Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755919Ab3IZIJ4 (ORCPT ); Thu, 26 Sep 2013 04:09:56 -0400 Received: from mail1.windriver.com ([147.11.146.13]:41655 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755771Ab3IZIJu (ORCPT ); Thu, 26 Sep 2013 04:09:50 -0400 From: Ming Liu To: , , , , CC: , Subject: [PATCH V1] oom: avoid selecting threads sharing mm with init Date: Thu, 26 Sep 2013 16:09:17 +0800 Message-ID: <1380182957-3231-1-git-send-email-ming.liu@windriver.com> X-Mailer: git-send-email 1.7.0.4 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1809 Lines: 51 It won't help free memory for killing tasks sharing mm with init, we should skip them in oom_unkillable_task(), or we may risk init process getting killed because after selecting a task to kill, the oom killer iterates all processes and kills all other user threads that share the same mm_struct in different thread groups. In some extreme cases, the selected task happens to be a vfork child of init process sharing the same mm_struct with it, which causes kernel panic on init getting killed. This panic is observed in a busybox shell that busybox itself is init, with a kthread keeps consuming memories. Signed-off-by: Ming Liu --- mm/oom_kill.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 314e9d2..7e50a95 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -113,11 +113,22 @@ struct task_struct *find_lock_task_mm(struct task_struct *p) static bool oom_unkillable_task(struct task_struct *p, const struct mem_cgroup *memcg, const nodemask_t *nodemask) { + struct task_struct *init_tsk; + if (is_global_init(p)) return true; if (p->flags & PF_KTHREAD) return true; + /* It won't help free memory if p is sharing mm with init */ + rcu_read_lock(); + init_tsk = find_task_by_pid_ns(1, &init_pid_ns); + if(p->mm == init_tsk->mm) { + rcu_read_unlock(); + return true; + } + rcu_read_unlock(); + /* When mem_cgroup_out_of_memory() and p is not member of the group */ if (memcg && !task_in_mem_cgroup(p, memcg)) return true; -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/