syzbot

============================================
WARNING: possible recursive locking detected
6.2.0-rc1-syzkaller #0 Not tainted
--------------------------------------------
syz-executor243/5058 is trying to acquire lock:
ffff8880245fc868 (&pipe->mutex/1){+.+.}-{3:3}, at: __pipe_lock fs/pipe.c:103 [inline]
ffff8880245fc868 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_write+0x12b/0x1aa0 fs/pipe.c:431

but task is already holding lock:
ffff8880245fc468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:82 [inline]
ffff8880245fc468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:90 [inline]
ffff8880245fc468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_wait_readable+0x3d7/0x550 fs/pipe.c:1049

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-executor243/5058:
 #0: ffff8880245fc468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:82 [inline]
 #0: ffff8880245fc468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:90 [inline]
 #0: ffff8880245fc468 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_wait_readable+0x3d7/0x550 fs/pipe.c:1049

stack backtrace:
CPU: 1 PID: 5058 Comm: syz-executor243 Not tainted 6.2.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 print_deadlock_bug kernel/locking/lockdep.c:2990 [inline]
 check_deadlock kernel/locking/lockdep.c:3033 [inline]
 validate_chain+0x4721/0x6470 kernel/locking/lockdep.c:3818
 __lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055
 lock_acquire+0x1a7/0x400 kernel/locking/lockdep.c:5668
 __mutex_lock_common+0x1de/0x26c0 kernel/locking/mutex.c:603
 __mutex_lock kernel/locking/mutex.c:747 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799
 __pipe_lock fs/pipe.c:103 [inline]
 pipe_write+0x12b/0x1aa0 fs/pipe.c:431
 do_iter_write+0x6f0/0xc50 fs/read_write.c:861
 iter_file_splice_write+0x830/0xff0 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 do_splice+0x1105/0x1930 fs/splice.c:1074
 __do_splice fs/splice.c:1139 [inline]
 __do_sys_splice fs/splice.c:1346 [inline]
 __se_sys_splice+0x2a8/0x410 fs/splice.c:1328
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f1f76a108e9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 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:00007f1f769c2308 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f1f76a98408 RCX: 00007f1f76a108e9
RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007f1f76a98400 R08: 0000000000000006 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1f76a66064
R13: 00007ffeca37fcff R14: 00007f1f769c2400 R15: 0000000000022000
 </TASK>