============================================
WARNING: possible recursive locking detected
5.9.0-rc2-syzkaller #0 Not tainted
--------------------------------------------
syz-executor.0/29486 is trying to acquire lock:
ffff8880a2607418 (&sighand->siglock){-.-.}-{2:2}, at: __lock_task_sighand+0x106/0x2d0 kernel/signal.c:1390

but task is already holding lock:
ffff8880a2607418 (&sighand->siglock){-.-.}-{2:2}, at: __lock_task_sighand+0x106/0x2d0 kernel/signal.c:1390

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

       CPU0
       ----
  lock(&sighand->siglock);
  lock(&sighand->siglock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

4 locks held by syz-executor.0/29486:
 #0: ffffffff89bd6900 (rcu_read_lock){....}-{1:2}, at: do_send_specific+0x0/0x330 kernel/signal.c:1575
 #1: ffff8880a2607418 (&sighand->siglock){-.-.}-{2:2}, at: __lock_task_sighand+0x106/0x2d0 kernel/signal.c:1390
 #2: ffff8880a2607460 (&sighand->signalfd_wqh){....}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:122
 #3: ffffffff89bd6900 (rcu_read_lock){....}-{1:2}, at: __lock_task_sighand+0x0/0x2d0 kernel/signal.c:1352

stack backtrace:
CPU: 0 PID: 29486 Comm: syz-executor.0 Not tainted 5.9.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 print_deadlock_bug kernel/locking/lockdep.c:2391 [inline]
 check_deadlock kernel/locking/lockdep.c:2432 [inline]
 validate_chain kernel/locking/lockdep.c:3202 [inline]
 __lock_acquire.cold+0x115/0x396 kernel/locking/lockdep.c:4426
 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:5005
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:159
 __lock_task_sighand+0x106/0x2d0 kernel/signal.c:1390
 lock_task_sighand include/linux/sched/signal.h:687 [inline]
 task_work_add+0x1d7/0x290 kernel/task_work.c:51
 io_req_task_work_add fs/io_uring.c:1765 [inline]
 __io_async_wake+0x415/0x980 fs/io_uring.c:4589
 __wake_up_common+0x147/0x650 kernel/sched/wait.c:93
 __wake_up_common_lock+0xd0/0x130 kernel/sched/wait.c:123
 signalfd_notify include/linux/signalfd.h:22 [inline]
 __send_signal+0x75b/0xf90 kernel/signal.c:1163
 do_send_sig_info kernel/signal.c:1290 [inline]
 do_send_specific+0x21c/0x330 kernel/signal.c:3798
 do_tkill+0x186/0x1f0 kernel/signal.c:3824
 __do_sys_tkill kernel/signal.c:3859 [inline]
 __se_sys_tkill kernel/signal.c:3853 [inline]
 __x64_sys_tkill+0x67/0x90 kernel/signal.c:3853
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45d5b9
Code: 5d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ff54ca4fc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000c8
RAX: ffffffffffffffda RBX: 0000000000036300 RCX: 000000000045d5b9
RDX: 0000000000000000 RSI: 000000000000002f RDI: 000000000000085f
RBP: 000000000118cf78 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c
R13: 00007ffeee8ef89f R14: 00007ff54ca509c0 R15: 000000000118cf4c