INFO: task kworker/u4:15:6732 blocked for more than 143 seconds. Not tainted 5.15.180-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u4:15 state:D stack:21752 pid: 6732 ppid: 2 flags:0x00004000 Workqueue: writeback wb_workfn (flush-7:3) Call Trace: context_switch kernel/sched/core.c:5030 [inline] __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376 schedule+0x11b/0x1f0 kernel/sched/core.c:6459 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6518 __mutex_lock_common+0xe34/0x25a0 kernel/locking/mutex.c:669 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 jfs_commit_inode+0x242/0x580 fs/jfs/inode.c:102 jfs_write_inode+0x13f/0x210 fs/jfs/inode.c:132 write_inode fs/fs-writeback.c:1495 [inline] __writeback_single_inode+0x644/0xe30 fs/fs-writeback.c:1705 writeback_sb_inodes+0xbce/0x1a40 fs/fs-writeback.c:1930 __writeback_inodes_wb+0x114/0x400 fs/fs-writeback.c:2001 wb_writeback+0x465/0xc50 fs/fs-writeback.c:2106 wb_check_old_data_flush fs/fs-writeback.c:2206 [inline] wb_do_writeback fs/fs-writeback.c:2259 [inline] wb_workfn+0xc55/0x1130 fs/fs-writeback.c:2288 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457 kthread+0x3f6/0x4f0 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Showing all locks held in the system: 2 locks held by kworker/u4:0/9: 1 lock held by khungtaskd/27: #0: ffffffff8cb1f4e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 2 locks held by getty/3924: #0: ffff88814c7ce098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252 #1: ffffc90002cd62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6af/0x1db0 drivers/tty/n_tty.c:2158 3 locks held by kworker/u5:7/4188: #0: ffff88807a0d6938 ((wq_completion)hci7){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283 #1: ffffc90002edfd20 ((work_completion)(&hdev->power_on)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285 #2: ffff8880794c8ff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_open+0xa4/0x1330 net/bluetooth/hci_core.c:1446 2 locks held by kworker/0:12/4430: #0: ffff8880b8e3a318 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xa8/0x140 kernel/sched/core.c:483 #1: ffff8880b8e27848 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x53d/0x810 kernel/sched/psi.c:891 6 locks held by kworker/1:11/5854: #0: ffff888141b8e538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283 #1: ffffc9000305fd20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285 #2: ffff888147f56220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:760 [inline] #2: ffff888147f56220 (&dev->mutex){....}-{3:3}, at: hub_event+0x208/0x54c0 drivers/usb/core/hub.c:5781 #3: ffff888147f695c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3138 [inline] #3: ffff888147f695c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5363 [inline] #3: ffff888147f695c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline] #3: ffff888147f695c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline] #3: ffff888147f695c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2238/0x54c0 drivers/usb/core/hub.c:5835 #4: ffff888147f16568 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5364 [inline] #4: ffff888147f16568 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5607 [inline] #4: ffff888147f16568 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5753 [inline] #4: ffff888147f16568 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x2260/0x54c0 drivers/usb/core/hub.c:5835 #5: ffffffff8d5aa670 (ehci_cf_port_reset_rwsem){.+.+}-{3:3}, at: hub_port_reset+0x1f4/0x1dd0 drivers/usb/core/hub.c:3000 4 locks held by kworker/u4:15/6732: #0: ffff888019bb8938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283 #1: ffffc9000395fd20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285 #2: ffff8880779de0e0 (&type->s_umount_key#95){++++}-{3:3}, at: trylock_super+0x1b/0xf0 fs/super.c:418 #3: ffff888051983008 (&jfs_ip->commit_mutex){+.+.}-{3:3}, at: jfs_commit_inode+0x242/0x580 fs/jfs/inode.c:102 4 locks held by syz.3.1453/8986: 2 locks held by syz.7.2182/11555: #0: ffff8880779de0e0 (&type->s_umount_key#95){++++}-{3:3}, at: iterate_supers+0xac/0x1e0 fs/super.c:716 #1: ffff88814730e7d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline] #1: ffff88814730e7d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x274/0xab0 fs/fs-writeback.c:2768 2 locks held by syz.1.2375/12331: #0: ffff888019b9f098 (&tty->ldisc_sem){++++}-{0:0}, at: __tty_ldisc_lock drivers/tty/tty_ldisc.c:300 [inline] #0: ffff888019b9f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_lock_pair_timeout drivers/tty/tty_ldisc.c:346 [inline] #0: ffff888019b9f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_lock_pair drivers/tty/tty_ldisc.c:377 [inline] #0: ffff888019b9f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_release+0x58/0x200 drivers/tty/tty_ldisc.c:802 #1: ffff888061ae5098 (&tty->ldisc_sem/1){+.+.}-{0:0}, at: __tty_ldisc_lock_nested drivers/tty/tty_ldisc.c:306 [inline] #1: ffff888061ae5098 (&tty->ldisc_sem/1){+.+.}-{0:0}, at: tty_ldisc_lock_pair_timeout drivers/tty/tty_ldisc.c:348 [inline] #1: ffff888061ae5098 (&tty->ldisc_sem/1){+.+.}-{0:0}, at: tty_ldisc_lock_pair drivers/tty/tty_ldisc.c:377 [inline] #1: ffff888061ae5098 (&tty->ldisc_sem/1){+.+.}-{0:0}, at: tty_ldisc_release+0x7c/0x200 drivers/tty/tty_ldisc.c:802 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.15.180-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x181/0x2a0 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+0xe72/0xeb0 kernel/hung_task.c:369 kthread+0x3f6/0x4f0 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 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline] NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline] NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:722