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Subject: Re: + futex-runtime-enable-pi-and-robust-functionality.patch added
	to -mm tree
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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To: Thomas Gleixner <tglx@linutronix.de>
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Date: Thu, 27 Mar 2008 14:32:19 +1100
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> Hmm, not sure whether there is such code, but then it would be not too bad
> to add
> 
>    if (!p)
>       return -EFAULT;
> 
> to the S390 implementations which only read data and have an exception
> fixup.

I have a different problem on some embedded powerpc's where the TLB miss
code isn't checking for the cached pgdir pointer being NULL (which
happens because we are early at boot and haven't activated an mm). So we
end up either taking recursive faults or going into lalaland walking
the page tables.

It happens on some unreleased code, I'll verify if it happens on
8xx/4xx/etc... in a minute, and will cook a patch if it does.

Cheers,
Ben.