The 6.0 kernel removes the 'migratepage' VFS op. Check for
migratepage.
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Rob Norris <robn@despairlabs.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org
Closes#17217
(cherry picked from commit ab9bb193f9)
