======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/u10:1/37 is trying to acquire lock:
ffff88817427f5f8 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf2/0x15e0

but task is already holding lock:
ffff8881a73d40b0 (&tree->tree_lock#2/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x300

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+0x19f/0x1300
       hfs_find_init+0x18e/0x300
       hfs_extend_file+0x35c/0x15e0
       hfs_bmap_reserve+0x107/0x430
       hfs_cat_create+0x20f/0x800
       hfs_mkdir+0x79/0xe0
       vfs_mkdir+0x413/0x630
       filename_mkdirat+0x285/0x510
       __se_sys_mkdirat+0x35/0x150
       do_syscall_64+0x14d/0xf80
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}:
       __lock_acquire+0x15a5/0x2cf0
       lock_acquire+0xf0/0x2e0
       __mutex_lock+0x19f/0x1300
       hfs_extend_file+0xf2/0x15e0
       hfs_bmap_reserve+0x107/0x430
       __hfs_ext_write_extent+0x1fa/0x470
       hfs_ext_write_extent+0x17e/0x210
       hfs_write_inode+0x117/0x960
       __writeback_single_inode+0x75a/0x11a0
       writeback_sb_inodes+0x992/0x1a20
       wb_writeback+0x456/0xb70
       wb_workfn+0x414/0xf50
       process_scheduled_works+0xb02/0x1830
       worker_thread+0xa50/0xfc0
       kthread+0x388/0x470
       ret_from_fork+0x51e/0xb90
       ret_from_fork_asm+0x1a/0x30

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 ***

3 locks held by kworker/u10:1/37:
 #0: ffff8881626ee148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830
 #1: ffffc90000ad7c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830
 #2: ffff8881a73d40b0 (&tree->tree_lock#2/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x300

stack backtrace:
CPU: 1 UID: 0 PID: 37 Comm: kworker/u10:1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: writeback wb_workfn (flush-7:1)
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_circular_bug+0x2e1/0x300
 check_noncircular+0x12e/0x150
 __lock_acquire+0x15a5/0x2cf0
 lock_acquire+0xf0/0x2e0
 __mutex_lock+0x19f/0x1300
 hfs_extend_file+0xf2/0x15e0
 hfs_bmap_reserve+0x107/0x430
 __hfs_ext_write_extent+0x1fa/0x470
 hfs_ext_write_extent+0x17e/0x210
 hfs_write_inode+0x117/0x960
 __writeback_single_inode+0x75a/0x11a0
 writeback_sb_inodes+0x992/0x1a20
 wb_writeback+0x456/0xb70
 wb_workfn+0x414/0xf50
 process_scheduled_works+0xb02/0x1830
 worker_thread+0xa50/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30
 </TASK>
