* Re: [xen-unstable test] 113562: regressions - FAIL
2017-09-18 10:15 ` George Dunlap
@ 2017-09-18 10:26 ` Wei Liu
2017-09-18 10:32 ` George Dunlap
2017-09-18 10:29 ` George Dunlap
2017-09-18 10:46 ` Roger Pau Monné
2 siblings, 1 reply; 14+ messages in thread
From: Wei Liu @ 2017-09-18 10:26 UTC (permalink / raw)
To: George Dunlap
Cc: xen-devel, Wei Liu, George Dunlap, Dario Faggioli,
osstest service owner, Roger Pau Monné
On Mon, Sep 18, 2017 at 11:15:03AM +0100, George Dunlap wrote:
> On 09/18/2017 10:45 AM, Roger Pau Monné wrote:
> > On Mon, Sep 18, 2017 at 10:37:58AM +0100, Wei Liu wrote:
> >> On Mon, Sep 18, 2017 at 08:36:03AM +0000, osstest service owner wrote:
> >>> flight 113562 xen-unstable real [real]
> >>> http://logs.test-lab.xenproject.org/osstest/logs/113562/
> >>>
> >>> Regressions :-(
> >>>
> >>> Tests which did not succeed and are blocking,
> >>> including tests which could not be run:
> >>> test-amd64-amd64-xl-credit2 15 guest-saverestore fail REGR. vs. 113387
> >>
> >> There appears to be a bug:
> >>
> >> http://logs.test-lab.xenproject.org/osstest/logs/113562/test-amd64-amd64-xl-credit2/serial-godello0.log
> >>
> >> Sep 18 01:14:28.803062 (XEN) Xen BUG at spinlock.c:47
> >
> > Seem to be caused because budget_lock is sometimes locked with irqsave
> > while others not.
>
> Just wondering where you're getting the budget lock from? The call
> stack in that link makes it look like it's the RCU clean-up triggering a
> domain destroy. (Haven't looked deeper into the specific line numbers.)
>
Looking at the backtrace I am not sure yet if budget_lock is the
culprit.
But, Xen does have a requirement to distinguish IRQ-safe lock and
IRQ-unsafe lock. The budget_lock violates that rule.
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^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [xen-unstable test] 113562: regressions - FAIL
2017-09-18 10:26 ` Wei Liu
@ 2017-09-18 10:32 ` George Dunlap
0 siblings, 0 replies; 14+ messages in thread
From: George Dunlap @ 2017-09-18 10:32 UTC (permalink / raw)
To: Wei Liu
Cc: George Dunlap, Dario Faggioli, xen-devel, osstest service owner,
Roger Pau Monné
On 09/18/2017 11:26 AM, Wei Liu wrote:
> On Mon, Sep 18, 2017 at 11:15:03AM +0100, George Dunlap wrote:
>> On 09/18/2017 10:45 AM, Roger Pau Monné wrote:
>>> On Mon, Sep 18, 2017 at 10:37:58AM +0100, Wei Liu wrote:
>>>> On Mon, Sep 18, 2017 at 08:36:03AM +0000, osstest service owner wrote:
>>>>> flight 113562 xen-unstable real [real]
>>>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/
>>>>>
>>>>> Regressions :-(
>>>>>
>>>>> Tests which did not succeed and are blocking,
>>>>> including tests which could not be run:
>>>>> test-amd64-amd64-xl-credit2 15 guest-saverestore fail REGR. vs. 113387
>>>>
>>>> There appears to be a bug:
>>>>
>>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/test-amd64-amd64-xl-credit2/serial-godello0.log
>>>>
>>>> Sep 18 01:14:28.803062 (XEN) Xen BUG at spinlock.c:47
>>>
>>> Seem to be caused because budget_lock is sometimes locked with irqsave
>>> while others not.
>>
>> Just wondering where you're getting the budget lock from? The call
>> stack in that link makes it look like it's the RCU clean-up triggering a
>> domain destroy. (Haven't looked deeper into the specific line numbers.)
>>
>
> Looking at the backtrace I am not sure yet if budget_lock is the
> culprit.
>
> But, Xen does have a requirement to distinguish IRQ-safe lock and
> IRQ-unsafe lock. The budget_lock violates that rule.
It looks that way at first glance, but actually it doesn't. :-)
All of the calls where the budget lock is grabbed without "_irqsave",
there is an ASSERT() previously that the per-scheduler private lock has
already been grabbed -- which, if true, means that irqs are already
disabled.
-George
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^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [xen-unstable test] 113562: regressions - FAIL
2017-09-18 10:15 ` George Dunlap
2017-09-18 10:26 ` Wei Liu
@ 2017-09-18 10:29 ` George Dunlap
2017-09-18 17:36 ` Dario Faggioli
2017-09-18 10:46 ` Roger Pau Monné
2 siblings, 1 reply; 14+ messages in thread
From: George Dunlap @ 2017-09-18 10:29 UTC (permalink / raw)
To: Roger Pau Monné, Wei Liu
Cc: George Dunlap, Dario Faggioli, xen-devel, osstest service owner
On 09/18/2017 11:15 AM, George Dunlap wrote:
> On 09/18/2017 10:45 AM, Roger Pau Monné wrote:
>> On Mon, Sep 18, 2017 at 10:37:58AM +0100, Wei Liu wrote:
>>> On Mon, Sep 18, 2017 at 08:36:03AM +0000, osstest service owner wrote:
>>>> flight 113562 xen-unstable real [real]
>>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/
>>>>
>>>> Regressions :-(
>>>>
>>>> Tests which did not succeed and are blocking,
>>>> including tests which could not be run:
>>>> test-amd64-amd64-xl-credit2 15 guest-saverestore fail REGR. vs. 113387
>>>
>>> There appears to be a bug:
>>>
>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/test-amd64-amd64-xl-credit2/serial-godello0.log
>>>
>>> Sep 18 01:14:28.803062 (XEN) Xen BUG at spinlock.c:47
>>
>> Seem to be caused because budget_lock is sometimes locked with irqsave
>> while others not.
>
> Just wondering where you're getting the budget lock from? The call
> stack in that link makes it look like it's the RCU clean-up triggering a
> domain destroy. (Haven't looked deeper into the specific line numbers.)
In fact in this case it appears to be the xfree(sdom->repl_timer) in
csched2_free_domdata() being inside the critical section (which disables
irqs); there's actually an xfree() right in that function outside the
critical section.
-George
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https://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [xen-unstable test] 113562: regressions - FAIL
2017-09-18 10:29 ` George Dunlap
@ 2017-09-18 17:36 ` Dario Faggioli
0 siblings, 0 replies; 14+ messages in thread
From: Dario Faggioli @ 2017-09-18 17:36 UTC (permalink / raw)
To: George Dunlap, Roger Pau Monné, Wei Liu
Cc: George Dunlap, xen-devel, osstest service owner
[-- Attachment #1.1: Type: text/plain, Size: 1672 bytes --]
On Mon, 2017-09-18 at 11:29 +0100, George Dunlap wrote:
> > > On Mon, Sep 18, 2017 at 10:37:58AM +0100, Wei Liu wrote:
> > > > On Mon, Sep 18, 2017 at 08:36:03AM +0000, osstest service owner
> > > > wrote:
> > > > > flight 113562 xen-unstable real [real]
> > > > > http://logs.test-lab.xenproject.org/osstest/logs/113562/
> > > > >
> > > > > Regressions :-(
> > > > >
> > > > > Tests which did not succeed and are blocking,
> > > > > including tests which could not be run:
> > > > > test-amd64-amd64-xl-credit2 15 guest-
> > > > > saverestore fail REGR. vs. 113387
> > > >
> > > > There appears to be a bug:
> > > >
> > > > http://logs.test-lab.xenproject.org/osstest/logs/113562/test-am
> > > > d64-amd64-xl-credit2/serial-godello0.log
> > > >
> > > > Sep 18 01:14:28.803062 (XEN) Xen BUG at spinlock.c:47
> > >
> In fact in this case it appears to be the xfree(sdom->repl_timer) in
> csched2_free_domdata() being inside the critical section (which
> disables
> irqs); there's actually an xfree() right in that function outside the
> critical section.
>
So, during the afternoon, there was an glitch here, in the local
network/NAS of my home office.
It took me a bit to fix it, and that delayed the work on the (trivial)
patch to fix this problem.
It's solved now, and I will work on and send the patch later (after
dinner).
Sorry again,
Dario
--
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
[-- Attachment #1.2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
[-- Attachment #2: Type: text/plain, Size: 127 bytes --]
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^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [xen-unstable test] 113562: regressions - FAIL
2017-09-18 10:15 ` George Dunlap
2017-09-18 10:26 ` Wei Liu
2017-09-18 10:29 ` George Dunlap
@ 2017-09-18 10:46 ` Roger Pau Monné
2017-09-18 11:05 ` George Dunlap
2 siblings, 1 reply; 14+ messages in thread
From: Roger Pau Monné @ 2017-09-18 10:46 UTC (permalink / raw)
To: George Dunlap
Cc: George Dunlap, Dario Faggioli, xen-devel, Wei Liu,
osstest service owner
On Mon, Sep 18, 2017 at 11:15:03AM +0100, George Dunlap wrote:
> On 09/18/2017 10:45 AM, Roger Pau Monné wrote:
> > On Mon, Sep 18, 2017 at 10:37:58AM +0100, Wei Liu wrote:
> >> On Mon, Sep 18, 2017 at 08:36:03AM +0000, osstest service owner wrote:
> >>> flight 113562 xen-unstable real [real]
> >>> http://logs.test-lab.xenproject.org/osstest/logs/113562/
> >>>
> >>> Regressions :-(
> >>>
> >>> Tests which did not succeed and are blocking,
> >>> including tests which could not be run:
> >>> test-amd64-amd64-xl-credit2 15 guest-saverestore fail REGR. vs. 113387
> >>
> >> There appears to be a bug:
> >>
> >> http://logs.test-lab.xenproject.org/osstest/logs/113562/test-amd64-amd64-xl-credit2/serial-godello0.log
> >>
> >> Sep 18 01:14:28.803062 (XEN) Xen BUG at spinlock.c:47
> >
> > Seem to be caused because budget_lock is sometimes locked with irqsave
> > while others not.
>
> Just wondering where you're getting the budget lock from? The call
> stack in that link makes it look like it's the RCU clean-up triggering a
> domain destroy. (Haven't looked deeper into the specific line numbers.)
Just skimmed over the commit and jumped into conclusions too fast. As
you mention later the issue is calling xfree with interrupts disabled
in csched2_free_domdata.
I would rather prefer budget_lock to be always locked with the
irqsave/restore variant to make what you mention above more obvious,
but that's just a question of taste.
Roger.
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https://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [xen-unstable test] 113562: regressions - FAIL
2017-09-18 10:46 ` Roger Pau Monné
@ 2017-09-18 11:05 ` George Dunlap
2017-09-18 11:11 ` Juergen Gross
2017-09-18 11:19 ` Jan Beulich
0 siblings, 2 replies; 14+ messages in thread
From: George Dunlap @ 2017-09-18 11:05 UTC (permalink / raw)
To: Roger Pau Monné
Cc: xen-devel, Wei Liu, George Dunlap, Dario Faggioli,
osstest service owner, Jan Beulich
On 09/18/2017 11:46 AM, Roger Pau Monné wrote:
> On Mon, Sep 18, 2017 at 11:15:03AM +0100, George Dunlap wrote:
>> On 09/18/2017 10:45 AM, Roger Pau Monné wrote:
>>> On Mon, Sep 18, 2017 at 10:37:58AM +0100, Wei Liu wrote:
>>>> On Mon, Sep 18, 2017 at 08:36:03AM +0000, osstest service owner wrote:
>>>>> flight 113562 xen-unstable real [real]
>>>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/
>>>>>
>>>>> Regressions :-(
>>>>>
>>>>> Tests which did not succeed and are blocking,
>>>>> including tests which could not be run:
>>>>> test-amd64-amd64-xl-credit2 15 guest-saverestore fail REGR. vs. 113387
>>>>
>>>> There appears to be a bug:
>>>>
>>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/test-amd64-amd64-xl-credit2/serial-godello0.log
>>>>
>>>> Sep 18 01:14:28.803062 (XEN) Xen BUG at spinlock.c:47
>>>
>>> Seem to be caused because budget_lock is sometimes locked with irqsave
>>> while others not.
>>
>> Just wondering where you're getting the budget lock from? The call
>> stack in that link makes it look like it's the RCU clean-up triggering a
>> domain destroy. (Haven't looked deeper into the specific line numbers.)
>
> Just skimmed over the commit and jumped into conclusions too fast. As
> you mention later the issue is calling xfree with interrupts disabled
> in csched2_free_domdata.
>
> I would rather prefer budget_lock to be always locked with the
> irqsave/restore variant to make what you mention above more obvious,
> but that's just a question of taste.
I *think* at some point in the past we had a discussion about this and
someone (perhaps Jan?) said if we always know the irqs are disabled we
shouldn't call the _irqsave() version, to save cpu cycles.
Personally I think the ASSERT()s are clear enough to people familiar
with the scheduling code.
-George
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [xen-unstable test] 113562: regressions - FAIL
2017-09-18 11:05 ` George Dunlap
@ 2017-09-18 11:11 ` Juergen Gross
2017-09-18 13:47 ` George Dunlap
2017-09-18 14:16 ` Roger Pau Monné
2017-09-18 11:19 ` Jan Beulich
1 sibling, 2 replies; 14+ messages in thread
From: Juergen Gross @ 2017-09-18 11:11 UTC (permalink / raw)
To: George Dunlap, Roger Pau Monné
Cc: xen-devel, Wei Liu, George Dunlap, Dario Faggioli,
osstest service owner, Jan Beulich
On 18/09/17 13:05, George Dunlap wrote:
> On 09/18/2017 11:46 AM, Roger Pau Monné wrote:
>> On Mon, Sep 18, 2017 at 11:15:03AM +0100, George Dunlap wrote:
>>> On 09/18/2017 10:45 AM, Roger Pau Monné wrote:
>>>> On Mon, Sep 18, 2017 at 10:37:58AM +0100, Wei Liu wrote:
>>>>> On Mon, Sep 18, 2017 at 08:36:03AM +0000, osstest service owner wrote:
>>>>>> flight 113562 xen-unstable real [real]
>>>>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/
>>>>>>
>>>>>> Regressions :-(
>>>>>>
>>>>>> Tests which did not succeed and are blocking,
>>>>>> including tests which could not be run:
>>>>>> test-amd64-amd64-xl-credit2 15 guest-saverestore fail REGR. vs. 113387
>>>>>
>>>>> There appears to be a bug:
>>>>>
>>>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/test-amd64-amd64-xl-credit2/serial-godello0.log
>>>>>
>>>>> Sep 18 01:14:28.803062 (XEN) Xen BUG at spinlock.c:47
>>>>
>>>> Seem to be caused because budget_lock is sometimes locked with irqsave
>>>> while others not.
>>>
>>> Just wondering where you're getting the budget lock from? The call
>>> stack in that link makes it look like it's the RCU clean-up triggering a
>>> domain destroy. (Haven't looked deeper into the specific line numbers.)
>>
>> Just skimmed over the commit and jumped into conclusions too fast. As
>> you mention later the issue is calling xfree with interrupts disabled
>> in csched2_free_domdata.
>>
>> I would rather prefer budget_lock to be always locked with the
>> irqsave/restore variant to make what you mention above more obvious,
>> but that's just a question of taste.
>
> I *think* at some point in the past we had a discussion about this and
> someone (perhaps Jan?) said if we always know the irqs are disabled we
> shouldn't call the _irqsave() version, to save cpu cycles.
>
> Personally I think the ASSERT()s are clear enough to people familiar
> with the scheduling code.
Why don't we add _irqoff variants of the locks containing the ASSERTion
that interrupts are really off? This would save the additional
instructions of the irqsave/restore variants and make it very clear that
no violation of the lock interface is happening.
Juergen
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^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [xen-unstable test] 113562: regressions - FAIL
2017-09-18 11:11 ` Juergen Gross
@ 2017-09-18 13:47 ` George Dunlap
2017-09-18 14:16 ` Roger Pau Monné
1 sibling, 0 replies; 14+ messages in thread
From: George Dunlap @ 2017-09-18 13:47 UTC (permalink / raw)
To: Juergen Gross, Roger Pau Monné
Cc: xen-devel, Wei Liu, George Dunlap, Dario Faggioli,
osstest service owner, Jan Beulich
On 09/18/2017 12:11 PM, Juergen Gross wrote:
> On 18/09/17 13:05, George Dunlap wrote:
>> On 09/18/2017 11:46 AM, Roger Pau Monné wrote:
>>> On Mon, Sep 18, 2017 at 11:15:03AM +0100, George Dunlap wrote:
>>>> On 09/18/2017 10:45 AM, Roger Pau Monné wrote:
>>>>> On Mon, Sep 18, 2017 at 10:37:58AM +0100, Wei Liu wrote:
>>>>>> On Mon, Sep 18, 2017 at 08:36:03AM +0000, osstest service owner wrote:
>>>>>>> flight 113562 xen-unstable real [real]
>>>>>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/
>>>>>>>
>>>>>>> Regressions :-(
>>>>>>>
>>>>>>> Tests which did not succeed and are blocking,
>>>>>>> including tests which could not be run:
>>>>>>> test-amd64-amd64-xl-credit2 15 guest-saverestore fail REGR. vs. 113387
>>>>>>
>>>>>> There appears to be a bug:
>>>>>>
>>>>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/test-amd64-amd64-xl-credit2/serial-godello0.log
>>>>>>
>>>>>> Sep 18 01:14:28.803062 (XEN) Xen BUG at spinlock.c:47
>>>>>
>>>>> Seem to be caused because budget_lock is sometimes locked with irqsave
>>>>> while others not.
>>>>
>>>> Just wondering where you're getting the budget lock from? The call
>>>> stack in that link makes it look like it's the RCU clean-up triggering a
>>>> domain destroy. (Haven't looked deeper into the specific line numbers.)
>>>
>>> Just skimmed over the commit and jumped into conclusions too fast. As
>>> you mention later the issue is calling xfree with interrupts disabled
>>> in csched2_free_domdata.
>>>
>>> I would rather prefer budget_lock to be always locked with the
>>> irqsave/restore variant to make what you mention above more obvious,
>>> but that's just a question of taste.
>>
>> I *think* at some point in the past we had a discussion about this and
>> someone (perhaps Jan?) said if we always know the irqs are disabled we
>> shouldn't call the _irqsave() version, to save cpu cycles.
>>
>> Personally I think the ASSERT()s are clear enough to people familiar
>> with the scheduling code.
>
> Why don't we add _irqoff variants of the locks containing the ASSERTion
> that interrupts are really off? This would save the additional
> instructions of the irqsave/restore variants and make it very clear that
> no violation of the lock interface is happening.
I'd be OK with such a patch -- but obviously at this point it would have
to wait for 4.11. :-)
-George
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^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [xen-unstable test] 113562: regressions - FAIL
2017-09-18 11:11 ` Juergen Gross
2017-09-18 13:47 ` George Dunlap
@ 2017-09-18 14:16 ` Roger Pau Monné
1 sibling, 0 replies; 14+ messages in thread
From: Roger Pau Monné @ 2017-09-18 14:16 UTC (permalink / raw)
To: Juergen Gross
Cc: xen-devel, Wei Liu, George Dunlap, Dario Faggioli, George Dunlap,
osstest service owner, Jan Beulich
On Mon, Sep 18, 2017 at 01:11:07PM +0200, Juergen Gross wrote:
> On 18/09/17 13:05, George Dunlap wrote:
> > On 09/18/2017 11:46 AM, Roger Pau Monné wrote:
> >> On Mon, Sep 18, 2017 at 11:15:03AM +0100, George Dunlap wrote:
> >>> On 09/18/2017 10:45 AM, Roger Pau Monné wrote:
> >>>> On Mon, Sep 18, 2017 at 10:37:58AM +0100, Wei Liu wrote:
> >>>>> On Mon, Sep 18, 2017 at 08:36:03AM +0000, osstest service owner wrote:
> >>>>>> flight 113562 xen-unstable real [real]
> >>>>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/
> >>>>>>
> >>>>>> Regressions :-(
> >>>>>>
> >>>>>> Tests which did not succeed and are blocking,
> >>>>>> including tests which could not be run:
> >>>>>> test-amd64-amd64-xl-credit2 15 guest-saverestore fail REGR. vs. 113387
> >>>>>
> >>>>> There appears to be a bug:
> >>>>>
> >>>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/test-amd64-amd64-xl-credit2/serial-godello0.log
> >>>>>
> >>>>> Sep 18 01:14:28.803062 (XEN) Xen BUG at spinlock.c:47
> >>>>
> >>>> Seem to be caused because budget_lock is sometimes locked with irqsave
> >>>> while others not.
> >>>
> >>> Just wondering where you're getting the budget lock from? The call
> >>> stack in that link makes it look like it's the RCU clean-up triggering a
> >>> domain destroy. (Haven't looked deeper into the specific line numbers.)
> >>
> >> Just skimmed over the commit and jumped into conclusions too fast. As
> >> you mention later the issue is calling xfree with interrupts disabled
> >> in csched2_free_domdata.
> >>
> >> I would rather prefer budget_lock to be always locked with the
> >> irqsave/restore variant to make what you mention above more obvious,
> >> but that's just a question of taste.
> >
> > I *think* at some point in the past we had a discussion about this and
> > someone (perhaps Jan?) said if we always know the irqs are disabled we
> > shouldn't call the _irqsave() version, to save cpu cycles.
> >
> > Personally I think the ASSERT()s are clear enough to people familiar
> > with the scheduling code.
>
> Why don't we add _irqoff variants of the locks containing the ASSERTion
> that interrupts are really off? This would save the additional
> instructions of the irqsave/restore variants and make it very clear that
> no violation of the lock interface is happening.
+1
Roger.
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^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [xen-unstable test] 113562: regressions - FAIL
2017-09-18 11:05 ` George Dunlap
2017-09-18 11:11 ` Juergen Gross
@ 2017-09-18 11:19 ` Jan Beulich
1 sibling, 0 replies; 14+ messages in thread
From: Jan Beulich @ 2017-09-18 11:19 UTC (permalink / raw)
To: George Dunlap
Cc: xen-devel, Wei Liu, George Dunlap, Dario Faggioli,
osstest service owner, Roger Pau Monné
>>> On 18.09.17 at 13:05, <george.dunlap@citrix.com> wrote:
> On 09/18/2017 11:46 AM, Roger Pau Monné wrote:
>> On Mon, Sep 18, 2017 at 11:15:03AM +0100, George Dunlap wrote:
>>> On 09/18/2017 10:45 AM, Roger Pau Monné wrote:
>>>> On Mon, Sep 18, 2017 at 10:37:58AM +0100, Wei Liu wrote:
>>>>> On Mon, Sep 18, 2017 at 08:36:03AM +0000, osstest service owner wrote:
>>>>>> flight 113562 xen-unstable real [real]
>>>>>> http://logs.test-lab.xenproject.org/osstest/logs/113562/
>>>>>>
>>>>>> Regressions :-(
>>>>>>
>>>>>> Tests which did not succeed and are blocking,
>>>>>> including tests which could not be run:
>>>>>> test-amd64-amd64-xl-credit2 15 guest-saverestore fail REGR. vs.
> 113387
>>>>>
>>>>> There appears to be a bug:
>>>>>
>>>>>
> http://logs.test-lab.xenproject.org/osstest/logs/113562/test-amd64-amd64-xl-c
> redit2/serial-godello0.log
>>>>>
>>>>> Sep 18 01:14:28.803062 (XEN) Xen BUG at spinlock.c:47
>>>>
>>>> Seem to be caused because budget_lock is sometimes locked with irqsave
>>>> while others not.
>>>
>>> Just wondering where you're getting the budget lock from? The call
>>> stack in that link makes it look like it's the RCU clean-up triggering a
>>> domain destroy. (Haven't looked deeper into the specific line numbers.)
>>
>> Just skimmed over the commit and jumped into conclusions too fast. As
>> you mention later the issue is calling xfree with interrupts disabled
>> in csched2_free_domdata.
>>
>> I would rather prefer budget_lock to be always locked with the
>> irqsave/restore variant to make what you mention above more obvious,
>> but that's just a question of taste.
>
> I *think* at some point in the past we had a discussion about this and
> someone (perhaps Jan?) said if we always know the irqs are disabled we
> shouldn't call the _irqsave() version, to save cpu cycles.
Regardless if it was me back then, I certainly share that position.
> Personally I think the ASSERT()s are clear enough to people familiar
> with the scheduling code.
I agree.
Jan
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