From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C265372 for ; Tue, 31 Aug 2021 17:48:08 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id B391A610D1; Tue, 31 Aug 2021 17:48:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1630432088; bh=FQhT4voOXSGn5CqQjRmxbe6MV9pTwA1BDm62Ac/YtAE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=C5sIhqEgn6qoEOgcoz62ZNo93cV4lQCFydN3JR+VsX1d6DjrErCQzyUspUIvqvFSB n1/kZlzCQdmZXJ5QjLE1wwheXwdjiLqI1sosLOFEzLpwyXn8FKdHZkhHKEAqSN5uNT UbyqjiRfYUM6Sg9wnZ3fZzL+d1mDK115MLo7CZ+VBbhBt76BoU9CbVm0XxFQFIY3H9 a8tIiS4yW2QAjjOmLB+6CSvv/SzKXhBpTuQrCCV5LSA1cJmJfY1IbhslMYQlX+rI9v 0utXk8jYmzNqLIkB9mDWX1fhYjL+LpubEFH+sFujK4Id0fzyGoyR2ZvqmT/5jIMxgW xJfeb3VZGcZ9Q== Date: Tue, 31 Aug 2021 10:48:06 -0700 From: Nathan Chancellor To: Marco Elver Cc: Heiko Carstens , Christian Borntraeger , Linus Torvalds , Vasily Gorbik , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, qemu-s390x Subject: Re: [GIT PULL] s390 updates for 5.15 merge window Message-ID: References: <82161448-2770-158c-fdd3-d253b4ae476f@de.ibm.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 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: 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