1 files changed, 653 insertions, 84 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9b10d8753784..e2b98a6875c0 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -29,6 +29,7 @@
 #include <linux/rcupdate.h>
 #include <linux/limits.h>
 #include <linux/mutex.h>
+#include <linux/rbtree.h>
 #include <linux/slab.h>
 #include <linux/swap.h>
 #include <linux/spinlock.h>
@@ -43,6 +44,7 @@
 
 struct cgroup_subsys mem_cgroup_subsys __read_mostly;
 #define MEM_CGROUP_RECLAIM_RETRIES      5
+struct mem_cgroup *root_mem_cgroup __read_mostly;
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 /* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
@@ -53,6 +55,7 @@ static int really_do_swap_account __initdata = 1; /* for remember boot option*/
 #endif
 
 static DEFINE_MUTEX(memcg_tasklist);    /* can be hold under cgroup_mutex */
+#define SOFTLIMIT_EVENTS_THRESH (1000)
 
 /*
  * Statistics for memory cgroup.
@@ -66,6 +69,8 @@ enum mem_cgroup_stat_index {
         MEM_CGROUP_STAT_MAPPED_FILE,  /* # of pages charged as file rss */
         MEM_CGROUP_STAT_PGPGIN_COUNT,   /* # of pages paged in */
         MEM_CGROUP_STAT_PGPGOUT_COUNT,  /* # of pages paged out */
+        MEM_CGROUP_STAT_EVENTS, /* sum of pagein + pageout for internal use */
+        MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
 
         MEM_CGROUP_STAT_NSTATS,
 };
@@ -78,6 +83,20 @@ struct mem_cgroup_stat {
         struct mem_cgroup_stat_cpu cpustat[0];
 };
 
+static inline void
+__mem_cgroup_stat_reset_safe(struct mem_cgroup_stat_cpu *stat,
+                                enum mem_cgroup_stat_index idx)
+{
+        stat->count[idx] = 0;
+}
+
+static inline s64
+__mem_cgroup_stat_read_local(struct mem_cgroup_stat_cpu *stat,
+                                enum mem_cgroup_stat_index idx)
+{
+        return stat->count[idx];
+}
+
 /*
  * For accounting under irq disable, no need for increment preempt count.
  */
@@ -117,6 +136,12 @@ struct mem_cgroup_per_zone {
         unsigned long           count[NR_LRU_LISTS];
 
         struct zone_reclaim_stat reclaim_stat;
+        struct rb_node          tree_node;      /* RB tree node */
+        unsigned long long      usage_in_excess;/* Set to the value by which */
+                                                /* the soft limit is exceeded*/
+        bool                    on_tree;
+        struct mem_cgroup       *mem;           /* Back pointer, we cannot */
+                                                /* use container_of        */
 };
 /* Macro for accessing counter */
 #define MEM_CGROUP_ZSTAT(mz, idx)       ((mz)->count[(idx)])
@@ -130,6 +155,26 @@ struct mem_cgroup_lru_info {
 };
 
 /*
+ * Cgroups above their limits are maintained in a RB-Tree, independent of
+ * their hierarchy representation
+ */
+
+struct mem_cgroup_tree_per_zone {
+        struct rb_root rb_root;
+        spinlock_t lock;
+};
+
+struct mem_cgroup_tree_per_node {
+        struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES];
+};
+
+struct mem_cgroup_tree {
+        struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
+};
+
+static struct mem_cgroup_tree soft_limit_tree __read_mostly;
+
+/*
  * 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,
@@ -186,6 +231,13 @@ struct mem_cgroup {
         struct mem_cgroup_stat stat;
 };
 
+/*
+ * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
+ * limit reclaim to prevent infinite loops, if they ever occur.
+ */
+#define MEM_CGROUP_MAX_RECLAIM_LOOPS            (100)
+#define MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS (2)
+
 enum charge_type {
         MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
         MEM_CGROUP_CHARGE_TYPE_MAPPED,
@@ -200,13 +252,8 @@ enum charge_type {
 #define PCGF_CACHE      (1UL << PCG_CACHE)
 #define PCGF_USED       (1UL << PCG_USED)
 #define PCGF_LOCK       (1UL << PCG_LOCK)
-static const unsigned long
-pcg_default_flags[NR_CHARGE_TYPE] = {
-        PCGF_CACHE | PCGF_USED | PCGF_LOCK, /* File Cache */
-        PCGF_USED | PCGF_LOCK, /* Anon */
-        PCGF_CACHE | PCGF_USED | PCGF_LOCK, /* Shmem */
-        0, /* FORCE */
-};
+/* Not used, but added here for completeness */
+#define PCGF_ACCT       (1UL << PCG_ACCT)
 
 /* for encoding cft->private value on file */
 #define _MEM                    (0)
@@ -215,15 +262,241 @@ pcg_default_flags[NR_CHARGE_TYPE] = {
 #define MEMFILE_TYPE(val)       (((val) >> 16) & 0xffff)
 #define MEMFILE_ATTR(val)       ((val) & 0xffff)
 
+/*
+ * Reclaim flags for mem_cgroup_hierarchical_reclaim
+ */
+#define MEM_CGROUP_RECLAIM_NOSWAP_BIT   0x0
+#define MEM_CGROUP_RECLAIM_NOSWAP       (1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT)
+#define MEM_CGROUP_RECLAIM_SHRINK_BIT   0x1
+#define MEM_CGROUP_RECLAIM_SHRINK       (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT)
+#define MEM_CGROUP_RECLAIM_SOFT_BIT     0x2
+#define MEM_CGROUP_RECLAIM_SOFT         (1 << MEM_CGROUP_RECLAIM_SOFT_BIT)
+
 static void mem_cgroup_get(struct mem_cgroup *mem);
 static void mem_cgroup_put(struct mem_cgroup *mem);
 static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem);
 
+static struct mem_cgroup_per_zone *
+mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid)
+{
+        return &mem->info.nodeinfo[nid]->zoneinfo[zid];
+}
+
+static 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);
+
+        if (!mem)
+                return NULL;
+
+        return mem_cgroup_zoneinfo(mem, nid, zid);
+}
+
+static struct mem_cgroup_tree_per_zone *
+soft_limit_tree_node_zone(int nid, int zid)
+{
+        return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
+}
+
+static struct mem_cgroup_tree_per_zone *
+soft_limit_tree_from_page(struct page *page)
+{
+        int nid = page_to_nid(page);
+        int zid = page_zonenum(page);
+
+        return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
+}
+
+static void
+__mem_cgroup_insert_exceeded(struct mem_cgroup *mem,
+                                struct mem_cgroup_per_zone *mz,
+                                struct mem_cgroup_tree_per_zone *mctz)
+{
+        struct rb_node **p = &mctz->rb_root.rb_node;
+        struct rb_node *parent = NULL;
+        struct mem_cgroup_per_zone *mz_node;
+
+        if (mz->on_tree)
+                return;
+
+        mz->usage_in_excess = res_counter_soft_limit_excess(&mem->res);
+        while (*p) {
+                parent = *p;
+                mz_node = rb_entry(parent, struct mem_cgroup_per_zone,
+                                        tree_node);
+                if (mz->usage_in_excess < mz_node->usage_in_excess)
+                        p = &(*p)->rb_left;
+                /*
+                 * We can't avoid mem cgroups that are over their soft
+                 * limit by the same amount
+                 */
+                else if (mz->usage_in_excess >= mz_node->usage_in_excess)
+                        p = &(*p)->rb_right;
+        }
+        rb_link_node(&mz->tree_node, parent, p);
+        rb_insert_color(&mz->tree_node, &mctz->rb_root);
+        mz->on_tree = true;
+}
+
+static void
+__mem_cgroup_remove_exceeded(struct mem_cgroup *mem,
+                                struct mem_cgroup_per_zone *mz,
+                                struct mem_cgroup_tree_per_zone *mctz)
+{
+        if (!mz->on_tree)
+                return;
+        rb_erase(&mz->tree_node, &mctz->rb_root);
+        mz->on_tree = false;
+}
+
+static void
+mem_cgroup_insert_exceeded(struct mem_cgroup *mem,
+                                struct mem_cgroup_per_zone *mz,
+                                struct mem_cgroup_tree_per_zone *mctz)
+{
+        spin_lock(&mctz->lock);
+        __mem_cgroup_insert_exceeded(mem, mz, mctz);
+        spin_unlock(&mctz->lock);
+}
+
+static void
+mem_cgroup_remove_exceeded(struct mem_cgroup *mem,
+                                struct mem_cgroup_per_zone *mz,
+                                struct mem_cgroup_tree_per_zone *mctz)
+{
+        spin_lock(&mctz->lock);
+        __mem_cgroup_remove_exceeded(mem, mz, mctz);
+        spin_unlock(&mctz->lock);
+}
+
+static bool mem_cgroup_soft_limit_check(struct mem_cgroup *mem)
+{
+        bool ret = false;
+        int cpu;
+        s64 val;
+        struct mem_cgroup_stat_cpu *cpustat;
+
+        cpu = get_cpu();
+        cpustat = &mem->stat.cpustat[cpu];
+        val = __mem_cgroup_stat_read_local(cpustat, MEM_CGROUP_STAT_EVENTS);
+        if (unlikely(val > SOFTLIMIT_EVENTS_THRESH)) {
+                __mem_cgroup_stat_reset_safe(cpustat, MEM_CGROUP_STAT_EVENTS);
+                ret = true;
+        }
+        put_cpu();
+        return ret;
+}
+
+static void mem_cgroup_update_tree(struct mem_cgroup *mem, struct page *page)
+{
+        unsigned long long prev_usage_in_excess, new_usage_in_excess;
+        bool updated_tree = false;
+        struct mem_cgroup_per_zone *mz;
+        struct mem_cgroup_tree_per_zone *mctz;
+
+        mz = mem_cgroup_zoneinfo(mem, page_to_nid(page), page_zonenum(page));
+        mctz = soft_limit_tree_from_page(page);
+
+        /*
+         * We do updates in lazy mode, mem's are removed
+         * lazily from the per-zone, per-node rb tree
+         */
+        prev_usage_in_excess = mz->usage_in_excess;
+
+        new_usage_in_excess = res_counter_soft_limit_excess(&mem->res);
+        if (prev_usage_in_excess) {
+                mem_cgroup_remove_exceeded(mem, mz, mctz);
+                updated_tree = true;
+        }
+        if (!new_usage_in_excess)
+                goto done;
+        mem_cgroup_insert_exceeded(mem, mz, mctz);
+
+done:
+        if (updated_tree) {
+                spin_lock(&mctz->lock);
+                mz->usage_in_excess = new_usage_in_excess;
+                spin_unlock(&mctz->lock);
+        }
+}
+
+static void mem_cgroup_remove_from_trees(struct mem_cgroup *mem)
+{
+        int node, zone;
+        struct mem_cgroup_per_zone *mz;
+        struct mem_cgroup_tree_per_zone *mctz;
+
+        for_each_node_state(node, N_POSSIBLE) {
+                for (zone = 0; zone < MAX_NR_ZONES; zone++) {
+                        mz = mem_cgroup_zoneinfo(mem, node, zone);
+                        mctz = soft_limit_tree_node_zone(node, zone);
+                        mem_cgroup_remove_exceeded(mem, mz, mctz);
+                }
+        }
+}
+
+static inline unsigned long mem_cgroup_get_excess(struct mem_cgroup *mem)
+{
+        return res_counter_soft_limit_excess(&mem->res) >> PAGE_SHIFT;
+}
+
+static struct mem_cgroup_per_zone *
+__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
+{
+        struct rb_node *rightmost = NULL;
+        struct mem_cgroup_per_zone *mz = NULL;
+
+retry:
+        rightmost = rb_last(&mctz->rb_root);
+        if (!rightmost)
+                goto done;              /* Nothing to reclaim from */
+
+        mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node);
+        /*
+         * Remove the node now but someone else can add it back,
+         * we will to add it back at the end of reclaim to its correct
+         * position in the tree.
+         */
+        __mem_cgroup_remove_exceeded(mz->mem, mz, mctz);
+        if (!res_counter_soft_limit_excess(&mz->mem->res) ||
+                !css_tryget(&mz->mem->css))
+                goto retry;
+done:
+        return mz;
+}
+
+static struct mem_cgroup_per_zone *
+mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
+{
+        struct mem_cgroup_per_zone *mz;
+
+        spin_lock(&mctz->lock);
+        mz = __mem_cgroup_largest_soft_limit_node(mctz);
+        spin_unlock(&mctz->lock);
+        return mz;
+}
+
+static void mem_cgroup_swap_statistics(struct mem_cgroup *mem,
+                                         bool charge)
+{
+        int val = (charge) ? 1 : -1;
+        struct mem_cgroup_stat *stat = &mem->stat;
+        struct mem_cgroup_stat_cpu *cpustat;
+        int cpu = get_cpu();
+
+        cpustat = &stat->cpustat[cpu];
+        __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_SWAPOUT, val);
+        put_cpu();
+}
+
 static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
                                          struct page_cgroup *pc,
                                          bool charge)
 {
-        int val = (charge)? 1 : -1;
+        int val = (charge) ? 1 : -1;
         struct mem_cgroup_stat *stat = &mem->stat;
         struct mem_cgroup_stat_cpu *cpustat;
         int cpu = get_cpu();
@@ -240,28 +513,10 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
         else
                 __mem_cgroup_stat_add_safe(cpustat,
                                 MEM_CGROUP_STAT_PGPGOUT_COUNT, 1);
+        __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_EVENTS, 1);
         put_cpu();
 }
 
-static struct mem_cgroup_per_zone *
-mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid)
-{
-        return &mem->info.nodeinfo[nid]->zoneinfo[zid];
-}
-
-static 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);
-
-        if (!mem)
-                return NULL;
-
-        return mem_cgroup_zoneinfo(mem, nid, zid);
-}
-
 static unsigned long mem_cgroup_get_local_zonestat(struct mem_cgroup *mem,
                                         enum lru_list idx)
 {
@@ -354,6 +609,11 @@ static int mem_cgroup_walk_tree(struct mem_cgroup *root, void *data,
         return ret;
 }
 
+static inline bool mem_cgroup_is_root(struct mem_cgroup *mem)
+{
+        return (mem == root_mem_cgroup);
+}
+
 /*
  * Following LRU functions are allowed to be used without PCG_LOCK.
  * Operations are called by routine of global LRU independently from memcg.
@@ -371,22 +631,24 @@ static int mem_cgroup_walk_tree(struct mem_cgroup *root, void *data,
 void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru)
 {
         struct page_cgroup *pc;
-        struct mem_cgroup *mem;
         struct mem_cgroup_per_zone *mz;
 
         if (mem_cgroup_disabled())
                 return;
         pc = lookup_page_cgroup(page);
         /* can happen while we handle swapcache. */
-        if (list_empty(&pc->lru) || !pc->mem_cgroup)
+        if (!TestClearPageCgroupAcctLRU(pc))
                 return;
+        VM_BUG_ON(!pc->mem_cgroup);
         /*
          * 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;
+        if (mem_cgroup_is_root(pc->mem_cgroup))
+                return;
+        VM_BUG_ON(list_empty(&pc->lru));
         list_del_init(&pc->lru);
         return;
 }
@@ -410,8 +672,8 @@ void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
          * For making pc->mem_cgroup visible, insert smp_rmb() here.
          */
         smp_rmb();
-        /* unused page is not rotated. */
-        if (!PageCgroupUsed(pc))
+        /* unused or root page is not rotated. */
+        if (!PageCgroupUsed(pc) || mem_cgroup_is_root(pc->mem_cgroup))
                 return;
         mz = page_cgroup_zoneinfo(pc);
         list_move(&pc->lru, &mz->lists[lru]);
@@ -425,6 +687,7 @@ void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
         if (mem_cgroup_disabled())
                 return;
         pc = lookup_page_cgroup(page);
+        VM_BUG_ON(PageCgroupAcctLRU(pc));
         /*
          * Used bit is set without atomic ops but after smp_wmb().
          * For making pc->mem_cgroup visible, insert smp_rmb() here.
@@ -435,6 +698,9 @@ void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
 
         mz = page_cgroup_zoneinfo(pc);
         MEM_CGROUP_ZSTAT(mz, lru) += 1;
+        SetPageCgroupAcctLRU(pc);
+        if (mem_cgroup_is_root(pc->mem_cgroup))
+                return;
         list_add(&pc->lru, &mz->lists[lru]);
 }
 
@@ -469,7 +735,7 @@ static void mem_cgroup_lru_add_after_commit_swapcache(struct page *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))
+        if (PageLRU(page) && !PageCgroupAcctLRU(pc))
                 mem_cgroup_add_lru_list(page, page_lru(page));
         spin_unlock_irqrestore(&zone->lru_lock, flags);
 }
@@ -855,28 +1121,62 @@ mem_cgroup_select_victim(struct mem_cgroup *root_mem)
  * If shrink==true, for avoiding to free too much, this returns immedieately.
  */
 static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
-                                   gfp_t gfp_mask, bool noswap, bool shrink)
+                                                struct zone *zone,
+                                                gfp_t gfp_mask,
+                                                unsigned long reclaim_options)
 {
         struct mem_cgroup *victim;
         int ret, total = 0;
         int loop = 0;
+        bool noswap = reclaim_options & MEM_CGROUP_RECLAIM_NOSWAP;
+        bool shrink = reclaim_options & MEM_CGROUP_RECLAIM_SHRINK;
+        bool check_soft = reclaim_options & MEM_CGROUP_RECLAIM_SOFT;
+        unsigned long excess = mem_cgroup_get_excess(root_mem);
 
         /* If memsw_is_minimum==1, swap-out is of-no-use. */
         if (root_mem->memsw_is_minimum)
                 noswap = true;
 
-        while (loop < 2) {
+        while (1) {
                 victim = mem_cgroup_select_victim(root_mem);
-                if (victim == root_mem)
+                if (victim == root_mem) {
                         loop++;
+                        if (loop >= 2) {
+                                /*
+                                 * If we have not been able to reclaim
+                                 * anything, it might because there are
+                                 * no reclaimable pages under this hierarchy
+                                 */
+                                if (!check_soft || !total) {
+                                        css_put(&victim->css);
+                                        break;
+                                }
+                                /*
+                                 * We want to do more targetted reclaim.
+                                 * excess >> 2 is not to excessive so as to
+                                 * reclaim too much, nor too less that we keep
+                                 * coming back to reclaim from this cgroup
+                                 */
+                                if (total >= (excess >> 2) ||
+                                        (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS)) {
+                                        css_put(&victim->css);
+                                        break;
+                                }
+                        }
+                }
                 if (!mem_cgroup_local_usage(&victim->stat)) {
                         /* this cgroup's local usage == 0 */
                         css_put(&victim->css);
                         continue;
                 }
                 /* we use swappiness of local cgroup */
-                ret = try_to_free_mem_cgroup_pages(victim, gfp_mask, noswap,
-                                                   get_swappiness(victim));
+                if (check_soft)
+                        ret = mem_cgroup_shrink_node_zone(victim, gfp_mask,
+                                noswap, get_swappiness(victim), zone,
+                                zone->zone_pgdat->node_id);
+                else
+                        ret = try_to_free_mem_cgroup_pages(victim, gfp_mask,
+                                                noswap, get_swappiness(victim));
                 css_put(&victim->css);
                 /*
                  * At shrinking usage, we can't check we should stop here or
@@ -886,7 +1186,10 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
                 if (shrink)
                         return ret;
                 total += ret;
-                if (mem_cgroup_check_under_limit(root_mem))
+                if (check_soft) {
+                        if (res_counter_check_under_soft_limit(&root_mem->res))
+                                return total;
+                } else if (mem_cgroup_check_under_limit(root_mem))
                         return 1 + total;
         }
         return total;
@@ -965,11 +1268,11 @@ done:
  */
 static int __mem_cgroup_try_charge(struct mm_struct *mm,
                         gfp_t gfp_mask, struct mem_cgroup **memcg,
-                        bool oom)
+                        bool oom, struct page *page)
 {
-        struct mem_cgroup *mem, *mem_over_limit;
+        struct mem_cgroup *mem, *mem_over_limit, *mem_over_soft_limit;
         int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
-        struct res_counter *fail_res;
+        struct res_counter *fail_res, *soft_fail_res = NULL;
 
         if (unlikely(test_thread_flag(TIF_MEMDIE))) {
                 /* Don't account this! */
@@ -996,20 +1299,23 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
         VM_BUG_ON(css_is_removed(&mem->css));
 
         while (1) {
-                int ret;
-                bool noswap = false;
+                int ret = 0;
+                unsigned long flags = 0;
 
-                ret = res_counter_charge(&mem->res, PAGE_SIZE, &fail_res);
+                if (mem_cgroup_is_root(mem))
+                        goto done;
+                ret = res_counter_charge(&mem->res, PAGE_SIZE, &fail_res,
+                                                &soft_fail_res);
                 if (likely(!ret)) {
                         if (!do_swap_account)
                                 break;
                         ret = res_counter_charge(&mem->memsw, PAGE_SIZE,
-                                                        &fail_res);
+                                                        &fail_res, NULL);
                         if (likely(!ret))
                                 break;
                         /* mem+swap counter fails */
-                        res_counter_uncharge(&mem->res, PAGE_SIZE);
-                        noswap = true;
+                        res_counter_uncharge(&mem->res, PAGE_SIZE, NULL);
+                        flags |= MEM_CGROUP_RECLAIM_NOSWAP;
                         mem_over_limit = mem_cgroup_from_res_counter(fail_res,
                                                                         memsw);
                 } else
@@ -1020,8 +1326,8 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
                 if (!(gfp_mask & __GFP_WAIT))
                         goto nomem;
 
-                ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, gfp_mask,
-                                                        noswap, false);
+                ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL,
+                                                gfp_mask, flags);
                 if (ret)
                         continue;
 
@@ -1046,13 +1352,24 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
                         goto nomem;
                 }
         }
+        /*
+         * Insert just the ancestor, we should trickle down to the correct
+         * cgroup for reclaim, since the other nodes will be below their
+         * soft limit
+         */
+        if (soft_fail_res) {
+                mem_over_soft_limit =
+                        mem_cgroup_from_res_counter(soft_fail_res, res);
+                if (mem_cgroup_soft_limit_check(mem_over_soft_limit))
+                        mem_cgroup_update_tree(mem_over_soft_limit, page);
+        }
+done:
         return 0;
 nomem:
         css_put(&mem->css);
         return -ENOMEM;
 }
 
-
 /*
  * A helper function to get mem_cgroup from ID. must be called under
  * rcu_read_lock(). The caller must check css_is_removed() or some if
@@ -1119,15 +1436,38 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
         lock_page_cgroup(pc);
         if (unlikely(PageCgroupUsed(pc))) {
                 unlock_page_cgroup(pc);
-                res_counter_uncharge(&mem->res, PAGE_SIZE);
-                if (do_swap_account)
-                        res_counter_uncharge(&mem->memsw, PAGE_SIZE);
+                if (!mem_cgroup_is_root(mem)) {
+                        res_counter_uncharge(&mem->res, PAGE_SIZE, NULL);
+                        if (do_swap_account)
+                                res_counter_uncharge(&mem->memsw, PAGE_SIZE,
+                                                        NULL);
+                }
                 css_put(&mem->css);
                 return;
         }
+
         pc->mem_cgroup = mem;
+        /*
+         * We access a page_cgroup asynchronously without lock_page_cgroup().
+         * Especially when a page_cgroup is taken from a page, pc->mem_cgroup
+         * is accessed after testing USED bit. To make pc->mem_cgroup visible
+         * before USED bit, we need memory barrier here.
+         * See mem_cgroup_add_lru_list(), etc.
+         */
         smp_wmb();
-        pc->flags = pcg_default_flags[ctype];
+        switch (ctype) {
+        case MEM_CGROUP_CHARGE_TYPE_CACHE:
+        case MEM_CGROUP_CHARGE_TYPE_SHMEM:
+                SetPageCgroupCache(pc);
+                SetPageCgroupUsed(pc);
+                break;
+        case MEM_CGROUP_CHARGE_TYPE_MAPPED:
+                ClearPageCgroupCache(pc);
+                SetPageCgroupUsed(pc);
+                break;
+        default:
+                break;
+        }
 
         mem_cgroup_charge_statistics(mem, pc, true);
 
@@ -1178,7 +1518,8 @@ static int mem_cgroup_move_account(struct page_cgroup *pc,
         if (pc->mem_cgroup != from)
                 goto out;
 
-        res_counter_uncharge(&from->res, PAGE_SIZE);
+        if (!mem_cgroup_is_root(from))
+                res_counter_uncharge(&from->res, PAGE_SIZE, NULL);
         mem_cgroup_charge_statistics(from, pc, false);
 
         page = pc->page;
@@ -1197,8 +1538,8 @@ static int mem_cgroup_move_account(struct page_cgroup *pc,
                                                 1);
         }
 
-        if (do_swap_account)
-                res_counter_uncharge(&from->memsw, PAGE_SIZE);
+        if (do_swap_account && !mem_cgroup_is_root(from))
+                res_counter_uncharge(&from->memsw, PAGE_SIZE, NULL);
         css_put(&from->css);
 
         css_get(&to->css);
@@ -1238,7 +1579,7 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc,
         parent = mem_cgroup_from_cont(pcg);
 
 
-        ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false);
+        ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false, page);
         if (ret || !parent)
                 return ret;
 
@@ -1268,9 +1609,11 @@ 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);
+        if (!mem_cgroup_is_root(parent)) {
+                res_counter_uncharge(&parent->res, PAGE_SIZE, NULL);
+                if (do_swap_account)
+                        res_counter_uncharge(&parent->memsw, PAGE_SIZE, NULL);
+        }
         return ret;
 }
 
@@ -1295,7 +1638,7 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
         prefetchw(pc);
 
         mem = memcg;
-        ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true);
+        ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true, page);
         if (ret || !mem)
                 return ret;
 
@@ -1414,14 +1757,14 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
         if (!mem)
                 goto charge_cur_mm;
         *ptr = mem;
-        ret = __mem_cgroup_try_charge(NULL, mask, ptr, true);
+        ret = __mem_cgroup_try_charge(NULL, mask, ptr, true, page);
         /* 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);
+        return __mem_cgroup_try_charge(mm, mask, ptr, true, page);
 }
 
 static void
@@ -1459,7 +1802,10 @@ __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
                          * This recorded memcg can be obsolete one. So, avoid
                          * calling css_tryget
                          */
-                        res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
+                        if (!mem_cgroup_is_root(memcg))
+                                res_counter_uncharge(&memcg->memsw, PAGE_SIZE,
+                                                        NULL);
+                        mem_cgroup_swap_statistics(memcg, false);
                         mem_cgroup_put(memcg);
                 }
                 rcu_read_unlock();
@@ -1484,9 +1830,11 @@ void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
                 return;
         if (!mem)
                 return;
-        res_counter_uncharge(&mem->res, PAGE_SIZE);
-        if (do_swap_account)
-                res_counter_uncharge(&mem->memsw, PAGE_SIZE);
+        if (!mem_cgroup_is_root(mem)) {
+                res_counter_uncharge(&mem->res, PAGE_SIZE, NULL);
+                if (do_swap_account)
+                        res_counter_uncharge(&mem->memsw, PAGE_SIZE, NULL);
+        }
         css_put(&mem->css);
 }
 
@@ -1500,6 +1848,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
         struct page_cgroup *pc;
         struct mem_cgroup *mem = NULL;
         struct mem_cgroup_per_zone *mz;
+        bool soft_limit_excess = false;
 
         if (mem_cgroup_disabled())
                 return NULL;
@@ -1538,9 +1887,14 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
                 break;
         }
 
-        res_counter_uncharge(&mem->res, PAGE_SIZE);
-        if (do_swap_account && (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT))
-                res_counter_uncharge(&mem->memsw, PAGE_SIZE);
+        if (!mem_cgroup_is_root(mem)) {
+                res_counter_uncharge(&mem->res, PAGE_SIZE, &soft_limit_excess);
+                if (do_swap_account &&
+                                (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT))
+                        res_counter_uncharge(&mem->memsw, PAGE_SIZE, NULL);
+        }
+        if (ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
+                mem_cgroup_swap_statistics(mem, true);
         mem_cgroup_charge_statistics(mem, pc, false);
 
         ClearPageCgroupUsed(pc);
@@ -1554,6 +1908,8 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
         mz = page_cgroup_zoneinfo(pc);
         unlock_page_cgroup(pc);
 
+        if (soft_limit_excess && mem_cgroup_soft_limit_check(mem))
+                mem_cgroup_update_tree(mem, page);
         /* at swapout, this memcg will be accessed to record to swap */
         if (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
                 css_put(&mem->css);
@@ -1629,7 +1985,9 @@ void mem_cgroup_uncharge_swap(swp_entry_t ent)
                  * We uncharge this because swap is freed.
                  * This memcg can be obsolete one. We avoid calling css_tryget
                  */
-                res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
+                if (!mem_cgroup_is_root(memcg))
+                        res_counter_uncharge(&memcg->memsw, PAGE_SIZE, NULL);
+                mem_cgroup_swap_statistics(memcg, false);
                 mem_cgroup_put(memcg);
         }
         rcu_read_unlock();
@@ -1658,7 +2016,8 @@ 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_KERNEL, &mem, false);
+                ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false,
+                                                page);
                 css_put(&mem->css);
         }
         *ptr = mem;
@@ -1798,8 +2157,9 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
                 if (!ret)
                         break;
 
-                progress = mem_cgroup_hierarchical_reclaim(memcg, GFP_KERNEL,
-                                                   false, true);
+                progress = mem_cgroup_hierarchical_reclaim(memcg, NULL,
+                                                GFP_KERNEL,
+                                                MEM_CGROUP_RECLAIM_SHRINK);
                 curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
                 /* Usage is reduced ? */
                 if (curusage >= oldusage)
@@ -1851,7 +2211,9 @@ static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
                 if (!ret)
                         break;
 
-                mem_cgroup_hierarchical_reclaim(memcg, GFP_KERNEL, true, true);
+                mem_cgroup_hierarchical_reclaim(memcg, NULL, GFP_KERNEL,
+                                                MEM_CGROUP_RECLAIM_NOSWAP |
+                                                MEM_CGROUP_RECLAIM_SHRINK);
                 curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
                 /* Usage is reduced ? */
                 if (curusage >= oldusage)
@@ -1862,6 +2224,97 @@ static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
         return ret;
 }
 
+unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
+                                                gfp_t gfp_mask, int nid,
+                                                int zid)
+{
+        unsigned long nr_reclaimed = 0;
+        struct mem_cgroup_per_zone *mz, *next_mz = NULL;
+        unsigned long reclaimed;
+        int loop = 0;
+        struct mem_cgroup_tree_per_zone *mctz;
+
+        if (order > 0)
+                return 0;
+
+        mctz = soft_limit_tree_node_zone(nid, zid);
+        /*
+         * This loop can run a while, specially if mem_cgroup's continuously
+         * keep exceeding their soft limit and putting the system under
+         * pressure
+         */
+        do {
+                if (next_mz)
+                        mz = next_mz;
+                else
+                        mz = mem_cgroup_largest_soft_limit_node(mctz);
+                if (!mz)
+                        break;
+
+                reclaimed = mem_cgroup_hierarchical_reclaim(mz->mem, zone,
+                                                gfp_mask,
+                                                MEM_CGROUP_RECLAIM_SOFT);
+                nr_reclaimed += reclaimed;
+                spin_lock(&mctz->lock);
+
+                /*
+                 * If we failed to reclaim anything from this memory cgroup
+                 * it is time to move on to the next cgroup
+                 */
+                next_mz = NULL;
+                if (!reclaimed) {
+                        do {
+                                /*
+                                 * Loop until we find yet another one.
+                                 *
+                                 * By the time we get the soft_limit lock
+                                 * again, someone might have aded the
+                                 * group back on the RB tree. Iterate to
+                                 * make sure we get a different mem.
+                                 * mem_cgroup_largest_soft_limit_node returns
+                                 * NULL if no other cgroup is present on
+                                 * the tree
+                                 */
+                                next_mz =
+                                __mem_cgroup_largest_soft_limit_node(mctz);
+                                if (next_mz == mz) {
+                                        css_put(&next_mz->mem->css);
+                                        next_mz = NULL;
+                                } else /* next_mz == NULL or other memcg */
+                                        break;
+                        } while (1);
+                }
+                mz->usage_in_excess =
+                        res_counter_soft_limit_excess(&mz->mem->res);
+                __mem_cgroup_remove_exceeded(mz->mem, mz, mctz);
+                /*
+                 * One school of thought says that we should not add
+                 * back the node to the tree if reclaim returns 0.
+                 * But our reclaim could return 0, simply because due
+                 * to priority we are exposing a smaller subset of
+                 * memory to reclaim from. Consider this as a longer
+                 * term TODO.
+                 */
+                if (mz->usage_in_excess)
+                        __mem_cgroup_insert_exceeded(mz->mem, mz, mctz);
+                spin_unlock(&mctz->lock);
+                css_put(&mz->mem->css);
+                loop++;
+                /*
+                 * Could not reclaim anything and there are no more
+                 * mem cgroups to try or we seem to be looping without
+                 * reclaiming anything.
+                 */
+                if (!nr_reclaimed &&
+                        (next_mz == NULL ||
+                        loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
+                        break;
+        } while (!nr_reclaimed);
+        if (next_mz)
+                css_put(&next_mz->mem->css);
+        return nr_reclaimed;
+}
+
 /*
  * This routine traverse page_cgroup in given list and drop them all.
  * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
@@ -2046,20 +2499,64 @@ static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
         return retval;
 }
 
+struct mem_cgroup_idx_data {
+        s64 val;
+        enum mem_cgroup_stat_index idx;
+};
+
+static int
+mem_cgroup_get_idx_stat(struct mem_cgroup *mem, void *data)
+{
+        struct mem_cgroup_idx_data *d = data;
+        d->val += mem_cgroup_read_stat(&mem->stat, d->idx);
+        return 0;
+}
+
+static void
+mem_cgroup_get_recursive_idx_stat(struct mem_cgroup *mem,
+                                enum mem_cgroup_stat_index idx, s64 *val)
+{
+        struct mem_cgroup_idx_data d;
+        d.idx = idx;
+        d.val = 0;
+        mem_cgroup_walk_tree(mem, &d, mem_cgroup_get_idx_stat);
+        *val = d.val;
+}
+
 static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
 {
         struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
-        u64 val = 0;
+        u64 idx_val, val;
         int type, name;
 
         type = MEMFILE_TYPE(cft->private);
         name = MEMFILE_ATTR(cft->private);
         switch (type) {
         case _MEM:
-                val = res_counter_read_u64(&mem->res, name);
+                if (name == RES_USAGE && mem_cgroup_is_root(mem)) {
+                        mem_cgroup_get_recursive_idx_stat(mem,
+                                MEM_CGROUP_STAT_CACHE, &idx_val);
+                        val = idx_val;
+                        mem_cgroup_get_recursive_idx_stat(mem,
+                                MEM_CGROUP_STAT_RSS, &idx_val);
+                        val += idx_val;
+                        val <<= PAGE_SHIFT;
+                } else
+                        val = res_counter_read_u64(&mem->res, name);
                 break;
         case _MEMSWAP:
-                val = res_counter_read_u64(&mem->memsw, name);
+                if (name == RES_USAGE && mem_cgroup_is_root(mem)) {
+                        mem_cgroup_get_recursive_idx_stat(mem,
+                                MEM_CGROUP_STAT_CACHE, &idx_val);
+                        val = idx_val;
+                        mem_cgroup_get_recursive_idx_stat(mem,
+                                MEM_CGROUP_STAT_RSS, &idx_val);
+                        val += idx_val;
+                        mem_cgroup_get_recursive_idx_stat(mem,
+                                MEM_CGROUP_STAT_SWAPOUT, &idx_val);
+                        val <<= PAGE_SHIFT;
+                } else
+                        val = res_counter_read_u64(&mem->memsw, name);
                 break;
         default:
                 BUG();
@@ -2083,6 +2580,10 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
         name = MEMFILE_ATTR(cft->private);
         switch (name) {
         case RES_LIMIT:
+                if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
+                        ret = -EINVAL;
+                        break;
+                }
                 /* This function does all necessary parse...reuse it */
                 ret = res_counter_memparse_write_strategy(buffer, &val);
                 if (ret)
@@ -2092,6 +2593,20 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
                 else
                         ret = mem_cgroup_resize_memsw_limit(memcg, val);
                 break;
+        case RES_SOFT_LIMIT:
+                ret = res_counter_memparse_write_strategy(buffer, &val);
+                if (ret)
+                        break;
+                /*
+                 * For memsw, soft limits are hard to implement in terms
+                 * of semantics, for now, we support soft limits for
+                 * control without swap
+                 */
+                if (type == _MEM)
+                        ret = res_counter_set_soft_limit(&memcg->res, val);
+                else
+                        ret = -EINVAL;
+                break;
         default:
                 ret = -EINVAL; /* should be BUG() ? */
                 break;
@@ -2149,6 +2664,7 @@ static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
                         res_counter_reset_failcnt(&mem->memsw);
                 break;
         }
+
         return 0;
 }
 
@@ -2160,6 +2676,7 @@ enum {
         MCS_MAPPED_FILE,
         MCS_PGPGIN,
         MCS_PGPGOUT,
+        MCS_SWAP,
         MCS_INACTIVE_ANON,
         MCS_ACTIVE_ANON,
         MCS_INACTIVE_FILE,
@@ -2181,6 +2698,7 @@ struct {
         {"mapped_file", "total_mapped_file"},
         {"pgpgin", "total_pgpgin"},
         {"pgpgout", "total_pgpgout"},
+        {"swap", "total_swap"},
         {"inactive_anon", "total_inactive_anon"},
         {"active_anon", "total_active_anon"},
         {"inactive_file", "total_inactive_file"},
@@ -2205,6 +2723,10 @@ static int mem_cgroup_get_local_stat(struct mem_cgroup *mem, void *data)
         s->stat[MCS_PGPGIN] += val;
         val = mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_PGPGOUT_COUNT);
         s->stat[MCS_PGPGOUT] += val;
+        if (do_swap_account) {
+                val = mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_SWAPOUT);
+                s->stat[MCS_SWAP] += val * PAGE_SIZE;
+        }
 
         /* per zone stat */
         val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_ANON);
@@ -2236,8 +2758,11 @@ static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
         memset(&mystat, 0, sizeof(mystat));
         mem_cgroup_get_local_stat(mem_cont, &mystat);
 
-        for (i = 0; i < NR_MCS_STAT; i++)
+        for (i = 0; i < NR_MCS_STAT; i++) {
+                if (i == MCS_SWAP && !do_swap_account)
+                        continue;
                 cb->fill(cb, memcg_stat_strings[i].local_name, mystat.stat[i]);
+        }
 
         /* Hierarchical information */
         {
@@ -2250,9 +2775,11 @@ static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
 
         memset(&mystat, 0, sizeof(mystat));
         mem_cgroup_get_total_stat(mem_cont, &mystat);
-        for (i = 0; i < NR_MCS_STAT; i++)
+        for (i = 0; i < NR_MCS_STAT; i++) {
+                if (i == MCS_SWAP && !do_swap_account)
+                        continue;
                 cb->fill(cb, memcg_stat_strings[i].total_name, mystat.stat[i]);
-
+        }
 
 #ifdef CONFIG_DEBUG_VM
         cb->fill(cb, "inactive_ratio", calc_inactive_ratio(mem_cont, NULL));
@@ -2345,6 +2872,12 @@ static struct cftype mem_cgroup_files[] = {
                 .read_u64 = mem_cgroup_read,
         },
         {
+                .name = "soft_limit_in_bytes",
+                .private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
+                .write_string = mem_cgroup_write,
+                .read_u64 = mem_cgroup_read,
+        },
+        {
                 .name = "failcnt",
                 .private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
                 .trigger = mem_cgroup_reset,
@@ -2438,6 +2971,9 @@ static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
                 mz = &pn->zoneinfo[zone];
                 for_each_lru(l)
                         INIT_LIST_HEAD(&mz->lists[l]);
+                mz->usage_in_excess = 0;
+                mz->on_tree = false;
+                mz->mem = mem;
         }
         return 0;
 }
@@ -2483,6 +3019,7 @@ static void __mem_cgroup_free(struct mem_cgroup *mem)
 {
         int node;
 
+        mem_cgroup_remove_from_trees(mem);
         free_css_id(&mem_cgroup_subsys, &mem->css);
 
         for_each_node_state(node, N_POSSIBLE)
@@ -2531,6 +3068,31 @@ static void __init enable_swap_cgroup(void)
 }
 #endif
 
+static int mem_cgroup_soft_limit_tree_init(void)
+{
+        struct mem_cgroup_tree_per_node *rtpn;
+        struct mem_cgroup_tree_per_zone *rtpz;
+        int tmp, node, zone;
+
+        for_each_node_state(node, N_POSSIBLE) {
+                tmp = node;
+                if (!node_state(node, N_NORMAL_MEMORY))
+                        tmp = -1;
+                rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
+                if (!rtpn)
+                        return 1;
+
+                soft_limit_tree.rb_tree_per_node[node] = rtpn;
+
+                for (zone = 0; zone < MAX_NR_ZONES; zone++) {
+                        rtpz = &rtpn->rb_tree_per_zone[zone];
+                        rtpz->rb_root = RB_ROOT;
+                        spin_lock_init(&rtpz->lock);
+                }
+        }
+        return 0;
+}
+
 static struct cgroup_subsys_state * __ref
 mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 {
@@ -2545,10 +3107,15 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
         for_each_node_state(node, N_POSSIBLE)
                 if (alloc_mem_cgroup_per_zone_info(mem, node))
                         goto free_out;
+
         /* root ? */
         if (cont->parent == NULL) {
                 enable_swap_cgroup();
                 parent = NULL;
+                root_mem_cgroup = mem;
+                if (mem_cgroup_soft_limit_tree_init())
+                        goto free_out;
+
         } else {
                 parent = mem_cgroup_from_cont(cont->parent);
                 mem->use_hierarchy = parent->use_hierarchy;
@@ -2577,6 +3144,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
         return &mem->css;
 free_out:
         __mem_cgroup_free(mem);
+        root_mem_cgroup = NULL;
         return ERR_PTR(error);
 }
 
@@ -2612,7 +3180,8 @@ static int mem_cgroup_populate(struct cgroup_subsys *ss,
 static void mem_cgroup_move_task(struct cgroup_subsys *ss,
                                 struct cgroup *cont,
                                 struct cgroup *old_cont,
-                                struct task_struct *p)
+                                struct task_struct *p,
+                                bool threadgroup)
 {
         mutex_lock(&memcg_tasklist);
         /*