syzbot

hfs: unable to locate alternate MDB
hfs: continuing without an alternate MDB

============================================
WARNING: possible recursive locking detected
4.17.0-rc1+ #9 Not tainted
--------------------------------------------
syzkaller905163/4505 is trying to acquire lock:
00000000cf71528f (&tree->tree_lock){+.+.}, at: hfs_find_init+0x11c/0x180 fs/hfs/bfind.c:28

but task is already holding lock:
000000007d108cde (&tree->tree_lock){+.+.}, at: hfs_find_init+0x11c/0x180 fs/hfs/bfind.c:28

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

       CPU0
       ----
  lock(&tree->tree_lock);
  lock(&tree->tree_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by syzkaller905163/4505:
 #0: 000000005253f77a (&type->s_umount_key#36/1){+.+.}, at: alloc_super fs/super.c:212 [inline]
 #0: 000000005253f77a (&type->s_umount_key#36/1){+.+.}, at: sget_userns+0x2dd/0xf20 fs/super.c:503
 #1: 000000007d108cde (&tree->tree_lock){+.+.}, at: hfs_find_init+0x11c/0x180 fs/hfs/bfind.c:28
 #2: 00000000d9af4d52 (&HFS_I(tree->inode)->extents_lock){+.+.}, at: hfs_get_block+0x56c/0x850 fs/hfs/extent.c:359

stack backtrace:
CPU: 1 PID: 4505 Comm: syzkaller905163 Not tainted 4.17.0-rc1+ #9
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 print_deadlock_bug kernel/locking/lockdep.c:1761 [inline]
 check_deadlock kernel/locking/lockdep.c:1805 [inline]
 validate_chain kernel/locking/lockdep.c:2401 [inline]
 __lock_acquire.cold.62+0x18c/0x55b kernel/locking/lockdep.c:3431
 lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3920
 __mutex_lock_common kernel/locking/mutex.c:756 [inline]
 __mutex_lock+0x16d/0x17f0 kernel/locking/mutex.c:893
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
 hfs_find_init+0x11c/0x180 fs/hfs/bfind.c:28
 hfs_ext_read_extent+0x1b9/0xc20 fs/hfs/extent.c:196
 hfs_get_block+0x578/0x850 fs/hfs/extent.c:360
 block_read_full_page+0x2c7/0xab0 fs/buffer.c:2236
 hfs_readpage+0x1c/0x20 fs/hfs/inode.c:38
 do_read_cache_page+0x778/0x13b0 mm/filemap.c:2806
 read_cache_page+0x61/0x80 mm/filemap.c:2894
 read_mapping_page include/linux/pagemap.h:402 [inline]
 __hfs_bnode_create+0x601/0x9f0 fs/hfs/bnode.c:281
 hfs_bnode_find+0x2b8/0xb80 fs/hfs/bnode.c:330
 hfs_brec_find+0x2f3/0x5b0 fs/hfs/bfind.c:114
 hfs_brec_read+0x27/0x120 fs/hfs/bfind.c:153
 hfs_cat_find_brec+0x14a/0x400 fs/hfs/catalog.c:186
 hfs_fill_super+0x11f4/0x18c0 fs/hfs/super.c:426
 mount_bdev+0x30c/0x3e0 fs/super.c:1165
 hfs_mount+0x34/0x40 fs/hfs/super.c:463
 mount_fs+0xae/0x328 fs/super.c:1268
 vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037
 vfs_kern_mount fs/namespace.c:1027 [inline]
 do_new_mount fs/namespace.c:2517 [inline]
 do_mount+0x564/0x3070 fs/namespace.c:2847
 ksys_mount+0x12d/0x140 fs/namespace.c:3063
 __do_sys_mount fs/namespace.c:3077 [inline]
 __se_sys_mount fs/namespace.c:3074 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3074
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x442e4a
RSP: 002b:00007ffe9b4269d8 EFLAGS: 00000297 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000258 RCX: 0000000000442e4a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffe9b4269e0