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From:   Liam Howlett <liam.howlett@oracle.com>
To:     Naresh Kamboju <naresh.kamboju@linaro.org>
CC:     open list <linux-kernel@vger.kernel.org>,
        Linux-Next Mailing List <linux-next@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Andrew Morton <akpm@linux-foundation.org>,
        Matthew Wilcox <willy@infradead.org>,
        David Howells <dhowells@redhat.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        SeongJae Park <sj@kernel.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Will Deacon <will@kernel.org>,
        Davidlohr Bueso <dave@stgolabs.net>
Subject: Re: BUG: kernel NULL pointer dereference, address: 00000004 -
 mas_update_gap
Thread-Topic: BUG: kernel NULL pointer dereference, address: 00000004 -
 mas_update_gap
Thread-Index: AQHYaO8VaP9c9T6G3ECkHQCWsCAGkK0jMz4A
Date:   Tue, 17 May 2022 15:27:08 +0000
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* Naresh Kamboju <naresh.kamboju@linaro.org> [220516 02:35]:
> While running LTP sched tests on i386 the following kernel BUG noticed on
> Linux next-20220513 [1].
>=20
...

> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
>=20
> metadata:
>   git_ref: master
>   git_repo: ''
>   git_sha: 1e1b28b936aed946122b4e0991e7144fdbbfd77e
>   git_describe: next-20220513
>   kernel_version: 5.18.0-rc6
>   kernel-config: https://builds.tuxbuild.com/296PiI1oM7N6Vk7m9lxuipmXW7B/=
config
>   build-url: https://gitlab.com/Linaro/lkft/mirrors/next/linux-next/-/pip=
elines/538244935
>   artifact-location: https://builds.tuxbuild.com/296PiI1oM7N6Vk7m9lxuipmX=
W7B
>   toolchain: gcc-11
>=20
> --
> Linaro LKFT
> https://lkft.linaro.org
>=20
> [1] https://lkft.validation.linaro.org/scheduler/job/5021335#L1718


I was able to reproduce this issue with ltp running:
"./runltp -p -q -f sched"

I have sent a fix out [1] that allows the test to execute on i386 qemu.

Thanks,
Liam

1. https://lore.kernel.org/linux-mm/20220517152209.3486724-1-Liam.Howlett@o=
racle.com/