syzbot

INFO: task syz-executor:5908 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:21736 pid:5908  ppid:1      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
 bit_wait+0x11/0xd0 kernel/sched/wait_bit.c:199
 __wait_on_bit+0xac/0x2d0 kernel/sched/wait_bit.c:49
 out_of_line_wait_on_bit+0x123/0x170 kernel/sched/wait_bit.c:64
 wait_on_bit include/linux/wait_bit.h:76 [inline]
 gfs2_glock_wait+0xbd/0x2a0 fs/gfs2/glock.c:1380
 gfs2_glock_nq_init fs/gfs2/glock.h:252 [inline]
 __gfs2_lookup+0x118/0x270 fs/gfs2/inode.c:905
 __lookup_slow+0x281/0x3b0 fs/namei.c:1702
 lookup_slow+0x53/0x70 fs/namei.c:1719
 walk_component+0x2be/0x3f0 fs/namei.c:2010
 lookup_last fs/namei.c:2467 [inline]
 path_lookupat+0x169/0x440 fs/namei.c:2491
 filename_lookup+0x1f4/0x510 fs/namei.c:2520
 user_path_at_empty+0x42/0x60 fs/namei.c:2917
 user_path_at include/linux/namei.h:57 [inline]
 ksys_umount fs/namespace.c:1921 [inline]
 __do_sys_umount fs/namespace.c:1929 [inline]
 __se_sys_umount fs/namespace.c:1927 [inline]
 __x64_sys_umount+0xf5/0x170 fs/namespace.c:1927
 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: 0033:0x7fbbda590a77
RSP: 002b:00007fff584c5868 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: ffffffffffffffda RBX: 00007fbbda613d7d RCX: 00007fbbda590a77
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff584c5920
RBP: 00007fff584c5920 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fff584c6a10
R13: 00007fbbda613d7d R14: 000055556cfc44a8 R15: 00007fff584c8bd0
 </TASK>

Showing all locks held in the system:
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
2 locks held by getty/5528:
 #0: ffff88814cad30a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000328b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
1 lock held by syz-executor/5908:
 #0: ffff88805d031588 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:814 [inline]
 #0: ffff88805d031588 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1718

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

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: 1118 Comm: kworker/u4:6 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
RIP: 0010:__lock_acquire+0xc/0x7c80 kernel/locking/lockdep.c:4993
Code: 8b 0c 24 80 e1 07 80 c1 03 38 c1 7c 93 48 8b 3c 24 e8 e8 00 76 00 eb 88 66 0f 1f 44 00 00 f3 0f 1e fa 55 48 89 e5 41 57 41 56 <41> 55 41 54 53 48 83 e4 e0 48 81 ec 20 02 00 00 45 89 cd 45 89 c4
RSP: 0018:ffffc900044df858 EFLAGS: 00000006
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8cd2ff20
RBP: ffffc900044df868 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1c94426 R12: 1ffff9200089bf20
R13: ffffffff8cd2ff20 R14: 0000000000000246 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f34c4ffe000 CR3: 000000000cb30000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:753 [inline]
 batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:824 [inline]
 batadv_iv_ogm_schedule+0x417/0xe90 net/batman-adv/bat_iv_ogm.c:867
 batadv_iv_send_outstanding_bat_ogm_packet+0x731/0x840 net/batman-adv/bat_iv_ogm.c:1711
 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>