2020-08-17 18:05:09

by Dan Aloni

[permalink] [raw]
Subject: Re: [PATCH RFC] xprtrdma: Release in-flight MRs on disconnect

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 <[email protected]>
> Signed-off-by: Chuck Lever <[email protected]>
> ---
> 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