syzbot

loop0: detected capacity change from 0 to 1024
======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc5-syzkaller-00275-gbec6f00f120e #0 Not tainted
------------------------------------------------------
syz-executor231/5832 is trying to acquire lock:
ffff888033a070f8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_allocate+0x9d/0x8e0 fs/hfsplus/bitmap.c:35

but task is already holding lock:
ffff8880334cbdc8 (&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:5866
       __mutex_lock_common kernel/locking/mutex.c:601 [inline]
       __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746
       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:2401
       do_read_cache_folio+0x354/0x590 mm/filemap.c:3885
       do_read_cache_page mm/filemap.c:3951 [inline]
       read_cache_page+0x5d/0x170 mm/filemap.c:3960
       read_mapping_page include/linux/pagemap.h:989 [inline]
       hfsplus_block_allocate+0xff/0x8e0 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
       generic_perform_write+0x2c7/0x910 mm/filemap.c:4103
       generic_file_write_iter+0x10f/0x540 mm/filemap.c:4246
       new_sync_write fs/read_write.c:591 [inline]
       vfs_write+0x54b/0xa90 fs/read_write.c:684
       ksys_write+0x145/0x250 fs/read_write.c:736
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf6/0x210 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:3166 [inline]
       check_prevs_add kernel/locking/lockdep.c:3285 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909
       __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
       __mutex_lock_common kernel/locking/mutex.c:601 [inline]
       __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746
       hfsplus_block_allocate+0x9d/0x8e0 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:1636
       vfs_get_tree+0x92/0x2b0 fs/super.c:1759
       do_new_mount+0x24a/0xa40 fs/namespace.c:3881
       do_mount fs/namespace.c:4221 [inline]
       __do_sys_mount fs/namespace.c:4432 [inline]
       __se_sys_mount+0x317/0x410 fs/namespace.c:4409
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf6/0x210 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-executor231/5832:
 #0: ffff88803460c0e0 (&type->s_umount_key#41/1){+.+.}-{4:4}, at: alloc_super+0x204/0x970 fs/super.c:344
 #1: ffff888033a07198 (&sbi->vh_mutex){+.+.}-{4:4}, at: hfsplus_fill_super+0x1297/0x1b70 fs/hfsplus/super.c:554
 #2: ffff8880348400b0 (&tree->tree_lock){+.+.}-{4:4}, at: hfsplus_find_init+0x15a/0x1d0 fs/hfsplus/bfind.c:28
 #3: ffff8880334cbdc8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x1fc/0x1990 fs/hfsplus/extents.c:458

stack backtrace:
CPU: 1 UID: 0 PID: 5832 Comm: syz-executor231 Not tainted 6.15.0-rc5-syzkaller-00275-gbec6f00f120e #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:2079
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2211
 check_prev_add kernel/locking/lockdep.c:3166 [inline]
 check_prevs_add kernel/locking/lockdep.c:3285 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909
 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
 __mutex_lock_common kernel/locking/mutex.c:601 [inline]
 __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746
 hfsplus_block_allocate+0x9d/0x8e0 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:1636
 vfs_get_tree+0x92/0x2b0 fs/super.c:1759
 do_new_mount+0x24a/0xa40 fs/namespace.c:3881
 do_mount fs/namespace.c:4221 [inline]
 __do_sys_mount fs/namespace.c:4432 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4409
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8e271bd7ea
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffef00138f8 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffef0013950 RCX: 00007f8e271bd7ea
RDX: 0000200000000000 RSI: 0000200000002380 RDI: 00007ffef0013950
RBP: 0000200000002380 R08: 00007ffef0013990 R09: 00000000000006dd
R10: 000000000080000c R11: 0000000000000286 R12: 0000200000000000
R13: 00007ffef0013990 R14: 00000000000006e3 R15: 0000200000000ac0
 </TASK>