From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f54.google.com (mail-la0-f54.google.com [209.85.215.54]) by kanga.kvack.org (Postfix) with ESMTP id B21126B0256 for ; Mon, 31 Aug 2015 11:24:54 -0400 (EDT) Received: by labnh1 with SMTP id nh1so48516893lab.3 for ; Mon, 31 Aug 2015 08:24:54 -0700 (PDT) Received: from relay.parallels.com (relay.parallels.com. [195.214.232.42]) by mx.google.com with ESMTPS id nq2si13407409lbc.42.2015.08.31.08.24.52 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 31 Aug 2015 08:24:53 -0700 (PDT) Date: Mon, 31 Aug 2015 18:24:36 +0300 From: Vladimir Davydov 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> Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: Michal Hocko , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org 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, 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