======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/u8:7/815 is trying to acquire lock:
ffff888061b21a98 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf9/0x1680 fs/hfs/extent.c:397

but task is already holding lock:
ffff8880360ca0a0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x18d/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/rtmutex_api.c:561 [inline]
       mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:580
       hfs_find_init+0x18d/0x300 fs/hfs/bfind.c:-1
       hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
       hfs_get_block+0x4fd/0xbf0 fs/hfs/extent.c:366
       block_read_full_folio+0x29f/0x810 fs/buffer.c:2308
       filemap_read_folio+0x12c/0x3a0 mm/filemap.c:2520
       do_read_cache_folio+0x2bf/0x560 mm/filemap.c:4156
       do_read_cache_page mm/filemap.c:4222 [inline]
       read_cache_page+0x5d/0x170 mm/filemap.c:4231
       read_mapping_page include/linux/pagemap.h:1009 [inline]
       __hfs_bnode_create+0x4ad/0x970 fs/hfs/bnode.c:346
       hfs_bnode_find+0x20e/0xcf0 fs/hfs/bnode.c:391
       hfs_brec_find+0x17b/0x510 fs/hfs/bfind.c:135
       hfs_brec_read+0x24/0x110 fs/hfs/bfind.c:174
       hfs_cat_find_brec+0x18f/0x690 fs/hfs/catalog.c:228
       hfs_fill_super+0x54d/0x7c0 fs/hfs/super.c:366
       get_tree_bdev_flags+0x430/0x4f0 fs/super.c:1872
       vfs_get_tree+0x92/0x2a0 fs/super.c:1932
       fc_mount fs/namespace.c:1278 [inline]
       do_new_mount_fc fs/namespace.c:3885 [inline]
       do_new_mount+0x325/0xb00 fs/namespace.c:3961
       do_mount fs/namespace.c:4325 [inline]
       __do_sys_mount fs/namespace.c:4543 [inline]
       __se_sys_mount+0x31d/0x420 fs/namespace.c:4520
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3209 [inline]
       check_prevs_add kernel/locking/lockdep.c:3328 [inline]
       validate_chain kernel/locking/lockdep.c:3952 [inline]
       __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288
       lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942
       __mutex_lock_common kernel/locking/rtmutex_api.c:561 [inline]
       mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:580
       hfs_extend_file+0xf9/0x1680 fs/hfs/extent.c:397
       hfs_bmap_reserve+0x108/0x430 fs/hfs/btree.c:399
       __hfs_ext_write_extent+0x1fc/0x470 fs/hfs/extent.c:121
       hfs_ext_write_extent+0x17d/0x210 fs/hfs/extent.c:144
       hfs_write_inode+0x117/0xa00 fs/hfs/inode.c:475
       write_inode fs/fs-writeback.c:1623 [inline]
       __writeback_single_inode+0x6a0/0x1230 fs/fs-writeback.c:1866
       writeback_sb_inodes+0x9db/0x1ab0 fs/fs-writeback.c:2114
       wb_writeback+0x41c/0xad0 fs/fs-writeback.c:2299
       wb_do_writeback fs/fs-writeback.c:2467 [inline]
       wb_workfn+0x437/0x10f0 fs/fs-writeback.c:2512
       process_one_work kernel/workqueue.c:3396 [inline]
       process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
       worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
       kthread+0x38b/0x470 kernel/kthread.c:436
       ret_from_fork+0x514/0xb70 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/1);
                               lock(&HFS_I(tree->inode)->extents_lock);
                               lock(&tree->tree_lock/1);
  lock(&HFS_I(tree->inode)->extents_lock);

 *** DEADLOCK ***

locks held by kworker/u8:7/815: 3, last CPU#1:
 #0: ffff88801feec938 ((wq_completion)writeback){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff88801feec938 ((wq_completion)writeback){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff88801feec938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff88801feec938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc90005affc40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc90005affc40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc90005affc40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc90005affc40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffff8880360ca0a0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x18d/0x300 fs/hfs/bfind.c:-1

stack backtrace:
CPU: 1 UID: 0 PID: 815 Comm: kworker/u8:7 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: writeback wb_workfn (flush-7:7)
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2087
 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2219
 check_prev_add kernel/locking/lockdep.c:3209 [inline]
 check_prevs_add kernel/locking/lockdep.c:3328 [inline]
 validate_chain kernel/locking/lockdep.c:3952 [inline]
 __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288
 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942
 __mutex_lock_common kernel/locking/rtmutex_api.c:561 [inline]
 mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:580
 hfs_extend_file+0xf9/0x1680 fs/hfs/extent.c:397
 hfs_bmap_reserve+0x108/0x430 fs/hfs/btree.c:399
 __hfs_ext_write_extent+0x1fc/0x470 fs/hfs/extent.c:121
 hfs_ext_write_extent+0x17d/0x210 fs/hfs/extent.c:144
 hfs_write_inode+0x117/0xa00 fs/hfs/inode.c:475
 write_inode fs/fs-writeback.c:1623 [inline]
 __writeback_single_inode+0x6a0/0x1230 fs/fs-writeback.c:1866
 writeback_sb_inodes+0x9db/0x1ab0 fs/fs-writeback.c:2114
 wb_writeback+0x41c/0xad0 fs/fs-writeback.c:2299
 wb_do_writeback fs/fs-writeback.c:2467 [inline]
 wb_workfn+0x437/0x10f0 fs/fs-writeback.c:2512
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
 kthread+0x38b/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 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:478 at hfs_bnode_create+0x45a/0x4e0 fs/hfs/bnode.c:478, CPU#1: kworker/u8:7/815
Modules linked in:
CPU: 1 UID: 0 PID: 815 Comm: kworker/u8:7 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: writeback wb_workfn (flush-7:7)
RIP: 0010:hfs_bnode_create+0x45a/0x4e0 fs/hfs/bnode.c:478
Code: 89 8b 89 ee e8 27 39 76 fe e9 d6 fc ff ff e8 0d ab 15 ff 4c 89 ef e8 85 ae ab 08 48 c7 c7 80 79 89 8b 89 ee e8 07 39 76 fe 90 <0f> 0b 90 eb b0 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c dd fb ff ff
RSP: 0018:ffffc90005afed08 EFLAGS: 00010246
RAX: 000000000000001f RBX: ffff8880360ca000 RCX: 3e1aeda5d92afd00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000b5fd4d R12: 0000000000000000
R13: ffff8880360ca0d0 R14: ffff88802138c000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888124abb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555565845a28 CR3: 0000000060d5e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 hfs_btree_inc_height+0xf9/0xac0 fs/hfs/brec.c:490
 hfs_brec_insert+0x7eb/0xc80 fs/hfs/brec.c:148
 __hfs_ext_write_extent+0x2a3/0x470 fs/hfs/extent.c:124
 hfs_ext_write_extent+0x17d/0x210 fs/hfs/extent.c:144
 hfs_write_inode+0x117/0xa00 fs/hfs/inode.c:475
 write_inode fs/fs-writeback.c:1623 [inline]
 __writeback_single_inode+0x6a0/0x1230 fs/fs-writeback.c:1866
 writeback_sb_inodes+0x9db/0x1ab0 fs/fs-writeback.c:2114
 wb_writeback+0x41c/0xad0 fs/fs-writeback.c:2299
 wb_do_writeback fs/fs-writeback.c:2467 [inline]
 wb_workfn+0x437/0x10f0 fs/fs-writeback.c:2512
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
 kthread+0x38b/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>