From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f50.google.com (mail-pa0-f50.google.com [209.85.220.50]) by kanga.kvack.org (Postfix) with ESMTP id 785A06B006E for ; Wed, 6 May 2015 08:24:44 -0400 (EDT) Received: by pabsx10 with SMTP id sx10so8003063pab.3 for ; Wed, 06 May 2015 05:24:44 -0700 (PDT) Received: from mx2.parallels.com (mx2.parallels.com. [199.115.105.18]) by mx.google.com with ESMTPS id yv1si28905181pac.33.2015.05.06.05.24.43 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 May 2015 05:24:43 -0700 (PDT) Date: Wed, 6 May 2015 15:24:31 +0300 From: Vladimir Davydov Subject: Re: [PATCH 1/2] gfp: add __GFP_NOACCOUNT Message-ID: <20150506122431.GA29387@esperanza> References: <20150506115941.GH14550@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20150506115941.GH14550@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , Johannes Weiner , Tejun Heo , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Greg Thelen , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org On Wed, May 06, 2015 at 01:59:41PM +0200, Michal Hocko wrote: > On Tue 05-05-15 12:45:42, Vladimir Davydov wrote: > > Not all kmem allocations should be accounted to memcg. The following > > patch gives an example when accounting of a certain type of allocations > > to memcg can effectively result in a memory leak. > > > This patch adds the __GFP_NOACCOUNT flag which if passed to kmalloc > > and friends will force the allocation to go through the root > > cgroup. It will be used by the next patch. > > The name of the flag is way too generic. It is not clear that the > accounting is KMEMCG related. __GFP_NO_KMEMCG sounds better? > > I was going to suggest doing per-cache rather than gfp flag and that > would actually work just fine for the kmemleak as it uses its own cache > already. But the ida_simple_get would be trickier because it doesn't use > any special cache and more over only one user seem to have a problem so > this doesn't sound like a good fit. I don't think making this flag per-cache is an option either, but for another reason - it would not be possible to merge such a kmem cache with caches without this flag set. As a result, total memory pressure would increase, even for setups without kmem-active memory cgroups, which does not sound acceptable to me. > > So I do not object to opt-out for kmemcg accounting but I really think > the name should be changed. I named it __GFP_NOACCOUNT to match with __GFP_NOTRACK, which is a very specific flag too (kmemcheck), nevertheless it has a rather generic name. Anyways, what else apart from memcg can account kmem so that we have to mention KMEMCG in the flag name explicitly? 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