From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f172.google.com (mail-pd0-f172.google.com [209.85.192.172]) by kanga.kvack.org (Postfix) with ESMTP id 4836E6B0031 for ; Mon, 23 Sep 2013 05:45:56 -0400 (EDT) Received: by mail-pd0-f172.google.com with SMTP id z10so3020554pdj.3 for ; Mon, 23 Sep 2013 02:45:55 -0700 (PDT) From: Ming Liu Subject: [PATCH] oom: avoid killing init if it assume the oom killed thread's mm Date: Mon, 23 Sep 2013 17:45:28 +0800 Message-ID: <1379929528-19179-1-git-send-email-ming.liu@windriver.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org, rientjes@google.com, mhocko@suse.cz, rusty@rustcorp.com.au, hannes@cmpxchg.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org 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. But 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 | 16 ++++++++-------- 1 files changed, 8 insertions(+), 8 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 314e9d2..7db4881 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -479,17 +479,17 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, task_unlock(victim); /* - * Kill all user processes sharing victim->mm in other thread groups, if - * any. They don't get access to memory reserves, though, to avoid - * depletion of all memory. This prevents mm->mmap_sem livelock when an - * oom killed thread cannot exit because it requires the semaphore and - * its contended by another thread trying to allocate memory itself. - * That thread will now get access to memory reserves since it has a - * pending fatal signal. + * Kill all user processes except init sharing victim->mm in other + * thread groups, if any. They don't get access to memory reserves, + * though, to avoid depletion of all memory. This prevents mm->mmap_sem + * livelock when an oom killed thread cannot exit because it requires + * the semaphore and its contended by another thread trying to allocate + * memory itself. That thread will now get access to memory reserves + * since it has a pending fatal signal. */ for_each_process(p) if (p->mm == mm && !same_thread_group(p, victim) && - !(p->flags & PF_KTHREAD)) { + !(p->flags & PF_KTHREAD) && !is_global_init(p)) { if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) continue; -- 1.7.0.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org