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>
41 #include <asm/pgalloc.h>
45 #define CREATE_TRACE_POINTS
46 #include <trace/events/thp.h>
49 * By default, transparent hugepage support is disabled in order to avoid
50 * risking an increased memory footprint for applications that are not
51 * guaranteed to benefit from it. When transparent hugepage support is
52 * enabled, it is for all mappings, and khugepaged scans all mappings.
53 * Defrag is invoked by khugepaged hugepage allocations and by page faults
54 * for all hugepage allocations.
56 unsigned long transparent_hugepage_flags __read_mostly
=
57 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
58 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
60 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
61 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
63 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
)|
64 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
)|
65 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
67 static struct shrinker deferred_split_shrinker
;
69 static atomic_t huge_zero_refcount
;
70 struct page
*huge_zero_page __read_mostly
;
71 unsigned long huge_zero_pfn __read_mostly
= ~0UL;
73 bool hugepage_vma_check(struct vm_area_struct
*vma
,
74 unsigned long vm_flags
,
75 bool smaps
, bool in_pf
)
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
);
124 if (!hugepage_flags_enabled())
127 /* THP settings require madvise. */
128 if (!(vm_flags
& VM_HUGEPAGE
) && !hugepage_flags_always())
131 /* Only regular file is valid */
132 if (!in_pf
&& file_thp_enabled(vma
))
135 if (!vma_is_anonymous(vma
))
138 if (vma_is_temporary_stack(vma
))
142 * THPeligible bit of smaps should show 1 for proper VMAs even
143 * though anon_vma is not initialized yet.
145 * Allow page fault since anon_vma may be not initialized until
146 * the first page fault.
149 return (smaps
|| in_pf
);
154 static bool get_huge_zero_page(void)
156 struct page
*zero_page
;
158 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
161 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
164 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
167 count_vm_event(THP_ZERO_PAGE_ALLOC
);
169 if (cmpxchg(&huge_zero_page
, NULL
, zero_page
)) {
171 __free_pages(zero_page
, compound_order(zero_page
));
174 WRITE_ONCE(huge_zero_pfn
, page_to_pfn(zero_page
));
176 /* We take additional reference here. It will be put back by shrinker */
177 atomic_set(&huge_zero_refcount
, 2);
182 static void put_huge_zero_page(void)
185 * Counter should never go to zero here. Only shrinker can put
188 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
191 struct page
*mm_get_huge_zero_page(struct mm_struct
*mm
)
193 if (test_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
194 return READ_ONCE(huge_zero_page
);
196 if (!get_huge_zero_page())
199 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
200 put_huge_zero_page();
202 return READ_ONCE(huge_zero_page
);
205 void mm_put_huge_zero_page(struct mm_struct
*mm
)
207 if (test_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
208 put_huge_zero_page();
211 static unsigned long shrink_huge_zero_page_count(struct shrinker
*shrink
,
212 struct shrink_control
*sc
)
214 /* we can free zero page only if last reference remains */
215 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
218 static unsigned long shrink_huge_zero_page_scan(struct shrinker
*shrink
,
219 struct shrink_control
*sc
)
221 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
222 struct page
*zero_page
= xchg(&huge_zero_page
, NULL
);
223 BUG_ON(zero_page
== NULL
);
224 WRITE_ONCE(huge_zero_pfn
, ~0UL);
225 __free_pages(zero_page
, compound_order(zero_page
));
232 static struct shrinker huge_zero_page_shrinker
= {
233 .count_objects
= shrink_huge_zero_page_count
,
234 .scan_objects
= shrink_huge_zero_page_scan
,
235 .seeks
= DEFAULT_SEEKS
,
239 static ssize_t
enabled_show(struct kobject
*kobj
,
240 struct kobj_attribute
*attr
, char *buf
)
244 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
))
245 output
= "[always] madvise never";
246 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
247 &transparent_hugepage_flags
))
248 output
= "always [madvise] never";
250 output
= "always madvise [never]";
252 return sysfs_emit(buf
, "%s\n", output
);
255 static ssize_t
enabled_store(struct kobject
*kobj
,
256 struct kobj_attribute
*attr
,
257 const char *buf
, size_t count
)
261 if (sysfs_streq(buf
, "always")) {
262 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
263 set_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
264 } else if (sysfs_streq(buf
, "madvise")) {
265 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
266 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
267 } else if (sysfs_streq(buf
, "never")) {
268 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
269 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
274 int err
= start_stop_khugepaged();
281 static struct kobj_attribute enabled_attr
= __ATTR_RW(enabled
);
283 ssize_t
single_hugepage_flag_show(struct kobject
*kobj
,
284 struct kobj_attribute
*attr
, char *buf
,
285 enum transparent_hugepage_flag flag
)
287 return sysfs_emit(buf
, "%d\n",
288 !!test_bit(flag
, &transparent_hugepage_flags
));
291 ssize_t
single_hugepage_flag_store(struct kobject
*kobj
,
292 struct kobj_attribute
*attr
,
293 const char *buf
, size_t count
,
294 enum transparent_hugepage_flag flag
)
299 ret
= kstrtoul(buf
, 10, &value
);
306 set_bit(flag
, &transparent_hugepage_flags
);
308 clear_bit(flag
, &transparent_hugepage_flags
);
313 static ssize_t
defrag_show(struct kobject
*kobj
,
314 struct kobj_attribute
*attr
, char *buf
)
318 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
,
319 &transparent_hugepage_flags
))
320 output
= "[always] defer defer+madvise madvise never";
321 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
,
322 &transparent_hugepage_flags
))
323 output
= "always [defer] defer+madvise madvise never";
324 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
,
325 &transparent_hugepage_flags
))
326 output
= "always defer [defer+madvise] madvise never";
327 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
,
328 &transparent_hugepage_flags
))
329 output
= "always defer defer+madvise [madvise] never";
331 output
= "always defer defer+madvise madvise [never]";
333 return sysfs_emit(buf
, "%s\n", output
);
336 static ssize_t
defrag_store(struct kobject
*kobj
,
337 struct kobj_attribute
*attr
,
338 const char *buf
, size_t count
)
340 if (sysfs_streq(buf
, "always")) {
341 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
342 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
343 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
344 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
345 } else if (sysfs_streq(buf
, "defer+madvise")) {
346 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
347 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
348 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
349 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
350 } else if (sysfs_streq(buf
, "defer")) {
351 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
352 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
353 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
354 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
355 } else if (sysfs_streq(buf
, "madvise")) {
356 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
357 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
358 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
359 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
360 } else if (sysfs_streq(buf
, "never")) {
361 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
362 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
363 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
364 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
370 static struct kobj_attribute defrag_attr
= __ATTR_RW(defrag
);
372 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
373 struct kobj_attribute
*attr
, char *buf
)
375 return single_hugepage_flag_show(kobj
, attr
, buf
,
376 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
378 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
379 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
381 return single_hugepage_flag_store(kobj
, attr
, buf
, count
,
382 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
384 static struct kobj_attribute use_zero_page_attr
= __ATTR_RW(use_zero_page
);
386 static ssize_t
hpage_pmd_size_show(struct kobject
*kobj
,
387 struct kobj_attribute
*attr
, char *buf
)
389 return sysfs_emit(buf
, "%lu\n", HPAGE_PMD_SIZE
);
391 static struct kobj_attribute hpage_pmd_size_attr
=
392 __ATTR_RO(hpage_pmd_size
);
394 static struct attribute
*hugepage_attr
[] = {
397 &use_zero_page_attr
.attr
,
398 &hpage_pmd_size_attr
.attr
,
400 &shmem_enabled_attr
.attr
,
405 static const struct attribute_group hugepage_attr_group
= {
406 .attrs
= hugepage_attr
,
409 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
413 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
414 if (unlikely(!*hugepage_kobj
)) {
415 pr_err("failed to create transparent hugepage kobject\n");
419 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
421 pr_err("failed to register transparent hugepage group\n");
425 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
427 pr_err("failed to register transparent hugepage group\n");
428 goto remove_hp_group
;
434 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
436 kobject_put(*hugepage_kobj
);
440 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
442 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
443 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
444 kobject_put(hugepage_kobj
);
447 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
452 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
455 #endif /* CONFIG_SYSFS */
457 static int __init
hugepage_init(void)
460 struct kobject
*hugepage_kobj
;
462 if (!has_transparent_hugepage()) {
464 * Hardware doesn't support hugepages, hence disable
467 transparent_hugepage_flags
= 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX
;
472 * hugepages can't be allocated by the buddy allocator
474 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
>= MAX_ORDER
);
476 * we use page->mapping and page->index in second tail page
477 * as list_head: assuming THP order >= 2
479 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
< 2);
481 err
= hugepage_init_sysfs(&hugepage_kobj
);
485 err
= khugepaged_init();
489 err
= register_shrinker(&huge_zero_page_shrinker
, "thp-zero");
491 goto err_hzp_shrinker
;
492 err
= register_shrinker(&deferred_split_shrinker
, "thp-deferred_split");
494 goto err_split_shrinker
;
497 * By default disable transparent hugepages on smaller systems,
498 * where the extra memory used could hurt more than TLB overhead
499 * is likely to save. The admin can still enable it through /sys.
501 if (totalram_pages() < (512 << (20 - PAGE_SHIFT
))) {
502 transparent_hugepage_flags
= 0;
506 err
= start_stop_khugepaged();
512 unregister_shrinker(&deferred_split_shrinker
);
514 unregister_shrinker(&huge_zero_page_shrinker
);
516 khugepaged_destroy();
518 hugepage_exit_sysfs(hugepage_kobj
);
522 subsys_initcall(hugepage_init
);
524 static int __init
setup_transparent_hugepage(char *str
)
529 if (!strcmp(str
, "always")) {
530 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
531 &transparent_hugepage_flags
);
532 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
533 &transparent_hugepage_flags
);
535 } else if (!strcmp(str
, "madvise")) {
536 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
537 &transparent_hugepage_flags
);
538 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
539 &transparent_hugepage_flags
);
541 } else if (!strcmp(str
, "never")) {
542 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
543 &transparent_hugepage_flags
);
544 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
545 &transparent_hugepage_flags
);
550 pr_warn("transparent_hugepage= cannot parse, ignored\n");
553 __setup("transparent_hugepage=", setup_transparent_hugepage
);
555 pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
557 if (likely(vma
->vm_flags
& VM_WRITE
))
558 pmd
= pmd_mkwrite(pmd
);
563 static inline struct deferred_split
*get_deferred_split_queue(struct page
*page
)
565 struct mem_cgroup
*memcg
= page_memcg(compound_head(page
));
566 struct pglist_data
*pgdat
= NODE_DATA(page_to_nid(page
));
569 return &memcg
->deferred_split_queue
;
571 return &pgdat
->deferred_split_queue
;
574 static inline struct deferred_split
*get_deferred_split_queue(struct page
*page
)
576 struct pglist_data
*pgdat
= NODE_DATA(page_to_nid(page
));
578 return &pgdat
->deferred_split_queue
;
582 void prep_transhuge_page(struct page
*page
)
585 * we use page->mapping and page->index in second tail page
586 * as list_head: assuming THP order >= 2
589 INIT_LIST_HEAD(page_deferred_list(page
));
590 set_compound_page_dtor(page
, TRANSHUGE_PAGE_DTOR
);
593 static inline bool is_transparent_hugepage(struct page
*page
)
595 if (!PageCompound(page
))
598 page
= compound_head(page
);
599 return is_huge_zero_page(page
) ||
600 page
[1].compound_dtor
== TRANSHUGE_PAGE_DTOR
;
603 static unsigned long __thp_get_unmapped_area(struct file
*filp
,
604 unsigned long addr
, unsigned long len
,
605 loff_t off
, unsigned long flags
, unsigned long size
)
607 loff_t off_end
= off
+ len
;
608 loff_t off_align
= round_up(off
, size
);
609 unsigned long len_pad
, ret
;
611 if (off_end
<= off_align
|| (off_end
- off_align
) < size
)
614 len_pad
= len
+ size
;
615 if (len_pad
< len
|| (off
+ len_pad
) < off
)
618 ret
= current
->mm
->get_unmapped_area(filp
, addr
, len_pad
,
619 off
>> PAGE_SHIFT
, flags
);
622 * The failure might be due to length padding. The caller will retry
623 * without the padding.
625 if (IS_ERR_VALUE(ret
))
629 * Do not try to align to THP boundary if allocation at the address
635 ret
+= (off
- ret
) & (size
- 1);
639 unsigned long thp_get_unmapped_area(struct file
*filp
, unsigned long addr
,
640 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
643 loff_t off
= (loff_t
)pgoff
<< PAGE_SHIFT
;
645 ret
= __thp_get_unmapped_area(filp
, addr
, len
, off
, flags
, PMD_SIZE
);
649 return current
->mm
->get_unmapped_area(filp
, addr
, len
, pgoff
, flags
);
651 EXPORT_SYMBOL_GPL(thp_get_unmapped_area
);
653 static vm_fault_t
__do_huge_pmd_anonymous_page(struct vm_fault
*vmf
,
654 struct page
*page
, gfp_t gfp
)
656 struct vm_area_struct
*vma
= vmf
->vma
;
658 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
661 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
663 if (mem_cgroup_charge(page_folio(page
), vma
->vm_mm
, gfp
)) {
665 count_vm_event(THP_FAULT_FALLBACK
);
666 count_vm_event(THP_FAULT_FALLBACK_CHARGE
);
667 return VM_FAULT_FALLBACK
;
669 cgroup_throttle_swaprate(page
, gfp
);
671 pgtable
= pte_alloc_one(vma
->vm_mm
);
672 if (unlikely(!pgtable
)) {
677 clear_huge_page(page
, vmf
->address
, HPAGE_PMD_NR
);
679 * The memory barrier inside __SetPageUptodate makes sure that
680 * clear_huge_page writes become visible before the set_pmd_at()
683 __SetPageUptodate(page
);
685 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
686 if (unlikely(!pmd_none(*vmf
->pmd
))) {
691 ret
= check_stable_address_space(vma
->vm_mm
);
695 /* Deliver the page fault to userland */
696 if (userfaultfd_missing(vma
)) {
697 spin_unlock(vmf
->ptl
);
699 pte_free(vma
->vm_mm
, pgtable
);
700 ret
= handle_userfault(vmf
, VM_UFFD_MISSING
);
701 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
705 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
706 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
707 page_add_new_anon_rmap(page
, vma
, haddr
);
708 lru_cache_add_inactive_or_unevictable(page
, vma
);
709 pgtable_trans_huge_deposit(vma
->vm_mm
, vmf
->pmd
, pgtable
);
710 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
711 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
712 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
713 mm_inc_nr_ptes(vma
->vm_mm
);
714 spin_unlock(vmf
->ptl
);
715 count_vm_event(THP_FAULT_ALLOC
);
716 count_memcg_event_mm(vma
->vm_mm
, THP_FAULT_ALLOC
);
721 spin_unlock(vmf
->ptl
);
724 pte_free(vma
->vm_mm
, pgtable
);
731 * always: directly stall for all thp allocations
732 * defer: wake kswapd and fail if not immediately available
733 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
734 * fail if not immediately available
735 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
737 * never: never stall for any thp allocation
739 gfp_t
vma_thp_gfp_mask(struct vm_area_struct
*vma
)
741 const bool vma_madvised
= vma
&& (vma
->vm_flags
& VM_HUGEPAGE
);
743 /* Always do synchronous compaction */
744 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
745 return GFP_TRANSHUGE
| (vma_madvised
? 0 : __GFP_NORETRY
);
747 /* Kick kcompactd and fail quickly */
748 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
749 return GFP_TRANSHUGE_LIGHT
| __GFP_KSWAPD_RECLAIM
;
751 /* Synchronous compaction if madvised, otherwise kick kcompactd */
752 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
))
753 return GFP_TRANSHUGE_LIGHT
|
754 (vma_madvised
? __GFP_DIRECT_RECLAIM
:
755 __GFP_KSWAPD_RECLAIM
);
757 /* Only do synchronous compaction if madvised */
758 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
759 return GFP_TRANSHUGE_LIGHT
|
760 (vma_madvised
? __GFP_DIRECT_RECLAIM
: 0);
762 return GFP_TRANSHUGE_LIGHT
;
765 /* Caller must hold page table lock. */
766 static void set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
767 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
768 struct page
*zero_page
)
773 entry
= mk_pmd(zero_page
, vma
->vm_page_prot
);
774 entry
= pmd_mkhuge(entry
);
776 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
777 set_pmd_at(mm
, haddr
, pmd
, entry
);
781 vm_fault_t
do_huge_pmd_anonymous_page(struct vm_fault
*vmf
)
783 struct vm_area_struct
*vma
= vmf
->vma
;
786 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
788 if (!transhuge_vma_suitable(vma
, haddr
))
789 return VM_FAULT_FALLBACK
;
790 if (unlikely(anon_vma_prepare(vma
)))
792 khugepaged_enter_vma(vma
, vma
->vm_flags
);
794 if (!(vmf
->flags
& FAULT_FLAG_WRITE
) &&
795 !mm_forbids_zeropage(vma
->vm_mm
) &&
796 transparent_hugepage_use_zero_page()) {
798 struct page
*zero_page
;
800 pgtable
= pte_alloc_one(vma
->vm_mm
);
801 if (unlikely(!pgtable
))
803 zero_page
= mm_get_huge_zero_page(vma
->vm_mm
);
804 if (unlikely(!zero_page
)) {
805 pte_free(vma
->vm_mm
, pgtable
);
806 count_vm_event(THP_FAULT_FALLBACK
);
807 return VM_FAULT_FALLBACK
;
809 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
811 if (pmd_none(*vmf
->pmd
)) {
812 ret
= check_stable_address_space(vma
->vm_mm
);
814 spin_unlock(vmf
->ptl
);
815 pte_free(vma
->vm_mm
, pgtable
);
816 } else if (userfaultfd_missing(vma
)) {
817 spin_unlock(vmf
->ptl
);
818 pte_free(vma
->vm_mm
, pgtable
);
819 ret
= handle_userfault(vmf
, VM_UFFD_MISSING
);
820 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
822 set_huge_zero_page(pgtable
, vma
->vm_mm
, vma
,
823 haddr
, vmf
->pmd
, zero_page
);
824 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
825 spin_unlock(vmf
->ptl
);
828 spin_unlock(vmf
->ptl
);
829 pte_free(vma
->vm_mm
, pgtable
);
833 gfp
= vma_thp_gfp_mask(vma
);
834 folio
= vma_alloc_folio(gfp
, HPAGE_PMD_ORDER
, vma
, haddr
, true);
835 if (unlikely(!folio
)) {
836 count_vm_event(THP_FAULT_FALLBACK
);
837 return VM_FAULT_FALLBACK
;
839 return __do_huge_pmd_anonymous_page(vmf
, &folio
->page
, gfp
);
842 static void insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
843 pmd_t
*pmd
, pfn_t pfn
, pgprot_t prot
, bool write
,
846 struct mm_struct
*mm
= vma
->vm_mm
;
850 ptl
= pmd_lock(mm
, pmd
);
851 if (!pmd_none(*pmd
)) {
853 if (pmd_pfn(*pmd
) != pfn_t_to_pfn(pfn
)) {
854 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd
));
857 entry
= pmd_mkyoung(*pmd
);
858 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
859 if (pmdp_set_access_flags(vma
, addr
, pmd
, entry
, 1))
860 update_mmu_cache_pmd(vma
, addr
, pmd
);
866 entry
= pmd_mkhuge(pfn_t_pmd(pfn
, prot
));
867 if (pfn_t_devmap(pfn
))
868 entry
= pmd_mkdevmap(entry
);
870 entry
= pmd_mkyoung(pmd_mkdirty(entry
));
871 entry
= maybe_pmd_mkwrite(entry
, vma
);
875 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
880 set_pmd_at(mm
, addr
, pmd
, entry
);
881 update_mmu_cache_pmd(vma
, addr
, pmd
);
886 pte_free(mm
, pgtable
);
890 * vmf_insert_pfn_pmd_prot - insert a pmd size pfn
891 * @vmf: Structure describing the fault
892 * @pfn: pfn to insert
893 * @pgprot: page protection to use
894 * @write: whether it's a write fault
896 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and
897 * also consult the vmf_insert_mixed_prot() documentation when
898 * @pgprot != @vmf->vma->vm_page_prot.
900 * Return: vm_fault_t value.
902 vm_fault_t
vmf_insert_pfn_pmd_prot(struct vm_fault
*vmf
, pfn_t pfn
,
903 pgprot_t pgprot
, bool write
)
905 unsigned long addr
= vmf
->address
& PMD_MASK
;
906 struct vm_area_struct
*vma
= vmf
->vma
;
907 pgtable_t pgtable
= NULL
;
910 * If we had pmd_special, we could avoid all these restrictions,
911 * but we need to be consistent with PTEs and architectures that
912 * can't support a 'special' bit.
914 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) &&
916 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
917 (VM_PFNMAP
|VM_MIXEDMAP
));
918 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
920 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
921 return VM_FAULT_SIGBUS
;
923 if (arch_needs_pgtable_deposit()) {
924 pgtable
= pte_alloc_one(vma
->vm_mm
);
929 track_pfn_insert(vma
, &pgprot
, pfn
);
931 insert_pfn_pmd(vma
, addr
, vmf
->pmd
, pfn
, pgprot
, write
, pgtable
);
932 return VM_FAULT_NOPAGE
;
934 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot
);
936 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
937 static pud_t
maybe_pud_mkwrite(pud_t pud
, struct vm_area_struct
*vma
)
939 if (likely(vma
->vm_flags
& VM_WRITE
))
940 pud
= pud_mkwrite(pud
);
944 static void insert_pfn_pud(struct vm_area_struct
*vma
, unsigned long addr
,
945 pud_t
*pud
, pfn_t pfn
, pgprot_t prot
, bool write
)
947 struct mm_struct
*mm
= vma
->vm_mm
;
951 ptl
= pud_lock(mm
, pud
);
952 if (!pud_none(*pud
)) {
954 if (pud_pfn(*pud
) != pfn_t_to_pfn(pfn
)) {
955 WARN_ON_ONCE(!is_huge_zero_pud(*pud
));
958 entry
= pud_mkyoung(*pud
);
959 entry
= maybe_pud_mkwrite(pud_mkdirty(entry
), vma
);
960 if (pudp_set_access_flags(vma
, addr
, pud
, entry
, 1))
961 update_mmu_cache_pud(vma
, addr
, pud
);
966 entry
= pud_mkhuge(pfn_t_pud(pfn
, prot
));
967 if (pfn_t_devmap(pfn
))
968 entry
= pud_mkdevmap(entry
);
970 entry
= pud_mkyoung(pud_mkdirty(entry
));
971 entry
= maybe_pud_mkwrite(entry
, vma
);
973 set_pud_at(mm
, addr
, pud
, entry
);
974 update_mmu_cache_pud(vma
, addr
, pud
);
981 * vmf_insert_pfn_pud_prot - insert a pud size pfn
982 * @vmf: Structure describing the fault
983 * @pfn: pfn to insert
984 * @pgprot: page protection to use
985 * @write: whether it's a write fault
987 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and
988 * also consult the vmf_insert_mixed_prot() documentation when
989 * @pgprot != @vmf->vma->vm_page_prot.
991 * Return: vm_fault_t value.
993 vm_fault_t
vmf_insert_pfn_pud_prot(struct vm_fault
*vmf
, pfn_t pfn
,
994 pgprot_t pgprot
, bool write
)
996 unsigned long addr
= vmf
->address
& PUD_MASK
;
997 struct vm_area_struct
*vma
= vmf
->vma
;
1000 * If we had pud_special, we could avoid all these restrictions,
1001 * but we need to be consistent with PTEs and architectures that
1002 * can't support a 'special' bit.
1004 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) &&
1005 !pfn_t_devmap(pfn
));
1006 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
1007 (VM_PFNMAP
|VM_MIXEDMAP
));
1008 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
1010 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
1011 return VM_FAULT_SIGBUS
;
1013 track_pfn_insert(vma
, &pgprot
, pfn
);
1015 insert_pfn_pud(vma
, addr
, vmf
->pud
, pfn
, pgprot
, write
);
1016 return VM_FAULT_NOPAGE
;
1018 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot
);
1019 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1021 static void touch_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
1022 pmd_t
*pmd
, bool write
)
1026 _pmd
= pmd_mkyoung(*pmd
);
1028 _pmd
= pmd_mkdirty(_pmd
);
1029 if (pmdp_set_access_flags(vma
, addr
& HPAGE_PMD_MASK
,
1031 update_mmu_cache_pmd(vma
, addr
, pmd
);
1034 struct page
*follow_devmap_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
1035 pmd_t
*pmd
, int flags
, struct dev_pagemap
**pgmap
)
1037 unsigned long pfn
= pmd_pfn(*pmd
);
1038 struct mm_struct
*mm
= vma
->vm_mm
;
1041 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1043 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
1044 if (WARN_ON_ONCE((flags
& (FOLL_PIN
| FOLL_GET
)) ==
1045 (FOLL_PIN
| FOLL_GET
)))
1048 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
1051 if (pmd_present(*pmd
) && pmd_devmap(*pmd
))
1056 if (flags
& FOLL_TOUCH
)
1057 touch_pmd(vma
, addr
, pmd
, flags
& FOLL_WRITE
);
1060 * device mapped pages can only be returned if the
1061 * caller will manage the page reference count.
1063 if (!(flags
& (FOLL_GET
| FOLL_PIN
)))
1064 return ERR_PTR(-EEXIST
);
1066 pfn
+= (addr
& ~PMD_MASK
) >> PAGE_SHIFT
;
1067 *pgmap
= get_dev_pagemap(pfn
, *pgmap
);
1069 return ERR_PTR(-EFAULT
);
1070 page
= pfn_to_page(pfn
);
1071 if (!try_grab_page(page
, flags
))
1072 page
= ERR_PTR(-ENOMEM
);
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
;
1199 assert_spin_locked(pud_lockptr(mm
, pud
));
1201 if (flags
& FOLL_WRITE
&& !pud_write(*pud
))
1204 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
1205 if (WARN_ON_ONCE((flags
& (FOLL_PIN
| FOLL_GET
)) ==
1206 (FOLL_PIN
| FOLL_GET
)))
1209 if (pud_present(*pud
) && pud_devmap(*pud
))
1214 if (flags
& FOLL_TOUCH
)
1215 touch_pud(vma
, addr
, pud
, flags
& FOLL_WRITE
);
1218 * device mapped pages can only be returned if the
1219 * caller will manage the page reference count.
1221 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here:
1223 if (!(flags
& (FOLL_GET
| FOLL_PIN
)))
1224 return ERR_PTR(-EEXIST
);
1226 pfn
+= (addr
& ~PUD_MASK
) >> PAGE_SHIFT
;
1227 *pgmap
= get_dev_pagemap(pfn
, *pgmap
);
1229 return ERR_PTR(-EFAULT
);
1230 page
= pfn_to_page(pfn
);
1231 if (!try_grab_page(page
, flags
))
1232 page
= ERR_PTR(-ENOMEM
);
1237 int copy_huge_pud(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1238 pud_t
*dst_pud
, pud_t
*src_pud
, unsigned long addr
,
1239 struct vm_area_struct
*vma
)
1241 spinlock_t
*dst_ptl
, *src_ptl
;
1245 dst_ptl
= pud_lock(dst_mm
, dst_pud
);
1246 src_ptl
= pud_lockptr(src_mm
, src_pud
);
1247 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
1251 if (unlikely(!pud_trans_huge(pud
) && !pud_devmap(pud
)))
1255 * When page table lock is held, the huge zero pud should not be
1256 * under splitting since we don't split the page itself, only pud to
1259 if (is_huge_zero_pud(pud
)) {
1260 /* No huge zero pud yet */
1264 * TODO: once we support anonymous pages, use page_try_dup_anon_rmap()
1265 * and split if duplicating fails.
1267 pudp_set_wrprotect(src_mm
, addr
, src_pud
);
1268 pud
= pud_mkold(pud_wrprotect(pud
));
1269 set_pud_at(dst_mm
, addr
, dst_pud
, pud
);
1273 spin_unlock(src_ptl
);
1274 spin_unlock(dst_ptl
);
1278 void huge_pud_set_accessed(struct vm_fault
*vmf
, pud_t orig_pud
)
1280 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1282 vmf
->ptl
= pud_lock(vmf
->vma
->vm_mm
, vmf
->pud
);
1283 if (unlikely(!pud_same(*vmf
->pud
, orig_pud
)))
1286 touch_pud(vmf
->vma
, vmf
->address
, vmf
->pud
, write
);
1288 spin_unlock(vmf
->ptl
);
1290 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1292 void huge_pmd_set_accessed(struct vm_fault
*vmf
)
1294 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1296 vmf
->ptl
= pmd_lock(vmf
->vma
->vm_mm
, vmf
->pmd
);
1297 if (unlikely(!pmd_same(*vmf
->pmd
, vmf
->orig_pmd
)))
1300 touch_pmd(vmf
->vma
, vmf
->address
, vmf
->pmd
, write
);
1303 spin_unlock(vmf
->ptl
);
1306 vm_fault_t
do_huge_pmd_wp_page(struct vm_fault
*vmf
)
1308 const bool unshare
= vmf
->flags
& FAULT_FLAG_UNSHARE
;
1309 struct vm_area_struct
*vma
= vmf
->vma
;
1311 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1312 pmd_t orig_pmd
= vmf
->orig_pmd
;
1314 vmf
->ptl
= pmd_lockptr(vma
->vm_mm
, vmf
->pmd
);
1315 VM_BUG_ON_VMA(!vma
->anon_vma
, vma
);
1317 VM_BUG_ON(unshare
&& (vmf
->flags
& FAULT_FLAG_WRITE
));
1318 VM_BUG_ON(!unshare
&& !(vmf
->flags
& FAULT_FLAG_WRITE
));
1320 if (is_huge_zero_pmd(orig_pmd
))
1323 spin_lock(vmf
->ptl
);
1325 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
))) {
1326 spin_unlock(vmf
->ptl
);
1330 page
= pmd_page(orig_pmd
);
1331 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1333 /* Early check when only holding the PT lock. */
1334 if (PageAnonExclusive(page
))
1337 if (!trylock_page(page
)) {
1339 spin_unlock(vmf
->ptl
);
1341 spin_lock(vmf
->ptl
);
1342 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
))) {
1343 spin_unlock(vmf
->ptl
);
1351 /* Recheck after temporarily dropping the PT lock. */
1352 if (PageAnonExclusive(page
)) {
1358 * See do_wp_page(): we can only reuse the page exclusively if there are
1359 * no additional references. Note that we always drain the LRU
1360 * pagevecs immediately after adding a THP.
1362 if (page_count(page
) > 1 + PageSwapCache(page
) * thp_nr_pages(page
))
1363 goto unlock_fallback
;
1364 if (PageSwapCache(page
))
1365 try_to_free_swap(page
);
1366 if (page_count(page
) == 1) {
1369 page_move_anon_rmap(page
, vma
);
1372 if (unlikely(unshare
)) {
1373 spin_unlock(vmf
->ptl
);
1376 entry
= pmd_mkyoung(orig_pmd
);
1377 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1378 if (pmdp_set_access_flags(vma
, haddr
, vmf
->pmd
, entry
, 1))
1379 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1380 spin_unlock(vmf
->ptl
);
1381 return VM_FAULT_WRITE
;
1386 spin_unlock(vmf
->ptl
);
1388 __split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
, false, NULL
);
1389 return VM_FAULT_FALLBACK
;
1392 /* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */
1393 static inline bool can_follow_write_pmd(pmd_t pmd
, struct page
*page
,
1394 struct vm_area_struct
*vma
,
1397 /* If the pmd is writable, we can write to the page. */
1401 /* Maybe FOLL_FORCE is set to override it? */
1402 if (!(flags
& FOLL_FORCE
))
1405 /* But FOLL_FORCE has no effect on shared mappings */
1406 if (vma
->vm_flags
& (VM_MAYSHARE
| VM_SHARED
))
1409 /* ... or read-only private ones */
1410 if (!(vma
->vm_flags
& VM_MAYWRITE
))
1413 /* ... or already writable ones that just need to take a write fault */
1414 if (vma
->vm_flags
& VM_WRITE
)
1418 * See can_change_pte_writable(): we broke COW and could map the page
1419 * writable if we have an exclusive anonymous page ...
1421 if (!page
|| !PageAnon(page
) || !PageAnonExclusive(page
))
1424 /* ... and a write-fault isn't required for other reasons. */
1425 if (vma_soft_dirty_enabled(vma
) && !pmd_soft_dirty(pmd
))
1427 return !userfaultfd_huge_pmd_wp(vma
, pmd
);
1430 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1435 struct mm_struct
*mm
= vma
->vm_mm
;
1438 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1440 page
= pmd_page(*pmd
);
1441 VM_BUG_ON_PAGE(!PageHead(page
) && !is_zone_device_page(page
), page
);
1443 if ((flags
& FOLL_WRITE
) &&
1444 !can_follow_write_pmd(*pmd
, page
, vma
, flags
))
1447 /* Avoid dumping huge zero page */
1448 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1449 return ERR_PTR(-EFAULT
);
1451 /* Full NUMA hinting faults to serialise migration in fault paths */
1452 if ((flags
& FOLL_NUMA
) && pmd_protnone(*pmd
))
1455 if (!pmd_write(*pmd
) && gup_must_unshare(flags
, page
))
1456 return ERR_PTR(-EMLINK
);
1458 VM_BUG_ON_PAGE((flags
& FOLL_PIN
) && PageAnon(page
) &&
1459 !PageAnonExclusive(page
), page
);
1461 if (!try_grab_page(page
, flags
))
1462 return ERR_PTR(-ENOMEM
);
1464 if (flags
& FOLL_TOUCH
)
1465 touch_pmd(vma
, addr
, pmd
, flags
& FOLL_WRITE
);
1467 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1468 VM_BUG_ON_PAGE(!PageCompound(page
) && !is_zone_device_page(page
), page
);
1473 /* NUMA hinting page fault entry point for trans huge pmds */
1474 vm_fault_t
do_huge_pmd_numa_page(struct vm_fault
*vmf
)
1476 struct vm_area_struct
*vma
= vmf
->vma
;
1477 pmd_t oldpmd
= vmf
->orig_pmd
;
1480 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1481 int page_nid
= NUMA_NO_NODE
;
1482 int target_nid
, last_cpupid
= -1;
1483 bool migrated
= false;
1484 bool was_writable
= pmd_savedwrite(oldpmd
);
1487 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1488 if (unlikely(!pmd_same(oldpmd
, *vmf
->pmd
))) {
1489 spin_unlock(vmf
->ptl
);
1493 pmd
= pmd_modify(oldpmd
, vma
->vm_page_prot
);
1494 page
= vm_normal_page_pmd(vma
, haddr
, pmd
);
1498 /* See similar comment in do_numa_page for explanation */
1500 flags
|= TNF_NO_GROUP
;
1502 page_nid
= page_to_nid(page
);
1503 last_cpupid
= page_cpupid_last(page
);
1504 target_nid
= numa_migrate_prep(page
, vma
, haddr
, page_nid
,
1507 if (target_nid
== NUMA_NO_NODE
) {
1512 spin_unlock(vmf
->ptl
);
1514 migrated
= migrate_misplaced_page(page
, vma
, target_nid
);
1516 flags
|= TNF_MIGRATED
;
1517 page_nid
= target_nid
;
1519 flags
|= TNF_MIGRATE_FAIL
;
1520 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1521 if (unlikely(!pmd_same(oldpmd
, *vmf
->pmd
))) {
1522 spin_unlock(vmf
->ptl
);
1529 if (page_nid
!= NUMA_NO_NODE
)
1530 task_numa_fault(last_cpupid
, page_nid
, HPAGE_PMD_NR
,
1536 /* Restore the PMD */
1537 pmd
= pmd_modify(oldpmd
, vma
->vm_page_prot
);
1538 pmd
= pmd_mkyoung(pmd
);
1540 pmd
= pmd_mkwrite(pmd
);
1541 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, pmd
);
1542 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1543 spin_unlock(vmf
->ptl
);
1548 * Return true if we do MADV_FREE successfully on entire pmd page.
1549 * Otherwise, return false.
1551 bool madvise_free_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1552 pmd_t
*pmd
, unsigned long addr
, unsigned long next
)
1557 struct mm_struct
*mm
= tlb
->mm
;
1560 tlb_change_page_size(tlb
, HPAGE_PMD_SIZE
);
1562 ptl
= pmd_trans_huge_lock(pmd
, vma
);
1567 if (is_huge_zero_pmd(orig_pmd
))
1570 if (unlikely(!pmd_present(orig_pmd
))) {
1571 VM_BUG_ON(thp_migration_supported() &&
1572 !is_pmd_migration_entry(orig_pmd
));
1576 page
= pmd_page(orig_pmd
);
1578 * If other processes are mapping this page, we couldn't discard
1579 * the page unless they all do MADV_FREE so let's skip the page.
1581 if (total_mapcount(page
) != 1)
1584 if (!trylock_page(page
))
1588 * If user want to discard part-pages of THP, split it so MADV_FREE
1589 * will deactivate only them.
1591 if (next
- addr
!= HPAGE_PMD_SIZE
) {
1594 split_huge_page(page
);
1600 if (PageDirty(page
))
1601 ClearPageDirty(page
);
1604 if (pmd_young(orig_pmd
) || pmd_dirty(orig_pmd
)) {
1605 pmdp_invalidate(vma
, addr
, pmd
);
1606 orig_pmd
= pmd_mkold(orig_pmd
);
1607 orig_pmd
= pmd_mkclean(orig_pmd
);
1609 set_pmd_at(mm
, addr
, pmd
, orig_pmd
);
1610 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1613 mark_page_lazyfree(page
);
1621 static inline void zap_deposited_table(struct mm_struct
*mm
, pmd_t
*pmd
)
1625 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1626 pte_free(mm
, pgtable
);
1630 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1631 pmd_t
*pmd
, unsigned long addr
)
1636 tlb_change_page_size(tlb
, HPAGE_PMD_SIZE
);
1638 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1642 * For architectures like ppc64 we look at deposited pgtable
1643 * when calling pmdp_huge_get_and_clear. So do the
1644 * pgtable_trans_huge_withdraw after finishing pmdp related
1647 orig_pmd
= pmdp_huge_get_and_clear_full(vma
, addr
, pmd
,
1649 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1650 if (vma_is_special_huge(vma
)) {
1651 if (arch_needs_pgtable_deposit())
1652 zap_deposited_table(tlb
->mm
, pmd
);
1654 } else if (is_huge_zero_pmd(orig_pmd
)) {
1655 zap_deposited_table(tlb
->mm
, pmd
);
1658 struct page
*page
= NULL
;
1659 int flush_needed
= 1;
1661 if (pmd_present(orig_pmd
)) {
1662 page
= pmd_page(orig_pmd
);
1663 page_remove_rmap(page
, vma
, true);
1664 VM_BUG_ON_PAGE(page_mapcount(page
) < 0, page
);
1665 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1666 } else if (thp_migration_supported()) {
1669 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd
));
1670 entry
= pmd_to_swp_entry(orig_pmd
);
1671 page
= pfn_swap_entry_to_page(entry
);
1674 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1676 if (PageAnon(page
)) {
1677 zap_deposited_table(tlb
->mm
, pmd
);
1678 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1680 if (arch_needs_pgtable_deposit())
1681 zap_deposited_table(tlb
->mm
, pmd
);
1682 add_mm_counter(tlb
->mm
, mm_counter_file(page
), -HPAGE_PMD_NR
);
1687 tlb_remove_page_size(tlb
, page
, HPAGE_PMD_SIZE
);
1692 #ifndef pmd_move_must_withdraw
1693 static inline int pmd_move_must_withdraw(spinlock_t
*new_pmd_ptl
,
1694 spinlock_t
*old_pmd_ptl
,
1695 struct vm_area_struct
*vma
)
1698 * With split pmd lock we also need to move preallocated
1699 * PTE page table if new_pmd is on different PMD page table.
1701 * We also don't deposit and withdraw tables for file pages.
1703 return (new_pmd_ptl
!= old_pmd_ptl
) && vma_is_anonymous(vma
);
1707 static pmd_t
move_soft_dirty_pmd(pmd_t pmd
)
1709 #ifdef CONFIG_MEM_SOFT_DIRTY
1710 if (unlikely(is_pmd_migration_entry(pmd
)))
1711 pmd
= pmd_swp_mksoft_dirty(pmd
);
1712 else if (pmd_present(pmd
))
1713 pmd
= pmd_mksoft_dirty(pmd
);
1718 bool move_huge_pmd(struct vm_area_struct
*vma
, unsigned long old_addr
,
1719 unsigned long new_addr
, pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1721 spinlock_t
*old_ptl
, *new_ptl
;
1723 struct mm_struct
*mm
= vma
->vm_mm
;
1724 bool force_flush
= false;
1727 * The destination pmd shouldn't be established, free_pgtables()
1728 * should have release it.
1730 if (WARN_ON(!pmd_none(*new_pmd
))) {
1731 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1736 * We don't have to worry about the ordering of src and dst
1737 * ptlocks because exclusive mmap_lock prevents deadlock.
1739 old_ptl
= __pmd_trans_huge_lock(old_pmd
, vma
);
1741 new_ptl
= pmd_lockptr(mm
, new_pmd
);
1742 if (new_ptl
!= old_ptl
)
1743 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
1744 pmd
= pmdp_huge_get_and_clear(mm
, old_addr
, old_pmd
);
1745 if (pmd_present(pmd
))
1747 VM_BUG_ON(!pmd_none(*new_pmd
));
1749 if (pmd_move_must_withdraw(new_ptl
, old_ptl
, vma
)) {
1751 pgtable
= pgtable_trans_huge_withdraw(mm
, old_pmd
);
1752 pgtable_trans_huge_deposit(mm
, new_pmd
, pgtable
);
1754 pmd
= move_soft_dirty_pmd(pmd
);
1755 set_pmd_at(mm
, new_addr
, new_pmd
, pmd
);
1757 flush_pmd_tlb_range(vma
, old_addr
, old_addr
+ PMD_SIZE
);
1758 if (new_ptl
!= old_ptl
)
1759 spin_unlock(new_ptl
);
1760 spin_unlock(old_ptl
);
1768 * - 0 if PMD could not be locked
1769 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary
1770 * or if prot_numa but THP migration is not supported
1771 * - HPAGE_PMD_NR if protections changed and TLB flush necessary
1773 int change_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1774 pmd_t
*pmd
, unsigned long addr
, pgprot_t newprot
,
1775 unsigned long cp_flags
)
1777 struct mm_struct
*mm
= vma
->vm_mm
;
1779 pmd_t oldpmd
, entry
;
1780 bool preserve_write
;
1782 bool prot_numa
= cp_flags
& MM_CP_PROT_NUMA
;
1783 bool uffd_wp
= cp_flags
& MM_CP_UFFD_WP
;
1784 bool uffd_wp_resolve
= cp_flags
& MM_CP_UFFD_WP_RESOLVE
;
1786 tlb_change_page_size(tlb
, HPAGE_PMD_SIZE
);
1788 if (prot_numa
&& !thp_migration_supported())
1791 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1795 preserve_write
= prot_numa
&& pmd_write(*pmd
);
1798 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1799 if (is_swap_pmd(*pmd
)) {
1800 swp_entry_t entry
= pmd_to_swp_entry(*pmd
);
1801 struct page
*page
= pfn_swap_entry_to_page(entry
);
1803 VM_BUG_ON(!is_pmd_migration_entry(*pmd
));
1804 if (is_writable_migration_entry(entry
)) {
1807 * A protection check is difficult so
1808 * just be safe and disable write
1811 entry
= make_readable_exclusive_migration_entry(swp_offset(entry
));
1813 entry
= make_readable_migration_entry(swp_offset(entry
));
1814 newpmd
= swp_entry_to_pmd(entry
);
1815 if (pmd_swp_soft_dirty(*pmd
))
1816 newpmd
= pmd_swp_mksoft_dirty(newpmd
);
1817 if (pmd_swp_uffd_wp(*pmd
))
1818 newpmd
= pmd_swp_mkuffd_wp(newpmd
);
1819 set_pmd_at(mm
, addr
, pmd
, newpmd
);
1828 * Avoid trapping faults against the zero page. The read-only
1829 * data is likely to be read-cached on the local CPU and
1830 * local/remote hits to the zero page are not interesting.
1832 if (is_huge_zero_pmd(*pmd
))
1835 if (pmd_protnone(*pmd
))
1838 page
= pmd_page(*pmd
);
1840 * Skip scanning top tier node if normal numa
1841 * balancing is disabled
1843 if (!(sysctl_numa_balancing_mode
& NUMA_BALANCING_NORMAL
) &&
1844 node_is_toptier(page_to_nid(page
)))
1848 * In case prot_numa, we are under mmap_read_lock(mm). It's critical
1849 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1850 * which is also under mmap_read_lock(mm):
1853 * change_huge_pmd(prot_numa=1)
1854 * pmdp_huge_get_and_clear_notify()
1855 * madvise_dontneed()
1857 * pmd_trans_huge(*pmd) == 0 (without ptl)
1860 * // pmd is re-established
1862 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1863 * which may break userspace.
1865 * pmdp_invalidate_ad() is required to make sure we don't miss
1866 * dirty/young flags set by hardware.
1868 oldpmd
= pmdp_invalidate_ad(vma
, addr
, pmd
);
1870 entry
= pmd_modify(oldpmd
, newprot
);
1872 entry
= pmd_mk_savedwrite(entry
);
1874 entry
= pmd_wrprotect(entry
);
1875 entry
= pmd_mkuffd_wp(entry
);
1876 } else if (uffd_wp_resolve
) {
1878 * Leave the write bit to be handled by PF interrupt
1879 * handler, then things like COW could be properly
1882 entry
= pmd_clear_uffd_wp(entry
);
1885 set_pmd_at(mm
, addr
, pmd
, entry
);
1887 if (huge_pmd_needs_flush(oldpmd
, entry
))
1888 tlb_flush_pmd_range(tlb
, addr
, HPAGE_PMD_SIZE
);
1890 BUG_ON(vma_is_anonymous(vma
) && !preserve_write
&& pmd_write(entry
));
1897 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1899 * Note that if it returns page table lock pointer, this routine returns without
1900 * unlocking page table lock. So callers must unlock it.
1902 spinlock_t
*__pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1905 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
1906 if (likely(is_swap_pmd(*pmd
) || pmd_trans_huge(*pmd
) ||
1914 * Returns page table lock pointer if a given pud maps a thp, NULL otherwise.
1916 * Note that if it returns page table lock pointer, this routine returns without
1917 * unlocking page table lock. So callers must unlock it.
1919 spinlock_t
*__pud_trans_huge_lock(pud_t
*pud
, struct vm_area_struct
*vma
)
1923 ptl
= pud_lock(vma
->vm_mm
, pud
);
1924 if (likely(pud_trans_huge(*pud
) || pud_devmap(*pud
)))
1930 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1931 int zap_huge_pud(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1932 pud_t
*pud
, unsigned long addr
)
1936 ptl
= __pud_trans_huge_lock(pud
, vma
);
1940 pudp_huge_get_and_clear_full(tlb
->mm
, addr
, pud
, tlb
->fullmm
);
1941 tlb_remove_pud_tlb_entry(tlb
, pud
, addr
);
1942 if (vma_is_special_huge(vma
)) {
1944 /* No zero page support yet */
1946 /* No support for anonymous PUD pages yet */
1952 static void __split_huge_pud_locked(struct vm_area_struct
*vma
, pud_t
*pud
,
1953 unsigned long haddr
)
1955 VM_BUG_ON(haddr
& ~HPAGE_PUD_MASK
);
1956 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
1957 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PUD_SIZE
, vma
);
1958 VM_BUG_ON(!pud_trans_huge(*pud
) && !pud_devmap(*pud
));
1960 count_vm_event(THP_SPLIT_PUD
);
1962 pudp_huge_clear_flush_notify(vma
, haddr
, pud
);
1965 void __split_huge_pud(struct vm_area_struct
*vma
, pud_t
*pud
,
1966 unsigned long address
)
1969 struct mmu_notifier_range range
;
1971 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
1972 address
& HPAGE_PUD_MASK
,
1973 (address
& HPAGE_PUD_MASK
) + HPAGE_PUD_SIZE
);
1974 mmu_notifier_invalidate_range_start(&range
);
1975 ptl
= pud_lock(vma
->vm_mm
, pud
);
1976 if (unlikely(!pud_trans_huge(*pud
) && !pud_devmap(*pud
)))
1978 __split_huge_pud_locked(vma
, pud
, range
.start
);
1983 * No need to double call mmu_notifier->invalidate_range() callback as
1984 * the above pudp_huge_clear_flush_notify() did already call it.
1986 mmu_notifier_invalidate_range_only_end(&range
);
1988 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1990 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
1991 unsigned long haddr
, pmd_t
*pmd
)
1993 struct mm_struct
*mm
= vma
->vm_mm
;
1999 * Leave pmd empty until pte is filled note that it is fine to delay
2000 * notification until mmu_notifier_invalidate_range_end() as we are
2001 * replacing a zero pmd write protected page with a zero pte write
2004 * See Documentation/mm/mmu_notifier.rst
2006 pmdp_huge_clear_flush(vma
, haddr
, pmd
);
2008 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2009 pmd_populate(mm
, &_pmd
, pgtable
);
2011 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2013 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2014 entry
= pte_mkspecial(entry
);
2015 pte
= pte_offset_map(&_pmd
, haddr
);
2016 VM_BUG_ON(!pte_none(*pte
));
2017 set_pte_at(mm
, haddr
, pte
, entry
);
2020 smp_wmb(); /* make pte visible before pmd */
2021 pmd_populate(mm
, pmd
, pgtable
);
2024 static void __split_huge_pmd_locked(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2025 unsigned long haddr
, bool freeze
)
2027 struct mm_struct
*mm
= vma
->vm_mm
;
2030 pmd_t old_pmd
, _pmd
;
2031 bool young
, write
, soft_dirty
, pmd_migration
= false, uffd_wp
= false;
2032 bool anon_exclusive
= false;
2036 VM_BUG_ON(haddr
& ~HPAGE_PMD_MASK
);
2037 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
2038 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
, vma
);
2039 VM_BUG_ON(!is_pmd_migration_entry(*pmd
) && !pmd_trans_huge(*pmd
)
2040 && !pmd_devmap(*pmd
));
2042 count_vm_event(THP_SPLIT_PMD
);
2044 if (!vma_is_anonymous(vma
)) {
2045 old_pmd
= pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
2047 * We are going to unmap this huge page. So
2048 * just go ahead and zap it
2050 if (arch_needs_pgtable_deposit())
2051 zap_deposited_table(mm
, pmd
);
2052 if (vma_is_special_huge(vma
))
2054 if (unlikely(is_pmd_migration_entry(old_pmd
))) {
2057 entry
= pmd_to_swp_entry(old_pmd
);
2058 page
= pfn_swap_entry_to_page(entry
);
2060 page
= pmd_page(old_pmd
);
2061 if (!PageDirty(page
) && pmd_dirty(old_pmd
))
2062 set_page_dirty(page
);
2063 if (!PageReferenced(page
) && pmd_young(old_pmd
))
2064 SetPageReferenced(page
);
2065 page_remove_rmap(page
, vma
, true);
2068 add_mm_counter(mm
, mm_counter_file(page
), -HPAGE_PMD_NR
);
2072 if (is_huge_zero_pmd(*pmd
)) {
2074 * FIXME: Do we want to invalidate secondary mmu by calling
2075 * mmu_notifier_invalidate_range() see comments below inside
2076 * __split_huge_pmd() ?
2078 * We are going from a zero huge page write protected to zero
2079 * small page also write protected so it does not seems useful
2080 * to invalidate secondary mmu at this time.
2082 return __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
2086 * Up to this point the pmd is present and huge and userland has the
2087 * whole access to the hugepage during the split (which happens in
2088 * place). If we overwrite the pmd with the not-huge version pointing
2089 * to the pte here (which of course we could if all CPUs were bug
2090 * free), userland could trigger a small page size TLB miss on the
2091 * small sized TLB while the hugepage TLB entry is still established in
2092 * the huge TLB. Some CPU doesn't like that.
2093 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum
2094 * 383 on page 105. Intel should be safe but is also warns that it's
2095 * only safe if the permission and cache attributes of the two entries
2096 * loaded in the two TLB is identical (which should be the case here).
2097 * But it is generally safer to never allow small and huge TLB entries
2098 * for the same virtual address to be loaded simultaneously. So instead
2099 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2100 * current pmd notpresent (atomically because here the pmd_trans_huge
2101 * must remain set at all times on the pmd until the split is complete
2102 * for this pmd), then we flush the SMP TLB and finally we write the
2103 * non-huge version of the pmd entry with pmd_populate.
2105 old_pmd
= pmdp_invalidate(vma
, haddr
, pmd
);
2107 pmd_migration
= is_pmd_migration_entry(old_pmd
);
2108 if (unlikely(pmd_migration
)) {
2111 entry
= pmd_to_swp_entry(old_pmd
);
2112 page
= pfn_swap_entry_to_page(entry
);
2113 write
= is_writable_migration_entry(entry
);
2115 anon_exclusive
= is_readable_exclusive_migration_entry(entry
);
2117 soft_dirty
= pmd_swp_soft_dirty(old_pmd
);
2118 uffd_wp
= pmd_swp_uffd_wp(old_pmd
);
2120 page
= pmd_page(old_pmd
);
2121 if (pmd_dirty(old_pmd
))
2123 write
= pmd_write(old_pmd
);
2124 young
= pmd_young(old_pmd
);
2125 soft_dirty
= pmd_soft_dirty(old_pmd
);
2126 uffd_wp
= pmd_uffd_wp(old_pmd
);
2128 VM_BUG_ON_PAGE(!page_count(page
), page
);
2129 page_ref_add(page
, HPAGE_PMD_NR
- 1);
2132 * Without "freeze", we'll simply split the PMD, propagating the
2133 * PageAnonExclusive() flag for each PTE by setting it for
2134 * each subpage -- no need to (temporarily) clear.
2136 * With "freeze" we want to replace mapped pages by
2137 * migration entries right away. This is only possible if we
2138 * managed to clear PageAnonExclusive() -- see
2139 * set_pmd_migration_entry().
2141 * In case we cannot clear PageAnonExclusive(), split the PMD
2142 * only and let try_to_migrate_one() fail later.
2144 anon_exclusive
= PageAnon(page
) && PageAnonExclusive(page
);
2145 if (freeze
&& anon_exclusive
&& page_try_share_anon_rmap(page
))
2150 * Withdraw the table only after we mark the pmd entry invalid.
2151 * This's critical for some architectures (Power).
2153 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2154 pmd_populate(mm
, &_pmd
, pgtable
);
2156 for (i
= 0, addr
= haddr
; i
< HPAGE_PMD_NR
; i
++, addr
+= PAGE_SIZE
) {
2159 * Note that NUMA hinting access restrictions are not
2160 * transferred to avoid any possibility of altering
2161 * permissions across VMAs.
2163 if (freeze
|| pmd_migration
) {
2164 swp_entry_t swp_entry
;
2166 swp_entry
= make_writable_migration_entry(
2167 page_to_pfn(page
+ i
));
2168 else if (anon_exclusive
)
2169 swp_entry
= make_readable_exclusive_migration_entry(
2170 page_to_pfn(page
+ i
));
2172 swp_entry
= make_readable_migration_entry(
2173 page_to_pfn(page
+ i
));
2174 entry
= swp_entry_to_pte(swp_entry
);
2176 entry
= pte_swp_mksoft_dirty(entry
);
2178 entry
= pte_swp_mkuffd_wp(entry
);
2180 entry
= mk_pte(page
+ i
, READ_ONCE(vma
->vm_page_prot
));
2181 entry
= maybe_mkwrite(entry
, vma
);
2183 SetPageAnonExclusive(page
+ i
);
2185 entry
= pte_wrprotect(entry
);
2187 entry
= pte_mkold(entry
);
2189 entry
= pte_mksoft_dirty(entry
);
2191 entry
= pte_mkuffd_wp(entry
);
2193 pte
= pte_offset_map(&_pmd
, addr
);
2194 BUG_ON(!pte_none(*pte
));
2195 set_pte_at(mm
, addr
, pte
, entry
);
2197 atomic_inc(&page
[i
]._mapcount
);
2201 if (!pmd_migration
) {
2203 * Set PG_double_map before dropping compound_mapcount to avoid
2204 * false-negative page_mapped().
2206 if (compound_mapcount(page
) > 1 &&
2207 !TestSetPageDoubleMap(page
)) {
2208 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2209 atomic_inc(&page
[i
]._mapcount
);
2212 lock_page_memcg(page
);
2213 if (atomic_add_negative(-1, compound_mapcount_ptr(page
))) {
2214 /* Last compound_mapcount is gone. */
2215 __mod_lruvec_page_state(page
, NR_ANON_THPS
,
2217 if (TestClearPageDoubleMap(page
)) {
2218 /* No need in mapcount reference anymore */
2219 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2220 atomic_dec(&page
[i
]._mapcount
);
2223 unlock_page_memcg(page
);
2225 /* Above is effectively page_remove_rmap(page, vma, true) */
2226 munlock_vma_page(page
, vma
, true);
2229 smp_wmb(); /* make pte visible before pmd */
2230 pmd_populate(mm
, pmd
, pgtable
);
2233 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2234 page_remove_rmap(page
+ i
, vma
, false);
2240 void __split_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2241 unsigned long address
, bool freeze
, struct folio
*folio
)
2244 struct mmu_notifier_range range
;
2246 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
2247 address
& HPAGE_PMD_MASK
,
2248 (address
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
);
2249 mmu_notifier_invalidate_range_start(&range
);
2250 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
2253 * If caller asks to setup a migration entry, we need a folio to check
2254 * pmd against. Otherwise we can end up replacing wrong folio.
2256 VM_BUG_ON(freeze
&& !folio
);
2257 VM_WARN_ON_ONCE(folio
&& !folio_test_locked(folio
));
2259 if (pmd_trans_huge(*pmd
) || pmd_devmap(*pmd
) ||
2260 is_pmd_migration_entry(*pmd
)) {
2262 * It's safe to call pmd_page when folio is set because it's
2263 * guaranteed that pmd is present.
2265 if (folio
&& folio
!= page_folio(pmd_page(*pmd
)))
2267 __split_huge_pmd_locked(vma
, pmd
, range
.start
, freeze
);
2273 * No need to double call mmu_notifier->invalidate_range() callback.
2274 * They are 3 cases to consider inside __split_huge_pmd_locked():
2275 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2276 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2277 * fault will trigger a flush_notify before pointing to a new page
2278 * (it is fine if the secondary mmu keeps pointing to the old zero
2279 * page in the meantime)
2280 * 3) Split a huge pmd into pte pointing to the same page. No need
2281 * to invalidate secondary tlb entry they are all still valid.
2282 * any further changes to individual pte will notify. So no need
2283 * to call mmu_notifier->invalidate_range()
2285 mmu_notifier_invalidate_range_only_end(&range
);
2288 void split_huge_pmd_address(struct vm_area_struct
*vma
, unsigned long address
,
2289 bool freeze
, struct folio
*folio
)
2296 pgd
= pgd_offset(vma
->vm_mm
, address
);
2297 if (!pgd_present(*pgd
))
2300 p4d
= p4d_offset(pgd
, address
);
2301 if (!p4d_present(*p4d
))
2304 pud
= pud_offset(p4d
, address
);
2305 if (!pud_present(*pud
))
2308 pmd
= pmd_offset(pud
, address
);
2310 __split_huge_pmd(vma
, pmd
, address
, freeze
, folio
);
2313 static inline void split_huge_pmd_if_needed(struct vm_area_struct
*vma
, unsigned long address
)
2316 * If the new address isn't hpage aligned and it could previously
2317 * contain an hugepage: check if we need to split an huge pmd.
2319 if (!IS_ALIGNED(address
, HPAGE_PMD_SIZE
) &&
2320 range_in_vma(vma
, ALIGN_DOWN(address
, HPAGE_PMD_SIZE
),
2321 ALIGN(address
, HPAGE_PMD_SIZE
)))
2322 split_huge_pmd_address(vma
, address
, false, NULL
);
2325 void vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2326 unsigned long start
,
2330 /* Check if we need to split start first. */
2331 split_huge_pmd_if_needed(vma
, start
);
2333 /* Check if we need to split end next. */
2334 split_huge_pmd_if_needed(vma
, end
);
2337 * If we're also updating the vma->vm_next->vm_start,
2338 * check if we need to split it.
2340 if (adjust_next
> 0) {
2341 struct vm_area_struct
*next
= vma
->vm_next
;
2342 unsigned long nstart
= next
->vm_start
;
2343 nstart
+= adjust_next
;
2344 split_huge_pmd_if_needed(next
, nstart
);
2348 static void unmap_page(struct page
*page
)
2350 struct folio
*folio
= page_folio(page
);
2351 enum ttu_flags ttu_flags
= TTU_RMAP_LOCKED
| TTU_SPLIT_HUGE_PMD
|
2354 VM_BUG_ON_PAGE(!PageHead(page
), page
);
2357 * Anon pages need migration entries to preserve them, but file
2358 * pages can simply be left unmapped, then faulted back on demand.
2359 * If that is ever changed (perhaps for mlock), update remap_page().
2361 if (folio_test_anon(folio
))
2362 try_to_migrate(folio
, ttu_flags
);
2364 try_to_unmap(folio
, ttu_flags
| TTU_IGNORE_MLOCK
);
2367 static void remap_page(struct folio
*folio
, unsigned long nr
)
2371 /* If unmap_page() uses try_to_migrate() on file, remove this check */
2372 if (!folio_test_anon(folio
))
2375 remove_migration_ptes(folio
, folio
, true);
2376 i
+= folio_nr_pages(folio
);
2379 folio
= folio_next(folio
);
2383 static void lru_add_page_tail(struct page
*head
, struct page
*tail
,
2384 struct lruvec
*lruvec
, struct list_head
*list
)
2386 VM_BUG_ON_PAGE(!PageHead(head
), head
);
2387 VM_BUG_ON_PAGE(PageCompound(tail
), head
);
2388 VM_BUG_ON_PAGE(PageLRU(tail
), head
);
2389 lockdep_assert_held(&lruvec
->lru_lock
);
2392 /* page reclaim is reclaiming a huge page */
2393 VM_WARN_ON(PageLRU(head
));
2395 list_add_tail(&tail
->lru
, list
);
2397 /* head is still on lru (and we have it frozen) */
2398 VM_WARN_ON(!PageLRU(head
));
2399 if (PageUnevictable(tail
))
2400 tail
->mlock_count
= 0;
2402 list_add_tail(&tail
->lru
, &head
->lru
);
2407 static void __split_huge_page_tail(struct page
*head
, int tail
,
2408 struct lruvec
*lruvec
, struct list_head
*list
)
2410 struct page
*page_tail
= head
+ tail
;
2412 VM_BUG_ON_PAGE(atomic_read(&page_tail
->_mapcount
) != -1, page_tail
);
2415 * Clone page flags before unfreezing refcount.
2417 * After successful get_page_unless_zero() might follow flags change,
2418 * for example lock_page() which set PG_waiters.
2420 * Note that for mapped sub-pages of an anonymous THP,
2421 * PG_anon_exclusive has been cleared in unmap_page() and is stored in
2422 * the migration entry instead from where remap_page() will restore it.
2423 * We can still have PG_anon_exclusive set on effectively unmapped and
2424 * unreferenced sub-pages of an anonymous THP: we can simply drop
2425 * PG_anon_exclusive (-> PG_mappedtodisk) for these here.
2427 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
;
2428 page_tail
->flags
|= (head
->flags
&
2429 ((1L << PG_referenced
) |
2430 (1L << PG_swapbacked
) |
2431 (1L << PG_swapcache
) |
2432 (1L << PG_mlocked
) |
2433 (1L << PG_uptodate
) |
2435 (1L << PG_workingset
) |
2437 (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
;
2448 page_tail
->private = 0;
2450 /* Page flags must be visible before we make the page non-compound. */
2454 * Clear PageTail before unfreezing page refcount.
2456 * After successful get_page_unless_zero() might follow put_page()
2457 * which needs correct compound_head().
2459 clear_compound_head(page_tail
);
2461 /* Finally unfreeze refcount. Additional reference from page cache. */
2462 page_ref_unfreeze(page_tail
, 1 + (!PageAnon(head
) ||
2463 PageSwapCache(head
)));
2465 if (page_is_young(head
))
2466 set_page_young(page_tail
);
2467 if (page_is_idle(head
))
2468 set_page_idle(page_tail
);
2470 page_cpupid_xchg_last(page_tail
, page_cpupid_last(head
));
2473 * always add to the tail because some iterators expect new
2474 * pages to show after the currently processed elements - e.g.
2477 lru_add_page_tail(head
, page_tail
, lruvec
, list
);
2480 static void __split_huge_page(struct page
*page
, struct list_head
*list
,
2483 struct folio
*folio
= page_folio(page
);
2484 struct page
*head
= &folio
->page
;
2485 struct lruvec
*lruvec
;
2486 struct address_space
*swap_cache
= NULL
;
2487 unsigned long offset
= 0;
2488 unsigned int nr
= thp_nr_pages(head
);
2491 /* complete memcg works before add pages to LRU */
2492 split_page_memcg(head
, nr
);
2494 if (PageAnon(head
) && PageSwapCache(head
)) {
2495 swp_entry_t entry
= { .val
= page_private(head
) };
2497 offset
= swp_offset(entry
);
2498 swap_cache
= swap_address_space(entry
);
2499 xa_lock(&swap_cache
->i_pages
);
2502 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
2503 lruvec
= folio_lruvec_lock(folio
);
2505 ClearPageHasHWPoisoned(head
);
2507 for (i
= nr
- 1; i
>= 1; i
--) {
2508 __split_huge_page_tail(head
, i
, lruvec
, list
);
2509 /* Some pages can be beyond EOF: drop them from page cache */
2510 if (head
[i
].index
>= end
) {
2511 struct folio
*tail
= page_folio(head
+ i
);
2513 if (shmem_mapping(head
->mapping
))
2514 shmem_uncharge(head
->mapping
->host
, 1);
2515 else if (folio_test_clear_dirty(tail
))
2516 folio_account_cleaned(tail
,
2517 inode_to_wb(folio
->mapping
->host
));
2518 __filemap_remove_folio(tail
, NULL
);
2520 } else if (!PageAnon(page
)) {
2521 __xa_store(&head
->mapping
->i_pages
, head
[i
].index
,
2523 } else if (swap_cache
) {
2524 __xa_store(&swap_cache
->i_pages
, offset
+ i
,
2529 ClearPageCompound(head
);
2530 unlock_page_lruvec(lruvec
);
2531 /* Caller disabled irqs, so they are still disabled here */
2533 split_page_owner(head
, nr
);
2535 /* See comment in __split_huge_page_tail() */
2536 if (PageAnon(head
)) {
2537 /* Additional pin to swap cache */
2538 if (PageSwapCache(head
)) {
2539 page_ref_add(head
, 2);
2540 xa_unlock(&swap_cache
->i_pages
);
2545 /* Additional pin to page cache */
2546 page_ref_add(head
, 2);
2547 xa_unlock(&head
->mapping
->i_pages
);
2551 remap_page(folio
, nr
);
2553 if (PageSwapCache(head
)) {
2554 swp_entry_t entry
= { .val
= page_private(head
) };
2556 split_swap_cluster(entry
);
2559 for (i
= 0; i
< nr
; i
++) {
2560 struct page
*subpage
= head
+ i
;
2561 if (subpage
== page
)
2563 unlock_page(subpage
);
2566 * Subpages may be freed if there wasn't any mapping
2567 * like if add_to_swap() is running on a lru page that
2568 * had its mapping zapped. And freeing these pages
2569 * requires taking the lru_lock so we do the put_page
2570 * of the tail pages after the split is complete.
2572 free_page_and_swap_cache(subpage
);
2576 /* Racy check whether the huge page can be split */
2577 bool can_split_folio(struct folio
*folio
, int *pextra_pins
)
2581 /* Additional pins from page cache */
2582 if (folio_test_anon(folio
))
2583 extra_pins
= folio_test_swapcache(folio
) ?
2584 folio_nr_pages(folio
) : 0;
2586 extra_pins
= folio_nr_pages(folio
);
2588 *pextra_pins
= extra_pins
;
2589 return folio_mapcount(folio
) == folio_ref_count(folio
) - extra_pins
- 1;
2593 * This function splits huge page into normal pages. @page can point to any
2594 * subpage of huge page to split. Split doesn't change the position of @page.
2596 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2597 * The huge page must be locked.
2599 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2601 * Both head page and tail pages will inherit mapping, flags, and so on from
2604 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2605 * they are not mapped.
2607 * Returns 0 if the hugepage is split successfully.
2608 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2611 int split_huge_page_to_list(struct page
*page
, struct list_head
*list
)
2613 struct folio
*folio
= page_folio(page
);
2614 struct page
*head
= &folio
->page
;
2615 struct deferred_split
*ds_queue
= get_deferred_split_queue(head
);
2616 XA_STATE(xas
, &head
->mapping
->i_pages
, head
->index
);
2617 struct anon_vma
*anon_vma
= NULL
;
2618 struct address_space
*mapping
= NULL
;
2619 int extra_pins
, ret
;
2623 VM_BUG_ON_PAGE(!PageLocked(head
), head
);
2624 VM_BUG_ON_PAGE(!PageCompound(head
), head
);
2626 is_hzp
= is_huge_zero_page(head
);
2627 VM_WARN_ON_ONCE_PAGE(is_hzp
, head
);
2631 if (PageWriteback(head
))
2634 if (PageAnon(head
)) {
2636 * The caller does not necessarily hold an mmap_lock that would
2637 * prevent the anon_vma disappearing so we first we take a
2638 * reference to it and then lock the anon_vma for write. This
2639 * is similar to folio_lock_anon_vma_read except the write lock
2640 * is taken to serialise against parallel split or collapse
2643 anon_vma
= page_get_anon_vma(head
);
2650 anon_vma_lock_write(anon_vma
);
2652 mapping
= head
->mapping
;
2660 xas_split_alloc(&xas
, head
, compound_order(head
),
2661 mapping_gfp_mask(mapping
) & GFP_RECLAIM_MASK
);
2662 if (xas_error(&xas
)) {
2663 ret
= xas_error(&xas
);
2668 i_mmap_lock_read(mapping
);
2671 *__split_huge_page() may need to trim off pages beyond EOF:
2672 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2673 * which cannot be nested inside the page tree lock. So note
2674 * end now: i_size itself may be changed at any moment, but
2675 * head page lock is good enough to serialize the trimming.
2677 end
= DIV_ROUND_UP(i_size_read(mapping
->host
), PAGE_SIZE
);
2678 if (shmem_mapping(mapping
))
2679 end
= shmem_fallocend(mapping
->host
, end
);
2683 * Racy check if we can split the page, before unmap_page() will
2686 if (!can_split_folio(folio
, &extra_pins
)) {
2693 /* block interrupt reentry in xa_lock and spinlock */
2694 local_irq_disable();
2697 * Check if the head page is present in page cache.
2698 * We assume all tail are present too, if head is there.
2702 if (xas_load(&xas
) != head
)
2706 /* Prevent deferred_split_scan() touching ->_refcount */
2707 spin_lock(&ds_queue
->split_queue_lock
);
2708 if (page_ref_freeze(head
, 1 + extra_pins
)) {
2709 if (!list_empty(page_deferred_list(head
))) {
2710 ds_queue
->split_queue_len
--;
2711 list_del(page_deferred_list(head
));
2713 spin_unlock(&ds_queue
->split_queue_lock
);
2715 int nr
= thp_nr_pages(head
);
2717 xas_split(&xas
, head
, thp_order(head
));
2718 if (PageSwapBacked(head
)) {
2719 __mod_lruvec_page_state(head
, NR_SHMEM_THPS
,
2722 __mod_lruvec_page_state(head
, NR_FILE_THPS
,
2724 filemap_nr_thps_dec(mapping
);
2728 __split_huge_page(page
, list
, end
);
2731 spin_unlock(&ds_queue
->split_queue_lock
);
2736 remap_page(folio
, folio_nr_pages(folio
));
2742 anon_vma_unlock_write(anon_vma
);
2743 put_anon_vma(anon_vma
);
2746 i_mmap_unlock_read(mapping
);
2749 count_vm_event(!ret
? THP_SPLIT_PAGE
: THP_SPLIT_PAGE_FAILED
);
2753 void free_transhuge_page(struct page
*page
)
2755 struct deferred_split
*ds_queue
= get_deferred_split_queue(page
);
2756 unsigned long flags
;
2758 spin_lock_irqsave(&ds_queue
->split_queue_lock
, flags
);
2759 if (!list_empty(page_deferred_list(page
))) {
2760 ds_queue
->split_queue_len
--;
2761 list_del(page_deferred_list(page
));
2763 spin_unlock_irqrestore(&ds_queue
->split_queue_lock
, flags
);
2764 free_compound_page(page
);
2767 void deferred_split_huge_page(struct page
*page
)
2769 struct deferred_split
*ds_queue
= get_deferred_split_queue(page
);
2771 struct mem_cgroup
*memcg
= page_memcg(compound_head(page
));
2773 unsigned long flags
;
2775 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
2778 * The try_to_unmap() in page reclaim path might reach here too,
2779 * this may cause a race condition to corrupt deferred split queue.
2780 * And, if page reclaim is already handling the same page, it is
2781 * unnecessary to handle it again in shrinker.
2783 * Check PageSwapCache to determine if the page is being
2784 * handled by page reclaim since THP swap would add the page into
2785 * swap cache before calling try_to_unmap().
2787 if (PageSwapCache(page
))
2790 spin_lock_irqsave(&ds_queue
->split_queue_lock
, flags
);
2791 if (list_empty(page_deferred_list(page
))) {
2792 count_vm_event(THP_DEFERRED_SPLIT_PAGE
);
2793 list_add_tail(page_deferred_list(page
), &ds_queue
->split_queue
);
2794 ds_queue
->split_queue_len
++;
2797 set_shrinker_bit(memcg
, page_to_nid(page
),
2798 deferred_split_shrinker
.id
);
2801 spin_unlock_irqrestore(&ds_queue
->split_queue_lock
, flags
);
2804 static unsigned long deferred_split_count(struct shrinker
*shrink
,
2805 struct shrink_control
*sc
)
2807 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2808 struct deferred_split
*ds_queue
= &pgdata
->deferred_split_queue
;
2812 ds_queue
= &sc
->memcg
->deferred_split_queue
;
2814 return READ_ONCE(ds_queue
->split_queue_len
);
2817 static unsigned long deferred_split_scan(struct shrinker
*shrink
,
2818 struct shrink_control
*sc
)
2820 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2821 struct deferred_split
*ds_queue
= &pgdata
->deferred_split_queue
;
2822 unsigned long flags
;
2823 LIST_HEAD(list
), *pos
, *next
;
2829 ds_queue
= &sc
->memcg
->deferred_split_queue
;
2832 spin_lock_irqsave(&ds_queue
->split_queue_lock
, flags
);
2833 /* Take pin on all head pages to avoid freeing them under us */
2834 list_for_each_safe(pos
, next
, &ds_queue
->split_queue
) {
2835 page
= list_entry((void *)pos
, struct page
, deferred_list
);
2836 page
= compound_head(page
);
2837 if (get_page_unless_zero(page
)) {
2838 list_move(page_deferred_list(page
), &list
);
2840 /* We lost race with put_compound_page() */
2841 list_del_init(page_deferred_list(page
));
2842 ds_queue
->split_queue_len
--;
2844 if (!--sc
->nr_to_scan
)
2847 spin_unlock_irqrestore(&ds_queue
->split_queue_lock
, flags
);
2849 list_for_each_safe(pos
, next
, &list
) {
2850 page
= list_entry((void *)pos
, struct page
, deferred_list
);
2851 if (!trylock_page(page
))
2853 /* split_huge_page() removes page from list on success */
2854 if (!split_huge_page(page
))
2861 spin_lock_irqsave(&ds_queue
->split_queue_lock
, flags
);
2862 list_splice_tail(&list
, &ds_queue
->split_queue
);
2863 spin_unlock_irqrestore(&ds_queue
->split_queue_lock
, flags
);
2866 * Stop shrinker if we didn't split any page, but the queue is empty.
2867 * This can happen if pages were freed under us.
2869 if (!split
&& list_empty(&ds_queue
->split_queue
))
2874 static struct shrinker deferred_split_shrinker
= {
2875 .count_objects
= deferred_split_count
,
2876 .scan_objects
= deferred_split_scan
,
2877 .seeks
= DEFAULT_SEEKS
,
2878 .flags
= SHRINKER_NUMA_AWARE
| SHRINKER_MEMCG_AWARE
|
2882 #ifdef CONFIG_DEBUG_FS
2883 static void split_huge_pages_all(void)
2887 unsigned long pfn
, max_zone_pfn
;
2888 unsigned long total
= 0, split
= 0;
2890 pr_debug("Split all THPs\n");
2891 for_each_zone(zone
) {
2892 if (!managed_zone(zone
))
2894 max_zone_pfn
= zone_end_pfn(zone
);
2895 for (pfn
= zone
->zone_start_pfn
; pfn
< max_zone_pfn
; pfn
++) {
2897 if (!pfn_valid(pfn
))
2900 page
= pfn_to_page(pfn
);
2901 if (!get_page_unless_zero(page
))
2904 if (zone
!= page_zone(page
))
2907 if (!PageHead(page
) || PageHuge(page
) || !PageLRU(page
))
2912 nr_pages
= thp_nr_pages(page
);
2913 if (!split_huge_page(page
))
2915 pfn
+= nr_pages
- 1;
2923 pr_debug("%lu of %lu THP split\n", split
, total
);
2926 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct
*vma
)
2928 return vma_is_special_huge(vma
) || (vma
->vm_flags
& VM_IO
) ||
2929 is_vm_hugetlb_page(vma
);
2932 static int split_huge_pages_pid(int pid
, unsigned long vaddr_start
,
2933 unsigned long vaddr_end
)
2936 struct task_struct
*task
;
2937 struct mm_struct
*mm
;
2938 unsigned long total
= 0, split
= 0;
2941 vaddr_start
&= PAGE_MASK
;
2942 vaddr_end
&= PAGE_MASK
;
2944 /* Find the task_struct from pid */
2946 task
= find_task_by_vpid(pid
);
2952 get_task_struct(task
);
2955 /* Find the mm_struct */
2956 mm
= get_task_mm(task
);
2957 put_task_struct(task
);
2964 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n",
2965 pid
, vaddr_start
, vaddr_end
);
2969 * always increase addr by PAGE_SIZE, since we could have a PTE page
2970 * table filled with PTE-mapped THPs, each of which is distinct.
2972 for (addr
= vaddr_start
; addr
< vaddr_end
; addr
+= PAGE_SIZE
) {
2973 struct vm_area_struct
*vma
= vma_lookup(mm
, addr
);
2979 /* skip special VMA and hugetlb VMA */
2980 if (vma_not_suitable_for_thp_split(vma
)) {
2985 /* FOLL_DUMP to ignore special (like zero) pages */
2986 page
= follow_page(vma
, addr
, FOLL_GET
| FOLL_DUMP
);
2988 if (IS_ERR_OR_NULL(page
) || is_zone_device_page(page
))
2991 if (!is_transparent_hugepage(page
))
2995 if (!can_split_folio(page_folio(page
), NULL
))
2998 if (!trylock_page(page
))
3001 if (!split_huge_page(page
))
3009 mmap_read_unlock(mm
);
3012 pr_debug("%lu of %lu THP split\n", split
, total
);
3018 static int split_huge_pages_in_file(const char *file_path
, pgoff_t off_start
,
3021 struct filename
*file
;
3022 struct file
*candidate
;
3023 struct address_space
*mapping
;
3027 unsigned long total
= 0, split
= 0;
3029 file
= getname_kernel(file_path
);
3033 candidate
= file_open_name(file
, O_RDONLY
, 0);
3034 if (IS_ERR(candidate
))
3037 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n",
3038 file_path
, off_start
, off_end
);
3040 mapping
= candidate
->f_mapping
;
3042 for (index
= off_start
; index
< off_end
; index
+= nr_pages
) {
3043 struct page
*fpage
= pagecache_get_page(mapping
, index
,
3044 FGP_ENTRY
| FGP_HEAD
, 0);
3047 if (xa_is_value(fpage
) || !fpage
)
3050 if (!is_transparent_hugepage(fpage
))
3054 nr_pages
= thp_nr_pages(fpage
);
3056 if (!trylock_page(fpage
))
3059 if (!split_huge_page(fpage
))
3068 filp_close(candidate
, NULL
);
3071 pr_debug("%lu of %lu file-backed THP split\n", split
, total
);
3077 #define MAX_INPUT_BUF_SZ 255
3079 static ssize_t
split_huge_pages_write(struct file
*file
, const char __user
*buf
,
3080 size_t count
, loff_t
*ppops
)
3082 static DEFINE_MUTEX(split_debug_mutex
);
3084 /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */
3085 char input_buf
[MAX_INPUT_BUF_SZ
];
3087 unsigned long vaddr_start
, vaddr_end
;
3089 ret
= mutex_lock_interruptible(&split_debug_mutex
);
3095 memset(input_buf
, 0, MAX_INPUT_BUF_SZ
);
3096 if (copy_from_user(input_buf
, buf
, min_t(size_t, count
, MAX_INPUT_BUF_SZ
)))
3099 input_buf
[MAX_INPUT_BUF_SZ
- 1] = '\0';
3101 if (input_buf
[0] == '/') {
3103 char *buf
= input_buf
;
3104 char file_path
[MAX_INPUT_BUF_SZ
];
3105 pgoff_t off_start
= 0, off_end
= 0;
3106 size_t input_len
= strlen(input_buf
);
3108 tok
= strsep(&buf
, ",");
3110 strcpy(file_path
, tok
);
3116 ret
= sscanf(buf
, "0x%lx,0x%lx", &off_start
, &off_end
);
3121 ret
= split_huge_pages_in_file(file_path
, off_start
, off_end
);
3128 ret
= sscanf(input_buf
, "%d,0x%lx,0x%lx", &pid
, &vaddr_start
, &vaddr_end
);
3129 if (ret
== 1 && pid
== 1) {
3130 split_huge_pages_all();
3131 ret
= strlen(input_buf
);
3133 } else if (ret
!= 3) {
3138 ret
= split_huge_pages_pid(pid
, vaddr_start
, vaddr_end
);
3140 ret
= strlen(input_buf
);
3142 mutex_unlock(&split_debug_mutex
);
3147 static const struct file_operations split_huge_pages_fops
= {
3148 .owner
= THIS_MODULE
,
3149 .write
= split_huge_pages_write
,
3150 .llseek
= no_llseek
,
3153 static int __init
split_huge_pages_debugfs(void)
3155 debugfs_create_file("split_huge_pages", 0200, NULL
, NULL
,
3156 &split_huge_pages_fops
);
3159 late_initcall(split_huge_pages_debugfs
);
3162 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
3163 int set_pmd_migration_entry(struct page_vma_mapped_walk
*pvmw
,
3166 struct vm_area_struct
*vma
= pvmw
->vma
;
3167 struct mm_struct
*mm
= vma
->vm_mm
;
3168 unsigned long address
= pvmw
->address
;
3169 bool anon_exclusive
;
3174 if (!(pvmw
->pmd
&& !pvmw
->pte
))
3177 flush_cache_range(vma
, address
, address
+ HPAGE_PMD_SIZE
);
3178 pmdval
= pmdp_invalidate(vma
, address
, pvmw
->pmd
);
3180 anon_exclusive
= PageAnon(page
) && PageAnonExclusive(page
);
3181 if (anon_exclusive
&& page_try_share_anon_rmap(page
)) {
3182 set_pmd_at(mm
, address
, pvmw
->pmd
, pmdval
);
3186 if (pmd_dirty(pmdval
))
3187 set_page_dirty(page
);
3188 if (pmd_write(pmdval
))
3189 entry
= make_writable_migration_entry(page_to_pfn(page
));
3190 else if (anon_exclusive
)
3191 entry
= make_readable_exclusive_migration_entry(page_to_pfn(page
));
3193 entry
= make_readable_migration_entry(page_to_pfn(page
));
3194 pmdswp
= swp_entry_to_pmd(entry
);
3195 if (pmd_soft_dirty(pmdval
))
3196 pmdswp
= pmd_swp_mksoft_dirty(pmdswp
);
3197 set_pmd_at(mm
, address
, pvmw
->pmd
, pmdswp
);
3198 page_remove_rmap(page
, vma
, true);
3200 trace_set_migration_pmd(address
, pmd_val(pmdswp
));
3205 void remove_migration_pmd(struct page_vma_mapped_walk
*pvmw
, struct page
*new)
3207 struct vm_area_struct
*vma
= pvmw
->vma
;
3208 struct mm_struct
*mm
= vma
->vm_mm
;
3209 unsigned long address
= pvmw
->address
;
3210 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
3214 if (!(pvmw
->pmd
&& !pvmw
->pte
))
3217 entry
= pmd_to_swp_entry(*pvmw
->pmd
);
3219 pmde
= pmd_mkold(mk_huge_pmd(new, READ_ONCE(vma
->vm_page_prot
)));
3220 if (pmd_swp_soft_dirty(*pvmw
->pmd
))
3221 pmde
= pmd_mksoft_dirty(pmde
);
3222 if (is_writable_migration_entry(entry
))
3223 pmde
= maybe_pmd_mkwrite(pmde
, vma
);
3224 if (pmd_swp_uffd_wp(*pvmw
->pmd
))
3225 pmde
= pmd_wrprotect(pmd_mkuffd_wp(pmde
));
3227 if (PageAnon(new)) {
3228 rmap_t rmap_flags
= RMAP_COMPOUND
;
3230 if (!is_readable_migration_entry(entry
))
3231 rmap_flags
|= RMAP_EXCLUSIVE
;
3233 page_add_anon_rmap(new, vma
, haddr
, rmap_flags
);
3235 page_add_file_rmap(new, vma
, true);
3237 VM_BUG_ON(pmd_write(pmde
) && PageAnon(new) && !PageAnonExclusive(new));
3238 set_pmd_at(mm
, haddr
, pvmw
->pmd
, pmde
);
3240 /* No need to invalidate - it was non-present before */
3241 update_mmu_cache_pmd(vma
, address
, pvmw
->pmd
);
3242 trace_remove_migration_pmd(address
, pmd_val(pmde
));