From: John Hubbard <jhubbard@nvidia.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "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>,
"Jason Gunthorpe" <jgg@ziepe.ca>, "Jens Axboe" <axboe@kernel.dk>,
"Jonathan Corbet" <corbet@lwn.net>,
"Jérôme Glisse" <jglisse@redhat.com>,
"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>,
"John Hubbard" <jhubbard@nvidia.com>,
"Christoph Hellwig" <hch@lst.de>,
"Leon Romanovsky" <leonro@mellanox.com>
Subject: [PATCH v9 08/25] mm/gup: allow FOLL_FORCE for get_user_pages_fast()
Date: Tue, 10 Dec 2019 18:53:01 -0800 [thread overview]
Message-ID: <20191211025318.457113-9-jhubbard@nvidia.com> (raw)
In-Reply-To: <20191211025318.457113-1-jhubbard@nvidia.com>
Commit 817be129e6f2 ("mm: validate get_user_pages_fast flags") allowed
only FOLL_WRITE and FOLL_LONGTERM to be passed to get_user_pages_fast().
This, combined with the fact that get_user_pages_fast() falls back to
"slow gup", which *does* accept FOLL_FORCE, leads to an odd situation:
if you need FOLL_FORCE, you cannot call get_user_pages_fast().
There does not appear to be any reason for filtering out FOLL_FORCE.
There is nothing in the _fast() implementation that requires that we
avoid writing to the pages. So it appears to have been an oversight.
Fix by allowing FOLL_FORCE to be set for get_user_pages_fast().
Fixes: 817be129e6f2 ("mm: validate get_user_pages_fast flags")
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
mm/gup.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/gup.c b/mm/gup.c
index c0c56888e7cc..958ab0757389 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2414,7 +2414,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
unsigned long addr, len, end;
int nr = 0, ret = 0;
- if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM)))
+ if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM |
+ FOLL_FORCE)))
return -EINVAL;
start = untagged_addr(start) & PAGE_MASK;
--
2.24.0
next prev parent reply other threads:[~2019-12-11 2:53 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-11 2:52 [PATCH v9 00/25] mm/gup: track dma-pinned pages: FOLL_PIN John Hubbard
2019-12-11 2:52 ` [PATCH v9 01/25] mm/gup: factor out duplicate code from four routines John Hubbard
2019-12-11 2:52 ` [PATCH v9 02/25] mm/gup: move try_get_compound_head() to top, fix minor issues John Hubbard
2019-12-11 2:52 ` [PATCH v9 03/25] mm: Cleanup __put_devmap_managed_page() vs ->page_free() John Hubbard
2019-12-11 2:52 ` [PATCH v9 04/25] mm: devmap: refactor 1-based refcounting for ZONE_DEVICE pages John Hubbard
2019-12-11 2:52 ` [PATCH v9 05/25] goldish_pipe: rename local pin_user_pages() routine John Hubbard
2019-12-11 2:52 ` [PATCH v9 06/25] mm: fix get_user_pages_remote()'s handling of FOLL_LONGTERM John Hubbard
2019-12-11 2:53 ` [PATCH v9 07/25] vfio: fix FOLL_LONGTERM use, simplify get_user_pages_remote() call John Hubbard
2019-12-11 2:53 ` John Hubbard [this message]
2019-12-11 2:53 ` [PATCH v9 09/25] IB/umem: use get_user_pages_fast() to pin DMA pages John Hubbard
2019-12-11 2:53 ` [PATCH v9 10/25] mm/gup: introduce pin_user_pages*() and FOLL_PIN John Hubbard
2019-12-11 20:57 ` Jonathan Corbet
2019-12-11 21:25 ` John Hubbard
2019-12-11 2:53 ` [PATCH v9 11/25] goldish_pipe: convert to pin_user_pages() and put_user_page() John Hubbard
2019-12-11 2:53 ` [PATCH v9 12/25] IB/{core,hw,umem}: set FOLL_PIN via pin_user_pages*(), fix up ODP John Hubbard
2019-12-11 2:53 ` [PATCH v9 13/25] mm/process_vm_access: set FOLL_PIN via pin_user_pages_remote() John Hubbard
2019-12-11 2:53 ` [PATCH v9 14/25] drm/via: set FOLL_PIN via pin_user_pages_fast() John Hubbard
2019-12-11 2:53 ` [PATCH v9 15/25] fs/io_uring: set FOLL_PIN via pin_user_pages() John Hubbard
2019-12-11 2:53 ` [PATCH v9 16/25] net/xdp: " John Hubbard
2019-12-11 2:53 ` [PATCH v9 17/25] media/v4l2-core: set pages dirty upon releasing DMA buffers John Hubbard
2019-12-11 2:53 ` [PATCH v9 18/25] media/v4l2-core: pin_user_pages (FOLL_PIN) and put_user_page() conversion John Hubbard
2019-12-11 2:53 ` [PATCH v9 19/25] vfio, mm: " John Hubbard
2019-12-11 2:53 ` [PATCH v9 20/25] powerpc: book3s64: convert to pin_user_pages() and put_user_page() John Hubbard
2019-12-11 10:42 ` Jan Kara
2019-12-11 2:53 ` [PATCH v9 21/25] mm/gup_benchmark: use proper FOLL_WRITE flags instead of hard-coding "1" John Hubbard
2019-12-11 2:53 ` [PATCH v9 22/25] mm, tree-wide: rename put_user_page*() to unpin_user_page*() John Hubbard
2019-12-11 2:53 ` [PATCH v9 23/25] mm/gup: track FOLL_PIN pages John Hubbard
2019-12-11 11:28 ` Jan Kara
2019-12-12 5:53 ` John Hubbard
2019-12-17 8:03 ` kbuild test robot
2019-12-17 8:03 ` [RFC PATCH] mm/gup: try_pin_compound_head() can be static kbuild test robot
2019-12-17 13:56 ` John Hubbard
2019-12-11 2:53 ` [PATCH v9 24/25] mm/gup_benchmark: support pin_user_pages() and related calls John Hubbard
2019-12-11 2:53 ` [PATCH v9 25/25] selftests/vm: run_vmtests: invoke gup_benchmark with basic FOLL_PIN coverage John Hubbard
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