[Xen-devel] Soft lockup/Time went backwards in latest unstable

[Derek Murray <Derek.Murray@xxxxxxxxxxxx>]

I'm running Xen on a Lenovo Thinkpad T60p, based on an Intel Core Duo  
T2500 processor. Since upgrading to the latest unstable, the console  
is filled with "Time went backwards" messages. An example:
Timer ISR/1: Time went backwards: delta=-52249969 delta_cpu=67750031  
shadow=197099583154 off=168169166 processed=197320000000  
cpu_processed=197200000000
0: 197310000000
1: 197200000000
Timer ISR/1: Time went backwards: delta=-76271442 delta_cpu=73728558  
shadow=197099583154 off=224147323 processed=197400000000  
cpu_processed=197250000000
0: 197390000000
1: 197250000000
Timer ISR/1: Time went backwards: delta=-90285138 delta_cpu=69714862  
shadow=197099583154 off=280133627 processed=197470000000  
cpu_processed=197310000000
0: 197460000000
1: 197310000000

In addition, I noticed a soft lockup, with the following stack trace:

BUG: soft lockup detected on CPU#0!
[<c014ef57>] softlockup_tick+0x97/0xd0
[<c01097ea>] timer_interrupt+0x2fa/0x6b0
[<ee06a875>] sd_rw_intr+0x75/0x2e0 [sd_mod]
[<c014f2c3>] handle_IRQ_event+0x33/0xa0
[<c014f3d8>] __do_IRQ+0xa8/0x120
[<c010733f>] do_IRQ+0x3f/0xa0
[<c0244b4e>] evtchn_do_upcall+0xbe/0x100
[<c010580d>] hypervisor_callback+0x3d/0x48
[<c020007b>] cfb_imageblit+0x10b/0x530
[<c0243f5a>] force_evtchn_callback+0xa/0x10
[<ee07c63f>] acpi_processor_idle+0x26d/0x422 [processor]
[<ee07c3d2>] acpi_processor_idle+0x0/0x422 [processor]
[<c01035a1>] cpu_idle+0x71/0xd0
[<c03b482d>] start_kernel+0x39d/0x480
[<c03b4220>] unknown_bootoption+0x0/0x270

and

BUG: soft lockup detected on CPU#1!
[<c014ef57>] softlockup_tick+0x97/0xd0
[<c01097ea>] timer_interrupt+0x2fa/0x6b0
[<c014f2c3>] handle_IRQ_event+0x33/0xa0
[<c014f3d8>] __do_IRQ+0xa8/0x120
[<c010733f>] do_IRQ+0x3f/0xa0
[<c0107344>] do_IRQ+0x44/0xa0
[<c0244b4e>] evtchn_do_upcall+0xbe/0x100
[<c010580d>] hypervisor_callback+0x3d/0x48
[<c0243f5a>] force_evtchn_callback+0xa/0x10
[<ee07c63f>] acpi_processor_idle+0x26d/0x422 [processor]
[<ee07c3d2>] acpi_processor_idle+0x0/0x422 [processor]
[<c01035a1>] cpu_idle+0x71/0xd0

It appears that this issue was introduced in Xen 3.0.4, as this  
exhibits the same issue. 3.0.3 works fine. The version of unstable  
that I was using previously (which did not have this issue) worked  
with kernel version 2.6.16.29; 3.0.4 comes with 2.6.16.33. Could the  
problem have been introduced in the move from 2.6.16.29 to 2.6.16.33  
(or somewhere in between)?
I'm not sure how to go about handling this apparent bug, though I am  
prepared to offer any assistance necessary in fixing it. I've  
attached my xm dmesg, in case that's any help.
Thanks in advance.

Regards,

Derek Murray.

Attachment: xen_dmesg
Description: Binary data

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