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Date:   Thu, 24 Feb 2022 05:37:03 -0800
From:   Christoph Hellwig <hch@infradead.org>
To:     "Wang Jianchao (Kuaishou)" <jianchao.wan9@gmail.com>
Cc:     Jens Axboe <axboe@kernel.dk>, Josef Bacik <jbacik@fb.com>,
        Tejun Heo <tj@kernel.org>,
        Bart Van Assche <bvanassche@acm.org>,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC V5 0/16] blk: blk-rq-qos framework refactor and cleanup
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On Thu, Feb 24, 2022 at 05:06:38PM +0800, Wang Jianchao (Kuaishou) wrote:
> Hi Jens
> 
> This patchset is working on our v4.18 kernel to provide the capacity
> for upgrade blk-rq-qos policies on the fly w/o needing to restart
> machine and applications.

Why would you upgrade kernel code at runtime?  And how is what you do
on some randm old kernel relevant for mainline?