Date: Mon, 02 Oct 2000 21:04:27 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: Jason Evans <jasone@canonware.com> Cc: freebsd-smp@FreeBSD.ORG, Steve Kargl <sgk@troutmask.apl.washington.edu> Subject: Re: witness code status? Message-ID: <XFMail.001002210427.jhb@FreeBSD.org> In-Reply-To: <20001002164139.I58256@canonware.com>
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On 02-Oct-00 Jason Evans wrote:
> On Mon, Oct 02, 2000 at 04:32:36PM -0700, Steve Kargl wrote:
>> What's the current status of the integration of BSDi's
>> witness code? If I include "options WITNESS" in my kernel
>> config file, I get an immediate panic at boot. My sources
>> are from today (01 Oct 00), and the system is currently
>> running a MP kernel (built without the witness code).
>>
>> PS: Yes, I know there will be periods of instability, but
>> you (the SMP developers) can't possibly have all combinations
>> of MP hardware.
>
> I (and others) have been running kernels with the witness code enabled for
> over a month. The witness code's purpose is to detect lock cycles that
> could cause deadlock, among other incorrect mutex uses. The stack trace
> and panic message in your email seem indicate a programming error. In
> other words, the witness code is doing its job.
Except that it's not in this case. The error indicates that mtx_enter()
is being called with MTX_SPIN, but if you look in sys/dev/randomdev/*,
all of the mtx_*() functions use MTX_DEF. It's a bug alright, but not
in the random code.
> Jason
>
>> panic: mutex_enter: MTX_DEF on MTX_SPIN mutex random harvest\
>> @/usr/src/sys/modules/randomdev/../../dev/randomdev/yarrow.c:515
>> cpuid = 1; lapic.id = 00000000
>> Debugger("panic')
>>
>> CPU1 stopping CPUs: 0x00000001 stopped
>> Stopped at Debugger+0x38: movb $0,in_Debugger.684
>>
>> db>trace
>> Debugger(c0277da1)
>> panic
>> witness_enter
>> _mtx_enter
>> random_harvest_internal
>> write_random
>> random_write
>> ufs_vnoperatespec
>> vn_write
>> dofilewrite
>> write
>> syscall2
>> Xint0x80_syscall
--
John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
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