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Date: Thu, 04 Sep 2014 05:04:37 -0400
From: Sasha Levin <sasha.levin@oracle.com>
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To: Mel Gorman <mgorman@suse.de>
CC: Hugh Dickins <hughd@google.com>, "linux-mm@kvack.org" <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dave Jones <davej@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>, Rik van Riel <riel@redhat.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Cyrill Gorcunov <gorcunov@gmail.com>
Subject: Re: mm: BUG in unmap_page_range
References: <53DD5F20.8010507@oracle.com> <alpine.LSU.2.11.1408040418500.3406@eggly.anvils> <20140805144439.GW10819@suse.de> <alpine.LSU.2.11.1408051649330.6591@eggly.anvils> <53E17F06.30401@oracle.com> <53E989FB.5000904@oracle.com> <53FD4D9F.6050500@oracle.com> <20140827152622.GC12424@suse.de> <540127AC.4040804@oracle.com>
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On 08/29/2014 09:23 PM, Sasha Levin wrote:
> On 08/27/2014 11:26 AM, Mel Gorman wrote:
>> > diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
>> > index 281870f..ffea570 100644
>> > --- a/include/asm-generic/pgtable.h
>> > +++ b/include/asm-generic/pgtable.h
>> > @@ -723,6 +723,9 @@ static inline pte_t pte_mknuma(pte_t pte)
>> >  
>> >  	VM_BUG_ON(!(val & _PAGE_PRESENT));
>> >  
>> > +	/* debugging only, specific to x86 */
>> > +	VM_BUG_ON(val & _PAGE_PROTNONE);
>> > +
>> >  	val &= ~_PAGE_PRESENT;
>> >  	val |= _PAGE_NUMA;
> Triggered again, the first VM_BUG_ON got hit, the second one never did.

Okay, this bug has reproduced quite a few times since then that I no longer
suspect it's random memory corruption. I'd be happy to try out more debug
patches if you have any leads.


Thanks,
Sasha