Messages in this thread | | | Date | Tue, 21 Aug 2012 13:40:45 +0400 | From | Glauber Costa <> | Subject | Re: [PATCH v2 11/11] protect architectures where THREAD_SIZE >= PAGE_SIZE against fork bombs |
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On 08/21/2012 01:35 PM, Michal Hocko wrote: > On Thu 09-08-12 17:01:19, 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. > > quick git grep "define *THREAD_SIZE\>" arch says that there is no such > architecture. > >> 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 :(){ :|:& };: > > I guess there were no other tasks in the same group (except for the > parent shell), right?
Yes.
> I am asking because this should trigger memcg-oom > but that one will usually pick up something else than the fork bomb > which would have a small memory footprint. But that needs to be handled > on the oom level obviously. > Sure, but keep in mind that the main protection is against tasks *not* in this memcg.
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