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Date: Fri, 22 Nov 2024 13:08:28 +0100
From: Christoph Hellwig <hch@lst.de>
To: Nilay Shroff <nilay@linux.ibm.com>
Cc: linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
	kbusch@kernel.org, hch@lst.de, sagi@grimberg.me, axboe@fb.com,
	chaitanyak@nvidia.com, yi.zhang@redhat.com,
	shinichiro.kawasaki@wdc.com, mlombard@redhat.com,
	gjoyce@linux.ibm.com
Subject: Re: [PATCH] nvmet: fix the use of ZERO_PAGE in
 nvme_execute_identify_ns_nvm()
Message-ID: <20241122120828.GB25707@lst.de>
References: <20241122085113.2487839-1-nilay@linux.ibm.com>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Fri, Nov 22, 2024 at 02:20:36PM +0530, Nilay Shroff wrote:
> The nvme_execute_identify_ns_nvm function uses ZERO_PAGE
> for copying SG list with all zeros. As ZERO_PAGE would not
> necessarily return the virtual-address of the zero page, we
> need to first convert the page address to kernel virtual-
> address and then use it as source address for copying the
> data to SG list with all zeros.
> 
> Using return address of ZERO_PAGE(0) as source address for
> copying data to SG list would fill the target buffer with
> random value and causes the undesired side effect. This patch
> implements the fix ensuring that we use virtual-address of the
> zero page for copying all zeros to the SG list buffers.

I wonder if using ZERO_PAGE() is simply a little too smart for it's
own sake and it should just use kzalloc like a bunch of other identify
implementation..