BPF Archive on lore.kernel.org
 help / color / Atom feed
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
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

  reply index

Thread overview: 57+ 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 ` [PATCH v2 01/18] mm/gup: pass flags arg to __gup_device_* functions John Hubbard
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
2019-11-04 16:51   ` Jerome Glisse
2019-11-03 21:17 ` [PATCH v2 03/18] goldish_pipe: rename local pin_user_pages() routine John Hubbard
2019-11-04 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
2019-11-10 10:10   ` Hans Verkuil
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
2019-11-04 17:33   ` Jerome Glisse
2019-11-04 19:04     ` John Hubbard
2019-11-04 19:18       ` Jerome Glisse
2019-11-04 19:30         ` John Hubbard
2019-11-04 19:52           ` Jerome Glisse
2019-11-04 20:09             ` John Hubbard
2019-11-04 20:31               ` Jason Gunthorpe
2019-11-04 20:40                 ` John Hubbard
2019-11-04 20:31               ` Jerome Glisse
2019-11-04 20:37                 ` Jason Gunthorpe
2019-11-04 20:57                   ` John Hubbard
2019-11-04 21:15                     ` Jason Gunthorpe
2019-11-04 21:34                       ` John Hubbard [this message]
2019-11-04 20:33   ` David Rientjes
2019-11-04 20:48     ` Jerome Glisse
2019-11-05 13:10   ` Mike Rapoport
2019-11-05 19:00     ` John Hubbard
2019-11-07  2:25       ` Ira Weiny
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 ` [PATCH v2 07/18] infiniband: set FOLL_PIN, FOLL_LONGTERM via pin_longterm_pages*() John Hubbard
2019-11-04 20:33   ` Jason Gunthorpe
2019-11-04 20:48     ` John Hubbard
2019-11-04 20:57       ` Jason Gunthorpe
2019-11-04 22:03         ` John Hubbard
2019-11-05  2:32           ` Jason Gunthorpe
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
2019-11-04 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
2019-11-04 17:44   ` Jerome Glisse
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 ` [PATCH v2 11/18] net/xdp: " John Hubbard
2019-11-03 21:18 ` [PATCH v2 12/18] mm/gup: track FOLL_PIN pages John Hubbard
2019-11-04 18:52   ` Jerome Glisse
2019-11-04 22:49     ` John Hubbard
2019-11-04 23:49       ` Jerome Glisse
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
2019-11-10 10:11   ` Hans Verkuil
2019-11-03 21:18 ` [PATCH v2 14/18] vfio, mm: " 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 ` [PATCH v2 16/18] mm/gup_benchmark: support pin_user_pages() and related calls 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 ` [PATCH v2 18/18] mm/gup: remove support for gup(FOLL_LONGTERM) 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=caaaaf52-490b-6ce1-81d8-675013354c73@nvidia.com \
    --to=jhubbard@nvidia.com \
    --cc=airlied@linux.ie \
    --cc=akpm@linux-foundation.org \
    --cc=alex.williamson@redhat.com \
    --cc=axboe@kernel.dk \
    --cc=benh@kernel.crashing.org \
    --cc=bjorn.topel@intel.com \
    --cc=bpf@vger.kernel.org \
    --cc=corbet@lwn.net \
    --cc=dan.j.williams@intel.com \
    --cc=daniel@ffwll.ch \
    --cc=davem@davemloft.net \
    --cc=david@fromorbit.com \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=hch@infradead.org \
    --cc=ira.weiny@intel.com \
    --cc=jack@suse.cz \
    --cc=jgg@ziepe.ca \
    --cc=jglisse@redhat.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=linux-media@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-rdma@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=magnus.karlsson@intel.com \
    --cc=mchehab@kernel.org \
    --cc=mhocko@suse.com \
    --cc=mike.kravetz@oracle.com \
    --cc=mpe@ellerman.id.au \
    --cc=netdev@vger.kernel.org \
    --cc=paulus@samba.org \
    --cc=shuah@kernel.org \
    --cc=vbabka@suse.cz \
    --cc=viro@zeniv.linux.org.uk \
    /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

BPF Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/bpf/0 bpf/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 bpf bpf/ https://lore.kernel.org/bpf \
		bpf@vger.kernel.org
	public-inbox-index bpf

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.bpf


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