2 * Copyright (C) 2009 Red Hat, Inc.
4 * This work is licensed under the terms of the GNU GPL, version 2. See
5 * the COPYING file in the top-level directory.
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 #include <linux/sched.h>
12 #include <linux/sched/coredump.h>
13 #include <linux/sched/numa_balancing.h>
14 #include <linux/highmem.h>
15 #include <linux/hugetlb.h>
16 #include <linux/mmu_notifier.h>
17 #include <linux/rmap.h>
18 #include <linux/swap.h>
19 #include <linux/shrinker.h>
20 #include <linux/mm_inline.h>
21 #include <linux/swapops.h>
22 #include <linux/dax.h>
23 #include <linux/khugepaged.h>
24 #include <linux/freezer.h>
25 #include <linux/pfn_t.h>
26 #include <linux/mman.h>
27 #include <linux/memremap.h>
28 #include <linux/pagemap.h>
29 #include <linux/debugfs.h>
30 #include <linux/migrate.h>
31 #include <linux/hashtable.h>
32 #include <linux/userfaultfd_k.h>
33 #include <linux/page_idle.h>
34 #include <linux/shmem_fs.h>
35 #include <linux/oom.h>
38 #include <asm/pgalloc.h>
42 * By default transparent hugepage support is disabled in order that avoid
43 * to risk increase the memory footprint of applications without a guaranteed
44 * benefit. When transparent hugepage support is enabled, is for all mappings,
45 * and khugepaged scans all mappings.
46 * Defrag is invoked by khugepaged hugepage allocations and by page faults
47 * for all hugepage allocations.
49 unsigned long transparent_hugepage_flags __read_mostly
=
50 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
51 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
53 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
54 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
)|
57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
)|
58 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
60 static struct shrinker deferred_split_shrinker
;
62 static atomic_t huge_zero_refcount
;
63 struct page
*huge_zero_page __read_mostly
;
65 static struct page
*get_huge_zero_page(void)
67 struct page
*zero_page
;
69 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
70 return READ_ONCE(huge_zero_page
);
72 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
75 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
78 count_vm_event(THP_ZERO_PAGE_ALLOC
);
80 if (cmpxchg(&huge_zero_page
, NULL
, zero_page
)) {
82 __free_pages(zero_page
, compound_order(zero_page
));
86 /* We take additional reference here. It will be put back by shrinker */
87 atomic_set(&huge_zero_refcount
, 2);
89 return READ_ONCE(huge_zero_page
);
92 static void put_huge_zero_page(void)
95 * Counter should never go to zero here. Only shrinker can put
98 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
101 struct page
*mm_get_huge_zero_page(struct mm_struct
*mm
)
103 if (test_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
104 return READ_ONCE(huge_zero_page
);
106 if (!get_huge_zero_page())
109 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
110 put_huge_zero_page();
112 return READ_ONCE(huge_zero_page
);
115 void mm_put_huge_zero_page(struct mm_struct
*mm
)
117 if (test_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
118 put_huge_zero_page();
121 static unsigned long shrink_huge_zero_page_count(struct shrinker
*shrink
,
122 struct shrink_control
*sc
)
124 /* we can free zero page only if last reference remains */
125 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
128 static unsigned long shrink_huge_zero_page_scan(struct shrinker
*shrink
,
129 struct shrink_control
*sc
)
131 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
132 struct page
*zero_page
= xchg(&huge_zero_page
, NULL
);
133 BUG_ON(zero_page
== NULL
);
134 __free_pages(zero_page
, compound_order(zero_page
));
141 static struct shrinker huge_zero_page_shrinker
= {
142 .count_objects
= shrink_huge_zero_page_count
,
143 .scan_objects
= shrink_huge_zero_page_scan
,
144 .seeks
= DEFAULT_SEEKS
,
148 static ssize_t
enabled_show(struct kobject
*kobj
,
149 struct kobj_attribute
*attr
, char *buf
)
151 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
))
152 return sprintf(buf
, "[always] madvise never\n");
153 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
154 return sprintf(buf
, "always [madvise] never\n");
156 return sprintf(buf
, "always madvise [never]\n");
159 static ssize_t
enabled_store(struct kobject
*kobj
,
160 struct kobj_attribute
*attr
,
161 const char *buf
, size_t count
)
165 if (!memcmp("always", buf
,
166 min(sizeof("always")-1, count
))) {
167 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
168 set_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
169 } else if (!memcmp("madvise", buf
,
170 min(sizeof("madvise")-1, count
))) {
171 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
172 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
173 } else if (!memcmp("never", buf
,
174 min(sizeof("never")-1, count
))) {
175 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
176 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
181 int err
= start_stop_khugepaged();
187 static struct kobj_attribute enabled_attr
=
188 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
190 ssize_t
single_hugepage_flag_show(struct kobject
*kobj
,
191 struct kobj_attribute
*attr
, char *buf
,
192 enum transparent_hugepage_flag flag
)
194 return sprintf(buf
, "%d\n",
195 !!test_bit(flag
, &transparent_hugepage_flags
));
198 ssize_t
single_hugepage_flag_store(struct kobject
*kobj
,
199 struct kobj_attribute
*attr
,
200 const char *buf
, size_t count
,
201 enum transparent_hugepage_flag flag
)
206 ret
= kstrtoul(buf
, 10, &value
);
213 set_bit(flag
, &transparent_hugepage_flags
);
215 clear_bit(flag
, &transparent_hugepage_flags
);
220 static ssize_t
defrag_show(struct kobject
*kobj
,
221 struct kobj_attribute
*attr
, char *buf
)
223 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
224 return sprintf(buf
, "[always] defer defer+madvise madvise never\n");
225 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
226 return sprintf(buf
, "always [defer] defer+madvise madvise never\n");
227 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
))
228 return sprintf(buf
, "always defer [defer+madvise] madvise never\n");
229 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
230 return sprintf(buf
, "always defer defer+madvise [madvise] never\n");
231 return sprintf(buf
, "always defer defer+madvise madvise [never]\n");
234 static ssize_t
defrag_store(struct kobject
*kobj
,
235 struct kobj_attribute
*attr
,
236 const char *buf
, size_t count
)
238 if (!memcmp("always", buf
,
239 min(sizeof("always")-1, count
))) {
240 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
241 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
242 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
243 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
244 } else if (!memcmp("defer+madvise", buf
,
245 min(sizeof("defer+madvise")-1, count
))) {
246 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
247 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
248 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
249 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
250 } else if (!memcmp("defer", buf
,
251 min(sizeof("defer")-1, count
))) {
252 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
253 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
254 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
255 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
256 } else if (!memcmp("madvise", buf
,
257 min(sizeof("madvise")-1, count
))) {
258 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
259 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
260 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
261 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
262 } else if (!memcmp("never", buf
,
263 min(sizeof("never")-1, count
))) {
264 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
265 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
266 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
273 static struct kobj_attribute defrag_attr
=
274 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
276 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
277 struct kobj_attribute
*attr
, char *buf
)
279 return single_hugepage_flag_show(kobj
, attr
, buf
,
280 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
282 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
283 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
285 return single_hugepage_flag_store(kobj
, attr
, buf
, count
,
286 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
288 static struct kobj_attribute use_zero_page_attr
=
289 __ATTR(use_zero_page
, 0644, use_zero_page_show
, use_zero_page_store
);
291 static ssize_t
hpage_pmd_size_show(struct kobject
*kobj
,
292 struct kobj_attribute
*attr
, char *buf
)
294 return sprintf(buf
, "%lu\n", HPAGE_PMD_SIZE
);
296 static struct kobj_attribute hpage_pmd_size_attr
=
297 __ATTR_RO(hpage_pmd_size
);
299 #ifdef CONFIG_DEBUG_VM
300 static ssize_t
debug_cow_show(struct kobject
*kobj
,
301 struct kobj_attribute
*attr
, char *buf
)
303 return single_hugepage_flag_show(kobj
, attr
, buf
,
304 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
306 static ssize_t
debug_cow_store(struct kobject
*kobj
,
307 struct kobj_attribute
*attr
,
308 const char *buf
, size_t count
)
310 return single_hugepage_flag_store(kobj
, attr
, buf
, count
,
311 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
313 static struct kobj_attribute debug_cow_attr
=
314 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
315 #endif /* CONFIG_DEBUG_VM */
317 static struct attribute
*hugepage_attr
[] = {
320 &use_zero_page_attr
.attr
,
321 &hpage_pmd_size_attr
.attr
,
322 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
323 &shmem_enabled_attr
.attr
,
325 #ifdef CONFIG_DEBUG_VM
326 &debug_cow_attr
.attr
,
331 static struct attribute_group hugepage_attr_group
= {
332 .attrs
= hugepage_attr
,
335 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
339 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
340 if (unlikely(!*hugepage_kobj
)) {
341 pr_err("failed to create transparent hugepage kobject\n");
345 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
347 pr_err("failed to register transparent hugepage group\n");
351 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
353 pr_err("failed to register transparent hugepage group\n");
354 goto remove_hp_group
;
360 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
362 kobject_put(*hugepage_kobj
);
366 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
368 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
369 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
370 kobject_put(hugepage_kobj
);
373 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
378 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
381 #endif /* CONFIG_SYSFS */
383 static int __init
hugepage_init(void)
386 struct kobject
*hugepage_kobj
;
388 if (!has_transparent_hugepage()) {
389 transparent_hugepage_flags
= 0;
394 * hugepages can't be allocated by the buddy allocator
396 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
>= MAX_ORDER
);
398 * we use page->mapping and page->index in second tail page
399 * as list_head: assuming THP order >= 2
401 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
< 2);
403 err
= hugepage_init_sysfs(&hugepage_kobj
);
407 err
= khugepaged_init();
411 err
= register_shrinker(&huge_zero_page_shrinker
);
413 goto err_hzp_shrinker
;
414 err
= register_shrinker(&deferred_split_shrinker
);
416 goto err_split_shrinker
;
419 * By default disable transparent hugepages on smaller systems,
420 * where the extra memory used could hurt more than TLB overhead
421 * is likely to save. The admin can still enable it through /sys.
423 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
))) {
424 transparent_hugepage_flags
= 0;
428 err
= start_stop_khugepaged();
434 unregister_shrinker(&deferred_split_shrinker
);
436 unregister_shrinker(&huge_zero_page_shrinker
);
438 khugepaged_destroy();
440 hugepage_exit_sysfs(hugepage_kobj
);
444 subsys_initcall(hugepage_init
);
446 static int __init
setup_transparent_hugepage(char *str
)
451 if (!strcmp(str
, "always")) {
452 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
453 &transparent_hugepage_flags
);
454 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
455 &transparent_hugepage_flags
);
457 } else if (!strcmp(str
, "madvise")) {
458 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
459 &transparent_hugepage_flags
);
460 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
461 &transparent_hugepage_flags
);
463 } else if (!strcmp(str
, "never")) {
464 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
465 &transparent_hugepage_flags
);
466 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
467 &transparent_hugepage_flags
);
472 pr_warn("transparent_hugepage= cannot parse, ignored\n");
475 __setup("transparent_hugepage=", setup_transparent_hugepage
);
477 pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
479 if (likely(vma
->vm_flags
& VM_WRITE
))
480 pmd
= pmd_mkwrite(pmd
);
484 static inline struct list_head
*page_deferred_list(struct page
*page
)
487 * ->lru in the tail pages is occupied by compound_head.
488 * Let's use ->mapping + ->index in the second tail page as list_head.
490 return (struct list_head
*)&page
[2].mapping
;
493 void prep_transhuge_page(struct page
*page
)
496 * we use page->mapping and page->indexlru in second tail page
497 * as list_head: assuming THP order >= 2
500 INIT_LIST_HEAD(page_deferred_list(page
));
501 set_compound_page_dtor(page
, TRANSHUGE_PAGE_DTOR
);
504 unsigned long __thp_get_unmapped_area(struct file
*filp
, unsigned long len
,
505 loff_t off
, unsigned long flags
, unsigned long size
)
508 loff_t off_end
= off
+ len
;
509 loff_t off_align
= round_up(off
, size
);
510 unsigned long len_pad
;
512 if (off_end
<= off_align
|| (off_end
- off_align
) < size
)
515 len_pad
= len
+ size
;
516 if (len_pad
< len
|| (off
+ len_pad
) < off
)
519 addr
= current
->mm
->get_unmapped_area(filp
, 0, len_pad
,
520 off
>> PAGE_SHIFT
, flags
);
521 if (IS_ERR_VALUE(addr
))
524 addr
+= (off
- addr
) & (size
- 1);
528 unsigned long thp_get_unmapped_area(struct file
*filp
, unsigned long addr
,
529 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
531 loff_t off
= (loff_t
)pgoff
<< PAGE_SHIFT
;
535 if (!IS_DAX(filp
->f_mapping
->host
) || !IS_ENABLED(CONFIG_FS_DAX_PMD
))
538 addr
= __thp_get_unmapped_area(filp
, len
, off
, flags
, PMD_SIZE
);
543 return current
->mm
->get_unmapped_area(filp
, addr
, len
, pgoff
, flags
);
545 EXPORT_SYMBOL_GPL(thp_get_unmapped_area
);
547 static int __do_huge_pmd_anonymous_page(struct vm_fault
*vmf
, struct page
*page
,
550 struct vm_area_struct
*vma
= vmf
->vma
;
551 struct mem_cgroup
*memcg
;
553 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
556 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
558 if (mem_cgroup_try_charge(page
, vma
->vm_mm
, gfp
, &memcg
, true)) {
560 count_vm_event(THP_FAULT_FALLBACK
);
561 return VM_FAULT_FALLBACK
;
564 pgtable
= pte_alloc_one(vma
->vm_mm
, haddr
);
565 if (unlikely(!pgtable
)) {
570 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
572 * The memory barrier inside __SetPageUptodate makes sure that
573 * clear_huge_page writes become visible before the set_pmd_at()
576 __SetPageUptodate(page
);
578 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
579 if (unlikely(!pmd_none(*vmf
->pmd
))) {
584 ret
= check_stable_address_space(vma
->vm_mm
);
588 /* Deliver the page fault to userland */
589 if (userfaultfd_missing(vma
)) {
592 spin_unlock(vmf
->ptl
);
593 mem_cgroup_cancel_charge(page
, memcg
, true);
595 pte_free(vma
->vm_mm
, pgtable
);
596 ret
= handle_userfault(vmf
, VM_UFFD_MISSING
);
597 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
601 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
602 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
603 page_add_new_anon_rmap(page
, vma
, haddr
, true);
604 mem_cgroup_commit_charge(page
, memcg
, false, true);
605 lru_cache_add_active_or_unevictable(page
, vma
);
606 pgtable_trans_huge_deposit(vma
->vm_mm
, vmf
->pmd
, pgtable
);
607 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
608 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
609 atomic_long_inc(&vma
->vm_mm
->nr_ptes
);
610 spin_unlock(vmf
->ptl
);
611 count_vm_event(THP_FAULT_ALLOC
);
616 spin_unlock(vmf
->ptl
);
619 pte_free(vma
->vm_mm
, pgtable
);
620 mem_cgroup_cancel_charge(page
, memcg
, true);
627 * always: directly stall for all thp allocations
628 * defer: wake kswapd and fail if not immediately available
629 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
630 * fail if not immediately available
631 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
633 * never: never stall for any thp allocation
635 static inline gfp_t
alloc_hugepage_direct_gfpmask(struct vm_area_struct
*vma
)
637 const bool vma_madvised
= !!(vma
->vm_flags
& VM_HUGEPAGE
);
639 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
640 return GFP_TRANSHUGE
| (vma_madvised
? 0 : __GFP_NORETRY
);
641 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
642 return GFP_TRANSHUGE_LIGHT
| __GFP_KSWAPD_RECLAIM
;
643 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
))
644 return GFP_TRANSHUGE_LIGHT
| (vma_madvised
? __GFP_DIRECT_RECLAIM
:
645 __GFP_KSWAPD_RECLAIM
);
646 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
647 return GFP_TRANSHUGE_LIGHT
| (vma_madvised
? __GFP_DIRECT_RECLAIM
:
649 return GFP_TRANSHUGE_LIGHT
;
652 /* Caller must hold page table lock. */
653 static bool set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
654 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
655 struct page
*zero_page
)
660 entry
= mk_pmd(zero_page
, vma
->vm_page_prot
);
661 entry
= pmd_mkhuge(entry
);
663 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
664 set_pmd_at(mm
, haddr
, pmd
, entry
);
665 atomic_long_inc(&mm
->nr_ptes
);
669 int do_huge_pmd_anonymous_page(struct vm_fault
*vmf
)
671 struct vm_area_struct
*vma
= vmf
->vma
;
674 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
676 if (haddr
< vma
->vm_start
|| haddr
+ HPAGE_PMD_SIZE
> vma
->vm_end
)
677 return VM_FAULT_FALLBACK
;
678 if (unlikely(anon_vma_prepare(vma
)))
680 if (unlikely(khugepaged_enter(vma
, vma
->vm_flags
)))
682 if (!(vmf
->flags
& FAULT_FLAG_WRITE
) &&
683 !mm_forbids_zeropage(vma
->vm_mm
) &&
684 transparent_hugepage_use_zero_page()) {
686 struct page
*zero_page
;
689 pgtable
= pte_alloc_one(vma
->vm_mm
, haddr
);
690 if (unlikely(!pgtable
))
692 zero_page
= mm_get_huge_zero_page(vma
->vm_mm
);
693 if (unlikely(!zero_page
)) {
694 pte_free(vma
->vm_mm
, pgtable
);
695 count_vm_event(THP_FAULT_FALLBACK
);
696 return VM_FAULT_FALLBACK
;
698 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
701 if (pmd_none(*vmf
->pmd
)) {
702 ret
= check_stable_address_space(vma
->vm_mm
);
704 spin_unlock(vmf
->ptl
);
705 } else if (userfaultfd_missing(vma
)) {
706 spin_unlock(vmf
->ptl
);
707 ret
= handle_userfault(vmf
, VM_UFFD_MISSING
);
708 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
710 set_huge_zero_page(pgtable
, vma
->vm_mm
, vma
,
711 haddr
, vmf
->pmd
, zero_page
);
712 spin_unlock(vmf
->ptl
);
716 spin_unlock(vmf
->ptl
);
718 pte_free(vma
->vm_mm
, pgtable
);
721 gfp
= alloc_hugepage_direct_gfpmask(vma
);
722 page
= alloc_hugepage_vma(gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
723 if (unlikely(!page
)) {
724 count_vm_event(THP_FAULT_FALLBACK
);
725 return VM_FAULT_FALLBACK
;
727 prep_transhuge_page(page
);
728 return __do_huge_pmd_anonymous_page(vmf
, page
, gfp
);
731 static void insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
732 pmd_t
*pmd
, pfn_t pfn
, pgprot_t prot
, bool write
,
735 struct mm_struct
*mm
= vma
->vm_mm
;
739 ptl
= pmd_lock(mm
, pmd
);
740 entry
= pmd_mkhuge(pfn_t_pmd(pfn
, prot
));
741 if (pfn_t_devmap(pfn
))
742 entry
= pmd_mkdevmap(entry
);
744 entry
= pmd_mkyoung(pmd_mkdirty(entry
));
745 entry
= maybe_pmd_mkwrite(entry
, vma
);
749 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
750 atomic_long_inc(&mm
->nr_ptes
);
753 set_pmd_at(mm
, addr
, pmd
, entry
);
754 update_mmu_cache_pmd(vma
, addr
, pmd
);
758 int vmf_insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
759 pmd_t
*pmd
, pfn_t pfn
, bool write
)
761 pgprot_t pgprot
= vma
->vm_page_prot
;
762 pgtable_t pgtable
= NULL
;
764 * If we had pmd_special, we could avoid all these restrictions,
765 * but we need to be consistent with PTEs and architectures that
766 * can't support a 'special' bit.
768 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)));
769 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
770 (VM_PFNMAP
|VM_MIXEDMAP
));
771 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
772 BUG_ON(!pfn_t_devmap(pfn
));
774 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
775 return VM_FAULT_SIGBUS
;
777 if (arch_needs_pgtable_deposit()) {
778 pgtable
= pte_alloc_one(vma
->vm_mm
, addr
);
783 track_pfn_insert(vma
, &pgprot
, pfn
);
785 insert_pfn_pmd(vma
, addr
, pmd
, pfn
, pgprot
, write
, pgtable
);
786 return VM_FAULT_NOPAGE
;
788 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd
);
790 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
791 static pud_t
maybe_pud_mkwrite(pud_t pud
, struct vm_area_struct
*vma
)
793 if (likely(vma
->vm_flags
& VM_WRITE
))
794 pud
= pud_mkwrite(pud
);
798 static void insert_pfn_pud(struct vm_area_struct
*vma
, unsigned long addr
,
799 pud_t
*pud
, pfn_t pfn
, pgprot_t prot
, bool write
)
801 struct mm_struct
*mm
= vma
->vm_mm
;
805 ptl
= pud_lock(mm
, pud
);
806 entry
= pud_mkhuge(pfn_t_pud(pfn
, prot
));
807 if (pfn_t_devmap(pfn
))
808 entry
= pud_mkdevmap(entry
);
810 entry
= pud_mkyoung(pud_mkdirty(entry
));
811 entry
= maybe_pud_mkwrite(entry
, vma
);
813 set_pud_at(mm
, addr
, pud
, entry
);
814 update_mmu_cache_pud(vma
, addr
, pud
);
818 int vmf_insert_pfn_pud(struct vm_area_struct
*vma
, unsigned long addr
,
819 pud_t
*pud
, pfn_t pfn
, bool write
)
821 pgprot_t pgprot
= vma
->vm_page_prot
;
823 * If we had pud_special, we could avoid all these restrictions,
824 * but we need to be consistent with PTEs and architectures that
825 * can't support a 'special' bit.
827 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)));
828 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
829 (VM_PFNMAP
|VM_MIXEDMAP
));
830 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
831 BUG_ON(!pfn_t_devmap(pfn
));
833 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
834 return VM_FAULT_SIGBUS
;
836 track_pfn_insert(vma
, &pgprot
, pfn
);
838 insert_pfn_pud(vma
, addr
, pud
, pfn
, pgprot
, write
);
839 return VM_FAULT_NOPAGE
;
841 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud
);
842 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
844 static void touch_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
850 * We should set the dirty bit only for FOLL_WRITE but for now
851 * the dirty bit in the pmd is meaningless. And if the dirty
852 * bit will become meaningful and we'll only set it with
853 * FOLL_WRITE, an atomic set_bit will be required on the pmd to
854 * set the young bit, instead of the current set_pmd_at.
856 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
857 if (pmdp_set_access_flags(vma
, addr
& HPAGE_PMD_MASK
,
859 update_mmu_cache_pmd(vma
, addr
, pmd
);
862 struct page
*follow_devmap_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
863 pmd_t
*pmd
, int flags
)
865 unsigned long pfn
= pmd_pfn(*pmd
);
866 struct mm_struct
*mm
= vma
->vm_mm
;
867 struct dev_pagemap
*pgmap
;
870 assert_spin_locked(pmd_lockptr(mm
, pmd
));
873 * When we COW a devmap PMD entry, we split it into PTEs, so we should
874 * not be in this function with `flags & FOLL_COW` set.
876 WARN_ONCE(flags
& FOLL_COW
, "mm: In follow_devmap_pmd with FOLL_COW set");
878 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
881 if (pmd_present(*pmd
) && pmd_devmap(*pmd
))
886 if (flags
& FOLL_TOUCH
)
887 touch_pmd(vma
, addr
, pmd
);
890 * device mapped pages can only be returned if the
891 * caller will manage the page reference count.
893 if (!(flags
& FOLL_GET
))
894 return ERR_PTR(-EEXIST
);
896 pfn
+= (addr
& ~PMD_MASK
) >> PAGE_SHIFT
;
897 pgmap
= get_dev_pagemap(pfn
, NULL
);
899 return ERR_PTR(-EFAULT
);
900 page
= pfn_to_page(pfn
);
902 put_dev_pagemap(pgmap
);
907 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
908 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
909 struct vm_area_struct
*vma
)
911 spinlock_t
*dst_ptl
, *src_ptl
;
912 struct page
*src_page
;
914 pgtable_t pgtable
= NULL
;
917 /* Skip if can be re-fill on fault */
918 if (!vma_is_anonymous(vma
))
921 pgtable
= pte_alloc_one(dst_mm
, addr
);
922 if (unlikely(!pgtable
))
925 dst_ptl
= pmd_lock(dst_mm
, dst_pmd
);
926 src_ptl
= pmd_lockptr(src_mm
, src_pmd
);
927 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
931 if (unlikely(!pmd_trans_huge(pmd
))) {
932 pte_free(dst_mm
, pgtable
);
936 * When page table lock is held, the huge zero pmd should not be
937 * under splitting since we don't split the page itself, only pmd to
940 if (is_huge_zero_pmd(pmd
)) {
941 struct page
*zero_page
;
943 * get_huge_zero_page() will never allocate a new page here,
944 * since we already have a zero page to copy. It just takes a
947 zero_page
= mm_get_huge_zero_page(dst_mm
);
948 set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
954 src_page
= pmd_page(pmd
);
955 VM_BUG_ON_PAGE(!PageHead(src_page
), src_page
);
957 page_dup_rmap(src_page
, true);
958 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
959 atomic_long_inc(&dst_mm
->nr_ptes
);
960 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
962 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
963 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
964 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
968 spin_unlock(src_ptl
);
969 spin_unlock(dst_ptl
);
974 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
975 static void touch_pud(struct vm_area_struct
*vma
, unsigned long addr
,
981 * We should set the dirty bit only for FOLL_WRITE but for now
982 * the dirty bit in the pud is meaningless. And if the dirty
983 * bit will become meaningful and we'll only set it with
984 * FOLL_WRITE, an atomic set_bit will be required on the pud to
985 * set the young bit, instead of the current set_pud_at.
987 _pud
= pud_mkyoung(pud_mkdirty(*pud
));
988 if (pudp_set_access_flags(vma
, addr
& HPAGE_PUD_MASK
,
990 update_mmu_cache_pud(vma
, addr
, pud
);
993 struct page
*follow_devmap_pud(struct vm_area_struct
*vma
, unsigned long addr
,
994 pud_t
*pud
, int flags
)
996 unsigned long pfn
= pud_pfn(*pud
);
997 struct mm_struct
*mm
= vma
->vm_mm
;
998 struct dev_pagemap
*pgmap
;
1001 assert_spin_locked(pud_lockptr(mm
, pud
));
1003 if (flags
& FOLL_WRITE
&& !pud_write(*pud
))
1006 if (pud_present(*pud
) && pud_devmap(*pud
))
1011 if (flags
& FOLL_TOUCH
)
1012 touch_pud(vma
, addr
, pud
);
1015 * device mapped pages can only be returned if the
1016 * caller will manage the page reference count.
1018 if (!(flags
& FOLL_GET
))
1019 return ERR_PTR(-EEXIST
);
1021 pfn
+= (addr
& ~PUD_MASK
) >> PAGE_SHIFT
;
1022 pgmap
= get_dev_pagemap(pfn
, NULL
);
1024 return ERR_PTR(-EFAULT
);
1025 page
= pfn_to_page(pfn
);
1027 put_dev_pagemap(pgmap
);
1032 int copy_huge_pud(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1033 pud_t
*dst_pud
, pud_t
*src_pud
, unsigned long addr
,
1034 struct vm_area_struct
*vma
)
1036 spinlock_t
*dst_ptl
, *src_ptl
;
1040 dst_ptl
= pud_lock(dst_mm
, dst_pud
);
1041 src_ptl
= pud_lockptr(src_mm
, src_pud
);
1042 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
1046 if (unlikely(!pud_trans_huge(pud
) && !pud_devmap(pud
)))
1050 * When page table lock is held, the huge zero pud should not be
1051 * under splitting since we don't split the page itself, only pud to
1054 if (is_huge_zero_pud(pud
)) {
1055 /* No huge zero pud yet */
1058 pudp_set_wrprotect(src_mm
, addr
, src_pud
);
1059 pud
= pud_mkold(pud_wrprotect(pud
));
1060 set_pud_at(dst_mm
, addr
, dst_pud
, pud
);
1064 spin_unlock(src_ptl
);
1065 spin_unlock(dst_ptl
);
1069 void huge_pud_set_accessed(struct vm_fault
*vmf
, pud_t orig_pud
)
1072 unsigned long haddr
;
1073 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1075 vmf
->ptl
= pud_lock(vmf
->vma
->vm_mm
, vmf
->pud
);
1076 if (unlikely(!pud_same(*vmf
->pud
, orig_pud
)))
1079 entry
= pud_mkyoung(orig_pud
);
1081 entry
= pud_mkdirty(entry
);
1082 haddr
= vmf
->address
& HPAGE_PUD_MASK
;
1083 if (pudp_set_access_flags(vmf
->vma
, haddr
, vmf
->pud
, entry
, write
))
1084 update_mmu_cache_pud(vmf
->vma
, vmf
->address
, vmf
->pud
);
1087 spin_unlock(vmf
->ptl
);
1089 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1091 void huge_pmd_set_accessed(struct vm_fault
*vmf
, pmd_t orig_pmd
)
1094 unsigned long haddr
;
1095 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1097 vmf
->ptl
= pmd_lock(vmf
->vma
->vm_mm
, vmf
->pmd
);
1098 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1101 entry
= pmd_mkyoung(orig_pmd
);
1103 entry
= pmd_mkdirty(entry
);
1104 haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1105 if (pmdp_set_access_flags(vmf
->vma
, haddr
, vmf
->pmd
, entry
, write
))
1106 update_mmu_cache_pmd(vmf
->vma
, vmf
->address
, vmf
->pmd
);
1109 spin_unlock(vmf
->ptl
);
1112 static int do_huge_pmd_wp_page_fallback(struct vm_fault
*vmf
, pmd_t orig_pmd
,
1115 struct vm_area_struct
*vma
= vmf
->vma
;
1116 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1117 struct mem_cgroup
*memcg
;
1121 struct page
**pages
;
1122 unsigned long mmun_start
; /* For mmu_notifiers */
1123 unsigned long mmun_end
; /* For mmu_notifiers */
1125 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
1127 if (unlikely(!pages
)) {
1128 ret
|= VM_FAULT_OOM
;
1132 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1133 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
, vma
,
1134 vmf
->address
, page_to_nid(page
));
1135 if (unlikely(!pages
[i
] ||
1136 mem_cgroup_try_charge(pages
[i
], vma
->vm_mm
,
1137 GFP_KERNEL
, &memcg
, false))) {
1141 memcg
= (void *)page_private(pages
[i
]);
1142 set_page_private(pages
[i
], 0);
1143 mem_cgroup_cancel_charge(pages
[i
], memcg
,
1148 ret
|= VM_FAULT_OOM
;
1151 set_page_private(pages
[i
], (unsigned long)memcg
);
1154 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1155 copy_user_highpage(pages
[i
], page
+ i
,
1156 haddr
+ PAGE_SIZE
* i
, vma
);
1157 __SetPageUptodate(pages
[i
]);
1162 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1163 mmu_notifier_invalidate_range_start(vma
->vm_mm
, mmun_start
, mmun_end
);
1165 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1166 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1167 goto out_free_pages
;
1168 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1170 pmdp_huge_clear_flush_notify(vma
, haddr
, vmf
->pmd
);
1171 /* leave pmd empty until pte is filled */
1173 pgtable
= pgtable_trans_huge_withdraw(vma
->vm_mm
, vmf
->pmd
);
1174 pmd_populate(vma
->vm_mm
, &_pmd
, pgtable
);
1176 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1178 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1179 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1180 memcg
= (void *)page_private(pages
[i
]);
1181 set_page_private(pages
[i
], 0);
1182 page_add_new_anon_rmap(pages
[i
], vmf
->vma
, haddr
, false);
1183 mem_cgroup_commit_charge(pages
[i
], memcg
, false, false);
1184 lru_cache_add_active_or_unevictable(pages
[i
], vma
);
1185 vmf
->pte
= pte_offset_map(&_pmd
, haddr
);
1186 VM_BUG_ON(!pte_none(*vmf
->pte
));
1187 set_pte_at(vma
->vm_mm
, haddr
, vmf
->pte
, entry
);
1188 pte_unmap(vmf
->pte
);
1192 smp_wmb(); /* make pte visible before pmd */
1193 pmd_populate(vma
->vm_mm
, vmf
->pmd
, pgtable
);
1194 page_remove_rmap(page
, true);
1195 spin_unlock(vmf
->ptl
);
1197 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
1199 ret
|= VM_FAULT_WRITE
;
1206 spin_unlock(vmf
->ptl
);
1207 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
1208 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1209 memcg
= (void *)page_private(pages
[i
]);
1210 set_page_private(pages
[i
], 0);
1211 mem_cgroup_cancel_charge(pages
[i
], memcg
, false);
1218 int do_huge_pmd_wp_page(struct vm_fault
*vmf
, pmd_t orig_pmd
)
1220 struct vm_area_struct
*vma
= vmf
->vma
;
1221 struct page
*page
= NULL
, *new_page
;
1222 struct mem_cgroup
*memcg
;
1223 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1224 unsigned long mmun_start
; /* For mmu_notifiers */
1225 unsigned long mmun_end
; /* For mmu_notifiers */
1226 gfp_t huge_gfp
; /* for allocation and charge */
1229 vmf
->ptl
= pmd_lockptr(vma
->vm_mm
, vmf
->pmd
);
1230 VM_BUG_ON_VMA(!vma
->anon_vma
, vma
);
1231 if (is_huge_zero_pmd(orig_pmd
))
1233 spin_lock(vmf
->ptl
);
1234 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1237 page
= pmd_page(orig_pmd
);
1238 VM_BUG_ON_PAGE(!PageCompound(page
) || !PageHead(page
), page
);
1240 * We can only reuse the page if nobody else maps the huge page or it's
1243 if (page_trans_huge_mapcount(page
, NULL
) == 1) {
1245 entry
= pmd_mkyoung(orig_pmd
);
1246 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1247 if (pmdp_set_access_flags(vma
, haddr
, vmf
->pmd
, entry
, 1))
1248 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1249 ret
|= VM_FAULT_WRITE
;
1253 spin_unlock(vmf
->ptl
);
1255 if (transparent_hugepage_enabled(vma
) &&
1256 !transparent_hugepage_debug_cow()) {
1257 huge_gfp
= alloc_hugepage_direct_gfpmask(vma
);
1258 new_page
= alloc_hugepage_vma(huge_gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
1262 if (likely(new_page
)) {
1263 prep_transhuge_page(new_page
);
1266 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1267 ret
|= VM_FAULT_FALLBACK
;
1269 ret
= do_huge_pmd_wp_page_fallback(vmf
, orig_pmd
, page
);
1270 if (ret
& VM_FAULT_OOM
) {
1271 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1272 ret
|= VM_FAULT_FALLBACK
;
1276 count_vm_event(THP_FAULT_FALLBACK
);
1280 if (unlikely(mem_cgroup_try_charge(new_page
, vma
->vm_mm
,
1281 huge_gfp
, &memcg
, true))) {
1283 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1286 ret
|= VM_FAULT_FALLBACK
;
1287 count_vm_event(THP_FAULT_FALLBACK
);
1291 count_vm_event(THP_FAULT_ALLOC
);
1294 clear_huge_page(new_page
, haddr
, HPAGE_PMD_NR
);
1296 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
1297 __SetPageUptodate(new_page
);
1300 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1301 mmu_notifier_invalidate_range_start(vma
->vm_mm
, mmun_start
, mmun_end
);
1303 spin_lock(vmf
->ptl
);
1306 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
))) {
1307 spin_unlock(vmf
->ptl
);
1308 mem_cgroup_cancel_charge(new_page
, memcg
, true);
1313 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
1314 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1315 pmdp_huge_clear_flush_notify(vma
, haddr
, vmf
->pmd
);
1316 page_add_new_anon_rmap(new_page
, vma
, haddr
, true);
1317 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
1318 lru_cache_add_active_or_unevictable(new_page
, vma
);
1319 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
1320 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1322 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1324 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1325 page_remove_rmap(page
, true);
1328 ret
|= VM_FAULT_WRITE
;
1330 spin_unlock(vmf
->ptl
);
1332 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
1336 spin_unlock(vmf
->ptl
);
1341 * FOLL_FORCE can write to even unwritable pmd's, but only
1342 * after we've gone through a COW cycle and they are dirty.
1344 static inline bool can_follow_write_pmd(pmd_t pmd
, unsigned int flags
)
1346 return pmd_write(pmd
) ||
1347 ((flags
& FOLL_FORCE
) && (flags
& FOLL_COW
) && pmd_dirty(pmd
));
1350 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1355 struct mm_struct
*mm
= vma
->vm_mm
;
1356 struct page
*page
= NULL
;
1358 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1360 if (flags
& FOLL_WRITE
&& !can_follow_write_pmd(*pmd
, flags
))
1363 /* Avoid dumping huge zero page */
1364 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1365 return ERR_PTR(-EFAULT
);
1367 /* Full NUMA hinting faults to serialise migration in fault paths */
1368 if ((flags
& FOLL_NUMA
) && pmd_protnone(*pmd
))
1371 page
= pmd_page(*pmd
);
1372 VM_BUG_ON_PAGE(!PageHead(page
) && !is_zone_device_page(page
), page
);
1373 if (flags
& FOLL_TOUCH
)
1374 touch_pmd(vma
, addr
, pmd
);
1375 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1377 * We don't mlock() pte-mapped THPs. This way we can avoid
1378 * leaking mlocked pages into non-VM_LOCKED VMAs.
1382 * In most cases the pmd is the only mapping of the page as we
1383 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1384 * writable private mappings in populate_vma_page_range().
1386 * The only scenario when we have the page shared here is if we
1387 * mlocking read-only mapping shared over fork(). We skip
1388 * mlocking such pages.
1392 * We can expect PageDoubleMap() to be stable under page lock:
1393 * for file pages we set it in page_add_file_rmap(), which
1394 * requires page to be locked.
1397 if (PageAnon(page
) && compound_mapcount(page
) != 1)
1399 if (PageDoubleMap(page
) || !page
->mapping
)
1401 if (!trylock_page(page
))
1404 if (page
->mapping
&& !PageDoubleMap(page
))
1405 mlock_vma_page(page
);
1409 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1410 VM_BUG_ON_PAGE(!PageCompound(page
) && !is_zone_device_page(page
), page
);
1411 if (flags
& FOLL_GET
)
1418 /* NUMA hinting page fault entry point for trans huge pmds */
1419 int do_huge_pmd_numa_page(struct vm_fault
*vmf
, pmd_t pmd
)
1421 struct vm_area_struct
*vma
= vmf
->vma
;
1422 struct anon_vma
*anon_vma
= NULL
;
1424 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1425 int page_nid
= -1, this_nid
= numa_node_id();
1426 int target_nid
, last_cpupid
= -1;
1428 bool migrated
= false;
1432 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1433 if (unlikely(!pmd_same(pmd
, *vmf
->pmd
)))
1437 * If there are potential migrations, wait for completion and retry
1438 * without disrupting NUMA hinting information. Do not relock and
1439 * check_same as the page may no longer be mapped.
1441 if (unlikely(pmd_trans_migrating(*vmf
->pmd
))) {
1442 page
= pmd_page(*vmf
->pmd
);
1443 if (!get_page_unless_zero(page
))
1445 spin_unlock(vmf
->ptl
);
1446 wait_on_page_locked(page
);
1451 page
= pmd_page(pmd
);
1452 BUG_ON(is_huge_zero_page(page
));
1453 page_nid
= page_to_nid(page
);
1454 last_cpupid
= page_cpupid_last(page
);
1455 count_vm_numa_event(NUMA_HINT_FAULTS
);
1456 if (page_nid
== this_nid
) {
1457 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
1458 flags
|= TNF_FAULT_LOCAL
;
1461 /* See similar comment in do_numa_page for explanation */
1462 if (!pmd_savedwrite(pmd
))
1463 flags
|= TNF_NO_GROUP
;
1466 * Acquire the page lock to serialise THP migrations but avoid dropping
1467 * page_table_lock if at all possible
1469 page_locked
= trylock_page(page
);
1470 target_nid
= mpol_misplaced(page
, vma
, haddr
);
1471 if (target_nid
== -1) {
1472 /* If the page was locked, there are no parallel migrations */
1477 /* Migration could have started since the pmd_trans_migrating check */
1480 if (!get_page_unless_zero(page
))
1482 spin_unlock(vmf
->ptl
);
1483 wait_on_page_locked(page
);
1489 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1490 * to serialises splits
1493 spin_unlock(vmf
->ptl
);
1494 anon_vma
= page_lock_anon_vma_read(page
);
1496 /* Confirm the PMD did not change while page_table_lock was released */
1497 spin_lock(vmf
->ptl
);
1498 if (unlikely(!pmd_same(pmd
, *vmf
->pmd
))) {
1505 /* Bail if we fail to protect against THP splits for any reason */
1506 if (unlikely(!anon_vma
)) {
1513 * The page_table_lock above provides a memory barrier
1514 * with change_protection_range.
1516 if (mm_tlb_flush_pending(vma
->vm_mm
))
1517 flush_tlb_range(vma
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
1520 * Migrate the THP to the requested node, returns with page unlocked
1521 * and access rights restored.
1523 spin_unlock(vmf
->ptl
);
1524 migrated
= migrate_misplaced_transhuge_page(vma
->vm_mm
, vma
,
1525 vmf
->pmd
, pmd
, vmf
->address
, page
, target_nid
);
1527 flags
|= TNF_MIGRATED
;
1528 page_nid
= target_nid
;
1530 flags
|= TNF_MIGRATE_FAIL
;
1534 BUG_ON(!PageLocked(page
));
1535 was_writable
= pmd_savedwrite(pmd
);
1536 pmd
= pmd_modify(pmd
, vma
->vm_page_prot
);
1537 pmd
= pmd_mkyoung(pmd
);
1539 pmd
= pmd_mkwrite(pmd
);
1540 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, pmd
);
1541 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1544 spin_unlock(vmf
->ptl
);
1548 page_unlock_anon_vma_read(anon_vma
);
1551 task_numa_fault(last_cpupid
, page_nid
, HPAGE_PMD_NR
,
1558 * Return true if we do MADV_FREE successfully on entire pmd page.
1559 * Otherwise, return false.
1561 bool madvise_free_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1562 pmd_t
*pmd
, unsigned long addr
, unsigned long next
)
1567 struct mm_struct
*mm
= tlb
->mm
;
1570 tlb_remove_check_page_size_change(tlb
, HPAGE_PMD_SIZE
);
1572 ptl
= pmd_trans_huge_lock(pmd
, vma
);
1577 if (is_huge_zero_pmd(orig_pmd
))
1580 page
= pmd_page(orig_pmd
);
1582 * If other processes are mapping this page, we couldn't discard
1583 * the page unless they all do MADV_FREE so let's skip the page.
1585 if (page_mapcount(page
) != 1)
1588 if (!trylock_page(page
))
1592 * If user want to discard part-pages of THP, split it so MADV_FREE
1593 * will deactivate only them.
1595 if (next
- addr
!= HPAGE_PMD_SIZE
) {
1598 split_huge_page(page
);
1604 if (PageDirty(page
))
1605 ClearPageDirty(page
);
1608 if (pmd_young(orig_pmd
) || pmd_dirty(orig_pmd
)) {
1609 pmdp_invalidate(vma
, addr
, pmd
);
1610 orig_pmd
= pmd_mkold(orig_pmd
);
1611 orig_pmd
= pmd_mkclean(orig_pmd
);
1613 set_pmd_at(mm
, addr
, pmd
, orig_pmd
);
1614 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1617 mark_page_lazyfree(page
);
1625 static inline void zap_deposited_table(struct mm_struct
*mm
, pmd_t
*pmd
)
1629 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1630 pte_free(mm
, pgtable
);
1631 atomic_long_dec(&mm
->nr_ptes
);
1634 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1635 pmd_t
*pmd
, unsigned long addr
)
1640 tlb_remove_check_page_size_change(tlb
, HPAGE_PMD_SIZE
);
1642 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1646 * For architectures like ppc64 we look at deposited pgtable
1647 * when calling pmdp_huge_get_and_clear. So do the
1648 * pgtable_trans_huge_withdraw after finishing pmdp related
1651 orig_pmd
= pmdp_huge_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1653 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1654 if (vma_is_dax(vma
)) {
1655 if (arch_needs_pgtable_deposit())
1656 zap_deposited_table(tlb
->mm
, pmd
);
1658 if (is_huge_zero_pmd(orig_pmd
))
1659 tlb_remove_page_size(tlb
, pmd_page(orig_pmd
), HPAGE_PMD_SIZE
);
1660 } else if (is_huge_zero_pmd(orig_pmd
)) {
1661 zap_deposited_table(tlb
->mm
, pmd
);
1663 tlb_remove_page_size(tlb
, pmd_page(orig_pmd
), HPAGE_PMD_SIZE
);
1665 struct page
*page
= pmd_page(orig_pmd
);
1666 page_remove_rmap(page
, true);
1667 VM_BUG_ON_PAGE(page_mapcount(page
) < 0, page
);
1668 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1669 if (PageAnon(page
)) {
1670 zap_deposited_table(tlb
->mm
, pmd
);
1671 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1673 if (arch_needs_pgtable_deposit())
1674 zap_deposited_table(tlb
->mm
, pmd
);
1675 add_mm_counter(tlb
->mm
, MM_FILEPAGES
, -HPAGE_PMD_NR
);
1678 tlb_remove_page_size(tlb
, page
, HPAGE_PMD_SIZE
);
1683 #ifndef pmd_move_must_withdraw
1684 static inline int pmd_move_must_withdraw(spinlock_t
*new_pmd_ptl
,
1685 spinlock_t
*old_pmd_ptl
,
1686 struct vm_area_struct
*vma
)
1689 * With split pmd lock we also need to move preallocated
1690 * PTE page table if new_pmd is on different PMD page table.
1692 * We also don't deposit and withdraw tables for file pages.
1694 return (new_pmd_ptl
!= old_pmd_ptl
) && vma_is_anonymous(vma
);
1698 bool move_huge_pmd(struct vm_area_struct
*vma
, unsigned long old_addr
,
1699 unsigned long new_addr
, unsigned long old_end
,
1700 pmd_t
*old_pmd
, pmd_t
*new_pmd
, bool *need_flush
)
1702 spinlock_t
*old_ptl
, *new_ptl
;
1704 struct mm_struct
*mm
= vma
->vm_mm
;
1705 bool force_flush
= false;
1707 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1708 (new_addr
& ~HPAGE_PMD_MASK
) ||
1709 old_end
- old_addr
< HPAGE_PMD_SIZE
)
1713 * The destination pmd shouldn't be established, free_pgtables()
1714 * should have release it.
1716 if (WARN_ON(!pmd_none(*new_pmd
))) {
1717 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1722 * We don't have to worry about the ordering of src and dst
1723 * ptlocks because exclusive mmap_sem prevents deadlock.
1725 old_ptl
= __pmd_trans_huge_lock(old_pmd
, vma
);
1727 new_ptl
= pmd_lockptr(mm
, new_pmd
);
1728 if (new_ptl
!= old_ptl
)
1729 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
1730 pmd
= pmdp_huge_get_and_clear(mm
, old_addr
, old_pmd
);
1731 if (pmd_present(pmd
) && pmd_dirty(pmd
))
1733 VM_BUG_ON(!pmd_none(*new_pmd
));
1735 if (pmd_move_must_withdraw(new_ptl
, old_ptl
, vma
)) {
1737 pgtable
= pgtable_trans_huge_withdraw(mm
, old_pmd
);
1738 pgtable_trans_huge_deposit(mm
, new_pmd
, pgtable
);
1740 set_pmd_at(mm
, new_addr
, new_pmd
, pmd_mksoft_dirty(pmd
));
1741 if (new_ptl
!= old_ptl
)
1742 spin_unlock(new_ptl
);
1744 flush_tlb_range(vma
, old_addr
, old_addr
+ PMD_SIZE
);
1747 spin_unlock(old_ptl
);
1755 * - 0 if PMD could not be locked
1756 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1757 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1759 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1760 unsigned long addr
, pgprot_t newprot
, int prot_numa
)
1762 struct mm_struct
*mm
= vma
->vm_mm
;
1765 bool preserve_write
;
1768 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1772 preserve_write
= prot_numa
&& pmd_write(*pmd
);
1776 * Avoid trapping faults against the zero page. The read-only
1777 * data is likely to be read-cached on the local CPU and
1778 * local/remote hits to the zero page are not interesting.
1780 if (prot_numa
&& is_huge_zero_pmd(*pmd
))
1783 if (prot_numa
&& pmd_protnone(*pmd
))
1787 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1788 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1789 * which is also under down_read(mmap_sem):
1792 * change_huge_pmd(prot_numa=1)
1793 * pmdp_huge_get_and_clear_notify()
1794 * madvise_dontneed()
1796 * pmd_trans_huge(*pmd) == 0 (without ptl)
1799 * // pmd is re-established
1801 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1802 * which may break userspace.
1804 * pmdp_invalidate() is required to make sure we don't miss
1805 * dirty/young flags set by hardware.
1808 pmdp_invalidate(vma
, addr
, pmd
);
1811 * Recover dirty/young flags. It relies on pmdp_invalidate to not
1814 if (pmd_dirty(*pmd
))
1815 entry
= pmd_mkdirty(entry
);
1816 if (pmd_young(*pmd
))
1817 entry
= pmd_mkyoung(entry
);
1819 entry
= pmd_modify(entry
, newprot
);
1821 entry
= pmd_mk_savedwrite(entry
);
1823 set_pmd_at(mm
, addr
, pmd
, entry
);
1824 BUG_ON(vma_is_anonymous(vma
) && !preserve_write
&& pmd_write(entry
));
1831 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1833 * Note that if it returns page table lock pointer, this routine returns without
1834 * unlocking page table lock. So callers must unlock it.
1836 spinlock_t
*__pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1839 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
1840 if (likely(pmd_trans_huge(*pmd
) || pmd_devmap(*pmd
)))
1847 * Returns true if a given pud maps a thp, false otherwise.
1849 * Note that if it returns true, this routine returns without unlocking page
1850 * table lock. So callers must unlock it.
1852 spinlock_t
*__pud_trans_huge_lock(pud_t
*pud
, struct vm_area_struct
*vma
)
1856 ptl
= pud_lock(vma
->vm_mm
, pud
);
1857 if (likely(pud_trans_huge(*pud
) || pud_devmap(*pud
)))
1863 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1864 int zap_huge_pud(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1865 pud_t
*pud
, unsigned long addr
)
1870 ptl
= __pud_trans_huge_lock(pud
, vma
);
1874 * For architectures like ppc64 we look at deposited pgtable
1875 * when calling pudp_huge_get_and_clear. So do the
1876 * pgtable_trans_huge_withdraw after finishing pudp related
1879 orig_pud
= pudp_huge_get_and_clear_full(tlb
->mm
, addr
, pud
,
1881 tlb_remove_pud_tlb_entry(tlb
, pud
, addr
);
1882 if (vma_is_dax(vma
)) {
1884 /* No zero page support yet */
1886 /* No support for anonymous PUD pages yet */
1892 static void __split_huge_pud_locked(struct vm_area_struct
*vma
, pud_t
*pud
,
1893 unsigned long haddr
)
1895 VM_BUG_ON(haddr
& ~HPAGE_PUD_MASK
);
1896 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
1897 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PUD_SIZE
, vma
);
1898 VM_BUG_ON(!pud_trans_huge(*pud
) && !pud_devmap(*pud
));
1900 count_vm_event(THP_SPLIT_PUD
);
1902 pudp_huge_clear_flush_notify(vma
, haddr
, pud
);
1905 void __split_huge_pud(struct vm_area_struct
*vma
, pud_t
*pud
,
1906 unsigned long address
)
1909 struct mm_struct
*mm
= vma
->vm_mm
;
1910 unsigned long haddr
= address
& HPAGE_PUD_MASK
;
1912 mmu_notifier_invalidate_range_start(mm
, haddr
, haddr
+ HPAGE_PUD_SIZE
);
1913 ptl
= pud_lock(mm
, pud
);
1914 if (unlikely(!pud_trans_huge(*pud
) && !pud_devmap(*pud
)))
1916 __split_huge_pud_locked(vma
, pud
, haddr
);
1920 mmu_notifier_invalidate_range_end(mm
, haddr
, haddr
+ HPAGE_PUD_SIZE
);
1922 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1924 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
1925 unsigned long haddr
, pmd_t
*pmd
)
1927 struct mm_struct
*mm
= vma
->vm_mm
;
1932 /* leave pmd empty until pte is filled */
1933 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
1935 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1936 pmd_populate(mm
, &_pmd
, pgtable
);
1938 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1940 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
1941 entry
= pte_mkspecial(entry
);
1942 pte
= pte_offset_map(&_pmd
, haddr
);
1943 VM_BUG_ON(!pte_none(*pte
));
1944 set_pte_at(mm
, haddr
, pte
, entry
);
1947 smp_wmb(); /* make pte visible before pmd */
1948 pmd_populate(mm
, pmd
, pgtable
);
1951 static void __split_huge_pmd_locked(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1952 unsigned long haddr
, bool freeze
)
1954 struct mm_struct
*mm
= vma
->vm_mm
;
1958 bool young
, write
, dirty
, soft_dirty
;
1962 VM_BUG_ON(haddr
& ~HPAGE_PMD_MASK
);
1963 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
1964 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
, vma
);
1965 VM_BUG_ON(!pmd_trans_huge(*pmd
) && !pmd_devmap(*pmd
));
1967 count_vm_event(THP_SPLIT_PMD
);
1969 if (!vma_is_anonymous(vma
)) {
1970 _pmd
= pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
1972 * We are going to unmap this huge page. So
1973 * just go ahead and zap it
1975 if (arch_needs_pgtable_deposit())
1976 zap_deposited_table(mm
, pmd
);
1977 if (vma_is_dax(vma
))
1979 page
= pmd_page(_pmd
);
1980 if (!PageReferenced(page
) && pmd_young(_pmd
))
1981 SetPageReferenced(page
);
1982 page_remove_rmap(page
, true);
1984 add_mm_counter(mm
, MM_FILEPAGES
, -HPAGE_PMD_NR
);
1986 } else if (is_huge_zero_pmd(*pmd
)) {
1987 return __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
1990 page
= pmd_page(*pmd
);
1991 VM_BUG_ON_PAGE(!page_count(page
), page
);
1992 page_ref_add(page
, HPAGE_PMD_NR
- 1);
1993 write
= pmd_write(*pmd
);
1994 young
= pmd_young(*pmd
);
1995 dirty
= pmd_dirty(*pmd
);
1996 soft_dirty
= pmd_soft_dirty(*pmd
);
1998 pmdp_huge_split_prepare(vma
, haddr
, pmd
);
1999 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2000 pmd_populate(mm
, &_pmd
, pgtable
);
2002 for (i
= 0, addr
= haddr
; i
< HPAGE_PMD_NR
; i
++, addr
+= PAGE_SIZE
) {
2005 * Note that NUMA hinting access restrictions are not
2006 * transferred to avoid any possibility of altering
2007 * permissions across VMAs.
2010 swp_entry_t swp_entry
;
2011 swp_entry
= make_migration_entry(page
+ i
, write
);
2012 entry
= swp_entry_to_pte(swp_entry
);
2014 entry
= pte_swp_mksoft_dirty(entry
);
2016 entry
= mk_pte(page
+ i
, READ_ONCE(vma
->vm_page_prot
));
2017 entry
= maybe_mkwrite(entry
, vma
);
2019 entry
= pte_wrprotect(entry
);
2021 entry
= pte_mkold(entry
);
2023 entry
= pte_mksoft_dirty(entry
);
2026 SetPageDirty(page
+ i
);
2027 pte
= pte_offset_map(&_pmd
, addr
);
2028 BUG_ON(!pte_none(*pte
));
2029 set_pte_at(mm
, addr
, pte
, entry
);
2030 atomic_inc(&page
[i
]._mapcount
);
2035 * Set PG_double_map before dropping compound_mapcount to avoid
2036 * false-negative page_mapped().
2038 if (compound_mapcount(page
) > 1 && !TestSetPageDoubleMap(page
)) {
2039 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2040 atomic_inc(&page
[i
]._mapcount
);
2043 if (atomic_add_negative(-1, compound_mapcount_ptr(page
))) {
2044 /* Last compound_mapcount is gone. */
2045 __dec_node_page_state(page
, NR_ANON_THPS
);
2046 if (TestClearPageDoubleMap(page
)) {
2047 /* No need in mapcount reference anymore */
2048 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2049 atomic_dec(&page
[i
]._mapcount
);
2053 smp_wmb(); /* make pte visible before pmd */
2055 * Up to this point the pmd is present and huge and userland has the
2056 * whole access to the hugepage during the split (which happens in
2057 * place). If we overwrite the pmd with the not-huge version pointing
2058 * to the pte here (which of course we could if all CPUs were bug
2059 * free), userland could trigger a small page size TLB miss on the
2060 * small sized TLB while the hugepage TLB entry is still established in
2061 * the huge TLB. Some CPU doesn't like that.
2062 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2063 * 383 on page 93. Intel should be safe but is also warns that it's
2064 * only safe if the permission and cache attributes of the two entries
2065 * loaded in the two TLB is identical (which should be the case here).
2066 * But it is generally safer to never allow small and huge TLB entries
2067 * for the same virtual address to be loaded simultaneously. So instead
2068 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2069 * current pmd notpresent (atomically because here the pmd_trans_huge
2070 * and pmd_trans_splitting must remain set at all times on the pmd
2071 * until the split is complete for this pmd), then we flush the SMP TLB
2072 * and finally we write the non-huge version of the pmd entry with
2075 pmdp_invalidate(vma
, haddr
, pmd
);
2076 pmd_populate(mm
, pmd
, pgtable
);
2079 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2080 page_remove_rmap(page
+ i
, false);
2086 void __split_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2087 unsigned long address
, bool freeze
, struct page
*page
)
2090 struct mm_struct
*mm
= vma
->vm_mm
;
2091 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
2093 mmu_notifier_invalidate_range_start(mm
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
2094 ptl
= pmd_lock(mm
, pmd
);
2097 * If caller asks to setup a migration entries, we need a page to check
2098 * pmd against. Otherwise we can end up replacing wrong page.
2100 VM_BUG_ON(freeze
&& !page
);
2101 if (page
&& page
!= pmd_page(*pmd
))
2104 if (pmd_trans_huge(*pmd
)) {
2105 page
= pmd_page(*pmd
);
2106 if (PageMlocked(page
))
2107 clear_page_mlock(page
);
2108 } else if (!pmd_devmap(*pmd
))
2110 __split_huge_pmd_locked(vma
, pmd
, haddr
, freeze
);
2113 mmu_notifier_invalidate_range_end(mm
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
2116 void split_huge_pmd_address(struct vm_area_struct
*vma
, unsigned long address
,
2117 bool freeze
, struct page
*page
)
2124 pgd
= pgd_offset(vma
->vm_mm
, address
);
2125 if (!pgd_present(*pgd
))
2128 p4d
= p4d_offset(pgd
, address
);
2129 if (!p4d_present(*p4d
))
2132 pud
= pud_offset(p4d
, address
);
2133 if (!pud_present(*pud
))
2136 pmd
= pmd_offset(pud
, address
);
2138 __split_huge_pmd(vma
, pmd
, address
, freeze
, page
);
2141 void vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2142 unsigned long start
,
2147 * If the new start address isn't hpage aligned and it could
2148 * previously contain an hugepage: check if we need to split
2151 if (start
& ~HPAGE_PMD_MASK
&&
2152 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2153 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2154 split_huge_pmd_address(vma
, start
, false, NULL
);
2157 * If the new end address isn't hpage aligned and it could
2158 * previously contain an hugepage: check if we need to split
2161 if (end
& ~HPAGE_PMD_MASK
&&
2162 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2163 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2164 split_huge_pmd_address(vma
, end
, false, NULL
);
2167 * If we're also updating the vma->vm_next->vm_start, if the new
2168 * vm_next->vm_start isn't page aligned and it could previously
2169 * contain an hugepage: check if we need to split an huge pmd.
2171 if (adjust_next
> 0) {
2172 struct vm_area_struct
*next
= vma
->vm_next
;
2173 unsigned long nstart
= next
->vm_start
;
2174 nstart
+= adjust_next
<< PAGE_SHIFT
;
2175 if (nstart
& ~HPAGE_PMD_MASK
&&
2176 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2177 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2178 split_huge_pmd_address(next
, nstart
, false, NULL
);
2182 static void freeze_page(struct page
*page
)
2184 enum ttu_flags ttu_flags
= TTU_IGNORE_MLOCK
| TTU_IGNORE_ACCESS
|
2185 TTU_RMAP_LOCKED
| TTU_SPLIT_HUGE_PMD
;
2188 VM_BUG_ON_PAGE(!PageHead(page
), page
);
2191 ttu_flags
|= TTU_MIGRATION
;
2193 unmap_success
= try_to_unmap(page
, ttu_flags
);
2194 VM_BUG_ON_PAGE(!unmap_success
, page
);
2197 static void unfreeze_page(struct page
*page
)
2200 if (PageTransHuge(page
)) {
2201 remove_migration_ptes(page
, page
, true);
2203 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2204 remove_migration_ptes(page
+ i
, page
+ i
, true);
2208 static void __split_huge_page_tail(struct page
*head
, int tail
,
2209 struct lruvec
*lruvec
, struct list_head
*list
)
2211 struct page
*page_tail
= head
+ tail
;
2213 VM_BUG_ON_PAGE(atomic_read(&page_tail
->_mapcount
) != -1, page_tail
);
2214 VM_BUG_ON_PAGE(page_ref_count(page_tail
) != 0, page_tail
);
2217 * tail_page->_refcount is zero and not changing from under us. But
2218 * get_page_unless_zero() may be running from under us on the
2219 * tail_page. If we used atomic_set() below instead of atomic_inc() or
2220 * atomic_add(), we would then run atomic_set() concurrently with
2221 * get_page_unless_zero(), and atomic_set() is implemented in C not
2222 * using locked ops. spin_unlock on x86 sometime uses locked ops
2223 * because of PPro errata 66, 92, so unless somebody can guarantee
2224 * atomic_set() here would be safe on all archs (and not only on x86),
2225 * it's safer to use atomic_inc()/atomic_add().
2227 if (PageAnon(head
) && !PageSwapCache(head
)) {
2228 page_ref_inc(page_tail
);
2230 /* Additional pin to radix tree */
2231 page_ref_add(page_tail
, 2);
2234 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
;
2235 page_tail
->flags
|= (head
->flags
&
2236 ((1L << PG_referenced
) |
2237 (1L << PG_swapbacked
) |
2238 (1L << PG_swapcache
) |
2239 (1L << PG_mlocked
) |
2240 (1L << PG_uptodate
) |
2243 (1L << PG_unevictable
) |
2247 * After clearing PageTail the gup refcount can be released.
2248 * Page flags also must be visible before we make the page non-compound.
2252 clear_compound_head(page_tail
);
2254 if (page_is_young(head
))
2255 set_page_young(page_tail
);
2256 if (page_is_idle(head
))
2257 set_page_idle(page_tail
);
2259 /* ->mapping in first tail page is compound_mapcount */
2260 VM_BUG_ON_PAGE(tail
> 2 && page_tail
->mapping
!= TAIL_MAPPING
,
2262 page_tail
->mapping
= head
->mapping
;
2264 page_tail
->index
= head
->index
+ tail
;
2265 page_cpupid_xchg_last(page_tail
, page_cpupid_last(head
));
2266 lru_add_page_tail(head
, page_tail
, lruvec
, list
);
2269 static void __split_huge_page(struct page
*page
, struct list_head
*list
,
2270 unsigned long flags
)
2272 struct page
*head
= compound_head(page
);
2273 struct zone
*zone
= page_zone(head
);
2274 struct lruvec
*lruvec
;
2278 lruvec
= mem_cgroup_page_lruvec(head
, zone
->zone_pgdat
);
2280 /* complete memcg works before add pages to LRU */
2281 mem_cgroup_split_huge_fixup(head
);
2283 if (!PageAnon(page
))
2284 end
= DIV_ROUND_UP(i_size_read(head
->mapping
->host
), PAGE_SIZE
);
2286 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
2287 __split_huge_page_tail(head
, i
, lruvec
, list
);
2288 /* Some pages can be beyond i_size: drop them from page cache */
2289 if (head
[i
].index
>= end
) {
2290 __ClearPageDirty(head
+ i
);
2291 __delete_from_page_cache(head
+ i
, NULL
);
2292 if (IS_ENABLED(CONFIG_SHMEM
) && PageSwapBacked(head
))
2293 shmem_uncharge(head
->mapping
->host
, 1);
2298 ClearPageCompound(head
);
2299 /* See comment in __split_huge_page_tail() */
2300 if (PageAnon(head
)) {
2301 /* Additional pin to radix tree of swap cache */
2302 if (PageSwapCache(head
))
2303 page_ref_add(head
, 2);
2307 /* Additional pin to radix tree */
2308 page_ref_add(head
, 2);
2309 spin_unlock(&head
->mapping
->tree_lock
);
2312 spin_unlock_irqrestore(zone_lru_lock(page_zone(head
)), flags
);
2314 unfreeze_page(head
);
2316 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2317 struct page
*subpage
= head
+ i
;
2318 if (subpage
== page
)
2320 unlock_page(subpage
);
2323 * Subpages may be freed if there wasn't any mapping
2324 * like if add_to_swap() is running on a lru page that
2325 * had its mapping zapped. And freeing these pages
2326 * requires taking the lru_lock so we do the put_page
2327 * of the tail pages after the split is complete.
2333 int total_mapcount(struct page
*page
)
2335 int i
, compound
, ret
;
2337 VM_BUG_ON_PAGE(PageTail(page
), page
);
2339 if (likely(!PageCompound(page
)))
2340 return atomic_read(&page
->_mapcount
) + 1;
2342 compound
= compound_mapcount(page
);
2346 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2347 ret
+= atomic_read(&page
[i
]._mapcount
) + 1;
2348 /* File pages has compound_mapcount included in _mapcount */
2349 if (!PageAnon(page
))
2350 return ret
- compound
* HPAGE_PMD_NR
;
2351 if (PageDoubleMap(page
))
2352 ret
-= HPAGE_PMD_NR
;
2357 * This calculates accurately how many mappings a transparent hugepage
2358 * has (unlike page_mapcount() which isn't fully accurate). This full
2359 * accuracy is primarily needed to know if copy-on-write faults can
2360 * reuse the page and change the mapping to read-write instead of
2361 * copying them. At the same time this returns the total_mapcount too.
2363 * The function returns the highest mapcount any one of the subpages
2364 * has. If the return value is one, even if different processes are
2365 * mapping different subpages of the transparent hugepage, they can
2366 * all reuse it, because each process is reusing a different subpage.
2368 * The total_mapcount is instead counting all virtual mappings of the
2369 * subpages. If the total_mapcount is equal to "one", it tells the
2370 * caller all mappings belong to the same "mm" and in turn the
2371 * anon_vma of the transparent hugepage can become the vma->anon_vma
2372 * local one as no other process may be mapping any of the subpages.
2374 * It would be more accurate to replace page_mapcount() with
2375 * page_trans_huge_mapcount(), however we only use
2376 * page_trans_huge_mapcount() in the copy-on-write faults where we
2377 * need full accuracy to avoid breaking page pinning, because
2378 * page_trans_huge_mapcount() is slower than page_mapcount().
2380 int page_trans_huge_mapcount(struct page
*page
, int *total_mapcount
)
2382 int i
, ret
, _total_mapcount
, mapcount
;
2384 /* hugetlbfs shouldn't call it */
2385 VM_BUG_ON_PAGE(PageHuge(page
), page
);
2387 if (likely(!PageTransCompound(page
))) {
2388 mapcount
= atomic_read(&page
->_mapcount
) + 1;
2390 *total_mapcount
= mapcount
;
2394 page
= compound_head(page
);
2396 _total_mapcount
= ret
= 0;
2397 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2398 mapcount
= atomic_read(&page
[i
]._mapcount
) + 1;
2399 ret
= max(ret
, mapcount
);
2400 _total_mapcount
+= mapcount
;
2402 if (PageDoubleMap(page
)) {
2404 _total_mapcount
-= HPAGE_PMD_NR
;
2406 mapcount
= compound_mapcount(page
);
2408 _total_mapcount
+= mapcount
;
2410 *total_mapcount
= _total_mapcount
;
2414 /* Racy check whether the huge page can be split */
2415 bool can_split_huge_page(struct page
*page
, int *pextra_pins
)
2419 /* Additional pins from radix tree */
2421 extra_pins
= PageSwapCache(page
) ? HPAGE_PMD_NR
: 0;
2423 extra_pins
= HPAGE_PMD_NR
;
2425 *pextra_pins
= extra_pins
;
2426 return total_mapcount(page
) == page_count(page
) - extra_pins
- 1;
2430 * This function splits huge page into normal pages. @page can point to any
2431 * subpage of huge page to split. Split doesn't change the position of @page.
2433 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2434 * The huge page must be locked.
2436 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2438 * Both head page and tail pages will inherit mapping, flags, and so on from
2441 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2442 * they are not mapped.
2444 * Returns 0 if the hugepage is split successfully.
2445 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2448 int split_huge_page_to_list(struct page
*page
, struct list_head
*list
)
2450 struct page
*head
= compound_head(page
);
2451 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(head
));
2452 struct anon_vma
*anon_vma
= NULL
;
2453 struct address_space
*mapping
= NULL
;
2454 int count
, mapcount
, extra_pins
, ret
;
2456 unsigned long flags
;
2458 VM_BUG_ON_PAGE(is_huge_zero_page(page
), page
);
2459 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2460 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
2462 if (PageAnon(head
)) {
2464 * The caller does not necessarily hold an mmap_sem that would
2465 * prevent the anon_vma disappearing so we first we take a
2466 * reference to it and then lock the anon_vma for write. This
2467 * is similar to page_lock_anon_vma_read except the write lock
2468 * is taken to serialise against parallel split or collapse
2471 anon_vma
= page_get_anon_vma(head
);
2477 anon_vma_lock_write(anon_vma
);
2479 mapping
= head
->mapping
;
2488 i_mmap_lock_read(mapping
);
2492 * Racy check if we can split the page, before freeze_page() will
2495 if (!can_split_huge_page(head
, &extra_pins
)) {
2500 mlocked
= PageMlocked(page
);
2502 VM_BUG_ON_PAGE(compound_mapcount(head
), head
);
2504 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2508 /* prevent PageLRU to go away from under us, and freeze lru stats */
2509 spin_lock_irqsave(zone_lru_lock(page_zone(head
)), flags
);
2514 spin_lock(&mapping
->tree_lock
);
2515 pslot
= radix_tree_lookup_slot(&mapping
->page_tree
,
2518 * Check if the head page is present in radix tree.
2519 * We assume all tail are present too, if head is there.
2521 if (radix_tree_deref_slot_protected(pslot
,
2522 &mapping
->tree_lock
) != head
)
2526 /* Prevent deferred_split_scan() touching ->_refcount */
2527 spin_lock(&pgdata
->split_queue_lock
);
2528 count
= page_count(head
);
2529 mapcount
= total_mapcount(head
);
2530 if (!mapcount
&& page_ref_freeze(head
, 1 + extra_pins
)) {
2531 if (!list_empty(page_deferred_list(head
))) {
2532 pgdata
->split_queue_len
--;
2533 list_del(page_deferred_list(head
));
2536 __dec_node_page_state(page
, NR_SHMEM_THPS
);
2537 spin_unlock(&pgdata
->split_queue_lock
);
2538 __split_huge_page(page
, list
, flags
);
2541 if (IS_ENABLED(CONFIG_DEBUG_VM
) && mapcount
) {
2542 pr_alert("total_mapcount: %u, page_count(): %u\n",
2545 dump_page(head
, NULL
);
2546 dump_page(page
, "total_mapcount(head) > 0");
2549 spin_unlock(&pgdata
->split_queue_lock
);
2551 spin_unlock(&mapping
->tree_lock
);
2552 spin_unlock_irqrestore(zone_lru_lock(page_zone(head
)), flags
);
2553 unfreeze_page(head
);
2559 anon_vma_unlock_write(anon_vma
);
2560 put_anon_vma(anon_vma
);
2563 i_mmap_unlock_read(mapping
);
2565 count_vm_event(!ret
? THP_SPLIT_PAGE
: THP_SPLIT_PAGE_FAILED
);
2569 void free_transhuge_page(struct page
*page
)
2571 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
2572 unsigned long flags
;
2574 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2575 if (!list_empty(page_deferred_list(page
))) {
2576 pgdata
->split_queue_len
--;
2577 list_del(page_deferred_list(page
));
2579 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2580 free_compound_page(page
);
2583 void deferred_split_huge_page(struct page
*page
)
2585 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
2586 unsigned long flags
;
2588 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
2590 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2591 if (list_empty(page_deferred_list(page
))) {
2592 count_vm_event(THP_DEFERRED_SPLIT_PAGE
);
2593 list_add_tail(page_deferred_list(page
), &pgdata
->split_queue
);
2594 pgdata
->split_queue_len
++;
2596 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2599 static unsigned long deferred_split_count(struct shrinker
*shrink
,
2600 struct shrink_control
*sc
)
2602 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2603 return ACCESS_ONCE(pgdata
->split_queue_len
);
2606 static unsigned long deferred_split_scan(struct shrinker
*shrink
,
2607 struct shrink_control
*sc
)
2609 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2610 unsigned long flags
;
2611 LIST_HEAD(list
), *pos
, *next
;
2615 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2616 /* Take pin on all head pages to avoid freeing them under us */
2617 list_for_each_safe(pos
, next
, &pgdata
->split_queue
) {
2618 page
= list_entry((void *)pos
, struct page
, mapping
);
2619 page
= compound_head(page
);
2620 if (get_page_unless_zero(page
)) {
2621 list_move(page_deferred_list(page
), &list
);
2623 /* We lost race with put_compound_page() */
2624 list_del_init(page_deferred_list(page
));
2625 pgdata
->split_queue_len
--;
2627 if (!--sc
->nr_to_scan
)
2630 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2632 list_for_each_safe(pos
, next
, &list
) {
2633 page
= list_entry((void *)pos
, struct page
, mapping
);
2635 /* split_huge_page() removes page from list on success */
2636 if (!split_huge_page(page
))
2642 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2643 list_splice_tail(&list
, &pgdata
->split_queue
);
2644 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2647 * Stop shrinker if we didn't split any page, but the queue is empty.
2648 * This can happen if pages were freed under us.
2650 if (!split
&& list_empty(&pgdata
->split_queue
))
2655 static struct shrinker deferred_split_shrinker
= {
2656 .count_objects
= deferred_split_count
,
2657 .scan_objects
= deferred_split_scan
,
2658 .seeks
= DEFAULT_SEEKS
,
2659 .flags
= SHRINKER_NUMA_AWARE
,
2662 #ifdef CONFIG_DEBUG_FS
2663 static int split_huge_pages_set(void *data
, u64 val
)
2667 unsigned long pfn
, max_zone_pfn
;
2668 unsigned long total
= 0, split
= 0;
2673 for_each_populated_zone(zone
) {
2674 max_zone_pfn
= zone_end_pfn(zone
);
2675 for (pfn
= zone
->zone_start_pfn
; pfn
< max_zone_pfn
; pfn
++) {
2676 if (!pfn_valid(pfn
))
2679 page
= pfn_to_page(pfn
);
2680 if (!get_page_unless_zero(page
))
2683 if (zone
!= page_zone(page
))
2686 if (!PageHead(page
) || PageHuge(page
) || !PageLRU(page
))
2691 if (!split_huge_page(page
))
2699 pr_info("%lu of %lu THP split\n", split
, total
);
2703 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops
, NULL
, split_huge_pages_set
,
2706 static int __init
split_huge_pages_debugfs(void)
2710 ret
= debugfs_create_file("split_huge_pages", 0200, NULL
, NULL
,
2711 &split_huge_pages_fops
);
2713 pr_warn("Failed to create split_huge_pages in debugfs");
2716 late_initcall(split_huge_pages_debugfs
);