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Date:   Tue, 23 Jul 2019 09:10:41 +0800
From:   Ming Lei <ming.lei@redhat.com>
To:     Bob Liu <bob.liu@oracle.com>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        linux-nvme@lists.infradead.org, Max Gurtovoy <maxg@mellanox.com>,
        Sagi Grimberg <sagi@grimberg.me>,
        Keith Busch <keith.busch@intel.com>,
        Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 0/5] blk-mq: wait until completed req's complete fn is run
Message-ID: <20190723011040.GE30776@ming.t460p>
References: <20190722053954.25423-1-ming.lei@redhat.com>
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On Tue, Jul 23, 2019 at 07:27:00AM +0800, Bob Liu wrote:
> On 7/22/19 1:39 PM, Ming Lei wrote:
> > Hi,
> > 
> > blk-mq may schedule to call queue's complete function on remote CPU via
> > IPI, but never provide any way to synchronize the request's complete
> > fn.
> > 
> > In some driver's EH(such as NVMe), hardware queue's resource may be freed &
> > re-allocated. If the completed request's complete fn is run finally after the
> > hardware queue's resource is released, kernel crash will be triggered.
> > 
> 
> Have you seen the crash? Anyway to emulate/verify this bug..

The crash is reported on nvme-rdma by one RH partner, and the approach
of this patchset has been verified already.

Thanks,
Ming