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Date:      Wed, 28 Jan 2004 13:03:38 -0500
From:      John Baldwin <jhb@FreeBSD.org>
To:        "Erik Moe" <emoe@cox.net>, <freebsd-current@freebsd.org>
Subject:   Re: 5.2-RELEASE panic in turnstile_wait
Message-ID:  <200401281303.38753.jhb@FreeBSD.org>
In-Reply-To: <IJEJIDFLPIJEPPAPEIHCCECMCEAA.emoe@cox.net>
References:  <IJEJIDFLPIJEPPAPEIHCCECMCEAA.emoe@cox.net>

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On Tuesday 27 January 2004 10:06 pm, Erik Moe wrote:
> panic: page fault
> panic messages:
> ---
> Fatal trap 12: page fault while in kernel mode
> fault virtual address	= 0x6c
> fault code		= supervisor read, page not present
> instruction pointer	= 0x8:0xc0571bfd
> stack pointer	        = 0x10:0xe3ab7c28
> frame pointer	        = 0x10:0xe3ab7c2c
> code segment		= base 0x0, limit 0xfffff, type 0x1b
> 			= DPL 0, pres 1, def32 1, gran 1
> processor eflags	= resume, IOPL = 0
> current process		= 699 (zcat)
> trap number		= 12
> panic: page fault
>
> #4  0xc06b5113 in trap (frame=
>       {tf_fs = 24, tf_es = 16, tf_ds = 16, tf_edi = -969008320, tf_esi
> = -969012736, tf_ebp = -475300820, tf_isp = -475300844, tf_ebx =
> -969008320, tf_edx = -969012736, tf_ecx = 0, tf_eax = 0, tf_trapno = 12,
> tf_err = 0, tf_eip = -1068033027, tf_cs = 8, tf_eflags = 65538, tf_esp =
> -962721112, tf_ss = -475300780})
>     at /usr/src/sys/i386/i386/trap.c:250
> #5  0xc06a7de8 in calltrap () at {standard input}:94
> #6  0xc0571efc in turnstile_wait (ts=0xc63e1b40, lock=0xc69e0aa8,
> owner=0x0) at /usr/src/sys/kern/subr_turnstile.c:458

There is an extra frame in here that gdb misses.

> (kgdb) frame 6
> #6  0xc0571efc in turnstile_wait (ts=0xc63e1b40, lock=0xc69e0aa8,
> owner=0x0) at /usr/src/sys/kern/subr_turnstile.c:458
> 458			turnstile_setowner(ts, owner);

The real panic is in turnstile_setowner().  If owner is indeed NULL (gdb 
sometimes messes up values of local variables and arguments) then that is why 
it is panicing.  Can you pop up to frame 7 and print out *m?

-- 
John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org



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