INFO: task syz-executor:4794 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:21968 pid: 4794 ppid:     1 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 wb_wait_for_completion+0x171/0x290 fs/fs-writeback.c:191
 sync_inodes_sb+0x1bd/0x950 fs/fs-writeback.c:2787
 sync_filesystem+0x16d/0x220 fs/sync.c:64
 generic_shutdown_super+0x6b/0x300 fs/super.c:448
 kill_block_super+0x7c/0xe0 fs/super.c:1427
 deactivate_locked_super+0x93/0xf0 fs/super.c:335
 cleanup_mnt+0x42d/0x4e0 fs/namespace.c:1148
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f21b8fa7697
RSP: 002b:00007ffc01dbe928 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f21b9028a12 RCX: 00007f21b8fa7697
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffc01dbe9e0
RBP: 00007ffc01dbe9e0 R08: 00007ffc01dbf9e0 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc01dbfa60
R13: 00007f21b9028a12 R14: 0000000000017d83 R15: 00007ffc01dbfaa0
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/0:0/7:
4 locks held by kworker/u4:0/9:
 #0: ffff8880195f7138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90000ce7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff88805d3b4650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x224/0xdb0 fs/xfs/libxfs/xfs_bmap.c:4573
 #3: ffff88806eac9768 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_bmapi_convert_delalloc+0x25b/0xdb0 fs/xfs/libxfs/xfs_bmap.c:4578
1 lock held by khungtaskd/27:
 #0: ffffffff8c31eaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
4 locks held by kworker/u4:3/396:
 #0: 
ffff8880195f7138
 (
(wq_completion)writeback
){+.+.}-{0:0}
, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: 
ffffc9000314fd00
 (
(work_completion)(&(&wb->dwork)->work)
){+.+.}-{0:0}
, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: 
ffff8880741ce650
 (
sb_internal
#2
){.+.+}-{0:0}
, at: xfs_bmapi_convert_delalloc+0x224/0xdb0 fs/xfs/libxfs/xfs_bmap.c:4573
 #3: 
ffff88806eacade8
 (
&xfs_nondir_ilock_class
){++++}-{3:3}
, at: xfs_bmapi_convert_delalloc+0x25b/0xdb0 fs/xfs/libxfs/xfs_bmap.c:4578
4 locks held by kworker/u4:4/1277:
 #0: 
ffff8880195f7138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90004e57d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: 
ffff888019dde650
 (
sb_internal
#2
){.+.+}-{0:0}
, at: xfs_bmapi_convert_delalloc+0x224/0xdb0 fs/xfs/libxfs/xfs_bmap.c:4573
 #3: 
ffff88805c1e9768
 (
&xfs_nondir_ilock_class
){++++}-{3:3}
, at: xfs_bmapi_convert_delalloc+0x25b/0xdb0 fs/xfs/libxfs/xfs_bmap.c:4578
2 locks held by getty/3950:
 #0: 
ffff88814cd63098
 (
&tty->ldisc_sem
){++++}-{0:0}
, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: 
ffffc900026562e8
 (
&ldata->atomic_read_lock
){+.+.}-{3:3}
, at: n_tty_read+0x5df/0x1a70 drivers/tty/n_tty.c:2158
4 locks held by kworker/u4:5/4273:
 #0: 
ffff8880195f7138
 (
(wq_completion)writeback
){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc9000318fd00
 (
(work_completion)(&(&wb->dwork)->work)
){+.+.}-{0:0}
, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff88805b766650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x224/0xdb0 fs/xfs/libxfs/xfs_bmap.c:4573
 #3: ffff88805c191ee8 (&xfs_nondir_ilock_class){++++}-{3:3}
, at: xfs_bmapi_convert_delalloc+0x25b/0xdb0 fs/xfs/libxfs/xfs_bmap.c:4578
5 locks held by kworker/1:7/4659:
2 locks held by syz-executor/4794:
 #0: 
ffff88805d3b40e0
 (
&type->s_umount_key
#52
){+.+.}-{3:3}
, at: deactivate_super+0xa0/0xd0 fs/super.c:365
 #1: 
ffff8880203c87d8
 (
&bdi->wb_switch_rwsem
){+.+.}-{3:3}
, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
, at: sync_inodes_sb+0x1a1/0x950 fs/fs-writeback.c:2785
2 locks held by syz-executor/5063:
 #0: 
ffff888019dde0e0
 (
&type->s_umount_key
#52
){+.+.}-{3:3}
, at: deactivate_super+0xa0/0xd0 fs/super.c:365
 #1: 
ffff8880203ce7d8
 (
&bdi->wb_switch_rwsem
){+.+.}-{3:3}
, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
, at: sync_inodes_sb+0x1a1/0x950 fs/fs-writeback.c:2785
2 locks held by syz-executor/5093:
 #0: ffff8880741ce0e0 (&type->s_umount_key#52){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:365
 #1: 
ffff8880203d47d8 (
&bdi->wb_switch_rwsem
){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
){+.+.}-{3:3}, at: sync_inodes_sb+0x1a1/0x950 fs/fs-writeback.c:2785
2 locks held by syz-executor/5130:
 #0: ffff88801f3640e0 (&type->s_umount_key#52){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:365
 #1: ffff8881476027d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff8881476027d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a1/0x950 fs/fs-writeback.c:2785
4 locks held by kworker/u4:7/5148:
 #0: ffff8880195f7138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc900036bfd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff88801f364650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x224/0xdb0 fs/xfs/libxfs/xfs_bmap.c:4573
 #3: ffff88806eacd368 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_bmapi_convert_delalloc+0x25b/0xdb0 fs/xfs/libxfs/xfs_bmap.c:4578
2 locks held by syz-executor/5200:
 #0: ffff88805b7660e0 (&type->s_umount_key#52){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:365
 #1: ffff8880204a87d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff8880204a87d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a1/0x950 fs/fs-writeback.c:2785

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4256 Comm: kworker/0:15 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Workqueue: xfs-buf/loop3 xfs_buf_ioend_work
RIP: 0010:io_serial_in+0x73/0xb0 drivers/tty/serial/8250/8250_port.c:461
Code: e8 72 a2 29 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 33 ae 6e 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:ffffc9000308f370 EFLAGS: 00000002
RAX: 1ffffffff2cbff00 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020
RBP: 0000000000000020 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000611e64 R12: dffffc0000000000
R13: ffffffff965ffaa8 R14: ffffffff965ff840 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020384000 CR3: 00000000183b7000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 serial_in drivers/tty/serial/8250/8250.h:116 [inline]
 wait_for_xmitr+0xe9/0x260 drivers/tty/serial/8250/8250_port.c:2069
 serial8250_console_putchar+0x1a/0x50 drivers/tty/serial/8250/8250_port.c:3309
 uart_console_write+0xaa/0x100 drivers/tty/serial/serial_core.c:1981
 serial8250_console_write+0xc46/0x1000 drivers/tty/serial/8250/8250_port.c:3386
 call_console_drivers kernel/printk/printk.c:-1 [inline]
 console_unlock+0xb9a/0x1120 kernel/printk/printk.c:2744
 vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274
 _printk+0xda/0x130 kernel/printk/printk.c:2299
 print_hex_dump+0x1cf/0x2b0 lib/hexdump.c:285
 xfs_hex_dump+0x39/0x50 fs/xfs/xfs_message.c:118
 xfs_buf_verifier_error+0x1ba/0x290 fs/xfs/xfs_error.c:418
 xfs_allocbt_read_verify+0x53/0xd0 fs/xfs/libxfs/xfs_alloc_btree.c:-1
 xfs_buf_ioend+0x25c/0x6e0 fs/xfs/xfs_buf.c:1263
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>