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)
261 struct mem_cgroup *mem;
262 struct page_cgroup *pc, *race_pc;
264 unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
267 * Should page_cgroup's go to their own slab?
268 * One could optimize the performance of the charging routine
269 * by saving a bit in the page_flags and using it as a lock
270 * to see if the cgroup page already has a page_cgroup associated
274 lock_page_cgroup(page);
275 pc = page_get_page_cgroup(page);
277 * The page_cgroup exists and the page has already been accounted
280 if (unlikely(!atomic_inc_not_zero(&pc->ref_cnt))) {
281 /* this page is under being uncharged ? */
282 unlock_page_cgroup(page);
289 unlock_page_cgroup(page);
291 pc = kzalloc(sizeof(struct page_cgroup), GFP_KERNEL);
297 * We always charge the cgroup the mm_struct belongs to
298 * the mm_struct's mem_cgroup changes on task migration if the
299 * thread group leader migrates. It's possible that mm is not
300 * set, if so charge the init_mm (happens for pagecache usage).
305 mem = rcu_dereference(mm->mem_cgroup);
307 * For every charge from the cgroup, increment reference
314 * If we created the page_cgroup, we should free it on exceeding
317 while (res_counter_charge(&mem->res, PAGE_SIZE)) {
318 if (try_to_free_mem_cgroup_pages(mem))
322 * try_to_free_mem_cgroup_pages() might not give us a full
323 * picture of reclaim. Some pages are reclaimed and might be
324 * moved to swap cache or just unmapped from the cgroup.
325 * Check the limit again to see if the reclaim reduced the
326 * current usage of the cgroup before giving up
328 if (res_counter_check_under_limit(&mem->res))
331 * Since we control both RSS and cache, we end up with a
332 * very interesting scenario where we end up reclaiming
333 * memory (essentially RSS), since the memory is pushed
334 * to swap cache, we eventually end up adding those
335 * pages back to our list. Hence we give ourselves a
336 * few chances before we fail
338 else if (nr_retries--) {
339 congestion_wait(WRITE, HZ/10);
344 mem_cgroup_out_of_memory(mem, GFP_KERNEL);
348 lock_page_cgroup(page);
350 * Check if somebody else beat us to allocating the page_cgroup
352 race_pc = page_get_page_cgroup(page);
356 atomic_inc(&pc->ref_cnt);
357 res_counter_uncharge(&mem->res, PAGE_SIZE);
362 atomic_set(&pc->ref_cnt, 1);
363 pc->mem_cgroup = mem;
365 page_assign_page_cgroup(page, pc);
367 spin_lock_irqsave(&mem->lru_lock, flags);
368 list_add(&pc->lru, &mem->active_list);
369 spin_unlock_irqrestore(&mem->lru_lock, flags);
372 unlock_page_cgroup(page);
381 * See if the cached pages should be charged at all?
383 int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm)
385 struct mem_cgroup *mem;
389 mem = rcu_dereference(mm->mem_cgroup);
390 if (mem->control_type == MEM_CGROUP_TYPE_ALL)
391 return mem_cgroup_charge(page, mm);
397 * Uncharging is always a welcome operation, we never complain, simply
400 void mem_cgroup_uncharge(struct page_cgroup *pc)
402 struct mem_cgroup *mem;
407 * This can handle cases when a page is not charged at all and we
408 * are switching between handling the control_type.
413 if (atomic_dec_and_test(&pc->ref_cnt)) {
415 lock_page_cgroup(page);
416 mem = pc->mem_cgroup;
418 page_assign_page_cgroup(page, NULL);
419 unlock_page_cgroup(page);
420 res_counter_uncharge(&mem->res, PAGE_SIZE);
422 spin_lock_irqsave(&mem->lru_lock, flags);
423 list_del_init(&pc->lru);
424 spin_unlock_irqrestore(&mem->lru_lock, flags);
429 int mem_cgroup_write_strategy(char *buf, unsigned long long *tmp)
431 *tmp = memparse(buf, &buf);
436 * Round up the value to the closest page size
438 *tmp = ((*tmp + PAGE_SIZE - 1) >> PAGE_SHIFT) << PAGE_SHIFT;
442 static ssize_t mem_cgroup_read(struct cgroup *cont,
443 struct cftype *cft, struct file *file,
444 char __user *userbuf, size_t nbytes, loff_t *ppos)
446 return res_counter_read(&mem_cgroup_from_cont(cont)->res,
447 cft->private, userbuf, nbytes, ppos,
451 static ssize_t mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
452 struct file *file, const char __user *userbuf,
453 size_t nbytes, loff_t *ppos)
455 return res_counter_write(&mem_cgroup_from_cont(cont)->res,
456 cft->private, userbuf, nbytes, ppos,
457 mem_cgroup_write_strategy);
460 static ssize_t mem_control_type_write(struct cgroup *cont,
461 struct cftype *cft, struct file *file,
462 const char __user *userbuf,
463 size_t nbytes, loff_t *pos)
468 struct mem_cgroup *mem;
470 mem = mem_cgroup_from_cont(cont);
471 buf = kmalloc(nbytes + 1, GFP_KERNEL);
478 if (copy_from_user(buf, userbuf, nbytes))
482 tmp = simple_strtoul(buf, &end, 10);
486 if (tmp <= MEM_CGROUP_TYPE_UNSPEC || tmp >= MEM_CGROUP_TYPE_MAX)
489 mem->control_type = tmp;
497 static ssize_t mem_control_type_read(struct cgroup *cont,
499 struct file *file, char __user *userbuf,
500 size_t nbytes, loff_t *ppos)
504 struct mem_cgroup *mem;
506 mem = mem_cgroup_from_cont(cont);
508 val = mem->control_type;
509 s += sprintf(s, "%lu\n", val);
510 return simple_read_from_buffer((void __user *)userbuf, nbytes,
514 static struct cftype mem_cgroup_files[] = {
516 .name = "usage_in_bytes",
517 .private = RES_USAGE,
518 .read = mem_cgroup_read,
521 .name = "limit_in_bytes",
522 .private = RES_LIMIT,
523 .write = mem_cgroup_write,
524 .read = mem_cgroup_read,
528 .private = RES_FAILCNT,
529 .read = mem_cgroup_read,
532 .name = "control_type",
533 .write = mem_control_type_write,
534 .read = mem_control_type_read,
538 static struct mem_cgroup init_mem_cgroup;
540 static struct cgroup_subsys_state *
541 mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
543 struct mem_cgroup *mem;
545 if (unlikely((cont->parent) == NULL)) {
546 mem = &init_mem_cgroup;
547 init_mm.mem_cgroup = mem;
549 mem = kzalloc(sizeof(struct mem_cgroup), GFP_KERNEL);
554 res_counter_init(&mem->res);
555 INIT_LIST_HEAD(&mem->active_list);
556 INIT_LIST_HEAD(&mem->inactive_list);
557 spin_lock_init(&mem->lru_lock);
558 mem->control_type = MEM_CGROUP_TYPE_ALL;
562 static void mem_cgroup_destroy(struct cgroup_subsys *ss,
565 kfree(mem_cgroup_from_cont(cont));
568 static int mem_cgroup_populate(struct cgroup_subsys *ss,
571 return cgroup_add_files(cont, ss, mem_cgroup_files,
572 ARRAY_SIZE(mem_cgroup_files));
575 static void mem_cgroup_move_task(struct cgroup_subsys *ss,
577 struct cgroup *old_cont,
578 struct task_struct *p)
580 struct mm_struct *mm;
581 struct mem_cgroup *mem, *old_mem;
587 mem = mem_cgroup_from_cont(cont);
588 old_mem = mem_cgroup_from_cont(old_cont);
594 * Only thread group leaders are allowed to migrate, the mm_struct is
595 * in effect owned by the leader
597 if (p->tgid != p->pid)
601 rcu_assign_pointer(mm->mem_cgroup, mem);
602 css_put(&old_mem->css);
609 struct cgroup_subsys mem_cgroup_subsys = {
611 .subsys_id = mem_cgroup_subsys_id,
612 .create = mem_cgroup_create,
613 .destroy = mem_cgroup_destroy,
614 .populate = mem_cgroup_populate,
615 .attach = mem_cgroup_move_task,