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>
35 #include <linux/page_owner.h>
38 #include <asm/pgalloc.h>
42 * By default, transparent hugepage support is disabled in order to avoid
43 * risking an increased memory footprint for applications that are not
44 * guaranteed to benefit from it. When transparent hugepage support is
45 * enabled, it is for all mappings, 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 bool transparent_hugepage_enabled(struct vm_area_struct
*vma
)
67 /* The addr is used to check if the vma size fits */
68 unsigned long addr
= (vma
->vm_end
& HPAGE_PMD_MASK
) - HPAGE_PMD_SIZE
;
70 if (!transhuge_vma_suitable(vma
, addr
))
72 if (vma_is_anonymous(vma
))
73 return __transparent_hugepage_enabled(vma
);
74 if (vma_is_shmem(vma
))
75 return shmem_huge_enabled(vma
);
80 static struct page
*get_huge_zero_page(void)
82 struct page
*zero_page
;
84 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
85 return READ_ONCE(huge_zero_page
);
87 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
90 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
93 count_vm_event(THP_ZERO_PAGE_ALLOC
);
95 if (cmpxchg(&huge_zero_page
, NULL
, zero_page
)) {
97 __free_pages(zero_page
, compound_order(zero_page
));
101 /* We take additional reference here. It will be put back by shrinker */
102 atomic_set(&huge_zero_refcount
, 2);
104 return READ_ONCE(huge_zero_page
);
107 static void put_huge_zero_page(void)
110 * Counter should never go to zero here. Only shrinker can put
113 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
116 struct page
*mm_get_huge_zero_page(struct mm_struct
*mm
)
118 if (test_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
119 return READ_ONCE(huge_zero_page
);
121 if (!get_huge_zero_page())
124 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
125 put_huge_zero_page();
127 return READ_ONCE(huge_zero_page
);
130 void mm_put_huge_zero_page(struct mm_struct
*mm
)
132 if (test_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
133 put_huge_zero_page();
136 static unsigned long shrink_huge_zero_page_count(struct shrinker
*shrink
,
137 struct shrink_control
*sc
)
139 /* we can free zero page only if last reference remains */
140 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
143 static unsigned long shrink_huge_zero_page_scan(struct shrinker
*shrink
,
144 struct shrink_control
*sc
)
146 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
147 struct page
*zero_page
= xchg(&huge_zero_page
, NULL
);
148 BUG_ON(zero_page
== NULL
);
149 __free_pages(zero_page
, compound_order(zero_page
));
156 static struct shrinker huge_zero_page_shrinker
= {
157 .count_objects
= shrink_huge_zero_page_count
,
158 .scan_objects
= shrink_huge_zero_page_scan
,
159 .seeks
= DEFAULT_SEEKS
,
163 static ssize_t
enabled_show(struct kobject
*kobj
,
164 struct kobj_attribute
*attr
, char *buf
)
166 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
))
167 return sprintf(buf
, "[always] madvise never\n");
168 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
169 return sprintf(buf
, "always [madvise] never\n");
171 return sprintf(buf
, "always madvise [never]\n");
174 static ssize_t
enabled_store(struct kobject
*kobj
,
175 struct kobj_attribute
*attr
,
176 const char *buf
, size_t count
)
180 if (!memcmp("always", buf
,
181 min(sizeof("always")-1, count
))) {
182 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
183 set_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
184 } else if (!memcmp("madvise", buf
,
185 min(sizeof("madvise")-1, count
))) {
186 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
187 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
188 } else if (!memcmp("never", buf
,
189 min(sizeof("never")-1, count
))) {
190 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
191 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
196 int err
= start_stop_khugepaged();
202 static struct kobj_attribute enabled_attr
=
203 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
205 ssize_t
single_hugepage_flag_show(struct kobject
*kobj
,
206 struct kobj_attribute
*attr
, char *buf
,
207 enum transparent_hugepage_flag flag
)
209 return sprintf(buf
, "%d\n",
210 !!test_bit(flag
, &transparent_hugepage_flags
));
213 ssize_t
single_hugepage_flag_store(struct kobject
*kobj
,
214 struct kobj_attribute
*attr
,
215 const char *buf
, size_t count
,
216 enum transparent_hugepage_flag flag
)
221 ret
= kstrtoul(buf
, 10, &value
);
228 set_bit(flag
, &transparent_hugepage_flags
);
230 clear_bit(flag
, &transparent_hugepage_flags
);
235 static ssize_t
defrag_show(struct kobject
*kobj
,
236 struct kobj_attribute
*attr
, char *buf
)
238 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
239 return sprintf(buf
, "[always] defer defer+madvise madvise never\n");
240 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
241 return sprintf(buf
, "always [defer] defer+madvise madvise never\n");
242 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
))
243 return sprintf(buf
, "always defer [defer+madvise] madvise never\n");
244 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
245 return sprintf(buf
, "always defer defer+madvise [madvise] never\n");
246 return sprintf(buf
, "always defer defer+madvise madvise [never]\n");
249 static ssize_t
defrag_store(struct kobject
*kobj
,
250 struct kobj_attribute
*attr
,
251 const char *buf
, size_t count
)
253 if (!memcmp("always", buf
,
254 min(sizeof("always")-1, count
))) {
255 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
256 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
258 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
259 } else if (!memcmp("defer+madvise", buf
,
260 min(sizeof("defer+madvise")-1, count
))) {
261 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
262 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
264 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
265 } else if (!memcmp("defer", buf
,
266 min(sizeof("defer")-1, count
))) {
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
268 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
269 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
270 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
271 } else if (!memcmp("madvise", buf
,
272 min(sizeof("madvise")-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 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
277 } else if (!memcmp("never", buf
,
278 min(sizeof("never")-1, count
))) {
279 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
280 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
281 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
282 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
288 static struct kobj_attribute defrag_attr
=
289 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
291 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
292 struct kobj_attribute
*attr
, char *buf
)
294 return single_hugepage_flag_show(kobj
, attr
, buf
,
295 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
297 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
298 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
300 return single_hugepage_flag_store(kobj
, attr
, buf
, count
,
301 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
303 static struct kobj_attribute use_zero_page_attr
=
304 __ATTR(use_zero_page
, 0644, use_zero_page_show
, use_zero_page_store
);
306 static ssize_t
hpage_pmd_size_show(struct kobject
*kobj
,
307 struct kobj_attribute
*attr
, char *buf
)
309 return sprintf(buf
, "%lu\n", HPAGE_PMD_SIZE
);
311 static struct kobj_attribute hpage_pmd_size_attr
=
312 __ATTR_RO(hpage_pmd_size
);
314 #ifdef CONFIG_DEBUG_VM
315 static ssize_t
debug_cow_show(struct kobject
*kobj
,
316 struct kobj_attribute
*attr
, char *buf
)
318 return single_hugepage_flag_show(kobj
, attr
, buf
,
319 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
321 static ssize_t
debug_cow_store(struct kobject
*kobj
,
322 struct kobj_attribute
*attr
,
323 const char *buf
, size_t count
)
325 return single_hugepage_flag_store(kobj
, attr
, buf
, count
,
326 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
328 static struct kobj_attribute debug_cow_attr
=
329 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
330 #endif /* CONFIG_DEBUG_VM */
332 static struct attribute
*hugepage_attr
[] = {
335 &use_zero_page_attr
.attr
,
336 &hpage_pmd_size_attr
.attr
,
337 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
338 &shmem_enabled_attr
.attr
,
340 #ifdef CONFIG_DEBUG_VM
341 &debug_cow_attr
.attr
,
346 static const struct attribute_group hugepage_attr_group
= {
347 .attrs
= hugepage_attr
,
350 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
354 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
355 if (unlikely(!*hugepage_kobj
)) {
356 pr_err("failed to create transparent hugepage kobject\n");
360 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
362 pr_err("failed to register transparent hugepage group\n");
366 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
368 pr_err("failed to register transparent hugepage group\n");
369 goto remove_hp_group
;
375 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
377 kobject_put(*hugepage_kobj
);
381 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
383 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
384 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
385 kobject_put(hugepage_kobj
);
388 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
393 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
396 #endif /* CONFIG_SYSFS */
398 static int __init
hugepage_init(void)
401 struct kobject
*hugepage_kobj
;
403 if (!has_transparent_hugepage()) {
404 transparent_hugepage_flags
= 0;
409 * hugepages can't be allocated by the buddy allocator
411 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
>= MAX_ORDER
);
413 * we use page->mapping and page->index in second tail page
414 * as list_head: assuming THP order >= 2
416 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
< 2);
418 err
= hugepage_init_sysfs(&hugepage_kobj
);
422 err
= khugepaged_init();
426 err
= register_shrinker(&huge_zero_page_shrinker
);
428 goto err_hzp_shrinker
;
429 err
= register_shrinker(&deferred_split_shrinker
);
431 goto err_split_shrinker
;
434 * By default disable transparent hugepages on smaller systems,
435 * where the extra memory used could hurt more than TLB overhead
436 * is likely to save. The admin can still enable it through /sys.
438 if (totalram_pages() < (512 << (20 - PAGE_SHIFT
))) {
439 transparent_hugepage_flags
= 0;
443 err
= start_stop_khugepaged();
449 unregister_shrinker(&deferred_split_shrinker
);
451 unregister_shrinker(&huge_zero_page_shrinker
);
453 khugepaged_destroy();
455 hugepage_exit_sysfs(hugepage_kobj
);
459 subsys_initcall(hugepage_init
);
461 static int __init
setup_transparent_hugepage(char *str
)
466 if (!strcmp(str
, "always")) {
467 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
468 &transparent_hugepage_flags
);
469 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
470 &transparent_hugepage_flags
);
472 } else if (!strcmp(str
, "madvise")) {
473 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
474 &transparent_hugepage_flags
);
475 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
476 &transparent_hugepage_flags
);
478 } else if (!strcmp(str
, "never")) {
479 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
480 &transparent_hugepage_flags
);
481 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
482 &transparent_hugepage_flags
);
487 pr_warn("transparent_hugepage= cannot parse, ignored\n");
490 __setup("transparent_hugepage=", setup_transparent_hugepage
);
492 pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
494 if (likely(vma
->vm_flags
& VM_WRITE
))
495 pmd
= pmd_mkwrite(pmd
);
500 static inline struct deferred_split
*get_deferred_split_queue(struct page
*page
)
502 struct mem_cgroup
*memcg
= compound_head(page
)->mem_cgroup
;
503 struct pglist_data
*pgdat
= NODE_DATA(page_to_nid(page
));
506 return &memcg
->deferred_split_queue
;
508 return &pgdat
->deferred_split_queue
;
511 static inline struct deferred_split
*get_deferred_split_queue(struct page
*page
)
513 struct pglist_data
*pgdat
= NODE_DATA(page_to_nid(page
));
515 return &pgdat
->deferred_split_queue
;
519 void prep_transhuge_page(struct page
*page
)
522 * we use page->mapping and page->indexlru in second tail page
523 * as list_head: assuming THP order >= 2
526 INIT_LIST_HEAD(page_deferred_list(page
));
527 set_compound_page_dtor(page
, TRANSHUGE_PAGE_DTOR
);
530 static unsigned long __thp_get_unmapped_area(struct file
*filp
, unsigned long len
,
531 loff_t off
, unsigned long flags
, unsigned long size
)
534 loff_t off_end
= off
+ len
;
535 loff_t off_align
= round_up(off
, size
);
536 unsigned long len_pad
;
538 if (off_end
<= off_align
|| (off_end
- off_align
) < size
)
541 len_pad
= len
+ size
;
542 if (len_pad
< len
|| (off
+ len_pad
) < off
)
545 addr
= current
->mm
->get_unmapped_area(filp
, 0, len_pad
,
546 off
>> PAGE_SHIFT
, flags
);
547 if (IS_ERR_VALUE(addr
))
550 addr
+= (off
- addr
) & (size
- 1);
554 unsigned long thp_get_unmapped_area(struct file
*filp
, unsigned long addr
,
555 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
557 loff_t off
= (loff_t
)pgoff
<< PAGE_SHIFT
;
561 if (!IS_DAX(filp
->f_mapping
->host
) || !IS_ENABLED(CONFIG_FS_DAX_PMD
))
564 addr
= __thp_get_unmapped_area(filp
, len
, off
, flags
, PMD_SIZE
);
569 return current
->mm
->get_unmapped_area(filp
, addr
, len
, pgoff
, flags
);
571 EXPORT_SYMBOL_GPL(thp_get_unmapped_area
);
573 static vm_fault_t
__do_huge_pmd_anonymous_page(struct vm_fault
*vmf
,
574 struct page
*page
, gfp_t gfp
)
576 struct vm_area_struct
*vma
= vmf
->vma
;
577 struct mem_cgroup
*memcg
;
579 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
582 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
584 if (mem_cgroup_try_charge_delay(page
, vma
->vm_mm
, gfp
, &memcg
, true)) {
586 count_vm_event(THP_FAULT_FALLBACK
);
587 return VM_FAULT_FALLBACK
;
590 pgtable
= pte_alloc_one(vma
->vm_mm
);
591 if (unlikely(!pgtable
)) {
596 clear_huge_page(page
, vmf
->address
, HPAGE_PMD_NR
);
598 * The memory barrier inside __SetPageUptodate makes sure that
599 * clear_huge_page writes become visible before the set_pmd_at()
602 __SetPageUptodate(page
);
604 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
605 if (unlikely(!pmd_none(*vmf
->pmd
))) {
610 ret
= check_stable_address_space(vma
->vm_mm
);
614 /* Deliver the page fault to userland */
615 if (userfaultfd_missing(vma
)) {
618 spin_unlock(vmf
->ptl
);
619 mem_cgroup_cancel_charge(page
, memcg
, true);
621 pte_free(vma
->vm_mm
, pgtable
);
622 ret2
= handle_userfault(vmf
, VM_UFFD_MISSING
);
623 VM_BUG_ON(ret2
& VM_FAULT_FALLBACK
);
627 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
628 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
629 page_add_new_anon_rmap(page
, vma
, haddr
, true);
630 mem_cgroup_commit_charge(page
, memcg
, false, true);
631 lru_cache_add_active_or_unevictable(page
, vma
);
632 pgtable_trans_huge_deposit(vma
->vm_mm
, vmf
->pmd
, pgtable
);
633 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
634 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
635 mm_inc_nr_ptes(vma
->vm_mm
);
636 spin_unlock(vmf
->ptl
);
637 count_vm_event(THP_FAULT_ALLOC
);
638 count_memcg_events(memcg
, THP_FAULT_ALLOC
, 1);
643 spin_unlock(vmf
->ptl
);
646 pte_free(vma
->vm_mm
, pgtable
);
647 mem_cgroup_cancel_charge(page
, memcg
, true);
654 * always: directly stall for all thp allocations
655 * defer: wake kswapd and fail if not immediately available
656 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
657 * fail if not immediately available
658 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
660 * never: never stall for any thp allocation
662 static inline gfp_t
alloc_hugepage_direct_gfpmask(struct vm_area_struct
*vma
)
664 const bool vma_madvised
= !!(vma
->vm_flags
& VM_HUGEPAGE
);
666 /* Always do synchronous compaction */
667 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
668 return GFP_TRANSHUGE
| (vma_madvised
? 0 : __GFP_NORETRY
);
670 /* Kick kcompactd and fail quickly */
671 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
672 return GFP_TRANSHUGE_LIGHT
| __GFP_KSWAPD_RECLAIM
;
674 /* Synchronous compaction if madvised, otherwise kick kcompactd */
675 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
))
676 return GFP_TRANSHUGE_LIGHT
|
677 (vma_madvised
? __GFP_DIRECT_RECLAIM
:
678 __GFP_KSWAPD_RECLAIM
);
680 /* Only do synchronous compaction if madvised */
681 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
682 return GFP_TRANSHUGE_LIGHT
|
683 (vma_madvised
? __GFP_DIRECT_RECLAIM
: 0);
685 return GFP_TRANSHUGE_LIGHT
;
688 /* Caller must hold page table lock. */
689 static bool set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
690 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
691 struct page
*zero_page
)
696 entry
= mk_pmd(zero_page
, vma
->vm_page_prot
);
697 entry
= pmd_mkhuge(entry
);
699 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
700 set_pmd_at(mm
, haddr
, pmd
, entry
);
705 vm_fault_t
do_huge_pmd_anonymous_page(struct vm_fault
*vmf
)
707 struct vm_area_struct
*vma
= vmf
->vma
;
710 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
712 if (!transhuge_vma_suitable(vma
, haddr
))
713 return VM_FAULT_FALLBACK
;
714 if (unlikely(anon_vma_prepare(vma
)))
716 if (unlikely(khugepaged_enter(vma
, vma
->vm_flags
)))
718 if (!(vmf
->flags
& FAULT_FLAG_WRITE
) &&
719 !mm_forbids_zeropage(vma
->vm_mm
) &&
720 transparent_hugepage_use_zero_page()) {
722 struct page
*zero_page
;
725 pgtable
= pte_alloc_one(vma
->vm_mm
);
726 if (unlikely(!pgtable
))
728 zero_page
= mm_get_huge_zero_page(vma
->vm_mm
);
729 if (unlikely(!zero_page
)) {
730 pte_free(vma
->vm_mm
, pgtable
);
731 count_vm_event(THP_FAULT_FALLBACK
);
732 return VM_FAULT_FALLBACK
;
734 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
737 if (pmd_none(*vmf
->pmd
)) {
738 ret
= check_stable_address_space(vma
->vm_mm
);
740 spin_unlock(vmf
->ptl
);
741 } else if (userfaultfd_missing(vma
)) {
742 spin_unlock(vmf
->ptl
);
743 ret
= handle_userfault(vmf
, VM_UFFD_MISSING
);
744 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
746 set_huge_zero_page(pgtable
, vma
->vm_mm
, vma
,
747 haddr
, vmf
->pmd
, zero_page
);
748 spin_unlock(vmf
->ptl
);
752 spin_unlock(vmf
->ptl
);
754 pte_free(vma
->vm_mm
, pgtable
);
757 gfp
= alloc_hugepage_direct_gfpmask(vma
);
758 page
= alloc_hugepage_vma(gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
759 if (unlikely(!page
)) {
760 count_vm_event(THP_FAULT_FALLBACK
);
761 return VM_FAULT_FALLBACK
;
763 prep_transhuge_page(page
);
764 return __do_huge_pmd_anonymous_page(vmf
, page
, gfp
);
767 static void insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
768 pmd_t
*pmd
, pfn_t pfn
, pgprot_t prot
, bool write
,
771 struct mm_struct
*mm
= vma
->vm_mm
;
775 ptl
= pmd_lock(mm
, pmd
);
776 if (!pmd_none(*pmd
)) {
778 if (pmd_pfn(*pmd
) != pfn_t_to_pfn(pfn
)) {
779 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd
));
782 entry
= pmd_mkyoung(*pmd
);
783 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
784 if (pmdp_set_access_flags(vma
, addr
, pmd
, entry
, 1))
785 update_mmu_cache_pmd(vma
, addr
, pmd
);
791 entry
= pmd_mkhuge(pfn_t_pmd(pfn
, prot
));
792 if (pfn_t_devmap(pfn
))
793 entry
= pmd_mkdevmap(entry
);
795 entry
= pmd_mkyoung(pmd_mkdirty(entry
));
796 entry
= maybe_pmd_mkwrite(entry
, vma
);
800 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
805 set_pmd_at(mm
, addr
, pmd
, entry
);
806 update_mmu_cache_pmd(vma
, addr
, pmd
);
811 pte_free(mm
, pgtable
);
814 vm_fault_t
vmf_insert_pfn_pmd(struct vm_fault
*vmf
, pfn_t pfn
, bool write
)
816 unsigned long addr
= vmf
->address
& PMD_MASK
;
817 struct vm_area_struct
*vma
= vmf
->vma
;
818 pgprot_t pgprot
= vma
->vm_page_prot
;
819 pgtable_t pgtable
= NULL
;
822 * If we had pmd_special, we could avoid all these restrictions,
823 * but we need to be consistent with PTEs and architectures that
824 * can't support a 'special' bit.
826 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
));
832 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
833 return VM_FAULT_SIGBUS
;
835 if (arch_needs_pgtable_deposit()) {
836 pgtable
= pte_alloc_one(vma
->vm_mm
);
841 track_pfn_insert(vma
, &pgprot
, pfn
);
843 insert_pfn_pmd(vma
, addr
, vmf
->pmd
, pfn
, pgprot
, write
, pgtable
);
844 return VM_FAULT_NOPAGE
;
846 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd
);
848 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
849 static pud_t
maybe_pud_mkwrite(pud_t pud
, struct vm_area_struct
*vma
)
851 if (likely(vma
->vm_flags
& VM_WRITE
))
852 pud
= pud_mkwrite(pud
);
856 static void insert_pfn_pud(struct vm_area_struct
*vma
, unsigned long addr
,
857 pud_t
*pud
, pfn_t pfn
, pgprot_t prot
, bool write
)
859 struct mm_struct
*mm
= vma
->vm_mm
;
863 ptl
= pud_lock(mm
, pud
);
864 if (!pud_none(*pud
)) {
866 if (pud_pfn(*pud
) != pfn_t_to_pfn(pfn
)) {
867 WARN_ON_ONCE(!is_huge_zero_pud(*pud
));
870 entry
= pud_mkyoung(*pud
);
871 entry
= maybe_pud_mkwrite(pud_mkdirty(entry
), vma
);
872 if (pudp_set_access_flags(vma
, addr
, pud
, entry
, 1))
873 update_mmu_cache_pud(vma
, addr
, pud
);
878 entry
= pud_mkhuge(pfn_t_pud(pfn
, prot
));
879 if (pfn_t_devmap(pfn
))
880 entry
= pud_mkdevmap(entry
);
882 entry
= pud_mkyoung(pud_mkdirty(entry
));
883 entry
= maybe_pud_mkwrite(entry
, vma
);
885 set_pud_at(mm
, addr
, pud
, entry
);
886 update_mmu_cache_pud(vma
, addr
, pud
);
892 vm_fault_t
vmf_insert_pfn_pud(struct vm_fault
*vmf
, pfn_t pfn
, bool write
)
894 unsigned long addr
= vmf
->address
& PUD_MASK
;
895 struct vm_area_struct
*vma
= vmf
->vma
;
896 pgprot_t pgprot
= vma
->vm_page_prot
;
899 * If we had pud_special, we could avoid all these restrictions,
900 * but we need to be consistent with PTEs and architectures that
901 * can't support a 'special' bit.
903 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) &&
905 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
906 (VM_PFNMAP
|VM_MIXEDMAP
));
907 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
909 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
910 return VM_FAULT_SIGBUS
;
912 track_pfn_insert(vma
, &pgprot
, pfn
);
914 insert_pfn_pud(vma
, addr
, vmf
->pud
, pfn
, pgprot
, write
);
915 return VM_FAULT_NOPAGE
;
917 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud
);
918 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
920 static void touch_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
921 pmd_t
*pmd
, int flags
)
925 _pmd
= pmd_mkyoung(*pmd
);
926 if (flags
& FOLL_WRITE
)
927 _pmd
= pmd_mkdirty(_pmd
);
928 if (pmdp_set_access_flags(vma
, addr
& HPAGE_PMD_MASK
,
929 pmd
, _pmd
, flags
& FOLL_WRITE
))
930 update_mmu_cache_pmd(vma
, addr
, pmd
);
933 struct page
*follow_devmap_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
934 pmd_t
*pmd
, int flags
, struct dev_pagemap
**pgmap
)
936 unsigned long pfn
= pmd_pfn(*pmd
);
937 struct mm_struct
*mm
= vma
->vm_mm
;
940 assert_spin_locked(pmd_lockptr(mm
, pmd
));
943 * When we COW a devmap PMD entry, we split it into PTEs, so we should
944 * not be in this function with `flags & FOLL_COW` set.
946 WARN_ONCE(flags
& FOLL_COW
, "mm: In follow_devmap_pmd with FOLL_COW set");
948 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
951 if (pmd_present(*pmd
) && pmd_devmap(*pmd
))
956 if (flags
& FOLL_TOUCH
)
957 touch_pmd(vma
, addr
, pmd
, flags
);
960 * device mapped pages can only be returned if the
961 * caller will manage the page reference count.
963 if (!(flags
& FOLL_GET
))
964 return ERR_PTR(-EEXIST
);
966 pfn
+= (addr
& ~PMD_MASK
) >> PAGE_SHIFT
;
967 *pgmap
= get_dev_pagemap(pfn
, *pgmap
);
969 return ERR_PTR(-EFAULT
);
970 page
= pfn_to_page(pfn
);
976 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
977 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
978 struct vm_area_struct
*vma
)
980 spinlock_t
*dst_ptl
, *src_ptl
;
981 struct page
*src_page
;
983 pgtable_t pgtable
= NULL
;
986 /* Skip if can be re-fill on fault */
987 if (!vma_is_anonymous(vma
))
990 pgtable
= pte_alloc_one(dst_mm
);
991 if (unlikely(!pgtable
))
994 dst_ptl
= pmd_lock(dst_mm
, dst_pmd
);
995 src_ptl
= pmd_lockptr(src_mm
, src_pmd
);
996 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
1001 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1002 if (unlikely(is_swap_pmd(pmd
))) {
1003 swp_entry_t entry
= pmd_to_swp_entry(pmd
);
1005 VM_BUG_ON(!is_pmd_migration_entry(pmd
));
1006 if (is_write_migration_entry(entry
)) {
1007 make_migration_entry_read(&entry
);
1008 pmd
= swp_entry_to_pmd(entry
);
1009 if (pmd_swp_soft_dirty(*src_pmd
))
1010 pmd
= pmd_swp_mksoft_dirty(pmd
);
1011 set_pmd_at(src_mm
, addr
, src_pmd
, pmd
);
1013 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1014 mm_inc_nr_ptes(dst_mm
);
1015 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
1016 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
1022 if (unlikely(!pmd_trans_huge(pmd
))) {
1023 pte_free(dst_mm
, pgtable
);
1027 * When page table lock is held, the huge zero pmd should not be
1028 * under splitting since we don't split the page itself, only pmd to
1031 if (is_huge_zero_pmd(pmd
)) {
1032 struct page
*zero_page
;
1034 * get_huge_zero_page() will never allocate a new page here,
1035 * since we already have a zero page to copy. It just takes a
1038 zero_page
= mm_get_huge_zero_page(dst_mm
);
1039 set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
1045 src_page
= pmd_page(pmd
);
1046 VM_BUG_ON_PAGE(!PageHead(src_page
), src_page
);
1048 page_dup_rmap(src_page
, true);
1049 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1050 mm_inc_nr_ptes(dst_mm
);
1051 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
1053 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
1054 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
1055 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
1059 spin_unlock(src_ptl
);
1060 spin_unlock(dst_ptl
);
1065 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1066 static void touch_pud(struct vm_area_struct
*vma
, unsigned long addr
,
1067 pud_t
*pud
, int flags
)
1071 _pud
= pud_mkyoung(*pud
);
1072 if (flags
& FOLL_WRITE
)
1073 _pud
= pud_mkdirty(_pud
);
1074 if (pudp_set_access_flags(vma
, addr
& HPAGE_PUD_MASK
,
1075 pud
, _pud
, flags
& FOLL_WRITE
))
1076 update_mmu_cache_pud(vma
, addr
, pud
);
1079 struct page
*follow_devmap_pud(struct vm_area_struct
*vma
, unsigned long addr
,
1080 pud_t
*pud
, int flags
, struct dev_pagemap
**pgmap
)
1082 unsigned long pfn
= pud_pfn(*pud
);
1083 struct mm_struct
*mm
= vma
->vm_mm
;
1086 assert_spin_locked(pud_lockptr(mm
, pud
));
1088 if (flags
& FOLL_WRITE
&& !pud_write(*pud
))
1091 if (pud_present(*pud
) && pud_devmap(*pud
))
1096 if (flags
& FOLL_TOUCH
)
1097 touch_pud(vma
, addr
, pud
, flags
);
1100 * device mapped pages can only be returned if the
1101 * caller will manage the page reference count.
1103 if (!(flags
& FOLL_GET
))
1104 return ERR_PTR(-EEXIST
);
1106 pfn
+= (addr
& ~PUD_MASK
) >> PAGE_SHIFT
;
1107 *pgmap
= get_dev_pagemap(pfn
, *pgmap
);
1109 return ERR_PTR(-EFAULT
);
1110 page
= pfn_to_page(pfn
);
1116 int copy_huge_pud(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1117 pud_t
*dst_pud
, pud_t
*src_pud
, unsigned long addr
,
1118 struct vm_area_struct
*vma
)
1120 spinlock_t
*dst_ptl
, *src_ptl
;
1124 dst_ptl
= pud_lock(dst_mm
, dst_pud
);
1125 src_ptl
= pud_lockptr(src_mm
, src_pud
);
1126 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
1130 if (unlikely(!pud_trans_huge(pud
) && !pud_devmap(pud
)))
1134 * When page table lock is held, the huge zero pud should not be
1135 * under splitting since we don't split the page itself, only pud to
1138 if (is_huge_zero_pud(pud
)) {
1139 /* No huge zero pud yet */
1142 pudp_set_wrprotect(src_mm
, addr
, src_pud
);
1143 pud
= pud_mkold(pud_wrprotect(pud
));
1144 set_pud_at(dst_mm
, addr
, dst_pud
, pud
);
1148 spin_unlock(src_ptl
);
1149 spin_unlock(dst_ptl
);
1153 void huge_pud_set_accessed(struct vm_fault
*vmf
, pud_t orig_pud
)
1156 unsigned long haddr
;
1157 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1159 vmf
->ptl
= pud_lock(vmf
->vma
->vm_mm
, vmf
->pud
);
1160 if (unlikely(!pud_same(*vmf
->pud
, orig_pud
)))
1163 entry
= pud_mkyoung(orig_pud
);
1165 entry
= pud_mkdirty(entry
);
1166 haddr
= vmf
->address
& HPAGE_PUD_MASK
;
1167 if (pudp_set_access_flags(vmf
->vma
, haddr
, vmf
->pud
, entry
, write
))
1168 update_mmu_cache_pud(vmf
->vma
, vmf
->address
, vmf
->pud
);
1171 spin_unlock(vmf
->ptl
);
1173 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1175 void huge_pmd_set_accessed(struct vm_fault
*vmf
, pmd_t orig_pmd
)
1178 unsigned long haddr
;
1179 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1181 vmf
->ptl
= pmd_lock(vmf
->vma
->vm_mm
, vmf
->pmd
);
1182 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1185 entry
= pmd_mkyoung(orig_pmd
);
1187 entry
= pmd_mkdirty(entry
);
1188 haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1189 if (pmdp_set_access_flags(vmf
->vma
, haddr
, vmf
->pmd
, entry
, write
))
1190 update_mmu_cache_pmd(vmf
->vma
, vmf
->address
, vmf
->pmd
);
1193 spin_unlock(vmf
->ptl
);
1196 static vm_fault_t
do_huge_pmd_wp_page_fallback(struct vm_fault
*vmf
,
1197 pmd_t orig_pmd
, struct page
*page
)
1199 struct vm_area_struct
*vma
= vmf
->vma
;
1200 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1201 struct mem_cgroup
*memcg
;
1206 struct page
**pages
;
1207 struct mmu_notifier_range range
;
1209 pages
= kmalloc_array(HPAGE_PMD_NR
, sizeof(struct page
*),
1211 if (unlikely(!pages
)) {
1212 ret
|= VM_FAULT_OOM
;
1216 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1217 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
, vma
,
1218 vmf
->address
, page_to_nid(page
));
1219 if (unlikely(!pages
[i
] ||
1220 mem_cgroup_try_charge_delay(pages
[i
], vma
->vm_mm
,
1221 GFP_KERNEL
, &memcg
, false))) {
1225 memcg
= (void *)page_private(pages
[i
]);
1226 set_page_private(pages
[i
], 0);
1227 mem_cgroup_cancel_charge(pages
[i
], memcg
,
1232 ret
|= VM_FAULT_OOM
;
1235 set_page_private(pages
[i
], (unsigned long)memcg
);
1238 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1239 copy_user_highpage(pages
[i
], page
+ i
,
1240 haddr
+ PAGE_SIZE
* i
, vma
);
1241 __SetPageUptodate(pages
[i
]);
1245 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
1246 haddr
, haddr
+ HPAGE_PMD_SIZE
);
1247 mmu_notifier_invalidate_range_start(&range
);
1249 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1250 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1251 goto out_free_pages
;
1252 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1255 * Leave pmd empty until pte is filled note we must notify here as
1256 * concurrent CPU thread might write to new page before the call to
1257 * mmu_notifier_invalidate_range_end() happens which can lead to a
1258 * device seeing memory write in different order than CPU.
1260 * See Documentation/vm/mmu_notifier.rst
1262 pmdp_huge_clear_flush_notify(vma
, haddr
, vmf
->pmd
);
1264 pgtable
= pgtable_trans_huge_withdraw(vma
->vm_mm
, vmf
->pmd
);
1265 pmd_populate(vma
->vm_mm
, &_pmd
, pgtable
);
1267 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1269 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1270 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1271 memcg
= (void *)page_private(pages
[i
]);
1272 set_page_private(pages
[i
], 0);
1273 page_add_new_anon_rmap(pages
[i
], vmf
->vma
, haddr
, false);
1274 mem_cgroup_commit_charge(pages
[i
], memcg
, false, false);
1275 lru_cache_add_active_or_unevictable(pages
[i
], vma
);
1276 vmf
->pte
= pte_offset_map(&_pmd
, haddr
);
1277 VM_BUG_ON(!pte_none(*vmf
->pte
));
1278 set_pte_at(vma
->vm_mm
, haddr
, vmf
->pte
, entry
);
1279 pte_unmap(vmf
->pte
);
1283 smp_wmb(); /* make pte visible before pmd */
1284 pmd_populate(vma
->vm_mm
, vmf
->pmd
, pgtable
);
1285 page_remove_rmap(page
, true);
1286 spin_unlock(vmf
->ptl
);
1289 * No need to double call mmu_notifier->invalidate_range() callback as
1290 * the above pmdp_huge_clear_flush_notify() did already call it.
1292 mmu_notifier_invalidate_range_only_end(&range
);
1294 ret
|= VM_FAULT_WRITE
;
1301 spin_unlock(vmf
->ptl
);
1302 mmu_notifier_invalidate_range_end(&range
);
1303 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1304 memcg
= (void *)page_private(pages
[i
]);
1305 set_page_private(pages
[i
], 0);
1306 mem_cgroup_cancel_charge(pages
[i
], memcg
, false);
1313 vm_fault_t
do_huge_pmd_wp_page(struct vm_fault
*vmf
, pmd_t orig_pmd
)
1315 struct vm_area_struct
*vma
= vmf
->vma
;
1316 struct page
*page
= NULL
, *new_page
;
1317 struct mem_cgroup
*memcg
;
1318 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1319 struct mmu_notifier_range range
;
1320 gfp_t huge_gfp
; /* for allocation and charge */
1323 vmf
->ptl
= pmd_lockptr(vma
->vm_mm
, vmf
->pmd
);
1324 VM_BUG_ON_VMA(!vma
->anon_vma
, vma
);
1325 if (is_huge_zero_pmd(orig_pmd
))
1327 spin_lock(vmf
->ptl
);
1328 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1331 page
= pmd_page(orig_pmd
);
1332 VM_BUG_ON_PAGE(!PageCompound(page
) || !PageHead(page
), page
);
1334 * We can only reuse the page if nobody else maps the huge page or it's
1337 if (!trylock_page(page
)) {
1339 spin_unlock(vmf
->ptl
);
1341 spin_lock(vmf
->ptl
);
1342 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
))) {
1349 if (reuse_swap_page(page
, NULL
)) {
1351 entry
= pmd_mkyoung(orig_pmd
);
1352 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1353 if (pmdp_set_access_flags(vma
, haddr
, vmf
->pmd
, entry
, 1))
1354 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1355 ret
|= VM_FAULT_WRITE
;
1361 spin_unlock(vmf
->ptl
);
1363 if (__transparent_hugepage_enabled(vma
) &&
1364 !transparent_hugepage_debug_cow()) {
1365 huge_gfp
= alloc_hugepage_direct_gfpmask(vma
);
1366 new_page
= alloc_hugepage_vma(huge_gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
1370 if (likely(new_page
)) {
1371 prep_transhuge_page(new_page
);
1374 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1375 ret
|= VM_FAULT_FALLBACK
;
1377 ret
= do_huge_pmd_wp_page_fallback(vmf
, orig_pmd
, page
);
1378 if (ret
& VM_FAULT_OOM
) {
1379 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1380 ret
|= VM_FAULT_FALLBACK
;
1384 count_vm_event(THP_FAULT_FALLBACK
);
1388 if (unlikely(mem_cgroup_try_charge_delay(new_page
, vma
->vm_mm
,
1389 huge_gfp
, &memcg
, true))) {
1391 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1394 ret
|= VM_FAULT_FALLBACK
;
1395 count_vm_event(THP_FAULT_FALLBACK
);
1399 count_vm_event(THP_FAULT_ALLOC
);
1400 count_memcg_events(memcg
, THP_FAULT_ALLOC
, 1);
1403 clear_huge_page(new_page
, vmf
->address
, HPAGE_PMD_NR
);
1405 copy_user_huge_page(new_page
, page
, vmf
->address
,
1407 __SetPageUptodate(new_page
);
1409 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
1410 haddr
, haddr
+ HPAGE_PMD_SIZE
);
1411 mmu_notifier_invalidate_range_start(&range
);
1413 spin_lock(vmf
->ptl
);
1416 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
))) {
1417 spin_unlock(vmf
->ptl
);
1418 mem_cgroup_cancel_charge(new_page
, memcg
, true);
1423 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
1424 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1425 pmdp_huge_clear_flush_notify(vma
, haddr
, vmf
->pmd
);
1426 page_add_new_anon_rmap(new_page
, vma
, haddr
, true);
1427 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
1428 lru_cache_add_active_or_unevictable(new_page
, vma
);
1429 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
1430 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1432 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1434 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1435 page_remove_rmap(page
, true);
1438 ret
|= VM_FAULT_WRITE
;
1440 spin_unlock(vmf
->ptl
);
1443 * No need to double call mmu_notifier->invalidate_range() callback as
1444 * the above pmdp_huge_clear_flush_notify() did already call it.
1446 mmu_notifier_invalidate_range_only_end(&range
);
1450 spin_unlock(vmf
->ptl
);
1455 * FOLL_FORCE can write to even unwritable pmd's, but only
1456 * after we've gone through a COW cycle and they are dirty.
1458 static inline bool can_follow_write_pmd(pmd_t pmd
, unsigned int flags
)
1460 return pmd_write(pmd
) ||
1461 ((flags
& FOLL_FORCE
) && (flags
& FOLL_COW
) && pmd_dirty(pmd
));
1464 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1469 struct mm_struct
*mm
= vma
->vm_mm
;
1470 struct page
*page
= NULL
;
1472 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1474 if (flags
& FOLL_WRITE
&& !can_follow_write_pmd(*pmd
, flags
))
1477 /* Avoid dumping huge zero page */
1478 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1479 return ERR_PTR(-EFAULT
);
1481 /* Full NUMA hinting faults to serialise migration in fault paths */
1482 if ((flags
& FOLL_NUMA
) && pmd_protnone(*pmd
))
1485 page
= pmd_page(*pmd
);
1486 VM_BUG_ON_PAGE(!PageHead(page
) && !is_zone_device_page(page
), page
);
1487 if (flags
& FOLL_TOUCH
)
1488 touch_pmd(vma
, addr
, pmd
, flags
);
1489 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1491 * We don't mlock() pte-mapped THPs. This way we can avoid
1492 * leaking mlocked pages into non-VM_LOCKED VMAs.
1496 * In most cases the pmd is the only mapping of the page as we
1497 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1498 * writable private mappings in populate_vma_page_range().
1500 * The only scenario when we have the page shared here is if we
1501 * mlocking read-only mapping shared over fork(). We skip
1502 * mlocking such pages.
1506 * We can expect PageDoubleMap() to be stable under page lock:
1507 * for file pages we set it in page_add_file_rmap(), which
1508 * requires page to be locked.
1511 if (PageAnon(page
) && compound_mapcount(page
) != 1)
1513 if (PageDoubleMap(page
) || !page
->mapping
)
1515 if (!trylock_page(page
))
1518 if (page
->mapping
&& !PageDoubleMap(page
))
1519 mlock_vma_page(page
);
1523 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1524 VM_BUG_ON_PAGE(!PageCompound(page
) && !is_zone_device_page(page
), page
);
1525 if (flags
& FOLL_GET
)
1532 /* NUMA hinting page fault entry point for trans huge pmds */
1533 vm_fault_t
do_huge_pmd_numa_page(struct vm_fault
*vmf
, pmd_t pmd
)
1535 struct vm_area_struct
*vma
= vmf
->vma
;
1536 struct anon_vma
*anon_vma
= NULL
;
1538 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1539 int page_nid
= NUMA_NO_NODE
, this_nid
= numa_node_id();
1540 int target_nid
, last_cpupid
= -1;
1542 bool migrated
= false;
1546 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1547 if (unlikely(!pmd_same(pmd
, *vmf
->pmd
)))
1551 * If there are potential migrations, wait for completion and retry
1552 * without disrupting NUMA hinting information. Do not relock and
1553 * check_same as the page may no longer be mapped.
1555 if (unlikely(pmd_trans_migrating(*vmf
->pmd
))) {
1556 page
= pmd_page(*vmf
->pmd
);
1557 if (!get_page_unless_zero(page
))
1559 spin_unlock(vmf
->ptl
);
1560 put_and_wait_on_page_locked(page
);
1564 page
= pmd_page(pmd
);
1565 BUG_ON(is_huge_zero_page(page
));
1566 page_nid
= page_to_nid(page
);
1567 last_cpupid
= page_cpupid_last(page
);
1568 count_vm_numa_event(NUMA_HINT_FAULTS
);
1569 if (page_nid
== this_nid
) {
1570 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
1571 flags
|= TNF_FAULT_LOCAL
;
1574 /* See similar comment in do_numa_page for explanation */
1575 if (!pmd_savedwrite(pmd
))
1576 flags
|= TNF_NO_GROUP
;
1579 * Acquire the page lock to serialise THP migrations but avoid dropping
1580 * page_table_lock if at all possible
1582 page_locked
= trylock_page(page
);
1583 target_nid
= mpol_misplaced(page
, vma
, haddr
);
1584 if (target_nid
== NUMA_NO_NODE
) {
1585 /* If the page was locked, there are no parallel migrations */
1590 /* Migration could have started since the pmd_trans_migrating check */
1592 page_nid
= NUMA_NO_NODE
;
1593 if (!get_page_unless_zero(page
))
1595 spin_unlock(vmf
->ptl
);
1596 put_and_wait_on_page_locked(page
);
1601 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1602 * to serialises splits
1605 spin_unlock(vmf
->ptl
);
1606 anon_vma
= page_lock_anon_vma_read(page
);
1608 /* Confirm the PMD did not change while page_table_lock was released */
1609 spin_lock(vmf
->ptl
);
1610 if (unlikely(!pmd_same(pmd
, *vmf
->pmd
))) {
1613 page_nid
= NUMA_NO_NODE
;
1617 /* Bail if we fail to protect against THP splits for any reason */
1618 if (unlikely(!anon_vma
)) {
1620 page_nid
= NUMA_NO_NODE
;
1625 * Since we took the NUMA fault, we must have observed the !accessible
1626 * bit. Make sure all other CPUs agree with that, to avoid them
1627 * modifying the page we're about to migrate.
1629 * Must be done under PTL such that we'll observe the relevant
1630 * inc_tlb_flush_pending().
1632 * We are not sure a pending tlb flush here is for a huge page
1633 * mapping or not. Hence use the tlb range variant
1635 if (mm_tlb_flush_pending(vma
->vm_mm
)) {
1636 flush_tlb_range(vma
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
1638 * change_huge_pmd() released the pmd lock before
1639 * invalidating the secondary MMUs sharing the primary
1640 * MMU pagetables (with ->invalidate_range()). The
1641 * mmu_notifier_invalidate_range_end() (which
1642 * internally calls ->invalidate_range()) in
1643 * change_pmd_range() will run after us, so we can't
1644 * rely on it here and we need an explicit invalidate.
1646 mmu_notifier_invalidate_range(vma
->vm_mm
, haddr
,
1647 haddr
+ HPAGE_PMD_SIZE
);
1651 * Migrate the THP to the requested node, returns with page unlocked
1652 * and access rights restored.
1654 spin_unlock(vmf
->ptl
);
1656 migrated
= migrate_misplaced_transhuge_page(vma
->vm_mm
, vma
,
1657 vmf
->pmd
, pmd
, vmf
->address
, page
, target_nid
);
1659 flags
|= TNF_MIGRATED
;
1660 page_nid
= target_nid
;
1662 flags
|= TNF_MIGRATE_FAIL
;
1666 BUG_ON(!PageLocked(page
));
1667 was_writable
= pmd_savedwrite(pmd
);
1668 pmd
= pmd_modify(pmd
, vma
->vm_page_prot
);
1669 pmd
= pmd_mkyoung(pmd
);
1671 pmd
= pmd_mkwrite(pmd
);
1672 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, pmd
);
1673 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1676 spin_unlock(vmf
->ptl
);
1680 page_unlock_anon_vma_read(anon_vma
);
1682 if (page_nid
!= NUMA_NO_NODE
)
1683 task_numa_fault(last_cpupid
, page_nid
, HPAGE_PMD_NR
,
1690 * Return true if we do MADV_FREE successfully on entire pmd page.
1691 * Otherwise, return false.
1693 bool madvise_free_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1694 pmd_t
*pmd
, unsigned long addr
, unsigned long next
)
1699 struct mm_struct
*mm
= tlb
->mm
;
1702 tlb_change_page_size(tlb
, HPAGE_PMD_SIZE
);
1704 ptl
= pmd_trans_huge_lock(pmd
, vma
);
1709 if (is_huge_zero_pmd(orig_pmd
))
1712 if (unlikely(!pmd_present(orig_pmd
))) {
1713 VM_BUG_ON(thp_migration_supported() &&
1714 !is_pmd_migration_entry(orig_pmd
));
1718 page
= pmd_page(orig_pmd
);
1720 * If other processes are mapping this page, we couldn't discard
1721 * the page unless they all do MADV_FREE so let's skip the page.
1723 if (page_mapcount(page
) != 1)
1726 if (!trylock_page(page
))
1730 * If user want to discard part-pages of THP, split it so MADV_FREE
1731 * will deactivate only them.
1733 if (next
- addr
!= HPAGE_PMD_SIZE
) {
1736 split_huge_page(page
);
1742 if (PageDirty(page
))
1743 ClearPageDirty(page
);
1746 if (pmd_young(orig_pmd
) || pmd_dirty(orig_pmd
)) {
1747 pmdp_invalidate(vma
, addr
, pmd
);
1748 orig_pmd
= pmd_mkold(orig_pmd
);
1749 orig_pmd
= pmd_mkclean(orig_pmd
);
1751 set_pmd_at(mm
, addr
, pmd
, orig_pmd
);
1752 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1755 mark_page_lazyfree(page
);
1763 static inline void zap_deposited_table(struct mm_struct
*mm
, pmd_t
*pmd
)
1767 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1768 pte_free(mm
, pgtable
);
1772 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1773 pmd_t
*pmd
, unsigned long addr
)
1778 tlb_change_page_size(tlb
, HPAGE_PMD_SIZE
);
1780 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1784 * For architectures like ppc64 we look at deposited pgtable
1785 * when calling pmdp_huge_get_and_clear. So do the
1786 * pgtable_trans_huge_withdraw after finishing pmdp related
1789 orig_pmd
= pmdp_huge_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1791 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1792 if (vma_is_dax(vma
)) {
1793 if (arch_needs_pgtable_deposit())
1794 zap_deposited_table(tlb
->mm
, pmd
);
1796 if (is_huge_zero_pmd(orig_pmd
))
1797 tlb_remove_page_size(tlb
, pmd_page(orig_pmd
), HPAGE_PMD_SIZE
);
1798 } else if (is_huge_zero_pmd(orig_pmd
)) {
1799 zap_deposited_table(tlb
->mm
, pmd
);
1801 tlb_remove_page_size(tlb
, pmd_page(orig_pmd
), HPAGE_PMD_SIZE
);
1803 struct page
*page
= NULL
;
1804 int flush_needed
= 1;
1806 if (pmd_present(orig_pmd
)) {
1807 page
= pmd_page(orig_pmd
);
1808 page_remove_rmap(page
, true);
1809 VM_BUG_ON_PAGE(page_mapcount(page
) < 0, page
);
1810 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1811 } else if (thp_migration_supported()) {
1814 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd
));
1815 entry
= pmd_to_swp_entry(orig_pmd
);
1816 page
= pfn_to_page(swp_offset(entry
));
1819 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1821 if (PageAnon(page
)) {
1822 zap_deposited_table(tlb
->mm
, pmd
);
1823 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1825 if (arch_needs_pgtable_deposit())
1826 zap_deposited_table(tlb
->mm
, pmd
);
1827 add_mm_counter(tlb
->mm
, mm_counter_file(page
), -HPAGE_PMD_NR
);
1832 tlb_remove_page_size(tlb
, page
, HPAGE_PMD_SIZE
);
1837 #ifndef pmd_move_must_withdraw
1838 static inline int pmd_move_must_withdraw(spinlock_t
*new_pmd_ptl
,
1839 spinlock_t
*old_pmd_ptl
,
1840 struct vm_area_struct
*vma
)
1843 * With split pmd lock we also need to move preallocated
1844 * PTE page table if new_pmd is on different PMD page table.
1846 * We also don't deposit and withdraw tables for file pages.
1848 return (new_pmd_ptl
!= old_pmd_ptl
) && vma_is_anonymous(vma
);
1852 static pmd_t
move_soft_dirty_pmd(pmd_t pmd
)
1854 #ifdef CONFIG_MEM_SOFT_DIRTY
1855 if (unlikely(is_pmd_migration_entry(pmd
)))
1856 pmd
= pmd_swp_mksoft_dirty(pmd
);
1857 else if (pmd_present(pmd
))
1858 pmd
= pmd_mksoft_dirty(pmd
);
1863 bool move_huge_pmd(struct vm_area_struct
*vma
, unsigned long old_addr
,
1864 unsigned long new_addr
, unsigned long old_end
,
1865 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1867 spinlock_t
*old_ptl
, *new_ptl
;
1869 struct mm_struct
*mm
= vma
->vm_mm
;
1870 bool force_flush
= false;
1872 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1873 (new_addr
& ~HPAGE_PMD_MASK
) ||
1874 old_end
- old_addr
< HPAGE_PMD_SIZE
)
1878 * The destination pmd shouldn't be established, free_pgtables()
1879 * should have release it.
1881 if (WARN_ON(!pmd_none(*new_pmd
))) {
1882 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1887 * We don't have to worry about the ordering of src and dst
1888 * ptlocks because exclusive mmap_sem prevents deadlock.
1890 old_ptl
= __pmd_trans_huge_lock(old_pmd
, vma
);
1892 new_ptl
= pmd_lockptr(mm
, new_pmd
);
1893 if (new_ptl
!= old_ptl
)
1894 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
1895 pmd
= pmdp_huge_get_and_clear(mm
, old_addr
, old_pmd
);
1896 if (pmd_present(pmd
))
1898 VM_BUG_ON(!pmd_none(*new_pmd
));
1900 if (pmd_move_must_withdraw(new_ptl
, old_ptl
, vma
)) {
1902 pgtable
= pgtable_trans_huge_withdraw(mm
, old_pmd
);
1903 pgtable_trans_huge_deposit(mm
, new_pmd
, pgtable
);
1905 pmd
= move_soft_dirty_pmd(pmd
);
1906 set_pmd_at(mm
, new_addr
, new_pmd
, pmd
);
1908 flush_tlb_range(vma
, old_addr
, old_addr
+ PMD_SIZE
);
1909 if (new_ptl
!= old_ptl
)
1910 spin_unlock(new_ptl
);
1911 spin_unlock(old_ptl
);
1919 * - 0 if PMD could not be locked
1920 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1921 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1923 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1924 unsigned long addr
, pgprot_t newprot
, int prot_numa
)
1926 struct mm_struct
*mm
= vma
->vm_mm
;
1929 bool preserve_write
;
1932 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1936 preserve_write
= prot_numa
&& pmd_write(*pmd
);
1939 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1940 if (is_swap_pmd(*pmd
)) {
1941 swp_entry_t entry
= pmd_to_swp_entry(*pmd
);
1943 VM_BUG_ON(!is_pmd_migration_entry(*pmd
));
1944 if (is_write_migration_entry(entry
)) {
1947 * A protection check is difficult so
1948 * just be safe and disable write
1950 make_migration_entry_read(&entry
);
1951 newpmd
= swp_entry_to_pmd(entry
);
1952 if (pmd_swp_soft_dirty(*pmd
))
1953 newpmd
= pmd_swp_mksoft_dirty(newpmd
);
1954 set_pmd_at(mm
, addr
, pmd
, newpmd
);
1961 * Avoid trapping faults against the zero page. The read-only
1962 * data is likely to be read-cached on the local CPU and
1963 * local/remote hits to the zero page are not interesting.
1965 if (prot_numa
&& is_huge_zero_pmd(*pmd
))
1968 if (prot_numa
&& pmd_protnone(*pmd
))
1972 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1973 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1974 * which is also under down_read(mmap_sem):
1977 * change_huge_pmd(prot_numa=1)
1978 * pmdp_huge_get_and_clear_notify()
1979 * madvise_dontneed()
1981 * pmd_trans_huge(*pmd) == 0 (without ptl)
1984 * // pmd is re-established
1986 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1987 * which may break userspace.
1989 * pmdp_invalidate() is required to make sure we don't miss
1990 * dirty/young flags set by hardware.
1992 entry
= pmdp_invalidate(vma
, addr
, pmd
);
1994 entry
= pmd_modify(entry
, newprot
);
1996 entry
= pmd_mk_savedwrite(entry
);
1998 set_pmd_at(mm
, addr
, pmd
, entry
);
1999 BUG_ON(vma_is_anonymous(vma
) && !preserve_write
&& pmd_write(entry
));
2006 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
2008 * Note that if it returns page table lock pointer, this routine returns without
2009 * unlocking page table lock. So callers must unlock it.
2011 spinlock_t
*__pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
2014 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
2015 if (likely(is_swap_pmd(*pmd
) || pmd_trans_huge(*pmd
) ||
2023 * Returns true if a given pud maps a thp, false otherwise.
2025 * Note that if it returns true, this routine returns without unlocking page
2026 * table lock. So callers must unlock it.
2028 spinlock_t
*__pud_trans_huge_lock(pud_t
*pud
, struct vm_area_struct
*vma
)
2032 ptl
= pud_lock(vma
->vm_mm
, pud
);
2033 if (likely(pud_trans_huge(*pud
) || pud_devmap(*pud
)))
2039 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
2040 int zap_huge_pud(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
2041 pud_t
*pud
, unsigned long addr
)
2045 ptl
= __pud_trans_huge_lock(pud
, vma
);
2049 * For architectures like ppc64 we look at deposited pgtable
2050 * when calling pudp_huge_get_and_clear. So do the
2051 * pgtable_trans_huge_withdraw after finishing pudp related
2054 pudp_huge_get_and_clear_full(tlb
->mm
, addr
, pud
, tlb
->fullmm
);
2055 tlb_remove_pud_tlb_entry(tlb
, pud
, addr
);
2056 if (vma_is_dax(vma
)) {
2058 /* No zero page support yet */
2060 /* No support for anonymous PUD pages yet */
2066 static void __split_huge_pud_locked(struct vm_area_struct
*vma
, pud_t
*pud
,
2067 unsigned long haddr
)
2069 VM_BUG_ON(haddr
& ~HPAGE_PUD_MASK
);
2070 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
2071 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PUD_SIZE
, vma
);
2072 VM_BUG_ON(!pud_trans_huge(*pud
) && !pud_devmap(*pud
));
2074 count_vm_event(THP_SPLIT_PUD
);
2076 pudp_huge_clear_flush_notify(vma
, haddr
, pud
);
2079 void __split_huge_pud(struct vm_area_struct
*vma
, pud_t
*pud
,
2080 unsigned long address
)
2083 struct mmu_notifier_range range
;
2085 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
2086 address
& HPAGE_PUD_MASK
,
2087 (address
& HPAGE_PUD_MASK
) + HPAGE_PUD_SIZE
);
2088 mmu_notifier_invalidate_range_start(&range
);
2089 ptl
= pud_lock(vma
->vm_mm
, pud
);
2090 if (unlikely(!pud_trans_huge(*pud
) && !pud_devmap(*pud
)))
2092 __split_huge_pud_locked(vma
, pud
, range
.start
);
2097 * No need to double call mmu_notifier->invalidate_range() callback as
2098 * the above pudp_huge_clear_flush_notify() did already call it.
2100 mmu_notifier_invalidate_range_only_end(&range
);
2102 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2104 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
2105 unsigned long haddr
, pmd_t
*pmd
)
2107 struct mm_struct
*mm
= vma
->vm_mm
;
2113 * Leave pmd empty until pte is filled note that it is fine to delay
2114 * notification until mmu_notifier_invalidate_range_end() as we are
2115 * replacing a zero pmd write protected page with a zero pte write
2118 * See Documentation/vm/mmu_notifier.rst
2120 pmdp_huge_clear_flush(vma
, haddr
, pmd
);
2122 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2123 pmd_populate(mm
, &_pmd
, pgtable
);
2125 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2127 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2128 entry
= pte_mkspecial(entry
);
2129 pte
= pte_offset_map(&_pmd
, haddr
);
2130 VM_BUG_ON(!pte_none(*pte
));
2131 set_pte_at(mm
, haddr
, pte
, entry
);
2134 smp_wmb(); /* make pte visible before pmd */
2135 pmd_populate(mm
, pmd
, pgtable
);
2138 static void __split_huge_pmd_locked(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2139 unsigned long haddr
, bool freeze
)
2141 struct mm_struct
*mm
= vma
->vm_mm
;
2144 pmd_t old_pmd
, _pmd
;
2145 bool young
, write
, soft_dirty
, pmd_migration
= false;
2149 VM_BUG_ON(haddr
& ~HPAGE_PMD_MASK
);
2150 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
2151 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
, vma
);
2152 VM_BUG_ON(!is_pmd_migration_entry(*pmd
) && !pmd_trans_huge(*pmd
)
2153 && !pmd_devmap(*pmd
));
2155 count_vm_event(THP_SPLIT_PMD
);
2157 if (!vma_is_anonymous(vma
)) {
2158 _pmd
= pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
2160 * We are going to unmap this huge page. So
2161 * just go ahead and zap it
2163 if (arch_needs_pgtable_deposit())
2164 zap_deposited_table(mm
, pmd
);
2165 if (vma_is_dax(vma
))
2167 page
= pmd_page(_pmd
);
2168 if (!PageDirty(page
) && pmd_dirty(_pmd
))
2169 set_page_dirty(page
);
2170 if (!PageReferenced(page
) && pmd_young(_pmd
))
2171 SetPageReferenced(page
);
2172 page_remove_rmap(page
, true);
2174 add_mm_counter(mm
, mm_counter_file(page
), -HPAGE_PMD_NR
);
2176 } else if (is_huge_zero_pmd(*pmd
)) {
2178 * FIXME: Do we want to invalidate secondary mmu by calling
2179 * mmu_notifier_invalidate_range() see comments below inside
2180 * __split_huge_pmd() ?
2182 * We are going from a zero huge page write protected to zero
2183 * small page also write protected so it does not seems useful
2184 * to invalidate secondary mmu at this time.
2186 return __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
2190 * Up to this point the pmd is present and huge and userland has the
2191 * whole access to the hugepage during the split (which happens in
2192 * place). If we overwrite the pmd with the not-huge version pointing
2193 * to the pte here (which of course we could if all CPUs were bug
2194 * free), userland could trigger a small page size TLB miss on the
2195 * small sized TLB while the hugepage TLB entry is still established in
2196 * the huge TLB. Some CPU doesn't like that.
2197 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2198 * 383 on page 93. Intel should be safe but is also warns that it's
2199 * only safe if the permission and cache attributes of the two entries
2200 * loaded in the two TLB is identical (which should be the case here).
2201 * But it is generally safer to never allow small and huge TLB entries
2202 * for the same virtual address to be loaded simultaneously. So instead
2203 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2204 * current pmd notpresent (atomically because here the pmd_trans_huge
2205 * must remain set at all times on the pmd until the split is complete
2206 * for this pmd), then we flush the SMP TLB and finally we write the
2207 * non-huge version of the pmd entry with pmd_populate.
2209 old_pmd
= pmdp_invalidate(vma
, haddr
, pmd
);
2211 pmd_migration
= is_pmd_migration_entry(old_pmd
);
2212 if (unlikely(pmd_migration
)) {
2215 entry
= pmd_to_swp_entry(old_pmd
);
2216 page
= pfn_to_page(swp_offset(entry
));
2217 write
= is_write_migration_entry(entry
);
2219 soft_dirty
= pmd_swp_soft_dirty(old_pmd
);
2221 page
= pmd_page(old_pmd
);
2222 if (pmd_dirty(old_pmd
))
2224 write
= pmd_write(old_pmd
);
2225 young
= pmd_young(old_pmd
);
2226 soft_dirty
= pmd_soft_dirty(old_pmd
);
2228 VM_BUG_ON_PAGE(!page_count(page
), page
);
2229 page_ref_add(page
, HPAGE_PMD_NR
- 1);
2232 * Withdraw the table only after we mark the pmd entry invalid.
2233 * This's critical for some architectures (Power).
2235 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2236 pmd_populate(mm
, &_pmd
, pgtable
);
2238 for (i
= 0, addr
= haddr
; i
< HPAGE_PMD_NR
; i
++, addr
+= PAGE_SIZE
) {
2241 * Note that NUMA hinting access restrictions are not
2242 * transferred to avoid any possibility of altering
2243 * permissions across VMAs.
2245 if (freeze
|| pmd_migration
) {
2246 swp_entry_t swp_entry
;
2247 swp_entry
= make_migration_entry(page
+ i
, write
);
2248 entry
= swp_entry_to_pte(swp_entry
);
2250 entry
= pte_swp_mksoft_dirty(entry
);
2252 entry
= mk_pte(page
+ i
, READ_ONCE(vma
->vm_page_prot
));
2253 entry
= maybe_mkwrite(entry
, vma
);
2255 entry
= pte_wrprotect(entry
);
2257 entry
= pte_mkold(entry
);
2259 entry
= pte_mksoft_dirty(entry
);
2261 pte
= pte_offset_map(&_pmd
, addr
);
2262 BUG_ON(!pte_none(*pte
));
2263 set_pte_at(mm
, addr
, pte
, entry
);
2264 atomic_inc(&page
[i
]._mapcount
);
2269 * Set PG_double_map before dropping compound_mapcount to avoid
2270 * false-negative page_mapped().
2272 if (compound_mapcount(page
) > 1 && !TestSetPageDoubleMap(page
)) {
2273 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2274 atomic_inc(&page
[i
]._mapcount
);
2277 if (atomic_add_negative(-1, compound_mapcount_ptr(page
))) {
2278 /* Last compound_mapcount is gone. */
2279 __dec_node_page_state(page
, NR_ANON_THPS
);
2280 if (TestClearPageDoubleMap(page
)) {
2281 /* No need in mapcount reference anymore */
2282 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2283 atomic_dec(&page
[i
]._mapcount
);
2287 smp_wmb(); /* make pte visible before pmd */
2288 pmd_populate(mm
, pmd
, pgtable
);
2291 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2292 page_remove_rmap(page
+ i
, false);
2298 void __split_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2299 unsigned long address
, bool freeze
, struct page
*page
)
2302 struct mmu_notifier_range range
;
2304 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
2305 address
& HPAGE_PMD_MASK
,
2306 (address
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
);
2307 mmu_notifier_invalidate_range_start(&range
);
2308 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
2311 * If caller asks to setup a migration entries, we need a page to check
2312 * pmd against. Otherwise we can end up replacing wrong page.
2314 VM_BUG_ON(freeze
&& !page
);
2315 if (page
&& page
!= pmd_page(*pmd
))
2318 if (pmd_trans_huge(*pmd
)) {
2319 page
= pmd_page(*pmd
);
2320 if (PageMlocked(page
))
2321 clear_page_mlock(page
);
2322 } else if (!(pmd_devmap(*pmd
) || is_pmd_migration_entry(*pmd
)))
2324 __split_huge_pmd_locked(vma
, pmd
, range
.start
, freeze
);
2328 * No need to double call mmu_notifier->invalidate_range() callback.
2329 * They are 3 cases to consider inside __split_huge_pmd_locked():
2330 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2331 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2332 * fault will trigger a flush_notify before pointing to a new page
2333 * (it is fine if the secondary mmu keeps pointing to the old zero
2334 * page in the meantime)
2335 * 3) Split a huge pmd into pte pointing to the same page. No need
2336 * to invalidate secondary tlb entry they are all still valid.
2337 * any further changes to individual pte will notify. So no need
2338 * to call mmu_notifier->invalidate_range()
2340 mmu_notifier_invalidate_range_only_end(&range
);
2343 void split_huge_pmd_address(struct vm_area_struct
*vma
, unsigned long address
,
2344 bool freeze
, struct page
*page
)
2351 pgd
= pgd_offset(vma
->vm_mm
, address
);
2352 if (!pgd_present(*pgd
))
2355 p4d
= p4d_offset(pgd
, address
);
2356 if (!p4d_present(*p4d
))
2359 pud
= pud_offset(p4d
, address
);
2360 if (!pud_present(*pud
))
2363 pmd
= pmd_offset(pud
, address
);
2365 __split_huge_pmd(vma
, pmd
, address
, freeze
, page
);
2368 void vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2369 unsigned long start
,
2374 * If the new start address isn't hpage aligned and it could
2375 * previously contain an hugepage: check if we need to split
2378 if (start
& ~HPAGE_PMD_MASK
&&
2379 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2380 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2381 split_huge_pmd_address(vma
, start
, false, NULL
);
2384 * If the new end address isn't hpage aligned and it could
2385 * previously contain an hugepage: check if we need to split
2388 if (end
& ~HPAGE_PMD_MASK
&&
2389 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2390 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2391 split_huge_pmd_address(vma
, end
, false, NULL
);
2394 * If we're also updating the vma->vm_next->vm_start, if the new
2395 * vm_next->vm_start isn't page aligned and it could previously
2396 * contain an hugepage: check if we need to split an huge pmd.
2398 if (adjust_next
> 0) {
2399 struct vm_area_struct
*next
= vma
->vm_next
;
2400 unsigned long nstart
= next
->vm_start
;
2401 nstart
+= adjust_next
<< PAGE_SHIFT
;
2402 if (nstart
& ~HPAGE_PMD_MASK
&&
2403 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2404 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2405 split_huge_pmd_address(next
, nstart
, false, NULL
);
2409 static void unmap_page(struct page
*page
)
2411 enum ttu_flags ttu_flags
= TTU_IGNORE_MLOCK
| TTU_IGNORE_ACCESS
|
2412 TTU_RMAP_LOCKED
| TTU_SPLIT_HUGE_PMD
;
2415 VM_BUG_ON_PAGE(!PageHead(page
), page
);
2418 ttu_flags
|= TTU_SPLIT_FREEZE
;
2420 unmap_success
= try_to_unmap(page
, ttu_flags
);
2421 VM_BUG_ON_PAGE(!unmap_success
, page
);
2424 static void remap_page(struct page
*page
)
2427 if (PageTransHuge(page
)) {
2428 remove_migration_ptes(page
, page
, true);
2430 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2431 remove_migration_ptes(page
+ i
, page
+ i
, true);
2435 static void __split_huge_page_tail(struct page
*head
, int tail
,
2436 struct lruvec
*lruvec
, struct list_head
*list
)
2438 struct page
*page_tail
= head
+ tail
;
2440 VM_BUG_ON_PAGE(atomic_read(&page_tail
->_mapcount
) != -1, page_tail
);
2443 * Clone page flags before unfreezing refcount.
2445 * After successful get_page_unless_zero() might follow flags change,
2446 * for exmaple lock_page() which set PG_waiters.
2448 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
;
2449 page_tail
->flags
|= (head
->flags
&
2450 ((1L << PG_referenced
) |
2451 (1L << PG_swapbacked
) |
2452 (1L << PG_swapcache
) |
2453 (1L << PG_mlocked
) |
2454 (1L << PG_uptodate
) |
2456 (1L << PG_workingset
) |
2458 (1L << PG_unevictable
) |
2461 /* ->mapping in first tail page is compound_mapcount */
2462 VM_BUG_ON_PAGE(tail
> 2 && page_tail
->mapping
!= TAIL_MAPPING
,
2464 page_tail
->mapping
= head
->mapping
;
2465 page_tail
->index
= head
->index
+ tail
;
2467 /* Page flags must be visible before we make the page non-compound. */
2471 * Clear PageTail before unfreezing page refcount.
2473 * After successful get_page_unless_zero() might follow put_page()
2474 * which needs correct compound_head().
2476 clear_compound_head(page_tail
);
2478 /* Finally unfreeze refcount. Additional reference from page cache. */
2479 page_ref_unfreeze(page_tail
, 1 + (!PageAnon(head
) ||
2480 PageSwapCache(head
)));
2482 if (page_is_young(head
))
2483 set_page_young(page_tail
);
2484 if (page_is_idle(head
))
2485 set_page_idle(page_tail
);
2487 page_cpupid_xchg_last(page_tail
, page_cpupid_last(head
));
2490 * always add to the tail because some iterators expect new
2491 * pages to show after the currently processed elements - e.g.
2494 lru_add_page_tail(head
, page_tail
, lruvec
, list
);
2497 static void __split_huge_page(struct page
*page
, struct list_head
*list
,
2498 pgoff_t end
, unsigned long flags
)
2500 struct page
*head
= compound_head(page
);
2501 pg_data_t
*pgdat
= page_pgdat(head
);
2502 struct lruvec
*lruvec
;
2503 struct address_space
*swap_cache
= NULL
;
2504 unsigned long offset
= 0;
2507 lruvec
= mem_cgroup_page_lruvec(head
, pgdat
);
2509 /* complete memcg works before add pages to LRU */
2510 mem_cgroup_split_huge_fixup(head
);
2512 if (PageAnon(head
) && PageSwapCache(head
)) {
2513 swp_entry_t entry
= { .val
= page_private(head
) };
2515 offset
= swp_offset(entry
);
2516 swap_cache
= swap_address_space(entry
);
2517 xa_lock(&swap_cache
->i_pages
);
2520 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
2521 __split_huge_page_tail(head
, i
, lruvec
, list
);
2522 /* Some pages can be beyond i_size: drop them from page cache */
2523 if (head
[i
].index
>= end
) {
2524 ClearPageDirty(head
+ i
);
2525 __delete_from_page_cache(head
+ i
, NULL
);
2526 if (IS_ENABLED(CONFIG_SHMEM
) && PageSwapBacked(head
))
2527 shmem_uncharge(head
->mapping
->host
, 1);
2529 } else if (!PageAnon(page
)) {
2530 __xa_store(&head
->mapping
->i_pages
, head
[i
].index
,
2532 } else if (swap_cache
) {
2533 __xa_store(&swap_cache
->i_pages
, offset
+ i
,
2538 ClearPageCompound(head
);
2540 split_page_owner(head
, HPAGE_PMD_ORDER
);
2542 /* See comment in __split_huge_page_tail() */
2543 if (PageAnon(head
)) {
2544 /* Additional pin to swap cache */
2545 if (PageSwapCache(head
)) {
2546 page_ref_add(head
, 2);
2547 xa_unlock(&swap_cache
->i_pages
);
2552 /* Additional pin to page cache */
2553 page_ref_add(head
, 2);
2554 xa_unlock(&head
->mapping
->i_pages
);
2557 spin_unlock_irqrestore(&pgdat
->lru_lock
, flags
);
2561 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2562 struct page
*subpage
= head
+ i
;
2563 if (subpage
== page
)
2565 unlock_page(subpage
);
2568 * Subpages may be freed if there wasn't any mapping
2569 * like if add_to_swap() is running on a lru page that
2570 * had its mapping zapped. And freeing these pages
2571 * requires taking the lru_lock so we do the put_page
2572 * of the tail pages after the split is complete.
2578 int total_mapcount(struct page
*page
)
2580 int i
, compound
, ret
;
2582 VM_BUG_ON_PAGE(PageTail(page
), page
);
2584 if (likely(!PageCompound(page
)))
2585 return atomic_read(&page
->_mapcount
) + 1;
2587 compound
= compound_mapcount(page
);
2591 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2592 ret
+= atomic_read(&page
[i
]._mapcount
) + 1;
2593 /* File pages has compound_mapcount included in _mapcount */
2594 if (!PageAnon(page
))
2595 return ret
- compound
* HPAGE_PMD_NR
;
2596 if (PageDoubleMap(page
))
2597 ret
-= HPAGE_PMD_NR
;
2602 * This calculates accurately how many mappings a transparent hugepage
2603 * has (unlike page_mapcount() which isn't fully accurate). This full
2604 * accuracy is primarily needed to know if copy-on-write faults can
2605 * reuse the page and change the mapping to read-write instead of
2606 * copying them. At the same time this returns the total_mapcount too.
2608 * The function returns the highest mapcount any one of the subpages
2609 * has. If the return value is one, even if different processes are
2610 * mapping different subpages of the transparent hugepage, they can
2611 * all reuse it, because each process is reusing a different subpage.
2613 * The total_mapcount is instead counting all virtual mappings of the
2614 * subpages. If the total_mapcount is equal to "one", it tells the
2615 * caller all mappings belong to the same "mm" and in turn the
2616 * anon_vma of the transparent hugepage can become the vma->anon_vma
2617 * local one as no other process may be mapping any of the subpages.
2619 * It would be more accurate to replace page_mapcount() with
2620 * page_trans_huge_mapcount(), however we only use
2621 * page_trans_huge_mapcount() in the copy-on-write faults where we
2622 * need full accuracy to avoid breaking page pinning, because
2623 * page_trans_huge_mapcount() is slower than page_mapcount().
2625 int page_trans_huge_mapcount(struct page
*page
, int *total_mapcount
)
2627 int i
, ret
, _total_mapcount
, mapcount
;
2629 /* hugetlbfs shouldn't call it */
2630 VM_BUG_ON_PAGE(PageHuge(page
), page
);
2632 if (likely(!PageTransCompound(page
))) {
2633 mapcount
= atomic_read(&page
->_mapcount
) + 1;
2635 *total_mapcount
= mapcount
;
2639 page
= compound_head(page
);
2641 _total_mapcount
= ret
= 0;
2642 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2643 mapcount
= atomic_read(&page
[i
]._mapcount
) + 1;
2644 ret
= max(ret
, mapcount
);
2645 _total_mapcount
+= mapcount
;
2647 if (PageDoubleMap(page
)) {
2649 _total_mapcount
-= HPAGE_PMD_NR
;
2651 mapcount
= compound_mapcount(page
);
2653 _total_mapcount
+= mapcount
;
2655 *total_mapcount
= _total_mapcount
;
2659 /* Racy check whether the huge page can be split */
2660 bool can_split_huge_page(struct page
*page
, int *pextra_pins
)
2664 /* Additional pins from page cache */
2666 extra_pins
= PageSwapCache(page
) ? HPAGE_PMD_NR
: 0;
2668 extra_pins
= HPAGE_PMD_NR
;
2670 *pextra_pins
= extra_pins
;
2671 return total_mapcount(page
) == page_count(page
) - extra_pins
- 1;
2675 * This function splits huge page into normal pages. @page can point to any
2676 * subpage of huge page to split. Split doesn't change the position of @page.
2678 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2679 * The huge page must be locked.
2681 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2683 * Both head page and tail pages will inherit mapping, flags, and so on from
2686 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2687 * they are not mapped.
2689 * Returns 0 if the hugepage is split successfully.
2690 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2693 int split_huge_page_to_list(struct page
*page
, struct list_head
*list
)
2695 struct page
*head
= compound_head(page
);
2696 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(head
));
2697 struct deferred_split
*ds_queue
= get_deferred_split_queue(page
);
2698 struct anon_vma
*anon_vma
= NULL
;
2699 struct address_space
*mapping
= NULL
;
2700 int count
, mapcount
, extra_pins
, ret
;
2702 unsigned long flags
;
2705 VM_BUG_ON_PAGE(is_huge_zero_page(page
), page
);
2706 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2707 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
2709 if (PageWriteback(page
))
2712 if (PageAnon(head
)) {
2714 * The caller does not necessarily hold an mmap_sem that would
2715 * prevent the anon_vma disappearing so we first we take a
2716 * reference to it and then lock the anon_vma for write. This
2717 * is similar to page_lock_anon_vma_read except the write lock
2718 * is taken to serialise against parallel split or collapse
2721 anon_vma
= page_get_anon_vma(head
);
2728 anon_vma_lock_write(anon_vma
);
2730 mapping
= head
->mapping
;
2739 i_mmap_lock_read(mapping
);
2742 *__split_huge_page() may need to trim off pages beyond EOF:
2743 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2744 * which cannot be nested inside the page tree lock. So note
2745 * end now: i_size itself may be changed at any moment, but
2746 * head page lock is good enough to serialize the trimming.
2748 end
= DIV_ROUND_UP(i_size_read(mapping
->host
), PAGE_SIZE
);
2752 * Racy check if we can split the page, before unmap_page() will
2755 if (!can_split_huge_page(head
, &extra_pins
)) {
2760 mlocked
= PageMlocked(page
);
2762 VM_BUG_ON_PAGE(compound_mapcount(head
), head
);
2764 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2768 /* prevent PageLRU to go away from under us, and freeze lru stats */
2769 spin_lock_irqsave(&pgdata
->lru_lock
, flags
);
2772 XA_STATE(xas
, &mapping
->i_pages
, page_index(head
));
2775 * Check if the head page is present in page cache.
2776 * We assume all tail are present too, if head is there.
2778 xa_lock(&mapping
->i_pages
);
2779 if (xas_load(&xas
) != head
)
2783 /* Prevent deferred_split_scan() touching ->_refcount */
2784 spin_lock(&ds_queue
->split_queue_lock
);
2785 count
= page_count(head
);
2786 mapcount
= total_mapcount(head
);
2787 if (!mapcount
&& page_ref_freeze(head
, 1 + extra_pins
)) {
2788 if (!list_empty(page_deferred_list(head
))) {
2789 ds_queue
->split_queue_len
--;
2790 list_del(page_deferred_list(head
));
2793 __dec_node_page_state(page
, NR_SHMEM_THPS
);
2794 spin_unlock(&ds_queue
->split_queue_lock
);
2795 __split_huge_page(page
, list
, end
, flags
);
2796 if (PageSwapCache(head
)) {
2797 swp_entry_t entry
= { .val
= page_private(head
) };
2799 ret
= split_swap_cluster(entry
);
2803 if (IS_ENABLED(CONFIG_DEBUG_VM
) && mapcount
) {
2804 pr_alert("total_mapcount: %u, page_count(): %u\n",
2807 dump_page(head
, NULL
);
2808 dump_page(page
, "total_mapcount(head) > 0");
2811 spin_unlock(&ds_queue
->split_queue_lock
);
2813 xa_unlock(&mapping
->i_pages
);
2814 spin_unlock_irqrestore(&pgdata
->lru_lock
, flags
);
2821 anon_vma_unlock_write(anon_vma
);
2822 put_anon_vma(anon_vma
);
2825 i_mmap_unlock_read(mapping
);
2827 count_vm_event(!ret
? THP_SPLIT_PAGE
: THP_SPLIT_PAGE_FAILED
);
2831 void free_transhuge_page(struct page
*page
)
2833 struct deferred_split
*ds_queue
= get_deferred_split_queue(page
);
2834 unsigned long flags
;
2836 spin_lock_irqsave(&ds_queue
->split_queue_lock
, flags
);
2837 if (!list_empty(page_deferred_list(page
))) {
2838 ds_queue
->split_queue_len
--;
2839 list_del(page_deferred_list(page
));
2841 spin_unlock_irqrestore(&ds_queue
->split_queue_lock
, flags
);
2842 free_compound_page(page
);
2845 void deferred_split_huge_page(struct page
*page
)
2847 struct deferred_split
*ds_queue
= get_deferred_split_queue(page
);
2849 struct mem_cgroup
*memcg
= compound_head(page
)->mem_cgroup
;
2851 unsigned long flags
;
2853 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
2856 * The try_to_unmap() in page reclaim path might reach here too,
2857 * this may cause a race condition to corrupt deferred split queue.
2858 * And, if page reclaim is already handling the same page, it is
2859 * unnecessary to handle it again in shrinker.
2861 * Check PageSwapCache to determine if the page is being
2862 * handled by page reclaim since THP swap would add the page into
2863 * swap cache before calling try_to_unmap().
2865 if (PageSwapCache(page
))
2868 spin_lock_irqsave(&ds_queue
->split_queue_lock
, flags
);
2869 if (list_empty(page_deferred_list(page
))) {
2870 count_vm_event(THP_DEFERRED_SPLIT_PAGE
);
2871 list_add_tail(page_deferred_list(page
), &ds_queue
->split_queue
);
2872 ds_queue
->split_queue_len
++;
2875 memcg_set_shrinker_bit(memcg
, page_to_nid(page
),
2876 deferred_split_shrinker
.id
);
2879 spin_unlock_irqrestore(&ds_queue
->split_queue_lock
, flags
);
2882 static unsigned long deferred_split_count(struct shrinker
*shrink
,
2883 struct shrink_control
*sc
)
2885 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2886 struct deferred_split
*ds_queue
= &pgdata
->deferred_split_queue
;
2890 ds_queue
= &sc
->memcg
->deferred_split_queue
;
2892 return READ_ONCE(ds_queue
->split_queue_len
);
2895 static unsigned long deferred_split_scan(struct shrinker
*shrink
,
2896 struct shrink_control
*sc
)
2898 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2899 struct deferred_split
*ds_queue
= &pgdata
->deferred_split_queue
;
2900 unsigned long flags
;
2901 LIST_HEAD(list
), *pos
, *next
;
2907 ds_queue
= &sc
->memcg
->deferred_split_queue
;
2910 spin_lock_irqsave(&ds_queue
->split_queue_lock
, flags
);
2911 /* Take pin on all head pages to avoid freeing them under us */
2912 list_for_each_safe(pos
, next
, &ds_queue
->split_queue
) {
2913 page
= list_entry((void *)pos
, struct page
, mapping
);
2914 page
= compound_head(page
);
2915 if (get_page_unless_zero(page
)) {
2916 list_move(page_deferred_list(page
), &list
);
2918 /* We lost race with put_compound_page() */
2919 list_del_init(page_deferred_list(page
));
2920 ds_queue
->split_queue_len
--;
2922 if (!--sc
->nr_to_scan
)
2925 spin_unlock_irqrestore(&ds_queue
->split_queue_lock
, flags
);
2927 list_for_each_safe(pos
, next
, &list
) {
2928 page
= list_entry((void *)pos
, struct page
, mapping
);
2929 if (!trylock_page(page
))
2931 /* split_huge_page() removes page from list on success */
2932 if (!split_huge_page(page
))
2939 spin_lock_irqsave(&ds_queue
->split_queue_lock
, flags
);
2940 list_splice_tail(&list
, &ds_queue
->split_queue
);
2941 spin_unlock_irqrestore(&ds_queue
->split_queue_lock
, flags
);
2944 * Stop shrinker if we didn't split any page, but the queue is empty.
2945 * This can happen if pages were freed under us.
2947 if (!split
&& list_empty(&ds_queue
->split_queue
))
2952 static struct shrinker deferred_split_shrinker
= {
2953 .count_objects
= deferred_split_count
,
2954 .scan_objects
= deferred_split_scan
,
2955 .seeks
= DEFAULT_SEEKS
,
2956 .flags
= SHRINKER_NUMA_AWARE
| SHRINKER_MEMCG_AWARE
|
2960 #ifdef CONFIG_DEBUG_FS
2961 static int split_huge_pages_set(void *data
, u64 val
)
2965 unsigned long pfn
, max_zone_pfn
;
2966 unsigned long total
= 0, split
= 0;
2971 for_each_populated_zone(zone
) {
2972 max_zone_pfn
= zone_end_pfn(zone
);
2973 for (pfn
= zone
->zone_start_pfn
; pfn
< max_zone_pfn
; pfn
++) {
2974 if (!pfn_valid(pfn
))
2977 page
= pfn_to_page(pfn
);
2978 if (!get_page_unless_zero(page
))
2981 if (zone
!= page_zone(page
))
2984 if (!PageHead(page
) || PageHuge(page
) || !PageLRU(page
))
2989 if (!split_huge_page(page
))
2997 pr_info("%lu of %lu THP split\n", split
, total
);
3001 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops
, NULL
, split_huge_pages_set
,
3004 static int __init
split_huge_pages_debugfs(void)
3006 debugfs_create_file("split_huge_pages", 0200, NULL
, NULL
,
3007 &split_huge_pages_fops
);
3010 late_initcall(split_huge_pages_debugfs
);
3013 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
3014 void set_pmd_migration_entry(struct page_vma_mapped_walk
*pvmw
,
3017 struct vm_area_struct
*vma
= pvmw
->vma
;
3018 struct mm_struct
*mm
= vma
->vm_mm
;
3019 unsigned long address
= pvmw
->address
;
3024 if (!(pvmw
->pmd
&& !pvmw
->pte
))
3027 flush_cache_range(vma
, address
, address
+ HPAGE_PMD_SIZE
);
3028 pmdval
= *pvmw
->pmd
;
3029 pmdp_invalidate(vma
, address
, pvmw
->pmd
);
3030 if (pmd_dirty(pmdval
))
3031 set_page_dirty(page
);
3032 entry
= make_migration_entry(page
, pmd_write(pmdval
));
3033 pmdswp
= swp_entry_to_pmd(entry
);
3034 if (pmd_soft_dirty(pmdval
))
3035 pmdswp
= pmd_swp_mksoft_dirty(pmdswp
);
3036 set_pmd_at(mm
, address
, pvmw
->pmd
, pmdswp
);
3037 page_remove_rmap(page
, true);
3041 void remove_migration_pmd(struct page_vma_mapped_walk
*pvmw
, struct page
*new)
3043 struct vm_area_struct
*vma
= pvmw
->vma
;
3044 struct mm_struct
*mm
= vma
->vm_mm
;
3045 unsigned long address
= pvmw
->address
;
3046 unsigned long mmun_start
= address
& HPAGE_PMD_MASK
;
3050 if (!(pvmw
->pmd
&& !pvmw
->pte
))
3053 entry
= pmd_to_swp_entry(*pvmw
->pmd
);
3055 pmde
= pmd_mkold(mk_huge_pmd(new, vma
->vm_page_prot
));
3056 if (pmd_swp_soft_dirty(*pvmw
->pmd
))
3057 pmde
= pmd_mksoft_dirty(pmde
);
3058 if (is_write_migration_entry(entry
))
3059 pmde
= maybe_pmd_mkwrite(pmde
, vma
);
3061 flush_cache_range(vma
, mmun_start
, mmun_start
+ HPAGE_PMD_SIZE
);
3063 page_add_anon_rmap(new, vma
, mmun_start
, true);
3065 page_add_file_rmap(new, true);
3066 set_pmd_at(mm
, mmun_start
, pvmw
->pmd
, pmde
);
3067 if ((vma
->vm_flags
& VM_LOCKED
) && !PageDoubleMap(new))
3068 mlock_vma_page(new);
3069 update_mmu_cache_pmd(vma
, address
, pvmw
->pmd
);