linux-kernel - Re: [PATCH] mm: migration: pair unlock_page and lock

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Message-ID: <20111126173315.GG8397@redhat.com>
Date:	Sat, 26 Nov 2011 18:33:15 +0100
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	Hillf Danton <dhillf@...il.com>
Cc:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: [PATCH] mm: migration: pair unlock_page and lock_page when
 migrating huge pages

Hi Hillf,

On Fri, Nov 25, 2011 at 08:20:31PM +0800, Hillf Danton wrote:
> Skip unlocking page if fail to lock, then lock and unlock are paired.
> 
> Signed-off-by: Hillf Danton <dhillf@...il.com>
> ---
> 
> --- a/mm/migrate.c	Fri Nov 25 20:11:14 2011
> +++ b/mm/migrate.c	Fri Nov 25 20:21:26 2011
> @@ -869,9 +869,9 @@ static int unmap_and_move_huge_page(new_
> 
>  	if (anon_vma)
>  		put_anon_vma(anon_vma);
> -out:
>  	unlock_page(hpage);
> 
> +out:
>  	if (rc != -EAGAIN) {
>  		list_del(&hpage->lru);
>  		put_page(hpage);

Looks good, I guess that path wasn't exercised frequently because
there's no blocking I/O involvement with hugetlbfs.

Thanks,
Andrea
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