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Date: Thu, 19 Oct 2017 00:02:49 -0600
From: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Subject: Re: [PATCH v9 0/6] MAP_DIRECT for DAX userspace flush
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To: Sagi Grimberg <sagi@grimberg.me>
Cc: linux-xfs@vger.kernel.org, Jan Kara <jack@suse.cz>, Arnd Bergmann <arnd@arndb.de>, "Darrick J. Wong" <darrick.wong@oracle.com>, Linux API <linux-api@vger.kernel.org>, "linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>, Dave Chinner <david@fromorbit.com>, Christoph Hellwig <hch@lst.de>, "J. Bruce Fields" <bfields@fieldses.org>, Linux MM <linux-mm@kvack.org>, Jeff Layton <jlayton@poochiereds.net>, Al Viro <viro@zeniv.linux.org.uk>, Andy Lutomirski <luto@kernel.org>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>
List-ID: <linux-nvdimm@lists.01.org>

On Mon, Oct 16, 2017 at 03:02:52PM +0300, Sagi Grimberg wrote:
> But why should the kernel ever need to mangle the CQ? if a lease break
> would deregister the MR the device is expected to generate remote
> protection errors on its own.

The point is to avoid protection errors - hittles change over when the
DAX mapping changes like ODP does.

Theonly way to get there is to notify the app before the mappings
change.. Dan suggested having ibv_pollcq return this indication..

Jason
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