From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f169.google.com (mail-wi0-f169.google.com [209.85.212.169]) by kanga.kvack.org (Postfix) with ESMTP id 811546B0038 for ; Wed, 1 Apr 2015 11:19:24 -0400 (EDT) Received: by widdi4 with SMTP id di4so48877694wid.0 for ; Wed, 01 Apr 2015 08:19:24 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id u4si2293320wif.83.2015.04.01.08.19.22 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 01 Apr 2015 08:19:22 -0700 (PDT) Date: Wed, 1 Apr 2015 17:19:20 +0200 From: Michal Hocko Subject: Re: [patch 00/12] mm: page_alloc: improve OOM mechanism and policy Message-ID: <20150401151920.GB23824@dhcp22.suse.cz> References: <1427264236-17249-1-git-send-email-hannes@cmpxchg.org> <20150326195822.GB28129@dastard> <20150327150509.GA21119@cmpxchg.org> <20150330003240.GB28621@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150330003240.GB28621@dastard> Sender: owner-linux-mm@kvack.org List-ID: To: Dave Chinner Cc: Johannes Weiner , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , Tetsuo Handa , Huang Ying , Andrea Arcangeli , Theodore Ts'o On Mon 30-03-15 11:32:40, Dave Chinner wrote: > On Fri, Mar 27, 2015 at 11:05:09AM -0400, Johannes Weiner wrote: [...] > > GFP_NOFS sites are currently one of the sites that can deadlock inside > > the allocator, even though many of them seem to have fallback code. > > My reasoning here is that if you *have* an exit strategy for failing > > allocations that is smarter than hanging, we should probably use that. > > We already do that for allocations where we can handle failure in > GFP_NOFS conditions. It is, however, somewhat useless if we can't > tell the allocator to try really hard if we've already had a failure > and we are already in memory reclaim conditions (e.g. a shrinker > trying to clean dirty objects so they can be reclaimed). > > From that perspective, I think that this patch set aims force us > away from handling fallbacks ourselves because a) it makes GFP_NOFS > more likely to fail, and b) provides no mechanism to "try harder" > when we really need the allocation to succeed. You can ask for this "try harder" by __GFP_HIGH flag. Would that help in your fallback case? -- 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