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Message-ID: <YqAL+HeZDk5Wug28@google.com>
Date: Wed, 8 Jun 2022 11:39:52 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Minchan Kim <minchan@...nel.org>
Cc: Naresh Kamboju <naresh.kamboju@...aro.org>,
open list <linux-kernel@...r.kernel.org>,
linux-fsdevel@...r.kernel.org,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@...r.kernel.org>,
linux-block <linux-block@...r.kernel.org>,
regressions@...ts.linux.dev, Jens Axboe <axboe@...nel.dk>,
Sergey Senozhatsky <senozhatsky@...omium.org>,
Nitin Gupta <ngupta@...are.org>
Subject: Re: qemu-arm: zram: mkfs.ext4 : Unable to handle kernel NULL pointer
dereference at virtual address 00000140
On (22/06/07 16:52), Minchan Kim wrote:
> > rootfs: https://oebuilds.tuxbuild.com/29zhlbEc3EWq2wod9Uy964Bp27q/images/am57xx-evm/rpb-console-image-lkft-am57xx-evm-20220601222434.rootfs.ext4.gz
> > kernel: https://builds.tuxbuild.com/29zhqJJizU2Y7Ka7ArhryUOrNDC/zImage
> >
> > Boot command,
> > /usr/bin/qemu-system-aarch64 -cpu host,aarch64=off -machine
> > virt-2.10,accel=kvm -nographic -net
> > nic,model=virtio,maaacaddr=BA:DD:AD:CC:09:04 -net tap -m 2048 -monitor
> > none -kernel kernel/zImage --append "console=ttyAMA0 root=/dev/vda rw"
> > -hda rootfs/rpb-console-image-lkft-am57xx-evm-20220601222434.rootfs.ext4
> > -m 4096 -smp 2
> >
> > # cd /opt/kselftests/default-in-kernel/zram
> > # ./zram.sh
> >
> > Allow me sometime I will try to bisect this problem.
>
> Thanks for sharing the info.
>
> I managed to work your rootfs with my local arm build
> based on the problematic git tip.
> However, I couldn't suceed to reproduce it.
>
> I needed to build zsmalloc/zram built-in instead of modules
> Is it related? Hmm,
>
> Yeah, It would be very helpful if you could help to bisect it.
This looks like a NULL lock->name dereference in lockdep. I suspect
that somehow local_lock doesn't get .dep_map initialized. Maybe running
the kernel with CONFIG_DEBUG_LOCK_ALLOC would help us? Naresh, can you
help us with this?
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