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Date: Sun, 9 Dec 2012 23:17:09 +0200
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Mel Gorman <mgorman@suse.de>
Cc: Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Andrea Arcangeli <aarcange@redhat.com>, Rik van Riel <riel@redhat.com>,
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        Thomas Gleixner <tglx@linutronix.de>, Paul Turner <pjt@google.com>,
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        Alex Shi <lkml.alex@gmail.com>,
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        Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 00/49] Automatic NUMA Balancing v10
Message-ID: <20121209211708.GA29607@shutemov.name>
References: <1354875832-9700-1-git-send-email-mgorman@suse.de>
 <20121207110113.GB21482@gmail.com>
 <20121209203630.GC1009@suse.de>
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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