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Date: Mon, 26 Jan 2004 10:16:07 -0500 (EST)
From: Robert Watson <rwatson@freebsd.org>
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To: Jun Su <csujun@263.net>
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cc: current@freebsd.org
Subject: Re: [PANIC] today's cvs with KTRACE and MUTEX_PROFILING enabled
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On Mon, 26 Jan 2004, Jun Su wrote:

> > On Mon, 26 Jan 2004, Jun Su wrote:
> >
> > > I got the following panic when booting. Seems the if_data_mutex is
> > > corrupt by something.If you need any information, please feel free to
> > > let me know.  Thanks.
> >
> > Are you running with kernel modules?  If so, were all of them built as
> > part of your kernel build?  Turning on mutex profiling changes the size of
> > the mutex structure, so if you have modules that aren't built to be aware
> > of mutex profiling, you will get memory corruption.  When using mutex
> > profiling, I would generally suggest avoiding the use of kernel modules,
> > since it avoids the whole issue...
> Yes. This is the root cause. Our module building env doesn't include
> opt_global.h. Then the module's mtx doesn't match the one in Kernel. I think
> this is a requirement for MUTEX_PROFILING, not a suggestion before we
> complete the new building env for kernel module. I suggest to add this to
> man page. What is your option?

The following text appears in the NOTES section of MUTEX_PROFILING.9:

     The MUTEX_PROFILING option increases the size of struct mtx, so a
     kernel built with that option will not work with modules built
     without it.

We can probably make this a little more explicit by specifically
mentioning opt_global.h.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Senior Research Scientist, McAfee Research