Messages in this thread | | | Date | Fri, 1 Aug 2014 14:42:19 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [patch 2/3] mm, oom: remove unnecessary check for NULL zonelist |
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On Fri, 1 Aug 2014, Johannes Weiner wrote:
> > > out_of_memory() wants the zonelist that was used during allocation, > > > not just the random first node's zonelist that's simply picked to > > > serialize page fault OOM kills system-wide. > > > > > > This would even change how panic_on_oom behaves for page fault OOMs > > > (in a completely unpredictable way) if we get CONSTRAINED_CPUSET. > > > > > > This change makes no sense to me. > > > > > > > Allocations during fault will be constrained by the cpuset's mems, if we > > are oom then why would we panic when panic_on_oom == 1? > > Can you please address the concerns I raised? >
I see one concern: that panic_on_oom == 1 will not trigger on pagefault when constrained by cpusets. To address that, I'll state that, since cpuset-constrained allocations are the allocation context for pagefaults, panic_on_oom == 1 should not trigger on pagefault when constrained by cpusets.
> And please describe user-visible changes in the changelog. >
Ok, Andrew please annotate the changelog for mm-oom-remove-unnecessary-check-for-null-zonelist.patch by including:
This also causes panic_on_oom == 1 to not panic the machine when the pagefault is constrained by the mems of current's cpuset. That behavior agrees with the semantics of the sysctl in Documentation/sysctl/vm.txt.
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