INFO: task kworker/u4:8:10521 blocked for more than 143 seconds.
      Not tainted 5.7.0-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:8    D24336 10521      2 0x80004000
Workqueue: netns cleanup_net
Call Trace:
 context_switch kernel/sched/core.c:3430 [inline]
 __schedule+0x8f3/0x1f90 kernel/sched/core.c:4156
 schedule+0xd0/0x2a0 kernel/sched/core.c:4231
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4290
 __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
 __mutex_lock+0x7b3/0x13c0 kernel/locking/mutex.c:1103
 ip_set_net_exit+0x194/0x5b0 net/netfilter/ipset/ip_set_core.c:2402
 ops_exit_list.isra.0+0xa8/0x150 net/core/net_namespace.c:186
 cleanup_net+0x511/0xa50 net/core/net_namespace.c:603
 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
 worker_thread+0x96/0xe20 kernel/workqueue.c:2414
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

Showing all locks held in the system:
4 locks held by kworker/u4:0/7:
1 lock held by khungtaskd/1149:
 #0: ffffffff899be040 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5779
1 lock held by in:imklog/6475:
 #0: ffff8880a735d8f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826
4 locks held by kworker/u4:8/10521:
 #0: ffff88821b039138 ((wq_completion)netns){+.+.}-{0:0}, at: __write_once_size include/linux/compiler.h:279 [inline]
 #0: ffff88821b039138 ((wq_completion)netns){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff88821b039138 ((wq_completion)netns){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline]
 #0: ffff88821b039138 ((wq_completion)netns){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
 #0: ffff88821b039138 ((wq_completion)netns){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline]
 #0: ffff88821b039138 ((wq_completion)netns){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline]
 #0: ffff88821b039138 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x844/0x16a0 kernel/workqueue.c:2239
 #1: ffffc90001c97dc0 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x878/0x16a0 kernel/workqueue.c:2243
 #2: ffffffff8a586130 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x9b/0xa50 net/core/net_namespace.c:565
 #3: ffffffff8d238a98 (&table[i].mutex){+.+.}-{3:3}, at: ip_set_net_exit+0x194/0x5b0 net/netfilter/ipset/ip_set_core.c:2402
3 locks held by syz-executor.5/21653:

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 1149 Comm: khungtaskd Not tainted 5.7.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
 watchdog+0xa8c/0x1010 kernel/hung_task.c:289
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 124 Comm: kworker/u4:3 Not tainted 5.7.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_nc_worker
RIP: 0010:trace_lock_release include/trace/events/lock.h:58 [inline]
RIP: 0010:lock_release+0x193/0x800 kernel/locking/lockdep.c:4976
Code: 3f 0f 87 a8 04 00 00 89 ed be 08 00 00 00 48 89 e8 48 c1 f8 06 48 8d 3c c5 00 1f 8b 8a e8 35 67 58 00 48 0f a3 2d 5d 56 31 09 <0f> 82 f2 03 00 00 48 c7 c2 14 51 8b 8a c7 44 24 48 01 00 00 00 48
RSP: 0018:ffffc90001317c00 EFLAGS: 00000047
RAX: 0000000000000001 RBX: 1ffff92000262f83 RCX: ffffffff8159c89b
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8a8b1f00
RBP: 0000000000000001 R08: ffff8880a8ce81c0 R09: fffffbfff15163e1
R10: ffffffff8a8b1f07 R11: fffffbfff15163e0 R12: ffffffff899be040
R13: ffffffff87c0dfe6 R14: dffffc0000000000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557f1f9fab18 CR3: 0000000053e54000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 rcu_lock_release include/linux/rcupdate.h:246 [inline]
 rcu_read_unlock include/linux/rcupdate.h:688 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:411 [inline]
 batadv_nc_worker+0x21c/0x760 net/batman-adv/network-coding.c:718
 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
 worker_thread+0x96/0xe20 kernel/workqueue.c:2414
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351