1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2009 Red Hat, Inc.
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/sched.h>
10 #include <linux/sched/coredump.h>
11 #include <linux/sched/numa_balancing.h>
12 #include <linux/highmem.h>
13 #include <linux/hugetlb.h>
14 #include <linux/mmu_notifier.h>
15 #include <linux/rmap.h>
16 #include <linux/swap.h>
17 #include <linux/shrinker.h>
18 #include <linux/mm_inline.h>
19 #include <linux/swapops.h>
20 #include <linux/dax.h>
21 #include <linux/khugepaged.h>
22 #include <linux/freezer.h>
23 #include <linux/pfn_t.h>
24 #include <linux/mman.h>
25 #include <linux/memremap.h>
26 #include <linux/pagemap.h>
27 #include <linux/debugfs.h>
28 #include <linux/migrate.h>
29 #include <linux/hashtable.h>
30 #include <linux/userfaultfd_k.h>
31 #include <linux/page_idle.h>
32 #include <linux/shmem_fs.h>
33 #include <linux/oom.h>
34 #include <linux/numa.h>
37 #include <asm/pgalloc.h>
41 * By default, transparent hugepage support is disabled in order to avoid
42 * risking an increased memory footprint for applications that are not
43 * guaranteed to benefit from it. When transparent hugepage support is
44 * enabled, it is for all mappings, and khugepaged scans all mappings.
45 * Defrag is invoked by khugepaged hugepage allocations and by page faults
46 * for all hugepage allocations.
48 unsigned long transparent_hugepage_flags __read_mostly
=
49 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
50 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
52 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
53 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
55 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
)|
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
)|
57 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
59 static struct shrinker deferred_split_shrinker
;
61 static atomic_t huge_zero_refcount
;
62 struct page
*huge_zero_page __read_mostly
;
64 bool transparent_hugepage_enabled(struct vm_area_struct
*vma
)
66 if (vma_is_anonymous(vma
))
67 return __transparent_hugepage_enabled(vma
);
68 if (vma_is_shmem(vma
) && shmem_huge_enabled(vma
))
69 return __transparent_hugepage_enabled(vma
);
74 static struct page
*get_huge_zero_page(void)
76 struct page
*zero_page
;
78 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
79 return READ_ONCE(huge_zero_page
);
81 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
84 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
87 count_vm_event(THP_ZERO_PAGE_ALLOC
);
89 if (cmpxchg(&huge_zero_page
, NULL
, zero_page
)) {
91 __free_pages(zero_page
, compound_order(zero_page
));
95 /* We take additional reference here. It will be put back by shrinker */
96 atomic_set(&huge_zero_refcount
, 2);
98 return READ_ONCE(huge_zero_page
);
101 static void put_huge_zero_page(void)
104 * Counter should never go to zero here. Only shrinker can put
107 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
110 struct page
*mm_get_huge_zero_page(struct mm_struct
*mm
)
112 if (test_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
113 return READ_ONCE(huge_zero_page
);
115 if (!get_huge_zero_page())
118 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
119 put_huge_zero_page();
121 return READ_ONCE(huge_zero_page
);
124 void mm_put_huge_zero_page(struct mm_struct
*mm
)
126 if (test_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
127 put_huge_zero_page();
130 static unsigned long shrink_huge_zero_page_count(struct shrinker
*shrink
,
131 struct shrink_control
*sc
)
133 /* we can free zero page only if last reference remains */
134 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
137 static unsigned long shrink_huge_zero_page_scan(struct shrinker
*shrink
,
138 struct shrink_control
*sc
)
140 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
141 struct page
*zero_page
= xchg(&huge_zero_page
, NULL
);
142 BUG_ON(zero_page
== NULL
);
143 __free_pages(zero_page
, compound_order(zero_page
));
150 static struct shrinker huge_zero_page_shrinker
= {
151 .count_objects
= shrink_huge_zero_page_count
,
152 .scan_objects
= shrink_huge_zero_page_scan
,
153 .seeks
= DEFAULT_SEEKS
,
157 static ssize_t
enabled_show(struct kobject
*kobj
,
158 struct kobj_attribute
*attr
, char *buf
)
160 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
))
161 return sprintf(buf
, "[always] madvise never\n");
162 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
163 return sprintf(buf
, "always [madvise] never\n");
165 return sprintf(buf
, "always madvise [never]\n");
168 static ssize_t
enabled_store(struct kobject
*kobj
,
169 struct kobj_attribute
*attr
,
170 const char *buf
, size_t count
)
174 if (!memcmp("always", buf
,
175 min(sizeof("always")-1, count
))) {
176 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
177 set_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
178 } else if (!memcmp("madvise", buf
,
179 min(sizeof("madvise")-1, count
))) {
180 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
181 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
182 } else if (!memcmp("never", buf
,
183 min(sizeof("never")-1, count
))) {
184 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
185 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
190 int err
= start_stop_khugepaged();
196 static struct kobj_attribute enabled_attr
=
197 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
199 ssize_t
single_hugepage_flag_show(struct kobject
*kobj
,
200 struct kobj_attribute
*attr
, char *buf
,
201 enum transparent_hugepage_flag flag
)
203 return sprintf(buf
, "%d\n",
204 !!test_bit(flag
, &transparent_hugepage_flags
));
207 ssize_t
single_hugepage_flag_store(struct kobject
*kobj
,
208 struct kobj_attribute
*attr
,
209 const char *buf
, size_t count
,
210 enum transparent_hugepage_flag flag
)
215 ret
= kstrtoul(buf
, 10, &value
);
222 set_bit(flag
, &transparent_hugepage_flags
);
224 clear_bit(flag
, &transparent_hugepage_flags
);
229 static ssize_t
defrag_show(struct kobject
*kobj
,
230 struct kobj_attribute
*attr
, char *buf
)
232 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
233 return sprintf(buf
, "[always] defer defer+madvise madvise never\n");
234 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
235 return sprintf(buf
, "always [defer] defer+madvise madvise never\n");
236 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
))
237 return sprintf(buf
, "always defer [defer+madvise] madvise never\n");
238 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
239 return sprintf(buf
, "always defer defer+madvise [madvise] never\n");
240 return sprintf(buf
, "always defer defer+madvise madvise [never]\n");
243 static ssize_t
defrag_store(struct kobject
*kobj
,
244 struct kobj_attribute
*attr
,
245 const char *buf
, size_t count
)
247 if (!memcmp("always", buf
,
248 min(sizeof("always")-1, count
))) {
249 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
250 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
251 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
252 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
253 } else if (!memcmp("defer+madvise", buf
,
254 min(sizeof("defer+madvise")-1, count
))) {
255 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
256 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
258 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
259 } else if (!memcmp("defer", buf
,
260 min(sizeof("defer")-1, count
))) {
261 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
262 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
264 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
265 } else if (!memcmp("madvise", buf
,
266 min(sizeof("madvise")-1, count
))) {
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
268 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
269 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
270 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
271 } else if (!memcmp("never", buf
,
272 min(sizeof("never")-1, count
))) {
273 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
274 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
275 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
276 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
282 static struct kobj_attribute defrag_attr
=
283 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
285 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
286 struct kobj_attribute
*attr
, char *buf
)
288 return single_hugepage_flag_show(kobj
, attr
, buf
,
289 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
291 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
292 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
294 return single_hugepage_flag_store(kobj
, attr
, buf
, count
,
295 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
297 static struct kobj_attribute use_zero_page_attr
=
298 __ATTR(use_zero_page
, 0644, use_zero_page_show
, use_zero_page_store
);
300 static ssize_t
hpage_pmd_size_show(struct kobject
*kobj
,
301 struct kobj_attribute
*attr
, char *buf
)
303 return sprintf(buf
, "%lu\n", HPAGE_PMD_SIZE
);
305 static struct kobj_attribute hpage_pmd_size_attr
=
306 __ATTR_RO(hpage_pmd_size
);
308 #ifdef CONFIG_DEBUG_VM
309 static ssize_t
debug_cow_show(struct kobject
*kobj
,
310 struct kobj_attribute
*attr
, char *buf
)
312 return single_hugepage_flag_show(kobj
, attr
, buf
,
313 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
315 static ssize_t
debug_cow_store(struct kobject
*kobj
,
316 struct kobj_attribute
*attr
,
317 const char *buf
, size_t count
)
319 return single_hugepage_flag_store(kobj
, attr
, buf
, count
,
320 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
322 static struct kobj_attribute debug_cow_attr
=
323 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
324 #endif /* CONFIG_DEBUG_VM */
326 static struct attribute
*hugepage_attr
[] = {
329 &use_zero_page_attr
.attr
,
330 &hpage_pmd_size_attr
.attr
,
331 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
332 &shmem_enabled_attr
.attr
,
334 #ifdef CONFIG_DEBUG_VM
335 &debug_cow_attr
.attr
,
340 static const struct attribute_group hugepage_attr_group
= {
341 .attrs
= hugepage_attr
,
344 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
348 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
349 if (unlikely(!*hugepage_kobj
)) {
350 pr_err("failed to create transparent hugepage kobject\n");
354 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
356 pr_err("failed to register transparent hugepage group\n");
360 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
362 pr_err("failed to register transparent hugepage group\n");
363 goto remove_hp_group
;
369 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
371 kobject_put(*hugepage_kobj
);
375 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
377 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
378 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
379 kobject_put(hugepage_kobj
);
382 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
387 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
390 #endif /* CONFIG_SYSFS */
392 static int __init
hugepage_init(void)
395 struct kobject
*hugepage_kobj
;
397 if (!has_transparent_hugepage()) {
398 transparent_hugepage_flags
= 0;
403 * hugepages can't be allocated by the buddy allocator
405 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
>= MAX_ORDER
);
407 * we use page->mapping and page->index in second tail page
408 * as list_head: assuming THP order >= 2
410 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
< 2);
412 err
= hugepage_init_sysfs(&hugepage_kobj
);
416 err
= khugepaged_init();
420 err
= register_shrinker(&huge_zero_page_shrinker
);
422 goto err_hzp_shrinker
;
423 err
= register_shrinker(&deferred_split_shrinker
);
425 goto err_split_shrinker
;
428 * By default disable transparent hugepages on smaller systems,
429 * where the extra memory used could hurt more than TLB overhead
430 * is likely to save. The admin can still enable it through /sys.
432 if (totalram_pages() < (512 << (20 - PAGE_SHIFT
))) {
433 transparent_hugepage_flags
= 0;
437 err
= start_stop_khugepaged();
443 unregister_shrinker(&deferred_split_shrinker
);
445 unregister_shrinker(&huge_zero_page_shrinker
);
447 khugepaged_destroy();
449 hugepage_exit_sysfs(hugepage_kobj
);
453 subsys_initcall(hugepage_init
);
455 static int __init
setup_transparent_hugepage(char *str
)
460 if (!strcmp(str
, "always")) {
461 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
462 &transparent_hugepage_flags
);
463 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
464 &transparent_hugepage_flags
);
466 } else if (!strcmp(str
, "madvise")) {
467 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
468 &transparent_hugepage_flags
);
469 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
470 &transparent_hugepage_flags
);
472 } else if (!strcmp(str
, "never")) {
473 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
474 &transparent_hugepage_flags
);
475 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
476 &transparent_hugepage_flags
);
481 pr_warn("transparent_hugepage= cannot parse, ignored\n");
484 __setup("transparent_hugepage=", setup_transparent_hugepage
);
486 pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
488 if (likely(vma
->vm_flags
& VM_WRITE
))
489 pmd
= pmd_mkwrite(pmd
);
493 static inline struct list_head
*page_deferred_list(struct page
*page
)
495 /* ->lru in the tail pages is occupied by compound_head. */
496 return &page
[2].deferred_list
;
499 void prep_transhuge_page(struct page
*page
)
502 * we use page->mapping and page->indexlru in second tail page
503 * as list_head: assuming THP order >= 2
506 INIT_LIST_HEAD(page_deferred_list(page
));
507 set_compound_page_dtor(page
, TRANSHUGE_PAGE_DTOR
);
510 static unsigned long __thp_get_unmapped_area(struct file
*filp
, unsigned long len
,
511 loff_t off
, unsigned long flags
, unsigned long size
)
514 loff_t off_end
= off
+ len
;
515 loff_t off_align
= round_up(off
, size
);
516 unsigned long len_pad
;
518 if (off_end
<= off_align
|| (off_end
- off_align
) < size
)
521 len_pad
= len
+ size
;
522 if (len_pad
< len
|| (off
+ len_pad
) < off
)
525 addr
= current
->mm
->get_unmapped_area(filp
, 0, len_pad
,
526 off
>> PAGE_SHIFT
, flags
);
527 if (IS_ERR_VALUE(addr
))
530 addr
+= (off
- addr
) & (size
- 1);
534 unsigned long thp_get_unmapped_area(struct file
*filp
, unsigned long addr
,
535 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
537 loff_t off
= (loff_t
)pgoff
<< PAGE_SHIFT
;
541 if (!IS_DAX(filp
->f_mapping
->host
) || !IS_ENABLED(CONFIG_FS_DAX_PMD
))
544 addr
= __thp_get_unmapped_area(filp
, len
, off
, flags
, PMD_SIZE
);
549 return current
->mm
->get_unmapped_area(filp
, addr
, len
, pgoff
, flags
);
551 EXPORT_SYMBOL_GPL(thp_get_unmapped_area
);
553 static vm_fault_t
__do_huge_pmd_anonymous_page(struct vm_fault
*vmf
,
554 struct page
*page
, gfp_t gfp
)
556 struct vm_area_struct
*vma
= vmf
->vma
;
557 struct mem_cgroup
*memcg
;
559 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
562 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
564 if (mem_cgroup_try_charge_delay(page
, vma
->vm_mm
, gfp
, &memcg
, true)) {
566 count_vm_event(THP_FAULT_FALLBACK
);
567 return VM_FAULT_FALLBACK
;
570 pgtable
= pte_alloc_one(vma
->vm_mm
);
571 if (unlikely(!pgtable
)) {
576 clear_huge_page(page
, vmf
->address
, HPAGE_PMD_NR
);
578 * The memory barrier inside __SetPageUptodate makes sure that
579 * clear_huge_page writes become visible before the set_pmd_at()
582 __SetPageUptodate(page
);
584 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
585 if (unlikely(!pmd_none(*vmf
->pmd
))) {
590 ret
= check_stable_address_space(vma
->vm_mm
);
594 /* Deliver the page fault to userland */
595 if (userfaultfd_missing(vma
)) {
598 spin_unlock(vmf
->ptl
);
599 mem_cgroup_cancel_charge(page
, memcg
, true);
601 pte_free(vma
->vm_mm
, pgtable
);
602 ret2
= handle_userfault(vmf
, VM_UFFD_MISSING
);
603 VM_BUG_ON(ret2
& VM_FAULT_FALLBACK
);
607 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
608 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
609 page_add_new_anon_rmap(page
, vma
, haddr
, true);
610 mem_cgroup_commit_charge(page
, memcg
, false, true);
611 lru_cache_add_active_or_unevictable(page
, vma
);
612 pgtable_trans_huge_deposit(vma
->vm_mm
, vmf
->pmd
, pgtable
);
613 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
614 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
615 mm_inc_nr_ptes(vma
->vm_mm
);
616 spin_unlock(vmf
->ptl
);
617 count_vm_event(THP_FAULT_ALLOC
);
618 count_memcg_events(memcg
, THP_FAULT_ALLOC
, 1);
623 spin_unlock(vmf
->ptl
);
626 pte_free(vma
->vm_mm
, pgtable
);
627 mem_cgroup_cancel_charge(page
, memcg
, true);
634 * always: directly stall for all thp allocations
635 * defer: wake kswapd and fail if not immediately available
636 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
637 * fail if not immediately available
638 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
640 * never: never stall for any thp allocation
642 static inline gfp_t
alloc_hugepage_direct_gfpmask(struct vm_area_struct
*vma
)
644 const bool vma_madvised
= !!(vma
->vm_flags
& VM_HUGEPAGE
);
646 /* Always do synchronous compaction */
647 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
648 return GFP_TRANSHUGE
| (vma_madvised
? 0 : __GFP_NORETRY
);
650 /* Kick kcompactd and fail quickly */
651 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
652 return GFP_TRANSHUGE_LIGHT
| __GFP_KSWAPD_RECLAIM
;
654 /* Synchronous compaction if madvised, otherwise kick kcompactd */
655 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
))
656 return GFP_TRANSHUGE_LIGHT
|
657 (vma_madvised
? __GFP_DIRECT_RECLAIM
:
658 __GFP_KSWAPD_RECLAIM
);
660 /* Only do synchronous compaction if madvised */
661 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
662 return GFP_TRANSHUGE_LIGHT
|
663 (vma_madvised
? __GFP_DIRECT_RECLAIM
: 0);
665 return GFP_TRANSHUGE_LIGHT
;
668 /* Caller must hold page table lock. */
669 static bool set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
670 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
671 struct page
*zero_page
)
676 entry
= mk_pmd(zero_page
, vma
->vm_page_prot
);
677 entry
= pmd_mkhuge(entry
);
679 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
680 set_pmd_at(mm
, haddr
, pmd
, entry
);
685 vm_fault_t
do_huge_pmd_anonymous_page(struct vm_fault
*vmf
)
687 struct vm_area_struct
*vma
= vmf
->vma
;
690 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
692 if (haddr
< vma
->vm_start
|| haddr
+ HPAGE_PMD_SIZE
> vma
->vm_end
)
693 return VM_FAULT_FALLBACK
;
694 if (unlikely(anon_vma_prepare(vma
)))
696 if (unlikely(khugepaged_enter(vma
, vma
->vm_flags
)))
698 if (!(vmf
->flags
& FAULT_FLAG_WRITE
) &&
699 !mm_forbids_zeropage(vma
->vm_mm
) &&
700 transparent_hugepage_use_zero_page()) {
702 struct page
*zero_page
;
705 pgtable
= pte_alloc_one(vma
->vm_mm
);
706 if (unlikely(!pgtable
))
708 zero_page
= mm_get_huge_zero_page(vma
->vm_mm
);
709 if (unlikely(!zero_page
)) {
710 pte_free(vma
->vm_mm
, pgtable
);
711 count_vm_event(THP_FAULT_FALLBACK
);
712 return VM_FAULT_FALLBACK
;
714 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
717 if (pmd_none(*vmf
->pmd
)) {
718 ret
= check_stable_address_space(vma
->vm_mm
);
720 spin_unlock(vmf
->ptl
);
721 } else if (userfaultfd_missing(vma
)) {
722 spin_unlock(vmf
->ptl
);
723 ret
= handle_userfault(vmf
, VM_UFFD_MISSING
);
724 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
726 set_huge_zero_page(pgtable
, vma
->vm_mm
, vma
,
727 haddr
, vmf
->pmd
, zero_page
);
728 spin_unlock(vmf
->ptl
);
732 spin_unlock(vmf
->ptl
);
734 pte_free(vma
->vm_mm
, pgtable
);
737 gfp
= alloc_hugepage_direct_gfpmask(vma
);
738 page
= alloc_hugepage_vma(gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
739 if (unlikely(!page
)) {
740 count_vm_event(THP_FAULT_FALLBACK
);
741 return VM_FAULT_FALLBACK
;
743 prep_transhuge_page(page
);
744 return __do_huge_pmd_anonymous_page(vmf
, page
, gfp
);
747 static void insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
748 pmd_t
*pmd
, pfn_t pfn
, pgprot_t prot
, bool write
,
751 struct mm_struct
*mm
= vma
->vm_mm
;
755 ptl
= pmd_lock(mm
, pmd
);
756 if (!pmd_none(*pmd
)) {
758 if (pmd_pfn(*pmd
) != pfn_t_to_pfn(pfn
)) {
759 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd
));
762 entry
= pmd_mkyoung(*pmd
);
763 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
764 if (pmdp_set_access_flags(vma
, addr
, pmd
, entry
, 1))
765 update_mmu_cache_pmd(vma
, addr
, pmd
);
771 entry
= pmd_mkhuge(pfn_t_pmd(pfn
, prot
));
772 if (pfn_t_devmap(pfn
))
773 entry
= pmd_mkdevmap(entry
);
775 entry
= pmd_mkyoung(pmd_mkdirty(entry
));
776 entry
= maybe_pmd_mkwrite(entry
, vma
);
780 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
785 set_pmd_at(mm
, addr
, pmd
, entry
);
786 update_mmu_cache_pmd(vma
, addr
, pmd
);
791 pte_free(mm
, pgtable
);
794 vm_fault_t
vmf_insert_pfn_pmd(struct vm_fault
*vmf
, pfn_t pfn
, bool write
)
796 unsigned long addr
= vmf
->address
& PMD_MASK
;
797 struct vm_area_struct
*vma
= vmf
->vma
;
798 pgprot_t pgprot
= vma
->vm_page_prot
;
799 pgtable_t pgtable
= NULL
;
802 * If we had pmd_special, we could avoid all these restrictions,
803 * but we need to be consistent with PTEs and architectures that
804 * can't support a 'special' bit.
806 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) &&
808 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
809 (VM_PFNMAP
|VM_MIXEDMAP
));
810 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
812 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
813 return VM_FAULT_SIGBUS
;
815 if (arch_needs_pgtable_deposit()) {
816 pgtable
= pte_alloc_one(vma
->vm_mm
);
821 track_pfn_insert(vma
, &pgprot
, pfn
);
823 insert_pfn_pmd(vma
, addr
, vmf
->pmd
, pfn
, pgprot
, write
, pgtable
);
824 return VM_FAULT_NOPAGE
;
826 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd
);
828 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
829 static pud_t
maybe_pud_mkwrite(pud_t pud
, struct vm_area_struct
*vma
)
831 if (likely(vma
->vm_flags
& VM_WRITE
))
832 pud
= pud_mkwrite(pud
);
836 static void insert_pfn_pud(struct vm_area_struct
*vma
, unsigned long addr
,
837 pud_t
*pud
, pfn_t pfn
, pgprot_t prot
, bool write
)
839 struct mm_struct
*mm
= vma
->vm_mm
;
843 ptl
= pud_lock(mm
, pud
);
844 if (!pud_none(*pud
)) {
846 if (pud_pfn(*pud
) != pfn_t_to_pfn(pfn
)) {
847 WARN_ON_ONCE(!is_huge_zero_pud(*pud
));
850 entry
= pud_mkyoung(*pud
);
851 entry
= maybe_pud_mkwrite(pud_mkdirty(entry
), vma
);
852 if (pudp_set_access_flags(vma
, addr
, pud
, entry
, 1))
853 update_mmu_cache_pud(vma
, addr
, pud
);
858 entry
= pud_mkhuge(pfn_t_pud(pfn
, prot
));
859 if (pfn_t_devmap(pfn
))
860 entry
= pud_mkdevmap(entry
);
862 entry
= pud_mkyoung(pud_mkdirty(entry
));
863 entry
= maybe_pud_mkwrite(entry
, vma
);
865 set_pud_at(mm
, addr
, pud
, entry
);
866 update_mmu_cache_pud(vma
, addr
, pud
);
872 vm_fault_t
vmf_insert_pfn_pud(struct vm_fault
*vmf
, pfn_t pfn
, bool write
)
874 unsigned long addr
= vmf
->address
& PUD_MASK
;
875 struct vm_area_struct
*vma
= vmf
->vma
;
876 pgprot_t pgprot
= vma
->vm_page_prot
;
879 * If we had pud_special, we could avoid all these restrictions,
880 * but we need to be consistent with PTEs and architectures that
881 * can't support a 'special' bit.
883 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) &&
885 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
886 (VM_PFNMAP
|VM_MIXEDMAP
));
887 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
889 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
890 return VM_FAULT_SIGBUS
;
892 track_pfn_insert(vma
, &pgprot
, pfn
);
894 insert_pfn_pud(vma
, addr
, vmf
->pud
, pfn
, pgprot
, write
);
895 return VM_FAULT_NOPAGE
;
897 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud
);
898 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
900 static void touch_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
901 pmd_t
*pmd
, int flags
)
905 _pmd
= pmd_mkyoung(*pmd
);
906 if (flags
& FOLL_WRITE
)
907 _pmd
= pmd_mkdirty(_pmd
);
908 if (pmdp_set_access_flags(vma
, addr
& HPAGE_PMD_MASK
,
909 pmd
, _pmd
, flags
& FOLL_WRITE
))
910 update_mmu_cache_pmd(vma
, addr
, pmd
);
913 struct page
*follow_devmap_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
914 pmd_t
*pmd
, int flags
, struct dev_pagemap
**pgmap
)
916 unsigned long pfn
= pmd_pfn(*pmd
);
917 struct mm_struct
*mm
= vma
->vm_mm
;
920 assert_spin_locked(pmd_lockptr(mm
, pmd
));
923 * When we COW a devmap PMD entry, we split it into PTEs, so we should
924 * not be in this function with `flags & FOLL_COW` set.
926 WARN_ONCE(flags
& FOLL_COW
, "mm: In follow_devmap_pmd with FOLL_COW set");
928 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
931 if (pmd_present(*pmd
) && pmd_devmap(*pmd
))
936 if (flags
& FOLL_TOUCH
)
937 touch_pmd(vma
, addr
, pmd
, flags
);
940 * device mapped pages can only be returned if the
941 * caller will manage the page reference count.
943 if (!(flags
& FOLL_GET
))
944 return ERR_PTR(-EEXIST
);
946 pfn
+= (addr
& ~PMD_MASK
) >> PAGE_SHIFT
;
947 *pgmap
= get_dev_pagemap(pfn
, *pgmap
);
949 return ERR_PTR(-EFAULT
);
950 page
= pfn_to_page(pfn
);
956 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
957 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
958 struct vm_area_struct
*vma
)
960 spinlock_t
*dst_ptl
, *src_ptl
;
961 struct page
*src_page
;
963 pgtable_t pgtable
= NULL
;
966 /* Skip if can be re-fill on fault */
967 if (!vma_is_anonymous(vma
))
970 pgtable
= pte_alloc_one(dst_mm
);
971 if (unlikely(!pgtable
))
974 dst_ptl
= pmd_lock(dst_mm
, dst_pmd
);
975 src_ptl
= pmd_lockptr(src_mm
, src_pmd
);
976 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
981 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
982 if (unlikely(is_swap_pmd(pmd
))) {
983 swp_entry_t entry
= pmd_to_swp_entry(pmd
);
985 VM_BUG_ON(!is_pmd_migration_entry(pmd
));
986 if (is_write_migration_entry(entry
)) {
987 make_migration_entry_read(&entry
);
988 pmd
= swp_entry_to_pmd(entry
);
989 if (pmd_swp_soft_dirty(*src_pmd
))
990 pmd
= pmd_swp_mksoft_dirty(pmd
);
991 set_pmd_at(src_mm
, addr
, src_pmd
, pmd
);
993 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
994 mm_inc_nr_ptes(dst_mm
);
995 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
996 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
1002 if (unlikely(!pmd_trans_huge(pmd
))) {
1003 pte_free(dst_mm
, pgtable
);
1007 * When page table lock is held, the huge zero pmd should not be
1008 * under splitting since we don't split the page itself, only pmd to
1011 if (is_huge_zero_pmd(pmd
)) {
1012 struct page
*zero_page
;
1014 * get_huge_zero_page() will never allocate a new page here,
1015 * since we already have a zero page to copy. It just takes a
1018 zero_page
= mm_get_huge_zero_page(dst_mm
);
1019 set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
1025 src_page
= pmd_page(pmd
);
1026 VM_BUG_ON_PAGE(!PageHead(src_page
), src_page
);
1028 page_dup_rmap(src_page
, true);
1029 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1030 mm_inc_nr_ptes(dst_mm
);
1031 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
1033 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
1034 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
1035 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
1039 spin_unlock(src_ptl
);
1040 spin_unlock(dst_ptl
);
1045 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1046 static void touch_pud(struct vm_area_struct
*vma
, unsigned long addr
,
1047 pud_t
*pud
, int flags
)
1051 _pud
= pud_mkyoung(*pud
);
1052 if (flags
& FOLL_WRITE
)
1053 _pud
= pud_mkdirty(_pud
);
1054 if (pudp_set_access_flags(vma
, addr
& HPAGE_PUD_MASK
,
1055 pud
, _pud
, flags
& FOLL_WRITE
))
1056 update_mmu_cache_pud(vma
, addr
, pud
);
1059 struct page
*follow_devmap_pud(struct vm_area_struct
*vma
, unsigned long addr
,
1060 pud_t
*pud
, int flags
, struct dev_pagemap
**pgmap
)
1062 unsigned long pfn
= pud_pfn(*pud
);
1063 struct mm_struct
*mm
= vma
->vm_mm
;
1066 assert_spin_locked(pud_lockptr(mm
, pud
));
1068 if (flags
& FOLL_WRITE
&& !pud_write(*pud
))
1071 if (pud_present(*pud
) && pud_devmap(*pud
))
1076 if (flags
& FOLL_TOUCH
)
1077 touch_pud(vma
, addr
, pud
, flags
);
1080 * device mapped pages can only be returned if the
1081 * caller will manage the page reference count.
1083 if (!(flags
& FOLL_GET
))
1084 return ERR_PTR(-EEXIST
);
1086 pfn
+= (addr
& ~PUD_MASK
) >> PAGE_SHIFT
;
1087 *pgmap
= get_dev_pagemap(pfn
, *pgmap
);
1089 return ERR_PTR(-EFAULT
);
1090 page
= pfn_to_page(pfn
);
1096 int copy_huge_pud(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1097 pud_t
*dst_pud
, pud_t
*src_pud
, unsigned long addr
,
1098 struct vm_area_struct
*vma
)
1100 spinlock_t
*dst_ptl
, *src_ptl
;
1104 dst_ptl
= pud_lock(dst_mm
, dst_pud
);
1105 src_ptl
= pud_lockptr(src_mm
, src_pud
);
1106 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
1110 if (unlikely(!pud_trans_huge(pud
) && !pud_devmap(pud
)))
1114 * When page table lock is held, the huge zero pud should not be
1115 * under splitting since we don't split the page itself, only pud to
1118 if (is_huge_zero_pud(pud
)) {
1119 /* No huge zero pud yet */
1122 pudp_set_wrprotect(src_mm
, addr
, src_pud
);
1123 pud
= pud_mkold(pud_wrprotect(pud
));
1124 set_pud_at(dst_mm
, addr
, dst_pud
, pud
);
1128 spin_unlock(src_ptl
);
1129 spin_unlock(dst_ptl
);
1133 void huge_pud_set_accessed(struct vm_fault
*vmf
, pud_t orig_pud
)
1136 unsigned long haddr
;
1137 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1139 vmf
->ptl
= pud_lock(vmf
->vma
->vm_mm
, vmf
->pud
);
1140 if (unlikely(!pud_same(*vmf
->pud
, orig_pud
)))
1143 entry
= pud_mkyoung(orig_pud
);
1145 entry
= pud_mkdirty(entry
);
1146 haddr
= vmf
->address
& HPAGE_PUD_MASK
;
1147 if (pudp_set_access_flags(vmf
->vma
, haddr
, vmf
->pud
, entry
, write
))
1148 update_mmu_cache_pud(vmf
->vma
, vmf
->address
, vmf
->pud
);
1151 spin_unlock(vmf
->ptl
);
1153 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1155 void huge_pmd_set_accessed(struct vm_fault
*vmf
, pmd_t orig_pmd
)
1158 unsigned long haddr
;
1159 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1161 vmf
->ptl
= pmd_lock(vmf
->vma
->vm_mm
, vmf
->pmd
);
1162 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1165 entry
= pmd_mkyoung(orig_pmd
);
1167 entry
= pmd_mkdirty(entry
);
1168 haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1169 if (pmdp_set_access_flags(vmf
->vma
, haddr
, vmf
->pmd
, entry
, write
))
1170 update_mmu_cache_pmd(vmf
->vma
, vmf
->address
, vmf
->pmd
);
1173 spin_unlock(vmf
->ptl
);
1176 static vm_fault_t
do_huge_pmd_wp_page_fallback(struct vm_fault
*vmf
,
1177 pmd_t orig_pmd
, struct page
*page
)
1179 struct vm_area_struct
*vma
= vmf
->vma
;
1180 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1181 struct mem_cgroup
*memcg
;
1186 struct page
**pages
;
1187 struct mmu_notifier_range range
;
1189 pages
= kmalloc_array(HPAGE_PMD_NR
, sizeof(struct page
*),
1191 if (unlikely(!pages
)) {
1192 ret
|= VM_FAULT_OOM
;
1196 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1197 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
, vma
,
1198 vmf
->address
, page_to_nid(page
));
1199 if (unlikely(!pages
[i
] ||
1200 mem_cgroup_try_charge_delay(pages
[i
], vma
->vm_mm
,
1201 GFP_KERNEL
, &memcg
, false))) {
1205 memcg
= (void *)page_private(pages
[i
]);
1206 set_page_private(pages
[i
], 0);
1207 mem_cgroup_cancel_charge(pages
[i
], memcg
,
1212 ret
|= VM_FAULT_OOM
;
1215 set_page_private(pages
[i
], (unsigned long)memcg
);
1218 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1219 copy_user_highpage(pages
[i
], page
+ i
,
1220 haddr
+ PAGE_SIZE
* i
, vma
);
1221 __SetPageUptodate(pages
[i
]);
1225 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
1226 haddr
, haddr
+ HPAGE_PMD_SIZE
);
1227 mmu_notifier_invalidate_range_start(&range
);
1229 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1230 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1231 goto out_free_pages
;
1232 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1235 * Leave pmd empty until pte is filled note we must notify here as
1236 * concurrent CPU thread might write to new page before the call to
1237 * mmu_notifier_invalidate_range_end() happens which can lead to a
1238 * device seeing memory write in different order than CPU.
1240 * See Documentation/vm/mmu_notifier.rst
1242 pmdp_huge_clear_flush_notify(vma
, haddr
, vmf
->pmd
);
1244 pgtable
= pgtable_trans_huge_withdraw(vma
->vm_mm
, vmf
->pmd
);
1245 pmd_populate(vma
->vm_mm
, &_pmd
, pgtable
);
1247 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1249 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1250 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1251 memcg
= (void *)page_private(pages
[i
]);
1252 set_page_private(pages
[i
], 0);
1253 page_add_new_anon_rmap(pages
[i
], vmf
->vma
, haddr
, false);
1254 mem_cgroup_commit_charge(pages
[i
], memcg
, false, false);
1255 lru_cache_add_active_or_unevictable(pages
[i
], vma
);
1256 vmf
->pte
= pte_offset_map(&_pmd
, haddr
);
1257 VM_BUG_ON(!pte_none(*vmf
->pte
));
1258 set_pte_at(vma
->vm_mm
, haddr
, vmf
->pte
, entry
);
1259 pte_unmap(vmf
->pte
);
1263 smp_wmb(); /* make pte visible before pmd */
1264 pmd_populate(vma
->vm_mm
, vmf
->pmd
, pgtable
);
1265 page_remove_rmap(page
, true);
1266 spin_unlock(vmf
->ptl
);
1269 * No need to double call mmu_notifier->invalidate_range() callback as
1270 * the above pmdp_huge_clear_flush_notify() did already call it.
1272 mmu_notifier_invalidate_range_only_end(&range
);
1274 ret
|= VM_FAULT_WRITE
;
1281 spin_unlock(vmf
->ptl
);
1282 mmu_notifier_invalidate_range_end(&range
);
1283 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1284 memcg
= (void *)page_private(pages
[i
]);
1285 set_page_private(pages
[i
], 0);
1286 mem_cgroup_cancel_charge(pages
[i
], memcg
, false);
1293 vm_fault_t
do_huge_pmd_wp_page(struct vm_fault
*vmf
, pmd_t orig_pmd
)
1295 struct vm_area_struct
*vma
= vmf
->vma
;
1296 struct page
*page
= NULL
, *new_page
;
1297 struct mem_cgroup
*memcg
;
1298 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1299 struct mmu_notifier_range range
;
1300 gfp_t huge_gfp
; /* for allocation and charge */
1303 vmf
->ptl
= pmd_lockptr(vma
->vm_mm
, vmf
->pmd
);
1304 VM_BUG_ON_VMA(!vma
->anon_vma
, vma
);
1305 if (is_huge_zero_pmd(orig_pmd
))
1307 spin_lock(vmf
->ptl
);
1308 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1311 page
= pmd_page(orig_pmd
);
1312 VM_BUG_ON_PAGE(!PageCompound(page
) || !PageHead(page
), page
);
1314 * We can only reuse the page if nobody else maps the huge page or it's
1317 if (!trylock_page(page
)) {
1319 spin_unlock(vmf
->ptl
);
1321 spin_lock(vmf
->ptl
);
1322 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
))) {
1329 if (reuse_swap_page(page
, NULL
)) {
1331 entry
= pmd_mkyoung(orig_pmd
);
1332 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1333 if (pmdp_set_access_flags(vma
, haddr
, vmf
->pmd
, entry
, 1))
1334 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1335 ret
|= VM_FAULT_WRITE
;
1341 spin_unlock(vmf
->ptl
);
1343 if (__transparent_hugepage_enabled(vma
) &&
1344 !transparent_hugepage_debug_cow()) {
1345 huge_gfp
= alloc_hugepage_direct_gfpmask(vma
);
1346 new_page
= alloc_hugepage_vma(huge_gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
1350 if (likely(new_page
)) {
1351 prep_transhuge_page(new_page
);
1354 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1355 ret
|= VM_FAULT_FALLBACK
;
1357 ret
= do_huge_pmd_wp_page_fallback(vmf
, orig_pmd
, page
);
1358 if (ret
& VM_FAULT_OOM
) {
1359 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1360 ret
|= VM_FAULT_FALLBACK
;
1364 count_vm_event(THP_FAULT_FALLBACK
);
1368 if (unlikely(mem_cgroup_try_charge_delay(new_page
, vma
->vm_mm
,
1369 huge_gfp
, &memcg
, true))) {
1371 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1374 ret
|= VM_FAULT_FALLBACK
;
1375 count_vm_event(THP_FAULT_FALLBACK
);
1379 count_vm_event(THP_FAULT_ALLOC
);
1380 count_memcg_events(memcg
, THP_FAULT_ALLOC
, 1);
1383 clear_huge_page(new_page
, vmf
->address
, HPAGE_PMD_NR
);
1385 copy_user_huge_page(new_page
, page
, vmf
->address
,
1387 __SetPageUptodate(new_page
);
1389 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
1390 haddr
, haddr
+ HPAGE_PMD_SIZE
);
1391 mmu_notifier_invalidate_range_start(&range
);
1393 spin_lock(vmf
->ptl
);
1396 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
))) {
1397 spin_unlock(vmf
->ptl
);
1398 mem_cgroup_cancel_charge(new_page
, memcg
, true);
1403 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
1404 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1405 pmdp_huge_clear_flush_notify(vma
, haddr
, vmf
->pmd
);
1406 page_add_new_anon_rmap(new_page
, vma
, haddr
, true);
1407 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
1408 lru_cache_add_active_or_unevictable(new_page
, vma
);
1409 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
1410 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1412 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1414 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1415 page_remove_rmap(page
, true);
1418 ret
|= VM_FAULT_WRITE
;
1420 spin_unlock(vmf
->ptl
);
1423 * No need to double call mmu_notifier->invalidate_range() callback as
1424 * the above pmdp_huge_clear_flush_notify() did already call it.
1426 mmu_notifier_invalidate_range_only_end(&range
);
1430 spin_unlock(vmf
->ptl
);
1435 * FOLL_FORCE can write to even unwritable pmd's, but only
1436 * after we've gone through a COW cycle and they are dirty.
1438 static inline bool can_follow_write_pmd(pmd_t pmd
, unsigned int flags
)
1440 return pmd_write(pmd
) ||
1441 ((flags
& FOLL_FORCE
) && (flags
& FOLL_COW
) && pmd_dirty(pmd
));
1444 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1449 struct mm_struct
*mm
= vma
->vm_mm
;
1450 struct page
*page
= NULL
;
1452 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1454 if (flags
& FOLL_WRITE
&& !can_follow_write_pmd(*pmd
, flags
))
1457 /* Avoid dumping huge zero page */
1458 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1459 return ERR_PTR(-EFAULT
);
1461 /* Full NUMA hinting faults to serialise migration in fault paths */
1462 if ((flags
& FOLL_NUMA
) && pmd_protnone(*pmd
))
1465 page
= pmd_page(*pmd
);
1466 VM_BUG_ON_PAGE(!PageHead(page
) && !is_zone_device_page(page
), page
);
1467 if (flags
& FOLL_TOUCH
)
1468 touch_pmd(vma
, addr
, pmd
, flags
);
1469 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1471 * We don't mlock() pte-mapped THPs. This way we can avoid
1472 * leaking mlocked pages into non-VM_LOCKED VMAs.
1476 * In most cases the pmd is the only mapping of the page as we
1477 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1478 * writable private mappings in populate_vma_page_range().
1480 * The only scenario when we have the page shared here is if we
1481 * mlocking read-only mapping shared over fork(). We skip
1482 * mlocking such pages.
1486 * We can expect PageDoubleMap() to be stable under page lock:
1487 * for file pages we set it in page_add_file_rmap(), which
1488 * requires page to be locked.
1491 if (PageAnon(page
) && compound_mapcount(page
) != 1)
1493 if (PageDoubleMap(page
) || !page
->mapping
)
1495 if (!trylock_page(page
))
1498 if (page
->mapping
&& !PageDoubleMap(page
))
1499 mlock_vma_page(page
);
1503 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1504 VM_BUG_ON_PAGE(!PageCompound(page
) && !is_zone_device_page(page
), page
);
1505 if (flags
& FOLL_GET
)
1512 /* NUMA hinting page fault entry point for trans huge pmds */
1513 vm_fault_t
do_huge_pmd_numa_page(struct vm_fault
*vmf
, pmd_t pmd
)
1515 struct vm_area_struct
*vma
= vmf
->vma
;
1516 struct anon_vma
*anon_vma
= NULL
;
1518 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1519 int page_nid
= NUMA_NO_NODE
, this_nid
= numa_node_id();
1520 int target_nid
, last_cpupid
= -1;
1522 bool migrated
= false;
1526 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1527 if (unlikely(!pmd_same(pmd
, *vmf
->pmd
)))
1531 * If there are potential migrations, wait for completion and retry
1532 * without disrupting NUMA hinting information. Do not relock and
1533 * check_same as the page may no longer be mapped.
1535 if (unlikely(pmd_trans_migrating(*vmf
->pmd
))) {
1536 page
= pmd_page(*vmf
->pmd
);
1537 if (!get_page_unless_zero(page
))
1539 spin_unlock(vmf
->ptl
);
1540 put_and_wait_on_page_locked(page
);
1544 page
= pmd_page(pmd
);
1545 BUG_ON(is_huge_zero_page(page
));
1546 page_nid
= page_to_nid(page
);
1547 last_cpupid
= page_cpupid_last(page
);
1548 count_vm_numa_event(NUMA_HINT_FAULTS
);
1549 if (page_nid
== this_nid
) {
1550 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
1551 flags
|= TNF_FAULT_LOCAL
;
1554 /* See similar comment in do_numa_page for explanation */
1555 if (!pmd_savedwrite(pmd
))
1556 flags
|= TNF_NO_GROUP
;
1559 * Acquire the page lock to serialise THP migrations but avoid dropping
1560 * page_table_lock if at all possible
1562 page_locked
= trylock_page(page
);
1563 target_nid
= mpol_misplaced(page
, vma
, haddr
);
1564 if (target_nid
== NUMA_NO_NODE
) {
1565 /* If the page was locked, there are no parallel migrations */
1570 /* Migration could have started since the pmd_trans_migrating check */
1572 page_nid
= NUMA_NO_NODE
;
1573 if (!get_page_unless_zero(page
))
1575 spin_unlock(vmf
->ptl
);
1576 put_and_wait_on_page_locked(page
);
1581 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1582 * to serialises splits
1585 spin_unlock(vmf
->ptl
);
1586 anon_vma
= page_lock_anon_vma_read(page
);
1588 /* Confirm the PMD did not change while page_table_lock was released */
1589 spin_lock(vmf
->ptl
);
1590 if (unlikely(!pmd_same(pmd
, *vmf
->pmd
))) {
1593 page_nid
= NUMA_NO_NODE
;
1597 /* Bail if we fail to protect against THP splits for any reason */
1598 if (unlikely(!anon_vma
)) {
1600 page_nid
= NUMA_NO_NODE
;
1605 * Since we took the NUMA fault, we must have observed the !accessible
1606 * bit. Make sure all other CPUs agree with that, to avoid them
1607 * modifying the page we're about to migrate.
1609 * Must be done under PTL such that we'll observe the relevant
1610 * inc_tlb_flush_pending().
1612 * We are not sure a pending tlb flush here is for a huge page
1613 * mapping or not. Hence use the tlb range variant
1615 if (mm_tlb_flush_pending(vma
->vm_mm
)) {
1616 flush_tlb_range(vma
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
1618 * change_huge_pmd() released the pmd lock before
1619 * invalidating the secondary MMUs sharing the primary
1620 * MMU pagetables (with ->invalidate_range()). The
1621 * mmu_notifier_invalidate_range_end() (which
1622 * internally calls ->invalidate_range()) in
1623 * change_pmd_range() will run after us, so we can't
1624 * rely on it here and we need an explicit invalidate.
1626 mmu_notifier_invalidate_range(vma
->vm_mm
, haddr
,
1627 haddr
+ HPAGE_PMD_SIZE
);
1631 * Migrate the THP to the requested node, returns with page unlocked
1632 * and access rights restored.
1634 spin_unlock(vmf
->ptl
);
1636 migrated
= migrate_misplaced_transhuge_page(vma
->vm_mm
, vma
,
1637 vmf
->pmd
, pmd
, vmf
->address
, page
, target_nid
);
1639 flags
|= TNF_MIGRATED
;
1640 page_nid
= target_nid
;
1642 flags
|= TNF_MIGRATE_FAIL
;
1646 BUG_ON(!PageLocked(page
));
1647 was_writable
= pmd_savedwrite(pmd
);
1648 pmd
= pmd_modify(pmd
, vma
->vm_page_prot
);
1649 pmd
= pmd_mkyoung(pmd
);
1651 pmd
= pmd_mkwrite(pmd
);
1652 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, pmd
);
1653 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1656 spin_unlock(vmf
->ptl
);
1660 page_unlock_anon_vma_read(anon_vma
);
1662 if (page_nid
!= NUMA_NO_NODE
)
1663 task_numa_fault(last_cpupid
, page_nid
, HPAGE_PMD_NR
,
1670 * Return true if we do MADV_FREE successfully on entire pmd page.
1671 * Otherwise, return false.
1673 bool madvise_free_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1674 pmd_t
*pmd
, unsigned long addr
, unsigned long next
)
1679 struct mm_struct
*mm
= tlb
->mm
;
1682 tlb_change_page_size(tlb
, HPAGE_PMD_SIZE
);
1684 ptl
= pmd_trans_huge_lock(pmd
, vma
);
1689 if (is_huge_zero_pmd(orig_pmd
))
1692 if (unlikely(!pmd_present(orig_pmd
))) {
1693 VM_BUG_ON(thp_migration_supported() &&
1694 !is_pmd_migration_entry(orig_pmd
));
1698 page
= pmd_page(orig_pmd
);
1700 * If other processes are mapping this page, we couldn't discard
1701 * the page unless they all do MADV_FREE so let's skip the page.
1703 if (page_mapcount(page
) != 1)
1706 if (!trylock_page(page
))
1710 * If user want to discard part-pages of THP, split it so MADV_FREE
1711 * will deactivate only them.
1713 if (next
- addr
!= HPAGE_PMD_SIZE
) {
1716 split_huge_page(page
);
1722 if (PageDirty(page
))
1723 ClearPageDirty(page
);
1726 if (pmd_young(orig_pmd
) || pmd_dirty(orig_pmd
)) {
1727 pmdp_invalidate(vma
, addr
, pmd
);
1728 orig_pmd
= pmd_mkold(orig_pmd
);
1729 orig_pmd
= pmd_mkclean(orig_pmd
);
1731 set_pmd_at(mm
, addr
, pmd
, orig_pmd
);
1732 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1735 mark_page_lazyfree(page
);
1743 static inline void zap_deposited_table(struct mm_struct
*mm
, pmd_t
*pmd
)
1747 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1748 pte_free(mm
, pgtable
);
1752 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1753 pmd_t
*pmd
, unsigned long addr
)
1758 tlb_change_page_size(tlb
, HPAGE_PMD_SIZE
);
1760 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1764 * For architectures like ppc64 we look at deposited pgtable
1765 * when calling pmdp_huge_get_and_clear. So do the
1766 * pgtable_trans_huge_withdraw after finishing pmdp related
1769 orig_pmd
= pmdp_huge_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1771 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1772 if (vma_is_dax(vma
)) {
1773 if (arch_needs_pgtable_deposit())
1774 zap_deposited_table(tlb
->mm
, pmd
);
1776 if (is_huge_zero_pmd(orig_pmd
))
1777 tlb_remove_page_size(tlb
, pmd_page(orig_pmd
), HPAGE_PMD_SIZE
);
1778 } else if (is_huge_zero_pmd(orig_pmd
)) {
1779 zap_deposited_table(tlb
->mm
, pmd
);
1781 tlb_remove_page_size(tlb
, pmd_page(orig_pmd
), HPAGE_PMD_SIZE
);
1783 struct page
*page
= NULL
;
1784 int flush_needed
= 1;
1786 if (pmd_present(orig_pmd
)) {
1787 page
= pmd_page(orig_pmd
);
1788 page_remove_rmap(page
, true);
1789 VM_BUG_ON_PAGE(page_mapcount(page
) < 0, page
);
1790 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1791 } else if (thp_migration_supported()) {
1794 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd
));
1795 entry
= pmd_to_swp_entry(orig_pmd
);
1796 page
= pfn_to_page(swp_offset(entry
));
1799 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1801 if (PageAnon(page
)) {
1802 zap_deposited_table(tlb
->mm
, pmd
);
1803 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1805 if (arch_needs_pgtable_deposit())
1806 zap_deposited_table(tlb
->mm
, pmd
);
1807 add_mm_counter(tlb
->mm
, mm_counter_file(page
), -HPAGE_PMD_NR
);
1812 tlb_remove_page_size(tlb
, page
, HPAGE_PMD_SIZE
);
1817 #ifndef pmd_move_must_withdraw
1818 static inline int pmd_move_must_withdraw(spinlock_t
*new_pmd_ptl
,
1819 spinlock_t
*old_pmd_ptl
,
1820 struct vm_area_struct
*vma
)
1823 * With split pmd lock we also need to move preallocated
1824 * PTE page table if new_pmd is on different PMD page table.
1826 * We also don't deposit and withdraw tables for file pages.
1828 return (new_pmd_ptl
!= old_pmd_ptl
) && vma_is_anonymous(vma
);
1832 static pmd_t
move_soft_dirty_pmd(pmd_t pmd
)
1834 #ifdef CONFIG_MEM_SOFT_DIRTY
1835 if (unlikely(is_pmd_migration_entry(pmd
)))
1836 pmd
= pmd_swp_mksoft_dirty(pmd
);
1837 else if (pmd_present(pmd
))
1838 pmd
= pmd_mksoft_dirty(pmd
);
1843 bool move_huge_pmd(struct vm_area_struct
*vma
, unsigned long old_addr
,
1844 unsigned long new_addr
, unsigned long old_end
,
1845 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1847 spinlock_t
*old_ptl
, *new_ptl
;
1849 struct mm_struct
*mm
= vma
->vm_mm
;
1850 bool force_flush
= false;
1852 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1853 (new_addr
& ~HPAGE_PMD_MASK
) ||
1854 old_end
- old_addr
< HPAGE_PMD_SIZE
)
1858 * The destination pmd shouldn't be established, free_pgtables()
1859 * should have release it.
1861 if (WARN_ON(!pmd_none(*new_pmd
))) {
1862 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1867 * We don't have to worry about the ordering of src and dst
1868 * ptlocks because exclusive mmap_sem prevents deadlock.
1870 old_ptl
= __pmd_trans_huge_lock(old_pmd
, vma
);
1872 new_ptl
= pmd_lockptr(mm
, new_pmd
);
1873 if (new_ptl
!= old_ptl
)
1874 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
1875 pmd
= pmdp_huge_get_and_clear(mm
, old_addr
, old_pmd
);
1876 if (pmd_present(pmd
))
1878 VM_BUG_ON(!pmd_none(*new_pmd
));
1880 if (pmd_move_must_withdraw(new_ptl
, old_ptl
, vma
)) {
1882 pgtable
= pgtable_trans_huge_withdraw(mm
, old_pmd
);
1883 pgtable_trans_huge_deposit(mm
, new_pmd
, pgtable
);
1885 pmd
= move_soft_dirty_pmd(pmd
);
1886 set_pmd_at(mm
, new_addr
, new_pmd
, pmd
);
1888 flush_tlb_range(vma
, old_addr
, old_addr
+ PMD_SIZE
);
1889 if (new_ptl
!= old_ptl
)
1890 spin_unlock(new_ptl
);
1891 spin_unlock(old_ptl
);
1899 * - 0 if PMD could not be locked
1900 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1901 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1903 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1904 unsigned long addr
, pgprot_t newprot
, int prot_numa
)
1906 struct mm_struct
*mm
= vma
->vm_mm
;
1909 bool preserve_write
;
1912 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1916 preserve_write
= prot_numa
&& pmd_write(*pmd
);
1919 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1920 if (is_swap_pmd(*pmd
)) {
1921 swp_entry_t entry
= pmd_to_swp_entry(*pmd
);
1923 VM_BUG_ON(!is_pmd_migration_entry(*pmd
));
1924 if (is_write_migration_entry(entry
)) {
1927 * A protection check is difficult so
1928 * just be safe and disable write
1930 make_migration_entry_read(&entry
);
1931 newpmd
= swp_entry_to_pmd(entry
);
1932 if (pmd_swp_soft_dirty(*pmd
))
1933 newpmd
= pmd_swp_mksoft_dirty(newpmd
);
1934 set_pmd_at(mm
, addr
, pmd
, newpmd
);
1941 * Avoid trapping faults against the zero page. The read-only
1942 * data is likely to be read-cached on the local CPU and
1943 * local/remote hits to the zero page are not interesting.
1945 if (prot_numa
&& is_huge_zero_pmd(*pmd
))
1948 if (prot_numa
&& pmd_protnone(*pmd
))
1952 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1953 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1954 * which is also under down_read(mmap_sem):
1957 * change_huge_pmd(prot_numa=1)
1958 * pmdp_huge_get_and_clear_notify()
1959 * madvise_dontneed()
1961 * pmd_trans_huge(*pmd) == 0 (without ptl)
1964 * // pmd is re-established
1966 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1967 * which may break userspace.
1969 * pmdp_invalidate() is required to make sure we don't miss
1970 * dirty/young flags set by hardware.
1972 entry
= pmdp_invalidate(vma
, addr
, pmd
);
1974 entry
= pmd_modify(entry
, newprot
);
1976 entry
= pmd_mk_savedwrite(entry
);
1978 set_pmd_at(mm
, addr
, pmd
, entry
);
1979 BUG_ON(vma_is_anonymous(vma
) && !preserve_write
&& pmd_write(entry
));
1986 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1988 * Note that if it returns page table lock pointer, this routine returns without
1989 * unlocking page table lock. So callers must unlock it.
1991 spinlock_t
*__pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1994 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
1995 if (likely(is_swap_pmd(*pmd
) || pmd_trans_huge(*pmd
) ||
2003 * Returns true if a given pud maps a thp, false otherwise.
2005 * Note that if it returns true, this routine returns without unlocking page
2006 * table lock. So callers must unlock it.
2008 spinlock_t
*__pud_trans_huge_lock(pud_t
*pud
, struct vm_area_struct
*vma
)
2012 ptl
= pud_lock(vma
->vm_mm
, pud
);
2013 if (likely(pud_trans_huge(*pud
) || pud_devmap(*pud
)))
2019 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
2020 int zap_huge_pud(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
2021 pud_t
*pud
, unsigned long addr
)
2025 ptl
= __pud_trans_huge_lock(pud
, vma
);
2029 * For architectures like ppc64 we look at deposited pgtable
2030 * when calling pudp_huge_get_and_clear. So do the
2031 * pgtable_trans_huge_withdraw after finishing pudp related
2034 pudp_huge_get_and_clear_full(tlb
->mm
, addr
, pud
, tlb
->fullmm
);
2035 tlb_remove_pud_tlb_entry(tlb
, pud
, addr
);
2036 if (vma_is_dax(vma
)) {
2038 /* No zero page support yet */
2040 /* No support for anonymous PUD pages yet */
2046 static void __split_huge_pud_locked(struct vm_area_struct
*vma
, pud_t
*pud
,
2047 unsigned long haddr
)
2049 VM_BUG_ON(haddr
& ~HPAGE_PUD_MASK
);
2050 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
2051 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PUD_SIZE
, vma
);
2052 VM_BUG_ON(!pud_trans_huge(*pud
) && !pud_devmap(*pud
));
2054 count_vm_event(THP_SPLIT_PUD
);
2056 pudp_huge_clear_flush_notify(vma
, haddr
, pud
);
2059 void __split_huge_pud(struct vm_area_struct
*vma
, pud_t
*pud
,
2060 unsigned long address
)
2063 struct mmu_notifier_range range
;
2065 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
2066 address
& HPAGE_PUD_MASK
,
2067 (address
& HPAGE_PUD_MASK
) + HPAGE_PUD_SIZE
);
2068 mmu_notifier_invalidate_range_start(&range
);
2069 ptl
= pud_lock(vma
->vm_mm
, pud
);
2070 if (unlikely(!pud_trans_huge(*pud
) && !pud_devmap(*pud
)))
2072 __split_huge_pud_locked(vma
, pud
, range
.start
);
2077 * No need to double call mmu_notifier->invalidate_range() callback as
2078 * the above pudp_huge_clear_flush_notify() did already call it.
2080 mmu_notifier_invalidate_range_only_end(&range
);
2082 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2084 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
2085 unsigned long haddr
, pmd_t
*pmd
)
2087 struct mm_struct
*mm
= vma
->vm_mm
;
2093 * Leave pmd empty until pte is filled note that it is fine to delay
2094 * notification until mmu_notifier_invalidate_range_end() as we are
2095 * replacing a zero pmd write protected page with a zero pte write
2098 * See Documentation/vm/mmu_notifier.rst
2100 pmdp_huge_clear_flush(vma
, haddr
, pmd
);
2102 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2103 pmd_populate(mm
, &_pmd
, pgtable
);
2105 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2107 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2108 entry
= pte_mkspecial(entry
);
2109 pte
= pte_offset_map(&_pmd
, haddr
);
2110 VM_BUG_ON(!pte_none(*pte
));
2111 set_pte_at(mm
, haddr
, pte
, entry
);
2114 smp_wmb(); /* make pte visible before pmd */
2115 pmd_populate(mm
, pmd
, pgtable
);
2118 static void __split_huge_pmd_locked(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2119 unsigned long haddr
, bool freeze
)
2121 struct mm_struct
*mm
= vma
->vm_mm
;
2124 pmd_t old_pmd
, _pmd
;
2125 bool young
, write
, soft_dirty
, pmd_migration
= false;
2129 VM_BUG_ON(haddr
& ~HPAGE_PMD_MASK
);
2130 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
2131 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
, vma
);
2132 VM_BUG_ON(!is_pmd_migration_entry(*pmd
) && !pmd_trans_huge(*pmd
)
2133 && !pmd_devmap(*pmd
));
2135 count_vm_event(THP_SPLIT_PMD
);
2137 if (!vma_is_anonymous(vma
)) {
2138 _pmd
= pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
2140 * We are going to unmap this huge page. So
2141 * just go ahead and zap it
2143 if (arch_needs_pgtable_deposit())
2144 zap_deposited_table(mm
, pmd
);
2145 if (vma_is_dax(vma
))
2147 page
= pmd_page(_pmd
);
2148 if (!PageDirty(page
) && pmd_dirty(_pmd
))
2149 set_page_dirty(page
);
2150 if (!PageReferenced(page
) && pmd_young(_pmd
))
2151 SetPageReferenced(page
);
2152 page_remove_rmap(page
, true);
2154 add_mm_counter(mm
, mm_counter_file(page
), -HPAGE_PMD_NR
);
2156 } else if (is_huge_zero_pmd(*pmd
)) {
2158 * FIXME: Do we want to invalidate secondary mmu by calling
2159 * mmu_notifier_invalidate_range() see comments below inside
2160 * __split_huge_pmd() ?
2162 * We are going from a zero huge page write protected to zero
2163 * small page also write protected so it does not seems useful
2164 * to invalidate secondary mmu at this time.
2166 return __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
2170 * Up to this point the pmd is present and huge and userland has the
2171 * whole access to the hugepage during the split (which happens in
2172 * place). If we overwrite the pmd with the not-huge version pointing
2173 * to the pte here (which of course we could if all CPUs were bug
2174 * free), userland could trigger a small page size TLB miss on the
2175 * small sized TLB while the hugepage TLB entry is still established in
2176 * the huge TLB. Some CPU doesn't like that.
2177 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2178 * 383 on page 93. Intel should be safe but is also warns that it's
2179 * only safe if the permission and cache attributes of the two entries
2180 * loaded in the two TLB is identical (which should be the case here).
2181 * But it is generally safer to never allow small and huge TLB entries
2182 * for the same virtual address to be loaded simultaneously. So instead
2183 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2184 * current pmd notpresent (atomically because here the pmd_trans_huge
2185 * must remain set at all times on the pmd until the split is complete
2186 * for this pmd), then we flush the SMP TLB and finally we write the
2187 * non-huge version of the pmd entry with pmd_populate.
2189 old_pmd
= pmdp_invalidate(vma
, haddr
, pmd
);
2191 pmd_migration
= is_pmd_migration_entry(old_pmd
);
2192 if (unlikely(pmd_migration
)) {
2195 entry
= pmd_to_swp_entry(old_pmd
);
2196 page
= pfn_to_page(swp_offset(entry
));
2197 write
= is_write_migration_entry(entry
);
2199 soft_dirty
= pmd_swp_soft_dirty(old_pmd
);
2201 page
= pmd_page(old_pmd
);
2202 if (pmd_dirty(old_pmd
))
2204 write
= pmd_write(old_pmd
);
2205 young
= pmd_young(old_pmd
);
2206 soft_dirty
= pmd_soft_dirty(old_pmd
);
2208 VM_BUG_ON_PAGE(!page_count(page
), page
);
2209 page_ref_add(page
, HPAGE_PMD_NR
- 1);
2212 * Withdraw the table only after we mark the pmd entry invalid.
2213 * This's critical for some architectures (Power).
2215 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2216 pmd_populate(mm
, &_pmd
, pgtable
);
2218 for (i
= 0, addr
= haddr
; i
< HPAGE_PMD_NR
; i
++, addr
+= PAGE_SIZE
) {
2221 * Note that NUMA hinting access restrictions are not
2222 * transferred to avoid any possibility of altering
2223 * permissions across VMAs.
2225 if (freeze
|| pmd_migration
) {
2226 swp_entry_t swp_entry
;
2227 swp_entry
= make_migration_entry(page
+ i
, write
);
2228 entry
= swp_entry_to_pte(swp_entry
);
2230 entry
= pte_swp_mksoft_dirty(entry
);
2232 entry
= mk_pte(page
+ i
, READ_ONCE(vma
->vm_page_prot
));
2233 entry
= maybe_mkwrite(entry
, vma
);
2235 entry
= pte_wrprotect(entry
);
2237 entry
= pte_mkold(entry
);
2239 entry
= pte_mksoft_dirty(entry
);
2241 pte
= pte_offset_map(&_pmd
, addr
);
2242 BUG_ON(!pte_none(*pte
));
2243 set_pte_at(mm
, addr
, pte
, entry
);
2244 atomic_inc(&page
[i
]._mapcount
);
2249 * Set PG_double_map before dropping compound_mapcount to avoid
2250 * false-negative page_mapped().
2252 if (compound_mapcount(page
) > 1 && !TestSetPageDoubleMap(page
)) {
2253 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2254 atomic_inc(&page
[i
]._mapcount
);
2257 if (atomic_add_negative(-1, compound_mapcount_ptr(page
))) {
2258 /* Last compound_mapcount is gone. */
2259 __dec_node_page_state(page
, NR_ANON_THPS
);
2260 if (TestClearPageDoubleMap(page
)) {
2261 /* No need in mapcount reference anymore */
2262 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2263 atomic_dec(&page
[i
]._mapcount
);
2267 smp_wmb(); /* make pte visible before pmd */
2268 pmd_populate(mm
, pmd
, pgtable
);
2271 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2272 page_remove_rmap(page
+ i
, false);
2278 void __split_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2279 unsigned long address
, bool freeze
, struct page
*page
)
2282 struct mmu_notifier_range range
;
2284 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
2285 address
& HPAGE_PMD_MASK
,
2286 (address
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
);
2287 mmu_notifier_invalidate_range_start(&range
);
2288 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
2291 * If caller asks to setup a migration entries, we need a page to check
2292 * pmd against. Otherwise we can end up replacing wrong page.
2294 VM_BUG_ON(freeze
&& !page
);
2295 if (page
&& page
!= pmd_page(*pmd
))
2298 if (pmd_trans_huge(*pmd
)) {
2299 page
= pmd_page(*pmd
);
2300 if (PageMlocked(page
))
2301 clear_page_mlock(page
);
2302 } else if (!(pmd_devmap(*pmd
) || is_pmd_migration_entry(*pmd
)))
2304 __split_huge_pmd_locked(vma
, pmd
, range
.start
, freeze
);
2308 * No need to double call mmu_notifier->invalidate_range() callback.
2309 * They are 3 cases to consider inside __split_huge_pmd_locked():
2310 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2311 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2312 * fault will trigger a flush_notify before pointing to a new page
2313 * (it is fine if the secondary mmu keeps pointing to the old zero
2314 * page in the meantime)
2315 * 3) Split a huge pmd into pte pointing to the same page. No need
2316 * to invalidate secondary tlb entry they are all still valid.
2317 * any further changes to individual pte will notify. So no need
2318 * to call mmu_notifier->invalidate_range()
2320 mmu_notifier_invalidate_range_only_end(&range
);
2323 void split_huge_pmd_address(struct vm_area_struct
*vma
, unsigned long address
,
2324 bool freeze
, struct page
*page
)
2331 pgd
= pgd_offset(vma
->vm_mm
, address
);
2332 if (!pgd_present(*pgd
))
2335 p4d
= p4d_offset(pgd
, address
);
2336 if (!p4d_present(*p4d
))
2339 pud
= pud_offset(p4d
, address
);
2340 if (!pud_present(*pud
))
2343 pmd
= pmd_offset(pud
, address
);
2345 __split_huge_pmd(vma
, pmd
, address
, freeze
, page
);
2348 void vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2349 unsigned long start
,
2354 * If the new start address isn't hpage aligned and it could
2355 * previously contain an hugepage: check if we need to split
2358 if (start
& ~HPAGE_PMD_MASK
&&
2359 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2360 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2361 split_huge_pmd_address(vma
, start
, false, NULL
);
2364 * If the new end address isn't hpage aligned and it could
2365 * previously contain an hugepage: check if we need to split
2368 if (end
& ~HPAGE_PMD_MASK
&&
2369 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2370 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2371 split_huge_pmd_address(vma
, end
, false, NULL
);
2374 * If we're also updating the vma->vm_next->vm_start, if the new
2375 * vm_next->vm_start isn't page aligned and it could previously
2376 * contain an hugepage: check if we need to split an huge pmd.
2378 if (adjust_next
> 0) {
2379 struct vm_area_struct
*next
= vma
->vm_next
;
2380 unsigned long nstart
= next
->vm_start
;
2381 nstart
+= adjust_next
<< PAGE_SHIFT
;
2382 if (nstart
& ~HPAGE_PMD_MASK
&&
2383 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2384 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2385 split_huge_pmd_address(next
, nstart
, false, NULL
);
2389 static void unmap_page(struct page
*page
)
2391 enum ttu_flags ttu_flags
= TTU_IGNORE_MLOCK
| TTU_IGNORE_ACCESS
|
2392 TTU_RMAP_LOCKED
| TTU_SPLIT_HUGE_PMD
;
2395 VM_BUG_ON_PAGE(!PageHead(page
), page
);
2398 ttu_flags
|= TTU_SPLIT_FREEZE
;
2400 unmap_success
= try_to_unmap(page
, ttu_flags
);
2401 VM_BUG_ON_PAGE(!unmap_success
, page
);
2404 static void remap_page(struct page
*page
)
2407 if (PageTransHuge(page
)) {
2408 remove_migration_ptes(page
, page
, true);
2410 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2411 remove_migration_ptes(page
+ i
, page
+ i
, true);
2415 static void __split_huge_page_tail(struct page
*head
, int tail
,
2416 struct lruvec
*lruvec
, struct list_head
*list
)
2418 struct page
*page_tail
= head
+ tail
;
2420 VM_BUG_ON_PAGE(atomic_read(&page_tail
->_mapcount
) != -1, page_tail
);
2423 * Clone page flags before unfreezing refcount.
2425 * After successful get_page_unless_zero() might follow flags change,
2426 * for exmaple lock_page() which set PG_waiters.
2428 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
;
2429 page_tail
->flags
|= (head
->flags
&
2430 ((1L << PG_referenced
) |
2431 (1L << PG_swapbacked
) |
2432 (1L << PG_swapcache
) |
2433 (1L << PG_mlocked
) |
2434 (1L << PG_uptodate
) |
2436 (1L << PG_workingset
) |
2438 (1L << PG_unevictable
) |
2441 /* ->mapping in first tail page is compound_mapcount */
2442 VM_BUG_ON_PAGE(tail
> 2 && page_tail
->mapping
!= TAIL_MAPPING
,
2444 page_tail
->mapping
= head
->mapping
;
2445 page_tail
->index
= head
->index
+ tail
;
2447 /* Page flags must be visible before we make the page non-compound. */
2451 * Clear PageTail before unfreezing page refcount.
2453 * After successful get_page_unless_zero() might follow put_page()
2454 * which needs correct compound_head().
2456 clear_compound_head(page_tail
);
2458 /* Finally unfreeze refcount. Additional reference from page cache. */
2459 page_ref_unfreeze(page_tail
, 1 + (!PageAnon(head
) ||
2460 PageSwapCache(head
)));
2462 if (page_is_young(head
))
2463 set_page_young(page_tail
);
2464 if (page_is_idle(head
))
2465 set_page_idle(page_tail
);
2467 page_cpupid_xchg_last(page_tail
, page_cpupid_last(head
));
2470 * always add to the tail because some iterators expect new
2471 * pages to show after the currently processed elements - e.g.
2474 lru_add_page_tail(head
, page_tail
, lruvec
, list
);
2477 static void __split_huge_page(struct page
*page
, struct list_head
*list
,
2478 pgoff_t end
, unsigned long flags
)
2480 struct page
*head
= compound_head(page
);
2481 pg_data_t
*pgdat
= page_pgdat(head
);
2482 struct lruvec
*lruvec
;
2485 lruvec
= mem_cgroup_page_lruvec(head
, pgdat
);
2487 /* complete memcg works before add pages to LRU */
2488 mem_cgroup_split_huge_fixup(head
);
2490 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
2491 __split_huge_page_tail(head
, i
, lruvec
, list
);
2492 /* Some pages can be beyond i_size: drop them from page cache */
2493 if (head
[i
].index
>= end
) {
2494 ClearPageDirty(head
+ i
);
2495 __delete_from_page_cache(head
+ i
, NULL
);
2496 if (IS_ENABLED(CONFIG_SHMEM
) && PageSwapBacked(head
))
2497 shmem_uncharge(head
->mapping
->host
, 1);
2499 } else if (!PageAnon(page
)) {
2500 __xa_store(&head
->mapping
->i_pages
, head
[i
].index
,
2505 ClearPageCompound(head
);
2506 /* See comment in __split_huge_page_tail() */
2507 if (PageAnon(head
)) {
2508 /* Additional pin to swap cache */
2509 if (PageSwapCache(head
))
2510 page_ref_add(head
, 2);
2514 /* Additional pin to page cache */
2515 page_ref_add(head
, 2);
2516 xa_unlock(&head
->mapping
->i_pages
);
2519 spin_unlock_irqrestore(&pgdat
->lru_lock
, flags
);
2523 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2524 struct page
*subpage
= head
+ i
;
2525 if (subpage
== page
)
2527 unlock_page(subpage
);
2530 * Subpages may be freed if there wasn't any mapping
2531 * like if add_to_swap() is running on a lru page that
2532 * had its mapping zapped. And freeing these pages
2533 * requires taking the lru_lock so we do the put_page
2534 * of the tail pages after the split is complete.
2540 int total_mapcount(struct page
*page
)
2542 int i
, compound
, ret
;
2544 VM_BUG_ON_PAGE(PageTail(page
), page
);
2546 if (likely(!PageCompound(page
)))
2547 return atomic_read(&page
->_mapcount
) + 1;
2549 compound
= compound_mapcount(page
);
2553 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2554 ret
+= atomic_read(&page
[i
]._mapcount
) + 1;
2555 /* File pages has compound_mapcount included in _mapcount */
2556 if (!PageAnon(page
))
2557 return ret
- compound
* HPAGE_PMD_NR
;
2558 if (PageDoubleMap(page
))
2559 ret
-= HPAGE_PMD_NR
;
2564 * This calculates accurately how many mappings a transparent hugepage
2565 * has (unlike page_mapcount() which isn't fully accurate). This full
2566 * accuracy is primarily needed to know if copy-on-write faults can
2567 * reuse the page and change the mapping to read-write instead of
2568 * copying them. At the same time this returns the total_mapcount too.
2570 * The function returns the highest mapcount any one of the subpages
2571 * has. If the return value is one, even if different processes are
2572 * mapping different subpages of the transparent hugepage, they can
2573 * all reuse it, because each process is reusing a different subpage.
2575 * The total_mapcount is instead counting all virtual mappings of the
2576 * subpages. If the total_mapcount is equal to "one", it tells the
2577 * caller all mappings belong to the same "mm" and in turn the
2578 * anon_vma of the transparent hugepage can become the vma->anon_vma
2579 * local one as no other process may be mapping any of the subpages.
2581 * It would be more accurate to replace page_mapcount() with
2582 * page_trans_huge_mapcount(), however we only use
2583 * page_trans_huge_mapcount() in the copy-on-write faults where we
2584 * need full accuracy to avoid breaking page pinning, because
2585 * page_trans_huge_mapcount() is slower than page_mapcount().
2587 int page_trans_huge_mapcount(struct page
*page
, int *total_mapcount
)
2589 int i
, ret
, _total_mapcount
, mapcount
;
2591 /* hugetlbfs shouldn't call it */
2592 VM_BUG_ON_PAGE(PageHuge(page
), page
);
2594 if (likely(!PageTransCompound(page
))) {
2595 mapcount
= atomic_read(&page
->_mapcount
) + 1;
2597 *total_mapcount
= mapcount
;
2601 page
= compound_head(page
);
2603 _total_mapcount
= ret
= 0;
2604 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2605 mapcount
= atomic_read(&page
[i
]._mapcount
) + 1;
2606 ret
= max(ret
, mapcount
);
2607 _total_mapcount
+= mapcount
;
2609 if (PageDoubleMap(page
)) {
2611 _total_mapcount
-= HPAGE_PMD_NR
;
2613 mapcount
= compound_mapcount(page
);
2615 _total_mapcount
+= mapcount
;
2617 *total_mapcount
= _total_mapcount
;
2621 /* Racy check whether the huge page can be split */
2622 bool can_split_huge_page(struct page
*page
, int *pextra_pins
)
2626 /* Additional pins from page cache */
2628 extra_pins
= PageSwapCache(page
) ? HPAGE_PMD_NR
: 0;
2630 extra_pins
= HPAGE_PMD_NR
;
2632 *pextra_pins
= extra_pins
;
2633 return total_mapcount(page
) == page_count(page
) - extra_pins
- 1;
2637 * This function splits huge page into normal pages. @page can point to any
2638 * subpage of huge page to split. Split doesn't change the position of @page.
2640 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2641 * The huge page must be locked.
2643 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2645 * Both head page and tail pages will inherit mapping, flags, and so on from
2648 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2649 * they are not mapped.
2651 * Returns 0 if the hugepage is split successfully.
2652 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2655 int split_huge_page_to_list(struct page
*page
, struct list_head
*list
)
2657 struct page
*head
= compound_head(page
);
2658 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(head
));
2659 struct anon_vma
*anon_vma
= NULL
;
2660 struct address_space
*mapping
= NULL
;
2661 int count
, mapcount
, extra_pins
, ret
;
2663 unsigned long flags
;
2666 VM_BUG_ON_PAGE(is_huge_zero_page(page
), page
);
2667 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2668 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
2670 if (PageWriteback(page
))
2673 if (PageAnon(head
)) {
2675 * The caller does not necessarily hold an mmap_sem that would
2676 * prevent the anon_vma disappearing so we first we take a
2677 * reference to it and then lock the anon_vma for write. This
2678 * is similar to page_lock_anon_vma_read except the write lock
2679 * is taken to serialise against parallel split or collapse
2682 anon_vma
= page_get_anon_vma(head
);
2689 anon_vma_lock_write(anon_vma
);
2691 mapping
= head
->mapping
;
2700 i_mmap_lock_read(mapping
);
2703 *__split_huge_page() may need to trim off pages beyond EOF:
2704 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2705 * which cannot be nested inside the page tree lock. So note
2706 * end now: i_size itself may be changed at any moment, but
2707 * head page lock is good enough to serialize the trimming.
2709 end
= DIV_ROUND_UP(i_size_read(mapping
->host
), PAGE_SIZE
);
2713 * Racy check if we can split the page, before unmap_page() will
2716 if (!can_split_huge_page(head
, &extra_pins
)) {
2721 mlocked
= PageMlocked(page
);
2723 VM_BUG_ON_PAGE(compound_mapcount(head
), head
);
2725 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2729 /* prevent PageLRU to go away from under us, and freeze lru stats */
2730 spin_lock_irqsave(&pgdata
->lru_lock
, flags
);
2733 XA_STATE(xas
, &mapping
->i_pages
, page_index(head
));
2736 * Check if the head page is present in page cache.
2737 * We assume all tail are present too, if head is there.
2739 xa_lock(&mapping
->i_pages
);
2740 if (xas_load(&xas
) != head
)
2744 /* Prevent deferred_split_scan() touching ->_refcount */
2745 spin_lock(&pgdata
->split_queue_lock
);
2746 count
= page_count(head
);
2747 mapcount
= total_mapcount(head
);
2748 if (!mapcount
&& page_ref_freeze(head
, 1 + extra_pins
)) {
2749 if (!list_empty(page_deferred_list(head
))) {
2750 pgdata
->split_queue_len
--;
2751 list_del(page_deferred_list(head
));
2754 __dec_node_page_state(page
, NR_SHMEM_THPS
);
2755 spin_unlock(&pgdata
->split_queue_lock
);
2756 __split_huge_page(page
, list
, end
, flags
);
2757 if (PageSwapCache(head
)) {
2758 swp_entry_t entry
= { .val
= page_private(head
) };
2760 ret
= split_swap_cluster(entry
);
2764 if (IS_ENABLED(CONFIG_DEBUG_VM
) && mapcount
) {
2765 pr_alert("total_mapcount: %u, page_count(): %u\n",
2768 dump_page(head
, NULL
);
2769 dump_page(page
, "total_mapcount(head) > 0");
2772 spin_unlock(&pgdata
->split_queue_lock
);
2774 xa_unlock(&mapping
->i_pages
);
2775 spin_unlock_irqrestore(&pgdata
->lru_lock
, flags
);
2782 anon_vma_unlock_write(anon_vma
);
2783 put_anon_vma(anon_vma
);
2786 i_mmap_unlock_read(mapping
);
2788 count_vm_event(!ret
? THP_SPLIT_PAGE
: THP_SPLIT_PAGE_FAILED
);
2792 void free_transhuge_page(struct page
*page
)
2794 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
2795 unsigned long flags
;
2797 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2798 if (!list_empty(page_deferred_list(page
))) {
2799 pgdata
->split_queue_len
--;
2800 list_del(page_deferred_list(page
));
2802 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2803 free_compound_page(page
);
2806 void deferred_split_huge_page(struct page
*page
)
2808 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
2809 unsigned long flags
;
2811 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
2813 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2814 if (list_empty(page_deferred_list(page
))) {
2815 count_vm_event(THP_DEFERRED_SPLIT_PAGE
);
2816 list_add_tail(page_deferred_list(page
), &pgdata
->split_queue
);
2817 pgdata
->split_queue_len
++;
2819 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2822 static unsigned long deferred_split_count(struct shrinker
*shrink
,
2823 struct shrink_control
*sc
)
2825 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2826 return READ_ONCE(pgdata
->split_queue_len
);
2829 static unsigned long deferred_split_scan(struct shrinker
*shrink
,
2830 struct shrink_control
*sc
)
2832 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2833 unsigned long flags
;
2834 LIST_HEAD(list
), *pos
, *next
;
2838 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2839 /* Take pin on all head pages to avoid freeing them under us */
2840 list_for_each_safe(pos
, next
, &pgdata
->split_queue
) {
2841 page
= list_entry((void *)pos
, struct page
, mapping
);
2842 page
= compound_head(page
);
2843 if (get_page_unless_zero(page
)) {
2844 list_move(page_deferred_list(page
), &list
);
2846 /* We lost race with put_compound_page() */
2847 list_del_init(page_deferred_list(page
));
2848 pgdata
->split_queue_len
--;
2850 if (!--sc
->nr_to_scan
)
2853 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2855 list_for_each_safe(pos
, next
, &list
) {
2856 page
= list_entry((void *)pos
, struct page
, mapping
);
2857 if (!trylock_page(page
))
2859 /* split_huge_page() removes page from list on success */
2860 if (!split_huge_page(page
))
2867 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2868 list_splice_tail(&list
, &pgdata
->split_queue
);
2869 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2872 * Stop shrinker if we didn't split any page, but the queue is empty.
2873 * This can happen if pages were freed under us.
2875 if (!split
&& list_empty(&pgdata
->split_queue
))
2880 static struct shrinker deferred_split_shrinker
= {
2881 .count_objects
= deferred_split_count
,
2882 .scan_objects
= deferred_split_scan
,
2883 .seeks
= DEFAULT_SEEKS
,
2884 .flags
= SHRINKER_NUMA_AWARE
,
2887 #ifdef CONFIG_DEBUG_FS
2888 static int split_huge_pages_set(void *data
, u64 val
)
2892 unsigned long pfn
, max_zone_pfn
;
2893 unsigned long total
= 0, split
= 0;
2898 for_each_populated_zone(zone
) {
2899 max_zone_pfn
= zone_end_pfn(zone
);
2900 for (pfn
= zone
->zone_start_pfn
; pfn
< max_zone_pfn
; pfn
++) {
2901 if (!pfn_valid(pfn
))
2904 page
= pfn_to_page(pfn
);
2905 if (!get_page_unless_zero(page
))
2908 if (zone
!= page_zone(page
))
2911 if (!PageHead(page
) || PageHuge(page
) || !PageLRU(page
))
2916 if (!split_huge_page(page
))
2924 pr_info("%lu of %lu THP split\n", split
, total
);
2928 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops
, NULL
, split_huge_pages_set
,
2931 static int __init
split_huge_pages_debugfs(void)
2933 debugfs_create_file("split_huge_pages", 0200, NULL
, NULL
,
2934 &split_huge_pages_fops
);
2937 late_initcall(split_huge_pages_debugfs
);
2940 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2941 void set_pmd_migration_entry(struct page_vma_mapped_walk
*pvmw
,
2944 struct vm_area_struct
*vma
= pvmw
->vma
;
2945 struct mm_struct
*mm
= vma
->vm_mm
;
2946 unsigned long address
= pvmw
->address
;
2951 if (!(pvmw
->pmd
&& !pvmw
->pte
))
2954 flush_cache_range(vma
, address
, address
+ HPAGE_PMD_SIZE
);
2955 pmdval
= *pvmw
->pmd
;
2956 pmdp_invalidate(vma
, address
, pvmw
->pmd
);
2957 if (pmd_dirty(pmdval
))
2958 set_page_dirty(page
);
2959 entry
= make_migration_entry(page
, pmd_write(pmdval
));
2960 pmdswp
= swp_entry_to_pmd(entry
);
2961 if (pmd_soft_dirty(pmdval
))
2962 pmdswp
= pmd_swp_mksoft_dirty(pmdswp
);
2963 set_pmd_at(mm
, address
, pvmw
->pmd
, pmdswp
);
2964 page_remove_rmap(page
, true);
2968 void remove_migration_pmd(struct page_vma_mapped_walk
*pvmw
, struct page
*new)
2970 struct vm_area_struct
*vma
= pvmw
->vma
;
2971 struct mm_struct
*mm
= vma
->vm_mm
;
2972 unsigned long address
= pvmw
->address
;
2973 unsigned long mmun_start
= address
& HPAGE_PMD_MASK
;
2977 if (!(pvmw
->pmd
&& !pvmw
->pte
))
2980 entry
= pmd_to_swp_entry(*pvmw
->pmd
);
2982 pmde
= pmd_mkold(mk_huge_pmd(new, vma
->vm_page_prot
));
2983 if (pmd_swp_soft_dirty(*pvmw
->pmd
))
2984 pmde
= pmd_mksoft_dirty(pmde
);
2985 if (is_write_migration_entry(entry
))
2986 pmde
= maybe_pmd_mkwrite(pmde
, vma
);
2988 flush_cache_range(vma
, mmun_start
, mmun_start
+ HPAGE_PMD_SIZE
);
2990 page_add_anon_rmap(new, vma
, mmun_start
, true);
2992 page_add_file_rmap(new, true);
2993 set_pmd_at(mm
, mmun_start
, pvmw
->pmd
, pmde
);
2994 if ((vma
->vm_flags
& VM_LOCKED
) && !PageDoubleMap(new))
2995 mlock_vma_page(new);
2996 update_mmu_cache_pmd(vma
, address
, pvmw
->pmd
);