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 */
89 MEM_CGROUP_TYPE_UNSPEC
= 0,
90 MEM_CGROUP_TYPE_MAPPED
,
91 MEM_CGROUP_TYPE_CACHED
,
96 static struct mem_cgroup init_mem_cgroup
;
99 struct mem_cgroup
*mem_cgroup_from_cont(struct cgroup
*cont
)
101 return container_of(cgroup_subsys_state(cont
,
102 mem_cgroup_subsys_id
), struct mem_cgroup
,
107 struct mem_cgroup
*mem_cgroup_from_task(struct task_struct
*p
)
109 return container_of(task_subsys_state(p
, mem_cgroup_subsys_id
),
110 struct mem_cgroup
, css
);
113 void mm_init_cgroup(struct mm_struct
*mm
, struct task_struct
*p
)
115 struct mem_cgroup
*mem
;
117 mem
= mem_cgroup_from_task(p
);
119 mm
->mem_cgroup
= mem
;
122 void mm_free_cgroup(struct mm_struct
*mm
)
124 css_put(&mm
->mem_cgroup
->css
);
127 static inline int page_cgroup_locked(struct page
*page
)
129 return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT
,
133 void page_assign_page_cgroup(struct page
*page
, struct page_cgroup
*pc
)
138 * While resetting the page_cgroup we might not hold the
139 * page_cgroup lock. free_hot_cold_page() is an example
143 VM_BUG_ON(!page_cgroup_locked(page
));
144 locked
= (page
->page_cgroup
& PAGE_CGROUP_LOCK
);
145 page
->page_cgroup
= ((unsigned long)pc
| locked
);
148 struct page_cgroup
*page_get_page_cgroup(struct page
*page
)
150 return (struct page_cgroup
*)
151 (page
->page_cgroup
& ~PAGE_CGROUP_LOCK
);
154 static void __always_inline
lock_page_cgroup(struct page
*page
)
156 bit_spin_lock(PAGE_CGROUP_LOCK_BIT
, &page
->page_cgroup
);
157 VM_BUG_ON(!page_cgroup_locked(page
));
160 static void __always_inline
unlock_page_cgroup(struct page
*page
)
162 bit_spin_unlock(PAGE_CGROUP_LOCK_BIT
, &page
->page_cgroup
);
165 static void __mem_cgroup_move_lists(struct page_cgroup
*pc
, bool active
)
168 list_move(&pc
->lru
, &pc
->mem_cgroup
->active_list
);
170 list_move(&pc
->lru
, &pc
->mem_cgroup
->inactive_list
);
174 * This routine assumes that the appropriate zone's lru lock is already held
176 void mem_cgroup_move_lists(struct page_cgroup
*pc
, bool active
)
178 struct mem_cgroup
*mem
;
182 mem
= pc
->mem_cgroup
;
184 spin_lock(&mem
->lru_lock
);
185 __mem_cgroup_move_lists(pc
, active
);
186 spin_unlock(&mem
->lru_lock
);
189 unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan
,
190 struct list_head
*dst
,
191 unsigned long *scanned
, int order
,
192 int mode
, struct zone
*z
,
193 struct mem_cgroup
*mem_cont
,
196 unsigned long nr_taken
= 0;
200 struct list_head
*src
;
201 struct page_cgroup
*pc
;
204 src
= &mem_cont
->active_list
;
206 src
= &mem_cont
->inactive_list
;
208 spin_lock(&mem_cont
->lru_lock
);
209 for (scan
= 0; scan
< nr_to_scan
&& !list_empty(src
); scan
++) {
210 pc
= list_entry(src
->prev
, struct page_cgroup
, lru
);
214 if (PageActive(page
) && !active
) {
215 __mem_cgroup_move_lists(pc
, true);
219 if (!PageActive(page
) && active
) {
220 __mem_cgroup_move_lists(pc
, false);
227 * TODO: make the active/inactive lists per zone
229 if (page_zone(page
) != z
)
233 * Check if the meta page went away from under us
235 if (!list_empty(&pc
->lru
))
236 list_move(&pc
->lru
, &pc_list
);
240 if (__isolate_lru_page(page
, mode
) == 0) {
241 list_move(&page
->lru
, dst
);
246 list_splice(&pc_list
, src
);
247 spin_unlock(&mem_cont
->lru_lock
);
254 * Charge the memory controller for page usage.
256 * 0 if the charge was successful
257 * < 0 if the cgroup is over its limit
259 int mem_cgroup_charge(struct page
*page
, struct mm_struct
*mm
,
262 struct mem_cgroup
*mem
;
263 struct page_cgroup
*pc
, *race_pc
;
265 unsigned long nr_retries
= MEM_CGROUP_RECLAIM_RETRIES
;
268 * Should page_cgroup's go to their own slab?
269 * One could optimize the performance of the charging routine
270 * by saving a bit in the page_flags and using it as a lock
271 * to see if the cgroup page already has a page_cgroup associated
275 lock_page_cgroup(page
);
276 pc
= page_get_page_cgroup(page
);
278 * The page_cgroup exists and the page has already been accounted
281 if (unlikely(!atomic_inc_not_zero(&pc
->ref_cnt
))) {
282 /* this page is under being uncharged ? */
283 unlock_page_cgroup(page
);
290 unlock_page_cgroup(page
);
292 pc
= kzalloc(sizeof(struct page_cgroup
), gfp_mask
);
298 * We always charge the cgroup the mm_struct belongs to
299 * the mm_struct's mem_cgroup changes on task migration if the
300 * thread group leader migrates. It's possible that mm is not
301 * set, if so charge the init_mm (happens for pagecache usage).
306 mem
= rcu_dereference(mm
->mem_cgroup
);
308 * For every charge from the cgroup, increment reference
315 * If we created the page_cgroup, we should free it on exceeding
318 while (res_counter_charge(&mem
->res
, PAGE_SIZE
)) {
319 bool is_atomic
= gfp_mask
& GFP_ATOMIC
;
321 * We cannot reclaim under GFP_ATOMIC, fail the charge
326 if (try_to_free_mem_cgroup_pages(mem
, gfp_mask
))
330 * try_to_free_mem_cgroup_pages() might not give us a full
331 * picture of reclaim. Some pages are reclaimed and might be
332 * moved to swap cache or just unmapped from the cgroup.
333 * Check the limit again to see if the reclaim reduced the
334 * current usage of the cgroup before giving up
336 if (res_counter_check_under_limit(&mem
->res
))
339 * Since we control both RSS and cache, we end up with a
340 * very interesting scenario where we end up reclaiming
341 * memory (essentially RSS), since the memory is pushed
342 * to swap cache, we eventually end up adding those
343 * pages back to our list. Hence we give ourselves a
344 * few chances before we fail
346 else if (nr_retries
--) {
347 congestion_wait(WRITE
, HZ
/10);
353 mem_cgroup_out_of_memory(mem
, GFP_KERNEL
);
357 lock_page_cgroup(page
);
359 * Check if somebody else beat us to allocating the page_cgroup
361 race_pc
= page_get_page_cgroup(page
);
365 atomic_inc(&pc
->ref_cnt
);
366 res_counter_uncharge(&mem
->res
, PAGE_SIZE
);
371 atomic_set(&pc
->ref_cnt
, 1);
372 pc
->mem_cgroup
= mem
;
374 page_assign_page_cgroup(page
, pc
);
376 spin_lock_irqsave(&mem
->lru_lock
, flags
);
377 list_add(&pc
->lru
, &mem
->active_list
);
378 spin_unlock_irqrestore(&mem
->lru_lock
, flags
);
381 unlock_page_cgroup(page
);
390 * See if the cached pages should be charged at all?
392 int mem_cgroup_cache_charge(struct page
*page
, struct mm_struct
*mm
,
395 struct mem_cgroup
*mem
;
399 mem
= rcu_dereference(mm
->mem_cgroup
);
400 if (mem
->control_type
== MEM_CGROUP_TYPE_ALL
)
401 return mem_cgroup_charge(page
, mm
, gfp_mask
);
407 * Uncharging is always a welcome operation, we never complain, simply
410 void mem_cgroup_uncharge(struct page_cgroup
*pc
)
412 struct mem_cgroup
*mem
;
417 * This can handle cases when a page is not charged at all and we
418 * are switching between handling the control_type.
423 if (atomic_dec_and_test(&pc
->ref_cnt
)) {
425 lock_page_cgroup(page
);
426 mem
= pc
->mem_cgroup
;
428 page_assign_page_cgroup(page
, NULL
);
429 unlock_page_cgroup(page
);
430 res_counter_uncharge(&mem
->res
, PAGE_SIZE
);
432 spin_lock_irqsave(&mem
->lru_lock
, flags
);
433 list_del_init(&pc
->lru
);
434 spin_unlock_irqrestore(&mem
->lru_lock
, flags
);
439 int mem_cgroup_write_strategy(char *buf
, unsigned long long *tmp
)
441 *tmp
= memparse(buf
, &buf
);
446 * Round up the value to the closest page size
448 *tmp
= ((*tmp
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
) << PAGE_SHIFT
;
452 static ssize_t
mem_cgroup_read(struct cgroup
*cont
,
453 struct cftype
*cft
, struct file
*file
,
454 char __user
*userbuf
, size_t nbytes
, loff_t
*ppos
)
456 return res_counter_read(&mem_cgroup_from_cont(cont
)->res
,
457 cft
->private, userbuf
, nbytes
, ppos
,
461 static ssize_t
mem_cgroup_write(struct cgroup
*cont
, struct cftype
*cft
,
462 struct file
*file
, const char __user
*userbuf
,
463 size_t nbytes
, loff_t
*ppos
)
465 return res_counter_write(&mem_cgroup_from_cont(cont
)->res
,
466 cft
->private, userbuf
, nbytes
, ppos
,
467 mem_cgroup_write_strategy
);
470 static ssize_t
mem_control_type_write(struct cgroup
*cont
,
471 struct cftype
*cft
, struct file
*file
,
472 const char __user
*userbuf
,
473 size_t nbytes
, loff_t
*pos
)
478 struct mem_cgroup
*mem
;
480 mem
= mem_cgroup_from_cont(cont
);
481 buf
= kmalloc(nbytes
+ 1, GFP_KERNEL
);
488 if (copy_from_user(buf
, userbuf
, nbytes
))
492 tmp
= simple_strtoul(buf
, &end
, 10);
496 if (tmp
<= MEM_CGROUP_TYPE_UNSPEC
|| tmp
>= MEM_CGROUP_TYPE_MAX
)
499 mem
->control_type
= tmp
;
507 static ssize_t
mem_control_type_read(struct cgroup
*cont
,
509 struct file
*file
, char __user
*userbuf
,
510 size_t nbytes
, loff_t
*ppos
)
514 struct mem_cgroup
*mem
;
516 mem
= mem_cgroup_from_cont(cont
);
518 val
= mem
->control_type
;
519 s
+= sprintf(s
, "%lu\n", val
);
520 return simple_read_from_buffer((void __user
*)userbuf
, nbytes
,
524 static struct cftype mem_cgroup_files
[] = {
526 .name
= "usage_in_bytes",
527 .private = RES_USAGE
,
528 .read
= mem_cgroup_read
,
531 .name
= "limit_in_bytes",
532 .private = RES_LIMIT
,
533 .write
= mem_cgroup_write
,
534 .read
= mem_cgroup_read
,
538 .private = RES_FAILCNT
,
539 .read
= mem_cgroup_read
,
542 .name
= "control_type",
543 .write
= mem_control_type_write
,
544 .read
= mem_control_type_read
,
548 static struct mem_cgroup init_mem_cgroup
;
550 static struct cgroup_subsys_state
*
551 mem_cgroup_create(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
553 struct mem_cgroup
*mem
;
555 if (unlikely((cont
->parent
) == NULL
)) {
556 mem
= &init_mem_cgroup
;
557 init_mm
.mem_cgroup
= mem
;
559 mem
= kzalloc(sizeof(struct mem_cgroup
), GFP_KERNEL
);
564 res_counter_init(&mem
->res
);
565 INIT_LIST_HEAD(&mem
->active_list
);
566 INIT_LIST_HEAD(&mem
->inactive_list
);
567 spin_lock_init(&mem
->lru_lock
);
568 mem
->control_type
= MEM_CGROUP_TYPE_ALL
;
572 static void mem_cgroup_destroy(struct cgroup_subsys
*ss
,
575 kfree(mem_cgroup_from_cont(cont
));
578 static int mem_cgroup_populate(struct cgroup_subsys
*ss
,
581 return cgroup_add_files(cont
, ss
, mem_cgroup_files
,
582 ARRAY_SIZE(mem_cgroup_files
));
585 static void mem_cgroup_move_task(struct cgroup_subsys
*ss
,
587 struct cgroup
*old_cont
,
588 struct task_struct
*p
)
590 struct mm_struct
*mm
;
591 struct mem_cgroup
*mem
, *old_mem
;
597 mem
= mem_cgroup_from_cont(cont
);
598 old_mem
= mem_cgroup_from_cont(old_cont
);
604 * Only thread group leaders are allowed to migrate, the mm_struct is
605 * in effect owned by the leader
607 if (p
->tgid
!= p
->pid
)
611 rcu_assign_pointer(mm
->mem_cgroup
, mem
);
612 css_put(&old_mem
->css
);
619 struct cgroup_subsys mem_cgroup_subsys
= {
621 .subsys_id
= mem_cgroup_subsys_id
,
622 .create
= mem_cgroup_create
,
623 .destroy
= mem_cgroup_destroy
,
624 .populate
= mem_cgroup_populate
,
625 .attach
= mem_cgroup_move_task
,