Re: [patch -mm 4/9 v2] oom: remove compulsory panic_on_oom mode

[David Rientjes]

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.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/