[powerpc] Kernel OOPS running kselftest (sigfuz)

[Sachin Sant]

While running kselftests(sigfuz) against 5.1.0 kernel (sha: 1fb3b526df)
ran into following OOPS.

Last good run was against Commit 8823880561. This is PowerNV environment.

(15/17) avocado-misc-tests/kernel/kselftest.py:kselftest.test:  
[  732.811553] sigfuz[28111]: illegal instruction (4) at 10001884 nip 10001884 lr 10001854 code 1 in sigfuz[10000000+10000]
[  732.811590] sigfuz[28111]: code: e8410018 3d206666 61296667 7d234896 7c6afe70 7d291e70 7d2a4850 552a103a 
[  732.811599] sigfuz[28111]: code: 55292036 7d2a4a14 7f834800 409e0008 <7c00055d> 38210020 e8010010 7c0803a6 
[  732.811676] Bad kernel stack pointer 7fffb949e670 at c000000000071e7c
[  732.811688] Oops: Bad kernel stack pointer, sig: 6 [#1]
[  732.811695] LE PAGE_SIZE=64K MMU=Radix MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV
[  732.811746] Dumping ftrace buffer:
[  732.811925]    (ftrace buffer empty)
[  732.811934] Modules linked in: xt_CHECKSUM xt_MASQUERADE tun bridge stp llc ip6t_rpfilter ipt_REJECT nf_reject_ipv4 ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set nfnetlink ebtable_nat ebtable_broute ip6table_nat ip6table_mangle ip6table_security ip6table_raw iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c iptable_mangle iptable_security iptable_raw ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter kvm_hv kvm i2c_dev sunrpc dm_mirror dm_region_hash dm_log dm_mod ses enclosure scsi_transport_sas sg ipmi_powernv ipmi_devintf ipmi_msghandler uio_pdrv_genirq leds_powernv uio ibmpowernv opal_prd powernv_op_panel ip_tables ext4 mbcache jbd2 sd_mod ipr libata tg3 ptp pps_core [last unloaded: kretprobe_example]
[  732.812035] CPU: 118 PID: 28112 Comm: sigfuz Tainted: G           O      5.1.0-autotest-autotest #1
[  732.812040] Bad kernel stack pointer 7fffbacce670 at c000000000071e7c
[  732.812043] NIP:  c000000000071e7c LR: 0000000024c8028d CTR: 000000001b01d9b1
[  732.812046] REGS: c0002007ff283d30 TRAP: 1500   Tainted: G           O       (5.1.0-autotest-autotest)
[  732.812063] MSR:  9000000100001031 <SF,HV,ME,IR,DR,LE,TM[E]>  CR: 52a9219f  XER: 4003a27e
[  732.812076] CFAR: c000000000071b70 IRQMASK: c000200710e42f00 
[  732.812076] GPR00: 00000000000000fa 00007fffb949e670 00007fffbaef7f00 0000000000000000 
[  732.812076] GPR04: 0000000000006dd0 000000000000000a 00000000fa7ecd56 00007fffbaeb00e4 
[  732.812076] GPR08: 0000000000006dd0 0000000000000000 0000000000000000 0000000000000000 
[  732.812076] GPR12: 0000000000000000 00007fffb94a6900 0000000000000000 0000000000000000 
[  732.812076] GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
[  732.812076] GPR20: 0000000000000000 0000000010003408 00000000100033f0 00000000100033e0 
[  732.812076] GPR24: 00000000100033b8 0000000010003390 0000000010003370 0000000010020164 
[  732.812076] GPR28: 00007fffbaef4428 00000000003d0f00 0000000010020164 000000005cd5df78 
[  732.812124] sigfuz[28118]: illegal instruction (4) at 100018a0 nip 100018a0 lr 10001828 code 1 in sigfuz[10000000+10000]
[  732.812132] NIP [c000000000071e7c] restore_gprs+0x100/0x198
[  732.812136] sigfuz[28118]: code: 552a103a 55292036 7d2a4a14 7f834800 409e0008 7c00055d 38210020 e8010010 
[  732.812141] LR [0000000024c8028d] 0x24c8028d
[  732.812142] Call Trace:
[  732.812150] sigfuz[28118]: code: 7c0803a6 4e800020 60000000 60420000 <7c00051d> 41820008 4bfff679 e8410018 
[  732.812153] Instruction dump:
[  732.812168] e8c700a0 e8a70098 f8a1fff8 e8a70078 f8a1fff0 e8e700a8 38a00000 7ca10164 
[  732.812178] 7c314ba6 e8a1fff8 e821fff0 7c0007dd <7c421378> 7db04aa6 7c314aa6 38800002 
[  732.812189] ---[ end trace 34d7d6321d88e03e ]---
[  732.812311] sigfuz[28119]: illegal instruction (4) at 100018a0 nip 100018a0 lr 10001828 code 1 in sigfuz[10000000+10000]
[  732.812325] sigfuz[28119]: code: 552a103a 55292036 7d2a4a14 7f834800 409e0008 7c00055d 38210020 e8010010 
[  732.812335] sigfuz[28119]: code: 7c0803a6 4e800020 60000000 60420000 <7c00051d> 41820008 4bfff679 e8410018 
[  732.812492] 
[  732.812496] Oops: Bad kernel stack pointer, sig: 6 [#2]
[  732.812503] LE PAGE_SIZE=64K MMU=Radix MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV
[  732.812522] Dumping ftrace buffer:
[  732.812560]    (ftrace buffer empty)

Thanks
-Sachin