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>
21 #include <asm/pgalloc.h>
25 * By default transparent hugepage support is enabled for all mappings
26 * and khugepaged scans all mappings. Defrag is only invoked by
27 * khugepaged hugepage allocations and by page faults inside
28 * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived
31 unsigned long transparent_hugepage_flags __read_mostly
=
32 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
33 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
35 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
36 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
38 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
)|
39 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
41 /* default scan 8*512 pte (or vmas) every 30 second */
42 static unsigned int khugepaged_pages_to_scan __read_mostly
= HPAGE_PMD_NR
*8;
43 static unsigned int khugepaged_pages_collapsed
;
44 static unsigned int khugepaged_full_scans
;
45 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly
= 10000;
46 /* during fragmentation poll the hugepage allocator once every minute */
47 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly
= 60000;
48 static struct task_struct
*khugepaged_thread __read_mostly
;
49 static DEFINE_MUTEX(khugepaged_mutex
);
50 static DEFINE_SPINLOCK(khugepaged_mm_lock
);
51 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait
);
53 * default collapse hugepages if there is at least one pte mapped like
54 * it would have happened if the vma was large enough during page
57 static unsigned int khugepaged_max_ptes_none __read_mostly
= HPAGE_PMD_NR
-1;
59 static int khugepaged(void *none
);
60 static int mm_slots_hash_init(void);
61 static int khugepaged_slab_init(void);
62 static void khugepaged_slab_free(void);
64 #define MM_SLOTS_HASH_HEADS 1024
65 static struct hlist_head
*mm_slots_hash __read_mostly
;
66 static struct kmem_cache
*mm_slot_cache __read_mostly
;
69 * struct mm_slot - hash lookup from mm to mm_slot
70 * @hash: hash collision list
71 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
72 * @mm: the mm that this information is valid for
75 struct hlist_node hash
;
76 struct list_head mm_node
;
81 * struct khugepaged_scan - cursor for scanning
82 * @mm_head: the head of the mm list to scan
83 * @mm_slot: the current mm_slot we are scanning
84 * @address: the next address inside that to be scanned
86 * There is only the one khugepaged_scan instance of this cursor structure.
88 struct khugepaged_scan
{
89 struct list_head mm_head
;
90 struct mm_slot
*mm_slot
;
91 unsigned long address
;
93 static struct khugepaged_scan khugepaged_scan
= {
94 .mm_head
= LIST_HEAD_INIT(khugepaged_scan
.mm_head
),
98 static int set_recommended_min_free_kbytes(void)
102 unsigned long recommended_min
;
103 extern int min_free_kbytes
;
105 if (!khugepaged_enabled())
108 for_each_populated_zone(zone
)
111 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
112 recommended_min
= pageblock_nr_pages
* nr_zones
* 2;
115 * Make sure that on average at least two pageblocks are almost free
116 * of another type, one for a migratetype to fall back to and a
117 * second to avoid subsequent fallbacks of other types There are 3
118 * MIGRATE_TYPES we care about.
120 recommended_min
+= pageblock_nr_pages
* nr_zones
*
121 MIGRATE_PCPTYPES
* MIGRATE_PCPTYPES
;
123 /* don't ever allow to reserve more than 5% of the lowmem */
124 recommended_min
= min(recommended_min
,
125 (unsigned long) nr_free_buffer_pages() / 20);
126 recommended_min
<<= (PAGE_SHIFT
-10);
128 if (recommended_min
> min_free_kbytes
)
129 min_free_kbytes
= recommended_min
;
130 setup_per_zone_wmarks();
133 late_initcall(set_recommended_min_free_kbytes
);
135 static int start_khugepaged(void)
138 if (khugepaged_enabled()) {
139 if (!khugepaged_thread
)
140 khugepaged_thread
= kthread_run(khugepaged
, NULL
,
142 if (unlikely(IS_ERR(khugepaged_thread
))) {
144 "khugepaged: kthread_run(khugepaged) failed\n");
145 err
= PTR_ERR(khugepaged_thread
);
146 khugepaged_thread
= NULL
;
149 if (!list_empty(&khugepaged_scan
.mm_head
))
150 wake_up_interruptible(&khugepaged_wait
);
152 set_recommended_min_free_kbytes();
153 } else if (khugepaged_thread
) {
154 kthread_stop(khugepaged_thread
);
155 khugepaged_thread
= NULL
;
163 static ssize_t
double_flag_show(struct kobject
*kobj
,
164 struct kobj_attribute
*attr
, char *buf
,
165 enum transparent_hugepage_flag enabled
,
166 enum transparent_hugepage_flag req_madv
)
168 if (test_bit(enabled
, &transparent_hugepage_flags
)) {
169 VM_BUG_ON(test_bit(req_madv
, &transparent_hugepage_flags
));
170 return sprintf(buf
, "[always] madvise never\n");
171 } else if (test_bit(req_madv
, &transparent_hugepage_flags
))
172 return sprintf(buf
, "always [madvise] never\n");
174 return sprintf(buf
, "always madvise [never]\n");
176 static ssize_t
double_flag_store(struct kobject
*kobj
,
177 struct kobj_attribute
*attr
,
178 const char *buf
, size_t count
,
179 enum transparent_hugepage_flag enabled
,
180 enum transparent_hugepage_flag req_madv
)
182 if (!memcmp("always", buf
,
183 min(sizeof("always")-1, count
))) {
184 set_bit(enabled
, &transparent_hugepage_flags
);
185 clear_bit(req_madv
, &transparent_hugepage_flags
);
186 } else if (!memcmp("madvise", buf
,
187 min(sizeof("madvise")-1, count
))) {
188 clear_bit(enabled
, &transparent_hugepage_flags
);
189 set_bit(req_madv
, &transparent_hugepage_flags
);
190 } else if (!memcmp("never", buf
,
191 min(sizeof("never")-1, count
))) {
192 clear_bit(enabled
, &transparent_hugepage_flags
);
193 clear_bit(req_madv
, &transparent_hugepage_flags
);
200 static ssize_t
enabled_show(struct kobject
*kobj
,
201 struct kobj_attribute
*attr
, char *buf
)
203 return double_flag_show(kobj
, attr
, buf
,
204 TRANSPARENT_HUGEPAGE_FLAG
,
205 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
207 static ssize_t
enabled_store(struct kobject
*kobj
,
208 struct kobj_attribute
*attr
,
209 const char *buf
, size_t count
)
213 ret
= double_flag_store(kobj
, attr
, buf
, count
,
214 TRANSPARENT_HUGEPAGE_FLAG
,
215 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
220 mutex_lock(&khugepaged_mutex
);
221 err
= start_khugepaged();
222 mutex_unlock(&khugepaged_mutex
);
230 static struct kobj_attribute enabled_attr
=
231 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
233 static ssize_t
single_flag_show(struct kobject
*kobj
,
234 struct kobj_attribute
*attr
, char *buf
,
235 enum transparent_hugepage_flag flag
)
237 return sprintf(buf
, "%d\n",
238 !!test_bit(flag
, &transparent_hugepage_flags
));
241 static ssize_t
single_flag_store(struct kobject
*kobj
,
242 struct kobj_attribute
*attr
,
243 const char *buf
, size_t count
,
244 enum transparent_hugepage_flag flag
)
249 ret
= kstrtoul(buf
, 10, &value
);
256 set_bit(flag
, &transparent_hugepage_flags
);
258 clear_bit(flag
, &transparent_hugepage_flags
);
264 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
265 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
266 * memory just to allocate one more hugepage.
268 static ssize_t
defrag_show(struct kobject
*kobj
,
269 struct kobj_attribute
*attr
, char *buf
)
271 return double_flag_show(kobj
, attr
, buf
,
272 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
273 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
275 static ssize_t
defrag_store(struct kobject
*kobj
,
276 struct kobj_attribute
*attr
,
277 const char *buf
, size_t count
)
279 return double_flag_store(kobj
, attr
, buf
, count
,
280 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
281 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
283 static struct kobj_attribute defrag_attr
=
284 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
286 #ifdef CONFIG_DEBUG_VM
287 static ssize_t
debug_cow_show(struct kobject
*kobj
,
288 struct kobj_attribute
*attr
, char *buf
)
290 return single_flag_show(kobj
, attr
, buf
,
291 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
293 static ssize_t
debug_cow_store(struct kobject
*kobj
,
294 struct kobj_attribute
*attr
,
295 const char *buf
, size_t count
)
297 return single_flag_store(kobj
, attr
, buf
, count
,
298 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
300 static struct kobj_attribute debug_cow_attr
=
301 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
302 #endif /* CONFIG_DEBUG_VM */
304 static struct attribute
*hugepage_attr
[] = {
307 #ifdef CONFIG_DEBUG_VM
308 &debug_cow_attr
.attr
,
313 static struct attribute_group hugepage_attr_group
= {
314 .attrs
= hugepage_attr
,
317 static ssize_t
scan_sleep_millisecs_show(struct kobject
*kobj
,
318 struct kobj_attribute
*attr
,
321 return sprintf(buf
, "%u\n", khugepaged_scan_sleep_millisecs
);
324 static ssize_t
scan_sleep_millisecs_store(struct kobject
*kobj
,
325 struct kobj_attribute
*attr
,
326 const char *buf
, size_t count
)
331 err
= strict_strtoul(buf
, 10, &msecs
);
332 if (err
|| msecs
> UINT_MAX
)
335 khugepaged_scan_sleep_millisecs
= msecs
;
336 wake_up_interruptible(&khugepaged_wait
);
340 static struct kobj_attribute scan_sleep_millisecs_attr
=
341 __ATTR(scan_sleep_millisecs
, 0644, scan_sleep_millisecs_show
,
342 scan_sleep_millisecs_store
);
344 static ssize_t
alloc_sleep_millisecs_show(struct kobject
*kobj
,
345 struct kobj_attribute
*attr
,
348 return sprintf(buf
, "%u\n", khugepaged_alloc_sleep_millisecs
);
351 static ssize_t
alloc_sleep_millisecs_store(struct kobject
*kobj
,
352 struct kobj_attribute
*attr
,
353 const char *buf
, size_t count
)
358 err
= strict_strtoul(buf
, 10, &msecs
);
359 if (err
|| msecs
> UINT_MAX
)
362 khugepaged_alloc_sleep_millisecs
= msecs
;
363 wake_up_interruptible(&khugepaged_wait
);
367 static struct kobj_attribute alloc_sleep_millisecs_attr
=
368 __ATTR(alloc_sleep_millisecs
, 0644, alloc_sleep_millisecs_show
,
369 alloc_sleep_millisecs_store
);
371 static ssize_t
pages_to_scan_show(struct kobject
*kobj
,
372 struct kobj_attribute
*attr
,
375 return sprintf(buf
, "%u\n", khugepaged_pages_to_scan
);
377 static ssize_t
pages_to_scan_store(struct kobject
*kobj
,
378 struct kobj_attribute
*attr
,
379 const char *buf
, size_t count
)
384 err
= strict_strtoul(buf
, 10, &pages
);
385 if (err
|| !pages
|| pages
> UINT_MAX
)
388 khugepaged_pages_to_scan
= pages
;
392 static struct kobj_attribute pages_to_scan_attr
=
393 __ATTR(pages_to_scan
, 0644, pages_to_scan_show
,
394 pages_to_scan_store
);
396 static ssize_t
pages_collapsed_show(struct kobject
*kobj
,
397 struct kobj_attribute
*attr
,
400 return sprintf(buf
, "%u\n", khugepaged_pages_collapsed
);
402 static struct kobj_attribute pages_collapsed_attr
=
403 __ATTR_RO(pages_collapsed
);
405 static ssize_t
full_scans_show(struct kobject
*kobj
,
406 struct kobj_attribute
*attr
,
409 return sprintf(buf
, "%u\n", khugepaged_full_scans
);
411 static struct kobj_attribute full_scans_attr
=
412 __ATTR_RO(full_scans
);
414 static ssize_t
khugepaged_defrag_show(struct kobject
*kobj
,
415 struct kobj_attribute
*attr
, char *buf
)
417 return single_flag_show(kobj
, attr
, buf
,
418 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
420 static ssize_t
khugepaged_defrag_store(struct kobject
*kobj
,
421 struct kobj_attribute
*attr
,
422 const char *buf
, size_t count
)
424 return single_flag_store(kobj
, attr
, buf
, count
,
425 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
427 static struct kobj_attribute khugepaged_defrag_attr
=
428 __ATTR(defrag
, 0644, khugepaged_defrag_show
,
429 khugepaged_defrag_store
);
432 * max_ptes_none controls if khugepaged should collapse hugepages over
433 * any unmapped ptes in turn potentially increasing the memory
434 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
435 * reduce the available free memory in the system as it
436 * runs. Increasing max_ptes_none will instead potentially reduce the
437 * free memory in the system during the khugepaged scan.
439 static ssize_t
khugepaged_max_ptes_none_show(struct kobject
*kobj
,
440 struct kobj_attribute
*attr
,
443 return sprintf(buf
, "%u\n", khugepaged_max_ptes_none
);
445 static ssize_t
khugepaged_max_ptes_none_store(struct kobject
*kobj
,
446 struct kobj_attribute
*attr
,
447 const char *buf
, size_t count
)
450 unsigned long max_ptes_none
;
452 err
= strict_strtoul(buf
, 10, &max_ptes_none
);
453 if (err
|| max_ptes_none
> HPAGE_PMD_NR
-1)
456 khugepaged_max_ptes_none
= max_ptes_none
;
460 static struct kobj_attribute khugepaged_max_ptes_none_attr
=
461 __ATTR(max_ptes_none
, 0644, khugepaged_max_ptes_none_show
,
462 khugepaged_max_ptes_none_store
);
464 static struct attribute
*khugepaged_attr
[] = {
465 &khugepaged_defrag_attr
.attr
,
466 &khugepaged_max_ptes_none_attr
.attr
,
467 &pages_to_scan_attr
.attr
,
468 &pages_collapsed_attr
.attr
,
469 &full_scans_attr
.attr
,
470 &scan_sleep_millisecs_attr
.attr
,
471 &alloc_sleep_millisecs_attr
.attr
,
475 static struct attribute_group khugepaged_attr_group
= {
476 .attrs
= khugepaged_attr
,
477 .name
= "khugepaged",
480 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
484 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
485 if (unlikely(!*hugepage_kobj
)) {
486 printk(KERN_ERR
"hugepage: failed kobject create\n");
490 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
492 printk(KERN_ERR
"hugepage: failed register hugeage group\n");
496 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
498 printk(KERN_ERR
"hugepage: failed register hugeage group\n");
499 goto remove_hp_group
;
505 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
507 kobject_put(*hugepage_kobj
);
511 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
513 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
514 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
515 kobject_put(hugepage_kobj
);
518 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
523 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
526 #endif /* CONFIG_SYSFS */
528 static int __init
hugepage_init(void)
531 struct kobject
*hugepage_kobj
;
533 if (!has_transparent_hugepage()) {
534 transparent_hugepage_flags
= 0;
538 err
= hugepage_init_sysfs(&hugepage_kobj
);
542 err
= khugepaged_slab_init();
546 err
= mm_slots_hash_init();
548 khugepaged_slab_free();
553 * By default disable transparent hugepages on smaller systems,
554 * where the extra memory used could hurt more than TLB overhead
555 * is likely to save. The admin can still enable it through /sys.
557 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
)))
558 transparent_hugepage_flags
= 0;
564 hugepage_exit_sysfs(hugepage_kobj
);
567 module_init(hugepage_init
)
569 static int __init
setup_transparent_hugepage(char *str
)
574 if (!strcmp(str
, "always")) {
575 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
576 &transparent_hugepage_flags
);
577 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
578 &transparent_hugepage_flags
);
580 } else if (!strcmp(str
, "madvise")) {
581 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
582 &transparent_hugepage_flags
);
583 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
584 &transparent_hugepage_flags
);
586 } else if (!strcmp(str
, "never")) {
587 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
588 &transparent_hugepage_flags
);
589 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
590 &transparent_hugepage_flags
);
596 "transparent_hugepage= cannot parse, ignored\n");
599 __setup("transparent_hugepage=", setup_transparent_hugepage
);
601 static inline pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
603 if (likely(vma
->vm_flags
& VM_WRITE
))
604 pmd
= pmd_mkwrite(pmd
);
608 static int __do_huge_pmd_anonymous_page(struct mm_struct
*mm
,
609 struct vm_area_struct
*vma
,
610 unsigned long haddr
, pmd_t
*pmd
,
615 VM_BUG_ON(!PageCompound(page
));
616 pgtable
= pte_alloc_one(mm
, haddr
);
617 if (unlikely(!pgtable
))
620 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
621 __SetPageUptodate(page
);
623 spin_lock(&mm
->page_table_lock
);
624 if (unlikely(!pmd_none(*pmd
))) {
625 spin_unlock(&mm
->page_table_lock
);
626 mem_cgroup_uncharge_page(page
);
628 pte_free(mm
, pgtable
);
631 entry
= mk_pmd(page
, vma
->vm_page_prot
);
632 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
633 entry
= pmd_mkhuge(entry
);
635 * The spinlocking to take the lru_lock inside
636 * page_add_new_anon_rmap() acts as a full memory
637 * barrier to be sure clear_huge_page writes become
638 * visible after the set_pmd_at() write.
640 page_add_new_anon_rmap(page
, vma
, haddr
);
641 set_pmd_at(mm
, haddr
, pmd
, entry
);
642 pgtable_trans_huge_deposit(mm
, pgtable
);
643 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
645 spin_unlock(&mm
->page_table_lock
);
651 static inline gfp_t
alloc_hugepage_gfpmask(int defrag
, gfp_t extra_gfp
)
653 return (GFP_TRANSHUGE
& ~(defrag
? 0 : __GFP_WAIT
)) | extra_gfp
;
656 static inline struct page
*alloc_hugepage_vma(int defrag
,
657 struct vm_area_struct
*vma
,
658 unsigned long haddr
, int nd
,
661 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag
, extra_gfp
),
662 HPAGE_PMD_ORDER
, vma
, haddr
, nd
);
666 static inline struct page
*alloc_hugepage(int defrag
)
668 return alloc_pages(alloc_hugepage_gfpmask(defrag
, 0),
673 int do_huge_pmd_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
674 unsigned long address
, pmd_t
*pmd
,
678 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
681 if (haddr
>= vma
->vm_start
&& haddr
+ HPAGE_PMD_SIZE
<= vma
->vm_end
) {
682 if (unlikely(anon_vma_prepare(vma
)))
684 if (unlikely(khugepaged_enter(vma
)))
686 page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
687 vma
, haddr
, numa_node_id(), 0);
688 if (unlikely(!page
)) {
689 count_vm_event(THP_FAULT_FALLBACK
);
692 count_vm_event(THP_FAULT_ALLOC
);
693 if (unlikely(mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
))) {
697 if (unlikely(__do_huge_pmd_anonymous_page(mm
, vma
, haddr
, pmd
,
699 mem_cgroup_uncharge_page(page
);
708 * Use __pte_alloc instead of pte_alloc_map, because we can't
709 * run pte_offset_map on the pmd, if an huge pmd could
710 * materialize from under us from a different thread.
712 if (unlikely(__pte_alloc(mm
, vma
, pmd
, address
)))
714 /* if an huge pmd materialized from under us just retry later */
715 if (unlikely(pmd_trans_huge(*pmd
)))
718 * A regular pmd is established and it can't morph into a huge pmd
719 * from under us anymore at this point because we hold the mmap_sem
720 * read mode and khugepaged takes it in write mode. So now it's
721 * safe to run pte_offset_map().
723 pte
= pte_offset_map(pmd
, address
);
724 return handle_pte_fault(mm
, vma
, address
, pte
, pmd
, flags
);
727 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
728 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
729 struct vm_area_struct
*vma
)
731 struct page
*src_page
;
737 pgtable
= pte_alloc_one(dst_mm
, addr
);
738 if (unlikely(!pgtable
))
741 spin_lock(&dst_mm
->page_table_lock
);
742 spin_lock_nested(&src_mm
->page_table_lock
, SINGLE_DEPTH_NESTING
);
746 if (unlikely(!pmd_trans_huge(pmd
))) {
747 pte_free(dst_mm
, pgtable
);
750 if (unlikely(pmd_trans_splitting(pmd
))) {
751 /* split huge page running from under us */
752 spin_unlock(&src_mm
->page_table_lock
);
753 spin_unlock(&dst_mm
->page_table_lock
);
754 pte_free(dst_mm
, pgtable
);
756 wait_split_huge_page(vma
->anon_vma
, src_pmd
); /* src_vma */
759 src_page
= pmd_page(pmd
);
760 VM_BUG_ON(!PageHead(src_page
));
762 page_dup_rmap(src_page
);
763 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
765 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
766 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
767 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
768 pgtable_trans_huge_deposit(dst_mm
, pgtable
);
773 spin_unlock(&src_mm
->page_table_lock
);
774 spin_unlock(&dst_mm
->page_table_lock
);
779 static int do_huge_pmd_wp_page_fallback(struct mm_struct
*mm
,
780 struct vm_area_struct
*vma
,
781 unsigned long address
,
782 pmd_t
*pmd
, pmd_t orig_pmd
,
790 unsigned long mmun_start
; /* For mmu_notifiers */
791 unsigned long mmun_end
; /* For mmu_notifiers */
793 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
795 if (unlikely(!pages
)) {
800 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
801 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
|
803 vma
, address
, page_to_nid(page
));
804 if (unlikely(!pages
[i
] ||
805 mem_cgroup_newpage_charge(pages
[i
], mm
,
809 mem_cgroup_uncharge_start();
811 mem_cgroup_uncharge_page(pages
[i
]);
814 mem_cgroup_uncharge_end();
821 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
822 copy_user_highpage(pages
[i
], page
+ i
,
823 haddr
+ PAGE_SIZE
* i
, vma
);
824 __SetPageUptodate(pages
[i
]);
829 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
830 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
832 spin_lock(&mm
->page_table_lock
);
833 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
835 VM_BUG_ON(!PageHead(page
));
837 pmdp_clear_flush(vma
, haddr
, pmd
);
838 /* leave pmd empty until pte is filled */
840 pgtable
= pgtable_trans_huge_withdraw(mm
);
841 pmd_populate(mm
, &_pmd
, pgtable
);
843 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
845 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
846 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
847 page_add_new_anon_rmap(pages
[i
], vma
, haddr
);
848 pte
= pte_offset_map(&_pmd
, haddr
);
849 VM_BUG_ON(!pte_none(*pte
));
850 set_pte_at(mm
, haddr
, pte
, entry
);
855 smp_wmb(); /* make pte visible before pmd */
856 pmd_populate(mm
, pmd
, pgtable
);
857 page_remove_rmap(page
);
858 spin_unlock(&mm
->page_table_lock
);
860 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
862 ret
|= VM_FAULT_WRITE
;
869 spin_unlock(&mm
->page_table_lock
);
870 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
871 mem_cgroup_uncharge_start();
872 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
873 mem_cgroup_uncharge_page(pages
[i
]);
876 mem_cgroup_uncharge_end();
881 int do_huge_pmd_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
882 unsigned long address
, pmd_t
*pmd
, pmd_t orig_pmd
)
885 struct page
*page
, *new_page
;
887 unsigned long mmun_start
; /* For mmu_notifiers */
888 unsigned long mmun_end
; /* For mmu_notifiers */
890 VM_BUG_ON(!vma
->anon_vma
);
891 spin_lock(&mm
->page_table_lock
);
892 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
895 page
= pmd_page(orig_pmd
);
896 VM_BUG_ON(!PageCompound(page
) || !PageHead(page
));
897 haddr
= address
& HPAGE_PMD_MASK
;
898 if (page_mapcount(page
) == 1) {
900 entry
= pmd_mkyoung(orig_pmd
);
901 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
902 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, 1))
903 update_mmu_cache_pmd(vma
, address
, pmd
);
904 ret
|= VM_FAULT_WRITE
;
908 spin_unlock(&mm
->page_table_lock
);
910 if (transparent_hugepage_enabled(vma
) &&
911 !transparent_hugepage_debug_cow())
912 new_page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
913 vma
, haddr
, numa_node_id(), 0);
917 if (unlikely(!new_page
)) {
918 count_vm_event(THP_FAULT_FALLBACK
);
919 ret
= do_huge_pmd_wp_page_fallback(mm
, vma
, address
,
920 pmd
, orig_pmd
, page
, haddr
);
921 if (ret
& VM_FAULT_OOM
)
922 split_huge_page(page
);
926 count_vm_event(THP_FAULT_ALLOC
);
928 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
))) {
930 split_huge_page(page
);
936 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
937 __SetPageUptodate(new_page
);
940 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
941 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
943 spin_lock(&mm
->page_table_lock
);
945 if (unlikely(!pmd_same(*pmd
, orig_pmd
))) {
946 spin_unlock(&mm
->page_table_lock
);
947 mem_cgroup_uncharge_page(new_page
);
952 VM_BUG_ON(!PageHead(page
));
953 entry
= mk_pmd(new_page
, vma
->vm_page_prot
);
954 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
955 entry
= pmd_mkhuge(entry
);
956 pmdp_clear_flush(vma
, haddr
, pmd
);
957 page_add_new_anon_rmap(new_page
, vma
, haddr
);
958 set_pmd_at(mm
, haddr
, pmd
, entry
);
959 update_mmu_cache_pmd(vma
, address
, pmd
);
960 page_remove_rmap(page
);
962 ret
|= VM_FAULT_WRITE
;
964 spin_unlock(&mm
->page_table_lock
);
966 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
970 spin_unlock(&mm
->page_table_lock
);
974 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
979 struct mm_struct
*mm
= vma
->vm_mm
;
980 struct page
*page
= NULL
;
982 assert_spin_locked(&mm
->page_table_lock
);
984 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
987 page
= pmd_page(*pmd
);
988 VM_BUG_ON(!PageHead(page
));
989 if (flags
& FOLL_TOUCH
) {
992 * We should set the dirty bit only for FOLL_WRITE but
993 * for now the dirty bit in the pmd is meaningless.
994 * And if the dirty bit will become meaningful and
995 * we'll only set it with FOLL_WRITE, an atomic
996 * set_bit will be required on the pmd to set the
997 * young bit, instead of the current set_pmd_at.
999 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
1000 set_pmd_at(mm
, addr
& HPAGE_PMD_MASK
, pmd
, _pmd
);
1002 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1003 if (page
->mapping
&& trylock_page(page
)) {
1006 mlock_vma_page(page
);
1010 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1011 VM_BUG_ON(!PageCompound(page
));
1012 if (flags
& FOLL_GET
)
1013 get_page_foll(page
);
1019 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1020 pmd_t
*pmd
, unsigned long addr
)
1024 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1028 pgtable
= pgtable_trans_huge_withdraw(tlb
->mm
);
1029 orig_pmd
= pmdp_get_and_clear(tlb
->mm
, addr
, pmd
);
1030 page
= pmd_page(orig_pmd
);
1031 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1032 page_remove_rmap(page
);
1033 VM_BUG_ON(page_mapcount(page
) < 0);
1034 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1035 VM_BUG_ON(!PageHead(page
));
1037 spin_unlock(&tlb
->mm
->page_table_lock
);
1038 tlb_remove_page(tlb
, page
);
1039 pte_free(tlb
->mm
, pgtable
);
1045 int mincore_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1046 unsigned long addr
, unsigned long end
,
1051 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1053 * All logical pages in the range are present
1054 * if backed by a huge page.
1056 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1057 memset(vec
, 1, (end
- addr
) >> PAGE_SHIFT
);
1064 int move_huge_pmd(struct vm_area_struct
*vma
, struct vm_area_struct
*new_vma
,
1065 unsigned long old_addr
,
1066 unsigned long new_addr
, unsigned long old_end
,
1067 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1072 struct mm_struct
*mm
= vma
->vm_mm
;
1074 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1075 (new_addr
& ~HPAGE_PMD_MASK
) ||
1076 old_end
- old_addr
< HPAGE_PMD_SIZE
||
1077 (new_vma
->vm_flags
& VM_NOHUGEPAGE
))
1081 * The destination pmd shouldn't be established, free_pgtables()
1082 * should have release it.
1084 if (WARN_ON(!pmd_none(*new_pmd
))) {
1085 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1089 ret
= __pmd_trans_huge_lock(old_pmd
, vma
);
1091 pmd
= pmdp_get_and_clear(mm
, old_addr
, old_pmd
);
1092 VM_BUG_ON(!pmd_none(*new_pmd
));
1093 set_pmd_at(mm
, new_addr
, new_pmd
, pmd
);
1094 spin_unlock(&mm
->page_table_lock
);
1100 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1101 unsigned long addr
, pgprot_t newprot
)
1103 struct mm_struct
*mm
= vma
->vm_mm
;
1106 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1108 entry
= pmdp_get_and_clear(mm
, addr
, pmd
);
1109 entry
= pmd_modify(entry
, newprot
);
1110 set_pmd_at(mm
, addr
, pmd
, entry
);
1111 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1119 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1120 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1122 * Note that if it returns 1, this routine returns without unlocking page
1123 * table locks. So callers must unlock them.
1125 int __pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1127 spin_lock(&vma
->vm_mm
->page_table_lock
);
1128 if (likely(pmd_trans_huge(*pmd
))) {
1129 if (unlikely(pmd_trans_splitting(*pmd
))) {
1130 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1131 wait_split_huge_page(vma
->anon_vma
, pmd
);
1134 /* Thp mapped by 'pmd' is stable, so we can
1135 * handle it as it is. */
1139 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1143 pmd_t
*page_check_address_pmd(struct page
*page
,
1144 struct mm_struct
*mm
,
1145 unsigned long address
,
1146 enum page_check_address_pmd_flag flag
)
1150 pmd_t
*pmd
, *ret
= NULL
;
1152 if (address
& ~HPAGE_PMD_MASK
)
1155 pgd
= pgd_offset(mm
, address
);
1156 if (!pgd_present(*pgd
))
1159 pud
= pud_offset(pgd
, address
);
1160 if (!pud_present(*pud
))
1163 pmd
= pmd_offset(pud
, address
);
1166 if (pmd_page(*pmd
) != page
)
1169 * split_vma() may create temporary aliased mappings. There is
1170 * no risk as long as all huge pmd are found and have their
1171 * splitting bit set before __split_huge_page_refcount
1172 * runs. Finding the same huge pmd more than once during the
1173 * same rmap walk is not a problem.
1175 if (flag
== PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
&&
1176 pmd_trans_splitting(*pmd
))
1178 if (pmd_trans_huge(*pmd
)) {
1179 VM_BUG_ON(flag
== PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
&&
1180 !pmd_trans_splitting(*pmd
));
1187 static int __split_huge_page_splitting(struct page
*page
,
1188 struct vm_area_struct
*vma
,
1189 unsigned long address
)
1191 struct mm_struct
*mm
= vma
->vm_mm
;
1194 /* For mmu_notifiers */
1195 const unsigned long mmun_start
= address
;
1196 const unsigned long mmun_end
= address
+ HPAGE_PMD_SIZE
;
1198 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1199 spin_lock(&mm
->page_table_lock
);
1200 pmd
= page_check_address_pmd(page
, mm
, address
,
1201 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
);
1204 * We can't temporarily set the pmd to null in order
1205 * to split it, the pmd must remain marked huge at all
1206 * times or the VM won't take the pmd_trans_huge paths
1207 * and it won't wait on the anon_vma->root->mutex to
1208 * serialize against split_huge_page*.
1210 pmdp_splitting_flush(vma
, address
, pmd
);
1213 spin_unlock(&mm
->page_table_lock
);
1214 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1219 static void __split_huge_page_refcount(struct page
*page
)
1222 struct zone
*zone
= page_zone(page
);
1223 struct lruvec
*lruvec
;
1226 /* prevent PageLRU to go away from under us, and freeze lru stats */
1227 spin_lock_irq(&zone
->lru_lock
);
1228 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
1230 compound_lock(page
);
1231 /* complete memcg works before add pages to LRU */
1232 mem_cgroup_split_huge_fixup(page
);
1234 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
1235 struct page
*page_tail
= page
+ i
;
1237 /* tail_page->_mapcount cannot change */
1238 BUG_ON(page_mapcount(page_tail
) < 0);
1239 tail_count
+= page_mapcount(page_tail
);
1240 /* check for overflow */
1241 BUG_ON(tail_count
< 0);
1242 BUG_ON(atomic_read(&page_tail
->_count
) != 0);
1244 * tail_page->_count is zero and not changing from
1245 * under us. But get_page_unless_zero() may be running
1246 * from under us on the tail_page. If we used
1247 * atomic_set() below instead of atomic_add(), we
1248 * would then run atomic_set() concurrently with
1249 * get_page_unless_zero(), and atomic_set() is
1250 * implemented in C not using locked ops. spin_unlock
1251 * on x86 sometime uses locked ops because of PPro
1252 * errata 66, 92, so unless somebody can guarantee
1253 * atomic_set() here would be safe on all archs (and
1254 * not only on x86), it's safer to use atomic_add().
1256 atomic_add(page_mapcount(page
) + page_mapcount(page_tail
) + 1,
1257 &page_tail
->_count
);
1259 /* after clearing PageTail the gup refcount can be released */
1263 * retain hwpoison flag of the poisoned tail page:
1264 * fix for the unsuitable process killed on Guest Machine(KVM)
1265 * by the memory-failure.
1267 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
| __PG_HWPOISON
;
1268 page_tail
->flags
|= (page
->flags
&
1269 ((1L << PG_referenced
) |
1270 (1L << PG_swapbacked
) |
1271 (1L << PG_mlocked
) |
1272 (1L << PG_uptodate
)));
1273 page_tail
->flags
|= (1L << PG_dirty
);
1275 /* clear PageTail before overwriting first_page */
1279 * __split_huge_page_splitting() already set the
1280 * splitting bit in all pmd that could map this
1281 * hugepage, that will ensure no CPU can alter the
1282 * mapcount on the head page. The mapcount is only
1283 * accounted in the head page and it has to be
1284 * transferred to all tail pages in the below code. So
1285 * for this code to be safe, the split the mapcount
1286 * can't change. But that doesn't mean userland can't
1287 * keep changing and reading the page contents while
1288 * we transfer the mapcount, so the pmd splitting
1289 * status is achieved setting a reserved bit in the
1290 * pmd, not by clearing the present bit.
1292 page_tail
->_mapcount
= page
->_mapcount
;
1294 BUG_ON(page_tail
->mapping
);
1295 page_tail
->mapping
= page
->mapping
;
1297 page_tail
->index
= page
->index
+ i
;
1299 BUG_ON(!PageAnon(page_tail
));
1300 BUG_ON(!PageUptodate(page_tail
));
1301 BUG_ON(!PageDirty(page_tail
));
1302 BUG_ON(!PageSwapBacked(page_tail
));
1304 lru_add_page_tail(page
, page_tail
, lruvec
);
1306 atomic_sub(tail_count
, &page
->_count
);
1307 BUG_ON(atomic_read(&page
->_count
) <= 0);
1309 __mod_zone_page_state(zone
, NR_ANON_TRANSPARENT_HUGEPAGES
, -1);
1310 __mod_zone_page_state(zone
, NR_ANON_PAGES
, HPAGE_PMD_NR
);
1312 ClearPageCompound(page
);
1313 compound_unlock(page
);
1314 spin_unlock_irq(&zone
->lru_lock
);
1316 for (i
= 1; i
< HPAGE_PMD_NR
; i
++) {
1317 struct page
*page_tail
= page
+ i
;
1318 BUG_ON(page_count(page_tail
) <= 0);
1320 * Tail pages may be freed if there wasn't any mapping
1321 * like if add_to_swap() is running on a lru page that
1322 * had its mapping zapped. And freeing these pages
1323 * requires taking the lru_lock so we do the put_page
1324 * of the tail pages after the split is complete.
1326 put_page(page_tail
);
1330 * Only the head page (now become a regular page) is required
1331 * to be pinned by the caller.
1333 BUG_ON(page_count(page
) <= 0);
1336 static int __split_huge_page_map(struct page
*page
,
1337 struct vm_area_struct
*vma
,
1338 unsigned long address
)
1340 struct mm_struct
*mm
= vma
->vm_mm
;
1344 unsigned long haddr
;
1346 spin_lock(&mm
->page_table_lock
);
1347 pmd
= page_check_address_pmd(page
, mm
, address
,
1348 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
);
1350 pgtable
= pgtable_trans_huge_withdraw(mm
);
1351 pmd_populate(mm
, &_pmd
, pgtable
);
1354 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1356 BUG_ON(PageCompound(page
+i
));
1357 entry
= mk_pte(page
+ i
, vma
->vm_page_prot
);
1358 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1359 if (!pmd_write(*pmd
))
1360 entry
= pte_wrprotect(entry
);
1362 BUG_ON(page_mapcount(page
) != 1);
1363 if (!pmd_young(*pmd
))
1364 entry
= pte_mkold(entry
);
1365 pte
= pte_offset_map(&_pmd
, haddr
);
1366 BUG_ON(!pte_none(*pte
));
1367 set_pte_at(mm
, haddr
, pte
, entry
);
1371 smp_wmb(); /* make pte visible before pmd */
1373 * Up to this point the pmd is present and huge and
1374 * userland has the whole access to the hugepage
1375 * during the split (which happens in place). If we
1376 * overwrite the pmd with the not-huge version
1377 * pointing to the pte here (which of course we could
1378 * if all CPUs were bug free), userland could trigger
1379 * a small page size TLB miss on the small sized TLB
1380 * while the hugepage TLB entry is still established
1381 * in the huge TLB. Some CPU doesn't like that. See
1382 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1383 * Erratum 383 on page 93. Intel should be safe but is
1384 * also warns that it's only safe if the permission
1385 * and cache attributes of the two entries loaded in
1386 * the two TLB is identical (which should be the case
1387 * here). But it is generally safer to never allow
1388 * small and huge TLB entries for the same virtual
1389 * address to be loaded simultaneously. So instead of
1390 * doing "pmd_populate(); flush_tlb_range();" we first
1391 * mark the current pmd notpresent (atomically because
1392 * here the pmd_trans_huge and pmd_trans_splitting
1393 * must remain set at all times on the pmd until the
1394 * split is complete for this pmd), then we flush the
1395 * SMP TLB and finally we write the non-huge version
1396 * of the pmd entry with pmd_populate.
1398 pmdp_invalidate(vma
, address
, pmd
);
1399 pmd_populate(mm
, pmd
, pgtable
);
1402 spin_unlock(&mm
->page_table_lock
);
1407 /* must be called with anon_vma->root->mutex hold */
1408 static void __split_huge_page(struct page
*page
,
1409 struct anon_vma
*anon_vma
)
1411 int mapcount
, mapcount2
;
1412 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
1413 struct anon_vma_chain
*avc
;
1415 BUG_ON(!PageHead(page
));
1416 BUG_ON(PageTail(page
));
1419 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1420 struct vm_area_struct
*vma
= avc
->vma
;
1421 unsigned long addr
= vma_address(page
, vma
);
1422 BUG_ON(is_vma_temporary_stack(vma
));
1423 mapcount
+= __split_huge_page_splitting(page
, vma
, addr
);
1426 * It is critical that new vmas are added to the tail of the
1427 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1428 * and establishes a child pmd before
1429 * __split_huge_page_splitting() freezes the parent pmd (so if
1430 * we fail to prevent copy_huge_pmd() from running until the
1431 * whole __split_huge_page() is complete), we will still see
1432 * the newly established pmd of the child later during the
1433 * walk, to be able to set it as pmd_trans_splitting too.
1435 if (mapcount
!= page_mapcount(page
))
1436 printk(KERN_ERR
"mapcount %d page_mapcount %d\n",
1437 mapcount
, page_mapcount(page
));
1438 BUG_ON(mapcount
!= page_mapcount(page
));
1440 __split_huge_page_refcount(page
);
1443 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1444 struct vm_area_struct
*vma
= avc
->vma
;
1445 unsigned long addr
= vma_address(page
, vma
);
1446 BUG_ON(is_vma_temporary_stack(vma
));
1447 mapcount2
+= __split_huge_page_map(page
, vma
, addr
);
1449 if (mapcount
!= mapcount2
)
1450 printk(KERN_ERR
"mapcount %d mapcount2 %d page_mapcount %d\n",
1451 mapcount
, mapcount2
, page_mapcount(page
));
1452 BUG_ON(mapcount
!= mapcount2
);
1455 int split_huge_page(struct page
*page
)
1457 struct anon_vma
*anon_vma
;
1460 BUG_ON(!PageAnon(page
));
1461 anon_vma
= page_lock_anon_vma(page
);
1465 if (!PageCompound(page
))
1468 BUG_ON(!PageSwapBacked(page
));
1469 __split_huge_page(page
, anon_vma
);
1470 count_vm_event(THP_SPLIT
);
1472 BUG_ON(PageCompound(page
));
1474 page_unlock_anon_vma(anon_vma
);
1479 #define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
1481 int hugepage_madvise(struct vm_area_struct
*vma
,
1482 unsigned long *vm_flags
, int advice
)
1484 struct mm_struct
*mm
= vma
->vm_mm
;
1489 * Be somewhat over-protective like KSM for now!
1491 if (*vm_flags
& (VM_HUGEPAGE
| VM_NO_THP
))
1493 if (mm
->def_flags
& VM_NOHUGEPAGE
)
1495 *vm_flags
&= ~VM_NOHUGEPAGE
;
1496 *vm_flags
|= VM_HUGEPAGE
;
1498 * If the vma become good for khugepaged to scan,
1499 * register it here without waiting a page fault that
1500 * may not happen any time soon.
1502 if (unlikely(khugepaged_enter_vma_merge(vma
)))
1505 case MADV_NOHUGEPAGE
:
1507 * Be somewhat over-protective like KSM for now!
1509 if (*vm_flags
& (VM_NOHUGEPAGE
| VM_NO_THP
))
1511 *vm_flags
&= ~VM_HUGEPAGE
;
1512 *vm_flags
|= VM_NOHUGEPAGE
;
1514 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1515 * this vma even if we leave the mm registered in khugepaged if
1516 * it got registered before VM_NOHUGEPAGE was set.
1524 static int __init
khugepaged_slab_init(void)
1526 mm_slot_cache
= kmem_cache_create("khugepaged_mm_slot",
1527 sizeof(struct mm_slot
),
1528 __alignof__(struct mm_slot
), 0, NULL
);
1535 static void __init
khugepaged_slab_free(void)
1537 kmem_cache_destroy(mm_slot_cache
);
1538 mm_slot_cache
= NULL
;
1541 static inline struct mm_slot
*alloc_mm_slot(void)
1543 if (!mm_slot_cache
) /* initialization failed */
1545 return kmem_cache_zalloc(mm_slot_cache
, GFP_KERNEL
);
1548 static inline void free_mm_slot(struct mm_slot
*mm_slot
)
1550 kmem_cache_free(mm_slot_cache
, mm_slot
);
1553 static int __init
mm_slots_hash_init(void)
1555 mm_slots_hash
= kzalloc(MM_SLOTS_HASH_HEADS
* sizeof(struct hlist_head
),
1563 static void __init
mm_slots_hash_free(void)
1565 kfree(mm_slots_hash
);
1566 mm_slots_hash
= NULL
;
1570 static struct mm_slot
*get_mm_slot(struct mm_struct
*mm
)
1572 struct mm_slot
*mm_slot
;
1573 struct hlist_head
*bucket
;
1574 struct hlist_node
*node
;
1576 bucket
= &mm_slots_hash
[((unsigned long)mm
/ sizeof(struct mm_struct
))
1577 % MM_SLOTS_HASH_HEADS
];
1578 hlist_for_each_entry(mm_slot
, node
, bucket
, hash
) {
1579 if (mm
== mm_slot
->mm
)
1585 static void insert_to_mm_slots_hash(struct mm_struct
*mm
,
1586 struct mm_slot
*mm_slot
)
1588 struct hlist_head
*bucket
;
1590 bucket
= &mm_slots_hash
[((unsigned long)mm
/ sizeof(struct mm_struct
))
1591 % MM_SLOTS_HASH_HEADS
];
1593 hlist_add_head(&mm_slot
->hash
, bucket
);
1596 static inline int khugepaged_test_exit(struct mm_struct
*mm
)
1598 return atomic_read(&mm
->mm_users
) == 0;
1601 int __khugepaged_enter(struct mm_struct
*mm
)
1603 struct mm_slot
*mm_slot
;
1606 mm_slot
= alloc_mm_slot();
1610 /* __khugepaged_exit() must not run from under us */
1611 VM_BUG_ON(khugepaged_test_exit(mm
));
1612 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE
, &mm
->flags
))) {
1613 free_mm_slot(mm_slot
);
1617 spin_lock(&khugepaged_mm_lock
);
1618 insert_to_mm_slots_hash(mm
, mm_slot
);
1620 * Insert just behind the scanning cursor, to let the area settle
1623 wakeup
= list_empty(&khugepaged_scan
.mm_head
);
1624 list_add_tail(&mm_slot
->mm_node
, &khugepaged_scan
.mm_head
);
1625 spin_unlock(&khugepaged_mm_lock
);
1627 atomic_inc(&mm
->mm_count
);
1629 wake_up_interruptible(&khugepaged_wait
);
1634 int khugepaged_enter_vma_merge(struct vm_area_struct
*vma
)
1636 unsigned long hstart
, hend
;
1639 * Not yet faulted in so we will register later in the
1640 * page fault if needed.
1644 /* khugepaged not yet working on file or special mappings */
1646 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
1647 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1648 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1650 return khugepaged_enter(vma
);
1654 void __khugepaged_exit(struct mm_struct
*mm
)
1656 struct mm_slot
*mm_slot
;
1659 spin_lock(&khugepaged_mm_lock
);
1660 mm_slot
= get_mm_slot(mm
);
1661 if (mm_slot
&& khugepaged_scan
.mm_slot
!= mm_slot
) {
1662 hlist_del(&mm_slot
->hash
);
1663 list_del(&mm_slot
->mm_node
);
1666 spin_unlock(&khugepaged_mm_lock
);
1669 clear_bit(MMF_VM_HUGEPAGE
, &mm
->flags
);
1670 free_mm_slot(mm_slot
);
1672 } else if (mm_slot
) {
1674 * This is required to serialize against
1675 * khugepaged_test_exit() (which is guaranteed to run
1676 * under mmap sem read mode). Stop here (after we
1677 * return all pagetables will be destroyed) until
1678 * khugepaged has finished working on the pagetables
1679 * under the mmap_sem.
1681 down_write(&mm
->mmap_sem
);
1682 up_write(&mm
->mmap_sem
);
1686 static void release_pte_page(struct page
*page
)
1688 /* 0 stands for page_is_file_cache(page) == false */
1689 dec_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1691 putback_lru_page(page
);
1694 static void release_pte_pages(pte_t
*pte
, pte_t
*_pte
)
1696 while (--_pte
>= pte
) {
1697 pte_t pteval
= *_pte
;
1698 if (!pte_none(pteval
))
1699 release_pte_page(pte_page(pteval
));
1703 static void release_all_pte_pages(pte_t
*pte
)
1705 release_pte_pages(pte
, pte
+ HPAGE_PMD_NR
);
1708 static int __collapse_huge_page_isolate(struct vm_area_struct
*vma
,
1709 unsigned long address
,
1714 int referenced
= 0, isolated
= 0, none
= 0;
1715 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
1716 _pte
++, address
+= PAGE_SIZE
) {
1717 pte_t pteval
= *_pte
;
1718 if (pte_none(pteval
)) {
1719 if (++none
<= khugepaged_max_ptes_none
)
1722 release_pte_pages(pte
, _pte
);
1726 if (!pte_present(pteval
) || !pte_write(pteval
)) {
1727 release_pte_pages(pte
, _pte
);
1730 page
= vm_normal_page(vma
, address
, pteval
);
1731 if (unlikely(!page
)) {
1732 release_pte_pages(pte
, _pte
);
1735 VM_BUG_ON(PageCompound(page
));
1736 BUG_ON(!PageAnon(page
));
1737 VM_BUG_ON(!PageSwapBacked(page
));
1739 /* cannot use mapcount: can't collapse if there's a gup pin */
1740 if (page_count(page
) != 1) {
1741 release_pte_pages(pte
, _pte
);
1745 * We can do it before isolate_lru_page because the
1746 * page can't be freed from under us. NOTE: PG_lock
1747 * is needed to serialize against split_huge_page
1748 * when invoked from the VM.
1750 if (!trylock_page(page
)) {
1751 release_pte_pages(pte
, _pte
);
1755 * Isolate the page to avoid collapsing an hugepage
1756 * currently in use by the VM.
1758 if (isolate_lru_page(page
)) {
1760 release_pte_pages(pte
, _pte
);
1763 /* 0 stands for page_is_file_cache(page) == false */
1764 inc_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1765 VM_BUG_ON(!PageLocked(page
));
1766 VM_BUG_ON(PageLRU(page
));
1768 /* If there is no mapped pte young don't collapse the page */
1769 if (pte_young(pteval
) || PageReferenced(page
) ||
1770 mmu_notifier_test_young(vma
->vm_mm
, address
))
1773 if (unlikely(!referenced
))
1774 release_all_pte_pages(pte
);
1781 static void __collapse_huge_page_copy(pte_t
*pte
, struct page
*page
,
1782 struct vm_area_struct
*vma
,
1783 unsigned long address
,
1787 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
; _pte
++) {
1788 pte_t pteval
= *_pte
;
1789 struct page
*src_page
;
1791 if (pte_none(pteval
)) {
1792 clear_user_highpage(page
, address
);
1793 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, 1);
1795 src_page
= pte_page(pteval
);
1796 copy_user_highpage(page
, src_page
, address
, vma
);
1797 VM_BUG_ON(page_mapcount(src_page
) != 1);
1798 release_pte_page(src_page
);
1800 * ptl mostly unnecessary, but preempt has to
1801 * be disabled to update the per-cpu stats
1802 * inside page_remove_rmap().
1806 * paravirt calls inside pte_clear here are
1809 pte_clear(vma
->vm_mm
, address
, _pte
);
1810 page_remove_rmap(src_page
);
1812 free_page_and_swap_cache(src_page
);
1815 address
+= PAGE_SIZE
;
1820 static void khugepaged_alloc_sleep(void)
1822 wait_event_freezable_timeout(khugepaged_wait
, false,
1823 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs
));
1827 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
1829 if (IS_ERR(*hpage
)) {
1835 khugepaged_alloc_sleep();
1836 } else if (*hpage
) {
1845 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
1846 struct vm_area_struct
*vma
, unsigned long address
,
1851 * Allocate the page while the vma is still valid and under
1852 * the mmap_sem read mode so there is no memory allocation
1853 * later when we take the mmap_sem in write mode. This is more
1854 * friendly behavior (OTOH it may actually hide bugs) to
1855 * filesystems in userland with daemons allocating memory in
1856 * the userland I/O paths. Allocating memory with the
1857 * mmap_sem in read mode is good idea also to allow greater
1860 *hpage
= alloc_hugepage_vma(khugepaged_defrag(), vma
, address
,
1861 node
, __GFP_OTHER_NODE
);
1864 * After allocating the hugepage, release the mmap_sem read lock in
1865 * preparation for taking it in write mode.
1867 up_read(&mm
->mmap_sem
);
1868 if (unlikely(!*hpage
)) {
1869 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
1870 *hpage
= ERR_PTR(-ENOMEM
);
1874 count_vm_event(THP_COLLAPSE_ALLOC
);
1878 static struct page
*khugepaged_alloc_hugepage(bool *wait
)
1883 hpage
= alloc_hugepage(khugepaged_defrag());
1885 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
1890 khugepaged_alloc_sleep();
1892 count_vm_event(THP_COLLAPSE_ALLOC
);
1893 } while (unlikely(!hpage
) && likely(khugepaged_enabled()));
1898 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
1901 *hpage
= khugepaged_alloc_hugepage(wait
);
1903 if (unlikely(!*hpage
))
1910 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
1911 struct vm_area_struct
*vma
, unsigned long address
,
1914 up_read(&mm
->mmap_sem
);
1920 static void collapse_huge_page(struct mm_struct
*mm
,
1921 unsigned long address
,
1922 struct page
**hpage
,
1923 struct vm_area_struct
*vma
,
1931 struct page
*new_page
;
1934 unsigned long hstart
, hend
;
1935 unsigned long mmun_start
; /* For mmu_notifiers */
1936 unsigned long mmun_end
; /* For mmu_notifiers */
1938 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
1940 /* release the mmap_sem read lock. */
1941 new_page
= khugepaged_alloc_page(hpage
, mm
, vma
, address
, node
);
1945 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
)))
1949 * Prevent all access to pagetables with the exception of
1950 * gup_fast later hanlded by the ptep_clear_flush and the VM
1951 * handled by the anon_vma lock + PG_lock.
1953 down_write(&mm
->mmap_sem
);
1954 if (unlikely(khugepaged_test_exit(mm
)))
1957 vma
= find_vma(mm
, address
);
1958 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1959 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1960 if (address
< hstart
|| address
+ HPAGE_PMD_SIZE
> hend
)
1963 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) && !khugepaged_always()) ||
1964 (vma
->vm_flags
& VM_NOHUGEPAGE
))
1967 if (!vma
->anon_vma
|| vma
->vm_ops
)
1969 if (is_vma_temporary_stack(vma
))
1971 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
1973 pgd
= pgd_offset(mm
, address
);
1974 if (!pgd_present(*pgd
))
1977 pud
= pud_offset(pgd
, address
);
1978 if (!pud_present(*pud
))
1981 pmd
= pmd_offset(pud
, address
);
1982 /* pmd can't go away or become huge under us */
1983 if (!pmd_present(*pmd
) || pmd_trans_huge(*pmd
))
1986 anon_vma_lock(vma
->anon_vma
);
1988 pte
= pte_offset_map(pmd
, address
);
1989 ptl
= pte_lockptr(mm
, pmd
);
1991 mmun_start
= address
;
1992 mmun_end
= address
+ HPAGE_PMD_SIZE
;
1993 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1994 spin_lock(&mm
->page_table_lock
); /* probably unnecessary */
1996 * After this gup_fast can't run anymore. This also removes
1997 * any huge TLB entry from the CPU so we won't allow
1998 * huge and small TLB entries for the same virtual address
1999 * to avoid the risk of CPU bugs in that area.
2001 _pmd
= pmdp_clear_flush(vma
, address
, pmd
);
2002 spin_unlock(&mm
->page_table_lock
);
2003 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2006 isolated
= __collapse_huge_page_isolate(vma
, address
, pte
);
2009 if (unlikely(!isolated
)) {
2011 spin_lock(&mm
->page_table_lock
);
2012 BUG_ON(!pmd_none(*pmd
));
2013 set_pmd_at(mm
, address
, pmd
, _pmd
);
2014 spin_unlock(&mm
->page_table_lock
);
2015 anon_vma_unlock(vma
->anon_vma
);
2020 * All pages are isolated and locked so anon_vma rmap
2021 * can't run anymore.
2023 anon_vma_unlock(vma
->anon_vma
);
2025 __collapse_huge_page_copy(pte
, new_page
, vma
, address
, ptl
);
2027 __SetPageUptodate(new_page
);
2028 pgtable
= pmd_pgtable(_pmd
);
2030 _pmd
= mk_pmd(new_page
, vma
->vm_page_prot
);
2031 _pmd
= maybe_pmd_mkwrite(pmd_mkdirty(_pmd
), vma
);
2032 _pmd
= pmd_mkhuge(_pmd
);
2035 * spin_lock() below is not the equivalent of smp_wmb(), so
2036 * this is needed to avoid the copy_huge_page writes to become
2037 * visible after the set_pmd_at() write.
2041 spin_lock(&mm
->page_table_lock
);
2042 BUG_ON(!pmd_none(*pmd
));
2043 page_add_new_anon_rmap(new_page
, vma
, address
);
2044 set_pmd_at(mm
, address
, pmd
, _pmd
);
2045 update_mmu_cache_pmd(vma
, address
, pmd
);
2046 pgtable_trans_huge_deposit(mm
, pgtable
);
2047 spin_unlock(&mm
->page_table_lock
);
2051 khugepaged_pages_collapsed
++;
2053 up_write(&mm
->mmap_sem
);
2057 mem_cgroup_uncharge_page(new_page
);
2061 static int khugepaged_scan_pmd(struct mm_struct
*mm
,
2062 struct vm_area_struct
*vma
,
2063 unsigned long address
,
2064 struct page
**hpage
)
2070 int ret
= 0, referenced
= 0, none
= 0;
2072 unsigned long _address
;
2076 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2078 pgd
= pgd_offset(mm
, address
);
2079 if (!pgd_present(*pgd
))
2082 pud
= pud_offset(pgd
, address
);
2083 if (!pud_present(*pud
))
2086 pmd
= pmd_offset(pud
, address
);
2087 if (!pmd_present(*pmd
) || pmd_trans_huge(*pmd
))
2090 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2091 for (_address
= address
, _pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2092 _pte
++, _address
+= PAGE_SIZE
) {
2093 pte_t pteval
= *_pte
;
2094 if (pte_none(pteval
)) {
2095 if (++none
<= khugepaged_max_ptes_none
)
2100 if (!pte_present(pteval
) || !pte_write(pteval
))
2102 page
= vm_normal_page(vma
, _address
, pteval
);
2103 if (unlikely(!page
))
2106 * Chose the node of the first page. This could
2107 * be more sophisticated and look at more pages,
2108 * but isn't for now.
2111 node
= page_to_nid(page
);
2112 VM_BUG_ON(PageCompound(page
));
2113 if (!PageLRU(page
) || PageLocked(page
) || !PageAnon(page
))
2115 /* cannot use mapcount: can't collapse if there's a gup pin */
2116 if (page_count(page
) != 1)
2118 if (pte_young(pteval
) || PageReferenced(page
) ||
2119 mmu_notifier_test_young(vma
->vm_mm
, address
))
2125 pte_unmap_unlock(pte
, ptl
);
2127 /* collapse_huge_page will return with the mmap_sem released */
2128 collapse_huge_page(mm
, address
, hpage
, vma
, node
);
2133 static void collect_mm_slot(struct mm_slot
*mm_slot
)
2135 struct mm_struct
*mm
= mm_slot
->mm
;
2137 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2139 if (khugepaged_test_exit(mm
)) {
2141 hlist_del(&mm_slot
->hash
);
2142 list_del(&mm_slot
->mm_node
);
2145 * Not strictly needed because the mm exited already.
2147 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2150 /* khugepaged_mm_lock actually not necessary for the below */
2151 free_mm_slot(mm_slot
);
2156 static unsigned int khugepaged_scan_mm_slot(unsigned int pages
,
2157 struct page
**hpage
)
2158 __releases(&khugepaged_mm_lock
)
2159 __acquires(&khugepaged_mm_lock
)
2161 struct mm_slot
*mm_slot
;
2162 struct mm_struct
*mm
;
2163 struct vm_area_struct
*vma
;
2167 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2169 if (khugepaged_scan
.mm_slot
)
2170 mm_slot
= khugepaged_scan
.mm_slot
;
2172 mm_slot
= list_entry(khugepaged_scan
.mm_head
.next
,
2173 struct mm_slot
, mm_node
);
2174 khugepaged_scan
.address
= 0;
2175 khugepaged_scan
.mm_slot
= mm_slot
;
2177 spin_unlock(&khugepaged_mm_lock
);
2180 down_read(&mm
->mmap_sem
);
2181 if (unlikely(khugepaged_test_exit(mm
)))
2184 vma
= find_vma(mm
, khugepaged_scan
.address
);
2187 for (; vma
; vma
= vma
->vm_next
) {
2188 unsigned long hstart
, hend
;
2191 if (unlikely(khugepaged_test_exit(mm
))) {
2196 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) &&
2197 !khugepaged_always()) ||
2198 (vma
->vm_flags
& VM_NOHUGEPAGE
)) {
2203 if (!vma
->anon_vma
|| vma
->vm_ops
)
2205 if (is_vma_temporary_stack(vma
))
2207 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
2209 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2210 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2213 if (khugepaged_scan
.address
> hend
)
2215 if (khugepaged_scan
.address
< hstart
)
2216 khugepaged_scan
.address
= hstart
;
2217 VM_BUG_ON(khugepaged_scan
.address
& ~HPAGE_PMD_MASK
);
2219 while (khugepaged_scan
.address
< hend
) {
2222 if (unlikely(khugepaged_test_exit(mm
)))
2223 goto breakouterloop
;
2225 VM_BUG_ON(khugepaged_scan
.address
< hstart
||
2226 khugepaged_scan
.address
+ HPAGE_PMD_SIZE
>
2228 ret
= khugepaged_scan_pmd(mm
, vma
,
2229 khugepaged_scan
.address
,
2231 /* move to next address */
2232 khugepaged_scan
.address
+= HPAGE_PMD_SIZE
;
2233 progress
+= HPAGE_PMD_NR
;
2235 /* we released mmap_sem so break loop */
2236 goto breakouterloop_mmap_sem
;
2237 if (progress
>= pages
)
2238 goto breakouterloop
;
2242 up_read(&mm
->mmap_sem
); /* exit_mmap will destroy ptes after this */
2243 breakouterloop_mmap_sem
:
2245 spin_lock(&khugepaged_mm_lock
);
2246 VM_BUG_ON(khugepaged_scan
.mm_slot
!= mm_slot
);
2248 * Release the current mm_slot if this mm is about to die, or
2249 * if we scanned all vmas of this mm.
2251 if (khugepaged_test_exit(mm
) || !vma
) {
2253 * Make sure that if mm_users is reaching zero while
2254 * khugepaged runs here, khugepaged_exit will find
2255 * mm_slot not pointing to the exiting mm.
2257 if (mm_slot
->mm_node
.next
!= &khugepaged_scan
.mm_head
) {
2258 khugepaged_scan
.mm_slot
= list_entry(
2259 mm_slot
->mm_node
.next
,
2260 struct mm_slot
, mm_node
);
2261 khugepaged_scan
.address
= 0;
2263 khugepaged_scan
.mm_slot
= NULL
;
2264 khugepaged_full_scans
++;
2267 collect_mm_slot(mm_slot
);
2273 static int khugepaged_has_work(void)
2275 return !list_empty(&khugepaged_scan
.mm_head
) &&
2276 khugepaged_enabled();
2279 static int khugepaged_wait_event(void)
2281 return !list_empty(&khugepaged_scan
.mm_head
) ||
2282 kthread_should_stop();
2285 static void khugepaged_do_scan(void)
2287 struct page
*hpage
= NULL
;
2288 unsigned int progress
= 0, pass_through_head
= 0;
2289 unsigned int pages
= khugepaged_pages_to_scan
;
2292 barrier(); /* write khugepaged_pages_to_scan to local stack */
2294 while (progress
< pages
) {
2295 if (!khugepaged_prealloc_page(&hpage
, &wait
))
2300 if (unlikely(kthread_should_stop() || freezing(current
)))
2303 spin_lock(&khugepaged_mm_lock
);
2304 if (!khugepaged_scan
.mm_slot
)
2305 pass_through_head
++;
2306 if (khugepaged_has_work() &&
2307 pass_through_head
< 2)
2308 progress
+= khugepaged_scan_mm_slot(pages
- progress
,
2312 spin_unlock(&khugepaged_mm_lock
);
2315 if (!IS_ERR_OR_NULL(hpage
))
2319 static void khugepaged_wait_work(void)
2323 if (khugepaged_has_work()) {
2324 if (!khugepaged_scan_sleep_millisecs
)
2327 wait_event_freezable_timeout(khugepaged_wait
,
2328 kthread_should_stop(),
2329 msecs_to_jiffies(khugepaged_scan_sleep_millisecs
));
2333 if (khugepaged_enabled())
2334 wait_event_freezable(khugepaged_wait
, khugepaged_wait_event());
2337 static int khugepaged(void *none
)
2339 struct mm_slot
*mm_slot
;
2342 set_user_nice(current
, 19);
2344 while (!kthread_should_stop()) {
2345 khugepaged_do_scan();
2346 khugepaged_wait_work();
2349 spin_lock(&khugepaged_mm_lock
);
2350 mm_slot
= khugepaged_scan
.mm_slot
;
2351 khugepaged_scan
.mm_slot
= NULL
;
2353 collect_mm_slot(mm_slot
);
2354 spin_unlock(&khugepaged_mm_lock
);
2358 void __split_huge_page_pmd(struct mm_struct
*mm
, pmd_t
*pmd
)
2362 spin_lock(&mm
->page_table_lock
);
2363 if (unlikely(!pmd_trans_huge(*pmd
))) {
2364 spin_unlock(&mm
->page_table_lock
);
2367 page
= pmd_page(*pmd
);
2368 VM_BUG_ON(!page_count(page
));
2370 spin_unlock(&mm
->page_table_lock
);
2372 split_huge_page(page
);
2375 BUG_ON(pmd_trans_huge(*pmd
));
2378 static void split_huge_page_address(struct mm_struct
*mm
,
2379 unsigned long address
)
2385 VM_BUG_ON(!(address
& ~HPAGE_PMD_MASK
));
2387 pgd
= pgd_offset(mm
, address
);
2388 if (!pgd_present(*pgd
))
2391 pud
= pud_offset(pgd
, address
);
2392 if (!pud_present(*pud
))
2395 pmd
= pmd_offset(pud
, address
);
2396 if (!pmd_present(*pmd
))
2399 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2400 * materialize from under us.
2402 split_huge_page_pmd(mm
, pmd
);
2405 void __vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2406 unsigned long start
,
2411 * If the new start address isn't hpage aligned and it could
2412 * previously contain an hugepage: check if we need to split
2415 if (start
& ~HPAGE_PMD_MASK
&&
2416 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2417 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2418 split_huge_page_address(vma
->vm_mm
, start
);
2421 * If the new end address isn't hpage aligned and it could
2422 * previously contain an hugepage: check if we need to split
2425 if (end
& ~HPAGE_PMD_MASK
&&
2426 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2427 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2428 split_huge_page_address(vma
->vm_mm
, end
);
2431 * If we're also updating the vma->vm_next->vm_start, if the new
2432 * vm_next->vm_start isn't page aligned and it could previously
2433 * contain an hugepage: check if we need to split an huge pmd.
2435 if (adjust_next
> 0) {
2436 struct vm_area_struct
*next
= vma
->vm_next
;
2437 unsigned long nstart
= next
->vm_start
;
2438 nstart
+= adjust_next
<< PAGE_SHIFT
;
2439 if (nstart
& ~HPAGE_PMD_MASK
&&
2440 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2441 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2442 split_huge_page_address(next
->vm_mm
, nstart
);