Date: 18 Nov 2000 09:22:47 -0600 From: Michael Harnois <mdharnois@home.com> To: John Baldwin <jhb@FreeBSD.ORG> Cc: Sheldon Hearn <sheldonh@uunet.co.za>, current@FreeBSD.ORG, Valentin Chopov <valentin@valcho.net>, Boris Popov <bp@butya.kz>, Soren Schmidt <sos@freebsd.dk>, "Steven E. Ames" <steve@virtual-voodoo.com>, Alfred Perlstein <bright@wintelcom.net> Subject: Re: CURRENT is freezing again ... Message-ID: <86y9yhl2yg.fsf@mharnois.workgroup.net> In-Reply-To: <XFMail.001117103002.jhb@FreeBSD.org> References: <XFMail.001117103002.jhb@FreeBSD.org>
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On Fri, 17 Nov 2000 10:30:02 -0800 (PST), John Baldwin <jhb@FreeBSD.ORG> said:
> what the WITNESS code does is perform extra checks on mutex
> enter's and exit's to ensure that we aren't handling mutexes in
> such a way that a deadlock is possible. Thus, it verifies that
> you don't grab mutexes out of order, or that you don't grab
> sleep mutexes with interrupts disabled, etc.
Is this code meaningful on UP machines? Having been a victim of these
seemingly random freezes since SMPng started, as others have noted, I
decided to compile it in earlier this week. Twice now I've been dumped
into the debugger with this output:
lock order reversal
1st dc0 last acquired @ ../../pci/if_dc.c:2717
2nd 0xc0acdb3c dc1 @ ../../pci/if_dc.c: 2717
3rd 0xc0acab3c dc0 @ ../../pci/if_dc.c: 2929
Debugger ("witness_enter")
Stopped at Debugger+0x39: movb $0, in.Debugger.639
--
Michael D. Harnois, Redeemer Lutheran Church, Washburn, IA
mdharnois@home.com aa0bt@aa0bt.ampr.org
The atheist staring from the attic window is often nearer to God than the
believer caught up in his own false image of God. -- Martin Buber
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