Linux-Fsdevel Archive on lore.kernel.org
 help / color / Atom feed
WARNING: multiple messages refer to this Message-ID
From: Jerome Glisse <jglisse@redhat.com>
To: John Hubbard <jhubbard@nvidia.com>
Cc: Jan Kara <jack@suse.cz>, Matthew Wilcox <willy@infradead.org>,
	Dave Chinner <david@fromorbit.com>,
	Dan Williams <dan.j.williams@intel.com>,
	John Hubbard <john.hubbard@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux MM <linux-mm@kvack.org>,
	tom@talpey.com, Al Viro <viro@zeniv.linux.org.uk>,
	benve@cisco.com, Christoph Hellwig <hch@infradead.org>,
	Christopher Lameter <cl@linux.com>,
	"Dalessandro, Dennis" <dennis.dalessandro@intel.com>,
	Doug Ledford <dledford@redhat.com>,
	Jason Gunthorpe <jgg@ziepe.ca>, Michal Hocko <mhocko@kernel.org>,
	mike.marciniszyn@intel.com, rcampbell@nvidia.com,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 1/2] mm: introduce put_user_page*(), placeholder versions
Date: Fri, 11 Jan 2019 21:46:25 -0500
Message-ID: <20190112024625.GB5059@redhat.com> (raw)
In-Reply-To: <294bdcfa-5bf9-9c09-9d43-875e8375e264@nvidia.com>

On Fri, Jan 11, 2019 at 06:38:44PM -0800, John Hubbard wrote:
> On 1/11/19 6:02 PM, Jerome Glisse wrote:
> > On Fri, Jan 11, 2019 at 05:04:05PM -0800, John Hubbard wrote:
> >> On 1/11/19 8:51 AM, Jerome Glisse wrote:
> >>> On Thu, Jan 10, 2019 at 06:59:31PM -0800, John Hubbard wrote:
> >>>> On 1/3/19 6:44 AM, Jerome Glisse wrote:
> >>>>> On Thu, Jan 03, 2019 at 10:26:54AM +0100, Jan Kara wrote:
> >>>>>> On Wed 02-01-19 20:55:33, Jerome Glisse wrote:
> >>>>>>> On Wed, Dec 19, 2018 at 12:08:56PM +0100, Jan Kara wrote:
> >>>>>>>> On Tue 18-12-18 21:07:24, Jerome Glisse wrote:
> >>>>>>>>> On Tue, Dec 18, 2018 at 03:29:34PM -0800, John Hubbard wrote:
> >>> [...]
> >>
> >> Hi Jerome,
> >>
> >> Looks good, in a conceptual sense. Let me do a brain dump of how I see it,
> >> in case anyone spots a disastrous conceptual error (such as the lock_page
> >> point), while I'm putting together the revised patchset.
> >>
> >> I've studied this carefully, and I agree that using mapcount in 
> >> this way is viable, *as long* as we use a lock (or a construct that looks just 
> >> like one: your "memory barrier, check, retry" is really just a lock) in
> >> order to hold off gup() while page_mkclean() is in progress. In other words,
> >> nothing that increments mapcount may proceed while page_mkclean() is running.
> > 
> > No, increment to page->_mapcount are fine while page_mkclean() is running.
> > The above solution do work no matter what happens thanks to the memory
> > barrier. By clearing the pin flag first and reading the page->_mapcount
> > after (and doing the reverse in GUP) we know that a racing GUP will either
> > have its pin page clear but the incremented mapcount taken into account by
> > page_mkclean() or page_mkclean() will miss the incremented mapcount but
> > it will also no clear the pin flag set concurrently by any GUP.
> > 
> > Here are all the possible time line:
> > [T1]:
> > GUP on CPU0                      | page_mkclean() on CPU1
> >                                  |
> > [G2] atomic_inc(&page->mapcount) |
> > [G3] smp_wmb();                  |
> > [G4] SetPagePin(page);           |
> >                                 ...
> >                                  | [C1] pined = TestClearPagePin(page);
> 
> It appears that you're using the "page pin is clear" to indicate that
> page_mkclean() is running. The problem is, that approach leads to toggling
> the PagePin flag, and so an observer (other than gup or page_mkclean) will
> see intervals during which the PagePin flag is clear, when conceptually it
> should be set.
> 
> Jan and other FS people, is it definitely the case that we only have to take
> action (defer, wait, revoke, etc) for gup-pinned pages, in page_mkclean()?
> Because I recall from earlier experiments that there were several places, not 
> just page_mkclean().

Yes and it is fine to temporarily have the pin flag unstable. Anything
that need stable page content will have to lock the page so will have
to sync against any page_mkclean() and in the end the only thing were
we want to check the pin flag is when doing write back ie after
page_mkclean() while the page is still locked. If they are any other
place that need to check the pin flag then they will need to lock the
page. But i can not think of any other place right now.


[...]

> >> The other idea that you and Dan (and maybe others) pointed out was a debug
> >> option, which we'll certainly need in order to safely convert all the call
> >> sites. (Mirror the mappings at a different kernel offset, so that put_page()
> >> and put_user_page() can verify that the right call was made.)  That will be
> >> a separate patchset, as you recommended.
> >>
> >> I'll even go as far as recommending the page lock itself. I realize that this 
> >> adds overhead to gup(), but we *must* hold off page_mkclean(), and I believe
> >> that this (below) has similar overhead to the notes above--but is *much* easier
> >> to verify correct. (If the page lock is unacceptable due to being so widely used,
> >> then I'd recommend using another page bit to do the same thing.)
> > 
> > Please page lock is pointless and it will not work for GUP fast. The above
> > scheme do work and is fine. I spend the day again thinking about all memory
> > ordering and i do not see any issues.
> > 
> 
> Why is it that page lock cannot be used for gup fast, btw?

Well it can not happen within the preempt disable section. But after
as a post pass before GUP_fast return and after reenabling preempt then
it is fine like it would be for regular GUP. But locking page for GUP
is also likely to slow down some workload (with direct-IO).

Cheers,
Jérôme

From: Jerome Glisse <jglisse@redhat.com>
To: John Hubbard <jhubbard@nvidia.com>
Cc: Jan Kara <jack@suse.cz>, Matthew Wilcox <willy@infradead.org>,
	Dave Chinner <david@fromorbit.com>,
	Dan Williams <dan.j.williams@intel.com>,
	John Hubbard <john.hubbard@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux MM <linux-mm@kvack.org>,
	tom@talpey.com, Al Viro <viro@zeniv.linux.org.uk>,
	benve@cisco.com, Christoph Hellwig <hch@infradead.org>,
	Christopher Lameter <cl@linux.com>,
	"Dalessandro, Dennis" <dennis.dalessandro@intel.com>,
	Doug Ledford <dledford@redhat.com>,
	Jason Gunthorpe <jgg@ziepe.ca>, Michal Hocko <mhocko@kernel.org>,
	mike.marciniszyn@intel.com, rcampbell@nvidia.com,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 1/2] mm: introduce put_user_page*(), placeholder versions
Date: Fri, 11 Jan 2019 21:46:25 -0500
Message-ID: <20190112024625.GB5059@redhat.com> (raw)
Message-ID: <20190112024625.8PyJrKcGih7bom3fPBHgatWbWv9Cbskm9s5j0fSL3f8@z> (raw)
In-Reply-To: <294bdcfa-5bf9-9c09-9d43-875e8375e264@nvidia.com>

On Fri, Jan 11, 2019 at 06:38:44PM -0800, John Hubbard wrote:
> On 1/11/19 6:02 PM, Jerome Glisse wrote:
> > On Fri, Jan 11, 2019 at 05:04:05PM -0800, John Hubbard wrote:
> >> On 1/11/19 8:51 AM, Jerome Glisse wrote:
> >>> On Thu, Jan 10, 2019 at 06:59:31PM -0800, John Hubbard wrote:
> >>>> On 1/3/19 6:44 AM, Jerome Glisse wrote:
> >>>>> On Thu, Jan 03, 2019 at 10:26:54AM +0100, Jan Kara wrote:
> >>>>>> On Wed 02-01-19 20:55:33, Jerome Glisse wrote:
> >>>>>>> On Wed, Dec 19, 2018 at 12:08:56PM +0100, Jan Kara wrote:
> >>>>>>>> On Tue 18-12-18 21:07:24, Jerome Glisse wrote:
> >>>>>>>>> On Tue, Dec 18, 2018 at 03:29:34PM -0800, John Hubbard wrote:
> >>> [...]
> >>
> >> Hi Jerome,
> >>
> >> Looks good, in a conceptual sense. Let me do a brain dump of how I see it,
> >> in case anyone spots a disastrous conceptual error (such as the lock_page
> >> point), while I'm putting together the revised patchset.
> >>
> >> I've studied this carefully, and I agree that using mapcount in 
> >> this way is viable, *as long* as we use a lock (or a construct that looks just 
> >> like one: your "memory barrier, check, retry" is really just a lock) in
> >> order to hold off gup() while page_mkclean() is in progress. In other words,
> >> nothing that increments mapcount may proceed while page_mkclean() is running.
> > 
> > No, increment to page->_mapcount are fine while page_mkclean() is running.
> > The above solution do work no matter what happens thanks to the memory
> > barrier. By clearing the pin flag first and reading the page->_mapcount
> > after (and doing the reverse in GUP) we know that a racing GUP will either
> > have its pin page clear but the incremented mapcount taken into account by
> > page_mkclean() or page_mkclean() will miss the incremented mapcount but
> > it will also no clear the pin flag set concurrently by any GUP.
> > 
> > Here are all the possible time line:
> > [T1]:
> > GUP on CPU0                      | page_mkclean() on CPU1
> >                                  |
> > [G2] atomic_inc(&page->mapcount) |
> > [G3] smp_wmb();                  |
> > [G4] SetPagePin(page);           |
> >                                 ...
> >                                  | [C1] pined = TestClearPagePin(page);
> 
> It appears that you're using the "page pin is clear" to indicate that
> page_mkclean() is running. The problem is, that approach leads to toggling
> the PagePin flag, and so an observer (other than gup or page_mkclean) will
> see intervals during which the PagePin flag is clear, when conceptually it
> should be set.
> 
> Jan and other FS people, is it definitely the case that we only have to take
> action (defer, wait, revoke, etc) for gup-pinned pages, in page_mkclean()?
> Because I recall from earlier experiments that there were several places, not 
> just page_mkclean().

Yes and it is fine to temporarily have the pin flag unstable. Anything
that need stable page content will have to lock the page so will have
to sync against any page_mkclean() and in the end the only thing were
we want to check the pin flag is when doing write back ie after
page_mkclean() while the page is still locked. If they are any other
place that need to check the pin flag then they will need to lock the
page. But i can not think of any other place right now.


[...]

> >> The other idea that you and Dan (and maybe others) pointed out was a debug
> >> option, which we'll certainly need in order to safely convert all the call
> >> sites. (Mirror the mappings at a different kernel offset, so that put_page()
> >> and put_user_page() can verify that the right call was made.)  That will be
> >> a separate patchset, as you recommended.
> >>
> >> I'll even go as far as recommending the page lock itself. I realize that this 
> >> adds overhead to gup(), but we *must* hold off page_mkclean(), and I believe
> >> that this (below) has similar overhead to the notes above--but is *much* easier
> >> to verify correct. (If the page lock is unacceptable due to being so widely used,
> >> then I'd recommend using another page bit to do the same thing.)
> > 
> > Please page lock is pointless and it will not work for GUP fast. The above
> > scheme do work and is fine. I spend the day again thinking about all memory
> > ordering and i do not see any issues.
> > 
> 
> Why is it that page lock cannot be used for gup fast, btw?

Well it can not happen within the preempt disable section. But after
as a post pass before GUP_fast return and after reenabling preempt then
it is fine like it would be for regular GUP. But locking page for GUP
is also likely to slow down some workload (with direct-IO).

Cheers,
Jérôme

  parent reply index

Thread overview: 213+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-04  0:17 [PATCH 0/2] put_user_page*(): start converting the call sites john.hubbard
2018-12-04  0:17 ` [PATCH 1/2] mm: introduce put_user_page*(), placeholder versions john.hubbard
2018-12-04  7:53   ` Mike Rapoport
2018-12-05  1:40     ` John Hubbard
2018-12-04 20:28   ` Dan Williams
2018-12-04 21:56     ` John Hubbard
2018-12-04 23:03       ` Dan Williams
2018-12-05  0:36         ` Jerome Glisse
2018-12-05  0:40           ` Dan Williams
2018-12-05  0:59             ` John Hubbard
2018-12-05  0:58         ` John Hubbard
2018-12-05  1:00           ` Dan Williams
2018-12-05  1:15           ` Matthew Wilcox
2018-12-05  1:44             ` Jerome Glisse
2018-12-05  1:57               ` John Hubbard
2018-12-07  2:45                 ` John Hubbard
2018-12-07 19:16                   ` Jerome Glisse
2018-12-07 19:26                     ` Dan Williams
2018-12-07 19:40                       ` Jerome Glisse
2018-12-08  0:52                     ` John Hubbard
2018-12-08  2:24                       ` Jerome Glisse
2018-12-10 10:28                         ` Jan Kara
2018-12-12 15:03                           ` Jerome Glisse
2018-12-12 16:27                             ` Dan Williams
2018-12-12 17:02                               ` Jerome Glisse
2018-12-12 17:49                                 ` Dan Williams
2018-12-12 19:07                                   ` John Hubbard
2018-12-12 21:30                               ` Jerome Glisse
2018-12-12 21:40                                 ` Dan Williams
2018-12-12 21:53                                   ` Jerome Glisse
2018-12-12 22:11                                     ` Matthew Wilcox
2018-12-12 22:16                                       ` Jerome Glisse
2018-12-12 23:37                                     ` Jason Gunthorpe
2018-12-12 23:46                                       ` John Hubbard
2018-12-12 23:54                                       ` Dan Williams
2018-12-13  0:01                                       ` Jerome Glisse
2018-12-13  0:18                                         ` Dan Williams
2018-12-13  0:44                                           ` Jerome Glisse
2018-12-13  3:26                                             ` Jason Gunthorpe
2018-12-13  3:20                                         ` Jason Gunthorpe
2018-12-13 12:43                                           ` Jerome Glisse
2018-12-13 13:40                                             ` Tom Talpey
2018-12-13 14:18                                               ` Jerome Glisse
2018-12-13 14:51                                                 ` Tom Talpey
2018-12-13 15:18                                                   ` Jerome Glisse
2018-12-13 18:12                                                     ` Tom Talpey
2018-12-13 19:18                                                       ` Jerome Glisse
2018-12-14 10:41                                             ` Jan Kara
2018-12-14 15:25                                               ` Jerome Glisse
2018-12-12 21:56                                 ` John Hubbard
2018-12-12 22:04                                   ` Jerome Glisse
2018-12-12 22:11                                     ` John Hubbard
2018-12-12 22:14                                       ` Jerome Glisse
2018-12-12 22:17                                         ` John Hubbard
2018-12-12 21:46                             ` Dave Chinner
2018-12-12 21:59                               ` Jerome Glisse
2018-12-13  0:51                                 ` Dave Chinner
2018-12-13  2:02                                   ` Jerome Glisse
2018-12-13 15:56                                     ` Christopher Lameter
2018-12-13 16:02                                       ` Jerome Glisse
2018-12-14  6:00                                     ` Dave Chinner
2018-12-14 15:13                                       ` Jerome Glisse
2018-12-14  3:52                                   ` John Hubbard
2018-12-14  5:21                                     ` Dan Williams
2018-12-14  6:11                                       ` John Hubbard
2018-12-14 15:20                                         ` Jerome Glisse
2018-12-14 19:38                                         ` Dan Williams
2018-12-14 19:48                                           ` Matthew Wilcox
2018-12-14 19:53                                             ` Dave Hansen
2018-12-14 20:03                                               ` Matthew Wilcox
2018-12-14 20:17                                                 ` Dan Williams
2018-12-14 20:29                                                   ` Matthew Wilcox
2018-12-15  0:41                                                 ` John Hubbard
2018-12-17  8:56                                           ` Jan Kara
2018-12-17 18:28                                             ` Dan Williams
2018-12-14 15:43                               ` Jan Kara
2018-12-16 21:58                                 ` Dave Chinner
2018-12-17 18:11                                   ` Jerome Glisse
2018-12-17 18:34                                     ` Matthew Wilcox
2018-12-17 19:48                                       ` Jerome Glisse
2018-12-17 19:51                                         ` Matthew Wilcox
2018-12-17 19:54                                           ` Jerome Glisse
2018-12-17 19:59                                             ` Matthew Wilcox
2018-12-17 20:55                                               ` Jerome Glisse
2018-12-17 21:03                                                 ` Matthew Wilcox
2018-12-17 21:15                                                   ` Jerome Glisse
2018-12-18  1:09                                       ` Dave Chinner
2018-12-18  6:12                                       ` Darrick J. Wong
2018-12-18  9:30                                       ` Jan Kara
2018-12-18 23:29                                         ` John Hubbard
2018-12-19  2:07                                           ` Jerome Glisse
2018-12-19 11:08                                             ` Jan Kara
2018-12-20 10:54                                               ` John Hubbard
2018-12-20 16:50                                                 ` Jerome Glisse
2018-12-20 16:57                                                   ` Dan Williams
2018-12-20 16:49                                               ` Jerome Glisse
2019-01-03  1:55                                               ` Jerome Glisse
2019-01-03  3:27                                                 ` John Hubbard
2019-01-03 14:57                                                   ` Jerome Glisse
2019-01-03  9:26                                                 ` Jan Kara
2019-01-03 14:44                                                   ` Jerome Glisse
2019-01-11  2:59                                                     ` John Hubbard
2019-01-11  2:59                                                       ` John Hubbard
2019-01-11 16:51                                                       ` Jerome Glisse
2019-01-11 16:51                                                         ` Jerome Glisse
2019-01-12  1:04                                                         ` John Hubbard
2019-01-12  1:04                                                           ` John Hubbard
2019-01-12  2:02                                                           ` Jerome Glisse
2019-01-12  2:02                                                             ` Jerome Glisse
2019-01-12  2:38                                                             ` John Hubbard
2019-01-12  2:38                                                               ` John Hubbard
2019-01-12  2:46                                                               ` Jerome Glisse [this message]
2019-01-12  2:46                                                                 ` Jerome Glisse
2019-01-12  3:06                                                                 ` John Hubbard
2019-01-12  3:06                                                                   ` John Hubbard
2019-01-12  3:25                                                                   ` Jerome Glisse
2019-01-12  3:25                                                                     ` Jerome Glisse
2019-01-12 20:46                                                                     ` John Hubbard
2019-01-12 20:46                                                                       ` John Hubbard
2019-01-14 14:54                                                                   ` Jan Kara
2019-01-14 14:54                                                                     ` Jan Kara
2019-01-14 17:21                                                                     ` Jerome Glisse
2019-01-14 17:21                                                                       ` Jerome Glisse
2019-01-14 19:09                                                                       ` John Hubbard
2019-01-14 19:09                                                                         ` John Hubbard
2019-01-15  8:34                                                                         ` Jan Kara
2019-01-15  8:34                                                                           ` Jan Kara
2019-01-15 21:39                                                                           ` John Hubbard
2019-01-15 21:39                                                                             ` John Hubbard
2019-01-15  8:07                                                                       ` Jan Kara
2019-01-15  8:07                                                                         ` Jan Kara
2019-01-15 17:15                                                                         ` Jerome Glisse
2019-01-15 17:15                                                                           ` Jerome Glisse
2019-01-15 21:56                                                                           ` John Hubbard
2019-01-15 21:56                                                                             ` John Hubbard
2019-01-15 22:12                                                                             ` Jerome Glisse
2019-01-15 22:12                                                                               ` Jerome Glisse
2019-01-16  0:44                                                                               ` John Hubbard
2019-01-16  0:44                                                                                 ` John Hubbard
2019-01-16  1:56                                                                                 ` Jerome Glisse
2019-01-16  1:56                                                                                   ` Jerome Glisse
2019-01-16  2:01                                                                                   ` Dan Williams
2019-01-16  2:01                                                                                     ` Dan Williams
2019-01-16  2:23                                                                                     ` Jerome Glisse
2019-01-16  2:23                                                                                       ` Jerome Glisse
2019-01-16  4:34                                                                                       ` Dave Chinner
2019-01-16  4:34                                                                                         ` Dave Chinner
2019-01-16 14:50                                                                                         ` Jerome Glisse
2019-01-16 14:50                                                                                           ` Jerome Glisse
2019-01-16 22:51                                                                                           ` Dave Chinner
2019-01-16 22:51                                                                                             ` Dave Chinner
2019-01-16 11:38                                                                         ` Jan Kara
2019-01-16 11:38                                                                           ` Jan Kara
2019-01-16 13:08                                                                           ` Jerome Glisse
2019-01-16 13:08                                                                             ` Jerome Glisse
2019-01-17  5:42                                                                             ` John Hubbard
2019-01-17  5:42                                                                               ` John Hubbard
2019-01-17 15:21                                                                               ` Jerome Glisse
2019-01-17 15:21                                                                                 ` Jerome Glisse
2019-01-18  0:16                                                                                 ` Dave Chinner
2019-01-18  1:59                                                                                   ` Jerome Glisse
2019-01-17  9:30                                                                             ` Jan Kara
2019-01-17  9:30                                                                               ` Jan Kara
2019-01-17 15:17                                                                               ` Jerome Glisse
2019-01-17 15:17                                                                                 ` Jerome Glisse
2019-01-22 15:24                                                                                 ` Jan Kara
2019-01-22 16:46                                                                                   ` Jerome Glisse
2019-01-23 18:02                                                                                     ` Jan Kara
2019-01-23 19:04                                                                                       ` Jerome Glisse
2019-01-29  0:22                                                                                         ` John Hubbard
2019-01-29  1:23                                                                                           ` Jerome Glisse
2019-01-29  6:41                                                                                             ` John Hubbard
2019-01-29 10:12                                                                                               ` Jan Kara
2019-01-30  2:21                                                                                                 ` John Hubbard
2019-01-17  5:25                                                                         ` John Hubbard
2019-01-17  5:25                                                                           ` John Hubbard
2019-01-17  9:04                                                                           ` Jan Kara
2019-01-17  9:04                                                                             ` Jan Kara
2019-01-12  3:14                                                               ` Jerome Glisse
2019-01-12  3:14                                                                 ` Jerome Glisse
2018-12-18 10:33                                   ` Jan Kara
2018-12-18 23:42                                     ` Dave Chinner
2018-12-19  3:03                                       ` Jason Gunthorpe
2018-12-19  5:26                                         ` Dan Williams
2018-12-19 11:19                                           ` Jan Kara
2018-12-19 10:28                                         ` Dave Chinner
2018-12-19 11:35                                           ` Jan Kara
2018-12-19 16:56                                             ` Jason Gunthorpe
2018-12-19 22:33                                             ` Dave Chinner
2018-12-20  9:07                                               ` Jan Kara
2018-12-20 16:54                                               ` Jerome Glisse
2018-12-19 13:24                                       ` Jan Kara
2018-12-08  5:18                       ` Matthew Wilcox
2018-12-12 19:13                         ` John Hubbard
2018-12-08  7:16                       ` Dan Williams
2018-12-08 16:33                         ` Jerome Glisse
2018-12-08 16:48                           ` Christoph Hellwig
2018-12-08 17:47                             ` Jerome Glisse
2018-12-08 18:26                               ` Christoph Hellwig
2018-12-08 18:45                                 ` Jerome Glisse
2018-12-08 18:09                             ` Dan Williams
2018-12-08 18:12                               ` Christoph Hellwig
2018-12-11  6:18                               ` Dave Chinner
2018-12-05  5:52             ` Dan Williams
2018-12-05 11:16       ` Jan Kara
2018-12-04  0:17 ` [PATCH 2/2] infiniband/mm: convert put_page() to put_user_page*() john.hubbard
2018-12-04 17:10 ` [PATCH 0/2] put_user_page*(): start converting the call sites David Laight
2018-12-05  1:05   ` John Hubbard
2018-12-05 14:08     ` David Laight
2018-12-28  8:37       ` Pavel Machek
2019-02-08  7:56 [PATCH 0/2] mm: put_user_page() call site conversion first john.hubbard
2019-02-08  7:56 ` [PATCH 1/2] mm: introduce put_user_page*(), placeholder versions john.hubbard
2019-02-08 10:32   ` Mike Rapoport
2019-02-08 20:44     ` John Hubbard

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190112024625.GB5059@redhat.com \
    --to=jglisse@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=benve@cisco.com \
    --cc=cl@linux.com \
    --cc=dan.j.williams@intel.com \
    --cc=david@fromorbit.com \
    --cc=dennis.dalessandro@intel.com \
    --cc=dledford@redhat.com \
    --cc=hch@infradead.org \
    --cc=jack@suse.cz \
    --cc=jgg@ziepe.ca \
    --cc=jhubbard@nvidia.com \
    --cc=john.hubbard@gmail.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@kernel.org \
    --cc=mike.marciniszyn@intel.com \
    --cc=rcampbell@nvidia.com \
    --cc=tom@talpey.com \
    --cc=viro@zeniv.linux.org.uk \
    --cc=willy@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Fsdevel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-fsdevel/0 linux-fsdevel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-fsdevel linux-fsdevel/ https://lore.kernel.org/linux-fsdevel \
		linux-fsdevel@vger.kernel.org linux-fsdevel@archiver.kernel.org
	public-inbox-index linux-fsdevel


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-fsdevel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox