From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752426AbdLGJ6i (ORCPT ); Thu, 7 Dec 2017 04:58:38 -0500 Received: from mx2.suse.de ([195.135.220.15]:42196 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751059AbdLGJ6h (ORCPT ); Thu, 7 Dec 2017 04:58:37 -0500 Date: Thu, 7 Dec 2017 10:58:35 +0100 From: Michal Hocko To: Sergey Senozhatsky Cc: Suren Baghdasaryan , akpm@linux-foundation.org, hannes@cmpxchg.org, hillf.zj@alibaba-inc.com, minchan@kernel.org, mgorman@techsingularity.net, ying.huang@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, timmurray@google.com, tkjos@google.com Subject: Re: [PATCH] mm: terminate shrink_slab loop if signal is pending Message-ID: <20171207095835.GE20234@dhcp22.suse.cz> References: <20171206192026.25133-1-surenb@google.com> <20171207095223.GB574@jagdpanzerIV> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171207095223.GB574@jagdpanzerIV> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 07-12-17 18:52:23, Sergey Senozhatsky wrote: > On (12/06/17 11:20), Suren Baghdasaryan wrote: > > Slab shrinkers can be quite time consuming and when signal > > is pending they can delay handling of the signal. If fatal > > signal is pending there is no point in shrinking that process > > since it will be killed anyway. This change checks for pending > > fatal signals inside shrink_slab loop and if one is detected > > terminates this loop early. > > > > Signed-off-by: Suren Baghdasaryan > > --- > > mm/vmscan.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index c02c850ea349..69296528ff33 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -486,6 +486,13 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, > > .memcg = memcg, > > }; > > > > + /* > > + * We are about to die and free our memory. > > + * Stop shrinking which might delay signal handling. > > + */ > > + if (unlikely(fatal_signal_pending(current)) > > - if (unlikely(fatal_signal_pending(current)) > + if (unlikely(fatal_signal_pending(current))) Heh, well, spotted. This begs a question how this has been tested, if at all? -- Michal Hocko SUSE Labs