Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753596AbbFRXAb (ORCPT ); Thu, 18 Jun 2015 19:00:31 -0400 Received: from mail-ig0-f178.google.com ([209.85.213.178]:33658 "EHLO mail-ig0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751341AbbFRXAM (ORCPT ); Thu, 18 Jun 2015 19:00:12 -0400 Date: Thu, 18 Jun 2015 16:00:09 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Andrew Morton cc: Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [patch 3/3] mm, oom: do not panic for oom kills triggered from sysrq In-Reply-To: Message-ID: References: User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2114 Lines: 59 Sysrq+f is used to kill a process either for debug or when the VM is otherwise unresponsive. It is not intended to trigger a panic when no process may be killed. Avoid panicking the system for sysrq+f when no processes are killed. Suggested-by: Michal Hocko Signed-off-by: David Rientjes --- Documentation/sysrq.txt | 3 ++- mm/oom_kill.c | 7 +++++-- 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/Documentation/sysrq.txt b/Documentation/sysrq.txt --- a/Documentation/sysrq.txt +++ b/Documentation/sysrq.txt @@ -75,7 +75,8 @@ On all - write a character to /proc/sysrq-trigger. e.g.: 'e' - Send a SIGTERM to all processes, except for init. -'f' - Will call oom_kill to kill a memory hog process. +'f' - Will call the oom killer to kill a memory hog process, but do not + panic if nothing can be killed. 'g' - Used by kgdb (kernel debugger) diff --git a/mm/oom_kill.c b/mm/oom_kill.c --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -607,6 +607,9 @@ void check_panic_on_oom(struct oom_control *oc, enum oom_constraint constraint, if (constraint != CONSTRAINT_NONE) return; } + /* Do not panic for oom kills triggered by sysrq */ + if (oc->order == -1) + return; dump_header(oc, NULL, memcg); panic("Out of memory: %s panic_on_oom is enabled\n", sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide"); @@ -686,11 +689,11 @@ bool out_of_memory(struct oom_control *oc) p = select_bad_process(oc, &points, totalpages); /* Found nothing?!?! Either we hang forever, or we panic. */ - if (!p) { + if (!p && oc->order != -1) { dump_header(oc, NULL, NULL); panic("Out of memory and no killable processes...\n"); } - if (p != (void *)-1UL) { + if (p && p != (void *)-1UL) { oom_kill_process(oc, p, points, totalpages, NULL, "Out of memory"); killed = 1; -- 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/