syzbot

INFO: task syz-executor:6010 blocked for more than 143 seconds.
      Tainted: G        W           6.16.0-syzkaller-01056-gae388edd4a8f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:21416 pid:6010  tgid:6010  ppid:1      task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5397 [inline]
 __schedule+0x165b/0x4c50 kernel/sched/core.c:6786
 __schedule_loop kernel/sched/core.c:6864 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6879
 schedule_timeout+0x9a/0x270 kernel/time/sleep_timeout.c:75
 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+0x2bf/0x5d0 kernel/sched/completion.c:148
 kthread_stop+0x194/0x550 kernel/kthread.c:791
 bch2_copygc_stop+0x4f/0xa0 fs/bcachefs/movinggc.c:438
 __bch2_fs_read_only+0x47/0x5b0 fs/bcachefs/super.c:280
 bch2_fs_read_only+0x42a/0xb00 fs/bcachefs/super.c:366
 __bch2_fs_stop+0x100/0x900 fs/bcachefs/super.c:677
 generic_shutdown_super+0x132/0x2c0 fs/super.c:643
 bch2_kill_sb+0x41/0x50 fs/bcachefs/fs.c:2618
 deactivate_locked_super+0xbc/0x130 fs/super.c:474
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1378
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:114
 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4ed524fcd7
RSP: 002b:00007ffd8b3f7c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f4ed52d0b55 RCX: 00007f4ed524fcd7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd8b3f7d30
RBP: 00007ffd8b3f7d30 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffd8b3f8dc0
R13: 00007f4ed52d0b55 R14: 000000000003296a R15: 00007ffd8b3f8e00
 </TASK>

Showing all locks held in the system:
5 locks held by kworker/u8:1/13:
1 lock held by khungtaskd/39:
 #0: ffffffff8d9aa300 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8d9aa300 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8d9aa300 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6770
2 locks held by getty/5577:
 #0: ffff88823bf920a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e9b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x444/0x1410 drivers/tty/n_tty.c:2222
2 locks held by syz-executor/6010:
 #0: ffff88803a1260d0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff88803a1260d0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff88803a1260d0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:506
 #1: ffff888058f00268 (&c->state_lock){++++}-{4:4}, at: __bch2_fs_stop+0xf8/0x900 fs/bcachefs/super.c:676
2 locks held by bch-copygc/loop/6252:
 #0: ffff888058f04678 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:161 [inline]
 #0: ffff888058f04678 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:253 [inline]
 #0: ffff888058f04678 (&c->btree_trans_barrier){.+.+}-{0:0}, at: bch2_trans_srcu_lock+0xaf/0x220 fs/bcachefs/btree_iter.c:3299
 #1: ffff888058f37360 (&c->gc_lock){.+.+}-{4:4}, at: bch2_btree_update_start+0x542/0x1de0 fs/bcachefs/btree_update_interior.c:1211

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 39 Comm: khungtaskd Tainted: G        W           6.16.0-syzkaller-01056-gae388edd4a8f #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:307 [inline]
 watchdog+0xe9e/0xee0 kernel/hung_task.c:470
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 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: 13 Comm: kworker/u8:1 Tainted: G        W           6.16.0-syzkaller-01056-gae388edd4a8f #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: bat_events batadv_dat_purge
RIP: 0010:match_held_lock+0x0/0xc0 kernel/locking/lockdep.c:5308
Code: 41 5e 41 5f e9 d1 a6 03 00 cc e8 fb f8 ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <41> 56 53 bb 01 00 00 00 48 39 77 10 74 6a 81 7f 20 00 00 20 00 72
RSP: 0018:ffffc90000127570 EFLAGS: 00000083
RAX: 0000000000000005 RBX: ffff88801c290bb8 RCX: 496b7ddff956c700
RDX: 0000000000000001 RSI: ffff8880b8923d50 RDI: ffff88801c290bb8
RBP: 00000000ffffffff R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000024ee4 R12: 0000000000000046
R13: ffff88801c290000 R14: ffff8880b8923d50 R15: 0000000000000004
FS:  0000000000000000(0000) GS:ffff8881269fa000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f93a4fc0000 CR3: 00000000330d8000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __lock_is_held kernel/locking/lockdep.c:5604 [inline]
 lock_is_held_type+0xa8/0x190 kernel/locking/lockdep.c:5943
 lock_is_held include/linux/lockdep.h:249 [inline]
 rtlock_slowlock_locked+0xb7/0x42c0 kernel/locking/rtmutex.c:1836
 rtlock_slowlock kernel/locking/rtmutex.c:1895 [inline]
 rtlock_lock kernel/locking/spinlock_rt.c:43 [inline]
 __rt_spin_lock kernel/locking/spinlock_rt.c:49 [inline]
 rt_spin_lock+0x152/0x2c0 kernel/locking/spinlock_rt.c:57
 spin_lock include/linux/spinlock_rt.h:44 [inline]
 __local_bh_disable_ip+0x264/0x400 kernel/softirq.c:168
 local_bh_disable include/linux/bottom_half.h:20 [inline]
 spin_lock_bh include/linux/spinlock_rt.h:87 [inline]
 __batadv_dat_purge+0x124/0x400 net/batman-adv/distributed-arp-table.c:173
 batadv_dat_purge+0x20/0x70 net/batman-adv/distributed-arp-table.c:204
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>