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Date:   Tue, 31 Aug 2021 12:13:13 +0200
From:   Heiko Carstens <hca@linux.ibm.com>
To:     Christian Borntraeger <borntraeger@de.ibm.com>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        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
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On Tue, Aug 31, 2021 at 09:09:10AM +0200, Christian Borntraeger wrote:
> 
> 
> On 31.08.21 04:19, Nathan Chancellor wrote:
> > Hi Heiko,
> > 
> > On Mon, Aug 30, 2021 at 03:11:50PM +0200, Heiko Carstens wrote:
> > > - Enable KCSAN for s390. This comes with a small common code change to fix a
> > >    compile warning. Acked by Marco Elver:
> > >    https://lore.kernel.org/r/20210729142811.1309391-1-hca@linux.ibm.com/
> > 
> > This caught my eye, as we are boot testing KCSAN + KCSAN_KUNIT_TEST in
> > our CI [1] for x86_64 so it would be nice to enable this for s390 as
> > well. However, it does not seem like the unit tests pass when booting up
> > in QEMU, is this expected or am I doing something wrong? The results and
> > compiler versions are below (the results are the same), they should both
> > have the commits that are mentioned in the KCSAN message.
> 
> Do you have a branch somewhere where you have the s390 build rules as well as
> the qemu command line? Maybe its a QEMU TCG issue, dont know. CC qemu-s390x
> just in case.

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!