Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753768AbbHaPYy (ORCPT ); Mon, 31 Aug 2015 11:24:54 -0400 Received: from relay.parallels.com ([195.214.232.42]:37447 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753106AbbHaPYx (ORCPT ); Mon, 31 Aug 2015 11:24:53 -0400 Date: Mon, 31 Aug 2015 18:24:36 +0300 From: Vladimir Davydov To: Tejun Heo CC: Michal Hocko , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , , Subject: Re: [PATCH 0/2] Fix memcg/memory.high in case kmem accounting is enabled Message-ID: <20150831152436.GA15420@esperanza> References: <20150831132414.GG29723@dhcp22.suse.cz> <20150831142049.GV9610@esperanza> <20150831144604.GD2271@mtj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20150831144604.GD2271@mtj.duckdns.org> X-ClientProxiedBy: US-EXCH2.sw.swsoft.com (10.255.249.46) To MSK-EXCH1.sw.swsoft.com (10.67.48.55) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1299 Lines: 31 On Mon, Aug 31, 2015 at 10:46:04AM -0400, Tejun Heo wrote: > Hello, Vladimir. > > On Mon, Aug 31, 2015 at 05:20:49PM +0300, Vladimir Davydov wrote: > ... > > That being said, this is the fix at the right layer. > > While this *might* be a necessary workaround for the hard limit case > right now, this is by no means the fix at the right layer. The > expectation is that mm keeps a reasonable amount of memory available > for allocations which can't block. These allocations may fail from > time to time depending on luck and under extreme memory pressure but > the caller should be able to depend on it as a speculative allocation > mechanism which doesn't fail willy-nilly. > > Hardlimit breaking GFP_NOWAIT behavior is a bug on memcg side, not > slab or slub. I never denied that there is GFP_NOWAIT/GFP_NOFS problem in memcg. I even proposed ways to cope with it in one of the previous e-mails. Nevertheless, we just can't allow slab/slub internals call memcg_charge whenever they want as I pointed out in a parallel thread. Thanks, Vladimir -- 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/