loop1: detected capacity change from 0 to 64
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.1.18954/29426 is trying to acquire lock:
ffff88802aa2e260 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf9/0x1680 fs/hfs/extent.c:397

but task is already holding lock:
ffff888054e600a8 (&tree->tree_lock#2/1){+.+.}-{4:4}, at: hfs_find_init+0x18d/0x300 fs/hfs/bfind.c:-1

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&tree->tree_lock#2/1){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       hfs_find_init+0x18d/0x300 fs/hfs/bfind.c:-1
       hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
       hfs_get_block+0x4fd/0xbf0 fs/hfs/extent.c:366
       block_read_full_folio+0x29f/0x810 fs/buffer.c:2309
       filemap_read_folio+0x12c/0x3a0 mm/filemap.c:2520
       do_read_cache_folio+0x354/0x590 mm/filemap.c:4156
       do_read_cache_page mm/filemap.c:4222 [inline]
       read_cache_page+0x5d/0x170 mm/filemap.c:4231
       read_mapping_page include/linux/pagemap.h:1009 [inline]
       __hfs_bnode_create+0x4ad/0x970 fs/hfs/bnode.c:346
       hfs_bnode_find+0x20e/0xcf0 fs/hfs/bnode.c:391
       hfs_btree_open+0x1428/0x1f50 fs/hfs/btree.c:275
       hfs_mdb_get+0x1552/0x2130 fs/hfs/mdb.c:280
       hfs_fill_super+0x482/0x7b0 fs/hfs/super.c:352
       get_tree_bdev_flags+0x430/0x4f0 fs/super.c:1887
       vfs_get_tree+0x92/0x2a0 fs/super.c:1947
       fc_mount fs/namespace.c:1198 [inline]
       do_new_mount_fc fs/namespace.c:3772 [inline]
       do_new_mount+0x319/0xdc0 fs/namespace.c:3848
       do_mount fs/namespace.c:4181 [inline]
       __do_sys_mount fs/namespace.c:4397 [inline]
       __se_sys_mount+0x31d/0x420 fs/namespace.c:4374
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3181 [inline]
       check_prevs_add kernel/locking/lockdep.c:3300 [inline]
       validate_chain kernel/locking/lockdep.c:3924 [inline]
       __lock_acquire+0x15ff/0x2e50 kernel/locking/lockdep.c:5254
       lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       hfs_extend_file+0xf9/0x1680 fs/hfs/extent.c:397
       hfs_bmap_reserve+0x108/0x430 fs/hfs/btree.c:399
       __hfs_ext_write_extent+0x1fc/0x470 fs/hfs/extent.c:121
       __hfs_ext_cache_extent+0x6e/0x9b0 fs/hfs/extent.c:174
       hfs_ext_read_extent fs/hfs/extent.c:202 [inline]
       hfs_extend_file+0x3ad/0x1680 fs/hfs/extent.c:401
       hfs_get_block+0x401/0xbf0 fs/hfs/extent.c:353
       __block_write_begin_int+0x6c2/0x1900 fs/buffer.c:2031
       block_write_begin fs/buffer.c:2145 [inline]
       cont_write_begin+0x71b/0xac0 fs/buffer.c:2507
       hfs_write_begin+0x123/0x1c0 fs/hfs/inode.c:62
       generic_perform_write+0x2d5/0x8f0 mm/filemap.c:4374
       generic_file_write_iter+0xae/0x330 mm/filemap.c:4517
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x612/0xba0 fs/read_write.c:687
       ksys_write+0x150/0x270 fs/read_write.c:739
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&tree->tree_lock#2/1);
                               lock(&HFS_I(tree->inode)->extents_lock);
                               lock(&tree->tree_lock#2/1);
  lock(&HFS_I(tree->inode)->extents_lock);

 *** DEADLOCK ***

locks held by syz.1.18954/29426: 5, last CPU#0:
 #0: ffff88807a16bb30 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259
 #1: ffff888033612460 (sb_writers#25){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
 #1: ffff888033612460 (sb_writers#25){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
 #2: ffff888077d30800 (&sb->s_type->i_mutex_key#49){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #2: ffff888077d30800 (&sb->s_type->i_mutex_key#49){+.+.}-{4:4}, at: generic_file_write_iter+0x82/0x330 mm/filemap.c:4514
 #3: ffff888077d30660 (&HFS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf9/0x1680 fs/hfs/extent.c:397
 #4: ffff888054e600a8 (&tree->tree_lock#2/1){+.+.}-{4:4}, at: hfs_find_init+0x18d/0x300 fs/hfs/bfind.c:-1

stack backtrace:
CPU: 0 UID: 0 PID: 29426 Comm: syz.1.18954 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2059
 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2191
 check_prev_add kernel/locking/lockdep.c:3181 [inline]
 check_prevs_add kernel/locking/lockdep.c:3300 [inline]
 validate_chain kernel/locking/lockdep.c:3924 [inline]
 __lock_acquire+0x15ff/0x2e50 kernel/locking/lockdep.c:5254
 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
 hfs_extend_file+0xf9/0x1680 fs/hfs/extent.c:397
 hfs_bmap_reserve+0x108/0x430 fs/hfs/btree.c:399
 __hfs_ext_write_extent+0x1fc/0x470 fs/hfs/extent.c:121
 __hfs_ext_cache_extent+0x6e/0x9b0 fs/hfs/extent.c:174
 hfs_ext_read_extent fs/hfs/extent.c:202 [inline]
 hfs_extend_file+0x3ad/0x1680 fs/hfs/extent.c:401
 hfs_get_block+0x401/0xbf0 fs/hfs/extent.c:353
 __block_write_begin_int+0x6c2/0x1900 fs/buffer.c:2031
 block_write_begin fs/buffer.c:2145 [inline]
 cont_write_begin+0x71b/0xac0 fs/buffer.c:2507
 hfs_write_begin+0x123/0x1c0 fs/hfs/inode.c:62
 generic_perform_write+0x2d5/0x8f0 mm/filemap.c:4374
 generic_file_write_iter+0xae/0x330 mm/filemap.c:4517
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7eff4cf9e159
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:00007eff4de50028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007eff4d225fa0 RCX: 00007eff4cf9e159
RDX: 0000000000001006 RSI: 0000200000001400 RDI: 0000000000000004
RBP: 00007eff4d035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007eff4d226038 R14: 00007eff4d225fa0 R15: 00007ffdaea1cd78
 </TASK>