Re: Linux 3.13: BUG: soft lockup - CPU#1 stuck for 22s! [qemu-kvm:2653]

["Jason S. Wagner" <jasonswagner@gmail.com>]

Hi Paolo,

Hmm, the symptoms don't seem to match entirely -- I already am on a 
64-bit kernel.  I didn't recognize high CPU utilization, but I also 
admit I wasn't looking for it.  Leaving the instance running doesn't 
eventually hang my system, but it did cause strange system behavior.

Some apps would stall while launching, others that were already running 
would not be able to perform some operations.  Nautilus, for example, 
couldn't render directory views and would display "Loading..." in the 
corner of the window.  I assume this is because CPU1 is locked by KVM.  
Stopping the instance would allow any pending operations to complete; 
apps stuck launching all started at once, and Nautilus was again able 
to show me my local disk.

I believe it also prevented clean shutdown.  My keyboard's LEDs would 
stop responding and after allowing a reasonable amount of time, I 
reached for the reset button several times.

I'll reinstall Linux 3.13 tonight and try to confirm these details.

On Wed, Mar 12, 2014 at 7:08 AM, Paolo Bonzini <pbonzini@redhat.com> 
wrote:
> Il 11/03/2014 21:01, Jason S. Wagner ha scritto:
>> Hi all,
>> 
>> Over the weekend, Linux 3.13.6 was installed on my machine. When I
>> started gnome-boxes on Monday morning, my VM halted during boot. 
>> Only a
>> portion of the VESA BIOS init output was displayed on-screen before 
>> the
>> halt. Backtraces occasionally appeared in dmesg
>> (http://pastebin.com/uUiNLmJ6). Some other programs were prevented 
>> from
>> performing some tasks while the VM was running.
>> 
>> While investigating, I was directed to an earlier KVM bug report
>> (https://lkml.org/lkml/2014/2/11/487). I downgraded to Linux 3.12.9 
>> and
>> rebooted, and now my VM is starting. Unfortunately, I'm very new to
>> Linux, so I'm not sure what the next steps would be.
> 
> Yeah, it's quite likely this is the issue you're facing.
> 
> And the author of the report at 
> http://www.spinics.net/lists/kvm/msg100196.html also told me 
> privately that 64-bit kernel made it go away, so it's also likely to 
> be the same thing.  Thomas, do you also see a "soft lockup" message?
> 
> Paolo