Date: Wed, 11 May 2005 20:36:08 -0700 (PDT) From: Doug White <dwhite@gumbysoft.com> To: Ed Maste <emaste@phaedrus.sandvine.ca> Cc: stable@freebsd.org Subject: Re: Experimental ttwwakeup() panic patch Message-ID: <20050511202829.F11600@carver.gumbysoft.com> In-Reply-To: <20050506145902.GA51724@sandvine.com> References: <20050503115344.S26250@carver.gumbysoft.com> <20050506145902.GA51724@sandvine.com>
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Sorry for the late reply on this. On Fri, 6 May 2005, Ed Maste wrote: > On Wed, May 04, 2005 at 08:54:23PM -0700, Doug White wrote: > > > > http://people.freebsd.org/~dwhite/tty.c.20050503.patch > > > > This patch has been committed and exists as rev 1.228.2.4 of > > src/sys/kern/tty.c. Please let me know if this fixes the panic for you, > > or causes new problems :) > > For what it's worth, I've come across a similar crash during a test that > repeatedly ssh'd into the machine. > > This was while opening a pty, not using serial console. The symptoms > seem similar; my tty struct has a struct knlist with a null struct mtx *. > I haven't yet investigated in great detail or tried the patch. I just > wanted to offer this as another data point. > > Although kgdb gets confused during the backtrace (frames 7 and 8) the > tf_eip is a cmpxchg in knote(). This is a problem mlaier and I may have fixed, at least against -CURRENT. It appears that the process group alias in struct tty is accessed without locking and its changing out from under us. Give this a try: http://people.freebsd.org/~mlaier/tty.t_pgrp.diff It compiles but I haven't actually booted a kernel with it, so YMMV. -- Doug White | FreeBSD: The Power to Serve dwhite@gumbysoft.com | www.FreeBSD.org
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