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Date: Thu, 20 Dec 2012 15:06:42 +0400
From: Glauber Costa <glommer@parallels.com>
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To: Dave Chinner <david@fromorbit.com>
CC: <linux-kernel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
        <linux-mm@kvack.org>, <xfs@oss.sgi.com>
Subject: Re: [PATCH 05/19] shrinker: convert superblock shrinkers to new API
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On 11/28/2012 03:14 AM, Dave Chinner wrote:
> +static long super_cache_count(struct shrinker *shrink, struct shrink_control *sc)
> +{
> +	struct super_block *sb;
> +	long	total_objects = 0;
> +
> +	sb = container_of(shrink, struct super_block, s_shrink);
> +
> +	if (!grab_super_passive(sb))
> +		return -1;
> +


You're missing the GFP_FS check here. This leads to us doing all the
counting only to find out later, in the scanner, that we won't be able
to free it. Better exit early.