syzbot

loop0: detected capacity change from 0 to 1024
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.17/6036 is trying to acquire lock:
ffff8880347b1548 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_get_block+0x272/0xac0 fs/hfsplus/extents.c:260

but task is already holding lock:
ffff8880347b22c8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_truncate+0x211/0xcd0 fs/hfsplus/extents.c:573

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

4 locks held by syz.0.17/6036:
 #0: ffff888077078420 (sb_writers#12){.+.+}-{0:0}, at: do_open fs/namei.c:4621 [inline]
 #0: ffff888077078420 (sb_writers#12){.+.+}-{0:0}, at: path_openat+0x25bd/0x3140 fs/namei.c:4787
 #1: ffff8880347b24b8 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1032 [inline]
 #1: ffff8880347b24b8 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: do_truncate+0x146/0x230 fs/open.c:63
 #2: ffff8880347b22c8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_truncate+0x211/0xcd0 fs/hfsplus/extents.c:573
 #3: ffff8880347438f8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_free+0xeb/0x6a0 fs/hfsplus/bitmap.c:182

stack backtrace:
CPU: 0 UID: 0 PID: 6036 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_deadlock_bug+0x225/0x2f0 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain kernel/locking/lockdep.c:3895 [inline]
 __lock_acquire+0x1497/0x2890 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:614 [inline]
 __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776
 hfsplus_get_block+0x272/0xac0 fs/hfsplus/extents.c:260
 block_read_full_folio+0x457/0x850 fs/buffer.c:2420
 filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2496
 do_read_cache_folio+0x266/0x5c0 mm/filemap.c:4096
 do_read_cache_page mm/filemap.c:4162 [inline]
 read_cache_page+0x5b/0x160 mm/filemap.c:4171
 read_mapping_page include/linux/pagemap.h:1011 [inline]
 hfsplus_block_free+0x14e/0x6a0 fs/hfsplus/bitmap.c:185
 hfsplus_free_extents+0x34e/0x4b0 fs/hfsplus/extents.c:360
 hfsplus_file_truncate+0xa05/0xcd0 fs/hfsplus/extents.c:588
 hfsplus_setattr+0x19f/0x320 fs/hfsplus/inode.c:286
 notify_change+0x6d2/0x1290 fs/attr.c:546
 do_truncate+0x1d7/0x230 fs/open.c:68
 handle_truncate fs/namei.c:4235 [inline]
 do_open fs/namei.c:4632 [inline]
 path_openat+0x2a1a/0x3140 fs/namei.c:4787
 do_filp_open+0x20b/0x470 fs/namei.c:4814
 do_sys_openat2+0x11f/0x280 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_creat fs/open.c:1514 [inline]
 __se_sys_creat fs/open.c:1508 [inline]
 __x64_sys_creat+0xcc/0x120 fs/open.c:1508
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f247898f749
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:00007ffff3b60f58 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007f2478be5fa0 RCX: 00007f247898f749
RDX: 0000000000000000 RSI: 0000000000000022 RDI: 0000200000000000
RBP: 00007f2478a13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2478be5fa0 R14: 00007f2478be5fa0 R15: 0000000000000002
 </TASK>
hfsplus: unable to mark blocks free: error -5
hfsplus: can't free extent: start 134, count 1