On Thu, Nov 1, 2012 at 3:43 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > On Thu, 1 Nov 2012 14:58:18 -0700 (PDT) > David Rientjes <rientjes@xxxxxxxxxx> wrote: > >> Exiting threads, those with PF_EXITING set, can pagefault and require >> memory before they can make forward progress. This happens, for instance, >> when a process must fault task->robust_list, a userspace structure, before >> detaching its memory. >> >> These threads also aren't guaranteed to get access to memory reserves >> unless oom killed or killed from userspace. The oom killer won't grant >> memory reserves if other threads are also exiting other than current and >> stalling at the same point. This prevents needlessly killing processes >> when others are already exiting. >> >> Instead of special casing all the possible sitations between PF_EXITING >> getting set and a thread detaching its mm where it may allocate memory, >> which probably wouldn't get updated when a change is made to the exit >> path, the solution is to give all exiting threads access to memory >> reserves if they call the oom killer. This allows them to quickly >> allocate, detach its mm, and free the memory it represents. > > Seems very sensible. > >> Acked-by: Minchan Kim <minchan@xxxxxxxxxx> >> Tested-by: Luigi Semenzato <semenzato@xxxxxxxxxx> > > What did Luigi actually test? Was there some reproducible bad behavior > which this patch fixes? Yes. I have a load that reliably reproduces the problem (in 3.4), and it goes away with this change. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>