syzbot

============================================
WARNING: possible recursive locking detected
5.15.153-syzkaller #0 Not tainted
--------------------------------------------
syz-executor.0/4504 is trying to acquire lock:
ffff8880195fdc68 (&pipe->mutex/1){+.+.}-{3:3}, at: __pipe_lock fs/pipe.c:102 [inline]
ffff8880195fdc68 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_write+0x12f/0x1b60 fs/pipe.c:430

but task is already holding lock:
ffff8880195fe068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:81 [inline]
ffff8880195fe068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:89 [inline]
ffff8880195fe068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_wait_readable+0x3e1/0x550 fs/pipe.c:1046

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-executor.0/4504:
 #0: ffff8880195fe068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:81 [inline]
 #0: ffff8880195fe068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:89 [inline]
 #0: ffff8880195fe068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_wait_readable+0x3e1/0x550 fs/pipe.c:1046

stack backtrace:
CPU: 1 PID: 4504 Comm: syz-executor.0 Not tainted 5.15.153-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_deadlock_bug kernel/locking/lockdep.c:2946 [inline]
 check_deadlock kernel/locking/lockdep.c:2989 [inline]
 validate_chain+0x46d2/0x5930 kernel/locking/lockdep.c:3775
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 __pipe_lock fs/pipe.c:102 [inline]
 pipe_write+0x12f/0x1b60 fs/pipe.c:430
 do_iter_readv_writev+0x594/0x7a0
 do_iter_write+0x1ea/0x760 fs/read_write.c:855
 iter_file_splice_write+0x806/0xfa0 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 do_splice+0xfe6/0x1790 fs/splice.c:1079
 __do_splice fs/splice.c:1144 [inline]
 __do_sys_splice fs/splice.c:1350 [inline]
 __se_sys_splice+0x340/0x420 fs/splice.c:1332
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fe6de0c0e69
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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:00007fe6dc6330c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007fe6de1eef80 RCX: 00007fe6de0c0e69
RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007fe6de10d47a R08: 0000000000008002 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fe6de1eef80 R15: 00007ffc0576f558
 </TASK>