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Date: Thu, 22 Jan 2009 18:39:19 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: "linux-mm@...ck.org" <linux-mm@...ck.org>,
"menage@...gle.com" <menage@...gle.com>,
"lizf@...fujitsu.com" <lizf@...fujitsu.com>,
"balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>,
"nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [FIX][PATCH 5/7] memcg : fix OOM Killer behavior under memcg
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
This patch tries to fix OOM Killer problems caused by hierarchy.
Now, memcg itself has OOM KILL function (in oom_kill.c) and tries to
kill a task in memcg.
But, when hierarchy is used, it's broken and correct task cannot
be killed. For example, in following cgroup
/groupA/ hierarchy=1, limit=1G,
01 nolimit
02 nolimit
All tasks' memory usage under /groupA, /groupA/01, groupA/02 is limited to
groupA's 1Gbytes but OOM Killer just kills tasks in groupA.
This patch provides makes the bad process be selected from all tasks
under hierarchy. BTW, currently, oom_jiffies is updated against groupA
in above case. oom_jiffies of tree should be updated.
To see how oom_jiffies is used, please check mem_cgroup_oom_called()
callers.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
---
Documentation/cgroups/memcg_test.txt | 20 +++++++++++++++++++-
include/linux/memcontrol.h | 4 ++--
mm/memcontrol.c | 32 +++++++++++++++++++++++++++++---
3 files changed, 50 insertions(+), 6 deletions(-)
Index: mmotm-2.6.29-Jan16/mm/memcontrol.c
===================================================================
--- mmotm-2.6.29-Jan16.orig/mm/memcontrol.c
+++ mmotm-2.6.29-Jan16/mm/memcontrol.c
@@ -295,6 +295,9 @@ struct mem_cgroup *mem_cgroup_from_task(
static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
{
struct mem_cgroup *mem = NULL;
+
+ if (!mm)
+ return;
/*
* Because we have no locks, mm->owner's may be being moved to other
* cgroup. We use css_tryget() here even if this looks
@@ -483,13 +486,23 @@ void mem_cgroup_move_lists(struct page *
mem_cgroup_add_lru_list(page, to);
}
-int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
+int task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *mem)
{
int ret;
+ struct mem_cgroup *curr = NULL;
task_lock(task);
- ret = task->mm && mm_match_cgroup(task->mm, mem);
+ rcu_read_lock();
+ curr = try_get_mem_cgroup_from_mm(task->mm);
+ rcu_read_unlock();
task_unlock(task);
+ if (!curr)
+ return 0;
+ if (curr->use_hierarchy)
+ ret = css_is_ancestor(&curr->css, &mem->css);
+ else
+ ret = (curr == mem);
+ css_put(&curr->css);
return ret;
}
@@ -820,6 +833,19 @@ bool mem_cgroup_oom_called(struct task_s
rcu_read_unlock();
return ret;
}
+
+static int record_last_oom_cb(struct mem_cgroup *mem, void *data)
+{
+ mem->last_oom_jiffies = jiffies;
+ return 0;
+}
+
+static void record_last_oom(struct mem_cgroup *mem)
+{
+ mem_cgroup_walk_tree(mem, NULL, record_last_oom_cb);
+}
+
+
/*
* Unlike exported interface, "oom" parameter is added. if oom==true,
* oom-killer can be invoked.
@@ -902,7 +928,7 @@ static int __mem_cgroup_try_charge(struc
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;
+ record_last_oom(mem_over_limit);
}
goto nomem;
}
Index: mmotm-2.6.29-Jan16/Documentation/cgroups/memcg_test.txt
===================================================================
--- mmotm-2.6.29-Jan16.orig/Documentation/cgroups/memcg_test.txt
+++ mmotm-2.6.29-Jan16/Documentation/cgroups/memcg_test.txt
@@ -1,5 +1,5 @@
Memory Resource Controller(Memcg) Implementation Memo.
-Last Updated: 2009/1/19
+Last Updated: 2009/1/20
Base Kernel Version: based on 2.6.29-rc2.
Because VM is getting complex (one of reasons is memcg...), memcg's behavior
@@ -360,3 +360,21 @@ Under below explanation, we assume CONFI
# kill malloc task.
Of course, tmpfs v.s. swapoff test should be tested, too.
+
+ 9.8 OOM-Killer
+ Out-of-memory caused by memcg's limit will kill tasks under
+ the memcg. When hierarchy is used, a task under hierarchy
+ will be killed by the kernel.
+ In this case, panic_on_oom shouldn't be invoked and tasks
+ in other groups shouldn't be killed.
+
+ It's not difficult to cause OOM under memcg as following.
+ Case A) when you can swapoff
+ #swapoff -a
+ #echo 50M > /memory.limit_in_bytes
+ run 51M of malloc
+
+ Case B) when you use mem+swap limitation.
+ #echo 50M > memory.limit_in_bytes
+ #echo 50M > memory.memsw.limit_in_bytes
+ run 51M of malloc
Index: mmotm-2.6.29-Jan16/include/linux/memcontrol.h
===================================================================
--- mmotm-2.6.29-Jan16.orig/include/linux/memcontrol.h
+++ mmotm-2.6.29-Jan16/include/linux/memcontrol.h
@@ -66,7 +66,7 @@ extern unsigned long mem_cgroup_isolate_
struct mem_cgroup *mem_cont,
int active, int file);
extern void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask);
-int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem);
+int task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *mem);
extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
@@ -192,7 +192,7 @@ static inline int mm_match_cgroup(struct
}
static inline int task_in_mem_cgroup(struct task_struct *task,
- const struct mem_cgroup *mem)
+ struct mem_cgroup *mem)
{
return 1;
}
--
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