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

From: Michal Hocko
Date: Mon Oct 19 2015 - 09:21:00 EST


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@xxxxxxxxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxxx>

> ---
> 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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