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

Justin Piszcz
2009-06-30T08:05:02Z

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-BP4nVm5VUdNhbmWW9KSYcQ@public.gmane.org>
>> 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.