system command hangs (unkillable); ps shows 'sbwait' state?

[Rob]

Hi,

I'm using fairly recent FreeBSD-stable on intel PC.

Within last few days, I encountered two hangs of a system command, that
I was unable to resolve. I could not kill the command, even a 'kill -9'
did not work.

1. I had a 2.5 Gb disk mounted on /home/software.
    As root, I overloaded the filesystem, with negative percentage left
    on the device (from df command). So as root, I did a 'rm -rf' in
    /home/software, followed by a 'df -h'. But the df command gave no
    response and became unkillable by any means (ctrl-C, kill -9 <pid>).
    Using 'ps', I found the df command in the 'sbwait' state.

2. I had a usb device mounted as /dev/da0s1 on /mnt. Mounting (as root)
    went all well, but when I unmounted it, as root, the umount command
    hanged, again the umount command was in sbwait state.
    In this case it was even worse: when I killed the xterminal
    where the umount command was hanging, the whole system froze.
    Only power off/on helped me out here.

I don't know what happened; don't know how to further investigate this.
Has somebody else similar experiences? Is stability going down for Stable kernel?


Regards,
Rob.