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authorJohn Hubbard <jhubbard@nvidia.com>2020-06-03 15:56:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-03 20:09:42 -0700
commitf81cd178ecfd0806c1d2859cfe0a162d80c81a69 (patch)
tree7abc36f482d48e1add0a8a9a573be4bebd167417 /mm/gup.c
parent2170ecfa768850bb29487baa3101c993ab7d7402 (diff)
mm/gup: might_lock_read(mmap_sem) in get_user_pages_fast()
Instead of scattering these assertions across the drivers, do this assertion inside the core of get_user_pages_fast*() functions. That also includes pin_user_pages_fast*() routines. Add a might_lock_read(mmap_sem) call to internal_get_user_pages_fast(). Suggested-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Matthew Wilcox <willy@infradead.org> Cc: Michel Lespinasse <walken@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Link: http://lkml.kernel.org/r/20200522010443.1290485-1-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
-rw-r--r--mm/gup.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/gup.c b/mm/gup.c
index 0702c1a7e041..61ee405ec558 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2739,6 +2739,9 @@ static int internal_get_user_pages_fast(unsigned long start, int nr_pages,
FOLL_FAST_ONLY)))
return -EINVAL;
+ if (!(gup_flags & FOLL_FAST_ONLY))
+ might_lock_read(&current->mm->mmap_sem);
+
start = untagged_addr(start) & PAGE_MASK;
addr = start;
len = (unsigned long) nr_pages << PAGE_SHIFT;