============================================
WARNING: possible recursive locking detected
5.11.0-syzkaller #0 Not tainted
--------------------------------------------
syz-executor331/5891 is trying to acquire lock:
ffff888015ca2c68 (&pipe->mutex/1){+.+.}-{3:3}, at: __pipe_lock fs/pipe.c:87 [inline]
ffff888015ca2c68 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_write+0x113/0x18e0 fs/pipe.c:416

but task is already holding lock:
ffff888015ca1468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:66 [inline]
ffff888015ca1468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:74 [inline]
ffff888015ca1468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_wait_readable+0x2df/0x3a0 fs/pipe.c:1031

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

       CPU0
       ----
  lock(&pipe->mutex/1);
  lock(&pipe->mutex/1);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

1 lock held by syz-executor331/5891:
 #0: ffff888015ca1468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:66 [inline]
 #0: ffff888015ca1468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:74 [inline]
 #0: ffff888015ca1468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_wait_readable+0x2df/0x3a0 fs/pipe.c:1031

stack backtrace:
CPU: 0 PID: 5891 Comm: syz-executor331 Not tainted 5.11.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x9a/0xcc lib/dump_stack.c:120
 print_deadlock_bug kernel/locking/lockdep.c:2761 [inline]
 check_deadlock kernel/locking/lockdep.c:2804 [inline]
 validate_chain kernel/locking/lockdep.c:3595 [inline]
 __lock_acquire.cold+0x117/0x3ab kernel/locking/lockdep.c:4832
 lock_acquire kernel/locking/lockdep.c:5442 [inline]
 lock_acquire+0x1a8/0x720 kernel/locking/lockdep.c:5407
 __mutex_lock_common kernel/locking/mutex.c:956 [inline]
 __mutex_lock+0x134/0x1110 kernel/locking/mutex.c:1103
 __pipe_lock fs/pipe.c:87 [inline]
 pipe_write+0x113/0x18e0 fs/pipe.c:416
 call_write_iter include/linux/fs.h:1901 [inline]
 do_iter_readv_writev+0x333/0x6d0 fs/read_write.c:740
 do_iter_write+0x12a/0x5b0 fs/read_write.c:866
 iter_file_splice_write+0x58d/0xad0 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 do_splice+0x9e0/0x1c50 fs/splice.c:1059
 __do_splice+0xf4/0x1b0 fs/splice.c:1137
 __do_sys_splice fs/splice.c:1343 [inline]
 __se_sys_splice fs/splice.c:1325 [inline]
 __x64_sys_splice+0x14a/0x200 fs/splice.c:1325
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f0e2afbdc99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 81 14 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0e2af70308 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f0e2b046408 RCX: 00007f0e2afbdc99
RDX: 0000000000000006 RSI: 0000