============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
kworker/u8:12/1171 is trying to acquire lock:
ffff8880b873b868 (&pool->cb_lock){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
ffff8880b873b868 (&pool->cb_lock){+...}-{3:3}, at: worker_lock_callback kernel/workqueue.c:3200 [inline]
ffff8880b873b868 (&pool->cb_lock){+...}-{3:3}, at: bh_worker+0x86/0x890 kernel/workqueue.c:3753

but task is already holding lock:
ffff8880b863b868 (&pool->cb_lock){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
ffff8880b863b868 (&pool->cb_lock){+...}-{3:3}, at: worker_lock_callback kernel/workqueue.c:3200 [inline]
ffff8880b863b868 (&pool->cb_lock){+...}-{3:3}, at: bh_worker+0x86/0x890 kernel/workqueue.c:3753

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&pool->cb_lock);
  lock(&pool->cb_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

locks held by kworker/u8:12/1171: 7, last CPU#0:
 #0: ffff888032868938 ((wq_completion)bat_events){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff888032868938 ((wq_completion)bat_events){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff888032868938 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3352 [inline]
 #0: ffff888032868938 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3470
 #1: ffffc90006787c40 ((work_completion)(&(&bat_priv->tt.work)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc90006787c40 ((work_completion)(&(&bat_priv->tt.work)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc90006787c40 ((work_completion)(&(&bat_priv->tt.work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3352 [inline]
 #1: ffffc90006787c40 ((work_completion)(&(&bat_priv->tt.work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3470
 #2: ffffffff8e1c3800 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3d/0x420 kernel/softirq.c:186
 #3: ffff8880b863b868 (&pool->cb_lock){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #3: ffff8880b863b868 (&pool->cb_lock){+...}-{3:3}, at: worker_lock_callback kernel/workqueue.c:3200 [inline]
 #3: ffff8880b863b868 (&pool->cb_lock){+...}-{3:3}, at: bh_worker+0x86/0x890 kernel/workqueue.c:3753
 #4: ffffffff8e1c3800 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #4: ffffffff8e1c3800 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #4: ffffffff8e1c3800 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #4: ffffffff8e1c3800 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e2/0x400 kernel/locking/spinlock_rt.c:57
 #5: ffff88813ff21938 ((wq_completion)events_bh_highpri){+...}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #5: ffff88813ff21938 ((wq_completion)events_bh_highpri){+...}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #5: ffff88813ff21938 ((wq_completion)events_bh_highpri){+...}-{0:0}, at: process_one_work kernel/workqueue.c:3352 [inline]
 #5: ffff88813ff21938 ((wq_completion)events_bh_highpri){+...}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3470
 #6: ffffc900067877a0 ((work_completion)(&dead_work.work)){+...}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #6: ffffc900067877a0 ((work_completion)(&dead_work.work)){+...}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #6: ffffc900067877a0 ((work_completion)(&dead_work.work)){+...}-{0:0}, at: process_one_work kernel/workqueue.c:3352 [inline]
 #6: ffffc900067877a0 ((work_completion)(&dead_work.work)){+...}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3470

stack backtrace:
CPU: 0 UID: 0 PID: 1171 Comm: kworker/u8:12 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: bat_events batadv_tt_purge
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3057
 check_deadlock kernel/locking/lockdep.c:3109 [inline]
 validate_chain kernel/locking/lockdep.c:3911 [inline]
 __lock_acquire+0x24df/0x2ce0 kernel/locking/lockdep.c:5253
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5886
 rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56
 spin_lock include/linux/spinlock_rt.h:45 [inline]
 worker_lock_callback kernel/workqueue.c:3200 [inline]
 bh_worker+0x86/0x890 kernel/workqueue.c:3753
 drain_dead_softirq_workfn+0x95/0x220 kernel/workqueue.c:3828
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3470
 bh_worker+0x44d/0x890 kernel/workqueue.c:3773
 tasklet_hi_action+0xf/0x70 kernel/softirq.c:1003
 handle_softirqs+0x1da/0x6d0 kernel/softirq.c:645
 __do_softirq kernel/softirq.c:679 [inline]
 __local_bh_enable_ip+0x16f/0x2b0 kernel/softirq.c:325
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 spin_unlock_bh include/linux/spinlock_rt.h:122 [inline]
 batadv_tt_local_purge+0x2ed/0x380 net/batman-adv/translation-table.c:1402
 batadv_tt_purge+0x35/0x9f0 net/batman-adv/translation-table.c:3753
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3470
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3551
 kthread+0x38b/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
BUG: workqueue leaked atomic, lock or RCU: kworker/u8:12[1171]
     preempt=0x00000000 lock=5->0 RCU=2->2 workfn=drain_dead_softirq_workfn
INFO: lockdep is turned off.
CPU: 0 UID: 0 PID: 1171 Comm: kworker/u8:12 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: bat_events batadv_tt_purge
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 process_one_work kernel/workqueue.c:3408 [inline]
 process_scheduled_works+0x12c7/0x1630 kernel/workqueue.c:3470
 bh_worker+0x44d/0x890 kernel/workqueue.c:3773
 tasklet_hi_action+0xf/0x70 kernel/softirq.c:1003
 handle_softirqs+0x1da/0x6d0 kernel/softirq.c:645
 __do_softirq kernel/softirq.c:679 [inline]
 __local_bh_enable_ip+0x16f/0x2b0 kernel/softirq.c:325
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 spin_unlock_bh include/linux/spinlock_rt.h:122 [inline]
 batadv_tt_local_purge+0x2ed/0x380 net/batman-adv/translation-table.c:1402
 batadv_tt_purge+0x35/0x9f0 net/batman-adv/translation-table.c:3753
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3470
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3551
 kthread+0x38b/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>