Re: Memory management woes - order 1 allocation failures

[Christoph Lameter]

On Fri, 26 Feb 2010, Frans Pop wrote:

> On Friday 26 February 2010, Pekka Enberg wrote:
> > > Isn't it a bit strange that cache claims so much memory that real
> > > processes get into allocation failures?
> >
> > All of the failed allocations seem to be GFP_ATOMIC so it's not _that_
> > strange.
>
> It's still very ugly though. And I would say it should be unnecessary.
>
> > Dunno if anything changed recently. What's the last known good kernel for
> > you?
>
> I've not used that box very intensively in the past, but I first saw the
> allocation failure with aptitude with either .31 or .32. I would be
> extremely surprised if I could reproduce the problem with .30.
> And I have done large rsyncs to the box without any problems in the past,
> but that must have been with .24 or so kernels.
>
> It seems likely to me that it's related to all the other swap and
> allocation issues we've been seeing after .30.

Hmmm.. How long is the allocation that fails? SLUB can always fall back to
order 0 allocs if the object is < PAGE_SIZE. SLAB cannot do so if it has
decided to use a higher order slab cache for a kmalloc cache.

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