From: Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH 11/19] mm: page_alloc: Lookup pageblock migratetype with
 IRQs enabled during free
Date: Tue, 13 May 2014 15:36:25 +0200
Message-ID: <53721FD9.6000106@suse.cz>
References: <1399974350-11089-1-git-send-email-mgorman@suse.de> <1399974350-11089-12-git-send-email-mgorman@suse.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Cc: Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>,
 Michal Hocko <mhocko@suse.cz>,
 Hugh Dickins <hughd@google.com>, Peter Zijlstra <peterz@infradead.org>,
 Dave Hansen <dave.hansen@intel.com>,
 Linux Kernel <linux-kernel@vger.kernel.org>,
 Linux-MM <linux-mm@kvack.org>,
 Linux-FSDevel <linux-fsdevel@vger.kernel.org>
To: Mel Gorman <mgorman@suse.de>,
 Andrew Morton <akpm@linux-foundation.org>
Return-path: <owner-linux-mm@kvack.org>
In-Reply-To: <1399974350-11089-12-git-send-email-mgorman@suse.de>
Sender: owner-linux-mm@kvack.org
List-Id: linux-fsdevel.vger.kernel.org

On 05/13/2014 11:45 AM, Mel Gorman wrote:
> get_pageblock_migratetype() is called during free with IRQs disabled. This
> is unnecessary and disables IRQs for longer than necessary.
>
> Signed-off-by: Mel Gorman <mgorman@suse.de>
> Acked-by: Rik van Riel <riel@redhat.com>

With a comment below,

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>   mm/page_alloc.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 3948f0a..fcbf637 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -773,9 +773,9 @@ static void __free_pages_ok(struct page *page, unsigned int order)
>   	if (!free_pages_prepare(page, order))
>   		return;
>
> +	migratetype = get_pfnblock_migratetype(page, pfn);
>   	local_irq_save(flags);
>   	__count_vm_events(PGFREE, 1 << order);
> -	migratetype = get_pfnblock_migratetype(page, pfn);
>   	set_freepage_migratetype(page, migratetype);

The line above could be also outside disabled IRQ, no?

>   	free_one_page(page_zone(page), page, pfn, order, migratetype);
>   	local_irq_restore(flags);
>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>