Re: [Linux PPC] Disable PREEMPT

On Thu, Sep 03, 2026 at 05:01:13PM +0530, Shrikanth Hegde wrote:

quoted

quoted

quoted

This is not the latest kernel so it might have been fixed in the
meantime for the platform in question. Will need to check that.

If possible run against current upstream and share the results.

https://github.com/openSUSE/kernel-source/blob/6824496d1801f73def615dca8794202eeb7b0d86/config/ppc64le/default

[  472.091531][ T6181] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: kvmhv_run_single_vcpu+0x19d4/0x1b50 [kvm_hv]
[  472.091598][ T6181] CPU: 29 UID: 107 PID: 6181 Comm: CPU 112/KVM Not tainted 7.2.2-5.g6824496-default #1 PREEMPT(full) openSUSE Tumbleweed (unreleased)  61871a5f06863b4006f5ef27cd9f18e8a7a2edad
[  472.091612][ T6181] Hardware name: IBM,9824-42A Power11 (architected) 0x820200 0xf000007 of:IBM,FW1110.20 (OB1110_130) hv:phyp pSeries
[  472.091624][ T6181] Call Trace:
[  472.091630][ T6181] [c00000000fdfb680] [c00000000134ce90] dump_stack_lvl+0x84/0xc0 (unreliable)
[  472.091653][ T6181] [c00000000fdfb6b0] [c00000000022e7c8] vpanic+0x324/0x5e4
[  472.091666][ T6181] [c00000000fdfb760] [c00000000022eac4] do_panic_on_target_cpu+0x0/0x2c
[  472.091677][ T6181] [c00000000fdfb780] [c0000000013c1ff8] __stack_chk_fail+0x48/0x60
[  472.091689][ T6181] [c00000000fdfb7f0] [c00800001aae219c] kvmhv_run_single_vcpu+0x19d4/0x1b50 [kvm_hv]
[  472.091712][ T6181] [c00000000fdfb940] [c00800001aae24b4] kvmppc_vcpu_run_hv+0x19c/0x12f0 [kvm_hv]
[  472.091732][ T6181] [c00000000fdfba10] [c00800001aeeed18] kvmppc_vcpu_run+0x30/0x48 [kvm]
[  472.091779][ T6181] [c00000000fdfba30] [c00800001aee9ef4] kvm_arch_vcpu_ioctl_run+0x35c/0x4a0 [kvm]
[  472.091813][ T6181] [c00000000fdfbac0] [c00800001aedaac4] kvm_vcpu_ioctl+0x1ac/0xad8 [kvm]
[  472.091844][ T6181] [c00000000fdfbca0] [c0000000007f1244] sys_ioctl+0x374/0x1060
[  472.091857][ T6181] [c00000000fdfbdb0] [c00000000002f7f8] system_call_exception+0x188/0x430
[  472.091871][ T6181] [c00000000fdfbe50] [c00000000000cfdc] system_call_vectored_common+0x15c/0x2ec
[  472.091886][ T6181] ---- interrupt: 3000 at 0x7fffb5565fac
[  472.091896][ T6181] NIP:  00007fffb5565fac LR: 00007fffb5565fac CTR: 0000000000000000
[  472.091904][ T6181] REGS: c00000000fdfbe80 TRAP: 3000   Not tainted  (7.2.2-5.g6824496-default)
[  472.091911][ T6181] MSR:  800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE>  CR: 42044402  XER: 00000000
[  472.091938][ T6181] IRQMASK: 0
[  472.091938][ T6181] GPR00: 0000000000000036 00007fbfa77ed7a0 00007fffb5677100 00000000000000fa
[  472.091938][ T6181] GPR04: 000000002000ae80 0000000000000000 0000000000000000 0000000000000000
[  472.091938][ T6181] GPR08: 00000000000000fa 0000000000000000 0000000000000000 0000000000000000
[  472.091938][ T6181] GPR12: 0000000000000000 00007fbfa77f5ec0 000000014676f000 00007fbfa77ee7c0
[  472.091938][ T6181] GPR16: 000000014674e8d0 00007fbfa77eeec0 00007fbfa77eeec0 fffffffffffffff7
[  472.091938][ T6181] GPR20: 00007fffb71210d0 0000000000000001 00007fbfa77eeec0 0000000000000000
[  472.091938][ T6181] GPR24: 00007fbfa77ed8e8 0000000105971428 000000002000ae80 0000000105f77a70
[  472.091938][ T6181] GPR28: 0000000000000000 0000000000000000 000000002000ae80 000000014674f000
[  472.092020][ T6181] NIP [00007fffb5565fac] 0x7fffb5565fac
[  472.092027][ T6181] LR [00007fffb5565fac] 0x7fffb5565fac
[  472.092033][ T6181] ---- interrupt: 3000
[  472.098256][ T6181] pstore: backend (nvram) writing error (-1)

This is the host, cannot run the kernel as guest because it fails to boot most
of the time inside KVM.

Will look into. btw the patch shared i.e below patch fixes the boot hanf issue?

https://lore.kernel.org/all/1d79ec6f-ce7f-4432-80e0-a54fa1668642@linux.ibm.com/ (local)

I would not bet on that. It looks like host side patch, and the problem
is with booting 7.2.2 as guest. Some 6.12 frankenkernel can be booted on
the same host, and used to produce the crash above by running a kernel
build inside the guest.

Thanks

Michal