Comment 3 for bug 485563

I have seen the same syslog output a couple of times now. When it occurs, it's (almost) impossible to bring back the instance alive: no SSH access and reboot via the aws console panel or elasticfox plugin does not help either.

Further in the syslog output, I get the following output which might be related (not sure):
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kernel BUG at arch/i386/mm/hypervisor.c:185!
invalid opcode: 0000 [#1]
SMP
last sysfs file: /block/sdh/size
Modules linked in: ipv6(F)(U) xfs(F)(U) xennet(F)(U) xenblk(F)(U) ext3(F)(U) jbd(F)(U) mbcache(F)(U)
CPU: 0
EIP: 0061:[<c101bf0e>] Tainted: GF VLI
EFLAGS: 00210282 (2.6.21.7-2.fc8xen-ec2-v1.0 #2)
EIP is at xen_pgd_pin+0x54/0x5e
eax: ffffffea ebx: c2a28ef8 ecx: 00000001 edx: 00000000
esi: 00007ff0 edi: 00000000 ebp: ed2ab630 esp: c2a28ef8
ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0069
Process apache2 (pid: 16864, ti=c2a28000 task=ece17210 task.ti=c2a28000)
Stack: 00000002 00364984 20739000 0040e720 00000000 c101816d c03e0b00 c1018196
       c2b6ebcc c102250e c2b6e718 c2a28fb8 c106e159 c2a28fb8 bfe70100 01200011
       00000000 ed2ab630 c03e0b00 ecc73a80 c2b6ebd8 c2b6ebec c2b6ebe8 c03e0b00
Call Trace:
 [<c101816d>] __pgd_pin+0x2f/0x3c
 [<c1018196>] mm_pin+0x1c/0x23
 [<c102250e>] copy_process+0xac3/0x10bc
 [<c106e159>] kmem_cache_alloc+0x6b/0x98
 [<c1022b58>] do_fork+0x51/0x13a
 [<c100321e>] sys_clone+0x36/0x3b
 [<c1005688>] syscall_call+0x7/0xb
 [<c1200000>] __sched_text_start+0x240/0x83f
 =======================
Code: eb fe a1 24 c2 38 c1 8b 14 90 81 e2 ff ff ff 7f 89 54 24 04 89 e3 b9 01 00 00 00 31 d2 be f0 7f 00 00 e8 36 54 fe ff 85 c0 79 04 <0f> 0b eb fe 83 c4 0c 5b 5e c3 56 89 c2 53 83 ec 0c c1 ea 0c 80
EIP: [<c101bf0e>] xen_pgd_pin+0x54/0x5e SS:ESP 0069:c2a28ef8
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Searching in google, I find this bug which relates to a kernel issue: https://bugzilla.redhat.com/show_bug.cgi?id=335961