syzbot

============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
kworker/u4:0/9 is trying to acquire lock:
ffffe8ffffd35150 (&pd_list->lock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffffe8ffffd35150 (&pd_list->lock){+...}-{2:2}, at: padata_find_next kernel/padata.c:264 [inline]
ffffe8ffffd35150 (&pd_list->lock){+...}-{2:2}, at: padata_reorder kernel/padata.c:317 [inline]
ffffe8ffffd35150 (&pd_list->lock){+...}-{2:2}, at: padata_do_serial+0x60a/0xa70 kernel/padata.c:387

but task is already holding lock:
ffffe8ffffc351a0 (&pd_list->lock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffffe8ffffc351a0 (&pd_list->lock){+...}-{2:2}, at: padata_reorder kernel/padata.c:308 [inline]
ffffe8ffffc351a0 (&pd_list->lock){+...}-{2:2}, at: padata_do_serial+0x4a5/0xa70 kernel/padata.c:387

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

       CPU0
       ----
  lock(&pd_list->lock);
  lock(&pd_list->lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by kworker/u4:0/9:
 #0: ffff88814424e938 ((wq_completion)pencrypt_parallel){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc900000e7d00 ((work_completion)(&pw->pw_work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffffe8ffffc351a0 (&pd_list->lock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #2: ffffe8ffffc351a0 (&pd_list->lock){+...}-{2:2}, at: padata_reorder kernel/padata.c:308 [inline]
 #2: ffffe8ffffc351a0 (&pd_list->lock){+...}-{2:2}, at: padata_do_serial+0x4a5/0xa70 kernel/padata.c:387

stack backtrace:
CPU: 1 PID: 9 Comm: kworker/u4:0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: pencrypt_parallel padata_parallel_worker
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 __lock_acquire+0x124e/0x7bd0 kernel/locking/lockdep.c:-1
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 padata_find_next kernel/padata.c:264 [inline]
 padata_reorder kernel/padata.c:317 [inline]
 padata_do_serial+0x60a/0xa70 kernel/padata.c:387
 padata_parallel_worker+0x6b/0x1c0 kernel/padata.c:160
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>