Trivial hard lockup, SCSI, 2.4.23

From: Ian Soboroff
Date: Tue Dec 16 2003 - 13:29:38 EST



I've found that I can lock a machine running 2.4.23aa1 by trying to
access a nonexistent SCSI device. In other words, if a userspace
program tries to access /dev/sdd, but no device is attached on any
SCSI bus using that device node, the machine locks hard.

We found this when we disconnected a SCSI hardware RAID from a server,
but forgot to remove the cron job which checked its status.

The lockup leaves no errors whatsoever in the logs. I finally tracked
it down with the NMI watchdog.

Ian


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