syzbot

INFO: task syz-executor:4372 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D
 stack:22440 pid:4372  ppid:1      flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 wb_wait_for_completion+0x162/0x280 fs/fs-writeback.c:191
 sync_inodes_sb+0x1b8/0x9e0 fs/fs-writeback.c:2740
 sync_filesystem+0x16d/0x220 fs/sync.c:64
 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+0x463/0x4f0 fs/namespace.c:1182
 task_work_run+0x1ca/0x250 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:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7a72f901f7
RSP: 002b:00007fffd86521c8 EFLAGS: 00000246
 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f7a73011d7d RCX: 00007f7a72f901f7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fffd8652280
RBP: 00007fffd8652280 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fffd8653310
R13: 00007f7a73011d7d R14: 0000000000017b22 R15: 00007fffd8653350
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/0:0/7:
 #0: ffff888017472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #1: ffffc900000c7d00 ((work_completion)(&rew->rew_work)
){+.+.}-{0:0}
, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
4 locks held by kworker/u4:0/9:
 #0: ffff888144265938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #1: ffffc900000e7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #2: ffff88801def8650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_one_delalloc fs/xfs/libxfs/xfs_bmap.c:4571 [inline]
 #2: ffff88801def8650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x2fd/0x1480 fs/xfs/libxfs/xfs_bmap.c:4698
 #3: 
ffff88805fef9858
 (
&xfs_nondir_ilock_class
){++++}-{3:3}
, at: xfs_bmapi_convert_one_delalloc fs/xfs/libxfs/xfs_bmap.c:4576 [inline]
, at: xfs_bmapi_convert_delalloc+0x329/0x1480 fs/xfs/libxfs/xfs_bmap.c:4698
1 lock held by rcu_tasks_kthre/12:
 #0: 
ffffffff8cb2b570
 (
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: 
ffffffff8cb2bd90
 (
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: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
4 locks held by kworker/u4:2/29:
 #0: ffff888144265938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #1: ffffc90000a5fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #2: ffff88807b108650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_one_delalloc fs/xfs/libxfs/xfs_bmap.c:4571 [inline]
 #2: ffff88807b108650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x2fd/0x1480 fs/xfs/libxfs/xfs_bmap.c:4698
 #3: ffff88807113af98 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_bmapi_convert_one_delalloc fs/xfs/libxfs/xfs_bmap.c:4576 [inline]
 #3: ffff88807113af98 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_bmapi_convert_delalloc+0x329/0x1480 fs/xfs/libxfs/xfs_bmap.c:4698
4 locks held by kworker/u4:3/46:
 #0: 
ffff888144265938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #1: ffffc90000b77d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #2: 
ffff88807c8a6650
 (
sb_internal
#2
){.+.+}-{0:0}
, at: xfs_bmapi_convert_one_delalloc fs/xfs/libxfs/xfs_bmap.c:4571 [inline]
, at: xfs_bmapi_convert_delalloc+0x2fd/0x1480 fs/xfs/libxfs/xfs_bmap.c:4698
 #3: 
ffff88807113ce98 (
&xfs_nondir_ilock_class
){++++}-{3:3}, at: xfs_bmapi_convert_one_delalloc fs/xfs/libxfs/xfs_bmap.c:4576 [inline]
){++++}-{3:3}, at: xfs_bmapi_convert_delalloc+0x329/0x1480 fs/xfs/libxfs/xfs_bmap.c:4698
4 locks held by kworker/u4:4/56:
 #0: 
ffff888144265938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #1: ffffc90001587d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #2: ffff88805dafc650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_one_delalloc fs/xfs/libxfs/xfs_bmap.c:4571 [inline]
 #2: ffff88805dafc650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x2fd/0x1480 fs/xfs/libxfs/xfs_bmap.c:4698
 #3: ffff88805fefa018 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_bmapi_convert_one_delalloc fs/xfs/libxfs/xfs_bmap.c:4576 [inline]
 #3: ffff88805fefa018 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_bmapi_convert_delalloc+0x329/0x1480 fs/xfs/libxfs/xfs_bmap.c:4698
2 locks held by getty/4029:
 #0: ffff88802f74c098
 (&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+0x41b/0x1380 drivers/tty/n_tty.c:2198
2 locks held by kworker/0:8/4327:
5 locks held by kworker/u4:5/4346:
2 locks held by syz-executor/4372:
 #0: ffff88801def80e0 (&type->s_umount_key#53){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffff888143f0a7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff888143f0a7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x19c/0x9e0 fs/fs-writeback.c:2738
3 locks held by kworker/u4:6/4416:
 #0: ffff888017479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #1: 
ffffc90003307d00
 (
(linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8dd41268 (rtnl_mutex){+.+.}-{3:3}
, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263
2 locks held by syz-executor/4434:
 #0: ffff88805dafc0e0 (&type->s_umount_key
#53
){+.+.}-{3:3}
, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffff888024a587d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff888024a587d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x19c/0x9e0 fs/fs-writeback.c:2738
2 locks held by syz-executor/4467:
 #0: ffff88807b1080e0 (&type->s_umount_key#53){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffff888024a5e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff888024a5e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x19c/0x9e0 fs/fs-writeback.c:2738
2 locks held by syz-executor/4498:
 #0: ffff88807c8a60e0 (&type->s_umount_key#53){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffff888143f9c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff888143f9c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x19c/0x9e0 fs/fs-writeback.c:2738
2 locks held by syz-executor/4536:
 #0: 
ffff88807d1ee0e0
 (
&type->s_umount_key
#53){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffff888143faa7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff888143faa7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x19c/0x9e0 fs/fs-writeback.c:2738
4 locks held by kworker/u4:10/4564:
 #0: ffff888144265938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #1: 
ffffc90003b27d00
 (
(work_completion)(&(&wb->dwork)->work)
){+.+.}-{0:0}
, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #2: ffff88807d1ee650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_one_delalloc fs/xfs/libxfs/xfs_bmap.c:4571 [inline]
 #2: ffff88807d1ee650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x2fd/0x1480 fs/xfs/libxfs/xfs_bmap.c:4698
 #3: 
ffff88807113ed98 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_bmapi_convert_one_delalloc fs/xfs/libxfs/xfs_bmap.c:4576 [inline]
ffff88807113ed98 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_bmapi_convert_delalloc+0x329/0x1480 fs/xfs/libxfs/xfs_bmap.c:4698
2 locks held by syz-executor/4594:
 #0: ffffffff8dd41268 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8dd41268 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x740/0xed0 net/core/rtnetlink.c:6150
 #1: 
ffffffff8cb308b8
 (
rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x455/0x830 kernel/rcu/tree_exp.h:962
1 lock held by dhcpcd/4601:
 #0: ffff88823bc6cc90 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #0: ffff88823bc6cc90 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release net/socket.c:653 [inline]
 #0: ffff88823bc6cc90 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: sock_close+0x90/0x240 net/socket.c:1400
2 locks held by dhcpcd/4602:
 #0: 
ffff8880710e3210
 (
&sb->s_type->i_mutex_key
#10
){+.+.}-{3:3}
, at: inode_lock include/linux/fs.h:758 [inline]
, at: __sock_release net/socket.c:653 [inline]
, at: sock_close+0x90/0x240 net/socket.c:1400
 #1: ffffffff8cb308b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline]
 #1: ffffffff8cb308b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x346/0x830 kernel/rcu/tree_exp.h:962

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

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 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3f4/0x470 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
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 129 Comm: kworker/1:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: xfs-buf/loop0 xfs_buf_ioend_work
RIP: 0010:io_serial_in+0x73/0xb0 drivers/tty/serial/8250/8250_port.c:461
Code: e8 72 8b 09 fd 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 73 b8 59 fd 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 44 89 f9 80 e1 07 38 c1 7c aa 4c
RSP: 0018:ffffc90002e37318 EFLAGS: 00000006
RAX: 1ffffffff2dee005 RBX: 00000000000003f9 RCX: 0000000000000000
RDX: 00000000000003f9 RSI: 0000000000000000 RDI: 0000000000000020
RBP: ffffc90002e37510 R08: 0000000000000004 R09: 0000000000000003
R10: fffff520005c6e44 R11: 1ffff920005c6e44 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff96f704c0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f2a8fb2660 CR3: 000000007e421000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 serial_port_in include/linux/serial_core.h:668 [inline]
 serial8250_console_write+0x247/0x17a0 drivers/tty/serial/8250/8250_port.c:3437
 call_console_driver kernel/printk/printk.c:1977 [inline]
 console_emit_next_record+0x947/0xc90 kernel/printk/printk.c:2777
 console_flush_all kernel/printk/printk.c:-1 [inline]
 console_unlock+0x223/0x630 kernel/printk/printk.c:2906
 vprintk_emit+0x489/0x680 kernel/printk/printk.c:2303
 _printk+0xcc/0x110 kernel/printk/printk.c:2328
 __xfs_printk fs/xfs/xfs_message.c:24 [inline]
 _xfs_alert_tag+0x1c8/0x2d0 fs/xfs/xfs_message.c:74
 xfs_buf_verifier_error+0x14c/0x290 fs/xfs/xfs_error.c:430
 xfs_agfl_read_verify+0x1bf/0x240 fs/xfs/libxfs/xfs_alloc.c:-1
 xfs_buf_ioend+0x27a/0x780 fs/xfs/xfs_buf.c:1303
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>