Re: [Bug #13648] nfsd: page allocation failure

[Justin Piszcz]

On Mon, 29 Jun 2009, David Rientjes wrote:

> On Mon, 29 Jun 2009, Rafael J. Wysocki wrote:
>
> > This message has been generated automatically as a part of a report
> > of regressions introduced between 2.6.29 and 2.6.30.
> >
> > The following bug entry is on the current list of known regressions
> > introduced between 2.6.29 and 2.6.30.  Please verify if it still should
> > be listed and let me know (either way).
> >
> >
> > Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=13648
> > Subject		: nfsd: page allocation failure
> > Submitter	: Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx>
> > Date		: 2009-06-22 12:08 (7 days old)
> > References	: http://lkml.org/lkml/2009/6/22/309
>
> I'd be interested to hear from Justin if reducing
> /proc/sys/vm/dirty_background_ratio as I earlier suggested helps.
>
> ZONE_NORMAL isn't much larger than ZONE_DMA32 on this machine and both
> lowmem zones have an abundance of free memory which suggests pdflush's
> ratio isn't being met to commence background writeout while at the same
> time ZONE_NORMAL is being depleted as the result of constant nfs
> GFP_ATOMIC allocations that cannot try direct reclaim.

Hello,

http://patchwork.kernel.org/patch/30960/

"It's funny, though, that the problem that originally started this thread 
was quickly diagnosed because of these messages.  As far as I know, my 
suggestion to increase /proc/sys/vm/dirty_background_ratio to kick pdflush 
earlier has prevented the slab allocation failures and not required 
delayed acks for nfsd."

--

The current value is 10, what value do you suggest I try?

$ cat /proc/sys/vm/dirty_background_ratio
10

Justin.

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