kernel oops with lttng enable-event test in ubuntu_lttng_smoke_test on f-hwe-5.15 ppc

Issue found on Focal 5.15.0-70.77~20.04.1 PowerPC instance on openstack.

This is not a regression, this is the first time we have openstack support.
Also, ubuntu_lttng_smoke_test is good on Jammy 5.15.0-70.77 PowerPC instance on openstack.

Command to reproduce this:
  sudo apt install lttng-modules-dkms
  sudo lttng create
  sudo lttng enable-event --kernel sched_switch

dmesg:
[ 627.080518] lttng_kretprobes: loading out-of-tree module taints kernel.
[ 627.080624] lttng_kretprobes: module verification failed: signature and/or required key missing - tainting kernel
[ 627.220129] BUG: Unable to handle kernel data access on read at 0xc008000001540000
[ 627.220224] Faulting instruction address: 0xc00000000029bbb0
[ 627.220270] Oops: Kernel access of bad area, sig: 11 [#1]
[ 627.220306] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
[ 627.220353] Modules linked in: lttng_tracer(OE+) lttng_statedump(OE) lttng_wrapper(OE) lttng_kprobes(OE) lttng_clock(OE) lttng_uprobes(OE) lttng_lib_ring_buffer(OE) lttng_kretprobes(OE) dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua binfmt_misc vmx_crypto sch_fq_codel ramoops reed_solomon pstore_blk drm pstore_zone drm_panel_orientation_quirks ip_tables x_tables autofs4 btrfs blake2b_generic zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear virtio_net crct10dif_vpmsum net_failover failover crc32c_vpmsum virtio_scsi
[ 627.220716] CPU: 2 PID: 2651 Comm: lttng-sessiond Tainted: G OE 5.15.0-70-generic #77~20.04.1-Ubuntu
[ 627.220787] NIP: c00000000029bbb0 LR: c00000000029c1d0 CTR: c00000000029bffc
[ 627.220840] REGS: c00000001ed33450 TRAP: 0300 Tainted: G OE (5.15.0-70-generic)
[ 627.220900] MSR: 800000000280b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 84228284 XER: 20040000
[ 627.220970] CFAR: c00000000029bbfc DAR: c008000001540000 DSISR: 40000000 IRQMASK: 0
               GPR00: c00000000029c1d0 c00000001ed336f0 c008000002c58100 0000000000007ec5
               GPR04: c00000001ed3375d c0080000016cbec8 c00800000153ffff 000000000000003b
               GPR08: c0080000016d0048 0000000000000001 0000000000000000 c008000001540024
               GPR12: c0080000016cc290 c0000000fff9d280 0000000000000000 c008000002e80450
               GPR16: 0000000000000000 c00000001ed33d00 c0000000028a47e0 0000000000007e8c
               GPR20: 0000000000000162 c008000002c40150 c008000002c40190 0000000000000038
               GPR24: 0000000000000030 0000000000000028 0000000000000020 0000000000000000
               GPR28: 0000000000000018 0000000000000010 00000000f9010028 0000000000000008
[ 627.221439] NIP [c00000000029bbb0] kallsyms_expand_symbol.constprop.0+0x60/0xc0
[ 627.221492] LR [c00000000029c1d0] kallsyms_lookup_name+0x1e0/0x330
[ 627.221536] Call Trace:
[ 627.221553] [c00000001ed336f0] [c0000000002e664c] register_kprobe.part.0+0x63c/0x760 (unreliable)
[ 627.221614] [c00000001ed33810] [c008000002c302d4] wrapper_kallsyms_lookup_name+0x4c/0xf0 [lttng_wrapper]
[ 627.221678] [c00000001ed33880] [c008000002c300b0] wrapper_get_pfnblock_flags_mask_init+0x28/0x60 [lttng_wrapper]
[ 627.221746] [c00000001ed338a0] [c008000002e52a44] lttng_events_init+0x40/0x268 [lttng_tracer]
[ 627.221829] [c00000001ed33940] [c000000000012370] do_one_initcall+0x60/0x2c0
[ 627.221881] [c00000001ed33a10] [c00000000029726c] do_init_module+0x6c/0x2c0
[ 627.221925] [c00000001ed33a90] [c000000000299ecc] load_module+0x170c/0x1d60
[ 627.221969] [c00000001ed33c90] [c00000000029a884] __do_sys_finit_module+0xd4/0x160
[ 627.222021] [c00000001ed33db0] [c00000000002f254] system_call_exception+0x114/0x2c0
[ 627.222073] [c00000001ed33e10] [c00000000000c74c] system_call_common+0xec/0x250
[ 627.222125] --- interrupt: c00 at 0x75c441c422b4
[ 627.222159] NIP: 000075c441c422b4 LR: 000075c44223fdac CTR: 0000000000000000
[ 627.222209] REGS: c00000001ed33e80 TRAP: 0c00 Tainted: G OE (5.15.0-70-generic)
[ 627.222267] MSR: 800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 24222248 XER: 00000000
[ 627.222334] IRQMASK: 0
               GPR00: 0000000000000161 000075c42ffeae90 000075c441d37100 0000000000000048
               GPR04: 000075c44224bd70 0000000000000000 0000000000000000 0000000000000000
               GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
               GPR12: 0000000000000000 000075c430006400 0000000000000000 000075c42fffd8dc
               GPR16: 000075c42fffd8d8 0000000000000000 000075c42fffdd90 0000000000000000
               GPR20: 0000000000000000 00000542f596e238 000075c420008e60 00000542f596e2a0
               GPR24: 000075c4200150c0 0000000000000001 000075c42ffeb108 000075c42000b970
               GPR28: 000075c44224bd70 0000000000000000 0000000000000000 000075c42000b9c0
[ 627.222748] NIP [000075c441c422b4] 0x75c441c422b4
[ 627.222782] LR [000075c44223fdac] 0x75c44223fdac
[ 627.222816] --- interrupt: c00
[ 627.222842] Instruction dump:
[ 627.222867] 78630020 4182007c 3949ffff 3d22fea7 39660001 38e00080 39894190 794a0020
[ 627.222922] 3d22fea7 7d6b5214 38a93dc8 39200000 <8d460001> 794a0fa4 7d0c522e 7d4540ae
[ 627.222978] ---[ end trace 50750693ada97fa7 ]---