RPC/RDMA: maintain the RPC task bytes-sent statistic.
[safe/jmp/linux-2.6] / mm / memcontrol.c
index e227d7c..36896f3 100644 (file)
 #include <linux/backing-dev.h>
 #include <linux/bit_spinlock.h>
 #include <linux/rcupdate.h>
+#include <linux/slab.h>
 #include <linux/swap.h>
 #include <linux/spinlock.h>
 #include <linux/fs.h>
 #include <linux/seq_file.h>
+#include <linux/vmalloc.h>
 
 #include <asm/uaccess.h>
 
-struct cgroup_subsys mem_cgroup_subsys;
-static const int MEM_CGROUP_RECLAIM_RETRIES = 5;
+struct cgroup_subsys mem_cgroup_subsys __read_mostly;
+static struct kmem_cache *page_cgroup_cache __read_mostly;
+#define MEM_CGROUP_RECLAIM_RETRIES     5
 
 /*
  * Statistics for memory cgroup.
@@ -45,6 +48,8 @@ enum mem_cgroup_stat_index {
         */
        MEM_CGROUP_STAT_CACHE,     /* # of pages charged as cache */
        MEM_CGROUP_STAT_RSS,       /* # of pages charged as rss */
+       MEM_CGROUP_STAT_PGPGIN_COUNT,   /* # of pages paged in */
+       MEM_CGROUP_STAT_PGPGOUT_COUNT,  /* # of pages paged out */
 
        MEM_CGROUP_STAT_NSTATS,
 };
@@ -161,7 +166,6 @@ struct page_cgroup {
        struct list_head lru;           /* per cgroup LRU list */
        struct page *page;
        struct mem_cgroup *mem_cgroup;
-       int ref_cnt;                    /* cached, mapped, migrating */
        int flags;
 };
 #define PAGE_CGROUP_FLAG_CACHE (0x1)   /* charged as cache */
@@ -180,6 +184,7 @@ static enum zone_type page_cgroup_zid(struct page_cgroup *pc)
 enum charge_type {
        MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
        MEM_CGROUP_CHARGE_TYPE_MAPPED,
+       MEM_CGROUP_CHARGE_TYPE_FORCE,   /* used by force_empty */
 };
 
 /*
@@ -196,6 +201,13 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *mem, int flags,
                __mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_CACHE, val);
        else
                __mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_RSS, val);
+
+       if (charge)
+               __mem_cgroup_stat_add_safe(stat,
+                               MEM_CGROUP_STAT_PGPGIN_COUNT, 1);
+       else
+               __mem_cgroup_stat_add_safe(stat,
+                               MEM_CGROUP_STAT_PGPGOUT_COUNT, 1);
 }
 
 static struct mem_cgroup_per_zone *
@@ -236,26 +248,20 @@ static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
                                css);
 }
 
-static struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
+struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
 {
+       /*
+        * mm_update_next_owner() may clear mm->owner to NULL
+        * if it races with swapoff, page migration, etc.
+        * So this can be called with p == NULL.
+        */
+       if (unlikely(!p))
+               return NULL;
+
        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);
@@ -287,10 +293,10 @@ static void unlock_page_cgroup(struct page *page)
        bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
 }
 
-static void __mem_cgroup_remove_list(struct page_cgroup *pc)
+static void __mem_cgroup_remove_list(struct mem_cgroup_per_zone *mz,
+                       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;
@@ -298,13 +304,13 @@ static void __mem_cgroup_remove_list(struct page_cgroup *pc)
                MEM_CGROUP_ZSTAT(mz, MEM_CGROUP_ZSTAT_INACTIVE) -= 1;
 
        mem_cgroup_charge_statistics(pc->mem_cgroup, pc->flags, false);
-       list_del_init(&pc->lru);
+       list_del(&pc->lru);
 }
 
-static void __mem_cgroup_add_list(struct page_cgroup *pc)
+static void __mem_cgroup_add_list(struct mem_cgroup_per_zone *mz,
+                               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;
@@ -356,6 +362,9 @@ void mem_cgroup_move_lists(struct page *page, bool active)
        struct mem_cgroup_per_zone *mz;
        unsigned long flags;
 
+       if (mem_cgroup_subsys.disabled)
+               return;
+
        /*
         * We cannot lock_page_cgroup while holding zone's lru_lock,
         * because other holders of lock_page_cgroup can be interrupted
@@ -476,6 +485,7 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
        int zid = zone_idx(z);
        struct mem_cgroup_per_zone *mz;
 
+       BUG_ON(!mem_cont);
        mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
        if (active)
                src = &mz->active_list;
@@ -525,7 +535,8 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
  * < 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)
+                               gfp_t gfp_mask, enum charge_type ctype,
+                               struct mem_cgroup *memcg)
 {
        struct mem_cgroup *mem;
        struct page_cgroup *pc;
@@ -533,35 +544,8 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
        unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
        struct mem_cgroup_per_zone *mz;
 
-       if (mem_cgroup_subsys.disabled)
-               return 0;
-
-       /*
-        * 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:
-       lock_page_cgroup(page);
-       pc = page_get_page_cgroup(page);
-       /*
-        * The page_cgroup exists and
-        * the page has already been accounted.
-        */
-       if (pc) {
-               VM_BUG_ON(pc->page != page);
-               VM_BUG_ON(pc->ref_cnt <= 0);
-
-               pc->ref_cnt++;
-               unlock_page_cgroup(page);
-               goto done;
-       }
-       unlock_page_cgroup(page);
-
-       pc = kzalloc(sizeof(struct page_cgroup), gfp_mask);
-       if (pc == NULL)
+       pc = kmem_cache_alloc(page_cgroup_cache, gfp_mask);
+       if (unlikely(pc == NULL))
                goto err;
 
        /*
@@ -570,16 +554,23 @@ retry:
         * 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 (likely(!memcg)) {
+               rcu_read_lock();
+               mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
+               if (unlikely(!mem)) {
+                       rcu_read_unlock();
+                       kmem_cache_free(page_cgroup_cache, pc);
+                       return 0;
+               }
+               /*
+                * For every charge from the cgroup, increment reference count
+                */
+               css_get(&mem->css);
+               rcu_read_unlock();
+       } else {
+               mem = memcg;
+               css_get(&memcg->css);
+       }
 
        while (res_counter_charge(&mem->res, PAGE_SIZE)) {
                if (!(gfp_mask & __GFP_WAIT))
@@ -602,34 +593,32 @@ retry:
                        mem_cgroup_out_of_memory(mem, gfp_mask);
                        goto out;
                }
-               congestion_wait(WRITE, HZ/10);
        }
 
-       pc->ref_cnt = 1;
        pc->mem_cgroup = mem;
        pc->page = page;
-       pc->flags = PAGE_CGROUP_FLAG_ACTIVE;
+       /*
+        * If a page is accounted as a page cache, insert to inactive list.
+        * If anon, insert to active list.
+        */
        if (ctype == MEM_CGROUP_CHARGE_TYPE_CACHE)
-               pc->flags |= PAGE_CGROUP_FLAG_CACHE;
+               pc->flags = PAGE_CGROUP_FLAG_CACHE;
+       else
+               pc->flags = PAGE_CGROUP_FLAG_ACTIVE;
 
        lock_page_cgroup(page);
-       if (page_get_page_cgroup(page)) {
+       if (unlikely(page_get_page_cgroup(page))) {
                unlock_page_cgroup(page);
-               /*
-                * 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);
-               goto retry;
+               kmem_cache_free(page_cgroup_cache, pc);
+               goto done;
        }
        page_assign_page_cgroup(page, pc);
 
        mz = page_cgroup_zoneinfo(pc);
        spin_lock_irqsave(&mz->lru_lock, flags);
-       __mem_cgroup_add_list(pc);
+       __mem_cgroup_add_list(mz, pc);
        spin_unlock_irqrestore(&mz->lru_lock, flags);
 
        unlock_page_cgroup(page);
@@ -637,31 +626,72 @@ done:
        return 0;
 out:
        css_put(&mem->css);
-       kfree(pc);
+       kmem_cache_free(page_cgroup_cache, pc);
 err:
        return -ENOMEM;
 }
 
 int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask)
 {
+       if (mem_cgroup_subsys.disabled)
+               return 0;
+
+       /*
+        * If already mapped, we don't have to account.
+        * If page cache, page->mapping has address_space.
+        * But page->mapping may have out-of-use anon_vma pointer,
+        * detecit it by PageAnon() check. newly-mapped-anon's page->mapping
+        * is NULL.
+        */
+       if (page_mapped(page) || (page->mapping && !PageAnon(page)))
+               return 0;
+       if (unlikely(!mm))
+               mm = &init_mm;
        return mem_cgroup_charge_common(page, mm, gfp_mask,
-                               MEM_CGROUP_CHARGE_TYPE_MAPPED);
+                               MEM_CGROUP_CHARGE_TYPE_MAPPED, NULL);
 }
 
 int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
                                gfp_t gfp_mask)
 {
-       if (!mm)
+       if (mem_cgroup_subsys.disabled)
+               return 0;
+
+       /*
+        * Corner case handling. This is called from add_to_page_cache()
+        * in usual. But some FS (shmem) precharges this page before calling it
+        * and call add_to_page_cache() with GFP_NOWAIT.
+        *
+        * For GFP_NOWAIT case, the page may be pre-charged before calling
+        * add_to_page_cache(). (See shmem.c) check it here and avoid to call
+        * charge twice. (It works but has to pay a bit larger cost.)
+        */
+       if (!(gfp_mask & __GFP_WAIT)) {
+               struct page_cgroup *pc;
+
+               lock_page_cgroup(page);
+               pc = page_get_page_cgroup(page);
+               if (pc) {
+                       VM_BUG_ON(pc->page != page);
+                       VM_BUG_ON(!pc->mem_cgroup);
+                       unlock_page_cgroup(page);
+                       return 0;
+               }
+               unlock_page_cgroup(page);
+       }
+
+       if (unlikely(!mm))
                mm = &init_mm;
+
        return mem_cgroup_charge_common(page, mm, gfp_mask,
-                               MEM_CGROUP_CHARGE_TYPE_CACHE);
+                               MEM_CGROUP_CHARGE_TYPE_CACHE, NULL);
 }
 
 /*
- * Uncharging is always a welcome operation, we never complain, simply
- * uncharge.
+ * uncharge if !page_mapped(page)
  */
-void mem_cgroup_uncharge_page(struct page *page)
+static void
+__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
 {
        struct page_cgroup *pc;
        struct mem_cgroup *mem;
@@ -676,98 +706,158 @@ void mem_cgroup_uncharge_page(struct page *page)
         */
        lock_page_cgroup(page);
        pc = page_get_page_cgroup(page);
-       if (!pc)
+       if (unlikely(!pc))
                goto unlock;
 
        VM_BUG_ON(pc->page != page);
-       VM_BUG_ON(pc->ref_cnt <= 0);
 
-       if (--(pc->ref_cnt) == 0) {
-               mz = page_cgroup_zoneinfo(pc);
-               spin_lock_irqsave(&mz->lru_lock, flags);
-               __mem_cgroup_remove_list(pc);
-               spin_unlock_irqrestore(&mz->lru_lock, flags);
+       if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
+           && ((pc->flags & PAGE_CGROUP_FLAG_CACHE)
+               || page_mapped(page)))
+               goto unlock;
 
-               page_assign_page_cgroup(page, NULL);
-               unlock_page_cgroup(page);
+       mz = page_cgroup_zoneinfo(pc);
+       spin_lock_irqsave(&mz->lru_lock, flags);
+       __mem_cgroup_remove_list(mz, pc);
+       spin_unlock_irqrestore(&mz->lru_lock, flags);
 
-               mem = pc->mem_cgroup;
-               res_counter_uncharge(&mem->res, PAGE_SIZE);
-               css_put(&mem->css);
+       page_assign_page_cgroup(page, NULL);
+       unlock_page_cgroup(page);
 
-               kfree(pc);
-               return;
-       }
+       mem = pc->mem_cgroup;
+       res_counter_uncharge(&mem->res, PAGE_SIZE);
+       css_put(&mem->css);
 
+       kmem_cache_free(page_cgroup_cache, pc);
+       return;
 unlock:
        unlock_page_cgroup(page);
 }
 
+void mem_cgroup_uncharge_page(struct page *page)
+{
+       __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
+}
+
+void mem_cgroup_uncharge_cache_page(struct page *page)
+{
+       VM_BUG_ON(page_mapped(page));
+       __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
+}
+
 /*
- * Returns non-zero if a page (under migration) has valid page_cgroup member.
- * Refcnt of page_cgroup is incremented.
+ * Before starting migration, account against new page.
  */
-int mem_cgroup_prepare_migration(struct page *page)
+int mem_cgroup_prepare_migration(struct page *page, struct page *newpage)
 {
        struct page_cgroup *pc;
+       struct mem_cgroup *mem = NULL;
+       enum charge_type ctype = MEM_CGROUP_CHARGE_TYPE_MAPPED;
+       int ret = 0;
 
        if (mem_cgroup_subsys.disabled)
                return 0;
 
        lock_page_cgroup(page);
        pc = page_get_page_cgroup(page);
-       if (pc)
-               pc->ref_cnt++;
+       if (pc) {
+               mem = pc->mem_cgroup;
+               css_get(&mem->css);
+               if (pc->flags & PAGE_CGROUP_FLAG_CACHE)
+                       ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
+       }
        unlock_page_cgroup(page);
-       return pc != NULL;
+       if (mem) {
+               ret = mem_cgroup_charge_common(newpage, NULL, GFP_KERNEL,
+                       ctype, mem);
+               css_put(&mem->css);
+       }
+       return ret;
 }
 
-void mem_cgroup_end_migration(struct page *page)
+/* remove redundant charge if migration failed*/
+void mem_cgroup_end_migration(struct page *newpage)
 {
-       mem_cgroup_uncharge_page(page);
+       /*
+        * At success, page->mapping is not NULL.
+        * special rollback care is necessary when
+        * 1. at migration failure. (newpage->mapping is cleared in this case)
+        * 2. the newpage was moved but not remapped again because the task
+        *    exits and the newpage is obsolete. In this case, the new page
+        *    may be a swapcache. So, we just call mem_cgroup_uncharge_page()
+        *    always for avoiding mess. The  page_cgroup will be removed if
+        *    unnecessary. File cache pages is still on radix-tree. Don't
+        *    care it.
+        */
+       if (!newpage->mapping)
+               __mem_cgroup_uncharge_common(newpage,
+                                        MEM_CGROUP_CHARGE_TYPE_FORCE);
+       else if (PageAnon(newpage))
+               mem_cgroup_uncharge_page(newpage);
 }
 
 /*
- * 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.
+ * A call to try to shrink memory usage under specified resource controller.
+ * This is typically used for page reclaiming for shmem for reducing side
+ * effect of page allocation from shmem, which is used by some mem_cgroup.
  */
-void mem_cgroup_page_migration(struct page *page, struct page *newpage)
+int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask)
 {
-       struct page_cgroup *pc;
-       struct mem_cgroup_per_zone *mz;
-       unsigned long flags;
+       struct mem_cgroup *mem;
+       int progress = 0;
+       int retry = MEM_CGROUP_RECLAIM_RETRIES;
 
-       lock_page_cgroup(page);
-       pc = page_get_page_cgroup(page);
-       if (!pc) {
-               unlock_page_cgroup(page);
-               return;
+       if (mem_cgroup_subsys.disabled)
+               return 0;
+       if (!mm)
+               return 0;
+
+       rcu_read_lock();
+       mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
+       if (unlikely(!mem)) {
+               rcu_read_unlock();
+               return 0;
        }
+       css_get(&mem->css);
+       rcu_read_unlock();
 
-       mz = page_cgroup_zoneinfo(pc);
-       spin_lock_irqsave(&mz->lru_lock, flags);
-       __mem_cgroup_remove_list(pc);
-       spin_unlock_irqrestore(&mz->lru_lock, flags);
+       do {
+               progress = try_to_free_mem_cgroup_pages(mem, gfp_mask);
+               progress += res_counter_check_under_limit(&mem->res);
+       } while (!progress && --retry);
 
-       page_assign_page_cgroup(page, NULL);
-       unlock_page_cgroup(page);
+       css_put(&mem->css);
+       if (!retry)
+               return -ENOMEM;
+       return 0;
+}
 
-       pc->page = newpage;
-       lock_page_cgroup(newpage);
-       page_assign_page_cgroup(newpage, pc);
+int mem_cgroup_resize_limit(struct mem_cgroup *memcg, unsigned long long val)
+{
 
-       mz = page_cgroup_zoneinfo(pc);
-       spin_lock_irqsave(&mz->lru_lock, flags);
-       __mem_cgroup_add_list(pc);
-       spin_unlock_irqrestore(&mz->lru_lock, flags);
+       int retry_count = MEM_CGROUP_RECLAIM_RETRIES;
+       int progress;
+       int ret = 0;
 
-       unlock_page_cgroup(newpage);
+       while (res_counter_set_limit(&memcg->res, val)) {
+               if (signal_pending(current)) {
+                       ret = -EINTR;
+                       break;
+               }
+               if (!retry_count) {
+                       ret = -EBUSY;
+                       break;
+               }
+               progress = try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL);
+               if (!progress)
+                       retry_count--;
+       }
+       return ret;
 }
 
+
 /*
  * 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)
@@ -792,12 +882,20 @@ static void mem_cgroup_force_empty_list(struct mem_cgroup *mem,
                page = pc->page;
                get_page(page);
                spin_unlock_irqrestore(&mz->lru_lock, flags);
-               mem_cgroup_uncharge_page(page);
-               put_page(page);
-               if (--count <= 0) {
-                       count = FORCE_UNCHARGE_BATCH;
+               /*
+                * Check if this page is on LRU. !LRU page can be found
+                * if it's under page migration.
+                */
+               if (PageLRU(page)) {
+                       __mem_cgroup_uncharge_common(page,
+                                       MEM_CGROUP_CHARGE_TYPE_FORCE);
+                       put_page(page);
+                       if (--count <= 0) {
+                               count = FORCE_UNCHARGE_BATCH;
+                               cond_resched();
+                       }
+               } else
                        cond_resched();
-               }
                spin_lock_irqsave(&mz->lru_lock, flags);
        }
        spin_unlock_irqrestore(&mz->lru_lock, flags);
@@ -812,9 +910,6 @@ static int mem_cgroup_force_empty(struct mem_cgroup *mem)
        int ret = -EBUSY;
        int node, zid;
 
-       if (mem_cgroup_subsys.disabled)
-               return 0;
-
        css_get(&mem->css);
        /*
         * page reclaim code (kswapd etc..) will move pages between
@@ -840,55 +935,55 @@ out:
        return ret;
 }
 
-static 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 u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
 {
        return res_counter_read_u64(&mem_cgroup_from_cont(cont)->res,
                                    cft->private);
 }
-
-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)
+/*
+ * The user of this function is...
+ * RES_LIMIT.
+ */
+static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
+                           const char *buffer)
 {
-       return res_counter_write(&mem_cgroup_from_cont(cont)->res,
-                               cft->private, userbuf, nbytes, ppos,
-                               mem_cgroup_write_strategy);
+       struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+       unsigned long long val;
+       int ret;
+
+       switch (cft->private) {
+       case RES_LIMIT:
+               /* This function does all necessary parse...reuse it */
+               ret = res_counter_memparse_write_strategy(buffer, &val);
+               if (!ret)
+                       ret = mem_cgroup_resize_limit(memcg, val);
+               break;
+       default:
+               ret = -EINVAL; /* should be BUG() ? */
+               break;
+       }
+       return ret;
 }
 
-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)
+static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
 {
-       struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
-       int ret = mem_cgroup_force_empty(mem);
-       if (!ret)
-               ret = nbytes;
-       return ret;
+       struct mem_cgroup *mem;
+
+       mem = mem_cgroup_from_cont(cont);
+       switch (event) {
+       case RES_MAX_USAGE:
+               res_counter_reset_max(&mem->res);
+               break;
+       case RES_FAILCNT:
+               res_counter_reset_failcnt(&mem->res);
+               break;
+       }
+       return 0;
 }
 
-/*
- * 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)
+static int mem_force_empty_write(struct cgroup *cont, unsigned int event)
 {
-       return -EINVAL;
+       return mem_cgroup_force_empty(mem_cgroup_from_cont(cont));
 }
 
 static const struct mem_cgroup_stat_desc {
@@ -897,11 +992,13 @@ static const struct mem_cgroup_stat_desc {
 } mem_cgroup_stat_desc[] = {
        [MEM_CGROUP_STAT_CACHE] = { "cache", PAGE_SIZE, },
        [MEM_CGROUP_STAT_RSS] = { "rss", PAGE_SIZE, },
+       [MEM_CGROUP_STAT_PGPGIN_COUNT] = {"pgpgin", 1, },
+       [MEM_CGROUP_STAT_PGPGOUT_COUNT] = {"pgpgout", 1, },
 };
 
-static int mem_control_stat_show(struct seq_file *m, void *arg)
+static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
+                                struct cgroup_map_cb *cb)
 {
-       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;
@@ -911,8 +1008,7 @@ static int mem_control_stat_show(struct seq_file *m, void *arg)
 
                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);
+               cb->fill(cb, mem_cgroup_stat_desc[i].msg, val);
        }
        /* showing # of active pages */
        {
@@ -922,27 +1018,12 @@ static int mem_control_stat_show(struct seq_file *m, void *arg)
                                                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);
+               cb->fill(cb, "active", (active) * PAGE_SIZE);
+               cb->fill(cb, "inactive", (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",
@@ -950,24 +1031,30 @@ static struct cftype mem_cgroup_files[] = {
                .read_u64 = mem_cgroup_read,
        },
        {
+               .name = "max_usage_in_bytes",
+               .private = RES_MAX_USAGE,
+               .trigger = mem_cgroup_reset,
+               .read_u64 = mem_cgroup_read,
+       },
+       {
                .name = "limit_in_bytes",
                .private = RES_LIMIT,
-               .write = mem_cgroup_write,
+               .write_string = mem_cgroup_write,
                .read_u64 = mem_cgroup_read,
        },
        {
                .name = "failcnt",
                .private = RES_FAILCNT,
+               .trigger = mem_cgroup_reset,
                .read_u64 = mem_cgroup_read,
        },
        {
                .name = "force_empty",
-               .write = mem_force_empty_write,
-               .read = mem_force_empty_read,
+               .trigger = mem_force_empty_write,
        },
        {
                .name = "stat",
-               .open = mem_control_stat_open,
+               .read_map = mem_control_stat_show,
        },
 };
 
@@ -1007,6 +1094,29 @@ static void free_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
        kfree(mem->info.nodeinfo[node]);
 }
 
+static struct mem_cgroup *mem_cgroup_alloc(void)
+{
+       struct mem_cgroup *mem;
+
+       if (sizeof(*mem) < PAGE_SIZE)
+               mem = kmalloc(sizeof(*mem), GFP_KERNEL);
+       else
+               mem = vmalloc(sizeof(*mem));
+
+       if (mem)
+               memset(mem, 0, sizeof(*mem));
+       return mem;
+}
+
+static void mem_cgroup_free(struct mem_cgroup *mem)
+{
+       if (sizeof(*mem) < PAGE_SIZE)
+               kfree(mem);
+       else
+               vfree(mem);
+}
+
+
 static struct cgroup_subsys_state *
 mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 {
@@ -1015,17 +1125,15 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 
        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 ERR_PTR(-ENOMEM);
+               page_cgroup_cache = KMEM_CACHE(page_cgroup, SLAB_PANIC);
+       } else {
+               mem = mem_cgroup_alloc();
+               if (!mem)
+                       return ERR_PTR(-ENOMEM);
+       }
 
        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;
@@ -1035,7 +1143,7 @@ free_out:
        for_each_node_state(node, N_POSSIBLE)
                free_mem_cgroup_per_zone_info(mem, node);
        if (cont->parent != NULL)
-               kfree(mem);
+               mem_cgroup_free(mem);
        return ERR_PTR(-ENOMEM);
 }
 
@@ -1055,14 +1163,12 @@ static void mem_cgroup_destroy(struct cgroup_subsys *ss,
        for_each_node_state(node, N_POSSIBLE)
                free_mem_cgroup_per_zone_info(mem, node);
 
-       kfree(mem_cgroup_from_cont(cont));
+       mem_cgroup_free(mem_cgroup_from_cont(cont));
 }
 
 static int mem_cgroup_populate(struct cgroup_subsys *ss,
                                struct cgroup *cont)
 {
-       if (mem_cgroup_subsys.disabled)
-               return 0;
        return cgroup_add_files(cont, ss, mem_cgroup_files,
                                        ARRAY_SIZE(mem_cgroup_files));
 }
@@ -1075,9 +1181,6 @@ static void mem_cgroup_move_task(struct cgroup_subsys *ss,
        struct mm_struct *mm;
        struct mem_cgroup *mem, *old_mem;
 
-       if (mem_cgroup_subsys.disabled)
-               return;
-
        mm = get_task_mm(p);
        if (mm == NULL)
                return;
@@ -1085,9 +1188,6 @@ static void mem_cgroup_move_task(struct cgroup_subsys *ss,
        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
@@ -1095,10 +1195,6 @@ static void mem_cgroup_move_task(struct cgroup_subsys *ss,
        if (!thread_group_leader(p))
                goto out;
 
-       css_get(&mem->css);
-       rcu_assign_pointer(mm->mem_cgroup, mem);
-       css_put(&old_mem->css);
-
 out:
        mmput(mm);
 }