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[156.34.55.100]) by smtp.gmail.com with ESMTPSA id n10sm1577550qke.72.2019.06.13.08.12.19 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 13 Jun 2019 08:12:19 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1hbROk-0001qR-Po; Thu, 13 Jun 2019 12:12:18 -0300 Date: Thu, 13 Jun 2019 12:12:18 -0300 From: Jason Gunthorpe To: Dan Williams Cc: Ira Weiny , Jan Kara , Theodore Ts'o , Jeff Layton , Dave Chinner , Matthew Wilcox , linux-xfs , Andrew Morton , John Hubbard , =?utf-8?B?SsOpcsO0bWU=?= Glisse , linux-fsdevel , Linux Kernel Mailing List , linux-nvdimm , linux-ext4 , Linux MM Subject: Re: [PATCH RFC 00/10] RDMA/FS DAX truncate proposal Message-ID: <20190613151218.GB22901@ziepe.ca> References: <20190606222228.GB11698@iweiny-DESK2.sc.intel.com> <20190607103636.GA12765@quack2.suse.cz> <20190607121729.GA14802@ziepe.ca> <20190607145213.GB14559@iweiny-DESK2.sc.intel.com> <20190612102917.GB14578@quack2.suse.cz> <20190612114721.GB3876@ziepe.ca> <20190612120907.GC14578@quack2.suse.cz> <20190612191421.GM3876@ziepe.ca> <20190612221336.GA27080@iweiny-DESK2.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Jun 12, 2019 at 03:54:19PM -0700, Dan Williams wrote: > > > My preference would be to avoid this scenario, but if it is really > > > necessary, we could probably build it with some work. > > > > > > The only case we use it today is forced HW hot unplug, so it is rarely > > > used and only for an 'emergency' like use case. > > > > I'd really like to avoid this as well. I think it will be very confusing for > > RDMA apps to have their context suddenly be invalid. I think if we have a way > > for admins to ID who is pinning a file the admin can take more appropriate > > action on those processes. Up to and including killing the process. > > Can RDMA context invalidation, "device disassociate", be inflicted on > a process from the outside? Yes, but it is currently only applied to the entire device - ie you do 'rmmod mlx5_ib' and all the running user space process see that their FD has moved to some error and the device is broken. Targetting the disassociate of only a single FD would be a new thing. Jason