INFO: task kworker/u4:13:9038 blocked for more than 143 seconds. Not tainted 5.6.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:13 D24752 9038 2 0x80004000 Workqueue: netns cleanup_net Call Trace: context_switch kernel/sched/core.c:3386 [inline] __schedule+0x87f/0xcd0 kernel/sched/core.c:4082 schedule+0x188/0x210 kernel/sched/core.c:4156 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4215 __mutex_lock_common+0x11f1/0x2f30 kernel/locking/mutex.c:1033 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_nested+0x1b/0x30 kernel/locking/mutex.c:1118 hashlimit_proc_net_exit net/netfilter/xt_hashlimit.c:1253 [inline] hashlimit_net_exit+0x40/0x210 net/netfilter/xt_hashlimit.c:1276 ops_exit_list net/core/net_namespace.c:172 [inline] cleanup_net+0x6f8/0xb80 net/core/net_namespace.c:589 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Showing all locks held in the system: 1 lock held by khungtaskd/1117: #0: ffffffff892d98c8 (rcu_read_lock){....}, at: rcu_lock_acquire+0x4/0x30 include/linux/rcupdate.h:207 1 lock held by rsyslogd/8622: #0: ffff88809acbd5e0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x279/0x310 fs/file.c:821 2 locks held by getty/8712: #0: ffff888098e42090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900019d32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8713: #0: ffff888090e6f090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc90001a632e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8714: #0: ffff8880922bb090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc90001a432e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8715: #0: ffff8880a67a8090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc90001a532e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8716: #0: ffff8880a4547090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900019f32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8717: #0: ffff888091bc3090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc90001a332e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8718: #0: ffff8880a69ce090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900019a32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 4 locks held by kworker/u4:13/9038: #0: ffff8880a9a7e128 ((wq_completion)netns){+.+.}, at: spin_unlock_irq include/linux/spinlock.h:388 [inline] #0: ffff8880a9a7e128 ((wq_completion)netns){+.+.}, at: process_one_work+0x763/0x10f0 kernel/workqueue.c:2237 #1: ffffc90001a3fd78 (net_cleanup_work){+.+.}, at: process_one_work+0x7a5/0x10f0 kernel/workqueue.c:2239 #2: ffffffff8958f1e8 (pernet_ops_rwsem){++++}, at: cleanup_net+0xa5/0xb80 net/core/net_namespace.c:551 #3: ffffffff895adf30 (hashlimit_mutex){+.+.}, at: hashlimit_proc_net_exit net/netfilter/xt_hashlimit.c:1253 [inline] #3: ffffffff895adf30 (hashlimit_mutex){+.+.}, at: hashlimit_net_exit+0x40/0x210 net/netfilter/xt_hashlimit.c:1276 1 lock held by syz-executor.3/31845: #0: ffffffff895adf30 (hashlimit_mutex){+.+.}, at: htable_put+0x2e/0x2a0 net/netfilter/xt_hashlimit.c:432 1 lock held by syz-executor.3/31849: 1 lock held by syz-executor.1/31851: #0: ffffffff895adf30 (hashlimit_mutex){+.+.}, at: hashlimit_mt_check_common+0x4da/0x1020 net/netfilter/xt_hashlimit.c:889 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1117 Comm: khungtaskd Not tainted 5.6.0-rc1-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+0x1fb/0x318 lib/dump_stack.c:118 nmi_cpu_backtrace+0xaa/0x190 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x16f/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace+0x17/0x20 include/linux/nmi.h:146 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xd40/0xd60 kernel/hung_task.c:289 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 21 Comm: kworker/u4:1 Not tainted 5.6.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet RIP: 0010:__read_once_size include/linux/compiler.h:199 [inline] RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:31 [inline] RIP: 0010:atomic_read include/asm-generic/atomic-instrumented.h:27 [inline] RIP: 0010:rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:301 [inline] RIP: 0010:rcu_is_watching+0x62/0xa0 kernel/rcu/tree.c:919 Code: 4c 89 f7 e8 50 3c 50 00 48 c7 c3 18 80 03 00 49 03 1e 48 89 df be 04 00 00 00 e8 89 09 50 00 48 89 d8 48 c1 e8 03 42 8a 04 38 <84> c0 75 1e 8b 03 65 ff 0d 3d 34 9e 7e 74 0c 83 e0 02 d1 e8 5b 41 RSP: 0018:ffffc90000dd7b50 EFLAGS: 00000a06 RAX: 1ffff11015d67000 RBX: ffff8880aeb38018 RCX: ffffffff8163e977 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8880aeb38018 RBP: ffffc90000dd7b68 R08: dffffc0000000000 R09: ffffed1015d67004 R10: ffffed1015d67004 R11: 0000000000000000 R12: ffff88809eaab000 R13: dffffc0000000000 R14: ffffffff8908f108 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 000000004c295000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_read_lock include/linux/rcupdate.h:602 [inline] batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:754 [inline] batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:821 [inline] batadv_iv_ogm_schedule+0x3b5/0xf00 net/batman-adv/bat_iv_ogm.c:865 batadv_iv_send_outstanding_bat_ogm_packet+0x664/0x770 net/batman-adv/bat_iv_ogm.c:1718 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352