syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/u4:7/4946 is trying to acquire lock:
ffff8880244134f8 (&HFS_I(tree->inode)->extents_lock){+.+.}-{3:3}, at: hfs_extend_file+0xfb/0x13f0 fs/hfs/extent.c:397

but task is already holding lock:
ffff88814cbc80b0 (&tree->tree_lock#2/1){+.+.}-{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#2/1){+.+.}-{3:3}:
       __mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       hfs_find_init+0x15b/0x1d0 fs/hfs/bfind.c:-1
       hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
       hfs_extend_file+0x35d/0x13f0 fs/hfs/extent.c:401
       hfs_bmap_reserve+0x103/0x420 fs/hfs/btree.c:231
       hfs_cat_create+0x204/0x8e0 fs/hfs/catalog.c:104
       hfs_mkdir+0x68/0xe0 fs/hfs/dir.c:232
       vfs_mkdir+0x387/0x570 fs/namei.c:4073
       do_mkdirat+0x1df/0x5b0 fs/namei.c:4098
       __do_sys_mkdirat fs/namei.c:4113 [inline]
       __se_sys_mkdirat fs/namei.c:4111 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&HFS_I(tree->inode)->extents_lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c42/0x7d10 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       hfs_extend_file+0xfb/0x13f0 fs/hfs/extent.c:397
       hfs_bmap_reserve+0x103/0x420 fs/hfs/btree.c:231
       __hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
       hfs_ext_write_extent+0x17b/0x200 fs/hfs/extent.c:144
       hfs_write_inode+0xd8/0xa20 fs/hfs/inode.c:432
       write_inode fs/fs-writeback.c:1505 [inline]
       __writeback_single_inode+0x6c3/0xda0 fs/fs-writeback.c:1715
       writeback_sb_inodes+0xa4e/0x1680 fs/fs-writeback.c:1940
       wb_writeback+0x45d/0xbe0 fs/fs-writeback.c:2114
       wb_do_writeback fs/fs-writeback.c:2257 [inline]
       wb_workfn+0x43a/0xf20 fs/fs-writeback.c:2298
       process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
       worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
       kthread+0x436/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

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/u4:7/4946:
 #0: ffff888141bb8138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc9000342fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff88814cbc80b0 (&tree->tree_lock#2/1){+.+.}-{3:3}, at: hfs_find_init+0x15b/0x1d0 fs/hfs/bfind.c:-1

stack backtrace:
CPU: 1 PID: 4946 Comm: kworker/u4:7 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: writeback wb_workfn (flush-7:3)
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c42/0x7d10 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 hfs_extend_file+0xfb/0x13f0 fs/hfs/extent.c:397
 hfs_bmap_reserve+0x103/0x420 fs/hfs/btree.c:231
 __hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
 hfs_ext_write_extent+0x17b/0x200 fs/hfs/extent.c:144
 hfs_write_inode+0xd8/0xa20 fs/hfs/inode.c:432
 write_inode fs/fs-writeback.c:1505 [inline]
 __writeback_single_inode+0x6c3/0xda0 fs/fs-writeback.c:1715
 writeback_sb_inodes+0xa4e/0x1680 fs/fs-writeback.c:1940
 wb_writeback+0x45d/0xbe0 fs/fs-writeback.c:2114
 wb_do_writeback fs/fs-writeback.c:2257 [inline]
 wb_workfn+0x43a/0xf20 fs/fs-writeback.c:2298
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>