syzbot

loop0: detected capacity change from 0 to 1024
======================================================
WARNING: possible circular locking dependency detected
6.16.0-rc5-syzkaller-00266-g3f31a806a62e #0 Not tainted
------------------------------------------------------
syz.0.19/6010 is trying to acquire lock:
ffff88807db0f8f8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_allocate+0x94/0x9b0 fs/hfsplus/bitmap.c:35

but task is already holding lock:
ffff888024596648 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1fc/0x1990 fs/hfsplus/extents.c:458

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}:
       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_get_block+0x39e/0x1530 fs/hfsplus/extents.c:260
       block_read_full_folio+0x29f/0x830 fs/buffer.c:2427
       filemap_read_folio+0x117/0x380 mm/filemap.c:2412
       do_read_cache_folio+0x350/0x590 mm/filemap.c:3894
       do_read_cache_page mm/filemap.c:3960 [inline]
       read_cache_page+0x5d/0x170 mm/filemap.c:3969
       read_mapping_page include/linux/pagemap.h:966 [inline]
       hfsplus_block_allocate+0xe4/0x9b0 fs/hfsplus/bitmap.c:37
       hfsplus_file_extend+0xae3/0x1990 fs/hfsplus/extents.c:469
       hfsplus_get_block+0x411/0x1530 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x6b5/0x1900 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
       page_symlink+0x26f/0x430 fs/namei.c:5520
       hfsplus_symlink+0xca/0x260 fs/hfsplus/dir.c:449
       vfs_symlink+0x143/0x2f0 fs/namei.c:4739
       do_symlinkat+0x1b1/0x3f0 fs/namei.c:4765
       __do_sys_symlinkat fs/namei.c:4781 [inline]
       __se_sys_symlinkat fs/namei.c:4778 [inline]
       __x64_sys_symlinkat+0x95/0xb0 fs/namei.c:4778
       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

-> #0 (&sbi->alloc_mutex){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3168 [inline]
       check_prevs_add kernel/locking/lockdep.c:3287 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911
       __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_block_allocate+0x94/0x9b0 fs/hfsplus/bitmap.c:35
       hfsplus_file_extend+0xae3/0x1990 fs/hfsplus/extents.c:469
       hfsplus_bmap_reserve+0x122/0x500 fs/hfsplus/btree.c:358
       hfsplus_create_cat+0x183/0x1000 fs/hfsplus/catalog.c:272
       hfsplus_fill_super+0x1314/0x1b70 fs/hfsplus/super.c:561
       get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1681
       vfs_get_tree+0x92/0x2b0 fs/super.c:1804
       do_new_mount+0x24a/0xa40 fs/namespace.c:3902
       do_mount fs/namespace.c:4239 [inline]
       __do_sys_mount fs/namespace.c:4450 [inline]
       __se_sys_mount+0x317/0x410 fs/namespace.c:4427
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&HFSPLUS_I(inode)->extents_lock);
                               lock(&sbi->alloc_mutex);
                               lock(&HFSPLUS_I(inode)->extents_lock);
  lock(&sbi->alloc_mutex);

 *** DEADLOCK ***

4 locks held by syz.0.19/6010:
 #0: ffff888078d860e0 (&type->s_umount_key#52/1){+.+.}-{4:4}, at: alloc_super+0x204/0x970 fs/super.c:345
 #1: ffff88807db0f998 (&sbi->vh_mutex){+.+.}-{4:4}, at: hfsplus_fill_super+0x1297/0x1b70 fs/hfsplus/super.c:554
 #2: ffff8880329ca0b0 (&tree->tree_lock){+.+.}-{4:4}, at: hfsplus_find_init+0x15a/0x1d0 fs/hfsplus/bfind.c:28
 #3: ffff888024596648 (&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: 6010 Comm: syz.0.19 Not tainted 6.16.0-rc5-syzkaller-00266-g3f31a806a62e #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2046
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3168 [inline]
 check_prevs_add kernel/locking/lockdep.c:3287 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911
 __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_block_allocate+0x94/0x9b0 fs/hfsplus/bitmap.c:35
 hfsplus_file_extend+0xae3/0x1990 fs/hfsplus/extents.c:469
 hfsplus_bmap_reserve+0x122/0x500 fs/hfsplus/btree.c:358
 hfsplus_create_cat+0x183/0x1000 fs/hfsplus/catalog.c:272
 hfsplus_fill_super+0x1314/0x1b70 fs/hfsplus/super.c:561
 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1681
 vfs_get_tree+0x92/0x2b0 fs/super.c:1804
 do_new_mount+0x24a/0xa40 fs/namespace.c:3902
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4427
 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: 0033:0x7f79e77900ca
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:00007ffe9ba9a628 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe9ba9a6b0 RCX: 00007f79e77900ca
RDX: 0000200000000000 RSI: 0000200000000080 RDI: 00007ffe9ba9a670
RBP: 0000200000000000 R08: 00007ffe9ba9a6b0 R09: 0000000002000010
R10: 0000000002000010 R11: 0000000000000246 R12: 0000200000000080
R13: 00007ffe9ba9a670 R14: 00000000000006a6 R15: 0000200000000100
 </TASK>