1 files changed, 1192 insertions, 0 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
new file mode 100644
index 000000000000..5c2c702af617
--- /dev/null
+++ b/mm/memcontrol.c
@@ -0,0 +1,1192 @@
+/* memcontrol.c - Memory Controller
+ *
+ * Copyright IBM Corporation, 2007
+ * Author Balbir Singh <balbir@linux.vnet.ibm.com>
+ *
+ * Copyright 2007 OpenVZ SWsoft Inc
+ * Author: Pavel Emelianov <xemul@openvz.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/res_counter.h>
+#include <linux/memcontrol.h>
+#include <linux/cgroup.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/page-flags.h>
+#include <linux/backing-dev.h>
+#include <linux/bit_spinlock.h>
+#include <linux/rcupdate.h>
+#include <linux/swap.h>
+#include <linux/spinlock.h>
+#include <linux/fs.h>
+#include <linux/seq_file.h>
+
+#include <asm/uaccess.h>
+
+struct cgroup_subsys mem_cgroup_subsys;
+static const int MEM_CGROUP_RECLAIM_RETRIES = 5;
+
+/*
+ * Statistics for memory cgroup.
+ */
+enum mem_cgroup_stat_index {
+        /*
+         * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
+         */
+        MEM_CGROUP_STAT_CACHE,     /* # of pages charged as cache */
+        MEM_CGROUP_STAT_RSS,       /* # of pages charged as rss */
+
+        MEM_CGROUP_STAT_NSTATS,
+};
+
+struct mem_cgroup_stat_cpu {
+        s64 count[MEM_CGROUP_STAT_NSTATS];
+} ____cacheline_aligned_in_smp;
+
+struct mem_cgroup_stat {
+        struct mem_cgroup_stat_cpu cpustat[NR_CPUS];
+};
+
+/*
+ * For accounting under irq disable, no need for increment preempt count.
+ */
+static void __mem_cgroup_stat_add_safe(struct mem_cgroup_stat *stat,
+                enum mem_cgroup_stat_index idx, int val)
+{
+        int cpu = smp_processor_id();
+        stat->cpustat[cpu].count[idx] += val;
+}
+
+static s64 mem_cgroup_read_stat(struct mem_cgroup_stat *stat,
+                enum mem_cgroup_stat_index idx)
+{
+        int cpu;
+        s64 ret = 0;
+        for_each_possible_cpu(cpu)
+                ret += stat->cpustat[cpu].count[idx];
+        return ret;
+}
+
+/*
+ * per-zone information in memory controller.
+ */
+
+enum mem_cgroup_zstat_index {
+        MEM_CGROUP_ZSTAT_ACTIVE,
+        MEM_CGROUP_ZSTAT_INACTIVE,
+
+        NR_MEM_CGROUP_ZSTAT,
+};
+
+struct mem_cgroup_per_zone {
+        /*
+         * spin_lock to protect the per cgroup LRU
+         */
+        spinlock_t              lru_lock;
+        struct list_head        active_list;
+        struct list_head        inactive_list;
+        unsigned long count[NR_MEM_CGROUP_ZSTAT];
+};
+/* Macro for accessing counter */
+#define MEM_CGROUP_ZSTAT(mz, idx)       ((mz)->count[(idx)])
+
+struct mem_cgroup_per_node {
+        struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
+};
+
+struct mem_cgroup_lru_info {
+        struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES];
+};
+
+/*
+ * The memory controller data structure. The memory controller controls both
+ * page cache and RSS per cgroup. We would eventually like to provide
+ * statistics based on the statistics developed by Rik Van Riel for clock-pro,
+ * to help the administrator determine what knobs to tune.
+ *
+ * TODO: Add a water mark for the memory controller. Reclaim will begin when
+ * we hit the water mark. May be even add a low water mark, such that
+ * no reclaim occurs from a cgroup at it's low water mark, this is
+ * a feature that will be implemented much later in the future.
+ */
+struct mem_cgroup {
+        struct cgroup_subsys_state css;
+        /*
+         * the counter to account for memory usage
+         */
+        struct res_counter res;
+        /*
+         * Per cgroup active and inactive list, similar to the
+         * per zone LRU lists.
+         */
+        struct mem_cgroup_lru_info info;
+
+        int     prev_priority;  /* for recording reclaim priority */
+        /*
+         * statistics.
+         */
+        struct mem_cgroup_stat stat;
+};
+
+/*
+ * We use the lower bit of the page->page_cgroup pointer as a bit spin
+ * lock. We need to ensure that page->page_cgroup is atleast two
+ * byte aligned (based on comments from Nick Piggin)
+ */
+#define PAGE_CGROUP_LOCK_BIT    0x0
+#define PAGE_CGROUP_LOCK                (1 << PAGE_CGROUP_LOCK_BIT)
+
+/*
+ * A page_cgroup page is associated with every page descriptor. The
+ * page_cgroup helps us identify information about the cgroup
+ */
+struct page_cgroup {
+        struct list_head lru;           /* per cgroup LRU list */
+        struct page *page;
+        struct mem_cgroup *mem_cgroup;
+        atomic_t ref_cnt;               /* Helpful when pages move b/w  */
+                                        /* mapped and cached states     */
+        int      flags;
+};
+#define PAGE_CGROUP_FLAG_CACHE  (0x1)   /* charged as cache */
+#define PAGE_CGROUP_FLAG_ACTIVE (0x2)   /* page is active in this cgroup */
+
+static inline int page_cgroup_nid(struct page_cgroup *pc)
+{
+        return page_to_nid(pc->page);
+}
+
+static inline enum zone_type page_cgroup_zid(struct page_cgroup *pc)
+{
+        return page_zonenum(pc->page);
+}
+
+enum {
+        MEM_CGROUP_TYPE_UNSPEC = 0,
+        MEM_CGROUP_TYPE_MAPPED,
+        MEM_CGROUP_TYPE_CACHED,
+        MEM_CGROUP_TYPE_ALL,
+        MEM_CGROUP_TYPE_MAX,
+};
+
+enum charge_type {
+        MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
+        MEM_CGROUP_CHARGE_TYPE_MAPPED,
+};
+
+
+/*
+ * Always modified under lru lock. Then, not necessary to preempt_disable()
+ */
+static void mem_cgroup_charge_statistics(struct mem_cgroup *mem, int flags,
+                                        bool charge)
+{
+        int val = (charge)? 1 : -1;
+        struct mem_cgroup_stat *stat = &mem->stat;
+        VM_BUG_ON(!irqs_disabled());
+
+        if (flags & PAGE_CGROUP_FLAG_CACHE)
+                __mem_cgroup_stat_add_safe(stat,
+                                        MEM_CGROUP_STAT_CACHE, val);
+        else
+                __mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_RSS, val);
+}
+
+static inline struct mem_cgroup_per_zone *
+mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid)
+{
+        BUG_ON(!mem->info.nodeinfo[nid]);
+        return &mem->info.nodeinfo[nid]->zoneinfo[zid];
+}
+
+static inline struct mem_cgroup_per_zone *
+page_cgroup_zoneinfo(struct page_cgroup *pc)
+{
+        struct mem_cgroup *mem = pc->mem_cgroup;
+        int nid = page_cgroup_nid(pc);
+        int zid = page_cgroup_zid(pc);
+
+        return mem_cgroup_zoneinfo(mem, nid, zid);
+}
+
+static unsigned long mem_cgroup_get_all_zonestat(struct mem_cgroup *mem,
+                                        enum mem_cgroup_zstat_index idx)
+{
+        int nid, zid;
+        struct mem_cgroup_per_zone *mz;
+        u64 total = 0;
+
+        for_each_online_node(nid)
+                for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+                        mz = mem_cgroup_zoneinfo(mem, nid, zid);
+                        total += MEM_CGROUP_ZSTAT(mz, idx);
+                }
+        return total;
+}
+
+static struct mem_cgroup init_mem_cgroup;
+
+static inline
+struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
+{
+        return container_of(cgroup_subsys_state(cont,
+                                mem_cgroup_subsys_id), struct mem_cgroup,
+                                css);
+}
+
+static inline
+struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
+{
+        return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
+                                struct mem_cgroup, css);
+}
+
+void mm_init_cgroup(struct mm_struct *mm, struct task_struct *p)
+{
+        struct mem_cgroup *mem;
+
+        mem = mem_cgroup_from_task(p);
+        css_get(&mem->css);
+        mm->mem_cgroup = mem;
+}
+
+void mm_free_cgroup(struct mm_struct *mm)
+{
+        css_put(&mm->mem_cgroup->css);
+}
+
+static inline int page_cgroup_locked(struct page *page)
+{
+        return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT,
+                                        &page->page_cgroup);
+}
+
+void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
+{
+        int locked;
+
+        /*
+         * While resetting the page_cgroup we might not hold the
+         * page_cgroup lock. free_hot_cold_page() is an example
+         * of such a scenario
+         */
+        if (pc)
+                VM_BUG_ON(!page_cgroup_locked(page));
+        locked = (page->page_cgroup & PAGE_CGROUP_LOCK);
+        page->page_cgroup = ((unsigned long)pc | locked);
+}
+
+struct page_cgroup *page_get_page_cgroup(struct page *page)
+{
+        return (struct page_cgroup *)
+                (page->page_cgroup & ~PAGE_CGROUP_LOCK);
+}
+
+static void __always_inline lock_page_cgroup(struct page *page)
+{
+        bit_spin_lock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
+        VM_BUG_ON(!page_cgroup_locked(page));
+}
+
+static void __always_inline unlock_page_cgroup(struct page *page)
+{
+        bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
+}
+
+/*
+ * Tie new page_cgroup to struct page under lock_page_cgroup()
+ * This can fail if the page has been tied to a page_cgroup.
+ * If success, returns 0.
+ */
+static int page_cgroup_assign_new_page_cgroup(struct page *page,
+                                                struct page_cgroup *pc)
+{
+        int ret = 0;
+
+        lock_page_cgroup(page);
+        if (!page_get_page_cgroup(page))
+                page_assign_page_cgroup(page, pc);
+        else /* A page is tied to other pc. */
+                ret = 1;
+        unlock_page_cgroup(page);
+        return ret;
+}
+
+/*
+ * Clear page->page_cgroup member under lock_page_cgroup().
+ * If given "pc" value is different from one page->page_cgroup,
+ * page->cgroup is not cleared.
+ * Returns a value of page->page_cgroup at lock taken.
+ * A can can detect failure of clearing by following
+ *  clear_page_cgroup(page, pc) == pc
+ */
+
+static struct page_cgroup *clear_page_cgroup(struct page *page,
+                                                struct page_cgroup *pc)
+{
+        struct page_cgroup *ret;
+        /* lock and clear */
+        lock_page_cgroup(page);
+        ret = page_get_page_cgroup(page);
+        if (likely(ret == pc))
+                page_assign_page_cgroup(page, NULL);
+        unlock_page_cgroup(page);
+        return ret;
+}
+
+static void __mem_cgroup_remove_list(struct page_cgroup *pc)
+{
+        int from = pc->flags & PAGE_CGROUP_FLAG_ACTIVE;
+        struct mem_cgroup_per_zone *mz = page_cgroup_zoneinfo(pc);
+
+        if (from)
+                MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_ACTIVE) -= 1;
+        else
+                MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_INACTIVE) -= 1;
+
+        mem_cgroup_charge_statistics(pc->mem_cgroup, pc->flags, false);
+        list_del_init(&pc->lru);
+}
+
+static void __mem_cgroup_add_list(struct page_cgroup *pc)
+{
+        int to = pc->flags & PAGE_CGROUP_FLAG_ACTIVE;
+        struct mem_cgroup_per_zone *mz = page_cgroup_zoneinfo(pc);
+
+        if (!to) {
+                MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_INACTIVE) += 1;
+                list_add(&pc->lru, &mz->inactive_list);
+        } else {
+                MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_ACTIVE) += 1;
+                list_add(&pc->lru, &mz->active_list);
+        }
+        mem_cgroup_charge_statistics(pc->mem_cgroup, pc->flags, true);
+}
+
+static void __mem_cgroup_move_lists(struct page_cgroup *pc, bool active)
+{
+        int from = pc->flags & PAGE_CGROUP_FLAG_ACTIVE;
+        struct mem_cgroup_per_zone *mz = page_cgroup_zoneinfo(pc);
+
+        if (from)
+                MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_ACTIVE) -= 1;
+        else
+                MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_INACTIVE) -= 1;
+
+        if (active) {
+                MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_ACTIVE) += 1;
+                pc->flags |= PAGE_CGROUP_FLAG_ACTIVE;
+                list_move(&pc->lru, &mz->active_list);
+        } else {
+                MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_INACTIVE) += 1;
+                pc->flags &= ~PAGE_CGROUP_FLAG_ACTIVE;
+                list_move(&pc->lru, &mz->inactive_list);
+        }
+}
+
+int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
+{
+        int ret;
+
+        task_lock(task);
+        ret = task->mm && mm_cgroup(task->mm) == mem;
+        task_unlock(task);
+        return ret;
+}
+
+/*
+ * This routine assumes that the appropriate zone's lru lock is already held
+ */
+void mem_cgroup_move_lists(struct page_cgroup *pc, bool active)
+{
+        struct mem_cgroup_per_zone *mz;
+        unsigned long flags;
+
+        if (!pc)
+                return;
+
+        mz = page_cgroup_zoneinfo(pc);
+        spin_lock_irqsave(&mz->lru_lock, flags);
+        __mem_cgroup_move_lists(pc, active);
+        spin_unlock_irqrestore(&mz->lru_lock, flags);
+}
+
+/*
+ * Calculate mapped_ratio under memory controller. This will be used in
+ * vmscan.c for deteremining we have to reclaim mapped pages.
+ */
+int mem_cgroup_calc_mapped_ratio(struct mem_cgroup *mem)
+{
+        long total, rss;
+
+        /*
+         * usage is recorded in bytes. But, here, we assume the number of
+         * physical pages can be represented by "long" on any arch.
+         */
+        total = (long) (mem->res.usage >> PAGE_SHIFT) + 1L;
+        rss = (long)mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_RSS);
+        return (int)((rss * 100L) / total);
+}
+/*
+ * This function is called from vmscan.c. In page reclaiming loop. balance
+ * between active and inactive list is calculated. For memory controller
+ * page reclaiming, we should use using mem_cgroup's imbalance rather than
+ * zone's global lru imbalance.
+ */
+long mem_cgroup_reclaim_imbalance(struct mem_cgroup *mem)
+{
+        unsigned long active, inactive;
+        /* active and inactive are the number of pages. 'long' is ok.*/
+        active = mem_cgroup_get_all_zonestat(mem, MEM_CGROUP_ZSTAT_ACTIVE);
+        inactive = mem_cgroup_get_all_zonestat(mem, MEM_CGROUP_ZSTAT_INACTIVE);
+        return (long) (active / (inactive + 1));
+}
+
+/*
+ * prev_priority control...this will be used in memory reclaim path.
+ */
+int mem_cgroup_get_reclaim_priority(struct mem_cgroup *mem)
+{
+        return mem->prev_priority;
+}
+
+void mem_cgroup_note_reclaim_priority(struct mem_cgroup *mem, int priority)
+{
+        if (priority < mem->prev_priority)
+                mem->prev_priority = priority;
+}
+
+void mem_cgroup_record_reclaim_priority(struct mem_cgroup *mem, int priority)
+{
+        mem->prev_priority = priority;
+}
+
+/*
+ * Calculate # of pages to be scanned in this priority/zone.
+ * See also vmscan.c
+ *
+ * priority starts from "DEF_PRIORITY" and decremented in each loop.
+ * (see include/linux/mmzone.h)
+ */
+
+long mem_cgroup_calc_reclaim_active(struct mem_cgroup *mem,
+                                   struct zone *zone, int priority)
+{
+        long nr_active;
+        int nid = zone->zone_pgdat->node_id;
+        int zid = zone_idx(zone);
+        struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(mem, nid, zid);
+
+        nr_active = MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_ACTIVE);
+        return (nr_active >> priority);
+}
+
+long mem_cgroup_calc_reclaim_inactive(struct mem_cgroup *mem,
+                                        struct zone *zone, int priority)
+{
+        long nr_inactive;
+        int nid = zone->zone_pgdat->node_id;
+        int zid = zone_idx(zone);
+        struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(mem, nid, zid);
+
+        nr_inactive = MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_INACTIVE);
+
+        return (nr_inactive >> priority);
+}
+
+unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
+                                        struct list_head *dst,
+                                        unsigned long *scanned, int order,
+                                        int mode, struct zone *z,
+                                        struct mem_cgroup *mem_cont,
+                                        int active)
+{
+        unsigned long nr_taken = 0;
+        struct page *page;
+        unsigned long scan;
+        LIST_HEAD(pc_list);
+        struct list_head *src;
+        struct page_cgroup *pc, *tmp;
+        int nid = z->zone_pgdat->node_id;
+        int zid = zone_idx(z);
+        struct mem_cgroup_per_zone *mz;
+
+        mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
+        if (active)
+                src = &mz->active_list;
+        else
+                src = &mz->inactive_list;
+
+
+        spin_lock(&mz->lru_lock);
+        scan = 0;
+        list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
+                if (scan >= nr_to_scan)
+                        break;
+                page = pc->page;
+                VM_BUG_ON(!pc);
+
+                if (unlikely(!PageLRU(page)))
+                        continue;
+
+                if (PageActive(page) && !active) {
+                        __mem_cgroup_move_lists(pc, true);
+                        continue;
+                }
+                if (!PageActive(page) && active) {
+                        __mem_cgroup_move_lists(pc, false);
+                        continue;
+                }
+
+                scan++;
+                list_move(&pc->lru, &pc_list);
+
+                if (__isolate_lru_page(page, mode) == 0) {
+                        list_move(&page->lru, dst);
+                        nr_taken++;
+                }
+        }
+
+        list_splice(&pc_list, src);
+        spin_unlock(&mz->lru_lock);
+
+        *scanned = scan;
+        return nr_taken;
+}
+
+/*
+ * Charge the memory controller for page usage.
+ * Return
+ * 0 if the charge was successful
+ * < 0 if the cgroup is over its limit
+ */
+static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
+                                gfp_t gfp_mask, enum charge_type ctype)
+{
+        struct mem_cgroup *mem;
+        struct page_cgroup *pc;
+        unsigned long flags;
+        unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
+        struct mem_cgroup_per_zone *mz;
+
+        /*
+         * Should page_cgroup's go to their own slab?
+         * One could optimize the performance of the charging routine
+         * by saving a bit in the page_flags and using it as a lock
+         * to see if the cgroup page already has a page_cgroup associated
+         * with it
+         */
+retry:
+        if (page) {
+                lock_page_cgroup(page);
+                pc = page_get_page_cgroup(page);
+                /*
+                 * The page_cgroup exists and
+                 * the page has already been accounted.
+                 */
+                if (pc) {
+                        if (unlikely(!atomic_inc_not_zero(&pc->ref_cnt))) {
+                                /* this page is under being uncharged ? */
+                                unlock_page_cgroup(page);
+                                cpu_relax();
+                                goto retry;
+                        } else {
+                                unlock_page_cgroup(page);
+                                goto done;
+                        }
+                }
+                unlock_page_cgroup(page);
+        }
+
+        pc = kzalloc(sizeof(struct page_cgroup), gfp_mask);
+        if (pc == NULL)
+                goto err;
+
+        /*
+         * We always charge the cgroup the mm_struct belongs to.
+         * The mm_struct's mem_cgroup changes on task migration if the
+         * thread group leader migrates. It's possible that mm is not
+         * set, if so charge the init_mm (happens for pagecache usage).
+         */
+        if (!mm)
+                mm = &init_mm;
+
+        rcu_read_lock();
+        mem = rcu_dereference(mm->mem_cgroup);
+        /*
+         * For every charge from the cgroup, increment reference
+         * count
+         */
+        css_get(&mem->css);
+        rcu_read_unlock();
+
+        /*
+         * If we created the page_cgroup, we should free it on exceeding
+         * the cgroup limit.
+         */
+        while (res_counter_charge(&mem->res, PAGE_SIZE)) {
+                if (!(gfp_mask & __GFP_WAIT))
+                        goto out;
+
+                if (try_to_free_mem_cgroup_pages(mem, gfp_mask))
+                        continue;
+
+                /*
+                 * try_to_free_mem_cgroup_pages() might not give us a full
+                 * picture of reclaim. Some pages are reclaimed and might be
+                 * moved to swap cache or just unmapped from the cgroup.
+                 * Check the limit again to see if the reclaim reduced the
+                 * current usage of the cgroup before giving up
+                 */
+                if (res_counter_check_under_limit(&mem->res))
+                        continue;
+
+                if (!nr_retries--) {
+                        mem_cgroup_out_of_memory(mem, gfp_mask);
+                        goto out;
+                }
+                congestion_wait(WRITE, HZ/10);
+        }
+
+        atomic_set(&pc->ref_cnt, 1);
+        pc->mem_cgroup = mem;
+        pc->page = page;
+        pc->flags = PAGE_CGROUP_FLAG_ACTIVE;
+        if (ctype == MEM_CGROUP_CHARGE_TYPE_CACHE)
+                pc->flags |= PAGE_CGROUP_FLAG_CACHE;
+
+        if (!page || page_cgroup_assign_new_page_cgroup(page, pc)) {
+                /*
+                 * Another charge has been added to this page already.
+                 * We take lock_page_cgroup(page) again and read
+                 * page->cgroup, increment refcnt.... just retry is OK.
+                 */
+                res_counter_uncharge(&mem->res, PAGE_SIZE);
+                css_put(&mem->css);
+                kfree(pc);
+                if (!page)
+                        goto done;
+                goto retry;
+        }
+
+        mz = page_cgroup_zoneinfo(pc);
+        spin_lock_irqsave(&mz->lru_lock, flags);
+        /* Update statistics vector */
+        __mem_cgroup_add_list(pc);
+        spin_unlock_irqrestore(&mz->lru_lock, flags);
+
+done:
+        return 0;
+out:
+        css_put(&mem->css);
+        kfree(pc);
+err:
+        return -ENOMEM;
+}
+
+int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
+                        gfp_t gfp_mask)
+{
+        return mem_cgroup_charge_common(page, mm, gfp_mask,
+                        MEM_CGROUP_CHARGE_TYPE_MAPPED);
+}
+
+/*
+ * See if the cached pages should be charged at all?
+ */
+int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
+                                gfp_t gfp_mask)
+{
+        int ret = 0;
+        if (!mm)
+                mm = &init_mm;
+
+        ret = mem_cgroup_charge_common(page, mm, gfp_mask,
+                                MEM_CGROUP_CHARGE_TYPE_CACHE);
+        return ret;
+}
+
+/*
+ * Uncharging is always a welcome operation, we never complain, simply
+ * uncharge. This routine should be called with lock_page_cgroup held
+ */
+void mem_cgroup_uncharge(struct page_cgroup *pc)
+{
+        struct mem_cgroup *mem;
+        struct mem_cgroup_per_zone *mz;
+        struct page *page;
+        unsigned long flags;
+
+        /*
+         * Check if our page_cgroup is valid
+         */
+        if (!pc)
+                return;
+
+        if (atomic_dec_and_test(&pc->ref_cnt)) {
+                page = pc->page;
+                mz = page_cgroup_zoneinfo(pc);
+                /*
+                 * get page->cgroup and clear it under lock.
+                 * force_empty can drop page->cgroup without checking refcnt.
+                 */
+                unlock_page_cgroup(page);
+                if (clear_page_cgroup(page, pc) == pc) {
+                        mem = pc->mem_cgroup;
+                        css_put(&mem->css);
+                        res_counter_uncharge(&mem->res, PAGE_SIZE);
+                        spin_lock_irqsave(&mz->lru_lock, flags);
+                        __mem_cgroup_remove_list(pc);
+                        spin_unlock_irqrestore(&mz->lru_lock, flags);
+                        kfree(pc);
+                }
+                lock_page_cgroup(page);
+        }
+}
+
+void mem_cgroup_uncharge_page(struct page *page)
+{
+        lock_page_cgroup(page);
+        mem_cgroup_uncharge(page_get_page_cgroup(page));
+        unlock_page_cgroup(page);
+}
+
+/*
+ * Returns non-zero if a page (under migration) has valid page_cgroup member.
+ * Refcnt of page_cgroup is incremented.
+ */
+
+int mem_cgroup_prepare_migration(struct page *page)
+{
+        struct page_cgroup *pc;
+        int ret = 0;
+        lock_page_cgroup(page);
+        pc = page_get_page_cgroup(page);
+        if (pc && atomic_inc_not_zero(&pc->ref_cnt))
+                ret = 1;
+        unlock_page_cgroup(page);
+        return ret;
+}
+
+void mem_cgroup_end_migration(struct page *page)
+{
+        struct page_cgroup *pc;
+
+        lock_page_cgroup(page);
+        pc = page_get_page_cgroup(page);
+        mem_cgroup_uncharge(pc);
+        unlock_page_cgroup(page);
+}
+/*
+ * We know both *page* and *newpage* are now not-on-LRU and Pg_locked.
+ * And no race with uncharge() routines because page_cgroup for *page*
+ * has extra one reference by mem_cgroup_prepare_migration.
+ */
+
+void mem_cgroup_page_migration(struct page *page, struct page *newpage)
+{
+        struct page_cgroup *pc;
+        struct mem_cgroup *mem;
+        unsigned long flags;
+        struct mem_cgroup_per_zone *mz;
+retry:
+        pc = page_get_page_cgroup(page);
+        if (!pc)
+                return;
+        mem = pc->mem_cgroup;
+        mz = page_cgroup_zoneinfo(pc);
+        if (clear_page_cgroup(page, pc) != pc)
+                goto retry;
+        spin_lock_irqsave(&mz->lru_lock, flags);
+
+        __mem_cgroup_remove_list(pc);
+        spin_unlock_irqrestore(&mz->lru_lock, flags);
+
+        pc->page = newpage;
+        lock_page_cgroup(newpage);
+        page_assign_page_cgroup(newpage, pc);
+        unlock_page_cgroup(newpage);
+
+        mz = page_cgroup_zoneinfo(pc);
+        spin_lock_irqsave(&mz->lru_lock, flags);
+        __mem_cgroup_add_list(pc);
+        spin_unlock_irqrestore(&mz->lru_lock, flags);
+        return;
+}
+
+/*
+ * This routine traverse page_cgroup in given list and drop them all.
+ * This routine ignores page_cgroup->ref_cnt.
+ * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
+ */
+#define FORCE_UNCHARGE_BATCH    (128)
+static void
+mem_cgroup_force_empty_list(struct mem_cgroup *mem,
+                            struct mem_cgroup_per_zone *mz,
+                            int active)
+{
+        struct page_cgroup *pc;
+        struct page *page;
+        int count;
+        unsigned long flags;
+        struct list_head *list;
+
+        if (active)
+                list = &mz->active_list;
+        else
+                list = &mz->inactive_list;
+
+        if (list_empty(list))
+                return;
+retry:
+        count = FORCE_UNCHARGE_BATCH;
+        spin_lock_irqsave(&mz->lru_lock, flags);
+
+        while (--count && !list_empty(list)) {
+                pc = list_entry(list->prev, struct page_cgroup, lru);
+                page = pc->page;
+                /* Avoid race with charge */
+                atomic_set(&pc->ref_cnt, 0);
+                if (clear_page_cgroup(page, pc) == pc) {
+                        css_put(&mem->css);
+                        res_counter_uncharge(&mem->res, PAGE_SIZE);
+                        __mem_cgroup_remove_list(pc);
+                        kfree(pc);
+                } else  /* being uncharged ? ...do relax */
+                        break;
+        }
+        spin_unlock_irqrestore(&mz->lru_lock, flags);
+        if (!list_empty(list)) {
+                cond_resched();
+                goto retry;
+        }
+        return;
+}
+
+/*
+ * make mem_cgroup's charge to be 0 if there is no task.
+ * This enables deleting this mem_cgroup.
+ */
+
+int mem_cgroup_force_empty(struct mem_cgroup *mem)
+{
+        int ret = -EBUSY;
+        int node, zid;
+        css_get(&mem->css);
+        /*
+         * page reclaim code (kswapd etc..) will move pages between
+`        * active_list <-> inactive_list while we don't take a lock.
+         * So, we have to do loop here until all lists are empty.
+         */
+        while (mem->res.usage > 0) {
+                if (atomic_read(&mem->css.cgroup->count) > 0)
+                        goto out;
+                for_each_node_state(node, N_POSSIBLE)
+                        for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+                                struct mem_cgroup_per_zone *mz;
+                                mz = mem_cgroup_zoneinfo(mem, node, zid);
+                                /* drop all page_cgroup in active_list */
+                                mem_cgroup_force_empty_list(mem, mz, 1);
+                                /* drop all page_cgroup in inactive_list */
+                                mem_cgroup_force_empty_list(mem, mz, 0);
+                        }
+        }
+        ret = 0;
+out:
+        css_put(&mem->css);
+        return ret;
+}
+
+
+
+int mem_cgroup_write_strategy(char *buf, unsigned long long *tmp)
+{
+        *tmp = memparse(buf, &buf);
+        if (*buf != '\0')
+                return -EINVAL;
+
+        /*
+         * Round up the value to the closest page size
+         */
+        *tmp = ((*tmp + PAGE_SIZE - 1) >> PAGE_SHIFT) << PAGE_SHIFT;
+        return 0;
+}
+
+static ssize_t mem_cgroup_read(struct cgroup *cont,
+                        struct cftype *cft, struct file *file,
+                        char __user *userbuf, size_t nbytes, loff_t *ppos)
+{
+        return res_counter_read(&mem_cgroup_from_cont(cont)->res,
+                                cft->private, userbuf, nbytes, ppos,
+                                NULL);
+}
+
+static ssize_t mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
+                                struct file *file, const char __user *userbuf,
+                                size_t nbytes, loff_t *ppos)
+{
+        return res_counter_write(&mem_cgroup_from_cont(cont)->res,
+                                cft->private, userbuf, nbytes, ppos,
+                                mem_cgroup_write_strategy);
+}
+
+static ssize_t mem_force_empty_write(struct cgroup *cont,
+                                struct cftype *cft, struct file *file,
+                                const char __user *userbuf,
+                                size_t nbytes, loff_t *ppos)
+{
+        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
+        int ret;
+        ret = mem_cgroup_force_empty(mem);
+        if (!ret)
+                ret = nbytes;
+        return ret;
+}
+
+/*
+ * Note: This should be removed if cgroup supports write-only file.
+ */
+
+static ssize_t mem_force_empty_read(struct cgroup *cont,
+                                struct cftype *cft,
+                                struct file *file, char __user *userbuf,
+                                size_t nbytes, loff_t *ppos)
+{
+        return -EINVAL;
+}
+
+
+static const struct mem_cgroup_stat_desc {
+        const char *msg;
+        u64 unit;
+} mem_cgroup_stat_desc[] = {
+        [MEM_CGROUP_STAT_CACHE] = { "cache", PAGE_SIZE, },
+        [MEM_CGROUP_STAT_RSS] = { "rss", PAGE_SIZE, },
+};
+
+static int mem_control_stat_show(struct seq_file *m, void *arg)
+{
+        struct cgroup *cont = m->private;
+        struct mem_cgroup *mem_cont = mem_cgroup_from_cont(cont);
+        struct mem_cgroup_stat *stat = &mem_cont->stat;
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(stat->cpustat[0].count); i++) {
+                s64 val;
+
+                val = mem_cgroup_read_stat(stat, i);
+                val *= mem_cgroup_stat_desc[i].unit;
+                seq_printf(m, "%s %lld\n", mem_cgroup_stat_desc[i].msg,
+                                (long long)val);
+        }
+        /* showing # of active pages */
+        {
+                unsigned long active, inactive;
+
+                inactive = mem_cgroup_get_all_zonestat(mem_cont,
+                                                MEM_CGROUP_ZSTAT_INACTIVE);
+                active = mem_cgroup_get_all_zonestat(mem_cont,
+                                                MEM_CGROUP_ZSTAT_ACTIVE);
+                seq_printf(m, "active %ld\n", (active) * PAGE_SIZE);
+                seq_printf(m, "inactive %ld\n", (inactive) * PAGE_SIZE);
+        }
+        return 0;
+}
+
+static const struct file_operations mem_control_stat_file_operations = {
+        .read = seq_read,
+        .llseek = seq_lseek,
+        .release = single_release,
+};
+
+static int mem_control_stat_open(struct inode *unused, struct file *file)
+{
+        /* XXX __d_cont */
+        struct cgroup *cont = file->f_dentry->d_parent->d_fsdata;
+
+        file->f_op = &mem_control_stat_file_operations;
+        return single_open(file, mem_control_stat_show, cont);
+}
+
+
+
+static struct cftype mem_cgroup_files[] = {
+        {
+                .name = "usage_in_bytes",
+                .private = RES_USAGE,
+                .read = mem_cgroup_read,
+        },
+        {
+                .name = "limit_in_bytes",
+                .private = RES_LIMIT,
+                .write = mem_cgroup_write,
+                .read = mem_cgroup_read,
+        },
+        {
+                .name = "failcnt",
+                .private = RES_FAILCNT,
+                .read = mem_cgroup_read,
+        },
+        {
+                .name = "force_empty",
+                .write = mem_force_empty_write,
+                .read = mem_force_empty_read,
+        },
+        {
+                .name = "stat",
+                .open = mem_control_stat_open,
+        },
+};
+
+static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
+{
+        struct mem_cgroup_per_node *pn;
+        struct mem_cgroup_per_zone *mz;
+        int zone;
+        /*
+         * This routine is called against possible nodes.
+         * But it's BUG to call kmalloc() against offline node.
+         *
+         * TODO: this routine can waste much memory for nodes which will
+         *       never be onlined. It's better to use memory hotplug callback
+         *       function.
+         */
+        if (node_state(node, N_HIGH_MEMORY))
+                pn = kmalloc_node(sizeof(*pn), GFP_KERNEL, node);
+        else
+                pn = kmalloc(sizeof(*pn), GFP_KERNEL);
+        if (!pn)
+                return 1;
+
+        mem->info.nodeinfo[node] = pn;
+        memset(pn, 0, sizeof(*pn));
+
+        for (zone = 0; zone < MAX_NR_ZONES; zone++) {
+                mz = &pn->zoneinfo[zone];
+                INIT_LIST_HEAD(&mz->active_list);
+                INIT_LIST_HEAD(&mz->inactive_list);
+                spin_lock_init(&mz->lru_lock);
+        }
+        return 0;
+}
+
+static void free_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
+{
+        kfree(mem->info.nodeinfo[node]);
+}
+
+
+static struct mem_cgroup init_mem_cgroup;
+
+static struct cgroup_subsys_state *
+mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+        struct mem_cgroup *mem;
+        int node;
+
+        if (unlikely((cont->parent) == NULL)) {
+                mem = &init_mem_cgroup;
+                init_mm.mem_cgroup = mem;
+        } else
+                mem = kzalloc(sizeof(struct mem_cgroup), GFP_KERNEL);
+
+        if (mem == NULL)
+                return NULL;
+
+        res_counter_init(&mem->res);
+
+        memset(&mem->info, 0, sizeof(mem->info));
+
+        for_each_node_state(node, N_POSSIBLE)
+                if (alloc_mem_cgroup_per_zone_info(mem, node))
+                        goto free_out;
+
+        return &mem->css;
+free_out:
+        for_each_node_state(node, N_POSSIBLE)
+                free_mem_cgroup_per_zone_info(mem, node);
+        if (cont->parent != NULL)
+                kfree(mem);
+        return NULL;
+}
+
+static void mem_cgroup_pre_destroy(struct cgroup_subsys *ss,
+                                        struct cgroup *cont)
+{
+        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
+        mem_cgroup_force_empty(mem);
+}
+
+static void mem_cgroup_destroy(struct cgroup_subsys *ss,
+                                struct cgroup *cont)
+{
+        int node;
+        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
+
+        for_each_node_state(node, N_POSSIBLE)
+                free_mem_cgroup_per_zone_info(mem, node);
+
+        kfree(mem_cgroup_from_cont(cont));
+}
+
+static int mem_cgroup_populate(struct cgroup_subsys *ss,
+                                struct cgroup *cont)
+{
+        return cgroup_add_files(cont, ss, mem_cgroup_files,
+                                        ARRAY_SIZE(mem_cgroup_files));
+}
+
+static void mem_cgroup_move_task(struct cgroup_subsys *ss,
+                                struct cgroup *cont,
+                                struct cgroup *old_cont,
+                                struct task_struct *p)
+{
+        struct mm_struct *mm;
+        struct mem_cgroup *mem, *old_mem;
+
+        mm = get_task_mm(p);
+        if (mm == NULL)
+                return;
+
+        mem = mem_cgroup_from_cont(cont);
+        old_mem = mem_cgroup_from_cont(old_cont);
+
+        if (mem == old_mem)
+                goto out;
+
+        /*
+         * Only thread group leaders are allowed to migrate, the mm_struct is
+         * in effect owned by the leader
+         */
+        if (p->tgid != p->pid)
+                goto out;
+
+        css_get(&mem->css);
+        rcu_assign_pointer(mm->mem_cgroup, mem);
+        css_put(&old_mem->css);
+
+out:
+        mmput(mm);
+        return;
+}
+
+struct cgroup_subsys mem_cgroup_subsys = {
+        .name = "memory",
+        .subsys_id = mem_cgroup_subsys_id,
+        .create = mem_cgroup_create,
+        .pre_destroy = mem_cgroup_pre_destroy,
+        .destroy = mem_cgroup_destroy,
+        .populate = mem_cgroup_populate,
+        .attach = mem_cgroup_move_task,
+        .early_init = 0,
+};