Re: [Xen-devel] netback Oops then xenwatch stuck in D state

["Christopher S. Aker" <caker@xxxxxxxxxxxx>]

On Feb 1, 2013, at 8:01 PM, Wei Liu wrote:
> Just happened to fix a bug related to OOM not getting handled correctly.
> 
> http://lists.xen.org/archives/html/xen-devel/2013-01/msg02549.html

Rebuilt with the above patch, and have now hit this:

BUG: unable to handle kernel NULL pointer dereference at 00000000000008b8
IP: [<ffffffff81011dda>] xen_spin_lock_flags+0x3a/0x80
PGD 82c63067 PUD 82640067 PMD 0 
Oops: 0002 [#1] SMP 
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
CPU 0 
Pid: 1545, comm: netback/0 Not tainted 3.7.6-1-x86_64 #1 Supermicro X8DT6/X8DT6
RIP: e030:[<ffffffff81011dda>]  [<ffffffff81011dda>] 
xen_spin_lock_flags+0x3a/0x80
RSP: e02b:ffff880083693b58  EFLAGS: 00010006
RAX: 0000000000000400 RBX: 00000000000008b8 RCX: 0000000000dabda3
RDX: 0000000000000001 RSI: 0000000000000210 RDI: 00000000000008b8
RBP: ffff880083693b78 R08: 000000000000005f R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000001
R13: 0000000000000200 R14: 0000000000000400 R15: 0000000000dabda3
FS:  00007f19e7f69700(0000) GS:ffff880100600000(0000) knlGS:0000000000000000
CS:  e033 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000000000008b8 CR3: 0000000082413000 CR4: 0000000000002660
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process netback/0 (pid: 1545, threadinfo ffff880083692000, task 
ffff880083d2e740)
Stack:
 0000000000000210 00000000000008b8 ffff88005f807700 ffff88005f8077d8
 ffff880083693b98 ffffffff817605da 0000000000000000 00000000000008b8
 ffff880083693bd8 ffffffff8154446f ffff88005f807000 0000000000000000
Call Trace:
 [<ffffffff817605da>] _raw_spin_lock_irqsave+0x2a/0x40
 [<ffffffff8154446f>] xen_netbk_schedule_xenvif+0x8f/0x100
 [<ffffffff81544505>] xen_netbk_check_rx_xenvif+0x25/0x60
 [<ffffffff815445eb>] netbk_tx_err+0x5b/0x70
 [<ffffffff8154518c>] xen_netbk_tx_build_gops+0xb8c/0xbc0
 [<ffffffff816357b9>] ? enqueue_to_backlog+0xb9/0x190
 [<ffffffff8100140a>] ? xen_hypercall_event_channel_op+0xa/0x20
 [<ffffffff81639284>] ? netif_rx+0x44/0xe0
 [<ffffffff81015410>] ? do_softirq+0x50/0xa0
 [<ffffffff815452af>] xen_netbk_kthread+0xef/0x9d0
 [<ffffffff81080150>] ? finish_task_switch+0x60/0xd0
 [<ffffffff810720c0>] ? wake_up_bit+0x40/0x40
 [<ffffffff815451c0>] ? xen_netbk_tx_build_gops+0xbc0/0xbc0
 [<ffffffff81071a06>] kthread+0xc6/0xd0
 [<ffffffff810037b9>] ? xen_end_context_switch+0x19/0x20
 [<ffffffff81071940>] ? kthread_freezable_should_stop+0x70/0x70
 [<ffffffff8176847c>] ret_from_fork+0x7c/0xb0
 [<ffffffff81071940>] ? kthread_freezable_should_stop+0x70/0x70
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 
RIP  [<ffffffff81011dda>] xen_spin_lock_flags+0x3a/0x80
 RSP <ffff880083693b58>
CR2: 00000000000008b8
---[ end trace db6edd7c15bd6503 ]---

Plenty of RAM free (over 900M).  Same symptoms: now xenwatch is in D state and 
hotplug stuff is timing out.

-Chris


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