Commit f64c3f54 authored by Balbir Singh's avatar Balbir Singh Committed by Linus Torvalds
Browse files

memory controller: soft limit organize cgroups 



Organize cgroups over soft limit in a RB-Tree

Introduce an RB-Tree for storing memory cgroups that are over their soft
limit.  The overall goal is to

1. Add a memory cgroup to the RB-Tree when the soft limit is exceeded.
   We are careful about updates, updates take place only after a particular
   time interval has passed
2. We remove the node from the RB-Tree when the usage goes below the soft
   limit

The next set of patches will exploit the RB-Tree to get the group that is
over its soft limit by the largest amount and reclaim from it, when we
face memory contention.

[hugh.dickins@tiscali.co.uk: CONFIG_CGROUP_MEM_RES_CTLR=y CONFIG_PREEMPT=y fails to boot]
Signed-off-by: default avatarBalbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: default avatarHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 296c81d8

include/linux/res_counter.h

+4 −2
Original line number Diff line number Diff line
@@ -114,7 +114,8 @@ void res_counter_init(struct res_counter *counter, struct res_counter *parent); 
int __must_check res_counter_charge_locked(struct res_counter *counter,

		unsigned long val);

int __must_check res_counter_charge(struct res_counter *counter,

		unsigned long val, struct res_counter **limit_fail_at);

		unsigned long val, struct res_counter **limit_fail_at,

		struct res_counter **soft_limit_at);



/*

 * uncharge - tell that some portion of the resource is released
@@ -127,7 +128,8 @@ int __must_check res_counter_charge(struct res_counter *counter, 
 */



void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);

void res_counter_uncharge(struct res_counter *counter, unsigned long val);

void res_counter_uncharge(struct res_counter *counter, unsigned long val,

				bool *was_soft_limit_excess);



static inline bool res_counter_limit_check_locked(struct res_counter *cnt)

{

kernel/res_counter.c

+16 −2
Original line number Diff line number Diff line
@@ -37,17 +37,27 @@ int res_counter_charge_locked(struct res_counter *counter, unsigned long val) 
}



int res_counter_charge(struct res_counter *counter, unsigned long val,

			struct res_counter **limit_fail_at)

			struct res_counter **limit_fail_at,

			struct res_counter **soft_limit_fail_at)

{

	int ret;

	unsigned long flags;

	struct res_counter *c, *u;



	*limit_fail_at = NULL;

	if (soft_limit_fail_at)

		*soft_limit_fail_at = NULL;

	local_irq_save(flags);

	for (c = counter; c != NULL; c = c->parent) {

		spin_lock(&c->lock);

		ret = res_counter_charge_locked(c, val);

		/*

		 * With soft limits, we return the highest ancestor

		 * that exceeds its soft limit

		 */

		if (soft_limit_fail_at &&

			!res_counter_soft_limit_check_locked(c))

			*soft_limit_fail_at = c;

		spin_unlock(&c->lock);

		if (ret < 0) {

			*limit_fail_at = c;
@@ -75,7 +85,8 @@ void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val) 
	counter->usage -= val;

}



void res_counter_uncharge(struct res_counter *counter, unsigned long val)

void res_counter_uncharge(struct res_counter *counter, unsigned long val,

				bool *was_soft_limit_excess)

{

	unsigned long flags;

	struct res_counter *c;
@@ -83,6 +94,9 @@ void res_counter_uncharge(struct res_counter *counter, unsigned long val) 
	local_irq_save(flags);

	for (c = counter; c != NULL; c = c->parent) {

		spin_lock(&c->lock);

		if (was_soft_limit_excess)

			*was_soft_limit_excess =

				!res_counter_soft_limit_check_locked(c);

		res_counter_uncharge_locked(c, val);

		spin_unlock(&c->lock);

	}

mm/memcontrol.c

+257 −43
Original line number Diff line number Diff line
@@ -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>
@@ -54,6 +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.
@@ -67,6 +69,7 @@ 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_NSTATS,

};
@@ -79,6 +82,20 @@ 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.

 */
@@ -118,6 +135,10 @@ 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;

};

/* Macro for accessing counter */

#define MEM_CGROUP_ZSTAT(mz, idx)	((mz)->count[(idx)])
@@ -130,6 +151,26 @@ struct mem_cgroup_lru_info { 
	struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES];

};



/*

 * 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
@@ -215,6 +256,150 @@ 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);

	spin_lock(&mctz->lock);

	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;

	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);

	rb_erase(&mz->tree_node, &mctz->rb_root);

	mz->on_tree = false;

	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 void mem_cgroup_charge_statistics(struct mem_cgroup *mem,

					 struct page_cgroup *pc,

					 bool charge)
@@ -236,28 +421,10 @@ 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)

{
@@ -972,11 +1139,11 @@ 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! */
@@ -1006,16 +1173,17 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, 
		int ret;

		bool noswap = false;



		ret = res_counter_charge(&mem->res, PAGE_SIZE, &fail_res);

		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);

			res_counter_uncharge(&mem->res, PAGE_SIZE, NULL);

			noswap = true;

			mem_over_limit = mem_cgroup_from_res_counter(fail_res,

									memsw);
@@ -1053,13 +1221,23 @@ 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);

	}

	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
@@ -1126,9 +1304,9 @@ 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);

		res_counter_uncharge(&mem->res, PAGE_SIZE, NULL);

		if (do_swap_account)

			res_counter_uncharge(&mem->memsw, PAGE_SIZE);

			res_counter_uncharge(&mem->memsw, PAGE_SIZE, NULL);

		css_put(&mem->css);

		return;

	}
@@ -1205,7 +1383,7 @@ static int mem_cgroup_move_account(struct page_cgroup *pc, 
	if (pc->mem_cgroup != from)

		goto out;



	res_counter_uncharge(&from->res, PAGE_SIZE);

	res_counter_uncharge(&from->res, PAGE_SIZE, NULL);

	mem_cgroup_charge_statistics(from, pc, false);



	page = pc->page;
@@ -1225,7 +1403,7 @@ static int mem_cgroup_move_account(struct page_cgroup *pc, 
	}



	if (do_swap_account)

		res_counter_uncharge(&from->memsw, PAGE_SIZE);

		res_counter_uncharge(&from->memsw, PAGE_SIZE, NULL);

	css_put(&from->css);



	css_get(&to->css);
@@ -1265,7 +1443,7 @@ 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;
@@ -1295,9 +1473,9 @@ uncharge: 
	/* drop extra refcnt by try_charge() */

	css_put(&parent->css);

	/* uncharge if move fails */

	res_counter_uncharge(&parent->res, PAGE_SIZE);

	res_counter_uncharge(&parent->res, PAGE_SIZE, NULL);

	if (do_swap_account)

		res_counter_uncharge(&parent->memsw, PAGE_SIZE);

		res_counter_uncharge(&parent->memsw, PAGE_SIZE, NULL);

	return ret;

}
@@ -1322,7 +1500,7 @@ 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;
@@ -1441,14 +1619,14 @@ 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
@@ -1486,7 +1664,7 @@ __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);

			res_counter_uncharge(&memcg->memsw, PAGE_SIZE, NULL);

			mem_cgroup_put(memcg);

		}

		rcu_read_unlock();
@@ -1511,9 +1689,9 @@ void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem) 
		return;

	if (!mem)

		return;

	res_counter_uncharge(&mem->res, PAGE_SIZE);

	res_counter_uncharge(&mem->res, PAGE_SIZE, NULL);

	if (do_swap_account)

		res_counter_uncharge(&mem->memsw, PAGE_SIZE);

		res_counter_uncharge(&mem->memsw, PAGE_SIZE, NULL);

	css_put(&mem->css);

}
@@ -1527,6 +1705,7 @@ __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;
@@ -1565,9 +1744,9 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) 
		break;

	}



	res_counter_uncharge(&mem->res, PAGE_SIZE);

	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);

		res_counter_uncharge(&mem->memsw, PAGE_SIZE, NULL);

	mem_cgroup_charge_statistics(mem, pc, false);



	ClearPageCgroupUsed(pc);
@@ -1581,6 +1760,8 @@ __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);
@@ -1656,7 +1837,7 @@ 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);

		res_counter_uncharge(&memcg->memsw, PAGE_SIZE, NULL);

		mem_cgroup_put(memcg);

	}

	rcu_read_unlock();
@@ -1685,7 +1866,8 @@ 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;
@@ -2194,6 +2376,7 @@ static int mem_cgroup_reset(struct cgroup *cont, unsigned int event) 
			res_counter_reset_failcnt(&mem->memsw);

		break;

	}



	return 0;

}
@@ -2489,6 +2672,7 @@ 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;

	}

	return 0;

}
@@ -2534,6 +2718,7 @@ 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)
@@ -2582,6 +2767,31 @@ 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)

{
@@ -2596,11 +2806,15 @@ 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;

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