Bug 29059

	Several -CURRENT machines at this site are currently experiencing
	'spontaneous' reboots (i.e. an otherwise mostly idle system
	panics for no obvious reason).

	From what I gather of the debugging session shown below,
	the rt value is invalid. I am keeping the kernel crash dump
	just in case; please feel free to request more information
	and forensics.

Script started on Wed Jul 18 15:27:36 2001
# gdb -k /usr/obj/usr/src/sys/SHALMANESER/kernel.debug vmcore.0
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This GDB was configured as "i386-unknown-freebsd"...
IdlePTD 4472832
initial pcb at 380c40
panicstr: page fault
panic messages:
---
Fatal trap 12: page fault while in kernel mode
fault virtual address	= 0x6e6f729f
fault code		= supervisor read, page not present
instruction pointer	= 0x8:0xc0261184
stack pointer	        = 0x10:0xc804cf1c
frame pointer	        = 0x10:0xc804cf34
code segment		= base rx0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, def32 1, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 12 (swi6: tty:sio+)
trap number		= 12
panic: page fault

syncing disks... 12 12 8 8 3 3 
done
Uptime: 1d23h57m8s

dumping to dev ad0s1b, offset 242320
dump ata0: resetting devices .. done
127 126 125 124 123 122 121 120 119 118 117 116 115 114 113 112 111 110 109 108 107 106 105 104 103 102 101 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 
---
#0  dumpsys () at /usr/src/sys/kern/kern_shutdown.c:478
478		if (dumping++) {
(kgdb) bt
#0  dumpsys () at /usr/src/sys/kern/kern_shutdown.c:478
#1  0xc01d62aa in boot (howto=256) at /usr/src/sys/kern/kern_shutdown.c:321
#2  0xc01d66c1 in panic (fmt=0xc03227af "page fault")
    at /usr/src/sys/kern/kern_shutdown.c:600
#3  0xc02c9146 in trap_fatal (frame=0xc804cedc, eva=1852797599)
    at /usr/src/sys/i386/i386/trap.c:937
#4  0xc02c8e99 in trap_pfault (frame=0xc804cedc, usermode=0, eva=1852797599)
    at /usr/src/sys/i386/i386/trap.c:851
#5  0xc02c8853 in trap (frame={tf_fs = 24, tf_es = -1056374768, tf_ds = 16, 
      tf_edi = -1057656832, tf_esi = 1852797539, tf_ebp = -939208908, 
      tf_isp = -939208952, tf_ebx = -1050534144, tf_edx = 20, tf_ecx = 2, 
      tf_eax = -1053233216, tf_trapno = 12, tf_err = 0, tf_eip = -1071246972, 
      tf_cs = 8, tf_eflags = 66054, tf_esp = 0, tf_ss = 4})
    at /usr/src/sys/i386/i386/trap.c:410
#6  0xc0261184 in nd6_timer (ignored_arg=0x0)
    at /usr/src/sys/netinet6/nd6.c:441
#7  0xc01df7be in softclock (dummy=0x0) at /usr/src/sys/kern/kern_timeout.c:142
#8  0xc01cafb3 in ithread_loop (arg=0xc0efbd00)
    at /usr/src/sys/kern/kern_intr.c:520
#9  0xc01ca138 in fork_exit (callout=0xc01cae14 <ithread_loop>, 
    arg=0xc0efbd00, frame=0xc804cfa8) at /usr/src/sys/kern/kern_fork.c:723
(kgdb) fr 6
#6  0xc0261184 in nd6_timer (ignored_arg=0x0)
    at /usr/src/sys/netinet6/nd6.c:441
441				continue;
(kgdb) list
436			/* XXX: used for the DELAY case only: */
437			struct nd_ifinfo *ndi = NULL;
438	
439			if ((rt = ln->ln_rt) == NULL) {
440				ln = next;
441				continue;
442			}
443			if ((ifp = rt->rt_ifp) == NULL) {
444				ln = next;
445				continue;
(kgdb) print rt
$1 = (struct rtentry *) 0x6e6f7263
(kgdb) print ln
$2 = (struct llinfo_nd6 *) 0xc1621f00
(kgdb) print ifp
$3 = (struct ifnet *) 0xc0f57000
(kgdb) print *rt
Cannot access memory at address 0x6e6f7263.
(kgdb) print *ln
$4 = {ln_next = 0xc138efc0, ln_prev = 0x12, ln_rt = 0x6e6f7263, 
  ln_hold = 0x7572203a, ln_asked = 1852403310, ln_expire = 1869226087, 
  ln_state = 98, ln_router = 0, ln_byhint = 0}

Script done on Wed Jul 18 15:33:04 2001

Fix: 

None known so far.
How-To-Repeat: Not determined.