Re: xm pause hangs up on Xen 4.0]

[Keir Fraser <keir.fraser@eu.citrix.com>]

This might be a side effect of using 4.0, blktap2, and a very new pv_ops
kernel. blktap2 support added code to pause/unpause blktap2 devices on the
domain pause/unpause path (I don't know why -- no other backend device type
needs such special treatment) -- it looks like that which is hanging on this
particular dom0 kernel. Try not using blktap2, or try an older pv_ops
kernel, or even try removign the obvious blktap2-specific code from the
pause and unpause methods in xen/xend/XendDomainInfo.py in xend.

 -- Keir

On 26/04/2010 11:44, "Leandro Neves de Oliveira"
<leandro-xen@dataworks.com.br> wrote:

> 
> I've trying Xen 4.0 on Ubuntu 9.10. (xen-test-ubuntu
> 2.6.32.11-xen0-amd64 #8 SMP x86_64), but i have some problem
> with xm pause command. It hangs.
>                 
> After about 120 seconds I have the follow syslog message:
>                 
>         [58921.334917] INFO: task xend:27739 blocked for more than 120
>         seconds.
>         [58921.334923] "echo 0
>> /proc/sys/kernel/hung_task_timeout_secs"
>         disables this message.
>         [58921.334926] xend          D 0000000000007ac0     0 27739
>         22471
>         0x00000000
>         [58921.334930]  ffff880039cebc08 0000000000000282
>         0000000000000002
>         ffffffff809d8240
>         [58921.334934]  00000000000080d0 00000c0c00000000
>         ffff88006f451c18
>         ffff88006f451c00
>         [58921.334937]  ffff88000bf7c768 ffff880039cebfd8
>         0000000000007b28
>         ffff88000bf7c768
>         [58921.334941] Call Trace:
>         [58921.334950]  [<ffffffff8022affc>] ? __enqueue_entity
>         +0x7c/0x80
>         [58921.334953]  [<ffffffff8023523c>] ? enqueue_entity+0xbc/0x350
>         [58921.334958]  [<ffffffff8072a53d>] schedule_timeout
>         +0x1fd/0x2d0
>         [58921.334961]  [<ffffffff80237951>] ? dequeue_entity
>         +0x1a1/0x1e0
>         [58921.334964]  [<ffffffff8022ae9b>] ? __dequeue_entity
>         +0x2b/0x50
>         [58921.334967]  [<ffffffff80237758>] ? set_next_entity+0x88/0x90
>         [58921.334970]  [<ffffffff8072a160>] wait_for_common+0x100/0x200
>         [58921.334973]  [<ffffffff80230200>] ? default_wake_function
>         +0x0/0x10
>         [58921.334977]  [<ffffffff80306d70>] ? ifind_fast+0x70/0xc0
>         [58921.334980]  [<ffffffff8072a2f8>] wait_for_completion
>         +0x18/0x20
>         [58921.334985]  [<ffffffff8035b8b8>] sysfs_addrm_finish
>         +0x298/0x2e0
>         [58921.334988]  [<ffffffff803593a6>] sysfs_hash_and_remove
>         +0x56/0x80
>         [58921.334992]  [<ffffffff8035a170>] sysfs_remove_file+0x10/0x20
>         [58921.334996]  [<ffffffff804e26b2>] device_remove_file
>         +0x12/0x20
>         [58921.335000]  [<ffffffff80512d27>] blktap_sysfs_pause_device
>         +0xe7/0x130
>         [58921.335003]  [<ffffffff804e177b>] dev_attr_store+0x1b/0x20
>         [58921.335006]  [<ffffffff80359c30>] sysfs_write_file+0xe0/0x160
>         [58921.335011]  [<ffffffff802ef698>] vfs_write+0xb8/0x1a0
>         [58921.335014]  [<ffffffff8072f0b2>] ? do_page_fault+0x1a2/0x370
>         [58921.335017]  [<ffffffff802f013c>] sys_write+0x4c/0x80
>         [58921.335021]  [<ffffffff80209bc8>] system_call_fastpath
>         +0x16/0x1b
>         [58921.335024]  [<ffffffff80209b60>] ? system_call+0x0/0x52
>                 
>                 
> Then, after a "xm destroy" command, xen doesn't work more. If I
> do "xm create windowsXP.cfg" again I received the follow message:
>               
> Using config file "./windowsXP.cfg".
> Error: Device 768 (tap2) could not be connected. Hotplug scripts not
> working.
>                 
> No substancial messages at xend.log or xend-debug.log.
>                 
>                 
> The same windows machine is working on a 2.6.31.8-xen0-amd64 #1
> SMP Tue
> Apr 6 17:04:48 BRT 2010 x86_64 with Xen 3.4.2.
>                 
> Someone can help me?
>                 
> Att,
>