From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757302AbbIUQSf (ORCPT ); Mon, 21 Sep 2015 12:18:35 -0400 Received: from mail-wi0-f170.google.com ([209.85.212.170]:38794 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757283AbbIUQSe (ORCPT ); Mon, 21 Sep 2015 12:18:34 -0400 Date: Mon, 21 Sep 2015 18:18:31 +0200 From: Michal Hocko To: Yaowei Bai Cc: akpm@linux-foundation.org, mgorman@suse.de, rientjes@google.com, hannes@cmpxchg.org, vdavydov@parallels.com, oleg@redhat.com, vbabka@suse.cz, iamjoonsoo.kim@lge.com, zhangyanfei@cn.fujitsu.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] mm/oom_kill: introduce is_sysrq_oom helper Message-ID: <20150921161831.GF19811@dhcp22.suse.cz> References: <1442404800-4051-1-git-send-email-bywxiaobai@163.com> <1442404800-4051-2-git-send-email-bywxiaobai@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1442404800-4051-2-git-send-email-bywxiaobai@163.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 16-09-15 19:59:59, Yaowei Bai wrote: > Introduce is_sysrq_oom helper function indicating oom kill triggered > by sysrq to improve readability. > > No functional changes. I was complaining about a subtle semantic of order -1 when it was introduced. This is easier to follow. At least for me. > Signed-off-by: Yaowei Bai Acked-by: Michal Hocko > --- > mm/oom_kill.c | 17 +++++++++++++---- > 1 file changed, 13 insertions(+), 4 deletions(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 1ecc0bc..7b6228e 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -118,6 +118,15 @@ found: > return t; > } > > +/* > + * order == -1 means the oom kill is required by sysrq, otherwise only > + * for display purposes. > + */ > +static inline bool is_sysrq_oom(struct oom_control *oc) > +{ > + return oc->order == -1; > +} > + > /* return true if the task is not adequate as candidate victim task. */ > static bool oom_unkillable_task(struct task_struct *p, > struct mem_cgroup *memcg, const nodemask_t *nodemask) > @@ -265,7 +274,7 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc, > * Don't allow any other task to have access to the reserves. > */ > if (test_tsk_thread_flag(task, TIF_MEMDIE)) { > - if (oc->order != -1) > + if (!is_sysrq_oom(oc)) > return OOM_SCAN_ABORT; > } > if (!task->mm) > @@ -278,7 +287,7 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc, > if (oom_task_origin(task)) > return OOM_SCAN_SELECT; > > - if (task_will_free_mem(task) && oc->order != -1) > + if (task_will_free_mem(task) && !is_sysrq_oom(oc)) > return OOM_SCAN_ABORT; > > return OOM_SCAN_OK; > @@ -608,7 +617,7 @@ void check_panic_on_oom(struct oom_control *oc, enum oom_constraint constraint, > return; > } > /* Do not panic for oom kills triggered by sysrq */ > - if (oc->order == -1) > + if (is_sysrq_oom(oc)) > return; > dump_header(oc, NULL, memcg); > panic("Out of memory: %s panic_on_oom is enabled\n", > @@ -688,7 +697,7 @@ 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 && oc->order != -1) { > + if (!p && !is_sysrq_oom(oc)) { > dump_header(oc, NULL, NULL); > panic("Out of memory and no killable processes...\n"); > } > -- > 1.9.1 > > > -- > 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 -- Michal Hocko SUSE Labs