Message-ID: <4AF8433C.4090905@redhat.com>
Date: Mon, 09 Nov 2009 18:28:44 +0200
From: Izik Eidus <ieidus@redhat.com>
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To: Hugh Dickins <hugh.dickins@tiscali.co.uk>
CC: Linus Torvalds <torvalds@linux-foundation.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Andrea Arcangeli <aarcange@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ksm: cond_resched in unstable tree
References: <Pine.LNX.4.64.0911091554500.25509@sister.anvils>
In-Reply-To: <Pine.LNX.4.64.0911091554500.25509@sister.anvils>
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On 11/09/2009 05:58 PM, Hugh Dickins wrote:
> KSM needs a cond_resched() for CONFIG_PREEMPT_NONE, in its unbounded
> search of the unstable tree.  The stable tree cases already have one,
> and originally there was one down inside get_user_pages();
> but I missed it when I converted to follow_page() instead.
>
> Signed-off-by: Hugh Dickins<hugh.dickins@tiscali.co.uk>
> ---
>
>   mm/ksm.c |    1 +
>   1 file changed, 1 insertion(+)
>
> --- 2.6.32-rc6/mm/ksm.c	2009-10-12 00:26:43.000000000 +0100
> +++ linux/mm/ksm.c	2009-11-07 14:44:58.000000000 +0000
> @@ -1012,6 +1012,7 @@ static struct rmap_item *unstable_tree_s
>   		struct rmap_item *tree_rmap_item;
>   		int ret;
>
> +		cond_resched();
>   		tree_rmap_item = rb_entry(*new, struct rmap_item, node);
>   		page2[0] = get_mergeable_page(tree_rmap_item);
>   		if (!page2[0])
>    
ACK.
Low risk patch - we are for sure at sleepable context there.
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