[PATCH] mm: do not inc NR_PAGETABLE if ptlock_init failed

[PATCH] mm: do not inc NR_PAGETABLE if ptlock_init failed

[Vladimir Davydov]

If ALLOC_SPLIT_PTLOCKS is defined, ptlock_init may fail, in which case
we shouldn't increment NR_PAGETABLE.

Since small allocations, such as ptlock, normally do not fail (currently
they can fail if kmemcg is used though), this patch does not really fix
anything and should be considered as a code cleanup.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
---
 include/linux/mm.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6adf4167d664..30ef3b535444 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1553,8 +1553,10 @@ static inline void pgtable_init(void)
 
 static inline bool pgtable_page_ctor(struct page *page)
 {
+	if (!ptlock_init(page))
+		return false;
 	inc_zone_page_state(page, NR_PAGETABLE);
-	return ptlock_init(page);
+	return true;
 }
 
 static inline void pgtable_page_dtor(struct page *page)
-- 
2.1.4

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Re: [PATCH] mm: do not inc NR_PAGETABLE if ptlock_init failed

[Kirill A. Shutemov]

On Mon, Oct 19, 2015 at 03:14:41PM +0300, Vladimir Davydov wrote:
> If ALLOC_SPLIT_PTLOCKS is defined, ptlock_init may fail, in which case
> we shouldn't increment NR_PAGETABLE.
> 
> Since small allocations, such as ptlock, normally do not fail (currently
> they can fail if kmemcg is used though), this patch does not really fix
> anything and should be considered as a code cleanup.
> 
> Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

-- 
 Kirill A. Shutemov

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Re: [PATCH] mm: do not inc NR_PAGETABLE if ptlock_init failed

[Michal Hocko]

On Mon 19-10-15 15:14:41, Vladimir Davydov wrote:
> If ALLOC_SPLIT_PTLOCKS is defined, ptlock_init may fail, in which case
> we shouldn't increment NR_PAGETABLE.
> 
> Since small allocations, such as ptlock, normally do not fail (currently
> they can fail if kmemcg is used though), this patch does not really fix
> anything and should be considered as a code cleanup.
> 
> Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  include/linux/mm.h | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 6adf4167d664..30ef3b535444 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1553,8 +1553,10 @@ static inline void pgtable_init(void)
>  
>  static inline bool pgtable_page_ctor(struct page *page)
>  {
> +	if (!ptlock_init(page))
> +		return false;
>  	inc_zone_page_state(page, NR_PAGETABLE);
> -	return ptlock_init(page);
> +	return true;
>  }
>  
>  static inline void pgtable_page_dtor(struct page *page)
> -- 
> 2.1.4
> 
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-- 
Michal Hocko
SUSE Labs

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