INFO: task syz-executor:4275 blocked for more than 144 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor state:D stack:21136 pid:4275 ppid:1 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5245 [inline] __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562 schedule+0xb9/0x180 kernel/sched/core.c:6638 wb_wait_for_completion+0x16f/0x290 fs/fs-writeback.c:191 __writeback_inodes_sb_nr+0x226/0x280 fs/fs-writeback.c:2670 sync_filesystem+0x9f/0x220 fs/sync.c:54 generic_shutdown_super+0x6b/0x340 fs/super.c:474 kill_block_super+0x7c/0xe0 fs/super.c:1470 deactivate_locked_super+0x93/0xf0 fs/super.c:332 cleanup_mnt+0x42c/0x4b0 fs/namespace.c:1191 task_work_run+0x1d0/0x260 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f5abff9d9d7 RSP: 002b:00007ffc1bafaf88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007f5ac0032050 RCX: 00007f5abff9d9d7 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffc1bafb040 RBP: 00007ffc1bafb040 R08: 00007ffc1bafc040 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc1bafc0d0 R13: 00007f5ac0032050 R14: 000000000001f383 R15: 00007ffc1bafc110 Showing all locks held in the system: 1 lock held by rcu_tasks_kthre/12: #0: ffffffff8cb2dfb0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517 1 lock held by rcu_tasks_trace/13: #0: ffffffff8cb2e7d0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517 1 lock held by khungtaskd/28: #0: ffffffff8cb2d620 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #0: ffffffff8cb2d620 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #0: ffffffff8cb2d620 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513 2 locks held by kworker/1:2/125: #0: ffff888017472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267 #1: ffffc90002d97d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267 2 locks held by getty/4026: #0: ffff88802f746098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x429/0x1390 drivers/tty/n_tty.c:2198 1 lock held by syz-executor/4275: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362 3 locks held by kworker/1:5/4312: #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267 #1: ffffc90004127d00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267 #2: ffffffff8cb332f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline] #2: ffffffff8cb332f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2ec/0x890 kernel/rcu/tree_exp.h:962 2 locks held by kworker/u4:19/5114: 3 locks held by kworker/u4:21/5428: #0: ffff8880b8e3ab18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:538 #1: ffff8880b8e27888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x398/0x6d0 kernel/sched/psi.c:999 #2: ffff8880b8e28458 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:999 1 lock held by syz.1.336/5595: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755 1 lock held by syz.1.336/5598: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755 1 lock held by syz.1.336/5603: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755 1 lock held by syz.1.336/5604: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755 1 lock held by syz.1.336/5606: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755 1 lock held by syz.1.336/5608: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755 1 lock held by syz.4.352/5646: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755 1 lock held by syz.4.352/5648: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755 1 lock held by syz.4.352/5650: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755 1 lock held by syz.4.352/5651: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755 1 lock held by syz.4.352/5652: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755 1 lock held by syz.4.352/5655: #0: ffff888078a260e0 (&type->s_umount_key#31){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755 1 lock held by syz.2.607/6715: #0: ffffffff8cb331c0 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x48/0x600 kernel/rcu/tree.c:4023 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 28 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline] watchdog+0xeee/0xf30 kernel/hung_task.c:377 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 5428 Comm: kworker/u4:21 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Workqueue: bat_events batadv_nc_worker RIP: 0010:check_preemption_disabled+0x18/0x110 lib/smp_processor_id.c:14 Code: cc cc 48 c7 c7 00 0f df 8a 48 c7 c6 40 0f df 8a eb 00 55 41 57 41 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 <65> 8b 05 51 ff d4 75 65 8b 0d f2 54 d5 75 f7 c1 ff ff ff 7f 74 1f RSP: 0018:ffffc9000ae17b88 EFLAGS: 00000286 RAX: 9140bb8c5d32a200 RBX: 0000000000000001 RCX: 0000000000000000 RDX: ffff88807d073b80 RSI: ffffffff8adf0f40 RDI: ffffffff8adf0f00 RBP: fffffffffffffe38 R08: dffffc0000000000 R09: 1ffffffff215ec48 R10: dffffc0000000000 R11: fffffbfff215ec49 R12: dffffc0000000000 R13: ffffffff89f630ce R14: ffff88807e044c80 R15: 00000000000001bc FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa984fe92f8 CR3: 000000005ba8f000 CR4: 00000000003526e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_dynticks_curr_cpu_in_eqs include/linux/context_tracking.h:122 [inline] rcu_is_watching+0x11/0xa0 kernel/rcu/tree.c:721 rcu_read_unlock include/linux/rcupdate.h:820 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline] batadv_nc_worker+0x204/0x600 net/batman-adv/network-coding.c:719 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295