From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <037001c08f9d$068b3e00$0ab9c6d4@cybercable.fr>
From: "Boyd Roberts" <boyd@planete.net>
To: <9fans@cse.psu.edu>
References: <20010205115138.9D408199F3@mail.cse.psu.edu>
Subject: Re: [9fans] 9pcfs mballoc bug info
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Date: Mon,  5 Feb 2001 18:56:54 +0100
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> Didn't fix it yet, but in my case, txstart905() (plan9pc/etherlnk3.c)
> calls mbfree()  twice with the same buffer. Only transmit() and interrupt()
> (same file) call txstart905; and both routines hold the ilock on ctlr->wlock.

these dup frees are rarely easy to track down.  i'd add some code
before the free to detect it and print some debug, before the panic
leaves you with just a hex stack backtrace.  unfortunately this
may change the timing and the problem may go away.