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(pmd_none(*pmd
)) &&
714 unlikely(__pte_alloc(mm
, vma
, pmd
, address
)))
716 /* if an huge pmd materialized from under us just retry later */
717 if (unlikely(pmd_trans_huge(*pmd
)))
720 * A regular pmd is established and it can't morph into a huge pmd
721 * from under us anymore at this point because we hold the mmap_sem
722 * read mode and khugepaged takes it in write mode. So now it's
723 * safe to run pte_offset_map().
725 pte
= pte_offset_map(pmd
, address
);
726 return handle_pte_fault(mm
, vma
, address
, pte
, pmd
, flags
);
729 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
730 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
731 struct vm_area_struct
*vma
)
733 struct page
*src_page
;
739 pgtable
= pte_alloc_one(dst_mm
, addr
);
740 if (unlikely(!pgtable
))
743 spin_lock(&dst_mm
->page_table_lock
);
744 spin_lock_nested(&src_mm
->page_table_lock
, SINGLE_DEPTH_NESTING
);
748 if (unlikely(!pmd_trans_huge(pmd
))) {
749 pte_free(dst_mm
, pgtable
);
752 if (unlikely(pmd_trans_splitting(pmd
))) {
753 /* split huge page running from under us */
754 spin_unlock(&src_mm
->page_table_lock
);
755 spin_unlock(&dst_mm
->page_table_lock
);
756 pte_free(dst_mm
, pgtable
);
758 wait_split_huge_page(vma
->anon_vma
, src_pmd
); /* src_vma */
761 src_page
= pmd_page(pmd
);
762 VM_BUG_ON(!PageHead(src_page
));
764 page_dup_rmap(src_page
);
765 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
767 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
768 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
769 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
770 pgtable_trans_huge_deposit(dst_mm
, pgtable
);
775 spin_unlock(&src_mm
->page_table_lock
);
776 spin_unlock(&dst_mm
->page_table_lock
);
781 static int do_huge_pmd_wp_page_fallback(struct mm_struct
*mm
,
782 struct vm_area_struct
*vma
,
783 unsigned long address
,
784 pmd_t
*pmd
, pmd_t orig_pmd
,
792 unsigned long mmun_start
; /* For mmu_notifiers */
793 unsigned long mmun_end
; /* For mmu_notifiers */
795 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
797 if (unlikely(!pages
)) {
802 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
803 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
|
805 vma
, address
, page_to_nid(page
));
806 if (unlikely(!pages
[i
] ||
807 mem_cgroup_newpage_charge(pages
[i
], mm
,
811 mem_cgroup_uncharge_start();
813 mem_cgroup_uncharge_page(pages
[i
]);
816 mem_cgroup_uncharge_end();
823 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
824 copy_user_highpage(pages
[i
], page
+ i
,
825 haddr
+ PAGE_SIZE
* i
, vma
);
826 __SetPageUptodate(pages
[i
]);
831 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
832 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
834 spin_lock(&mm
->page_table_lock
);
835 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
837 VM_BUG_ON(!PageHead(page
));
839 pmdp_clear_flush(vma
, haddr
, pmd
);
840 /* leave pmd empty until pte is filled */
842 pgtable
= pgtable_trans_huge_withdraw(mm
);
843 pmd_populate(mm
, &_pmd
, pgtable
);
845 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
847 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
848 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
849 page_add_new_anon_rmap(pages
[i
], vma
, haddr
);
850 pte
= pte_offset_map(&_pmd
, haddr
);
851 VM_BUG_ON(!pte_none(*pte
));
852 set_pte_at(mm
, haddr
, pte
, entry
);
857 smp_wmb(); /* make pte visible before pmd */
858 pmd_populate(mm
, pmd
, pgtable
);
859 page_remove_rmap(page
);
860 spin_unlock(&mm
->page_table_lock
);
862 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
864 ret
|= VM_FAULT_WRITE
;
871 spin_unlock(&mm
->page_table_lock
);
872 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
873 mem_cgroup_uncharge_start();
874 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
875 mem_cgroup_uncharge_page(pages
[i
]);
878 mem_cgroup_uncharge_end();
883 int do_huge_pmd_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
884 unsigned long address
, pmd_t
*pmd
, pmd_t orig_pmd
)
887 struct page
*page
, *new_page
;
889 unsigned long mmun_start
; /* For mmu_notifiers */
890 unsigned long mmun_end
; /* For mmu_notifiers */
892 VM_BUG_ON(!vma
->anon_vma
);
893 spin_lock(&mm
->page_table_lock
);
894 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
897 page
= pmd_page(orig_pmd
);
898 VM_BUG_ON(!PageCompound(page
) || !PageHead(page
));
899 haddr
= address
& HPAGE_PMD_MASK
;
900 if (page_mapcount(page
) == 1) {
902 entry
= pmd_mkyoung(orig_pmd
);
903 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
904 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, 1))
905 update_mmu_cache_pmd(vma
, address
, pmd
);
906 ret
|= VM_FAULT_WRITE
;
910 spin_unlock(&mm
->page_table_lock
);
912 if (transparent_hugepage_enabled(vma
) &&
913 !transparent_hugepage_debug_cow())
914 new_page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
915 vma
, haddr
, numa_node_id(), 0);
919 if (unlikely(!new_page
)) {
920 count_vm_event(THP_FAULT_FALLBACK
);
921 ret
= do_huge_pmd_wp_page_fallback(mm
, vma
, address
,
922 pmd
, orig_pmd
, page
, haddr
);
923 if (ret
& VM_FAULT_OOM
)
924 split_huge_page(page
);
928 count_vm_event(THP_FAULT_ALLOC
);
930 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
))) {
932 split_huge_page(page
);
938 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
939 __SetPageUptodate(new_page
);
942 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
943 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
945 spin_lock(&mm
->page_table_lock
);
947 if (unlikely(!pmd_same(*pmd
, orig_pmd
))) {
948 spin_unlock(&mm
->page_table_lock
);
949 mem_cgroup_uncharge_page(new_page
);
954 VM_BUG_ON(!PageHead(page
));
955 entry
= mk_pmd(new_page
, vma
->vm_page_prot
);
956 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
957 entry
= pmd_mkhuge(entry
);
958 pmdp_clear_flush(vma
, haddr
, pmd
);
959 page_add_new_anon_rmap(new_page
, vma
, haddr
);
960 set_pmd_at(mm
, haddr
, pmd
, entry
);
961 update_mmu_cache_pmd(vma
, address
, pmd
);
962 page_remove_rmap(page
);
964 ret
|= VM_FAULT_WRITE
;
966 spin_unlock(&mm
->page_table_lock
);
968 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
972 spin_unlock(&mm
->page_table_lock
);
976 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
981 struct mm_struct
*mm
= vma
->vm_mm
;
982 struct page
*page
= NULL
;
984 assert_spin_locked(&mm
->page_table_lock
);
986 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
989 page
= pmd_page(*pmd
);
990 VM_BUG_ON(!PageHead(page
));
991 if (flags
& FOLL_TOUCH
) {
994 * We should set the dirty bit only for FOLL_WRITE but
995 * for now the dirty bit in the pmd is meaningless.
996 * And if the dirty bit will become meaningful and
997 * we'll only set it with FOLL_WRITE, an atomic
998 * set_bit will be required on the pmd to set the
999 * young bit, instead of the current set_pmd_at.
1001 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
1002 set_pmd_at(mm
, addr
& HPAGE_PMD_MASK
, pmd
, _pmd
);
1004 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1005 if (page
->mapping
&& trylock_page(page
)) {
1008 mlock_vma_page(page
);
1012 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1013 VM_BUG_ON(!PageCompound(page
));
1014 if (flags
& FOLL_GET
)
1015 get_page_foll(page
);
1021 /* NUMA hinting page fault entry point for trans huge pmds */
1022 int do_huge_pmd_numa_page(struct mm_struct
*mm
, unsigned long addr
,
1023 pmd_t pmd
, pmd_t
*pmdp
)
1026 unsigned long haddr
= addr
& HPAGE_PMD_MASK
;
1028 spin_lock(&mm
->page_table_lock
);
1029 if (unlikely(!pmd_same(pmd
, *pmdp
)))
1032 page
= pmd_page(pmd
);
1033 pmd
= pmd_mknonnuma(pmd
);
1034 set_pmd_at(mm
, haddr
, pmdp
, pmd
);
1035 VM_BUG_ON(pmd_numa(*pmdp
));
1036 update_mmu_cache_pmd(vma
, addr
, pmdp
);
1039 spin_unlock(&mm
->page_table_lock
);
1043 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1044 pmd_t
*pmd
, unsigned long addr
)
1048 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1052 pgtable
= pgtable_trans_huge_withdraw(tlb
->mm
);
1053 orig_pmd
= pmdp_get_and_clear(tlb
->mm
, addr
, pmd
);
1054 page
= pmd_page(orig_pmd
);
1055 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1056 page_remove_rmap(page
);
1057 VM_BUG_ON(page_mapcount(page
) < 0);
1058 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1059 VM_BUG_ON(!PageHead(page
));
1061 spin_unlock(&tlb
->mm
->page_table_lock
);
1062 tlb_remove_page(tlb
, page
);
1063 pte_free(tlb
->mm
, pgtable
);
1069 int mincore_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1070 unsigned long addr
, unsigned long end
,
1075 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1077 * All logical pages in the range are present
1078 * if backed by a huge page.
1080 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1081 memset(vec
, 1, (end
- addr
) >> PAGE_SHIFT
);
1088 int move_huge_pmd(struct vm_area_struct
*vma
, struct vm_area_struct
*new_vma
,
1089 unsigned long old_addr
,
1090 unsigned long new_addr
, unsigned long old_end
,
1091 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1096 struct mm_struct
*mm
= vma
->vm_mm
;
1098 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1099 (new_addr
& ~HPAGE_PMD_MASK
) ||
1100 old_end
- old_addr
< HPAGE_PMD_SIZE
||
1101 (new_vma
->vm_flags
& VM_NOHUGEPAGE
))
1105 * The destination pmd shouldn't be established, free_pgtables()
1106 * should have release it.
1108 if (WARN_ON(!pmd_none(*new_pmd
))) {
1109 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1113 ret
= __pmd_trans_huge_lock(old_pmd
, vma
);
1115 pmd
= pmdp_get_and_clear(mm
, old_addr
, old_pmd
);
1116 VM_BUG_ON(!pmd_none(*new_pmd
));
1117 set_pmd_at(mm
, new_addr
, new_pmd
, pmd
);
1118 spin_unlock(&mm
->page_table_lock
);
1124 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1125 unsigned long addr
, pgprot_t newprot
)
1127 struct mm_struct
*mm
= vma
->vm_mm
;
1130 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1132 entry
= pmdp_get_and_clear(mm
, addr
, pmd
);
1133 entry
= pmd_modify(entry
, newprot
);
1134 set_pmd_at(mm
, addr
, pmd
, entry
);
1135 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1143 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1144 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1146 * Note that if it returns 1, this routine returns without unlocking page
1147 * table locks. So callers must unlock them.
1149 int __pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1151 spin_lock(&vma
->vm_mm
->page_table_lock
);
1152 if (likely(pmd_trans_huge(*pmd
))) {
1153 if (unlikely(pmd_trans_splitting(*pmd
))) {
1154 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1155 wait_split_huge_page(vma
->anon_vma
, pmd
);
1158 /* Thp mapped by 'pmd' is stable, so we can
1159 * handle it as it is. */
1163 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1167 pmd_t
*page_check_address_pmd(struct page
*page
,
1168 struct mm_struct
*mm
,
1169 unsigned long address
,
1170 enum page_check_address_pmd_flag flag
)
1174 pmd_t
*pmd
, *ret
= NULL
;
1176 if (address
& ~HPAGE_PMD_MASK
)
1179 pgd
= pgd_offset(mm
, address
);
1180 if (!pgd_present(*pgd
))
1183 pud
= pud_offset(pgd
, address
);
1184 if (!pud_present(*pud
))
1187 pmd
= pmd_offset(pud
, address
);
1190 if (pmd_page(*pmd
) != page
)
1193 * split_vma() may create temporary aliased mappings. There is
1194 * no risk as long as all huge pmd are found and have their
1195 * splitting bit set before __split_huge_page_refcount
1196 * runs. Finding the same huge pmd more than once during the
1197 * same rmap walk is not a problem.
1199 if (flag
== PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
&&
1200 pmd_trans_splitting(*pmd
))
1202 if (pmd_trans_huge(*pmd
)) {
1203 VM_BUG_ON(flag
== PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
&&
1204 !pmd_trans_splitting(*pmd
));
1211 static int __split_huge_page_splitting(struct page
*page
,
1212 struct vm_area_struct
*vma
,
1213 unsigned long address
)
1215 struct mm_struct
*mm
= vma
->vm_mm
;
1218 /* For mmu_notifiers */
1219 const unsigned long mmun_start
= address
;
1220 const unsigned long mmun_end
= address
+ HPAGE_PMD_SIZE
;
1222 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1223 spin_lock(&mm
->page_table_lock
);
1224 pmd
= page_check_address_pmd(page
, mm
, address
,
1225 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
);
1228 * We can't temporarily set the pmd to null in order
1229 * to split it, the pmd must remain marked huge at all
1230 * times or the VM won't take the pmd_trans_huge paths
1231 * and it won't wait on the anon_vma->root->mutex to
1232 * serialize against split_huge_page*.
1234 pmdp_splitting_flush(vma
, address
, pmd
);
1237 spin_unlock(&mm
->page_table_lock
);
1238 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1243 static void __split_huge_page_refcount(struct page
*page
)
1246 struct zone
*zone
= page_zone(page
);
1247 struct lruvec
*lruvec
;
1250 /* prevent PageLRU to go away from under us, and freeze lru stats */
1251 spin_lock_irq(&zone
->lru_lock
);
1252 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
1254 compound_lock(page
);
1255 /* complete memcg works before add pages to LRU */
1256 mem_cgroup_split_huge_fixup(page
);
1258 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
1259 struct page
*page_tail
= page
+ i
;
1261 /* tail_page->_mapcount cannot change */
1262 BUG_ON(page_mapcount(page_tail
) < 0);
1263 tail_count
+= page_mapcount(page_tail
);
1264 /* check for overflow */
1265 BUG_ON(tail_count
< 0);
1266 BUG_ON(atomic_read(&page_tail
->_count
) != 0);
1268 * tail_page->_count is zero and not changing from
1269 * under us. But get_page_unless_zero() may be running
1270 * from under us on the tail_page. If we used
1271 * atomic_set() below instead of atomic_add(), we
1272 * would then run atomic_set() concurrently with
1273 * get_page_unless_zero(), and atomic_set() is
1274 * implemented in C not using locked ops. spin_unlock
1275 * on x86 sometime uses locked ops because of PPro
1276 * errata 66, 92, so unless somebody can guarantee
1277 * atomic_set() here would be safe on all archs (and
1278 * not only on x86), it's safer to use atomic_add().
1280 atomic_add(page_mapcount(page
) + page_mapcount(page_tail
) + 1,
1281 &page_tail
->_count
);
1283 /* after clearing PageTail the gup refcount can be released */
1287 * retain hwpoison flag of the poisoned tail page:
1288 * fix for the unsuitable process killed on Guest Machine(KVM)
1289 * by the memory-failure.
1291 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
| __PG_HWPOISON
;
1292 page_tail
->flags
|= (page
->flags
&
1293 ((1L << PG_referenced
) |
1294 (1L << PG_swapbacked
) |
1295 (1L << PG_mlocked
) |
1296 (1L << PG_uptodate
)));
1297 page_tail
->flags
|= (1L << PG_dirty
);
1299 /* clear PageTail before overwriting first_page */
1303 * __split_huge_page_splitting() already set the
1304 * splitting bit in all pmd that could map this
1305 * hugepage, that will ensure no CPU can alter the
1306 * mapcount on the head page. The mapcount is only
1307 * accounted in the head page and it has to be
1308 * transferred to all tail pages in the below code. So
1309 * for this code to be safe, the split the mapcount
1310 * can't change. But that doesn't mean userland can't
1311 * keep changing and reading the page contents while
1312 * we transfer the mapcount, so the pmd splitting
1313 * status is achieved setting a reserved bit in the
1314 * pmd, not by clearing the present bit.
1316 page_tail
->_mapcount
= page
->_mapcount
;
1318 BUG_ON(page_tail
->mapping
);
1319 page_tail
->mapping
= page
->mapping
;
1321 page_tail
->index
= page
->index
+ i
;
1323 BUG_ON(!PageAnon(page_tail
));
1324 BUG_ON(!PageUptodate(page_tail
));
1325 BUG_ON(!PageDirty(page_tail
));
1326 BUG_ON(!PageSwapBacked(page_tail
));
1328 lru_add_page_tail(page
, page_tail
, lruvec
);
1330 atomic_sub(tail_count
, &page
->_count
);
1331 BUG_ON(atomic_read(&page
->_count
) <= 0);
1333 __mod_zone_page_state(zone
, NR_ANON_TRANSPARENT_HUGEPAGES
, -1);
1334 __mod_zone_page_state(zone
, NR_ANON_PAGES
, HPAGE_PMD_NR
);
1336 ClearPageCompound(page
);
1337 compound_unlock(page
);
1338 spin_unlock_irq(&zone
->lru_lock
);
1340 for (i
= 1; i
< HPAGE_PMD_NR
; i
++) {
1341 struct page
*page_tail
= page
+ i
;
1342 BUG_ON(page_count(page_tail
) <= 0);
1344 * Tail pages may be freed if there wasn't any mapping
1345 * like if add_to_swap() is running on a lru page that
1346 * had its mapping zapped. And freeing these pages
1347 * requires taking the lru_lock so we do the put_page
1348 * of the tail pages after the split is complete.
1350 put_page(page_tail
);
1354 * Only the head page (now become a regular page) is required
1355 * to be pinned by the caller.
1357 BUG_ON(page_count(page
) <= 0);
1360 static int __split_huge_page_map(struct page
*page
,
1361 struct vm_area_struct
*vma
,
1362 unsigned long address
)
1364 struct mm_struct
*mm
= vma
->vm_mm
;
1368 unsigned long haddr
;
1370 spin_lock(&mm
->page_table_lock
);
1371 pmd
= page_check_address_pmd(page
, mm
, address
,
1372 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
);
1374 pgtable
= pgtable_trans_huge_withdraw(mm
);
1375 pmd_populate(mm
, &_pmd
, pgtable
);
1378 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1380 BUG_ON(PageCompound(page
+i
));
1381 entry
= mk_pte(page
+ i
, vma
->vm_page_prot
);
1382 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1383 if (!pmd_write(*pmd
))
1384 entry
= pte_wrprotect(entry
);
1386 BUG_ON(page_mapcount(page
) != 1);
1387 if (!pmd_young(*pmd
))
1388 entry
= pte_mkold(entry
);
1390 entry
= pte_mknuma(entry
);
1391 pte
= pte_offset_map(&_pmd
, haddr
);
1392 BUG_ON(!pte_none(*pte
));
1393 set_pte_at(mm
, haddr
, pte
, entry
);
1397 smp_wmb(); /* make pte visible before pmd */
1399 * Up to this point the pmd is present and huge and
1400 * userland has the whole access to the hugepage
1401 * during the split (which happens in place). If we
1402 * overwrite the pmd with the not-huge version
1403 * pointing to the pte here (which of course we could
1404 * if all CPUs were bug free), userland could trigger
1405 * a small page size TLB miss on the small sized TLB
1406 * while the hugepage TLB entry is still established
1407 * in the huge TLB. Some CPU doesn't like that. See
1408 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1409 * Erratum 383 on page 93. Intel should be safe but is
1410 * also warns that it's only safe if the permission
1411 * and cache attributes of the two entries loaded in
1412 * the two TLB is identical (which should be the case
1413 * here). But it is generally safer to never allow
1414 * small and huge TLB entries for the same virtual
1415 * address to be loaded simultaneously. So instead of
1416 * doing "pmd_populate(); flush_tlb_range();" we first
1417 * mark the current pmd notpresent (atomically because
1418 * here the pmd_trans_huge and pmd_trans_splitting
1419 * must remain set at all times on the pmd until the
1420 * split is complete for this pmd), then we flush the
1421 * SMP TLB and finally we write the non-huge version
1422 * of the pmd entry with pmd_populate.
1424 pmdp_invalidate(vma
, address
, pmd
);
1425 pmd_populate(mm
, pmd
, pgtable
);
1428 spin_unlock(&mm
->page_table_lock
);
1433 /* must be called with anon_vma->root->mutex hold */
1434 static void __split_huge_page(struct page
*page
,
1435 struct anon_vma
*anon_vma
)
1437 int mapcount
, mapcount2
;
1438 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
1439 struct anon_vma_chain
*avc
;
1441 BUG_ON(!PageHead(page
));
1442 BUG_ON(PageTail(page
));
1445 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1446 struct vm_area_struct
*vma
= avc
->vma
;
1447 unsigned long addr
= vma_address(page
, vma
);
1448 BUG_ON(is_vma_temporary_stack(vma
));
1449 mapcount
+= __split_huge_page_splitting(page
, vma
, addr
);
1452 * It is critical that new vmas are added to the tail of the
1453 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1454 * and establishes a child pmd before
1455 * __split_huge_page_splitting() freezes the parent pmd (so if
1456 * we fail to prevent copy_huge_pmd() from running until the
1457 * whole __split_huge_page() is complete), we will still see
1458 * the newly established pmd of the child later during the
1459 * walk, to be able to set it as pmd_trans_splitting too.
1461 if (mapcount
!= page_mapcount(page
))
1462 printk(KERN_ERR
"mapcount %d page_mapcount %d\n",
1463 mapcount
, page_mapcount(page
));
1464 BUG_ON(mapcount
!= page_mapcount(page
));
1466 __split_huge_page_refcount(page
);
1469 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1470 struct vm_area_struct
*vma
= avc
->vma
;
1471 unsigned long addr
= vma_address(page
, vma
);
1472 BUG_ON(is_vma_temporary_stack(vma
));
1473 mapcount2
+= __split_huge_page_map(page
, vma
, addr
);
1475 if (mapcount
!= mapcount2
)
1476 printk(KERN_ERR
"mapcount %d mapcount2 %d page_mapcount %d\n",
1477 mapcount
, mapcount2
, page_mapcount(page
));
1478 BUG_ON(mapcount
!= mapcount2
);
1481 int split_huge_page(struct page
*page
)
1483 struct anon_vma
*anon_vma
;
1486 BUG_ON(!PageAnon(page
));
1487 anon_vma
= page_lock_anon_vma(page
);
1491 if (!PageCompound(page
))
1494 BUG_ON(!PageSwapBacked(page
));
1495 __split_huge_page(page
, anon_vma
);
1496 count_vm_event(THP_SPLIT
);
1498 BUG_ON(PageCompound(page
));
1500 page_unlock_anon_vma(anon_vma
);
1505 #define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
1507 int hugepage_madvise(struct vm_area_struct
*vma
,
1508 unsigned long *vm_flags
, int advice
)
1510 struct mm_struct
*mm
= vma
->vm_mm
;
1515 * Be somewhat over-protective like KSM for now!
1517 if (*vm_flags
& (VM_HUGEPAGE
| VM_NO_THP
))
1519 if (mm
->def_flags
& VM_NOHUGEPAGE
)
1521 *vm_flags
&= ~VM_NOHUGEPAGE
;
1522 *vm_flags
|= VM_HUGEPAGE
;
1524 * If the vma become good for khugepaged to scan,
1525 * register it here without waiting a page fault that
1526 * may not happen any time soon.
1528 if (unlikely(khugepaged_enter_vma_merge(vma
)))
1531 case MADV_NOHUGEPAGE
:
1533 * Be somewhat over-protective like KSM for now!
1535 if (*vm_flags
& (VM_NOHUGEPAGE
| VM_NO_THP
))
1537 *vm_flags
&= ~VM_HUGEPAGE
;
1538 *vm_flags
|= VM_NOHUGEPAGE
;
1540 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1541 * this vma even if we leave the mm registered in khugepaged if
1542 * it got registered before VM_NOHUGEPAGE was set.
1550 static int __init
khugepaged_slab_init(void)
1552 mm_slot_cache
= kmem_cache_create("khugepaged_mm_slot",
1553 sizeof(struct mm_slot
),
1554 __alignof__(struct mm_slot
), 0, NULL
);
1561 static void __init
khugepaged_slab_free(void)
1563 kmem_cache_destroy(mm_slot_cache
);
1564 mm_slot_cache
= NULL
;
1567 static inline struct mm_slot
*alloc_mm_slot(void)
1569 if (!mm_slot_cache
) /* initialization failed */
1571 return kmem_cache_zalloc(mm_slot_cache
, GFP_KERNEL
);
1574 static inline void free_mm_slot(struct mm_slot
*mm_slot
)
1576 kmem_cache_free(mm_slot_cache
, mm_slot
);
1579 static int __init
mm_slots_hash_init(void)
1581 mm_slots_hash
= kzalloc(MM_SLOTS_HASH_HEADS
* sizeof(struct hlist_head
),
1589 static void __init
mm_slots_hash_free(void)
1591 kfree(mm_slots_hash
);
1592 mm_slots_hash
= NULL
;
1596 static struct mm_slot
*get_mm_slot(struct mm_struct
*mm
)
1598 struct mm_slot
*mm_slot
;
1599 struct hlist_head
*bucket
;
1600 struct hlist_node
*node
;
1602 bucket
= &mm_slots_hash
[((unsigned long)mm
/ sizeof(struct mm_struct
))
1603 % MM_SLOTS_HASH_HEADS
];
1604 hlist_for_each_entry(mm_slot
, node
, bucket
, hash
) {
1605 if (mm
== mm_slot
->mm
)
1611 static void insert_to_mm_slots_hash(struct mm_struct
*mm
,
1612 struct mm_slot
*mm_slot
)
1614 struct hlist_head
*bucket
;
1616 bucket
= &mm_slots_hash
[((unsigned long)mm
/ sizeof(struct mm_struct
))
1617 % MM_SLOTS_HASH_HEADS
];
1619 hlist_add_head(&mm_slot
->hash
, bucket
);
1622 static inline int khugepaged_test_exit(struct mm_struct
*mm
)
1624 return atomic_read(&mm
->mm_users
) == 0;
1627 int __khugepaged_enter(struct mm_struct
*mm
)
1629 struct mm_slot
*mm_slot
;
1632 mm_slot
= alloc_mm_slot();
1636 /* __khugepaged_exit() must not run from under us */
1637 VM_BUG_ON(khugepaged_test_exit(mm
));
1638 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE
, &mm
->flags
))) {
1639 free_mm_slot(mm_slot
);
1643 spin_lock(&khugepaged_mm_lock
);
1644 insert_to_mm_slots_hash(mm
, mm_slot
);
1646 * Insert just behind the scanning cursor, to let the area settle
1649 wakeup
= list_empty(&khugepaged_scan
.mm_head
);
1650 list_add_tail(&mm_slot
->mm_node
, &khugepaged_scan
.mm_head
);
1651 spin_unlock(&khugepaged_mm_lock
);
1653 atomic_inc(&mm
->mm_count
);
1655 wake_up_interruptible(&khugepaged_wait
);
1660 int khugepaged_enter_vma_merge(struct vm_area_struct
*vma
)
1662 unsigned long hstart
, hend
;
1665 * Not yet faulted in so we will register later in the
1666 * page fault if needed.
1670 /* khugepaged not yet working on file or special mappings */
1672 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
1673 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1674 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1676 return khugepaged_enter(vma
);
1680 void __khugepaged_exit(struct mm_struct
*mm
)
1682 struct mm_slot
*mm_slot
;
1685 spin_lock(&khugepaged_mm_lock
);
1686 mm_slot
= get_mm_slot(mm
);
1687 if (mm_slot
&& khugepaged_scan
.mm_slot
!= mm_slot
) {
1688 hlist_del(&mm_slot
->hash
);
1689 list_del(&mm_slot
->mm_node
);
1692 spin_unlock(&khugepaged_mm_lock
);
1695 clear_bit(MMF_VM_HUGEPAGE
, &mm
->flags
);
1696 free_mm_slot(mm_slot
);
1698 } else if (mm_slot
) {
1700 * This is required to serialize against
1701 * khugepaged_test_exit() (which is guaranteed to run
1702 * under mmap sem read mode). Stop here (after we
1703 * return all pagetables will be destroyed) until
1704 * khugepaged has finished working on the pagetables
1705 * under the mmap_sem.
1707 down_write(&mm
->mmap_sem
);
1708 up_write(&mm
->mmap_sem
);
1712 static void release_pte_page(struct page
*page
)
1714 /* 0 stands for page_is_file_cache(page) == false */
1715 dec_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1717 putback_lru_page(page
);
1720 static void release_pte_pages(pte_t
*pte
, pte_t
*_pte
)
1722 while (--_pte
>= pte
) {
1723 pte_t pteval
= *_pte
;
1724 if (!pte_none(pteval
))
1725 release_pte_page(pte_page(pteval
));
1729 static void release_all_pte_pages(pte_t
*pte
)
1731 release_pte_pages(pte
, pte
+ HPAGE_PMD_NR
);
1734 static int __collapse_huge_page_isolate(struct vm_area_struct
*vma
,
1735 unsigned long address
,
1740 int referenced
= 0, isolated
= 0, none
= 0;
1741 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
1742 _pte
++, address
+= PAGE_SIZE
) {
1743 pte_t pteval
= *_pte
;
1744 if (pte_none(pteval
)) {
1745 if (++none
<= khugepaged_max_ptes_none
)
1748 release_pte_pages(pte
, _pte
);
1752 if (!pte_present(pteval
) || !pte_write(pteval
)) {
1753 release_pte_pages(pte
, _pte
);
1756 page
= vm_normal_page(vma
, address
, pteval
);
1757 if (unlikely(!page
)) {
1758 release_pte_pages(pte
, _pte
);
1761 VM_BUG_ON(PageCompound(page
));
1762 BUG_ON(!PageAnon(page
));
1763 VM_BUG_ON(!PageSwapBacked(page
));
1765 /* cannot use mapcount: can't collapse if there's a gup pin */
1766 if (page_count(page
) != 1) {
1767 release_pte_pages(pte
, _pte
);
1771 * We can do it before isolate_lru_page because the
1772 * page can't be freed from under us. NOTE: PG_lock
1773 * is needed to serialize against split_huge_page
1774 * when invoked from the VM.
1776 if (!trylock_page(page
)) {
1777 release_pte_pages(pte
, _pte
);
1781 * Isolate the page to avoid collapsing an hugepage
1782 * currently in use by the VM.
1784 if (isolate_lru_page(page
)) {
1786 release_pte_pages(pte
, _pte
);
1789 /* 0 stands for page_is_file_cache(page) == false */
1790 inc_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1791 VM_BUG_ON(!PageLocked(page
));
1792 VM_BUG_ON(PageLRU(page
));
1794 /* If there is no mapped pte young don't collapse the page */
1795 if (pte_young(pteval
) || PageReferenced(page
) ||
1796 mmu_notifier_test_young(vma
->vm_mm
, address
))
1799 if (unlikely(!referenced
))
1800 release_all_pte_pages(pte
);
1807 static void __collapse_huge_page_copy(pte_t
*pte
, struct page
*page
,
1808 struct vm_area_struct
*vma
,
1809 unsigned long address
,
1813 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
; _pte
++) {
1814 pte_t pteval
= *_pte
;
1815 struct page
*src_page
;
1817 if (pte_none(pteval
)) {
1818 clear_user_highpage(page
, address
);
1819 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, 1);
1821 src_page
= pte_page(pteval
);
1822 copy_user_highpage(page
, src_page
, address
, vma
);
1823 VM_BUG_ON(page_mapcount(src_page
) != 1);
1824 release_pte_page(src_page
);
1826 * ptl mostly unnecessary, but preempt has to
1827 * be disabled to update the per-cpu stats
1828 * inside page_remove_rmap().
1832 * paravirt calls inside pte_clear here are
1835 pte_clear(vma
->vm_mm
, address
, _pte
);
1836 page_remove_rmap(src_page
);
1838 free_page_and_swap_cache(src_page
);
1841 address
+= PAGE_SIZE
;
1846 static void khugepaged_alloc_sleep(void)
1848 wait_event_freezable_timeout(khugepaged_wait
, false,
1849 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs
));
1853 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
1855 if (IS_ERR(*hpage
)) {
1861 khugepaged_alloc_sleep();
1862 } else if (*hpage
) {
1871 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
1872 struct vm_area_struct
*vma
, unsigned long address
,
1877 * Allocate the page while the vma is still valid and under
1878 * the mmap_sem read mode so there is no memory allocation
1879 * later when we take the mmap_sem in write mode. This is more
1880 * friendly behavior (OTOH it may actually hide bugs) to
1881 * filesystems in userland with daemons allocating memory in
1882 * the userland I/O paths. Allocating memory with the
1883 * mmap_sem in read mode is good idea also to allow greater
1886 *hpage
= alloc_hugepage_vma(khugepaged_defrag(), vma
, address
,
1887 node
, __GFP_OTHER_NODE
);
1890 * After allocating the hugepage, release the mmap_sem read lock in
1891 * preparation for taking it in write mode.
1893 up_read(&mm
->mmap_sem
);
1894 if (unlikely(!*hpage
)) {
1895 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
1896 *hpage
= ERR_PTR(-ENOMEM
);
1900 count_vm_event(THP_COLLAPSE_ALLOC
);
1904 static struct page
*khugepaged_alloc_hugepage(bool *wait
)
1909 hpage
= alloc_hugepage(khugepaged_defrag());
1911 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
1916 khugepaged_alloc_sleep();
1918 count_vm_event(THP_COLLAPSE_ALLOC
);
1919 } while (unlikely(!hpage
) && likely(khugepaged_enabled()));
1924 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
1927 *hpage
= khugepaged_alloc_hugepage(wait
);
1929 if (unlikely(!*hpage
))
1936 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
1937 struct vm_area_struct
*vma
, unsigned long address
,
1940 up_read(&mm
->mmap_sem
);
1946 static void collapse_huge_page(struct mm_struct
*mm
,
1947 unsigned long address
,
1948 struct page
**hpage
,
1949 struct vm_area_struct
*vma
,
1957 struct page
*new_page
;
1960 unsigned long hstart
, hend
;
1961 unsigned long mmun_start
; /* For mmu_notifiers */
1962 unsigned long mmun_end
; /* For mmu_notifiers */
1964 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
1966 /* release the mmap_sem read lock. */
1967 new_page
= khugepaged_alloc_page(hpage
, mm
, vma
, address
, node
);
1971 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
)))
1975 * Prevent all access to pagetables with the exception of
1976 * gup_fast later hanlded by the ptep_clear_flush and the VM
1977 * handled by the anon_vma lock + PG_lock.
1979 down_write(&mm
->mmap_sem
);
1980 if (unlikely(khugepaged_test_exit(mm
)))
1983 vma
= find_vma(mm
, address
);
1984 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1985 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1986 if (address
< hstart
|| address
+ HPAGE_PMD_SIZE
> hend
)
1989 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) && !khugepaged_always()) ||
1990 (vma
->vm_flags
& VM_NOHUGEPAGE
))
1993 if (!vma
->anon_vma
|| vma
->vm_ops
)
1995 if (is_vma_temporary_stack(vma
))
1997 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
1999 pgd
= pgd_offset(mm
, address
);
2000 if (!pgd_present(*pgd
))
2003 pud
= pud_offset(pgd
, address
);
2004 if (!pud_present(*pud
))
2007 pmd
= pmd_offset(pud
, address
);
2008 /* pmd can't go away or become huge under us */
2009 if (!pmd_present(*pmd
) || pmd_trans_huge(*pmd
))
2012 anon_vma_lock(vma
->anon_vma
);
2014 pte
= pte_offset_map(pmd
, address
);
2015 ptl
= pte_lockptr(mm
, pmd
);
2017 mmun_start
= address
;
2018 mmun_end
= address
+ HPAGE_PMD_SIZE
;
2019 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2020 spin_lock(&mm
->page_table_lock
); /* probably unnecessary */
2022 * After this gup_fast can't run anymore. This also removes
2023 * any huge TLB entry from the CPU so we won't allow
2024 * huge and small TLB entries for the same virtual address
2025 * to avoid the risk of CPU bugs in that area.
2027 _pmd
= pmdp_clear_flush(vma
, address
, pmd
);
2028 spin_unlock(&mm
->page_table_lock
);
2029 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2032 isolated
= __collapse_huge_page_isolate(vma
, address
, pte
);
2035 if (unlikely(!isolated
)) {
2037 spin_lock(&mm
->page_table_lock
);
2038 BUG_ON(!pmd_none(*pmd
));
2039 set_pmd_at(mm
, address
, pmd
, _pmd
);
2040 spin_unlock(&mm
->page_table_lock
);
2041 anon_vma_unlock(vma
->anon_vma
);
2046 * All pages are isolated and locked so anon_vma rmap
2047 * can't run anymore.
2049 anon_vma_unlock(vma
->anon_vma
);
2051 __collapse_huge_page_copy(pte
, new_page
, vma
, address
, ptl
);
2053 __SetPageUptodate(new_page
);
2054 pgtable
= pmd_pgtable(_pmd
);
2056 _pmd
= mk_pmd(new_page
, vma
->vm_page_prot
);
2057 _pmd
= maybe_pmd_mkwrite(pmd_mkdirty(_pmd
), vma
);
2058 _pmd
= pmd_mkhuge(_pmd
);
2061 * spin_lock() below is not the equivalent of smp_wmb(), so
2062 * this is needed to avoid the copy_huge_page writes to become
2063 * visible after the set_pmd_at() write.
2067 spin_lock(&mm
->page_table_lock
);
2068 BUG_ON(!pmd_none(*pmd
));
2069 page_add_new_anon_rmap(new_page
, vma
, address
);
2070 set_pmd_at(mm
, address
, pmd
, _pmd
);
2071 update_mmu_cache_pmd(vma
, address
, pmd
);
2072 pgtable_trans_huge_deposit(mm
, pgtable
);
2073 spin_unlock(&mm
->page_table_lock
);
2077 khugepaged_pages_collapsed
++;
2079 up_write(&mm
->mmap_sem
);
2083 mem_cgroup_uncharge_page(new_page
);
2087 static int khugepaged_scan_pmd(struct mm_struct
*mm
,
2088 struct vm_area_struct
*vma
,
2089 unsigned long address
,
2090 struct page
**hpage
)
2096 int ret
= 0, referenced
= 0, none
= 0;
2098 unsigned long _address
;
2102 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2104 pgd
= pgd_offset(mm
, address
);
2105 if (!pgd_present(*pgd
))
2108 pud
= pud_offset(pgd
, address
);
2109 if (!pud_present(*pud
))
2112 pmd
= pmd_offset(pud
, address
);
2113 if (!pmd_present(*pmd
) || pmd_trans_huge(*pmd
))
2116 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2117 for (_address
= address
, _pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2118 _pte
++, _address
+= PAGE_SIZE
) {
2119 pte_t pteval
= *_pte
;
2120 if (pte_none(pteval
)) {
2121 if (++none
<= khugepaged_max_ptes_none
)
2126 if (!pte_present(pteval
) || !pte_write(pteval
))
2128 page
= vm_normal_page(vma
, _address
, pteval
);
2129 if (unlikely(!page
))
2132 * Chose the node of the first page. This could
2133 * be more sophisticated and look at more pages,
2134 * but isn't for now.
2137 node
= page_to_nid(page
);
2138 VM_BUG_ON(PageCompound(page
));
2139 if (!PageLRU(page
) || PageLocked(page
) || !PageAnon(page
))
2141 /* cannot use mapcount: can't collapse if there's a gup pin */
2142 if (page_count(page
) != 1)
2144 if (pte_young(pteval
) || PageReferenced(page
) ||
2145 mmu_notifier_test_young(vma
->vm_mm
, address
))
2151 pte_unmap_unlock(pte
, ptl
);
2153 /* collapse_huge_page will return with the mmap_sem released */
2154 collapse_huge_page(mm
, address
, hpage
, vma
, node
);
2159 static void collect_mm_slot(struct mm_slot
*mm_slot
)
2161 struct mm_struct
*mm
= mm_slot
->mm
;
2163 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2165 if (khugepaged_test_exit(mm
)) {
2167 hlist_del(&mm_slot
->hash
);
2168 list_del(&mm_slot
->mm_node
);
2171 * Not strictly needed because the mm exited already.
2173 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2176 /* khugepaged_mm_lock actually not necessary for the below */
2177 free_mm_slot(mm_slot
);
2182 static unsigned int khugepaged_scan_mm_slot(unsigned int pages
,
2183 struct page
**hpage
)
2184 __releases(&khugepaged_mm_lock
)
2185 __acquires(&khugepaged_mm_lock
)
2187 struct mm_slot
*mm_slot
;
2188 struct mm_struct
*mm
;
2189 struct vm_area_struct
*vma
;
2193 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2195 if (khugepaged_scan
.mm_slot
)
2196 mm_slot
= khugepaged_scan
.mm_slot
;
2198 mm_slot
= list_entry(khugepaged_scan
.mm_head
.next
,
2199 struct mm_slot
, mm_node
);
2200 khugepaged_scan
.address
= 0;
2201 khugepaged_scan
.mm_slot
= mm_slot
;
2203 spin_unlock(&khugepaged_mm_lock
);
2206 down_read(&mm
->mmap_sem
);
2207 if (unlikely(khugepaged_test_exit(mm
)))
2210 vma
= find_vma(mm
, khugepaged_scan
.address
);
2213 for (; vma
; vma
= vma
->vm_next
) {
2214 unsigned long hstart
, hend
;
2217 if (unlikely(khugepaged_test_exit(mm
))) {
2222 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) &&
2223 !khugepaged_always()) ||
2224 (vma
->vm_flags
& VM_NOHUGEPAGE
)) {
2229 if (!vma
->anon_vma
|| vma
->vm_ops
)
2231 if (is_vma_temporary_stack(vma
))
2233 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
2235 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2236 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2239 if (khugepaged_scan
.address
> hend
)
2241 if (khugepaged_scan
.address
< hstart
)
2242 khugepaged_scan
.address
= hstart
;
2243 VM_BUG_ON(khugepaged_scan
.address
& ~HPAGE_PMD_MASK
);
2245 while (khugepaged_scan
.address
< hend
) {
2248 if (unlikely(khugepaged_test_exit(mm
)))
2249 goto breakouterloop
;
2251 VM_BUG_ON(khugepaged_scan
.address
< hstart
||
2252 khugepaged_scan
.address
+ HPAGE_PMD_SIZE
>
2254 ret
= khugepaged_scan_pmd(mm
, vma
,
2255 khugepaged_scan
.address
,
2257 /* move to next address */
2258 khugepaged_scan
.address
+= HPAGE_PMD_SIZE
;
2259 progress
+= HPAGE_PMD_NR
;
2261 /* we released mmap_sem so break loop */
2262 goto breakouterloop_mmap_sem
;
2263 if (progress
>= pages
)
2264 goto breakouterloop
;
2268 up_read(&mm
->mmap_sem
); /* exit_mmap will destroy ptes after this */
2269 breakouterloop_mmap_sem
:
2271 spin_lock(&khugepaged_mm_lock
);
2272 VM_BUG_ON(khugepaged_scan
.mm_slot
!= mm_slot
);
2274 * Release the current mm_slot if this mm is about to die, or
2275 * if we scanned all vmas of this mm.
2277 if (khugepaged_test_exit(mm
) || !vma
) {
2279 * Make sure that if mm_users is reaching zero while
2280 * khugepaged runs here, khugepaged_exit will find
2281 * mm_slot not pointing to the exiting mm.
2283 if (mm_slot
->mm_node
.next
!= &khugepaged_scan
.mm_head
) {
2284 khugepaged_scan
.mm_slot
= list_entry(
2285 mm_slot
->mm_node
.next
,
2286 struct mm_slot
, mm_node
);
2287 khugepaged_scan
.address
= 0;
2289 khugepaged_scan
.mm_slot
= NULL
;
2290 khugepaged_full_scans
++;
2293 collect_mm_slot(mm_slot
);
2299 static int khugepaged_has_work(void)
2301 return !list_empty(&khugepaged_scan
.mm_head
) &&
2302 khugepaged_enabled();
2305 static int khugepaged_wait_event(void)
2307 return !list_empty(&khugepaged_scan
.mm_head
) ||
2308 kthread_should_stop();
2311 static void khugepaged_do_scan(void)
2313 struct page
*hpage
= NULL
;
2314 unsigned int progress
= 0, pass_through_head
= 0;
2315 unsigned int pages
= khugepaged_pages_to_scan
;
2318 barrier(); /* write khugepaged_pages_to_scan to local stack */
2320 while (progress
< pages
) {
2321 if (!khugepaged_prealloc_page(&hpage
, &wait
))
2326 if (unlikely(kthread_should_stop() || freezing(current
)))
2329 spin_lock(&khugepaged_mm_lock
);
2330 if (!khugepaged_scan
.mm_slot
)
2331 pass_through_head
++;
2332 if (khugepaged_has_work() &&
2333 pass_through_head
< 2)
2334 progress
+= khugepaged_scan_mm_slot(pages
- progress
,
2338 spin_unlock(&khugepaged_mm_lock
);
2341 if (!IS_ERR_OR_NULL(hpage
))
2345 static void khugepaged_wait_work(void)
2349 if (khugepaged_has_work()) {
2350 if (!khugepaged_scan_sleep_millisecs
)
2353 wait_event_freezable_timeout(khugepaged_wait
,
2354 kthread_should_stop(),
2355 msecs_to_jiffies(khugepaged_scan_sleep_millisecs
));
2359 if (khugepaged_enabled())
2360 wait_event_freezable(khugepaged_wait
, khugepaged_wait_event());
2363 static int khugepaged(void *none
)
2365 struct mm_slot
*mm_slot
;
2368 set_user_nice(current
, 19);
2370 while (!kthread_should_stop()) {
2371 khugepaged_do_scan();
2372 khugepaged_wait_work();
2375 spin_lock(&khugepaged_mm_lock
);
2376 mm_slot
= khugepaged_scan
.mm_slot
;
2377 khugepaged_scan
.mm_slot
= NULL
;
2379 collect_mm_slot(mm_slot
);
2380 spin_unlock(&khugepaged_mm_lock
);
2384 void __split_huge_page_pmd(struct mm_struct
*mm
, pmd_t
*pmd
)
2388 spin_lock(&mm
->page_table_lock
);
2389 if (unlikely(!pmd_trans_huge(*pmd
))) {
2390 spin_unlock(&mm
->page_table_lock
);
2393 page
= pmd_page(*pmd
);
2394 VM_BUG_ON(!page_count(page
));
2396 spin_unlock(&mm
->page_table_lock
);
2398 split_huge_page(page
);
2401 BUG_ON(pmd_trans_huge(*pmd
));
2404 static void split_huge_page_address(struct mm_struct
*mm
,
2405 unsigned long address
)
2411 VM_BUG_ON(!(address
& ~HPAGE_PMD_MASK
));
2413 pgd
= pgd_offset(mm
, address
);
2414 if (!pgd_present(*pgd
))
2417 pud
= pud_offset(pgd
, address
);
2418 if (!pud_present(*pud
))
2421 pmd
= pmd_offset(pud
, address
);
2422 if (!pmd_present(*pmd
))
2425 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2426 * materialize from under us.
2428 split_huge_page_pmd(mm
, pmd
);
2431 void __vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2432 unsigned long start
,
2437 * If the new start address isn't hpage aligned and it could
2438 * previously contain an hugepage: check if we need to split
2441 if (start
& ~HPAGE_PMD_MASK
&&
2442 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2443 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2444 split_huge_page_address(vma
->vm_mm
, start
);
2447 * If the new end address isn't hpage aligned and it could
2448 * previously contain an hugepage: check if we need to split
2451 if (end
& ~HPAGE_PMD_MASK
&&
2452 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2453 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2454 split_huge_page_address(vma
->vm_mm
, end
);
2457 * If we're also updating the vma->vm_next->vm_start, if the new
2458 * vm_next->vm_start isn't page aligned and it could previously
2459 * contain an hugepage: check if we need to split an huge pmd.
2461 if (adjust_next
> 0) {
2462 struct vm_area_struct
*next
= vma
->vm_next
;
2463 unsigned long nstart
= next
->vm_start
;
2464 nstart
+= adjust_next
<< PAGE_SHIFT
;
2465 if (nstart
& ~HPAGE_PMD_MASK
&&
2466 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2467 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2468 split_huge_page_address(next
->vm_mm
, nstart
);