Bug 97075

This was happening on my RELENG_6_0 version too.
This is panic messages:

cpuid = 0; apic id = 00
fault virtual address = 0x88
fault code = supervisor read, page not present
instruction pointer = 0x8:0xffffffffb41289a7
stack pointer = 0x10:0xffffffffb1c5baf0
frame pointer = 0x10:0xffffffffb1c5bb10
code segment = base rx0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags = interrupt enabled, resume, IOPL = 0
current process = 44 (swi4: clock)
trap number = 12
panic: page fault
cpuid = 0
Uptime: 1m2s
Dumping 2047 MB (2 chunks)
chunk 0: 1MB (151 pages) ... ok
chunk 1: 2047MB (523888 pages) 2031 2015 1999 1983 1967 1951 1935 1919 1903 1887 1871 1855 1839 1823 1807 1791 1775 1759 1743 1727 1711 1695 1679 1663 1647 1631 1615 1599 1583 1567 1551 1535 1519 1503 1487 1471 1455 1439 1423 1407 1391 1375 1359 1343 1327 1311 1295 1279 1263 1247 1231 1215 1199 1183 1167 1151 1135 1119 1103 1087 1071 1055 1039 1023 1007 991 975 959 943 927 911 895 879 863 847 831 815 799 783 767 751 735 719 703 687 671 655 639 623 607 591 575 559 543 527 511 495 479 463 447 431 415 399 383 367 351 335 319 303 287 271 255 239 223 207 191 175 159 143 127 111 95 79 63 47 31 15

Here is my dmesg:
dmesg
Copyright (c) 1992-2006 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
        The Regents of the University of California. All rights reserved.
FreeBSD 6.1-RELEASE #1: Tue May  9 15:12:36 EEST 2006
    alex@narasyst.narasyst.com:/usr/src/sys/amd64/compile/NARASYST
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: AMD Opteron(tm) Processor 246 (2004.56-MHz K8-class CPU)
  Origin = "AuthenticAMD"  Id = 0xf5a  Stepping = 10
  Features=0x78bfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2>
  AMD Features=0xe0500800<SYSCALL,NX,MMX+,LM,3DNow+,3DNow>
real memory  = 4160159744 (3967 MB)
avail memory = 4018642944 (3832 MB)
ACPI APIC Table: <PTLTD          APIC  >
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
 cpu0 (BSP): APIC ID:  0
 cpu1 (AP): APIC ID:  1
MADT: Forcing active-low polarity and level trigger for SCI
ioapic0 <Version 1.1> irqs 0-23 on motherboard
ioapic1 <Version 1.1> irqs 24-27 on motherboard
ioapic2 <Version 1.1> irqs 28-31 on motherboard
acpi0: <PTLTD    XSDT> on motherboard
acpi0: Power Button (fixed)
acpi0: Sleep Button (fixed)
unknown: I/O range not supported
unknown: I/O range not supported
Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000
acpi_timer0: <24-bit timer at 3.579545MHz> port 0x8008-0x800b on acpi0
cpu0: <ACPI CPU> on acpi0
cpu1: <ACPI CPU> on acpi0
acpi_button0: <Power Button> on acpi0
pcib0: <ACPI Host-PCI bridge> port 0xcf8-0xcff on acpi0
pci0: <ACPI PCI bus> on pcib0
pcib1: <ACPI PCI-PCI bridge> at device 6.0 on pci0
pci1: <ACPI PCI bus> on pcib1
pci1: <serial bus, USB> at device 0.0 (no driver attached)
pci1: <serial bus, USB> at device 0.1 (no driver attached)
pci1: <display, VGA> at device 6.0 (no driver attached)
isab0: <PCI-ISA bridge> at device 7.0 on pci0
isa0: <ISA bus> on isab0
atapci0: <AMD 8111 UDMA133 controller> port 0x1f0-0x1f7,0x3f6,0x170-0x177,0x376,0x1020-0x102f at device 7.1 on pci0
ata0: <ATA channel 0> on atapci0
ata1: <ATA channel 1> on atapci0
pci0: <serial bus, SMBus> at device 7.2 (no driver attached)
pci0: <bridge> at device 7.3 (no driver attached)
pcib2: <ACPI PCI-PCI bridge> at device 10.0 on pci0
pci2: <ACPI PCI bus> on pcib2
bge0: <Broadcom BCM5705 Gigabit Ethernet, ASIC rev. 0x3003> mem 0xfd000000-0xfd00ffff irq 27 at device 3.0 on pci2
miibus0: <MII bus> on bge0
brgphy0: <BCM5705 10/100/1000baseTX PHY> on miibus0
brgphy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseTX, 1000baseTX-FDX, auto
bge0: Ethernet address: 00:50:45:5c:51:26
bge1: <Broadcom BCM5705 Gigabit Ethernet, ASIC rev. 0x3003> mem 0xfd010000-0xfd01ffff irq 27 at device 4.0 on pci2
miibus1: <MII bus> on bge1
brgphy1: <BCM5705 10/100/1000baseTX PHY> on miibus1
brgphy1:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseTX, 1000baseTX-FDX, auto
bge1: Ethernet address: 00:50:45:5c:51:27
atapci1: <SiI 3114 SATA150 controller> port 0x3020-0x3027,0x3014-0x3017,0x3018-0x301f,0x3010-0x3013,0x3000-0x300f mem 0xfd020000-0xfd0203ff irq 25 at device 5.0 on pci2
ata2: <ATA channel 0> on atapci1
ata3: <ATA channel 1> on atapci1
ata4: <ATA channel 2> on atapci1
ata5: <ATA channel 3> on atapci1
pci0: <base peripheral, interrupt controller> at device 10.1 (no driver attached)
pcib3: <ACPI PCI-PCI bridge> at device 11.0 on pci0
pci3: <ACPI PCI bus> on pcib3
twe0: <3ware Storage Controller. Driver version 1.50.01.002> port 0x4000-0x400f mem 0xfd800000-0xfdffffff irq 29 at device 1.0 on pci3
twe0: [GIANT-LOCKED]
twe0: 2 ports, Firmware FE8S 1.05.00.068, BIOS BE7X 1.08.00.048
pci0: <base peripheral, interrupt controller> at device 11.1 (no driver attached)
atkbdc0: <Keyboard controller (i8042)> port 0x60,0x64 irq 1 on acpi0
ppc0: <ECP parallel printer port> port 0x378-0x37f,0x778-0x77f irq 7 drq 1 on acpi0
ppc0: Generic chipset (ECP/PS2/NIBBLE) in COMPATIBLE mode
ppc0: FIFO with 16/16/8 bytes threshold
ppbus0: <Parallel port bus> on ppc0
orm0: <ISA Option ROMs> at iomem 0xc0000-0xc7fff,0xc8000-0xc97ff,0xc9800-0xcafff,0xcb000-0xcbfff on isa0
sc0: <System console> at flags 0x100 on isa0
sc0: VGA <16 virtual consoles, flags=0x300>
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on isa0
Timecounters tick every 1.000 msec
IPv6 packet filtering initialized, default to accept, logging limited to 5 packets/entry
ipfw2 (+ipv6) initialized, divert loadable, rule-based forwarding disabled, default to accept, logging limited to 5 packets/entry by default
twed0: <Unit 0, TwinStor, Normal> on twe0
twed0: 238474MB (488395120 sectors)
SMP: AP CPU #1 Launched!
Trying to mount root from ufs:/dev/twed0s1a
WARNING: / was not properly dismounted
IP Filter: v4.1.8 initialized.  Default = pass all, Logging = enabled
bge0: link state changed to UP

How-To-Repeat: I can force this panic to happens, when I execute 
#shutdown -r now from SSH
After that when system comes up and running, after a while (approximately
1-2 min).  System panic.  And after fresh start it start to work for longer,
about 1-2 days), it is possible to be another error.  As soon as I catch
this stack I will attach it too.  I just return 2xRAM.  So I was with 4GB,
while this panic appears.