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mm/gup: might_lock_read(mmap_sem) in get_user_pages_fast()

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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>
This commit is contained in:
John Hubbard 2020-06-03 15:56:40 -07:00 committed by Linus Torvalds
parent 2170ecfa76
commit f81cd178ec
1 changed files with 3 additions and 0 deletions
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3
mm/gup.c
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@ -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;