd);
1113 if (pmd_swp_uffd_wp(*src_pmd))
1114 pmd = pmd_swp_mkuffd_wp(pmd);
1115 set_pmd_at(src_mm, addr, src_pmd, pmd);
1117 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1118 mm_inc_nr_ptes(dst_mm);
1119 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1120 if (!userfaultfd_wp(dst_vma))
1121 pmd = pmd_swp_clear_uffd_wp(pmd);
1122 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1128 if (unlikely(!pmd_trans_huge(pmd))) {
1129 pte_free(dst_mm, pgtable);
1133 * When page table lock is held, the huge zero pmd should not be
1134 * under splitting since we don't split the page itself, only pmd to
1137 if (is_huge_zero_pmd(pmd)) {
1139 * get_huge_zero_page() will never allocate a new page here,
1140 * since we already have a zero page to copy. It just takes a
1143 mm_get_huge_zero_page(dst_mm);
1147 src_page = pmd_page(pmd);
1148 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1151 if (unlikely(page_try_dup_anon_rmap(src_page, true, src_vma))) {
1152 /* Page maybe pinned: split and retry the fault on PTEs. */
1154 pte_free(dst_mm, pgtable);
1155 spin_unlock(src_ptl);
1156 spin_unlock(dst_ptl);
1157 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL);
1160 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1162 mm_inc_nr_ptes(dst_mm);
1163 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1164 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1165 if (!userfaultfd_wp(dst_vma))
1166 pmd = pmd_clear_uffd_wp(pmd);
1167 pmd = pmd_mkold(pmd_wrprotect(pmd));
1168 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1172 spin_unlock(src_ptl);
1173 spin_unlock(dst_ptl);
1178 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1179 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1180 pud_t *pud, bool write)
1184 _pud = pud_mkyoung(*pud);
1186 _pud = pud_mkdirty(_pud);
1187 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1189 update_mmu_cache_pud(vma, addr, pud);
1192 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1193 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1195 unsigned long pfn = pud_pfn(*pud);
1196 struct mm_struct *mm = vma->vm_mm;
1200 assert_spin_locked(pud_lockptr(mm, pud));
1202 if (flags & FOLL_WRITE && !pud_write(*pud))
1205 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
1206 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
1207 (FOLL_PIN | FOLL_GET)))
1210 if (pud_present(*pud) && pud_devmap(*pud))
1215 if (flags & FOLL_TOUCH)
1216 touch_pud(vma, addr, pud, flags & FOLL_WRITE);
1219 * device mapped pages can only be returned if the
1220 * caller will manage the page reference count.
1222 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here:
1224 if (!(flags & (FOLL_GET | FOLL_PIN)))
1225 return ERR_PTR(-EEXIST);
1227 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1228 *pgmap = get_dev_pagemap(pfn, *pgmap);
1230 return ERR_PTR(-EFAULT);
1231 page = pfn_to_page(pfn);
1233 ret = try_grab_page(page, flags);
1235 page = ERR_PTR(ret);
1240 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1241 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1242 struct vm_area_struct *vma)
1244 spinlock_t *dst_ptl, *src_ptl;
1248 dst_ptl = pud_lock(dst_mm, dst_pud);
1249 src_ptl = pud_lockptr(src_mm, src_pud);
1250 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1254 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1258 * When page table lock is held, the huge zero pud should not be
1259 * under splitting since we don't split the page itself, only pud to
1262 if (is_huge_zero_pud(pud)) {
1263 /* No huge zero pud yet */
1267 * TODO: once we support anonymous pages, use page_try_dup_anon_rmap()
1268 * and split if duplicating fails.
1270 pudp_set_wrprotect(src_mm, addr, src_pud);
1271 pud = pud_mkold(pud_wrprotect(pud));
1272 set_pud_at(dst_mm, addr, dst_pud, pud);
1276 spin_unlock(src_ptl);
1277 spin_unlock(dst_ptl);
1281 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1283 bool write = vmf->flags & FAULT_FLAG_WRITE;
1285 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1286 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1289 touch_pud(vmf->vma, vmf->address, vmf->pud, write);
1291 spin_unlock(vmf->ptl);
1293 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1295 void huge_pmd_set_accessed(struct vm_fault *vmf)
1297 bool write = vmf->flags & FAULT_FLAG_WRITE;
1299 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1300 if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd)))
1303 touch_pmd(vmf->vma, vmf->address, vmf->pmd, write);
1306 spin_unlock(vmf->ptl);
1309 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf)
1311 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
1312 struct vm_area_struct *vma = vmf->vma;
1313 struct folio *folio;
1315 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1316 pmd_t orig_pmd = vmf->orig_pmd;
1318 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1319 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1321 if (is_huge_zero_pmd(orig_pmd))
1324 spin_lock(vmf->ptl);
1326 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1327 spin_unlock(vmf->ptl);
1331 page = pmd_page(orig_pmd);
1332 folio = page_folio(page);
1333 VM_BUG_ON_PAGE(!PageHead(page), page);
1335 /* Early check when only holding the PT lock. */
1336 if (PageAnonExclusive(page))
1339 if (!folio_trylock(folio)) {
1341 spin_unlock(vmf->ptl);
1343 spin_lock(vmf->ptl);
1344 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1345 spin_unlock(vmf->ptl);
1346 folio_unlock(folio);
1353 /* Recheck after temporarily dropping the PT lock. */
1354 if (PageAnonExclusive(page)) {
1355 folio_unlock(folio);
1360 * See do_wp_page(): we can only reuse the folio exclusively if
1361 * there are no additional references. Note that we always drain
1362 * the LRU pagevecs immediately after adding a THP.
1364 if (folio_ref_count(folio) >
1365 1 + folio_test_swapcache(folio) * folio_nr_pages(folio))
1366 goto unlock_fallback;
1367 if (folio_test_swapcache(folio))
1368 folio_free_swap(folio);
1369 if (folio_ref_count(folio) == 1) {
1372 page_move_anon_rmap(page, vma);
1373 folio_unlock(folio);
1375 if (unlikely(unshare)) {
1376 spin_unlock(vmf->ptl);
1379 entry = pmd_mkyoung(orig_pmd);
1380 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1381 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1382 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1383 spin_unlock(vmf->ptl);
1388 folio_unlock(folio);
1389 spin_unlock(vmf->ptl);
1391 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
1392 return VM_FAULT_FALLBACK;
1395 static inline bool can_change_pmd_writable(struct vm_area_struct *vma,
1396 unsigned long addr, pmd_t pmd)
1400 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
1403 /* Don't touch entries that are not even readable (NUMA hinting). */
1404 if (pmd_protnone(pmd))
1407 /* Do we need write faults for softdirty tracking? */
1408 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd))
1411 /* Do we need write faults for uffd-wp tracking? */
1412 if (userfaultfd_huge_pmd_wp(vma, pmd))
1415 if (!(vma->vm_flags & VM_SHARED)) {
1416 /* See can_change_pte_writable(). */
1417 page = vm_normal_page_pmd(vma, addr, pmd);
1418 return page && PageAnon(page) && PageAnonExclusive(page);
1421 /* See can_change_pte_writable(). */
1422 return pmd_dirty(pmd);
1425 /* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */
1426 static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page,
1427 struct vm_area_struct *vma,
1430 /* If the pmd is writable, we can write to the page. */
1434 /* Maybe FOLL_FORCE is set to override it? */
1435 if (!(flags & FOLL_FORCE))
1438 /* But FOLL_FORCE has no effect on shared mappings */
1439 if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED))
1442 /* ... or read-only private ones */
1443 if (!(vma->vm_flags & VM_MAYWRITE))
1446 /* ... or already writable ones that just need to take a write fault */
1447 if (vma->vm_flags & VM_WRITE)
1451 * See can_change_pte_writable(): we broke COW and could map the page
1452 * writable if we have an exclusive anonymous page ...
1454 if (!page || !PageAnon(page) || !PageAnonExclusive(page))
1457 /* ... and a write-fault isn't required for other reasons. */
1458 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd))
1460 return !userfaultfd_huge_pmd_wp(vma, pmd);
1463 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1468 struct mm_struct *mm = vma->vm_mm;
1472 assert_spin_locked(pmd_lockptr(mm, pmd));
1474 page = pmd_page(*pmd);
1475 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1477 if ((flags & FOLL_WRITE) &&
1478 !can_follow_write_pmd(*pmd, page, vma, flags))
1481 /* Avoid dumping huge zero page */
1482 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1483 return ERR_PTR(-EFAULT);
1485 /* Full NUMA hinting faults to serialise migration in fault paths */
1486 if (pmd_protnone(*pmd) && !gup_can_follow_protnone(flags))
1489 if (!pmd_write(*pmd) && gup_must_unshare(vma, flags, page))
1490 return ERR_PTR(-EMLINK);
1492 VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) &&
1493 !PageAnonExclusive(page), page);
1495 ret = try_grab_page(page, flags);
1497 return ERR_PTR(ret);
1499 if (flags & FOLL_TOUCH)
1500 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE);
1502 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1503 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1508 /* NUMA hinting page fault entry point for trans huge pmds */
1509 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
1511 struct vm_area_struct *vma = vmf->vma;
1512 pmd_t oldpmd = vmf->orig_pmd;
1515 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1516 int page_nid = NUMA_NO_NODE;
1517 int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK);
1518 bool migrated = false, writable = false;
1521 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1522 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
1523 spin_unlock(vmf->ptl);
1527 pmd = pmd_modify(oldpmd, vma->vm_page_prot);
1530 * Detect now whether the PMD could be writable; this information
1531 * is only valid while holding the PT lock.
1533 writable = pmd_write(pmd);
1534 if (!writable && vma_wants_manual_pte_write_upgrade(vma) &&
1535 can_change_pmd_writable(vma, vmf->address, pmd))
1538 page = vm_normal_page_pmd(vma, haddr, pmd);
1542 /* See similar comment in do_numa_page for explanation */
1544 flags |= TNF_NO_GROUP;
1546 page_nid = page_to_nid(page);
1548 * For memory tiering mode, cpupid of slow memory page is used
1549 * to record page access time. So use default value.
1551 if (node_is_toptier(page_nid))
1552 last_cpupid = page_cpupid_last(page);
1553 target_nid = numa_migrate_prep(page, vma, haddr, page_nid,
1556 if (target_nid == NUMA_NO_NODE) {
1561 spin_unlock(vmf->ptl);
1564 migrated = migrate_misplaced_page(page, vma, target_nid);
1566 flags |= TNF_MIGRATED;
1567 page_nid = target_nid;
1569 flags |= TNF_MIGRATE_FAIL;
1570 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1571 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
1572 spin_unlock(vmf->ptl);
1579 if (page_nid != NUMA_NO_NODE)
1580 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1586 /* Restore the PMD */
1587 pmd = pmd_modify(oldpmd, vma->vm_page_prot);
1588 pmd = pmd_mkyoung(pmd);
1590 pmd = pmd_mkwrite(pmd);
1591 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1592 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1593 spin_unlock(vmf->ptl);
1598 * Return true if we do MADV_FREE successfully on entire pmd page.
1599 * Otherwise, return false.
1601 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1602 pmd_t *pmd, unsigned long addr, unsigned long next)
1607 struct mm_struct *mm = tlb->mm;
1610 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1612 ptl = pmd_trans_huge_lock(pmd, vma);
1617 if (is_huge_zero_pmd(orig_pmd))
1620 if (unlikely(!pmd_present(orig_pmd))) {
1621 VM_BUG_ON(thp_migration_supported() &&
1622 !is_pmd_migration_entry(orig_pmd));
1626 page = pmd_page(orig_pmd);
1628 * If other processes are mapping this page, we couldn't discard
1629 * the page unless they all do MADV_FREE so let's skip the page.
1631 if (total_mapcount(page) != 1)
1634 if (!trylock_page(page))
1638 * If user want to discard part-pages of THP, split it so MADV_FREE
1639 * will deactivate only them.
1641 if (next - addr != HPAGE_PMD_SIZE) {
1644 split_huge_page(page);
1650 if (PageDirty(page))
1651 ClearPageDirty(page);
1654 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1655 pmdp_invalidate(vma, addr, pmd);
1656 orig_pmd = pmd_mkold(orig_pmd);
1657 orig_pmd = pmd_mkclean(orig_pmd);
1659 set_pmd_at(mm, addr, pmd, orig_pmd);
1660 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1663 mark_page_lazyfree(page);
1671 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1675 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1676 pte_free(mm, pgtable);
1680 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1681 pmd_t *pmd, unsigned long addr)
1686 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1688 ptl = __pmd_trans_huge_lock(pmd, vma);
1692 * For architectures like ppc64 we look at deposited pgtable
1693 * when calling pmdp_huge_get_and_clear. So do the
1694 * pgtable_trans_huge_withdraw after finishing pmdp related
1697 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd,
1699 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1700 if (vma_is_special_huge(vma)) {
1701 if (arch_needs_pgtable_deposit())
1702 zap_deposited_table(tlb->mm, pmd);
1704 } else if (is_huge_zero_pmd(orig_pmd)) {
1705 zap_deposited_table(tlb->mm, pmd);
1708 struct page *page = NULL;
1709 int flush_needed = 1;
1711 if (pmd_present(orig_pmd)) {
1712 page = pmd_page(orig_pmd);
1713 page_remove_rmap(page, vma, true);
1714 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1715 VM_BUG_ON_PAGE(!PageHead(page), page);
1716 } else if (thp_migration_supported()) {
1719 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1720 entry = pmd_to_swp_entry(orig_pmd);
1721 page = pfn_swap_entry_to_page(entry);
1724 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1726 if (PageAnon(page)) {
1727 zap_deposited_table(tlb->mm, pmd);
1728 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1730 if (arch_needs_pgtable_deposit())
1731 zap_deposited_table(tlb->mm, pmd);
1732 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1737 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1742 #ifndef pmd_move_must_withdraw
1743 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1744 spinlock_t *old_pmd_ptl,
1745 struct vm_area_struct *vma)
1748 * With split pmd lock we also need to move preallocated
1749 * PTE page table if new_pmd is on different PMD page table.
1751 * We also don't deposit and withdraw tables for file pages.
1753 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1757 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1759 #ifdef CONFIG_MEM_SOFT_DIRTY
1760 if (unlikely(is_pmd_migration_entry(pmd)))
1761 pmd = pmd_swp_mksoft_dirty(pmd);
1762 else if (pmd_present(pmd))
1763 pmd = pmd_mksoft_dirty(pmd);
1768 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1769 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
1771 spinlock_t *old_ptl, *new_ptl;
1773 struct mm_struct *mm = vma->vm_mm;
1774 bool force_flush = false;
1777 * The destination pmd shouldn't be established, free_pgtables()
1778 * should have release it.
1780 if (WARN_ON(!pmd_none(*new_pmd))) {
1781 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1786 * We don't have to worry about the ordering of src and dst
1787 * ptlocks because exclusive mmap_lock prevents deadlock.
1789 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1791 new_ptl = pmd_lockptr(mm, new_pmd);
1792 if (new_ptl != old_ptl)
1793 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1794 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1795 if (pmd_present(pmd))
1797 VM_BUG_ON(!pmd_none(*new_pmd));
1799 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1801 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1802 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1804 pmd = move_soft_dirty_pmd(pmd);
1805 set_pmd_at(mm, new_addr, new_pmd, pmd);
1807 flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1808 if (new_ptl != old_ptl)
1809 spin_unlock(new_ptl);
1810 spin_unlock(old_ptl);
1818 * - 0 if PMD could not be locked
1819 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary
1820 * or if prot_numa but THP migration is not supported
1821 * - HPAGE_PMD_NR if protections changed and TLB flush necessary
1823 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1824 pmd_t *pmd, unsigned long addr, pgprot_t newprot,
1825 unsigned long cp_flags)
1827 struct mm_struct *mm = vma->vm_mm;
1829 pmd_t oldpmd, entry;
1830 bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
1831 bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
1832 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
1835 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1837 if (prot_numa && !thp_migration_supported())
1840 ptl = __pmd_trans_huge_lock(pmd, vma);
1844 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1845 if (is_swap_pmd(*pmd)) {
1846 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1847 struct page *page = pfn_swap_entry_to_page(entry);
1849 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1850 if (is_writable_migration_entry(entry)) {
1853 * A protection check is difficult so
1854 * just be safe and disable write
1857 entry = make_readable_exclusive_migration_entry(swp_offset(entry));
1859 entry = make_readable_migration_entry(swp_offset(entry));
1860 newpmd = swp_entry_to_pmd(entry);
1861 if (pmd_swp_soft_dirty(*pmd))
1862 newpmd = pmd_swp_mksoft_dirty(newpmd);
1863 if (pmd_swp_uffd_wp(*pmd))
1864 newpmd = pmd_swp_mkuffd_wp(newpmd);
1865 set_pmd_at(mm, addr, pmd, newpmd);
1875 * Avoid trapping faults against the zero page. The read-only
1876 * data is likely to be read-cached on the local CPU and
1877 * local/remote hits to the zero page are not interesting.
1879 if (is_huge_zero_pmd(*pmd))
1882 if (pmd_protnone(*pmd))
1885 page = pmd_page(*pmd);
1886 toptier = node_is_toptier(page_to_nid(page));
1888 * Skip scanning top tier node if normal numa
1889 * balancing is disabled
1891 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
1895 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
1897 xchg_page_access_time(page, jiffies_to_msecs(jiffies));
1900 * In case prot_numa, we are under mmap_read_lock(mm). It's critical
1901 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1902 * which is also under mmap_read_lock(mm):
1905 * change_huge_pmd(prot_numa=1)
1906 * pmdp_huge_get_and_clear_notify()
1907 * madvise_dontneed()
1909 * pmd_trans_huge(*pmd) == 0 (without ptl)
1912 * // pmd is re-established
1914 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1915 * which may break userspace.
1917 * pmdp_invalidate_ad() is required to make sure we don't miss
1918 * dirty/young flags set by hardware.
1920 oldpmd = pmdp_invalidate_ad(vma, addr, pmd);
1922 entry = pmd_modify(oldpmd, newprot);
1924 entry = pmd_wrprotect(entry);
1925 entry = pmd_mkuffd_wp(entry);
1926 } else if (uffd_wp_resolve) {
1928 * Leave the write bit to be handled by PF interrupt
1929 * handler, then things like COW could be properly
1932 entry = pmd_clear_uffd_wp(entry);
1935 /* See change_pte_range(). */
1936 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(entry) &&
1937 can_change_pmd_writable(vma, addr, entry))
1938 entry = pmd_mkwrite(entry);
1941 set_pmd_at(mm, addr, pmd, entry);
1943 if (huge_pmd_needs_flush(oldpmd, entry))
1944 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE);
1951 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1953 * Note that if it returns page table lock pointer, this routine returns without
1954 * unlocking page table lock. So callers must unlock it.
1956 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1959 ptl = pmd_lock(vma->vm_mm, pmd);
1960 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1968 * Returns page table lock pointer if a given pud maps a thp, NULL otherwise.
1970 * Note that if it returns page table lock pointer, this routine returns without
1971 * unlocking page table lock. So callers must unlock it.
1973 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1977 ptl = pud_lock(vma->vm_mm, pud);
1978 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1984 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1985 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1986 pud_t *pud, unsigned long addr)
1990 ptl = __pud_trans_huge_lock(pud, vma);
1994 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
1995 tlb_remove_pud_tlb_entry(tlb, pud, addr);
1996 if (vma_is_special_huge(vma)) {
1998 /* No zero page support yet */
2000 /* No support for anonymous PUD pages yet */
2006 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2007 unsigned long haddr)
2009 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2010 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2011 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2012 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2014 count_vm_event(THP_SPLIT_PUD);
2016 pudp_huge_clear_flush_notify(vma, haddr, pud);
2019 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2020 unsigned long address)
2023 struct mmu_notifier_range range;
2025 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2026 address & HPAGE_PUD_MASK,
2027 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
2028 mmu_notifier_invalidate_range_start(&range);
2029 ptl = pud_lock(vma->vm_mm, pud);
2030 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2032 __split_huge_pud_locked(vma, pud, range.start);
2037 * No need to double call mmu_notifier->invalidate_range() callback as
2038 * the above pudp_huge_clear_flush_notify() did already call it.
2040 mmu_notifier_invalidate_range_only_end(&range);
2042 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2044 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2045 unsigned long haddr, pmd_t *pmd)
2047 struct mm_struct *mm = vma->vm_mm;
2053 * Leave pmd empty until pte is filled note that it is fine to delay
2054 * notification until mmu_notifier_invalidate_range_end() as we are
2055 * replacing a zero pmd write protected page with a zero pte write
2058 * See Documentation/mm/mmu_notifier.rst
2060 pmdp_huge_clear_flush(vma, haddr, pmd);
2062 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2063 pmd_populate(mm, &_pmd, pgtable);
2065 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2067 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2068 entry = pte_mkspecial(entry);
2069 pte = pte_offset_map(&_pmd, haddr);
2070 VM_BUG_ON(!pte_none(*pte));
2071 set_pte_at(mm, haddr, pte, entry);
2074 smp_wmb(); /* make pte visible before pmd */
2075 pmd_populate(mm, pmd, pgtable);
2078 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2079 unsigned long haddr, bool freeze)
2081 struct mm_struct *mm = vma->vm_mm;
2084 pmd_t old_pmd, _pmd;
2085 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
2086 bool anon_exclusive = false, dirty = false;
2090 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2091 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2092 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2093 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2094 && !pmd_devmap(*pmd));
2096 count_vm_event(THP_SPLIT_PMD);
2098 if (!vma_is_anonymous(vma)) {
2099 old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2101 * We are going to unmap this huge page. So
2102 * just go ahead and zap it
2104 if (arch_needs_pgtable_deposit())
2105 zap_deposited_table(mm, pmd);
2106 if (vma_is_special_huge(vma))
2108 if (unlikely(is_pmd_migration_entry(old_pmd))) {
2111 entry = pmd_to_swp_entry(old_pmd);
2112 page = pfn_swap_entry_to_page(entry);
2114 page = pmd_page(old_pmd);
2115 if (!PageDirty(page) && pmd_dirty(old_pmd))
2116 set_page_dirty(page);
2117 if (!PageReferenced(page) && pmd_young(old_pmd))
2118 SetPageReferenced(page);
2119 page_remove_rmap(page, vma, true);
2122 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2126 if (is_huge_zero_pmd(*pmd)) {
2128 * FIXME: Do we want to invalidate secondary mmu by calling
2129 * mmu_notifier_invalidate_range() see comments below inside
2130 * __split_huge_pmd() ?
2132 * We are going from a zero huge page write protected to zero
2133 * small page also write protected so it does not seems useful
2134 * to invalidate secondary mmu at this time.
2136 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2140 * Up to this point the pmd is present and huge and userland has the
2141 * whole access to the hugepage during the split (which happens in
2142 * place). If we overwrite the pmd with the not-huge version pointing
2143 * to the pte here (which of course we could if all CPUs were bug
2144 * free), userland could trigger a small page size TLB miss on the
2145 * small sized TLB while the hugepage TLB entry is still established in
2146 * the huge TLB. Some CPU doesn't like that.
2147 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum
2148 * 383 on page 105. Intel should be safe but is also warns that it's
2149 * only safe if the permission and cache attributes of the two entries
2150 * loaded in the two TLB is identical (which should be the case here).
2151 * But it is generally safer to never allow small and huge TLB entries
2152 * for the same virtual address to be loaded simultaneously. So instead
2153 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2154 * current pmd notpresent (atomically because here the pmd_trans_huge
2155 * must remain set at all times on the pmd until the split is complete
2156 * for this pmd), then we flush the SMP TLB and finally we write the
2157 * non-huge version of the pmd entry with pmd_populate.
2159 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2161 pmd_migration = is_pmd_migration_entry(old_pmd);
2162 if (unlikely(pmd_migration)) {
2165 entry = pmd_to_swp_entry(old_pmd);
2166 page = pfn_swap_entry_to_page(entry);
2167 write = is_writable_migration_entry(entry);
2169 anon_exclusive = is_readable_exclusive_migration_entry(entry);
2170 young = is_migration_entry_young(entry);
2171 dirty = is_migration_entry_dirty(entry);
2172 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2173 uffd_wp = pmd_swp_uffd_wp(old_pmd);
2175 page = pmd_page(old_pmd);
2176 if (pmd_dirty(old_pmd)) {
2180 write = pmd_write(old_pmd);
2181 young = pmd_young(old_pmd);
2182 soft_dirty = pmd_soft_dirty(old_pmd);
2183 uffd_wp = pmd_uffd_wp(old_pmd);
2185 VM_BUG_ON_PAGE(!page_count(page), page);
2188 * Without "freeze", we'll simply split the PMD, propagating the
2189 * PageAnonExclusive() flag for each PTE by setting it for
2190 * each subpage -- no need to (temporarily) clear.
2192 * With "freeze" we want to replace mapped pages by
2193 * migration entries right away. This is only possible if we
2194 * managed to clear PageAnonExclusive() -- see
2195 * set_pmd_migration_entry().
2197 * In case we cannot clear PageAnonExclusive(), split the PMD
2198 * only and let try_to_migrate_one() fail later.
2200 * See page_try_share_anon_rmap(): invalidate PMD first.
2202 anon_exclusive = PageAnon(page) && PageAnonExclusive(page);
2203 if (freeze && anon_exclusive && page_try_share_anon_rmap(page))
2206 page_ref_add(page, HPAGE_PMD_NR - 1);
2210 * Withdraw the table only after we mark the pmd entry invalid.
2211 * This's critical for some architectures (Power).
2213 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2214 pmd_populate(mm, &_pmd, pgtable);
2216 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2219 * Note that NUMA hinting access restrictions are not
2220 * transferred to avoid any possibility of altering
2221 * permissions across VMAs.
2223 if (freeze || pmd_migration) {
2224 swp_entry_t swp_entry;
2226 swp_entry = make_writable_migration_entry(
2227 page_to_pfn(page + i));
2228 else if (anon_exclusive)
2229 swp_entry = make_readable_exclusive_migration_entry(
2230 page_to_pfn(page + i));
2232 swp_entry = make_readable_migration_entry(
2233 page_to_pfn(page + i));
2235 swp_entry = make_migration_entry_young(swp_entry);
2237 swp_entry = make_migration_entry_dirty(swp_entry);
2238 entry = swp_entry_to_pte(swp_entry);
2240 entry = pte_swp_mksoft_dirty(entry);
2242 entry = pte_swp_mkuffd_wp(entry);
2244 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2245 entry = maybe_mkwrite(entry, vma);
2247 SetPageAnonExclusive(page + i);
2249 entry = pte_mkold(entry);
2250 /* NOTE: this may set soft-dirty too on some archs */
2252 entry = pte_mkdirty(entry);
2254 * NOTE: this needs to happen after pte_mkdirty,
2255 * because some archs (sparc64, loongarch) could
2256 * set hw write bit when mkdirty.
2259 entry = pte_wrprotect(entry);
2261 entry = pte_mksoft_dirty(entry);
2263 entry = pte_mkuffd_wp(entry);
2264 page_add_anon_rmap(page + i, vma, addr, false);
2266 pte = pte_offset_map(&_pmd, addr);
2267 BUG_ON(!pte_none(*pte));
2268 set_pte_at(mm, addr, pte, entry);
2273 page_remove_rmap(page, vma, true);
2277 smp_wmb(); /* make pte visible before pmd */
2278 pmd_populate(mm, pmd, pgtable);
2281 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2282 unsigned long address, bool freeze, struct folio *folio)
2285 struct mmu_notifier_range range;
2287 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2288 address & HPAGE_PMD_MASK,
2289 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2290 mmu_notifier_invalidate_range_start(&range);
2291 ptl = pmd_lock(vma->vm_mm, pmd);
2294 * If caller asks to setup a migration entry, we need a folio to check
2295 * pmd against. Otherwise we can end up replacing wrong folio.
2297 VM_BUG_ON(freeze && !folio);
2298 VM_WARN_ON_ONCE(folio && !folio_test_locked(folio));
2300 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) ||
2301 is_pmd_migration_entry(*pmd)) {
2303 * It's safe to call pmd_page when folio is set because it's
2304 * guaranteed that pmd is present.
2306 if (folio && folio != page_folio(pmd_page(*pmd)))
2308 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2314 * No need to double call mmu_notifier->invalidate_range() callback.
2315 * They are 3 cases to consider inside __split_huge_pmd_locked():
2316 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2317 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2318 * fault will trigger a flush_notify before pointing to a new page
2319 * (it is fine if the secondary mmu keeps pointing to the old zero
2320 * page in the meantime)
2321 * 3) Split a huge pmd into pte pointing to the same page. No need
2322 * to invalidate secondary tlb entry they are all still valid.
2323 * any further changes to individual pte will notify. So no need
2324 * to call mmu_notifier->invalidate_range()
2326 mmu_notifier_invalidate_range_only_end(&range);
2329 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2330 bool freeze, struct folio *folio)
2332 pmd_t *pmd = mm_find_pmd(vma->vm_mm, address);
2337 __split_huge_pmd(vma, pmd, address, freeze, folio);
2340 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address)
2343 * If the new address isn't hpage aligned and it could previously
2344 * contain an hugepage: check if we need to split an huge pmd.
2346 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) &&
2347 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE),
2348 ALIGN(address, HPAGE_PMD_SIZE)))
2349 split_huge_pmd_address(vma, address, false, NULL);
2352 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2353 unsigned long start,
2357 /* Check if we need to split start first. */
2358 split_huge_pmd_if_needed(vma, start);
2360 /* Check if we need to split end next. */
2361 split_huge_pmd_if_needed(vma, end);
2364 * If we're also updating the next vma vm_start,
2365 * check if we need to split it.
2367 if (adjust_next > 0) {
2368 struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end);
2369 unsigned long nstart = next->vm_start;
2370 nstart += adjust_next;
2371 split_huge_pmd_if_needed(next, nstart);
2375 static void unmap_folio(struct folio *folio)
2377 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD |
2380 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
2383 * Anon pages need migration entries to preserve them, but file
2384 * pages can simply be left unmapped, then faulted back on demand.
2385 * If that is ever changed (perhaps for mlock), update remap_page().
2387 if (folio_test_anon(folio))
2388 try_to_migrate(folio, ttu_flags);
2390 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK);
2393 static void remap_page(struct folio *folio, unsigned long nr)
2397 /* If unmap_folio() uses try_to_migrate() on file, remove this check */
2398 if (!folio_test_anon(folio))
2401 remove_migration_ptes(folio, folio, true);
2402 i += folio_nr_pages(folio);
2405 folio = folio_next(folio);
2409 static void lru_add_page_tail(struct page *head, struct page *tail,
2410 struct lruvec *lruvec, struct list_head *list)
2412 VM_BUG_ON_PAGE(!PageHead(head), head);
2413 VM_BUG_ON_PAGE(PageCompound(tail), head);
2414 VM_BUG_ON_PAGE(PageLRU(tail), head);
2415 lockdep_assert_held(&lruvec->lru_lock);
2418 /* page reclaim is reclaiming a huge page */
2419 VM_WARN_ON(PageLRU(head));
2421 list_add_tail(&tail->lru, list);
2423 /* head is still on lru (and we have it frozen) */
2424 VM_WARN_ON(!PageLRU(head));
2425 if (PageUnevictable(tail))
2426 tail->mlock_count = 0;
2428 list_add_tail(&tail->lru, &head->lru);
2433 static void __split_huge_page_tail(struct page *head, int tail,
2434 struct lruvec *lruvec, struct list_head *list)
2436 struct page *page_tail = head + tail;
2438 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2441 * Clone page flags before unfreezing refcount.
2443 * After successful get_page_unless_zero() might follow flags change,
2444 * for example lock_page() which set PG_waiters.
2446 * Note that for mapped sub-pages of an anonymous THP,
2447 * PG_anon_exclusive has been cleared in unmap_folio() and is stored in
2448 * the migration entry instead from where remap_page() will restore it.
2449 * We can still have PG_anon_exclusive set on effectively unmapped and
2450 * unreferenced sub-pages of an anonymous THP: we can simply drop
2451 * PG_anon_exclusive (-> PG_mappedtodisk) for these here.
2453 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2454 page_tail->flags |= (head->flags &
2455 ((1L << PG_referenced) |
2456 (1L << PG_swapbacked) |
2457 (1L << PG_swapcache) |
2458 (1L << PG_mlocked) |
2459 (1L << PG_uptodate) |
2461 (1L << PG_workingset) |
2463 (1L << PG_unevictable) |
2464 #ifdef CONFIG_ARCH_USES_PG_ARCH_X
2469 LRU_GEN_MASK | LRU_REFS_MASK));
2471 /* ->mapping in first and second tail page is replaced by other uses */
2472 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2474 page_tail->mapping = head->mapping;
2475 page_tail->index = head->index + tail;
2478 * page->private should not be set in tail pages with the exception
2479 * of swap cache pages that store the swp_entry_t in tail pages.
2480 * Fix up and warn once if private is unexpectedly set.
2482 * What of 32-bit systems, on which head[1].compound_pincount overlays
2483 * head[1].private? No problem: THP_SWAP is not enabled on 32-bit, and
2484 * compound_pincount must be 0 for folio_ref_freeze() to have succeeded.
2486 if (!folio_test_swapcache(page_folio(head))) {
2487 VM_WARN_ON_ONCE_PAGE(page_tail->private != 0, page_tail);
2488 page_tail->private = 0;
2491 /* Page flags must be visible before we make the page non-compound. */
2495 * Clear PageTail before unfreezing page refcount.
2497 * After successful get_page_unless_zero() might follow put_page()
2498 * which needs correct compound_head().
2500 clear_compound_head(page_tail);
2502 /* Finally unfreeze refcount. Additional reference from page cache. */
2503 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2504 PageSwapCache(head)));
2506 if (page_is_young(head))
2507 set_page_young(page_tail);
2508 if (page_is_idle(head))
2509 set_page_idle(page_tail);
2511 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2514 * always add to the tail because some iterators expect new
2515 * pages to show after the currently processed elements - e.g.
2518 lru_add_page_tail(head, page_tail, lruvec, list);
2521 static void __split_huge_page(struct page *page, struct list_head *list,
2524 struct folio *folio = page_folio(page);
2525 struct page *head = &folio->page;
2526 struct lruvec *lruvec;
2527 struct address_space *swap_cache = NULL;
2528 unsigned long offset = 0;
2529 unsigned int nr = thp_nr_pages(head);
2532 /* complete memcg works before add pages to LRU */
2533 split_page_memcg(head, nr);
2535 if (PageAnon(head) && PageSwapCache(head)) {
2536 swp_entry_t entry = { .val = page_private(head) };
2538 offset = swp_offset(entry);
2539 swap_cache = swap_address_space(entry);
2540 xa_lock(&swap_cache->i_pages);
2543 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
2544 lruvec = folio_lruvec_lock(folio);
2546 ClearPageHasHWPoisoned(head);
2548 for (i = nr - 1; i >= 1; i--) {
2549 __split_huge_page_tail(head, i, lruvec, list);
2550 /* Some pages can be beyond EOF: drop them from page cache */
2551 if (head[i].index >= end) {
2552 struct folio *tail = page_folio(head + i);
2554 if (shmem_mapping(head->mapping))
2555 shmem_uncharge(head->mapping->host, 1);
2556 else if (folio_test_clear_dirty(tail))
2557 folio_account_cleaned(tail,
2558 inode_to_wb(folio->mapping->host));
2559 __filemap_remove_folio(tail, NULL);
2561 } else if (!PageAnon(page)) {
2562 __xa_store(&head->mapping->i_pages, head[i].index,
2564 } else if (swap_cache) {
2565 __xa_store(&swap_cache->i_pages, offset + i,
2570 ClearPageCompound(head);
2571 unlock_page_lruvec(lruvec);
2572 /* Caller disabled irqs, so they are still disabled here */
2574 split_page_owner(head, nr);
2576 /* See comment in __split_huge_page_tail() */
2577 if (PageAnon(head)) {
2578 /* Additional pin to swap cache */
2579 if (PageSwapCache(head)) {
2580 page_ref_add(head, 2);
2581 xa_unlock(&swap_cache->i_pages);
2586 /* Additional pin to page cache */
2587 page_ref_add(head, 2);
2588 xa_unlock(&head->mapping->i_pages);
2592 remap_page(folio, nr);
2594 if (PageSwapCache(head)) {
2595 swp_entry_t entry = { .val = page_private(head) };
2597 split_swap_cluster(entry);
2600 for (i = 0; i < nr; i++) {
2601 struct page *subpage = head + i;
2602 if (subpage == page)
2604 unlock_page(subpage);
2607 * Subpages may be freed if there wasn't any mapping
2608 * like if add_to_swap() is running on a lru page that
2609 * had its mapping zapped. And freeing these pages
2610 * requires taking the lru_lock so we do the put_page
2611 * of the tail pages after the split is complete.
2613 free_page_and_swap_cache(subpage);
2617 /* Racy check whether the huge page can be split */
2618 bool can_split_folio(struct folio *folio, int *pextra_pins)
2622 /* Additional pins from page cache */
2623 if (folio_test_anon(folio))
2624 extra_pins = folio_test_swapcache(folio) ?
2625 folio_nr_pages(folio) : 0;
2627 extra_pins = folio_nr_pages(folio);
2629 *pextra_pins = extra_pins;
2630 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1;
2634 * This function splits huge page into normal pages. @page can point to any
2635 * subpage of huge page to split. Split doesn't change the position of @page.
2637 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2638 * The huge page must be locked.
2640 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2642 * Both head page and tail pages will inherit mapping, flags, and so on from
2645 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2646 * they are not mapped.
2648 * Returns 0 if the hugepage is split successfully.
2649 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2652 int split_huge_page_to_list(struct page *page, struct list_head *list)
2654 struct folio *folio = page_folio(page);
2655 struct deferred_split *ds_queue = get_deferred_split_queue(&folio->page);
2656 XA_STATE(xas, &folio->mapping->i_pages, folio->index);
2657 struct anon_vma *anon_vma = NULL;
2658 struct address_space *mapping = NULL;
2659 int extra_pins, ret;
2663 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
2664 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
2666 is_hzp = is_huge_zero_page(&folio->page);
2667 VM_WARN_ON_ONCE_FOLIO(is_hzp, folio);
2671 if (folio_test_writeback(folio))
2674 if (folio_test_anon(folio)) {
2676 * The caller does not necessarily hold an mmap_lock that would
2677 * prevent the anon_vma disappearing so we first we take a
2678 * reference to it and then lock the anon_vma for write. This
2679 * is similar to folio_lock_anon_vma_read except the write lock
2680 * is taken to serialise against parallel split or collapse
2683 anon_vma = folio_get_anon_vma(folio);
2690 anon_vma_lock_write(anon_vma);
2694 mapping = folio->mapping;
2702 gfp = current_gfp_context(mapping_gfp_mask(mapping) &
2705 if (folio_test_private(folio) &&
2706 !filemap_release_folio(folio, gfp)) {
2711 xas_split_alloc(&xas, folio, folio_order(folio), gfp);
2712 if (xas_error(&xas)) {
2713 ret = xas_error(&xas);
2718 i_mmap_lock_read(mapping);
2721 *__split_huge_page() may need to trim off pages beyond EOF:
2722 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2723 * which cannot be nested inside the page tree lock. So note
2724 * end now: i_size itself may be changed at any moment, but
2725 * folio lock is good enough to serialize the trimming.
2727 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2728 if (shmem_mapping(mapping))
2729 end = shmem_fallocend(mapping->host, end);
2733 * Racy check if we can split the page, before unmap_folio() will
2736 if (!can_split_folio(folio, &extra_pins)) {
2743 /* block interrupt reentry in xa_lock and spinlock */
2744 local_irq_disable();
2747 * Check if the folio is present in page cache.
2748 * We assume all tail are present too, if folio is there.
2752 if (xas_load(&xas) != folio)
2756 /* Prevent deferred_split_scan() touching ->_refcount */
2757 spin_lock(&ds_queue->split_queue_lock);
2758 if (folio_ref_freeze(folio, 1 + extra_pins)) {
2759 if (!list_empty(page_deferred_list(&folio->page))) {
2760 ds_queue->split_queue_len--;
2761 list_del(page_deferred_list(&folio->page));
2763 spin_unlock(&ds_queue->split_queue_lock);
2765 int nr = folio_nr_pages(folio);
2767 xas_split(&xas, folio, folio_order(folio));
2768 if (folio_test_swapbacked(folio)) {
2769 __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS,
2772 __lruvec_stat_mod_folio(folio, NR_FILE_THPS,
2774 filemap_nr_thps_dec(mapping);
2778 __split_huge_page(page, list, end);
2781 spin_unlock(&ds_queue->split_queue_lock);
2786 remap_page(folio, folio_nr_pages(folio));
2792 anon_vma_unlock_write(anon_vma);
2793 put_anon_vma(anon_vma);
2796 i_mmap_unlock_read(mapping);
2799 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2803 void free_transhuge_page(struct page *page)
2805 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2806 unsigned long flags;
2808 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2809 if (!list_empty(page_deferred_list(page))) {
2810 ds_queue->split_queue_len--;
2811 list_del(page_deferred_list(page));
2813 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2814 free_compound_page(page);
2817 void deferred_split_huge_page(struct page *page)
2819 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2821 struct mem_cgroup *memcg = page_memcg(compound_head(page));
2823 unsigned long flags;
2825 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2828 * The try_to_unmap() in page reclaim path might reach here too,
2829 * this may cause a race condition to corrupt deferred split queue.
2830 * And, if page reclaim is already handling the same page, it is
2831 * unnecessary to handle it again in shrinker.
2833 * Check PageSwapCache to determine if the page is being
2834 * handled by page reclaim since THP swap would add the page into
2835 * swap cache before calling try_to_unmap().
2837 if (PageSwapCache(page))
2840 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2841 if (list_empty(page_deferred_list(page))) {
2842 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2843 list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
2844 ds_queue->split_queue_len++;
2847 set_shrinker_bit(memcg, page_to_nid(page),
2848 deferred_split_shrinker.id);
2851 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2854 static unsigned long deferred_split_count(struct shrinker *shrink,
2855 struct shrink_control *sc)
2857 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2858 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2862 ds_queue = &sc->memcg->deferred_split_queue;
2864 return READ_ONCE(ds_queue->split_queue_len);
2867 static unsigned long deferred_split_scan(struct shrinker *shrink,
2868 struct shrink_control *sc)
2870 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2871 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2872 unsigned long flags;
2873 LIST_HEAD(list), *pos, *next;
2879 ds_queue = &sc->memcg->deferred_split_queue;
2882 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2883 /* Take pin on all head pages to avoid freeing them under us */
2884 list_for_each_safe(pos, next, &ds_queue->split_queue) {
2885 page = list_entry((void *)pos, struct page, deferred_list);
2886 page = compound_head(page);
2887 if (get_page_unless_zero(page)) {
2888 list_move(page_deferred_list(page), &list);
2890 /* We lost race with put_compound_page() */
2891 list_del_init(page_deferred_list(page));
2892 ds_queue->split_queue_len--;
2894 if (!--sc->nr_to_scan)
2897 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2899 list_for_each_safe(pos, next, &list) {
2900 page = list_entry((void *)pos, struct page, deferred_list);
2901 if (!trylock_page(page))
2903 /* split_huge_page() removes page from list on success */
2904 if (!split_huge_page(page))
2911 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2912 list_splice_tail(&list, &ds_queue->split_queue);
2913 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2916 * Stop shrinker if we didn't split any page, but the queue is empty.
2917 * This can happen if pages were freed under us.
2919 if (!split && list_empty(&ds_queue->split_queue))
2924 static struct shrinker deferred_split_shrinker = {
2925 .count_objects = deferred_split_count,
2926 .scan_objects = deferred_split_scan,
2927 .seeks = DEFAULT_SEEKS,
2928 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
2932 #ifdef CONFIG_DEBUG_FS
2933 static void split_huge_pages_all(void)
2937 unsigned long pfn, max_zone_pfn;
2938 unsigned long total = 0, split = 0;
2940 pr_debug("Split all THPs\n");
2941 for_each_zone(zone) {
2942 if (!managed_zone(zone))
2944 max_zone_pfn = zone_end_pfn(zone);
2945 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2948 page = pfn_to_online_page(pfn);
2949 if (!page || !get_page_unless_zero(page))
2952 if (zone != page_zone(page))
2955 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2960 nr_pages = thp_nr_pages(page);
2961 if (!split_huge_page(page))
2963 pfn += nr_pages - 1;
2971 pr_debug("%lu of %lu THP split\n", split, total);
2974 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma)
2976 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) ||
2977 is_vm_hugetlb_page(vma);
2980 static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
2981 unsigned long vaddr_end)
2984 struct task_struct *task;
2985 struct mm_struct *mm;
2986 unsigned long total = 0, split = 0;
2989 vaddr_start &= PAGE_MASK;
2990 vaddr_end &= PAGE_MASK;
2992 /* Find the task_struct from pid */
2994 task = find_task_by_vpid(pid);
3000 get_task_struct(task);
3003 /* Find the mm_struct */
3004 mm = get_task_mm(task);
3005 put_task_struct(task);
3012 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n",
3013 pid, vaddr_start, vaddr_end);
3017 * always increase addr by PAGE_SIZE, since we could have a PTE page
3018 * table filled with PTE-mapped THPs, each of which is distinct.
3020 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) {
3021 struct vm_area_struct *vma = vma_lookup(mm, addr);
3027 /* skip special VMA and hugetlb VMA */
3028 if (vma_not_suitable_for_thp_split(vma)) {
3033 /* FOLL_DUMP to ignore special (like zero) pages */
3034 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
3036 if (IS_ERR_OR_NULL(page))
3039 if (!is_transparent_hugepage(page))
3043 if (!can_split_folio(page_folio(page), NULL))
3046 if (!trylock_page(page))
3049 if (!split_huge_page(page))
3057 mmap_read_unlock(mm);
3060 pr_debug("%lu of %lu THP split\n", split, total);
3066 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
3069 struct filename *file;
3070 struct file *candidate;
3071 struct address_space *mapping;
3075 unsigned long total = 0, split = 0;
3077 file = getname_kernel(file_path);
3081 candidate = file_open_name(file, O_RDONLY, 0);
3082 if (IS_ERR(candidate))
3085 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n",
3086 file_path, off_start, off_end);
3088 mapping = candidate->f_mapping;
3090 for (index = off_start; index < off_end; index += nr_pages) {
3091 struct folio *folio = __filemap_get_folio(mapping, index,
3095 if (xa_is_value(folio) || !folio)
3098 if (!folio_test_large(folio))
3102 nr_pages = folio_nr_pages(folio);
3104 if (!folio_trylock(folio))
3107 if (!split_folio(folio))
3110 folio_unlock(folio);
3116 filp_close(candidate, NULL);
3119 pr_debug("%lu of %lu file-backed THP split\n", split, total);
3125 #define MAX_INPUT_BUF_SZ 255
3127 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
3128 size_t count, loff_t *ppops)
3130 static DEFINE_MUTEX(split_debug_mutex);
3132 /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */
3133 char input_buf[MAX_INPUT_BUF_SZ];
3135 unsigned long vaddr_start, vaddr_end;
3137 ret = mutex_lock_interruptible(&split_debug_mutex);
3143 memset(input_buf, 0, MAX_INPUT_BUF_SZ);
3144 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ)))
3147 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0';
3149 if (input_buf[0] == '/') {
3151 char *buf = input_buf;
3152 char file_path[MAX_INPUT_BUF_SZ];
3153 pgoff_t off_start = 0, off_end = 0;
3154 size_t input_len = strlen(input_buf);
3156 tok = strsep(&buf, ",");
3158 strcpy(file_path, tok);
3164 ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end);
3169 ret = split_huge_pages_in_file(file_path, off_start, off_end);
3176 ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end);
3177 if (ret == 1 && pid == 1) {
3178 split_huge_pages_all();
3179 ret = strlen(input_buf);
3181 } else if (ret != 3) {
3186 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end);
3188 ret = strlen(input_buf);
3190 mutex_unlock(&split_debug_mutex);
3195 static const struct file_operations split_huge_pages_fops = {
3196 .owner = THIS_MODULE,
3197 .write = split_huge_pages_write,
3198 .llseek = no_llseek,
3201 static int __init split_huge_pages_debugfs(void)
3203 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
3204 &split_huge_pages_fops);
3207 late_initcall(split_huge_pages_debugfs);
3210 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
3211 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
3214 struct vm_area_struct *vma = pvmw->vma;
3215 struct mm_struct *mm = vma->vm_mm;
3216 unsigned long address = pvmw->address;
3217 bool anon_exclusive;
3222 if (!(pvmw->pmd && !pvmw->pte))
3225 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
3226 pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
3228 /* See page_try_share_anon_rmap(): invalidate PMD first. */
3229 anon_exclusive = PageAnon(page) && PageAnonExclusive(page);
3230 if (anon_exclusive && page_try_share_anon_rmap(page)) {
3231 set_pmd_at(mm, address, pvmw->pmd, pmdval);
3235 if (pmd_dirty(pmdval))
3236 set_page_dirty(page);
3237 if (pmd_write(pmdval))
3238 entry = make_writable_migration_entry(page_to_pfn(page));
3239 else if (anon_exclusive)
3240 entry = make_readable_exclusive_migration_entry(page_to_pfn(page));
3242 entry = make_readable_migration_entry(page_to_pfn(page));
3243 if (pmd_young(pmdval))
3244 entry = make_migration_entry_young(entry);
3245 if (pmd_dirty(pmdval))
3246 entry = make_migration_entry_dirty(entry);
3247 pmdswp = swp_entry_to_pmd(entry);
3248 if (pmd_soft_dirty(pmdval))
3249 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
3250 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
3251 page_remove_rmap(page, vma, true);
3253 trace_set_migration_pmd(address, pmd_val(pmdswp));
3258 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
3260 struct vm_area_struct *vma = pvmw->vma;
3261 struct mm_struct *mm = vma->vm_mm;
3262 unsigned long address = pvmw->address;
3263 unsigned long haddr = address & HPAGE_PMD_MASK;
3267 if (!(pvmw->pmd && !pvmw->pte))
3270 entry = pmd_to_swp_entry(*pvmw->pmd);
3272 pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot));
3273 if (pmd_swp_soft_dirty(*pvmw->pmd))
3274 pmde = pmd_mksoft_dirty(pmde);
3275 if (pmd_swp_uffd_wp(*pvmw->pmd))
3276 pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde));
3277 if (!is_migration_entry_young(entry))
3278 pmde = pmd_mkold(pmde);
3279 /* NOTE: this may contain setting soft-dirty on some archs */
3280 if (PageDirty(new) && is_migration_entry_dirty(entry))
3281 pmde = pmd_mkdirty(pmde);
3282 if (is_writable_migration_entry(entry))
3283 pmde = maybe_pmd_mkwrite(pmde, vma);
3285 pmde = pmd_wrprotect(pmde);
3287 if (PageAnon(new)) {
3288 rmap_t rmap_flags = RMAP_COMPOUND;
3290 if (!is_readable_migration_entry(entry))
3291 rmap_flags |= RMAP_EXCLUSIVE;
3293 page_add_anon_rmap(new, vma, haddr, rmap_flags);
3295 page_add_file_rmap(new, vma, true);
3297 VM_BUG_ON(pmd_write(pmde) && PageAnon(new) && !PageAnonExclusive(new));
3298 set_pmd_at(mm, haddr, pvmw->pmd, pmde);
3300 /* No need to invalidate - it was non-present before */
3301 update_mmu_cache_pmd(vma, address, pvmw->pmd);
3302 trace_remove_migration_pmd(address, pmd_val(pmde));