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memcg: avoid oom-killing innocent task in case of use_hierarchy

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commit d31f56dbf8bafaacb0c617f9a6f137498d5c7aed upstream

task_in_mem_cgroup(), which is called by select_bad_process() to check whether
a task can be a candidate for being oom-killed from memcg's limit, checks
"curr->use_hierarchy"("curr" is the mem_cgroup the task belongs to).

But this check return true(it's false positive) when:

	<some path>/00		use_hierarchy == 0	<- hitting limit
	  <some path>/00/aa	use_hierarchy == 1	<- "curr"

This leads to killing an innocent task in 00/aa. This patch is a fix for this
bug. And this patch also fixes the arg for mem_cgroup_print_oom_info(). We
should print information of mem_cgroup which the task being killed, not current,
belongs to.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Daisuke Nishimura
2010-01-05 12:26:33 +09:00
committed by Greg Kroah-Hartman
parent f1850a5783
commit ae3559fa2f
2 changed files with 8 additions and 2 deletions
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8
mm/memcontrol.c
View File

@@ -496,7 +496,13 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
task_unlock(task);
if (!curr)
return 0;
if (curr->use_hierarchy)
/*
* We should check use_hierarchy of "mem" not "curr". Because checking
* use_hierarchy of "curr" here make this function true if hierarchy is
* enabled in "curr" and "curr" is a child of "mem" in *cgroup*
* hierarchy(even if use_hierarchy is disabled in "mem").
*/
if (mem->use_hierarchy)
ret = css_is_ancestor(&curr->css, &mem->css);
else
ret = (curr == mem);

2
mm/oom_kill.c
View File

@@ -400,7 +400,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
cpuset_print_task_mems_allowed(current);
task_unlock(current);
dump_stack();
mem_cgroup_print_oom_info(mem, current);
mem_cgroup_print_oom_info(mem, p);
show_mem();
if (sysctl_oom_dump_tasks)
dump_tasks(mem);