INFO: task syz-executor:4187 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor state:D stack:21808 pid: 4187 ppid: 1 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 wb_wait_for_completion+0x171/0x290 fs/fs-writeback.c:191 sync_inodes_sb+0x1bd/0x950 fs/fs-writeback.c:2781 sync_filesystem+0x16d/0x220 fs/sync.c:64 generic_shutdown_super+0x6b/0x300 fs/super.c:448 kill_block_super+0x7c/0xe0 fs/super.c:1427 deactivate_locked_super+0x93/0xf0 fs/super.c:335 cleanup_mnt+0x42d/0x4e0 fs/namespace.c:1148 task_work_run+0x125/0x1a0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f1e8e292117 RSP: 002b:00007fff80a993b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007f1e8e2fa71f RCX: 00007f1e8e292117 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff80a99470 RBP: 00007fff80a99470 R08: 00007fff80a9a470 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff80a9a500 R13: 00007f1e8e2fa71f R14: 0000000000011b25 R15: 00007fff80a9a540 Showing all locks held in the system: 3 locks held by kworker/u4:0/9: 3 locks held by kworker/1:0/21: 1 lock held by khungtaskd/27: #0: ffffffff8c31eaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 2 locks held by getty/3947: #0: ffff88814cb3c098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252 #1: ffffc900025e62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5df/0x1a70 drivers/tty/n_tty.c:2158 2 locks held by udevd/4179: #0: ffff8880203a8518 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xf9/0x7d0 block/bdev.c:915 #1: ffff888020766468 (&lo->lo_mutex){+.+.}-{3:3}, at: lo_release+0x4d/0x1f0 drivers/block/loop.c:2071 1 lock held by syz-executor/4185: #0: ffffffff8d43c548 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:699 [inline] #0: ffffffff8d43c548 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3440 2 locks held by syz-executor/4187: #0: ffff88807e12e0e0 (&type->s_umount_key#65){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:365 #1: ffff8881473ae7d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline] #1: ffff8881473ae7d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a1/0x950 fs/fs-writeback.c:2779 2 locks held by syz-executor/4196: #0: ffffffff8d43c548 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:699 [inline] #0: ffffffff8d43c548 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3440 #1: ffffffff8c323528 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline] #1: ffffffff8c323528 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2d1/0x750 kernel/rcu/tree_exp.h:845 2 locks held by kworker/1:4/4255: #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc9000336fd00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 4 locks held by kworker/u4:8/4351: #0: ffff8880185d8138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc90003e6fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 #2: ffff88807e12e650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x224/0xdb0 fs/xfs/libxfs/xfs_bmap.c:4573 #3: ffff88805ff2bce8 (&xfs_nondir_ilock_class){++++}-{3:3} , at: xfs_bmapi_convert_delalloc+0x25b/0xdb0 fs/xfs/libxfs/xfs_bmap.c:4578 2 locks held by kworker/u4:10/4569: 2 locks held by kworker/1:15/4985: #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc9000130fd00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 2 locks held by kworker/1:19/5413: #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0} , at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc9000405fd00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 2 locks held by kworker/1:20/5414: #0: ffff888016c72138 ( (wq_completion)rcu_gp ){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1 #1: ffffc9000459fd00 ( (work_completion)(&rew.rew_work) ){+.+.}-{0:0} , at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285 3 locks held by syz.4.372/5798: #0: ffff8880748b8ff0 ( &hdev->req_lock ){+.+.}-{3:3} , at: hci_dev_do_close+0x5f/0x1030 net/bluetooth/hci_core.c:1737 #1: ffff8880748b8078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_do_close+0x3f4/0x1030 net/bluetooth/hci_core.c:1782 #2: ffffffff8d582668 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1517 [inline] (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa4/0x220 net/bluetooth/hci_conn.c:1622 1 lock held by syz.3.375/5809: #0: ffffffff8c323528 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline] (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a5/0x750 kernel/rcu/tree_exp.h:845 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline] watchdog+0xe0f/0xe50 kernel/hung_task.c:369 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 4571 Comm: kworker/u4:12 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: bat_events batadv_nc_worker RIP: 0010:rcu_lock_release+0x0/0x20 include/linux/rcupdate.h:317 Code: 96 23 e8 f7 48 c7 c7 a0 ea 31 8c 31 f6 31 d2 b9 02 00 00 00 45 31 c0 45 31 c9 68 05 fc 90 89 e8 f6 05 cc f7 48 83 c4 08 c3 90 6b 23 e8 f7 e8 66 23 e8 f7 48 c7 c7 a0 ea 31 8c 48 c7 c6 35 fc RSP: 0018:ffffc900048b7bd8 EFLAGS: 00000287 RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffff88802ca20000 RDX: 0000000000000000 RSI: ffffffff8a79f760 RDI: ffff88802ca20000 RBP: ffff888019dd7fc0 R08: dffffc0000000000 R09: 1ffffffff203a218 R10: dffffc0000000000 R11: fffffbfff203a219 R12: 000000000000035b R13: fffffffffffffe38 R14: ffff88807d744c80 R15: ffff888019dd7fd0 FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fddb2f7f000 CR3: 0000000075c35000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_read_unlock include/linux/rcupdate.h:773 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:416 [inline] batadv_nc_worker+0x25b/0x5c0 net/batman-adv/network-coding.c:723 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287