On Thu, Sep 10, 2026 at 01:29:08PM +0200, Michal Suchánek wrote:
> On Thu, Sep 10, 2026 at 04:11:20PM +0530, Shrikanth Hegde wrote:
> > 
> > 
> > On 9/10/26 2:29 PM, Michal Suchánek wrote:
> > > On Fri, Sep 04, 2026 at 02:34:21PM +0530, Shrikanth Hegde wrote:
> > > > 
> > > > 
> > > > On 9/4/26 1:05 PM, Michal Suchánek wrote:
> > > > > On Thu, Sep 03, 2026 at 10:52:59PM +0530, Shrikanth Hegde wrote:
> > > > > > 
> > > > > > > > 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.
> > > > > > > 
> > > > > > > > 
> > > > > > > > > Nonethless, there are quite a few platforms. Originally no 
> > > > > > > > > preemption
> > > > > > > > > was the only option, and that's the reason why many people 
> > > > > > > > > run that.
> > > > > > > > > It's the conservative, known working option. And that's the 
> > > > > > > > > reason a lot
> > > > > > > > > of platfrom code does not get tested with more aggressive 
> > > > > > > > > preemtion
> > > > > > > > > models, and never gets fixed to work with them.
> > > > > > > > > 
> > > > > > > > 
> > > > > > > > Full preemption has been there for many years!.
> > > > > > > 
> > > > > > > Possible for years, forced only recently.
> > > > > > > 
> > > > > > > > Lazy is not that aggressive compared to that.
> > > > > > > > 
> > > > > > > > > Simply disabling the no preemtion option does not make the 
> > > > > > > > > platform code
> > > > > > > > > ready.
> > > > > > > > > 
> > > > > > > > 
> > > > > > > > Let's understand your crash case. Let's see where it is going 
> > > > > > > > wrong. I am suspecting
> > > > > > > > it is some wrong usage of preemption api rather than arch can't 
> > > > > > > > support preemption.
> > > > > > > 
> > > > > > > Very likely some wrong use of the preemption API by the arch 
> > > > > > > code, or no
> > > > > > > use where it should have been used. It did not matter so long as 
> > > > > > > people
> > > > > > > could run their no preempt configs and ignore the problem.
> > > > > > > 
> > > > > > > Thanks
> > > > > > 
> > > > > > 
> > > > > > Friendly LLM analysis says preemption is enabled too early and 
> > > > > > before
> > > > > > completing kvmppc_handle_exit_hv() / kvmppc_handle_nested_exit()
> > > > > > 
> > > > > > Below is ONLY a speculation and completely UNTESTED.
> > > > > > Maybe worth a try.
> > > > > 
> > > > > The patch is munged by the e-mail client, and it causes immediate
> > > > > voluntary preemprion in rcu critical section and hard lockup on 
> > > > > starting
> > > > > a KVM VM.
> > > > > 
> > > > > Also it would be sort of bad news if it worked because that would be
> > > > > specific to book3s KVM HV and would not help with the KVM HV from the
> > > > > original report which likely is not book3s, nor with KVM PR.
> > > > > 
> > > > 
> > > > Thanks for trying. We will try a local repro and look into it why stack 
> > > > is
> > > > getting corrupted.
> > > 
> > > There is also stack corruption when idling. At this point the machine is
> > > stuck half-dead and would not go through with the panic, it requires
> > > dump from the hyprvisor side to capture this.
> > > 
> > > Thanks
> > > 
> > > Michal
> > > 
> > 
> > 
> > is this on host with kvm running or this is without kvm running anything?
> 
> Difficult to say after the fact. Given running KVM VMs is crashing with
> this kernel most likely no VM was running.
> 
> > 
> > Do you see corruption if you don't have kvm module loaded?
> 
> Difficult to say, this takes hours to days to reproduce, and the module
> is normally loaded by default. I can blacklist it to make sure it does
> not get loaded.
> 
> > 
> > These maybe two independent issue.
> > Our KVM team is trying local repro for the kvm issue you have reported.
> > 
> > If possible, could you try vmcore capture (maybe with fadump)?
> 
> I have the vmcore, this dmesg is from the vmcore. I would not get
> displayed otherwise, or maybe some content from the console is lost.
> 
> Unfortunately, this is a kernel from a rolling distribution, and may be
> difficult to analyze bacause new kernel build is used by now.
> 
> Thanks
> 
> Michal
> 
> > 
> > > [542489.550547] [      T0] Kernel panic - not syncing: stack-protector: 
> > > Kernel stack is corrupted in: __sprint_symbol+0x1e4/0x1f0
> > > [542489.557809] [      T0] ------------[ cut here ]------------
> > > [542489.557814] [      T0] Voluntary context switch within RCU read-side 
> > > critical section!
> > > [542489.557822] [      T0] WARNING: [] kernel/rcu/tree_plugin.h:332 at 
> > > rcu_note_context_switch+0x6a0/0x7b0, CPU#59: swapper/59/0
> > > [542489.557837] [      T0] Modules linked in: vhost_net vhost vhost_iotlb 
> > > tap rpadlpar_io rpaphp kvm_hv kvm mptcp_diag xsk_diag tcp_diag udp_diag 
> > > raw_diag inet_diag unix_diag af_packet_diag netlink_diag xt_conntrack 
> > > xt_MASQUERADE xfrm_user xt_set ip_set xt_addrtype nft_compat 
> > > nf_conntrack_netbios_ns nf_conntrack_broadcast nft_masq nft_fib_inet 
> > > nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 
> > > nf_reject_ipv6 nft_reject nft_ct bonding tls nft_chain_nat nf_nat 
> > > nf_conntrack tun nf_defrag_ipv6 nf_defrag_ipv4 rfkill af_packet 
> > > binfmt_misc xfs aes_gcm_p10_crypto crypto_simd ibmveth cryptd xts 
> > > vmx_crypto rtc_generic fuse nvme_fabrics ip_tables x_tables ibmvscsi 
> > > scsi_transport_srp sd_mod scsi_dh_emc scsi_dh_rdac scsi_dh_alua sg 
> > > scsi_mod scsi_common nvme nvme_core nvme_keyring nvme_auth pseries_wdt 
> > > btrfs xor libblake2b raid6_pq dm_mirror dm_region_hash dm_log dm_mod 
> > > br_netfilter bridge stp llc nf_tables
> > > [542489.557944] [      T0] CPU: 59 UID: 0 PID: 0 Comm: swapper/59 
> > > Tainted: G      D W           7.2.2-5.g6824496-default #1 PREEMPT(full) 
> > > openSUSE Tumbleweed (unreleased)  61871a5f06863b4006f5ef27cd9f18e8a7a2edad
> > > [542489.557957] [      T0] Tainted: [D]=DIE, [W]=WARN
> > > [542489.557961] [      T0] Hardware name: IBM,9824-42A Power11 
> > > (architected) 0x820200 0xf000007 of:IBM,FW1110.20 (OB1110_130) hv:phyp 
> > > pSeries
> > > [542489.557967] [      T0] NIP:  c00000000035d700 LR: c00000000035d6fc 
> > > CTR: 0000000000000000
> > > [542489.557974] [      T0] REGS: c000001de047f990 TRAP: 0700   Tainted: G 
> > >      D W            (7.2.2-5.g6824496-default)
> > > [542489.557980] [      T0] MSR:  800000000282b033 
> > > <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>  CR: 44002284  XER: 0000000e
> > > [542489.557999] [      T0] CFAR: c00000000022d7a8 IRQMASK: 1
> > >                             GPR00: c00000000035d6fc c000001de047fc30 
> > > c00000000205ad00 000000000000003f
> > >                             GPR04: 3ffffffffffc02ef c000001de047f950 
> > > c000001de047f910 0000003ff0e20000
> > >                             GPR08: 0000000000000027 0000000000000001 
> > > c000001de0191300 0000000044002284
> > >                             GPR12: c000003ff1614890 c000003fffff9f00 
> > > 0000000000000000 000000002eef9860
> > >                             GPR16: 0000000000000000 c000003ff40dcc80 
> > > 0000003ff0e20000 c000000000058010
> > >                             GPR20: c000000000058160 c0000000032bcc80 
> > > c0000000032bcc80 c000000000057f80
> > >                             GPR24: ffffffffffffffff 000000000000003b 
> > > c000001de0191300 c000000003bea6e0
> > >                             GPR28: c000000000058010 ffffffffffffffff 
> > > 0000000000000000 c000003ff40de100
> > > [542489.558066] [      T0] NIP [c00000000035d700] 
> > > rcu_note_context_switch+0x6a0/0x7b0
> > > [542489.558072] [      T0] LR [c00000000035d6fc] 
> > > rcu_note_context_switch+0x69c/0x7b0
> > > [542489.558078] [      T0] Call Trace:
> > > [542489.558082] [      T0] [c000001de047fc30] [c00000000035d6fc] 
> > > rcu_note_context_switch+0x69c/0x7b0 (unreliable)
> > > [542489.558092] [      T0] [c000001de047fcd0] [c0000000013c4fc0] 
> > > __schedule+0xf0/0x1d10
> > > [542489.558108] [      T0] [c000001de047fe20] [c0000000013c6eb0] 
> > > schedule_idle+0x30/0x60
> > > [542489.558121] [      T0] [c000001de047fe40] [c0000000002caed8] 
> > > do_idle+0x258/0x470
> > > [542489.558133] [      T0] [c000001de047feb0] [c0000000002cb3b4] 
> > > cpu_startup_entry+0x54/0x60
> > > [542489.558145] [      T0] [c000001de047fee0] [c00000000005a720] 
> > > start_secondary+0x860/0xd70
> > > [542489.558154] [      T0] [c000001de047ffe0] [c00000000000e158] 
> > > start_secondary_prolog+0x10/0x14
> > > [542489.558162] [      T0] Code: f8c900a8 4bfffe6c 60000000 60420000 
> > > 3c62ff87 39200001 f9410068 3d4201b2 386329d8 992aa087 4becff91 60000000 
> > > <0fe00000> e9410068 4bfff9c4 60420000
> > > [542489.558184] [      T0] ---[ end trace 0000000000000000 ]---
> > > [542521.228724] [     C59] watchdog: CPU 59 Hard LOCKUP
> > > [542521.228726] [     C59] watchdog: CPU 59 TB:3697937465165330, last 
> > > heartbeat TB:3697921085812082 (31990ms ago)
> > > [542521.228728] [     C59] Modules linked in: vhost_net vhost vhost_iotlb 
> > > tap rpadlpar_io rpaphp kvm_hv kvm mptcp_diag xsk_diag tcp_diag udp_diag 
> > > raw_diag inet_diag unix_diag af_packet_diag netlink_diag xt_conntrack 
> > > xt_MASQUERADE xfrm_user xt_set ip_set xt_addrtype nft_compat 
> > > nf_conntrack_netbios_ns nf_conntrack_broadcast nft_masq nft_fib_inet 
> > > nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 
> > > nf_reject_ipv6 nft_reject nft_ct bonding tls nft_chain_nat nf_nat 
> > > nf_conntrack tun nf_defrag_ipv6 nf_defrag_ipv4 rfkill af_packet 
> > > binfmt_misc xfs aes_gcm_p10_crypto crypto_simd ibmveth cryptd xts 
> > > vmx_crypto rtc_generic fuse nvme_fabrics ip_tables x_tables ibmvscsi 
> > > scsi_transport_srp sd_mod scsi_dh_emc scsi_dh_rdac scsi_dh_alua sg 
> > > scsi_mod scsi_common nvme nvme_core nvme_keyring nvme_auth pseries_wdt 
> > > btrfs xor libblake2b raid6_pq dm_mirror dm_region_hash dm_log dm_mod 
> > > br_netfilter bridge stp llc nf_tables
> > > [542521.228776] [     C59] CPU: 59 UID: 0 PID: 0 Comm: swapper/59 
> > > Tainted: G      D W           7.2.2-5.g6824496-default #1 PREEMPT(full) 
> > > openSUSE Tumbleweed (unreleased)  61871a5f06863b4006f5ef27cd9f18e8a7a2edad
> > > [542521.228780] [     C59] Tainted: [D]=DIE, [W]=WARN
> > > [542521.228781] [     C59] Hardware name: IBM,9824-42A Power11 
> > > (architected) 0x820200 0xf000007 of:IBM,FW1110.20 (OB1110_130) hv:phyp 
> > > pSeries
> > > [542521.228783] [     C59] NIP:  c0000000013d2c94 LR: c0000000013d5330 
> > > CTR: c000000003812be8
> > > [542521.228785] [     C59] REGS: c000003ffed2bd60 TRAP: 0100   Tainted: G 
> > >      D W            (7.2.2-5.g6824496-default)
> > > [542521.228788] [     C59] MSR:  8000000000081033 <SF,ME,IR,DR,RI,LE>  
> > > CR: 42002282  XER: 2004000e
> > > [542521.228794] [     C59] CFAR: 000000000000011c IRQMASK: 3
> > >                             GPR00: c000000000260a58 c000003ffef2fb60 
> > > c00000000205ad00 c000001deaab3c00
> > >                             GPR04: 00000000000001f8 0000000000000000 
> > > fffffffffffe0000 0000000000010000
> > >                             GPR08: 0000000000000001 0000000000000001 
> > > 000000001c82ef77 fffffffffffffffd
> > >                             GPR12: c000000003812be0 c000003fffff9f00 
> > > 0000000000000000 0000000000000000
> > >                             GPR16: 0000000000000000 0000000000000000 
> > > 0000000000000001 c000000003bc2b00
> > >                             GPR20: c000003ff40c8de8 0000000000000001 
> > > c000003ff40c8da8 c000003ffef2fe08
> > >                             GPR24: 0000000000000000 c000000003bea6e0 
> > > 000000000000003b 0000003ff0e20000
> > >                             GPR28: 0000000000780000 c0000000032bbe80 
> > > c000003ff40dbe80 c000001deaab3c00
> > > [542521.228820] [     C59] NIP [c0000000013d2c94] 
> > > queued_spin_lock_slowpath+0x164/0x19a0
> > > [542521.228824] [     C59] LR [c0000000013d5330] _raw_spin_lock+0x80/0xa0
> > > [542521.228827] [     C59] Call Trace:
> > > [542521.228827] [     C59] [c000003ffef2fb60] [0000000000001000] 0x1000 
> > > (unreliable)
> > > [542521.228833] [     C59] [c000003ffef2fc60] [c000001de0191300] 
> > > 0xc000001de0191300
> > > [542521.228836] [     C59] [c000003ffef2fc80] [c000000000260a58] 
> > > __queue_work+0x2f8/0x740
> > > [542521.228841] [     C59] [c000003ffef2fd50] [c00000000038ceac] 
> > > call_timer_fn+0x4c/0x260
> > > [542521.228845] [     C59] [c000003ffef2fde0] [c00000000038d308] 
> > > __run_timers+0x248/0x410
> > > [542521.228849] [     C59] [c000003ffef2fec0] [c00000000038d56c] 
> > > run_timer_softirq+0x9c/0x130
> > > [542521.228852] [     C59] [c000003ffef2fef0] [c00000000023ab0c] 
> > > handle_softirqs+0x14c/0x4a0
> > > [542521.228855] [     C59] [c000003ffef2ffe0] [c000000000018418] 
> > > do_softirq_own_stack+0x38/0x50
> > > [542521.228860] [     C59] [c000001de047f910] [c00000000023a238] 
> > > __irq_exit_rcu+0x198/0x1c0
> > > [542521.228862] [     C59] [c000001de047f940] [c000000000026acc] 
> > > timer_interrupt+0x1cc/0x4f0
> > > [542521.228866] [     C59] [c000001de047f9b0] [c000000000009fdc] 
> > > decrementer_common_virt+0x28c/0x290
> > > [542521.228871] [     C59] ---- interrupt: 900 at 
> > > plpar_hcall_norets_notrace+0x18/0x2c
> > > [542521.228876] [     C59] NIP:  c0000000001b7634 LR: c0000000013c4898 
> > > CTR: 0000000000000000
> > > [542521.228877] [     C59] REGS: c000001de047f9e0 TRAP: 0900   Tainted: G 
> > >      D W            (7.2.2-5.g6824496-default)
> > > [542521.228879] [     C59] MSR:  800000000280b033 
> > > <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>  CR: 22000282  XER: 2004000e
> > > [542521.228886] [     C59] CFAR: 0000000000000000 IRQMASK: 0
> > >                             GPR00: 0000000000000000 c000001de047fc80 
> > > c00000000205ad00 0000000000000000
> > >                             GPR04: 0000000000000000 0000000000000039 
> > > 0000000000000000 0000000000000000
> > >                             GPR08: ffffffffffffff7f 0000000000000000 
> > > ffffffffffffffff 0000000000000000
> > >                             GPR12: 0000000000000000 c000003fffff9f00 
> > > 0000000000000000 000000002eef9860
> > >                             GPR16: 0000000000000000 0000000000000001 
> > > 0000000000000001 c000000000058010
> > >                             GPR20: c000000000058160 0000000000000002 
> > > c000000000057fb0 c000000000057f80
> > >                             GPR24: ffffffffffffffff 0001ed6431fbb852 
> > > 0000000000000000 0000000000000001
> > >                             GPR28: 0000000000000000 0000000000000000 
> > > c0000000032a1878 c0000000032a1870
> > > [542521.228911] [     C59] NIP [c0000000001b7634] 
> > > plpar_hcall_norets_notrace+0x18/0x2c
> > > [542521.228915] [     C59] LR [c0000000013c4898] 
> > > check_and_cede_processor+0x48/0x60
> > > [542521.228918] [     C59] ---- interrupt: 900
> > > [542521.228919] [     C59] [c000001de047fc80] [ffffffffffffffff] 
> > > 0xffffffffffffffff (unreliable)
> > > [542521.228922] [     C59] [c000001de047fce0] [c0000000013c4944] 
> > > dedicated_cede_loop+0x94/0x1a0
> > > [542521.228926] [     C59] [c000001de047fd30] [c0000000013c3f00] 
> > > cpuidle_enter_state+0x300/0x748
> > > [542521.228930] [     C59] [c000001de047fde0] [c000000000f5ff10] 
> > > cpuidle_enter+0x50/0x80
> > > [542521.228935] [     C59] [c000001de047fe20] [c0000000002ba358] 
> > > call_cpuidle+0x48/0x90
> > > [542521.228939] [     C59] [c000001de047fe40] [c0000000002caf5c] 
> > > do_idle+0x2dc/0x470
> > > [542521.228942] [     C59] [c000001de047feb0] [c0000000002cb3b8] 
> > > cpu_startup_entry+0x58/0x60
> > > [542521.228945] [     C59] [c000001de047fee0] [c00000000005a720] 
> > > start_secondary+0x860/0xd70
> > > [542521.228948] [     C59] [c000001de047ffe0] [c00000000000e158] 
> > > start_secondary_prolog+0x10/0x14
> > > [542521.228951] [     C59] Code: 41810e8c 39400000 39000000 3cc0fffe 
> > > 60000000 813f0000 71290001 41820050 3ce00001 60000000 60420000 7c40003c 
> > > <71090001> 394a0001 40820028 3d2201ba
> > > [568119.679467] [     C59] pstore: dump skipped in NMI path because of 
> > > concurrent dump
> > > 
> > 
> 

And now with the entry fixes merged I can finally crash the kernel
by runnin kernel build on the host with no KVM involvement. It does lock
up during crash and requires fadump to collect vmcore.

Thanks

Michal

[ 1919.695922] [   T2102] Kernel panic - not syncing: stack-protector: Kernel 
stack is corrupted in: sys_ioctl+0xfe0/0x1060
[ 1919.695966] [   T2102] CPU: 4 UID: 0 PID: 2102 Comm: velociraptor-cl Not 
tainted 7.2.4-4.gefe5825-default #1 PREEMPT(full) openSUSE Tumbleweed 
(unreleased)  d4e9af9c041454ba4e51c7aa59aeea774951e118
[ 1919.695981] [   T2102] Hardware name: IBM,9824-42A Power11 (architected) 
0x820200 0xf000007 of:IBM,FW1110.20 (OB1110_130) hv:phyp pSeries
[ 1919.695991] [   T2102] Call Trace:
[ 1919.696653] [   T2102] ------------[ cut here ]------------
[ 1919.696665] [   T2102] Voluntary context switch within RCU read-side 
critical section!
[ 1919.696681] [   T2102] WARNING: [] kernel/rcu/tree_plugin.h:332 at 
rcu_note_context_switch+0x6a0/0x7b0, CPU#4: velociraptor-cl/2102
[ 1919.696700] [   T2102] Modules linked in: rpadlpar_io rpaphp mptcp_diag 
xsk_diag tcp_diag udp_diag raw_diag inet_diag unix_diag af_packet_diag 
netlink_diag xt_conntrack xt_MASQUERADE xfrm_user xt_set ip_set xt_addrtype 
nft_compat nf_conntrack_netbios_ns nf_conntrack_broadcast nft_masq nft_fib_inet 
nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 
nft_reject nft_ct bonding tls nft_chain_nat nf_nat nf_conntrack tun 
nf_defrag_ipv6 nf_defrag_ipv4 rfkill af_packet binfmt_misc xfs 
aes_gcm_p10_crypto crypto_simd ibmveth cryptd xts vmx_crypto rtc_generic fuse 
nvme_fabrics ip_tables x_tables ibmvscsi scsi_transport_srp sd_mod scsi_dh_emc 
scsi_dh_rdac scsi_dh_alua sg scsi_mod scsi_common nvme nvme_core nvme_keyring 
nvme_auth pseries_wdt btrfs xor libblake2b raid6_pq dm_mirror dm_region_hash 
dm_log dm_mod br_netfilter bridge stp llc nf_tables
[ 1919.696862] [   T2102] CPU: 4 UID: 0 PID: 2102 Comm: velociraptor-cl Not 
tainted 7.2.4-4.gefe5825-default #1 PREEMPT(full) openSUSE Tumbleweed 
(unreleased)  d4e9af9c041454ba4e51c7aa59aeea774951e118
[ 1919.696874] [   T2102] Hardware name: IBM,9824-42A Power11 (architected) 
0x820200 0xf000007 of:IBM,FW1110.20 (OB1110_130) hv:phyp pSeries
[ 1919.696882] [   T2102] NIP:  c00000000035e000 LR: c00000000035dffc CTR: 
0000000000000001
[ 1919.696889] [   T2102] REGS: c00000001c36b6b0 TRAP: 0700   Not tainted  
(7.2.4-4.gefe5825-default)
[ 1919.696897] [   T2102] MSR:  8000000000029033 <SF,EE,ME,IR,DR,RI,LE>  CR: 
48222200  XER: 00000000
[ 1919.696917] [   T2102] CFAR: c00000000022da28 IRQMASK: 1 
                          GPR00: c00000000035dffc c00000001c36b950 
c00000000205ad00 000000000000003f 
                          GPR04: 3ffffffffffc023a c00000001c36b670 
c00000001c36b630 0000001dd4260000 
                          GPR08: 0000000000000027 0000000000000001 
c00000002992a300 0000000048222200 
                          GPR12: c000003ff160f960 c000001ddfffb700 
c000001dd751cc80 0000000000000000 
                          GPR16: 0000000000000000 c0000000032bcc80 
0000000000000000 0000000000000000 
                          GPR20: 0000000000000000 c0000000032bcc80 
0000000000000000 0000000000000000 
                          GPR24: c00000002992a300 0000000000000000 
0000000000000000 c000000003bea6e0 
                          GPR28: 0000000000000000 c00000002992a300 
0000000000000000 c000001dd751e180 
[ 1919.697002] [   T2102] NIP [c00000000035e000] 
rcu_note_context_switch+0x6a0/0x7b0
[ 1919.697010] [   T2102] LR [c00000000035dffc] 
rcu_note_context_switch+0x69c/0x7b0
[ 1919.697018] [   T2102] Call Trace:
[ 1919.697022] [   T2102] [c00000001c36b950] [c00000000035dffc] 
rcu_note_context_switch+0x69c/0x7b0 (unreliable)
[ 1919.697033] [   T2102] [c00000001c36b9f0] [c0000000013c7e64] 
__schedule+0xf4/0x1d90
[ 1919.697045] [   T2102] [c00000001c36bb40] [c0000000013c9b48] 
schedule+0x48/0x130
[ 1919.697059] [   T2102] [c00000001c36bb70] [c0000000002c28b8] 
do_sched_yield+0xb8/0x150
[ 1919.697069] [   T2102] [c00000001c36bba0] [c0000000002c296c] 
sys_sched_yield+0x1c/0x30
[ 1919.697077] [   T2102] [c00000001c36bbc0] [c00000000002fa08] 
system_call_exception+0x188/0x430
[ 1919.697089] [   T2102] [c00000001c36be50] [c00000000000d620] 
system_call_common+0x160/0x2c4
[ 1919.697104] [   T2102] ---- interrupt: c00 at 0x100aba48
[ 1919.697113] [   T2102] NIP:  00000000100aba48 LR: 00000000100280a4 CTR: 
0000000000000000
[ 1919.697120] [   T2102] REGS: c00000001c36be80 TRAP: 0c00   Not tainted  
(7.2.4-4.gefe5825-default)
[ 1919.697126] [   T2102] MSR:  800000000000f033 <SF,EE,PR,FP,ME,IR,DR,RI,LE>  
CR: 24228408  XER: 00000000
[ 1919.697147] [   T2102] IRQMASK: 0 
                          GPR00: 000000000000009e 0000162f3b39bcc0 
0000162f3a97ac40 0000162f3a7cabc8 
                          GPR04: 0000000000000000 0000162f3a1d6e00 
0000000000000004 0000000000000101 
                          GPR08: 0000000000000005 0000000000000000 
0000000000000000 0000000000000000 
                          GPR12: 0000000000000000 00007ffdffed68c0 
0000000000000001 0000000000000001 
                          GPR16: 0000000000000000 fffffffffffffffd 
0000000000000000 000000000000000c 
                          GPR20: 0000000000800000 0000000000000001 
0000162f3b39bba0 00007ffdffece148 
                          GPR24: 00000007bd628d91 00000008c8044b7c 
00000007d72eb2ef 000000009e36057c 
                          GPR28: 0000000002c19fa3 000000006e9ed76c 
0000162f3a1d6e00 0000000000000001 
[ 1919.697230] [   T2102] NIP [00000000100aba48] 0x100aba48
[ 1919.697236] [   T2102] LR [00000000100280a4] 0x100280a4
[ 1919.697242] [   T2102] ---- interrupt: c00
[ 1919.697247] [   T2102] Code: f8c900a8 4bfffe6c 60000000 60420000 3c62ff87 
39200001 f9410068 3d4201b2 38632b78 992aa187 4becf911 60000000 <0fe00000> 
e9410068 4bfff9c4 60420000 
[ 1919.697279] [   T2102] ---[ end trace 0000000000000000 ]---
[ 1934.578776] [      C4] watchdog: CPU 4 self-detected hard LOCKUP @ 
queued_spin_lock_slowpath+0x1004/0x19a0
[ 1934.578791] [      C4] watchdog: CPU 4 TB:3717005501731461, last heartbeat 
TB:3716998337363492 (13992ms ago)
[ 1934.578794] [      C4] Modules linked in: rpadlpar_io rpaphp mptcp_diag 
xsk_diag tcp_diag udp_diag raw_diag inet_diag unix_diag af_packet_diag 
netlink_diag xt_conntrack xt_MASQUERADE xfrm_user xt_set ip_set xt_addrtype 
nft_compat nf_conntrack_netbios_ns nf_conntrack_broadcast nft_masq nft_fib_inet 
nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 
nft_reject nft_ct bonding tls nft_chain_nat nf_nat nf_conntrack tun 
nf_defrag_ipv6 nf_defrag_ipv4 rfkill af_packet binfmt_misc xfs 
aes_gcm_p10_crypto crypto_simd ibmveth cryptd xts vmx_crypto rtc_generic fuse 
nvme_fabrics ip_tables x_tables ibmvscsi scsi_transport_srp sd_mod scsi_dh_emc 
scsi_dh_rdac scsi_dh_alua sg scsi_mod scsi_common nvme nvme_core nvme_keyring 
nvme_auth pseries_wdt btrfs xor libblake2b raid6_pq dm_mirror dm_region_hash 
dm_log dm_mod br_netfilter bridge stp llc nf_tables
[ 1934.578841] [      C4] CPU: 4 UID: 399 PID: 49635 Comm: cc1 Tainted: G      
D W           7.2.4-4.gefe5825-default #1 PREEMPT(full) openSUSE Tumbleweed 
(unreleased)  d4e9af9c041454ba4e51c7aa59aeea774951e118
[ 1934.578846] [      C4] Tainted: [D]=DIE, [W]=WARN
[ 1934.578847] [      C4] Hardware name: IBM,9824-42A Power11 (architected) 
0x820200 0xf000007 of:IBM,FW1110.20 (OB1110_130) hv:phyp pSeries
[ 1934.578849] [      C4] NIP:  c0000000013d6a54 LR: c0000000013d6a38 CTR: 
0000000000000004
[ 1934.578851] [      C4] REGS: c000001ddfdd7d60 TRAP: 0900   Tainted: G      D 
W            (7.2.4-4.gefe5825-default)
[ 1934.578854] [      C4] MSR:  8000000000009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 
28002822  XER: 20040004
[ 1934.578861] [      C4] CFAR: 0000000000000000 IRQMASK: 1 
                          GPR00: c0000000013d8870 c000000021d0baf0 
c00000000205ad00 c000003ff449be88 
                          GPR04: 0000000000000250 c000001dd7507960 
00000000000b0077 c000000003bc1084 
                          GPR08: 0000000000000000 0000000000000000 
c000003ff449be80 c00000019f264400 
                          GPR12: c000000000776400 c000001ddfffb700 
0000000000000000 0000000000000000 
                          GPR16: 0000000000000000 0000000000000000 
0000000000000000 0000000000000000 
                          GPR20: 0000000000000000 0000000000000000 
0000000000000000 0000000000000000 
                          GPR24: 0000000000000000 c000000003bc1080 
c000001dd751be88 0000001dd4260000 
                          GPR28: 00000000000a0000 c0000000032bbe80 
c000001dd751be80 c000000003bc1084 
[ 1934.578887] [      C4] NIP [c0000000013d6a54] 
queued_spin_lock_slowpath+0x1004/0x19a0
[ 1934.578890] [      C4] LR [c0000000013d6a38] 
queued_spin_lock_slowpath+0xfe8/0x19a0
[ 1934.578893] [      C4] Call Trace:
[ 1934.578894] [      C4] [c000000021d0bbf0] [c0000000013d8870] 
queued_write_lock_slowpath+0x250/0x270
[ 1934.578897] [      C4] [c000000021d0bc20] [c0000000013d81bc] 
_raw_write_lock_irq+0x5c/0x70
[ 1934.578901] [      C4] [c000000021d0bc40] [c000000000237df4] 
do_exit+0x3b4/0xd00
[ 1934.578905] [      C4] [c000000021d0bd00] [c0000000002389cc] 
do_group_exit+0x3c/0xe0
[ 1934.578909] [      C4] [c000000021d0bd50] [c000000000238a94] 
sys_exit_group+0x24/0x30
[ 1934.578913] [      C4] [c000000021d0bd70] [c00000000002fa08] 
system_call_exception+0x188/0x430
[ 1934.578917] [      C4] [c000000021d0be50] [c00000000000cfdc] 
system_call_vectored_common+0x15c/0x2ec
[ 1934.578922] [      C4] ---- interrupt: 3000 at 0x7fff7fd34344
[ 1934.578926] [      C4] NIP:  00007fff7fd34344 LR: 00007fff7fd34344 CTR: 
0000000000000000
[ 1934.578928] [      C4] REGS: c000000021d0be80 TRAP: 3000   Tainted: G      D 
W            (7.2.4-4.gefe5825-default)
[ 1934.578930] [      C4] MSR:  800000000280f033 
<SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE>  CR: 44002422  XER: 00000000
[ 1934.578938] [      C4] IRQMASK: 0 
                          GPR00: 00000000000000ea 00007fffe2884cc0 
00007fff7fe96d00 0000000000000000 
                          GPR04: 0000000000000000 0000000038ed25e0 
0000000000000000 0000000000000008 
                          GPR08: 0000000000000008 0000000000000000 
0000000000000000 0000000000000000 
                          GPR12: 0000000000000000 00007fff8097dc80 
0000000000000000 0000000000000000 
                          GPR16: 0000000000000000 0000000000000000 
0000000000000000 0000000000000000 
                          GPR20: 0000000000000000 0000000000000000 
0000000000000001 0000000000000000 
                          GPR24: 00007fff7fe90828 0000000000000000 
0000000000000000 0000000000000001 
                          GPR28: 00007fff7fe99028 00007fff80977030 
fffffffffffff000 0000000000000000 
[ 1934.578962] [      C4] NIP [00007fff7fd34344] 0x7fff7fd34344
[ 1934.578964] [      C4] LR [00007fff7fd34344] 0x7fff7fd34344
[ 1934.578965] [      C4] ---- interrupt: 3000
[ 1934.578966] [      C4] Code: 3888ffff 7f474a14 f8010110 7c8407b4 4ad9b325 
fb430000 60000000 893e001d 2c090000 40820018 60420000 7c40003c <893e001d> 
2c090000 4182fff4 60000000 
[ 2710.413634] [      C4] pstore: dump skipped in NMI path because of 
concurrent dump


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