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Message-ID: <1522789265.2654.129.camel@codethink.co.uk>
Subject: Re: [PATCH 4.4 52/97] mtip32xx: use runtime tag to initialize
 command header
From:   Ben Hutchings <ben.hutchings@codethink.co.uk>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org
Cc:     stable@vger.kernel.org, Ming Lei <ming.lei@redhat.com>,
        Jens Axboe <axboe@fb.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Date:   Tue, 03 Apr 2018 22:01:05 +0100
In-Reply-To: <20180323094200.569562172@linuxfoundation.org>
References: <20180323094157.535925724@linuxfoundation.org>
         <20180323094200.569562172@linuxfoundation.org>
Organization: Codethink Ltd.
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On Fri, 2018-03-23 at 10:54 +0100, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Ming Lei <ming.lei@redhat.com>
> 
> 
> [ Upstream commit a4e84aae8139aca9fbfbced1f45c51ca81b57488 ]
> 
> mtip32xx supposes that 'request_idx' passed to .init_request()
> is tag of the request, and use that as request's tag to initialize
> command header.
> 
> After MQ IO scheduler is in, request tag assigned isn't same with
> the request index anymore, so cause strange hardware failure on
> mtip32xx, even whole system panic is triggered.
[...]

MQ IO schedulers were introduced in 4.11, so this shouldn't be needed
in older branches.  It also causes a performance regression (fixed
upstream).  Please revert this for 4.4 and 4.9.

Ben.

-- 
Ben Hutchings
Software Developer, Codethink Ltd.