Re: Out of Memory: Killed process 16498 (java).

From: Andrew Morton
Date: Thu Jan 19 2006 - 17:12:31 EST


Dave Jones <davej@xxxxxxxxxx> wrote:
>
> On Thu, Jan 19, 2006 at 03:11:45PM -0000, Andy Chittenden wrote:
> > DMA free:20kB min:24kB low:28kB high:36kB active:0kB inactive:0kB
> > present:12740kB pages_scanned:4 all_unreclaimable? yes
>
> Note we only scanned 4 pages before we gave up.
> Larry Woodman came up with this patch below that clears all_unreclaimable
> when in two places where we've made progress at freeing up some pages
> which has helped oom situations for some of our users.

That won't help - there are exactly zero pages on ZONE_DMA's LRU.

The problem appears to be that all of the DMA zone has been gobbled up by
the BIO layer. It seems quite inappropriate that a modern 64-bit machine
is allocating tons of disk I/O pages from the teeny ZONE_DMA. I'm
suspecting that someone has gone and set a queue's ->bounce_gfp to the wrong
thing.

Jens, would you have time to investigate please?
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