2021-09-23 12:29:37

by Qi Zheng

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

The paired pte_unmap() call is missing before the
dev_pagemap_mapping_shift() returns. So fix it.

Signed-off-by: Qi Zheng <[email protected]>
---
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;
}

/*
--
2.11.0

2021-09-23 15:20:47

by David Hildenbrand

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

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 <[email protected]>
> ---
> 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.

Reviewed-by: David Hildenbrand <[email protected]>

--
Thanks,

David / dhildenb

2021-09-23 15:35:02

by Qi Zheng

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

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 <[email protected]>
>> ---
>>   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 <[email protected]>
>

Thanks,
Qi

2021-09-23 23:20:07

by Andrew Morton

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

On Thu, 23 Sep 2021 20:26:42 +0800 Qi Zheng <[email protected]> wrote:

> The paired pte_unmap() call is missing before the
> dev_pagemap_mapping_shift() returns. So fix it.
>
> ...
>
> --- 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;
> }
>

This is neater?

+++ a/mm/memory-failure.c
@@ -330,11 +330,8 @@ static unsigned long dev_pagemap_mapping
if (pmd_devmap(*pmd))
return PMD_SHIFT;
pte = pte_offset_map(pmd, address);
- if (!pte_present(*pte))
- goto unmap;
- if (pte_devmap(*pte))
+ if (pte_present(*pte) && pte_devmap(*pte))
ret = PAGE_SHIFT;
-unmap:
pte_unmap(pte);
return ret;
}
_

2021-09-24 00:32:13

by Naoya Horiguchi

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

On Thu, Sep 23, 2021 at 04:17:38PM -0700, Andrew Morton wrote:
> On Thu, 23 Sep 2021 20:26:42 +0800 Qi Zheng <[email protected]> wrote:
>
> > The paired pte_unmap() call is missing before the
> > dev_pagemap_mapping_shift() returns. So fix it.
> >
> > ...
> >
> > --- 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;
> > }
> >
>
> This is neater?
>
> +++ a/mm/memory-failure.c
> @@ -330,11 +330,8 @@ static unsigned long dev_pagemap_mapping
> if (pmd_devmap(*pmd))
> return PMD_SHIFT;
> pte = pte_offset_map(pmd, address);
> - if (!pte_present(*pte))
> - goto unmap;
> - if (pte_devmap(*pte))
> + if (pte_present(*pte) && pte_devmap(*pte))
> ret = PAGE_SHIFT;
> -unmap:

This neater one looks good to me.

Acked-by: Naoya Horiguchi <[email protected]>

2021-09-24 02:26:57

by Qi Zheng

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

On 9/24/21 7:17 AM, Andrew Morton wrote:
> On Thu, 23 Sep 2021 20:26:42 +0800 Qi Zheng <[email protected]> wrote:
>
>> The paired pte_unmap() call is missing before the
>> dev_pagemap_mapping_shift() returns. So fix it.
>>
>> ...
>>
>> --- 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;
>> }
>>
>
> This is neater?

Yes, and I see this neater version has merged into your mm tree,
thanks. :)

>
> +++ a/mm/memory-failure.c
> @@ -330,11 +330,8 @@ static unsigned long dev_pagemap_mapping
> if (pmd_devmap(*pmd))
> return PMD_SHIFT;
> pte = pte_offset_map(pmd, address);
> - if (!pte_present(*pte))
> - goto unmap;
> - if (pte_devmap(*pte))
> + if (pte_present(*pte) && pte_devmap(*pte))
> ret = PAGE_SHIFT;
> -unmap:
> pte_unmap(pte);
> return ret;
> }
> _
>