syzbot


INFO: task hung in xfs_buf_item_unpin

Status: upstream: reported C repro on 2025/12/28 14:39
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+94ea215e3b2f90a29663@syzkaller.appspotmail.com
First crash: 7d15h, last: 7d15h
Bug presence (1)
Date Name Commit Repro Result
2026/01/02 upstream (ToT) 9b0436804460 C [report] INFO: task hung in xfs_buf_item_unpin
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: task hung in xfs_buf_item_unpin 1 2 987d 998d 0/3 auto-obsoleted due to no activity on 2023/08/21 23:02
upstream INFO: task hung in xfs_buf_item_unpin xfs 1 C error done 147 734d 1042d 0/29 auto-obsoleted due to no activity on 2024/03/11 08:02
linux-6.1 INFO: task hung in xfs_buf_item_unpin (2) origin:upstream missing-backport 1 C inconclusive 2 76d 135d 0/3 upstream: reported C repro on 2025/08/22 07:02
upstream INFO: task hung in xfs_buf_item_unpin (2) xfs 1 C done done 111 22h49m 507d 0/29 upstream: reported C repro on 2024/08/16 05:17
linux-6.1 INFO: task hung in xfs_buf_item_unpin 1 10 916d 1028d 0/3 auto-obsoleted due to no activity on 2023/10/11 09:07

Sample crash report:
INFO: task kworker/u4:7:1132 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:7    state:D stack:23728 pid:1132  ppid:2      flags:0x00004000
Workqueue: xfs-cil/loop2 xlog_cil_push_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x9b/0x280 kernel/time/timer.c:2144
 ___down_common kernel/locking/semaphore.c:229 [inline]
 __down_common+0x308/0x640 kernel/locking/semaphore.c:250
 down+0x80/0xd0 kernel/locking/semaphore.c:64
 xfs_buf_lock+0x14d/0x470 fs/xfs/xfs_buf.c:1126
 xfs_buf_item_unpin+0x1bd/0x660 fs/xfs/xfs_buf_item.c:582
 xfs_trans_committed_bulk+0x337/0x7f0 fs/xfs/xfs_trans.c:808
 xlog_cil_committed+0x223/0x5e0 fs/xfs/xfs_log_cil.c:733
 xlog_cil_push_work+0x1e21/0x23d0 fs/xfs/xfs_log_cil.c:1347
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 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
 </TASK>
INFO: task syz.2.290:8990 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.290       state:D stack:27432 pid:8990  ppid:5914   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x9b/0x280 kernel/time/timer.c:2144
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x2bd/0x590 kernel/sched/completion.c:148
 __flush_workqueue+0x63a/0x1380 kernel/workqueue.c:3219
 xlog_cil_push_now fs/xfs/xfs_log_cil.c:1463 [inline]
 xlog_cil_force_seq+0x22b/0x8b0 fs/xfs/xfs_log_cil.c:1665
 xfs_log_force_seq+0x190/0x430 fs/xfs/xfs_log.c:3373
 __xfs_trans_commit+0x94d/0xd90 fs/xfs/xfs_trans.c:1013
 xfs_sync_sb_buf+0xeb/0x180 fs/xfs/libxfs/xfs_sb.c:1164
 xfs_ioc_setlabel fs/xfs/xfs_ioctl.c:1823 [inline]
 xfs_file_ioctl+0x12ff/0x1590 fs/xfs/xfs_ioctl.c:1921
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9d6098f749
RSP: 002b:00007f9d6189a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f9d60be6090 RCX: 00007f9d6098f749
RDX: 00002000000001c0 RSI: 0000000041009432 RDI: 0000000000000004
RBP: 00007f9d60a13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9d60be6128 R14: 00007f9d60be6090 R15: 00007ffcda6637f8
 </TASK>

Showing all locks held in the system:
1 lock held by pool_workqueue_/3:
2 locks held by kworker/u4:1/12:
 #0: ffff888075073d38 ((wq_completion)xfs-cil/loop3){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888075073d38 ((wq_completion)xfs-cil/loop3){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc90000117d00 ((work_completion)(&ctx->push_work)
){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
2 locks held by kworker/1:0/23:
 #0: ffff888017872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc900001d7d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc900001d7d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
2 locks held by kworker/1:1/27:
 #0: ffff88805fb40d38 ((wq_completion)xfs-sync/loop0){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff88805fb40d38 ((wq_completion)xfs-sync/loop0){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc90000a2fd00 ((work_completion)(&(&log->l_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90000a2fd00 ((work_completion)(&(&log->l_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
6 locks held by kworker/u5:0/51:
 #0: ffff88802ec2bd38 ((wq_completion)hci5){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff88802ec2bd38 ((wq_completion)hci5){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc90000bc7d00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90000bc7d00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff88807aae0e70 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x1d4/0x390 net/bluetooth/hci_sync.c:326
 #3: ffff88807aae00b8 (&hdev->lock){+.+.}-{3:3}, at: hci_abort_conn_sync+0x1f7/0xdc0 net/bluetooth/hci_sync.c:5658
 #4: ffffffff8e1225c8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:1996 [inline]
 #4: ffffffff8e1225c8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_failed+0x165/0x300 net/bluetooth/hci_conn.c:1251
 #5: ffff88807b479b38 (&conn->lock#2){+.+.}-{3:3}, at: l2cap_conn_del+0x70/0x660 net/bluetooth/l2cap_core.c:1763
2 locks held by kworker/u4:7/1132:
 #0: ffff888020beb938 ((wq_completion)xfs-cil/loop2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888020beb938 ((wq_completion)xfs-cil/loop2){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc90004c4fd00 ((work_completion)(&ctx->push_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90004c4fd00 ((work_completion)(&ctx->push_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
2 locks held by kworker/u4:8/2913:
 #0: ffff888061640d38 ((wq_completion)xfs-cil/loop5){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888061640d38 ((wq_completion)xfs-cil/loop5){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc9000bf77d00 ((work_completion)(&ctx->push_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc9000bf77d00 ((work_completion)(&ctx->push_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
2 locks held by kworker/u4:9/2920:
 #0: ffff88802c625538 ((wq_completion)xfs-cil/loop0){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff88802c625538 ((wq_completion)xfs-cil/loop0){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc9000bf27d00 ((work_completion)(&ctx->push_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc9000bf27d00 ((work_completion)(&ctx->push_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
2 locks held by getty/5530:
 #0: ffff8880310a20a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000326e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
2 locks held by kworker/1:3/5826:
 #0: ffff88806d859938 ((wq_completion)xfs-sync/loop3){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff88806d859938 ((wq_completion)xfs-sync/loop3){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc90004577d00 ((work_completion)(&(&log->l_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90004577d00 ((work_completion)(&(&log->l_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
2 locks held by kworker/1:4/5903:
 #0: ffff88801e3ca538 ((wq_completion)xfs-sync/loop2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff88801e3ca538 ((wq_completion)xfs-sync/loop2){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc90004627d00 ((work_completion)(&(&log->l_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90004627d00 ((work_completion)(&(&log->l_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
1 lock held by syz.2.290/8990:
 #0: ffff88807c5e2418 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x200 fs/namespace.c:456
1 lock held by syz.0.308/9194:
 #0: ffff88807a99e418 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x200 fs/namespace.c:456
2 locks held by kworker/u4:6/9945:
 #0: ffff8880b8e3c018 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:558
 #1: ffff8880b8e289c0 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:189 [inline]
 #1: ffff8880b8e289c0 (psi_seq){-.-.}-{0:0}, at: __schedule+0x20ee/0x44d0 kernel/sched/core.c:6694
1 lock held by syz.3.492/11247:
 #0: ffff88801af74418 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x200 fs/namespace.c:456
1 lock held by syz.5.542/11833:
 #0: ffff88807d8ec418 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x200 fs/namespace.c:456
2 locks held by syz.6.548/11865:
2 locks held by syz.1.547/11867:

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x39b/0x3d0 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+0xf41/0xf80 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
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 11867 Comm: syz.1.547 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:101 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:127 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:178 [inline]
RIP: 0010:kasan_check_range+0x6a/0x290 mm/kasan/generic.c:187
Code: 03 49 ba 00 00 00 00 00 fc ff df 4f 8d 1c 17 49 ff c8 4d 89 c1 49 c1 e9 03 48 bb 01 00 00 00 00 fc ff df 4d 8d 34 19 4d 89 f4 <4d> 29 dc 49 83 fc 10 7f 29 4d 85 e4 0f 84 41 01 00 00 4c 89 cb 48
RSP: 0018:ffffc9000db376e8 EFLAGS: 00000803
RAX: 0000000000000001 RBX: dffffc0000000001 RCX: ffffffff81677b7b
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e4a2128
RBP: ffffc9000db37830 R08: ffffffff8e4a212f R09: 1ffffffff1c94425
R10: dffffc0000000000 R11: fffffbfff1c94425 R12: fffffbfff1c94426
R13: dffffc0000000000 R14: fffffbfff1c94426 R15: 1ffffffff1c94425
FS:  00007fb560e546c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1d0e7fe000 CR3: 00000000246af000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 cpumask_test_cpu include/linux/cpumask.h:504 [inline]
 cpu_online include/linux/cpumask.h:1082 [inline]
 trace_lock_release include/trace/events/lock.h:69 [inline]
 lock_release+0xab/0x8b0 kernel/locking/lockdep.c:5765
 __lruvec_stat_mod_folio include/linux/vmstat.h:615 [inline]
 shmem_add_to_page_cache+0xc2a/0x1b40 mm/shmem.c:813
 shmem_get_folio_gfp+0xf05/0x2ac0 mm/shmem.c:2071
 shmem_get_folio mm/shmem.c:2164 [inline]
 shmem_write_begin+0xf2/0x420 mm/shmem.c:2706
 generic_perform_write+0x2fb/0x5b0 mm/filemap.c:4031
 shmem_file_write_iter+0xfb/0x120 mm/shmem.c:2883
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x43b/0x940 fs/read_write.c:584
 ksys_write+0x147/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb55ff8e1ff
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007fb560e53df0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000001000000 RCX: 00007fb55ff8e1ff
RDX: 0000000001000000 RSI: 00007fb5571ff000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 00000000000096d2
R10: 0000000000000002 R11: 0000000000000293 R12: 0000000000000003
R13: 00007fb560e53ef0 R14: 00007fb560e53eb0 R15: 00007fb5571ff000
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/28 14:38 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan INFO: task hung in xfs_buf_item_unpin
* Struck through repros no longer work on HEAD.