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authorDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>2010-01-05 12:26:33 +0900
committerGreg Kroah-Hartman <gregkh@suse.de>2010-01-06 14:26:49 -0800
commitae3559fa2fe48ab923b52885bba2dca0355428f0 (patch)
tree6421e0229dac6f291e41d6bd86047de92a8e6a38
parentf1850a5783908f6528c305e321119e7aa6641151 (diff)
downloadlinux-linaro-stable-ae3559fa2fe48ab923b52885bba2dca0355428f0.tar.gz
memcg: avoid oom-killing innocent task in case of use_hierarchy
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>
-rw-r--r--mm/memcontrol.c8
-rw-r--r--mm/oom_kill.c2
2 files changed, 8 insertions, 2 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index fd4529d86de5..566925e7cdbd 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -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);
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index a7b2460e922b..ed452e9485d4 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -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);