Re: mm: BUG in unmap_page_range

From: Sasha Levin
Date: Wed Sep 17 2014 - 17:38:37 EST

On 09/11/2014 06:38 PM, Sasha Levin wrote:
> On 09/11/2014 12:28 PM, Mel Gorman wrote:
>> > Agreed. If 3.17-rc4 looks stable with the VM_BUG_ON then it would be
>> > really nice if you could bisect 3.17-rc4 to linux-next carrying the
>> > VM_BUG_ON(!(val & _PAGE_PRESENT)) check at each bisection point. I'm not
>> > 100% sure if I'm seeing the same corruption as you or some other issue and
>> > do not want to conflate numerous different problems into one. I know this
>> > is a pain in the ass but if 3.17-rc4 looks stable then a bisection might
>> > be faster overall than my constant head scratching :(
> The good news are that 3.17-rc4 seems to be stable. I'll start the bisection,
> which I suspect would take several days. I'll update when I run into something.

I might need a bit of a help here. The bisection is going sideways because I
can't reliably reproduce the issue.

We don't know what's causing this issue, but we know what the symptoms are. Is
there a VM_BUG_ON we could add somewhere so that it would be more likely to

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