Date: Fri, 06 Dec 1996 18:28:05 +0100 From: Tor Egge <Tor.Egge@idt.ntnu.no> To: smp@bluenose.na.tuns.ca Cc: peter@spinner.dialix.com, smp@freebsd.org Subject: More info about fatal trap 12 Message-ID: <199612061728.SAA22564@pat.idt.unit.no> In-Reply-To: Your message of "Fri, 6 Dec 1996 07:16:19 -0400 (AST)" References: <199612061116.HAA25054@bluenose.na.tuns.ca>
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> For compiling a kernel, `make depend' crashes the system.
> If 'make depend' is executed before `sysctl -w kern.smp_active=2',
> the kernel can be compiled to the very end until
>
> -------------
> cc -c -x assembler-with-cpp -DLOCORE -nostdinc -I- -I. -I../.. -I../../../include -DFAILSAFE -DCOMPAT_43 -DCD9660 -DMSDOSFS -DNFS -DFFS -DINET -DKERNEL ../../i386/i386/swtch.s
> --- vers.o ---
> sh ../../conf/newvers.sh SMP -DFAILSAFE -DCOMPAT_43 -DCD9660 -DMSDOSFS -DNFS -DFFS -DINET
>
> <crashes> :-(
> -------------
>
> I can provide the ktrace file, if you need it to identify the problem.
>
A closer examination of the kernel dump shows that the first page fault
is from the user process /bin/sh. The call stack is
#0 boot (howto=256) at ../../kern/kern_shutdown.c:267
#1 0xe0112d69 in panic (fmt=0xe01bcd3f "page fault")
at ../../kern/kern_shutdown.c:395
#2 0xe01bda25 in trap_fatal (frame=0xdfbffe58) at ../../i386/i386/trap.c:747
#3 0xe01bd458 in trap_pfault (frame=0xdfbffe58, usermode=0)
at ../../i386/i386/trap.c:654
#4 0xe01bd08b in trap (frame={tf_es = -270925808, tf_ds = 16,
tf_edi = -270878108, tf_esi = -541077504, tf_ebp = -541065552,
tf_isp = -541065600, tf_ebx = 89759744, tf_edx = -4194304,
tf_ecx = -528396, tf_eax = -528396, tf_trapno = 12, tf_err = 0,
tf_eip = -535058509, tf_cs = 8, tf_eflags = 66178, tf_esp = -532455933,
tf_ss = -270885632}) at ../../i386/i386/trap.c:313
#5 0xe01ba7b3 in pmap_enter (pmap=0xefdaba64, va=3753889792, pa=89759744,
prot=7 '\a', wired=0) at ../../i386/i386/pmap.c:2017
#6 0xe01a4193 in vm_fault (map=0xefdaba00, vaddr=3753889792,
fault_type=3 '\003', change_wiring=0) at ../../vm/vm_fault.c:773
#7 0xe01bd3b0 in trap_pfault (frame=0xdfbfffbc, usermode=1)
at ../../i386/i386/trap.c:634
#8 0xe01bcf33 in trap (frame={tf_es = 39, tf_ds = 39, tf_edi = 352256,
tf_esi = 330220, tf_ebp = -541074424, tf_isp = -541065244, tf_ebx = 0,
tf_edx = 1, tf_ecx = 330220, tf_eax = 0, tf_trapno = 12, tf_err = 7,
tf_eip = 45296, tf_cs = 31, tf_eflags = 66050, tf_esp = -541074448,
tf_ss = 39}) at ../../i386/i386/trap.c:241
------ userland ------ /bin/sh ----
#9 0xb0f0 in ?? () [forkshell]
#10 0x63ab in ?? () [evalcommand]
#11 0x58e1 in ?? () [evaltree]
#12 0xc11f in ?? () [cmdloop]
#13 0xc02e in ?? () [main]
#14 0x107e in ?? () [start]
Dump of assembler code for function forkshell:
0xb0cc <forkshell>: pushl %ebp
0xb0cd <forkshell+1>: movl %esp,%ebp
0xb0cf <forkshell+3>: subl $0xc,%esp
0xb0d2 <forkshell+6>: pushl %edi
0xb0d3 <forkshell+7>: pushl %esi
0xb0d4 <forkshell+8>: pushl %ebx
0xb0d5 <forkshell+9>: movl 0x8(%ebp),%edi
0xb0d8 <forkshell+12>: movl 0xc(%ebp),%esi
0xb0db <forkshell+15>: movl 0x52898,%eax
0xb0e0 <forkshell+20>: incl %eax
0xb0e1 <forkshell+21>: movl %eax,0x52898
0xb0e6 <forkshell+26>: movl 0x52898,%eax
0xb0eb <forkshell+31>: call 0x286c8 <fork>
0xb0f0 <forkshell+36>: movl %eax,0xfffffff8(%ebp)
0xb0f3 <forkshell+39>: cmpl $0xffffffff,%eax
The first access to the stack by the child process failed when trying
to save the return value from fork.
The parent process was running on CPU #1, and the child process
was running on CPU #0.
- Tor Egge
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