From: Heiko Carstens <hca@linux.ibm.com>
To: Marco Elver <elver@google.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>,
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
Date: Tue, 31 Aug 2021 17:18:30 +0200 [thread overview]
Message-ID: <YS5IRiFO9crNu46y@osiris> (raw)
In-Reply-To: <YS5Ed4Cyf+rOf9MR@elver.google.com>
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 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)
>
> 2. stack_trace_save() is subtly broken on s390: it starts the trace in
> stack_trace_save() itself. This is incorrect, as the trace should
> start with the caller. We reported something similar to arm64, also
> because one of our sanitizer tests failed:
> https://lkml.kernel.org/r/20210319184106.5688-1-mark.rutland@arm.com
...
> I fixed it with the below, and now most tests pass. Note that, other
> debugging tools may also report misleading stack traces without the
> stack_trace_save() fix (e.g. certain KFENCE reports).
>
> If you have a better solution for how to fix stack_trace_save() on s390,
> please discard my patch.
Ah, with your patch I get the below on a real machine; so it looks
like this really was the only problem for the failing self tests.
Thanks a lot for the patch! Will look into it later and apply if
everything else still works!
[ 5.138547] ok 1 - test_basic
[ 7.538799] ok 2 - test_concurrent_races
[ 9.938524] ok 3 - test_novalue_change
[ 11.620063] ok 4 - test_novalue_change_exception
[ 11.952404] ok 5 - test_unknown_origin
[ 14.349852] ok 6 - test_write_write_assume_atomic
[ 14.681937] ok 7 - test_write_write_struct
[ 15.031046] ok 8 - test_write_write_struct_part
[ 17.429869] ok 9 - test_read_atomic_write_atomic
[ 17.760862] ok 10 - test_read_plain_atomic_write
[ 18.093500] ok 11 - test_read_plain_atomic_rmw
[ 20.490570] ok 12 - test_zero_size_access
[ 22.939270] ok 13 - test_data_race
[ 23.271104] ok 14 - test_assert_exclusive_writer
[ 23.601940] ok 15 - test_assert_exclusive_access
[ 26.000281] ok 16 - test_assert_exclusive_access_writer
[ 26.330718] ok 17 - test_assert_exclusive_bits_change
[ 28.739480] ok 18 - test_assert_exclusive_bits_nochange
[ 28.962218] ok 19 - test_assert_exclusive_writer_scoped
[ 29.071385] ok 20 - test_assert_exclusive_access_scoped
[ 31.479706] ok 21 - test_jiffies_noreport
[ 33.879581] ok 22 - test_seqlock_noreport
[ 36.279853] ok 23 - test_atomic_builtins
[ 36.279893] ok 1 - kcsan
next prev parent reply other threads:[~2021-08-31 15:19 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 [this message]
2021-08-31 17:48 ` Nathan Chancellor
2021-08-31 17:49 ` Christian Borntraeger
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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