Re: [PATCH 00/49] Automatic NUMA Balancing v10

From: Kirill A. Shutemov
Date: Sun Dec 09 2012 - 16:16:24 EST


On Sun, Dec 09, 2012 at 08:36:31PM +0000, Mel Gorman wrote:
> Either way, last night I applied a patch on top of latest tip/master to
> remove the nr_cpus_allowed check so that numacore would be enabled again
> and tested that. In some places it has indeed much improved. In others
> it is still regressing badly and in two case, it's corrupting memory --
> specjbb when THP is enabled crashes when running for single or multiple
> JVMs. It is likely that a zero page is being inserted due to a race with
> migration and causes the JVM to throw a null pointer exception. Here is
> the comparison on the rough off-chance you actually read it this time.

Are you talking about huge zero page, right?

I've fixed a race in huge zero page implementation recently[1]. Symptoms
were similar -- SIGSEGV in JVM. The patch is in mmotm-2012-12-05-16-56 and
later.

[1] http://lkml.org/lkml/2012/11/30/279
--
Kirill A. Shutemov
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