Commit f81cd178 authored Jun 03, 2020 by John Hubbard Committed by Linus Torvalds Jun 03, 2020

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>

parent 2170ecfa

mm/gup.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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;

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