ftrace in ubuntu_kernel_selftests hang at step 16 "[16] event tracing - enable/disable with event level files"

Issue found on 5.15.0-37-generic with node wright-kernel (ThunderX arm64)

The ftrace test will hang after step 15:
 time sudo ./ftracetest
=== Ftrace unit tests ===
[1] Basic trace file check [PASS]
[2] Basic test for tracers [PASS]
[3] Basic trace clock test [PASS]
[4] Basic event tracing check [PASS]
[5] Change the ringbuffer size [PASS]
[6] Snapshot and tracing setting [PASS]
[7] trace_pipe and trace_marker [PASS]
[8] Test ftrace direct functions against tracers [UNRESOLVED]
[9] Test ftrace direct functions against kprobes [UNRESOLVED]
[10] Generic dynamic event - add/remove eprobe events [PASS]
[11] Generic dynamic event - add/remove kprobe events [PASS]
[12] Generic dynamic event - add/remove synthetic events [PASS]
[13] Generic dynamic event - selective clear (compatibility) [PASS]
[14] Generic dynamic event - generic clear event [PASS]
[15] Generic dynamic event - check if duplicate events are caught [PASS]
[16] event tracing - enable/disable with event level files

This kernel trace can be found in syslog:
[29986.536581] Unable to handle kernel access to user memory outside uaccess routines at virtual address 0000000e00000000
[29986.547476] Mem abort info:
[29986.550352] ESR = 0x96000004
[29986.553487] EC = 0x25: DABT (current EL), IL = 32 bits
[29986.558890] SET = 0, FnV = 0
[29986.562003] EA = 0, S1PTW = 0
[29986.565202] FSC = 0x04: level 0 translation fault
[29986.570161] Data abort info:
[29986.573095] ISV = 0, ISS = 0x00000004
[29986.577000] CM = 0, WnR = 0
[29986.580001] user pgtable: 4k pages, 48-bit VAs, pgdp=0000010097660000
[29986.586557] [0000000e00000000] pgd=0000000000000000, p4d=0000000000000000
[29986.593468] Internal error: Oops: 96000004 [#1] SMP
[29986.598405] Modules linked in: binfmt_misc tls nls_iso8859_1 cavium_rng_vf thunderx_zip thunderx_edac cavium_rng uio_pdrv_genirq uio efi_pstore ipmi_ssif sch_fq_codel dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua ipmi_devintf ipmi_msghandler ip_tables x_tables autofs4 btrfs blake2b_generic zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor xor_neon raid6_pq libcrc32c raid1 raid0 multipath linear nicvf cavium_ptp crct10dif_ce ghash_ce sha2_ce sha256_arm64 sha1_ce nicpf ast drm_vram_helper drm_ttm_helper ttm i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops cec rc_core drm thunder_bgx gpio_keys ahci thunder_xcv i2c_thunderx mdio_thunder xhci_pci thunderx_mmc mdio_cavium xhci_pci_renesas aes_neon_bs aes_neon_blk aes_ce_blk crypto_simd cryptd aes_ce_cipher
[29986.672233] CPU: 50 PID: 29084 Comm: cat Not tainted 5.15.0-37-generic #39-Ubuntu
[29986.679806] Hardware name: Cavium ThunderX CRB/To be filled by O.E.M., BIOS 5.11 12/12/2012
[29986.688253] pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[29986.695296] pc : __pi_strlen+0x14/0x150
[29986.699182] lr : trace_seq_puts+0x28/0xa0
[29986.703238] sp : ffff8000855c3ae0
[29986.706589] x29: ffff8000855c3ae0 x28: ffff0100072afce0 x27: ffff8000091277d0
[29986.713815] x26: ffff0100562f60c8 x25: ffff0100562f50c8 x24: ffff0100562f50c8
[29986.721040] x23: ffff01012be44004 x22: 00000000019aa301 x21: 0000000000000000
[29986.728271] x20: 0000000e00000000 x19: ffff0100562f50c8 x18: 0000000000000000
[29986.735499] x17: 0000000000000000 x16: 000039362f726570 x15: 523d65746174735f
[29986.742723] x14: 0000000000000001 x13: ffff8000855c37f0 x12: 000000000000000f
[29986.749947] x11: 0000000000000010 x10: 0000000000000020 x9 : ffff800009163d28
[29986.757170] x8 : 0101010101010101 x7 : 7f7f7f7f7f7f7f7f x6 : 000000000000003a
[29986.764394] x5 : ffff0100562f510c x4 : 0000000000000000 x3 : ffff0100562f50c8
[29986.771617] x2 : 0000000000000002 x1 : 0000000e00000000 x0 : 0000000e00000000
[29986.778841] Call trace:
[29986.781314] __pi_strlen+0x14/0x150
[29986.784845] trace_bputs_print+0x54/0x74
[29986.788814] print_trace_fmt+0x118/0x1d4
[29986.792802] print_trace_line+0x104/0x3a0
[29986.796880] s_show+0x3c/0x210
[29986.799975] seq_read_iter+0x3c4/0x4d0
[29986.803769] seq_read+0xe4/0x140
[29986.810035] vfs_read+0xb8/0x1f0
[29986.816261] ksys_read+0x74/0x100
[29986.822561] __arm64_sys_read+0x28/0x34
[29986.829284] invoke_syscall+0x78/0x100
[29986.835830] el0_svc_common.constprop.0+0x54/0x184
[29986.843443] do_el0_svc+0x34/0x9c
[29986.849579] el0_svc+0x48/0x1b0
[29986.855524] el0t_64_sync_handler+0xa4/0x130
[29986.862597] el0t_64_sync+0x1a4/0x1a8
[29986.869047] Code: 92402c04 b200c3e8 f13fc09f 5400088c (a9400c02)
[29986.877713] ---[ end trace f503bf106aad21c4 ]---

This is not a regression, we can see this node hanging at the very same point in previous cycles.