linux-kernel - Re: [PATCH v2 05/20] mm, hugetlb: grab a page_table_lock after page_cache

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Date:	Wed, 21 Aug 2013 15:01:05 +0530
From:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
	Michal Hocko <mhocko@...e.cz>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Hugh Dickins <hughd@...gle.com>,
	Davidlohr Bueso <davidlohr.bueso@...com>,
	David Gibson <david@...son.dropbear.id.au>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Joonsoo Kim <js1304@...il.com>,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Hillf Danton <dhillf@...il.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v2 05/20] mm, hugetlb: grab a page_table_lock after page_cache_release

Joonsoo Kim <iamjoonsoo.kim@....com> writes:

> 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.
>
> Reviewed-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>


Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>

>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index c017c52..6c8eec2 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2627,10 +2627,11 @@ 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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