From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f197.google.com (mail-wj0-f197.google.com [209.85.210.197]) by kanga.kvack.org (Postfix) with ESMTP id 4FEC228025E for ; Thu, 22 Dec 2016 14:27:57 -0500 (EST) Received: by mail-wj0-f197.google.com with SMTP id xr1so67236498wjb.7 for ; Thu, 22 Dec 2016 11:27:57 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id cv5si32875112wjc.141.2016.12.22.11.27.56 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 22 Dec 2016 11:27:56 -0800 (PST) Date: Thu, 22 Dec 2016 20:27:53 +0100 From: Michal Hocko Subject: Re: [PATCH] mm, oom_reaper: Update rationale comment for holding oom_lock. Message-ID: <20161222192752.GC19898@dhcp22.suse.cz> References: <1482411450-8097-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1482411450-8097-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: linux-mm@kvack.org, akpm@linux-foundation.org On Thu 22-12-16 21:57:30, Tetsuo Handa wrote: > Since commit 862e3073b3eed13f > ("mm, oom: get rid of signal_struct::oom_victims") > changed to wait until MMF_OOM_SKIP is set rather than wait while > TIF_MEMDIE is set, rationale comment for commit e2fe14564d3316d1 > ("oom_reaper: close race with exiting task") needs to be updated. > > Signed-off-by: Tetsuo Handa > --- > mm/oom_kill.c | 15 +++------------ > 1 file changed, 3 insertions(+), 12 deletions(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index ec9f11d..6fd076b 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -470,18 +470,9 @@ static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) > bool ret = true; > > /* > - * We have to make sure to not race with the victim exit path > - * and cause premature new oom victim selection: > - * __oom_reap_task_mm exit_mm > - * mmget_not_zero > - * mmput > - * atomic_dec_and_test > - * exit_oom_victim > - * [...] > - * out_of_memory > - * select_bad_process > - * # no TIF_MEMDIE task selects new victim > - * unmap_page_range # frees some memory > + * Make sure that other threads waiting for oom_lock at > + * __alloc_pages_may_oom() are given a chance to call > + * get_page_from_freelist() after MMF_OOM_SKIP is set. > */ > mutex_lock(&oom_lock); I am not sure the comment clarifies things. I would either remove the comment completely or write something like the below /* * Exclude any oom actions while we are reaping the oom * victim. This will save us from pointless searching of the * new oom victim. */ -- Michal Hocko SUSE Labs -- 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