(forw) Re: (forw) Re: Process stuck in STOP state

Alfred Perlstein alfred at freebsd.org
Fri Jan 2 00:47:25 UTC 2009

David, Julian, there's a pretty good synopsys by Tor attached
here for a deadlock in 7.x.

Can anyone comment if it's fixed or if there's a way to fix it?


----- Forwarded message from Tor Egge <Tor.Egge at cvsup.no.freebsd.org> -----

From: Tor Egge <Tor.Egge at cvsup.no.freebsd.org>
To: alfred at freebsd.org
Cc: smp at freebsd.org
Subject: Re: (forw) Re: Process stuck in STOP state
Date: Thu, 01 Jan 2009 22:15:14 +0000 (UTC)
Message-Id: <20090101.221514.41667097.Tor.Egge at cvsup.no.freebsd.org>
X-Mailer: Mew version 5.2 on Emacs 21.3 / Mule 5.0 (SAKAKI)
Sender: owner-freebsd-smp at freebsd.org

> Can someone look at this?  This is pretty weird, it seems
> that somehow there's some deadlock with vnode locks, but it
> doesn't appear to be due a leaked vnode lock as "show lockednods"
> doesn't show any vnodes locks.
> The trace should be somewhat easy to figure out but I'm kinda
> of stuck..
> Any ideas how this could happen?

I had a brief look at <URL:http://aqua.pixnet.tw/~jnlin/textdump/event3/1230/>

msgbuf.txt contained info about some nfs vnodes locked by pid 27645.

It looks like thread suspension is broken for the SINGLE_NO_EXIT case.

Threads performing an interruptable sleep are suspended, even while holding
other resources (e.g. vnode locks).

Threads performing a non-interruptable sleep, waiting for resources held by the
suspended threads are not suspended.

The thread that started the suspension is not woken up since some of the
other threads are not yet suspended.

- Tor Egge
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----- End forwarded message -----

- Alfred Perlstein

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