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Date:   Mon, 17 Aug 2020 19:09:56 +0300
From:   Dan Aloni <dan@kernelim.com>
To:     Chuck Lever <chuck.lever@oracle.com>
Cc:     linux-nfs@vger.kernel.org, linux-rdma@vger.kernel.org
Subject: Re: [PATCH RFC] xprtrdma: Release in-flight MRs on disconnect
Message-ID: <20200817160956.GA3516778@gmail.com>
References: <159767751439.190071.13659900216337230912.stgit@manet.1015granger.net>
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On Mon, Aug 17, 2020 at 11:19:26AM -0400, Chuck Lever wrote:
> Dan Aloni reports that when a server disconnects abruptly, a few
> memory regions are left DMA mapped. Over time this leak could pin
> enough I/O resources to slow or even deadlock an NFS/RDMA client.
> 
> I found that if a transport disconnects before pending Send and
> FastReg WRs can be posted, the to-be-registered MRs are stranded on
> the req's rl_registered list and never released -- since they
> weren't posted, there's no Send completion to DMA unmap them.
> 
> Reported-by: Dan Aloni <dan@kernelim.com>
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  net/sunrpc/xprtrdma/verbs.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> Hi Dan, does this help?

Yeah, works as expected with your fix.

Thanks!

-- 
Dan Aloni