With a system built from sources dated 2017-07-15 at 09:06:30 UTC....
I had a backup running in one session, using 'dump -X ...' (to use an internal fs(4) snapshot of the file system), and in another session I was doing a whole bunch of umount(8)'s of null-mounted file systems (running "$PATH/sandbox umount").
With no warning, the system completely hung. No keyboard or mouse activity, and other background processes like xosview stopped updating. Unable to get a core dump or even a stack trace, since I could not get into ddb. (Even if I could, my keyboard is attached via xhci/usb3, so doesn't work for ddb.)
I have no idea if this is reproducible, but I thought it might be useful for others to be aware.
+------------------+--------------------------+----------------------------+ | Paul Goyette | PGP Key fingerprint: | E-mail addresses: | | (Retired) | FA29 0E3B 35AF E8AE 6651 | paul at whooppee dot com | | Kernel Developer | 0786 F758 55DE 53BA 7731 | pgoyette at netbsd dot org | +------------------+--------------------------+----------------------------+
