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.
9 #include <linux/sched.h>
10 #include <linux/highmem.h>
11 #include <linux/hugetlb.h>
12 #include <linux/mmu_notifier.h>
13 #include <linux/rmap.h>
14 #include <linux/swap.h>
15 #include <linux/mm_inline.h>
16 #include <linux/kthread.h>
17 #include <linux/khugepaged.h>
18 #include <linux/freezer.h>
19 #include <linux/mman.h>
20 #include <linux/pagemap.h>
22 #include <asm/pgalloc.h>
26 * By default transparent hugepage support is enabled for all mappings
27 * and khugepaged scans all mappings. Defrag is only invoked by
28 * khugepaged hugepage allocations and by page faults inside
29 * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived
32 unsigned long transparent_hugepage_flags __read_mostly
=
33 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
34 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
36 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
37 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
39 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
)|
40 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
42 /* default scan 8*512 pte (or vmas) every 30 second */
43 static unsigned int khugepaged_pages_to_scan __read_mostly
= HPAGE_PMD_NR
*8;
44 static unsigned int khugepaged_pages_collapsed
;
45 static unsigned int khugepaged_full_scans
;
46 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly
= 10000;
47 /* during fragmentation poll the hugepage allocator once every minute */
48 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly
= 60000;
49 static struct task_struct
*khugepaged_thread __read_mostly
;
50 static DEFINE_MUTEX(khugepaged_mutex
);
51 static DEFINE_SPINLOCK(khugepaged_mm_lock
);
52 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait
);
54 * default collapse hugepages if there is at least one pte mapped like
55 * it would have happened if the vma was large enough during page
58 static unsigned int khugepaged_max_ptes_none __read_mostly
= HPAGE_PMD_NR
-1;
60 static int khugepaged(void *none
);
61 static int mm_slots_hash_init(void);
62 static int khugepaged_slab_init(void);
63 static void khugepaged_slab_free(void);
65 #define MM_SLOTS_HASH_HEADS 1024
66 static struct hlist_head
*mm_slots_hash __read_mostly
;
67 static struct kmem_cache
*mm_slot_cache __read_mostly
;
70 * struct mm_slot - hash lookup from mm to mm_slot
71 * @hash: hash collision list
72 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
73 * @mm: the mm that this information is valid for
76 struct hlist_node hash
;
77 struct list_head mm_node
;
82 * struct khugepaged_scan - cursor for scanning
83 * @mm_head: the head of the mm list to scan
84 * @mm_slot: the current mm_slot we are scanning
85 * @address: the next address inside that to be scanned
87 * There is only the one khugepaged_scan instance of this cursor structure.
89 struct khugepaged_scan
{
90 struct list_head mm_head
;
91 struct mm_slot
*mm_slot
;
92 unsigned long address
;
94 static struct khugepaged_scan khugepaged_scan
= {
95 .mm_head
= LIST_HEAD_INIT(khugepaged_scan
.mm_head
),
99 static int set_recommended_min_free_kbytes(void)
103 unsigned long recommended_min
;
104 extern int min_free_kbytes
;
106 if (!khugepaged_enabled())
109 for_each_populated_zone(zone
)
112 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
113 recommended_min
= pageblock_nr_pages
* nr_zones
* 2;
116 * Make sure that on average at least two pageblocks are almost free
117 * of another type, one for a migratetype to fall back to and a
118 * second to avoid subsequent fallbacks of other types There are 3
119 * MIGRATE_TYPES we care about.
121 recommended_min
+= pageblock_nr_pages
* nr_zones
*
122 MIGRATE_PCPTYPES
* MIGRATE_PCPTYPES
;
124 /* don't ever allow to reserve more than 5% of the lowmem */
125 recommended_min
= min(recommended_min
,
126 (unsigned long) nr_free_buffer_pages() / 20);
127 recommended_min
<<= (PAGE_SHIFT
-10);
129 if (recommended_min
> min_free_kbytes
)
130 min_free_kbytes
= recommended_min
;
131 setup_per_zone_wmarks();
134 late_initcall(set_recommended_min_free_kbytes
);
136 static int start_khugepaged(void)
139 if (khugepaged_enabled()) {
140 if (!khugepaged_thread
)
141 khugepaged_thread
= kthread_run(khugepaged
, NULL
,
143 if (unlikely(IS_ERR(khugepaged_thread
))) {
145 "khugepaged: kthread_run(khugepaged) failed\n");
146 err
= PTR_ERR(khugepaged_thread
);
147 khugepaged_thread
= NULL
;
150 if (!list_empty(&khugepaged_scan
.mm_head
))
151 wake_up_interruptible(&khugepaged_wait
);
153 set_recommended_min_free_kbytes();
154 } else if (khugepaged_thread
) {
155 kthread_stop(khugepaged_thread
);
156 khugepaged_thread
= NULL
;
164 static ssize_t
double_flag_show(struct kobject
*kobj
,
165 struct kobj_attribute
*attr
, char *buf
,
166 enum transparent_hugepage_flag enabled
,
167 enum transparent_hugepage_flag req_madv
)
169 if (test_bit(enabled
, &transparent_hugepage_flags
)) {
170 VM_BUG_ON(test_bit(req_madv
, &transparent_hugepage_flags
));
171 return sprintf(buf
, "[always] madvise never\n");
172 } else if (test_bit(req_madv
, &transparent_hugepage_flags
))
173 return sprintf(buf
, "always [madvise] never\n");
175 return sprintf(buf
, "always madvise [never]\n");
177 static ssize_t
double_flag_store(struct kobject
*kobj
,
178 struct kobj_attribute
*attr
,
179 const char *buf
, size_t count
,
180 enum transparent_hugepage_flag enabled
,
181 enum transparent_hugepage_flag req_madv
)
183 if (!memcmp("always", buf
,
184 min(sizeof("always")-1, count
))) {
185 set_bit(enabled
, &transparent_hugepage_flags
);
186 clear_bit(req_madv
, &transparent_hugepage_flags
);
187 } else if (!memcmp("madvise", buf
,
188 min(sizeof("madvise")-1, count
))) {
189 clear_bit(enabled
, &transparent_hugepage_flags
);
190 set_bit(req_madv
, &transparent_hugepage_flags
);
191 } else if (!memcmp("never", buf
,
192 min(sizeof("never")-1, count
))) {
193 clear_bit(enabled
, &transparent_hugepage_flags
);
194 clear_bit(req_madv
, &transparent_hugepage_flags
);
201 static ssize_t
enabled_show(struct kobject
*kobj
,
202 struct kobj_attribute
*attr
, char *buf
)
204 return double_flag_show(kobj
, attr
, buf
,
205 TRANSPARENT_HUGEPAGE_FLAG
,
206 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
208 static ssize_t
enabled_store(struct kobject
*kobj
,
209 struct kobj_attribute
*attr
,
210 const char *buf
, size_t count
)
214 ret
= double_flag_store(kobj
, attr
, buf
, count
,
215 TRANSPARENT_HUGEPAGE_FLAG
,
216 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
221 mutex_lock(&khugepaged_mutex
);
222 err
= start_khugepaged();
223 mutex_unlock(&khugepaged_mutex
);
231 static struct kobj_attribute enabled_attr
=
232 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
234 static ssize_t
single_flag_show(struct kobject
*kobj
,
235 struct kobj_attribute
*attr
, char *buf
,
236 enum transparent_hugepage_flag flag
)
238 return sprintf(buf
, "%d\n",
239 !!test_bit(flag
, &transparent_hugepage_flags
));
242 static ssize_t
single_flag_store(struct kobject
*kobj
,
243 struct kobj_attribute
*attr
,
244 const char *buf
, size_t count
,
245 enum transparent_hugepage_flag flag
)
250 ret
= kstrtoul(buf
, 10, &value
);
257 set_bit(flag
, &transparent_hugepage_flags
);
259 clear_bit(flag
, &transparent_hugepage_flags
);
265 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
266 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
267 * memory just to allocate one more hugepage.
269 static ssize_t
defrag_show(struct kobject
*kobj
,
270 struct kobj_attribute
*attr
, char *buf
)
272 return double_flag_show(kobj
, attr
, buf
,
273 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
274 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
276 static ssize_t
defrag_store(struct kobject
*kobj
,
277 struct kobj_attribute
*attr
,
278 const char *buf
, size_t count
)
280 return double_flag_store(kobj
, attr
, buf
, count
,
281 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
282 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
284 static struct kobj_attribute defrag_attr
=
285 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
287 #ifdef CONFIG_DEBUG_VM
288 static ssize_t
debug_cow_show(struct kobject
*kobj
,
289 struct kobj_attribute
*attr
, char *buf
)
291 return single_flag_show(kobj
, attr
, buf
,
292 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
294 static ssize_t
debug_cow_store(struct kobject
*kobj
,
295 struct kobj_attribute
*attr
,
296 const char *buf
, size_t count
)
298 return single_flag_store(kobj
, attr
, buf
, count
,
299 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
301 static struct kobj_attribute debug_cow_attr
=
302 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
303 #endif /* CONFIG_DEBUG_VM */
305 static struct attribute
*hugepage_attr
[] = {
308 #ifdef CONFIG_DEBUG_VM
309 &debug_cow_attr
.attr
,
314 static struct attribute_group hugepage_attr_group
= {
315 .attrs
= hugepage_attr
,
318 static ssize_t
scan_sleep_millisecs_show(struct kobject
*kobj
,
319 struct kobj_attribute
*attr
,
322 return sprintf(buf
, "%u\n", khugepaged_scan_sleep_millisecs
);
325 static ssize_t
scan_sleep_millisecs_store(struct kobject
*kobj
,
326 struct kobj_attribute
*attr
,
327 const char *buf
, size_t count
)
332 err
= strict_strtoul(buf
, 10, &msecs
);
333 if (err
|| msecs
> UINT_MAX
)
336 khugepaged_scan_sleep_millisecs
= msecs
;
337 wake_up_interruptible(&khugepaged_wait
);
341 static struct kobj_attribute scan_sleep_millisecs_attr
=
342 __ATTR(scan_sleep_millisecs
, 0644, scan_sleep_millisecs_show
,
343 scan_sleep_millisecs_store
);
345 static ssize_t
alloc_sleep_millisecs_show(struct kobject
*kobj
,
346 struct kobj_attribute
*attr
,
349 return sprintf(buf
, "%u\n", khugepaged_alloc_sleep_millisecs
);
352 static ssize_t
alloc_sleep_millisecs_store(struct kobject
*kobj
,
353 struct kobj_attribute
*attr
,
354 const char *buf
, size_t count
)
359 err
= strict_strtoul(buf
, 10, &msecs
);
360 if (err
|| msecs
> UINT_MAX
)
363 khugepaged_alloc_sleep_millisecs
= msecs
;
364 wake_up_interruptible(&khugepaged_wait
);
368 static struct kobj_attribute alloc_sleep_millisecs_attr
=
369 __ATTR(alloc_sleep_millisecs
, 0644, alloc_sleep_millisecs_show
,
370 alloc_sleep_millisecs_store
);
372 static ssize_t
pages_to_scan_show(struct kobject
*kobj
,
373 struct kobj_attribute
*attr
,
376 return sprintf(buf
, "%u\n", khugepaged_pages_to_scan
);
378 static ssize_t
pages_to_scan_store(struct kobject
*kobj
,
379 struct kobj_attribute
*attr
,
380 const char *buf
, size_t count
)
385 err
= strict_strtoul(buf
, 10, &pages
);
386 if (err
|| !pages
|| pages
> UINT_MAX
)
389 khugepaged_pages_to_scan
= pages
;
393 static struct kobj_attribute pages_to_scan_attr
=
394 __ATTR(pages_to_scan
, 0644, pages_to_scan_show
,
395 pages_to_scan_store
);
397 static ssize_t
pages_collapsed_show(struct kobject
*kobj
,
398 struct kobj_attribute
*attr
,
401 return sprintf(buf
, "%u\n", khugepaged_pages_collapsed
);
403 static struct kobj_attribute pages_collapsed_attr
=
404 __ATTR_RO(pages_collapsed
);
406 static ssize_t
full_scans_show(struct kobject
*kobj
,
407 struct kobj_attribute
*attr
,
410 return sprintf(buf
, "%u\n", khugepaged_full_scans
);
412 static struct kobj_attribute full_scans_attr
=
413 __ATTR_RO(full_scans
);
415 static ssize_t
khugepaged_defrag_show(struct kobject
*kobj
,
416 struct kobj_attribute
*attr
, char *buf
)
418 return single_flag_show(kobj
, attr
, buf
,
419 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
421 static ssize_t
khugepaged_defrag_store(struct kobject
*kobj
,
422 struct kobj_attribute
*attr
,
423 const char *buf
, size_t count
)
425 return single_flag_store(kobj
, attr
, buf
, count
,
426 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
428 static struct kobj_attribute khugepaged_defrag_attr
=
429 __ATTR(defrag
, 0644, khugepaged_defrag_show
,
430 khugepaged_defrag_store
);
433 * max_ptes_none controls if khugepaged should collapse hugepages over
434 * any unmapped ptes in turn potentially increasing the memory
435 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
436 * reduce the available free memory in the system as it
437 * runs. Increasing max_ptes_none will instead potentially reduce the
438 * free memory in the system during the khugepaged scan.
440 static ssize_t
khugepaged_max_ptes_none_show(struct kobject
*kobj
,
441 struct kobj_attribute
*attr
,
444 return sprintf(buf
, "%u\n", khugepaged_max_ptes_none
);
446 static ssize_t
khugepaged_max_ptes_none_store(struct kobject
*kobj
,
447 struct kobj_attribute
*attr
,
448 const char *buf
, size_t count
)
451 unsigned long max_ptes_none
;
453 err
= strict_strtoul(buf
, 10, &max_ptes_none
);
454 if (err
|| max_ptes_none
> HPAGE_PMD_NR
-1)
457 khugepaged_max_ptes_none
= max_ptes_none
;
461 static struct kobj_attribute khugepaged_max_ptes_none_attr
=
462 __ATTR(max_ptes_none
, 0644, khugepaged_max_ptes_none_show
,
463 khugepaged_max_ptes_none_store
);
465 static struct attribute
*khugepaged_attr
[] = {
466 &khugepaged_defrag_attr
.attr
,
467 &khugepaged_max_ptes_none_attr
.attr
,
468 &pages_to_scan_attr
.attr
,
469 &pages_collapsed_attr
.attr
,
470 &full_scans_attr
.attr
,
471 &scan_sleep_millisecs_attr
.attr
,
472 &alloc_sleep_millisecs_attr
.attr
,
476 static struct attribute_group khugepaged_attr_group
= {
477 .attrs
= khugepaged_attr
,
478 .name
= "khugepaged",
481 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
485 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
486 if (unlikely(!*hugepage_kobj
)) {
487 printk(KERN_ERR
"hugepage: failed kobject create\n");
491 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
493 printk(KERN_ERR
"hugepage: failed register hugeage group\n");
497 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
499 printk(KERN_ERR
"hugepage: failed register hugeage group\n");
500 goto remove_hp_group
;
506 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
508 kobject_put(*hugepage_kobj
);
512 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
514 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
515 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
516 kobject_put(hugepage_kobj
);
519 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
524 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
527 #endif /* CONFIG_SYSFS */
529 static int __init
hugepage_init(void)
532 struct kobject
*hugepage_kobj
;
534 if (!has_transparent_hugepage()) {
535 transparent_hugepage_flags
= 0;
539 err
= hugepage_init_sysfs(&hugepage_kobj
);
543 err
= khugepaged_slab_init();
547 err
= mm_slots_hash_init();
549 khugepaged_slab_free();
554 * By default disable transparent hugepages on smaller systems,
555 * where the extra memory used could hurt more than TLB overhead
556 * is likely to save. The admin can still enable it through /sys.
558 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
)))
559 transparent_hugepage_flags
= 0;
565 hugepage_exit_sysfs(hugepage_kobj
);
568 module_init(hugepage_init
)
570 static int __init
setup_transparent_hugepage(char *str
)
575 if (!strcmp(str
, "always")) {
576 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
577 &transparent_hugepage_flags
);
578 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
579 &transparent_hugepage_flags
);
581 } else if (!strcmp(str
, "madvise")) {
582 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
583 &transparent_hugepage_flags
);
584 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
585 &transparent_hugepage_flags
);
587 } else if (!strcmp(str
, "never")) {
588 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
589 &transparent_hugepage_flags
);
590 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
591 &transparent_hugepage_flags
);
597 "transparent_hugepage= cannot parse, ignored\n");
600 __setup("transparent_hugepage=", setup_transparent_hugepage
);
602 static inline pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
604 if (likely(vma
->vm_flags
& VM_WRITE
))
605 pmd
= pmd_mkwrite(pmd
);
609 static int __do_huge_pmd_anonymous_page(struct mm_struct
*mm
,
610 struct vm_area_struct
*vma
,
611 unsigned long haddr
, pmd_t
*pmd
,
616 VM_BUG_ON(!PageCompound(page
));
617 pgtable
= pte_alloc_one(mm
, haddr
);
618 if (unlikely(!pgtable
))
621 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
622 __SetPageUptodate(page
);
624 spin_lock(&mm
->page_table_lock
);
625 if (unlikely(!pmd_none(*pmd
))) {
626 spin_unlock(&mm
->page_table_lock
);
627 mem_cgroup_uncharge_page(page
);
629 pte_free(mm
, pgtable
);
632 entry
= mk_pmd(page
, vma
->vm_page_prot
);
633 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
634 entry
= pmd_mkhuge(entry
);
636 * The spinlocking to take the lru_lock inside
637 * page_add_new_anon_rmap() acts as a full memory
638 * barrier to be sure clear_huge_page writes become
639 * visible after the set_pmd_at() write.
641 page_add_new_anon_rmap(page
, vma
, haddr
);
642 set_pmd_at(mm
, haddr
, pmd
, entry
);
643 pgtable_trans_huge_deposit(mm
, pgtable
);
644 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
646 spin_unlock(&mm
->page_table_lock
);
652 static inline gfp_t
alloc_hugepage_gfpmask(int defrag
, gfp_t extra_gfp
)
654 return (GFP_TRANSHUGE
& ~(defrag
? 0 : __GFP_WAIT
)) | extra_gfp
;
657 static inline struct page
*alloc_hugepage_vma(int defrag
,
658 struct vm_area_struct
*vma
,
659 unsigned long haddr
, int nd
,
662 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag
, extra_gfp
),
663 HPAGE_PMD_ORDER
, vma
, haddr
, nd
);
667 static inline struct page
*alloc_hugepage(int defrag
)
669 return alloc_pages(alloc_hugepage_gfpmask(defrag
, 0),
674 int do_huge_pmd_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
675 unsigned long address
, pmd_t
*pmd
,
679 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
682 if (haddr
>= vma
->vm_start
&& haddr
+ HPAGE_PMD_SIZE
<= vma
->vm_end
) {
683 if (unlikely(anon_vma_prepare(vma
)))
685 if (unlikely(khugepaged_enter(vma
)))
687 page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
688 vma
, haddr
, numa_node_id(), 0);
689 if (unlikely(!page
)) {
690 count_vm_event(THP_FAULT_FALLBACK
);
693 count_vm_event(THP_FAULT_ALLOC
);
694 if (unlikely(mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
))) {
698 if (unlikely(__do_huge_pmd_anonymous_page(mm
, vma
, haddr
, pmd
,
700 mem_cgroup_uncharge_page(page
);
709 * Use __pte_alloc instead of pte_alloc_map, because we can't
710 * run pte_offset_map on the pmd, if an huge pmd could
711 * materialize from under us from a different thread.
713 if (unlikely(__pte_alloc(mm
, vma
, pmd
, address
)))
715 /* if an huge pmd materialized from under us just retry later */
716 if (unlikely(pmd_trans_huge(*pmd
)))
719 * A regular pmd is established and it can't morph into a huge pmd
720 * from under us anymore at this point because we hold the mmap_sem
721 * read mode and khugepaged takes it in write mode. So now it's
722 * safe to run pte_offset_map().
724 pte
= pte_offset_map(pmd
, address
);
725 return handle_pte_fault(mm
, vma
, address
, pte
, pmd
, flags
);
728 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
729 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
730 struct vm_area_struct
*vma
)
732 struct page
*src_page
;
738 pgtable
= pte_alloc_one(dst_mm
, addr
);
739 if (unlikely(!pgtable
))
742 spin_lock(&dst_mm
->page_table_lock
);
743 spin_lock_nested(&src_mm
->page_table_lock
, SINGLE_DEPTH_NESTING
);
747 if (unlikely(!pmd_trans_huge(pmd
))) {
748 pte_free(dst_mm
, pgtable
);
751 if (unlikely(pmd_trans_splitting(pmd
))) {
752 /* split huge page running from under us */
753 spin_unlock(&src_mm
->page_table_lock
);
754 spin_unlock(&dst_mm
->page_table_lock
);
755 pte_free(dst_mm
, pgtable
);
757 wait_split_huge_page(vma
->anon_vma
, src_pmd
); /* src_vma */
760 src_page
= pmd_page(pmd
);
761 VM_BUG_ON(!PageHead(src_page
));
763 page_dup_rmap(src_page
);
764 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
766 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
767 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
768 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
769 pgtable_trans_huge_deposit(dst_mm
, pgtable
);
774 spin_unlock(&src_mm
->page_table_lock
);
775 spin_unlock(&dst_mm
->page_table_lock
);
780 static int do_huge_pmd_wp_page_fallback(struct mm_struct
*mm
,
781 struct vm_area_struct
*vma
,
782 unsigned long address
,
783 pmd_t
*pmd
, pmd_t orig_pmd
,
791 unsigned long mmun_start
; /* For mmu_notifiers */
792 unsigned long mmun_end
; /* For mmu_notifiers */
794 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
796 if (unlikely(!pages
)) {
801 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
802 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
|
804 vma
, address
, page_to_nid(page
));
805 if (unlikely(!pages
[i
] ||
806 mem_cgroup_newpage_charge(pages
[i
], mm
,
810 mem_cgroup_uncharge_start();
812 mem_cgroup_uncharge_page(pages
[i
]);
815 mem_cgroup_uncharge_end();
822 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
823 copy_user_highpage(pages
[i
], page
+ i
,
824 haddr
+ PAGE_SIZE
* i
, vma
);
825 __SetPageUptodate(pages
[i
]);
830 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
831 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
833 spin_lock(&mm
->page_table_lock
);
834 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
836 VM_BUG_ON(!PageHead(page
));
838 pmdp_clear_flush(vma
, haddr
, pmd
);
839 /* leave pmd empty until pte is filled */
841 pgtable
= pgtable_trans_huge_withdraw(mm
);
842 pmd_populate(mm
, &_pmd
, pgtable
);
844 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
846 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
847 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
848 page_add_new_anon_rmap(pages
[i
], vma
, haddr
);
849 pte
= pte_offset_map(&_pmd
, haddr
);
850 VM_BUG_ON(!pte_none(*pte
));
851 set_pte_at(mm
, haddr
, pte
, entry
);
856 smp_wmb(); /* make pte visible before pmd */
857 pmd_populate(mm
, pmd
, pgtable
);
858 page_remove_rmap(page
);
859 spin_unlock(&mm
->page_table_lock
);
861 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
863 ret
|= VM_FAULT_WRITE
;
870 spin_unlock(&mm
->page_table_lock
);
871 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
872 mem_cgroup_uncharge_start();
873 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
874 mem_cgroup_uncharge_page(pages
[i
]);
877 mem_cgroup_uncharge_end();
882 int do_huge_pmd_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
883 unsigned long address
, pmd_t
*pmd
, pmd_t orig_pmd
)
886 struct page
*page
, *new_page
;
888 unsigned long mmun_start
; /* For mmu_notifiers */
889 unsigned long mmun_end
; /* For mmu_notifiers */
891 VM_BUG_ON(!vma
->anon_vma
);
892 spin_lock(&mm
->page_table_lock
);
893 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
896 page
= pmd_page(orig_pmd
);
897 VM_BUG_ON(!PageCompound(page
) || !PageHead(page
));
898 haddr
= address
& HPAGE_PMD_MASK
;
899 if (page_mapcount(page
) == 1) {
901 entry
= pmd_mkyoung(orig_pmd
);
902 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
903 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, 1))
904 update_mmu_cache_pmd(vma
, address
, pmd
);
905 ret
|= VM_FAULT_WRITE
;
909 spin_unlock(&mm
->page_table_lock
);
911 if (transparent_hugepage_enabled(vma
) &&
912 !transparent_hugepage_debug_cow())
913 new_page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
914 vma
, haddr
, numa_node_id(), 0);
918 if (unlikely(!new_page
)) {
919 count_vm_event(THP_FAULT_FALLBACK
);
920 ret
= do_huge_pmd_wp_page_fallback(mm
, vma
, address
,
921 pmd
, orig_pmd
, page
, haddr
);
922 if (ret
& VM_FAULT_OOM
)
923 split_huge_page(page
);
927 count_vm_event(THP_FAULT_ALLOC
);
929 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
))) {
931 split_huge_page(page
);
937 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
938 __SetPageUptodate(new_page
);
941 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
942 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
944 spin_lock(&mm
->page_table_lock
);
946 if (unlikely(!pmd_same(*pmd
, orig_pmd
))) {
947 spin_unlock(&mm
->page_table_lock
);
948 mem_cgroup_uncharge_page(new_page
);
953 VM_BUG_ON(!PageHead(page
));
954 entry
= mk_pmd(new_page
, vma
->vm_page_prot
);
955 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
956 entry
= pmd_mkhuge(entry
);
957 pmdp_clear_flush(vma
, haddr
, pmd
);
958 page_add_new_anon_rmap(new_page
, vma
, haddr
);
959 set_pmd_at(mm
, haddr
, pmd
, entry
);
960 update_mmu_cache_pmd(vma
, address
, pmd
);
961 page_remove_rmap(page
);
963 ret
|= VM_FAULT_WRITE
;
965 spin_unlock(&mm
->page_table_lock
);
967 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
971 spin_unlock(&mm
->page_table_lock
);
975 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
980 struct mm_struct
*mm
= vma
->vm_mm
;
981 struct page
*page
= NULL
;
983 assert_spin_locked(&mm
->page_table_lock
);
985 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
988 page
= pmd_page(*pmd
);
989 VM_BUG_ON(!PageHead(page
));
990 if (flags
& FOLL_TOUCH
) {
993 * We should set the dirty bit only for FOLL_WRITE but
994 * for now the dirty bit in the pmd is meaningless.
995 * And if the dirty bit will become meaningful and
996 * we'll only set it with FOLL_WRITE, an atomic
997 * set_bit will be required on the pmd to set the
998 * young bit, instead of the current set_pmd_at.
1000 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
1001 set_pmd_at(mm
, addr
& HPAGE_PMD_MASK
, pmd
, _pmd
);
1003 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1004 if (page
->mapping
&& trylock_page(page
)) {
1007 mlock_vma_page(page
);
1011 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1012 VM_BUG_ON(!PageCompound(page
));
1013 if (flags
& FOLL_GET
)
1014 get_page_foll(page
);
1020 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1021 pmd_t
*pmd
, unsigned long addr
)
1025 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1029 pgtable
= pgtable_trans_huge_withdraw(tlb
->mm
);
1030 orig_pmd
= pmdp_get_and_clear(tlb
->mm
, addr
, pmd
);
1031 page
= pmd_page(orig_pmd
);
1032 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1033 page_remove_rmap(page
);
1034 VM_BUG_ON(page_mapcount(page
) < 0);
1035 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1036 VM_BUG_ON(!PageHead(page
));
1038 spin_unlock(&tlb
->mm
->page_table_lock
);
1039 tlb_remove_page(tlb
, page
);
1040 pte_free(tlb
->mm
, pgtable
);
1046 int mincore_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1047 unsigned long addr
, unsigned long end
,
1052 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1054 * All logical pages in the range are present
1055 * if backed by a huge page.
1057 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1058 memset(vec
, 1, (end
- addr
) >> PAGE_SHIFT
);
1065 int move_huge_pmd(struct vm_area_struct
*vma
, struct vm_area_struct
*new_vma
,
1066 unsigned long old_addr
,
1067 unsigned long new_addr
, unsigned long old_end
,
1068 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1073 struct mm_struct
*mm
= vma
->vm_mm
;
1075 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1076 (new_addr
& ~HPAGE_PMD_MASK
) ||
1077 old_end
- old_addr
< HPAGE_PMD_SIZE
||
1078 (new_vma
->vm_flags
& VM_NOHUGEPAGE
))
1082 * The destination pmd shouldn't be established, free_pgtables()
1083 * should have release it.
1085 if (WARN_ON(!pmd_none(*new_pmd
))) {
1086 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1090 ret
= __pmd_trans_huge_lock(old_pmd
, vma
);
1092 pmd
= pmdp_get_and_clear(mm
, old_addr
, old_pmd
);
1093 VM_BUG_ON(!pmd_none(*new_pmd
));
1094 set_pmd_at(mm
, new_addr
, new_pmd
, pmd
);
1095 spin_unlock(&mm
->page_table_lock
);
1101 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1102 unsigned long addr
, pgprot_t newprot
)
1104 struct mm_struct
*mm
= vma
->vm_mm
;
1107 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1109 entry
= pmdp_get_and_clear(mm
, addr
, pmd
);
1110 entry
= pmd_modify(entry
, newprot
);
1111 set_pmd_at(mm
, addr
, pmd
, entry
);
1112 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1120 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1121 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1123 * Note that if it returns 1, this routine returns without unlocking page
1124 * table locks. So callers must unlock them.
1126 int __pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1128 spin_lock(&vma
->vm_mm
->page_table_lock
);
1129 if (likely(pmd_trans_huge(*pmd
))) {
1130 if (unlikely(pmd_trans_splitting(*pmd
))) {
1131 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1132 wait_split_huge_page(vma
->anon_vma
, pmd
);
1135 /* Thp mapped by 'pmd' is stable, so we can
1136 * handle it as it is. */
1140 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1144 pmd_t
*page_check_address_pmd(struct page
*page
,
1145 struct mm_struct
*mm
,
1146 unsigned long address
,
1147 enum page_check_address_pmd_flag flag
)
1149 pmd_t
*pmd
, *ret
= NULL
;
1151 if (address
& ~HPAGE_PMD_MASK
)
1154 pmd
= mm_find_pmd(mm
, address
);
1159 if (pmd_page(*pmd
) != page
)
1162 * split_vma() may create temporary aliased mappings. There is
1163 * no risk as long as all huge pmd are found and have their
1164 * splitting bit set before __split_huge_page_refcount
1165 * runs. Finding the same huge pmd more than once during the
1166 * same rmap walk is not a problem.
1168 if (flag
== PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
&&
1169 pmd_trans_splitting(*pmd
))
1171 if (pmd_trans_huge(*pmd
)) {
1172 VM_BUG_ON(flag
== PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
&&
1173 !pmd_trans_splitting(*pmd
));
1180 static int __split_huge_page_splitting(struct page
*page
,
1181 struct vm_area_struct
*vma
,
1182 unsigned long address
)
1184 struct mm_struct
*mm
= vma
->vm_mm
;
1187 /* For mmu_notifiers */
1188 const unsigned long mmun_start
= address
;
1189 const unsigned long mmun_end
= address
+ HPAGE_PMD_SIZE
;
1191 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1192 spin_lock(&mm
->page_table_lock
);
1193 pmd
= page_check_address_pmd(page
, mm
, address
,
1194 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
);
1197 * We can't temporarily set the pmd to null in order
1198 * to split it, the pmd must remain marked huge at all
1199 * times or the VM won't take the pmd_trans_huge paths
1200 * and it won't wait on the anon_vma->root->mutex to
1201 * serialize against split_huge_page*.
1203 pmdp_splitting_flush(vma
, address
, pmd
);
1206 spin_unlock(&mm
->page_table_lock
);
1207 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1212 static void __split_huge_page_refcount(struct page
*page
)
1215 struct zone
*zone
= page_zone(page
);
1216 struct lruvec
*lruvec
;
1219 /* prevent PageLRU to go away from under us, and freeze lru stats */
1220 spin_lock_irq(&zone
->lru_lock
);
1221 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
1223 compound_lock(page
);
1224 /* complete memcg works before add pages to LRU */
1225 mem_cgroup_split_huge_fixup(page
);
1227 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
1228 struct page
*page_tail
= page
+ i
;
1230 /* tail_page->_mapcount cannot change */
1231 BUG_ON(page_mapcount(page_tail
) < 0);
1232 tail_count
+= page_mapcount(page_tail
);
1233 /* check for overflow */
1234 BUG_ON(tail_count
< 0);
1235 BUG_ON(atomic_read(&page_tail
->_count
) != 0);
1237 * tail_page->_count is zero and not changing from
1238 * under us. But get_page_unless_zero() may be running
1239 * from under us on the tail_page. If we used
1240 * atomic_set() below instead of atomic_add(), we
1241 * would then run atomic_set() concurrently with
1242 * get_page_unless_zero(), and atomic_set() is
1243 * implemented in C not using locked ops. spin_unlock
1244 * on x86 sometime uses locked ops because of PPro
1245 * errata 66, 92, so unless somebody can guarantee
1246 * atomic_set() here would be safe on all archs (and
1247 * not only on x86), it's safer to use atomic_add().
1249 atomic_add(page_mapcount(page
) + page_mapcount(page_tail
) + 1,
1250 &page_tail
->_count
);
1252 /* after clearing PageTail the gup refcount can be released */
1256 * retain hwpoison flag of the poisoned tail page:
1257 * fix for the unsuitable process killed on Guest Machine(KVM)
1258 * by the memory-failure.
1260 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
| __PG_HWPOISON
;
1261 page_tail
->flags
|= (page
->flags
&
1262 ((1L << PG_referenced
) |
1263 (1L << PG_swapbacked
) |
1264 (1L << PG_mlocked
) |
1265 (1L << PG_uptodate
)));
1266 page_tail
->flags
|= (1L << PG_dirty
);
1268 /* clear PageTail before overwriting first_page */
1272 * __split_huge_page_splitting() already set the
1273 * splitting bit in all pmd that could map this
1274 * hugepage, that will ensure no CPU can alter the
1275 * mapcount on the head page. The mapcount is only
1276 * accounted in the head page and it has to be
1277 * transferred to all tail pages in the below code. So
1278 * for this code to be safe, the split the mapcount
1279 * can't change. But that doesn't mean userland can't
1280 * keep changing and reading the page contents while
1281 * we transfer the mapcount, so the pmd splitting
1282 * status is achieved setting a reserved bit in the
1283 * pmd, not by clearing the present bit.
1285 page_tail
->_mapcount
= page
->_mapcount
;
1287 BUG_ON(page_tail
->mapping
);
1288 page_tail
->mapping
= page
->mapping
;
1290 page_tail
->index
= page
->index
+ i
;
1292 BUG_ON(!PageAnon(page_tail
));
1293 BUG_ON(!PageUptodate(page_tail
));
1294 BUG_ON(!PageDirty(page_tail
));
1295 BUG_ON(!PageSwapBacked(page_tail
));
1297 lru_add_page_tail(page
, page_tail
, lruvec
);
1299 atomic_sub(tail_count
, &page
->_count
);
1300 BUG_ON(atomic_read(&page
->_count
) <= 0);
1302 __mod_zone_page_state(zone
, NR_ANON_TRANSPARENT_HUGEPAGES
, -1);
1303 __mod_zone_page_state(zone
, NR_ANON_PAGES
, HPAGE_PMD_NR
);
1305 ClearPageCompound(page
);
1306 compound_unlock(page
);
1307 spin_unlock_irq(&zone
->lru_lock
);
1309 for (i
= 1; i
< HPAGE_PMD_NR
; i
++) {
1310 struct page
*page_tail
= page
+ i
;
1311 BUG_ON(page_count(page_tail
) <= 0);
1313 * Tail pages may be freed if there wasn't any mapping
1314 * like if add_to_swap() is running on a lru page that
1315 * had its mapping zapped. And freeing these pages
1316 * requires taking the lru_lock so we do the put_page
1317 * of the tail pages after the split is complete.
1319 put_page(page_tail
);
1323 * Only the head page (now become a regular page) is required
1324 * to be pinned by the caller.
1326 BUG_ON(page_count(page
) <= 0);
1329 static int __split_huge_page_map(struct page
*page
,
1330 struct vm_area_struct
*vma
,
1331 unsigned long address
)
1333 struct mm_struct
*mm
= vma
->vm_mm
;
1337 unsigned long haddr
;
1339 spin_lock(&mm
->page_table_lock
);
1340 pmd
= page_check_address_pmd(page
, mm
, address
,
1341 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
);
1343 pgtable
= pgtable_trans_huge_withdraw(mm
);
1344 pmd_populate(mm
, &_pmd
, pgtable
);
1347 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1349 BUG_ON(PageCompound(page
+i
));
1350 entry
= mk_pte(page
+ i
, vma
->vm_page_prot
);
1351 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1352 if (!pmd_write(*pmd
))
1353 entry
= pte_wrprotect(entry
);
1355 BUG_ON(page_mapcount(page
) != 1);
1356 if (!pmd_young(*pmd
))
1357 entry
= pte_mkold(entry
);
1358 pte
= pte_offset_map(&_pmd
, haddr
);
1359 BUG_ON(!pte_none(*pte
));
1360 set_pte_at(mm
, haddr
, pte
, entry
);
1364 smp_wmb(); /* make pte visible before pmd */
1366 * Up to this point the pmd is present and huge and
1367 * userland has the whole access to the hugepage
1368 * during the split (which happens in place). If we
1369 * overwrite the pmd with the not-huge version
1370 * pointing to the pte here (which of course we could
1371 * if all CPUs were bug free), userland could trigger
1372 * a small page size TLB miss on the small sized TLB
1373 * while the hugepage TLB entry is still established
1374 * in the huge TLB. Some CPU doesn't like that. See
1375 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1376 * Erratum 383 on page 93. Intel should be safe but is
1377 * also warns that it's only safe if the permission
1378 * and cache attributes of the two entries loaded in
1379 * the two TLB is identical (which should be the case
1380 * here). But it is generally safer to never allow
1381 * small and huge TLB entries for the same virtual
1382 * address to be loaded simultaneously. So instead of
1383 * doing "pmd_populate(); flush_tlb_range();" we first
1384 * mark the current pmd notpresent (atomically because
1385 * here the pmd_trans_huge and pmd_trans_splitting
1386 * must remain set at all times on the pmd until the
1387 * split is complete for this pmd), then we flush the
1388 * SMP TLB and finally we write the non-huge version
1389 * of the pmd entry with pmd_populate.
1391 pmdp_invalidate(vma
, address
, pmd
);
1392 pmd_populate(mm
, pmd
, pgtable
);
1395 spin_unlock(&mm
->page_table_lock
);
1400 /* must be called with anon_vma->root->mutex hold */
1401 static void __split_huge_page(struct page
*page
,
1402 struct anon_vma
*anon_vma
)
1404 int mapcount
, mapcount2
;
1405 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
1406 struct anon_vma_chain
*avc
;
1408 BUG_ON(!PageHead(page
));
1409 BUG_ON(PageTail(page
));
1412 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1413 struct vm_area_struct
*vma
= avc
->vma
;
1414 unsigned long addr
= vma_address(page
, vma
);
1415 BUG_ON(is_vma_temporary_stack(vma
));
1416 mapcount
+= __split_huge_page_splitting(page
, vma
, addr
);
1419 * It is critical that new vmas are added to the tail of the
1420 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1421 * and establishes a child pmd before
1422 * __split_huge_page_splitting() freezes the parent pmd (so if
1423 * we fail to prevent copy_huge_pmd() from running until the
1424 * whole __split_huge_page() is complete), we will still see
1425 * the newly established pmd of the child later during the
1426 * walk, to be able to set it as pmd_trans_splitting too.
1428 if (mapcount
!= page_mapcount(page
))
1429 printk(KERN_ERR
"mapcount %d page_mapcount %d\n",
1430 mapcount
, page_mapcount(page
));
1431 BUG_ON(mapcount
!= page_mapcount(page
));
1433 __split_huge_page_refcount(page
);
1436 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1437 struct vm_area_struct
*vma
= avc
->vma
;
1438 unsigned long addr
= vma_address(page
, vma
);
1439 BUG_ON(is_vma_temporary_stack(vma
));
1440 mapcount2
+= __split_huge_page_map(page
, vma
, addr
);
1442 if (mapcount
!= mapcount2
)
1443 printk(KERN_ERR
"mapcount %d mapcount2 %d page_mapcount %d\n",
1444 mapcount
, mapcount2
, page_mapcount(page
));
1445 BUG_ON(mapcount
!= mapcount2
);
1448 int split_huge_page(struct page
*page
)
1450 struct anon_vma
*anon_vma
;
1453 BUG_ON(!PageAnon(page
));
1454 anon_vma
= page_lock_anon_vma(page
);
1458 if (!PageCompound(page
))
1461 BUG_ON(!PageSwapBacked(page
));
1462 __split_huge_page(page
, anon_vma
);
1463 count_vm_event(THP_SPLIT
);
1465 BUG_ON(PageCompound(page
));
1467 page_unlock_anon_vma(anon_vma
);
1472 #define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
1474 int hugepage_madvise(struct vm_area_struct
*vma
,
1475 unsigned long *vm_flags
, int advice
)
1477 struct mm_struct
*mm
= vma
->vm_mm
;
1482 * Be somewhat over-protective like KSM for now!
1484 if (*vm_flags
& (VM_HUGEPAGE
| VM_NO_THP
))
1486 if (mm
->def_flags
& VM_NOHUGEPAGE
)
1488 *vm_flags
&= ~VM_NOHUGEPAGE
;
1489 *vm_flags
|= VM_HUGEPAGE
;
1491 * If the vma become good for khugepaged to scan,
1492 * register it here without waiting a page fault that
1493 * may not happen any time soon.
1495 if (unlikely(khugepaged_enter_vma_merge(vma
)))
1498 case MADV_NOHUGEPAGE
:
1500 * Be somewhat over-protective like KSM for now!
1502 if (*vm_flags
& (VM_NOHUGEPAGE
| VM_NO_THP
))
1504 *vm_flags
&= ~VM_HUGEPAGE
;
1505 *vm_flags
|= VM_NOHUGEPAGE
;
1507 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1508 * this vma even if we leave the mm registered in khugepaged if
1509 * it got registered before VM_NOHUGEPAGE was set.
1517 static int __init
khugepaged_slab_init(void)
1519 mm_slot_cache
= kmem_cache_create("khugepaged_mm_slot",
1520 sizeof(struct mm_slot
),
1521 __alignof__(struct mm_slot
), 0, NULL
);
1528 static void __init
khugepaged_slab_free(void)
1530 kmem_cache_destroy(mm_slot_cache
);
1531 mm_slot_cache
= NULL
;
1534 static inline struct mm_slot
*alloc_mm_slot(void)
1536 if (!mm_slot_cache
) /* initialization failed */
1538 return kmem_cache_zalloc(mm_slot_cache
, GFP_KERNEL
);
1541 static inline void free_mm_slot(struct mm_slot
*mm_slot
)
1543 kmem_cache_free(mm_slot_cache
, mm_slot
);
1546 static int __init
mm_slots_hash_init(void)
1548 mm_slots_hash
= kzalloc(MM_SLOTS_HASH_HEADS
* sizeof(struct hlist_head
),
1556 static void __init
mm_slots_hash_free(void)
1558 kfree(mm_slots_hash
);
1559 mm_slots_hash
= NULL
;
1563 static struct mm_slot
*get_mm_slot(struct mm_struct
*mm
)
1565 struct mm_slot
*mm_slot
;
1566 struct hlist_head
*bucket
;
1567 struct hlist_node
*node
;
1569 bucket
= &mm_slots_hash
[((unsigned long)mm
/ sizeof(struct mm_struct
))
1570 % MM_SLOTS_HASH_HEADS
];
1571 hlist_for_each_entry(mm_slot
, node
, bucket
, hash
) {
1572 if (mm
== mm_slot
->mm
)
1578 static void insert_to_mm_slots_hash(struct mm_struct
*mm
,
1579 struct mm_slot
*mm_slot
)
1581 struct hlist_head
*bucket
;
1583 bucket
= &mm_slots_hash
[((unsigned long)mm
/ sizeof(struct mm_struct
))
1584 % MM_SLOTS_HASH_HEADS
];
1586 hlist_add_head(&mm_slot
->hash
, bucket
);
1589 static inline int khugepaged_test_exit(struct mm_struct
*mm
)
1591 return atomic_read(&mm
->mm_users
) == 0;
1594 int __khugepaged_enter(struct mm_struct
*mm
)
1596 struct mm_slot
*mm_slot
;
1599 mm_slot
= alloc_mm_slot();
1603 /* __khugepaged_exit() must not run from under us */
1604 VM_BUG_ON(khugepaged_test_exit(mm
));
1605 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE
, &mm
->flags
))) {
1606 free_mm_slot(mm_slot
);
1610 spin_lock(&khugepaged_mm_lock
);
1611 insert_to_mm_slots_hash(mm
, mm_slot
);
1613 * Insert just behind the scanning cursor, to let the area settle
1616 wakeup
= list_empty(&khugepaged_scan
.mm_head
);
1617 list_add_tail(&mm_slot
->mm_node
, &khugepaged_scan
.mm_head
);
1618 spin_unlock(&khugepaged_mm_lock
);
1620 atomic_inc(&mm
->mm_count
);
1622 wake_up_interruptible(&khugepaged_wait
);
1627 int khugepaged_enter_vma_merge(struct vm_area_struct
*vma
)
1629 unsigned long hstart
, hend
;
1632 * Not yet faulted in so we will register later in the
1633 * page fault if needed.
1637 /* khugepaged not yet working on file or special mappings */
1639 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
1640 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1641 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1643 return khugepaged_enter(vma
);
1647 void __khugepaged_exit(struct mm_struct
*mm
)
1649 struct mm_slot
*mm_slot
;
1652 spin_lock(&khugepaged_mm_lock
);
1653 mm_slot
= get_mm_slot(mm
);
1654 if (mm_slot
&& khugepaged_scan
.mm_slot
!= mm_slot
) {
1655 hlist_del(&mm_slot
->hash
);
1656 list_del(&mm_slot
->mm_node
);
1659 spin_unlock(&khugepaged_mm_lock
);
1662 clear_bit(MMF_VM_HUGEPAGE
, &mm
->flags
);
1663 free_mm_slot(mm_slot
);
1665 } else if (mm_slot
) {
1667 * This is required to serialize against
1668 * khugepaged_test_exit() (which is guaranteed to run
1669 * under mmap sem read mode). Stop here (after we
1670 * return all pagetables will be destroyed) until
1671 * khugepaged has finished working on the pagetables
1672 * under the mmap_sem.
1674 down_write(&mm
->mmap_sem
);
1675 up_write(&mm
->mmap_sem
);
1679 static void release_pte_page(struct page
*page
)
1681 /* 0 stands for page_is_file_cache(page) == false */
1682 dec_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1684 putback_lru_page(page
);
1687 static void release_pte_pages(pte_t
*pte
, pte_t
*_pte
)
1689 while (--_pte
>= pte
) {
1690 pte_t pteval
= *_pte
;
1691 if (!pte_none(pteval
))
1692 release_pte_page(pte_page(pteval
));
1696 static int __collapse_huge_page_isolate(struct vm_area_struct
*vma
,
1697 unsigned long address
,
1702 int referenced
= 0, none
= 0;
1703 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
1704 _pte
++, address
+= PAGE_SIZE
) {
1705 pte_t pteval
= *_pte
;
1706 if (pte_none(pteval
)) {
1707 if (++none
<= khugepaged_max_ptes_none
)
1712 if (!pte_present(pteval
) || !pte_write(pteval
))
1714 page
= vm_normal_page(vma
, address
, pteval
);
1715 if (unlikely(!page
))
1718 VM_BUG_ON(PageCompound(page
));
1719 BUG_ON(!PageAnon(page
));
1720 VM_BUG_ON(!PageSwapBacked(page
));
1722 /* cannot use mapcount: can't collapse if there's a gup pin */
1723 if (page_count(page
) != 1)
1726 * We can do it before isolate_lru_page because the
1727 * page can't be freed from under us. NOTE: PG_lock
1728 * is needed to serialize against split_huge_page
1729 * when invoked from the VM.
1731 if (!trylock_page(page
))
1734 * Isolate the page to avoid collapsing an hugepage
1735 * currently in use by the VM.
1737 if (isolate_lru_page(page
)) {
1741 /* 0 stands for page_is_file_cache(page) == false */
1742 inc_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1743 VM_BUG_ON(!PageLocked(page
));
1744 VM_BUG_ON(PageLRU(page
));
1746 /* If there is no mapped pte young don't collapse the page */
1747 if (pte_young(pteval
) || PageReferenced(page
) ||
1748 mmu_notifier_test_young(vma
->vm_mm
, address
))
1751 if (likely(referenced
))
1754 release_pte_pages(pte
, _pte
);
1758 static void __collapse_huge_page_copy(pte_t
*pte
, struct page
*page
,
1759 struct vm_area_struct
*vma
,
1760 unsigned long address
,
1764 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
; _pte
++) {
1765 pte_t pteval
= *_pte
;
1766 struct page
*src_page
;
1768 if (pte_none(pteval
)) {
1769 clear_user_highpage(page
, address
);
1770 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, 1);
1772 src_page
= pte_page(pteval
);
1773 copy_user_highpage(page
, src_page
, address
, vma
);
1774 VM_BUG_ON(page_mapcount(src_page
) != 1);
1775 release_pte_page(src_page
);
1777 * ptl mostly unnecessary, but preempt has to
1778 * be disabled to update the per-cpu stats
1779 * inside page_remove_rmap().
1783 * paravirt calls inside pte_clear here are
1786 pte_clear(vma
->vm_mm
, address
, _pte
);
1787 page_remove_rmap(src_page
);
1789 free_page_and_swap_cache(src_page
);
1792 address
+= PAGE_SIZE
;
1797 static void khugepaged_alloc_sleep(void)
1799 wait_event_freezable_timeout(khugepaged_wait
, false,
1800 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs
));
1804 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
1806 if (IS_ERR(*hpage
)) {
1812 khugepaged_alloc_sleep();
1813 } else if (*hpage
) {
1822 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
1823 struct vm_area_struct
*vma
, unsigned long address
,
1828 * Allocate the page while the vma is still valid and under
1829 * the mmap_sem read mode so there is no memory allocation
1830 * later when we take the mmap_sem in write mode. This is more
1831 * friendly behavior (OTOH it may actually hide bugs) to
1832 * filesystems in userland with daemons allocating memory in
1833 * the userland I/O paths. Allocating memory with the
1834 * mmap_sem in read mode is good idea also to allow greater
1837 *hpage
= alloc_hugepage_vma(khugepaged_defrag(), vma
, address
,
1838 node
, __GFP_OTHER_NODE
);
1841 * After allocating the hugepage, release the mmap_sem read lock in
1842 * preparation for taking it in write mode.
1844 up_read(&mm
->mmap_sem
);
1845 if (unlikely(!*hpage
)) {
1846 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
1847 *hpage
= ERR_PTR(-ENOMEM
);
1851 count_vm_event(THP_COLLAPSE_ALLOC
);
1855 static struct page
*khugepaged_alloc_hugepage(bool *wait
)
1860 hpage
= alloc_hugepage(khugepaged_defrag());
1862 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
1867 khugepaged_alloc_sleep();
1869 count_vm_event(THP_COLLAPSE_ALLOC
);
1870 } while (unlikely(!hpage
) && likely(khugepaged_enabled()));
1875 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
1878 *hpage
= khugepaged_alloc_hugepage(wait
);
1880 if (unlikely(!*hpage
))
1887 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
1888 struct vm_area_struct
*vma
, unsigned long address
,
1891 up_read(&mm
->mmap_sem
);
1897 static bool hugepage_vma_check(struct vm_area_struct
*vma
)
1899 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) && !khugepaged_always()) ||
1900 (vma
->vm_flags
& VM_NOHUGEPAGE
))
1903 if (!vma
->anon_vma
|| vma
->vm_ops
)
1905 if (is_vma_temporary_stack(vma
))
1907 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
1911 static void collapse_huge_page(struct mm_struct
*mm
,
1912 unsigned long address
,
1913 struct page
**hpage
,
1914 struct vm_area_struct
*vma
,
1920 struct page
*new_page
;
1923 unsigned long hstart
, hend
;
1924 unsigned long mmun_start
; /* For mmu_notifiers */
1925 unsigned long mmun_end
; /* For mmu_notifiers */
1927 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
1929 /* release the mmap_sem read lock. */
1930 new_page
= khugepaged_alloc_page(hpage
, mm
, vma
, address
, node
);
1934 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
)))
1938 * Prevent all access to pagetables with the exception of
1939 * gup_fast later hanlded by the ptep_clear_flush and the VM
1940 * handled by the anon_vma lock + PG_lock.
1942 down_write(&mm
->mmap_sem
);
1943 if (unlikely(khugepaged_test_exit(mm
)))
1946 vma
= find_vma(mm
, address
);
1947 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1948 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1949 if (address
< hstart
|| address
+ HPAGE_PMD_SIZE
> hend
)
1951 if (!hugepage_vma_check(vma
))
1953 pmd
= mm_find_pmd(mm
, address
);
1956 if (pmd_trans_huge(*pmd
))
1959 anon_vma_lock(vma
->anon_vma
);
1961 pte
= pte_offset_map(pmd
, address
);
1962 ptl
= pte_lockptr(mm
, pmd
);
1964 mmun_start
= address
;
1965 mmun_end
= address
+ HPAGE_PMD_SIZE
;
1966 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1967 spin_lock(&mm
->page_table_lock
); /* probably unnecessary */
1969 * After this gup_fast can't run anymore. This also removes
1970 * any huge TLB entry from the CPU so we won't allow
1971 * huge and small TLB entries for the same virtual address
1972 * to avoid the risk of CPU bugs in that area.
1974 _pmd
= pmdp_clear_flush(vma
, address
, pmd
);
1975 spin_unlock(&mm
->page_table_lock
);
1976 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1979 isolated
= __collapse_huge_page_isolate(vma
, address
, pte
);
1982 if (unlikely(!isolated
)) {
1984 spin_lock(&mm
->page_table_lock
);
1985 BUG_ON(!pmd_none(*pmd
));
1986 set_pmd_at(mm
, address
, pmd
, _pmd
);
1987 spin_unlock(&mm
->page_table_lock
);
1988 anon_vma_unlock(vma
->anon_vma
);
1993 * All pages are isolated and locked so anon_vma rmap
1994 * can't run anymore.
1996 anon_vma_unlock(vma
->anon_vma
);
1998 __collapse_huge_page_copy(pte
, new_page
, vma
, address
, ptl
);
2000 __SetPageUptodate(new_page
);
2001 pgtable
= pmd_pgtable(_pmd
);
2003 _pmd
= mk_pmd(new_page
, vma
->vm_page_prot
);
2004 _pmd
= maybe_pmd_mkwrite(pmd_mkdirty(_pmd
), vma
);
2005 _pmd
= pmd_mkhuge(_pmd
);
2008 * spin_lock() below is not the equivalent of smp_wmb(), so
2009 * this is needed to avoid the copy_huge_page writes to become
2010 * visible after the set_pmd_at() write.
2014 spin_lock(&mm
->page_table_lock
);
2015 BUG_ON(!pmd_none(*pmd
));
2016 page_add_new_anon_rmap(new_page
, vma
, address
);
2017 set_pmd_at(mm
, address
, pmd
, _pmd
);
2018 update_mmu_cache_pmd(vma
, address
, pmd
);
2019 pgtable_trans_huge_deposit(mm
, pgtable
);
2020 spin_unlock(&mm
->page_table_lock
);
2024 khugepaged_pages_collapsed
++;
2026 up_write(&mm
->mmap_sem
);
2030 mem_cgroup_uncharge_page(new_page
);
2034 static int khugepaged_scan_pmd(struct mm_struct
*mm
,
2035 struct vm_area_struct
*vma
,
2036 unsigned long address
,
2037 struct page
**hpage
)
2041 int ret
= 0, referenced
= 0, none
= 0;
2043 unsigned long _address
;
2047 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2049 pmd
= mm_find_pmd(mm
, address
);
2052 if (pmd_trans_huge(*pmd
))
2055 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2056 for (_address
= address
, _pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2057 _pte
++, _address
+= PAGE_SIZE
) {
2058 pte_t pteval
= *_pte
;
2059 if (pte_none(pteval
)) {
2060 if (++none
<= khugepaged_max_ptes_none
)
2065 if (!pte_present(pteval
) || !pte_write(pteval
))
2067 page
= vm_normal_page(vma
, _address
, pteval
);
2068 if (unlikely(!page
))
2071 * Chose the node of the first page. This could
2072 * be more sophisticated and look at more pages,
2073 * but isn't for now.
2076 node
= page_to_nid(page
);
2077 VM_BUG_ON(PageCompound(page
));
2078 if (!PageLRU(page
) || PageLocked(page
) || !PageAnon(page
))
2080 /* cannot use mapcount: can't collapse if there's a gup pin */
2081 if (page_count(page
) != 1)
2083 if (pte_young(pteval
) || PageReferenced(page
) ||
2084 mmu_notifier_test_young(vma
->vm_mm
, address
))
2090 pte_unmap_unlock(pte
, ptl
);
2092 /* collapse_huge_page will return with the mmap_sem released */
2093 collapse_huge_page(mm
, address
, hpage
, vma
, node
);
2098 static void collect_mm_slot(struct mm_slot
*mm_slot
)
2100 struct mm_struct
*mm
= mm_slot
->mm
;
2102 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2104 if (khugepaged_test_exit(mm
)) {
2106 hlist_del(&mm_slot
->hash
);
2107 list_del(&mm_slot
->mm_node
);
2110 * Not strictly needed because the mm exited already.
2112 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2115 /* khugepaged_mm_lock actually not necessary for the below */
2116 free_mm_slot(mm_slot
);
2121 static unsigned int khugepaged_scan_mm_slot(unsigned int pages
,
2122 struct page
**hpage
)
2123 __releases(&khugepaged_mm_lock
)
2124 __acquires(&khugepaged_mm_lock
)
2126 struct mm_slot
*mm_slot
;
2127 struct mm_struct
*mm
;
2128 struct vm_area_struct
*vma
;
2132 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2134 if (khugepaged_scan
.mm_slot
)
2135 mm_slot
= khugepaged_scan
.mm_slot
;
2137 mm_slot
= list_entry(khugepaged_scan
.mm_head
.next
,
2138 struct mm_slot
, mm_node
);
2139 khugepaged_scan
.address
= 0;
2140 khugepaged_scan
.mm_slot
= mm_slot
;
2142 spin_unlock(&khugepaged_mm_lock
);
2145 down_read(&mm
->mmap_sem
);
2146 if (unlikely(khugepaged_test_exit(mm
)))
2149 vma
= find_vma(mm
, khugepaged_scan
.address
);
2152 for (; vma
; vma
= vma
->vm_next
) {
2153 unsigned long hstart
, hend
;
2156 if (unlikely(khugepaged_test_exit(mm
))) {
2160 if (!hugepage_vma_check(vma
)) {
2165 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2166 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2169 if (khugepaged_scan
.address
> hend
)
2171 if (khugepaged_scan
.address
< hstart
)
2172 khugepaged_scan
.address
= hstart
;
2173 VM_BUG_ON(khugepaged_scan
.address
& ~HPAGE_PMD_MASK
);
2175 while (khugepaged_scan
.address
< hend
) {
2178 if (unlikely(khugepaged_test_exit(mm
)))
2179 goto breakouterloop
;
2181 VM_BUG_ON(khugepaged_scan
.address
< hstart
||
2182 khugepaged_scan
.address
+ HPAGE_PMD_SIZE
>
2184 ret
= khugepaged_scan_pmd(mm
, vma
,
2185 khugepaged_scan
.address
,
2187 /* move to next address */
2188 khugepaged_scan
.address
+= HPAGE_PMD_SIZE
;
2189 progress
+= HPAGE_PMD_NR
;
2191 /* we released mmap_sem so break loop */
2192 goto breakouterloop_mmap_sem
;
2193 if (progress
>= pages
)
2194 goto breakouterloop
;
2198 up_read(&mm
->mmap_sem
); /* exit_mmap will destroy ptes after this */
2199 breakouterloop_mmap_sem
:
2201 spin_lock(&khugepaged_mm_lock
);
2202 VM_BUG_ON(khugepaged_scan
.mm_slot
!= mm_slot
);
2204 * Release the current mm_slot if this mm is about to die, or
2205 * if we scanned all vmas of this mm.
2207 if (khugepaged_test_exit(mm
) || !vma
) {
2209 * Make sure that if mm_users is reaching zero while
2210 * khugepaged runs here, khugepaged_exit will find
2211 * mm_slot not pointing to the exiting mm.
2213 if (mm_slot
->mm_node
.next
!= &khugepaged_scan
.mm_head
) {
2214 khugepaged_scan
.mm_slot
= list_entry(
2215 mm_slot
->mm_node
.next
,
2216 struct mm_slot
, mm_node
);
2217 khugepaged_scan
.address
= 0;
2219 khugepaged_scan
.mm_slot
= NULL
;
2220 khugepaged_full_scans
++;
2223 collect_mm_slot(mm_slot
);
2229 static int khugepaged_has_work(void)
2231 return !list_empty(&khugepaged_scan
.mm_head
) &&
2232 khugepaged_enabled();
2235 static int khugepaged_wait_event(void)
2237 return !list_empty(&khugepaged_scan
.mm_head
) ||
2238 kthread_should_stop();
2241 static void khugepaged_do_scan(void)
2243 struct page
*hpage
= NULL
;
2244 unsigned int progress
= 0, pass_through_head
= 0;
2245 unsigned int pages
= khugepaged_pages_to_scan
;
2248 barrier(); /* write khugepaged_pages_to_scan to local stack */
2250 while (progress
< pages
) {
2251 if (!khugepaged_prealloc_page(&hpage
, &wait
))
2256 if (unlikely(kthread_should_stop() || freezing(current
)))
2259 spin_lock(&khugepaged_mm_lock
);
2260 if (!khugepaged_scan
.mm_slot
)
2261 pass_through_head
++;
2262 if (khugepaged_has_work() &&
2263 pass_through_head
< 2)
2264 progress
+= khugepaged_scan_mm_slot(pages
- progress
,
2268 spin_unlock(&khugepaged_mm_lock
);
2271 if (!IS_ERR_OR_NULL(hpage
))
2275 static void khugepaged_wait_work(void)
2279 if (khugepaged_has_work()) {
2280 if (!khugepaged_scan_sleep_millisecs
)
2283 wait_event_freezable_timeout(khugepaged_wait
,
2284 kthread_should_stop(),
2285 msecs_to_jiffies(khugepaged_scan_sleep_millisecs
));
2289 if (khugepaged_enabled())
2290 wait_event_freezable(khugepaged_wait
, khugepaged_wait_event());
2293 static int khugepaged(void *none
)
2295 struct mm_slot
*mm_slot
;
2298 set_user_nice(current
, 19);
2300 while (!kthread_should_stop()) {
2301 khugepaged_do_scan();
2302 khugepaged_wait_work();
2305 spin_lock(&khugepaged_mm_lock
);
2306 mm_slot
= khugepaged_scan
.mm_slot
;
2307 khugepaged_scan
.mm_slot
= NULL
;
2309 collect_mm_slot(mm_slot
);
2310 spin_unlock(&khugepaged_mm_lock
);
2314 void __split_huge_page_pmd(struct mm_struct
*mm
, pmd_t
*pmd
)
2318 spin_lock(&mm
->page_table_lock
);
2319 if (unlikely(!pmd_trans_huge(*pmd
))) {
2320 spin_unlock(&mm
->page_table_lock
);
2323 page
= pmd_page(*pmd
);
2324 VM_BUG_ON(!page_count(page
));
2326 spin_unlock(&mm
->page_table_lock
);
2328 split_huge_page(page
);
2331 BUG_ON(pmd_trans_huge(*pmd
));
2334 static void split_huge_page_address(struct mm_struct
*mm
,
2335 unsigned long address
)
2339 VM_BUG_ON(!(address
& ~HPAGE_PMD_MASK
));
2341 pmd
= mm_find_pmd(mm
, address
);
2345 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2346 * materialize from under us.
2348 split_huge_page_pmd(mm
, pmd
);
2351 void __vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2352 unsigned long start
,
2357 * If the new start address isn't hpage aligned and it could
2358 * previously contain an hugepage: check if we need to split
2361 if (start
& ~HPAGE_PMD_MASK
&&
2362 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2363 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2364 split_huge_page_address(vma
->vm_mm
, start
);
2367 * If the new end address isn't hpage aligned and it could
2368 * previously contain an hugepage: check if we need to split
2371 if (end
& ~HPAGE_PMD_MASK
&&
2372 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2373 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2374 split_huge_page_address(vma
->vm_mm
, end
);
2377 * If we're also updating the vma->vm_next->vm_start, if the new
2378 * vm_next->vm_start isn't page aligned and it could previously
2379 * contain an hugepage: check if we need to split an huge pmd.
2381 if (adjust_next
> 0) {
2382 struct vm_area_struct
*next
= vma
->vm_next
;
2383 unsigned long nstart
= next
->vm_start
;
2384 nstart
+= adjust_next
<< PAGE_SHIFT
;
2385 if (nstart
& ~HPAGE_PMD_MASK
&&
2386 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2387 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2388 split_huge_page_address(next
->vm_mm
, nstart
);