Re: [RFC] shared page table for hugetlbpage memory causing leak.

[Balbir Singh <balbir@linux.vnet.ibm.com>]

* Larry Woodman <lwoodman@redhat.com> [2008-01-17 06:53:38]:

> On Thu, 2008-01-17 at 15:49 +0530, Balbir Singh wrote:
> > * Adam Litke <agl@us.ibm.com> [2008-01-16 12:54:28]:
> > 
> > > Since we know we are dealing with a hugetlb VMA, how about the
> > > following, simpler, _untested_ patch:
> > > 
> > > Signed-off-by: Adam Litke <agl@us.ibm.com>
> > > 
> > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > > index 6f97821..75b0e4f 100644
> > > --- a/mm/hugetlb.c
> > > +++ b/mm/hugetlb.c
> > > @@ -644,6 +644,11 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
> > >  		dst_pte = huge_pte_alloc(dst, addr);
> > >  		if (!dst_pte)
> > >  			goto nomem;
> > > +
> > > +		/* If page table is shared do not copy or take references */
> > > +		if (src_pte == dst_pte)
> > > +			continue;
> > > +
> > 
> > Shouldn't you be checking the PTE contents rather than the pointers?
> No, this is chacking for shared page tables not shared pages.

Aah.. I see.

Thanks for clarifying!

-- 
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

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