Re: [PATCH 13/18] mm, hugetlb: grab a page_table_lock afterpage_cache_release

[Naoya Horiguchi]

On Mon, Jul 29, 2013 at 02:32:04PM +0900, Joonsoo Kim wrote:
> We don't need to grab a page_table_lock when we try to release a page.
> So, defer to grab a page_table_lock.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>

Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>

> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 35ccdad..255bd9e 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2630,10 +2630,11 @@ retry_avoidcopy:
>  	}
>  	spin_unlock(&mm->page_table_lock);
>  	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
> -	/* Caller expects lock to be held */
> -	spin_lock(&mm->page_table_lock);
>  	page_cache_release(new_page);
>  	page_cache_release(old_page);
> +
> +	/* Caller expects lock to be held */
> +	spin_lock(&mm->page_table_lock);
>  	return 0;
>  }
>  
> -- 
> 1.7.9.5
> 
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