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From:   Naresh Kamboju <naresh.kamboju@linaro.org>
Date:   Thu, 25 May 2023 19:05:49 +0530
Message-ID: <CA+G9fYs2y4RvOEOJ2qwX=O98j7sgkQJ+jZucd28wPUj6L-vN2A@mail.gmail.com>
Subject: Re: arm64: fp-stress: BUG: KFENCE: memory corruption in fpsimd_release_task
To:     Will Deacon <will@kernel.org>
Cc:     broonie@kernel.org,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        linux-stable <stable@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        lkft-triage@lists.linaro.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        Dan Carpenter <dan.carpenter@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>, Shuah Khan <shuah@kernel.org>,
        Anders Roxell <anders.roxell@linaro.org>
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On Mon, 22 May 2023 at 22:11, Will Deacon <will@kernel.org> wrote:
>
> Naresh,
>
> On Tue, May 16, 2023 at 02:44:49PM +0100, Will Deacon wrote:
> > On Tue, May 16, 2023 at 11:58:40AM +0530, Naresh Kamboju wrote:
> > > Following kernel BUG noticed while running selftests arm64 fp-stress
> > > running stable rc kernel versions 6.1.29-rc1 and 6.3.3-rc1.
> >
> > Is there a known-good build so that we could attempt a bisection?
>
> FWIW, I've been trying (and failing) all day to reproduce this in QEMU.
> I matched the same VL configuration as you have in the fastmodel and
> tried enabling additional memory debugging options too, but I'm yet to
> see a kfence splat (or any other splat fwiw).

Thanks for trying it out.
I have shared log [Log link] below on Linux next-20230314 which is the
starting point of BUG that we started noticing and that is raw log showing
FVP log with all -C details.

>
> How often do you see this?

Our CI system running  selftests: arm64 - subtests by using
./run_kselftest.sh -c arm64

With full selftests: arm64 the probability of occurrence is 40%.

On Linux next this fp-stress BUG: has been happening *intermittently* from
next-20230314 dated March 14, 2023.
On Linux stable-rc it started happening on 6.3.2-rc1 and 6.1.28-rc2.

More details (on previous email),
- https://lore.kernel.org/all/CA+G9fYtZjGomLjDi+Vf-hdcLpKPKbPmn4nwoPXvn24SG2hEJMg@mail.gmail.com/

- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230314/testrun/15566007/suite/log-parser-test/test/check-kernel-bug-
9588df685892e898be8969def31c5aa074b2faada33f12ebc88fd7e7b52893cd/details/

Log link:
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230314/testrun/15566007/suite/log-parser-test/test/check-kernel-bug-9588df685892e898be8969def31c5aa074b2faada33f12ebc88fd7e7b52893cd/log


>
> Will