Kernel WARNING at lib/vsprintf.c:2721 while running ftrace kernel selftests

[Sachin Sant]

While running ftrace specific kernel selftests following warning
is seen on a Power10 logical partition (LPAR) booted with
latest mainline kernel.

------------[ cut here ]------------
precision 63492 too large
WARNING: CPU: 15 PID: 2538829 at lib/vsprintf.c:2721 set_precision+0x68/0xa4
Modules linked in: nvram 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 netfs brd overlay exfat vfat fat btrfs blake2b_generic xor raid6_pq zstd_compress xfs loop sctp ip6_udp_tunnel udp_tunnel nfsd auth_rpcgss nfs_acl lockd grace configs dm_mod nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 bonding rfkill tls ip_set nf_tables libcrc32c nfnetlink sunrpc pseries_rng vmx_crypto ext4 mbcache jbd2 sd_mod t10_pi crc64_rocksoft crc64 sg ibmvscsi ibmveth scsi_transport_srp fuse [last unloaded: test_cpuidle_latency(O)]
CPU: 15 PID: 2538829 Comm: awk Tainted: G M O K 6.8.0-rc5-gfca7526b7d89 #1
Hardware name: IBM,9080-HEX POWER10 (raw) 0x800200 0xf000006 of:IBM,FW1060.00 (NH1060_018) hv:phyp pSeries
NIP: c000000000f57c34 LR: c000000000f57c30 CTR: c000000000f5cdf0
REGS: c000000a58e4f5f0 TRAP: 0700 Tainted: G M O K (6.8.0-rc5-gfca7526b7d89)
MSR: 8000000002029033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR: 48000824 XER: 00000005
CFAR: c00000000016154c IRQMASK: 0 
GPR00: c000000000f57c30 c000000a58e4f890 c000000001482800 0000000000000019 
GPR04: 0000000100011559 c000000a58e4f660 c000000a58e4f658 0000000000000027 
GPR08: c000000e84e37c10 0000000000000001 0000000000000027 c000000002a47e50 
GPR12: 0000000000000000 c000000e87bf7300 0000000000000000 0000000000000000 
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
GPR20: c0000004a43ec590 0000000000400cc0 0000000000000003 c0000000012c3e65 
GPR24: c000000a58e4fa18 0000000000000025 0000000000000020 000000000001ff97 
GPR28: c0000001168a00dd c0000001168c0074 c000000a58e4f920 000000000000f804 
NIP [c000000000f57c34] set_precision+0x68/0xa4
LR [c000000000f57c30] set_precision+0x64/0xa4
Call Trace:
[c000000a58e4f890] [c000000000f57c30] set_precision+0x64/0xa4 (unreliable)
[c000000a58e4f900] [c000000000f5ccc4] vsnprintf+0x198/0x4c8
[c000000a58e4f980] [c000000000f53228] seq_buf_vprintf+0x50/0xa0
[c000000a58e4f9b0] [c00000000031cec0] trace_seq_printf+0x60/0xe0
[c000000a58e4f9e0] [c00000000031b5f0] trace_print_print+0x78/0xa4
[c000000a58e4fa60] [c0000000003133a4] print_trace_line+0x2ac/0x6d8
[c000000a58e4fb20] [c0000000003145c0] s_show+0x58/0x2c0
[c000000a58e4fba0] [c0000000005dfb2c] seq_read_iter+0x448/0x618
[c000000a58e4fc70] [c0000000005dfe08] seq_read+0x10c/0x174
[c000000a58e4fd10] [c00000000059a7e0] vfs_read+0xe0/0x39c
[c000000a58e4fdc0] [c00000000059b59c] ksys_read+0x7c/0x140
[c000000a58e4fe10] [c000000000035d74] system_call_exception+0x134/0x330
[c000000a58e4fe50] [c00000000000d6a0] system_call_common+0x160/0x2e4
--- interrupt: c00 at 0x7fff84521684
NIP: 00007fff84521684 LR: 00000001252f0dc4 CTR: 0000000000000000
REGS: c000000a58e4fe80 TRAP: 0c00 Tainted: G M O K (6.8.0-rc5-gfca7526b7d89)
MSR: 800000000000f033 <SF,EE,PR,FP,ME,IR,DR,RI,LE> CR: 22000202 XER: 00000000
IRQMASK: 0 
GPR00: 0000000000000003 00007fffcd076c30 00007fff84607300 0000000000000005 
GPR04: 000000012a8a1a20 0000000000010000 fffffffffffffff5 000000012a9bcce6 
GPR08: 0000000000000001 0000000000000000 0000000000000000 0000000000000000 
GPR12: 0000000000000000 00007fff84a5d2a0 0000000000000001 000000012a8851d8 
GPR16: 000000012a884268 00007fff84601888 0000000125377f50 00007fff84601880 
GPR20: 0000000000000044 000000000000000f ffffffffffffffff 0000000000000000 
GPR24: 00007fffcd076e48 00007fffcd076d98 0000000000000000 0000000000000000 
GPR28: 00007fffcd076e48 0000000000000000 00007fffcd076da0 000000012a8a1900 
NIP [00007fff84521684] 0x7fff84521684
LR [00000001252f0dc4] 0x1252f0dc4
--- interrupt: c00
Code: f821ff91 2f890000 409e0034 7c0802a6 3c62fff0 39200001 3d420177 3863e310 992ad6db f8010080 4b209899 60000000 <0fe00000> e8010080 7c0803a6 2f9f0000 
---[ end trace 0000000000000000 ]—

This warning is seen while running test that was added by
following commit:

commit 3bf7009251f0f41cdd0188ab7b3879df81810703
     tracing/selftests: Add test to test the trace_marker


- Sachin