syzbot

============================================
WARNING: possible recursive locking detected
6.4.0-rc5-syzkaller-00133-g25041a4c02c7 #0 Not tainted
--------------------------------------------
syz-executor128/5004 is trying to acquire lock:
ffff8880287ea068 (&pipe->mutex/1){+.+.}-{3:3}, at: __pipe_lock fs/pipe.c:103 [inline]
ffff8880287ea068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_write+0x140/0x1ca0 fs/pipe.c:432

but task is already holding lock:
ffff8880287e9c68 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:82 [inline]
ffff8880287e9c68 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:90 [inline]
ffff8880287e9c68 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_wait_readable+0x39f/0x420 fs/pipe.c:1054

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-executor128/5004:
 #0: ffff8880287e9c68 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:82 [inline]
 #0: ffff8880287e9c68 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:90 [inline]
 #0: ffff8880287e9c68 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_wait_readable+0x39f/0x420 fs/pipe.c:1054

stack backtrace:
CPU: 1 PID: 5004 Comm: syz-executor128 Not tainted 6.4.0-rc5-syzkaller-00133-g25041a4c02c7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 print_deadlock_bug kernel/locking/lockdep.c:3006 [inline]
 check_deadlock kernel/locking/lockdep.c:3049 [inline]
 validate_chain kernel/locking/lockdep.c:3834 [inline]
 __lock_acquire+0x13eb/0x5f30 kernel/locking/lockdep.c:5088
 lock_acquire kernel/locking/lockdep.c:5705 [inline]
 lock_acquire+0x1b1/0x520 kernel/locking/lockdep.c:5670
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747
 __pipe_lock fs/pipe.c:103 [inline]
 pipe_write+0x140/0x1ca0 fs/pipe.c:432
 call_write_iter include/linux/fs.h:1868 [inline]
 do_iter_readv_writev+0x20b/0x3b0 fs/read_write.c:735
 do_iter_write+0x185/0x7e0 fs/read_write.c:860
 vfs_iter_write+0x74/0xa0 fs/read_write.c:901
 iter_file_splice_write+0x743/0xc80 fs/splice.c:795
 do_splice_from fs/splice.c:873 [inline]
 do_splice+0xb8c/0x1e50 fs/splice.c:1182
 __do_splice+0x14e/0x270 fs/splice.c:1260
 __do_sys_splice fs/splice.c:1471 [inline]
 __se_sys_splice fs/splice.c:1453 [inline]
 __x64_sys_splice+0x19c/0x250 fs/splice.c:1453
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f34b2b28f69
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:00007f34b2adb278 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f34b2bb1428 RCX: 00007f34b2b28f69
RDX: 0000000000000007 RSI: 0000000000000000 RDI: 0000000000000008
RBP: 00007f34b2bb1420 R08: 0000000000000100 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f34b2b7f040
R13: 00007f34b2adb290 R14: 00007f34b2adb400 R15: 0000000000022000
 </TASK>