mm/gup: fix wrongly calculated returned value in fault_in_safe_writeable()

Not like fault_in_readable() or fault_in_writeable(), in
fault_in_safe_writeable() local variable 'start' is increased page by page
to loop till the whole address range is handled.  However, it mistakenly
calculates the size of the handled range with 'uaddr - start'.

Fix it here.

Andreas said:

: In gfs2, fault_in_iov_iter_writeable() is used in
: gfs2_file_direct_read() and gfs2_file_read_iter(), so this potentially
: affects buffered as well as direct reads.  This bug could cause those
: gfs2 functions to spin in a loop.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Baoquan He <[email protected]>
Fixes: fe673d3f5bf1 ("mm: gup: make fault_in_safe_writeable() use fixup_user_fault()")
Reviewed-by: Oscar Salvador <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Andreas Gruenbacher <[email protected]>
Cc: Yanjun.Zhu <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions