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 */
89 #define PAGE_CGROUP_FLAG_ACTIVE (0x2) /* page is active in this cgroup */
92 MEM_CGROUP_TYPE_UNSPEC = 0,
93 MEM_CGROUP_TYPE_MAPPED,
94 MEM_CGROUP_TYPE_CACHED,
100 MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
101 MEM_CGROUP_CHARGE_TYPE_MAPPED,
104 static struct mem_cgroup init_mem_cgroup;
107 struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
109 return container_of(cgroup_subsys_state(cont,
110 mem_cgroup_subsys_id), struct mem_cgroup,
115 struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
117 return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
118 struct mem_cgroup, css);
121 void mm_init_cgroup(struct mm_struct *mm, struct task_struct *p)
123 struct mem_cgroup *mem;
125 mem = mem_cgroup_from_task(p);
127 mm->mem_cgroup = mem;
130 void mm_free_cgroup(struct mm_struct *mm)
132 css_put(&mm->mem_cgroup->css);
135 static inline int page_cgroup_locked(struct page *page)
137 return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT,
141 void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
146 * While resetting the page_cgroup we might not hold the
147 * page_cgroup lock. free_hot_cold_page() is an example
151 VM_BUG_ON(!page_cgroup_locked(page));
152 locked = (page->page_cgroup & PAGE_CGROUP_LOCK);
153 page->page_cgroup = ((unsigned long)pc | locked);
156 struct page_cgroup *page_get_page_cgroup(struct page *page)
158 return (struct page_cgroup *)
159 (page->page_cgroup & ~PAGE_CGROUP_LOCK);
162 static void __always_inline lock_page_cgroup(struct page *page)
164 bit_spin_lock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
165 VM_BUG_ON(!page_cgroup_locked(page));
168 static void __always_inline unlock_page_cgroup(struct page *page)
170 bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
174 * Tie new page_cgroup to struct page under lock_page_cgroup()
175 * This can fail if the page has been tied to a page_cgroup.
176 * If success, returns 0.
179 page_cgroup_assign_new_page_cgroup(struct page *page, struct page_cgroup *pc)
183 lock_page_cgroup(page);
184 if (!page_get_page_cgroup(page))
185 page_assign_page_cgroup(page, pc);
186 else /* A page is tied to other pc. */
188 unlock_page_cgroup(page);
193 * Clear page->page_cgroup member under lock_page_cgroup().
194 * If given "pc" value is different from one page->page_cgroup,
195 * page->cgroup is not cleared.
196 * Returns a value of page->page_cgroup at lock taken.
197 * A can can detect failure of clearing by following
198 * clear_page_cgroup(page, pc) == pc
201 static inline struct page_cgroup *
202 clear_page_cgroup(struct page *page, struct page_cgroup *pc)
204 struct page_cgroup *ret;
206 lock_page_cgroup(page);
207 ret = page_get_page_cgroup(page);
208 if (likely(ret == pc))
209 page_assign_page_cgroup(page, NULL);
210 unlock_page_cgroup(page);
215 static void __mem_cgroup_move_lists(struct page_cgroup *pc, bool active)
218 pc->flags |= PAGE_CGROUP_FLAG_ACTIVE;
219 list_move(&pc->lru, &pc->mem_cgroup->active_list);
221 pc->flags &= ~PAGE_CGROUP_FLAG_ACTIVE;
222 list_move(&pc->lru, &pc->mem_cgroup->inactive_list);
226 int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
231 ret = task->mm && mm_cgroup(task->mm) == mem;
237 * This routine assumes that the appropriate zone's lru lock is already held
239 void mem_cgroup_move_lists(struct page_cgroup *pc, bool active)
241 struct mem_cgroup *mem;
245 mem = pc->mem_cgroup;
247 spin_lock(&mem->lru_lock);
248 __mem_cgroup_move_lists(pc, active);
249 spin_unlock(&mem->lru_lock);
252 unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
253 struct list_head *dst,
254 unsigned long *scanned, int order,
255 int mode, struct zone *z,
256 struct mem_cgroup *mem_cont,
259 unsigned long nr_taken = 0;
263 struct list_head *src;
264 struct page_cgroup *pc, *tmp;
267 src = &mem_cont->active_list;
269 src = &mem_cont->inactive_list;
271 spin_lock(&mem_cont->lru_lock);
273 list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
274 if (scan >= nr_to_scan)
279 if (unlikely(!PageLRU(page)))
282 if (PageActive(page) && !active) {
283 __mem_cgroup_move_lists(pc, true);
286 if (!PageActive(page) && active) {
287 __mem_cgroup_move_lists(pc, false);
293 * TODO: make the active/inactive lists per zone
295 if (page_zone(page) != z)
299 list_move(&pc->lru, &pc_list);
301 if (__isolate_lru_page(page, mode) == 0) {
302 list_move(&page->lru, dst);
307 list_splice(&pc_list, src);
308 spin_unlock(&mem_cont->lru_lock);
315 * Charge the memory controller for page usage.
317 * 0 if the charge was successful
318 * < 0 if the cgroup is over its limit
320 static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
321 gfp_t gfp_mask, enum charge_type ctype)
323 struct mem_cgroup *mem;
324 struct page_cgroup *pc;
326 unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
329 * Should page_cgroup's go to their own slab?
330 * One could optimize the performance of the charging routine
331 * by saving a bit in the page_flags and using it as a lock
332 * to see if the cgroup page already has a page_cgroup associated
337 lock_page_cgroup(page);
338 pc = page_get_page_cgroup(page);
340 * The page_cgroup exists and
341 * the page has already been accounted.
344 if (unlikely(!atomic_inc_not_zero(&pc->ref_cnt))) {
345 /* this page is under being uncharged ? */
346 unlock_page_cgroup(page);
350 unlock_page_cgroup(page);
354 unlock_page_cgroup(page);
357 pc = kzalloc(sizeof(struct page_cgroup), gfp_mask);
362 * We always charge the cgroup the mm_struct belongs to.
363 * The mm_struct's mem_cgroup changes on task migration if the
364 * thread group leader migrates. It's possible that mm is not
365 * set, if so charge the init_mm (happens for pagecache usage).
371 mem = rcu_dereference(mm->mem_cgroup);
373 * For every charge from the cgroup, increment reference
380 * If we created the page_cgroup, we should free it on exceeding
383 while (res_counter_charge(&mem->res, PAGE_SIZE)) {
384 if (!(gfp_mask & __GFP_WAIT))
387 if (try_to_free_mem_cgroup_pages(mem, gfp_mask))
391 * try_to_free_mem_cgroup_pages() might not give us a full
392 * picture of reclaim. Some pages are reclaimed and might be
393 * moved to swap cache or just unmapped from the cgroup.
394 * Check the limit again to see if the reclaim reduced the
395 * current usage of the cgroup before giving up
397 if (res_counter_check_under_limit(&mem->res))
401 mem_cgroup_out_of_memory(mem, gfp_mask);
404 congestion_wait(WRITE, HZ/10);
407 atomic_set(&pc->ref_cnt, 1);
408 pc->mem_cgroup = mem;
410 pc->flags = PAGE_CGROUP_FLAG_ACTIVE;
411 if (ctype == MEM_CGROUP_CHARGE_TYPE_CACHE)
412 pc->flags |= PAGE_CGROUP_FLAG_CACHE;
414 if (!page || page_cgroup_assign_new_page_cgroup(page, pc)) {
416 * Another charge has been added to this page already.
417 * We take lock_page_cgroup(page) again and read
418 * page->cgroup, increment refcnt.... just retry is OK.
420 res_counter_uncharge(&mem->res, PAGE_SIZE);
428 spin_lock_irqsave(&mem->lru_lock, flags);
429 list_add(&pc->lru, &mem->active_list);
430 spin_unlock_irqrestore(&mem->lru_lock, flags);
441 int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
444 return mem_cgroup_charge_common(page, mm, gfp_mask,
445 MEM_CGROUP_CHARGE_TYPE_MAPPED);
449 * See if the cached pages should be charged at all?
451 int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
455 struct mem_cgroup *mem;
460 mem = rcu_dereference(mm->mem_cgroup);
463 if (mem->control_type == MEM_CGROUP_TYPE_ALL)
464 ret = mem_cgroup_charge_common(page, mm, gfp_mask,
465 MEM_CGROUP_CHARGE_TYPE_CACHE);
471 * Uncharging is always a welcome operation, we never complain, simply
474 void mem_cgroup_uncharge(struct page_cgroup *pc)
476 struct mem_cgroup *mem;
481 * This can handle cases when a page is not charged at all and we
482 * are switching between handling the control_type.
487 if (atomic_dec_and_test(&pc->ref_cnt)) {
490 * get page->cgroup and clear it under lock.
491 * force_empty can drop page->cgroup without checking refcnt.
493 if (clear_page_cgroup(page, pc) == pc) {
494 mem = pc->mem_cgroup;
496 res_counter_uncharge(&mem->res, PAGE_SIZE);
497 spin_lock_irqsave(&mem->lru_lock, flags);
498 list_del_init(&pc->lru);
499 spin_unlock_irqrestore(&mem->lru_lock, flags);
505 * Returns non-zero if a page (under migration) has valid page_cgroup member.
506 * Refcnt of page_cgroup is incremented.
509 int mem_cgroup_prepare_migration(struct page *page)
511 struct page_cgroup *pc;
513 lock_page_cgroup(page);
514 pc = page_get_page_cgroup(page);
515 if (pc && atomic_inc_not_zero(&pc->ref_cnt))
517 unlock_page_cgroup(page);
521 void mem_cgroup_end_migration(struct page *page)
523 struct page_cgroup *pc = page_get_page_cgroup(page);
524 mem_cgroup_uncharge(pc);
527 * We know both *page* and *newpage* are now not-on-LRU and Pg_locked.
528 * And no race with uncharge() routines because page_cgroup for *page*
529 * has extra one reference by mem_cgroup_prepare_migration.
532 void mem_cgroup_page_migration(struct page *page, struct page *newpage)
534 struct page_cgroup *pc;
536 pc = page_get_page_cgroup(page);
539 if (clear_page_cgroup(page, pc) != pc)
542 lock_page_cgroup(newpage);
543 page_assign_page_cgroup(newpage, pc);
544 unlock_page_cgroup(newpage);
549 * This routine traverse page_cgroup in given list and drop them all.
550 * This routine ignores page_cgroup->ref_cnt.
551 * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
553 #define FORCE_UNCHARGE_BATCH (128)
555 mem_cgroup_force_empty_list(struct mem_cgroup *mem, struct list_head *list)
557 struct page_cgroup *pc;
563 count = FORCE_UNCHARGE_BATCH;
564 spin_lock_irqsave(&mem->lru_lock, flags);
566 while (--count && !list_empty(list)) {
567 pc = list_entry(list->prev, struct page_cgroup, lru);
569 /* Avoid race with charge */
570 atomic_set(&pc->ref_cnt, 0);
571 if (clear_page_cgroup(page, pc) == pc) {
573 res_counter_uncharge(&mem->res, PAGE_SIZE);
574 list_del_init(&pc->lru);
576 } else /* being uncharged ? ...do relax */
579 spin_unlock_irqrestore(&mem->lru_lock, flags);
580 if (!list_empty(list)) {
588 * make mem_cgroup's charge to be 0 if there is no task.
589 * This enables deleting this mem_cgroup.
592 int mem_cgroup_force_empty(struct mem_cgroup *mem)
597 * page reclaim code (kswapd etc..) will move pages between
598 ` * active_list <-> inactive_list while we don't take a lock.
599 * So, we have to do loop here until all lists are empty.
601 while (!(list_empty(&mem->active_list) &&
602 list_empty(&mem->inactive_list))) {
603 if (atomic_read(&mem->css.cgroup->count) > 0)
605 /* drop all page_cgroup in active_list */
606 mem_cgroup_force_empty_list(mem, &mem->active_list);
607 /* drop all page_cgroup in inactive_list */
608 mem_cgroup_force_empty_list(mem, &mem->inactive_list);
618 int mem_cgroup_write_strategy(char *buf, unsigned long long *tmp)
620 *tmp = memparse(buf, &buf);
625 * Round up the value to the closest page size
627 *tmp = ((*tmp + PAGE_SIZE - 1) >> PAGE_SHIFT) << PAGE_SHIFT;
631 static ssize_t mem_cgroup_read(struct cgroup *cont,
632 struct cftype *cft, struct file *file,
633 char __user *userbuf, size_t nbytes, loff_t *ppos)
635 return res_counter_read(&mem_cgroup_from_cont(cont)->res,
636 cft->private, userbuf, nbytes, ppos,
640 static ssize_t mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
641 struct file *file, const char __user *userbuf,
642 size_t nbytes, loff_t *ppos)
644 return res_counter_write(&mem_cgroup_from_cont(cont)->res,
645 cft->private, userbuf, nbytes, ppos,
646 mem_cgroup_write_strategy);
649 static ssize_t mem_control_type_write(struct cgroup *cont,
650 struct cftype *cft, struct file *file,
651 const char __user *userbuf,
652 size_t nbytes, loff_t *pos)
657 struct mem_cgroup *mem;
659 mem = mem_cgroup_from_cont(cont);
660 buf = kmalloc(nbytes + 1, GFP_KERNEL);
667 if (copy_from_user(buf, userbuf, nbytes))
671 tmp = simple_strtoul(buf, &end, 10);
675 if (tmp <= MEM_CGROUP_TYPE_UNSPEC || tmp >= MEM_CGROUP_TYPE_MAX)
678 mem->control_type = tmp;
686 static ssize_t mem_control_type_read(struct cgroup *cont,
688 struct file *file, char __user *userbuf,
689 size_t nbytes, loff_t *ppos)
693 struct mem_cgroup *mem;
695 mem = mem_cgroup_from_cont(cont);
697 val = mem->control_type;
698 s += sprintf(s, "%lu\n", val);
699 return simple_read_from_buffer((void __user *)userbuf, nbytes,
704 static ssize_t mem_force_empty_write(struct cgroup *cont,
705 struct cftype *cft, struct file *file,
706 const char __user *userbuf,
707 size_t nbytes, loff_t *ppos)
709 struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
711 ret = mem_cgroup_force_empty(mem);
718 * Note: This should be removed if cgroup supports write-only file.
721 static ssize_t mem_force_empty_read(struct cgroup *cont,
723 struct file *file, char __user *userbuf,
724 size_t nbytes, loff_t *ppos)
730 static struct cftype mem_cgroup_files[] = {
732 .name = "usage_in_bytes",
733 .private = RES_USAGE,
734 .read = mem_cgroup_read,
737 .name = "limit_in_bytes",
738 .private = RES_LIMIT,
739 .write = mem_cgroup_write,
740 .read = mem_cgroup_read,
744 .private = RES_FAILCNT,
745 .read = mem_cgroup_read,
748 .name = "control_type",
749 .write = mem_control_type_write,
750 .read = mem_control_type_read,
753 .name = "force_empty",
754 .write = mem_force_empty_write,
755 .read = mem_force_empty_read,
759 static struct mem_cgroup init_mem_cgroup;
761 static struct cgroup_subsys_state *
762 mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
764 struct mem_cgroup *mem;
766 if (unlikely((cont->parent) == NULL)) {
767 mem = &init_mem_cgroup;
768 init_mm.mem_cgroup = mem;
770 mem = kzalloc(sizeof(struct mem_cgroup), GFP_KERNEL);
775 res_counter_init(&mem->res);
776 INIT_LIST_HEAD(&mem->active_list);
777 INIT_LIST_HEAD(&mem->inactive_list);
778 spin_lock_init(&mem->lru_lock);
779 mem->control_type = MEM_CGROUP_TYPE_ALL;
783 static void mem_cgroup_destroy(struct cgroup_subsys *ss,
786 kfree(mem_cgroup_from_cont(cont));
789 static int mem_cgroup_populate(struct cgroup_subsys *ss,
792 return cgroup_add_files(cont, ss, mem_cgroup_files,
793 ARRAY_SIZE(mem_cgroup_files));
796 static void mem_cgroup_move_task(struct cgroup_subsys *ss,
798 struct cgroup *old_cont,
799 struct task_struct *p)
801 struct mm_struct *mm;
802 struct mem_cgroup *mem, *old_mem;
808 mem = mem_cgroup_from_cont(cont);
809 old_mem = mem_cgroup_from_cont(old_cont);
815 * Only thread group leaders are allowed to migrate, the mm_struct is
816 * in effect owned by the leader
818 if (p->tgid != p->pid)
822 rcu_assign_pointer(mm->mem_cgroup, mem);
823 css_put(&old_mem->css);
830 struct cgroup_subsys mem_cgroup_subsys = {
832 .subsys_id = mem_cgroup_subsys_id,
833 .create = mem_cgroup_create,
834 .destroy = mem_cgroup_destroy,
835 .populate = mem_cgroup_populate,
836 .attach = mem_cgroup_move_task,