2 * Copyright (C) 2009 Red Hat, Inc.
4 * This work is licensed under the terms of the GNU GPL, version 2. See
5 * the COPYING file in the top-level directory.
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 #include <linux/sched.h>
12 #include <linux/sched/coredump.h>
13 #include <linux/sched/numa_balancing.h>
14 #include <linux/highmem.h>
15 #include <linux/hugetlb.h>
16 #include <linux/mmu_notifier.h>
17 #include <linux/rmap.h>
18 #include <linux/swap.h>
19 #include <linux/shrinker.h>
20 #include <linux/mm_inline.h>
21 #include <linux/swapops.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>
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;
66 bool transparent_hugepage_enabled(struct vm_area_struct *vma)
68 if (vma_is_anonymous(vma))
69 return __transparent_hugepage_enabled(vma);
70 if (vma_is_shmem(vma) && shmem_huge_enabled(vma))
71 return __transparent_hugepage_enabled(vma);
76 static struct page *get_huge_zero_page(void)
78 struct page *zero_page;
80 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
81 return READ_ONCE(huge_zero_page);
83 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
86 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
89 count_vm_event(THP_ZERO_PAGE_ALLOC);
91 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
93 __free_pages(zero_page, compound_order(zero_page));
97 /* We take additional reference here. It will be put back by shrinker */
98 atomic_set(&huge_zero_refcount, 2);
100 return READ_ONCE(huge_zero_page);
103 static void put_huge_zero_page(void)
106 * Counter should never go to zero here. Only shrinker can put
109 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
112 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
114 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
115 return READ_ONCE(huge_zero_page);
117 if (!get_huge_zero_page())
120 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
121 put_huge_zero_page();
123 return READ_ONCE(huge_zero_page);
126 void mm_put_huge_zero_page(struct mm_struct *mm)
128 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
129 put_huge_zero_page();
132 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
133 struct shrink_control *sc)
135 /* we can free zero page only if last reference remains */
136 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
139 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
140 struct shrink_control *sc)
142 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
143 struct page *zero_page = xchg(&huge_zero_page, NULL);
144 BUG_ON(zero_page == NULL);
145 __free_pages(zero_page, compound_order(zero_page));
152 static struct shrinker huge_zero_page_shrinker = {
153 .count_objects = shrink_huge_zero_page_count,
154 .scan_objects = shrink_huge_zero_page_scan,
155 .seeks = DEFAULT_SEEKS,
159 static ssize_t enabled_show(struct kobject *kobj,
160 struct kobj_attribute *attr, char *buf)
162 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
163 return sprintf(buf, "[always] madvise never\n");
164 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
165 return sprintf(buf, "always [madvise] never\n");
167 return sprintf(buf, "always madvise [never]\n");
170 static ssize_t enabled_store(struct kobject *kobj,
171 struct kobj_attribute *attr,
172 const char *buf, size_t count)
176 if (!memcmp("always", buf,
177 min(sizeof("always")-1, count))) {
178 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
179 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
180 } else if (!memcmp("madvise", buf,
181 min(sizeof("madvise")-1, count))) {
182 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
183 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
184 } else if (!memcmp("never", buf,
185 min(sizeof("never")-1, count))) {
186 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
187 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
192 int err = start_stop_khugepaged();
198 static struct kobj_attribute enabled_attr =
199 __ATTR(enabled, 0644, enabled_show, enabled_store);
201 ssize_t single_hugepage_flag_show(struct kobject *kobj,
202 struct kobj_attribute *attr, char *buf,
203 enum transparent_hugepage_flag flag)
205 return sprintf(buf, "%d\n",
206 !!test_bit(flag, &transparent_hugepage_flags));
209 ssize_t single_hugepage_flag_store(struct kobject *kobj,
210 struct kobj_attribute *attr,
211 const char *buf, size_t count,
212 enum transparent_hugepage_flag flag)
217 ret = kstrtoul(buf, 10, &value);
224 set_bit(flag, &transparent_hugepage_flags);
226 clear_bit(flag, &transparent_hugepage_flags);
231 static ssize_t defrag_show(struct kobject *kobj,
232 struct kobj_attribute *attr, char *buf)
234 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
235 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
236 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
237 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
238 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
239 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
240 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
241 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
242 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
245 static ssize_t defrag_store(struct kobject *kobj,
246 struct kobj_attribute *attr,
247 const char *buf, size_t count)
249 if (!memcmp("always", buf,
250 min(sizeof("always")-1, count))) {
251 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
252 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
253 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
254 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
255 } else if (!memcmp("defer+madvise", buf,
256 min(sizeof("defer+madvise")-1, count))) {
257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
258 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
259 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
260 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
261 } else if (!memcmp("defer", buf,
262 min(sizeof("defer")-1, count))) {
263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
264 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
265 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
266 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
267 } else if (!memcmp("madvise", buf,
268 min(sizeof("madvise")-1, count))) {
269 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
270 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
271 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
272 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
273 } else if (!memcmp("never", buf,
274 min(sizeof("never")-1, count))) {
275 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
276 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
277 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
278 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
284 static struct kobj_attribute defrag_attr =
285 __ATTR(defrag, 0644, defrag_show, defrag_store);
287 static ssize_t use_zero_page_show(struct kobject *kobj,
288 struct kobj_attribute *attr, char *buf)
290 return single_hugepage_flag_show(kobj, attr, buf,
291 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
293 static ssize_t use_zero_page_store(struct kobject *kobj,
294 struct kobj_attribute *attr, const char *buf, size_t count)
296 return single_hugepage_flag_store(kobj, attr, buf, count,
297 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
299 static struct kobj_attribute use_zero_page_attr =
300 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
302 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
303 struct kobj_attribute *attr, char *buf)
305 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
307 static struct kobj_attribute hpage_pmd_size_attr =
308 __ATTR_RO(hpage_pmd_size);
310 #ifdef CONFIG_DEBUG_VM
311 static ssize_t debug_cow_show(struct kobject *kobj,
312 struct kobj_attribute *attr, char *buf)
314 return single_hugepage_flag_show(kobj, attr, buf,
315 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
317 static ssize_t debug_cow_store(struct kobject *kobj,
318 struct kobj_attribute *attr,
319 const char *buf, size_t count)
321 return single_hugepage_flag_store(kobj, attr, buf, count,
322 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
324 static struct kobj_attribute debug_cow_attr =
325 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
326 #endif /* CONFIG_DEBUG_VM */
328 static struct attribute *hugepage_attr[] = {
331 &use_zero_page_attr.attr,
332 &hpage_pmd_size_attr.attr,
333 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
334 &shmem_enabled_attr.attr,
336 #ifdef CONFIG_DEBUG_VM
337 &debug_cow_attr.attr,
342 static const struct attribute_group hugepage_attr_group = {
343 .attrs = hugepage_attr,
346 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
350 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
351 if (unlikely(!*hugepage_kobj)) {
352 pr_err("failed to create transparent hugepage kobject\n");
356 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
358 pr_err("failed to register transparent hugepage group\n");
362 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
364 pr_err("failed to register transparent hugepage group\n");
365 goto remove_hp_group;
371 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
373 kobject_put(*hugepage_kobj);
377 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
379 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
380 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
381 kobject_put(hugepage_kobj);
384 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
389 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
392 #endif /* CONFIG_SYSFS */
394 static int __init hugepage_init(void)
397 struct kobject *hugepage_kobj;
399 if (!has_transparent_hugepage()) {
400 transparent_hugepage_flags = 0;
405 * hugepages can't be allocated by the buddy allocator
407 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
409 * we use page->mapping and page->index in second tail page
410 * as list_head: assuming THP order >= 2
412 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
414 err = hugepage_init_sysfs(&hugepage_kobj);
418 err = khugepaged_init();
422 err = register_shrinker(&huge_zero_page_shrinker);
424 goto err_hzp_shrinker;
425 err = register_shrinker(&deferred_split_shrinker);
427 goto err_split_shrinker;
430 * By default disable transparent hugepages on smaller systems,
431 * where the extra memory used could hurt more than TLB overhead
432 * is likely to save. The admin can still enable it through /sys.
434 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
435 transparent_hugepage_flags = 0;
439 err = start_stop_khugepaged();
445 unregister_shrinker(&deferred_split_shrinker);
447 unregister_shrinker(&huge_zero_page_shrinker);
449 khugepaged_destroy();
451 hugepage_exit_sysfs(hugepage_kobj);
455 subsys_initcall(hugepage_init);
457 static int __init setup_transparent_hugepage(char *str)
462 if (!strcmp(str, "always")) {
463 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
464 &transparent_hugepage_flags);
465 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
466 &transparent_hugepage_flags);
468 } else if (!strcmp(str, "madvise")) {
469 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
470 &transparent_hugepage_flags);
471 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
472 &transparent_hugepage_flags);
474 } else if (!strcmp(str, "never")) {
475 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
476 &transparent_hugepage_flags);
477 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
478 &transparent_hugepage_flags);
483 pr_warn("transparent_hugepage= cannot parse, ignored\n");
486 __setup("transparent_hugepage=", setup_transparent_hugepage);
488 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
490 if (likely(vma->vm_flags & VM_WRITE))
491 pmd = pmd_mkwrite(pmd);
495 static inline struct list_head *page_deferred_list(struct page *page)
497 /* ->lru in the tail pages is occupied by compound_head. */
498 return &page[2].deferred_list;
501 void prep_transhuge_page(struct page *page)
504 * we use page->mapping and page->indexlru in second tail page
505 * as list_head: assuming THP order >= 2
508 INIT_LIST_HEAD(page_deferred_list(page));
509 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
512 static unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
513 loff_t off, unsigned long flags, unsigned long size)
516 loff_t off_end = off + len;
517 loff_t off_align = round_up(off, size);
518 unsigned long len_pad;
520 if (off_end <= off_align || (off_end - off_align) < size)
523 len_pad = len + size;
524 if (len_pad < len || (off + len_pad) < off)
527 addr = current->mm->get_unmapped_area(filp, 0, len_pad,
528 off >> PAGE_SHIFT, flags);
529 if (IS_ERR_VALUE(addr))
532 addr += (off - addr) & (size - 1);
536 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
537 unsigned long len, unsigned long pgoff, unsigned long flags)
539 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
543 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
546 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
551 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
553 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
555 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
556 struct page *page, gfp_t gfp)
558 struct vm_area_struct *vma = vmf->vma;
559 struct mem_cgroup *memcg;
561 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
564 VM_BUG_ON_PAGE(!PageCompound(page), page);
566 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) {
568 count_vm_event(THP_FAULT_FALLBACK);
569 return VM_FAULT_FALLBACK;
572 pgtable = pte_alloc_one(vma->vm_mm);
573 if (unlikely(!pgtable)) {
578 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
580 * The memory barrier inside __SetPageUptodate makes sure that
581 * clear_huge_page writes become visible before the set_pmd_at()
584 __SetPageUptodate(page);
586 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
587 if (unlikely(!pmd_none(*vmf->pmd))) {
592 ret = check_stable_address_space(vma->vm_mm);
596 /* Deliver the page fault to userland */
597 if (userfaultfd_missing(vma)) {
600 spin_unlock(vmf->ptl);
601 mem_cgroup_cancel_charge(page, memcg, true);
603 pte_free(vma->vm_mm, pgtable);
604 ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
605 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK);
609 entry = mk_huge_pmd(page, vma->vm_page_prot);
610 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
611 page_add_new_anon_rmap(page, vma, haddr, true);
612 mem_cgroup_commit_charge(page, memcg, false, true);
613 lru_cache_add_active_or_unevictable(page, vma);
614 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
615 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
616 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
617 mm_inc_nr_ptes(vma->vm_mm);
618 spin_unlock(vmf->ptl);
619 count_vm_event(THP_FAULT_ALLOC);
620 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
625 spin_unlock(vmf->ptl);
628 pte_free(vma->vm_mm, pgtable);
629 mem_cgroup_cancel_charge(page, memcg, true);
636 * always: directly stall for all thp allocations
637 * defer: wake kswapd and fail if not immediately available
638 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
639 * fail if not immediately available
640 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
642 * never: never stall for any thp allocation
644 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
646 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
648 /* Always do synchronous compaction */
649 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
650 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
652 /* Kick kcompactd and fail quickly */
653 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
654 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
656 /* Synchronous compaction if madvised, otherwise kick kcompactd */
657 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
658 return GFP_TRANSHUGE_LIGHT |
659 (vma_madvised ? __GFP_DIRECT_RECLAIM :
660 __GFP_KSWAPD_RECLAIM);
662 /* Only do synchronous compaction if madvised */
663 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
664 return GFP_TRANSHUGE_LIGHT |
665 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
667 return GFP_TRANSHUGE_LIGHT;
670 /* Caller must hold page table lock. */
671 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
672 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
673 struct page *zero_page)
678 entry = mk_pmd(zero_page, vma->vm_page_prot);
679 entry = pmd_mkhuge(entry);
681 pgtable_trans_huge_deposit(mm, pmd, pgtable);
682 set_pmd_at(mm, haddr, pmd, entry);
687 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
689 struct vm_area_struct *vma = vmf->vma;
692 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
694 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
695 return VM_FAULT_FALLBACK;
696 if (unlikely(anon_vma_prepare(vma)))
698 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
700 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
701 !mm_forbids_zeropage(vma->vm_mm) &&
702 transparent_hugepage_use_zero_page()) {
704 struct page *zero_page;
707 pgtable = pte_alloc_one(vma->vm_mm);
708 if (unlikely(!pgtable))
710 zero_page = mm_get_huge_zero_page(vma->vm_mm);
711 if (unlikely(!zero_page)) {
712 pte_free(vma->vm_mm, pgtable);
713 count_vm_event(THP_FAULT_FALLBACK);
714 return VM_FAULT_FALLBACK;
716 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
719 if (pmd_none(*vmf->pmd)) {
720 ret = check_stable_address_space(vma->vm_mm);
722 spin_unlock(vmf->ptl);
723 } else if (userfaultfd_missing(vma)) {
724 spin_unlock(vmf->ptl);
725 ret = handle_userfault(vmf, VM_UFFD_MISSING);
726 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
728 set_huge_zero_page(pgtable, vma->vm_mm, vma,
729 haddr, vmf->pmd, zero_page);
730 spin_unlock(vmf->ptl);
734 spin_unlock(vmf->ptl);
736 pte_free(vma->vm_mm, pgtable);
739 gfp = alloc_hugepage_direct_gfpmask(vma);
740 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
741 if (unlikely(!page)) {
742 count_vm_event(THP_FAULT_FALLBACK);
743 return VM_FAULT_FALLBACK;
745 prep_transhuge_page(page);
746 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
749 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
750 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
753 struct mm_struct *mm = vma->vm_mm;
757 ptl = pmd_lock(mm, pmd);
758 if (!pmd_none(*pmd)) {
760 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
761 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
764 entry = pmd_mkyoung(*pmd);
765 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
766 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
767 update_mmu_cache_pmd(vma, addr, pmd);
773 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
774 if (pfn_t_devmap(pfn))
775 entry = pmd_mkdevmap(entry);
777 entry = pmd_mkyoung(pmd_mkdirty(entry));
778 entry = maybe_pmd_mkwrite(entry, vma);
782 pgtable_trans_huge_deposit(mm, pmd, pgtable);
787 set_pmd_at(mm, addr, pmd, entry);
788 update_mmu_cache_pmd(vma, addr, pmd);
793 pte_free(mm, pgtable);
796 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
798 unsigned long addr = vmf->address & PMD_MASK;
799 struct vm_area_struct *vma = vmf->vma;
800 pgprot_t pgprot = vma->vm_page_prot;
801 pgtable_t pgtable = NULL;
804 * If we had pmd_special, we could avoid all these restrictions,
805 * but we need to be consistent with PTEs and architectures that
806 * can't support a 'special' bit.
808 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
810 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
811 (VM_PFNMAP|VM_MIXEDMAP));
812 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
814 if (addr < vma->vm_start || addr >= vma->vm_end)
815 return VM_FAULT_SIGBUS;
817 if (arch_needs_pgtable_deposit()) {
818 pgtable = pte_alloc_one(vma->vm_mm);
823 track_pfn_insert(vma, &pgprot, pfn);
825 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
826 return VM_FAULT_NOPAGE;
828 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
830 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
831 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
833 if (likely(vma->vm_flags & VM_WRITE))
834 pud = pud_mkwrite(pud);
838 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
839 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
841 struct mm_struct *mm = vma->vm_mm;
845 ptl = pud_lock(mm, pud);
846 if (!pud_none(*pud)) {
848 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
849 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
852 entry = pud_mkyoung(*pud);
853 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
854 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
855 update_mmu_cache_pud(vma, addr, pud);
860 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
861 if (pfn_t_devmap(pfn))
862 entry = pud_mkdevmap(entry);
864 entry = pud_mkyoung(pud_mkdirty(entry));
865 entry = maybe_pud_mkwrite(entry, vma);
867 set_pud_at(mm, addr, pud, entry);
868 update_mmu_cache_pud(vma, addr, pud);
874 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
876 unsigned long addr = vmf->address & PUD_MASK;
877 struct vm_area_struct *vma = vmf->vma;
878 pgprot_t pgprot = vma->vm_page_prot;
881 * If we had pud_special, we could avoid all these restrictions,
882 * but we need to be consistent with PTEs and architectures that
883 * can't support a 'special' bit.
885 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
887 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
888 (VM_PFNMAP|VM_MIXEDMAP));
889 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
891 if (addr < vma->vm_start || addr >= vma->vm_end)
892 return VM_FAULT_SIGBUS;
894 track_pfn_insert(vma, &pgprot, pfn);
896 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
897 return VM_FAULT_NOPAGE;
899 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
900 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
902 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
903 pmd_t *pmd, int flags)
907 _pmd = pmd_mkyoung(*pmd);
908 if (flags & FOLL_WRITE)
909 _pmd = pmd_mkdirty(_pmd);
910 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
911 pmd, _pmd, flags & FOLL_WRITE))
912 update_mmu_cache_pmd(vma, addr, pmd);
915 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
916 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
918 unsigned long pfn = pmd_pfn(*pmd);
919 struct mm_struct *mm = vma->vm_mm;
922 assert_spin_locked(pmd_lockptr(mm, pmd));
925 * When we COW a devmap PMD entry, we split it into PTEs, so we should
926 * not be in this function with `flags & FOLL_COW` set.
928 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
930 if (flags & FOLL_WRITE && !pmd_write(*pmd))
933 if (pmd_present(*pmd) && pmd_devmap(*pmd))
938 if (flags & FOLL_TOUCH)
939 touch_pmd(vma, addr, pmd, flags);
942 * device mapped pages can only be returned if the
943 * caller will manage the page reference count.
945 if (!(flags & FOLL_GET))
946 return ERR_PTR(-EEXIST);
948 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
949 *pgmap = get_dev_pagemap(pfn, *pgmap);
951 return ERR_PTR(-EFAULT);
952 page = pfn_to_page(pfn);
958 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
959 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
960 struct vm_area_struct *vma)
962 spinlock_t *dst_ptl, *src_ptl;
963 struct page *src_page;
965 pgtable_t pgtable = NULL;
968 /* Skip if can be re-fill on fault */
969 if (!vma_is_anonymous(vma))
972 pgtable = pte_alloc_one(dst_mm);
973 if (unlikely(!pgtable))
976 dst_ptl = pmd_lock(dst_mm, dst_pmd);
977 src_ptl = pmd_lockptr(src_mm, src_pmd);
978 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
983 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
984 if (unlikely(is_swap_pmd(pmd))) {
985 swp_entry_t entry = pmd_to_swp_entry(pmd);
987 VM_BUG_ON(!is_pmd_migration_entry(pmd));
988 if (is_write_migration_entry(entry)) {
989 make_migration_entry_read(&entry);
990 pmd = swp_entry_to_pmd(entry);
991 if (pmd_swp_soft_dirty(*src_pmd))
992 pmd = pmd_swp_mksoft_dirty(pmd);
993 set_pmd_at(src_mm, addr, src_pmd, pmd);
995 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
996 mm_inc_nr_ptes(dst_mm);
997 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
998 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1004 if (unlikely(!pmd_trans_huge(pmd))) {
1005 pte_free(dst_mm, pgtable);
1009 * When page table lock is held, the huge zero pmd should not be
1010 * under splitting since we don't split the page itself, only pmd to
1013 if (is_huge_zero_pmd(pmd)) {
1014 struct page *zero_page;
1016 * get_huge_zero_page() will never allocate a new page here,
1017 * since we already have a zero page to copy. It just takes a
1020 zero_page = mm_get_huge_zero_page(dst_mm);
1021 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
1027 src_page = pmd_page(pmd);
1028 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1030 page_dup_rmap(src_page, true);
1031 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1032 mm_inc_nr_ptes(dst_mm);
1033 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1035 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1036 pmd = pmd_mkold(pmd_wrprotect(pmd));
1037 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1041 spin_unlock(src_ptl);
1042 spin_unlock(dst_ptl);
1047 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1048 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1049 pud_t *pud, int flags)
1053 _pud = pud_mkyoung(*pud);
1054 if (flags & FOLL_WRITE)
1055 _pud = pud_mkdirty(_pud);
1056 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1057 pud, _pud, flags & FOLL_WRITE))
1058 update_mmu_cache_pud(vma, addr, pud);
1061 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1062 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1064 unsigned long pfn = pud_pfn(*pud);
1065 struct mm_struct *mm = vma->vm_mm;
1068 assert_spin_locked(pud_lockptr(mm, pud));
1070 if (flags & FOLL_WRITE && !pud_write(*pud))
1073 if (pud_present(*pud) && pud_devmap(*pud))
1078 if (flags & FOLL_TOUCH)
1079 touch_pud(vma, addr, pud, flags);
1082 * device mapped pages can only be returned if the
1083 * caller will manage the page reference count.
1085 if (!(flags & FOLL_GET))
1086 return ERR_PTR(-EEXIST);
1088 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1089 *pgmap = get_dev_pagemap(pfn, *pgmap);
1091 return ERR_PTR(-EFAULT);
1092 page = pfn_to_page(pfn);
1098 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1099 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1100 struct vm_area_struct *vma)
1102 spinlock_t *dst_ptl, *src_ptl;
1106 dst_ptl = pud_lock(dst_mm, dst_pud);
1107 src_ptl = pud_lockptr(src_mm, src_pud);
1108 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1112 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1116 * When page table lock is held, the huge zero pud should not be
1117 * under splitting since we don't split the page itself, only pud to
1120 if (is_huge_zero_pud(pud)) {
1121 /* No huge zero pud yet */
1124 pudp_set_wrprotect(src_mm, addr, src_pud);
1125 pud = pud_mkold(pud_wrprotect(pud));
1126 set_pud_at(dst_mm, addr, dst_pud, pud);
1130 spin_unlock(src_ptl);
1131 spin_unlock(dst_ptl);
1135 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1138 unsigned long haddr;
1139 bool write = vmf->flags & FAULT_FLAG_WRITE;
1141 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1142 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1145 entry = pud_mkyoung(orig_pud);
1147 entry = pud_mkdirty(entry);
1148 haddr = vmf->address & HPAGE_PUD_MASK;
1149 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1150 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1153 spin_unlock(vmf->ptl);
1155 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1157 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1160 unsigned long haddr;
1161 bool write = vmf->flags & FAULT_FLAG_WRITE;
1163 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1164 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1167 entry = pmd_mkyoung(orig_pmd);
1169 entry = pmd_mkdirty(entry);
1170 haddr = vmf->address & HPAGE_PMD_MASK;
1171 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1172 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1175 spin_unlock(vmf->ptl);
1178 static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf,
1179 pmd_t orig_pmd, struct page *page)
1181 struct vm_area_struct *vma = vmf->vma;
1182 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1183 struct mem_cgroup *memcg;
1188 struct page **pages;
1189 struct mmu_notifier_range range;
1191 pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *),
1193 if (unlikely(!pages)) {
1194 ret |= VM_FAULT_OOM;
1198 for (i = 0; i < HPAGE_PMD_NR; i++) {
1199 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1200 vmf->address, page_to_nid(page));
1201 if (unlikely(!pages[i] ||
1202 mem_cgroup_try_charge_delay(pages[i], vma->vm_mm,
1203 GFP_KERNEL, &memcg, false))) {
1207 memcg = (void *)page_private(pages[i]);
1208 set_page_private(pages[i], 0);
1209 mem_cgroup_cancel_charge(pages[i], memcg,
1214 ret |= VM_FAULT_OOM;
1217 set_page_private(pages[i], (unsigned long)memcg);
1220 for (i = 0; i < HPAGE_PMD_NR; i++) {
1221 copy_user_highpage(pages[i], page + i,
1222 haddr + PAGE_SIZE * i, vma);
1223 __SetPageUptodate(pages[i]);
1227 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1228 haddr, haddr + HPAGE_PMD_SIZE);
1229 mmu_notifier_invalidate_range_start(&range);
1231 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1232 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1233 goto out_free_pages;
1234 VM_BUG_ON_PAGE(!PageHead(page), page);
1237 * Leave pmd empty until pte is filled note we must notify here as
1238 * concurrent CPU thread might write to new page before the call to
1239 * mmu_notifier_invalidate_range_end() happens which can lead to a
1240 * device seeing memory write in different order than CPU.
1242 * See Documentation/vm/mmu_notifier.rst
1244 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1246 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1247 pmd_populate(vma->vm_mm, &_pmd, pgtable);
1249 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1251 entry = mk_pte(pages[i], vma->vm_page_prot);
1252 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1253 memcg = (void *)page_private(pages[i]);
1254 set_page_private(pages[i], 0);
1255 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1256 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1257 lru_cache_add_active_or_unevictable(pages[i], vma);
1258 vmf->pte = pte_offset_map(&_pmd, haddr);
1259 VM_BUG_ON(!pte_none(*vmf->pte));
1260 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1261 pte_unmap(vmf->pte);
1265 smp_wmb(); /* make pte visible before pmd */
1266 pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1267 page_remove_rmap(page, true);
1268 spin_unlock(vmf->ptl);
1271 * No need to double call mmu_notifier->invalidate_range() callback as
1272 * the above pmdp_huge_clear_flush_notify() did already call it.
1274 mmu_notifier_invalidate_range_only_end(&range);
1276 ret |= VM_FAULT_WRITE;
1283 spin_unlock(vmf->ptl);
1284 mmu_notifier_invalidate_range_end(&range);
1285 for (i = 0; i < HPAGE_PMD_NR; i++) {
1286 memcg = (void *)page_private(pages[i]);
1287 set_page_private(pages[i], 0);
1288 mem_cgroup_cancel_charge(pages[i], memcg, false);
1295 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1297 struct vm_area_struct *vma = vmf->vma;
1298 struct page *page = NULL, *new_page;
1299 struct mem_cgroup *memcg;
1300 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1301 struct mmu_notifier_range range;
1302 gfp_t huge_gfp; /* for allocation and charge */
1305 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1306 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1307 if (is_huge_zero_pmd(orig_pmd))
1309 spin_lock(vmf->ptl);
1310 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1313 page = pmd_page(orig_pmd);
1314 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1316 * We can only reuse the page if nobody else maps the huge page or it's
1319 if (!trylock_page(page)) {
1321 spin_unlock(vmf->ptl);
1323 spin_lock(vmf->ptl);
1324 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1331 if (reuse_swap_page(page, NULL)) {
1333 entry = pmd_mkyoung(orig_pmd);
1334 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1335 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1336 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1337 ret |= VM_FAULT_WRITE;
1343 spin_unlock(vmf->ptl);
1345 if (__transparent_hugepage_enabled(vma) &&
1346 !transparent_hugepage_debug_cow()) {
1347 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1348 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1352 if (likely(new_page)) {
1353 prep_transhuge_page(new_page);
1356 split_huge_pmd(vma, vmf->pmd, vmf->address);
1357 ret |= VM_FAULT_FALLBACK;
1359 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1360 if (ret & VM_FAULT_OOM) {
1361 split_huge_pmd(vma, vmf->pmd, vmf->address);
1362 ret |= VM_FAULT_FALLBACK;
1366 count_vm_event(THP_FAULT_FALLBACK);
1370 if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm,
1371 huge_gfp, &memcg, true))) {
1373 split_huge_pmd(vma, vmf->pmd, vmf->address);
1376 ret |= VM_FAULT_FALLBACK;
1377 count_vm_event(THP_FAULT_FALLBACK);
1381 count_vm_event(THP_FAULT_ALLOC);
1382 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
1385 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1387 copy_user_huge_page(new_page, page, vmf->address,
1389 __SetPageUptodate(new_page);
1391 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1392 haddr, haddr + HPAGE_PMD_SIZE);
1393 mmu_notifier_invalidate_range_start(&range);
1395 spin_lock(vmf->ptl);
1398 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1399 spin_unlock(vmf->ptl);
1400 mem_cgroup_cancel_charge(new_page, memcg, true);
1405 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1406 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1407 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1408 page_add_new_anon_rmap(new_page, vma, haddr, true);
1409 mem_cgroup_commit_charge(new_page, memcg, false, true);
1410 lru_cache_add_active_or_unevictable(new_page, vma);
1411 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1412 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1414 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1416 VM_BUG_ON_PAGE(!PageHead(page), page);
1417 page_remove_rmap(page, true);
1420 ret |= VM_FAULT_WRITE;
1422 spin_unlock(vmf->ptl);
1425 * No need to double call mmu_notifier->invalidate_range() callback as
1426 * the above pmdp_huge_clear_flush_notify() did already call it.
1428 mmu_notifier_invalidate_range_only_end(&range);
1432 spin_unlock(vmf->ptl);
1437 * FOLL_FORCE can write to even unwritable pmd's, but only
1438 * after we've gone through a COW cycle and they are dirty.
1440 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1442 return pmd_write(pmd) ||
1443 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1446 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1451 struct mm_struct *mm = vma->vm_mm;
1452 struct page *page = NULL;
1454 assert_spin_locked(pmd_lockptr(mm, pmd));
1456 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1459 /* Avoid dumping huge zero page */
1460 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1461 return ERR_PTR(-EFAULT);
1463 /* Full NUMA hinting faults to serialise migration in fault paths */
1464 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1467 page = pmd_page(*pmd);
1468 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1469 if (flags & FOLL_TOUCH)
1470 touch_pmd(vma, addr, pmd, flags);
1471 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1473 * We don't mlock() pte-mapped THPs. This way we can avoid
1474 * leaking mlocked pages into non-VM_LOCKED VMAs.
1478 * In most cases the pmd is the only mapping of the page as we
1479 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1480 * writable private mappings in populate_vma_page_range().
1482 * The only scenario when we have the page shared here is if we
1483 * mlocking read-only mapping shared over fork(). We skip
1484 * mlocking such pages.
1488 * We can expect PageDoubleMap() to be stable under page lock:
1489 * for file pages we set it in page_add_file_rmap(), which
1490 * requires page to be locked.
1493 if (PageAnon(page) && compound_mapcount(page) != 1)
1495 if (PageDoubleMap(page) || !page->mapping)
1497 if (!trylock_page(page))
1500 if (page->mapping && !PageDoubleMap(page))
1501 mlock_vma_page(page);
1505 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1506 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1507 if (flags & FOLL_GET)
1514 /* NUMA hinting page fault entry point for trans huge pmds */
1515 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1517 struct vm_area_struct *vma = vmf->vma;
1518 struct anon_vma *anon_vma = NULL;
1520 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1521 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id();
1522 int target_nid, last_cpupid = -1;
1524 bool migrated = false;
1528 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1529 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1533 * If there are potential migrations, wait for completion and retry
1534 * without disrupting NUMA hinting information. Do not relock and
1535 * check_same as the page may no longer be mapped.
1537 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1538 page = pmd_page(*vmf->pmd);
1539 if (!get_page_unless_zero(page))
1541 spin_unlock(vmf->ptl);
1542 put_and_wait_on_page_locked(page);
1546 page = pmd_page(pmd);
1547 BUG_ON(is_huge_zero_page(page));
1548 page_nid = page_to_nid(page);
1549 last_cpupid = page_cpupid_last(page);
1550 count_vm_numa_event(NUMA_HINT_FAULTS);
1551 if (page_nid == this_nid) {
1552 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1553 flags |= TNF_FAULT_LOCAL;
1556 /* See similar comment in do_numa_page for explanation */
1557 if (!pmd_savedwrite(pmd))
1558 flags |= TNF_NO_GROUP;
1561 * Acquire the page lock to serialise THP migrations but avoid dropping
1562 * page_table_lock if at all possible
1564 page_locked = trylock_page(page);
1565 target_nid = mpol_misplaced(page, vma, haddr);
1566 if (target_nid == NUMA_NO_NODE) {
1567 /* If the page was locked, there are no parallel migrations */
1572 /* Migration could have started since the pmd_trans_migrating check */
1574 page_nid = NUMA_NO_NODE;
1575 if (!get_page_unless_zero(page))
1577 spin_unlock(vmf->ptl);
1578 put_and_wait_on_page_locked(page);
1583 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1584 * to serialises splits
1587 spin_unlock(vmf->ptl);
1588 anon_vma = page_lock_anon_vma_read(page);
1590 /* Confirm the PMD did not change while page_table_lock was released */
1591 spin_lock(vmf->ptl);
1592 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1595 page_nid = NUMA_NO_NODE;
1599 /* Bail if we fail to protect against THP splits for any reason */
1600 if (unlikely(!anon_vma)) {
1602 page_nid = NUMA_NO_NODE;
1607 * Since we took the NUMA fault, we must have observed the !accessible
1608 * bit. Make sure all other CPUs agree with that, to avoid them
1609 * modifying the page we're about to migrate.
1611 * Must be done under PTL such that we'll observe the relevant
1612 * inc_tlb_flush_pending().
1614 * We are not sure a pending tlb flush here is for a huge page
1615 * mapping or not. Hence use the tlb range variant
1617 if (mm_tlb_flush_pending(vma->vm_mm)) {
1618 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1620 * change_huge_pmd() released the pmd lock before
1621 * invalidating the secondary MMUs sharing the primary
1622 * MMU pagetables (with ->invalidate_range()). The
1623 * mmu_notifier_invalidate_range_end() (which
1624 * internally calls ->invalidate_range()) in
1625 * change_pmd_range() will run after us, so we can't
1626 * rely on it here and we need an explicit invalidate.
1628 mmu_notifier_invalidate_range(vma->vm_mm, haddr,
1629 haddr + HPAGE_PMD_SIZE);
1633 * Migrate the THP to the requested node, returns with page unlocked
1634 * and access rights restored.
1636 spin_unlock(vmf->ptl);
1638 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1639 vmf->pmd, pmd, vmf->address, page, target_nid);
1641 flags |= TNF_MIGRATED;
1642 page_nid = target_nid;
1644 flags |= TNF_MIGRATE_FAIL;
1648 BUG_ON(!PageLocked(page));
1649 was_writable = pmd_savedwrite(pmd);
1650 pmd = pmd_modify(pmd, vma->vm_page_prot);
1651 pmd = pmd_mkyoung(pmd);
1653 pmd = pmd_mkwrite(pmd);
1654 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1655 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1658 spin_unlock(vmf->ptl);
1662 page_unlock_anon_vma_read(anon_vma);
1664 if (page_nid != NUMA_NO_NODE)
1665 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1672 * Return true if we do MADV_FREE successfully on entire pmd page.
1673 * Otherwise, return false.
1675 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1676 pmd_t *pmd, unsigned long addr, unsigned long next)
1681 struct mm_struct *mm = tlb->mm;
1684 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1686 ptl = pmd_trans_huge_lock(pmd, vma);
1691 if (is_huge_zero_pmd(orig_pmd))
1694 if (unlikely(!pmd_present(orig_pmd))) {
1695 VM_BUG_ON(thp_migration_supported() &&
1696 !is_pmd_migration_entry(orig_pmd));
1700 page = pmd_page(orig_pmd);
1702 * If other processes are mapping this page, we couldn't discard
1703 * the page unless they all do MADV_FREE so let's skip the page.
1705 if (page_mapcount(page) != 1)
1708 if (!trylock_page(page))
1712 * If user want to discard part-pages of THP, split it so MADV_FREE
1713 * will deactivate only them.
1715 if (next - addr != HPAGE_PMD_SIZE) {
1718 split_huge_page(page);
1724 if (PageDirty(page))
1725 ClearPageDirty(page);
1728 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1729 pmdp_invalidate(vma, addr, pmd);
1730 orig_pmd = pmd_mkold(orig_pmd);
1731 orig_pmd = pmd_mkclean(orig_pmd);
1733 set_pmd_at(mm, addr, pmd, orig_pmd);
1734 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1737 mark_page_lazyfree(page);
1745 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1749 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1750 pte_free(mm, pgtable);
1754 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1755 pmd_t *pmd, unsigned long addr)
1760 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1762 ptl = __pmd_trans_huge_lock(pmd, vma);
1766 * For architectures like ppc64 we look at deposited pgtable
1767 * when calling pmdp_huge_get_and_clear. So do the
1768 * pgtable_trans_huge_withdraw after finishing pmdp related
1771 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1773 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1774 if (vma_is_dax(vma)) {
1775 if (arch_needs_pgtable_deposit())
1776 zap_deposited_table(tlb->mm, pmd);
1778 if (is_huge_zero_pmd(orig_pmd))
1779 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1780 } else if (is_huge_zero_pmd(orig_pmd)) {
1781 zap_deposited_table(tlb->mm, pmd);
1783 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1785 struct page *page = NULL;
1786 int flush_needed = 1;
1788 if (pmd_present(orig_pmd)) {
1789 page = pmd_page(orig_pmd);
1790 page_remove_rmap(page, true);
1791 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1792 VM_BUG_ON_PAGE(!PageHead(page), page);
1793 } else if (thp_migration_supported()) {
1796 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1797 entry = pmd_to_swp_entry(orig_pmd);
1798 page = pfn_to_page(swp_offset(entry));
1801 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1803 if (PageAnon(page)) {
1804 zap_deposited_table(tlb->mm, pmd);
1805 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1807 if (arch_needs_pgtable_deposit())
1808 zap_deposited_table(tlb->mm, pmd);
1809 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1814 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1819 #ifndef pmd_move_must_withdraw
1820 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1821 spinlock_t *old_pmd_ptl,
1822 struct vm_area_struct *vma)
1825 * With split pmd lock we also need to move preallocated
1826 * PTE page table if new_pmd is on different PMD page table.
1828 * We also don't deposit and withdraw tables for file pages.
1830 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1834 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1836 #ifdef CONFIG_MEM_SOFT_DIRTY
1837 if (unlikely(is_pmd_migration_entry(pmd)))
1838 pmd = pmd_swp_mksoft_dirty(pmd);
1839 else if (pmd_present(pmd))
1840 pmd = pmd_mksoft_dirty(pmd);
1845 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1846 unsigned long new_addr, unsigned long old_end,
1847 pmd_t *old_pmd, pmd_t *new_pmd)
1849 spinlock_t *old_ptl, *new_ptl;
1851 struct mm_struct *mm = vma->vm_mm;
1852 bool force_flush = false;
1854 if ((old_addr & ~HPAGE_PMD_MASK) ||
1855 (new_addr & ~HPAGE_PMD_MASK) ||
1856 old_end - old_addr < HPAGE_PMD_SIZE)
1860 * The destination pmd shouldn't be established, free_pgtables()
1861 * should have release it.
1863 if (WARN_ON(!pmd_none(*new_pmd))) {
1864 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1869 * We don't have to worry about the ordering of src and dst
1870 * ptlocks because exclusive mmap_sem prevents deadlock.
1872 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1874 new_ptl = pmd_lockptr(mm, new_pmd);
1875 if (new_ptl != old_ptl)
1876 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1877 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1878 if (pmd_present(pmd))
1880 VM_BUG_ON(!pmd_none(*new_pmd));
1882 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1884 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1885 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1887 pmd = move_soft_dirty_pmd(pmd);
1888 set_pmd_at(mm, new_addr, new_pmd, pmd);
1890 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1891 if (new_ptl != old_ptl)
1892 spin_unlock(new_ptl);
1893 spin_unlock(old_ptl);
1901 * - 0 if PMD could not be locked
1902 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1903 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1905 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1906 unsigned long addr, pgprot_t newprot, int prot_numa)
1908 struct mm_struct *mm = vma->vm_mm;
1911 bool preserve_write;
1914 ptl = __pmd_trans_huge_lock(pmd, vma);
1918 preserve_write = prot_numa && pmd_write(*pmd);
1921 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1922 if (is_swap_pmd(*pmd)) {
1923 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1925 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1926 if (is_write_migration_entry(entry)) {
1929 * A protection check is difficult so
1930 * just be safe and disable write
1932 make_migration_entry_read(&entry);
1933 newpmd = swp_entry_to_pmd(entry);
1934 if (pmd_swp_soft_dirty(*pmd))
1935 newpmd = pmd_swp_mksoft_dirty(newpmd);
1936 set_pmd_at(mm, addr, pmd, newpmd);
1943 * Avoid trapping faults against the zero page. The read-only
1944 * data is likely to be read-cached on the local CPU and
1945 * local/remote hits to the zero page are not interesting.
1947 if (prot_numa && is_huge_zero_pmd(*pmd))
1950 if (prot_numa && pmd_protnone(*pmd))
1954 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1955 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1956 * which is also under down_read(mmap_sem):
1959 * change_huge_pmd(prot_numa=1)
1960 * pmdp_huge_get_and_clear_notify()
1961 * madvise_dontneed()
1963 * pmd_trans_huge(*pmd) == 0 (without ptl)
1966 * // pmd is re-established
1968 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1969 * which may break userspace.
1971 * pmdp_invalidate() is required to make sure we don't miss
1972 * dirty/young flags set by hardware.
1974 entry = pmdp_invalidate(vma, addr, pmd);
1976 entry = pmd_modify(entry, newprot);
1978 entry = pmd_mk_savedwrite(entry);
1980 set_pmd_at(mm, addr, pmd, entry);
1981 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1988 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1990 * Note that if it returns page table lock pointer, this routine returns without
1991 * unlocking page table lock. So callers must unlock it.
1993 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1996 ptl = pmd_lock(vma->vm_mm, pmd);
1997 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
2005 * Returns true if a given pud maps a thp, false otherwise.
2007 * Note that if it returns true, this routine returns without unlocking page
2008 * table lock. So callers must unlock it.
2010 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
2014 ptl = pud_lock(vma->vm_mm, pud);
2015 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
2021 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
2022 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
2023 pud_t *pud, unsigned long addr)
2027 ptl = __pud_trans_huge_lock(pud, vma);
2031 * For architectures like ppc64 we look at deposited pgtable
2032 * when calling pudp_huge_get_and_clear. So do the
2033 * pgtable_trans_huge_withdraw after finishing pudp related
2036 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
2037 tlb_remove_pud_tlb_entry(tlb, pud, addr);
2038 if (vma_is_dax(vma)) {
2040 /* No zero page support yet */
2042 /* No support for anonymous PUD pages yet */
2048 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2049 unsigned long haddr)
2051 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2052 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2053 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2054 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2056 count_vm_event(THP_SPLIT_PUD);
2058 pudp_huge_clear_flush_notify(vma, haddr, pud);
2061 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2062 unsigned long address)
2065 struct mmu_notifier_range range;
2067 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2068 address & HPAGE_PUD_MASK,
2069 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
2070 mmu_notifier_invalidate_range_start(&range);
2071 ptl = pud_lock(vma->vm_mm, pud);
2072 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2074 __split_huge_pud_locked(vma, pud, range.start);
2079 * No need to double call mmu_notifier->invalidate_range() callback as
2080 * the above pudp_huge_clear_flush_notify() did already call it.
2082 mmu_notifier_invalidate_range_only_end(&range);
2084 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2086 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2087 unsigned long haddr, pmd_t *pmd)
2089 struct mm_struct *mm = vma->vm_mm;
2095 * Leave pmd empty until pte is filled note that it is fine to delay
2096 * notification until mmu_notifier_invalidate_range_end() as we are
2097 * replacing a zero pmd write protected page with a zero pte write
2100 * See Documentation/vm/mmu_notifier.rst
2102 pmdp_huge_clear_flush(vma, haddr, pmd);
2104 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2105 pmd_populate(mm, &_pmd, pgtable);
2107 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2109 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2110 entry = pte_mkspecial(entry);
2111 pte = pte_offset_map(&_pmd, haddr);
2112 VM_BUG_ON(!pte_none(*pte));
2113 set_pte_at(mm, haddr, pte, entry);
2116 smp_wmb(); /* make pte visible before pmd */
2117 pmd_populate(mm, pmd, pgtable);
2120 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2121 unsigned long haddr, bool freeze)
2123 struct mm_struct *mm = vma->vm_mm;
2126 pmd_t old_pmd, _pmd;
2127 bool young, write, soft_dirty, pmd_migration = false;
2131 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2132 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2133 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2134 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2135 && !pmd_devmap(*pmd));
2137 count_vm_event(THP_SPLIT_PMD);
2139 if (!vma_is_anonymous(vma)) {
2140 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2142 * We are going to unmap this huge page. So
2143 * just go ahead and zap it
2145 if (arch_needs_pgtable_deposit())
2146 zap_deposited_table(mm, pmd);
2147 if (vma_is_dax(vma))
2149 page = pmd_page(_pmd);
2150 if (!PageDirty(page) && pmd_dirty(_pmd))
2151 set_page_dirty(page);
2152 if (!PageReferenced(page) && pmd_young(_pmd))
2153 SetPageReferenced(page);
2154 page_remove_rmap(page, true);
2156 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2158 } else if (is_huge_zero_pmd(*pmd)) {
2160 * FIXME: Do we want to invalidate secondary mmu by calling
2161 * mmu_notifier_invalidate_range() see comments below inside
2162 * __split_huge_pmd() ?
2164 * We are going from a zero huge page write protected to zero
2165 * small page also write protected so it does not seems useful
2166 * to invalidate secondary mmu at this time.
2168 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2172 * Up to this point the pmd is present and huge and userland has the
2173 * whole access to the hugepage during the split (which happens in
2174 * place). If we overwrite the pmd with the not-huge version pointing
2175 * to the pte here (which of course we could if all CPUs were bug
2176 * free), userland could trigger a small page size TLB miss on the
2177 * small sized TLB while the hugepage TLB entry is still established in
2178 * the huge TLB. Some CPU doesn't like that.
2179 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2180 * 383 on page 93. Intel should be safe but is also warns that it's
2181 * only safe if the permission and cache attributes of the two entries
2182 * loaded in the two TLB is identical (which should be the case here).
2183 * But it is generally safer to never allow small and huge TLB entries
2184 * for the same virtual address to be loaded simultaneously. So instead
2185 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2186 * current pmd notpresent (atomically because here the pmd_trans_huge
2187 * must remain set at all times on the pmd until the split is complete
2188 * for this pmd), then we flush the SMP TLB and finally we write the
2189 * non-huge version of the pmd entry with pmd_populate.
2191 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2193 pmd_migration = is_pmd_migration_entry(old_pmd);
2194 if (unlikely(pmd_migration)) {
2197 entry = pmd_to_swp_entry(old_pmd);
2198 page = pfn_to_page(swp_offset(entry));
2199 write = is_write_migration_entry(entry);
2201 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2203 page = pmd_page(old_pmd);
2204 if (pmd_dirty(old_pmd))
2206 write = pmd_write(old_pmd);
2207 young = pmd_young(old_pmd);
2208 soft_dirty = pmd_soft_dirty(old_pmd);
2210 VM_BUG_ON_PAGE(!page_count(page), page);
2211 page_ref_add(page, HPAGE_PMD_NR - 1);
2214 * Withdraw the table only after we mark the pmd entry invalid.
2215 * This's critical for some architectures (Power).
2217 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2218 pmd_populate(mm, &_pmd, pgtable);
2220 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2223 * Note that NUMA hinting access restrictions are not
2224 * transferred to avoid any possibility of altering
2225 * permissions across VMAs.
2227 if (freeze || pmd_migration) {
2228 swp_entry_t swp_entry;
2229 swp_entry = make_migration_entry(page + i, write);
2230 entry = swp_entry_to_pte(swp_entry);
2232 entry = pte_swp_mksoft_dirty(entry);
2234 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2235 entry = maybe_mkwrite(entry, vma);
2237 entry = pte_wrprotect(entry);
2239 entry = pte_mkold(entry);
2241 entry = pte_mksoft_dirty(entry);
2243 pte = pte_offset_map(&_pmd, addr);
2244 BUG_ON(!pte_none(*pte));
2245 set_pte_at(mm, addr, pte, entry);
2246 atomic_inc(&page[i]._mapcount);
2251 * Set PG_double_map before dropping compound_mapcount to avoid
2252 * false-negative page_mapped().
2254 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2255 for (i = 0; i < HPAGE_PMD_NR; i++)
2256 atomic_inc(&page[i]._mapcount);
2259 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2260 /* Last compound_mapcount is gone. */
2261 __dec_node_page_state(page, NR_ANON_THPS);
2262 if (TestClearPageDoubleMap(page)) {
2263 /* No need in mapcount reference anymore */
2264 for (i = 0; i < HPAGE_PMD_NR; i++)
2265 atomic_dec(&page[i]._mapcount);
2269 smp_wmb(); /* make pte visible before pmd */
2270 pmd_populate(mm, pmd, pgtable);
2273 for (i = 0; i < HPAGE_PMD_NR; i++) {
2274 page_remove_rmap(page + i, false);
2280 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2281 unsigned long address, bool freeze, struct page *page)
2284 struct mmu_notifier_range range;
2286 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2287 address & HPAGE_PMD_MASK,
2288 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2289 mmu_notifier_invalidate_range_start(&range);
2290 ptl = pmd_lock(vma->vm_mm, pmd);
2293 * If caller asks to setup a migration entries, we need a page to check
2294 * pmd against. Otherwise we can end up replacing wrong page.
2296 VM_BUG_ON(freeze && !page);
2297 if (page && page != pmd_page(*pmd))
2300 if (pmd_trans_huge(*pmd)) {
2301 page = pmd_page(*pmd);
2302 if (PageMlocked(page))
2303 clear_page_mlock(page);
2304 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2306 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2310 * No need to double call mmu_notifier->invalidate_range() callback.
2311 * They are 3 cases to consider inside __split_huge_pmd_locked():
2312 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2313 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2314 * fault will trigger a flush_notify before pointing to a new page
2315 * (it is fine if the secondary mmu keeps pointing to the old zero
2316 * page in the meantime)
2317 * 3) Split a huge pmd into pte pointing to the same page. No need
2318 * to invalidate secondary tlb entry they are all still valid.
2319 * any further changes to individual pte will notify. So no need
2320 * to call mmu_notifier->invalidate_range()
2322 mmu_notifier_invalidate_range_only_end(&range);
2325 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2326 bool freeze, struct page *page)
2333 pgd = pgd_offset(vma->vm_mm, address);
2334 if (!pgd_present(*pgd))
2337 p4d = p4d_offset(pgd, address);
2338 if (!p4d_present(*p4d))
2341 pud = pud_offset(p4d, address);
2342 if (!pud_present(*pud))
2345 pmd = pmd_offset(pud, address);
2347 __split_huge_pmd(vma, pmd, address, freeze, page);
2350 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2351 unsigned long start,
2356 * If the new start address isn't hpage aligned and it could
2357 * previously contain an hugepage: check if we need to split
2360 if (start & ~HPAGE_PMD_MASK &&
2361 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2362 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2363 split_huge_pmd_address(vma, start, false, NULL);
2366 * If the new end address isn't hpage aligned and it could
2367 * previously contain an hugepage: check if we need to split
2370 if (end & ~HPAGE_PMD_MASK &&
2371 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2372 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2373 split_huge_pmd_address(vma, end, false, NULL);
2376 * If we're also updating the vma->vm_next->vm_start, if the new
2377 * vm_next->vm_start isn't page aligned and it could previously
2378 * contain an hugepage: check if we need to split an huge pmd.
2380 if (adjust_next > 0) {
2381 struct vm_area_struct *next = vma->vm_next;
2382 unsigned long nstart = next->vm_start;
2383 nstart += adjust_next << PAGE_SHIFT;
2384 if (nstart & ~HPAGE_PMD_MASK &&
2385 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2386 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2387 split_huge_pmd_address(next, nstart, false, NULL);
2391 static void unmap_page(struct page *page)
2393 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2394 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2397 VM_BUG_ON_PAGE(!PageHead(page), page);
2400 ttu_flags |= TTU_SPLIT_FREEZE;
2402 unmap_success = try_to_unmap(page, ttu_flags);
2403 VM_BUG_ON_PAGE(!unmap_success, page);
2406 static void remap_page(struct page *page)
2409 if (PageTransHuge(page)) {
2410 remove_migration_ptes(page, page, true);
2412 for (i = 0; i < HPAGE_PMD_NR; i++)
2413 remove_migration_ptes(page + i, page + i, true);
2417 static void __split_huge_page_tail(struct page *head, int tail,
2418 struct lruvec *lruvec, struct list_head *list)
2420 struct page *page_tail = head + tail;
2422 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2425 * Clone page flags before unfreezing refcount.
2427 * After successful get_page_unless_zero() might follow flags change,
2428 * for exmaple lock_page() which set PG_waiters.
2430 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2431 page_tail->flags |= (head->flags &
2432 ((1L << PG_referenced) |
2433 (1L << PG_swapbacked) |
2434 (1L << PG_swapcache) |
2435 (1L << PG_mlocked) |
2436 (1L << PG_uptodate) |
2438 (1L << PG_workingset) |
2440 (1L << PG_unevictable) |
2443 /* ->mapping in first tail page is compound_mapcount */
2444 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2446 page_tail->mapping = head->mapping;
2447 page_tail->index = head->index + tail;
2449 /* Page flags must be visible before we make the page non-compound. */
2453 * Clear PageTail before unfreezing page refcount.
2455 * After successful get_page_unless_zero() might follow put_page()
2456 * which needs correct compound_head().
2458 clear_compound_head(page_tail);
2460 /* Finally unfreeze refcount. Additional reference from page cache. */
2461 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2462 PageSwapCache(head)));
2464 if (page_is_young(head))
2465 set_page_young(page_tail);
2466 if (page_is_idle(head))
2467 set_page_idle(page_tail);
2469 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2472 * always add to the tail because some iterators expect new
2473 * pages to show after the currently processed elements - e.g.
2476 lru_add_page_tail(head, page_tail, lruvec, list);
2479 static void __split_huge_page(struct page *page, struct list_head *list,
2480 pgoff_t end, unsigned long flags)
2482 struct page *head = compound_head(page);
2483 pg_data_t *pgdat = page_pgdat(head);
2484 struct lruvec *lruvec;
2487 lruvec = mem_cgroup_page_lruvec(head, pgdat);
2489 /* complete memcg works before add pages to LRU */
2490 mem_cgroup_split_huge_fixup(head);
2492 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2493 __split_huge_page_tail(head, i, lruvec, list);
2494 /* Some pages can be beyond i_size: drop them from page cache */
2495 if (head[i].index >= end) {
2496 ClearPageDirty(head + i);
2497 __delete_from_page_cache(head + i, NULL);
2498 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2499 shmem_uncharge(head->mapping->host, 1);
2501 } else if (!PageAnon(page)) {
2502 __xa_store(&head->mapping->i_pages, head[i].index,
2507 ClearPageCompound(head);
2508 /* See comment in __split_huge_page_tail() */
2509 if (PageAnon(head)) {
2510 /* Additional pin to swap cache */
2511 if (PageSwapCache(head))
2512 page_ref_add(head, 2);
2516 /* Additional pin to page cache */
2517 page_ref_add(head, 2);
2518 xa_unlock(&head->mapping->i_pages);
2521 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
2525 for (i = 0; i < HPAGE_PMD_NR; i++) {
2526 struct page *subpage = head + i;
2527 if (subpage == page)
2529 unlock_page(subpage);
2532 * Subpages may be freed if there wasn't any mapping
2533 * like if add_to_swap() is running on a lru page that
2534 * had its mapping zapped. And freeing these pages
2535 * requires taking the lru_lock so we do the put_page
2536 * of the tail pages after the split is complete.
2542 int total_mapcount(struct page *page)
2544 int i, compound, ret;
2546 VM_BUG_ON_PAGE(PageTail(page), page);
2548 if (likely(!PageCompound(page)))
2549 return atomic_read(&page->_mapcount) + 1;
2551 compound = compound_mapcount(page);
2555 for (i = 0; i < HPAGE_PMD_NR; i++)
2556 ret += atomic_read(&page[i]._mapcount) + 1;
2557 /* File pages has compound_mapcount included in _mapcount */
2558 if (!PageAnon(page))
2559 return ret - compound * HPAGE_PMD_NR;
2560 if (PageDoubleMap(page))
2561 ret -= HPAGE_PMD_NR;
2566 * This calculates accurately how many mappings a transparent hugepage
2567 * has (unlike page_mapcount() which isn't fully accurate). This full
2568 * accuracy is primarily needed to know if copy-on-write faults can
2569 * reuse the page and change the mapping to read-write instead of
2570 * copying them. At the same time this returns the total_mapcount too.
2572 * The function returns the highest mapcount any one of the subpages
2573 * has. If the return value is one, even if different processes are
2574 * mapping different subpages of the transparent hugepage, they can
2575 * all reuse it, because each process is reusing a different subpage.
2577 * The total_mapcount is instead counting all virtual mappings of the
2578 * subpages. If the total_mapcount is equal to "one", it tells the
2579 * caller all mappings belong to the same "mm" and in turn the
2580 * anon_vma of the transparent hugepage can become the vma->anon_vma
2581 * local one as no other process may be mapping any of the subpages.
2583 * It would be more accurate to replace page_mapcount() with
2584 * page_trans_huge_mapcount(), however we only use
2585 * page_trans_huge_mapcount() in the copy-on-write faults where we
2586 * need full accuracy to avoid breaking page pinning, because
2587 * page_trans_huge_mapcount() is slower than page_mapcount().
2589 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2591 int i, ret, _total_mapcount, mapcount;
2593 /* hugetlbfs shouldn't call it */
2594 VM_BUG_ON_PAGE(PageHuge(page), page);
2596 if (likely(!PageTransCompound(page))) {
2597 mapcount = atomic_read(&page->_mapcount) + 1;
2599 *total_mapcount = mapcount;
2603 page = compound_head(page);
2605 _total_mapcount = ret = 0;
2606 for (i = 0; i < HPAGE_PMD_NR; i++) {
2607 mapcount = atomic_read(&page[i]._mapcount) + 1;
2608 ret = max(ret, mapcount);
2609 _total_mapcount += mapcount;
2611 if (PageDoubleMap(page)) {
2613 _total_mapcount -= HPAGE_PMD_NR;
2615 mapcount = compound_mapcount(page);
2617 _total_mapcount += mapcount;
2619 *total_mapcount = _total_mapcount;
2623 /* Racy check whether the huge page can be split */
2624 bool can_split_huge_page(struct page *page, int *pextra_pins)
2628 /* Additional pins from page cache */
2630 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2632 extra_pins = HPAGE_PMD_NR;
2634 *pextra_pins = extra_pins;
2635 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2639 * This function splits huge page into normal pages. @page can point to any
2640 * subpage of huge page to split. Split doesn't change the position of @page.
2642 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2643 * The huge page must be locked.
2645 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2647 * Both head page and tail pages will inherit mapping, flags, and so on from
2650 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2651 * they are not mapped.
2653 * Returns 0 if the hugepage is split successfully.
2654 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2657 int split_huge_page_to_list(struct page *page, struct list_head *list)
2659 struct page *head = compound_head(page);
2660 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2661 struct anon_vma *anon_vma = NULL;
2662 struct address_space *mapping = NULL;
2663 int count, mapcount, extra_pins, ret;
2665 unsigned long flags;
2668 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2669 VM_BUG_ON_PAGE(!PageLocked(page), page);
2670 VM_BUG_ON_PAGE(!PageCompound(page), page);
2672 if (PageWriteback(page))
2675 if (PageAnon(head)) {
2677 * The caller does not necessarily hold an mmap_sem that would
2678 * prevent the anon_vma disappearing so we first we take a
2679 * reference to it and then lock the anon_vma for write. This
2680 * is similar to page_lock_anon_vma_read except the write lock
2681 * is taken to serialise against parallel split or collapse
2684 anon_vma = page_get_anon_vma(head);
2691 anon_vma_lock_write(anon_vma);
2693 mapping = head->mapping;
2702 i_mmap_lock_read(mapping);
2705 *__split_huge_page() may need to trim off pages beyond EOF:
2706 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2707 * which cannot be nested inside the page tree lock. So note
2708 * end now: i_size itself may be changed at any moment, but
2709 * head page lock is good enough to serialize the trimming.
2711 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2715 * Racy check if we can split the page, before unmap_page() will
2718 if (!can_split_huge_page(head, &extra_pins)) {
2723 mlocked = PageMlocked(page);
2725 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2727 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2731 /* prevent PageLRU to go away from under us, and freeze lru stats */
2732 spin_lock_irqsave(&pgdata->lru_lock, flags);
2735 XA_STATE(xas, &mapping->i_pages, page_index(head));
2738 * Check if the head page is present in page cache.
2739 * We assume all tail are present too, if head is there.
2741 xa_lock(&mapping->i_pages);
2742 if (xas_load(&xas) != head)
2746 /* Prevent deferred_split_scan() touching ->_refcount */
2747 spin_lock(&pgdata->split_queue_lock);
2748 count = page_count(head);
2749 mapcount = total_mapcount(head);
2750 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2751 if (!list_empty(page_deferred_list(head))) {
2752 pgdata->split_queue_len--;
2753 list_del(page_deferred_list(head));
2756 __dec_node_page_state(page, NR_SHMEM_THPS);
2757 spin_unlock(&pgdata->split_queue_lock);
2758 __split_huge_page(page, list, end, flags);
2759 if (PageSwapCache(head)) {
2760 swp_entry_t entry = { .val = page_private(head) };
2762 ret = split_swap_cluster(entry);
2766 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2767 pr_alert("total_mapcount: %u, page_count(): %u\n",
2770 dump_page(head, NULL);
2771 dump_page(page, "total_mapcount(head) > 0");
2774 spin_unlock(&pgdata->split_queue_lock);
2776 xa_unlock(&mapping->i_pages);
2777 spin_unlock_irqrestore(&pgdata->lru_lock, flags);
2784 anon_vma_unlock_write(anon_vma);
2785 put_anon_vma(anon_vma);
2788 i_mmap_unlock_read(mapping);
2790 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2794 void free_transhuge_page(struct page *page)
2796 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2797 unsigned long flags;
2799 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2800 if (!list_empty(page_deferred_list(page))) {
2801 pgdata->split_queue_len--;
2802 list_del(page_deferred_list(page));
2804 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2805 free_compound_page(page);
2808 void deferred_split_huge_page(struct page *page)
2810 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2811 unsigned long flags;
2813 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2815 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2816 if (list_empty(page_deferred_list(page))) {
2817 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2818 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2819 pgdata->split_queue_len++;
2821 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2824 static unsigned long deferred_split_count(struct shrinker *shrink,
2825 struct shrink_control *sc)
2827 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2828 return READ_ONCE(pgdata->split_queue_len);
2831 static unsigned long deferred_split_scan(struct shrinker *shrink,
2832 struct shrink_control *sc)
2834 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2835 unsigned long flags;
2836 LIST_HEAD(list), *pos, *next;
2840 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2841 /* Take pin on all head pages to avoid freeing them under us */
2842 list_for_each_safe(pos, next, &pgdata->split_queue) {
2843 page = list_entry((void *)pos, struct page, mapping);
2844 page = compound_head(page);
2845 if (get_page_unless_zero(page)) {
2846 list_move(page_deferred_list(page), &list);
2848 /* We lost race with put_compound_page() */
2849 list_del_init(page_deferred_list(page));
2850 pgdata->split_queue_len--;
2852 if (!--sc->nr_to_scan)
2855 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2857 list_for_each_safe(pos, next, &list) {
2858 page = list_entry((void *)pos, struct page, mapping);
2859 if (!trylock_page(page))
2861 /* split_huge_page() removes page from list on success */
2862 if (!split_huge_page(page))
2869 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2870 list_splice_tail(&list, &pgdata->split_queue);
2871 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2874 * Stop shrinker if we didn't split any page, but the queue is empty.
2875 * This can happen if pages were freed under us.
2877 if (!split && list_empty(&pgdata->split_queue))
2882 static struct shrinker deferred_split_shrinker = {
2883 .count_objects = deferred_split_count,
2884 .scan_objects = deferred_split_scan,
2885 .seeks = DEFAULT_SEEKS,
2886 .flags = SHRINKER_NUMA_AWARE,
2889 #ifdef CONFIG_DEBUG_FS
2890 static int split_huge_pages_set(void *data, u64 val)
2894 unsigned long pfn, max_zone_pfn;
2895 unsigned long total = 0, split = 0;
2900 for_each_populated_zone(zone) {
2901 max_zone_pfn = zone_end_pfn(zone);
2902 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2903 if (!pfn_valid(pfn))
2906 page = pfn_to_page(pfn);
2907 if (!get_page_unless_zero(page))
2910 if (zone != page_zone(page))
2913 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2918 if (!split_huge_page(page))
2926 pr_info("%lu of %lu THP split\n", split, total);
2930 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2933 static int __init split_huge_pages_debugfs(void)
2935 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2936 &split_huge_pages_fops);
2939 late_initcall(split_huge_pages_debugfs);
2942 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2943 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2946 struct vm_area_struct *vma = pvmw->vma;
2947 struct mm_struct *mm = vma->vm_mm;
2948 unsigned long address = pvmw->address;
2953 if (!(pvmw->pmd && !pvmw->pte))
2956 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2957 pmdval = *pvmw->pmd;
2958 pmdp_invalidate(vma, address, pvmw->pmd);
2959 if (pmd_dirty(pmdval))
2960 set_page_dirty(page);
2961 entry = make_migration_entry(page, pmd_write(pmdval));
2962 pmdswp = swp_entry_to_pmd(entry);
2963 if (pmd_soft_dirty(pmdval))
2964 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2965 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2966 page_remove_rmap(page, true);
2970 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2972 struct vm_area_struct *vma = pvmw->vma;
2973 struct mm_struct *mm = vma->vm_mm;
2974 unsigned long address = pvmw->address;
2975 unsigned long mmun_start = address & HPAGE_PMD_MASK;
2979 if (!(pvmw->pmd && !pvmw->pte))
2982 entry = pmd_to_swp_entry(*pvmw->pmd);
2984 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2985 if (pmd_swp_soft_dirty(*pvmw->pmd))
2986 pmde = pmd_mksoft_dirty(pmde);
2987 if (is_write_migration_entry(entry))
2988 pmde = maybe_pmd_mkwrite(pmde, vma);
2990 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2992 page_add_anon_rmap(new, vma, mmun_start, true);
2994 page_add_file_rmap(new, true);
2995 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2996 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
2997 mlock_vma_page(new);
2998 update_mmu_cache_pmd(vma, address, pvmw->pmd);