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SubjectRe: [patch -mm 4/9 v2] oom: remove compulsory panic_on_oom mode
On Wed, 17 Feb 2010, KAMEZAWA Hiroyuki wrote:

> > What do you think about making pagefaults use out_of_memory() directly and
> > respecting the sysctl_panic_on_oom settings?
> >
>
> I don't think this patch is good. Because several memcg can
> cause oom at the same time independently, system-wide oom locking is
> unsuitable. BTW, what I doubt is much more fundamental thing.
>

We want to lock all populated zones with ZONE_OOM_LOCKED to avoid
needlessly killing more than one task regardless of how many memcgs are
oom.

> What I doubt at most is "why VM_FAULT_OOM is necessary ? or why we have
> to call oom_killer when page fault returns it".
> Is there someone who returns VM_FAULT_OOM without calling page allocator
> and oom-killer helps something in such situation ?
>

Before we invoked the oom killer for VM_FAULT_OOM, we simply sent a
SIGKILL to current because we simply don't have memory to fault the page
in, it's better to select a memory-hogging task to kill based on badness()
than to constantly kill current which may not help in the long term.


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