syzbot

INFO: task syz-executor:4326 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:21552 pid: 4326 ppid:     1 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 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+0x426/0x4d0 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: 0033:0x7f016da66097
RSP: 002b:00007ffd7ee44838 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f016dafa2ca RCX: 00007f016da66097
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd7ee448f0
RBP: 00007ffd7ee448f0 R08: 00007ffd7ee458f0 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd7ee45980
R13: 00007f016dafa2ca R14: 0000000000026a28 R15: 00007ffd7ee459c0
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: 
ffffffff8c31ef20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
4 locks held by kworker/u4:1/144:
 #0: ffff8881427b0138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900015dfd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: 
ffff888026406650
 (sb_internal
#2){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x224/0xda0 fs/xfs/libxfs/xfs_bmap.c:4573
 #3: ffff88805ceb3ce8 (&xfs_nondir_ilock_class
){++++}-{3:3}
, at: xfs_bmapi_convert_delalloc+0x25b/0xda0 fs/xfs/libxfs/xfs_bmap.c:4578
4 locks held by kworker/u4:4/3052:
 #0: 
ffff8881427b0138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000c6efd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: 
ffff88807bda4650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x224/0xda0 fs/xfs/libxfs/xfs_bmap.c:4573
 #3: ffff88805ceb1768 (&xfs_nondir_ilock_class
){++++}-{3:3}
, at: xfs_bmapi_convert_delalloc+0x25b/0xda0 fs/xfs/libxfs/xfs_bmap.c:4578
2 locks held by getty/3948:
 #0: ffff88814d849098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
5 locks held by kworker/1:18/4294:
4 locks held by kworker/u4:5/4298:
 #0: 
ffff8881427b0138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000301fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: 
ffff88801ad98650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x224/0xda0 fs/xfs/libxfs/xfs_bmap.c:4573
 #3: ffff88805ceb3568 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_bmapi_convert_delalloc+0x25b/0xda0 fs/xfs/libxfs/xfs_bmap.c:4578
2 locks held by syz-executor/4326:
 #0: ffff88807bda40e0 (&type->s_umount_key#54){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:365
 #1: ffff888147a387d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff888147a387d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a1/0x950 fs/fs-writeback.c:2785
2 locks held by kworker/0:11/4346:
2 locks held by syz-executor/4394:
 #0: 
ffff88801ad980e0 (&type->s_umount_key#54
){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:365
 #1: ffff888147a3e7d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff888147a3e7d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a1/0x950 fs/fs-writeback.c:2785
2 locks held by syz-executor/4416:
 #0: ffff8880264060e0
 (
&type->s_umount_key#54
){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:365
 #1: ffff888147a447d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff888147a447d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a1/0x950 fs/fs-writeback.c:2785
4 locks held by kworker/u4:6/4425:
 #0: ffff8881427b0138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000338fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff888068dd2650
 (
sb_internal
#2
){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x224/0xda0 fs/xfs/libxfs/xfs_bmap.c:4573
 #3: ffff8880703b1768 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_bmapi_convert_delalloc+0x25b/0xda0 fs/xfs/libxfs/xfs_bmap.c:4578
4 locks held by kworker/u4:7/4437:
 #0: 
ffff8881427b0138
 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000340fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff88805e120650 (sb_internal#2){.+.+}-{0:0}, at: xfs_bmapi_convert_delalloc+0x224/0xda0 fs/xfs/libxfs/xfs_bmap.c:4573
 #3: ffff88805ceb4468 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_bmapi_convert_delalloc+0x25b/0xda0 fs/xfs/libxfs/xfs_bmap.c:4578
2 locks held by syz-executor/4442:
 #0: ffff88805e1200e0 (&type->s_umount_key#54){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:365
 #1: ffff88801ffa27d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff88801ffa27d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a1/0x950 fs/fs-writeback.c:2785
2 locks held by syz-executor/4474:
 #0: ffff888068dd20e0 (&type->s_umount_key#54){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:365
 #1: ffff8880204d87d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff8880204d87d8 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a1/0x950 fs/fs-writeback.c:2785

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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+0xe1b/0xe60 kernel/hung_task.c:369
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4296 Comm: kworker/1:20 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: xfs-buf/loop3 xfs_buf_ioend_work
RIP: 0010:format_decode+0x1/0x1330 lib/vsprintf.c:2519
Code: 44 89 e1 80 e1 07 38 c1 0f 8c 6d ff ff ff 4c 89 e7 e8 53 1a b8 fd e9 60 ff ff ff 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 55 <41> 57 41 56 41 55 41 54 53 48 83 ec 48 49 89 f6 49 89 fc 65 48 8b
RSP: 0018:ffffc90002fff300 EFLAGS: 00000293
RAX: ffffffff8405ef89 RBX: ffff0a0000000500 RCX: ffff888027c29dc0
RDX: 0000000000000000 RSI: ffffc90002fff358 RDI: ffffffff8a2be266
RBP: ffffffff8a2be266 R08: ffffc90002fff5e6 R09: 1ffff920005ffebc
R10: dffffc0000000000 R11: fffff520005ffebd R12: ffffc90082fff5df
R13: ffffc90002fff5e7 R14: 0000000000000001 R15: ffffffff8a2be266
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6ec8482000 CR3: 000000007e066000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 vsnprintf+0xef/0x1c20 lib/vsprintf.c:2763
 sprintf+0xe4/0x140 lib/vsprintf.c:3013
 print_time kernel/printk/printk.c:1274 [inline]
 info_print_prefix+0x168/0x360 kernel/printk/printk.c:1300
 record_print_text kernel/printk/printk.c:1349 [inline]
 console_unlock+0x650/0x10f0 kernel/printk/printk.c:2725
 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_agf_read_verify+0x1d2/0x250 fs/xfs/libxfs/xfs_alloc.c:-1
 xfs_buf_ioend+0x256/0x6a0 fs/xfs/xfs_buf.c:1263
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>