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
);
173 int task_in_mem_cgroup(struct task_struct
*task
, const struct mem_cgroup
*mem
)
178 ret
= task
->mm
&& mm_cgroup(task
->mm
) == mem
;
184 * This routine assumes that the appropriate zone's lru lock is already held
186 void mem_cgroup_move_lists(struct page_cgroup
*pc
, bool active
)
188 struct mem_cgroup
*mem
;
192 mem
= pc
->mem_cgroup
;
194 spin_lock(&mem
->lru_lock
);
195 __mem_cgroup_move_lists(pc
, active
);
196 spin_unlock(&mem
->lru_lock
);
199 unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan
,
200 struct list_head
*dst
,
201 unsigned long *scanned
, int order
,
202 int mode
, struct zone
*z
,
203 struct mem_cgroup
*mem_cont
,
206 unsigned long nr_taken
= 0;
210 struct list_head
*src
;
211 struct page_cgroup
*pc
;
214 src
= &mem_cont
->active_list
;
216 src
= &mem_cont
->inactive_list
;
218 spin_lock(&mem_cont
->lru_lock
);
219 for (scan
= 0; scan
< nr_to_scan
&& !list_empty(src
); scan
++) {
220 pc
= list_entry(src
->prev
, struct page_cgroup
, lru
);
224 if (PageActive(page
) && !active
) {
225 __mem_cgroup_move_lists(pc
, true);
229 if (!PageActive(page
) && active
) {
230 __mem_cgroup_move_lists(pc
, false);
237 * TODO: make the active/inactive lists per zone
239 if (page_zone(page
) != z
)
243 * Check if the meta page went away from under us
245 if (!list_empty(&pc
->lru
))
246 list_move(&pc
->lru
, &pc_list
);
250 if (__isolate_lru_page(page
, mode
) == 0) {
251 list_move(&page
->lru
, dst
);
256 list_splice(&pc_list
, src
);
257 spin_unlock(&mem_cont
->lru_lock
);
264 * Charge the memory controller for page usage.
266 * 0 if the charge was successful
267 * < 0 if the cgroup is over its limit
269 int mem_cgroup_charge(struct page
*page
, struct mm_struct
*mm
,
272 struct mem_cgroup
*mem
;
273 struct page_cgroup
*pc
, *race_pc
;
275 unsigned long nr_retries
= MEM_CGROUP_RECLAIM_RETRIES
;
278 * Should page_cgroup's go to their own slab?
279 * One could optimize the performance of the charging routine
280 * by saving a bit in the page_flags and using it as a lock
281 * to see if the cgroup page already has a page_cgroup associated
285 lock_page_cgroup(page
);
286 pc
= page_get_page_cgroup(page
);
288 * The page_cgroup exists and the page has already been accounted
291 if (unlikely(!atomic_inc_not_zero(&pc
->ref_cnt
))) {
292 /* this page is under being uncharged ? */
293 unlock_page_cgroup(page
);
300 unlock_page_cgroup(page
);
302 pc
= kzalloc(sizeof(struct page_cgroup
), gfp_mask
);
308 * We always charge the cgroup the mm_struct belongs to
309 * the mm_struct's mem_cgroup changes on task migration if the
310 * thread group leader migrates. It's possible that mm is not
311 * set, if so charge the init_mm (happens for pagecache usage).
316 mem
= rcu_dereference(mm
->mem_cgroup
);
318 * For every charge from the cgroup, increment reference
325 * If we created the page_cgroup, we should free it on exceeding
328 while (res_counter_charge(&mem
->res
, PAGE_SIZE
)) {
329 bool is_atomic
= gfp_mask
& GFP_ATOMIC
;
331 * We cannot reclaim under GFP_ATOMIC, fail the charge
336 if (try_to_free_mem_cgroup_pages(mem
, gfp_mask
))
340 * try_to_free_mem_cgroup_pages() might not give us a full
341 * picture of reclaim. Some pages are reclaimed and might be
342 * moved to swap cache or just unmapped from the cgroup.
343 * Check the limit again to see if the reclaim reduced the
344 * current usage of the cgroup before giving up
346 if (res_counter_check_under_limit(&mem
->res
))
349 * Since we control both RSS and cache, we end up with a
350 * very interesting scenario where we end up reclaiming
351 * memory (essentially RSS), since the memory is pushed
352 * to swap cache, we eventually end up adding those
353 * pages back to our list. Hence we give ourselves a
354 * few chances before we fail
356 else if (nr_retries
--) {
357 congestion_wait(WRITE
, HZ
/10);
363 mem_cgroup_out_of_memory(mem
, GFP_KERNEL
);
367 lock_page_cgroup(page
);
369 * Check if somebody else beat us to allocating the page_cgroup
371 race_pc
= page_get_page_cgroup(page
);
375 atomic_inc(&pc
->ref_cnt
);
376 res_counter_uncharge(&mem
->res
, PAGE_SIZE
);
381 atomic_set(&pc
->ref_cnt
, 1);
382 pc
->mem_cgroup
= mem
;
384 page_assign_page_cgroup(page
, pc
);
386 spin_lock_irqsave(&mem
->lru_lock
, flags
);
387 list_add(&pc
->lru
, &mem
->active_list
);
388 spin_unlock_irqrestore(&mem
->lru_lock
, flags
);
391 unlock_page_cgroup(page
);
400 * See if the cached pages should be charged at all?
402 int mem_cgroup_cache_charge(struct page
*page
, struct mm_struct
*mm
,
405 struct mem_cgroup
*mem
;
409 mem
= rcu_dereference(mm
->mem_cgroup
);
410 if (mem
->control_type
== MEM_CGROUP_TYPE_ALL
)
411 return mem_cgroup_charge(page
, mm
, gfp_mask
);
417 * Uncharging is always a welcome operation, we never complain, simply
420 void mem_cgroup_uncharge(struct page_cgroup
*pc
)
422 struct mem_cgroup
*mem
;
427 * This can handle cases when a page is not charged at all and we
428 * are switching between handling the control_type.
433 if (atomic_dec_and_test(&pc
->ref_cnt
)) {
435 lock_page_cgroup(page
);
436 mem
= pc
->mem_cgroup
;
438 page_assign_page_cgroup(page
, NULL
);
439 unlock_page_cgroup(page
);
440 res_counter_uncharge(&mem
->res
, PAGE_SIZE
);
442 spin_lock_irqsave(&mem
->lru_lock
, flags
);
443 list_del_init(&pc
->lru
);
444 spin_unlock_irqrestore(&mem
->lru_lock
, flags
);
449 int mem_cgroup_write_strategy(char *buf
, unsigned long long *tmp
)
451 *tmp
= memparse(buf
, &buf
);
456 * Round up the value to the closest page size
458 *tmp
= ((*tmp
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
) << PAGE_SHIFT
;
462 static ssize_t
mem_cgroup_read(struct cgroup
*cont
,
463 struct cftype
*cft
, struct file
*file
,
464 char __user
*userbuf
, size_t nbytes
, loff_t
*ppos
)
466 return res_counter_read(&mem_cgroup_from_cont(cont
)->res
,
467 cft
->private, userbuf
, nbytes
, ppos
,
471 static ssize_t
mem_cgroup_write(struct cgroup
*cont
, struct cftype
*cft
,
472 struct file
*file
, const char __user
*userbuf
,
473 size_t nbytes
, loff_t
*ppos
)
475 return res_counter_write(&mem_cgroup_from_cont(cont
)->res
,
476 cft
->private, userbuf
, nbytes
, ppos
,
477 mem_cgroup_write_strategy
);
480 static ssize_t
mem_control_type_write(struct cgroup
*cont
,
481 struct cftype
*cft
, struct file
*file
,
482 const char __user
*userbuf
,
483 size_t nbytes
, loff_t
*pos
)
488 struct mem_cgroup
*mem
;
490 mem
= mem_cgroup_from_cont(cont
);
491 buf
= kmalloc(nbytes
+ 1, GFP_KERNEL
);
498 if (copy_from_user(buf
, userbuf
, nbytes
))
502 tmp
= simple_strtoul(buf
, &end
, 10);
506 if (tmp
<= MEM_CGROUP_TYPE_UNSPEC
|| tmp
>= MEM_CGROUP_TYPE_MAX
)
509 mem
->control_type
= tmp
;
517 static ssize_t
mem_control_type_read(struct cgroup
*cont
,
519 struct file
*file
, char __user
*userbuf
,
520 size_t nbytes
, loff_t
*ppos
)
524 struct mem_cgroup
*mem
;
526 mem
= mem_cgroup_from_cont(cont
);
528 val
= mem
->control_type
;
529 s
+= sprintf(s
, "%lu\n", val
);
530 return simple_read_from_buffer((void __user
*)userbuf
, nbytes
,
534 static struct cftype mem_cgroup_files
[] = {
536 .name
= "usage_in_bytes",
537 .private = RES_USAGE
,
538 .read
= mem_cgroup_read
,
541 .name
= "limit_in_bytes",
542 .private = RES_LIMIT
,
543 .write
= mem_cgroup_write
,
544 .read
= mem_cgroup_read
,
548 .private = RES_FAILCNT
,
549 .read
= mem_cgroup_read
,
552 .name
= "control_type",
553 .write
= mem_control_type_write
,
554 .read
= mem_control_type_read
,
558 static struct mem_cgroup init_mem_cgroup
;
560 static struct cgroup_subsys_state
*
561 mem_cgroup_create(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
563 struct mem_cgroup
*mem
;
565 if (unlikely((cont
->parent
) == NULL
)) {
566 mem
= &init_mem_cgroup
;
567 init_mm
.mem_cgroup
= mem
;
569 mem
= kzalloc(sizeof(struct mem_cgroup
), GFP_KERNEL
);
574 res_counter_init(&mem
->res
);
575 INIT_LIST_HEAD(&mem
->active_list
);
576 INIT_LIST_HEAD(&mem
->inactive_list
);
577 spin_lock_init(&mem
->lru_lock
);
578 mem
->control_type
= MEM_CGROUP_TYPE_ALL
;
582 static void mem_cgroup_destroy(struct cgroup_subsys
*ss
,
585 kfree(mem_cgroup_from_cont(cont
));
588 static int mem_cgroup_populate(struct cgroup_subsys
*ss
,
591 return cgroup_add_files(cont
, ss
, mem_cgroup_files
,
592 ARRAY_SIZE(mem_cgroup_files
));
595 static void mem_cgroup_move_task(struct cgroup_subsys
*ss
,
597 struct cgroup
*old_cont
,
598 struct task_struct
*p
)
600 struct mm_struct
*mm
;
601 struct mem_cgroup
*mem
, *old_mem
;
607 mem
= mem_cgroup_from_cont(cont
);
608 old_mem
= mem_cgroup_from_cont(old_cont
);
614 * Only thread group leaders are allowed to migrate, the mm_struct is
615 * in effect owned by the leader
617 if (p
->tgid
!= p
->pid
)
621 rcu_assign_pointer(mm
->mem_cgroup
, mem
);
622 css_put(&old_mem
->css
);
629 struct cgroup_subsys mem_cgroup_subsys
= {
631 .subsys_id
= mem_cgroup_subsys_id
,
632 .create
= mem_cgroup_create
,
633 .destroy
= mem_cgroup_destroy
,
634 .populate
= mem_cgroup_populate
,
635 .attach
= mem_cgroup_move_task
,