======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
kworker/u8:1/13 is trying to acquire lock:
ffff8880308e4ef8 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf2/0x15e0 fs/hfs/extent.c:397

but task is already holding lock:
ffff888074f020b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/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/1){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       hfs_find_init+0x18e/0x300 fs/hfs/bfind.c:-1
       hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
       hfs_extend_file+0x35c/0x15e0 fs/hfs/extent.c:401
       hfs_bmap_reserve+0x107/0x430 fs/hfs/btree.c:269
       hfs_cat_create+0x20f/0x800 fs/hfs/catalog.c:104
       hfs_mkdir+0x6c/0xe0 fs/hfs/dir.c:232
       vfs_mkdir+0x753/0x870 fs/namei.c:5139
       do_mkdirat+0x27d/0x4b0 fs/namei.c:5173
       __do_sys_mkdirat fs/namei.c:5195 [inline]
       __se_sys_mkdirat fs/namei.c:5193 [inline]
       __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:5193
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xe2/0xf80 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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       hfs_extend_file+0xf2/0x15e0 fs/hfs/extent.c:397
       hfs_bmap_reserve+0x107/0x430 fs/hfs/btree.c:269
       __hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
       hfs_ext_write_extent+0x17e/0x210 fs/hfs/extent.c:144
       hfs_write_inode+0x117/0x960 fs/hfs/inode.c:441
       write_inode fs/fs-writeback.c:1582 [inline]
       __writeback_single_inode+0x7e1/0x1230 fs/fs-writeback.c:1802
       writeback_sb_inodes+0x92e/0x1940 fs/fs-writeback.c:2030
       wb_writeback+0x445/0xad0 fs/fs-writeback.c:2216
       wb_do_writeback fs/fs-writeback.c:2363 [inline]
       wb_workfn+0x3f8/0xef0 fs/fs-writeback.c:2403
       process_one_work kernel/workqueue.c:3257 [inline]
       process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340
       worker_thread+0xda6/0x1360 kernel/workqueue.c:3421
       kthread+0x726/0x8b0 kernel/kthread.c:463
       ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

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 ***

3 locks held by kworker/u8:1/13:
 #0: ffff888141ec6148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff888141ec6148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc90000127bc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc90000127bc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
 #2: ffff888074f020b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x300 fs/hfs/bfind.c:-1

stack backtrace:
CPU: 0 UID: 0 PID: 13 Comm: kworker/u8:1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Workqueue: writeback wb_workfn (flush-7:6)
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:614 [inline]
 __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
 hfs_extend_file+0xf2/0x15e0 fs/hfs/extent.c:397
 hfs_bmap_reserve+0x107/0x430 fs/hfs/btree.c:269
 __hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
 hfs_ext_write_extent+0x17e/0x210 fs/hfs/extent.c:144
 hfs_write_inode+0x117/0x960 fs/hfs/inode.c:441
 write_inode fs/fs-writeback.c:1582 [inline]
 __writeback_single_inode+0x7e1/0x1230 fs/fs-writeback.c:1802
 writeback_sb_inodes+0x92e/0x1940 fs/fs-writeback.c:2030
 wb_writeback+0x445/0xad0 fs/fs-writeback.c:2216
 wb_do_writeback fs/fs-writeback.c:2363 [inline]
 wb_workfn+0x3f8/0xef0 fs/fs-writeback.c:2403
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340
 worker_thread+0xda6/0x1360 kernel/workqueue.c:3421
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
hfs: new node 0 already hashed?
------------[ cut here ]------------
1
WARNING: fs/hfs/bnode.c:520 at hfs_bnode_create+0x461/0x4f0 fs/hfs/bnode.c:520, CPU#0: kworker/u8:1/13
Modules linked in:
CPU: 0 UID: 0 PID: 13 Comm: kworker/u8:1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Workqueue: writeback wb_workfn (flush-7:6)
RIP: 0010:hfs_bnode_create+0x461/0x4f0 fs/hfs/bnode.c:520
Code: c7 8b 89 ee e8 e0 33 7e fe e9 cf fc ff ff e8 56 fa 1a ff 4c 89 ef e8 ae 1c f0 08 48 c7 c7 a0 88 c7 8b 89 ee e8 c0 33 7e fe 90 <0f> 0b 90 eb b0 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c d6 fb ff ff
RSP: 0018:ffffc90000126c20 EFLAGS: 00010246
RAX: 000000000000001f RBX: ffff888074f02000 RCX: 2db94925ae030400
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1c7ce48 R12: 0000000000000000
R13: ffff888074f020e0 R14: ffff888026fb7800 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8881256f5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5345be1198 CR3: 0000000031581000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 hfs_bmap_alloc+0x5c1/0x650 fs/hfs/btree.c:326
 hfs_btree_inc_height+0x100/0xad0 fs/hfs/brec.c:490
 hfs_brec_insert+0x7ef/0xc90 fs/hfs/brec.c:148
 __hfs_ext_write_extent+0x2a1/0x470 fs/hfs/extent.c:124
 hfs_ext_write_extent+0x17e/0x210 fs/hfs/extent.c:144
 hfs_write_inode+0x117/0x960 fs/hfs/inode.c:441
 write_inode fs/fs-writeback.c:1582 [inline]
 __writeback_single_inode+0x7e1/0x1230 fs/fs-writeback.c:1802
 writeback_sb_inodes+0x92e/0x1940 fs/fs-writeback.c:2030
 wb_writeback+0x445/0xad0 fs/fs-writeback.c:2216
 wb_do_writeback fs/fs-writeback.c:2363 [inline]
 wb_workfn+0x3f8/0xef0 fs/fs-writeback.c:2403
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340
 worker_thread+0xda6/0x1360 kernel/workqueue.c:3421
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>