============================================
WARNING: possible recursive locking detected
5.9.0-rc2-syzkaller #0 Not tainted
--------------------------------------------
syz-executor.2/5209 is trying to acquire lock:
ffff8880483b61d8 (&sighand->siglock){-...}-{2:2}, at: __lock_task_sighand+0x106/0x2d0 kernel/signal.c:1390

but task is already holding lock:
ffff8880483b61d8 (&sighand->siglock){-...}-{2:2}, at: force_sig_info_to_task+0x6c/0x3a0 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.2/5209:
 #0: ffff8880483b61d8 (&sighand->siglock){-...}-{2:2}, at: force_sig_info_to_task+0x6c/0x3a0 kernel/signal.c:1316
 #1: ffff8880483b6220 (&sighand->signalfd_wqh){....}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:122
 #2: ffffffff89bd6900 (rcu_read_lock){....}-{1:2}, at: __lock_task_sighand+0x0/0x2d0 kernel/signal.c:1352

stack backtrace:
CPU: 1 PID: 5209 Comm: syz-executor.2 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
 force_sig_info_to_task+0x2a0/0x3a0 kernel/signal.c:1333
 force_sig_info kernel/signal.c:1341 [inline]
 force_sig+0xa5/0xe0 kernel/signal.c:1629
 __exc_general_protection arch/x86/kernel/traps.c:553 [inline]
 exc_general_protection+0x1ff/0x2d0 arch/x86/kernel/traps.c:524
 asm_exc_general_protection+0x1e/0x30 arch/x86/include/asm/idtentry.h:532
RIP: 0033:0x4003a0
Code: 68 00 00 00 00 e9 00 00 00 00 ff 25 d2 3c 34 00 68 00 00 00 00 e9 00 00 00 00 ff 25 ca 3c 34 00 68 00 00 00 00 e9 00 00 00 00 <ff> 25 c2 3c 34 00 68 00 00 00 00 e9 00 00 00 00 53 48 83 ec 10 64
RSP: 002b:00007fcc52a88828 EFLAGS: 00010207
RAX: 00007fcc52a88850 RBX: 6666666666666667 RCX: 0000000000457cc0
RDX: 0000000000000000 RSI: 0000000000000023 RDI: 00007fcc52a88850
RBP: 000000000118cf80 R08: 000000000000000f R09: 0000000000000000
R10: 0000000000000000 R11: 000000000051a1a0 R12: 000000000118cf4c
R13: 000000000169fb6f R14: 00007fcc52a899c0 R15: 000000000118cf4c