From 0b7f569e45bb6be142d87017030669a6a7d327a1 Mon Sep 17 00:00:00 2001
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Date: Thu, 2 Apr 2009 16:57:38 -0700
Subject: [PATCH] memcg: fix OOM killer under memcg
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.
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: const fix]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
Documentation/cgroups/memcg_test.txt | 20 ++++++++++++++++++-
include/linux/cgroup.h | 2 +-
kernel/cgroup.c | 2 +-
mm/memcontrol.c | 30 ++++++++++++++++++++++++++--
4 files changed, 49 insertions(+), 5 deletions(-)
diff --git a/Documentation/cgroups/memcg_test.txt b/Documentation/cgroups/memcg_test.txt
index 523a9c16c400..8a11caf417a0 100644
--- a/Documentation/cgroups/memcg_test.txt
+++ b/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 CONFIG_MEM_RES_CTRL_SWAP=y.
# 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
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index b2816fba5306..43763bd772b9 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -503,7 +503,7 @@ struct cgroup_subsys_state *css_get_next(struct cgroup_subsys *ss, int id,
/* Returns true if root is ancestor of cg */
bool css_is_ancestor(struct cgroup_subsys_state *cg,
- struct cgroup_subsys_state *root);
+ const struct cgroup_subsys_state *root);
/* Get id and depth of css */
unsigned short css_id(struct cgroup_subsys_state *css);
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index f2a3f5c9936c..382109b5baeb 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3405,7 +3405,7 @@ unsigned short css_depth(struct cgroup_subsys_state *css)
}
bool css_is_ancestor(struct cgroup_subsys_state *child,
- struct cgroup_subsys_state *root)
+ const struct cgroup_subsys_state *root)
{
struct css_id *child_id = rcu_dereference(child->id);
struct css_id *root_id = rcu_dereference(root->id);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6f6a575e77ad..025f8abfae2d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -295,6 +295,9 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
{
struct mem_cgroup *mem = NULL;
+
+ if (!mm)
+ return 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
@@ -486,10 +489,20 @@ void mem_cgroup_move_lists(struct page *page,
int task_in_mem_cgroup(struct task_struct *task, const 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_struct *task)
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(struct mm_struct *mm,
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;
}
--
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