[RndTbl] *reading* a file causes reboot

Trevor Cordes trevor at tecnopolis.ca
Mon May 4 06:23:20 CDT 2015

This was a lovely "bug" to run into during a server migration tonight.

as root:
grep -r / foobar

cause a new system to crash/reboot.  Did it again and it did it exactly
at the same place.

The last line was about not being able to read (or some similar
error) /dev/watchdog

Rackspace thought it was a bug too, and quite odd, then they looked
around and decided this is "normal" when watchdogs are turned on.
Huh?  I haven't bz-checked this yet, but this smells funny to me.  A
read of a file should never *trigger* an action, right?  It's like
a /sys file: you echo > to them to get it to do something, never

Any thoughts?  If I don't find a bz about it, I'm definitely going to
make one.  (RHEL6)

RS claims the only "fix" is to disable watchdog or make sure not to
grep -r /.

I know grep -r / is really cheesy and lame-o and wasteful as there's
not going to be something in /dev I'll need (and reading /dem/kmem is
really cheesy) but sometimes I really need to find all
occurences of something fast with the least hassle possible (not going
into / and ls'ing and deciding what to include/exclude which is
different on many systems).  My point is, grep -r / has never given me
trouble in the past 20 years, but then again I usually don't have a

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