Re: WARNING in kvm_mmu_uninit_tdp_mmu

[Sean Christopherson]

On Sun, Jan 09, 2022, Sabri N. Ferreiro wrote:
> Hi,
> 
> When using Syzkaller to fuzz the Linux kernel, it triggers the following crash.
> 
> HEAD commit: a7904a538933 Linux 5.16-rc6
> git tree: upstream
> console output: https://pastebin.com/raw/keWCUeJ2
> kernel config: https://docs.google.com/document/d/1w94kqQ4ZSIE6BW-5WIhqp4_Zh7XTPH57L5OF2Xb6O6o/view
> C reproducer: https://pastebin.com/raw/kSxa6Yit
> Syzlang reproducer: https://pastebin.com/raw/2RMu8p6E
> 
> If you fix this issue, please add the following tag to the commit:
> Reported-by: Yuheng Shen mosesfonscqf75@xxxxxxxxx
> 
> ------------[ cut here ]------------
> WARNING: CPU: 5 PID: 29657 at arch/x86/kvm/mmu/tdp_mmu.c:46
> kvm_mmu_uninit_tdp_mmu+0xb9/0xf0

I wasn't able to reproduce to confirm, but this is more than likely fixed by
commit 3a0f64de479c ("KVM: x86/mmu: Don't advance iterator after restart due to yielding"),
which didn't land until 5.16-rc7.