From mboxrd@z Thu Jan 1 00:00:00 1970 From: Glauber Costa Subject: Re: [PATCH 11/11] protect architectures where THREAD_SIZE >= PAGE_SIZE against fork bombs Date: Tue, 26 Jun 2012 16:48:08 +0400 Message-ID: <4FE9AF88.5070803@parallels.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> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120625183818.GH3869-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Tejun Heo Cc: Frederic Weisbecker , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Andrew Morton , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Frederic Weisbecker , David Rientjes , Pekka Enberg , Michal Hocko , Johannes Weiner , Christoph Lameter , devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org, Pekka Enberg , Suleiman Souhlal 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.