syzbot

============================================
WARNING: possible recursive locking detected
6.1.83-syzkaller #0 Not tainted
--------------------------------------------
syz-executor124/4221 is trying to acquire lock:
ffff0000d8fe6c68 (&pipe->mutex/1){+.+.}-{3:3}, at: __pipe_lock fs/pipe.c:103 [inline]
ffff0000d8fe6c68 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_write+0x114/0x1990 fs/pipe.c:431

but task is already holding lock:
ffff0000d8fe7068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:82 [inline]
ffff0000d8fe7068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock+0x68/0x98 fs/pipe.c:90

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-executor124/4221:
 #0: ffff0000d8fe7068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:82 [inline]
 #0: ffff0000d8fe7068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock+0x68/0x98 fs/pipe.c:90

stack backtrace:
CPU: 1 PID: 4221 Comm: syz-executor124 Not tainted 6.1.83-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call trace:
 dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 dump_stack+0x1c/0x5c lib/dump_stack.c:113
 __lock_acquire+0x6310/0x7680 kernel/locking/lockdep.c:5049
 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662
 __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603
 __mutex_lock kernel/locking/mutex.c:747 [inline]
 mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
 __pipe_lock fs/pipe.c:103 [inline]
 pipe_write+0x114/0x1990 fs/pipe.c:431
 do_iter_write+0x534/0x964 fs/read_write.c:861
 vfs_iter_write+0x88/0xac fs/read_write.c:902
 iter_file_splice_write+0x62c/0xc5c fs/splice.c:685
 do_splice_from fs/splice.c:763 [inline]
 do_splice+0xfd0/0x1898 fs/splice.c:1102
 __do_splice fs/splice.c:1167 [inline]
 __do_sys_splice fs/splice.c:1374 [inline]
 __se_sys_splice fs/splice.c:1356 [inline]
 __arm64_sys_splice+0x50c/0x7fc fs/splice.c:1356
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585