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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Jan Kara <jack@suse.cz>
Cc: "Ira Weiny" <ira.weiny@intel.com>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Theodore Ts'o" <tytso@mit.edu>,
	"Jeff Layton" <jlayton@kernel.org>,
	"Dave Chinner" <david@fromorbit.com>,
	"Matthew Wilcox" <willy@infradead.org>,
	linux-xfs@vger.kernel.org,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"John Hubbard" <jhubbard@nvidia.com>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvdimm@lists.01.org, linux-ext4@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH RFC 00/10] RDMA/FS DAX truncate proposal
Date: Fri, 7 Jun 2019 09:17:29 -0300	[thread overview]
Message-ID: <20190607121729.GA14802@ziepe.ca> (raw)
In-Reply-To: <20190607103636.GA12765@quack2.suse.cz>

On Fri, Jun 07, 2019 at 12:36:36PM +0200, Jan Kara wrote:

> Because the pins would be invisible to sysadmin from that point on. 

It is not invisible, it just shows up in a rdma specific kernel
interface. You have to use rdma netlink to see the kernel object
holding this pin.

If this visibility is the main sticking point I suggest just enhancing
the existing MR reporting to include the file info for current GUP
pins and teaching lsof to collect information from there as well so it
is easy to use.

If the ownership of the lease transfers to the MR, and we report that
ownership to userspace in a way lsof can find, then I think all the
concerns that have been raised are met, right?

> ugly to live so we have to come up with something better. The best I can
> currently come up with is to have a method associated with the lease that
> would invalidate the RDMA context that holds the pins in the same way that
> a file close would do it.

This is back to requiring all RDMA HW to have some new behavior they
currently don't have..

The main objection to the current ODP & DAX solution is that very
little HW can actually implement it, having the alternative still
require HW support doesn't seem like progress.

I think we will eventually start seein some HW be able to do this
invalidation, but it won't be universal, and I'd rather leave it
optional, for recovery from truely catastrophic errors (ie my DAX is
on fire, I need to unplug it).

Jason

  reply	other threads:[~2019-06-07 12:17 UTC|newest]

Thread overview: 136+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-06  1:45 [PATCH RFC 00/10] RDMA/FS DAX truncate proposal ira.weiny
2019-06-06  1:45 ` ira.weiny
2019-06-06  1:45 ` [PATCH RFC 01/10] fs/locks: Add trace_leases_conflict ira.weiny
2019-06-09 12:52   ` Jeff Layton
2019-06-06  1:45 ` [PATCH RFC 02/10] fs/locks: Export F_LAYOUT lease to user space ira.weiny
2019-06-06  1:45   ` ira.weiny
2019-06-09 13:00   ` Jeff Layton
2019-06-09 13:00     ` Jeff Layton
2019-06-11 21:38     ` Ira Weiny
2019-06-11 21:38       ` Ira Weiny
2019-06-12  9:46       ` Jan Kara
2019-06-06  1:45 ` [PATCH RFC 03/10] mm/gup: Pass flags down to __gup_device_huge* calls ira.weiny
2019-06-06  1:45   ` ira.weiny
2019-06-06  6:18   ` Christoph Hellwig
2019-06-06 16:10     ` Ira Weiny
2019-06-06  1:45 ` [PATCH RFC 04/10] mm/gup: Ensure F_LAYOUT lease is held prior to GUP'ing pages ira.weiny
2019-06-06  1:45   ` ira.weiny
2019-06-06  1:45 ` [PATCH RFC 05/10] fs/ext4: Teach ext4 to break layout leases ira.weiny
2019-06-06  1:45   ` ira.weiny
2019-06-06  1:45 ` [PATCH RFC 06/10] fs/ext4: Teach dax_layout_busy_page() to operate on a sub-range ira.weiny
2019-06-06  1:45   ` ira.weiny
2019-06-06  1:45 ` [PATCH RFC 07/10] fs/ext4: Fail truncate if pages are GUP pinned ira.weiny
2019-06-06  1:45   ` ira.weiny
2019-06-06 10:58   ` Jan Kara
2019-06-06 10:58     ` Jan Kara
2019-06-06 16:17     ` Ira Weiny
2019-06-06  1:45 ` [PATCH RFC 08/10] fs/xfs: Teach xfs to use new dax_layout_busy_page() ira.weiny
2019-06-06  1:45   ` ira.weiny
2019-06-06  1:45 ` [PATCH RFC 09/10] fs/xfs: Fail truncate if pages are GUP pinned ira.weiny
2019-06-06  1:45   ` ira.weiny
2019-06-06  1:45 ` [PATCH RFC 10/10] mm/gup: Remove FOLL_LONGTERM DAX exclusion ira.weiny
2019-06-06  1:45   ` ira.weiny
2019-06-06  5:52 ` [PATCH RFC 00/10] RDMA/FS DAX truncate proposal John Hubbard
2019-06-06  5:52   ` John Hubbard
2019-06-06 17:11   ` Ira Weiny
2019-06-06 17:11     ` Ira Weiny
2019-06-06 19:46     ` Jason Gunthorpe
2019-06-06 10:42 ` Jan Kara
2019-06-06 15:35   ` Dan Williams
2019-06-06 19:51   ` Jason Gunthorpe
2019-06-06 22:22     ` Ira Weiny
2019-06-07 10:36       ` Jan Kara
2019-06-07 12:17         ` Jason Gunthorpe [this message]
2019-06-07 14:52           ` Ira Weiny
2019-06-07 14:52             ` Ira Weiny
2019-06-07 15:10             ` Jason Gunthorpe
2019-06-12 10:29             ` Jan Kara
2019-06-12 10:29               ` Jan Kara
2019-06-12 11:47               ` Jason Gunthorpe
2019-06-12 12:09                 ` Jan Kara
2019-06-12 12:09                   ` Jan Kara
2019-06-12 18:41                   ` Dan Williams
2019-06-13  7:17                     ` Jan Kara
2019-06-13  7:17                       ` Jan Kara
2019-06-12 19:14                   ` Jason Gunthorpe
2019-06-12 22:13                     ` Ira Weiny
2019-06-12 22:54                       ` Dan Williams
2019-06-12 22:54                         ` Dan Williams
2019-06-12 23:33                         ` Ira Weiny
2019-06-12 23:33                           ` Ira Weiny
2019-06-13  1:14                           ` Dan Williams
2019-06-13  1:14                             ` Dan Williams
2019-06-13 15:13                             ` Jason Gunthorpe
2019-06-13 16:25                               ` Dan Williams
2019-06-13 16:25                                 ` Dan Williams
2019-06-13 17:18                                 ` Jason Gunthorpe
2019-06-13 16:53                           ` Dan Williams
2019-06-13 16:53                             ` Dan Williams
2019-06-13 15:12                         ` Jason Gunthorpe
2019-06-13  7:53                       ` Jan Kara
2019-06-13  7:53                         ` Jan Kara
2019-06-12 18:49               ` Dan Williams
2019-06-12 18:49                 ` Dan Williams
2019-06-13  7:43                 ` Jan Kara
2019-06-06 22:03   ` Ira Weiny
2019-06-06 22:03     ` Ira Weiny
2019-06-06 22:26     ` Ira Weiny
2019-06-06 22:28     ` Dave Chinner
2019-06-07 11:04     ` Jan Kara
2019-06-07 18:25       ` Ira Weiny
2019-06-07 18:25         ` Ira Weiny
2019-06-07 18:25         ` Ira Weiny
2019-06-07 18:50         ` Jason Gunthorpe
2019-06-08  0:10         ` Dave Chinner
2019-06-08  0:10           ` Dave Chinner
2019-06-09  1:29           ` Ira Weiny
2019-06-09  1:29             ` Ira Weiny
2019-06-09  1:29             ` Ira Weiny
2019-06-12 12:37           ` Matthew Wilcox
2019-06-12 12:37             ` Matthew Wilcox
2019-06-12 12:37             ` Matthew Wilcox
2019-06-12 23:30             ` Ira Weiny
2019-06-12 23:30               ` Ira Weiny
2019-06-12 23:30               ` Ira Weiny
2019-06-13  0:55               ` Dave Chinner
2019-06-13  0:55                 ` Dave Chinner
2019-06-13  0:55                 ` Dave Chinner
2019-06-13 20:34                 ` Ira Weiny
2019-06-13 20:34                   ` Ira Weiny
2019-06-13 20:34                   ` Ira Weiny
2019-06-14  3:42                   ` Dave Chinner
2019-06-13  0:25             ` Dave Chinner
2019-06-13  0:25               ` Dave Chinner
2019-06-13  3:23               ` Matthew Wilcox
2019-06-13  3:23                 ` Matthew Wilcox
2019-06-13  3:23                 ` Matthew Wilcox
2019-06-13  4:36                 ` Dave Chinner
2019-06-13  4:36                   ` Dave Chinner
2019-06-13  4:36                   ` Dave Chinner
2019-06-13 10:47                   ` Matthew Wilcox
2019-06-13 10:47                     ` Matthew Wilcox
2019-06-13 10:47                     ` Matthew Wilcox
2019-06-13 15:29                 ` Jason Gunthorpe
2019-06-13 15:27               ` Matthew Wilcox
2019-06-13 15:27                 ` Matthew Wilcox
2019-06-13 15:27                 ` Matthew Wilcox
2019-06-13 21:13                 ` Ira Weiny
2019-06-13 21:13                   ` Ira Weiny
2019-06-13 23:45                   ` Jason Gunthorpe
2019-06-14  0:00                     ` Ira Weiny
2019-06-14  0:00                       ` Ira Weiny
2019-06-14  2:09                     ` Dave Chinner
2019-06-14  2:09                       ` Dave Chinner
2019-06-14  2:09                       ` Dave Chinner
2019-06-14  2:31                       ` Matthew Wilcox
2019-06-14  2:31                         ` Matthew Wilcox
2019-06-14  3:07                         ` Dave Chinner
2019-06-14  3:07                           ` Dave Chinner
2019-06-14  3:07                           ` Dave Chinner
2019-06-20 14:52                 ` Jan Kara
2019-06-20 14:52                   ` Jan Kara
2019-06-13 20:34               ` Ira Weiny
2019-06-13 20:34                 ` Ira Weiny
2019-06-13 20:34                 ` Ira Weiny
2019-06-14  2:58                 ` Dave Chinner
2019-06-14  2:58                   ` Dave Chinner

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