[powerpc] ftrace warning kernel/trace/ftrace.c:2068 with code-patching selftests

[Sachin Sant]

While running stress_code_patching test from selftests/powerpc/mm
against 5.17-rc1 booted on a POWER10 LPAR following ftrace warning
is seen:

WARNING: CPU: 1 PID: 2017392 at kernel/trace/ftrace.c:2068 ftrace_bug+0x274/0x2d8
Modules linked in: dm_mod bonding rfkill sunrpc pseries_rng xts vmx_crypto uio_pdrv_genirq uio sch_fq_codel ip_tables ext4 mbcache jbd2 sd_mod t10_pi sg ibmvscsi ibmveth scsi_transport_srp fuse
CPU: 1 PID: 2017392 Comm: stress_code_pat Not tainted 5.17.0-rc1-gdd81e1c7d5fb #1
NIP:  c0000000002d561c LR: c0000000002d5618 CTR: 00000000005b4448
REGS: c0000000332fb760 TRAP: 0700   Not tainted  (5.17.0-rc1-gdd81e1c7d5fb)
MSR:  800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>  CR: 48228224  XER: 00000009
CFAR: c0000000001f6b00 IRQMASK: 0 
GPR00: c0000000002d5618 c0000000332fba00 c000000002a20000 0000000000000022 
GPR04: 00000000ffff7fff c0000000332fb720 c0000000332fb718 0000000000000027 
GPR08: c00000167cca7e10 0000000000000001 0000000000000027 c0000000028d6d08 
GPR12: 0000000000008000 c00000167fa30780 0000000040000000 00007fff9a089798 
GPR16: 00007fff9a089724 00007fff9a026be8 00007fff99fbf4f0 00007fff9a08d568 
GPR20: 00007fffce533ed0 0000000000000001 00007fff9a0399d8 00007fffd9eccf94 
GPR24: 0000000000000001 0000000000000000 c0000000332fbc70 c000000000fb0d18 
GPR28: c000000000ff5080 c000000000fadd38 c0000000020032ec c0000000070800a8 
NIP [c0000000002d561c] ftrace_bug+0x274/0x2d8
LR [c0000000002d5618] ftrace_bug+0x270/0x2d8
Call Trace:
[c0000000332fba00] [c0000000002d5618] ftrace_bug+0x270/0x2d8 (unreliable)
[c0000000332fba90] [c0000000002ceaa8] ftrace_modify_all_code+0x108/0x1c0
[c0000000332fbac0] [c000000000081e58] arch_ftrace_update_code+0x18/0x110
[c0000000332fbae0] [c0000000002cec98] ftrace_run_update_code+0x58/0xe0
[c0000000332fbb10] [c0000000002d3f88] ftrace_startup+0xf8/0x1a0
[c0000000332fbb50] [c0000000002d407c] register_ftrace_function+0x4c/0xc0
[c0000000332fbb80] [c0000000002f7f88] function_trace_init+0x88/0x100
[c0000000332fbbb0] [c0000000002ee058] tracing_set_tracer+0x368/0x550
[c0000000332fbc50] [c0000000002ee358] tracing_set_trace_write+0x118/0x180
[c0000000332fbd10] [c00000000048e4c0] vfs_write+0xf0/0x340
[c0000000332fbd60] [c00000000048e8ec] ksys_write+0x7c/0x140
[c0000000332fbdb0] [c000000000033adc] system_call_exception+0x18c/0x390
[c0000000332fbe10] [c00000000000c64c] system_call_common+0xec/0x270
--- interrupt: c00 at 0x7fff99ccbd74
NIP:  00007fff99ccbd74 LR: 00007fff99c434c4 CTR: 0000000000000000
REGS: c0000000332fbe80 TRAP: 0c00   Not tainted  (5.17.0-rc1-gdd81e1c7d5fb)
MSR:  800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE>  CR: 28222222  XER: 00000000
IRQMASK: 0 
GPR00: 0000000000000004 00007fffd9eccd70 00007fff99dc7100 0000000000000001 
GPR04: 00007fffce531750 0000000000000009 0000000000000010 000000006e6f6974 
GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
GPR12: 0000000000000000 00007fff99efaeb0 0000000040000000 00007fff9a089798 
GPR16: 00007fff9a089724 00007fff9a026be8 00007fff99fbf4f0 00007fff9a08d568 
GPR20: 00007fffce533ed0 0000000000000001 00007fff9a0399d8 00007fffd9eccf94 
GPR24: 00007fffd9eccf90 00007fff9a08af94 0000000000000009 00007fffce531750 
GPR28: 0000000000000009 00007fff99dc1848 00007fffce531750 0000000000000009 
NIP [00007fff99ccbd74] 0x7fff99ccbd74
LR [00007fff99c434c4] 0x7fff99c434c4
--- interrupt: c00
Instruction dump:
48000014 3c62fe5d 38635230 4bf214c1 60000000 7fe3fb78 4bff8875 7c641b78 
3c62fe5d 38635248 4bf214a5 60000000 <0fe00000> 38210090 39000001 3d22fd66 
---[ end trace 0000000000000000 ]—

5.16 kernel was good. Git bisect points to following patch

commit 72b3942a173c387b27860ba1069636726e208777
    scripts: ftrace - move the sort-processing in ftrace_init

Have attached .config

Thanks
-Sachin

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