INFO: task kworker/u8:4:10554 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:4    state:D stack:21112 pid:10554 tgid:10554 ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: writeback wb_workfn (flush-7:2)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0x1472/0x4fe0 kernel/sched/core.c:6867
 __schedule_loop kernel/sched/core.c:6949 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7245
 rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1647
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
 rt_mutex_slowlock+0x2dc/0x710 kernel/locking/rtmutex.c:1800
 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:534 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:552
 jfs_commit_inode+0x1ca/0x530 fs/jfs/inode.c:108
 jfs_write_inode+0x145/0x220 fs/jfs/inode.c:138
 write_inode fs/fs-writeback.c:1582 [inline]
 __writeback_single_inode+0x7e4/0x1230 fs/fs-writeback.c:1802
 writeback_sb_inodes+0x92e/0x1910 fs/fs-writeback.c:2030
 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2107
 wb_writeback+0x459/0xad0 fs/fs-writeback.c:2218
 wb_check_old_data_flush fs/fs-writeback.c:2322 [inline]
 wb_do_writeback fs/fs-writeback.c:2375 [inline]
 wb_workfn+0xaf3/0xf00 fs/fs-writeback.c:2403
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340
 worker_thread+0xda6/0x1360 kernel/workqueue.c:3421
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>

Showing all locks held in the system:
6 locks held by kworker/0:1/10:
1 lock held by khungtaskd/38:
 #0: ffffffff8dbc77c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8dbc77c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8dbc77c0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:14/4170:
 #0: ffff88813fe69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff88813fe69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc9000f067bc0 (connector_reaper_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc9000f067bc0 (connector_reaper_work){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
2 locks held by getty/5556:
 #0: ffff8881437b30a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e832e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
4 locks held by udevd/5807:
1 lock held by udevd/5821:
 #0: ffff8880222b08a8 (&sb->s_type->i_mutex_key#8){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1042 [inline]
 #0: ffff8880222b08a8 (&sb->s_type->i_mutex_key#8){++++}-{4:4}, at: blkdev_read_iter+0x2ff/0x440 block/fops.c:855
6 locks held by kworker/1:4/5888:
 #0: ffff88805d88c938 ((wq_completion)xfs-inodegc/loop1){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff88805d88c938 ((wq_completion)xfs-inodegc/loop1){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc900051a7bc0 ((work_completion)(&(&gc->work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc900051a7bc0 ((work_completion)(&(&gc->work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
 #2: ffff888035754770 (sb_internal#2){.+.+}-{0:0}, at: xfs_trans_alloc+0xd7/0x960 fs/xfs/xfs_trans.c:256
 #3: ffff88803e573408 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_inactive_ifree+0x115/0x420 fs/xfs/xfs_inode.c:1261
 #4: ffff88805d2df648 (&dqp->q_qlock){+.+.}-{4:4}, at: xfs_trans_dqlockedjoin+0x1bf/0x2a0 fs/xfs/xfs_trans_dquot.c:396
 #5: ffff88805d2df1a0 (&xfs_dquot_group_class){+.+.}-{4:4}, at: xfs_trans_dqlockedjoin+0x1bf/0x2a0 fs/xfs/xfs_trans_dquot.c:396
1 lock held by syz-executor/10087:
 #0: ffff88805d2220d0 (&type->s_umount_key#61){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff88805d2220d0 (&type->s_umount_key#61){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff88805d2220d0 (&type->s_umount_key#61){++++}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:506
4 locks held by kworker/u8:4/10554:
 #0: ffff888140abb938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff888140abb938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc9000ced7bc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc9000ced7bc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
 #2: ffff88803a9a20d0 (&type->s_umount_key#69){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563
 #3: ffff88805cb19f28 (&jfs_ip->commit_mutex){+.+.}-{4:4}, at: jfs_commit_inode+0x1ca/0x530 fs/jfs/inode.c:108
4 locks held by syz.2.350/11007:
3 locks held by kworker/u8:11/12159:
 #0: ffff88804d3eb138 ((wq_completion)xfs-cil/loop1){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff88804d3eb138 ((wq_completion)xfs-cil/loop1){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc90016f8fbc0 ((work_completion)(&ctx->push_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc90016f8fbc0 ((work_completion)(&ctx->push_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
 #2: ffff88804d3ec8a0 (&cil->xc_ctx_lock){++++}-{4:4}, at: xlog_cil_push_work+0x4ed/0x2c00 fs/xfs/xfs_log_cil.c:1308
1 lock held by syz-executor/13681:
 #0: ffff8880357540d0 (&type->s_umount_key#53){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff8880357540d0 (&type->s_umount_key#53){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff8880357540d0 (&type->s_umount_key#53){++++}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:506
2 locks held by kworker/u8:13/14817:
 #0: ffff88813fe69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff88813fe69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc900067cfbc0 ((reaper_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc900067cfbc0 ((reaper_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
1 lock held by syz.9.578/15729:
 #0: ffff888035048480 (sb_writers#4){++++}-{0:0}, at: file_start_write include/linux/fs.h:2681 [inline]
 #0: ffff888035048480 (sb_writers#4){++++}-{0:0}, at: vfs_write+0x22d/0xba0 fs/read_write.c:682
2 locks held by syz.6.577/15740:
5 locks held by udevadm/15770:

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xf90/0xfe0 kernel/hung_task.c:515
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 3 Comm: pool_workqueue_ Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
RIP: 0010:remove_class_from_lock_chain kernel/locking/lockdep.c:6197 [inline]
RIP: 0010:remove_class_from_lock_chains kernel/locking/lockdep.c:6236 [inline]
RIP: 0010:zap_class+0xcf/0x340 kernel/locking/lockdep.c:6281
Code: 49 81 fc 00 00 08 00 0f 84 a4 01 00 00 4e 8b 2c e5 c0 33 e9 92 4d 85 ed 0f 94 c0 49 83 c5 f8 0f 94 c1 08 c1 75 d7 45 8b 75 00 <41> f6 c6 fc 0f 84 e1 00 00 00 41 c1 ee 08 4a 8d 1c 75 90 33 2e 92
RSP: 0018:ffffc90000087bc8 EFLAGS: 00000093
RAX: 000000000018d85a RBX: ffffffff925fe444 RCX: 000000000018d852
RDX: ffffffff932b33e8 RSI: ffffffff932b33e8 RDI: ffffffff92dc3270
RBP: ffffffff932d3830 R08: ffffffff81aca218 R09: ffffffff8dbc77c0
R10: dffffc0000000000 R11: fffffbfff1e8fbcf R12: 0000000000005f0c
R13: ffffffff932ef5d0 R14: 0000000000299108 R15: 00000000000011ea
FS:  0000000000000000(0000) GS:ffff8881266c9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1770158000 CR3: 000000005ac3a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __lockdep_free_key_range kernel/locking/lockdep.c:6407 [inline]
 lockdep_unregister_key+0x1c3/0x350 kernel/locking/lockdep.c:6609
 wq_unregister_lockdep kernel/workqueue.c:4852 [inline]
 pwq_release_workfn+0x6d2/0x870 kernel/workqueue.c:5148
 kthread_worker_fn+0x4ee/0xb00 kernel/kthread.c:1005
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>