======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
kworker/u8:2/36 is trying to acquire lock:
ffff8880504664f0 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xa6/0xcf0 fs/hfs/extent.c:397

but task is already holding lock:
ffff8880512820a8 (&tree->tree_lock#2/1){+.+.}-{4:4}, at: hfs_find_init+0x273/0x330 fs/hfs/bfind.c:36

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:632 [inline]
       __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806
       hfs_find_init+0x273/0x330 fs/hfs/bfind.c:36
       hfs_ext_read_extent+0x19d/0x9d0 fs/hfs/extent.c:200
       hfs_extend_file+0x4ff/0xcf0 fs/hfs/extent.c:401
       hfs_bmap_reserve+0x2ab/0x3a0 fs/hfs/btree.c:269
       hfs_cat_create+0x348/0x980 fs/hfs/catalog.c:104
       hfs_mkdir+0x7d/0x100 fs/hfs/dir.c:232
       vfs_mkdir+0x361/0x850 fs/namei.c:5261
       filename_mkdirat+0x48b/0x5e0 fs/namei.c:5294
       __do_sys_mkdirat fs/namei.c:5315 [inline]
       __se_sys_mkdirat fs/namei.c:5312 [inline]
       __x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5312
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&HFS_I(tree->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+0x14b8/0x2630 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825
       __mutex_lock_common kernel/locking/mutex.c:632 [inline]
       __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806
       hfs_extend_file+0xa6/0xcf0 fs/hfs/extent.c:397
       hfs_bmap_reserve+0x2ab/0x3a0 fs/hfs/btree.c:269
       __hfs_ext_write_extent+0x3c4/0x510 fs/hfs/extent.c:121
       hfs_ext_write_extent+0x1b7/0x200 fs/hfs/extent.c:144
       hfs_write_inode+0xce/0xab0 fs/hfs/inode.c:459
       write_inode fs/fs-writeback.c:1582 [inline]
       __writeback_single_inode+0xcd4/0x1350 fs/fs-writeback.c:1825
       writeback_sb_inodes+0x766/0x1c60 fs/fs-writeback.c:2054
       wb_writeback+0x1bf/0xb90 fs/fs-writeback.c:2239
       wb_do_writeback fs/fs-writeback.c:2386 [inline]
       wb_workfn+0x14f/0xc00 fs/fs-writeback.c:2426
       process_one_work+0xa0e/0x1980 kernel/workqueue.c:3288
       process_scheduled_works kernel/workqueue.c:3371 [inline]
       worker_thread+0x5ef/0xe50 kernel/workqueue.c:3452
       kthread+0x370/0x450 kernel/kthread.c:436
       ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

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/u8:2/36:
 #0: ffff888020ad8940 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3263
 #1: ffffc90000ac7d08 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3264
 #2: ffff8880512820a8 (&tree->tree_lock#2/1){+.+.}-{4:4}, at: hfs_find_init+0x273/0x330 fs/hfs/bfind.c:36

stack backtrace:
CPU: 0 UID: 0 PID: 36 Comm: kworker/u8:2 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: writeback wb_workfn (flush-7:5)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043
 check_noncircular+0x146/0x160 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+0x14b8/0x2630 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:632 [inline]
 __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806
 hfs_extend_file+0xa6/0xcf0 fs/hfs/extent.c:397
 hfs_bmap_reserve+0x2ab/0x3a0 fs/hfs/btree.c:269
 __hfs_ext_write_extent+0x3c4/0x510 fs/hfs/extent.c:121
 hfs_ext_write_extent+0x1b7/0x200 fs/hfs/extent.c:144
 hfs_write_inode+0xce/0xab0 fs/hfs/inode.c:459
 write_inode fs/fs-writeback.c:1582 [inline]
 __writeback_single_inode+0xcd4/0x1350 fs/fs-writeback.c:1825
 writeback_sb_inodes+0x766/0x1c60 fs/fs-writeback.c:2054
 wb_writeback+0x1bf/0xb90 fs/fs-writeback.c:2239
 wb_do_writeback fs/fs-writeback.c:2386 [inline]
 wb_workfn+0x14f/0xc00 fs/fs-writeback.c:2426
 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3288
 process_scheduled_works kernel/workqueue.c:3371 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3452
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
hfs: new node 0 already hashed?
------------[ cut here ]------------
1
WARNING: fs/hfs/bnode.c:520 at hfs_bnode_create.cold+0x41/0x49 fs/hfs/bnode.c:520, CPU#0: kworker/u8:2/36
Modules linked in:

CPU: 0 UID: 0 PID: 36 Comm: kworker/u8:2 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: writeback wb_workfn
 (flush-7:5)
RIP: 0010:hfs_bnode_create.cold+0x41/0x49 fs/hfs/bnode.c:520
Code: 95 fd 6a 0a e9 97 27 d1 01 e8 6b 75 e1 00 4c 89 f7 e8 83 fd 6a 0a e8 5e 75 e1 00 89 ee 48 c7 c7 40 8a d1 8b e8 c0 dc fa ff 90 <0f> 0b 90 e9 99 2a d1 01 e8 42 75 e1 00 e8 0d e3 4d 00 e9 f5 2c d1
RSP: 0018:ffffc90000ac7020 EFLAGS: 00010282
RAX: 000000000000001f RBX: ffff88807d74c400 RCX: 0000000000000000
RDX: 000000000000001f RSI: ffffffff81e79d79 RDI: fffff52000158df5
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 303178302f303178 R12: dffffc0000000000
R13: ffff888051282000 R14: ffff8880512820d8 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888124327000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc2b2e1f000 CR3: 000000007b6b0000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 hfs_bmap_alloc+0x5a7/0x6b0 fs/hfs/btree.c:326
 hfs_btree_inc_height.isra.0+0xff/0x820 fs/hfs/brec.c:490
 hfs_brec_insert+0x8ba/0xc20 fs/hfs/brec.c:148
 __hfs_ext_write_extent+0x3ef/0x510 fs/hfs/extent.c:124
 hfs_ext_write_extent+0x1b7/0x200 fs/hfs/extent.c:144
 hfs_write_inode+0xce/0xab0 fs/hfs/inode.c:459
 write_inode fs/fs-writeback.c:1582 [inline]
 __writeback_single_inode+0xcd4/0x1350 fs/fs-writeback.c:1825
 writeback_sb_inodes+0x766/0x1c60 fs/fs-writeback.c:2054
 wb_writeback+0x1bf/0xb90 fs/fs-writeback.c:2239
 wb_do_writeback fs/fs-writeback.c:2386 [inline]
 wb_workfn+0x14f/0xc00 fs/fs-writeback.c:2426
 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3288
 process_scheduled_works kernel/workqueue.c:3371 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3452
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>