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>
37 #include <asm/pgalloc.h>
41 * By default transparent hugepage support is disabled in order that avoid
42 * to risk increase the memory footprint of applications without a guaranteed
43 * benefit. When transparent hugepage support is enabled, is for all mappings,
44 * and khugepaged scans all mappings.
45 * Defrag is invoked by khugepaged hugepage allocations and by page faults
46 * for all hugepage allocations.
48 unsigned long transparent_hugepage_flags __read_mostly
=
49 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
50 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
52 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
53 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
55 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
)|
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
)|
57 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
59 static struct shrinker deferred_split_shrinker
;
61 static atomic_t huge_zero_refcount
;
62 struct page
*huge_zero_page __read_mostly
;
64 static struct page
*get_huge_zero_page(void)
66 struct page
*zero_page
;
68 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
69 return READ_ONCE(huge_zero_page
);
71 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
74 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
77 count_vm_event(THP_ZERO_PAGE_ALLOC
);
79 if (cmpxchg(&huge_zero_page
, NULL
, zero_page
)) {
81 __free_pages(zero_page
, compound_order(zero_page
));
85 /* We take additional reference here. It will be put back by shrinker */
86 atomic_set(&huge_zero_refcount
, 2);
88 return READ_ONCE(huge_zero_page
);
91 static void put_huge_zero_page(void)
94 * Counter should never go to zero here. Only shrinker can put
97 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
100 struct page
*mm_get_huge_zero_page(struct mm_struct
*mm
)
102 if (test_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
103 return READ_ONCE(huge_zero_page
);
105 if (!get_huge_zero_page())
108 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
109 put_huge_zero_page();
111 return READ_ONCE(huge_zero_page
);
114 void mm_put_huge_zero_page(struct mm_struct
*mm
)
116 if (test_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
117 put_huge_zero_page();
120 static unsigned long shrink_huge_zero_page_count(struct shrinker
*shrink
,
121 struct shrink_control
*sc
)
123 /* we can free zero page only if last reference remains */
124 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
127 static unsigned long shrink_huge_zero_page_scan(struct shrinker
*shrink
,
128 struct shrink_control
*sc
)
130 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
131 struct page
*zero_page
= xchg(&huge_zero_page
, NULL
);
132 BUG_ON(zero_page
== NULL
);
133 __free_pages(zero_page
, compound_order(zero_page
));
140 static struct shrinker huge_zero_page_shrinker
= {
141 .count_objects
= shrink_huge_zero_page_count
,
142 .scan_objects
= shrink_huge_zero_page_scan
,
143 .seeks
= DEFAULT_SEEKS
,
147 static ssize_t
enabled_show(struct kobject
*kobj
,
148 struct kobj_attribute
*attr
, char *buf
)
150 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
))
151 return sprintf(buf
, "[always] madvise never\n");
152 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
153 return sprintf(buf
, "always [madvise] never\n");
155 return sprintf(buf
, "always madvise [never]\n");
158 static ssize_t
enabled_store(struct kobject
*kobj
,
159 struct kobj_attribute
*attr
,
160 const char *buf
, size_t count
)
164 if (!memcmp("always", buf
,
165 min(sizeof("always")-1, count
))) {
166 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
167 set_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
168 } else if (!memcmp("madvise", buf
,
169 min(sizeof("madvise")-1, count
))) {
170 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
171 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
172 } else if (!memcmp("never", buf
,
173 min(sizeof("never")-1, count
))) {
174 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
175 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
180 int err
= start_stop_khugepaged();
186 static struct kobj_attribute enabled_attr
=
187 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
189 ssize_t
single_hugepage_flag_show(struct kobject
*kobj
,
190 struct kobj_attribute
*attr
, char *buf
,
191 enum transparent_hugepage_flag flag
)
193 return sprintf(buf
, "%d\n",
194 !!test_bit(flag
, &transparent_hugepage_flags
));
197 ssize_t
single_hugepage_flag_store(struct kobject
*kobj
,
198 struct kobj_attribute
*attr
,
199 const char *buf
, size_t count
,
200 enum transparent_hugepage_flag flag
)
205 ret
= kstrtoul(buf
, 10, &value
);
212 set_bit(flag
, &transparent_hugepage_flags
);
214 clear_bit(flag
, &transparent_hugepage_flags
);
219 static ssize_t
defrag_show(struct kobject
*kobj
,
220 struct kobj_attribute
*attr
, char *buf
)
222 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
223 return sprintf(buf
, "[always] defer defer+madvise madvise never\n");
224 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
225 return sprintf(buf
, "always [defer] defer+madvise madvise never\n");
226 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
))
227 return sprintf(buf
, "always defer [defer+madvise] madvise never\n");
228 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
229 return sprintf(buf
, "always defer defer+madvise [madvise] never\n");
230 return sprintf(buf
, "always defer defer+madvise madvise [never]\n");
233 static ssize_t
defrag_store(struct kobject
*kobj
,
234 struct kobj_attribute
*attr
,
235 const char *buf
, size_t count
)
237 if (!memcmp("always", buf
,
238 min(sizeof("always")-1, count
))) {
239 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
240 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
241 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
242 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
243 } else if (!memcmp("defer+madvise", buf
,
244 min(sizeof("defer+madvise")-1, count
))) {
245 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
246 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
247 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
248 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
249 } else if (!memcmp("defer", buf
,
250 min(sizeof("defer")-1, count
))) {
251 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_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_KSWAPD_FLAG
, &transparent_hugepage_flags
);
255 } else if (!memcmp("madvise", buf
,
256 min(sizeof("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_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
260 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
261 } else if (!memcmp("never", buf
,
262 min(sizeof("never")-1, count
))) {
263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
264 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
265 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
266 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
272 static struct kobj_attribute defrag_attr
=
273 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
275 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
276 struct kobj_attribute
*attr
, char *buf
)
278 return single_hugepage_flag_show(kobj
, attr
, buf
,
279 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
281 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
282 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
284 return single_hugepage_flag_store(kobj
, attr
, buf
, count
,
285 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
287 static struct kobj_attribute use_zero_page_attr
=
288 __ATTR(use_zero_page
, 0644, use_zero_page_show
, use_zero_page_store
);
290 static ssize_t
hpage_pmd_size_show(struct kobject
*kobj
,
291 struct kobj_attribute
*attr
, char *buf
)
293 return sprintf(buf
, "%lu\n", HPAGE_PMD_SIZE
);
295 static struct kobj_attribute hpage_pmd_size_attr
=
296 __ATTR_RO(hpage_pmd_size
);
298 #ifdef CONFIG_DEBUG_VM
299 static ssize_t
debug_cow_show(struct kobject
*kobj
,
300 struct kobj_attribute
*attr
, char *buf
)
302 return single_hugepage_flag_show(kobj
, attr
, buf
,
303 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
305 static ssize_t
debug_cow_store(struct kobject
*kobj
,
306 struct kobj_attribute
*attr
,
307 const char *buf
, size_t count
)
309 return single_hugepage_flag_store(kobj
, attr
, buf
, count
,
310 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
312 static struct kobj_attribute debug_cow_attr
=
313 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
314 #endif /* CONFIG_DEBUG_VM */
316 static struct attribute
*hugepage_attr
[] = {
319 &use_zero_page_attr
.attr
,
320 &hpage_pmd_size_attr
.attr
,
321 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
322 &shmem_enabled_attr
.attr
,
324 #ifdef CONFIG_DEBUG_VM
325 &debug_cow_attr
.attr
,
330 static struct attribute_group hugepage_attr_group
= {
331 .attrs
= hugepage_attr
,
334 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
338 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
339 if (unlikely(!*hugepage_kobj
)) {
340 pr_err("failed to create transparent hugepage kobject\n");
344 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
346 pr_err("failed to register transparent hugepage group\n");
350 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
352 pr_err("failed to register transparent hugepage group\n");
353 goto remove_hp_group
;
359 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
361 kobject_put(*hugepage_kobj
);
365 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
367 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
368 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
369 kobject_put(hugepage_kobj
);
372 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
377 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
380 #endif /* CONFIG_SYSFS */
382 static int __init
hugepage_init(void)
385 struct kobject
*hugepage_kobj
;
387 if (!has_transparent_hugepage()) {
388 transparent_hugepage_flags
= 0;
393 * hugepages can't be allocated by the buddy allocator
395 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
>= MAX_ORDER
);
397 * we use page->mapping and page->index in second tail page
398 * as list_head: assuming THP order >= 2
400 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
< 2);
402 err
= hugepage_init_sysfs(&hugepage_kobj
);
406 err
= khugepaged_init();
410 err
= register_shrinker(&huge_zero_page_shrinker
);
412 goto err_hzp_shrinker
;
413 err
= register_shrinker(&deferred_split_shrinker
);
415 goto err_split_shrinker
;
418 * By default disable transparent hugepages on smaller systems,
419 * where the extra memory used could hurt more than TLB overhead
420 * is likely to save. The admin can still enable it through /sys.
422 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
))) {
423 transparent_hugepage_flags
= 0;
427 err
= start_stop_khugepaged();
433 unregister_shrinker(&deferred_split_shrinker
);
435 unregister_shrinker(&huge_zero_page_shrinker
);
437 khugepaged_destroy();
439 hugepage_exit_sysfs(hugepage_kobj
);
443 subsys_initcall(hugepage_init
);
445 static int __init
setup_transparent_hugepage(char *str
)
450 if (!strcmp(str
, "always")) {
451 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
452 &transparent_hugepage_flags
);
453 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
454 &transparent_hugepage_flags
);
456 } else if (!strcmp(str
, "madvise")) {
457 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
458 &transparent_hugepage_flags
);
459 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
460 &transparent_hugepage_flags
);
462 } else if (!strcmp(str
, "never")) {
463 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
464 &transparent_hugepage_flags
);
465 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
466 &transparent_hugepage_flags
);
471 pr_warn("transparent_hugepage= cannot parse, ignored\n");
474 __setup("transparent_hugepage=", setup_transparent_hugepage
);
476 pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
478 if (likely(vma
->vm_flags
& VM_WRITE
))
479 pmd
= pmd_mkwrite(pmd
);
483 static inline struct list_head
*page_deferred_list(struct page
*page
)
486 * ->lru in the tail pages is occupied by compound_head.
487 * Let's use ->mapping + ->index in the second tail page as list_head.
489 return (struct list_head
*)&page
[2].mapping
;
492 void prep_transhuge_page(struct page
*page
)
495 * we use page->mapping and page->indexlru in second tail page
496 * as list_head: assuming THP order >= 2
499 INIT_LIST_HEAD(page_deferred_list(page
));
500 set_compound_page_dtor(page
, TRANSHUGE_PAGE_DTOR
);
503 unsigned long __thp_get_unmapped_area(struct file
*filp
, unsigned long len
,
504 loff_t off
, unsigned long flags
, unsigned long size
)
507 loff_t off_end
= off
+ len
;
508 loff_t off_align
= round_up(off
, size
);
509 unsigned long len_pad
;
511 if (off_end
<= off_align
|| (off_end
- off_align
) < size
)
514 len_pad
= len
+ size
;
515 if (len_pad
< len
|| (off
+ len_pad
) < off
)
518 addr
= current
->mm
->get_unmapped_area(filp
, 0, len_pad
,
519 off
>> PAGE_SHIFT
, flags
);
520 if (IS_ERR_VALUE(addr
))
523 addr
+= (off
- addr
) & (size
- 1);
527 unsigned long thp_get_unmapped_area(struct file
*filp
, unsigned long addr
,
528 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
530 loff_t off
= (loff_t
)pgoff
<< PAGE_SHIFT
;
534 if (!IS_DAX(filp
->f_mapping
->host
) || !IS_ENABLED(CONFIG_FS_DAX_PMD
))
537 addr
= __thp_get_unmapped_area(filp
, len
, off
, flags
, PMD_SIZE
);
542 return current
->mm
->get_unmapped_area(filp
, addr
, len
, pgoff
, flags
);
544 EXPORT_SYMBOL_GPL(thp_get_unmapped_area
);
546 static int __do_huge_pmd_anonymous_page(struct vm_fault
*vmf
, struct page
*page
,
549 struct vm_area_struct
*vma
= vmf
->vma
;
550 struct mem_cgroup
*memcg
;
552 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
554 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
556 if (mem_cgroup_try_charge(page
, vma
->vm_mm
, gfp
, &memcg
, true)) {
558 count_vm_event(THP_FAULT_FALLBACK
);
559 return VM_FAULT_FALLBACK
;
562 pgtable
= pte_alloc_one(vma
->vm_mm
, haddr
);
563 if (unlikely(!pgtable
)) {
564 mem_cgroup_cancel_charge(page
, memcg
, true);
569 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
571 * The memory barrier inside __SetPageUptodate makes sure that
572 * clear_huge_page writes become visible before the set_pmd_at()
575 __SetPageUptodate(page
);
577 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
578 if (unlikely(!pmd_none(*vmf
->pmd
))) {
579 spin_unlock(vmf
->ptl
);
580 mem_cgroup_cancel_charge(page
, memcg
, true);
582 pte_free(vma
->vm_mm
, pgtable
);
586 /* Deliver the page fault to userland */
587 if (userfaultfd_missing(vma
)) {
590 spin_unlock(vmf
->ptl
);
591 mem_cgroup_cancel_charge(page
, memcg
, true);
593 pte_free(vma
->vm_mm
, pgtable
);
594 ret
= handle_userfault(vmf
, VM_UFFD_MISSING
);
595 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
599 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
600 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
601 page_add_new_anon_rmap(page
, vma
, haddr
, true);
602 mem_cgroup_commit_charge(page
, memcg
, false, true);
603 lru_cache_add_active_or_unevictable(page
, vma
);
604 pgtable_trans_huge_deposit(vma
->vm_mm
, vmf
->pmd
, pgtable
);
605 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
606 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
607 atomic_long_inc(&vma
->vm_mm
->nr_ptes
);
608 spin_unlock(vmf
->ptl
);
609 count_vm_event(THP_FAULT_ALLOC
);
616 * always: directly stall for all thp allocations
617 * defer: wake kswapd and fail if not immediately available
618 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
619 * fail if not immediately available
620 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
622 * never: never stall for any thp allocation
624 static inline gfp_t
alloc_hugepage_direct_gfpmask(struct vm_area_struct
*vma
)
626 const bool vma_madvised
= !!(vma
->vm_flags
& VM_HUGEPAGE
);
628 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
629 return GFP_TRANSHUGE
| (vma_madvised
? 0 : __GFP_NORETRY
);
630 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
631 return GFP_TRANSHUGE_LIGHT
| __GFP_KSWAPD_RECLAIM
;
632 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
))
633 return GFP_TRANSHUGE_LIGHT
| (vma_madvised
? __GFP_DIRECT_RECLAIM
:
634 __GFP_KSWAPD_RECLAIM
);
635 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
636 return GFP_TRANSHUGE_LIGHT
| (vma_madvised
? __GFP_DIRECT_RECLAIM
:
638 return GFP_TRANSHUGE_LIGHT
;
641 /* Caller must hold page table lock. */
642 static bool set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
643 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
644 struct page
*zero_page
)
649 entry
= mk_pmd(zero_page
, vma
->vm_page_prot
);
650 entry
= pmd_mkhuge(entry
);
652 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
653 set_pmd_at(mm
, haddr
, pmd
, entry
);
654 atomic_long_inc(&mm
->nr_ptes
);
658 int do_huge_pmd_anonymous_page(struct vm_fault
*vmf
)
660 struct vm_area_struct
*vma
= vmf
->vma
;
663 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
665 if (haddr
< vma
->vm_start
|| haddr
+ HPAGE_PMD_SIZE
> vma
->vm_end
)
666 return VM_FAULT_FALLBACK
;
667 if (unlikely(anon_vma_prepare(vma
)))
669 if (unlikely(khugepaged_enter(vma
, vma
->vm_flags
)))
671 if (!(vmf
->flags
& FAULT_FLAG_WRITE
) &&
672 !mm_forbids_zeropage(vma
->vm_mm
) &&
673 transparent_hugepage_use_zero_page()) {
675 struct page
*zero_page
;
678 pgtable
= pte_alloc_one(vma
->vm_mm
, haddr
);
679 if (unlikely(!pgtable
))
681 zero_page
= mm_get_huge_zero_page(vma
->vm_mm
);
682 if (unlikely(!zero_page
)) {
683 pte_free(vma
->vm_mm
, pgtable
);
684 count_vm_event(THP_FAULT_FALLBACK
);
685 return VM_FAULT_FALLBACK
;
687 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
690 if (pmd_none(*vmf
->pmd
)) {
691 if (userfaultfd_missing(vma
)) {
692 spin_unlock(vmf
->ptl
);
693 ret
= handle_userfault(vmf
, VM_UFFD_MISSING
);
694 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
696 set_huge_zero_page(pgtable
, vma
->vm_mm
, vma
,
697 haddr
, vmf
->pmd
, zero_page
);
698 spin_unlock(vmf
->ptl
);
702 spin_unlock(vmf
->ptl
);
704 pte_free(vma
->vm_mm
, pgtable
);
707 gfp
= alloc_hugepage_direct_gfpmask(vma
);
708 page
= alloc_hugepage_vma(gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
709 if (unlikely(!page
)) {
710 count_vm_event(THP_FAULT_FALLBACK
);
711 return VM_FAULT_FALLBACK
;
713 prep_transhuge_page(page
);
714 return __do_huge_pmd_anonymous_page(vmf
, page
, gfp
);
717 static void insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
718 pmd_t
*pmd
, pfn_t pfn
, pgprot_t prot
, bool write
,
721 struct mm_struct
*mm
= vma
->vm_mm
;
725 ptl
= pmd_lock(mm
, pmd
);
726 entry
= pmd_mkhuge(pfn_t_pmd(pfn
, prot
));
727 if (pfn_t_devmap(pfn
))
728 entry
= pmd_mkdevmap(entry
);
730 entry
= pmd_mkyoung(pmd_mkdirty(entry
));
731 entry
= maybe_pmd_mkwrite(entry
, vma
);
735 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
736 atomic_long_inc(&mm
->nr_ptes
);
739 set_pmd_at(mm
, addr
, pmd
, entry
);
740 update_mmu_cache_pmd(vma
, addr
, pmd
);
744 int vmf_insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
745 pmd_t
*pmd
, pfn_t pfn
, bool write
)
747 pgprot_t pgprot
= vma
->vm_page_prot
;
748 pgtable_t pgtable
= NULL
;
750 * If we had pmd_special, we could avoid all these restrictions,
751 * but we need to be consistent with PTEs and architectures that
752 * can't support a 'special' bit.
754 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)));
755 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
756 (VM_PFNMAP
|VM_MIXEDMAP
));
757 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
758 BUG_ON(!pfn_t_devmap(pfn
));
760 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
761 return VM_FAULT_SIGBUS
;
763 if (arch_needs_pgtable_deposit()) {
764 pgtable
= pte_alloc_one(vma
->vm_mm
, addr
);
769 track_pfn_insert(vma
, &pgprot
, pfn
);
771 insert_pfn_pmd(vma
, addr
, pmd
, pfn
, pgprot
, write
, pgtable
);
772 return VM_FAULT_NOPAGE
;
774 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd
);
776 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
777 static pud_t
maybe_pud_mkwrite(pud_t pud
, struct vm_area_struct
*vma
)
779 if (likely(vma
->vm_flags
& VM_WRITE
))
780 pud
= pud_mkwrite(pud
);
784 static void insert_pfn_pud(struct vm_area_struct
*vma
, unsigned long addr
,
785 pud_t
*pud
, pfn_t pfn
, pgprot_t prot
, bool write
)
787 struct mm_struct
*mm
= vma
->vm_mm
;
791 ptl
= pud_lock(mm
, pud
);
792 entry
= pud_mkhuge(pfn_t_pud(pfn
, prot
));
793 if (pfn_t_devmap(pfn
))
794 entry
= pud_mkdevmap(entry
);
796 entry
= pud_mkyoung(pud_mkdirty(entry
));
797 entry
= maybe_pud_mkwrite(entry
, vma
);
799 set_pud_at(mm
, addr
, pud
, entry
);
800 update_mmu_cache_pud(vma
, addr
, pud
);
804 int vmf_insert_pfn_pud(struct vm_area_struct
*vma
, unsigned long addr
,
805 pud_t
*pud
, pfn_t pfn
, bool write
)
807 pgprot_t pgprot
= vma
->vm_page_prot
;
809 * If we had pud_special, we could avoid all these restrictions,
810 * but we need to be consistent with PTEs and architectures that
811 * can't support a 'special' bit.
813 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)));
814 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
815 (VM_PFNMAP
|VM_MIXEDMAP
));
816 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
817 BUG_ON(!pfn_t_devmap(pfn
));
819 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
820 return VM_FAULT_SIGBUS
;
822 track_pfn_insert(vma
, &pgprot
, pfn
);
824 insert_pfn_pud(vma
, addr
, pud
, pfn
, pgprot
, write
);
825 return VM_FAULT_NOPAGE
;
827 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud
);
828 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
830 static void touch_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
836 * We should set the dirty bit only for FOLL_WRITE but for now
837 * the dirty bit in the pmd is meaningless. And if the dirty
838 * bit will become meaningful and we'll only set it with
839 * FOLL_WRITE, an atomic set_bit will be required on the pmd to
840 * set the young bit, instead of the current set_pmd_at.
842 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
843 if (pmdp_set_access_flags(vma
, addr
& HPAGE_PMD_MASK
,
845 update_mmu_cache_pmd(vma
, addr
, pmd
);
848 struct page
*follow_devmap_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
849 pmd_t
*pmd
, int flags
)
851 unsigned long pfn
= pmd_pfn(*pmd
);
852 struct mm_struct
*mm
= vma
->vm_mm
;
853 struct dev_pagemap
*pgmap
;
856 assert_spin_locked(pmd_lockptr(mm
, pmd
));
859 * When we COW a devmap PMD entry, we split it into PTEs, so we should
860 * not be in this function with `flags & FOLL_COW` set.
862 WARN_ONCE(flags
& FOLL_COW
, "mm: In follow_devmap_pmd with FOLL_COW set");
864 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
867 if (pmd_present(*pmd
) && pmd_devmap(*pmd
))
872 if (flags
& FOLL_TOUCH
)
873 touch_pmd(vma
, addr
, pmd
);
876 * device mapped pages can only be returned if the
877 * caller will manage the page reference count.
879 if (!(flags
& FOLL_GET
))
880 return ERR_PTR(-EEXIST
);
882 pfn
+= (addr
& ~PMD_MASK
) >> PAGE_SHIFT
;
883 pgmap
= get_dev_pagemap(pfn
, NULL
);
885 return ERR_PTR(-EFAULT
);
886 page
= pfn_to_page(pfn
);
888 put_dev_pagemap(pgmap
);
893 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
894 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
895 struct vm_area_struct
*vma
)
897 spinlock_t
*dst_ptl
, *src_ptl
;
898 struct page
*src_page
;
900 pgtable_t pgtable
= NULL
;
903 /* Skip if can be re-fill on fault */
904 if (!vma_is_anonymous(vma
))
907 pgtable
= pte_alloc_one(dst_mm
, addr
);
908 if (unlikely(!pgtable
))
911 dst_ptl
= pmd_lock(dst_mm
, dst_pmd
);
912 src_ptl
= pmd_lockptr(src_mm
, src_pmd
);
913 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
917 if (unlikely(!pmd_trans_huge(pmd
))) {
918 pte_free(dst_mm
, pgtable
);
922 * When page table lock is held, the huge zero pmd should not be
923 * under splitting since we don't split the page itself, only pmd to
926 if (is_huge_zero_pmd(pmd
)) {
927 struct page
*zero_page
;
929 * get_huge_zero_page() will never allocate a new page here,
930 * since we already have a zero page to copy. It just takes a
933 zero_page
= mm_get_huge_zero_page(dst_mm
);
934 set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
940 src_page
= pmd_page(pmd
);
941 VM_BUG_ON_PAGE(!PageHead(src_page
), src_page
);
943 page_dup_rmap(src_page
, true);
944 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
945 atomic_long_inc(&dst_mm
->nr_ptes
);
946 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
948 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
949 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
950 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
954 spin_unlock(src_ptl
);
955 spin_unlock(dst_ptl
);
960 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
961 static void touch_pud(struct vm_area_struct
*vma
, unsigned long addr
,
967 * We should set the dirty bit only for FOLL_WRITE but for now
968 * the dirty bit in the pud is meaningless. And if the dirty
969 * bit will become meaningful and we'll only set it with
970 * FOLL_WRITE, an atomic set_bit will be required on the pud to
971 * set the young bit, instead of the current set_pud_at.
973 _pud
= pud_mkyoung(pud_mkdirty(*pud
));
974 if (pudp_set_access_flags(vma
, addr
& HPAGE_PUD_MASK
,
976 update_mmu_cache_pud(vma
, addr
, pud
);
979 struct page
*follow_devmap_pud(struct vm_area_struct
*vma
, unsigned long addr
,
980 pud_t
*pud
, int flags
)
982 unsigned long pfn
= pud_pfn(*pud
);
983 struct mm_struct
*mm
= vma
->vm_mm
;
984 struct dev_pagemap
*pgmap
;
987 assert_spin_locked(pud_lockptr(mm
, pud
));
989 if (flags
& FOLL_WRITE
&& !pud_write(*pud
))
992 if (pud_present(*pud
) && pud_devmap(*pud
))
997 if (flags
& FOLL_TOUCH
)
998 touch_pud(vma
, addr
, pud
);
1001 * device mapped pages can only be returned if the
1002 * caller will manage the page reference count.
1004 if (!(flags
& FOLL_GET
))
1005 return ERR_PTR(-EEXIST
);
1007 pfn
+= (addr
& ~PUD_MASK
) >> PAGE_SHIFT
;
1008 pgmap
= get_dev_pagemap(pfn
, NULL
);
1010 return ERR_PTR(-EFAULT
);
1011 page
= pfn_to_page(pfn
);
1013 put_dev_pagemap(pgmap
);
1018 int copy_huge_pud(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1019 pud_t
*dst_pud
, pud_t
*src_pud
, unsigned long addr
,
1020 struct vm_area_struct
*vma
)
1022 spinlock_t
*dst_ptl
, *src_ptl
;
1026 dst_ptl
= pud_lock(dst_mm
, dst_pud
);
1027 src_ptl
= pud_lockptr(src_mm
, src_pud
);
1028 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
1032 if (unlikely(!pud_trans_huge(pud
) && !pud_devmap(pud
)))
1036 * When page table lock is held, the huge zero pud should not be
1037 * under splitting since we don't split the page itself, only pud to
1040 if (is_huge_zero_pud(pud
)) {
1041 /* No huge zero pud yet */
1044 pudp_set_wrprotect(src_mm
, addr
, src_pud
);
1045 pud
= pud_mkold(pud_wrprotect(pud
));
1046 set_pud_at(dst_mm
, addr
, dst_pud
, pud
);
1050 spin_unlock(src_ptl
);
1051 spin_unlock(dst_ptl
);
1055 void huge_pud_set_accessed(struct vm_fault
*vmf
, pud_t orig_pud
)
1058 unsigned long haddr
;
1059 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1061 vmf
->ptl
= pud_lock(vmf
->vma
->vm_mm
, vmf
->pud
);
1062 if (unlikely(!pud_same(*vmf
->pud
, orig_pud
)))
1065 entry
= pud_mkyoung(orig_pud
);
1067 entry
= pud_mkdirty(entry
);
1068 haddr
= vmf
->address
& HPAGE_PUD_MASK
;
1069 if (pudp_set_access_flags(vmf
->vma
, haddr
, vmf
->pud
, entry
, write
))
1070 update_mmu_cache_pud(vmf
->vma
, vmf
->address
, vmf
->pud
);
1073 spin_unlock(vmf
->ptl
);
1075 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1077 void huge_pmd_set_accessed(struct vm_fault
*vmf
, pmd_t orig_pmd
)
1080 unsigned long haddr
;
1081 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1083 vmf
->ptl
= pmd_lock(vmf
->vma
->vm_mm
, vmf
->pmd
);
1084 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1087 entry
= pmd_mkyoung(orig_pmd
);
1089 entry
= pmd_mkdirty(entry
);
1090 haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1091 if (pmdp_set_access_flags(vmf
->vma
, haddr
, vmf
->pmd
, entry
, write
))
1092 update_mmu_cache_pmd(vmf
->vma
, vmf
->address
, vmf
->pmd
);
1095 spin_unlock(vmf
->ptl
);
1098 static int do_huge_pmd_wp_page_fallback(struct vm_fault
*vmf
, pmd_t orig_pmd
,
1101 struct vm_area_struct
*vma
= vmf
->vma
;
1102 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1103 struct mem_cgroup
*memcg
;
1107 struct page
**pages
;
1108 unsigned long mmun_start
; /* For mmu_notifiers */
1109 unsigned long mmun_end
; /* For mmu_notifiers */
1111 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
1113 if (unlikely(!pages
)) {
1114 ret
|= VM_FAULT_OOM
;
1118 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1119 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
, vma
,
1120 vmf
->address
, page_to_nid(page
));
1121 if (unlikely(!pages
[i
] ||
1122 mem_cgroup_try_charge(pages
[i
], vma
->vm_mm
,
1123 GFP_KERNEL
, &memcg
, false))) {
1127 memcg
= (void *)page_private(pages
[i
]);
1128 set_page_private(pages
[i
], 0);
1129 mem_cgroup_cancel_charge(pages
[i
], memcg
,
1134 ret
|= VM_FAULT_OOM
;
1137 set_page_private(pages
[i
], (unsigned long)memcg
);
1140 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1141 copy_user_highpage(pages
[i
], page
+ i
,
1142 haddr
+ PAGE_SIZE
* i
, vma
);
1143 __SetPageUptodate(pages
[i
]);
1148 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1149 mmu_notifier_invalidate_range_start(vma
->vm_mm
, mmun_start
, mmun_end
);
1151 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1152 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1153 goto out_free_pages
;
1154 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1156 pmdp_huge_clear_flush_notify(vma
, haddr
, vmf
->pmd
);
1157 /* leave pmd empty until pte is filled */
1159 pgtable
= pgtable_trans_huge_withdraw(vma
->vm_mm
, vmf
->pmd
);
1160 pmd_populate(vma
->vm_mm
, &_pmd
, pgtable
);
1162 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1164 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1165 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1166 memcg
= (void *)page_private(pages
[i
]);
1167 set_page_private(pages
[i
], 0);
1168 page_add_new_anon_rmap(pages
[i
], vmf
->vma
, haddr
, false);
1169 mem_cgroup_commit_charge(pages
[i
], memcg
, false, false);
1170 lru_cache_add_active_or_unevictable(pages
[i
], vma
);
1171 vmf
->pte
= pte_offset_map(&_pmd
, haddr
);
1172 VM_BUG_ON(!pte_none(*vmf
->pte
));
1173 set_pte_at(vma
->vm_mm
, haddr
, vmf
->pte
, entry
);
1174 pte_unmap(vmf
->pte
);
1178 smp_wmb(); /* make pte visible before pmd */
1179 pmd_populate(vma
->vm_mm
, vmf
->pmd
, pgtable
);
1180 page_remove_rmap(page
, true);
1181 spin_unlock(vmf
->ptl
);
1183 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
1185 ret
|= VM_FAULT_WRITE
;
1192 spin_unlock(vmf
->ptl
);
1193 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
1194 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1195 memcg
= (void *)page_private(pages
[i
]);
1196 set_page_private(pages
[i
], 0);
1197 mem_cgroup_cancel_charge(pages
[i
], memcg
, false);
1204 int do_huge_pmd_wp_page(struct vm_fault
*vmf
, pmd_t orig_pmd
)
1206 struct vm_area_struct
*vma
= vmf
->vma
;
1207 struct page
*page
= NULL
, *new_page
;
1208 struct mem_cgroup
*memcg
;
1209 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1210 unsigned long mmun_start
; /* For mmu_notifiers */
1211 unsigned long mmun_end
; /* For mmu_notifiers */
1212 gfp_t huge_gfp
; /* for allocation and charge */
1215 vmf
->ptl
= pmd_lockptr(vma
->vm_mm
, vmf
->pmd
);
1216 VM_BUG_ON_VMA(!vma
->anon_vma
, vma
);
1217 if (is_huge_zero_pmd(orig_pmd
))
1219 spin_lock(vmf
->ptl
);
1220 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1223 page
= pmd_page(orig_pmd
);
1224 VM_BUG_ON_PAGE(!PageCompound(page
) || !PageHead(page
), page
);
1226 * We can only reuse the page if nobody else maps the huge page or it's
1229 if (page_trans_huge_mapcount(page
, NULL
) == 1) {
1231 entry
= pmd_mkyoung(orig_pmd
);
1232 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1233 if (pmdp_set_access_flags(vma
, haddr
, vmf
->pmd
, entry
, 1))
1234 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1235 ret
|= VM_FAULT_WRITE
;
1239 spin_unlock(vmf
->ptl
);
1241 if (transparent_hugepage_enabled(vma
) &&
1242 !transparent_hugepage_debug_cow()) {
1243 huge_gfp
= alloc_hugepage_direct_gfpmask(vma
);
1244 new_page
= alloc_hugepage_vma(huge_gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
1248 if (likely(new_page
)) {
1249 prep_transhuge_page(new_page
);
1252 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1253 ret
|= VM_FAULT_FALLBACK
;
1255 ret
= do_huge_pmd_wp_page_fallback(vmf
, orig_pmd
, page
);
1256 if (ret
& VM_FAULT_OOM
) {
1257 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1258 ret
|= VM_FAULT_FALLBACK
;
1262 count_vm_event(THP_FAULT_FALLBACK
);
1266 if (unlikely(mem_cgroup_try_charge(new_page
, vma
->vm_mm
,
1267 huge_gfp
, &memcg
, true))) {
1269 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1272 ret
|= VM_FAULT_FALLBACK
;
1273 count_vm_event(THP_FAULT_FALLBACK
);
1277 count_vm_event(THP_FAULT_ALLOC
);
1280 clear_huge_page(new_page
, haddr
, HPAGE_PMD_NR
);
1282 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
1283 __SetPageUptodate(new_page
);
1286 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1287 mmu_notifier_invalidate_range_start(vma
->vm_mm
, mmun_start
, mmun_end
);
1289 spin_lock(vmf
->ptl
);
1292 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
))) {
1293 spin_unlock(vmf
->ptl
);
1294 mem_cgroup_cancel_charge(new_page
, memcg
, true);
1299 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
1300 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1301 pmdp_huge_clear_flush_notify(vma
, haddr
, vmf
->pmd
);
1302 page_add_new_anon_rmap(new_page
, vma
, haddr
, true);
1303 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
1304 lru_cache_add_active_or_unevictable(new_page
, vma
);
1305 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
1306 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1308 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1310 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1311 page_remove_rmap(page
, true);
1314 ret
|= VM_FAULT_WRITE
;
1316 spin_unlock(vmf
->ptl
);
1318 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
1322 spin_unlock(vmf
->ptl
);
1327 * FOLL_FORCE can write to even unwritable pmd's, but only
1328 * after we've gone through a COW cycle and they are dirty.
1330 static inline bool can_follow_write_pmd(pmd_t pmd
, unsigned int flags
)
1332 return pmd_write(pmd
) ||
1333 ((flags
& FOLL_FORCE
) && (flags
& FOLL_COW
) && pmd_dirty(pmd
));
1336 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1341 struct mm_struct
*mm
= vma
->vm_mm
;
1342 struct page
*page
= NULL
;
1344 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1346 if (flags
& FOLL_WRITE
&& !can_follow_write_pmd(*pmd
, flags
))
1349 /* Avoid dumping huge zero page */
1350 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1351 return ERR_PTR(-EFAULT
);
1353 /* Full NUMA hinting faults to serialise migration in fault paths */
1354 if ((flags
& FOLL_NUMA
) && pmd_protnone(*pmd
))
1357 page
= pmd_page(*pmd
);
1358 VM_BUG_ON_PAGE(!PageHead(page
) && !is_zone_device_page(page
), page
);
1359 if (flags
& FOLL_TOUCH
)
1360 touch_pmd(vma
, addr
, pmd
);
1361 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1363 * We don't mlock() pte-mapped THPs. This way we can avoid
1364 * leaking mlocked pages into non-VM_LOCKED VMAs.
1368 * In most cases the pmd is the only mapping of the page as we
1369 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1370 * writable private mappings in populate_vma_page_range().
1372 * The only scenario when we have the page shared here is if we
1373 * mlocking read-only mapping shared over fork(). We skip
1374 * mlocking such pages.
1378 * We can expect PageDoubleMap() to be stable under page lock:
1379 * for file pages we set it in page_add_file_rmap(), which
1380 * requires page to be locked.
1383 if (PageAnon(page
) && compound_mapcount(page
) != 1)
1385 if (PageDoubleMap(page
) || !page
->mapping
)
1387 if (!trylock_page(page
))
1390 if (page
->mapping
&& !PageDoubleMap(page
))
1391 mlock_vma_page(page
);
1395 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1396 VM_BUG_ON_PAGE(!PageCompound(page
) && !is_zone_device_page(page
), page
);
1397 if (flags
& FOLL_GET
)
1404 /* NUMA hinting page fault entry point for trans huge pmds */
1405 int do_huge_pmd_numa_page(struct vm_fault
*vmf
, pmd_t pmd
)
1407 struct vm_area_struct
*vma
= vmf
->vma
;
1408 struct anon_vma
*anon_vma
= NULL
;
1410 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1411 int page_nid
= -1, this_nid
= numa_node_id();
1412 int target_nid
, last_cpupid
= -1;
1414 bool migrated
= false;
1418 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1419 if (unlikely(!pmd_same(pmd
, *vmf
->pmd
)))
1423 * If there are potential migrations, wait for completion and retry
1424 * without disrupting NUMA hinting information. Do not relock and
1425 * check_same as the page may no longer be mapped.
1427 if (unlikely(pmd_trans_migrating(*vmf
->pmd
))) {
1428 page
= pmd_page(*vmf
->pmd
);
1429 if (!get_page_unless_zero(page
))
1431 spin_unlock(vmf
->ptl
);
1432 wait_on_page_locked(page
);
1437 page
= pmd_page(pmd
);
1438 BUG_ON(is_huge_zero_page(page
));
1439 page_nid
= page_to_nid(page
);
1440 last_cpupid
= page_cpupid_last(page
);
1441 count_vm_numa_event(NUMA_HINT_FAULTS
);
1442 if (page_nid
== this_nid
) {
1443 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
1444 flags
|= TNF_FAULT_LOCAL
;
1447 /* See similar comment in do_numa_page for explanation */
1448 if (!pmd_savedwrite(pmd
))
1449 flags
|= TNF_NO_GROUP
;
1452 * Acquire the page lock to serialise THP migrations but avoid dropping
1453 * page_table_lock if at all possible
1455 page_locked
= trylock_page(page
);
1456 target_nid
= mpol_misplaced(page
, vma
, haddr
);
1457 if (target_nid
== -1) {
1458 /* If the page was locked, there are no parallel migrations */
1463 /* Migration could have started since the pmd_trans_migrating check */
1466 if (!get_page_unless_zero(page
))
1468 spin_unlock(vmf
->ptl
);
1469 wait_on_page_locked(page
);
1475 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1476 * to serialises splits
1479 spin_unlock(vmf
->ptl
);
1480 anon_vma
= page_lock_anon_vma_read(page
);
1482 /* Confirm the PMD did not change while page_table_lock was released */
1483 spin_lock(vmf
->ptl
);
1484 if (unlikely(!pmd_same(pmd
, *vmf
->pmd
))) {
1491 /* Bail if we fail to protect against THP splits for any reason */
1492 if (unlikely(!anon_vma
)) {
1499 * The page_table_lock above provides a memory barrier
1500 * with change_protection_range.
1502 if (mm_tlb_flush_pending(vma
->vm_mm
))
1503 flush_tlb_range(vma
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
1506 * Migrate the THP to the requested node, returns with page unlocked
1507 * and access rights restored.
1509 spin_unlock(vmf
->ptl
);
1510 migrated
= migrate_misplaced_transhuge_page(vma
->vm_mm
, vma
,
1511 vmf
->pmd
, pmd
, vmf
->address
, page
, target_nid
);
1513 flags
|= TNF_MIGRATED
;
1514 page_nid
= target_nid
;
1516 flags
|= TNF_MIGRATE_FAIL
;
1520 BUG_ON(!PageLocked(page
));
1521 was_writable
= pmd_savedwrite(pmd
);
1522 pmd
= pmd_modify(pmd
, vma
->vm_page_prot
);
1523 pmd
= pmd_mkyoung(pmd
);
1525 pmd
= pmd_mkwrite(pmd
);
1526 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, pmd
);
1527 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1530 spin_unlock(vmf
->ptl
);
1534 page_unlock_anon_vma_read(anon_vma
);
1537 task_numa_fault(last_cpupid
, page_nid
, HPAGE_PMD_NR
,
1544 * Return true if we do MADV_FREE successfully on entire pmd page.
1545 * Otherwise, return false.
1547 bool madvise_free_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1548 pmd_t
*pmd
, unsigned long addr
, unsigned long next
)
1553 struct mm_struct
*mm
= tlb
->mm
;
1556 tlb_remove_check_page_size_change(tlb
, HPAGE_PMD_SIZE
);
1558 ptl
= pmd_trans_huge_lock(pmd
, vma
);
1563 if (is_huge_zero_pmd(orig_pmd
))
1566 page
= pmd_page(orig_pmd
);
1568 * If other processes are mapping this page, we couldn't discard
1569 * the page unless they all do MADV_FREE so let's skip the page.
1571 if (page_mapcount(page
) != 1)
1574 if (!trylock_page(page
))
1578 * If user want to discard part-pages of THP, split it so MADV_FREE
1579 * will deactivate only them.
1581 if (next
- addr
!= HPAGE_PMD_SIZE
) {
1584 split_huge_page(page
);
1590 if (PageDirty(page
))
1591 ClearPageDirty(page
);
1594 if (pmd_young(orig_pmd
) || pmd_dirty(orig_pmd
)) {
1595 pmdp_invalidate(vma
, addr
, pmd
);
1596 orig_pmd
= pmd_mkold(orig_pmd
);
1597 orig_pmd
= pmd_mkclean(orig_pmd
);
1599 set_pmd_at(mm
, addr
, pmd
, orig_pmd
);
1600 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1603 mark_page_lazyfree(page
);
1611 static inline void zap_deposited_table(struct mm_struct
*mm
, pmd_t
*pmd
)
1615 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1616 pte_free(mm
, pgtable
);
1617 atomic_long_dec(&mm
->nr_ptes
);
1620 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1621 pmd_t
*pmd
, unsigned long addr
)
1626 tlb_remove_check_page_size_change(tlb
, HPAGE_PMD_SIZE
);
1628 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1632 * For architectures like ppc64 we look at deposited pgtable
1633 * when calling pmdp_huge_get_and_clear. So do the
1634 * pgtable_trans_huge_withdraw after finishing pmdp related
1637 orig_pmd
= pmdp_huge_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1639 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1640 if (vma_is_dax(vma
)) {
1641 if (arch_needs_pgtable_deposit())
1642 zap_deposited_table(tlb
->mm
, pmd
);
1644 if (is_huge_zero_pmd(orig_pmd
))
1645 tlb_remove_page_size(tlb
, pmd_page(orig_pmd
), HPAGE_PMD_SIZE
);
1646 } else if (is_huge_zero_pmd(orig_pmd
)) {
1647 zap_deposited_table(tlb
->mm
, pmd
);
1649 tlb_remove_page_size(tlb
, pmd_page(orig_pmd
), HPAGE_PMD_SIZE
);
1651 struct page
*page
= pmd_page(orig_pmd
);
1652 page_remove_rmap(page
, true);
1653 VM_BUG_ON_PAGE(page_mapcount(page
) < 0, page
);
1654 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1655 if (PageAnon(page
)) {
1656 zap_deposited_table(tlb
->mm
, pmd
);
1657 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1659 if (arch_needs_pgtable_deposit())
1660 zap_deposited_table(tlb
->mm
, pmd
);
1661 add_mm_counter(tlb
->mm
, MM_FILEPAGES
, -HPAGE_PMD_NR
);
1664 tlb_remove_page_size(tlb
, page
, HPAGE_PMD_SIZE
);
1669 #ifndef pmd_move_must_withdraw
1670 static inline int pmd_move_must_withdraw(spinlock_t
*new_pmd_ptl
,
1671 spinlock_t
*old_pmd_ptl
,
1672 struct vm_area_struct
*vma
)
1675 * With split pmd lock we also need to move preallocated
1676 * PTE page table if new_pmd is on different PMD page table.
1678 * We also don't deposit and withdraw tables for file pages.
1680 return (new_pmd_ptl
!= old_pmd_ptl
) && vma_is_anonymous(vma
);
1684 bool move_huge_pmd(struct vm_area_struct
*vma
, unsigned long old_addr
,
1685 unsigned long new_addr
, unsigned long old_end
,
1686 pmd_t
*old_pmd
, pmd_t
*new_pmd
, bool *need_flush
)
1688 spinlock_t
*old_ptl
, *new_ptl
;
1690 struct mm_struct
*mm
= vma
->vm_mm
;
1691 bool force_flush
= false;
1693 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1694 (new_addr
& ~HPAGE_PMD_MASK
) ||
1695 old_end
- old_addr
< HPAGE_PMD_SIZE
)
1699 * The destination pmd shouldn't be established, free_pgtables()
1700 * should have release it.
1702 if (WARN_ON(!pmd_none(*new_pmd
))) {
1703 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1708 * We don't have to worry about the ordering of src and dst
1709 * ptlocks because exclusive mmap_sem prevents deadlock.
1711 old_ptl
= __pmd_trans_huge_lock(old_pmd
, vma
);
1713 new_ptl
= pmd_lockptr(mm
, new_pmd
);
1714 if (new_ptl
!= old_ptl
)
1715 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
1716 pmd
= pmdp_huge_get_and_clear(mm
, old_addr
, old_pmd
);
1717 if (pmd_present(pmd
) && pmd_dirty(pmd
))
1719 VM_BUG_ON(!pmd_none(*new_pmd
));
1721 if (pmd_move_must_withdraw(new_ptl
, old_ptl
, vma
)) {
1723 pgtable
= pgtable_trans_huge_withdraw(mm
, old_pmd
);
1724 pgtable_trans_huge_deposit(mm
, new_pmd
, pgtable
);
1726 set_pmd_at(mm
, new_addr
, new_pmd
, pmd_mksoft_dirty(pmd
));
1727 if (new_ptl
!= old_ptl
)
1728 spin_unlock(new_ptl
);
1730 flush_tlb_range(vma
, old_addr
, old_addr
+ PMD_SIZE
);
1733 spin_unlock(old_ptl
);
1741 * - 0 if PMD could not be locked
1742 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1743 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1745 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1746 unsigned long addr
, pgprot_t newprot
, int prot_numa
)
1748 struct mm_struct
*mm
= vma
->vm_mm
;
1751 bool preserve_write
;
1754 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1758 preserve_write
= prot_numa
&& pmd_write(*pmd
);
1762 * Avoid trapping faults against the zero page. The read-only
1763 * data is likely to be read-cached on the local CPU and
1764 * local/remote hits to the zero page are not interesting.
1766 if (prot_numa
&& is_huge_zero_pmd(*pmd
))
1769 if (prot_numa
&& pmd_protnone(*pmd
))
1773 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1774 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1775 * which is also under down_read(mmap_sem):
1778 * change_huge_pmd(prot_numa=1)
1779 * pmdp_huge_get_and_clear_notify()
1780 * madvise_dontneed()
1782 * pmd_trans_huge(*pmd) == 0 (without ptl)
1785 * // pmd is re-established
1787 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1788 * which may break userspace.
1790 * pmdp_invalidate() is required to make sure we don't miss
1791 * dirty/young flags set by hardware.
1794 pmdp_invalidate(vma
, addr
, pmd
);
1797 * Recover dirty/young flags. It relies on pmdp_invalidate to not
1800 if (pmd_dirty(*pmd
))
1801 entry
= pmd_mkdirty(entry
);
1802 if (pmd_young(*pmd
))
1803 entry
= pmd_mkyoung(entry
);
1805 entry
= pmd_modify(entry
, newprot
);
1807 entry
= pmd_mk_savedwrite(entry
);
1809 set_pmd_at(mm
, addr
, pmd
, entry
);
1810 BUG_ON(vma_is_anonymous(vma
) && !preserve_write
&& pmd_write(entry
));
1817 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1819 * Note that if it returns page table lock pointer, this routine returns without
1820 * unlocking page table lock. So callers must unlock it.
1822 spinlock_t
*__pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1825 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
1826 if (likely(pmd_trans_huge(*pmd
) || pmd_devmap(*pmd
)))
1833 * Returns true if a given pud maps a thp, false otherwise.
1835 * Note that if it returns true, this routine returns without unlocking page
1836 * table lock. So callers must unlock it.
1838 spinlock_t
*__pud_trans_huge_lock(pud_t
*pud
, struct vm_area_struct
*vma
)
1842 ptl
= pud_lock(vma
->vm_mm
, pud
);
1843 if (likely(pud_trans_huge(*pud
) || pud_devmap(*pud
)))
1849 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1850 int zap_huge_pud(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1851 pud_t
*pud
, unsigned long addr
)
1856 ptl
= __pud_trans_huge_lock(pud
, vma
);
1860 * For architectures like ppc64 we look at deposited pgtable
1861 * when calling pudp_huge_get_and_clear. So do the
1862 * pgtable_trans_huge_withdraw after finishing pudp related
1865 orig_pud
= pudp_huge_get_and_clear_full(tlb
->mm
, addr
, pud
,
1867 tlb_remove_pud_tlb_entry(tlb
, pud
, addr
);
1868 if (vma_is_dax(vma
)) {
1870 /* No zero page support yet */
1872 /* No support for anonymous PUD pages yet */
1878 static void __split_huge_pud_locked(struct vm_area_struct
*vma
, pud_t
*pud
,
1879 unsigned long haddr
)
1881 VM_BUG_ON(haddr
& ~HPAGE_PUD_MASK
);
1882 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
1883 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PUD_SIZE
, vma
);
1884 VM_BUG_ON(!pud_trans_huge(*pud
) && !pud_devmap(*pud
));
1886 count_vm_event(THP_SPLIT_PUD
);
1888 pudp_huge_clear_flush_notify(vma
, haddr
, pud
);
1891 void __split_huge_pud(struct vm_area_struct
*vma
, pud_t
*pud
,
1892 unsigned long address
)
1895 struct mm_struct
*mm
= vma
->vm_mm
;
1896 unsigned long haddr
= address
& HPAGE_PUD_MASK
;
1898 mmu_notifier_invalidate_range_start(mm
, haddr
, haddr
+ HPAGE_PUD_SIZE
);
1899 ptl
= pud_lock(mm
, pud
);
1900 if (unlikely(!pud_trans_huge(*pud
) && !pud_devmap(*pud
)))
1902 __split_huge_pud_locked(vma
, pud
, haddr
);
1906 mmu_notifier_invalidate_range_end(mm
, haddr
, haddr
+ HPAGE_PUD_SIZE
);
1908 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1910 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
1911 unsigned long haddr
, pmd_t
*pmd
)
1913 struct mm_struct
*mm
= vma
->vm_mm
;
1918 /* leave pmd empty until pte is filled */
1919 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
1921 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1922 pmd_populate(mm
, &_pmd
, pgtable
);
1924 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1926 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
1927 entry
= pte_mkspecial(entry
);
1928 pte
= pte_offset_map(&_pmd
, haddr
);
1929 VM_BUG_ON(!pte_none(*pte
));
1930 set_pte_at(mm
, haddr
, pte
, entry
);
1933 smp_wmb(); /* make pte visible before pmd */
1934 pmd_populate(mm
, pmd
, pgtable
);
1937 static void __split_huge_pmd_locked(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1938 unsigned long haddr
, bool freeze
)
1940 struct mm_struct
*mm
= vma
->vm_mm
;
1944 bool young
, write
, dirty
, soft_dirty
;
1948 VM_BUG_ON(haddr
& ~HPAGE_PMD_MASK
);
1949 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
1950 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
, vma
);
1951 VM_BUG_ON(!pmd_trans_huge(*pmd
) && !pmd_devmap(*pmd
));
1953 count_vm_event(THP_SPLIT_PMD
);
1955 if (!vma_is_anonymous(vma
)) {
1956 _pmd
= pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
1958 * We are going to unmap this huge page. So
1959 * just go ahead and zap it
1961 if (arch_needs_pgtable_deposit())
1962 zap_deposited_table(mm
, pmd
);
1963 if (vma_is_dax(vma
))
1965 page
= pmd_page(_pmd
);
1966 if (!PageReferenced(page
) && pmd_young(_pmd
))
1967 SetPageReferenced(page
);
1968 page_remove_rmap(page
, true);
1970 add_mm_counter(mm
, MM_FILEPAGES
, -HPAGE_PMD_NR
);
1972 } else if (is_huge_zero_pmd(*pmd
)) {
1973 return __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
1976 page
= pmd_page(*pmd
);
1977 VM_BUG_ON_PAGE(!page_count(page
), page
);
1978 page_ref_add(page
, HPAGE_PMD_NR
- 1);
1979 write
= pmd_write(*pmd
);
1980 young
= pmd_young(*pmd
);
1981 dirty
= pmd_dirty(*pmd
);
1982 soft_dirty
= pmd_soft_dirty(*pmd
);
1984 pmdp_huge_split_prepare(vma
, haddr
, pmd
);
1985 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1986 pmd_populate(mm
, &_pmd
, pgtable
);
1988 for (i
= 0, addr
= haddr
; i
< HPAGE_PMD_NR
; i
++, addr
+= PAGE_SIZE
) {
1991 * Note that NUMA hinting access restrictions are not
1992 * transferred to avoid any possibility of altering
1993 * permissions across VMAs.
1996 swp_entry_t swp_entry
;
1997 swp_entry
= make_migration_entry(page
+ i
, write
);
1998 entry
= swp_entry_to_pte(swp_entry
);
2000 entry
= pte_swp_mksoft_dirty(entry
);
2002 entry
= mk_pte(page
+ i
, READ_ONCE(vma
->vm_page_prot
));
2003 entry
= maybe_mkwrite(entry
, vma
);
2005 entry
= pte_wrprotect(entry
);
2007 entry
= pte_mkold(entry
);
2009 entry
= pte_mksoft_dirty(entry
);
2012 SetPageDirty(page
+ i
);
2013 pte
= pte_offset_map(&_pmd
, addr
);
2014 BUG_ON(!pte_none(*pte
));
2015 set_pte_at(mm
, addr
, pte
, entry
);
2016 atomic_inc(&page
[i
]._mapcount
);
2021 * Set PG_double_map before dropping compound_mapcount to avoid
2022 * false-negative page_mapped().
2024 if (compound_mapcount(page
) > 1 && !TestSetPageDoubleMap(page
)) {
2025 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2026 atomic_inc(&page
[i
]._mapcount
);
2029 if (atomic_add_negative(-1, compound_mapcount_ptr(page
))) {
2030 /* Last compound_mapcount is gone. */
2031 __dec_node_page_state(page
, NR_ANON_THPS
);
2032 if (TestClearPageDoubleMap(page
)) {
2033 /* No need in mapcount reference anymore */
2034 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2035 atomic_dec(&page
[i
]._mapcount
);
2039 smp_wmb(); /* make pte visible before pmd */
2041 * Up to this point the pmd is present and huge and userland has the
2042 * whole access to the hugepage during the split (which happens in
2043 * place). If we overwrite the pmd with the not-huge version pointing
2044 * to the pte here (which of course we could if all CPUs were bug
2045 * free), userland could trigger a small page size TLB miss on the
2046 * small sized TLB while the hugepage TLB entry is still established in
2047 * the huge TLB. Some CPU doesn't like that.
2048 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2049 * 383 on page 93. Intel should be safe but is also warns that it's
2050 * only safe if the permission and cache attributes of the two entries
2051 * loaded in the two TLB is identical (which should be the case here).
2052 * But it is generally safer to never allow small and huge TLB entries
2053 * for the same virtual address to be loaded simultaneously. So instead
2054 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2055 * current pmd notpresent (atomically because here the pmd_trans_huge
2056 * and pmd_trans_splitting must remain set at all times on the pmd
2057 * until the split is complete for this pmd), then we flush the SMP TLB
2058 * and finally we write the non-huge version of the pmd entry with
2061 pmdp_invalidate(vma
, haddr
, pmd
);
2062 pmd_populate(mm
, pmd
, pgtable
);
2065 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2066 page_remove_rmap(page
+ i
, false);
2072 void __split_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2073 unsigned long address
, bool freeze
, struct page
*page
)
2076 struct mm_struct
*mm
= vma
->vm_mm
;
2077 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
2079 mmu_notifier_invalidate_range_start(mm
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
2080 ptl
= pmd_lock(mm
, pmd
);
2083 * If caller asks to setup a migration entries, we need a page to check
2084 * pmd against. Otherwise we can end up replacing wrong page.
2086 VM_BUG_ON(freeze
&& !page
);
2087 if (page
&& page
!= pmd_page(*pmd
))
2090 if (pmd_trans_huge(*pmd
)) {
2091 page
= pmd_page(*pmd
);
2092 if (PageMlocked(page
))
2093 clear_page_mlock(page
);
2094 } else if (!pmd_devmap(*pmd
))
2096 __split_huge_pmd_locked(vma
, pmd
, haddr
, freeze
);
2099 mmu_notifier_invalidate_range_end(mm
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
2102 void split_huge_pmd_address(struct vm_area_struct
*vma
, unsigned long address
,
2103 bool freeze
, struct page
*page
)
2110 pgd
= pgd_offset(vma
->vm_mm
, address
);
2111 if (!pgd_present(*pgd
))
2114 p4d
= p4d_offset(pgd
, address
);
2115 if (!p4d_present(*p4d
))
2118 pud
= pud_offset(p4d
, address
);
2119 if (!pud_present(*pud
))
2122 pmd
= pmd_offset(pud
, address
);
2124 __split_huge_pmd(vma
, pmd
, address
, freeze
, page
);
2127 void vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2128 unsigned long start
,
2133 * If the new start address isn't hpage aligned and it could
2134 * previously contain an hugepage: check if we need to split
2137 if (start
& ~HPAGE_PMD_MASK
&&
2138 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2139 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2140 split_huge_pmd_address(vma
, start
, false, NULL
);
2143 * If the new end address isn't hpage aligned and it could
2144 * previously contain an hugepage: check if we need to split
2147 if (end
& ~HPAGE_PMD_MASK
&&
2148 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2149 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2150 split_huge_pmd_address(vma
, end
, false, NULL
);
2153 * If we're also updating the vma->vm_next->vm_start, if the new
2154 * vm_next->vm_start isn't page aligned and it could previously
2155 * contain an hugepage: check if we need to split an huge pmd.
2157 if (adjust_next
> 0) {
2158 struct vm_area_struct
*next
= vma
->vm_next
;
2159 unsigned long nstart
= next
->vm_start
;
2160 nstart
+= adjust_next
<< PAGE_SHIFT
;
2161 if (nstart
& ~HPAGE_PMD_MASK
&&
2162 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2163 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2164 split_huge_pmd_address(next
, nstart
, false, NULL
);
2168 static void freeze_page(struct page
*page
)
2170 enum ttu_flags ttu_flags
= TTU_IGNORE_MLOCK
| TTU_IGNORE_ACCESS
|
2171 TTU_RMAP_LOCKED
| TTU_SPLIT_HUGE_PMD
;
2174 VM_BUG_ON_PAGE(!PageHead(page
), page
);
2177 ttu_flags
|= TTU_MIGRATION
;
2179 unmap_success
= try_to_unmap(page
, ttu_flags
);
2180 VM_BUG_ON_PAGE(!unmap_success
, page
);
2183 static void unfreeze_page(struct page
*page
)
2186 if (PageTransHuge(page
)) {
2187 remove_migration_ptes(page
, page
, true);
2189 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2190 remove_migration_ptes(page
+ i
, page
+ i
, true);
2194 static void __split_huge_page_tail(struct page
*head
, int tail
,
2195 struct lruvec
*lruvec
, struct list_head
*list
)
2197 struct page
*page_tail
= head
+ tail
;
2199 VM_BUG_ON_PAGE(atomic_read(&page_tail
->_mapcount
) != -1, page_tail
);
2200 VM_BUG_ON_PAGE(page_ref_count(page_tail
) != 0, page_tail
);
2203 * tail_page->_refcount is zero and not changing from under us. But
2204 * get_page_unless_zero() may be running from under us on the
2205 * tail_page. If we used atomic_set() below instead of atomic_inc() or
2206 * atomic_add(), we would then run atomic_set() concurrently with
2207 * get_page_unless_zero(), and atomic_set() is implemented in C not
2208 * using locked ops. spin_unlock on x86 sometime uses locked ops
2209 * because of PPro errata 66, 92, so unless somebody can guarantee
2210 * atomic_set() here would be safe on all archs (and not only on x86),
2211 * it's safer to use atomic_inc()/atomic_add().
2213 if (PageAnon(head
) && !PageSwapCache(head
)) {
2214 page_ref_inc(page_tail
);
2216 /* Additional pin to radix tree */
2217 page_ref_add(page_tail
, 2);
2220 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
;
2221 page_tail
->flags
|= (head
->flags
&
2222 ((1L << PG_referenced
) |
2223 (1L << PG_swapbacked
) |
2224 (1L << PG_swapcache
) |
2225 (1L << PG_mlocked
) |
2226 (1L << PG_uptodate
) |
2229 (1L << PG_unevictable
) |
2233 * After clearing PageTail the gup refcount can be released.
2234 * Page flags also must be visible before we make the page non-compound.
2238 clear_compound_head(page_tail
);
2240 if (page_is_young(head
))
2241 set_page_young(page_tail
);
2242 if (page_is_idle(head
))
2243 set_page_idle(page_tail
);
2245 /* ->mapping in first tail page is compound_mapcount */
2246 VM_BUG_ON_PAGE(tail
> 2 && page_tail
->mapping
!= TAIL_MAPPING
,
2248 page_tail
->mapping
= head
->mapping
;
2250 page_tail
->index
= head
->index
+ tail
;
2251 page_cpupid_xchg_last(page_tail
, page_cpupid_last(head
));
2252 lru_add_page_tail(head
, page_tail
, lruvec
, list
);
2255 static void __split_huge_page(struct page
*page
, struct list_head
*list
,
2256 unsigned long flags
)
2258 struct page
*head
= compound_head(page
);
2259 struct zone
*zone
= page_zone(head
);
2260 struct lruvec
*lruvec
;
2264 lruvec
= mem_cgroup_page_lruvec(head
, zone
->zone_pgdat
);
2266 /* complete memcg works before add pages to LRU */
2267 mem_cgroup_split_huge_fixup(head
);
2269 if (!PageAnon(page
))
2270 end
= DIV_ROUND_UP(i_size_read(head
->mapping
->host
), PAGE_SIZE
);
2272 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
2273 __split_huge_page_tail(head
, i
, lruvec
, list
);
2274 /* Some pages can be beyond i_size: drop them from page cache */
2275 if (head
[i
].index
>= end
) {
2276 __ClearPageDirty(head
+ i
);
2277 __delete_from_page_cache(head
+ i
, NULL
);
2278 if (IS_ENABLED(CONFIG_SHMEM
) && PageSwapBacked(head
))
2279 shmem_uncharge(head
->mapping
->host
, 1);
2284 ClearPageCompound(head
);
2285 /* See comment in __split_huge_page_tail() */
2286 if (PageAnon(head
)) {
2287 /* Additional pin to radix tree of swap cache */
2288 if (PageSwapCache(head
))
2289 page_ref_add(head
, 2);
2293 /* Additional pin to radix tree */
2294 page_ref_add(head
, 2);
2295 spin_unlock(&head
->mapping
->tree_lock
);
2298 spin_unlock_irqrestore(zone_lru_lock(page_zone(head
)), flags
);
2300 unfreeze_page(head
);
2302 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2303 struct page
*subpage
= head
+ i
;
2304 if (subpage
== page
)
2306 unlock_page(subpage
);
2309 * Subpages may be freed if there wasn't any mapping
2310 * like if add_to_swap() is running on a lru page that
2311 * had its mapping zapped. And freeing these pages
2312 * requires taking the lru_lock so we do the put_page
2313 * of the tail pages after the split is complete.
2319 int total_mapcount(struct page
*page
)
2321 int i
, compound
, ret
;
2323 VM_BUG_ON_PAGE(PageTail(page
), page
);
2325 if (likely(!PageCompound(page
)))
2326 return atomic_read(&page
->_mapcount
) + 1;
2328 compound
= compound_mapcount(page
);
2332 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2333 ret
+= atomic_read(&page
[i
]._mapcount
) + 1;
2334 /* File pages has compound_mapcount included in _mapcount */
2335 if (!PageAnon(page
))
2336 return ret
- compound
* HPAGE_PMD_NR
;
2337 if (PageDoubleMap(page
))
2338 ret
-= HPAGE_PMD_NR
;
2343 * This calculates accurately how many mappings a transparent hugepage
2344 * has (unlike page_mapcount() which isn't fully accurate). This full
2345 * accuracy is primarily needed to know if copy-on-write faults can
2346 * reuse the page and change the mapping to read-write instead of
2347 * copying them. At the same time this returns the total_mapcount too.
2349 * The function returns the highest mapcount any one of the subpages
2350 * has. If the return value is one, even if different processes are
2351 * mapping different subpages of the transparent hugepage, they can
2352 * all reuse it, because each process is reusing a different subpage.
2354 * The total_mapcount is instead counting all virtual mappings of the
2355 * subpages. If the total_mapcount is equal to "one", it tells the
2356 * caller all mappings belong to the same "mm" and in turn the
2357 * anon_vma of the transparent hugepage can become the vma->anon_vma
2358 * local one as no other process may be mapping any of the subpages.
2360 * It would be more accurate to replace page_mapcount() with
2361 * page_trans_huge_mapcount(), however we only use
2362 * page_trans_huge_mapcount() in the copy-on-write faults where we
2363 * need full accuracy to avoid breaking page pinning, because
2364 * page_trans_huge_mapcount() is slower than page_mapcount().
2366 int page_trans_huge_mapcount(struct page
*page
, int *total_mapcount
)
2368 int i
, ret
, _total_mapcount
, mapcount
;
2370 /* hugetlbfs shouldn't call it */
2371 VM_BUG_ON_PAGE(PageHuge(page
), page
);
2373 if (likely(!PageTransCompound(page
))) {
2374 mapcount
= atomic_read(&page
->_mapcount
) + 1;
2376 *total_mapcount
= mapcount
;
2380 page
= compound_head(page
);
2382 _total_mapcount
= ret
= 0;
2383 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2384 mapcount
= atomic_read(&page
[i
]._mapcount
) + 1;
2385 ret
= max(ret
, mapcount
);
2386 _total_mapcount
+= mapcount
;
2388 if (PageDoubleMap(page
)) {
2390 _total_mapcount
-= HPAGE_PMD_NR
;
2392 mapcount
= compound_mapcount(page
);
2394 _total_mapcount
+= mapcount
;
2396 *total_mapcount
= _total_mapcount
;
2400 /* Racy check whether the huge page can be split */
2401 bool can_split_huge_page(struct page
*page
, int *pextra_pins
)
2405 /* Additional pins from radix tree */
2407 extra_pins
= PageSwapCache(page
) ? HPAGE_PMD_NR
: 0;
2409 extra_pins
= HPAGE_PMD_NR
;
2411 *pextra_pins
= extra_pins
;
2412 return total_mapcount(page
) == page_count(page
) - extra_pins
- 1;
2416 * This function splits huge page into normal pages. @page can point to any
2417 * subpage of huge page to split. Split doesn't change the position of @page.
2419 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2420 * The huge page must be locked.
2422 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2424 * Both head page and tail pages will inherit mapping, flags, and so on from
2427 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2428 * they are not mapped.
2430 * Returns 0 if the hugepage is split successfully.
2431 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2434 int split_huge_page_to_list(struct page
*page
, struct list_head
*list
)
2436 struct page
*head
= compound_head(page
);
2437 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(head
));
2438 struct anon_vma
*anon_vma
= NULL
;
2439 struct address_space
*mapping
= NULL
;
2440 int count
, mapcount
, extra_pins
, ret
;
2442 unsigned long flags
;
2444 VM_BUG_ON_PAGE(is_huge_zero_page(page
), page
);
2445 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2446 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
2448 if (PageAnon(head
)) {
2450 * The caller does not necessarily hold an mmap_sem that would
2451 * prevent the anon_vma disappearing so we first we take a
2452 * reference to it and then lock the anon_vma for write. This
2453 * is similar to page_lock_anon_vma_read except the write lock
2454 * is taken to serialise against parallel split or collapse
2457 anon_vma
= page_get_anon_vma(head
);
2463 anon_vma_lock_write(anon_vma
);
2465 mapping
= head
->mapping
;
2474 i_mmap_lock_read(mapping
);
2478 * Racy check if we can split the page, before freeze_page() will
2481 if (!can_split_huge_page(head
, &extra_pins
)) {
2486 mlocked
= PageMlocked(page
);
2488 VM_BUG_ON_PAGE(compound_mapcount(head
), head
);
2490 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2494 /* prevent PageLRU to go away from under us, and freeze lru stats */
2495 spin_lock_irqsave(zone_lru_lock(page_zone(head
)), flags
);
2500 spin_lock(&mapping
->tree_lock
);
2501 pslot
= radix_tree_lookup_slot(&mapping
->page_tree
,
2504 * Check if the head page is present in radix tree.
2505 * We assume all tail are present too, if head is there.
2507 if (radix_tree_deref_slot_protected(pslot
,
2508 &mapping
->tree_lock
) != head
)
2512 /* Prevent deferred_split_scan() touching ->_refcount */
2513 spin_lock(&pgdata
->split_queue_lock
);
2514 count
= page_count(head
);
2515 mapcount
= total_mapcount(head
);
2516 if (!mapcount
&& page_ref_freeze(head
, 1 + extra_pins
)) {
2517 if (!list_empty(page_deferred_list(head
))) {
2518 pgdata
->split_queue_len
--;
2519 list_del(page_deferred_list(head
));
2522 __dec_node_page_state(page
, NR_SHMEM_THPS
);
2523 spin_unlock(&pgdata
->split_queue_lock
);
2524 __split_huge_page(page
, list
, flags
);
2527 if (IS_ENABLED(CONFIG_DEBUG_VM
) && mapcount
) {
2528 pr_alert("total_mapcount: %u, page_count(): %u\n",
2531 dump_page(head
, NULL
);
2532 dump_page(page
, "total_mapcount(head) > 0");
2535 spin_unlock(&pgdata
->split_queue_lock
);
2537 spin_unlock(&mapping
->tree_lock
);
2538 spin_unlock_irqrestore(zone_lru_lock(page_zone(head
)), flags
);
2539 unfreeze_page(head
);
2545 anon_vma_unlock_write(anon_vma
);
2546 put_anon_vma(anon_vma
);
2549 i_mmap_unlock_read(mapping
);
2551 count_vm_event(!ret
? THP_SPLIT_PAGE
: THP_SPLIT_PAGE_FAILED
);
2555 void free_transhuge_page(struct page
*page
)
2557 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
2558 unsigned long flags
;
2560 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2561 if (!list_empty(page_deferred_list(page
))) {
2562 pgdata
->split_queue_len
--;
2563 list_del(page_deferred_list(page
));
2565 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2566 free_compound_page(page
);
2569 void deferred_split_huge_page(struct page
*page
)
2571 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
2572 unsigned long flags
;
2574 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
2576 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2577 if (list_empty(page_deferred_list(page
))) {
2578 count_vm_event(THP_DEFERRED_SPLIT_PAGE
);
2579 list_add_tail(page_deferred_list(page
), &pgdata
->split_queue
);
2580 pgdata
->split_queue_len
++;
2582 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2585 static unsigned long deferred_split_count(struct shrinker
*shrink
,
2586 struct shrink_control
*sc
)
2588 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2589 return ACCESS_ONCE(pgdata
->split_queue_len
);
2592 static unsigned long deferred_split_scan(struct shrinker
*shrink
,
2593 struct shrink_control
*sc
)
2595 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2596 unsigned long flags
;
2597 LIST_HEAD(list
), *pos
, *next
;
2601 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2602 /* Take pin on all head pages to avoid freeing them under us */
2603 list_for_each_safe(pos
, next
, &pgdata
->split_queue
) {
2604 page
= list_entry((void *)pos
, struct page
, mapping
);
2605 page
= compound_head(page
);
2606 if (get_page_unless_zero(page
)) {
2607 list_move(page_deferred_list(page
), &list
);
2609 /* We lost race with put_compound_page() */
2610 list_del_init(page_deferred_list(page
));
2611 pgdata
->split_queue_len
--;
2613 if (!--sc
->nr_to_scan
)
2616 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2618 list_for_each_safe(pos
, next
, &list
) {
2619 page
= list_entry((void *)pos
, struct page
, mapping
);
2621 /* split_huge_page() removes page from list on success */
2622 if (!split_huge_page(page
))
2628 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2629 list_splice_tail(&list
, &pgdata
->split_queue
);
2630 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2633 * Stop shrinker if we didn't split any page, but the queue is empty.
2634 * This can happen if pages were freed under us.
2636 if (!split
&& list_empty(&pgdata
->split_queue
))
2641 static struct shrinker deferred_split_shrinker
= {
2642 .count_objects
= deferred_split_count
,
2643 .scan_objects
= deferred_split_scan
,
2644 .seeks
= DEFAULT_SEEKS
,
2645 .flags
= SHRINKER_NUMA_AWARE
,
2648 #ifdef CONFIG_DEBUG_FS
2649 static int split_huge_pages_set(void *data
, u64 val
)
2653 unsigned long pfn
, max_zone_pfn
;
2654 unsigned long total
= 0, split
= 0;
2659 for_each_populated_zone(zone
) {
2660 max_zone_pfn
= zone_end_pfn(zone
);
2661 for (pfn
= zone
->zone_start_pfn
; pfn
< max_zone_pfn
; pfn
++) {
2662 if (!pfn_valid(pfn
))
2665 page
= pfn_to_page(pfn
);
2666 if (!get_page_unless_zero(page
))
2669 if (zone
!= page_zone(page
))
2672 if (!PageHead(page
) || PageHuge(page
) || !PageLRU(page
))
2677 if (!split_huge_page(page
))
2685 pr_info("%lu of %lu THP split\n", split
, total
);
2689 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops
, NULL
, split_huge_pages_set
,
2692 static int __init
split_huge_pages_debugfs(void)
2696 ret
= debugfs_create_file("split_huge_pages", 0200, NULL
, NULL
,
2697 &split_huge_pages_fops
);
2699 pr_warn("Failed to create split_huge_pages in debugfs");
2702 late_initcall(split_huge_pages_debugfs
);