INFO: task kworker/u4:8:16193 blocked for more than 140 seconds. Not tainted 4.19.211-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:8 D25848 16193 2 0x80000000 Workqueue: writeback wb_workfn (flush-7:5) Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x887/0x2040 kernel/sched/core.c:3517 schedule+0x8d/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1016 [inline] __mutex_lock+0x5f0/0x1190 kernel/locking/mutex.c:1078 f2fs_balance_fs+0x709/0xd80 fs/f2fs/segment.c:512 f2fs_write_inode+0x500/0x600 fs/f2fs/inode.c:630 write_inode fs/fs-writeback.c:1244 [inline] __writeback_single_inode+0x733/0x11d0 fs/fs-writeback.c:1442 writeback_sb_inodes+0x537/0xef0 fs/fs-writeback.c:1647 __writeback_inodes_wb+0xc6/0x280 fs/fs-writeback.c:1716 wb_writeback+0x841/0xcc0 fs/fs-writeback.c:1822 wb_check_old_data_flush fs/fs-writeback.c:1924 [inline] wb_do_writeback fs/fs-writeback.c:1977 [inline] wb_workfn+0x8ba/0x1250 fs/fs-writeback.c:2006 process_one_work+0x864/0x1570 kernel/workqueue.c:2153 worker_thread+0x64c/0x1130 kernel/workqueue.c:2296 kthread+0x33f/0x460 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Showing all locks held in the system: IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready 1 lock held by khungtaskd/1570: #0: 00000000c8e1b5cc (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4441 3 locks held by systemd-udevd/4696: #0: 00000000885bc95a (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1826 [inline] #0: 00000000885bc95a (&rq->lock){-.-.}, at: __schedule+0x1f9/0x2040 kernel/sched/core.c:3455 #1: 00000000c8e1b5cc (rcu_read_lock){....}, at: trace_sched_stat_runtime include/trace/events/sched.h:428 [inline] #1: 00000000c8e1b5cc (rcu_read_lock){....}, at: update_curr+0x2c3/0x870 kernel/sched/fair.c:857 #2: 0000000050e3f079 (kn->count#24){++++}, at: kernfs_seq_start+0x75/0x260 fs/kernfs/file.c:113 1 lock held by in:imklog/7830: #0: 00000000617e0ac0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767 1 lock held by syz-fuzzer/8163: 2 locks held by kworker/0:1/8379: #0: 00000000abdfee12 ((wq_completion)"rcu_gp"){+.+.}, at: process_one_work+0x767/0x1570 kernel/workqueue.c:2124 #1: 0000000052168c15 ((work_completion)(&rew.rew_work)){+.+.}, at: process_one_work+0x79c/0x1570 kernel/workqueue.c:2128 3 locks held by kworker/u4:4/8891: #0: 00000000cebef68e ((wq_completion)"%s""netns"){+.+.}, at: process_one_work+0x767/0x1570 kernel/workqueue.c:2124 #1: 00000000885c1f7e (net_cleanup_work){+.+.}, at: process_one_work+0x79c/0x1570 kernel/workqueue.c:2128 #2: 000000001718afd8 (pernet_ops_rwsem){++++}, at: cleanup_net+0xa8/0x8b0 net/core/net_namespace.c:521 4 locks held by kworker/u4:8/16193: #0: 000000008549e39b ((wq_completion)"writeback"){+.+.}, at: process_one_work+0x767/0x1570 kernel/workqueue.c:2124 #1: 000000004524c142 ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0x79c/0x1570 kernel/workqueue.c:2128 #2: 0000000035396b03 (&type->s_umount_key#84){++++}, at: trylock_super+0x1d/0x100 fs/super.c:412 #3: 0000000013ce5afe (&sbi->gc_mutex){+.+.}, at: f2fs_balance_fs+0x709/0xd80 fs/f2fs/segment.c:512 3 locks held by syz-executor.5/15049: 2 locks held by syz-executor.1/22742: #0: 0000000053cef296 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline] #0: 0000000053cef296 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x3fe/0xb80 net/core/rtnetlink.c:4779 #1: 00000000b4910c6b (rcu_preempt_state.exp_mutex){+.+.}, at: exp_funnel_lock kernel/rcu/tree_exp.h:297 [inline] #1: 00000000b4910c6b (rcu_preempt_state.exp_mutex){+.+.}, at: _synchronize_rcu_expedited+0x4dc/0x6f0 kernel/rcu/tree_exp.h:667 1 lock held by syz-executor.4/22752: #0: 0000000053cef296 (rtnl_mutex){+.+.}, at: ipv6_route_ioctl+0x21a/0x2f0 net/ipv6/route.c:3725 1 lock held by syz-executor.4/22754: #0: 0000000053cef296 (rtnl_mutex){+.+.}, at: ipv6_route_ioctl+0x21a/0x2f0 net/ipv6/route.c:3725 1 lock held by syz-executor.4/22758: #0: 0000000053cef296 (rtnl_mutex){+.+.}, at: ipv6_route_ioctl+0x21a/0x2f0 net/ipv6/route.c:3725 2 locks held by syz-executor.5/22770: #0: 0000000041a0e585 (&sb->s_type->i_mutex_key#13){+.+.}, at: inode_lock include/linux/fs.h:748 [inline] #0: 0000000041a0e585 (&sb->s_type->i_mutex_key#13){+.+.}, at: __sock_release+0x86/0x2a0 net/socket.c:598 #1: 00000000b4910c6b (rcu_preempt_state.exp_mutex){+.+.}, at: exp_funnel_lock kernel/rcu/tree_exp.h:329 [inline] #1: 00000000b4910c6b (rcu_preempt_state.exp_mutex){+.+.}, at: _synchronize_rcu_expedited+0x256/0x6f0 kernel/rcu/tree_exp.h:667 1 lock held by syz-executor.0/22755: #0: 0000000053cef296 (rtnl_mutex){+.+.}, at: ipv6_route_ioctl+0x21a/0x2f0 net/ipv6/route.c:3725 1 lock held by syz-executor.0/22764: #0: 0000000053cef296 (rtnl_mutex){+.+.}, at: ipv6_route_ioctl+0x21a/0x2f0 net/ipv6/route.c:3725 1 lock held by syz-executor.0/22781: #0: 0000000053cef296 (rtnl_mutex){+.+.}, at: ipv6_route_ioctl+0x21a/0x2f0 net/ipv6/route.c:3725 1 lock held by syz-executor.2/22756: #0: 0000000053cef296 (rtnl_mutex){+.+.}, at: ipv6_route_ioctl+0x21a/0x2f0 net/ipv6/route.c:3725 1 lock held by syz-executor.2/22766: #0: 0000000053cef296 (rtnl_mutex){+.+.}, at: ipv6_route_ioctl+0x21a/0x2f0 net/ipv6/route.c:3725 1 lock held by syz-executor.2/22782: #0: 0000000053cef296 (rtnl_mutex){+.+.}, at: ipv6_route_ioctl+0x21a/0x2f0 net/ipv6/route.c:3725 ============================================= IPv6: ADDRCONF(NETDEV_CHANGE): vxcan0: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready NMI backtrace for cpu 0 CPU: 0 PID: 1570 Comm: khungtaskd Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1a6/0x1f0 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline] watchdog+0x991/0xe60 kernel/hung_task.c:287 kthread+0x33f/0x460 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 22788 Comm: modprobe Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x4/0x20 kernel/kcov.c:188 Code: 84 00 00 00 00 00 48 8b 0c 24 0f b7 d6 0f b7 f7 bf 03 00 00 00 e9 ec fe ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 90 48 8b 0c 24 <89> f2 89 fe bf 05 00 00 00 e9 ce fe ff ff 66 66 2e 0f 1f 84 00 00 RSP: 0018:ffff88808cee7e30 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff88803bfb1430 RCX: ffffffff81a32332 RDX: 1ffff110030695b7 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88801834ad40 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000005 R11: 0000000000000000 R12: ffff88801834adbc R13: 0000000000000000 R14: ffff88803bfb1430 R15: ffff8880b5b84220 FS: 00007f552a6074c0(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f552a1b3070 CR3: 000000002ea8f000 CR4: 00000000003406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __fput+0x262/0x890 fs/file_table.c:273 task_work_run+0x148/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x251/0x2a0 arch/x86/entry/common.c:167 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f552a0baa4b Code: 48 8b 34 24 eb c5 66 0f 1f 84 00 00 00 00 00 48 c7 c0 ff ff ff ff eb c8 0f 1f 80 00 00 00 00 48 63 7f 70 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 f3 c3 0f 1f 00 48 8b 15 19 74 32 00 f7 d8 RSP: 002b:00007fff5f18bb68 EFLAGS: 00000206 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 000055f01c09e290 RCX: 00007f552a0baa4b RDX: 00007f552a3de900 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 00007f552a3df440 R08: 00007f552a6074c0 R09: 0000000000000110 R10: 0000000000000030 R11: 0000000000000206 R12: 0000000000000000 R13: 00007fff5f18bc5c R14: 000055f01c0a6260 R15: 000055f01c09e290