Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757343Ab2FZNoX (ORCPT ); Tue, 26 Jun 2012 09:44:23 -0400 Received: from mail-qa0-f49.google.com ([209.85.216.49]:60728 "EHLO mail-qa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757123Ab2FZNoV (ORCPT ); Tue, 26 Jun 2012 09:44:21 -0400 Date: Tue, 26 Jun 2012 15:44:15 +0200 From: Frederic Weisbecker To: Glauber Costa Cc: Tejun Heo , Frederic Weisbecker , cgroups@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org, David Rientjes , Pekka Enberg , Michal Hocko , Johannes Weiner , Christoph Lameter , devel@openvz.org, kamezawa.hiroyu@jp.fujitsu.com, Pekka Enberg , Suleiman Souhlal Subject: Re: [PATCH 11/11] protect architectures where THREAD_SIZE >= PAGE_SIZE against fork bombs Message-ID: <20120626134412.GB11519@somewhere.redhat.com> References: <1340633728-12785-1-git-send-email-glommer@parallels.com> <1340633728-12785-12-git-send-email-glommer@parallels.com> <4FE89807.50708@redhat.com> <20120625183818.GH3869@google.com> <4FE9AF88.5070803@parallels.com> <20120626133838.GA11519@somewhere.redhat.com> <4FE9BB25.60905@parallels.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FE9BB25.60905@parallels.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2504 Lines: 56 On Tue, Jun 26, 2012 at 05:37:41PM +0400, Glauber Costa wrote: > On 06/26/2012 05:38 PM, Frederic Weisbecker wrote: > >On Tue, Jun 26, 2012 at 04:48:08PM +0400, Glauber Costa wrote: > >>On 06/25/2012 10:38 PM, Tejun Heo wrote: > >>>On Mon, Jun 25, 2012 at 06:55:35PM +0200, Frederic Weisbecker wrote: > >>>>On 06/25/2012 04:15 PM, Glauber Costa wrote: > >>>> > >>>>>Because those architectures will draw their stacks directly from > >>>>>the page allocator, rather than the slab cache, we can directly > >>>>>pass __GFP_KMEMCG flag, and issue the corresponding free_pages. > >>>>> > >>>>>This code path is taken when the architecture doesn't define > >>>>>CONFIG_ARCH_THREAD_INFO_ALLOCATOR (only ia64 seems to), and has > >>>>>THREAD_SIZE >= PAGE_SIZE. Luckily, most - if not all - of the > >>>>>remaining architectures fall in this category. > >>>>> > >>>>>This will guarantee that every stack page is accounted to the memcg > >>>>>the process currently lives on, and will have the allocations to fail > >>>>>if they go over limit. > >>>>> > >>>>>For the time being, I am defining a new variant of THREADINFO_GFP, not > >>>>>to mess with the other path. Once the slab is also tracked by memcg, > >>>>>we can get rid of that flag. > >>>>> > >>>>>Tested to successfully protect against :(){ :|:& };: > >>>>> > >>>>>Signed-off-by: Glauber Costa > >>>>>CC: Christoph Lameter > >>>>>CC: Pekka Enberg > >>>>>CC: Michal Hocko > >>>>>CC: Kamezawa Hiroyuki > >>>>>CC: Johannes Weiner > >>>>>CC: Suleiman Souhlal > >>>> > >>>> > >>>>Acked-by: Frederic Weisbecker > >>> > >>>Frederic, does this (with proper slab accounting added later) achieve > >>>what you wanted with the task counter? > >>> > >> > >>A note: Frederic may confirm, but I think he doesn't even need > >>the slab accounting to follow to achieve that goal. > > > >Limiting is enough. But that requires internal accounting. > > > Yes, but why the *slab* needs to get involved? > accounting task stack pages should be equivalent to what you > were doing, even without slab accounting. Right ? Yeah that alone should be fine. -- 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/