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authorJohn Hubbard <jhubbard@nvidia.com>2020-01-30 22:12:43 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-01-31 10:30:37 -0800
commitf4000fdf435b8301a11cf85237c561047f8c4c72 (patch)
treedff6f95dcfa08316c17e073cbe15c3043aa92765
parentvfio: fix FOLL_LONGTERM use, simplify get_user_pages_remote() call (diff)
downloadlinux-dev-f4000fdf435b8301a11cf85237c561047f8c4c72.tar.xz
linux-dev-f4000fdf435b8301a11cf85237c561047f8c4c72.zip
mm/gup: allow FOLL_FORCE for get_user_pages_fast()
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(). Link: http://lkml.kernel.org/r/20200107224558.2362728-9-jhubbard@nvidia.com Fixes: 817be129e6f2 ("mm: validate get_user_pages_fast flags") Signed-off-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Leon Romanovsky <leonro@mellanox.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Christoph Hellwig <hch@lst.de> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Björn Töpel <bjorn.topel@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Hans Verkuil <hverkuil-cisco@xs4all.nl> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/gup.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/gup.c b/mm/gup.c
index 1315b85b3b1b..904bd8b9be1b 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2411,7 +2411,8 @@ 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;