syzbot

INFO: task syz-executor:4284 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:21720 pid: 4284 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
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 gfs2_gl_hash_clear+0x1ab/0x2f0 fs/gfs2/glock.c:2183
 gfs2_put_super+0x769/0x7d0 fs/gfs2/super.c:628
 generic_shutdown_super+0x130/0x300 fs/super.c:475
 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: 0033:0x7f85dd1b8a57
RSP: 002b:00007ffc9d706ea8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f85dd24d048 RCX: 00007f85dd1b8a57
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffc9d706f60
RBP: 00007ffc9d706f60 R08: 00007ffc9d707f60 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc9d707ff0
R13: 00007f85dd24d048 R14: 0000000000015356 R15: 00007ffc9d708030
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c31eb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3950:
 #0: ffff88814ca12098 (&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+0x5df/0x1a70 drivers/tty/n_tty.c:2158
1 lock held by syz-executor/4284:
 #0: ffff88807da7c0e0 (&type->s_umount_key#54){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:365
1 lock held by syz.1.212/4536:
 #0: ffff8880206f6468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xaa/0xb90 drivers/block/loop.c:1366

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

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 04/18/2026
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: 4320 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:__hlist_del include/linux/list.h:854 [inline]
RIP: 0010:hlist_del include/linux/list.h:870 [inline]
RIP: 0010:__alloc_object lib/debugobjects.c:217 [inline]
RIP: 0010:alloc_object+0x308/0x640 lib/debugobjects.c:253
Code: ee ce 75 12 4d 85 ff 0f 84 82 01 00 00 89 54 24 1c 4d 89 fe 49 c1 ee 03 41 80 3c 2e 00 74 08 4c 89 ff e8 cb ca d5 fd 49 8b 1f <4d> 8d 67 08 4d 89 e5 49 c1 ed 03 41 80 7c 2d 00 00 74 08 4c 89 e7
RSP: 0018:ffffc9000304fc58 EFLAGS: 00000046
RAX: ffff8880b9037018 RBX: ffff8880714b5620 RCX: dffffc0000000000
RDX: 0000000000000005 RSI: 0000000000000004 RDI: ffffc9000304fbe0
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000609f7c R12: ffff88807d4021f8
R13: 1ffff1100fa80471 R14: 1ffff1100480d231 R15: ffff888024069188
FS:  00007f8e592da880(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007efdc1e08a08 CR3: 000000005cb13000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lookup_object_or_alloc lib/debugobjects.c:591 [inline]
 debug_object_activate+0x13b/0x4e0 lib/debugobjects.c:696
 debug_rcu_head_queue kernel/rcu/rcu.h:176 [inline]
 __call_rcu kernel/rcu/tree.c:2995 [inline]
 call_rcu+0xa2/0x950 kernel/rcu/tree.c:3091
 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: 0033:0x7f8e593c8407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffcdbc0e9a0 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f8e592da880 RCX: 00007f8e593c8407
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000008
RBP: 00007f8e592da6e8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000002
R13: 000055ae5919a410 R14: 0000000000000008 R15: 000055ae5919ae00
 </TASK>