======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/u8:11/1366 is trying to acquire lock:
ffff8880623d16e8 (&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:
ffff888038a480a0 (&tree->tree_lock#2/1){+.+.}-{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#2/1){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline]
       mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552
       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+0x79/0xe0 fs/hfs/dir.c:232
       vfs_mkdir+0x40b/0x630 fs/namei.c:5233
       filename_mkdirat+0x289/0x520 fs/namei.c:5266
       __do_sys_mkdirat fs/namei.c:5287 [inline]
       __se_sys_mkdirat+0x35/0x150 fs/namei.c:5284
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/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+0xf0/0x2e0 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline]
       mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552
       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:459
       write_inode fs/fs-writeback.c:1582 [inline]
       __writeback_single_inode+0x75d/0x11a0 fs/fs-writeback.c:1813
       writeback_sb_inodes+0x995/0x19d0 fs/fs-writeback.c:2042
       wb_writeback+0x456/0xb70 fs/fs-writeback.c:2227
       wb_do_writeback fs/fs-writeback.c:2374 [inline]
       wb_workfn+0x41a/0xf60 fs/fs-writeback.c:2414
       process_one_work kernel/workqueue.c:3276 [inline]
       process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
       worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
       kthread+0x388/0x470 kernel/kthread.c:436
       ret_from_fork+0x51e/0xb90 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/u8:11/1366:
 #0: ffff88801eedf938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #0: ffff88801eedf938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0 kernel/workqueue.c:3359
 #1: ffffc9000683fc40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3252 [inline]
 #1: ffffc9000683fc40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0 kernel/workqueue.c:3359
 #2: ffff888038a480a0 (&tree->tree_lock#2/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x300 fs/hfs/bfind.c:-1

stack backtrace:
CPU: 0 UID: 0 PID: 1366 Comm: kworker/u8:11 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: writeback wb_workfn (flush-7:1)
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+0xf0/0x2e0 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline]
 mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552
 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:459
 write_inode fs/fs-writeback.c:1582 [inline]
 __writeback_single_inode+0x75d/0x11a0 fs/fs-writeback.c:1813
 writeback_sb_inodes+0x995/0x19d0 fs/fs-writeback.c:2042
 wb_writeback+0x456/0xb70 fs/fs-writeback.c:2227
 wb_do_writeback fs/fs-writeback.c:2374 [inline]
 wb_workfn+0x41a/0xf60 fs/fs-writeback.c:2414
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 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+0x461/0x4f0 fs/hfs/bnode.c:520, CPU#0: kworker/u8:11/1366
Modules linked in:
CPU: 0 UID: 0 PID: 1366 Comm: kworker/u8:11 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: writeback wb_workfn (flush-7:1)
RIP: 0010:hfs_bnode_create+0x461/0x4f0 fs/hfs/bnode.c:520
Code: 67 8b 89 ee e8 c0 ec 82 fe e9 cf fc ff ff e8 56 01 20 ff 4c 89 ef e8 0e 35 81 08 48 c7 c7 40 47 67 8b 89 ee e8 a0 ec 82 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:ffffc9000683ec60 EFLAGS: 00010246
RAX: 000000000000001f RBX: ffff888038a48000 RCX: dbbfc8b3265d9d00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1017104923 R12: 0000000000000000
R13: ffff888038a480d0 R14: ffff88803f817200 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888126339000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f60502e4000 CR3: 00000000568c6000 CR4: 00000000003526f0
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:459
 write_inode fs/fs-writeback.c:1582 [inline]
 __writeback_single_inode+0x75d/0x11a0 fs/fs-writeback.c:1813
 writeback_sb_inodes+0x995/0x19d0 fs/fs-writeback.c:2042
 wb_writeback+0x456/0xb70 fs/fs-writeback.c:2227
 wb_do_writeback fs/fs-writeback.c:2374 [inline]
 wb_workfn+0x41a/0xf60 fs/fs-writeback.c:2414
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>