On Fri, 1 Aug 2014, Johannes Weiner wrote:

quoted

quoted

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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