hfsplus: new node 0 already hashed?
------------[ cut here ]------------
WARNING: fs/hfsplus/bnode.c:671 at hfsplus_bnode_create+0x461/0x4f0 fs/hfsplus/bnode.c:671, CPU#0: syz.6.723/9359
Modules linked in:
CPU: 0 UID: 0 PID: 9359 Comm: syz.6.723 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:hfsplus_bnode_create+0x461/0x4f0 fs/hfsplus/bnode.c:671
Code: c1 8b 89 ee e8 e0 56 8e fe e9 cf fc ff ff e8 16 71 26 ff 4c 89 ef e8 8e 9a eb 08 48 c7 c7 c0 b6 c1 8b 89 ee e8 c0 56 8e 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:ffffc90002e95d40 EFLAGS: 00010246
RAX: 0000000000000023 RBX: ffff888024020000 RCX: 8bc9b0b648635f00
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffc90002e95a67 R09: 1ffff920005d2b4c
R10: dffffc0000000000 R11: fffff520005d2b4d R12: 0000000000000000
R13: ffff8880240200e0 R14: ffff888029aba400 R15: dffffc0000000000
FS:  0000200000000200(0000) GS:ffff8881259f0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f445c9056c0 CR3: 000000004e968000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 hfsplus_bmap_alloc+0x5af/0x640 fs/hfsplus/btree.c:415
 hfs_btree_inc_height+0xf6/0xb60 fs/hfsplus/brec.c:475
 hfsplus_brec_insert+0x12d/0xcc0 fs/hfsplus/brec.c:75
 __hfsplus_ext_write_extent+0x353/0x5b0 fs/hfsplus/extents.c:107
 __hfsplus_ext_cache_extent+0x89/0xe30 fs/hfsplus/extents.c:186
 hfsplus_ext_read_extent fs/hfsplus/extents.c:218 [inline]
 hfsplus_file_extend+0x444/0x1990 fs/hfsplus/extents.c:459
 hfsplus_get_block+0x411/0x1530 fs/hfsplus/extents.c:245
 __block_write_begin_int+0x6b5/0x1900 fs/buffer.c:2145
 block_write_begin fs/buffer.c:2256 [inline]
 cont_write_begin+0x789/0xb50 fs/buffer.c:2594
 hfsplus_write_begin+0x66/0xb0 fs/hfsplus/inode.c:48
 generic_perform_write+0x2c5/0x900 mm/filemap.c:4209
 generic_file_write_iter+0x117/0x550 mm/filemap.c:4352
 __kernel_write_iter+0x425/0x910 fs/read_write.c:619
 dump_emit_page fs/coredump.c:1298 [inline]
 dump_user_range+0x8a0/0xc90 fs/coredump.c:1372
 elf_core_dump+0x3369/0x3960 fs/binfmt_elf.c:2111
 coredump_write+0x1169/0x1900 fs/coredump.c:1049
 vfs_coredump+0x1db5/0x2a60 fs/coredump.c:1170
 get_signal+0x1109/0x1340 kernel/signal.c:3019
 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:40 [inline]
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 irqentry_exit_to_user_mode+0x81/0x120 kernel/entry/common.c:73
 exc_general_protection+0x171/0x200 arch/x86/kernel/traps.c:792
 asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:612
RIP: 0033:0x7f2c50d8ebb1
Code: 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 48 3d 01 f0 ff ff 73 01 <c3> 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:0000200000000090 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f2c50fd6090 RCX: 00007f2c50d8eba9
RDX: 00002000000000c0 RSI: 0000200000000090 RDI: 0000000001080000
RBP: 00007f2c50e11e19 R08: 0000200000000200 R09: 0000200000000200
R10: 00002000000001c0 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f2c50fd6128 R14: 00007f2c50fd6090 R15: 00007ffed74217d8
 </TASK>