hfs: unable to locate alternate MDB
hfs: continuing without an alternate MDB
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.439/6415 is trying to acquire lock:
ffff0000e02840b0 (&tree->tree_lock/1){+.+.}-{3:3}, at: hfs_find_init+0x148/0x1c8 fs/hfs/bfind.c:-1

but task is already holding lock:
ffff0000e02840b0 (&tree->tree_lock/1){+.+.}-{3:3}, at: hfs_find_init+0x148/0x1c8 fs/hfs/bfind.c:-1

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&tree->tree_lock/1);
  lock(&tree->tree_lock/1);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

5 locks held by syz.0.439/6415:
 #0: ffff0000dd46a460 (sb_writers#18){.+.+}-{0:0}, at: do_sys_ftruncate+0x210/0x31c fs/open.c:190
 #1: ffff0000f1363028 (&sb->s_type->i_mutex_key#38){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff0000f1363028 (&sb->s_type->i_mutex_key#38){+.+.}-{3:3}, at: do_truncate+0x174/0x20c fs/open.c:63
 #2: ffff0000f1362e78 (&HFS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfs_extend_file+0xe4/0x1094 fs/hfs/extent.c:397
 #3: ffff0000e02840b0 (&tree->tree_lock/1){+.+.}-{3:3}, at: hfs_find_init+0x148/0x1c8 fs/hfs/bfind.c:-1
 #4: ffff0000d644cef8 (&HFS_I(tree->inode)->extents_lock){+.+.}-{3:3}, at: hfs_extend_file+0xe4/0x1094 fs/hfs/extent.c:397

stack backtrace:
CPU: 1 PID: 6415 Comm: syz.0.439 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
Call trace:
 dump_backtrace+0x1c0/0x1ec arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 dump_stack+0x1c/0x5c lib/dump_stack.c:113
 __lock_acquire+0x15cc/0x6800 kernel/locking/lockdep.c:-1
 lock_acquire+0x20c/0x63c kernel/locking/lockdep.c:5662
 __mutex_lock_common+0x190/0x1f60 kernel/locking/mutex.c:603
 __mutex_lock kernel/locking/mutex.c:747 [inline]
 mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
 hfs_find_init+0x148/0x1c8 fs/hfs/bfind.c:-1
 hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
 hfs_extend_file+0x28c/0x1094 fs/hfs/extent.c:401
 hfs_bmap_reserve+0xd4/0x3e0 fs/hfs/btree.c:234
 __hfs_ext_write_extent+0x198/0x484 fs/hfs/extent.c:121
 __hfs_ext_cache_extent+0x84/0x74c fs/hfs/extent.c:174
 hfs_ext_read_extent fs/hfs/extent.c:202 [inline]
 hfs_extend_file+0x2d0/0x1094 fs/hfs/extent.c:401
 hfs_get_block+0x324/0xa3c fs/hfs/extent.c:353
 __block_write_begin_int+0x350/0x1388 fs/buffer.c:1991
 __block_write_begin fs/buffer.c:2041 [inline]
 block_write_begin fs/buffer.c:2102 [inline]
 cont_write_begin+0x53c/0x780 fs/buffer.c:2456
 hfs_write_begin+0x98/0xe4 fs/hfs/inode.c:58
 cont_expand_zero fs/buffer.c:2383 [inline]
 cont_write_begin+0x25c/0x780 fs/buffer.c:2446
 hfs_write_begin+0x98/0xe4 fs/hfs/inode.c:58
 hfs_file_truncate+0x170/0x820 fs/hfs/extent.c:494
 hfs_inode_setattr+0x3a0/0x5bc fs/hfs/inode.c:659
 notify_change+0xb0c/0xdcc fs/attr.c:499
 do_truncate+0x188/0x20c fs/open.c:65
 do_sys_ftruncate+0x284/0x31c fs/open.c:193
 __do_sys_ftruncate fs/open.c:204 [inline]
 __se_sys_ftruncate fs/open.c:202 [inline]
 __arm64_sys_ftruncate+0x60/0x74 fs/open.c:202
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 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