Message-ID: <20241217164810.2a9bcb57@gandalf.local.home>
Date: Tue, 17 Dec 2024 16:48:10 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: syzbot <syzbot+a1d25e53cd4a10f7f2d3@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
 mathieu.desnoyers@...icios.com, mhiramat@...nel.org,
 syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [trace?] WARNING in tracepoint_probe_unregister (3)

On Tue, 17 Dec 2024 13:14:29 -0800
syzbot <syzbot+a1d25e53cd4a10f7f2d3@...kaller.appspotmail.com> wrote:

> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    243f750a2df0 Merge tag 'gpio-fixes-for-v6.13-rc3' of git:/..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1310a4f8580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=99a5586995ec03b2
> dashboard link: https://syzkaller.appspot.com/bug?extid=a1d25e53cd4a10f7f2d3
> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/939c742e99e7/disk-243f750a.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/76db565b11d6/vmlinux-243f750a.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/822230eb0753/bzImage-243f750a.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+a1d25e53cd4a10f7f2d3@...kaller.appspotmail.com
> 

BTW,

If you are injecting faults and hitting bugs when you do.

   PLEASE REPORT YOU ARE INJECTING FAULTS!!!

It just happened that I looked at the above console output to know that.
Without that information, this would never be solved, as the memory
failures you are injecting are for things that are less than a page and
would only happen when the system is dangerously low on memory.

Knowing that this was caused after fault injection is critical knowledge!

Without that knowledge, this can be a big waste of time for maintainers who
will go off on wild goose chases trying to figure out what's wrong with the
logic, when it really was simply a missed check of something that didn't
get allocated, that would also never not get allocated unless the system
was in dire straits.

-- Steve


> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 8817 at kernel/tracepoint.c:358 tracepoint_remove_func kernel/tracepoint.c:358 [inline]
> WARNING: CPU: 0 PID: 8817 at kernel/tracepoint.c:358 tracepoint_probe_unregister+0x894/0xd70 kernel/tracepoint.c:504
> Modules linked in:
> CPU: 0 UID: 0 PID: 8817 Comm: syz.3.789 Not tainted 6.13.0-rc2-syzkaller-00192-g243f750a2df0 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
> RIP: 0010:tracepoint_remove_func kernel/tracepoint.c:358 [inline]
> RIP: 0010:tracepoint_probe_unregister+0x894/0xd70 kernel/tracepoint.c:504
> Code: 41 5e 41 5f c3 cc cc cc cc e8 68 27 fe ff 48 c7 c6 60 05 9b 81 48 89 df e8 79 52 e5 ff eb 9f bb fe ff ff ff e8 4d 27 fe ff 90 <0f> 0b 90 eb 91 e8 42 27 fe ff 48 89 da 48 b8 00 00 00 00 00 fc ff
> RSP: 0018:ffffc90003427898 EFLAGS: 00010287
> RAX: 000000000000951e RBX: 00000000fffffffe RCX: ffffc9000c9ec000
> RDX: 0000000000080000 RSI: ffffffff819b16a3 RDI: 0000000000000005
> RBP: ffffffff8ecbb240 R08: 0000000000000005 R09: 0000000000000000
> R10: 0000000000000001 R11: 0000000000000003 R12: ffffffff81a0da30
> R13: 0000000000000602 R14: 0000000000000002 R15: ffffffff8de3f8d8
> FS:  00007fe8b075e6c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fe8b075df98 CR3: 000000007a564000 CR4: 00000000003526f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  unregister_trace_sched_switch include/trace/events/sched.h:222 [inline]
>  tracing_sched_unregister kernel/trace/trace_sched_switch.c:87 [inline]
>  tracing_stop_sched_switch kernel/trace/trace_sched_switch.c:129 [inline]
>  tracing_stop_cmdline_record+0x66/0xa0 kernel/trace/trace_sched_switch.c:140
>  __ftrace_event_enable_disable+0x73f/0x850 kernel/trace/trace_events.c:645
>  ftrace_event_enable_disable kernel/trace/trace_events.c:730 [inline]
>  ftrace_clear_events kernel/trace/trace_events.c:739 [inline]
>  ftrace_event_set_open+0x238/0x2d0 kernel/trace/trace_events.c:2270
>  do_dentry_open+0xf59/0x1ea0 fs/open.c:945
>  vfs_open+0x82/0x3f0 fs/open.c:1075
>  do_open fs/namei.c:3828 [inline]
>  path_openat+0x1e6a/0x2d60 fs/namei.c:3987
>  do_filp_open+0x20c/0x470 fs/namei.c:4014
>  do_sys_openat2+0x17a/0x1e0 fs/open.c:1402
>  do_sys_open fs/open.c:1417 [inline]
>  __do_sys_openat fs/open.c:1433 [inline]
>  __se_sys_openat fs/open.c:1428 [inline]
>  __x64_sys_openat+0x175/0x210 fs/open.c:1428
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fe8af985d19
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fe8b075e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 00007fe8afb75fa0 RCX: 00007fe8af985d19
> RDX: 0000000000020201 RSI: 0000000020000100 RDI: ffffffffffffff9c
> RBP: 00007fe8afa01a20 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 0000000000000001 R14: 00007fe8afb75fa0 R15: 00007ffd25015738
>  </TASK>
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
> 
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
> 
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup

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