INFO: task kworker/u4:9:3464 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u4:9 state:D stack:25000 pid:3464 ppid:2 flags:0x00004000 Workqueue: writeback wb_workfn (flush-7:0) Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x1553/0x45a0 kernel/sched/core.c:6700 schedule+0xbd/0x170 kernel/sched/core.c:6774 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833 __mutex_lock_common kernel/locking/mutex.c:679 [inline] __mutex_lock+0x6a9/0xcc0 kernel/locking/mutex.c:747 jfs_commit_inode+0x1cb/0x520 fs/jfs/inode.c:108 jfs_write_inode+0x145/0x220 fs/jfs/inode.c:138 write_inode fs/fs-writeback.c:1483 [inline] __writeback_single_inode+0x705/0xec0 fs/fs-writeback.c:1700 writeback_sb_inodes+0x7cd/0xf50 fs/fs-writeback.c:1926 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:1997 wb_writeback+0x47e/0xbf0 fs/fs-writeback.c:2107 wb_check_background_flush fs/fs-writeback.c:2177 [inline] wb_do_writeback fs/fs-writeback.c:2265 [inline] wb_workfn+0xb8e/0xe60 fs/fs-writeback.c:2292 process_one_work kernel/workqueue.c:2653 [inline] process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2730 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2811 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 Showing all locks held in the system: 4 locks held by kworker/u4:0/11: #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #1: ffffc90000107d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #1: ffffc90000107d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #2: ffff888023f2c0e0 (&type->s_umount_key#56){++++}-{3:3}, at: super_trylock_shared+0x20/0xf0 fs/super.c:607 #3: ffff88805fee70c8 (&jfs_ip->commit_mutex){+.+.}-{3:3}, at: jfs_commit_inode+0x1cb/0x520 fs/jfs/inode.c:108 4 locks held by kworker/u4:1/12: #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #1: ffffc90000117d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #1: ffffc90000117d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #2: ffff8880297ec0e0 (&type->s_umount_key#56){++++}-{3:3}, at: super_trylock_shared+0x20/0xf0 fs/super.c:607 #3: ffff88805fc4f0c8 (&jfs_ip->commit_mutex){+.+.}-{3:3}, at: jfs_commit_inode+0x1cb/0x520 fs/jfs/inode.c:108 1 lock held by khungtaskd/29: #0: ffffffff8d1320a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #0: ffffffff8d1320a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #0: ffffffff8d1320a0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633 4 locks held by kworker/u4:3/49: #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #1: ffffc90000ba7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #1: ffffc90000ba7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #2: ffff88805c41e0e0 (&type->s_umount_key#56){++++}-{3:3}, at: super_trylock_shared+0x20/0xf0 fs/super.c:607 #3: ffff88805fc8b948 (&jfs_ip->commit_mutex){+.+.}-{3:3}, at: jfs_commit_inode+0x1cb/0x520 fs/jfs/inode.c:108 4 locks held by kworker/u4:4/59: #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #1: ffffc900015a7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #1: ffffc900015a7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #2: ffff88807b3220e0 (&type->s_umount_key#56){++++}-{3:3}, at: super_trylock_shared+0x20/0xf0 fs/super.c:607 #3: ffff88805fee3008 (&jfs_ip->commit_mutex){+.+.}-{3:3}, at: jfs_commit_inode+0x1cb/0x520 fs/jfs/inode.c:108 4 locks held by kworker/u4:5/79: #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #1: ffffc900015b7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #1: ffffc900015b7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #2: ffff88807ab400e0 (&type->s_umount_key#56){++++}-{3:3}, at: super_trylock_shared+0x20/0xf0 fs/super.c:607 #3: ffff88805feeb948 (&jfs_ip->commit_mutex){+.+.}-{3:3}, at: jfs_commit_inode+0x1cb/0x520 fs/jfs/inode.c:108 4 locks held by kworker/u4:6/1096: #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #1: ffffc90004cffd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #1: ffffc90004cffd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #2: ffff88801ffc80e0 (&type->s_umount_key#56){++++}-{3:3}, at: super_trylock_shared+0x20/0xf0 fs/super.c:607 #3: ffff88805ff901c8 (&jfs_ip->commit_mutex){+.+.}-{3:3}, at: jfs_commit_inode+0x1cb/0x520 fs/jfs/inode.c:108 4 locks held by kworker/u4:8/1143: #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #1: ffffc90004a0fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #1: ffffc90004a0fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #2: ffff88802ef380e0 (&type->s_umount_key#56){++++}-{3:3}, at: super_trylock_shared+0x20/0xf0 fs/super.c:607 #3: ffff8880745c81c8 (&jfs_ip->commit_mutex){+.+.}-{3:3}, at: jfs_commit_inode+0x1cb/0x520 fs/jfs/inode.c:108 4 locks held by kworker/u4:9/3464: #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #0: ffff888145a70138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #1: ffffc9000d247d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #1: ffffc9000d247d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #2: ffff88807cbd80e0 (&type->s_umount_key#56){++++}-{3:3}, at: super_trylock_shared+0x20/0xf0 fs/super.c:607 #3: ffff88805fc4b008 (&jfs_ip->commit_mutex){+.+.}-{3:3}, at: jfs_commit_inode+0x1cb/0x520 fs/jfs/inode.c:108 2 locks held by getty/5524: #0: ffff88802d15a0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc900015d02f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x433/0x1390 drivers/tty/n_tty.c:2217 2 locks held by kworker/1:4/5788: #0: ffff888017c72538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #0: ffff888017c72538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #1: ffffc90004707d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #1: ffffc90004707d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 4 locks held by syz.0.17/5912: 4 locks held by syz.1.18/5931: 4 locks held by syz.2.19/5955: 4 locks held by syz.3.20/5971: 4 locks held by syz.4.21/5994: 4 locks held by syz.5.22/6024: 4 locks held by syz.6.23/6048: 4 locks held by syz.7.24/6072: 2 locks held by dhcpcd/6073: #0: ffff888078597420 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline] #0: ffff888078597420 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: __sock_release net/socket.c:658 [inline] #0: ffff888078597420 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: sock_close+0x9b/0x230 net/socket.c:1420 #1: ffffffff8d137a78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:292 [inline] #1: ffffffff8d137a78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x306/0x880 kernel/rcu/tree_exp.h:1004 2 locks held by dhcpcd/6074: #0: ffff8880508f4130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1780 [inline] #0: ffff8880508f4130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3258 #1: ffffffff8d137a78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:324 [inline] #1: ffffffff8d137a78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3da/0x880 kernel/rcu/tree_exp.h:1004 1 lock held by dhcpcd/6075: #0: ffff888052cde130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1780 [inline] #0: ffff888052cde130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3258 1 lock held by dhcpcd/6076: #0: ffff88805f62a130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1780 [inline] #0: ffff88805f62a130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3258 1 lock held by dhcpcd/6077: #0: ffff888057f06130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1780 [inline] #0: ffff888057f06130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3258 1 lock held by dhcpcd/6078: #0: ffff888024e86130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1780 [inline] #0: ffff888024e86130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3258 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 29 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call Trace: dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106 nmi_cpu_backtrace+0x3a6/0x3e0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline] watchdog+0xf3d/0xf80 kernel/hung_task.c:379 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 6048 Comm: syz.6.23 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 RIP: 0010:__sanitizer_cov_trace_pc+0x5c/0x60 kernel/kcov.c:234 Code: f8 15 00 00 83 fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48 8d 7e 01 8b 89 fc 15 00 00 48 39 cf 73 08 48 89 3a 48 89 44 f2 08 0f 1f 00 f3 0f 1e fa 48 8b 04 24 65 48 8b 15 30 95 7c 7e 65 8b RSP: 0018:ffffc90003a4f6e0 EFLAGS: 00000293 RAX: ffffffff8304e7c1 RBX: 0000000000000004 RCX: ffff888028778000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000000000ff RBP: ffff888022b86000 R08: 0000000200000000 R09: 0000000000000000 R10: 0030000000000000 R11: 000007ff00000020 R12: dffffc0000000000 R13: 1ffff11004570c00 R14: 0000000000000000 R15: 1ffff11004570c02 FS: 000055558c388500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055bdd40ac660 CR3: 000000007316a000 CR4: 00000000003506e0 Call Trace: dtSplitRoot+0x7a1/0x16b0 fs/jfs/jfs_dtree.c:1981 dtSplitUp fs/jfs/jfs_dtree.c:993 [inline] dtInsert+0xed5/0x5de0 fs/jfs/jfs_dtree.c:871 jfs_symlink+0x8b5/0xfa0 fs/jfs/namei.c:1019 vfs_symlink+0x138/0x2b0 fs/namei.c:4481 do_symlinkat+0x1ba/0x400 fs/namei.c:4507 __do_sys_symlink fs/namei.c:4528 [inline] __se_sys_symlink fs/namei.c:4526 [inline] __x64_sys_symlink+0x7e/0x90 fs/namei.c:4526 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fb43759c819 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fffcbbc05e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000058 RAX: ffffffffffffffda RBX: 00007fb437815fa0 RCX: 00007fb43759c819 RDX: 0000000000000000 RSI: 0000200000000340 RDI: 0000200000000000 RBP: 00007fb437632c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb437815fac R14: 00007fb437815fa0 R15: 00007fb437815fa0