syzbot


INFO: task kworker/NUM:0H:NUM blocked in I/O wait for more than NUM seconds.

Status: moderation: reported on 2026/03/18 00:09
Subsystems: gfs2
[Documentation on labels]
Reported-by: syzbot+6804fee274579845d82a@syzkaller.appspotmail.com
First crash: 6d23h, last: 2d12h

Sample crash report:
INFO: task kworker/1:0H:25 blocked in I/O wait for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:0H    state:D stack:26128 pid:25    tgid:25    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: gfs2-glock/syz:syz glock_work_func
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5352 [inline]
 __schedule+0x1665/0x5590 kernel/sched/core.c:6964
 __schedule_loop kernel/sched/core.c:7047 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7062
 io_schedule+0x7f/0xd0 kernel/sched/core.c:7889
 bit_wait_io+0x11/0xd0 kernel/sched/wait_bit.c:250
 __wait_on_bit_lock+0xec/0x4e0 kernel/sched/wait_bit.c:93
 out_of_line_wait_on_bit_lock+0x13b/0x190 kernel/sched/wait_bit.c:120
 wait_on_bit_lock_io include/linux/wait_bit.h:221 [inline]
 __lock_buffer fs/buffer.c:72 [inline]
 lock_buffer include/linux/buffer_head.h:432 [inline]
 discard_buffer fs/buffer.c:1603 [inline]
 block_invalidate_folio+0x370/0x730 fs/buffer.c:1660
 folio_invalidate mm/truncate.c:140 [inline]
 truncate_cleanup_folio+0xcb/0x190 mm/truncate.c:160
 truncate_inode_pages_range+0x2ce/0xe30 mm/truncate.c:404
 inode_go_inval+0x13c/0x360 fs/gfs2/glops.c:366
 do_xmote+0x289/0x760 fs/gfs2/glock.c:699
 glock_work_func+0x2a8/0x580 fs/gfs2/glock.c:1011
 process_one_work+0x9ab/0x1780 kernel/workqueue.c:3289
 process_scheduled_works kernel/workqueue.c:3380 [inline]
 worker_thread+0xba8/0x11e0 kernel/workqueue.c:3466
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task syz-executor:5847 blocked in I/O wait for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:21096 pid:5847  tgid:5847  ppid:1      task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5352 [inline]
 __schedule+0x1665/0x5590 kernel/sched/core.c:6964
 __schedule_loop kernel/sched/core.c:7047 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7062
 io_schedule+0x7f/0xd0 kernel/sched/core.c:7889
 bit_wait_io+0x11/0xd0 kernel/sched/wait_bit.c:250
 __wait_on_bit+0xb9/0x310 kernel/sched/wait_bit.c:52
 out_of_line_wait_on_bit+0x13b/0x190 kernel/sched/wait_bit.c:67
 wait_on_bit_io include/linux/wait_bit.h:105 [inline]
 gfs2_evict_inode+0xa04/0x1130 fs/gfs2/super.c:1462
 evict+0x61e/0xb10 fs/inode.c:846
 free_local_statfs_inodes fs/gfs2/super.c:1501 [inline]
 gfs2_put_super+0x635/0x860 fs/gfs2/super.c:632
 generic_shutdown_super+0x13d/0x2d0 fs/super.c:646
 kill_block_super+0x44/0x90 fs/super.c:1725
 deactivate_locked_super+0xbc/0x130 fs/super.c:476
 cleanup_mnt+0x437/0x4d0 fs/namespace.c:1312
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:269 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f64fbf9d9d7
RSP: 002b:00007ffd93d469f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f64fc032050 RCX: 00007f64fbf9d9d7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd93d46ab0
RBP: 00007ffd93d46ab0 R08: 00007ffd93d47ab0 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd93d47b40
R13: 00007f64fc032050 R14: 00000000000201c6 R15: 00007ffd93d47b80
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/1:0H/25:
 #0: ffff8880567a1540 ((wq_completion)gfs2-glock/syz:syz){+.+.}-{0:0}, at: process_one_work+0x894/0x1780 kernel/workqueue.c:3261
 #1: ffffc900001f7c40 ((work_completion)(&(&gl->gl_work)->work)){+.+.}-{0:0}, at: process_one_work+0x8bb/0x1780 kernel/workqueue.c:3262
1 lock held by khungtaskd/31:
 #0: ffffffff8e75d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8e75d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8e75d6a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5607:
 #0: ffff888037a770a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0 drivers/tty/n_tty.c:2211
1 lock held by syz-executor/5847:
 #0: ffff88801ff140d8 (&type->s_umount_key#90){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88801ff140d8 (&type->s_umount_key#90){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff88801ff140d8 (&type->s_umount_key#90){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:508

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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:162 [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:353 [inline]
 watchdog+0x1002/0x1060 kernel/hung_task.c:561
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5833 Comm: syz-executor Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0033:0x7f1407d2b9d0
Code: 0f 05 bf 7f 00 00 00 b8 e7 00 00 00 0f 05 e9 23 ff ff ff 0f 1f 80 00 00 00 00 48 c7 c0 e8 ff ff ff 64 48 03 04 25 00 00 00 00 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 53 48 83 ec 38
RSP: 002b:00007ffd7471ab28 EFLAGS: 00000207
RAX: 00005555778c1528 RBX: 0000000000000000 RCX: 00007f1407d9d2f3
RDX: 0000000000000000 RSI: 00007ffd7471ab3c RDI: 0000000000000003
RBP: 00007ffd7471afe0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000004
R13: 00007ffd7471ab3c R14: 00007ffd7471abd0 R15: 0000000000000000
FS:  00005555778c1540 GS:  0000000000000000

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/18 11:29 linux-next 8e5a478b6d6a 0199f9a1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task kworker/NUM:0H:NUM blocked in I/O wait for more than NUM seconds.
2026/03/14 00:01 linux-next b84a0ebe421c 351cb5cf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task kworker/NUM:0H:NUM blocked in I/O wait for more than NUM seconds.
* Struck through repros no longer work on HEAD.