Call Trace: with rmmod

[zenglg]

rmmod tracepoint_sample

Some Call Trace in dmesg

[Thu Aug 25 16:03:00 2022] ------------[ cut here ]------------
[Thu Aug 25 16:03:00 2022] WARNING: CPU: 1 PID: 52758 at kernel/tracepoint.c:636 tracepoint_module_notify+0x1b7/0x1c0
[Thu Aug 25 16:03:00 2022] Modules linked in: tracepoint_sample(OE-) uinput snd_seq_dummy snd_hrtimer nft_objref nf_conntrack_netbios_ns nf_conntrack_broadcast 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 ip_set rfkill nf_tables nfnetlink qrtr ns sunrpc snd_hda_codec_generic ledtrig_audio snd_hda_intel snd_intel_dspcfg snd_intel_sdw_acpi snd_hda_codec snd_hda_core snd_hwdep snd_seq kvm_intel snd_seq_device snd_pcm iTCO_wdt kvm intel_pmc_bxt iTCO_vendor_support snd_timer irqbypass snd soundcore joydev i2c_i801 pcspkr i2c_smbus virtio_balloon lpc_ich zram ip_tables crct10dif_pclmul crc32_pclmul crc32c_intel qxl drm_ttm_helper ttm drm_kms_helper ghash_clmulni_intel cec drm serio_raw virtio_net virtio_blk net_failover failover virtio_console qemu_fw_cfg fuse [last unloaded: tracepoint_sample]
[Thu Aug 25 16:03:00 2022] CPU: 1 PID: 52758 Comm: rmmod Tainted: G           OE     5.14.10-300.fc35.x86_64 #1
[Thu Aug 25 16:03:00 2022] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
[Thu Aug 25 16:03:00 2022] RIP: 0010:tracepoint_module_notify+0x1b7/0x1c0
[Thu Aug 25 16:03:00 2022] Code: c7 a0 0e fb b4 e8 59 6e a6 00 b8 01 00 00 00 5b 5d 41 5c c3 48 c7 c7 a0 0e fb b4 e8 43 6e a6 00 b8 0d 80 00 00 5b 5d 41 5c c3 <0f> 0b eb c7 0f 1f 44 00 00 0f 1f 44 00 00 41 57 41 56 41 55 49 89
[Thu Aug 25 16:03:00 2022] RSP: 0018:ffffb6a38176be88 EFLAGS: 00010282
[Thu Aug 25 16:03:00 2022] RAX: ffffffffc0ab7000 RBX: ffffffffc0ab9080 RCX: ffffffffc0ab7004
[Thu Aug 25 16:03:00 2022] RDX: 0000000000002020 RSI: 000000008080005d RDI: fffffb2380a86d60
[Thu Aug 25 16:03:00 2022] RBP: ffff98122a1b5ac0 R08: 0000000000000001 R09: 0000000000000000
[Thu Aug 25 16:03:00 2022] R10: ffffb6a38176bd00 R11: 0000000000000001 R12: 0000000000000001
[Thu Aug 25 16:03:00 2022] R13: ffffffffc0ab9080 R14: ffffffffb4fa89a0 R15: 00000000fffffff6
[Thu Aug 25 16:03:00 2022] FS:  00007fecee47a740(0000) GS:ffff98127dd00000(0000) knlGS:0000000000000000
[Thu Aug 25 16:03:00 2022] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[Thu Aug 25 16:03:00 2022] CR2: 000055ab542bd2c8 CR3: 0000000007c54001 CR4: 0000000000020ee0
[Thu Aug 25 16:03:00 2022] Call Trace:
[Thu Aug 25 16:03:00 2022]  blocking_notifier_call_chain+0x5d/0x80
[Thu Aug 25 16:03:00 2022]  __do_sys_delete_module.constprop.0+0x188/0x280
[Thu Aug 25 16:03:00 2022]  ? exit_to_user_mode_prepare+0x14d/0x240
[Thu Aug 25 16:03:00 2022]  do_syscall_64+0x3b/0x90
[Thu Aug 25 16:03:00 2022]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[Thu Aug 25 16:03:00 2022] RIP: 0033:0x7fecee59188b
[Thu Aug 25 16:03:00 2022] Code: 73 01 c3 48 8b 0d 9d 75 0e 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 6d 75 0e 00 f7 d8 64 89 01 48
[Thu Aug 25 16:03:00 2022] RSP: 002b:00007ffe03812768 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
[Thu Aug 25 16:03:00 2022] RAX: ffffffffffffffda RBX: 000055ab542b2760 RCX: 00007fecee59188b
[Thu Aug 25 16:03:00 2022] RDX: 000000000000000a RSI: 0000000000000800 RDI: 000055ab542b27c8
[Thu Aug 25 16:03:00 2022] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[Thu Aug 25 16:03:00 2022] R10: 00007fecee622ac0 R11: 0000000000000206 R12: 00007ffe038129e0
[Thu Aug 25 16:03:00 2022] R13: 00007ffe038146cd R14: 000055ab542b22a0 R15: 000055ab542b2760
[Thu Aug 25 16:03:00 2022] ---[ end trace ac7c90bfee9c9909 ]---

Add unregister_trace_subsys_event() would solve it, please verify.

 static void __exit sample_exit(void)
 {
        printk(KERN_ALERT "sample exit\n");
+       unregister_trace_subsys_event(my_subsys_event, NULL);
        remove_proc_entry("tracepoint-sample", NULL);
 }