From: Ira Weiny <ira.weiny@intel.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: "Theodore Ts'o" <tytso@mit.edu>,
linux-nvdimm@lists.01.org, "Dave Chinner" <david@fromorbit.com>,
"Jeff Layton" <jlayton@kernel.org>,
linux-kernel@vger.kernel.org,
"Matthew Wilcox" <willy@infradead.org>,
linux-xfs@vger.kernel.org, linux-mm@kvack.org,
"Jérôme Glisse" <jglisse@redhat.com>,
"John Hubbard" <jhubbard@nvidia.com>,
linux-fsdevel@vger.kernel.org, "Jan Kara" <jack@suse.cz>,
linux-ext4@vger.kernel.org,
"Andrew Morton" <akpm@linux-foundation.org>
Subject: Re: [PATCH RFC 00/10] RDMA/FS DAX truncate proposal
Date: Fri, 7 Jun 2019 07:52:13 -0700 [thread overview]
Message-ID: <20190607145213.GB14559@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20190607121729.GA14802@ziepe.ca>
On Fri, Jun 07, 2019 at 09:17:29AM -0300, Jason Gunthorpe wrote:
> 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?
I was contemplating some new lsof feature yesterday. But what I don't think we
want is sysadmins to have multiple tools for multiple subsystems. Or even have
to teach lsof something new for every potential new subsystem user of GUP pins.
I was thinking more along the lines of reporting files which have GUP pins on
them directly somewhere (dare I say procfs?) and teaching lsof to report that
information. That would cover any subsystem which does a longterm pin.
>
> > 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).
Agreed. I think software wise there is not much some of the devices can do
with such an "invalidate".
Ira
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next prev parent reply other threads:[~2019-06-07 14:51 UTC|newest]
Thread overview: 76+ 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 ` [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
2019-06-09 13:00 ` Jeff Layton
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 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 ` [PATCH RFC 05/10] fs/ext4: Teach ext4 to break layout leases 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 ` [PATCH RFC 07/10] fs/ext4: Fail truncate if pages are GUP pinned ira.weiny
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 ` [PATCH RFC 09/10] fs/xfs: Fail truncate if pages are GUP pinned ira.weiny
2019-06-06 1:45 ` [PATCH RFC 10/10] mm/gup: Remove FOLL_LONGTERM DAX exclusion ira.weiny
2019-06-06 5:52 ` [PATCH RFC 00/10] RDMA/FS DAX truncate proposal John Hubbard
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
2019-06-07 14:52 ` Ira Weiny [this message]
2019-06-07 15:10 ` Jason Gunthorpe
2019-06-12 10:29 ` Jan Kara
2019-06-12 11:47 ` Jason Gunthorpe
2019-06-12 12:09 ` Jan Kara
2019-06-12 18:41 ` Dan Williams
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 23:33 ` Ira Weiny
2019-06-13 1:14 ` Dan Williams
2019-06-13 15:13 ` Jason Gunthorpe
2019-06-13 16:25 ` Dan Williams
2019-06-13 17:18 ` Jason Gunthorpe
2019-06-13 16:53 ` Dan Williams
2019-06-13 15:12 ` Jason Gunthorpe
2019-06-13 7:53 ` Jan Kara
2019-06-12 18:49 ` Dan Williams
2019-06-13 7:43 ` Jan Kara
2019-06-06 22:03 ` Ira Weiny
2019-06-06 22:26 ` 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 18:50 ` Jason Gunthorpe
2019-06-08 0:10 ` Dave Chinner
2019-06-09 1:29 ` Ira Weiny
2019-06-12 12:37 ` Matthew Wilcox
2019-06-12 23:30 ` Ira Weiny
2019-06-13 0:55 ` Dave Chinner
2019-06-13 20:34 ` Ira Weiny
2019-06-14 3:42 ` Dave Chinner
2019-06-13 0:25 ` Dave Chinner
2019-06-13 3:23 ` Matthew Wilcox
2019-06-13 4:36 ` Dave Chinner
2019-06-13 10:47 ` Matthew Wilcox
2019-06-13 15:29 ` Jason Gunthorpe
2019-06-13 15:27 ` Matthew Wilcox
2019-06-13 21:13 ` Ira Weiny
2019-06-13 23:45 ` Jason Gunthorpe
2019-06-14 0:00 ` Ira Weiny
2019-06-14 2:09 ` Dave Chinner
2019-06-14 2:31 ` Matthew Wilcox
2019-06-14 3:07 ` Dave Chinner
2019-06-20 14:52 ` Jan Kara
2019-06-13 20:34 ` Ira Weiny
2019-06-14 2:58 ` Dave Chinner
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