Re: WARNING in kvm_age_gfn

[cheung wall]

Thanks Oliver, I have confirmed the situation about the sha1 in the
path that is my fault. I will test this crash in the latest new linux
arm version. Meanwhile, more batches of the reports will be provided
after validation on the new experiment.

Best,
Cheung Wall

On Wed, Mar 13, 2024 at 1:25 PM Oliver Upton <oliver.upton@xxxxxxxxx> wrote:
>
> Hi,
>
> On Wed, Mar 13, 2024 at 01:02:10PM +0800, cheung wall wrote:
> > Hello,
> >
> > when using Syzkaller to fuzz the latest Linux Kernel arm64 version,
> > the following crash
>
> First, thank you. Glad to see folks are fuzzing KVM/arm64 now.
>
> > was triggered on:
> >
> > HEAD commit: 0dd3ee31125508cd67f7e7172247f05b7fd1753a  (tag: v6.7)
>
> In order for these sorts of bug reports to be actionable, they really
> need to be against a close-to-upstream tree. 6.8 is out now, and 6.9-rc1
> is right around the corner.
>
> Having said that, I think there might be an issue or two with your bot
> because...
>
> > git tree: upstream
> >
> > console output: https://pastebin.com/raw/3NCyqPUn
> >
> > kernel config: https://pastebin.com/raw/mXEg4abU
> >
> > C reproducer: https://pastebin.com/raw/N0gEqk5x
>
> This reproducer doesn't work on upstream (tested kvmarm-6.9 tag), and
>
> > WARNING: CPU: 0 PID: 711 at arch/arm64/kvm/mmu.c:1592
> > kvm_age_gfn+0x64/0xdc
> > data/embfuzz/emblinux/linux-4a61839152cc3e9e00ac059d73a28d148d622b30/arch/arm64/kvm/mmu.c:1592
>
> The SHA1 in this path is suspiciously the same as 6.1.61. Are you
> certain the bot is working on the correct tree? Nevertheless, I think
> the WARN and associated bug were addressed in commit df6556adf27b
> ("KVM: arm64: Correctly handle page aging notifiers for unaligned
> memslot").
>
> Last thing -- I'm guessing your syzkaller runs will dredge up quite a bit
> of low-hanging bugs given how little exposure this code has had. Could
> you please aggregate the first batch of reports and send as a single
> series of email? Makes it much easier to keep track of.
>
> --
> Thanks,
> Oliver