Re: [PATCH] mm/memory_failure: Fix the missing pte_unmap() call

[Qi Zheng]

On 9/23/21 11:19 PM, David Hildenbrand wrote:
> On 23.09.21 14:26, Qi Zheng wrote:
> > The paired pte_unmap() call is missing before the
> > dev_pagemap_mapping_shift() returns. So fix it.
> >
> > Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
> > ---
> >   mm/memory-failure.c | 9 ++++++---
> >   1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> > index e2984c123e7e..4e5419f16fd4 100644
> > --- a/mm/memory-failure.c
> > +++ b/mm/memory-failure.c
> > @@ -306,6 +306,7 @@ static unsigned long 
> > dev_pagemap_mapping_shift(struct page *page,
> >           struct vm_area_struct *vma)
> >   {
> >       unsigned long address = vma_address(page, vma);
> > +    unsigned long ret = 0;
> >       pgd_t *pgd;
> >       p4d_t *p4d;
> >       pud_t *pud;
> > @@ -330,10 +331,12 @@ static unsigned long 
> > dev_pagemap_mapping_shift(struct page *page,
> >           return PMD_SHIFT;
> >       pte = pte_offset_map(pmd, address);
> >       if (!pte_present(*pte))
> > -        return 0;
> > +        goto unmap;
> >       if (pte_devmap(*pte))
> > -        return PAGE_SHIFT;
> > -    return 0;
> > +        ret = PAGE_SHIFT;
> > +unmap:
> > +    pte_unmap(pte);
> > +    return ret;
> >   }
> >   /*
>
> I guess this code never runs on 32bit / highmem, that's why we didn't 
> notice so far.

I guess so too.

> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>

Thanks,
Qi