Re: [PATCH 2/3] mm: thp: Fix the update_mmu_cache() last argumentpassing in mm/huge_memory.c

From: Catalin Marinas
Date: Wed Sep 12 2012 - 11:52:10 EST


On Wed, Sep 12, 2012 at 04:40:37PM +0100, Michal Hocko wrote:
> On Tue 11-09-12 17:47:15, Will Deacon wrote:
> > From: Catalin Marinas <catalin.marinas@xxxxxxx>
> >
> > The update_mmu_cache() takes a pointer (to pte_t by default) as the last
> > argument but the huge_memory.c passes a pmd_t value. The patch changes
> > the argument to the pmd_t * pointer.
> >
> > Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> > Signed-off-by: Steve Capper <steve.capper@xxxxxxx>
> > Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
> > ---
> > mm/huge_memory.c | 6 +++---
> > 1 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index 57c4b93..4aa6d02 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -934,7 +934,7 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
> > entry = pmd_mkyoung(orig_pmd);
> > entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
> > if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
> > - update_mmu_cache(vma, address, entry);
> > + update_mmu_cache(vma, address, pmd);
>
> I am not sure but shouldn't we use the new entry rather than the given
> pmd?

The pmd pointer is the new pmd and 'entry' is the new value derived from
orig_pmd. update_mmu_cache() expects a pointer to pte_t or pmd_t rather
than it's value.

--
Catalin
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