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 const 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
, vmf
->address
, 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
);
932 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
933 if (unlikely(is_swap_pmd(pmd
))) {
934 swp_entry_t entry
= pmd_to_swp_entry(pmd
);
936 VM_BUG_ON(!is_pmd_migration_entry(pmd
));
937 if (is_write_migration_entry(entry
)) {
938 make_migration_entry_read(&entry
);
939 pmd
= swp_entry_to_pmd(entry
);
940 if (pmd_swp_soft_dirty(*src_pmd
))
941 pmd
= pmd_swp_mksoft_dirty(pmd
);
942 set_pmd_at(src_mm
, addr
, src_pmd
, pmd
);
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
);
947 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
953 if (unlikely(!pmd_trans_huge(pmd
))) {
954 pte_free(dst_mm
, pgtable
);
958 * When page table lock is held, the huge zero pmd should not be
959 * under splitting since we don't split the page itself, only pmd to
962 if (is_huge_zero_pmd(pmd
)) {
963 struct page
*zero_page
;
965 * get_huge_zero_page() will never allocate a new page here,
966 * since we already have a zero page to copy. It just takes a
969 zero_page
= mm_get_huge_zero_page(dst_mm
);
970 set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
976 src_page
= pmd_page(pmd
);
977 VM_BUG_ON_PAGE(!PageHead(src_page
), src_page
);
979 page_dup_rmap(src_page
, true);
980 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
981 atomic_long_inc(&dst_mm
->nr_ptes
);
982 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
984 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
985 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
986 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
990 spin_unlock(src_ptl
);
991 spin_unlock(dst_ptl
);
996 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
997 static void touch_pud(struct vm_area_struct
*vma
, unsigned long addr
,
1003 * We should set the dirty bit only for FOLL_WRITE but for now
1004 * the dirty bit in the pud is meaningless. And if the dirty
1005 * bit will become meaningful and we'll only set it with
1006 * FOLL_WRITE, an atomic set_bit will be required on the pud to
1007 * set the young bit, instead of the current set_pud_at.
1009 _pud
= pud_mkyoung(pud_mkdirty(*pud
));
1010 if (pudp_set_access_flags(vma
, addr
& HPAGE_PUD_MASK
,
1012 update_mmu_cache_pud(vma
, addr
, pud
);
1015 struct page
*follow_devmap_pud(struct vm_area_struct
*vma
, unsigned long addr
,
1016 pud_t
*pud
, int flags
)
1018 unsigned long pfn
= pud_pfn(*pud
);
1019 struct mm_struct
*mm
= vma
->vm_mm
;
1020 struct dev_pagemap
*pgmap
;
1023 assert_spin_locked(pud_lockptr(mm
, pud
));
1025 if (flags
& FOLL_WRITE
&& !pud_write(*pud
))
1028 if (pud_present(*pud
) && pud_devmap(*pud
))
1033 if (flags
& FOLL_TOUCH
)
1034 touch_pud(vma
, addr
, pud
);
1037 * device mapped pages can only be returned if the
1038 * caller will manage the page reference count.
1040 if (!(flags
& FOLL_GET
))
1041 return ERR_PTR(-EEXIST
);
1043 pfn
+= (addr
& ~PUD_MASK
) >> PAGE_SHIFT
;
1044 pgmap
= get_dev_pagemap(pfn
, NULL
);
1046 return ERR_PTR(-EFAULT
);
1047 page
= pfn_to_page(pfn
);
1049 put_dev_pagemap(pgmap
);
1054 int copy_huge_pud(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1055 pud_t
*dst_pud
, pud_t
*src_pud
, unsigned long addr
,
1056 struct vm_area_struct
*vma
)
1058 spinlock_t
*dst_ptl
, *src_ptl
;
1062 dst_ptl
= pud_lock(dst_mm
, dst_pud
);
1063 src_ptl
= pud_lockptr(src_mm
, src_pud
);
1064 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
1068 if (unlikely(!pud_trans_huge(pud
) && !pud_devmap(pud
)))
1072 * When page table lock is held, the huge zero pud should not be
1073 * under splitting since we don't split the page itself, only pud to
1076 if (is_huge_zero_pud(pud
)) {
1077 /* No huge zero pud yet */
1080 pudp_set_wrprotect(src_mm
, addr
, src_pud
);
1081 pud
= pud_mkold(pud_wrprotect(pud
));
1082 set_pud_at(dst_mm
, addr
, dst_pud
, pud
);
1086 spin_unlock(src_ptl
);
1087 spin_unlock(dst_ptl
);
1091 void huge_pud_set_accessed(struct vm_fault
*vmf
, pud_t orig_pud
)
1094 unsigned long haddr
;
1095 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1097 vmf
->ptl
= pud_lock(vmf
->vma
->vm_mm
, vmf
->pud
);
1098 if (unlikely(!pud_same(*vmf
->pud
, orig_pud
)))
1101 entry
= pud_mkyoung(orig_pud
);
1103 entry
= pud_mkdirty(entry
);
1104 haddr
= vmf
->address
& HPAGE_PUD_MASK
;
1105 if (pudp_set_access_flags(vmf
->vma
, haddr
, vmf
->pud
, entry
, write
))
1106 update_mmu_cache_pud(vmf
->vma
, vmf
->address
, vmf
->pud
);
1109 spin_unlock(vmf
->ptl
);
1111 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1113 void huge_pmd_set_accessed(struct vm_fault
*vmf
, pmd_t orig_pmd
)
1116 unsigned long haddr
;
1117 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1119 vmf
->ptl
= pmd_lock(vmf
->vma
->vm_mm
, vmf
->pmd
);
1120 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1123 entry
= pmd_mkyoung(orig_pmd
);
1125 entry
= pmd_mkdirty(entry
);
1126 haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1127 if (pmdp_set_access_flags(vmf
->vma
, haddr
, vmf
->pmd
, entry
, write
))
1128 update_mmu_cache_pmd(vmf
->vma
, vmf
->address
, vmf
->pmd
);
1131 spin_unlock(vmf
->ptl
);
1134 static int do_huge_pmd_wp_page_fallback(struct vm_fault
*vmf
, pmd_t orig_pmd
,
1137 struct vm_area_struct
*vma
= vmf
->vma
;
1138 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1139 struct mem_cgroup
*memcg
;
1143 struct page
**pages
;
1144 unsigned long mmun_start
; /* For mmu_notifiers */
1145 unsigned long mmun_end
; /* For mmu_notifiers */
1147 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
1149 if (unlikely(!pages
)) {
1150 ret
|= VM_FAULT_OOM
;
1154 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1155 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
, vma
,
1156 vmf
->address
, page_to_nid(page
));
1157 if (unlikely(!pages
[i
] ||
1158 mem_cgroup_try_charge(pages
[i
], vma
->vm_mm
,
1159 GFP_KERNEL
, &memcg
, false))) {
1163 memcg
= (void *)page_private(pages
[i
]);
1164 set_page_private(pages
[i
], 0);
1165 mem_cgroup_cancel_charge(pages
[i
], memcg
,
1170 ret
|= VM_FAULT_OOM
;
1173 set_page_private(pages
[i
], (unsigned long)memcg
);
1176 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1177 copy_user_highpage(pages
[i
], page
+ i
,
1178 haddr
+ PAGE_SIZE
* i
, vma
);
1179 __SetPageUptodate(pages
[i
]);
1184 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1185 mmu_notifier_invalidate_range_start(vma
->vm_mm
, mmun_start
, mmun_end
);
1187 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1188 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1189 goto out_free_pages
;
1190 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1192 pmdp_huge_clear_flush_notify(vma
, haddr
, vmf
->pmd
);
1193 /* leave pmd empty until pte is filled */
1195 pgtable
= pgtable_trans_huge_withdraw(vma
->vm_mm
, vmf
->pmd
);
1196 pmd_populate(vma
->vm_mm
, &_pmd
, pgtable
);
1198 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1200 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1201 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1202 memcg
= (void *)page_private(pages
[i
]);
1203 set_page_private(pages
[i
], 0);
1204 page_add_new_anon_rmap(pages
[i
], vmf
->vma
, haddr
, false);
1205 mem_cgroup_commit_charge(pages
[i
], memcg
, false, false);
1206 lru_cache_add_active_or_unevictable(pages
[i
], vma
);
1207 vmf
->pte
= pte_offset_map(&_pmd
, haddr
);
1208 VM_BUG_ON(!pte_none(*vmf
->pte
));
1209 set_pte_at(vma
->vm_mm
, haddr
, vmf
->pte
, entry
);
1210 pte_unmap(vmf
->pte
);
1214 smp_wmb(); /* make pte visible before pmd */
1215 pmd_populate(vma
->vm_mm
, vmf
->pmd
, pgtable
);
1216 page_remove_rmap(page
, true);
1217 spin_unlock(vmf
->ptl
);
1219 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
1221 ret
|= VM_FAULT_WRITE
;
1228 spin_unlock(vmf
->ptl
);
1229 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
1230 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1231 memcg
= (void *)page_private(pages
[i
]);
1232 set_page_private(pages
[i
], 0);
1233 mem_cgroup_cancel_charge(pages
[i
], memcg
, false);
1240 int do_huge_pmd_wp_page(struct vm_fault
*vmf
, pmd_t orig_pmd
)
1242 struct vm_area_struct
*vma
= vmf
->vma
;
1243 struct page
*page
= NULL
, *new_page
;
1244 struct mem_cgroup
*memcg
;
1245 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1246 unsigned long mmun_start
; /* For mmu_notifiers */
1247 unsigned long mmun_end
; /* For mmu_notifiers */
1248 gfp_t huge_gfp
; /* for allocation and charge */
1251 vmf
->ptl
= pmd_lockptr(vma
->vm_mm
, vmf
->pmd
);
1252 VM_BUG_ON_VMA(!vma
->anon_vma
, vma
);
1253 if (is_huge_zero_pmd(orig_pmd
))
1255 spin_lock(vmf
->ptl
);
1256 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1259 page
= pmd_page(orig_pmd
);
1260 VM_BUG_ON_PAGE(!PageCompound(page
) || !PageHead(page
), page
);
1262 * We can only reuse the page if nobody else maps the huge page or it's
1265 if (!trylock_page(page
)) {
1267 spin_unlock(vmf
->ptl
);
1269 spin_lock(vmf
->ptl
);
1270 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
))) {
1277 if (reuse_swap_page(page
, NULL
)) {
1279 entry
= pmd_mkyoung(orig_pmd
);
1280 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1281 if (pmdp_set_access_flags(vma
, haddr
, vmf
->pmd
, entry
, 1))
1282 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1283 ret
|= VM_FAULT_WRITE
;
1289 spin_unlock(vmf
->ptl
);
1291 if (transparent_hugepage_enabled(vma
) &&
1292 !transparent_hugepage_debug_cow()) {
1293 huge_gfp
= alloc_hugepage_direct_gfpmask(vma
);
1294 new_page
= alloc_hugepage_vma(huge_gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
1298 if (likely(new_page
)) {
1299 prep_transhuge_page(new_page
);
1302 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1303 ret
|= VM_FAULT_FALLBACK
;
1305 ret
= do_huge_pmd_wp_page_fallback(vmf
, orig_pmd
, page
);
1306 if (ret
& VM_FAULT_OOM
) {
1307 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1308 ret
|= VM_FAULT_FALLBACK
;
1312 count_vm_event(THP_FAULT_FALLBACK
);
1316 if (unlikely(mem_cgroup_try_charge(new_page
, vma
->vm_mm
,
1317 huge_gfp
, &memcg
, true))) {
1319 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1322 ret
|= VM_FAULT_FALLBACK
;
1323 count_vm_event(THP_FAULT_FALLBACK
);
1327 count_vm_event(THP_FAULT_ALLOC
);
1330 clear_huge_page(new_page
, vmf
->address
, HPAGE_PMD_NR
);
1332 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
1333 __SetPageUptodate(new_page
);
1336 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1337 mmu_notifier_invalidate_range_start(vma
->vm_mm
, mmun_start
, mmun_end
);
1339 spin_lock(vmf
->ptl
);
1342 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
))) {
1343 spin_unlock(vmf
->ptl
);
1344 mem_cgroup_cancel_charge(new_page
, memcg
, true);
1349 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
1350 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1351 pmdp_huge_clear_flush_notify(vma
, haddr
, vmf
->pmd
);
1352 page_add_new_anon_rmap(new_page
, vma
, haddr
, true);
1353 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
1354 lru_cache_add_active_or_unevictable(new_page
, vma
);
1355 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
1356 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1358 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1360 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1361 page_remove_rmap(page
, true);
1364 ret
|= VM_FAULT_WRITE
;
1366 spin_unlock(vmf
->ptl
);
1368 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
1372 spin_unlock(vmf
->ptl
);
1377 * FOLL_FORCE can write to even unwritable pmd's, but only
1378 * after we've gone through a COW cycle and they are dirty.
1380 static inline bool can_follow_write_pmd(pmd_t pmd
, unsigned int flags
)
1382 return pmd_write(pmd
) ||
1383 ((flags
& FOLL_FORCE
) && (flags
& FOLL_COW
) && pmd_dirty(pmd
));
1386 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1391 struct mm_struct
*mm
= vma
->vm_mm
;
1392 struct page
*page
= NULL
;
1394 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1396 if (flags
& FOLL_WRITE
&& !can_follow_write_pmd(*pmd
, flags
))
1399 /* Avoid dumping huge zero page */
1400 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1401 return ERR_PTR(-EFAULT
);
1403 /* Full NUMA hinting faults to serialise migration in fault paths */
1404 if ((flags
& FOLL_NUMA
) && pmd_protnone(*pmd
))
1407 page
= pmd_page(*pmd
);
1408 VM_BUG_ON_PAGE(!PageHead(page
) && !is_zone_device_page(page
), page
);
1409 if (flags
& FOLL_TOUCH
)
1410 touch_pmd(vma
, addr
, pmd
);
1411 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1413 * We don't mlock() pte-mapped THPs. This way we can avoid
1414 * leaking mlocked pages into non-VM_LOCKED VMAs.
1418 * In most cases the pmd is the only mapping of the page as we
1419 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1420 * writable private mappings in populate_vma_page_range().
1422 * The only scenario when we have the page shared here is if we
1423 * mlocking read-only mapping shared over fork(). We skip
1424 * mlocking such pages.
1428 * We can expect PageDoubleMap() to be stable under page lock:
1429 * for file pages we set it in page_add_file_rmap(), which
1430 * requires page to be locked.
1433 if (PageAnon(page
) && compound_mapcount(page
) != 1)
1435 if (PageDoubleMap(page
) || !page
->mapping
)
1437 if (!trylock_page(page
))
1440 if (page
->mapping
&& !PageDoubleMap(page
))
1441 mlock_vma_page(page
);
1445 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1446 VM_BUG_ON_PAGE(!PageCompound(page
) && !is_zone_device_page(page
), page
);
1447 if (flags
& FOLL_GET
)
1454 /* NUMA hinting page fault entry point for trans huge pmds */
1455 int do_huge_pmd_numa_page(struct vm_fault
*vmf
, pmd_t pmd
)
1457 struct vm_area_struct
*vma
= vmf
->vma
;
1458 struct anon_vma
*anon_vma
= NULL
;
1460 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1461 int page_nid
= -1, this_nid
= numa_node_id();
1462 int target_nid
, last_cpupid
= -1;
1464 bool migrated
= false;
1468 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1469 if (unlikely(!pmd_same(pmd
, *vmf
->pmd
)))
1473 * If there are potential migrations, wait for completion and retry
1474 * without disrupting NUMA hinting information. Do not relock and
1475 * check_same as the page may no longer be mapped.
1477 if (unlikely(pmd_trans_migrating(*vmf
->pmd
))) {
1478 page
= pmd_page(*vmf
->pmd
);
1479 if (!get_page_unless_zero(page
))
1481 spin_unlock(vmf
->ptl
);
1482 wait_on_page_locked(page
);
1487 page
= pmd_page(pmd
);
1488 BUG_ON(is_huge_zero_page(page
));
1489 page_nid
= page_to_nid(page
);
1490 last_cpupid
= page_cpupid_last(page
);
1491 count_vm_numa_event(NUMA_HINT_FAULTS
);
1492 if (page_nid
== this_nid
) {
1493 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
1494 flags
|= TNF_FAULT_LOCAL
;
1497 /* See similar comment in do_numa_page for explanation */
1498 if (!pmd_savedwrite(pmd
))
1499 flags
|= TNF_NO_GROUP
;
1502 * Acquire the page lock to serialise THP migrations but avoid dropping
1503 * page_table_lock if at all possible
1505 page_locked
= trylock_page(page
);
1506 target_nid
= mpol_misplaced(page
, vma
, haddr
);
1507 if (target_nid
== -1) {
1508 /* If the page was locked, there are no parallel migrations */
1513 /* Migration could have started since the pmd_trans_migrating check */
1516 if (!get_page_unless_zero(page
))
1518 spin_unlock(vmf
->ptl
);
1519 wait_on_page_locked(page
);
1525 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1526 * to serialises splits
1529 spin_unlock(vmf
->ptl
);
1530 anon_vma
= page_lock_anon_vma_read(page
);
1532 /* Confirm the PMD did not change while page_table_lock was released */
1533 spin_lock(vmf
->ptl
);
1534 if (unlikely(!pmd_same(pmd
, *vmf
->pmd
))) {
1541 /* Bail if we fail to protect against THP splits for any reason */
1542 if (unlikely(!anon_vma
)) {
1549 * Since we took the NUMA fault, we must have observed the !accessible
1550 * bit. Make sure all other CPUs agree with that, to avoid them
1551 * modifying the page we're about to migrate.
1553 * Must be done under PTL such that we'll observe the relevant
1554 * inc_tlb_flush_pending().
1556 * We are not sure a pending tlb flush here is for a huge page
1557 * mapping or not. Hence use the tlb range variant
1559 if (mm_tlb_flush_pending(vma
->vm_mm
))
1560 flush_tlb_range(vma
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
1563 * Migrate the THP to the requested node, returns with page unlocked
1564 * and access rights restored.
1566 spin_unlock(vmf
->ptl
);
1568 migrated
= migrate_misplaced_transhuge_page(vma
->vm_mm
, vma
,
1569 vmf
->pmd
, pmd
, vmf
->address
, page
, target_nid
);
1571 flags
|= TNF_MIGRATED
;
1572 page_nid
= target_nid
;
1574 flags
|= TNF_MIGRATE_FAIL
;
1578 BUG_ON(!PageLocked(page
));
1579 was_writable
= pmd_savedwrite(pmd
);
1580 pmd
= pmd_modify(pmd
, vma
->vm_page_prot
);
1581 pmd
= pmd_mkyoung(pmd
);
1583 pmd
= pmd_mkwrite(pmd
);
1584 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, pmd
);
1585 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1588 spin_unlock(vmf
->ptl
);
1592 page_unlock_anon_vma_read(anon_vma
);
1595 task_numa_fault(last_cpupid
, page_nid
, HPAGE_PMD_NR
,
1602 * Return true if we do MADV_FREE successfully on entire pmd page.
1603 * Otherwise, return false.
1605 bool madvise_free_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1606 pmd_t
*pmd
, unsigned long addr
, unsigned long next
)
1611 struct mm_struct
*mm
= tlb
->mm
;
1614 tlb_remove_check_page_size_change(tlb
, HPAGE_PMD_SIZE
);
1616 ptl
= pmd_trans_huge_lock(pmd
, vma
);
1621 if (is_huge_zero_pmd(orig_pmd
))
1624 if (unlikely(!pmd_present(orig_pmd
))) {
1625 VM_BUG_ON(thp_migration_supported() &&
1626 !is_pmd_migration_entry(orig_pmd
));
1630 page
= pmd_page(orig_pmd
);
1632 * If other processes are mapping this page, we couldn't discard
1633 * the page unless they all do MADV_FREE so let's skip the page.
1635 if (page_mapcount(page
) != 1)
1638 if (!trylock_page(page
))
1642 * If user want to discard part-pages of THP, split it so MADV_FREE
1643 * will deactivate only them.
1645 if (next
- addr
!= HPAGE_PMD_SIZE
) {
1648 split_huge_page(page
);
1654 if (PageDirty(page
))
1655 ClearPageDirty(page
);
1658 if (pmd_young(orig_pmd
) || pmd_dirty(orig_pmd
)) {
1659 pmdp_invalidate(vma
, addr
, pmd
);
1660 orig_pmd
= pmd_mkold(orig_pmd
);
1661 orig_pmd
= pmd_mkclean(orig_pmd
);
1663 set_pmd_at(mm
, addr
, pmd
, orig_pmd
);
1664 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1667 mark_page_lazyfree(page
);
1675 static inline void zap_deposited_table(struct mm_struct
*mm
, pmd_t
*pmd
)
1679 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1680 pte_free(mm
, pgtable
);
1681 atomic_long_dec(&mm
->nr_ptes
);
1684 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1685 pmd_t
*pmd
, unsigned long addr
)
1690 tlb_remove_check_page_size_change(tlb
, HPAGE_PMD_SIZE
);
1692 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1696 * For architectures like ppc64 we look at deposited pgtable
1697 * when calling pmdp_huge_get_and_clear. So do the
1698 * pgtable_trans_huge_withdraw after finishing pmdp related
1701 orig_pmd
= pmdp_huge_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1703 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1704 if (vma_is_dax(vma
)) {
1705 if (arch_needs_pgtable_deposit())
1706 zap_deposited_table(tlb
->mm
, pmd
);
1708 if (is_huge_zero_pmd(orig_pmd
))
1709 tlb_remove_page_size(tlb
, pmd_page(orig_pmd
), HPAGE_PMD_SIZE
);
1710 } else if (is_huge_zero_pmd(orig_pmd
)) {
1711 zap_deposited_table(tlb
->mm
, pmd
);
1713 tlb_remove_page_size(tlb
, pmd_page(orig_pmd
), HPAGE_PMD_SIZE
);
1715 struct page
*page
= NULL
;
1716 int flush_needed
= 1;
1718 if (pmd_present(orig_pmd
)) {
1719 page
= pmd_page(orig_pmd
);
1720 page_remove_rmap(page
, true);
1721 VM_BUG_ON_PAGE(page_mapcount(page
) < 0, page
);
1722 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1723 } else if (thp_migration_supported()) {
1726 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd
));
1727 entry
= pmd_to_swp_entry(orig_pmd
);
1728 page
= pfn_to_page(swp_offset(entry
));
1731 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1733 if (PageAnon(page
)) {
1734 zap_deposited_table(tlb
->mm
, pmd
);
1735 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1737 if (arch_needs_pgtable_deposit())
1738 zap_deposited_table(tlb
->mm
, pmd
);
1739 add_mm_counter(tlb
->mm
, MM_FILEPAGES
, -HPAGE_PMD_NR
);
1744 tlb_remove_page_size(tlb
, page
, HPAGE_PMD_SIZE
);
1749 #ifndef pmd_move_must_withdraw
1750 static inline int pmd_move_must_withdraw(spinlock_t
*new_pmd_ptl
,
1751 spinlock_t
*old_pmd_ptl
,
1752 struct vm_area_struct
*vma
)
1755 * With split pmd lock we also need to move preallocated
1756 * PTE page table if new_pmd is on different PMD page table.
1758 * We also don't deposit and withdraw tables for file pages.
1760 return (new_pmd_ptl
!= old_pmd_ptl
) && vma_is_anonymous(vma
);
1764 static pmd_t
move_soft_dirty_pmd(pmd_t pmd
)
1766 #ifdef CONFIG_MEM_SOFT_DIRTY
1767 if (unlikely(is_pmd_migration_entry(pmd
)))
1768 pmd
= pmd_swp_mksoft_dirty(pmd
);
1769 else if (pmd_present(pmd
))
1770 pmd
= pmd_mksoft_dirty(pmd
);
1775 bool move_huge_pmd(struct vm_area_struct
*vma
, unsigned long old_addr
,
1776 unsigned long new_addr
, unsigned long old_end
,
1777 pmd_t
*old_pmd
, pmd_t
*new_pmd
, bool *need_flush
)
1779 spinlock_t
*old_ptl
, *new_ptl
;
1781 struct mm_struct
*mm
= vma
->vm_mm
;
1782 bool force_flush
= false;
1784 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1785 (new_addr
& ~HPAGE_PMD_MASK
) ||
1786 old_end
- old_addr
< HPAGE_PMD_SIZE
)
1790 * The destination pmd shouldn't be established, free_pgtables()
1791 * should have release it.
1793 if (WARN_ON(!pmd_none(*new_pmd
))) {
1794 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1799 * We don't have to worry about the ordering of src and dst
1800 * ptlocks because exclusive mmap_sem prevents deadlock.
1802 old_ptl
= __pmd_trans_huge_lock(old_pmd
, vma
);
1804 new_ptl
= pmd_lockptr(mm
, new_pmd
);
1805 if (new_ptl
!= old_ptl
)
1806 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
1807 pmd
= pmdp_huge_get_and_clear(mm
, old_addr
, old_pmd
);
1808 if (pmd_present(pmd
) && pmd_dirty(pmd
))
1810 VM_BUG_ON(!pmd_none(*new_pmd
));
1812 if (pmd_move_must_withdraw(new_ptl
, old_ptl
, vma
)) {
1814 pgtable
= pgtable_trans_huge_withdraw(mm
, old_pmd
);
1815 pgtable_trans_huge_deposit(mm
, new_pmd
, pgtable
);
1817 pmd
= move_soft_dirty_pmd(pmd
);
1818 set_pmd_at(mm
, new_addr
, new_pmd
, pmd
);
1819 if (new_ptl
!= old_ptl
)
1820 spin_unlock(new_ptl
);
1822 flush_tlb_range(vma
, old_addr
, old_addr
+ PMD_SIZE
);
1825 spin_unlock(old_ptl
);
1833 * - 0 if PMD could not be locked
1834 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1835 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1837 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1838 unsigned long addr
, pgprot_t newprot
, int prot_numa
)
1840 struct mm_struct
*mm
= vma
->vm_mm
;
1843 bool preserve_write
;
1846 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1850 preserve_write
= prot_numa
&& pmd_write(*pmd
);
1853 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1854 if (is_swap_pmd(*pmd
)) {
1855 swp_entry_t entry
= pmd_to_swp_entry(*pmd
);
1857 VM_BUG_ON(!is_pmd_migration_entry(*pmd
));
1858 if (is_write_migration_entry(entry
)) {
1861 * A protection check is difficult so
1862 * just be safe and disable write
1864 make_migration_entry_read(&entry
);
1865 newpmd
= swp_entry_to_pmd(entry
);
1866 if (pmd_swp_soft_dirty(*pmd
))
1867 newpmd
= pmd_swp_mksoft_dirty(newpmd
);
1868 set_pmd_at(mm
, addr
, pmd
, newpmd
);
1875 * Avoid trapping faults against the zero page. The read-only
1876 * data is likely to be read-cached on the local CPU and
1877 * local/remote hits to the zero page are not interesting.
1879 if (prot_numa
&& is_huge_zero_pmd(*pmd
))
1882 if (prot_numa
&& pmd_protnone(*pmd
))
1886 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1887 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1888 * which is also under down_read(mmap_sem):
1891 * change_huge_pmd(prot_numa=1)
1892 * pmdp_huge_get_and_clear_notify()
1893 * madvise_dontneed()
1895 * pmd_trans_huge(*pmd) == 0 (without ptl)
1898 * // pmd is re-established
1900 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1901 * which may break userspace.
1903 * pmdp_invalidate() is required to make sure we don't miss
1904 * dirty/young flags set by hardware.
1907 pmdp_invalidate(vma
, addr
, pmd
);
1910 * Recover dirty/young flags. It relies on pmdp_invalidate to not
1913 if (pmd_dirty(*pmd
))
1914 entry
= pmd_mkdirty(entry
);
1915 if (pmd_young(*pmd
))
1916 entry
= pmd_mkyoung(entry
);
1918 entry
= pmd_modify(entry
, newprot
);
1920 entry
= pmd_mk_savedwrite(entry
);
1922 set_pmd_at(mm
, addr
, pmd
, entry
);
1923 BUG_ON(vma_is_anonymous(vma
) && !preserve_write
&& pmd_write(entry
));
1930 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1932 * Note that if it returns page table lock pointer, this routine returns without
1933 * unlocking page table lock. So callers must unlock it.
1935 spinlock_t
*__pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1938 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
1939 if (likely(is_swap_pmd(*pmd
) || pmd_trans_huge(*pmd
) ||
1947 * Returns true if a given pud maps a thp, false otherwise.
1949 * Note that if it returns true, this routine returns without unlocking page
1950 * table lock. So callers must unlock it.
1952 spinlock_t
*__pud_trans_huge_lock(pud_t
*pud
, struct vm_area_struct
*vma
)
1956 ptl
= pud_lock(vma
->vm_mm
, pud
);
1957 if (likely(pud_trans_huge(*pud
) || pud_devmap(*pud
)))
1963 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1964 int zap_huge_pud(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1965 pud_t
*pud
, unsigned long addr
)
1970 ptl
= __pud_trans_huge_lock(pud
, vma
);
1974 * For architectures like ppc64 we look at deposited pgtable
1975 * when calling pudp_huge_get_and_clear. So do the
1976 * pgtable_trans_huge_withdraw after finishing pudp related
1979 orig_pud
= pudp_huge_get_and_clear_full(tlb
->mm
, addr
, pud
,
1981 tlb_remove_pud_tlb_entry(tlb
, pud
, addr
);
1982 if (vma_is_dax(vma
)) {
1984 /* No zero page support yet */
1986 /* No support for anonymous PUD pages yet */
1992 static void __split_huge_pud_locked(struct vm_area_struct
*vma
, pud_t
*pud
,
1993 unsigned long haddr
)
1995 VM_BUG_ON(haddr
& ~HPAGE_PUD_MASK
);
1996 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
1997 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PUD_SIZE
, vma
);
1998 VM_BUG_ON(!pud_trans_huge(*pud
) && !pud_devmap(*pud
));
2000 count_vm_event(THP_SPLIT_PUD
);
2002 pudp_huge_clear_flush_notify(vma
, haddr
, pud
);
2005 void __split_huge_pud(struct vm_area_struct
*vma
, pud_t
*pud
,
2006 unsigned long address
)
2009 struct mm_struct
*mm
= vma
->vm_mm
;
2010 unsigned long haddr
= address
& HPAGE_PUD_MASK
;
2012 mmu_notifier_invalidate_range_start(mm
, haddr
, haddr
+ HPAGE_PUD_SIZE
);
2013 ptl
= pud_lock(mm
, pud
);
2014 if (unlikely(!pud_trans_huge(*pud
) && !pud_devmap(*pud
)))
2016 __split_huge_pud_locked(vma
, pud
, haddr
);
2020 mmu_notifier_invalidate_range_end(mm
, haddr
, haddr
+ HPAGE_PUD_SIZE
);
2022 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2024 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
2025 unsigned long haddr
, pmd_t
*pmd
)
2027 struct mm_struct
*mm
= vma
->vm_mm
;
2032 /* leave pmd empty until pte is filled */
2033 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
2035 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2036 pmd_populate(mm
, &_pmd
, pgtable
);
2038 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2040 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2041 entry
= pte_mkspecial(entry
);
2042 pte
= pte_offset_map(&_pmd
, haddr
);
2043 VM_BUG_ON(!pte_none(*pte
));
2044 set_pte_at(mm
, haddr
, pte
, entry
);
2047 smp_wmb(); /* make pte visible before pmd */
2048 pmd_populate(mm
, pmd
, pgtable
);
2051 static void __split_huge_pmd_locked(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2052 unsigned long haddr
, bool freeze
)
2054 struct mm_struct
*mm
= vma
->vm_mm
;
2058 bool young
, write
, dirty
, soft_dirty
, pmd_migration
= false;
2062 VM_BUG_ON(haddr
& ~HPAGE_PMD_MASK
);
2063 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
2064 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
, vma
);
2065 VM_BUG_ON(!is_pmd_migration_entry(*pmd
) && !pmd_trans_huge(*pmd
)
2066 && !pmd_devmap(*pmd
));
2068 count_vm_event(THP_SPLIT_PMD
);
2070 if (!vma_is_anonymous(vma
)) {
2071 _pmd
= pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
2073 * We are going to unmap this huge page. So
2074 * just go ahead and zap it
2076 if (arch_needs_pgtable_deposit())
2077 zap_deposited_table(mm
, pmd
);
2078 if (vma_is_dax(vma
))
2080 page
= pmd_page(_pmd
);
2081 if (!PageReferenced(page
) && pmd_young(_pmd
))
2082 SetPageReferenced(page
);
2083 page_remove_rmap(page
, true);
2085 add_mm_counter(mm
, MM_FILEPAGES
, -HPAGE_PMD_NR
);
2087 } else if (is_huge_zero_pmd(*pmd
)) {
2088 return __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
2091 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2092 pmd_migration
= is_pmd_migration_entry(*pmd
);
2093 if (pmd_migration
) {
2096 entry
= pmd_to_swp_entry(*pmd
);
2097 page
= pfn_to_page(swp_offset(entry
));
2100 page
= pmd_page(*pmd
);
2101 VM_BUG_ON_PAGE(!page_count(page
), page
);
2102 page_ref_add(page
, HPAGE_PMD_NR
- 1);
2103 write
= pmd_write(*pmd
);
2104 young
= pmd_young(*pmd
);
2105 dirty
= pmd_dirty(*pmd
);
2106 soft_dirty
= pmd_soft_dirty(*pmd
);
2108 pmdp_huge_split_prepare(vma
, haddr
, pmd
);
2109 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2110 pmd_populate(mm
, &_pmd
, pgtable
);
2112 for (i
= 0, addr
= haddr
; i
< HPAGE_PMD_NR
; i
++, addr
+= PAGE_SIZE
) {
2115 * Note that NUMA hinting access restrictions are not
2116 * transferred to avoid any possibility of altering
2117 * permissions across VMAs.
2119 if (freeze
|| pmd_migration
) {
2120 swp_entry_t swp_entry
;
2121 swp_entry
= make_migration_entry(page
+ i
, write
);
2122 entry
= swp_entry_to_pte(swp_entry
);
2124 entry
= pte_swp_mksoft_dirty(entry
);
2126 entry
= mk_pte(page
+ i
, READ_ONCE(vma
->vm_page_prot
));
2127 entry
= maybe_mkwrite(entry
, vma
);
2129 entry
= pte_wrprotect(entry
);
2131 entry
= pte_mkold(entry
);
2133 entry
= pte_mksoft_dirty(entry
);
2136 SetPageDirty(page
+ i
);
2137 pte
= pte_offset_map(&_pmd
, addr
);
2138 BUG_ON(!pte_none(*pte
));
2139 set_pte_at(mm
, addr
, pte
, entry
);
2140 atomic_inc(&page
[i
]._mapcount
);
2145 * Set PG_double_map before dropping compound_mapcount to avoid
2146 * false-negative page_mapped().
2148 if (compound_mapcount(page
) > 1 && !TestSetPageDoubleMap(page
)) {
2149 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2150 atomic_inc(&page
[i
]._mapcount
);
2153 if (atomic_add_negative(-1, compound_mapcount_ptr(page
))) {
2154 /* Last compound_mapcount is gone. */
2155 __dec_node_page_state(page
, NR_ANON_THPS
);
2156 if (TestClearPageDoubleMap(page
)) {
2157 /* No need in mapcount reference anymore */
2158 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2159 atomic_dec(&page
[i
]._mapcount
);
2163 smp_wmb(); /* make pte visible before pmd */
2165 * Up to this point the pmd is present and huge and userland has the
2166 * whole access to the hugepage during the split (which happens in
2167 * place). If we overwrite the pmd with the not-huge version pointing
2168 * to the pte here (which of course we could if all CPUs were bug
2169 * free), userland could trigger a small page size TLB miss on the
2170 * small sized TLB while the hugepage TLB entry is still established in
2171 * the huge TLB. Some CPU doesn't like that.
2172 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2173 * 383 on page 93. Intel should be safe but is also warns that it's
2174 * only safe if the permission and cache attributes of the two entries
2175 * loaded in the two TLB is identical (which should be the case here).
2176 * But it is generally safer to never allow small and huge TLB entries
2177 * for the same virtual address to be loaded simultaneously. So instead
2178 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2179 * current pmd notpresent (atomically because here the pmd_trans_huge
2180 * and pmd_trans_splitting must remain set at all times on the pmd
2181 * until the split is complete for this pmd), then we flush the SMP TLB
2182 * and finally we write the non-huge version of the pmd entry with
2185 pmdp_invalidate(vma
, haddr
, pmd
);
2186 pmd_populate(mm
, pmd
, pgtable
);
2189 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2190 page_remove_rmap(page
+ i
, false);
2196 void __split_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2197 unsigned long address
, bool freeze
, struct page
*page
)
2200 struct mm_struct
*mm
= vma
->vm_mm
;
2201 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
2203 mmu_notifier_invalidate_range_start(mm
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
2204 ptl
= pmd_lock(mm
, pmd
);
2207 * If caller asks to setup a migration entries, we need a page to check
2208 * pmd against. Otherwise we can end up replacing wrong page.
2210 VM_BUG_ON(freeze
&& !page
);
2211 if (page
&& page
!= pmd_page(*pmd
))
2214 if (pmd_trans_huge(*pmd
)) {
2215 page
= pmd_page(*pmd
);
2216 if (PageMlocked(page
))
2217 clear_page_mlock(page
);
2218 } else if (!(pmd_devmap(*pmd
) || is_pmd_migration_entry(*pmd
)))
2220 __split_huge_pmd_locked(vma
, pmd
, haddr
, freeze
);
2223 mmu_notifier_invalidate_range_end(mm
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
2226 void split_huge_pmd_address(struct vm_area_struct
*vma
, unsigned long address
,
2227 bool freeze
, struct page
*page
)
2234 pgd
= pgd_offset(vma
->vm_mm
, address
);
2235 if (!pgd_present(*pgd
))
2238 p4d
= p4d_offset(pgd
, address
);
2239 if (!p4d_present(*p4d
))
2242 pud
= pud_offset(p4d
, address
);
2243 if (!pud_present(*pud
))
2246 pmd
= pmd_offset(pud
, address
);
2248 __split_huge_pmd(vma
, pmd
, address
, freeze
, page
);
2251 void vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2252 unsigned long start
,
2257 * If the new start address isn't hpage aligned and it could
2258 * previously contain an hugepage: check if we need to split
2261 if (start
& ~HPAGE_PMD_MASK
&&
2262 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2263 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2264 split_huge_pmd_address(vma
, start
, false, NULL
);
2267 * If the new end address isn't hpage aligned and it could
2268 * previously contain an hugepage: check if we need to split
2271 if (end
& ~HPAGE_PMD_MASK
&&
2272 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2273 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2274 split_huge_pmd_address(vma
, end
, false, NULL
);
2277 * If we're also updating the vma->vm_next->vm_start, if the new
2278 * vm_next->vm_start isn't page aligned and it could previously
2279 * contain an hugepage: check if we need to split an huge pmd.
2281 if (adjust_next
> 0) {
2282 struct vm_area_struct
*next
= vma
->vm_next
;
2283 unsigned long nstart
= next
->vm_start
;
2284 nstart
+= adjust_next
<< PAGE_SHIFT
;
2285 if (nstart
& ~HPAGE_PMD_MASK
&&
2286 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2287 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2288 split_huge_pmd_address(next
, nstart
, false, NULL
);
2292 static void freeze_page(struct page
*page
)
2294 enum ttu_flags ttu_flags
= TTU_IGNORE_MLOCK
| TTU_IGNORE_ACCESS
|
2295 TTU_RMAP_LOCKED
| TTU_SPLIT_HUGE_PMD
;
2298 VM_BUG_ON_PAGE(!PageHead(page
), page
);
2301 ttu_flags
|= TTU_SPLIT_FREEZE
;
2303 unmap_success
= try_to_unmap(page
, ttu_flags
);
2304 VM_BUG_ON_PAGE(!unmap_success
, page
);
2307 static void unfreeze_page(struct page
*page
)
2310 if (PageTransHuge(page
)) {
2311 remove_migration_ptes(page
, page
, true);
2313 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2314 remove_migration_ptes(page
+ i
, page
+ i
, true);
2318 static void __split_huge_page_tail(struct page
*head
, int tail
,
2319 struct lruvec
*lruvec
, struct list_head
*list
)
2321 struct page
*page_tail
= head
+ tail
;
2323 VM_BUG_ON_PAGE(atomic_read(&page_tail
->_mapcount
) != -1, page_tail
);
2324 VM_BUG_ON_PAGE(page_ref_count(page_tail
) != 0, page_tail
);
2327 * tail_page->_refcount is zero and not changing from under us. But
2328 * get_page_unless_zero() may be running from under us on the
2329 * tail_page. If we used atomic_set() below instead of atomic_inc() or
2330 * atomic_add(), we would then run atomic_set() concurrently with
2331 * get_page_unless_zero(), and atomic_set() is implemented in C not
2332 * using locked ops. spin_unlock on x86 sometime uses locked ops
2333 * because of PPro errata 66, 92, so unless somebody can guarantee
2334 * atomic_set() here would be safe on all archs (and not only on x86),
2335 * it's safer to use atomic_inc()/atomic_add().
2337 if (PageAnon(head
) && !PageSwapCache(head
)) {
2338 page_ref_inc(page_tail
);
2340 /* Additional pin to radix tree */
2341 page_ref_add(page_tail
, 2);
2344 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
;
2345 page_tail
->flags
|= (head
->flags
&
2346 ((1L << PG_referenced
) |
2347 (1L << PG_swapbacked
) |
2348 (1L << PG_swapcache
) |
2349 (1L << PG_mlocked
) |
2350 (1L << PG_uptodate
) |
2353 (1L << PG_unevictable
) |
2357 * After clearing PageTail the gup refcount can be released.
2358 * Page flags also must be visible before we make the page non-compound.
2362 clear_compound_head(page_tail
);
2364 if (page_is_young(head
))
2365 set_page_young(page_tail
);
2366 if (page_is_idle(head
))
2367 set_page_idle(page_tail
);
2369 /* ->mapping in first tail page is compound_mapcount */
2370 VM_BUG_ON_PAGE(tail
> 2 && page_tail
->mapping
!= TAIL_MAPPING
,
2372 page_tail
->mapping
= head
->mapping
;
2374 page_tail
->index
= head
->index
+ tail
;
2375 page_cpupid_xchg_last(page_tail
, page_cpupid_last(head
));
2376 lru_add_page_tail(head
, page_tail
, lruvec
, list
);
2379 static void __split_huge_page(struct page
*page
, struct list_head
*list
,
2380 unsigned long flags
)
2382 struct page
*head
= compound_head(page
);
2383 struct zone
*zone
= page_zone(head
);
2384 struct lruvec
*lruvec
;
2388 lruvec
= mem_cgroup_page_lruvec(head
, zone
->zone_pgdat
);
2390 /* complete memcg works before add pages to LRU */
2391 mem_cgroup_split_huge_fixup(head
);
2393 if (!PageAnon(page
))
2394 end
= DIV_ROUND_UP(i_size_read(head
->mapping
->host
), PAGE_SIZE
);
2396 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
2397 __split_huge_page_tail(head
, i
, lruvec
, list
);
2398 /* Some pages can be beyond i_size: drop them from page cache */
2399 if (head
[i
].index
>= end
) {
2400 __ClearPageDirty(head
+ i
);
2401 __delete_from_page_cache(head
+ i
, NULL
);
2402 if (IS_ENABLED(CONFIG_SHMEM
) && PageSwapBacked(head
))
2403 shmem_uncharge(head
->mapping
->host
, 1);
2408 ClearPageCompound(head
);
2409 /* See comment in __split_huge_page_tail() */
2410 if (PageAnon(head
)) {
2411 /* Additional pin to radix tree of swap cache */
2412 if (PageSwapCache(head
))
2413 page_ref_add(head
, 2);
2417 /* Additional pin to radix tree */
2418 page_ref_add(head
, 2);
2419 spin_unlock(&head
->mapping
->tree_lock
);
2422 spin_unlock_irqrestore(zone_lru_lock(page_zone(head
)), flags
);
2424 unfreeze_page(head
);
2426 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2427 struct page
*subpage
= head
+ i
;
2428 if (subpage
== page
)
2430 unlock_page(subpage
);
2433 * Subpages may be freed if there wasn't any mapping
2434 * like if add_to_swap() is running on a lru page that
2435 * had its mapping zapped. And freeing these pages
2436 * requires taking the lru_lock so we do the put_page
2437 * of the tail pages after the split is complete.
2443 int total_mapcount(struct page
*page
)
2445 int i
, compound
, ret
;
2447 VM_BUG_ON_PAGE(PageTail(page
), page
);
2449 if (likely(!PageCompound(page
)))
2450 return atomic_read(&page
->_mapcount
) + 1;
2452 compound
= compound_mapcount(page
);
2456 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2457 ret
+= atomic_read(&page
[i
]._mapcount
) + 1;
2458 /* File pages has compound_mapcount included in _mapcount */
2459 if (!PageAnon(page
))
2460 return ret
- compound
* HPAGE_PMD_NR
;
2461 if (PageDoubleMap(page
))
2462 ret
-= HPAGE_PMD_NR
;
2467 * This calculates accurately how many mappings a transparent hugepage
2468 * has (unlike page_mapcount() which isn't fully accurate). This full
2469 * accuracy is primarily needed to know if copy-on-write faults can
2470 * reuse the page and change the mapping to read-write instead of
2471 * copying them. At the same time this returns the total_mapcount too.
2473 * The function returns the highest mapcount any one of the subpages
2474 * has. If the return value is one, even if different processes are
2475 * mapping different subpages of the transparent hugepage, they can
2476 * all reuse it, because each process is reusing a different subpage.
2478 * The total_mapcount is instead counting all virtual mappings of the
2479 * subpages. If the total_mapcount is equal to "one", it tells the
2480 * caller all mappings belong to the same "mm" and in turn the
2481 * anon_vma of the transparent hugepage can become the vma->anon_vma
2482 * local one as no other process may be mapping any of the subpages.
2484 * It would be more accurate to replace page_mapcount() with
2485 * page_trans_huge_mapcount(), however we only use
2486 * page_trans_huge_mapcount() in the copy-on-write faults where we
2487 * need full accuracy to avoid breaking page pinning, because
2488 * page_trans_huge_mapcount() is slower than page_mapcount().
2490 int page_trans_huge_mapcount(struct page
*page
, int *total_mapcount
)
2492 int i
, ret
, _total_mapcount
, mapcount
;
2494 /* hugetlbfs shouldn't call it */
2495 VM_BUG_ON_PAGE(PageHuge(page
), page
);
2497 if (likely(!PageTransCompound(page
))) {
2498 mapcount
= atomic_read(&page
->_mapcount
) + 1;
2500 *total_mapcount
= mapcount
;
2504 page
= compound_head(page
);
2506 _total_mapcount
= ret
= 0;
2507 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2508 mapcount
= atomic_read(&page
[i
]._mapcount
) + 1;
2509 ret
= max(ret
, mapcount
);
2510 _total_mapcount
+= mapcount
;
2512 if (PageDoubleMap(page
)) {
2514 _total_mapcount
-= HPAGE_PMD_NR
;
2516 mapcount
= compound_mapcount(page
);
2518 _total_mapcount
+= mapcount
;
2520 *total_mapcount
= _total_mapcount
;
2524 /* Racy check whether the huge page can be split */
2525 bool can_split_huge_page(struct page
*page
, int *pextra_pins
)
2529 /* Additional pins from radix tree */
2531 extra_pins
= PageSwapCache(page
) ? HPAGE_PMD_NR
: 0;
2533 extra_pins
= HPAGE_PMD_NR
;
2535 *pextra_pins
= extra_pins
;
2536 return total_mapcount(page
) == page_count(page
) - extra_pins
- 1;
2540 * This function splits huge page into normal pages. @page can point to any
2541 * subpage of huge page to split. Split doesn't change the position of @page.
2543 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2544 * The huge page must be locked.
2546 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2548 * Both head page and tail pages will inherit mapping, flags, and so on from
2551 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2552 * they are not mapped.
2554 * Returns 0 if the hugepage is split successfully.
2555 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2558 int split_huge_page_to_list(struct page
*page
, struct list_head
*list
)
2560 struct page
*head
= compound_head(page
);
2561 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(head
));
2562 struct anon_vma
*anon_vma
= NULL
;
2563 struct address_space
*mapping
= NULL
;
2564 int count
, mapcount
, extra_pins
, ret
;
2566 unsigned long flags
;
2568 VM_BUG_ON_PAGE(is_huge_zero_page(page
), page
);
2569 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2570 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
2572 if (PageWriteback(page
))
2575 if (PageAnon(head
)) {
2577 * The caller does not necessarily hold an mmap_sem that would
2578 * prevent the anon_vma disappearing so we first we take a
2579 * reference to it and then lock the anon_vma for write. This
2580 * is similar to page_lock_anon_vma_read except the write lock
2581 * is taken to serialise against parallel split or collapse
2584 anon_vma
= page_get_anon_vma(head
);
2590 anon_vma_lock_write(anon_vma
);
2592 mapping
= head
->mapping
;
2601 i_mmap_lock_read(mapping
);
2605 * Racy check if we can split the page, before freeze_page() will
2608 if (!can_split_huge_page(head
, &extra_pins
)) {
2613 mlocked
= PageMlocked(page
);
2615 VM_BUG_ON_PAGE(compound_mapcount(head
), head
);
2617 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2621 /* prevent PageLRU to go away from under us, and freeze lru stats */
2622 spin_lock_irqsave(zone_lru_lock(page_zone(head
)), flags
);
2627 spin_lock(&mapping
->tree_lock
);
2628 pslot
= radix_tree_lookup_slot(&mapping
->page_tree
,
2631 * Check if the head page is present in radix tree.
2632 * We assume all tail are present too, if head is there.
2634 if (radix_tree_deref_slot_protected(pslot
,
2635 &mapping
->tree_lock
) != head
)
2639 /* Prevent deferred_split_scan() touching ->_refcount */
2640 spin_lock(&pgdata
->split_queue_lock
);
2641 count
= page_count(head
);
2642 mapcount
= total_mapcount(head
);
2643 if (!mapcount
&& page_ref_freeze(head
, 1 + extra_pins
)) {
2644 if (!list_empty(page_deferred_list(head
))) {
2645 pgdata
->split_queue_len
--;
2646 list_del(page_deferred_list(head
));
2649 __dec_node_page_state(page
, NR_SHMEM_THPS
);
2650 spin_unlock(&pgdata
->split_queue_lock
);
2651 __split_huge_page(page
, list
, flags
);
2652 if (PageSwapCache(head
)) {
2653 swp_entry_t entry
= { .val
= page_private(head
) };
2655 ret
= split_swap_cluster(entry
);
2659 if (IS_ENABLED(CONFIG_DEBUG_VM
) && mapcount
) {
2660 pr_alert("total_mapcount: %u, page_count(): %u\n",
2663 dump_page(head
, NULL
);
2664 dump_page(page
, "total_mapcount(head) > 0");
2667 spin_unlock(&pgdata
->split_queue_lock
);
2669 spin_unlock(&mapping
->tree_lock
);
2670 spin_unlock_irqrestore(zone_lru_lock(page_zone(head
)), flags
);
2671 unfreeze_page(head
);
2677 anon_vma_unlock_write(anon_vma
);
2678 put_anon_vma(anon_vma
);
2681 i_mmap_unlock_read(mapping
);
2683 count_vm_event(!ret
? THP_SPLIT_PAGE
: THP_SPLIT_PAGE_FAILED
);
2687 void free_transhuge_page(struct page
*page
)
2689 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
2690 unsigned long flags
;
2692 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2693 if (!list_empty(page_deferred_list(page
))) {
2694 pgdata
->split_queue_len
--;
2695 list_del(page_deferred_list(page
));
2697 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2698 free_compound_page(page
);
2701 void deferred_split_huge_page(struct page
*page
)
2703 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
2704 unsigned long flags
;
2706 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
2708 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2709 if (list_empty(page_deferred_list(page
))) {
2710 count_vm_event(THP_DEFERRED_SPLIT_PAGE
);
2711 list_add_tail(page_deferred_list(page
), &pgdata
->split_queue
);
2712 pgdata
->split_queue_len
++;
2714 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2717 static unsigned long deferred_split_count(struct shrinker
*shrink
,
2718 struct shrink_control
*sc
)
2720 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2721 return READ_ONCE(pgdata
->split_queue_len
);
2724 static unsigned long deferred_split_scan(struct shrinker
*shrink
,
2725 struct shrink_control
*sc
)
2727 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2728 unsigned long flags
;
2729 LIST_HEAD(list
), *pos
, *next
;
2733 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2734 /* Take pin on all head pages to avoid freeing them under us */
2735 list_for_each_safe(pos
, next
, &pgdata
->split_queue
) {
2736 page
= list_entry((void *)pos
, struct page
, mapping
);
2737 page
= compound_head(page
);
2738 if (get_page_unless_zero(page
)) {
2739 list_move(page_deferred_list(page
), &list
);
2741 /* We lost race with put_compound_page() */
2742 list_del_init(page_deferred_list(page
));
2743 pgdata
->split_queue_len
--;
2745 if (!--sc
->nr_to_scan
)
2748 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2750 list_for_each_safe(pos
, next
, &list
) {
2751 page
= list_entry((void *)pos
, struct page
, mapping
);
2753 /* split_huge_page() removes page from list on success */
2754 if (!split_huge_page(page
))
2760 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2761 list_splice_tail(&list
, &pgdata
->split_queue
);
2762 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2765 * Stop shrinker if we didn't split any page, but the queue is empty.
2766 * This can happen if pages were freed under us.
2768 if (!split
&& list_empty(&pgdata
->split_queue
))
2773 static struct shrinker deferred_split_shrinker
= {
2774 .count_objects
= deferred_split_count
,
2775 .scan_objects
= deferred_split_scan
,
2776 .seeks
= DEFAULT_SEEKS
,
2777 .flags
= SHRINKER_NUMA_AWARE
,
2780 #ifdef CONFIG_DEBUG_FS
2781 static int split_huge_pages_set(void *data
, u64 val
)
2785 unsigned long pfn
, max_zone_pfn
;
2786 unsigned long total
= 0, split
= 0;
2791 for_each_populated_zone(zone
) {
2792 max_zone_pfn
= zone_end_pfn(zone
);
2793 for (pfn
= zone
->zone_start_pfn
; pfn
< max_zone_pfn
; pfn
++) {
2794 if (!pfn_valid(pfn
))
2797 page
= pfn_to_page(pfn
);
2798 if (!get_page_unless_zero(page
))
2801 if (zone
!= page_zone(page
))
2804 if (!PageHead(page
) || PageHuge(page
) || !PageLRU(page
))
2809 if (!split_huge_page(page
))
2817 pr_info("%lu of %lu THP split\n", split
, total
);
2821 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops
, NULL
, split_huge_pages_set
,
2824 static int __init
split_huge_pages_debugfs(void)
2828 ret
= debugfs_create_file("split_huge_pages", 0200, NULL
, NULL
,
2829 &split_huge_pages_fops
);
2831 pr_warn("Failed to create split_huge_pages in debugfs");
2834 late_initcall(split_huge_pages_debugfs
);
2837 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2838 void set_pmd_migration_entry(struct page_vma_mapped_walk
*pvmw
,
2841 struct vm_area_struct
*vma
= pvmw
->vma
;
2842 struct mm_struct
*mm
= vma
->vm_mm
;
2843 unsigned long address
= pvmw
->address
;
2848 if (!(pvmw
->pmd
&& !pvmw
->pte
))
2851 mmu_notifier_invalidate_range_start(mm
, address
,
2852 address
+ HPAGE_PMD_SIZE
);
2854 flush_cache_range(vma
, address
, address
+ HPAGE_PMD_SIZE
);
2855 pmdval
= *pvmw
->pmd
;
2856 pmdp_invalidate(vma
, address
, pvmw
->pmd
);
2857 if (pmd_dirty(pmdval
))
2858 set_page_dirty(page
);
2859 entry
= make_migration_entry(page
, pmd_write(pmdval
));
2860 pmdswp
= swp_entry_to_pmd(entry
);
2861 if (pmd_soft_dirty(pmdval
))
2862 pmdswp
= pmd_swp_mksoft_dirty(pmdswp
);
2863 set_pmd_at(mm
, address
, pvmw
->pmd
, pmdswp
);
2864 page_remove_rmap(page
, true);
2867 mmu_notifier_invalidate_range_end(mm
, address
,
2868 address
+ HPAGE_PMD_SIZE
);
2871 void remove_migration_pmd(struct page_vma_mapped_walk
*pvmw
, struct page
*new)
2873 struct vm_area_struct
*vma
= pvmw
->vma
;
2874 struct mm_struct
*mm
= vma
->vm_mm
;
2875 unsigned long address
= pvmw
->address
;
2876 unsigned long mmun_start
= address
& HPAGE_PMD_MASK
;
2880 if (!(pvmw
->pmd
&& !pvmw
->pte
))
2883 entry
= pmd_to_swp_entry(*pvmw
->pmd
);
2885 pmde
= pmd_mkold(mk_huge_pmd(new, vma
->vm_page_prot
));
2886 if (pmd_swp_soft_dirty(*pvmw
->pmd
))
2887 pmde
= pmd_mksoft_dirty(pmde
);
2888 if (is_write_migration_entry(entry
))
2889 pmde
= maybe_pmd_mkwrite(pmde
, vma
);
2891 flush_cache_range(vma
, mmun_start
, mmun_start
+ HPAGE_PMD_SIZE
);
2892 page_add_anon_rmap(new, vma
, mmun_start
, true);
2893 set_pmd_at(mm
, mmun_start
, pvmw
->pmd
, pmde
);
2894 if (vma
->vm_flags
& VM_LOCKED
)
2895 mlock_vma_page(new);
2896 update_mmu_cache_pmd(vma
, address
, pvmw
->pmd
);