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: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
index fcb9884df618..731af71cddc9 100644
--- a/include/linux/res_counter.h
+++ b/include/linux/res_counter.h
@@ -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)
 {