I have to withdraw my Comment #71. At that time I did not have yet the new initial-ramdisk installed. Having it installed, gives me always an read-only rootfs.
And I think, I have also found the reason. The scripts in the initial ramdisk are executed with "set -e". In this case your pkill fails and aborts the execution of init-bottom/udev. And in the "normal" case, init-bottom/udev aborts because "udevadm control --exit" reports by means of its return value that, after timeout (yes, udevadm has its own timeout of 60s!), the exit failed.
I have to withdraw my Comment #71. At that time I did not have yet the new initial-ramdisk installed. Having it installed, gives me always an read-only rootfs.
And I think, I have also found the reason. The scripts in the initial ramdisk are executed with "set -e". In this case your pkill fails and aborts the execution of init-bottom/udev. And in the "normal" case, init-bottom/udev aborts because "udevadm control --exit" reports by means of its return value that, after timeout (yes, udevadm has its own timeout of 60s!), the exit failed.