syzbot

============================================
WARNING: possible recursive locking detected
6.7.0-rc7-syzkaller-00016-gf5837722ffec #0 Not tainted
--------------------------------------------
syz-executor178/5062 is trying to acquire lock:
ffff88807b9f6068 (&pipe->mutex/1){+.+.}-{3:3}, at: __pipe_lock fs/pipe.c:103 [inline]
ffff88807b9f6068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_write+0x13a/0x1bc0 fs/pipe.c:453

but task is already holding lock:
ffff88807b9f6468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:82 [inline]
ffff88807b9f6468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:90 [inline]
ffff88807b9f6468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:85 [inline]
ffff88807b9f6468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_wait_readable+0x3c9/0x4a0 fs/pipe.c:1063

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-executor178/5062:
 #0: ffff88807b9f6468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:82 [inline]
 #0: ffff88807b9f6468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:90 [inline]
 #0: ffff88807b9f6468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:85 [inline]
 #0: ffff88807b9f6468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_wait_readable+0x3c9/0x4a0 fs/pipe.c:1063

stack backtrace:
CPU: 1 PID: 5062 Comm: syz-executor178 Not tainted 6.7.0-rc7-syzkaller-00016-gf5837722ffec #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain kernel/locking/lockdep.c:3856 [inline]
 __lock_acquire+0x20f8/0x3b20 kernel/locking/lockdep.c:5137
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x175/0x9d0 kernel/locking/mutex.c:747
 __pipe_lock fs/pipe.c:103 [inline]
 pipe_write+0x13a/0x1bc0 fs/pipe.c:453
 call_write_iter include/linux/fs.h:2020 [inline]
 do_iter_readv_writev+0x21e/0x3c0 fs/read_write.c:735
 do_iter_write+0x17f/0x7f0 fs/read_write.c:860
 vfs_iter_write+0x7a/0xb0 fs/read_write.c:901
 iter_file_splice_write+0x698/0xc00 fs/splice.c:736
 do_splice_from fs/splice.c:933 [inline]
 do_splice+0x127f/0x1f80 fs/splice.c:1292
 __do_splice+0x323/0x360 fs/splice.c:1370
 __do_sys_splice fs/splice.c:1586 [inline]
 __se_sys_splice fs/splice.c:1568 [inline]
 __x64_sys_splice+0x1ce/0x260 fs/splice.c:1568
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f696fe470b9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f696fe09188 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f696fed0328 RCX: 00007f696fe470b9
RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000007
RBP: 00007f696fed0320 R08: 0000000000000100 R09: 0000000000000000
R10: 0000000