hang during dump (reproducible)

Jake Holland jholland at fastsoft.com
Sat Feb 11 03:01:08 UTC 2012


I was reliably seeing a hang during panic in stable/8 -r231144 (and 8.2 release) with an active ssh session. The SCHEDULER_STOPPED patch fixed it, once I found it:

Many thanks to Attilio Rao, Kostik Belousov, and Andriy Gapon. And anybody else involved.

However, when I looked at the commit I noticed this:
> $ svn log -r228424 svn://svn.freebsd.org/base
> MFC after:              3 months (or never)

I'm not sure whether "never" is still considered an option, but it would be useful for me if 8.3 release, when it comes, does not hang this way during panic. But thanks for the patch, regardless.

Problem details:
If I did a "sysctl debug.kdb.panic=1" from the console while the machine was idle, the dump would complete and the machine would reboot and come up with a good core.

If I did the same command remotely via ssh, it would hang every time.
I also usually would see a hang if I had an active ssh session printing things while I caused a panic from the console. Occasionally in that case it would continue and make a good core if I killed the ssh session from the client side. An open but idle ssh session did not seem to induce a hang.

If anybody wants other details, I'd be happy to provide them.

Jake Holland

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