linux-kernel - Re: [PATCH 4.19 078/361] nvmet-rdma: use a private workqueue for delete

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Date:   Sun, 11 Nov 2018 18:32:04 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Bart Van Assche <bvanassche@....org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Sagi Grimberg <sagi@...mberg.me>,
        Christoph Hellwig <hch@....de>, Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.19 078/361] nvmet-rdma: use a private workqueue for
 delete

On Sun, Nov 11, 2018 at 05:27:05PM -0800, Bart Van Assche wrote:
> On 11/11/18 2:17 PM, Greg Kroah-Hartman wrote:
> > 4.19-stable review patch.  If anyone has any objections, please let me know.
> > 
> > ------------------
> > 
> > From: Sagi Grimberg <sagi@...mberg.me>
> > 
> > [ Upstream commit 2acf70ade79d26b97611a8df52eb22aa33814cd4 ]
> > 
> > Queue deletion is done asynchronous when the last reference on the queue
> > is dropped.  Thus, in order to make sure we don't over allocate under a
> > connect/disconnect storm, we let queue deletion complete before making
> > forward progress.
> > 
> > However, given that we flush the system_wq from rdma_cm context which
> > runs from a workqueue context, we can have a circular locking complaint
> > [1]. Fix that by using a private workqueue for queue deletion.
> 
> Hi Greg,
> 
> You may want to drop this patch. A bug was discovered in this patch a few
> days ago. I think not backporting this patch is better than backporting it.
> See also the discussion at
> http://lists.infradead.org/pipermail/linux-nvme/2018-November/020766.html. A
> quote from that e-mail thread: "I think we need to revert 2acf70a
> ("nvmet-rdma: use a private workqueue for delete") altogether because it
> never made any difference..".

Now dropped from the 4.18 and 4.19 queues, thanks.

greg k-h