Re: Re: DomU lockups after resume from S3 on Core i5 processors

[Joanna Rutkowska <joanna@invisiblethingslab.com>]

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On 07/05/10 23:28, Joanna Rutkowska wrote:
> On 07/05/10 12:38, Joanna Rutkowska wrote:
>> I'm experiencing very reproducible DomU lockups that occur after I
>> resume the system from an S3 sleep. Strangely this seem to happen only
>> on my Core i5 systems (tested on two different machines), but not on
>> older Core 2 Duo systems.
>>
>> Usually this causes the apps (e.g. Firefox) running in DomUs to become
>> unresponsive, but sometimes I see that some very limited functionality
>> of the app is still available (e.g. I can open/close Tabs in Firefox,
>> but cannot do much anything more). Also, when I log in to the DomU via
>> xm console, I usually can see the login prompt, can enter the username,
>> but then the console hangs.
>>
>> I tried to attach to such a hanged DomU using gdbserver-xen, but when I
>> subsequently try to attach to the server from gdb (via the target
>> 127.0.0.1:9999 command), my gdb segfaults (how funny!).
>>
>> I'm running Xen 3.4.3, and fairly recent pvops0 kernel in DomU. In Dom0
>> I run 2.6.34-xenlinux kernel (opensuse patches), but I doubt it is
>> relevant in any way.
>>
>> This seems like a scheduling problem, and, because it seems to affect
>> Core i5 processors, but not Core 2 Duos, it might have something to do
>> with Hyperthreading perhaps?
>>
> Ok, finally got the gdbsever working. This is the backtrace I get when
> attaching to a lockedup DomU after resume:
> 
> #0  0xffffffff810093aa in ?? ()
> #1  0xffffffff8168be18 in ?? ()
> #2  0xffff880003a21600 in ?? ()
> #3  0xffffffff8100ee63 in HYPERVISOR_sched_op ()
>     at
> /usr/src/debug/kernel-2.6.32/linux-2.6.32.x86_64/arch/x86/include/asm/xen/hypercall.h:292
> #4  xen_safe_halt () at arch/x86/xen/irq.c:104
> #5  0xffffffff8100c33e in raw_safe_halt () at
> /usr/src/debug/kernel-2.6.32/linux-2.6.32.x86_64/arch/x86/include/asm/paravirt.h:110
> #6  xen_idle () at arch/x86/xen/setup.c:193
> #7  0xffffffff81011cdd in cpu_idle () at arch/x86/kernel/process_64.c:143
> #8  0xffffffff8144b997 in rest_init () at init/main.c:445
> #9  0xffffffff81824ddc in start_kernel () at init/main.c:695
> #10 0xffffffff818242c1 in x86_64_start_reservations
> (real_mode_data=<value optimized out>) at arch/x86/kernel/head64.c:123
> #11 0xffffffff81828160 in xen_start_kernel () at
> arch/x86/xen/enlighten.c:1300
> #12 0xffffffff838f3000 in ?? ()
> #13 0xffffffff838f4000 in ?? ()
> #14 0xffffffff838f5000 in ?? ()
> 
> Any ideas?
> 
... and when I disabled Hyperthreading in BIOS, the problem seems to
gone. Obviously this is not a desired solution...

joanna.


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