From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Nathan Chancellor <nathan@kernel.org>,
Marco Elver <elver@google.com>,
Richard Henderson <rth@twiddle.net>
Cc: Heiko Carstens <hca@linux.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Vasily Gorbik <gor@linux.ibm.com>,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
llvm@lists.linux.dev, qemu-s390x <qemu-s390x@nongnu.org>
Subject: Re: [GIT PULL] s390 updates for 5.15 merge window
Date: Tue, 31 Aug 2021 19:49:41 +0200 [thread overview]
Message-ID: <4ae5cf63-4f86-5a1c-90b5-73912cfe42b9@de.ibm.com> (raw)
In-Reply-To: <YS5rVpFXe4w/D7BN@MSI.localdomain>
On 31.08.21 19:48, Nathan Chancellor wrote:
> On Tue, Aug 31, 2021 at 05:02:15PM +0200, Marco Elver wrote:
>> On Tue, Aug 31, 2021 at 12:46PM +0200, Marco Elver wrote:
>>> On Tue, 31 Aug 2021 at 12:13, Heiko Carstens <hca@linux.ibm.com> wrote:
>>> [...]
>>>> I really don't think this is QEMU related. The test fails are sort of
>>>> expected: we've seen KCSAN reports when the kernel boots and wanted to
>>>> fix them later.
>>>> However I have to admit that I wasn't aware of the KCSAN KUNIT tests,
>>>> and wouldn't have sent the s390 KCSAN enablement upstream if I would
>>>> have been aware of failing self tests.
>>>>
>>>> We'll fix them, and I let you know if things are supposed to work.
>>>>
>>>> Thanks a lot for making aware of this!
>>>
>>> Note: Set `CONFIG_KCSAN_REPORT_ONCE_IN_MS=100` (or smaller) instead of
>>> the default to make the test complete faster.
>>>
>>> The pattern I see from what Nathan reported is that all test cases
>>> that expect race reports don't observe them ("not ok" cases), and all
>>> those where no races are meant to be reported are fine ("ok" cases).
>>> Without actually seeing the log, I'm guessing that no races are
>>> reported at all, which is certainly not working as intended.
>>
>> I repro'd, and the problem is part QEMU TCG and a minor problem with
>> stack_trace_save() on s390:
>>
>> 1. QEMU TCG doesn't seem to want to execute threads concurrently,
>> resulting in no "value changes" being observed. This is probably just
>> a limitation of TCG, and if run on a real CPU, shouldn't be a problem.
>> On QEMU, most test cases will pass with CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY=n
>> (There's one left that requires value changes to be observable)
>
> Is this just a limitation of s390's TCG implementation or in general?
> Our CI runs on GitHub Actions, which does not support virtualization so
> I believe that all of our tests are being done with TCG and x86_64
> passes just fine:
Maybe Richard knows?
>
> https://github.com/ClangBuiltLinux/continuous-integration2/runs/3473222334?check_suite_focus=true
>
> Good to hear that it is working on bare metal now though, we could still
> enable build testing of it at a minimum but it would be nice to see the
> tests pass even in QEMU :)
>
> Cheers,
> Nathan
>
next prev parent reply other threads:[~2021-08-31 17:50 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-30 13:11 [GIT PULL] s390 updates for 5.15 merge window Heiko Carstens
2021-08-30 20:17 ` pr-tracker-bot
2021-08-31 2:19 ` Nathan Chancellor
2021-08-31 7:09 ` Christian Borntraeger
2021-08-31 10:13 ` Heiko Carstens
2021-08-31 10:46 ` Marco Elver
2021-08-31 15:02 ` Marco Elver
2021-08-31 15:18 ` Heiko Carstens
2021-08-31 17:48 ` Nathan Chancellor
2021-08-31 17:49 ` Christian Borntraeger [this message]
2021-09-01 14:03 ` Vasily Gorbik
2021-09-01 14:05 ` [PATCH] s390/unwind: use current_frame_address() to unwind current task Vasily Gorbik
2021-09-01 17:51 ` Marco Elver
2021-09-01 18:07 ` Heiko Carstens
2021-09-03 23:23 ` Nathan Chancellor
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