BugLink: http://bugs.launchpad.net/bugs/1643637

[ Upstream commit 849c4987 ]

If the number of pages we are flushing is more than twice the number
of entries in the TSB, just scan the TSB table for matches rather
than probing each and every page in the range.

Based upon a patch and report by James Clarke.
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>