2 * Copyright (C) 2009 Red Hat, Inc.
4 * This work is licensed under the terms of the GNU GPL, version 2. See
5 * the COPYING file in the top-level directory.
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 #include <linux/sched.h>
12 #include <linux/sched/coredump.h>
13 #include <linux/sched/numa_balancing.h>
14 #include <linux/highmem.h>
15 #include <linux/hugetlb.h>
16 #include <linux/mmu_notifier.h>
17 #include <linux/rmap.h>
18 #include <linux/swap.h>
19 #include <linux/shrinker.h>
20 #include <linux/mm_inline.h>
21 #include <linux/swapops.h>
22 #include <linux/dax.h>
23 #include <linux/khugepaged.h>
24 #include <linux/freezer.h>
25 #include <linux/pfn_t.h>
26 #include <linux/mman.h>
27 #include <linux/memremap.h>
28 #include <linux/pagemap.h>
29 #include <linux/debugfs.h>
30 #include <linux/migrate.h>
31 #include <linux/hashtable.h>
32 #include <linux/userfaultfd_k.h>
33 #include <linux/page_idle.h>
34 #include <linux/shmem_fs.h>
35 #include <linux/oom.h>
36 #include <linux/numa.h>
39 #include <asm/pgalloc.h>
43 * By default, transparent hugepage support is disabled in order to avoid
44 * risking an increased memory footprint for applications that are not
45 * guaranteed to benefit from it. When transparent hugepage support is
46 * enabled, it is for all mappings, and khugepaged scans all mappings.
47 * Defrag is invoked by khugepaged hugepage allocations and by page faults
48 * for all hugepage allocations.
50 unsigned long transparent_hugepage_flags __read_mostly
=
51 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
52 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
54 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
55 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
)|
58 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
)|
59 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
61 static struct shrinker deferred_split_shrinker
;
63 static atomic_t huge_zero_refcount
;
64 struct page
*huge_zero_page __read_mostly
;
66 bool transparent_hugepage_enabled(struct vm_area_struct
*vma
)
68 if (vma_is_anonymous(vma
))
69 return __transparent_hugepage_enabled(vma
);
70 if (vma_is_shmem(vma
) && shmem_huge_enabled(vma
))
71 return __transparent_hugepage_enabled(vma
);
76 static struct page
*get_huge_zero_page(void)
78 struct page
*zero_page
;
80 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
81 return READ_ONCE(huge_zero_page
);
83 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
86 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
89 count_vm_event(THP_ZERO_PAGE_ALLOC
);
91 if (cmpxchg(&huge_zero_page
, NULL
, zero_page
)) {
93 __free_pages(zero_page
, compound_order(zero_page
));
97 /* We take additional reference here. It will be put back by shrinker */
98 atomic_set(&huge_zero_refcount
, 2);
100 return READ_ONCE(huge_zero_page
);
103 static void put_huge_zero_page(void)
106 * Counter should never go to zero here. Only shrinker can put
109 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
112 struct page
*mm_get_huge_zero_page(struct mm_struct
*mm
)
114 if (test_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
115 return READ_ONCE(huge_zero_page
);
117 if (!get_huge_zero_page())
120 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
121 put_huge_zero_page();
123 return READ_ONCE(huge_zero_page
);
126 void mm_put_huge_zero_page(struct mm_struct
*mm
)
128 if (test_bit(MMF_HUGE_ZERO_PAGE
, &mm
->flags
))
129 put_huge_zero_page();
132 static unsigned long shrink_huge_zero_page_count(struct shrinker
*shrink
,
133 struct shrink_control
*sc
)
135 /* we can free zero page only if last reference remains */
136 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
139 static unsigned long shrink_huge_zero_page_scan(struct shrinker
*shrink
,
140 struct shrink_control
*sc
)
142 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
143 struct page
*zero_page
= xchg(&huge_zero_page
, NULL
);
144 BUG_ON(zero_page
== NULL
);
145 __free_pages(zero_page
, compound_order(zero_page
));
152 static struct shrinker huge_zero_page_shrinker
= {
153 .count_objects
= shrink_huge_zero_page_count
,
154 .scan_objects
= shrink_huge_zero_page_scan
,
155 .seeks
= DEFAULT_SEEKS
,
159 static ssize_t
enabled_show(struct kobject
*kobj
,
160 struct kobj_attribute
*attr
, char *buf
)
162 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
))
163 return sprintf(buf
, "[always] madvise never\n");
164 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
165 return sprintf(buf
, "always [madvise] never\n");
167 return sprintf(buf
, "always madvise [never]\n");
170 static ssize_t
enabled_store(struct kobject
*kobj
,
171 struct kobj_attribute
*attr
,
172 const char *buf
, size_t count
)
176 if (!memcmp("always", buf
,
177 min(sizeof("always")-1, count
))) {
178 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
179 set_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
180 } else if (!memcmp("madvise", buf
,
181 min(sizeof("madvise")-1, count
))) {
182 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
183 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
184 } else if (!memcmp("never", buf
,
185 min(sizeof("never")-1, count
))) {
186 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
);
187 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
192 int err
= start_stop_khugepaged();
198 static struct kobj_attribute enabled_attr
=
199 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
201 ssize_t
single_hugepage_flag_show(struct kobject
*kobj
,
202 struct kobj_attribute
*attr
, char *buf
,
203 enum transparent_hugepage_flag flag
)
205 return sprintf(buf
, "%d\n",
206 !!test_bit(flag
, &transparent_hugepage_flags
));
209 ssize_t
single_hugepage_flag_store(struct kobject
*kobj
,
210 struct kobj_attribute
*attr
,
211 const char *buf
, size_t count
,
212 enum transparent_hugepage_flag flag
)
217 ret
= kstrtoul(buf
, 10, &value
);
224 set_bit(flag
, &transparent_hugepage_flags
);
226 clear_bit(flag
, &transparent_hugepage_flags
);
231 static ssize_t
defrag_show(struct kobject
*kobj
,
232 struct kobj_attribute
*attr
, char *buf
)
234 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
235 return sprintf(buf
, "[always] defer defer+madvise madvise never\n");
236 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
237 return sprintf(buf
, "always [defer] defer+madvise madvise never\n");
238 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
))
239 return sprintf(buf
, "always defer [defer+madvise] madvise never\n");
240 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
241 return sprintf(buf
, "always defer defer+madvise [madvise] never\n");
242 return sprintf(buf
, "always defer defer+madvise madvise [never]\n");
245 static ssize_t
defrag_store(struct kobject
*kobj
,
246 struct kobj_attribute
*attr
,
247 const char *buf
, size_t count
)
249 if (!memcmp("always", buf
,
250 min(sizeof("always")-1, count
))) {
251 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
252 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
253 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
254 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
255 } else if (!memcmp("defer+madvise", buf
,
256 min(sizeof("defer+madvise")-1, count
))) {
257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
258 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
259 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
260 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
261 } else if (!memcmp("defer", buf
,
262 min(sizeof("defer")-1, count
))) {
263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
264 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
265 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
266 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
267 } else if (!memcmp("madvise", buf
,
268 min(sizeof("madvise")-1, count
))) {
269 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
270 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
271 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
272 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
273 } else if (!memcmp("never", buf
,
274 min(sizeof("never")-1, count
))) {
275 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
);
276 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
);
277 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
);
278 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
);
284 static struct kobj_attribute defrag_attr
=
285 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
287 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
288 struct kobj_attribute
*attr
, char *buf
)
290 return single_hugepage_flag_show(kobj
, attr
, buf
,
291 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
293 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
294 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
296 return single_hugepage_flag_store(kobj
, attr
, buf
, count
,
297 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
299 static struct kobj_attribute use_zero_page_attr
=
300 __ATTR(use_zero_page
, 0644, use_zero_page_show
, use_zero_page_store
);
302 static ssize_t
hpage_pmd_size_show(struct kobject
*kobj
,
303 struct kobj_attribute
*attr
, char *buf
)
305 return sprintf(buf
, "%lu\n", HPAGE_PMD_SIZE
);
307 static struct kobj_attribute hpage_pmd_size_attr
=
308 __ATTR_RO(hpage_pmd_size
);
310 #ifdef CONFIG_DEBUG_VM
311 static ssize_t
debug_cow_show(struct kobject
*kobj
,
312 struct kobj_attribute
*attr
, char *buf
)
314 return single_hugepage_flag_show(kobj
, attr
, buf
,
315 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
317 static ssize_t
debug_cow_store(struct kobject
*kobj
,
318 struct kobj_attribute
*attr
,
319 const char *buf
, size_t count
)
321 return single_hugepage_flag_store(kobj
, attr
, buf
, count
,
322 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
324 static struct kobj_attribute debug_cow_attr
=
325 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
326 #endif /* CONFIG_DEBUG_VM */
328 static struct attribute
*hugepage_attr
[] = {
331 &use_zero_page_attr
.attr
,
332 &hpage_pmd_size_attr
.attr
,
333 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
334 &shmem_enabled_attr
.attr
,
336 #ifdef CONFIG_DEBUG_VM
337 &debug_cow_attr
.attr
,
342 static const struct attribute_group hugepage_attr_group
= {
343 .attrs
= hugepage_attr
,
346 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
350 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
351 if (unlikely(!*hugepage_kobj
)) {
352 pr_err("failed to create transparent hugepage kobject\n");
356 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
358 pr_err("failed to register transparent hugepage group\n");
362 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
364 pr_err("failed to register transparent hugepage group\n");
365 goto remove_hp_group
;
371 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
373 kobject_put(*hugepage_kobj
);
377 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
379 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
380 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
381 kobject_put(hugepage_kobj
);
384 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
389 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
392 #endif /* CONFIG_SYSFS */
394 static int __init
hugepage_init(void)
397 struct kobject
*hugepage_kobj
;
399 if (!has_transparent_hugepage()) {
400 transparent_hugepage_flags
= 0;
405 * hugepages can't be allocated by the buddy allocator
407 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
>= MAX_ORDER
);
409 * we use page->mapping and page->index in second tail page
410 * as list_head: assuming THP order >= 2
412 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
< 2);
414 err
= hugepage_init_sysfs(&hugepage_kobj
);
418 err
= khugepaged_init();
422 err
= register_shrinker(&huge_zero_page_shrinker
);
424 goto err_hzp_shrinker
;
425 err
= register_shrinker(&deferred_split_shrinker
);
427 goto err_split_shrinker
;
430 * By default disable transparent hugepages on smaller systems,
431 * where the extra memory used could hurt more than TLB overhead
432 * is likely to save. The admin can still enable it through /sys.
434 if (totalram_pages() < (512 << (20 - PAGE_SHIFT
))) {
435 transparent_hugepage_flags
= 0;
439 err
= start_stop_khugepaged();
445 unregister_shrinker(&deferred_split_shrinker
);
447 unregister_shrinker(&huge_zero_page_shrinker
);
449 khugepaged_destroy();
451 hugepage_exit_sysfs(hugepage_kobj
);
455 subsys_initcall(hugepage_init
);
457 static int __init
setup_transparent_hugepage(char *str
)
462 if (!strcmp(str
, "always")) {
463 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
464 &transparent_hugepage_flags
);
465 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
466 &transparent_hugepage_flags
);
468 } else if (!strcmp(str
, "madvise")) {
469 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
470 &transparent_hugepage_flags
);
471 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
472 &transparent_hugepage_flags
);
474 } else if (!strcmp(str
, "never")) {
475 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
476 &transparent_hugepage_flags
);
477 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
478 &transparent_hugepage_flags
);
483 pr_warn("transparent_hugepage= cannot parse, ignored\n");
486 __setup("transparent_hugepage=", setup_transparent_hugepage
);
488 pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
490 if (likely(vma
->vm_flags
& VM_WRITE
))
491 pmd
= pmd_mkwrite(pmd
);
495 static inline struct list_head
*page_deferred_list(struct page
*page
)
497 /* ->lru in the tail pages is occupied by compound_head. */
498 return &page
[2].deferred_list
;
501 void prep_transhuge_page(struct page
*page
)
504 * we use page->mapping and page->indexlru in second tail page
505 * as list_head: assuming THP order >= 2
508 INIT_LIST_HEAD(page_deferred_list(page
));
509 set_compound_page_dtor(page
, TRANSHUGE_PAGE_DTOR
);
512 unsigned long __thp_get_unmapped_area(struct file
*filp
, unsigned long len
,
513 loff_t off
, unsigned long flags
, unsigned long size
)
516 loff_t off_end
= off
+ len
;
517 loff_t off_align
= round_up(off
, size
);
518 unsigned long len_pad
;
520 if (off_end
<= off_align
|| (off_end
- off_align
) < size
)
523 len_pad
= len
+ size
;
524 if (len_pad
< len
|| (off
+ len_pad
) < off
)
527 addr
= current
->mm
->get_unmapped_area(filp
, 0, len_pad
,
528 off
>> PAGE_SHIFT
, flags
);
529 if (IS_ERR_VALUE(addr
))
532 addr
+= (off
- addr
) & (size
- 1);
536 unsigned long thp_get_unmapped_area(struct file
*filp
, unsigned long addr
,
537 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
539 loff_t off
= (loff_t
)pgoff
<< PAGE_SHIFT
;
543 if (!IS_DAX(filp
->f_mapping
->host
) || !IS_ENABLED(CONFIG_FS_DAX_PMD
))
546 addr
= __thp_get_unmapped_area(filp
, len
, off
, flags
, PMD_SIZE
);
551 return current
->mm
->get_unmapped_area(filp
, addr
, len
, pgoff
, flags
);
553 EXPORT_SYMBOL_GPL(thp_get_unmapped_area
);
555 static vm_fault_t
__do_huge_pmd_anonymous_page(struct vm_fault
*vmf
,
556 struct page
*page
, gfp_t gfp
)
558 struct vm_area_struct
*vma
= vmf
->vma
;
559 struct mem_cgroup
*memcg
;
561 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
564 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
566 if (mem_cgroup_try_charge_delay(page
, vma
->vm_mm
, gfp
, &memcg
, true)) {
568 count_vm_event(THP_FAULT_FALLBACK
);
569 return VM_FAULT_FALLBACK
;
572 pgtable
= pte_alloc_one(vma
->vm_mm
);
573 if (unlikely(!pgtable
)) {
578 clear_huge_page(page
, vmf
->address
, HPAGE_PMD_NR
);
580 * The memory barrier inside __SetPageUptodate makes sure that
581 * clear_huge_page writes become visible before the set_pmd_at()
584 __SetPageUptodate(page
);
586 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
587 if (unlikely(!pmd_none(*vmf
->pmd
))) {
592 ret
= check_stable_address_space(vma
->vm_mm
);
596 /* Deliver the page fault to userland */
597 if (userfaultfd_missing(vma
)) {
600 spin_unlock(vmf
->ptl
);
601 mem_cgroup_cancel_charge(page
, memcg
, true);
603 pte_free(vma
->vm_mm
, pgtable
);
604 ret2
= handle_userfault(vmf
, VM_UFFD_MISSING
);
605 VM_BUG_ON(ret2
& VM_FAULT_FALLBACK
);
609 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
610 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
611 page_add_new_anon_rmap(page
, vma
, haddr
, true);
612 mem_cgroup_commit_charge(page
, memcg
, false, true);
613 lru_cache_add_active_or_unevictable(page
, vma
);
614 pgtable_trans_huge_deposit(vma
->vm_mm
, vmf
->pmd
, pgtable
);
615 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
616 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
617 mm_inc_nr_ptes(vma
->vm_mm
);
618 spin_unlock(vmf
->ptl
);
619 count_vm_event(THP_FAULT_ALLOC
);
620 count_memcg_events(memcg
, THP_FAULT_ALLOC
, 1);
625 spin_unlock(vmf
->ptl
);
628 pte_free(vma
->vm_mm
, pgtable
);
629 mem_cgroup_cancel_charge(page
, memcg
, true);
636 * always: directly stall for all thp allocations
637 * defer: wake kswapd and fail if not immediately available
638 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
639 * fail if not immediately available
640 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
642 * never: never stall for any thp allocation
644 static inline gfp_t
alloc_hugepage_direct_gfpmask(struct vm_area_struct
*vma
)
646 const bool vma_madvised
= !!(vma
->vm_flags
& VM_HUGEPAGE
);
648 /* Always do synchronous compaction */
649 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
650 return GFP_TRANSHUGE
| (vma_madvised
? 0 : __GFP_NORETRY
);
652 /* Kick kcompactd and fail quickly */
653 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
654 return GFP_TRANSHUGE_LIGHT
| __GFP_KSWAPD_RECLAIM
;
656 /* Synchronous compaction if madvised, otherwise kick kcompactd */
657 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG
, &transparent_hugepage_flags
))
658 return GFP_TRANSHUGE_LIGHT
|
659 (vma_madvised
? __GFP_DIRECT_RECLAIM
:
660 __GFP_KSWAPD_RECLAIM
);
662 /* Only do synchronous compaction if madvised */
663 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
664 return GFP_TRANSHUGE_LIGHT
|
665 (vma_madvised
? __GFP_DIRECT_RECLAIM
: 0);
667 return GFP_TRANSHUGE_LIGHT
;
670 /* Caller must hold page table lock. */
671 static bool set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
672 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
673 struct page
*zero_page
)
678 entry
= mk_pmd(zero_page
, vma
->vm_page_prot
);
679 entry
= pmd_mkhuge(entry
);
681 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
682 set_pmd_at(mm
, haddr
, pmd
, entry
);
687 vm_fault_t
do_huge_pmd_anonymous_page(struct vm_fault
*vmf
)
689 struct vm_area_struct
*vma
= vmf
->vma
;
692 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
694 if (haddr
< vma
->vm_start
|| haddr
+ HPAGE_PMD_SIZE
> vma
->vm_end
)
695 return VM_FAULT_FALLBACK
;
696 if (unlikely(anon_vma_prepare(vma
)))
698 if (unlikely(khugepaged_enter(vma
, vma
->vm_flags
)))
700 if (!(vmf
->flags
& FAULT_FLAG_WRITE
) &&
701 !mm_forbids_zeropage(vma
->vm_mm
) &&
702 transparent_hugepage_use_zero_page()) {
704 struct page
*zero_page
;
707 pgtable
= pte_alloc_one(vma
->vm_mm
);
708 if (unlikely(!pgtable
))
710 zero_page
= mm_get_huge_zero_page(vma
->vm_mm
);
711 if (unlikely(!zero_page
)) {
712 pte_free(vma
->vm_mm
, pgtable
);
713 count_vm_event(THP_FAULT_FALLBACK
);
714 return VM_FAULT_FALLBACK
;
716 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
719 if (pmd_none(*vmf
->pmd
)) {
720 ret
= check_stable_address_space(vma
->vm_mm
);
722 spin_unlock(vmf
->ptl
);
723 } else if (userfaultfd_missing(vma
)) {
724 spin_unlock(vmf
->ptl
);
725 ret
= handle_userfault(vmf
, VM_UFFD_MISSING
);
726 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
728 set_huge_zero_page(pgtable
, vma
->vm_mm
, vma
,
729 haddr
, vmf
->pmd
, zero_page
);
730 spin_unlock(vmf
->ptl
);
734 spin_unlock(vmf
->ptl
);
736 pte_free(vma
->vm_mm
, pgtable
);
739 gfp
= alloc_hugepage_direct_gfpmask(vma
);
740 page
= alloc_hugepage_vma(gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
741 if (unlikely(!page
)) {
742 count_vm_event(THP_FAULT_FALLBACK
);
743 return VM_FAULT_FALLBACK
;
745 prep_transhuge_page(page
);
746 return __do_huge_pmd_anonymous_page(vmf
, page
, gfp
);
749 static void insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
750 pmd_t
*pmd
, pfn_t pfn
, pgprot_t prot
, bool write
,
753 struct mm_struct
*mm
= vma
->vm_mm
;
757 ptl
= pmd_lock(mm
, pmd
);
758 if (!pmd_none(*pmd
)) {
760 if (pmd_pfn(*pmd
) != pfn_t_to_pfn(pfn
)) {
761 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd
));
764 entry
= pmd_mkyoung(*pmd
);
765 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
766 if (pmdp_set_access_flags(vma
, addr
, pmd
, entry
, 1))
767 update_mmu_cache_pmd(vma
, addr
, pmd
);
773 entry
= pmd_mkhuge(pfn_t_pmd(pfn
, prot
));
774 if (pfn_t_devmap(pfn
))
775 entry
= pmd_mkdevmap(entry
);
777 entry
= pmd_mkyoung(pmd_mkdirty(entry
));
778 entry
= maybe_pmd_mkwrite(entry
, vma
);
782 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
787 set_pmd_at(mm
, addr
, pmd
, entry
);
788 update_mmu_cache_pmd(vma
, addr
, pmd
);
793 pte_free(mm
, pgtable
);
796 vm_fault_t
vmf_insert_pfn_pmd(struct vm_fault
*vmf
, pfn_t pfn
, bool write
)
798 unsigned long addr
= vmf
->address
& PMD_MASK
;
799 struct vm_area_struct
*vma
= vmf
->vma
;
800 pgprot_t pgprot
= vma
->vm_page_prot
;
801 pgtable_t pgtable
= NULL
;
804 * If we had pmd_special, we could avoid all these restrictions,
805 * but we need to be consistent with PTEs and architectures that
806 * can't support a 'special' bit.
808 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) &&
810 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
811 (VM_PFNMAP
|VM_MIXEDMAP
));
812 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
814 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
815 return VM_FAULT_SIGBUS
;
817 if (arch_needs_pgtable_deposit()) {
818 pgtable
= pte_alloc_one(vma
->vm_mm
);
823 track_pfn_insert(vma
, &pgprot
, pfn
);
825 insert_pfn_pmd(vma
, addr
, vmf
->pmd
, pfn
, pgprot
, write
, pgtable
);
826 return VM_FAULT_NOPAGE
;
828 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd
);
830 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
831 static pud_t
maybe_pud_mkwrite(pud_t pud
, struct vm_area_struct
*vma
)
833 if (likely(vma
->vm_flags
& VM_WRITE
))
834 pud
= pud_mkwrite(pud
);
838 static void insert_pfn_pud(struct vm_area_struct
*vma
, unsigned long addr
,
839 pud_t
*pud
, pfn_t pfn
, pgprot_t prot
, bool write
)
841 struct mm_struct
*mm
= vma
->vm_mm
;
845 ptl
= pud_lock(mm
, pud
);
846 if (!pud_none(*pud
)) {
848 if (pud_pfn(*pud
) != pfn_t_to_pfn(pfn
)) {
849 WARN_ON_ONCE(!is_huge_zero_pud(*pud
));
852 entry
= pud_mkyoung(*pud
);
853 entry
= maybe_pud_mkwrite(pud_mkdirty(entry
), vma
);
854 if (pudp_set_access_flags(vma
, addr
, pud
, entry
, 1))
855 update_mmu_cache_pud(vma
, addr
, pud
);
860 entry
= pud_mkhuge(pfn_t_pud(pfn
, prot
));
861 if (pfn_t_devmap(pfn
))
862 entry
= pud_mkdevmap(entry
);
864 entry
= pud_mkyoung(pud_mkdirty(entry
));
865 entry
= maybe_pud_mkwrite(entry
, vma
);
867 set_pud_at(mm
, addr
, pud
, entry
);
868 update_mmu_cache_pud(vma
, addr
, pud
);
874 vm_fault_t
vmf_insert_pfn_pud(struct vm_fault
*vmf
, pfn_t pfn
, bool write
)
876 unsigned long addr
= vmf
->address
& PUD_MASK
;
877 struct vm_area_struct
*vma
= vmf
->vma
;
878 pgprot_t pgprot
= vma
->vm_page_prot
;
881 * If we had pud_special, we could avoid all these restrictions,
882 * but we need to be consistent with PTEs and architectures that
883 * can't support a 'special' bit.
885 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) &&
887 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
888 (VM_PFNMAP
|VM_MIXEDMAP
));
889 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
891 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
892 return VM_FAULT_SIGBUS
;
894 track_pfn_insert(vma
, &pgprot
, pfn
);
896 insert_pfn_pud(vma
, addr
, vmf
->pud
, pfn
, pgprot
, write
);
897 return VM_FAULT_NOPAGE
;
899 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud
);
900 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
902 static void touch_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
903 pmd_t
*pmd
, int flags
)
907 _pmd
= pmd_mkyoung(*pmd
);
908 if (flags
& FOLL_WRITE
)
909 _pmd
= pmd_mkdirty(_pmd
);
910 if (pmdp_set_access_flags(vma
, addr
& HPAGE_PMD_MASK
,
911 pmd
, _pmd
, flags
& FOLL_WRITE
))
912 update_mmu_cache_pmd(vma
, addr
, pmd
);
915 struct page
*follow_devmap_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
916 pmd_t
*pmd
, int flags
, struct dev_pagemap
**pgmap
)
918 unsigned long pfn
= pmd_pfn(*pmd
);
919 struct mm_struct
*mm
= vma
->vm_mm
;
922 assert_spin_locked(pmd_lockptr(mm
, pmd
));
925 * When we COW a devmap PMD entry, we split it into PTEs, so we should
926 * not be in this function with `flags & FOLL_COW` set.
928 WARN_ONCE(flags
& FOLL_COW
, "mm: In follow_devmap_pmd with FOLL_COW set");
930 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
933 if (pmd_present(*pmd
) && pmd_devmap(*pmd
))
938 if (flags
& FOLL_TOUCH
)
939 touch_pmd(vma
, addr
, pmd
, flags
);
942 * device mapped pages can only be returned if the
943 * caller will manage the page reference count.
945 if (!(flags
& FOLL_GET
))
946 return ERR_PTR(-EEXIST
);
948 pfn
+= (addr
& ~PMD_MASK
) >> PAGE_SHIFT
;
949 *pgmap
= get_dev_pagemap(pfn
, *pgmap
);
951 return ERR_PTR(-EFAULT
);
952 page
= pfn_to_page(pfn
);
958 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
959 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
960 struct vm_area_struct
*vma
)
962 spinlock_t
*dst_ptl
, *src_ptl
;
963 struct page
*src_page
;
965 pgtable_t pgtable
= NULL
;
968 /* Skip if can be re-fill on fault */
969 if (!vma_is_anonymous(vma
))
972 pgtable
= pte_alloc_one(dst_mm
);
973 if (unlikely(!pgtable
))
976 dst_ptl
= pmd_lock(dst_mm
, dst_pmd
);
977 src_ptl
= pmd_lockptr(src_mm
, src_pmd
);
978 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
983 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
984 if (unlikely(is_swap_pmd(pmd
))) {
985 swp_entry_t entry
= pmd_to_swp_entry(pmd
);
987 VM_BUG_ON(!is_pmd_migration_entry(pmd
));
988 if (is_write_migration_entry(entry
)) {
989 make_migration_entry_read(&entry
);
990 pmd
= swp_entry_to_pmd(entry
);
991 if (pmd_swp_soft_dirty(*src_pmd
))
992 pmd
= pmd_swp_mksoft_dirty(pmd
);
993 set_pmd_at(src_mm
, addr
, src_pmd
, pmd
);
995 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
996 mm_inc_nr_ptes(dst_mm
);
997 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
998 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
1004 if (unlikely(!pmd_trans_huge(pmd
))) {
1005 pte_free(dst_mm
, pgtable
);
1009 * When page table lock is held, the huge zero pmd should not be
1010 * under splitting since we don't split the page itself, only pmd to
1013 if (is_huge_zero_pmd(pmd
)) {
1014 struct page
*zero_page
;
1016 * get_huge_zero_page() will never allocate a new page here,
1017 * since we already have a zero page to copy. It just takes a
1020 zero_page
= mm_get_huge_zero_page(dst_mm
);
1021 set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
1027 src_page
= pmd_page(pmd
);
1028 VM_BUG_ON_PAGE(!PageHead(src_page
), src_page
);
1030 page_dup_rmap(src_page
, true);
1031 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1032 mm_inc_nr_ptes(dst_mm
);
1033 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
1035 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
1036 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
1037 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
1041 spin_unlock(src_ptl
);
1042 spin_unlock(dst_ptl
);
1047 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1048 static void touch_pud(struct vm_area_struct
*vma
, unsigned long addr
,
1049 pud_t
*pud
, int flags
)
1053 _pud
= pud_mkyoung(*pud
);
1054 if (flags
& FOLL_WRITE
)
1055 _pud
= pud_mkdirty(_pud
);
1056 if (pudp_set_access_flags(vma
, addr
& HPAGE_PUD_MASK
,
1057 pud
, _pud
, flags
& FOLL_WRITE
))
1058 update_mmu_cache_pud(vma
, addr
, pud
);
1061 struct page
*follow_devmap_pud(struct vm_area_struct
*vma
, unsigned long addr
,
1062 pud_t
*pud
, int flags
, struct dev_pagemap
**pgmap
)
1064 unsigned long pfn
= pud_pfn(*pud
);
1065 struct mm_struct
*mm
= vma
->vm_mm
;
1068 assert_spin_locked(pud_lockptr(mm
, pud
));
1070 if (flags
& FOLL_WRITE
&& !pud_write(*pud
))
1073 if (pud_present(*pud
) && pud_devmap(*pud
))
1078 if (flags
& FOLL_TOUCH
)
1079 touch_pud(vma
, addr
, pud
, flags
);
1082 * device mapped pages can only be returned if the
1083 * caller will manage the page reference count.
1085 if (!(flags
& FOLL_GET
))
1086 return ERR_PTR(-EEXIST
);
1088 pfn
+= (addr
& ~PUD_MASK
) >> PAGE_SHIFT
;
1089 *pgmap
= get_dev_pagemap(pfn
, *pgmap
);
1091 return ERR_PTR(-EFAULT
);
1092 page
= pfn_to_page(pfn
);
1098 int copy_huge_pud(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1099 pud_t
*dst_pud
, pud_t
*src_pud
, unsigned long addr
,
1100 struct vm_area_struct
*vma
)
1102 spinlock_t
*dst_ptl
, *src_ptl
;
1106 dst_ptl
= pud_lock(dst_mm
, dst_pud
);
1107 src_ptl
= pud_lockptr(src_mm
, src_pud
);
1108 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
1112 if (unlikely(!pud_trans_huge(pud
) && !pud_devmap(pud
)))
1116 * When page table lock is held, the huge zero pud should not be
1117 * under splitting since we don't split the page itself, only pud to
1120 if (is_huge_zero_pud(pud
)) {
1121 /* No huge zero pud yet */
1124 pudp_set_wrprotect(src_mm
, addr
, src_pud
);
1125 pud
= pud_mkold(pud_wrprotect(pud
));
1126 set_pud_at(dst_mm
, addr
, dst_pud
, pud
);
1130 spin_unlock(src_ptl
);
1131 spin_unlock(dst_ptl
);
1135 void huge_pud_set_accessed(struct vm_fault
*vmf
, pud_t orig_pud
)
1138 unsigned long haddr
;
1139 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1141 vmf
->ptl
= pud_lock(vmf
->vma
->vm_mm
, vmf
->pud
);
1142 if (unlikely(!pud_same(*vmf
->pud
, orig_pud
)))
1145 entry
= pud_mkyoung(orig_pud
);
1147 entry
= pud_mkdirty(entry
);
1148 haddr
= vmf
->address
& HPAGE_PUD_MASK
;
1149 if (pudp_set_access_flags(vmf
->vma
, haddr
, vmf
->pud
, entry
, write
))
1150 update_mmu_cache_pud(vmf
->vma
, vmf
->address
, vmf
->pud
);
1153 spin_unlock(vmf
->ptl
);
1155 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1157 void huge_pmd_set_accessed(struct vm_fault
*vmf
, pmd_t orig_pmd
)
1160 unsigned long haddr
;
1161 bool write
= vmf
->flags
& FAULT_FLAG_WRITE
;
1163 vmf
->ptl
= pmd_lock(vmf
->vma
->vm_mm
, vmf
->pmd
);
1164 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1167 entry
= pmd_mkyoung(orig_pmd
);
1169 entry
= pmd_mkdirty(entry
);
1170 haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1171 if (pmdp_set_access_flags(vmf
->vma
, haddr
, vmf
->pmd
, entry
, write
))
1172 update_mmu_cache_pmd(vmf
->vma
, vmf
->address
, vmf
->pmd
);
1175 spin_unlock(vmf
->ptl
);
1178 static vm_fault_t
do_huge_pmd_wp_page_fallback(struct vm_fault
*vmf
,
1179 pmd_t orig_pmd
, struct page
*page
)
1181 struct vm_area_struct
*vma
= vmf
->vma
;
1182 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1183 struct mem_cgroup
*memcg
;
1188 struct page
**pages
;
1189 struct mmu_notifier_range range
;
1191 pages
= kmalloc_array(HPAGE_PMD_NR
, sizeof(struct page
*),
1193 if (unlikely(!pages
)) {
1194 ret
|= VM_FAULT_OOM
;
1198 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1199 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
, vma
,
1200 vmf
->address
, page_to_nid(page
));
1201 if (unlikely(!pages
[i
] ||
1202 mem_cgroup_try_charge_delay(pages
[i
], vma
->vm_mm
,
1203 GFP_KERNEL
, &memcg
, false))) {
1207 memcg
= (void *)page_private(pages
[i
]);
1208 set_page_private(pages
[i
], 0);
1209 mem_cgroup_cancel_charge(pages
[i
], memcg
,
1214 ret
|= VM_FAULT_OOM
;
1217 set_page_private(pages
[i
], (unsigned long)memcg
);
1220 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1221 copy_user_highpage(pages
[i
], page
+ i
,
1222 haddr
+ PAGE_SIZE
* i
, vma
);
1223 __SetPageUptodate(pages
[i
]);
1227 mmu_notifier_range_init(&range
, MMU_NOTIFY_UNMAP
, 0, vma
, vma
->vm_mm
,
1229 haddr
+ HPAGE_PMD_SIZE
);
1230 mmu_notifier_invalidate_range_start(&range
);
1232 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1233 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1234 goto out_free_pages
;
1235 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1238 * Leave pmd empty until pte is filled note we must notify here as
1239 * concurrent CPU thread might write to new page before the call to
1240 * mmu_notifier_invalidate_range_end() happens which can lead to a
1241 * device seeing memory write in different order than CPU.
1243 * See Documentation/vm/mmu_notifier.rst
1245 pmdp_huge_clear_flush_notify(vma
, haddr
, vmf
->pmd
);
1247 pgtable
= pgtable_trans_huge_withdraw(vma
->vm_mm
, vmf
->pmd
);
1248 pmd_populate(vma
->vm_mm
, &_pmd
, pgtable
);
1250 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1252 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1253 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1254 memcg
= (void *)page_private(pages
[i
]);
1255 set_page_private(pages
[i
], 0);
1256 page_add_new_anon_rmap(pages
[i
], vmf
->vma
, haddr
, false);
1257 mem_cgroup_commit_charge(pages
[i
], memcg
, false, false);
1258 lru_cache_add_active_or_unevictable(pages
[i
], vma
);
1259 vmf
->pte
= pte_offset_map(&_pmd
, haddr
);
1260 VM_BUG_ON(!pte_none(*vmf
->pte
));
1261 set_pte_at(vma
->vm_mm
, haddr
, vmf
->pte
, entry
);
1262 pte_unmap(vmf
->pte
);
1266 smp_wmb(); /* make pte visible before pmd */
1267 pmd_populate(vma
->vm_mm
, vmf
->pmd
, pgtable
);
1268 page_remove_rmap(page
, true);
1269 spin_unlock(vmf
->ptl
);
1272 * No need to double call mmu_notifier->invalidate_range() callback as
1273 * the above pmdp_huge_clear_flush_notify() did already call it.
1275 mmu_notifier_invalidate_range_only_end(&range
);
1277 ret
|= VM_FAULT_WRITE
;
1284 spin_unlock(vmf
->ptl
);
1285 mmu_notifier_invalidate_range_end(&range
);
1286 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1287 memcg
= (void *)page_private(pages
[i
]);
1288 set_page_private(pages
[i
], 0);
1289 mem_cgroup_cancel_charge(pages
[i
], memcg
, false);
1296 vm_fault_t
do_huge_pmd_wp_page(struct vm_fault
*vmf
, pmd_t orig_pmd
)
1298 struct vm_area_struct
*vma
= vmf
->vma
;
1299 struct page
*page
= NULL
, *new_page
;
1300 struct mem_cgroup
*memcg
;
1301 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1302 struct mmu_notifier_range range
;
1303 gfp_t huge_gfp
; /* for allocation and charge */
1306 vmf
->ptl
= pmd_lockptr(vma
->vm_mm
, vmf
->pmd
);
1307 VM_BUG_ON_VMA(!vma
->anon_vma
, vma
);
1308 if (is_huge_zero_pmd(orig_pmd
))
1310 spin_lock(vmf
->ptl
);
1311 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
)))
1314 page
= pmd_page(orig_pmd
);
1315 VM_BUG_ON_PAGE(!PageCompound(page
) || !PageHead(page
), page
);
1317 * We can only reuse the page if nobody else maps the huge page or it's
1320 if (!trylock_page(page
)) {
1322 spin_unlock(vmf
->ptl
);
1324 spin_lock(vmf
->ptl
);
1325 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
))) {
1332 if (reuse_swap_page(page
, NULL
)) {
1334 entry
= pmd_mkyoung(orig_pmd
);
1335 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1336 if (pmdp_set_access_flags(vma
, haddr
, vmf
->pmd
, entry
, 1))
1337 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1338 ret
|= VM_FAULT_WRITE
;
1344 spin_unlock(vmf
->ptl
);
1346 if (__transparent_hugepage_enabled(vma
) &&
1347 !transparent_hugepage_debug_cow()) {
1348 huge_gfp
= alloc_hugepage_direct_gfpmask(vma
);
1349 new_page
= alloc_hugepage_vma(huge_gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
1353 if (likely(new_page
)) {
1354 prep_transhuge_page(new_page
);
1357 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1358 ret
|= VM_FAULT_FALLBACK
;
1360 ret
= do_huge_pmd_wp_page_fallback(vmf
, orig_pmd
, page
);
1361 if (ret
& VM_FAULT_OOM
) {
1362 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1363 ret
|= VM_FAULT_FALLBACK
;
1367 count_vm_event(THP_FAULT_FALLBACK
);
1371 if (unlikely(mem_cgroup_try_charge_delay(new_page
, vma
->vm_mm
,
1372 huge_gfp
, &memcg
, true))) {
1374 split_huge_pmd(vma
, vmf
->pmd
, vmf
->address
);
1377 ret
|= VM_FAULT_FALLBACK
;
1378 count_vm_event(THP_FAULT_FALLBACK
);
1382 count_vm_event(THP_FAULT_ALLOC
);
1383 count_memcg_events(memcg
, THP_FAULT_ALLOC
, 1);
1386 clear_huge_page(new_page
, vmf
->address
, HPAGE_PMD_NR
);
1388 copy_user_huge_page(new_page
, page
, vmf
->address
,
1390 __SetPageUptodate(new_page
);
1392 mmu_notifier_range_init(&range
, MMU_NOTIFY_UNMAP
, 0, vma
, vma
->vm_mm
,
1394 haddr
+ HPAGE_PMD_SIZE
);
1395 mmu_notifier_invalidate_range_start(&range
);
1397 spin_lock(vmf
->ptl
);
1400 if (unlikely(!pmd_same(*vmf
->pmd
, orig_pmd
))) {
1401 spin_unlock(vmf
->ptl
);
1402 mem_cgroup_cancel_charge(new_page
, memcg
, true);
1407 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
1408 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1409 pmdp_huge_clear_flush_notify(vma
, haddr
, vmf
->pmd
);
1410 page_add_new_anon_rmap(new_page
, vma
, haddr
, true);
1411 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
1412 lru_cache_add_active_or_unevictable(new_page
, vma
);
1413 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, entry
);
1414 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1416 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1418 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1419 page_remove_rmap(page
, true);
1422 ret
|= VM_FAULT_WRITE
;
1424 spin_unlock(vmf
->ptl
);
1427 * No need to double call mmu_notifier->invalidate_range() callback as
1428 * the above pmdp_huge_clear_flush_notify() did already call it.
1430 mmu_notifier_invalidate_range_only_end(&range
);
1434 spin_unlock(vmf
->ptl
);
1439 * FOLL_FORCE can write to even unwritable pmd's, but only
1440 * after we've gone through a COW cycle and they are dirty.
1442 static inline bool can_follow_write_pmd(pmd_t pmd
, unsigned int flags
)
1444 return pmd_write(pmd
) ||
1445 ((flags
& FOLL_FORCE
) && (flags
& FOLL_COW
) && pmd_dirty(pmd
));
1448 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1453 struct mm_struct
*mm
= vma
->vm_mm
;
1454 struct page
*page
= NULL
;
1456 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1458 if (flags
& FOLL_WRITE
&& !can_follow_write_pmd(*pmd
, flags
))
1461 /* Avoid dumping huge zero page */
1462 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1463 return ERR_PTR(-EFAULT
);
1465 /* Full NUMA hinting faults to serialise migration in fault paths */
1466 if ((flags
& FOLL_NUMA
) && pmd_protnone(*pmd
))
1469 page
= pmd_page(*pmd
);
1470 VM_BUG_ON_PAGE(!PageHead(page
) && !is_zone_device_page(page
), page
);
1471 if (flags
& FOLL_TOUCH
)
1472 touch_pmd(vma
, addr
, pmd
, flags
);
1473 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1475 * We don't mlock() pte-mapped THPs. This way we can avoid
1476 * leaking mlocked pages into non-VM_LOCKED VMAs.
1480 * In most cases the pmd is the only mapping of the page as we
1481 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1482 * writable private mappings in populate_vma_page_range().
1484 * The only scenario when we have the page shared here is if we
1485 * mlocking read-only mapping shared over fork(). We skip
1486 * mlocking such pages.
1490 * We can expect PageDoubleMap() to be stable under page lock:
1491 * for file pages we set it in page_add_file_rmap(), which
1492 * requires page to be locked.
1495 if (PageAnon(page
) && compound_mapcount(page
) != 1)
1497 if (PageDoubleMap(page
) || !page
->mapping
)
1499 if (!trylock_page(page
))
1502 if (page
->mapping
&& !PageDoubleMap(page
))
1503 mlock_vma_page(page
);
1507 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1508 VM_BUG_ON_PAGE(!PageCompound(page
) && !is_zone_device_page(page
), page
);
1509 if (flags
& FOLL_GET
)
1516 /* NUMA hinting page fault entry point for trans huge pmds */
1517 vm_fault_t
do_huge_pmd_numa_page(struct vm_fault
*vmf
, pmd_t pmd
)
1519 struct vm_area_struct
*vma
= vmf
->vma
;
1520 struct anon_vma
*anon_vma
= NULL
;
1522 unsigned long haddr
= vmf
->address
& HPAGE_PMD_MASK
;
1523 int page_nid
= NUMA_NO_NODE
, this_nid
= numa_node_id();
1524 int target_nid
, last_cpupid
= -1;
1526 bool migrated
= false;
1530 vmf
->ptl
= pmd_lock(vma
->vm_mm
, vmf
->pmd
);
1531 if (unlikely(!pmd_same(pmd
, *vmf
->pmd
)))
1535 * If there are potential migrations, wait for completion and retry
1536 * without disrupting NUMA hinting information. Do not relock and
1537 * check_same as the page may no longer be mapped.
1539 if (unlikely(pmd_trans_migrating(*vmf
->pmd
))) {
1540 page
= pmd_page(*vmf
->pmd
);
1541 if (!get_page_unless_zero(page
))
1543 spin_unlock(vmf
->ptl
);
1544 put_and_wait_on_page_locked(page
);
1548 page
= pmd_page(pmd
);
1549 BUG_ON(is_huge_zero_page(page
));
1550 page_nid
= page_to_nid(page
);
1551 last_cpupid
= page_cpupid_last(page
);
1552 count_vm_numa_event(NUMA_HINT_FAULTS
);
1553 if (page_nid
== this_nid
) {
1554 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
1555 flags
|= TNF_FAULT_LOCAL
;
1558 /* See similar comment in do_numa_page for explanation */
1559 if (!pmd_savedwrite(pmd
))
1560 flags
|= TNF_NO_GROUP
;
1563 * Acquire the page lock to serialise THP migrations but avoid dropping
1564 * page_table_lock if at all possible
1566 page_locked
= trylock_page(page
);
1567 target_nid
= mpol_misplaced(page
, vma
, haddr
);
1568 if (target_nid
== NUMA_NO_NODE
) {
1569 /* If the page was locked, there are no parallel migrations */
1574 /* Migration could have started since the pmd_trans_migrating check */
1576 page_nid
= NUMA_NO_NODE
;
1577 if (!get_page_unless_zero(page
))
1579 spin_unlock(vmf
->ptl
);
1580 put_and_wait_on_page_locked(page
);
1585 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1586 * to serialises splits
1589 spin_unlock(vmf
->ptl
);
1590 anon_vma
= page_lock_anon_vma_read(page
);
1592 /* Confirm the PMD did not change while page_table_lock was released */
1593 spin_lock(vmf
->ptl
);
1594 if (unlikely(!pmd_same(pmd
, *vmf
->pmd
))) {
1597 page_nid
= NUMA_NO_NODE
;
1601 /* Bail if we fail to protect against THP splits for any reason */
1602 if (unlikely(!anon_vma
)) {
1604 page_nid
= NUMA_NO_NODE
;
1609 * Since we took the NUMA fault, we must have observed the !accessible
1610 * bit. Make sure all other CPUs agree with that, to avoid them
1611 * modifying the page we're about to migrate.
1613 * Must be done under PTL such that we'll observe the relevant
1614 * inc_tlb_flush_pending().
1616 * We are not sure a pending tlb flush here is for a huge page
1617 * mapping or not. Hence use the tlb range variant
1619 if (mm_tlb_flush_pending(vma
->vm_mm
)) {
1620 flush_tlb_range(vma
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
1622 * change_huge_pmd() released the pmd lock before
1623 * invalidating the secondary MMUs sharing the primary
1624 * MMU pagetables (with ->invalidate_range()). The
1625 * mmu_notifier_invalidate_range_end() (which
1626 * internally calls ->invalidate_range()) in
1627 * change_pmd_range() will run after us, so we can't
1628 * rely on it here and we need an explicit invalidate.
1630 mmu_notifier_invalidate_range(vma
->vm_mm
, haddr
,
1631 haddr
+ HPAGE_PMD_SIZE
);
1635 * Migrate the THP to the requested node, returns with page unlocked
1636 * and access rights restored.
1638 spin_unlock(vmf
->ptl
);
1640 migrated
= migrate_misplaced_transhuge_page(vma
->vm_mm
, vma
,
1641 vmf
->pmd
, pmd
, vmf
->address
, page
, target_nid
);
1643 flags
|= TNF_MIGRATED
;
1644 page_nid
= target_nid
;
1646 flags
|= TNF_MIGRATE_FAIL
;
1650 BUG_ON(!PageLocked(page
));
1651 was_writable
= pmd_savedwrite(pmd
);
1652 pmd
= pmd_modify(pmd
, vma
->vm_page_prot
);
1653 pmd
= pmd_mkyoung(pmd
);
1655 pmd
= pmd_mkwrite(pmd
);
1656 set_pmd_at(vma
->vm_mm
, haddr
, vmf
->pmd
, pmd
);
1657 update_mmu_cache_pmd(vma
, vmf
->address
, vmf
->pmd
);
1660 spin_unlock(vmf
->ptl
);
1664 page_unlock_anon_vma_read(anon_vma
);
1666 if (page_nid
!= NUMA_NO_NODE
)
1667 task_numa_fault(last_cpupid
, page_nid
, HPAGE_PMD_NR
,
1674 * Return true if we do MADV_FREE successfully on entire pmd page.
1675 * Otherwise, return false.
1677 bool madvise_free_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1678 pmd_t
*pmd
, unsigned long addr
, unsigned long next
)
1683 struct mm_struct
*mm
= tlb
->mm
;
1686 tlb_change_page_size(tlb
, HPAGE_PMD_SIZE
);
1688 ptl
= pmd_trans_huge_lock(pmd
, vma
);
1693 if (is_huge_zero_pmd(orig_pmd
))
1696 if (unlikely(!pmd_present(orig_pmd
))) {
1697 VM_BUG_ON(thp_migration_supported() &&
1698 !is_pmd_migration_entry(orig_pmd
));
1702 page
= pmd_page(orig_pmd
);
1704 * If other processes are mapping this page, we couldn't discard
1705 * the page unless they all do MADV_FREE so let's skip the page.
1707 if (page_mapcount(page
) != 1)
1710 if (!trylock_page(page
))
1714 * If user want to discard part-pages of THP, split it so MADV_FREE
1715 * will deactivate only them.
1717 if (next
- addr
!= HPAGE_PMD_SIZE
) {
1720 split_huge_page(page
);
1726 if (PageDirty(page
))
1727 ClearPageDirty(page
);
1730 if (pmd_young(orig_pmd
) || pmd_dirty(orig_pmd
)) {
1731 pmdp_invalidate(vma
, addr
, pmd
);
1732 orig_pmd
= pmd_mkold(orig_pmd
);
1733 orig_pmd
= pmd_mkclean(orig_pmd
);
1735 set_pmd_at(mm
, addr
, pmd
, orig_pmd
);
1736 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1739 mark_page_lazyfree(page
);
1747 static inline void zap_deposited_table(struct mm_struct
*mm
, pmd_t
*pmd
)
1751 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1752 pte_free(mm
, pgtable
);
1756 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1757 pmd_t
*pmd
, unsigned long addr
)
1762 tlb_change_page_size(tlb
, HPAGE_PMD_SIZE
);
1764 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1768 * For architectures like ppc64 we look at deposited pgtable
1769 * when calling pmdp_huge_get_and_clear. So do the
1770 * pgtable_trans_huge_withdraw after finishing pmdp related
1773 orig_pmd
= pmdp_huge_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1775 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1776 if (vma_is_dax(vma
)) {
1777 if (arch_needs_pgtable_deposit())
1778 zap_deposited_table(tlb
->mm
, pmd
);
1780 if (is_huge_zero_pmd(orig_pmd
))
1781 tlb_remove_page_size(tlb
, pmd_page(orig_pmd
), HPAGE_PMD_SIZE
);
1782 } else if (is_huge_zero_pmd(orig_pmd
)) {
1783 zap_deposited_table(tlb
->mm
, pmd
);
1785 tlb_remove_page_size(tlb
, pmd_page(orig_pmd
), HPAGE_PMD_SIZE
);
1787 struct page
*page
= NULL
;
1788 int flush_needed
= 1;
1790 if (pmd_present(orig_pmd
)) {
1791 page
= pmd_page(orig_pmd
);
1792 page_remove_rmap(page
, true);
1793 VM_BUG_ON_PAGE(page_mapcount(page
) < 0, page
);
1794 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1795 } else if (thp_migration_supported()) {
1798 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd
));
1799 entry
= pmd_to_swp_entry(orig_pmd
);
1800 page
= pfn_to_page(swp_offset(entry
));
1803 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1805 if (PageAnon(page
)) {
1806 zap_deposited_table(tlb
->mm
, pmd
);
1807 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1809 if (arch_needs_pgtable_deposit())
1810 zap_deposited_table(tlb
->mm
, pmd
);
1811 add_mm_counter(tlb
->mm
, mm_counter_file(page
), -HPAGE_PMD_NR
);
1816 tlb_remove_page_size(tlb
, page
, HPAGE_PMD_SIZE
);
1821 #ifndef pmd_move_must_withdraw
1822 static inline int pmd_move_must_withdraw(spinlock_t
*new_pmd_ptl
,
1823 spinlock_t
*old_pmd_ptl
,
1824 struct vm_area_struct
*vma
)
1827 * With split pmd lock we also need to move preallocated
1828 * PTE page table if new_pmd is on different PMD page table.
1830 * We also don't deposit and withdraw tables for file pages.
1832 return (new_pmd_ptl
!= old_pmd_ptl
) && vma_is_anonymous(vma
);
1836 static pmd_t
move_soft_dirty_pmd(pmd_t pmd
)
1838 #ifdef CONFIG_MEM_SOFT_DIRTY
1839 if (unlikely(is_pmd_migration_entry(pmd
)))
1840 pmd
= pmd_swp_mksoft_dirty(pmd
);
1841 else if (pmd_present(pmd
))
1842 pmd
= pmd_mksoft_dirty(pmd
);
1847 bool move_huge_pmd(struct vm_area_struct
*vma
, unsigned long old_addr
,
1848 unsigned long new_addr
, unsigned long old_end
,
1849 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1851 spinlock_t
*old_ptl
, *new_ptl
;
1853 struct mm_struct
*mm
= vma
->vm_mm
;
1854 bool force_flush
= false;
1856 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1857 (new_addr
& ~HPAGE_PMD_MASK
) ||
1858 old_end
- old_addr
< HPAGE_PMD_SIZE
)
1862 * The destination pmd shouldn't be established, free_pgtables()
1863 * should have release it.
1865 if (WARN_ON(!pmd_none(*new_pmd
))) {
1866 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1871 * We don't have to worry about the ordering of src and dst
1872 * ptlocks because exclusive mmap_sem prevents deadlock.
1874 old_ptl
= __pmd_trans_huge_lock(old_pmd
, vma
);
1876 new_ptl
= pmd_lockptr(mm
, new_pmd
);
1877 if (new_ptl
!= old_ptl
)
1878 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
1879 pmd
= pmdp_huge_get_and_clear(mm
, old_addr
, old_pmd
);
1880 if (pmd_present(pmd
))
1882 VM_BUG_ON(!pmd_none(*new_pmd
));
1884 if (pmd_move_must_withdraw(new_ptl
, old_ptl
, vma
)) {
1886 pgtable
= pgtable_trans_huge_withdraw(mm
, old_pmd
);
1887 pgtable_trans_huge_deposit(mm
, new_pmd
, pgtable
);
1889 pmd
= move_soft_dirty_pmd(pmd
);
1890 set_pmd_at(mm
, new_addr
, new_pmd
, pmd
);
1892 flush_tlb_range(vma
, old_addr
, old_addr
+ PMD_SIZE
);
1893 if (new_ptl
!= old_ptl
)
1894 spin_unlock(new_ptl
);
1895 spin_unlock(old_ptl
);
1903 * - 0 if PMD could not be locked
1904 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1905 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1907 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1908 unsigned long addr
, pgprot_t newprot
, int prot_numa
)
1910 struct mm_struct
*mm
= vma
->vm_mm
;
1913 bool preserve_write
;
1916 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1920 preserve_write
= prot_numa
&& pmd_write(*pmd
);
1923 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1924 if (is_swap_pmd(*pmd
)) {
1925 swp_entry_t entry
= pmd_to_swp_entry(*pmd
);
1927 VM_BUG_ON(!is_pmd_migration_entry(*pmd
));
1928 if (is_write_migration_entry(entry
)) {
1931 * A protection check is difficult so
1932 * just be safe and disable write
1934 make_migration_entry_read(&entry
);
1935 newpmd
= swp_entry_to_pmd(entry
);
1936 if (pmd_swp_soft_dirty(*pmd
))
1937 newpmd
= pmd_swp_mksoft_dirty(newpmd
);
1938 set_pmd_at(mm
, addr
, pmd
, newpmd
);
1945 * Avoid trapping faults against the zero page. The read-only
1946 * data is likely to be read-cached on the local CPU and
1947 * local/remote hits to the zero page are not interesting.
1949 if (prot_numa
&& is_huge_zero_pmd(*pmd
))
1952 if (prot_numa
&& pmd_protnone(*pmd
))
1956 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1957 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1958 * which is also under down_read(mmap_sem):
1961 * change_huge_pmd(prot_numa=1)
1962 * pmdp_huge_get_and_clear_notify()
1963 * madvise_dontneed()
1965 * pmd_trans_huge(*pmd) == 0 (without ptl)
1968 * // pmd is re-established
1970 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1971 * which may break userspace.
1973 * pmdp_invalidate() is required to make sure we don't miss
1974 * dirty/young flags set by hardware.
1976 entry
= pmdp_invalidate(vma
, addr
, pmd
);
1978 entry
= pmd_modify(entry
, newprot
);
1980 entry
= pmd_mk_savedwrite(entry
);
1982 set_pmd_at(mm
, addr
, pmd
, entry
);
1983 BUG_ON(vma_is_anonymous(vma
) && !preserve_write
&& pmd_write(entry
));
1990 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1992 * Note that if it returns page table lock pointer, this routine returns without
1993 * unlocking page table lock. So callers must unlock it.
1995 spinlock_t
*__pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1998 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
1999 if (likely(is_swap_pmd(*pmd
) || pmd_trans_huge(*pmd
) ||
2007 * Returns true if a given pud maps a thp, false otherwise.
2009 * Note that if it returns true, this routine returns without unlocking page
2010 * table lock. So callers must unlock it.
2012 spinlock_t
*__pud_trans_huge_lock(pud_t
*pud
, struct vm_area_struct
*vma
)
2016 ptl
= pud_lock(vma
->vm_mm
, pud
);
2017 if (likely(pud_trans_huge(*pud
) || pud_devmap(*pud
)))
2023 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
2024 int zap_huge_pud(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
2025 pud_t
*pud
, unsigned long addr
)
2029 ptl
= __pud_trans_huge_lock(pud
, vma
);
2033 * For architectures like ppc64 we look at deposited pgtable
2034 * when calling pudp_huge_get_and_clear. So do the
2035 * pgtable_trans_huge_withdraw after finishing pudp related
2038 pudp_huge_get_and_clear_full(tlb
->mm
, addr
, pud
, tlb
->fullmm
);
2039 tlb_remove_pud_tlb_entry(tlb
, pud
, addr
);
2040 if (vma_is_dax(vma
)) {
2042 /* No zero page support yet */
2044 /* No support for anonymous PUD pages yet */
2050 static void __split_huge_pud_locked(struct vm_area_struct
*vma
, pud_t
*pud
,
2051 unsigned long haddr
)
2053 VM_BUG_ON(haddr
& ~HPAGE_PUD_MASK
);
2054 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
2055 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PUD_SIZE
, vma
);
2056 VM_BUG_ON(!pud_trans_huge(*pud
) && !pud_devmap(*pud
));
2058 count_vm_event(THP_SPLIT_PUD
);
2060 pudp_huge_clear_flush_notify(vma
, haddr
, pud
);
2063 void __split_huge_pud(struct vm_area_struct
*vma
, pud_t
*pud
,
2064 unsigned long address
)
2067 struct mmu_notifier_range range
;
2069 mmu_notifier_range_init(&range
, MMU_NOTIFY_UNMAP
, 0, vma
, vma
->vm_mm
,
2070 address
& HPAGE_PUD_MASK
,
2071 (address
& HPAGE_PUD_MASK
) + HPAGE_PUD_SIZE
);
2072 mmu_notifier_invalidate_range_start(&range
);
2073 ptl
= pud_lock(vma
->vm_mm
, pud
);
2074 if (unlikely(!pud_trans_huge(*pud
) && !pud_devmap(*pud
)))
2076 __split_huge_pud_locked(vma
, pud
, range
.start
);
2081 * No need to double call mmu_notifier->invalidate_range() callback as
2082 * the above pudp_huge_clear_flush_notify() did already call it.
2084 mmu_notifier_invalidate_range_only_end(&range
);
2086 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2088 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
2089 unsigned long haddr
, pmd_t
*pmd
)
2091 struct mm_struct
*mm
= vma
->vm_mm
;
2097 * Leave pmd empty until pte is filled note that it is fine to delay
2098 * notification until mmu_notifier_invalidate_range_end() as we are
2099 * replacing a zero pmd write protected page with a zero pte write
2102 * See Documentation/vm/mmu_notifier.rst
2104 pmdp_huge_clear_flush(vma
, haddr
, pmd
);
2106 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2107 pmd_populate(mm
, &_pmd
, pgtable
);
2109 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2111 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2112 entry
= pte_mkspecial(entry
);
2113 pte
= pte_offset_map(&_pmd
, haddr
);
2114 VM_BUG_ON(!pte_none(*pte
));
2115 set_pte_at(mm
, haddr
, pte
, entry
);
2118 smp_wmb(); /* make pte visible before pmd */
2119 pmd_populate(mm
, pmd
, pgtable
);
2122 static void __split_huge_pmd_locked(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2123 unsigned long haddr
, bool freeze
)
2125 struct mm_struct
*mm
= vma
->vm_mm
;
2128 pmd_t old_pmd
, _pmd
;
2129 bool young
, write
, soft_dirty
, pmd_migration
= false;
2133 VM_BUG_ON(haddr
& ~HPAGE_PMD_MASK
);
2134 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
2135 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
, vma
);
2136 VM_BUG_ON(!is_pmd_migration_entry(*pmd
) && !pmd_trans_huge(*pmd
)
2137 && !pmd_devmap(*pmd
));
2139 count_vm_event(THP_SPLIT_PMD
);
2141 if (!vma_is_anonymous(vma
)) {
2142 _pmd
= pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
2144 * We are going to unmap this huge page. So
2145 * just go ahead and zap it
2147 if (arch_needs_pgtable_deposit())
2148 zap_deposited_table(mm
, pmd
);
2149 if (vma_is_dax(vma
))
2151 page
= pmd_page(_pmd
);
2152 if (!PageDirty(page
) && pmd_dirty(_pmd
))
2153 set_page_dirty(page
);
2154 if (!PageReferenced(page
) && pmd_young(_pmd
))
2155 SetPageReferenced(page
);
2156 page_remove_rmap(page
, true);
2158 add_mm_counter(mm
, mm_counter_file(page
), -HPAGE_PMD_NR
);
2160 } else if (is_huge_zero_pmd(*pmd
)) {
2162 * FIXME: Do we want to invalidate secondary mmu by calling
2163 * mmu_notifier_invalidate_range() see comments below inside
2164 * __split_huge_pmd() ?
2166 * We are going from a zero huge page write protected to zero
2167 * small page also write protected so it does not seems useful
2168 * to invalidate secondary mmu at this time.
2170 return __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
2174 * Up to this point the pmd is present and huge and userland has the
2175 * whole access to the hugepage during the split (which happens in
2176 * place). If we overwrite the pmd with the not-huge version pointing
2177 * to the pte here (which of course we could if all CPUs were bug
2178 * free), userland could trigger a small page size TLB miss on the
2179 * small sized TLB while the hugepage TLB entry is still established in
2180 * the huge TLB. Some CPU doesn't like that.
2181 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2182 * 383 on page 93. Intel should be safe but is also warns that it's
2183 * only safe if the permission and cache attributes of the two entries
2184 * loaded in the two TLB is identical (which should be the case here).
2185 * But it is generally safer to never allow small and huge TLB entries
2186 * for the same virtual address to be loaded simultaneously. So instead
2187 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2188 * current pmd notpresent (atomically because here the pmd_trans_huge
2189 * must remain set at all times on the pmd until the split is complete
2190 * for this pmd), then we flush the SMP TLB and finally we write the
2191 * non-huge version of the pmd entry with pmd_populate.
2193 old_pmd
= pmdp_invalidate(vma
, haddr
, pmd
);
2195 pmd_migration
= is_pmd_migration_entry(old_pmd
);
2196 if (unlikely(pmd_migration
)) {
2199 entry
= pmd_to_swp_entry(old_pmd
);
2200 page
= pfn_to_page(swp_offset(entry
));
2201 write
= is_write_migration_entry(entry
);
2203 soft_dirty
= pmd_swp_soft_dirty(old_pmd
);
2205 page
= pmd_page(old_pmd
);
2206 if (pmd_dirty(old_pmd
))
2208 write
= pmd_write(old_pmd
);
2209 young
= pmd_young(old_pmd
);
2210 soft_dirty
= pmd_soft_dirty(old_pmd
);
2212 VM_BUG_ON_PAGE(!page_count(page
), page
);
2213 page_ref_add(page
, HPAGE_PMD_NR
- 1);
2216 * Withdraw the table only after we mark the pmd entry invalid.
2217 * This's critical for some architectures (Power).
2219 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2220 pmd_populate(mm
, &_pmd
, pgtable
);
2222 for (i
= 0, addr
= haddr
; i
< HPAGE_PMD_NR
; i
++, addr
+= PAGE_SIZE
) {
2225 * Note that NUMA hinting access restrictions are not
2226 * transferred to avoid any possibility of altering
2227 * permissions across VMAs.
2229 if (freeze
|| pmd_migration
) {
2230 swp_entry_t swp_entry
;
2231 swp_entry
= make_migration_entry(page
+ i
, write
);
2232 entry
= swp_entry_to_pte(swp_entry
);
2234 entry
= pte_swp_mksoft_dirty(entry
);
2236 entry
= mk_pte(page
+ i
, READ_ONCE(vma
->vm_page_prot
));
2237 entry
= maybe_mkwrite(entry
, vma
);
2239 entry
= pte_wrprotect(entry
);
2241 entry
= pte_mkold(entry
);
2243 entry
= pte_mksoft_dirty(entry
);
2245 pte
= pte_offset_map(&_pmd
, addr
);
2246 BUG_ON(!pte_none(*pte
));
2247 set_pte_at(mm
, addr
, pte
, entry
);
2248 atomic_inc(&page
[i
]._mapcount
);
2253 * Set PG_double_map before dropping compound_mapcount to avoid
2254 * false-negative page_mapped().
2256 if (compound_mapcount(page
) > 1 && !TestSetPageDoubleMap(page
)) {
2257 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2258 atomic_inc(&page
[i
]._mapcount
);
2261 if (atomic_add_negative(-1, compound_mapcount_ptr(page
))) {
2262 /* Last compound_mapcount is gone. */
2263 __dec_node_page_state(page
, NR_ANON_THPS
);
2264 if (TestClearPageDoubleMap(page
)) {
2265 /* No need in mapcount reference anymore */
2266 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2267 atomic_dec(&page
[i
]._mapcount
);
2271 smp_wmb(); /* make pte visible before pmd */
2272 pmd_populate(mm
, pmd
, pgtable
);
2275 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2276 page_remove_rmap(page
+ i
, false);
2282 void __split_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2283 unsigned long address
, bool freeze
, struct page
*page
)
2286 struct mmu_notifier_range range
;
2288 mmu_notifier_range_init(&range
, MMU_NOTIFY_UNMAP
, 0, vma
, vma
->vm_mm
,
2289 address
& HPAGE_PMD_MASK
,
2290 (address
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
);
2291 mmu_notifier_invalidate_range_start(&range
);
2292 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
2295 * If caller asks to setup a migration entries, we need a page to check
2296 * pmd against. Otherwise we can end up replacing wrong page.
2298 VM_BUG_ON(freeze
&& !page
);
2299 if (page
&& page
!= pmd_page(*pmd
))
2302 if (pmd_trans_huge(*pmd
)) {
2303 page
= pmd_page(*pmd
);
2304 if (PageMlocked(page
))
2305 clear_page_mlock(page
);
2306 } else if (!(pmd_devmap(*pmd
) || is_pmd_migration_entry(*pmd
)))
2308 __split_huge_pmd_locked(vma
, pmd
, range
.start
, freeze
);
2312 * No need to double call mmu_notifier->invalidate_range() callback.
2313 * They are 3 cases to consider inside __split_huge_pmd_locked():
2314 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2315 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2316 * fault will trigger a flush_notify before pointing to a new page
2317 * (it is fine if the secondary mmu keeps pointing to the old zero
2318 * page in the meantime)
2319 * 3) Split a huge pmd into pte pointing to the same page. No need
2320 * to invalidate secondary tlb entry they are all still valid.
2321 * any further changes to individual pte will notify. So no need
2322 * to call mmu_notifier->invalidate_range()
2324 mmu_notifier_invalidate_range_only_end(&range
);
2327 void split_huge_pmd_address(struct vm_area_struct
*vma
, unsigned long address
,
2328 bool freeze
, struct page
*page
)
2335 pgd
= pgd_offset(vma
->vm_mm
, address
);
2336 if (!pgd_present(*pgd
))
2339 p4d
= p4d_offset(pgd
, address
);
2340 if (!p4d_present(*p4d
))
2343 pud
= pud_offset(p4d
, address
);
2344 if (!pud_present(*pud
))
2347 pmd
= pmd_offset(pud
, address
);
2349 __split_huge_pmd(vma
, pmd
, address
, freeze
, page
);
2352 void vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2353 unsigned long start
,
2358 * If the new start address isn't hpage aligned and it could
2359 * previously contain an hugepage: check if we need to split
2362 if (start
& ~HPAGE_PMD_MASK
&&
2363 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2364 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2365 split_huge_pmd_address(vma
, start
, false, NULL
);
2368 * If the new end address isn't hpage aligned and it could
2369 * previously contain an hugepage: check if we need to split
2372 if (end
& ~HPAGE_PMD_MASK
&&
2373 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2374 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2375 split_huge_pmd_address(vma
, end
, false, NULL
);
2378 * If we're also updating the vma->vm_next->vm_start, if the new
2379 * vm_next->vm_start isn't page aligned and it could previously
2380 * contain an hugepage: check if we need to split an huge pmd.
2382 if (adjust_next
> 0) {
2383 struct vm_area_struct
*next
= vma
->vm_next
;
2384 unsigned long nstart
= next
->vm_start
;
2385 nstart
+= adjust_next
<< PAGE_SHIFT
;
2386 if (nstart
& ~HPAGE_PMD_MASK
&&
2387 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2388 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2389 split_huge_pmd_address(next
, nstart
, false, NULL
);
2393 static void unmap_page(struct page
*page
)
2395 enum ttu_flags ttu_flags
= TTU_IGNORE_MLOCK
| TTU_IGNORE_ACCESS
|
2396 TTU_RMAP_LOCKED
| TTU_SPLIT_HUGE_PMD
;
2399 VM_BUG_ON_PAGE(!PageHead(page
), page
);
2402 ttu_flags
|= TTU_SPLIT_FREEZE
;
2404 unmap_success
= try_to_unmap(page
, ttu_flags
);
2405 VM_BUG_ON_PAGE(!unmap_success
, page
);
2408 static void remap_page(struct page
*page
)
2411 if (PageTransHuge(page
)) {
2412 remove_migration_ptes(page
, page
, true);
2414 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2415 remove_migration_ptes(page
+ i
, page
+ i
, true);
2419 static void __split_huge_page_tail(struct page
*head
, int tail
,
2420 struct lruvec
*lruvec
, struct list_head
*list
)
2422 struct page
*page_tail
= head
+ tail
;
2424 VM_BUG_ON_PAGE(atomic_read(&page_tail
->_mapcount
) != -1, page_tail
);
2427 * Clone page flags before unfreezing refcount.
2429 * After successful get_page_unless_zero() might follow flags change,
2430 * for exmaple lock_page() which set PG_waiters.
2432 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
;
2433 page_tail
->flags
|= (head
->flags
&
2434 ((1L << PG_referenced
) |
2435 (1L << PG_swapbacked
) |
2436 (1L << PG_swapcache
) |
2437 (1L << PG_mlocked
) |
2438 (1L << PG_uptodate
) |
2440 (1L << PG_workingset
) |
2442 (1L << PG_unevictable
) |
2445 /* ->mapping in first tail page is compound_mapcount */
2446 VM_BUG_ON_PAGE(tail
> 2 && page_tail
->mapping
!= TAIL_MAPPING
,
2448 page_tail
->mapping
= head
->mapping
;
2449 page_tail
->index
= head
->index
+ tail
;
2451 /* Page flags must be visible before we make the page non-compound. */
2455 * Clear PageTail before unfreezing page refcount.
2457 * After successful get_page_unless_zero() might follow put_page()
2458 * which needs correct compound_head().
2460 clear_compound_head(page_tail
);
2462 /* Finally unfreeze refcount. Additional reference from page cache. */
2463 page_ref_unfreeze(page_tail
, 1 + (!PageAnon(head
) ||
2464 PageSwapCache(head
)));
2466 if (page_is_young(head
))
2467 set_page_young(page_tail
);
2468 if (page_is_idle(head
))
2469 set_page_idle(page_tail
);
2471 page_cpupid_xchg_last(page_tail
, page_cpupid_last(head
));
2474 * always add to the tail because some iterators expect new
2475 * pages to show after the currently processed elements - e.g.
2478 lru_add_page_tail(head
, page_tail
, lruvec
, list
);
2481 static void __split_huge_page(struct page
*page
, struct list_head
*list
,
2482 pgoff_t end
, unsigned long flags
)
2484 struct page
*head
= compound_head(page
);
2485 pg_data_t
*pgdat
= page_pgdat(head
);
2486 struct lruvec
*lruvec
;
2489 lruvec
= mem_cgroup_page_lruvec(head
, pgdat
);
2491 /* complete memcg works before add pages to LRU */
2492 mem_cgroup_split_huge_fixup(head
);
2494 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
2495 __split_huge_page_tail(head
, i
, lruvec
, list
);
2496 /* Some pages can be beyond i_size: drop them from page cache */
2497 if (head
[i
].index
>= end
) {
2498 ClearPageDirty(head
+ i
);
2499 __delete_from_page_cache(head
+ i
, NULL
);
2500 if (IS_ENABLED(CONFIG_SHMEM
) && PageSwapBacked(head
))
2501 shmem_uncharge(head
->mapping
->host
, 1);
2503 } else if (!PageAnon(page
)) {
2504 __xa_store(&head
->mapping
->i_pages
, head
[i
].index
,
2509 ClearPageCompound(head
);
2510 /* See comment in __split_huge_page_tail() */
2511 if (PageAnon(head
)) {
2512 /* Additional pin to swap cache */
2513 if (PageSwapCache(head
))
2514 page_ref_add(head
, 2);
2518 /* Additional pin to page cache */
2519 page_ref_add(head
, 2);
2520 xa_unlock(&head
->mapping
->i_pages
);
2523 spin_unlock_irqrestore(&pgdat
->lru_lock
, flags
);
2527 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2528 struct page
*subpage
= head
+ i
;
2529 if (subpage
== page
)
2531 unlock_page(subpage
);
2534 * Subpages may be freed if there wasn't any mapping
2535 * like if add_to_swap() is running on a lru page that
2536 * had its mapping zapped. And freeing these pages
2537 * requires taking the lru_lock so we do the put_page
2538 * of the tail pages after the split is complete.
2544 int total_mapcount(struct page
*page
)
2546 int i
, compound
, ret
;
2548 VM_BUG_ON_PAGE(PageTail(page
), page
);
2550 if (likely(!PageCompound(page
)))
2551 return atomic_read(&page
->_mapcount
) + 1;
2553 compound
= compound_mapcount(page
);
2557 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2558 ret
+= atomic_read(&page
[i
]._mapcount
) + 1;
2559 /* File pages has compound_mapcount included in _mapcount */
2560 if (!PageAnon(page
))
2561 return ret
- compound
* HPAGE_PMD_NR
;
2562 if (PageDoubleMap(page
))
2563 ret
-= HPAGE_PMD_NR
;
2568 * This calculates accurately how many mappings a transparent hugepage
2569 * has (unlike page_mapcount() which isn't fully accurate). This full
2570 * accuracy is primarily needed to know if copy-on-write faults can
2571 * reuse the page and change the mapping to read-write instead of
2572 * copying them. At the same time this returns the total_mapcount too.
2574 * The function returns the highest mapcount any one of the subpages
2575 * has. If the return value is one, even if different processes are
2576 * mapping different subpages of the transparent hugepage, they can
2577 * all reuse it, because each process is reusing a different subpage.
2579 * The total_mapcount is instead counting all virtual mappings of the
2580 * subpages. If the total_mapcount is equal to "one", it tells the
2581 * caller all mappings belong to the same "mm" and in turn the
2582 * anon_vma of the transparent hugepage can become the vma->anon_vma
2583 * local one as no other process may be mapping any of the subpages.
2585 * It would be more accurate to replace page_mapcount() with
2586 * page_trans_huge_mapcount(), however we only use
2587 * page_trans_huge_mapcount() in the copy-on-write faults where we
2588 * need full accuracy to avoid breaking page pinning, because
2589 * page_trans_huge_mapcount() is slower than page_mapcount().
2591 int page_trans_huge_mapcount(struct page
*page
, int *total_mapcount
)
2593 int i
, ret
, _total_mapcount
, mapcount
;
2595 /* hugetlbfs shouldn't call it */
2596 VM_BUG_ON_PAGE(PageHuge(page
), page
);
2598 if (likely(!PageTransCompound(page
))) {
2599 mapcount
= atomic_read(&page
->_mapcount
) + 1;
2601 *total_mapcount
= mapcount
;
2605 page
= compound_head(page
);
2607 _total_mapcount
= ret
= 0;
2608 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2609 mapcount
= atomic_read(&page
[i
]._mapcount
) + 1;
2610 ret
= max(ret
, mapcount
);
2611 _total_mapcount
+= mapcount
;
2613 if (PageDoubleMap(page
)) {
2615 _total_mapcount
-= HPAGE_PMD_NR
;
2617 mapcount
= compound_mapcount(page
);
2619 _total_mapcount
+= mapcount
;
2621 *total_mapcount
= _total_mapcount
;
2625 /* Racy check whether the huge page can be split */
2626 bool can_split_huge_page(struct page
*page
, int *pextra_pins
)
2630 /* Additional pins from page cache */
2632 extra_pins
= PageSwapCache(page
) ? HPAGE_PMD_NR
: 0;
2634 extra_pins
= HPAGE_PMD_NR
;
2636 *pextra_pins
= extra_pins
;
2637 return total_mapcount(page
) == page_count(page
) - extra_pins
- 1;
2641 * This function splits huge page into normal pages. @page can point to any
2642 * subpage of huge page to split. Split doesn't change the position of @page.
2644 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2645 * The huge page must be locked.
2647 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2649 * Both head page and tail pages will inherit mapping, flags, and so on from
2652 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2653 * they are not mapped.
2655 * Returns 0 if the hugepage is split successfully.
2656 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2659 int split_huge_page_to_list(struct page
*page
, struct list_head
*list
)
2661 struct page
*head
= compound_head(page
);
2662 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(head
));
2663 struct anon_vma
*anon_vma
= NULL
;
2664 struct address_space
*mapping
= NULL
;
2665 int count
, mapcount
, extra_pins
, ret
;
2667 unsigned long flags
;
2670 VM_BUG_ON_PAGE(is_huge_zero_page(page
), page
);
2671 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2672 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
2674 if (PageWriteback(page
))
2677 if (PageAnon(head
)) {
2679 * The caller does not necessarily hold an mmap_sem that would
2680 * prevent the anon_vma disappearing so we first we take a
2681 * reference to it and then lock the anon_vma for write. This
2682 * is similar to page_lock_anon_vma_read except the write lock
2683 * is taken to serialise against parallel split or collapse
2686 anon_vma
= page_get_anon_vma(head
);
2693 anon_vma_lock_write(anon_vma
);
2695 mapping
= head
->mapping
;
2704 i_mmap_lock_read(mapping
);
2707 *__split_huge_page() may need to trim off pages beyond EOF:
2708 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2709 * which cannot be nested inside the page tree lock. So note
2710 * end now: i_size itself may be changed at any moment, but
2711 * head page lock is good enough to serialize the trimming.
2713 end
= DIV_ROUND_UP(i_size_read(mapping
->host
), PAGE_SIZE
);
2717 * Racy check if we can split the page, before unmap_page() will
2720 if (!can_split_huge_page(head
, &extra_pins
)) {
2725 mlocked
= PageMlocked(page
);
2727 VM_BUG_ON_PAGE(compound_mapcount(head
), head
);
2729 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2733 /* prevent PageLRU to go away from under us, and freeze lru stats */
2734 spin_lock_irqsave(&pgdata
->lru_lock
, flags
);
2737 XA_STATE(xas
, &mapping
->i_pages
, page_index(head
));
2740 * Check if the head page is present in page cache.
2741 * We assume all tail are present too, if head is there.
2743 xa_lock(&mapping
->i_pages
);
2744 if (xas_load(&xas
) != head
)
2748 /* Prevent deferred_split_scan() touching ->_refcount */
2749 spin_lock(&pgdata
->split_queue_lock
);
2750 count
= page_count(head
);
2751 mapcount
= total_mapcount(head
);
2752 if (!mapcount
&& page_ref_freeze(head
, 1 + extra_pins
)) {
2753 if (!list_empty(page_deferred_list(head
))) {
2754 pgdata
->split_queue_len
--;
2755 list_del(page_deferred_list(head
));
2758 __dec_node_page_state(page
, NR_SHMEM_THPS
);
2759 spin_unlock(&pgdata
->split_queue_lock
);
2760 __split_huge_page(page
, list
, end
, flags
);
2761 if (PageSwapCache(head
)) {
2762 swp_entry_t entry
= { .val
= page_private(head
) };
2764 ret
= split_swap_cluster(entry
);
2768 if (IS_ENABLED(CONFIG_DEBUG_VM
) && mapcount
) {
2769 pr_alert("total_mapcount: %u, page_count(): %u\n",
2772 dump_page(head
, NULL
);
2773 dump_page(page
, "total_mapcount(head) > 0");
2776 spin_unlock(&pgdata
->split_queue_lock
);
2778 xa_unlock(&mapping
->i_pages
);
2779 spin_unlock_irqrestore(&pgdata
->lru_lock
, flags
);
2786 anon_vma_unlock_write(anon_vma
);
2787 put_anon_vma(anon_vma
);
2790 i_mmap_unlock_read(mapping
);
2792 count_vm_event(!ret
? THP_SPLIT_PAGE
: THP_SPLIT_PAGE_FAILED
);
2796 void free_transhuge_page(struct page
*page
)
2798 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
2799 unsigned long flags
;
2801 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2802 if (!list_empty(page_deferred_list(page
))) {
2803 pgdata
->split_queue_len
--;
2804 list_del(page_deferred_list(page
));
2806 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2807 free_compound_page(page
);
2810 void deferred_split_huge_page(struct page
*page
)
2812 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
2813 unsigned long flags
;
2815 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
2817 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2818 if (list_empty(page_deferred_list(page
))) {
2819 count_vm_event(THP_DEFERRED_SPLIT_PAGE
);
2820 list_add_tail(page_deferred_list(page
), &pgdata
->split_queue
);
2821 pgdata
->split_queue_len
++;
2823 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2826 static unsigned long deferred_split_count(struct shrinker
*shrink
,
2827 struct shrink_control
*sc
)
2829 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2830 return READ_ONCE(pgdata
->split_queue_len
);
2833 static unsigned long deferred_split_scan(struct shrinker
*shrink
,
2834 struct shrink_control
*sc
)
2836 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
2837 unsigned long flags
;
2838 LIST_HEAD(list
), *pos
, *next
;
2842 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2843 /* Take pin on all head pages to avoid freeing them under us */
2844 list_for_each_safe(pos
, next
, &pgdata
->split_queue
) {
2845 page
= list_entry((void *)pos
, struct page
, mapping
);
2846 page
= compound_head(page
);
2847 if (get_page_unless_zero(page
)) {
2848 list_move(page_deferred_list(page
), &list
);
2850 /* We lost race with put_compound_page() */
2851 list_del_init(page_deferred_list(page
));
2852 pgdata
->split_queue_len
--;
2854 if (!--sc
->nr_to_scan
)
2857 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2859 list_for_each_safe(pos
, next
, &list
) {
2860 page
= list_entry((void *)pos
, struct page
, mapping
);
2861 if (!trylock_page(page
))
2863 /* split_huge_page() removes page from list on success */
2864 if (!split_huge_page(page
))
2871 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
2872 list_splice_tail(&list
, &pgdata
->split_queue
);
2873 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
2876 * Stop shrinker if we didn't split any page, but the queue is empty.
2877 * This can happen if pages were freed under us.
2879 if (!split
&& list_empty(&pgdata
->split_queue
))
2884 static struct shrinker deferred_split_shrinker
= {
2885 .count_objects
= deferred_split_count
,
2886 .scan_objects
= deferred_split_scan
,
2887 .seeks
= DEFAULT_SEEKS
,
2888 .flags
= SHRINKER_NUMA_AWARE
,
2891 #ifdef CONFIG_DEBUG_FS
2892 static int split_huge_pages_set(void *data
, u64 val
)
2896 unsigned long pfn
, max_zone_pfn
;
2897 unsigned long total
= 0, split
= 0;
2902 for_each_populated_zone(zone
) {
2903 max_zone_pfn
= zone_end_pfn(zone
);
2904 for (pfn
= zone
->zone_start_pfn
; pfn
< max_zone_pfn
; pfn
++) {
2905 if (!pfn_valid(pfn
))
2908 page
= pfn_to_page(pfn
);
2909 if (!get_page_unless_zero(page
))
2912 if (zone
!= page_zone(page
))
2915 if (!PageHead(page
) || PageHuge(page
) || !PageLRU(page
))
2920 if (!split_huge_page(page
))
2928 pr_info("%lu of %lu THP split\n", split
, total
);
2932 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops
, NULL
, split_huge_pages_set
,
2935 static int __init
split_huge_pages_debugfs(void)
2937 debugfs_create_file("split_huge_pages", 0200, NULL
, NULL
,
2938 &split_huge_pages_fops
);
2941 late_initcall(split_huge_pages_debugfs
);
2944 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2945 void set_pmd_migration_entry(struct page_vma_mapped_walk
*pvmw
,
2948 struct vm_area_struct
*vma
= pvmw
->vma
;
2949 struct mm_struct
*mm
= vma
->vm_mm
;
2950 unsigned long address
= pvmw
->address
;
2955 if (!(pvmw
->pmd
&& !pvmw
->pte
))
2958 flush_cache_range(vma
, address
, address
+ HPAGE_PMD_SIZE
);
2959 pmdval
= *pvmw
->pmd
;
2960 pmdp_invalidate(vma
, address
, pvmw
->pmd
);
2961 if (pmd_dirty(pmdval
))
2962 set_page_dirty(page
);
2963 entry
= make_migration_entry(page
, pmd_write(pmdval
));
2964 pmdswp
= swp_entry_to_pmd(entry
);
2965 if (pmd_soft_dirty(pmdval
))
2966 pmdswp
= pmd_swp_mksoft_dirty(pmdswp
);
2967 set_pmd_at(mm
, address
, pvmw
->pmd
, pmdswp
);
2968 page_remove_rmap(page
, true);
2972 void remove_migration_pmd(struct page_vma_mapped_walk
*pvmw
, struct page
*new)
2974 struct vm_area_struct
*vma
= pvmw
->vma
;
2975 struct mm_struct
*mm
= vma
->vm_mm
;
2976 unsigned long address
= pvmw
->address
;
2977 unsigned long mmun_start
= address
& HPAGE_PMD_MASK
;
2981 if (!(pvmw
->pmd
&& !pvmw
->pte
))
2984 entry
= pmd_to_swp_entry(*pvmw
->pmd
);
2986 pmde
= pmd_mkold(mk_huge_pmd(new, vma
->vm_page_prot
));
2987 if (pmd_swp_soft_dirty(*pvmw
->pmd
))
2988 pmde
= pmd_mksoft_dirty(pmde
);
2989 if (is_write_migration_entry(entry
))
2990 pmde
= maybe_pmd_mkwrite(pmde
, vma
);
2992 flush_cache_range(vma
, mmun_start
, mmun_start
+ HPAGE_PMD_SIZE
);
2994 page_add_anon_rmap(new, vma
, mmun_start
, true);
2996 page_add_file_rmap(new, true);
2997 set_pmd_at(mm
, mmun_start
, pvmw
->pmd
, pmde
);
2998 if ((vma
->vm_flags
& VM_LOCKED
) && !PageDoubleMap(new))
2999 mlock_vma_page(new);
3000 update_mmu_cache_pmd(vma
, address
, pvmw
->pmd
);