From: John Hubbard <jhubbard@nvidia.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: "Jerome Glisse" <jglisse@redhat.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Alex Williamson" <alex.williamson@redhat.com>,
"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
"Björn Töpel" <bjorn.topel@intel.com>,
"Christoph Hellwig" <hch@infradead.org>,
"Dan Williams" <dan.j.williams@intel.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Dave Chinner" <david@fromorbit.com>,
"David Airlie" <airlied@linux.ie>,
"David S . Miller" <davem@davemloft.net>,
"Ira Weiny" <ira.weiny@intel.com>, "Jan Kara" <jack@suse.cz>,
"Jens Axboe" <axboe@kernel.dk>,
"Jonathan Corbet" <corbet@lwn.net>,
"Magnus Karlsson" <magnus.karlsson@intel.com>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Michael Ellerman" <mpe@ellerman.id.au>,
"Michal Hocko" <mhocko@suse.com>,
"Mike Kravetz" <mike.kravetz@oracle.com>,
"Paul Mackerras" <paulus@samba.org>,
"Shuah Khan" <shuah@kernel.org>,
"Vlastimil Babka" <vbabka@suse.cz>,
bpf@vger.kernel.org, dri-devel@lists.freedesktop.org,
kvm@vger.kernel.org, linux-block@vger.kernel.org,
linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-media@vger.kernel.org,
linux-rdma@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
netdev@vger.kernel.org, linux-mm@kvack.org,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 05/18] mm/gup: introduce pin_user_pages*() and FOLL_PIN
Date: Mon, 4 Nov 2019 13:34:04 -0800 [thread overview]
Message-ID: <caaaaf52-490b-6ce1-81d8-675013354c73@nvidia.com> (raw)
In-Reply-To: <20191104211525.GJ30938@ziepe.ca>
On 11/4/19 1:15 PM, Jason Gunthorpe wrote:
...
>> Right, and I thought about this when converting, and realized that the above
>> code is working around the current gup.c limitations, which are "cannot support
>> gup remote with FOLL_LONGTERM".
>
> But AFAICT it doesn't have a problem, the protection test is just too
> strict, and I guess the control flow needs a bit of fixing..
>
> The issue is this:
>
> static __always_inline long __get_user_pages_locked():
> {
> if (locked) {
> /* if VM_FAULT_RETRY can be returned, vmas become invalid */
> BUG_ON(vmas);
> /* check caller initialized locked */
> BUG_ON(*locked != 1);
> }
>
>
> so remote could be written as:
>
> if (gup_flags & FOLL_LONGTERM) {
> if (WARN_ON_ONCE(locked))
> return -EINVAL;
> return __gup_longterm_locked(...)
> }
>
> return __get_user_pages_locked(...)
>
> ??
Yes, that loosens it up just enough for the vfio case (which doesn't set
"locked") to get through, great! OK, I'll put that (the above plus
corresponding vfio fix) in a separate patch first.
This should clear things up nicely.
thanks,
--
John Hubbard
NVIDIA
WARNING: multiple messages have this Message-ID (diff)
From: John Hubbard <jhubbard@nvidia.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: "Michal Hocko" <mhocko@suse.com>, "Jan Kara" <jack@suse.cz>,
kvm@vger.kernel.org, linux-doc@vger.kernel.org,
"David Airlie" <airlied@linux.ie>,
"Dave Chinner" <david@fromorbit.com>,
dri-devel@lists.freedesktop.org,
LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, "Paul Mackerras" <paulus@samba.org>,
linux-kselftest@vger.kernel.org,
"Ira Weiny" <ira.weiny@intel.com>,
"Jonathan Corbet" <corbet@lwn.net>,
linux-rdma@vger.kernel.org,
"Christoph Hellwig" <hch@infradead.org>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Björn Töpel" <bjorn.topel@intel.com>,
linux-media@vger.kernel.org, "Shuah Khan" <shuah@kernel.org>,
linux-block@vger.kernel.org,
"Alex Williamson" <alex.williamson@redhat.com>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Dan Williams" <dan.j.williams@intel.com>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
bpf@vger.kernel.org,
"Magnus Karlsson" <magnus.karlsson@intel.com>,
"Jens Axboe" <axboe@kernel.dk>,
netdev@vger.kernel.org, "Jerome Glisse" <jglisse@redhat.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
linux-fsdevel@vger.kernel.org,
"Andrew Morton" <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org,
"David S . Miller" <davem@davemloft.net>,
"Mike Kravetz" <mike.kravetz@oracle.com>
Subject: Re: [PATCH v2 05/18] mm/gup: introduce pin_user_pages*() and FOLL_PIN
Date: Mon, 4 Nov 2019 13:34:04 -0800 [thread overview]
Message-ID: <caaaaf52-490b-6ce1-81d8-675013354c73@nvidia.com> (raw)
In-Reply-To: <20191104211525.GJ30938@ziepe.ca>
On 11/4/19 1:15 PM, Jason Gunthorpe wrote:
...
>> Right, and I thought about this when converting, and realized that the above
>> code is working around the current gup.c limitations, which are "cannot support
>> gup remote with FOLL_LONGTERM".
>
> But AFAICT it doesn't have a problem, the protection test is just too
> strict, and I guess the control flow needs a bit of fixing..
>
> The issue is this:
>
> static __always_inline long __get_user_pages_locked():
> {
> if (locked) {
> /* if VM_FAULT_RETRY can be returned, vmas become invalid */
> BUG_ON(vmas);
> /* check caller initialized locked */
> BUG_ON(*locked != 1);
> }
>
>
> so remote could be written as:
>
> if (gup_flags & FOLL_LONGTERM) {
> if (WARN_ON_ONCE(locked))
> return -EINVAL;
> return __gup_longterm_locked(...)
> }
>
> return __get_user_pages_locked(...)
>
> ??
Yes, that loosens it up just enough for the vfio case (which doesn't set
"locked") to get through, great! OK, I'll put that (the above plus
corresponding vfio fix) in a separate patch first.
This should clear things up nicely.
thanks,
--
John Hubbard
NVIDIA
WARNING: multiple messages have this Message-ID (diff)
From: John Hubbard <jhubbard@nvidia.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: "Jerome Glisse" <jglisse@redhat.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Alex Williamson" <alex.williamson@redhat.com>,
"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
"Björn Töpel" <bjorn.topel@intel.com>,
"Christoph Hellwig" <hch@infradead.org>,
"Dan Williams" <dan.j.williams@intel.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Dave Chinner" <david@fromorbit.com>,
"David Airlie" <airlied@linux.ie>,
"David S . Miller" <davem@davemloft.net>,
"Ira Weiny" <ira.weiny@intel.com>, "Jan Kara" <jack@suse.cz>,
"Jens Axboe" <axboe@kernel.dk>,
"Jonathan Corbet" <corbet@lwn.net>,
"Magnus Karlsson" <magnus.karlsson@intel.com>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Michael Ellerman" <mpe@ellerman.id.au>
Subject: Re: [PATCH v2 05/18] mm/gup: introduce pin_user_pages*() and FOLL_PIN
Date: Mon, 4 Nov 2019 13:34:04 -0800 [thread overview]
Message-ID: <caaaaf52-490b-6ce1-81d8-675013354c73@nvidia.com> (raw)
In-Reply-To: <20191104211525.GJ30938@ziepe.ca>
On 11/4/19 1:15 PM, Jason Gunthorpe wrote:
...
>> Right, and I thought about this when converting, and realized that the above
>> code is working around the current gup.c limitations, which are "cannot support
>> gup remote with FOLL_LONGTERM".
>
> But AFAICT it doesn't have a problem, the protection test is just too
> strict, and I guess the control flow needs a bit of fixing..
>
> The issue is this:
>
> static __always_inline long __get_user_pages_locked():
> {
> if (locked) {
> /* if VM_FAULT_RETRY can be returned, vmas become invalid */
> BUG_ON(vmas);
> /* check caller initialized locked */
> BUG_ON(*locked != 1);
> }
>
>
> so remote could be written as:
>
> if (gup_flags & FOLL_LONGTERM) {
> if (WARN_ON_ONCE(locked))
> return -EINVAL;
> return __gup_longterm_locked(...)
> }
>
> return __get_user_pages_locked(...)
>
> ??
Yes, that loosens it up just enough for the vfio case (which doesn't set
"locked") to get through, great! OK, I'll put that (the above plus
corresponding vfio fix) in a separate patch first.
This should clear things up nicely.
thanks,
--
John Hubbard
NVIDIA
next prev parent reply other threads:[~2019-11-04 21:34 UTC|newest]
Thread overview: 197+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-03 21:17 [PATCH v2 00/18] mm/gup: track dma-pinned pages: FOLL_PIN, FOLL_LONGTERM John Hubbard
2019-11-03 21:17 ` John Hubbard
2019-11-03 21:17 ` John Hubbard
2019-11-03 21:17 ` [PATCH v2 01/18] mm/gup: pass flags arg to __gup_device_* functions John Hubbard
2019-11-03 21:17 ` John Hubbard
2019-11-03 21:17 ` John Hubbard
2019-11-04 16:39 ` Jerome Glisse
2019-11-04 16:39 ` Jerome Glisse
2019-11-04 16:39 ` Jerome Glisse
2019-11-04 16:39 ` Jerome Glisse
2019-11-03 21:17 ` [PATCH v2 02/18] mm/gup: factor out duplicate code from four routines John Hubbard
2019-11-03 21:17 ` John Hubbard
2019-11-03 21:17 ` John Hubbard
2019-11-04 16:51 ` Jerome Glisse
2019-11-04 16:51 ` Jerome Glisse
2019-11-04 16:51 ` Jerome Glisse
2019-11-04 16:51 ` Jerome Glisse
2019-11-03 21:17 ` [PATCH v2 03/18] goldish_pipe: rename local pin_user_pages() routine John Hubbard
2019-11-03 21:17 ` John Hubbard
2019-11-03 21:17 ` John Hubbard
2019-11-03 21:17 ` John Hubbard
2019-11-04 16:52 ` Jerome Glisse
2019-11-04 16:52 ` Jerome Glisse
2019-11-04 16:52 ` Jerome Glisse
2019-11-04 16:52 ` Jerome Glisse
2019-11-03 21:17 ` [PATCH v2 04/18] media/v4l2-core: set pages dirty upon releasing DMA buffers John Hubbard
2019-11-03 21:17 ` John Hubbard
2019-11-03 21:17 ` John Hubbard
2019-11-10 10:10 ` Hans Verkuil
2019-11-10 10:10 ` Hans Verkuil
2019-11-10 10:10 ` Hans Verkuil
2019-11-10 10:10 ` Hans Verkuil
2019-11-11 21:46 ` John Hubbard
2019-11-11 21:46 ` John Hubbard
2019-11-11 21:46 ` John Hubbard
2019-11-11 21:46 ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 05/18] mm/gup: introduce pin_user_pages*() and FOLL_PIN John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-04 17:33 ` Jerome Glisse
2019-11-04 17:33 ` Jerome Glisse
2019-11-04 17:33 ` Jerome Glisse
2019-11-04 17:33 ` Jerome Glisse
2019-11-04 19:04 ` John Hubbard
2019-11-04 19:04 ` John Hubbard
2019-11-04 19:04 ` John Hubbard
2019-11-04 19:04 ` John Hubbard
2019-11-04 19:18 ` Jerome Glisse
2019-11-04 19:18 ` Jerome Glisse
2019-11-04 19:18 ` Jerome Glisse
2019-11-04 19:18 ` Jerome Glisse
2019-11-04 19:30 ` John Hubbard
2019-11-04 19:30 ` John Hubbard
2019-11-04 19:30 ` John Hubbard
2019-11-04 19:30 ` John Hubbard
2019-11-04 19:52 ` Jerome Glisse
2019-11-04 19:52 ` Jerome Glisse
2019-11-04 19:52 ` Jerome Glisse
2019-11-04 19:52 ` Jerome Glisse
2019-11-04 20:09 ` John Hubbard
2019-11-04 20:09 ` John Hubbard
2019-11-04 20:09 ` John Hubbard
2019-11-04 20:31 ` Jason Gunthorpe
2019-11-04 20:31 ` Jason Gunthorpe
2019-11-04 20:31 ` Jason Gunthorpe
2019-11-04 20:40 ` John Hubbard
2019-11-04 20:40 ` John Hubbard
2019-11-04 20:40 ` John Hubbard
2019-11-04 20:31 ` Jerome Glisse
2019-11-04 20:31 ` Jerome Glisse
2019-11-04 20:31 ` Jerome Glisse
2019-11-04 20:31 ` Jerome Glisse
2019-11-04 20:37 ` Jason Gunthorpe
2019-11-04 20:37 ` Jason Gunthorpe
2019-11-04 20:37 ` Jason Gunthorpe
2019-11-04 20:57 ` John Hubbard
2019-11-04 20:57 ` John Hubbard
2019-11-04 20:57 ` John Hubbard
2019-11-04 21:15 ` Jason Gunthorpe
2019-11-04 21:15 ` Jason Gunthorpe
2019-11-04 21:15 ` Jason Gunthorpe
2019-11-04 21:34 ` John Hubbard [this message]
2019-11-04 21:34 ` John Hubbard
2019-11-04 21:34 ` John Hubbard
2019-11-04 20:33 ` David Rientjes
2019-11-04 20:33 ` David Rientjes
2019-11-04 20:33 ` David Rientjes
2019-11-04 20:33 ` David Rientjes
2019-11-04 20:48 ` Jerome Glisse
2019-11-04 20:48 ` Jerome Glisse
2019-11-04 20:48 ` Jerome Glisse
2019-11-04 20:48 ` Jerome Glisse
2019-11-05 13:10 ` Mike Rapoport
2019-11-05 13:10 ` Mike Rapoport
2019-11-05 13:10 ` Mike Rapoport
2019-11-05 13:10 ` Mike Rapoport
2019-11-05 19:00 ` John Hubbard
2019-11-05 19:00 ` John Hubbard
2019-11-05 19:00 ` John Hubbard
2019-11-05 19:00 ` John Hubbard
2019-11-07 2:25 ` Ira Weiny
2019-11-07 2:25 ` Ira Weiny
2019-11-07 2:25 ` Ira Weiny
2019-11-07 2:25 ` Ira Weiny
2019-11-07 8:07 ` Mike Rapoport
2019-11-07 8:07 ` Mike Rapoport
2019-11-07 8:07 ` Mike Rapoport
2019-11-07 8:07 ` Mike Rapoport
2019-11-03 21:18 ` [PATCH v2 06/18] goldish_pipe: convert to pin_user_pages() and put_user_page() John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 07/18] infiniband: set FOLL_PIN, FOLL_LONGTERM via pin_longterm_pages*() John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-04 20:33 ` Jason Gunthorpe
2019-11-04 20:33 ` Jason Gunthorpe
2019-11-04 20:33 ` Jason Gunthorpe
2019-11-04 20:48 ` John Hubbard
2019-11-04 20:48 ` John Hubbard
2019-11-04 20:48 ` John Hubbard
2019-11-04 20:57 ` Jason Gunthorpe
2019-11-04 20:57 ` Jason Gunthorpe
2019-11-04 20:57 ` Jason Gunthorpe
2019-11-04 22:03 ` John Hubbard
2019-11-04 22:03 ` John Hubbard
2019-11-04 22:03 ` John Hubbard
2019-11-05 2:32 ` Jason Gunthorpe
2019-11-05 2:32 ` Jason Gunthorpe
2019-11-05 2:32 ` Jason Gunthorpe
2019-11-07 2:26 ` Ira Weiny
2019-11-07 2:26 ` Ira Weiny
2019-11-07 2:26 ` Ira Weiny
2019-11-07 2:26 ` Ira Weiny
2019-11-03 21:18 ` [PATCH v2 08/18] mm/process_vm_access: set FOLL_PIN via pin_user_pages_remote() John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-04 17:41 ` Jerome Glisse
2019-11-04 17:41 ` Jerome Glisse
2019-11-04 17:41 ` Jerome Glisse
2019-11-04 17:41 ` Jerome Glisse
2019-11-03 21:18 ` [PATCH v2 09/18] drm/via: set FOLL_PIN via pin_user_pages_fast() John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-04 17:44 ` Jerome Glisse
2019-11-04 17:44 ` Jerome Glisse
2019-11-04 17:44 ` Jerome Glisse
2019-11-04 17:44 ` Jerome Glisse
2019-11-04 18:22 ` John Hubbard
2019-11-04 18:22 ` John Hubbard
2019-11-04 18:22 ` John Hubbard
2019-11-04 18:22 ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 10/18] fs/io_uring: set FOLL_PIN via pin_user_pages() John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 11/18] net/xdp: " John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 12/18] mm/gup: track FOLL_PIN pages John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-04 18:52 ` Jerome Glisse
2019-11-04 18:52 ` Jerome Glisse
2019-11-04 18:52 ` Jerome Glisse
2019-11-04 18:52 ` Jerome Glisse
2019-11-04 22:49 ` John Hubbard
2019-11-04 22:49 ` John Hubbard
2019-11-04 22:49 ` John Hubbard
2019-11-04 23:49 ` Jerome Glisse
2019-11-04 23:49 ` Jerome Glisse
2019-11-04 23:49 ` Jerome Glisse
2019-11-04 23:49 ` Jerome Glisse
2019-11-05 0:18 ` John Hubbard
2019-11-05 0:18 ` John Hubbard
2019-11-05 0:18 ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 13/18] media/v4l2-core: pin_longterm_pages (FOLL_PIN) and put_user_page() conversion John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-10 10:11 ` Hans Verkuil
2019-11-10 10:11 ` Hans Verkuil
2019-11-10 10:11 ` Hans Verkuil
2019-11-10 10:11 ` Hans Verkuil
2019-11-03 21:18 ` [PATCH v2 14/18] vfio, mm: " John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 15/18] powerpc: book3s64: convert to pin_longterm_pages() and put_user_page() John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 16/18] mm/gup_benchmark: support pin_user_pages() and related calls John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 17/18] selftests/vm: run_vmtests: invoke gup_benchmark with basic FOLL_PIN coverage John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` [PATCH v2 18/18] mm/gup: remove support for gup(FOLL_LONGTERM) John Hubbard
2019-11-03 21:18 ` John Hubbard
2019-11-03 21:18 ` John Hubbard
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