syzbot

loop2: detected capacity change from 0 to 64
======================================================
WARNING: possible circular locking dependency detected
6.1.142-syzkaller #0 Not tainted
------------------------------------------------------
syz.2.1164/10136 is trying to acquire lock:
ffff888074dec878 (&HFS_I(tree->inode)->extents_lock){+.+.}-{3:3}, at: hfs_extend_file+0xd7/0x1280 fs/hfs/extent.c:397

but task is already holding lock:
ffff888027f5c0b0 (&tree->tree_lock/1){+.+.}-{3:3}, at: hfs_find_init+0x15b/0x1d0 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/1){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
       hfs_find_init+0x15b/0x1d0 fs/hfs/bfind.c:-1
       hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
       hfs_extend_file+0x2eb/0x1280 fs/hfs/extent.c:401
       hfs_bmap_reserve+0x103/0x420 fs/hfs/btree.c:234
       hfs_cat_create+0x1c0/0x8d0 fs/hfs/catalog.c:104
       hfs_mkdir+0x68/0xe0 fs/hfs/dir.c:232
       vfs_mkdir+0x387/0x570 fs/namei.c:4106
       do_mkdirat+0x1d0/0x430 fs/namei.c:4131
       __do_sys_mkdirat fs/namei.c:4146 [inline]
       __se_sys_mkdirat fs/namei.c:4144 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4144
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&HFS_I(tree->inode)->extents_lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
       lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
       hfs_extend_file+0xd7/0x1280 fs/hfs/extent.c:397
       hfs_bmap_reserve+0x103/0x420 fs/hfs/btree.c:234
       __hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
       __hfs_ext_cache_extent+0x6b/0x9b0 fs/hfs/extent.c:174
       hfs_ext_read_extent fs/hfs/extent.c:202 [inline]
       hfs_extend_file+0x313/0x1280 fs/hfs/extent.c:401
       hfs_get_block+0x3d4/0xbd0 fs/hfs/extent.c:353
       __block_write_begin_int+0x54b/0x1a70 fs/buffer.c:1991
       __block_write_begin fs/buffer.c:2041 [inline]
       block_write_begin+0x96/0x1e0 fs/buffer.c:2102
       cont_write_begin+0x5c4/0x7d0 fs/buffer.c:2456
       hfs_write_begin+0x87/0xd0 fs/hfs/inode.c:58
       generic_perform_write+0x2db/0x560 mm/filemap.c:3846
       __generic_file_write_iter+0x172/0x430 mm/filemap.c:3974
       generic_file_write_iter+0xab/0x2e0 mm/filemap.c:4006
       do_iter_readv_writev fs/read_write.c:-1 [inline]
       do_iter_write+0x62d/0xaf0 fs/read_write.c:861
       vfs_writev fs/read_write.c:934 [inline]
       do_pwritev+0x201/0x340 fs/read_write.c:1031
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

4 locks held by syz.2.1164/10136:
 #0: ffff88805508c460 (sb_writers#15){.+.+}-{0:0}, at: vfs_writev fs/read_write.c:933 [inline]
 #0: ffff88805508c460 (sb_writers#15){.+.+}-{0:0}, at: do_pwritev+0x1ef/0x340 fs/read_write.c:1031
 #1: ffff888074dedda8 (&sb->s_type->i_mutex_key#42){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff888074dedda8 (&sb->s_type->i_mutex_key#42){+.+.}-{3:3}, at: generic_file_write_iter+0x7f/0x2e0 mm/filemap.c:4003
 #2: ffff888074dedbf8 (&HFS_I(inode)->extents_lock){+.+.}-{3:3}, at: hfs_extend_file+0xd7/0x1280 fs/hfs/extent.c:397
 #3: ffff888027f5c0b0 (&tree->tree_lock/1){+.+.}-{3:3}, at: hfs_find_init+0x15b/0x1d0 fs/hfs/bfind.c:-1

stack backtrace:
CPU: 1 PID: 10136 Comm: syz.2.1164 Not tainted 6.1.142-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
 hfs_extend_file+0xd7/0x1280 fs/hfs/extent.c:397
 hfs_bmap_reserve+0x103/0x420 fs/hfs/btree.c:234
 __hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
 __hfs_ext_cache_extent+0x6b/0x9b0 fs/hfs/extent.c:174
 hfs_ext_read_extent fs/hfs/extent.c:202 [inline]
 hfs_extend_file+0x313/0x1280 fs/hfs/extent.c:401
 hfs_get_block+0x3d4/0xbd0 fs/hfs/extent.c:353
 __block_write_begin_int+0x54b/0x1a70 fs/buffer.c:1991
 __block_write_begin fs/buffer.c:2041 [inline]
 block_write_begin+0x96/0x1e0 fs/buffer.c:2102
 cont_write_begin+0x5c4/0x7d0 fs/buffer.c:2456
 hfs_write_begin+0x87/0xd0 fs/hfs/inode.c:58
 generic_perform_write+0x2db/0x560 mm/filemap.c:3846
 __generic_file_write_iter+0x172/0x430 mm/filemap.c:3974
 generic_file_write_iter+0xab/0x2e0 mm/filemap.c:4006
 do_iter_readv_writev fs/read_write.c:-1 [inline]
 do_iter_write+0x62d/0xaf0 fs/read_write.c:861
 vfs_writev fs/read_write.c:934 [inline]
 do_pwritev+0x201/0x340 fs/read_write.c:1031
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f18fef8e929
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:00007f18ffddc038 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007f18ff1b5fa0 RCX: 00007f18fef8e929
RDX: 0000000000000001 RSI: 00002000000001c0 RDI: 0000000000000004
RBP: 00007f18ff010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000e7b R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f18ff1b5fa0 R15: 00007fff5c7d30f8
 </TASK>