============================================
WARNING: possible recursive locking detected
5.8.0-syzkaller #0 Not tainted
--------------------------------------------
syz-executor.2/8375 is trying to acquire lock:
ffff888110e6e518 (&sighand->siglock){....}-{2:2}, at: __lock_task_sighand+0x81/0x180 kernel/signal.c:1390

but task is already holding lock:
ffff888110e6e518 (&sighand->siglock){....}-{2:2}, at: force_sig_info_to_task+0x1d/0xd0 kernel/signal.c:1316

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

3 locks held by syz-executor.2/8375:
 #0: ffff888110e6e518 (&sighand->siglock){....}-{2:2}, at: force_sig_info_to_task+0x1d/0xd0 kernel/signal.c:1316
 #1: ffff888110e6e560 (&sighand->signalfd_wqh){....}-{2:2}, at: __wake_up_common_lock+0x5c/0xb0 kernel/sched/wait.c:122
 #2: ffffffff842e1dc0 (rcu_read_lock){....}-{1:2}, at: __lock_task_sighand+0x0/0x180 kernel/signal.c:1366

stack backtrace:
CPU: 1 PID: 8375 Comm: syz-executor.2 Not tainted 5.8.0-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+0xb3/0xec 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.68+0x152/0x2bb kernel/locking/lockdep.c:4426
 lock_acquire+0xd0/0x3e0 kernel/locking/lockdep.c:5005
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x55/0x70 kernel/locking/spinlock.c:159
 __lock_task_sighand+0x81/0x180 kernel/signal.c:1390
 lock_task_sighand include/linux/sched/signal.h:685 [inline]
 task_work_add+0x6e/0xc0 kernel/task_work.c:45
 io_req_task_work_add.isra.78+0x1b/0x40 fs/io_uring.c:1725
 __io_async_wake+0x9b/0x1e0 fs/io_uring.c:4519
 __wake_up_common+0x7f/0x1a0 kernel/sched/wait.c:93
 __wake_up_common_lock+0x75/0xb0 kernel/sched/wait.c:123
 signalfd_notify include/linux/signalfd.h:22 [inline]
 __send_signal+0x3d7/0x700 kernel/signal.c:1163
 force_sig_info_to_task+0xaf/0xd0 kernel/signal.c:1333
 force_sig_fault_to_task kernel/signal.c:1672 [inline]
 force_sig_fault+0x4e/0x70 kernel/signal.c:1679
 __bad_area_nosemaphore+0x144/0x1f0 arch/x86/mm/fault.c:779
 do_user_addr_fault arch/x86/mm/fault.c:1268 [inline]
 handle_page_fault arch/x86/mm/fault.c:1365 [inline]
 exc_page_fault+0x652/0x780 arch/x86/mm/fault.c:1418
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:549
RIP: 0033:0x402b88
Code: 05 00 48 89 7c 24 f8 48 89 74 24 f0 48 89 54 24 e8 48 89 4c 24 e0 48 8b 74 24 f8 4c 8b 4c 24 f0 48 8b 4c 24 e8 48 8b 54 24 e0 <8b> 86 0c 01 00 00 44 8b 86 08 01 00 00 c1 e0 04 8d b8 7f 01 00 00
RSP: 002b:00007fb57c799c68 EFLAGS: 00010216
RAX: 0000000000402b60 RBX: 000000000118cf40 RCX: 0000000020000200
RDX: 0000000000000000 RSI: ffffffffffffffff RDI: ffffffffffffffff
RBP: 000000000118cf88 R08: 0000000000000000 R09: ffffffffffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c
R13: 000000000169fb6f R14: 00007fb57c79a9c0 R15: 000000000118cf4c