1 /* memcontrol.c - Memory Controller
3 * Copyright IBM Corporation, 2007
4 * Author Balbir Singh <balbir@linux.vnet.ibm.com>
6 * Copyright 2007 OpenVZ SWsoft Inc
7 * Author: Pavel Emelianov <xemul@openvz.org>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
20 #include <linux/res_counter.h>
21 #include <linux/memcontrol.h>
22 #include <linux/cgroup.h>
24 #include <linux/page-flags.h>
25 #include <linux/backing-dev.h>
26 #include <linux/bit_spinlock.h>
27 #include <linux/rcupdate.h>
28 #include <linux/swap.h>
29 #include <linux/spinlock.h>
32 #include <asm/uaccess.h>
34 struct cgroup_subsys mem_cgroup_subsys
;
35 static const int MEM_CGROUP_RECLAIM_RETRIES
= 5;
38 * The memory controller data structure. The memory controller controls both
39 * page cache and RSS per cgroup. We would eventually like to provide
40 * statistics based on the statistics developed by Rik Van Riel for clock-pro,
41 * to help the administrator determine what knobs to tune.
43 * TODO: Add a water mark for the memory controller. Reclaim will begin when
44 * we hit the water mark. May be even add a low water mark, such that
45 * no reclaim occurs from a cgroup at it's low water mark, this is
46 * a feature that will be implemented much later in the future.
49 struct cgroup_subsys_state css
;
51 * the counter to account for memory usage
53 struct res_counter res
;
55 * Per cgroup active and inactive list, similar to the
57 * TODO: Consider making these lists per zone
59 struct list_head active_list
;
60 struct list_head inactive_list
;
62 * spin_lock to protect the per cgroup LRU
65 unsigned long control_type
; /* control RSS or RSS+Pagecache */
69 * We use the lower bit of the page->page_cgroup pointer as a bit spin
70 * lock. We need to ensure that page->page_cgroup is atleast two
71 * byte aligned (based on comments from Nick Piggin)
73 #define PAGE_CGROUP_LOCK_BIT 0x0
74 #define PAGE_CGROUP_LOCK (1 << PAGE_CGROUP_LOCK_BIT)
77 * A page_cgroup page is associated with every page descriptor. The
78 * page_cgroup helps us identify information about the cgroup
81 struct list_head lru
; /* per cgroup LRU list */
83 struct mem_cgroup
*mem_cgroup
;
84 atomic_t ref_cnt
; /* Helpful when pages move b/w */
85 /* mapped and cached states */
88 #define PAGE_CGROUP_FLAG_CACHE (0x1) /* charged as cache */
91 MEM_CGROUP_TYPE_UNSPEC
= 0,
92 MEM_CGROUP_TYPE_MAPPED
,
93 MEM_CGROUP_TYPE_CACHED
,
99 MEM_CGROUP_CHARGE_TYPE_CACHE
= 0,
100 MEM_CGROUP_CHARGE_TYPE_MAPPED
,
103 static struct mem_cgroup init_mem_cgroup
;
106 struct mem_cgroup
*mem_cgroup_from_cont(struct cgroup
*cont
)
108 return container_of(cgroup_subsys_state(cont
,
109 mem_cgroup_subsys_id
), struct mem_cgroup
,
114 struct mem_cgroup
*mem_cgroup_from_task(struct task_struct
*p
)
116 return container_of(task_subsys_state(p
, mem_cgroup_subsys_id
),
117 struct mem_cgroup
, css
);
120 void mm_init_cgroup(struct mm_struct
*mm
, struct task_struct
*p
)
122 struct mem_cgroup
*mem
;
124 mem
= mem_cgroup_from_task(p
);
126 mm
->mem_cgroup
= mem
;
129 void mm_free_cgroup(struct mm_struct
*mm
)
131 css_put(&mm
->mem_cgroup
->css
);
134 static inline int page_cgroup_locked(struct page
*page
)
136 return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT
,
140 void page_assign_page_cgroup(struct page
*page
, struct page_cgroup
*pc
)
145 * While resetting the page_cgroup we might not hold the
146 * page_cgroup lock. free_hot_cold_page() is an example
150 VM_BUG_ON(!page_cgroup_locked(page
));
151 locked
= (page
->page_cgroup
& PAGE_CGROUP_LOCK
);
152 page
->page_cgroup
= ((unsigned long)pc
| locked
);
155 struct page_cgroup
*page_get_page_cgroup(struct page
*page
)
157 return (struct page_cgroup
*)
158 (page
->page_cgroup
& ~PAGE_CGROUP_LOCK
);
161 static void __always_inline
lock_page_cgroup(struct page
*page
)
163 bit_spin_lock(PAGE_CGROUP_LOCK_BIT
, &page
->page_cgroup
);
164 VM_BUG_ON(!page_cgroup_locked(page
));
167 static void __always_inline
unlock_page_cgroup(struct page
*page
)
169 bit_spin_unlock(PAGE_CGROUP_LOCK_BIT
, &page
->page_cgroup
);
173 * Tie new page_cgroup to struct page under lock_page_cgroup()
174 * This can fail if the page has been tied to a page_cgroup.
175 * If success, returns 0.
178 page_cgroup_assign_new_page_cgroup(struct page
*page
, struct page_cgroup
*pc
)
182 lock_page_cgroup(page
);
183 if (!page_get_page_cgroup(page
))
184 page_assign_page_cgroup(page
, pc
);
185 else /* A page is tied to other pc. */
187 unlock_page_cgroup(page
);
192 * Clear page->page_cgroup member under lock_page_cgroup().
193 * If given "pc" value is different from one page->page_cgroup,
194 * page->cgroup is not cleared.
195 * Returns a value of page->page_cgroup at lock taken.
196 * A can can detect failure of clearing by following
197 * clear_page_cgroup(page, pc) == pc
200 static inline struct page_cgroup
*
201 clear_page_cgroup(struct page
*page
, struct page_cgroup
*pc
)
203 struct page_cgroup
*ret
;
205 lock_page_cgroup(page
);
206 ret
= page_get_page_cgroup(page
);
207 if (likely(ret
== pc
))
208 page_assign_page_cgroup(page
, NULL
);
209 unlock_page_cgroup(page
);
214 static void __mem_cgroup_move_lists(struct page_cgroup
*pc
, bool active
)
217 list_move(&pc
->lru
, &pc
->mem_cgroup
->active_list
);
219 list_move(&pc
->lru
, &pc
->mem_cgroup
->inactive_list
);
222 int task_in_mem_cgroup(struct task_struct
*task
, const struct mem_cgroup
*mem
)
227 ret
= task
->mm
&& mm_cgroup(task
->mm
) == mem
;
233 * This routine assumes that the appropriate zone's lru lock is already held
235 void mem_cgroup_move_lists(struct page_cgroup
*pc
, bool active
)
237 struct mem_cgroup
*mem
;
241 mem
= pc
->mem_cgroup
;
243 spin_lock(&mem
->lru_lock
);
244 __mem_cgroup_move_lists(pc
, active
);
245 spin_unlock(&mem
->lru_lock
);
248 unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan
,
249 struct list_head
*dst
,
250 unsigned long *scanned
, int order
,
251 int mode
, struct zone
*z
,
252 struct mem_cgroup
*mem_cont
,
255 unsigned long nr_taken
= 0;
259 struct list_head
*src
;
260 struct page_cgroup
*pc
, *tmp
;
263 src
= &mem_cont
->active_list
;
265 src
= &mem_cont
->inactive_list
;
267 spin_lock(&mem_cont
->lru_lock
);
269 list_for_each_entry_safe_reverse(pc
, tmp
, src
, lru
) {
270 if (scan
>= nr_to_scan
)
275 if (unlikely(!PageLRU(page
)))
278 if (PageActive(page
) && !active
) {
279 __mem_cgroup_move_lists(pc
, true);
282 if (!PageActive(page
) && active
) {
283 __mem_cgroup_move_lists(pc
, false);
289 * TODO: make the active/inactive lists per zone
291 if (page_zone(page
) != z
)
295 list_move(&pc
->lru
, &pc_list
);
297 if (__isolate_lru_page(page
, mode
) == 0) {
298 list_move(&page
->lru
, dst
);
303 list_splice(&pc_list
, src
);
304 spin_unlock(&mem_cont
->lru_lock
);
311 * Charge the memory controller for page usage.
313 * 0 if the charge was successful
314 * < 0 if the cgroup is over its limit
316 static int mem_cgroup_charge_common(struct page
*page
, struct mm_struct
*mm
,
317 gfp_t gfp_mask
, enum charge_type ctype
)
319 struct mem_cgroup
*mem
;
320 struct page_cgroup
*pc
;
322 unsigned long nr_retries
= MEM_CGROUP_RECLAIM_RETRIES
;
325 * Should page_cgroup's go to their own slab?
326 * One could optimize the performance of the charging routine
327 * by saving a bit in the page_flags and using it as a lock
328 * to see if the cgroup page already has a page_cgroup associated
332 lock_page_cgroup(page
);
333 pc
= page_get_page_cgroup(page
);
335 * The page_cgroup exists and the page has already been accounted
338 if (unlikely(!atomic_inc_not_zero(&pc
->ref_cnt
))) {
339 /* this page is under being uncharged ? */
340 unlock_page_cgroup(page
);
344 unlock_page_cgroup(page
);
349 unlock_page_cgroup(page
);
351 pc
= kzalloc(sizeof(struct page_cgroup
), gfp_mask
);
357 * We always charge the cgroup the mm_struct belongs to
358 * the mm_struct's mem_cgroup changes on task migration if the
359 * thread group leader migrates. It's possible that mm is not
360 * set, if so charge the init_mm (happens for pagecache usage).
365 mem
= rcu_dereference(mm
->mem_cgroup
);
367 * For every charge from the cgroup, increment reference
374 * If we created the page_cgroup, we should free it on exceeding
377 while (res_counter_charge(&mem
->res
, PAGE_SIZE
)) {
378 bool is_atomic
= gfp_mask
& GFP_ATOMIC
;
380 * We cannot reclaim under GFP_ATOMIC, fail the charge
385 if (try_to_free_mem_cgroup_pages(mem
, gfp_mask
))
389 * try_to_free_mem_cgroup_pages() might not give us a full
390 * picture of reclaim. Some pages are reclaimed and might be
391 * moved to swap cache or just unmapped from the cgroup.
392 * Check the limit again to see if the reclaim reduced the
393 * current usage of the cgroup before giving up
395 if (res_counter_check_under_limit(&mem
->res
))
398 * Since we control both RSS and cache, we end up with a
399 * very interesting scenario where we end up reclaiming
400 * memory (essentially RSS), since the memory is pushed
401 * to swap cache, we eventually end up adding those
402 * pages back to our list. Hence we give ourselves a
403 * few chances before we fail
405 else if (nr_retries
--) {
406 congestion_wait(WRITE
, HZ
/10);
412 mem_cgroup_out_of_memory(mem
, GFP_KERNEL
);
416 atomic_set(&pc
->ref_cnt
, 1);
417 pc
->mem_cgroup
= mem
;
420 if (ctype
== MEM_CGROUP_CHARGE_TYPE_CACHE
)
421 pc
->flags
|= PAGE_CGROUP_FLAG_CACHE
;
422 if (page_cgroup_assign_new_page_cgroup(page
, pc
)) {
424 * an another charge is added to this page already.
425 * we do take lock_page_cgroup(page) again and read
426 * page->cgroup, increment refcnt.... just retry is OK.
428 res_counter_uncharge(&mem
->res
, PAGE_SIZE
);
434 spin_lock_irqsave(&mem
->lru_lock
, flags
);
435 list_add(&pc
->lru
, &mem
->active_list
);
436 spin_unlock_irqrestore(&mem
->lru_lock
, flags
);
446 int mem_cgroup_charge(struct page
*page
, struct mm_struct
*mm
,
449 return mem_cgroup_charge_common(page
, mm
, gfp_mask
,
450 MEM_CGROUP_CHARGE_TYPE_MAPPED
);
454 * See if the cached pages should be charged at all?
456 int mem_cgroup_cache_charge(struct page
*page
, struct mm_struct
*mm
,
460 struct mem_cgroup
*mem
;
465 mem
= rcu_dereference(mm
->mem_cgroup
);
468 if (mem
->control_type
== MEM_CGROUP_TYPE_ALL
)
469 ret
= mem_cgroup_charge_common(page
, mm
, gfp_mask
,
470 MEM_CGROUP_CHARGE_TYPE_CACHE
);
476 * Uncharging is always a welcome operation, we never complain, simply
479 void mem_cgroup_uncharge(struct page_cgroup
*pc
)
481 struct mem_cgroup
*mem
;
486 * This can handle cases when a page is not charged at all and we
487 * are switching between handling the control_type.
492 if (atomic_dec_and_test(&pc
->ref_cnt
)) {
495 * get page->cgroup and clear it under lock.
496 * force_empty can drop page->cgroup without checking refcnt.
498 if (clear_page_cgroup(page
, pc
) == pc
) {
499 mem
= pc
->mem_cgroup
;
501 res_counter_uncharge(&mem
->res
, PAGE_SIZE
);
502 spin_lock_irqsave(&mem
->lru_lock
, flags
);
503 list_del_init(&pc
->lru
);
504 spin_unlock_irqrestore(&mem
->lru_lock
, flags
);
510 * Returns non-zero if a page (under migration) has valid page_cgroup member.
511 * Refcnt of page_cgroup is incremented.
514 int mem_cgroup_prepare_migration(struct page
*page
)
516 struct page_cgroup
*pc
;
518 lock_page_cgroup(page
);
519 pc
= page_get_page_cgroup(page
);
520 if (pc
&& atomic_inc_not_zero(&pc
->ref_cnt
))
522 unlock_page_cgroup(page
);
526 void mem_cgroup_end_migration(struct page
*page
)
528 struct page_cgroup
*pc
= page_get_page_cgroup(page
);
529 mem_cgroup_uncharge(pc
);
532 * We know both *page* and *newpage* are now not-on-LRU and Pg_locked.
533 * And no race with uncharge() routines because page_cgroup for *page*
534 * has extra one reference by mem_cgroup_prepare_migration.
537 void mem_cgroup_page_migration(struct page
*page
, struct page
*newpage
)
539 struct page_cgroup
*pc
;
541 pc
= page_get_page_cgroup(page
);
544 if (clear_page_cgroup(page
, pc
) != pc
)
547 lock_page_cgroup(newpage
);
548 page_assign_page_cgroup(newpage
, pc
);
549 unlock_page_cgroup(newpage
);
554 * This routine traverse page_cgroup in given list and drop them all.
555 * This routine ignores page_cgroup->ref_cnt.
556 * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
558 #define FORCE_UNCHARGE_BATCH (128)
560 mem_cgroup_force_empty_list(struct mem_cgroup
*mem
, struct list_head
*list
)
562 struct page_cgroup
*pc
;
568 count
= FORCE_UNCHARGE_BATCH
;
569 spin_lock_irqsave(&mem
->lru_lock
, flags
);
571 while (--count
&& !list_empty(list
)) {
572 pc
= list_entry(list
->prev
, struct page_cgroup
, lru
);
574 /* Avoid race with charge */
575 atomic_set(&pc
->ref_cnt
, 0);
576 if (clear_page_cgroup(page
, pc
) == pc
) {
578 res_counter_uncharge(&mem
->res
, PAGE_SIZE
);
579 list_del_init(&pc
->lru
);
581 } else /* being uncharged ? ...do relax */
584 spin_unlock_irqrestore(&mem
->lru_lock
, flags
);
585 if (!list_empty(list
)) {
593 * make mem_cgroup's charge to be 0 if there is no task.
594 * This enables deleting this mem_cgroup.
597 int mem_cgroup_force_empty(struct mem_cgroup
*mem
)
602 * page reclaim code (kswapd etc..) will move pages between
603 ` * active_list <-> inactive_list while we don't take a lock.
604 * So, we have to do loop here until all lists are empty.
606 while (!(list_empty(&mem
->active_list
) &&
607 list_empty(&mem
->inactive_list
))) {
608 if (atomic_read(&mem
->css
.cgroup
->count
) > 0)
610 /* drop all page_cgroup in active_list */
611 mem_cgroup_force_empty_list(mem
, &mem
->active_list
);
612 /* drop all page_cgroup in inactive_list */
613 mem_cgroup_force_empty_list(mem
, &mem
->inactive_list
);
623 int mem_cgroup_write_strategy(char *buf
, unsigned long long *tmp
)
625 *tmp
= memparse(buf
, &buf
);
630 * Round up the value to the closest page size
632 *tmp
= ((*tmp
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
) << PAGE_SHIFT
;
636 static ssize_t
mem_cgroup_read(struct cgroup
*cont
,
637 struct cftype
*cft
, struct file
*file
,
638 char __user
*userbuf
, size_t nbytes
, loff_t
*ppos
)
640 return res_counter_read(&mem_cgroup_from_cont(cont
)->res
,
641 cft
->private, userbuf
, nbytes
, ppos
,
645 static ssize_t
mem_cgroup_write(struct cgroup
*cont
, struct cftype
*cft
,
646 struct file
*file
, const char __user
*userbuf
,
647 size_t nbytes
, loff_t
*ppos
)
649 return res_counter_write(&mem_cgroup_from_cont(cont
)->res
,
650 cft
->private, userbuf
, nbytes
, ppos
,
651 mem_cgroup_write_strategy
);
654 static ssize_t
mem_control_type_write(struct cgroup
*cont
,
655 struct cftype
*cft
, struct file
*file
,
656 const char __user
*userbuf
,
657 size_t nbytes
, loff_t
*pos
)
662 struct mem_cgroup
*mem
;
664 mem
= mem_cgroup_from_cont(cont
);
665 buf
= kmalloc(nbytes
+ 1, GFP_KERNEL
);
672 if (copy_from_user(buf
, userbuf
, nbytes
))
676 tmp
= simple_strtoul(buf
, &end
, 10);
680 if (tmp
<= MEM_CGROUP_TYPE_UNSPEC
|| tmp
>= MEM_CGROUP_TYPE_MAX
)
683 mem
->control_type
= tmp
;
691 static ssize_t
mem_control_type_read(struct cgroup
*cont
,
693 struct file
*file
, char __user
*userbuf
,
694 size_t nbytes
, loff_t
*ppos
)
698 struct mem_cgroup
*mem
;
700 mem
= mem_cgroup_from_cont(cont
);
702 val
= mem
->control_type
;
703 s
+= sprintf(s
, "%lu\n", val
);
704 return simple_read_from_buffer((void __user
*)userbuf
, nbytes
,
709 static ssize_t
mem_force_empty_write(struct cgroup
*cont
,
710 struct cftype
*cft
, struct file
*file
,
711 const char __user
*userbuf
,
712 size_t nbytes
, loff_t
*ppos
)
714 struct mem_cgroup
*mem
= mem_cgroup_from_cont(cont
);
716 ret
= mem_cgroup_force_empty(mem
);
723 * Note: This should be removed if cgroup supports write-only file.
726 static ssize_t
mem_force_empty_read(struct cgroup
*cont
,
728 struct file
*file
, char __user
*userbuf
,
729 size_t nbytes
, loff_t
*ppos
)
735 static struct cftype mem_cgroup_files
[] = {
737 .name
= "usage_in_bytes",
738 .private = RES_USAGE
,
739 .read
= mem_cgroup_read
,
742 .name
= "limit_in_bytes",
743 .private = RES_LIMIT
,
744 .write
= mem_cgroup_write
,
745 .read
= mem_cgroup_read
,
749 .private = RES_FAILCNT
,
750 .read
= mem_cgroup_read
,
753 .name
= "control_type",
754 .write
= mem_control_type_write
,
755 .read
= mem_control_type_read
,
758 .name
= "force_empty",
759 .write
= mem_force_empty_write
,
760 .read
= mem_force_empty_read
,
764 static struct mem_cgroup init_mem_cgroup
;
766 static struct cgroup_subsys_state
*
767 mem_cgroup_create(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
769 struct mem_cgroup
*mem
;
771 if (unlikely((cont
->parent
) == NULL
)) {
772 mem
= &init_mem_cgroup
;
773 init_mm
.mem_cgroup
= mem
;
775 mem
= kzalloc(sizeof(struct mem_cgroup
), GFP_KERNEL
);
780 res_counter_init(&mem
->res
);
781 INIT_LIST_HEAD(&mem
->active_list
);
782 INIT_LIST_HEAD(&mem
->inactive_list
);
783 spin_lock_init(&mem
->lru_lock
);
784 mem
->control_type
= MEM_CGROUP_TYPE_ALL
;
788 static void mem_cgroup_destroy(struct cgroup_subsys
*ss
,
791 kfree(mem_cgroup_from_cont(cont
));
794 static int mem_cgroup_populate(struct cgroup_subsys
*ss
,
797 return cgroup_add_files(cont
, ss
, mem_cgroup_files
,
798 ARRAY_SIZE(mem_cgroup_files
));
801 static void mem_cgroup_move_task(struct cgroup_subsys
*ss
,
803 struct cgroup
*old_cont
,
804 struct task_struct
*p
)
806 struct mm_struct
*mm
;
807 struct mem_cgroup
*mem
, *old_mem
;
813 mem
= mem_cgroup_from_cont(cont
);
814 old_mem
= mem_cgroup_from_cont(old_cont
);
820 * Only thread group leaders are allowed to migrate, the mm_struct is
821 * in effect owned by the leader
823 if (p
->tgid
!= p
->pid
)
827 rcu_assign_pointer(mm
->mem_cgroup
, mem
);
828 css_put(&old_mem
->css
);
835 struct cgroup_subsys mem_cgroup_subsys
= {
837 .subsys_id
= mem_cgroup_subsys_id
,
838 .create
= mem_cgroup_create
,
839 .destroy
= mem_cgroup_destroy
,
840 .populate
= mem_cgroup_populate
,
841 .attach
= mem_cgroup_move_task
,