Subject: Re: [Libhugetlbfs-devel] libbugetlbfs: Test case for powerpc huge_ptep_set_wrprotect() bug

From: Adam Litke <[email-masked]>
Date: Mon, 07 Jul 2008 10:27:00 -0500

On Mon, 2008-07-07 at 17:19 +1000, David Gibson wrote:
> Until very recently (in fact, even now in mainline) powerpc kernels
> had a bug in huge_ptep_set_wrprotect() which meant the 'huge' flag was
> not passed down to pte_update() and hpte_need_flush().  This meant the
> hash ptes for hugepages would not be correctly flushed on fork(),
> allowing the parent to pollute the child's mapping after the fork().
> 
> This patch adds a testcase to libhugetlbfs for this behaviour, also
> doing some other checking of the COW semantics over a fork().
> 
> Signed-off-by: David Gibson <[email-masked]>
Good test David, thanks...
Acked-by: Adam Litke <[email-masked]>

-- 
Adam Litke - (agl at us.ibm.com)
IBM Linux Technology Center