loop6: detected capacity change from 0 to 1024
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.6.1133/10640 is trying to acquire lock:
ffff88806d1e6d08 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_get_block+0x39e/0x1670 fs/hfsplus/extents.c:260

but task is already holding lock:
ffff888054e180f8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_allocate+0xa7/0xce0 fs/hfsplus/bitmap.c:35

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sbi->alloc_mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       hfsplus_block_allocate+0xa7/0xce0 fs/hfsplus/bitmap.c:35
       hfsplus_file_extend+0xb2d/0x1d70 fs/hfsplus/extents.c:464
       hfsplus_bmap_reserve+0x125/0x510 fs/hfsplus/btree.c:358
       hfsplus_create_cat+0x1e2/0x11b0 fs/hfsplus/catalog.c:272
       hfsplus_fill_super+0x1247/0x19e0 fs/hfsplus/super.c:601
       get_tree_bdev_flags+0x431/0x4f0 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+0x329/0xa50 fs/namespace.c:3712
       do_mount fs/namespace.c:4035 [inline]
       __do_sys_mount fs/namespace.c:4224 [inline]
       __se_sys_mount+0x31d/0x420 fs/namespace.c:4201
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       hfsplus_get_block+0x39e/0x1670 fs/hfsplus/extents.c:260
       block_read_full_folio+0x29f/0x830 fs/buffer.c:2420
       filemap_read_folio+0x137/0x3b0 mm/filemap.c:2496
       do_read_cache_folio+0x358/0x590 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:1022 [inline]
       hfsplus_block_allocate+0xf3/0xce0 fs/hfsplus/bitmap.c:37
       hfsplus_file_extend+0xb2d/0x1d70 fs/hfsplus/extents.c:464
       hfsplus_get_block+0x42c/0x1670 fs/hfsplus/extents.c:245
       __block_write_begin_int+0x6c6/0x1910 fs/buffer.c:2145
       block_write_begin fs/buffer.c:2256 [inline]
       cont_write_begin+0x737/0xae0 fs/buffer.c:2594
       hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:48
       page_symlink+0x27a/0x440 fs/namei.c:6286
       hfsplus_symlink+0xca/0x260 fs/hfsplus/dir.c:449
       vfs_symlink+0x4a1/0x550 fs/namei.c:5523
       do_symlinkat+0x1f1/0x3c0 fs/namei.c:5550
       __do_sys_symlinkat fs/namei.c:5571 [inline]
       __se_sys_symlinkat fs/namei.c:5568 [inline]
       __x64_sys_symlinkat+0x95/0xb0 fs/namei.c:5568
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xe2/0xf80 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(&sbi->alloc_mutex);
                               lock(&HFSPLUS_I(inode)->extents_lock);
                               lock(&sbi->alloc_mutex);
  lock(&HFSPLUS_I(inode)->extents_lock);

 *** DEADLOCK ***

5 locks held by syz.6.1133/10640:
 #0: ffff88807c4d6420 (sb_writers#21){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
 #1: ffff88806d1e75b8 (&type->i_mutex_dir_key#15/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
 #1: ffff88806d1e75b8 (&type->i_mutex_dir_key#15/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2873 [inline]
 #1: ffff88806d1e75b8 (&type->i_mutex_dir_key#15/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2884 [inline]
 #1: ffff88806d1e75b8 (&type->i_mutex_dir_key#15/1){+.+.}-{4:4}, at: filename_create+0x200/0x370 fs/namei.c:4888
 #2: ffff888054e18198 (&sbi->vh_mutex){+.+.}-{4:4}, at: hfsplus_symlink+0x81/0x260 fs/hfsplus/dir.c:444
 #3: ffff88806d1e07c8 (&hip->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x215/0x1d70 fs/hfsplus/extents.c:453
 #4: ffff888054e180f8 (&sbi->alloc_mutex){+.+.}-{4:4}, at: hfsplus_block_allocate+0xa7/0xce0 fs/hfsplus/bitmap.c:35

stack backtrace:
CPU: 0 UID: 0 PID: 10640 Comm: syz.6.1133 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:614 [inline]
 __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
 hfsplus_get_block+0x39e/0x1670 fs/hfsplus/extents.c:260
 block_read_full_folio+0x29f/0x830 fs/buffer.c:2420
 filemap_read_folio+0x137/0x3b0 mm/filemap.c:2496
 do_read_cache_folio+0x358/0x590 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:1022 [inline]
 hfsplus_block_allocate+0xf3/0xce0 fs/hfsplus/bitmap.c:37
 hfsplus_file_extend+0xb2d/0x1d70 fs/hfsplus/extents.c:464
 hfsplus_get_block+0x42c/0x1670 fs/hfsplus/extents.c:245
 __block_write_begin_int+0x6c6/0x1910 fs/buffer.c:2145
 block_write_begin fs/buffer.c:2256 [inline]
 cont_write_begin+0x737/0xae0 fs/buffer.c:2594
 hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:48
 page_symlink+0x27a/0x440 fs/namei.c:6286
 hfsplus_symlink+0xca/0x260 fs/hfsplus/dir.c:449
 vfs_symlink+0x4a1/0x550 fs/namei.c:5523
 do_symlinkat+0x1f1/0x3c0 fs/namei.c:5550
 __do_sys_symlinkat fs/namei.c:5571 [inline]
 __se_sys_symlinkat fs/namei.c:5568 [inline]
 __x64_sys_symlinkat+0x95/0xb0 fs/namei.c:5568
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa0d399aeb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa0d48dc028 EFLAGS: 00000246 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007fa0d3c15fa0 RCX: 00007fa0d399aeb9
RDX: 0000200000000100 RSI: ffffffffffffff9c RDI: 0000200000000080
RBP: 00007fa0d3a08c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa0d3c16038 R14: 00007fa0d3c15fa0 R15: 00007fff73b6ddd8
 </TASK>