From ad46fed9c9b596b6ece5728aad3722a9c4acc8cb Mon Sep 17 00:00:00 2001 From: Daisuke Nishimura Date: Tue, 15 Dec 2009 16:47:12 -0800 Subject: [PATCH] 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: /aa use_hierarchy == 0 <- hitting limit /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 Acked-by: Balbir Singh Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/memcontrol.c | 8 +++++++- mm/oom_kill.c | 2 +- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 63140151b618..5dc10374d769 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -758,7 +758,13 @@ 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 ea2147dabba6..9092b43f07fa 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -404,7 +404,7 @@ 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); -- 2.39.5