Re: [BUG] fatal hang untarring 90GB file, possibly writeback related.

Mel Gorman
2011-05-10T14:35:16Z

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On Tue, May 10, 2011 at 09:01:04AM -0500, James Bottomley wrote:
> On Tue, 2011-05-10 at 11:21 +0100, Mel Gorman wrote:
> > I really would like to hear if the fix makes a big difference or
> > if we need to consider forcing SLUB high-order allocations bailing
> > at the first sign of trouble (e.g. by masking out __GFP_WAIT in
> > allocate_slab). Even with the fix applied, kswapd might be waking up
> > less but processes will still be getting stalled in direct compaction
> > and direct reclaim so it would still be jittery.
>
> "the fix" being this
>
> https://lkml.org/lkml/2011/3/5/121
>

Drop this for the moment. It was a long shot at best and there is little
evidence the problem is in this area.

I'm attaching two patches. The first is the NO_KSWAPD one to stop
kswapd being woken up by SLUB using speculative high-orders. The second
one is more drastic and prevents slub entering direct reclaim or
compaction. It applies on top of patch 1. These are both untested and
afraid are a bit rushed as well :(

--
Mel Gorman
SUSE Labs

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