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authorDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>2009-12-15 16:47:12 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-16 07:20:07 -0800
commitd31f56dbf8bafaacb0c617f9a6f137498d5c7aed (patch)
tree88d095c2208d27362e58ff7431407040ead9d848 /mm/memcontrol.c
parent57f9fd7d25ac9a0d7e3a4ced580e780ab4524e3b (diff)
downloadlinux-d31f56dbf8bafaacb0c617f9a6f137498d5c7aed.tar.bz2
memcg: avoid oom-killing innocent task in case of use_hierarchy
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>/aa use_hierarchy == 0 <- hitting limit <some path>/aa/00 use_hierarchy == 1 <- the task belongs to This leads to killing an innocent task in aa/00. 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: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
-rw-r--r--mm/memcontrol.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6273984f2e34..a294b7576070 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -760,7 +760,13 @@ 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);
@@ -1009,7 +1015,7 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
static char memcg_name[PATH_MAX];
int ret;
- if (!memcg)
+ if (!memcg || !p)
return;