From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeff Moyer <jmoyer@redhat.com>
Subject: Re: [RFC PATCH]  fs null_blk: Null pointer deference problem in alloc_page_buffers
Date: Fri, 17 Jan 2014 12:39:58 -0500
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References: <1389950530-8903-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com>
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Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Matias Bjorling <m@bjorling.me>, Jens Axboe <axboe@kernel.dk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Yuanhan Liu <yuanhan.liu@linux.intel.com>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	Jan Kara <jack@suse.cz>, Johannes Weiner <hannes@cmpxchg.org>,
	Zhang Yanfei <zhangyanfei@cn.fujitsu.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Sumanth <sumantk2@linux.vnet.ibm.com>
To: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
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In-Reply-To: <1389950530-8903-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com>
	(Raghavendra K. T.'s message of "Fri, 17 Jan 2014 14:52:10 +0530")
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Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> writes:

> diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
> index a2e69d2..6b0e049 100644
> --- a/drivers/block/null_blk.c
> +++ b/drivers/block/null_blk.c
> @@ -535,6 +535,11 @@ static int null_add_dev(void)
>  	if (!nullb)
>  		return -ENOMEM;
>  
> +	if (bs > PAGE_SIZE) {
> +		WARN(1, "Invalid block size. Setting it to 4096\n");
> +		bs = 4096;
> +	}
> +

Why are you hard-coding 4k instead of just using PAGE_SIZE?

Cheers,
Jeff