* [merged] mm-gup-allow-foll_force-for-get_user_pages_fast.patch removed from -mm tree
@ 2020-01-31 23:17 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2020-01-31 23:17 UTC (permalink / raw)
To: alex.williamson, aneesh.kumar, axboe, bjorn.topel, corbet,
dan.j.williams, daniel.vetter, hch, hverkuil-cisco, ira.weiny,
jack, jgg, jgg, jglisse, jhubbard, kirill, leonro, mchehab,
mm-commits, rppt
The patch titled
Subject: mm/gup: allow FOLL_FORCE for get_user_pages_fast()
has been removed from the -mm tree. Its filename was
mm-gup-allow-foll_force-for-get_user_pages_fast.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: John Hubbard <jhubbard@nvidia.com>
Subject: 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>
---
mm/gup.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/gup.c~mm-gup-allow-foll_force-for-get_user_pages_fast
+++ a/mm/gup.c
@@ -2411,7 +2411,8 @@ int get_user_pages_fast(unsigned long st
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;
_
Patches currently in -mm which might be from jhubbard@nvidia.com are
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2020-01-31 23:17 [merged] mm-gup-allow-foll_force-for-get_user_pages_fast.patch removed from -mm tree akpm
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