syzbot

loop0: detected capacity change from 0 to 1024
============================================
WARNING: possible recursive locking detected
6.16.0-rc7-syzkaller-00120-g5f33ebd2018c #0 Not tainted
--------------------------------------------
syz-executor310/5840 is trying to acquire lock:
ffff88807fe920b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfsplus_find_init+0x15a/0x1d0 fs/hfsplus/bfind.c:28

but task is already holding lock:
ffff88807fe920b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfsplus_find_init+0x15a/0x1d0 fs/hfsplus/bfind.c:28

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-executor310/5840:
 #0: ffff88807fe90428 (sb_writers#8){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3096 [inline]
 #0: ffff88807fe90428 (sb_writers#8){.+.+}-{0:0}, at: vfs_writev+0x288/0x960 fs/read_write.c:1055
 #1: ffff88807feaa4b8 (&sb->s_type->i_mutex_key#14){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:869 [inline]
 #1: ffff88807feaa4b8 (&sb->s_type->i_mutex_key#14){+.+.}-{4:4}, at: generic_file_write_iter+0xe3/0x540 mm/filemap.c:4252
 #2: ffff88807feaa2c8 (&hip->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1fc/0x1990 fs/hfsplus/extents.c:458
 #3: ffff88807fe920b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfsplus_find_init+0x15a/0x1d0 fs/hfsplus/bfind.c:28
 #4: ffff88807fea8108 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1fc/0x1990 fs/hfsplus/extents.c:458

stack backtrace:
CPU: 0 UID: 0 PID: 5840 Comm: syz-executor310 Not tainted 6.16.0-rc7-syzkaller-00120-g5f33ebd2018c #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3044
 check_deadlock kernel/locking/lockdep.c:3096 [inline]
 validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3898
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
 __mutex_lock_common kernel/locking/mutex.c:602 [inline]
 __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:747
 hfsplus_find_init+0x15a/0x1d0 fs/hfsplus/bfind.c:28
 hfsplus_ext_read_extent fs/hfsplus/extents.c:216 [inline]
 hfsplus_file_extend+0x416/0x1990 fs/hfsplus/extents.c:462
 hfsplus_bmap_reserve+0x122/0x500 fs/hfsplus/btree.c:358
 __hfsplus_ext_write_extent+0x28d/0x5b0 fs/hfsplus/extents.c:104
 __hfsplus_ext_cache_extent+0x89/0xe30 fs/hfsplus/extents.c:186
 hfsplus_ext_read_extent fs/hfsplus/extents.c:218 [inline]
 hfsplus_file_extend+0x444/0x1990 fs/hfsplus/extents.c:462
 hfsplus_get_block+0x411/0x1530 fs/hfsplus/extents.c:245
 __block_write_begin_int+0x6b2/0x1900 fs/buffer.c:2151
 block_write_begin fs/buffer.c:2262 [inline]
 cont_write_begin+0x789/0xb50 fs/buffer.c:2601
 hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:46
 cont_expand_zero fs/buffer.c:2528 [inline]
 cont_write_begin+0x2fa/0xb50 fs/buffer.c:2591
 hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:46
 generic_perform_write+0x2c4/0x910 mm/filemap.c:4112
 generic_file_write_iter+0x10f/0x540 mm/filemap.c:4255
 do_iter_readv_writev+0x56b/0x7f0 fs/read_write.c:-1
 vfs_writev+0x31a/0x960 fs/read_write.c:1057
 do_pwritev fs/read_write.c:1153 [inline]
 __do_sys_pwritev2 fs/read_write.c:1211 [inline]
 __se_sys_pwritev2+0x179/0x290 fs/read_write.c:1202
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7effd4da4b99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 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:00007ffc96f3a588 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007effd4da4b99
RDX: 0000000000000001 RSI: 0000200000000240 RDI: 0000000000000004
RBP: 00007effd4e185f0 R08: 0000000000000000 R09: 0000000000000002
R10: 0000000001ffffff R11: 0000000000000246 R12: 00007ffc96f3a5c0
R13: 00007ffc96f3a7e8 R14: 0000200000000084 R15: 0000200000000080
 </TASK>