[syzbot] WARNING: locking bug in __perf_event_task_sched_in (2)

[syzbot] WARNING: locking bug in __perf_event_task_sched_in (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    6d0c4b11e743 libbpf: Poison strlcpy()
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17764f3a480000
kernel config:  https://syzkaller.appspot.com/x/.config?x=46221e8203c7aca6
dashboard link: https://syzkaller.appspot.com/bug?extid=d94d214ea473e218fc89
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/83567aa48724/disk-6d0c4b11.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6047fdb8660e/vmlinux-6d0c4b11.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a94d1047d7b7/bzImage-6d0c4b11.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d94d214ea473e218fc89@syzkaller.appspotmail.com

------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(1)
WARNING: CPU: 1 PID: 6975 at kernel/locking/lockdep.c:231 hlock_class kernel/locking/lockdep.c:231 [inline]
WARNING: CPU: 1 PID: 6975 at kernel/locking/lockdep.c:231 hlock_class kernel/locking/lockdep.c:220 [inline]
WARNING: CPU: 1 PID: 6975 at kernel/locking/lockdep.c:231 check_wait_context kernel/locking/lockdep.c:4754 [inline]
WARNING: CPU: 1 PID: 6975 at kernel/locking/lockdep.c:231 __lock_acquire+0xecf/0x56d0 kernel/locking/lockdep.c:5005
Modules linked in:
CPU: 1 PID: 6975 Comm: kworker/u4:13 Not tainted 6.2.0-rc2-syzkaller-00302-g6d0c4b11e743 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: netns cleanup_net
RIP: 0010:hlock_class kernel/locking/lockdep.c:231 [inline]
RIP: 0010:hlock_class kernel/locking/lockdep.c:220 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4754 [inline]
RIP: 0010:__lock_acquire+0xecf/0x56d0 kernel/locking/lockdep.c:5005
Code: 28 14 73 8e e8 02 bb 6b 00 8b 05 94 78 0f 0d 85 c0 0f 85 79 f8 ff ff 48 c7 c6 40 51 4c 8a 48 c7 c7 a0 4a 4c 8a e8 51 d6 5b 08 <0f> 0b 31 c0 e9 73 f7 ff ff 48 63 5c 24 18 be 08 00 00 00 48 89 d8
RSP: 0018:ffffc900035ef518 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 000000000000070e RCX: 0000000000000000
RDX: ffff888079031d40 RSI: ffffffff8166724c RDI: fffff520006bde95
RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000002 R11: 0000000000000001 R12: 0000000000000003
R13: ffff888079031d40 R14: ffff888079032778 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc92edd748 CR3: 0000000044fa3000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lock_acquire kernel/locking/lockdep.c:5668 [inline]
 lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
 rcu_lock_acquire include/linux/rcupdate.h:325 [inline]
 rcu_read_lock include/linux/rcupdate.h:764 [inline]
 perf_event_context_sched_in kernel/events/core.c:3913 [inline]
 __perf_event_task_sched_in+0xe2/0x6c0 kernel/events/core.c:3980
 perf_event_task_sched_in include/linux/perf_event.h:1328 [inline]
 finish_task_switch.isra.0+0x5e5/0xc80 kernel/sched/core.c:5118
 context_switch kernel/sched/core.c:5247 [inline]
 __schedule+0xb92/0x5450 kernel/sched/core.c:6555
 schedule+0xde/0x1b0 kernel/sched/core.c:6631
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6690
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0xa48/0x1360 kernel/locking/mutex.c:747
 devl_lock net/devlink/core.c:54 [inline]
 devlink_pernet_pre_exit+0x10a/0x220 net/devlink/core.c:301
 ops_pre_exit_list net/core/net_namespace.c:159 [inline]
 cleanup_net+0x455/0xb10 net/core/net_namespace.c:594
 process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
 worker_thread+0x669/0x1090 kernel/workqueue.c:2436
 kthread+0x2e8/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>


---
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Re: [syzbot] WARNING: locking bug in __perf_event_task_sched_in (2)

[Jakub Kicinski]

On Tue, 10 Jan 2023 12:50:48 -0800 syzbot wrote:
>  <TASK>
>  lock_acquire kernel/locking/lockdep.c:5668 [inline]
>  lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
>  rcu_lock_acquire include/linux/rcupdate.h:325 [inline]
>  rcu_read_lock include/linux/rcupdate.h:764 [inline]
>  perf_event_context_sched_in kernel/events/core.c:3913 [inline]
>  __perf_event_task_sched_in+0xe2/0x6c0 kernel/events/core.c:3980
>  perf_event_task_sched_in include/linux/perf_event.h:1328 [inline]
>  finish_task_switch.isra.0+0x5e5/0xc80 kernel/sched/core.c:5118
>  context_switch kernel/sched/core.c:5247 [inline]
>  __schedule+0xb92/0x5450 kernel/sched/core.c:6555
>  schedule+0xde/0x1b0 kernel/sched/core.c:6631
>  schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6690
>  __mutex_lock_common kernel/locking/mutex.c:679 [inline]
>  __mutex_lock+0xa48/0x1360 kernel/locking/mutex.c:747
>  devl_lock net/devlink/core.c:54 [inline]
>  devlink_pernet_pre_exit+0x10a/0x220 net/devlink/core.c:301
>  ops_pre_exit_list net/core/net_namespace.c:159 [inline]
>  cleanup_net+0x455/0xb10 net/core/net_namespace.c:594
>  process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
>  worker_thread+0x669/0x1090 kernel/workqueue.c:2436
>  kthread+0x2e8/0x3a0 kernel/kthread.c:376
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
>  </TASK>

Yes, I pooped it. We need to keep the mutex around as well as 
the devlink instance memory, otherwise locked screams.
Fix building..