From ae3559fa2fe48ab923b52885bba2dca0355428f0 Mon Sep 17 00:00:00 2001 From: Daisuke Nishimura Date: Tue, 5 Jan 2010 12:26:33 +0900 Subject: 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: /00 use_hierarchy == 0 <- hitting limit /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 Acked-by: KAMEZAWA Hiroyuki Reviewed-by: Balbir Singh 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 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); -- cgit v1.2.3