WARN include/linux/trace_recursion.h:162 (powerpc)

[Sachin Sant]

Following warning is seen with 6.2.0-rc6-next-20230201 on a
Power10 server.

------------[ cut here ]------------
RCU not on for: check_return_regs_valid+0xc/0x1e0
WARNING: CPU: 9 PID: 0 at include/linux/trace_recursion.h:162 arch_ftrace_ops_list_func+0x2c0/0x2e0
Modules linked in: kmem device_dax rpadlpar_io rpaphp uinput torture vmac poly1305_generic chacha_generic chacha20poly1305 n_gsm pps_ldisc ppp_synctty ppp_async ppp_generic serport slcan can_dev slip slhc snd_hrtimer snd_seq snd_seq_device snd_timer snd soundcore pcrypt crypto_user n_hdlc dummy veth tun nfsv3 nfs_acl nfs lockd grace fscache netfs brd overlay exfat vfat fat btrfs blake2b_generic xor raid6_pq zstd_compress xfs loop sctp ip6_udp_tunnel udp_tunnel libcrc32c dm_mod bonding tls rfkill sunrpc nd_pmem nd_btt dax_pmem papr_scm pseries_rng libnvdimm vmx_crypto ext4 mbcache jbd2 sd_mod t10_pi crc64_rocksoft crc64 sg ibmvscsi scsi_transport_srp ibmveth fuse [last unloaded: ipistorm(O)]
CPU: 9 PID: 0 Comm: swapper/9 Tainted: G O 6.2.0-rc6-next-20230201 #1
Hardware name: IBM,9080-HEX POWER10 (raw) 0x800200 0xf000006 of:IBM,FW1030.00 (NH1030_026) hv:phyp pSeries
NIP: c0000000002ee8a0 LR: c0000000002ee89c CTR: 0000000000725d90
REGS: c0000003c372f530 TRAP: 0700 Tainted: G O (6.2.0-rc6-next-20230201)
MSR: 8000000000021033 <SF,ME,IR,DR,RI,LE> CR: 28002824 XER: 00000002
CFAR: c000000000159fe0 IRQMASK: 3 
GPR00: c0000000002ee89c c0000003c372f7d0 c0000000013d0e00 0000000000000031 
GPR04: 00000001000055ef c0000003c372f5a0 c0000003c372f598 0000000000000027 
GPR08: c000000efef48010 000000000559c4c9 0000000000000027 c000000002928150 
GPR12: 0000000048002824 c000000effff5300 c000000000034fc0 0000000000000000 
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
GPR24: 0000000000000000 c000000000035770 c000000000034fbc c0000003c372f8a0 
GPR28: 0000000000000000 c0000003c3686600 0000000000000000 0000000000000000 
NIP [c0000000002ee8a0] arch_ftrace_ops_list_func+0x2c0/0x2e0
LR [c0000000002ee89c] arch_ftrace_ops_list_func+0x2bc/0x2e0
Call Trace:
[c0000003c372f7d0] [c0000000002ee89c] arch_ftrace_ops_list_func+0x2bc/0x2e0 (unreliable)
[c0000003c372f870] [c000000000080bb4] ftrace_call+0x4/0x50
[c0000003c372fa20] [c000000000035770] interrupt_exit_kernel_prepare+0xb0/0x250
[c0000003c372fa70] [c00000000000da68] interrupt_return_srr_kernel+0x8/0x18c
--- interrupt: 900 at plpar_hcall_norets_notrace+0x18/0x2c
NIP: c0000000000faf80 LR: c000000000b5c5f8 CTR: 0000000000000000
REGS: c0000003c372faa0 TRAP: 0900 Tainted: G O (6.2.0-rc6-next-20230201)
MSR: 800000000280b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 22000284 XER: 00000000
CFAR: 0000000000000000 IRQMASK: 0 
GPR00: 0000000000000000 c0000003c372fd40 c0000000013d0e00 0000000000000000 
GPR04: 00000000000000c0 0000000000000080 00132735029f6191 0000000000000110 
GPR08: 000000000001f400 0000000000000001 0000000000000000 0000000000000000 
GPR12: 0000000000000090 c000000effff5300 0000000000000000 000000001eef7920 
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
GPR20: 0000000000000000 0000000000000000 0000000000000000 c0000000029f9a00 
GPR24: 0000000000000001 0000073e58cd47b6 0000000000000000 0000000000000001 
GPR28: c0000000029f9a00 0000000000000001 c0000000021620a8 c0000000021620b0 
NIP [c0000000000faf80] plpar_hcall_norets_notrace+0x18/0x2c
LR [c000000000b5c5f8] check_and_cede_processor+0x48/0x60
--- interrupt: 900
[c0000003c372fd40] [c0000003c372fd70] 0xc0000003c372fd70 (unreliable)
[c0000003c372fda0] [c000000000b5c8d8] shared_cede_loop+0x78/0x170
[c0000003c372fde0] [c000000000efb518] cpuidle_enter_state+0xa8/0x558
[c0000003c372fe80] [c000000000b59660] cpuidle_enter+0x50/0x70
[c0000003c372fec0] [c0000000001ccd2c] call_cpuidle+0x4c/0x80
[c0000003c372fee0] [c0000000001d3fa0] do_idle+0x350/0x3b0
[c0000003c372ff60] [c0000000001d4238] cpu_startup_entry+0x38/0x40
[c0000003c372ff90] [c000000000065360] start_secondary+0x290/0x2a0
[c0000003c372ffe0] [c00000000000e358] start_secondary_prolog+0x10/0x14
Code: 3b800000 4bfffdbc 60000000 60000000 3c62ffe0 39200001 3d420164 7f44d378 386330a8 992a7de9 4be6b661 60000000 <0fe00000> fb010060 60000000 60000000 
---[ end trace 0000000000000000 ]---
------------[ cut here ]------------
RCU not on for: shared_cede_loop+0xc/0x170

The code in question was added by
commit d099dbfd330686a8c09cd8944bcc77a56f9e7815
    cpuidle: tracing: Warn about !rcu_is_watching()

- Sachin