Re: [Xen-devel] crash in csched_load_balance after xl vcpu-pin

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 11.04.18 at 23:31, <raistlin@xxxxxxxx> wrote:
> Il Mer 11 Apr 2018, 22:48 Olaf Hering <olaf@xxxxxxxxx> ha scritto:
> 
>> On Wed, Apr 11, Dario Faggioli wrote:
>>
>> > It will crash, again, possibly with the same stack trace, but I think
>> > it's worth a try.
>>
>>     BUG_ON(__vcpu_on_runq(CSCHED_VCPU(vc)));
>>
>> (XEN) Xen BUG at sched_credit.c:876
>> (XEN) ----[ Xen-4.11.20180410T125709.50f8ba84a5-7.bug1087289_411  x86_64
>> debug=y   Not tainted ]----
>> (XEN) CPU:    108
>> (XEN) RIP:    e008:[<ffff82d080229ab4>]
>> sched_credit.c#csched_vcpu_migrate+0x27/0x54
>> (XEN) RFLAGS: 0000000000010006   CONTEXT: hypervisor
>> ...
>> (XEN) Xen call trace:
>> (XEN)    [<ffff82d080229ab4>] sched_credit.c#csched_vcpu_migrate+0x27/0x54
>> (XEN)    [<ffff82d080236348>] schedule.c#vcpu_move_locked+0xbb/0xc2
>> (XEN)    [<ffff82d08023764c>] schedule.c#vcpu_migrate+0x226/0x25b
>> (XEN)    [<ffff82d080239367>] context_saved+0x95/0x9c
>> (XEN)    [<ffff82d08027797d>] context_switch+0xe66/0xeb0
>> (XEN)    [<ffff82d080236943>] schedule.c#schedule+0x5f4/0x627
>> (XEN)    [<ffff82d080239f15>] softirq.c#__do_softirq+0x85/0x90
>> (XEN)    [<ffff82d080239f6a>] do_softirq+0x13/0x15
>> (XEN)    [<ffff82d08031f5db>] vmx_asm_do_vmentry+0x2b/0x30
>>
> 
> So, really *exactly* the same. Ok, thanks.
> 
> I think that from "CONTEXT: hypervisor", we can tell that the current vcpu
> is the idle one,

No, not that fact - the context shown is strictly dependent on where
the exception occurred (that'll always be in the hypervisor for
BUG() and WARN()). The absence of a dXvY is telling you that it's
the idle vCPU we're on. See _show_registers().

Jan


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