Messages in this thread |  | | | Date | Tue, 26 Jun 2012 15:38:41 +0200 | | From | Frederic Weisbecker <> | | Subject | Re: [PATCH 11/11] protect architectures where THREAD_SIZE >= PAGE_SIZE against fork bombs |
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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 <glommer@parallels.com> > >>>CC: Christoph Lameter <cl@linux.com> > >>>CC: Pekka Enberg <penberg@cs.helsinki.fi> > >>>CC: Michal Hocko <mhocko@suse.cz> > >>>CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > >>>CC: Johannes Weiner <hannes@cmpxchg.org> > >>>CC: Suleiman Souhlal <suleiman@google.com> > >> > >> > >>Acked-by: Frederic Weisbecker <fweisbec@redhat.com> > > > >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.
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