Kernel panics when CONFIG_PAX_CONSTIFY_PLUGIN option is set.
Created attachment 353504 [details] kernel panic
Created attachment 353506 [details, diff] config.log
Created attachment 353508 [details] zfs_config.h
Created attachment 353510 [details] spl_config.h
Created attachment 353512 [details] emerge --info
My apologies for the late response. sys-fs/zfs-0.6.2-r1 should fix this.