Re: netback Oops then xenwatch stuck in D state

["Christopher S. Aker" <caker@theshore.net>]

On 2/12/13 4:58 AM, Ian Campbell wrote:
> Have you applied the XSA-39 fixes to this kernel?

Yes!  When I rebuilt with Wei's suggested patch for my original 
netback/xenwatch problem I also brought us up to date with XSA patches.

We just hit the same (new) problem on another machine, and looking at 
the BUG with more kernel output context gives a giant clue:

Feb 12 20:30:54: IPv6: ADDRCONF(NETDEV_UP): vif21.0: link is not ready
Feb 12 20:30:54: device vif21.0 entered promiscuous mode
Feb 12 20:30:56: xen-blkback:ring-ref 8, event-channel 31, protocol 2 
(x86_32-abi)
Feb 12 20:30:56: xen-blkback:ring-ref 9, event-channel 32, protocol 2 
(x86_32-abi)
Feb 12 20:30:56: IPv6: ADDRCONF(NETDEV_CHANGE): vif21.0: link becomes ready
Feb 12 20:30:56: br0: port 5(vif21.0) entered forwarding state
Feb 12 20:30:56: br0: port 5(vif21.0) entered forwarding state
Feb 12 20:30:58: br0: port 5(vif21.0) entered forwarding state
Feb 12 20:34:12: vif vif-21-0 vif21.0: Frag is bigger than frame.
Feb 12 20:34:12: vif vif-21-0 vif21.0: fatal error; disabling device 
<--------------
Feb 12 20:34:12: BUG: unable to handle kernel NULL pointer dereference 
at 00000000000008b8
Feb 12 20:34:12: IP: [<ffffffff81011dda>] xen_spin_lock_flags+0x3a/0x80
Feb 12 20:34:12: PGD 0
Feb 12 20:34:12: Oops: 0002 [#1] SMP
Feb 12 20:34:12: Modules linked in: ebt_comment ebt_arp ebt_set 
ebt_limit ebt_ip6 ebt_ip ip_set_hash_net ip_set ebtable_nat xen_gntdev 
bonding ebtable_filter e1000e
Feb 12 20:34:12: CPU 3
Feb 12 20:34:12: Pid: 1548, comm: netback/3 Not tainted 3.7.6-1-x86_64 
#1 Supermicro X8DT6/X8DT6
Feb 12 20:34:12: RIP: e030:[<ffffffff81011dda>]  [<ffffffff81011dda>] 
xen_spin_lock_flags+0x3a/0x80
Feb 12 20:34:12: RSP: e02b:ffff880083681b58  EFLAGS: 00010006
Feb 12 20:34:12: RAX: 0000000000000400 RBX: 00000000000008b8 RCX: 
0000000000000663
Feb 12 20:34:12: RDX: 0000000000000001 RSI: 0000000000000210 RDI: 
00000000000008b8
Feb 12 20:34:12: RBP: ffff880083681b78 R08: 000000000000000d R09: 
0000000000000000
Feb 12 20:34:12: R10: 0000000000000001 R11: 0000000000000001 R12: 
0000000000000001
Feb 12 20:34:12: R13: 0000000000000200 R14: 0000000000000400 R15: 
0000000000000663
Feb 12 20:34:12: FS:  00007f2bc1fb2700(0000) GS:ffff8801006c0000(0000) 
knlGS:0000000000000000
Feb 12 20:34:12: CS:  e033 DS: 0000 ES: 0000 CR0: 000000008005003b
Feb 12 20:34:12: CR2: 00000000000008b8 CR3: 0000000001c0b000 CR4: 
0000000000002660
Feb 12 20:34:12: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 
0000000000000000
Feb 12 20:34:12: DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 
0000000000000400
Feb 12 20:34:12: Process netback/3 (pid: 1548, threadinfo 
ffff880083680000, task ffff8800837ec9c0)
Feb 12 20:34:12: Stack:
Feb 12 20:34:12: 0000000000000210 00000000000008b8 ffff880003baa700 
ffff880003baa7d8
Feb 12 20:34:12: ffff880083681b98 ffffffff817605da 0000000000000000 
00000000000008b8
Feb 12 20:34:12: ffff880083681bd8 ffffffff8154446f ffff880003baa000 
0000000000000000
Feb 12 20:34:12: Call Trace:
Feb 12 20:34:12: [<ffffffff817605da>] _raw_spin_lock_irqsave+0x2a/0x40
Feb 12 20:34:12: [<ffffffff8154446f>] xen_netbk_schedule_xenvif+0x8f/0x100
Feb 12 20:34:12: [<ffffffff81544505>] xen_netbk_check_rx_xenvif+0x25/0x60
Feb 12 20:34:12: [<ffffffff815445eb>] netbk_tx_err+0x5b/0x70
Feb 12 20:34:12: [<ffffffff8154518c>] xen_netbk_tx_build_gops+0xb8c/0xbc0
Feb 12 20:34:12: [<ffffffff81012880>] ? __switch_to+0x160/0x4f0
Feb 12 20:34:12: [<ffffffff810891b8>] ? idle_balance+0xf8/0x150
Feb 12 20:34:12: [<ffffffff81080150>] ? finish_task_switch+0x60/0xd0
Feb 12 20:34:12: [<ffffffff8175f7b4>] ? __schedule+0x394/0x750
Feb 12 20:34:12: [<ffffffff815452af>] xen_netbk_kthread+0xef/0x9d0
Feb 12 20:34:12: [<ffffffff81080150>] ? finish_task_switch+0x60/0xd0
Feb 12 20:34:12: [<ffffffff810720c0>] ? wake_up_bit+0x40/0x40
Feb 12 20:34:12: [<ffffffff815451c0>] ? xen_netbk_tx_build_gops+0xbc0/0xbc0
Feb 12 20:34:12: [<ffffffff81071a06>] kthread+0xc6/0xd0
Feb 12 20:34:12: [<ffffffff810037b9>] ? xen_end_context_switch+0x19/0x20
Feb 12 20:34:12: [<ffffffff81071940>] ? 
kthread_freezable_should_stop+0x70/0x70
Feb 12 20:34:12: [<ffffffff8176847c>] ret_from_fork+0x7c/0xb0
Feb 12 20:34:12: [<ffffffff81071940>] ? 
kthread_freezable_should_stop+0x70/0x70
Feb 12 20:34:12: Code: 24 08 4c 89 6c 24 10 4c 89 74 24 18 49 89 f5 48 
89 fb 41 81 e5 00 02 00 00 41 bc 01 00 00 00 41 be 00 04 00 00 44 89 f0 
44 89 e2 <86> 13 84 d2 74 0b f3 90 80 3b 00 74 f3 ff c8 75 f5 84 d2 75 15
Feb 12 20:34:12: RIP  [<ffffffff81011dda>] xen_spin_lock_flags+0x3a/0x80
Feb 12 20:34:12: RSP <ffff880083681b58>
Feb 12 20:34:12: CR2: 00000000000008b8
Feb 12 20:34:12: ---[ end trace ae243211c8c8cba5 ]---

https://lkml.org/lkml/2013/2/12/575 - "xen/netback: shut down the ring 
if it contains garbage"

-Chris