337 lines
8.2 KiB
C
337 lines
8.2 KiB
C
/* memcontrol.c - Memory Controller
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*
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* Copyright IBM Corporation, 2007
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* Author Balbir Singh <balbir@linux.vnet.ibm.com>
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*
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* Copyright 2007 OpenVZ SWsoft Inc
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* Author: Pavel Emelianov <xemul@openvz.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/res_counter.h>
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#include <linux/memcontrol.h>
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#include <linux/cgroup.h>
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#include <linux/mm.h>
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#include <linux/page-flags.h>
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#include <linux/bit_spinlock.h>
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#include <linux/rcupdate.h>
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struct cgroup_subsys mem_cgroup_subsys;
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/*
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* The memory controller data structure. The memory controller controls both
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* page cache and RSS per cgroup. We would eventually like to provide
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* statistics based on the statistics developed by Rik Van Riel for clock-pro,
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* to help the administrator determine what knobs to tune.
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*
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* TODO: Add a water mark for the memory controller. Reclaim will begin when
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* we hit the water mark. May be even add a low water mark, such that
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* no reclaim occurs from a cgroup at it's low water mark, this is
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* a feature that will be implemented much later in the future.
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*/
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struct mem_cgroup {
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struct cgroup_subsys_state css;
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/*
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* the counter to account for memory usage
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*/
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struct res_counter res;
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/*
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* Per cgroup active and inactive list, similar to the
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* per zone LRU lists.
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* TODO: Consider making these lists per zone
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*/
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struct list_head active_list;
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struct list_head inactive_list;
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};
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/*
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* We use the lower bit of the page->page_cgroup pointer as a bit spin
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* lock. We need to ensure that page->page_cgroup is atleast two
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* byte aligned (based on comments from Nick Piggin)
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*/
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#define PAGE_CGROUP_LOCK_BIT 0x0
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#define PAGE_CGROUP_LOCK (1 << PAGE_CGROUP_LOCK_BIT)
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/*
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* A page_cgroup page is associated with every page descriptor. The
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* page_cgroup helps us identify information about the cgroup
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*/
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struct page_cgroup {
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struct list_head lru; /* per cgroup LRU list */
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struct page *page;
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struct mem_cgroup *mem_cgroup;
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atomic_t ref_cnt; /* Helpful when pages move b/w */
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/* mapped and cached states */
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};
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static inline
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struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
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{
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return container_of(cgroup_subsys_state(cont,
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mem_cgroup_subsys_id), struct mem_cgroup,
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css);
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}
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static inline
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struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
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{
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return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
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struct mem_cgroup, css);
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}
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void mm_init_cgroup(struct mm_struct *mm, struct task_struct *p)
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{
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struct mem_cgroup *mem;
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mem = mem_cgroup_from_task(p);
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css_get(&mem->css);
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mm->mem_cgroup = mem;
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}
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void mm_free_cgroup(struct mm_struct *mm)
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{
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css_put(&mm->mem_cgroup->css);
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}
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static inline int page_cgroup_locked(struct page *page)
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{
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return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT,
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&page->page_cgroup);
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}
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void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
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{
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int locked;
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/*
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* While resetting the page_cgroup we might not hold the
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* page_cgroup lock. free_hot_cold_page() is an example
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* of such a scenario
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*/
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if (pc)
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VM_BUG_ON(!page_cgroup_locked(page));
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locked = (page->page_cgroup & PAGE_CGROUP_LOCK);
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page->page_cgroup = ((unsigned long)pc | locked);
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}
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struct page_cgroup *page_get_page_cgroup(struct page *page)
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{
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return (struct page_cgroup *)
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(page->page_cgroup & ~PAGE_CGROUP_LOCK);
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}
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void __always_inline lock_page_cgroup(struct page *page)
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{
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bit_spin_lock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
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VM_BUG_ON(!page_cgroup_locked(page));
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}
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void __always_inline unlock_page_cgroup(struct page *page)
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{
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bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
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}
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/*
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* Charge the memory controller for page usage.
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* Return
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* 0 if the charge was successful
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* < 0 if the cgroup is over its limit
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*/
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int mem_cgroup_charge(struct page *page, struct mm_struct *mm)
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{
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struct mem_cgroup *mem;
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struct page_cgroup *pc, *race_pc;
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/*
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* Should page_cgroup's go to their own slab?
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* One could optimize the performance of the charging routine
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* by saving a bit in the page_flags and using it as a lock
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* to see if the cgroup page already has a page_cgroup associated
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* with it
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*/
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lock_page_cgroup(page);
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pc = page_get_page_cgroup(page);
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/*
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* The page_cgroup exists and the page has already been accounted
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*/
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if (pc) {
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atomic_inc(&pc->ref_cnt);
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goto done;
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}
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unlock_page_cgroup(page);
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pc = kzalloc(sizeof(struct page_cgroup), GFP_KERNEL);
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if (pc == NULL)
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goto err;
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rcu_read_lock();
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/*
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* We always charge the cgroup the mm_struct belongs to
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* the mm_struct's mem_cgroup changes on task migration if the
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* thread group leader migrates. It's possible that mm is not
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* set, if so charge the init_mm (happens for pagecache usage).
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*/
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if (!mm)
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mm = &init_mm;
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mem = rcu_dereference(mm->mem_cgroup);
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/*
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* For every charge from the cgroup, increment reference
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* count
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*/
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css_get(&mem->css);
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rcu_read_unlock();
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/*
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* If we created the page_cgroup, we should free it on exceeding
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* the cgroup limit.
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*/
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if (res_counter_charge(&mem->res, 1)) {
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css_put(&mem->css);
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goto free_pc;
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}
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lock_page_cgroup(page);
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/*
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* Check if somebody else beat us to allocating the page_cgroup
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*/
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race_pc = page_get_page_cgroup(page);
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if (race_pc) {
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kfree(pc);
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pc = race_pc;
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atomic_inc(&pc->ref_cnt);
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res_counter_uncharge(&mem->res, 1);
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css_put(&mem->css);
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goto done;
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}
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atomic_set(&pc->ref_cnt, 1);
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pc->mem_cgroup = mem;
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pc->page = page;
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page_assign_page_cgroup(page, pc);
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done:
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unlock_page_cgroup(page);
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return 0;
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free_pc:
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kfree(pc);
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return -ENOMEM;
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err:
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unlock_page_cgroup(page);
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return -ENOMEM;
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}
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/*
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* Uncharging is always a welcome operation, we never complain, simply
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* uncharge.
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*/
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void mem_cgroup_uncharge(struct page_cgroup *pc)
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{
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struct mem_cgroup *mem;
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struct page *page;
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if (!pc)
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return;
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if (atomic_dec_and_test(&pc->ref_cnt)) {
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page = pc->page;
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lock_page_cgroup(page);
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mem = pc->mem_cgroup;
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css_put(&mem->css);
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page_assign_page_cgroup(page, NULL);
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unlock_page_cgroup(page);
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res_counter_uncharge(&mem->res, 1);
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kfree(pc);
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}
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}
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static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
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struct file *file, char __user *userbuf, size_t nbytes,
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loff_t *ppos)
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{
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return res_counter_read(&mem_cgroup_from_cont(cont)->res,
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cft->private, userbuf, nbytes, ppos);
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}
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static ssize_t mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
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struct file *file, const char __user *userbuf,
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size_t nbytes, loff_t *ppos)
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{
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return res_counter_write(&mem_cgroup_from_cont(cont)->res,
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cft->private, userbuf, nbytes, ppos);
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}
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static struct cftype mem_cgroup_files[] = {
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{
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.name = "usage",
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.private = RES_USAGE,
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.read = mem_cgroup_read,
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},
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{
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.name = "limit",
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.private = RES_LIMIT,
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.write = mem_cgroup_write,
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.read = mem_cgroup_read,
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},
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{
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.name = "failcnt",
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.private = RES_FAILCNT,
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.read = mem_cgroup_read,
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},
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};
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static struct mem_cgroup init_mem_cgroup;
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static struct cgroup_subsys_state *
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mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
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{
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struct mem_cgroup *mem;
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if (unlikely((cont->parent) == NULL)) {
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mem = &init_mem_cgroup;
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init_mm.mem_cgroup = mem;
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} else
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mem = kzalloc(sizeof(struct mem_cgroup), GFP_KERNEL);
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if (mem == NULL)
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return NULL;
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res_counter_init(&mem->res);
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INIT_LIST_HEAD(&mem->active_list);
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INIT_LIST_HEAD(&mem->inactive_list);
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return &mem->css;
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}
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static void mem_cgroup_destroy(struct cgroup_subsys *ss,
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struct cgroup *cont)
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{
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kfree(mem_cgroup_from_cont(cont));
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}
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static int mem_cgroup_populate(struct cgroup_subsys *ss,
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struct cgroup *cont)
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{
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return cgroup_add_files(cont, ss, mem_cgroup_files,
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ARRAY_SIZE(mem_cgroup_files));
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}
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struct cgroup_subsys mem_cgroup_subsys = {
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.name = "memory",
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.subsys_id = mem_cgroup_subsys_id,
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.create = mem_cgroup_create,
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.destroy = mem_cgroup_destroy,
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.populate = mem_cgroup_populate,
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.early_init = 1,
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};
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