Re: Guest Hang Bugs

[James Thomason <james@divide.org>]

Avi and others,
 
The system under load finally panicked and all cores hit 100%, so I spoke
too soon. Unfortunately my console was garbled and I was not able to get the
text of that panic.

Afterwards I am unable to boot the guest with kvm -smp > 2 because the guest
panics at boot time.  The text of that boot time panic is below.  However,
booting the guest with kvm -smp 1 works.  After rebooting the KVM host, I am
able to boot the guest with kvm -smp 12 etc again.

I will try to induce the guest to panic again and see if I can capture it.

Configuration: 

KVM HOST: 
Ubuntu 8.10
KVM 83 2.6.29-rc1

KVM Guest: 
Ubuntu 8.10
2.6.27-9-server

Text of Guest Boot Panic:

Boot from (hd0,0) ext3   cd532b94-1a97-4337-bfe9-75e699839bab
Starting up ...
[    3.290000] Stuck ??
[    3.320000] BUG: unable to handle kernel NULL pointer dereference at
0000000000000018
[    3.320000] IP: [<ffffffff802e35de>] kmem_cache_create+0x7e/0x1a0
[    3.320000] PGD 0
[    3.320000] Oops: 0002 [1] SMP
[    3.320000] CPU 0
[    3.320000] Modules linked in:
[    3.320000] Pid: 1, comm: swapper Tainted: G S        2.6.27-9-server #1
[    3.320000] RIP: 0010:[<ffffffff802e35de>]  [<ffffffff802e35de>]
kmem_cache_create+0x7e/0x1a0
[    3.320000] RSP: 0018:ffff88081cc7be50  EFLAGS: 00010293
[    3.320000] RAX: 0000000000000080 RBX: ffffffff806df710 RCX:
0000000000000001
[    3.320000] RDX: 0000000000000000 RSI: 0000000000000001 RDI:
0000000000000001
[    3.320000] RBP: ffff88081cc7be90 R08: 0000000000000040 R09:
ffffffff806e1e18
[    3.320000] R10: ffff88081ccfdc00 R11: 0000000000000400 R12:
0000000000000080
[    3.320000] R13: 0000000000000000 R14: 0000000000000000 R15:
ffffffff805f9c69
[    3.320000] FS:  0000000000000000(0000) GS:ffffffff806e1a80(0000)
knlGS:0000000000000000
[    3.320000] CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
[    3.320000] CR2: 0000000000000018 CR3: 0000000000201000 CR4:
00000000000006e0
[    3.320000] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[    3.320000] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
0000000000000400
[    3.320000] Process swapper (pid: 1, threadinfo ffff88081cc7a000, task
ffff88081cc80000)
[    3.320000] Stack:  ffffffff80743eb2 0000000000000000 0000000000042000
ffffffff80784848
[    3.320000]  ffffffff807449ac 0000000000000000 0000000000093360
0000000000000000
[    3.320000]  ffff88081cc7bea0 ffffffff80744a09 ffff88081cc7bf10
ffffffff8020a041
[    3.320000] Call Trace:
[    3.320000]  [<ffffffff80743eb2>] ? init_pipe_fs+0x0/0x56
[    3.320000]  [<ffffffff807449ac>] ? eventpoll_init+0x0/0x8a
[    3.320000]  [<ffffffff80744a09>] eventpoll_init+0x5d/0x8a
[    3.320000]  [<ffffffff8020a041>] do_one_initcall+0x41/0x170
[    3.320000]  [<ffffffff8029ff09>] ? register_irq_proc+0x19/0xf0
[    3.320000]  [<ffffffff80330000>] ? load_elf_binary+0xc70/0x11c0
[    3.320000]  [<ffffffff807207fb>] kernel_init+0xd2/0x128
[    3.320000]  [<ffffffff802444d7>] ? schedule_tail+0x27/0x70
[    3.320000]  [<ffffffff80213c99>] child_rip+0xa/0x11
[    3.320000]  [<ffffffff80720729>] ? kernel_init+0x0/0x128
[    3.320000]  [<ffffffff80213c8f>] ? child_rip+0x0/0x11
[    3.320000] 
[    3.320000] 
[    3.320000] Code: 83 40 7c 01 8b 40 0c bf ff ff ff ff 44 39 e0 41 0f 4e
c4 89 43 0c eb 16 0f 1f 44 00 00 48 63 c7 48 8b 94 c3 f0 02 00 00 8b 43 0c
<89> 42 18 48 c7 c6 18 1e 6e 80 e8 b3 ed 0b 00 83 f8 3f 89 c7 7e
[    3.320000] RIP  [<ffffffff802e35de>] kmem_cache_create+0x7e/0x1a0
[    3.320000]  RSP <ffff88081cc7be50>
[    3.320000] CR2: 0000000000000018
[    3.320000] ---[ end trace 4eaa2a86a8e2da22 ]---
[    3.320000] Kernel panic - not syncing: Attempted to kill init!