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

[Joanna Rutkowska <joanna@invisiblethingslab.com>]

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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?

joanna.


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