memcg: fix hierarchical reclaim
[sfrench/cifs-2.6.git] / mm / memcontrol.c
index 659b0c58f13edce66a09500866b70b74f80a288b..322625f551c27504c89d3f0f743bd58da32f909f 100644 (file)
@@ -51,6 +51,7 @@ static int really_do_swap_account __initdata = 1; /* for remember boot option*/
 #define do_swap_account                (0)
 #endif
 
+static DEFINE_MUTEX(memcg_tasklist);   /* can be hold under cgroup_mutex */
 
 /*
  * Statistics for memory cgroup.
@@ -103,6 +104,8 @@ struct mem_cgroup_per_zone {
         */
        struct list_head        lists[NR_LRU_LISTS];
        unsigned long           count[NR_LRU_LISTS];
+
+       struct zone_reclaim_stat reclaim_stat;
 };
 /* Macro for accessing counter */
 #define MEM_CGROUP_ZSTAT(mz, idx)      ((mz)->count[(idx)])
@@ -142,11 +145,16 @@ struct mem_cgroup {
         */
        struct mem_cgroup_lru_info info;
 
+       /*
+         protect against reclaim related member.
+       */
+       spinlock_t reclaim_param_lock;
+
        int     prev_priority;  /* for recording reclaim priority */
 
        /*
         * While reclaiming in a hiearchy, we cache the last child we
-        * reclaimed from. Protected by cgroup_lock()
+        * reclaimed from. Protected by hierarchy_mutex
         */
        struct mem_cgroup *last_scanned_child;
        /*
@@ -154,8 +162,10 @@ struct mem_cgroup {
         */
        bool use_hierarchy;
        unsigned long   last_oom_jiffies;
-       int             obsolete;
        atomic_t        refcnt;
+
+       unsigned int    swappiness;
+
        /*
         * statistics. This must be placed at the end of memcg.
         */
@@ -183,7 +193,6 @@ pcg_default_flags[NR_CHARGE_TYPE] = {
        0, /* FORCE */
 };
 
-
 /* for encoding cft->private value on file */
 #define _MEM                   (0)
 #define _MEMSWAP               (1)
@@ -231,6 +240,9 @@ page_cgroup_zoneinfo(struct page_cgroup *pc)
        int nid = page_cgroup_nid(pc);
        int zid = page_cgroup_zid(pc);
 
+       if (!mem)
+               return NULL;
+
        return mem_cgroup_zoneinfo(mem, nid, zid);
 }
 
@@ -270,6 +282,31 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
                                struct mem_cgroup, css);
 }
 
+static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
+{
+       struct mem_cgroup *mem = NULL;
+       /*
+        * Because we have no locks, mm->owner's may be being moved to other
+        * cgroup. We use css_tryget() here even if this looks
+        * pessimistic (rather than adding locks here).
+        */
+       rcu_read_lock();
+       do {
+               mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
+               if (unlikely(!mem))
+                       break;
+       } while (!css_tryget(&mem->css));
+       rcu_read_unlock();
+       return mem;
+}
+
+static bool mem_cgroup_is_obsolete(struct mem_cgroup *mem)
+{
+       if (!mem)
+               return true;
+       return css_is_removed(&mem->css);
+}
+
 /*
  * Following LRU functions are allowed to be used without PCG_LOCK.
  * Operations are called by routine of global LRU independently from memcg.
@@ -294,8 +331,12 @@ void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru)
                return;
        pc = lookup_page_cgroup(page);
        /* can happen while we handle swapcache. */
-       if (list_empty(&pc->lru))
+       if (list_empty(&pc->lru) || !pc->mem_cgroup)
                return;
+       /*
+        * We don't check PCG_USED bit. It's cleared when the "page" is finally
+        * removed from global LRU.
+        */
        mz = page_cgroup_zoneinfo(pc);
        mem = pc->mem_cgroup;
        MEM_CGROUP_ZSTAT(mz, lru) -= 1;
@@ -317,6 +358,10 @@ void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
                return;
 
        pc = lookup_page_cgroup(page);
+       /*
+        * Used bit is set without atomic ops but after smp_wmb().
+        * For making pc->mem_cgroup visible, insert smp_rmb() here.
+        */
        smp_rmb();
        /* unused page is not rotated. */
        if (!PageCgroupUsed(pc))
@@ -333,7 +378,10 @@ void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
        if (mem_cgroup_disabled())
                return;
        pc = lookup_page_cgroup(page);
-       /* barrier to sync with "charge" */
+       /*
+        * Used bit is set without atomic ops but after smp_wmb().
+        * For making pc->mem_cgroup visible, insert smp_rmb() here.
+        */
        smp_rmb();
        if (!PageCgroupUsed(pc))
                return;
@@ -342,16 +390,44 @@ void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
        MEM_CGROUP_ZSTAT(mz, lru) += 1;
        list_add(&pc->lru, &mz->lists[lru]);
 }
+
 /*
- * To add swapcache into LRU. Be careful to all this function.
- * zone->lru_lock shouldn't be held and irq must not be disabled.
+ * At handling SwapCache, pc->mem_cgroup may be changed while it's linked to
+ * lru because the page may.be reused after it's fully uncharged (because of
+ * SwapCache behavior).To handle that, unlink page_cgroup from LRU when charge
+ * it again. This function is only used to charge SwapCache. It's done under
+ * lock_page and expected that zone->lru_lock is never held.
  */
-static void mem_cgroup_lru_fixup(struct page *page)
+static void mem_cgroup_lru_del_before_commit_swapcache(struct page *page)
+{
+       unsigned long flags;
+       struct zone *zone = page_zone(page);
+       struct page_cgroup *pc = lookup_page_cgroup(page);
+
+       spin_lock_irqsave(&zone->lru_lock, flags);
+       /*
+        * Forget old LRU when this page_cgroup is *not* used. This Used bit
+        * is guarded by lock_page() because the page is SwapCache.
+        */
+       if (!PageCgroupUsed(pc))
+               mem_cgroup_del_lru_list(page, page_lru(page));
+       spin_unlock_irqrestore(&zone->lru_lock, flags);
+}
+
+static void mem_cgroup_lru_add_after_commit_swapcache(struct page *page)
 {
-       if (!isolate_lru_page(page))
-               putback_lru_page(page);
+       unsigned long flags;
+       struct zone *zone = page_zone(page);
+       struct page_cgroup *pc = lookup_page_cgroup(page);
+
+       spin_lock_irqsave(&zone->lru_lock, flags);
+       /* link when the page is linked to LRU but page_cgroup isn't */
+       if (PageLRU(page) && list_empty(&pc->lru))
+               mem_cgroup_add_lru_list(page, page_lru(page));
+       spin_unlock_irqrestore(&zone->lru_lock, flags);
 }
 
+
 void mem_cgroup_move_lists(struct page *page,
                           enum lru_list from, enum lru_list to)
 {
@@ -393,39 +469,116 @@ int mem_cgroup_calc_mapped_ratio(struct mem_cgroup *mem)
  */
 int mem_cgroup_get_reclaim_priority(struct mem_cgroup *mem)
 {
-       return mem->prev_priority;
+       int prev_priority;
+
+       spin_lock(&mem->reclaim_param_lock);
+       prev_priority = mem->prev_priority;
+       spin_unlock(&mem->reclaim_param_lock);
+
+       return prev_priority;
 }
 
 void mem_cgroup_note_reclaim_priority(struct mem_cgroup *mem, int priority)
 {
+       spin_lock(&mem->reclaim_param_lock);
        if (priority < mem->prev_priority)
                mem->prev_priority = priority;
+       spin_unlock(&mem->reclaim_param_lock);
 }
 
 void mem_cgroup_record_reclaim_priority(struct mem_cgroup *mem, int priority)
 {
+       spin_lock(&mem->reclaim_param_lock);
        mem->prev_priority = priority;
+       spin_unlock(&mem->reclaim_param_lock);
 }
 
-/*
- * 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)
- */
+static int calc_inactive_ratio(struct mem_cgroup *memcg, unsigned long *present_pages)
+{
+       unsigned long active;
+       unsigned long inactive;
+       unsigned long gb;
+       unsigned long inactive_ratio;
 
-long mem_cgroup_calc_reclaim(struct mem_cgroup *mem, struct zone *zone,
-                                       int priority, enum lru_list lru)
+       inactive = mem_cgroup_get_all_zonestat(memcg, LRU_INACTIVE_ANON);
+       active = mem_cgroup_get_all_zonestat(memcg, LRU_ACTIVE_ANON);
+
+       gb = (inactive + active) >> (30 - PAGE_SHIFT);
+       if (gb)
+               inactive_ratio = int_sqrt(10 * gb);
+       else
+               inactive_ratio = 1;
+
+       if (present_pages) {
+               present_pages[0] = inactive;
+               present_pages[1] = active;
+       }
+
+       return inactive_ratio;
+}
+
+int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg)
+{
+       unsigned long active;
+       unsigned long inactive;
+       unsigned long present_pages[2];
+       unsigned long inactive_ratio;
+
+       inactive_ratio = calc_inactive_ratio(memcg, present_pages);
+
+       inactive = present_pages[0];
+       active = present_pages[1];
+
+       if (inactive * inactive_ratio < active)
+               return 1;
+
+       return 0;
+}
+
+unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg,
+                                      struct zone *zone,
+                                      enum lru_list lru)
+{
+       int nid = zone->zone_pgdat->node_id;
+       int zid = zone_idx(zone);
+       struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
+
+       return MEM_CGROUP_ZSTAT(mz, lru);
+}
+
+struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg,
+                                                     struct zone *zone)
 {
-       long nr_pages;
        int nid = zone->zone_pgdat->node_id;
        int zid = zone_idx(zone);
-       struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(mem, nid, zid);
+       struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
+
+       return &mz->reclaim_stat;
+}
+
+struct zone_reclaim_stat *
+mem_cgroup_get_reclaim_stat_from_page(struct page *page)
+{
+       struct page_cgroup *pc;
+       struct mem_cgroup_per_zone *mz;
+
+       if (mem_cgroup_disabled())
+               return NULL;
+
+       pc = lookup_page_cgroup(page);
+       /*
+        * Used bit is set without atomic ops but after smp_wmb().
+        * For making pc->mem_cgroup visible, insert smp_rmb() here.
+        */
+       smp_rmb();
+       if (!PageCgroupUsed(pc))
+               return NULL;
 
-       nr_pages = MEM_CGROUP_ZSTAT(mz, lru);
+       mz = page_cgroup_zoneinfo(pc);
+       if (!mz)
+               return NULL;
 
-       return (nr_pages >> priority);
+       return &mz->reclaim_stat;
 }
 
 unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
@@ -477,10 +630,10 @@ unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 
 /*
  * This routine finds the DFS walk successor. This routine should be
- * called with cgroup_mutex held
+ * called with hierarchy_mutex held
  */
 static struct mem_cgroup *
-mem_cgroup_get_next_node(struct mem_cgroup *curr, struct mem_cgroup *root_mem)
+__mem_cgroup_get_next_node(struct mem_cgroup *curr, struct mem_cgroup *root_mem)
 {
        struct cgroup *cgroup, *curr_cgroup, *root_cgroup;
 
@@ -491,19 +644,16 @@ mem_cgroup_get_next_node(struct mem_cgroup *curr, struct mem_cgroup *root_mem)
                /*
                 * Walk down to children
                 */
-               mem_cgroup_put(curr);
                cgroup = list_entry(curr_cgroup->children.next,
                                                struct cgroup, sibling);
                curr = mem_cgroup_from_cont(cgroup);
-               mem_cgroup_get(curr);
                goto done;
        }
 
 visit_parent:
        if (curr_cgroup == root_cgroup) {
-               mem_cgroup_put(curr);
-               curr = root_mem;
-               mem_cgroup_get(curr);
+               /* caller handles NULL case */
+               curr = NULL;
                goto done;
        }
 
@@ -511,11 +661,9 @@ visit_parent:
         * Goto next sibling
         */
        if (curr_cgroup->sibling.next != &curr_cgroup->parent->children) {
-               mem_cgroup_put(curr);
                cgroup = list_entry(curr_cgroup->sibling.next, struct cgroup,
                                                sibling);
                curr = mem_cgroup_from_cont(cgroup);
-               mem_cgroup_get(curr);
                goto done;
        }
 
@@ -526,7 +674,6 @@ visit_parent:
        goto visit_parent;
 
 done:
-       root_mem->last_scanned_child = curr;
        return curr;
 }
 
@@ -536,39 +683,74 @@ done:
  * that to reclaim free pages from.
  */
 static struct mem_cgroup *
-mem_cgroup_get_first_node(struct mem_cgroup *root_mem)
+mem_cgroup_get_next_node(struct mem_cgroup *root_mem)
 {
        struct cgroup *cgroup;
-       struct mem_cgroup *ret;
-       bool obsolete = (root_mem->last_scanned_child &&
-                               root_mem->last_scanned_child->obsolete);
+       struct mem_cgroup *orig, *next;
+       bool obsolete;
 
        /*
         * Scan all children under the mem_cgroup mem
         */
-       cgroup_lock();
+       mutex_lock(&mem_cgroup_subsys.hierarchy_mutex);
+
+       orig = root_mem->last_scanned_child;
+       obsolete = mem_cgroup_is_obsolete(orig);
+
        if (list_empty(&root_mem->css.cgroup->children)) {
-               ret = root_mem;
+               /*
+                * root_mem might have children before and last_scanned_child
+                * may point to one of them. We put it later.
+                */
+               if (orig)
+                       VM_BUG_ON(!obsolete);
+               next = NULL;
                goto done;
        }
 
-       if (!root_mem->last_scanned_child || obsolete) {
-
-               if (obsolete)
-                       mem_cgroup_put(root_mem->last_scanned_child);
-
+       if (!orig || obsolete) {
                cgroup = list_first_entry(&root_mem->css.cgroup->children,
                                struct cgroup, sibling);
-               ret = mem_cgroup_from_cont(cgroup);
-               mem_cgroup_get(ret);
+               next = mem_cgroup_from_cont(cgroup);
        } else
-               ret = mem_cgroup_get_next_node(root_mem->last_scanned_child,
-                                               root_mem);
+               next = __mem_cgroup_get_next_node(orig, root_mem);
 
 done:
-       root_mem->last_scanned_child = ret;
-       cgroup_unlock();
-       return ret;
+       if (next)
+               mem_cgroup_get(next);
+       root_mem->last_scanned_child = next;
+       if (orig)
+               mem_cgroup_put(orig);
+       mutex_unlock(&mem_cgroup_subsys.hierarchy_mutex);
+       return (next) ? next : root_mem;
+}
+
+static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
+{
+       if (do_swap_account) {
+               if (res_counter_check_under_limit(&mem->res) &&
+                       res_counter_check_under_limit(&mem->memsw))
+                       return true;
+       } else
+               if (res_counter_check_under_limit(&mem->res))
+                       return true;
+       return false;
+}
+
+static unsigned int get_swappiness(struct mem_cgroup *memcg)
+{
+       struct cgroup *cgrp = memcg->css.cgroup;
+       unsigned int swappiness;
+
+       /* root ? */
+       if (cgrp->parent == NULL)
+               return vm_swappiness;
+
+       spin_lock(&memcg->reclaim_param_lock);
+       swappiness = memcg->swappiness;
+       spin_unlock(&memcg->reclaim_param_lock);
+
+       return swappiness;
 }
 
 /*
@@ -591,26 +773,25 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
         * but there might be left over accounting, even after children
         * have left.
         */
-       ret = try_to_free_mem_cgroup_pages(root_mem, gfp_mask, noswap);
-       if (res_counter_check_under_limit(&root_mem->res))
+       ret = try_to_free_mem_cgroup_pages(root_mem, gfp_mask, noswap,
+                                          get_swappiness(root_mem));
+       if (mem_cgroup_check_under_limit(root_mem))
                return 0;
+       if (!root_mem->use_hierarchy)
+               return ret;
 
-       next_mem = mem_cgroup_get_first_node(root_mem);
+       next_mem = mem_cgroup_get_next_node(root_mem);
 
        while (next_mem != root_mem) {
-               if (next_mem->obsolete) {
-                       mem_cgroup_put(next_mem);
-                       cgroup_lock();
-                       next_mem = mem_cgroup_get_first_node(root_mem);
-                       cgroup_unlock();
+               if (mem_cgroup_is_obsolete(next_mem)) {
+                       next_mem = mem_cgroup_get_next_node(root_mem);
                        continue;
                }
-               ret = try_to_free_mem_cgroup_pages(next_mem, gfp_mask, noswap);
-               if (res_counter_check_under_limit(&root_mem->res))
+               ret = try_to_free_mem_cgroup_pages(next_mem, gfp_mask, noswap,
+                                                  get_swappiness(next_mem));
+               if (mem_cgroup_check_under_limit(root_mem))
                        return 0;
-               cgroup_lock();
-               next_mem = mem_cgroup_get_next_node(next_mem, root_mem);
-               cgroup_unlock();
+               next_mem = mem_cgroup_get_next_node(root_mem);
        }
        return ret;
 }
@@ -655,23 +836,17 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
         * thread group leader migrates. It's possible that mm is not
         * set, if so charge the init_mm (happens for pagecache usage).
         */
-       if (likely(!*memcg)) {
-               rcu_read_lock();
-               mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
-               if (unlikely(!mem)) {
-                       rcu_read_unlock();
-                       return 0;
-               }
-               /*
-                * For every charge from the cgroup, increment reference count
-                */
-               css_get(&mem->css);
+       mem = *memcg;
+       if (likely(!mem)) {
+               mem = try_get_mem_cgroup_from_mm(mm);
                *memcg = mem;
-               rcu_read_unlock();
        } else {
-               mem = *memcg;
                css_get(&mem->css);
        }
+       if (unlikely(!mem))
+               return 0;
+
+       VM_BUG_ON(mem_cgroup_is_obsolete(mem));
 
        while (1) {
                int ret;
@@ -709,17 +884,15 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
                 * current usage of the cgroup before giving up
                 *
                 */
-               if (!do_swap_account &&
-                       res_counter_check_under_limit(&mem->res))
-                       continue;
-               if (do_swap_account &&
-                       res_counter_check_under_limit(&mem->memsw))
+               if (mem_cgroup_check_under_limit(mem_over_limit))
                        continue;
 
                if (!nr_retries--) {
                        if (oom) {
-                               mem_cgroup_out_of_memory(mem, gfp_mask);
-                               mem->last_oom_jiffies = jiffies;
+                               mutex_lock(&memcg_tasklist);
+                               mem_cgroup_out_of_memory(mem_over_limit, gfp_mask);
+                               mutex_unlock(&memcg_tasklist);
+                               mem_over_limit->last_oom_jiffies = jiffies;
                        }
                        goto nomem;
                }
@@ -730,27 +903,25 @@ nomem:
        return -ENOMEM;
 }
 
-/**
- * mem_cgroup_try_charge - get charge of PAGE_SIZE.
- * @mm: an mm_struct which is charged against. (when *memcg is NULL)
- * @gfp_mask: gfp_mask for reclaim.
- * @memcg: a pointer to memory cgroup which is charged against.
- *
- * charge against memory cgroup pointed by *memcg. if *memcg == NULL, estimated
- * memory cgroup from @mm is got and stored in *memcg.
- *
- * Returns 0 if success. -ENOMEM at failure.
- * This call can invoke OOM-Killer.
- */
-
-int mem_cgroup_try_charge(struct mm_struct *mm,
-                         gfp_t mask, struct mem_cgroup **memcg)
+static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page)
 {
-       return __mem_cgroup_try_charge(mm, mask, memcg, true);
+       struct mem_cgroup *mem;
+       swp_entry_t ent;
+
+       if (!PageSwapCache(page))
+               return NULL;
+
+       ent.val = page_private(page);
+       mem = lookup_swap_cgroup(ent);
+       if (!mem)
+               return NULL;
+       if (!css_tryget(&mem->css))
+               return NULL;
+       return mem;
 }
 
 /*
- * commit a charge got by mem_cgroup_try_charge() and makes page_cgroup to be
+ * commit a charge got by __mem_cgroup_try_charge() and makes page_cgroup to be
  * USED state. If already USED, uncharge and return.
  */
 
@@ -820,14 +991,15 @@ static int mem_cgroup_move_account(struct page_cgroup *pc,
        if (pc->mem_cgroup != from)
                goto out;
 
-       css_put(&from->css);
        res_counter_uncharge(&from->res, PAGE_SIZE);
        mem_cgroup_charge_statistics(from, pc, false);
        if (do_swap_account)
                res_counter_uncharge(&from->memsw, PAGE_SIZE);
+       css_put(&from->css);
+
+       css_get(&to->css);
        pc->mem_cgroup = to;
        mem_cgroup_charge_statistics(to, pc, true);
-       css_get(&to->css);
        ret = 0;
 out:
        unlock_page_cgroup(pc);
@@ -860,8 +1032,10 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc,
        if (ret || !parent)
                return ret;
 
-       if (!get_page_unless_zero(page))
-               return -EBUSY;
+       if (!get_page_unless_zero(page)) {
+               ret = -EBUSY;
+               goto uncharge;
+       }
 
        ret = isolate_lru_page(page);
 
@@ -870,19 +1044,23 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc,
 
        ret = mem_cgroup_move_account(pc, child, parent);
 
-       /* drop extra refcnt by try_charge() (move_account increment one) */
-       css_put(&parent->css);
        putback_lru_page(page);
        if (!ret) {
                put_page(page);
+               /* drop extra refcnt by try_charge() */
+               css_put(&parent->css);
                return 0;
        }
-       /* uncharge if move fails */
+
 cancel:
+       put_page(page);
+uncharge:
+       /* drop extra refcnt by try_charge() */
+       css_put(&parent->css);
+       /* uncharge if move fails */
        res_counter_uncharge(&parent->res, PAGE_SIZE);
        if (do_swap_account)
                res_counter_uncharge(&parent->memsw, PAGE_SIZE);
-       put_page(page);
        return ret;
 }
 
@@ -940,6 +1118,9 @@ int mem_cgroup_newpage_charge(struct page *page,
 int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
                                gfp_t gfp_mask)
 {
+       struct mem_cgroup *mem = NULL;
+       int ret;
+
        if (mem_cgroup_disabled())
                return 0;
        if (PageCompound(page))
@@ -952,6 +1133,8 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
         * 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.)
+        * And when the page is SwapCache, it should take swap information
+        * into account. This is under lock_page() now.
         */
        if (!(gfp_mask & __GFP_WAIT)) {
                struct page_cgroup *pc;
@@ -968,30 +1151,60 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
                unlock_page_cgroup(pc);
        }
 
-       if (unlikely(!mm))
+       if (do_swap_account && PageSwapCache(page)) {
+               mem = try_get_mem_cgroup_from_swapcache(page);
+               if (mem)
+                       mm = NULL;
+                 else
+                       mem = NULL;
+               /* SwapCache may be still linked to LRU now. */
+               mem_cgroup_lru_del_before_commit_swapcache(page);
+       }
+
+       if (unlikely(!mm && !mem))
                mm = &init_mm;
 
        if (page_is_file_cache(page))
                return mem_cgroup_charge_common(page, mm, gfp_mask,
                                MEM_CGROUP_CHARGE_TYPE_CACHE, NULL);
-       else
-               return mem_cgroup_charge_common(page, mm, gfp_mask,
-                               MEM_CGROUP_CHARGE_TYPE_SHMEM, NULL);
+
+       ret = mem_cgroup_charge_common(page, mm, gfp_mask,
+                               MEM_CGROUP_CHARGE_TYPE_SHMEM, mem);
+       if (mem)
+               css_put(&mem->css);
+       if (PageSwapCache(page))
+               mem_cgroup_lru_add_after_commit_swapcache(page);
+
+       if (do_swap_account && !ret && PageSwapCache(page)) {
+               swp_entry_t ent = {.val = page_private(page)};
+               /* avoid double counting */
+               mem = swap_cgroup_record(ent, NULL);
+               if (mem) {
+                       res_counter_uncharge(&mem->memsw, PAGE_SIZE);
+                       mem_cgroup_put(mem);
+               }
+       }
+       return ret;
 }
 
+/*
+ * While swap-in, try_charge -> commit or cancel, the page is locked.
+ * And when try_charge() successfully returns, one refcnt to memcg without
+ * struct page_cgroup is aquired. This refcnt will be cumsumed by
+ * "commit()" or removed by "cancel()"
+ */
 int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
                                 struct page *page,
                                 gfp_t mask, struct mem_cgroup **ptr)
 {
        struct mem_cgroup *mem;
-       swp_entry_t     ent;
+       int ret;
 
        if (mem_cgroup_disabled())
                return 0;
 
        if (!do_swap_account)
                goto charge_cur_mm;
-
        /*
         * A racing thread's fault, or swapoff, may have already updated
         * the pte, and even removed page from swap cache: return success
@@ -999,70 +1212,20 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
         */
        if (!PageSwapCache(page))
                return 0;
-
-       ent.val = page_private(page);
-
-       mem = lookup_swap_cgroup(ent);
-       if (!mem || mem->obsolete)
+       mem = try_get_mem_cgroup_from_swapcache(page);
+       if (!mem)
                goto charge_cur_mm;
        *ptr = mem;
-       return __mem_cgroup_try_charge(NULL, mask, ptr, true);
+       ret = __mem_cgroup_try_charge(NULL, mask, ptr, true);
+       /* drop extra refcnt from tryget */
+       css_put(&mem->css);
+       return ret;
 charge_cur_mm:
        if (unlikely(!mm))
                mm = &init_mm;
        return __mem_cgroup_try_charge(mm, mask, ptr, true);
 }
 
-#ifdef CONFIG_SWAP
-
-int mem_cgroup_cache_charge_swapin(struct page *page,
-                       struct mm_struct *mm, gfp_t mask, bool locked)
-{
-       int ret = 0;
-
-       if (mem_cgroup_disabled())
-               return 0;
-       if (unlikely(!mm))
-               mm = &init_mm;
-       if (!locked)
-               lock_page(page);
-       /*
-        * If not locked, the page can be dropped from SwapCache until
-        * we reach here.
-        */
-       if (PageSwapCache(page)) {
-               struct mem_cgroup *mem = NULL;
-               swp_entry_t ent;
-
-               ent.val = page_private(page);
-               if (do_swap_account) {
-                       mem = lookup_swap_cgroup(ent);
-                       if (mem && mem->obsolete)
-                               mem = NULL;
-                       if (mem)
-                               mm = NULL;
-               }
-               ret = mem_cgroup_charge_common(page, mm, mask,
-                               MEM_CGROUP_CHARGE_TYPE_SHMEM, mem);
-
-               if (!ret && do_swap_account) {
-                       /* avoid double counting */
-                       mem = swap_cgroup_record(ent, NULL);
-                       if (mem) {
-                               res_counter_uncharge(&mem->memsw, PAGE_SIZE);
-                               mem_cgroup_put(mem);
-                       }
-               }
-       }
-       if (!locked)
-               unlock_page(page);
-       /* add this page(page_cgroup) to the LRU we want. */
-       mem_cgroup_lru_fixup(page);
-
-       return ret;
-}
-#endif
-
 void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
 {
        struct page_cgroup *pc;
@@ -1072,26 +1235,28 @@ void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
        if (!ptr)
                return;
        pc = lookup_page_cgroup(page);
+       mem_cgroup_lru_del_before_commit_swapcache(page);
        __mem_cgroup_commit_charge(ptr, pc, MEM_CGROUP_CHARGE_TYPE_MAPPED);
+       mem_cgroup_lru_add_after_commit_swapcache(page);
        /*
         * Now swap is on-memory. This means this page may be
         * counted both as mem and swap....double count.
-        * Fix it by uncharging from memsw. This SwapCache is stable
-        * because we're still under lock_page().
+        * Fix it by uncharging from memsw. Basically, this SwapCache is stable
+        * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
+        * may call delete_from_swap_cache() before reach here.
         */
-       if (do_swap_account) {
+       if (do_swap_account && PageSwapCache(page)) {
                swp_entry_t ent = {.val = page_private(page)};
                struct mem_cgroup *memcg;
                memcg = swap_cgroup_record(ent, NULL);
                if (memcg) {
-                       /* If memcg is obsolete, memcg can be != ptr */
                        res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
                        mem_cgroup_put(memcg);
                }
 
        }
        /* add this page(page_cgroup) to the LRU we want. */
-       mem_cgroup_lru_fixup(page);
+
 }
 
 void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
@@ -1159,11 +1324,19 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
 
        mem_cgroup_charge_statistics(mem, pc, false);
        ClearPageCgroupUsed(pc);
+       /*
+        * pc->mem_cgroup is not cleared here. It will be accessed when it's
+        * freed from LRU. This is safe because uncharged page is expected not
+        * to be reused (freed soon). Exception is SwapCache, it's handled by
+        * special functions.
+        */
 
        mz = page_cgroup_zoneinfo(pc);
        unlock_page_cgroup(pc);
 
-       css_put(&mem->css);
+       /* at swapout, this memcg will be accessed to record to swap */
+       if (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
+               css_put(&mem->css);
 
        return mem;
 
@@ -1204,6 +1377,8 @@ void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
                swap_cgroup_record(ent, memcg);
                mem_cgroup_get(memcg);
        }
+       if (memcg)
+               css_put(&memcg->css);
 }
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
@@ -1248,7 +1423,7 @@ int mem_cgroup_prepare_migration(struct page *page, struct mem_cgroup **ptr)
        unlock_page_cgroup(pc);
 
        if (mem) {
-               ret = mem_cgroup_try_charge(NULL, GFP_HIGHUSER_MOVABLE, &mem);
+               ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false);
                css_put(&mem->css);
        }
        *ptr = mem;
@@ -1312,29 +1487,26 @@ void mem_cgroup_end_migration(struct mem_cgroup *mem,
  * 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.
  */
-int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask)
+int mem_cgroup_shrink_usage(struct page *page,
+                           struct mm_struct *mm,
+                           gfp_t gfp_mask)
 {
-       struct mem_cgroup *mem;
+       struct mem_cgroup *mem = NULL;
        int progress = 0;
        int retry = MEM_CGROUP_RECLAIM_RETRIES;
 
        if (mem_cgroup_disabled())
                return 0;
-       if (!mm)
+       if (page)
+               mem = try_get_mem_cgroup_from_swapcache(page);
+       if (!mem && mm)
+               mem = try_get_mem_cgroup_from_mm(mm);
+       if (unlikely(!mem))
                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();
-
        do {
-               progress = try_to_free_mem_cgroup_pages(mem, gfp_mask, true);
-               progress += res_counter_check_under_limit(&mem->res);
+               progress = mem_cgroup_hierarchical_reclaim(mem, gfp_mask, true);
+               progress += mem_cgroup_check_under_limit(mem);
        } while (!progress && --retry);
 
        css_put(&mem->css);
@@ -1377,10 +1549,11 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
                if (!ret)
                        break;
 
-               progress = try_to_free_mem_cgroup_pages(memcg,
-                               GFP_HIGHUSER_MOVABLE, false);
+               progress = mem_cgroup_hierarchical_reclaim(memcg, GFP_KERNEL,
+                                                          false);
                if (!progress)                  retry_count--;
        }
+
        return ret;
 }
 
@@ -1418,7 +1591,7 @@ int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
                        break;
 
                oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
-               try_to_free_mem_cgroup_pages(memcg, GFP_HIGHUSER_MOVABLE, true);
+               mem_cgroup_hierarchical_reclaim(memcg, GFP_KERNEL, true);
                curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
                if (curusage >= oldusage)
                        retry_count--;
@@ -1464,7 +1637,7 @@ static int mem_cgroup_force_empty_list(struct mem_cgroup *mem,
                }
                spin_unlock_irqrestore(&zone->lru_lock, flags);
 
-               ret = mem_cgroup_move_parent(pc, mem, GFP_HIGHUSER_MOVABLE);
+               ret = mem_cgroup_move_parent(pc, mem, GFP_KERNEL);
                if (ret == -ENOMEM)
                        break;
 
@@ -1549,8 +1722,8 @@ try_to_free:
                        ret = -EINTR;
                        goto out;
                }
-               progress = try_to_free_mem_cgroup_pages(mem,
-                                                 GFP_HIGHUSER_MOVABLE, false);
+               progress = try_to_free_mem_cgroup_pages(mem, GFP_KERNEL,
+                                               false, get_swappiness(mem));
                if (!progress) {
                        nr_retries--;
                        /* maybe some writeback is necessary */
@@ -1664,6 +1837,34 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
        return ret;
 }
 
+static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
+               unsigned long long *mem_limit, unsigned long long *memsw_limit)
+{
+       struct cgroup *cgroup;
+       unsigned long long min_limit, min_memsw_limit, tmp;
+
+       min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
+       min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
+       cgroup = memcg->css.cgroup;
+       if (!memcg->use_hierarchy)
+               goto out;
+
+       while (cgroup->parent) {
+               cgroup = cgroup->parent;
+               memcg = mem_cgroup_from_cont(cgroup);
+               if (!memcg->use_hierarchy)
+                       break;
+               tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
+               min_limit = min(min_limit, tmp);
+               tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
+               min_memsw_limit = min(min_memsw_limit, tmp);
+       }
+out:
+       *mem_limit = min_limit;
+       *memsw_limit = min_memsw_limit;
+       return;
+}
+
 static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
 {
        struct mem_cgroup *mem;
@@ -1737,6 +1938,74 @@ static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
                cb->fill(cb, "unevictable", unevictable * PAGE_SIZE);
 
        }
+       {
+               unsigned long long limit, memsw_limit;
+               memcg_get_hierarchical_limit(mem_cont, &limit, &memsw_limit);
+               cb->fill(cb, "hierarchical_memory_limit", limit);
+               if (do_swap_account)
+                       cb->fill(cb, "hierarchical_memsw_limit", memsw_limit);
+       }
+
+#ifdef CONFIG_DEBUG_VM
+       cb->fill(cb, "inactive_ratio", calc_inactive_ratio(mem_cont, NULL));
+
+       {
+               int nid, zid;
+               struct mem_cgroup_per_zone *mz;
+               unsigned long recent_rotated[2] = {0, 0};
+               unsigned long recent_scanned[2] = {0, 0};
+
+               for_each_online_node(nid)
+                       for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+                               mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
+
+                               recent_rotated[0] +=
+                                       mz->reclaim_stat.recent_rotated[0];
+                               recent_rotated[1] +=
+                                       mz->reclaim_stat.recent_rotated[1];
+                               recent_scanned[0] +=
+                                       mz->reclaim_stat.recent_scanned[0];
+                               recent_scanned[1] +=
+                                       mz->reclaim_stat.recent_scanned[1];
+                       }
+               cb->fill(cb, "recent_rotated_anon", recent_rotated[0]);
+               cb->fill(cb, "recent_rotated_file", recent_rotated[1]);
+               cb->fill(cb, "recent_scanned_anon", recent_scanned[0]);
+               cb->fill(cb, "recent_scanned_file", recent_scanned[1]);
+       }
+#endif
+
+       return 0;
+}
+
+static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft)
+{
+       struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+
+       return get_swappiness(memcg);
+}
+
+static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
+                                      u64 val)
+{
+       struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+       struct mem_cgroup *parent;
+       if (val > 100)
+               return -EINVAL;
+
+       if (cgrp->parent == NULL)
+               return -EINVAL;
+
+       parent = mem_cgroup_from_cont(cgrp->parent);
+       /* If under hierarchy, only empty-root can set this value */
+       if ((parent->use_hierarchy) ||
+           (memcg->use_hierarchy && !list_empty(&cgrp->children)))
+               return -EINVAL;
+
+       spin_lock(&memcg->reclaim_param_lock);
+       memcg->swappiness = val;
+       spin_unlock(&memcg->reclaim_param_lock);
+
        return 0;
 }
 
@@ -1778,6 +2047,11 @@ static struct cftype mem_cgroup_files[] = {
                .write_u64 = mem_cgroup_hierarchy_write,
                .read_u64 = mem_cgroup_hierarchy_read,
        },
+       {
+               .name = "swappiness",
+               .read_u64 = mem_cgroup_swappiness_read,
+               .write_u64 = mem_cgroup_swappiness_write,
+       },
 };
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
@@ -1886,20 +2160,13 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
  * the number of reference from swap_cgroup and free mem_cgroup when
  * it goes down to 0.
  *
- * When mem_cgroup is destroyed, mem->obsolete will be set to 0 and
- * entry which points to this memcg will be ignore at swapin.
- *
  * Removal of cgroup itself succeeds regardless of refs from swap.
  */
 
-static void mem_cgroup_free(struct mem_cgroup *mem)
+static void __mem_cgroup_free(struct mem_cgroup *mem)
 {
        int node;
 
-       if (atomic_read(&mem->refcnt) > 0)
-               return;
-
-
        for_each_node_state(node, N_POSSIBLE)
                free_mem_cgroup_per_zone_info(mem, node);
 
@@ -1916,11 +2183,8 @@ static void mem_cgroup_get(struct mem_cgroup *mem)
 
 static void mem_cgroup_put(struct mem_cgroup *mem)
 {
-       if (atomic_dec_and_test(&mem->refcnt)) {
-               if (!mem->obsolete)
-                       return;
-               mem_cgroup_free(mem);
-       }
+       if (atomic_dec_and_test(&mem->refcnt))
+               __mem_cgroup_free(mem);
 }
 
 
@@ -1965,14 +2229,15 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
                res_counter_init(&mem->res, NULL);
                res_counter_init(&mem->memsw, NULL);
        }
-
        mem->last_scanned_child = NULL;
+       spin_lock_init(&mem->reclaim_param_lock);
 
+       if (parent)
+               mem->swappiness = get_swappiness(parent);
+       atomic_set(&mem->refcnt, 1);
        return &mem->css;
 free_out:
-       for_each_node_state(node, N_POSSIBLE)
-               free_mem_cgroup_per_zone_info(mem, node);
-       mem_cgroup_free(mem);
+       __mem_cgroup_free(mem);
        return ERR_PTR(-ENOMEM);
 }
 
@@ -1980,14 +2245,20 @@ static void mem_cgroup_pre_destroy(struct cgroup_subsys *ss,
                                        struct cgroup *cont)
 {
        struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
-       mem->obsolete = 1;
        mem_cgroup_force_empty(mem, false);
 }
 
 static void mem_cgroup_destroy(struct cgroup_subsys *ss,
                                struct cgroup *cont)
 {
-       mem_cgroup_free(mem_cgroup_from_cont(cont));
+       struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
+       struct mem_cgroup *last_scanned_child = mem->last_scanned_child;
+
+       if (last_scanned_child) {
+               VM_BUG_ON(!mem_cgroup_is_obsolete(last_scanned_child));
+               mem_cgroup_put(last_scanned_child);
+       }
+       mem_cgroup_put(mem);
 }
 
 static int mem_cgroup_populate(struct cgroup_subsys *ss,
@@ -2008,25 +2279,12 @@ static void mem_cgroup_move_task(struct cgroup_subsys *ss,
                                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);
-
+       mutex_lock(&memcg_tasklist);
        /*
-        * Only thread group leaders are allowed to migrate, the mm_struct is
-        * in effect owned by the leader
+        * FIXME: It's better to move charges of this process from old
+        * memcg to new memcg. But it's just on TODO-List now.
         */
-       if (!thread_group_leader(p))
-               goto out;
-
-out:
-       mmput(mm);
+       mutex_unlock(&memcg_tasklist);
 }
 
 struct cgroup_subsys mem_cgroup_subsys = {