syzbot

============================================
WARNING: possible recursive locking detected
6.12.0-syzkaller-09567-g7eef7e306d3c #0 Not tainted
--------------------------------------------
kworker/u4:4/55 is trying to acquire lock:
ffff888036718108 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_file_extend+0x21b/0x1b70 fs/hfsplus/extents.c:458

but task is already holding lock:
ffff8880367187c8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_ext_write_extent+0x8e/0x1f0 fs/hfsplus/extents.c:149

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&HFSPLUS_I(inode)->extents_lock);
  lock(&HFSPLUS_I(inode)->extents_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

5 locks held by kworker/u4:4/55:
 #0: ffff888030f0d148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline]
 #0: ffff888030f0d148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310
 #1: ffffc9000103fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline]
 #1: ffffc9000103fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310
 #2: ffff888034e260e0 (&type->s_umount_key#42){.+.+}-{4:4}, at: super_trylock_shared+0x22/0xf0 fs/super.c:562
 #3: ffff8880367187c8 (&HFSPLUS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfsplus_ext_write_extent+0x8e/0x1f0 fs/hfsplus/extents.c:149
 #4: ffff8880362640b0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfsplus_find_init+0x14a/0x1c0 fs/hfsplus/bfind.c:28

stack backtrace:
CPU: 0 UID: 0 PID: 55 Comm: kworker/u4:4 Not tainted 6.12.0-syzkaller-09567-g7eef7e306d3c #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_deadlock_bug+0x483/0x620 kernel/locking/lockdep.c:3037
 check_deadlock kernel/locking/lockdep.c:3089 [inline]
 validate_chain+0x15e2/0x5920 kernel/locking/lockdep.c:3891
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
 __mutex_lock_common kernel/locking/mutex.c:585 [inline]
 __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
 hfsplus_file_extend+0x21b/0x1b70 fs/hfsplus/extents.c:458
 hfsplus_bmap_reserve+0x105/0x4e0 fs/hfsplus/btree.c:358
 __hfsplus_ext_write_extent+0x2a4/0x5c0 fs/hfsplus/extents.c:104
 hfsplus_ext_write_extent_locked fs/hfsplus/extents.c:139 [inline]
 hfsplus_ext_write_extent+0x16a/0x1f0 fs/hfsplus/extents.c:150
 hfsplus_write_inode+0x22/0x5e0 fs/hfsplus/super.c:155
 write_inode fs/fs-writeback.c:1525 [inline]
 __writeback_single_inode+0x711/0x10d0 fs/fs-writeback.c:1745
 writeback_sb_inodes+0x80c/0x1370 fs/fs-writeback.c:1976
 __writeback_inodes_wb+0x11b/0x260 fs/fs-writeback.c:2047
 wb_writeback+0x427/0xbc0 fs/fs-writeback.c:2158
 wb_check_background_flush fs/fs-writeback.c:2228 [inline]
 wb_do_writeback fs/fs-writeback.c:2316 [inline]
 wb_workfn+0xc58/0x1090 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>