loop4: detected capacity change from 0 to 64
============================================
WARNING: possible recursive locking detected
6.1.140-syzkaller #0 Not tainted
--------------------------------------------
syz.4.36/4486 is trying to acquire lock:
ffff88802fa1a0b0 (&tree->tree_lock/1){+.+.}-{3:3}, at: hfs_find_init+0x15b/0x1d0 fs/hfs/bfind.c:-1

but task is already holding lock:
ffff88802fa1a0b0 (&tree->tree_lock/1){+.+.}-{3:3}, at: hfs_find_init+0x15b/0x1d0 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

6 locks held by syz.4.36/4486:
 #0: ffff88807c21cd68 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ae/0x360 fs/file.c:1040
 #1: ffff888075edc460 (sb_writers#16){.+.+}-{0:0}, at: vfs_write+0x256/0x960 fs/read_write.c:580
 #2: ffff8880286ba9a8 (&sb->s_type->i_mutex_key#23){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #2: ffff8880286ba9a8 (&sb->s_type->i_mutex_key#23){+.+.}-{3:3}, at: generic_file_write_iter+0x7f/0x2e0 mm/filemap.c:4003
 #3: ffff8880286ba7f8 (&HFS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfs_extend_file+0xd7/0x1280 fs/hfs/extent.c:397
 #4: ffff88802fa1a0b0 (&tree->tree_lock/1){+.+.}-{3:3}, at: hfs_find_init+0x15b/0x1d0 fs/hfs/bfind.c:-1
 #5: ffff8880286b9478 (&HFS_I(tree->inode)->extents_lock){+.+.}-{3:3}, at: hfs_extend_file+0xd7/0x1280 fs/hfs/extent.c:397

stack backtrace:
CPU: 1 PID: 4486 Comm: syz.4.36 Not tainted 6.1.140-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 __lock_acquire+0x122f/0x7c50 kernel/locking/lockdep.c:-1
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
 hfs_find_init+0x15b/0x1d0 fs/hfs/bfind.c:-1
 hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
 hfs_extend_file+0x2eb/0x1280 fs/hfs/extent.c:401
 hfs_bmap_reserve+0x103/0x420 fs/hfs/btree.c:234
 __hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
 __hfs_ext_cache_extent+0x6b/0x9b0 fs/hfs/extent.c:174
 hfs_ext_read_extent fs/hfs/extent.c:202 [inline]
 hfs_extend_file+0x313/0x1280 fs/hfs/extent.c:401
 hfs_get_block+0x3d4/0xbd0 fs/hfs/extent.c:353
 __block_write_begin_int+0x54b/0x1a70 fs/buffer.c:1991
 __block_write_begin fs/buffer.c:2041 [inline]
 block_write_begin+0x96/0x1e0 fs/buffer.c:2102
 cont_write_begin+0x5c4/0x7d0 fs/buffer.c:2456
 hfs_write_begin+0x87/0xd0 fs/hfs/inode.c:58
 generic_perform_write+0x2db/0x560 mm/filemap.c:3846
 __generic_file_write_iter+0x172/0x430 mm/filemap.c:3974
 generic_file_write_iter+0xab/0x2e0 mm/filemap.c:4006
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x44c/0x960 fs/read_write.c:584
 ksys_write+0x143/0x240 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f275b38e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f275c26a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f275b5b5fa0 RCX: 00007f275b38e969
RDX: 000000000208e24b RSI: 0000200000000280 RDI: 0000000000000005
RBP: 00007f275b410ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f275b5b5fa0 R15: 00007ffd8f25e8f8
 </TASK>