INFO: task syz.2.1481:12251 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.2.1481 state:D stack:26552 pid:12251 tgid:12245 ppid:5845 task_flags:0x400140 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1190/0x5de0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:7058 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115 __mutex_lock_common kernel/locking/mutex.c:676 [inline] __mutex_lock+0x81b/0x1060 kernel/locking/mutex.c:760 sync_bdevs+0xfd/0x360 block/bdev.c:1288 ksys_sync+0xb2/0x150 fs/sync.c:105 __do_sys_sync+0xe/0x20 fs/sync.c:113 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7faef6b8eba9 RSP: 002b:00007faef7a9e038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2 RAX: ffffffffffffffda RBX: 00007faef6dd6270 RCX: 00007faef6b8eba9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007faef6dd6270 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007faef6dd6308 R14: 00007faef6dd6270 R15: 00007ffced054918 Showing all locks held in the system: 1 lock held by khungtaskd/31: #0: ffffffff8e5c1260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e5c1260 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #0: ffffffff8e5c1260 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775 1 lock held by udevd/8789: #0: ffff888026732358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:945 2 locks held by getty/9154: #0: ffff888031ee30a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc90003f432f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222 1 lock held by syz.2.1481/12251: #0: ffff888026732358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0xfd/0x360 block/bdev.c:1288 6 locks held by syz.1.1617/12820: #0: ffff88807e8f3438 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2a2/0x370 fs/file.c:1232 #1: ffff888036364428 (sb_writers#8){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:738 #2: ffff88804f540488 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x28f/0x510 fs/kernfs/file.c:325 #3: ffff88801eaf8878 (kn->active#63){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x2b2/0x510 fs/kernfs/file.c:326 #4: ffffffff8e4849c8 (system_transition_mutex){+.+.}-{4:4}, at: software_resume+0x65/0x4e0 kernel/power/hibernate.c:1038 #5: ffff888026732358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xa2/0xe40 block/bdev.c:945 2 locks held by syz.5.1634/12892: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 #1: ffffffff8e4849c8 (system_transition_mutex){+.+.}-{4:4}, at: lock_system_sleep+0x87/0xa0 kernel/power/main.c:57 1 lock held by syz.4.1637/12901: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 1 lock held by syz.0.1639/12909: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 1 lock held by syz.3.1647/12945: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 1 lock held by syz-executor/12947: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 1 lock held by syz-executor/12949: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 1 lock held by syz-executor/12952: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 1 lock held by syz-executor/12953: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 1 lock held by syz-executor/12955: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 1 lock held by syz-executor/12960: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 1 lock held by syz-executor/12962: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 1 lock held by syz-executor/12965: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 1 lock held by syz-executor/12966: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 1 lock held by syz-executor/12968: #0: ffffffff8f3043a8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x63/0x420 drivers/char/misc.c:125 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline] watchdog+0xf0e/0x1260 kernel/hung_task.c:491 kthread+0x3c2/0x780 kernel/kthread.c:463 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 6516 Comm: kworker/u8:15 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Workqueue: bat_events batadv_nc_worker RIP: 0010:trace_lock_acquire include/trace/events/lock.h:24 [inline] RIP: 0010:lock_acquire+0x4e/0x350 kernel/locking/lockdep.c:5831 Code: 48 8b 05 bd e6 3e 12 48 89 44 24 30 31 c0 66 90 65 8b 05 d9 e6 3e 12 83 f8 07 0f 87 bc 02 00 00 89 c0 48 0f a3 05 22 a4 13 0f <0f> 82 74 02 00 00 8b 35 da d5 13 0f 85 f6 0f 85 8d 00 00 00 48 8b RSP: 0018:ffffc90003907ab0 EFLAGS: 00000297 RAX: 0000000000000000 RBX: ffffffff8e5c1260 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e5c1260 RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000400 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881246b5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055dd335beb48 CR3: 000000000e380000 CR4: 00000000003526f0 DR0: 0000000000000004 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:841 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline] batadv_nc_worker+0x16a/0x1030 net/batman-adv/network-coding.c:719 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:463 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245