syzbot

loop0: detected capacity change from 0 to 1024
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.17/6068 is trying to acquire lock:
ffff888039591778 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_get_block+0x39a/0x1600 fs/hfsplus/extents.c:260

but task is already holding lock:
ffff888039590878 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1f8/0x1c40 fs/hfsplus/extents.c:453

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

       CPU0
       ----
  lock(&HFSPLUS_I(inode)->extents_lock);
  lock(&HFSPLUS_I(inode)->extents_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

5 locks held by syz.0.17/6068:
 #0: ffff888036d780d0 (&type->s_umount_key#54/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xab0 fs/super.c:344
 #1: ffff888027e9c978 (&sbi->vh_mutex){+.+.}-{4:4}, at: hfsplus_fill_super+0x1199/0x1940 fs/hfsplus/super.c:594
 #2: ffff888039dba0a0 (&tree->tree_lock){+.+.}-{4:4}, at: hfsplus_find_init+0x168/0x2d0 fs/hfsplus/bfind.c:28
 #3: ffff888039590878 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1f8/0x1c40 fs/hfsplus/extents.c:453
 #4: ffff888027e9c8e8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_allocate+0xa7/0xd10 fs/hfsplus/bitmap.c:35

stack backtrace:
CPU: 1 UID: 0 PID: 6068 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain kernel/locking/lockdep.c:3895 [inline]
 __lock_acquire+0x2540/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline]
 mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552
 hfsplus_get_block+0x39a/0x1600 fs/hfsplus/extents.c:260
 block_read_full_folio+0x29f/0x830 fs/buffer.c:2420
 filemap_read_folio+0x117/0x380 mm/filemap.c:2496
 do_read_cache_folio+0x2bf/0x560 mm/filemap.c:4096
 do_read_cache_page mm/filemap.c:4162 [inline]
 read_cache_page+0x5d/0x170 mm/filemap.c:4171
 read_mapping_page include/linux/pagemap.h:1011 [inline]
 hfsplus_block_allocate+0xf3/0xd10 fs/hfsplus/bitmap.c:37
 hfsplus_file_extend+0xa9a/0x1c40 fs/hfsplus/extents.c:464
 hfsplus_bmap_reserve+0x128/0x520 fs/hfsplus/btree.c:358
 hfsplus_create_cat+0x188/0x10e0 fs/hfsplus/catalog.c:272
 hfsplus_fill_super+0x1216/0x1940 fs/hfsplus/super.c:601
 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1691
 vfs_get_tree+0x92/0x2a0 fs/super.c:1751
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3636 [inline]
 do_new_mount+0x302/0xa10 fs/namespace.c:3712
 do_mount fs/namespace.c:4035 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount+0x313/0x410 fs/namespace.c:4201
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f18a7ef0eea
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007ffce4bf44e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffce4bf4570 RCX: 00007f18a7ef0eea
RDX: 0000200000000100 RSI: 00002000000002c0 RDI: 00007ffce4bf4530
RBP: 0000200000000100 R08: 00007ffce4bf4570 R09: 0000000002010094
R10: 0000000002010094 R11: 0000000000000246 R12: 00002000000002c0
R13: 00007ffce4bf4530 R14: 000000000000070a R15: 0000200000000140
 </TASK>