BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 800000010f7b2067 P4D 800000010f7b2067 PUD 10438f067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 1 PID: 24 Comm: kworker/1:0 Not tainted 6.9.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Workqueue: bcachefs_write_ref bch2_do_invalidates_work
RIP: 0010:bch2_bkey_buf_realloc fs/bcachefs/bkey_buf.h:16 [inline]
RIP: 0010:bch2_bkey_buf_reassemble fs/bcachefs/bkey_buf.h:27 [inline]
RIP: 0010:btree_node_iter_and_journal_peek+0xc8/0x5d0 fs/bcachefs/btree_iter.c:898
Code: 00 00 4c 89 74 24 20 4c 89 f7 4c 89 e6 50 53 55 e8 0d 26 00 00 48 83 c4 18 4c 89 e7 e8 01 1f 00 00 49 89 c4 48 89 d5 49 8b 1f <80> 38 0d 72 33 49 8d 47 08 48 39 c3 75 2a 48 8b 44 24 08 48 8d b8
RSP: 0018:ffffc900000d37d8 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffffc900000d3a00 RCX: 578da58a1a59f400
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000000 R08: 000000000000000a R09: ffff88810d7caf10
R10: 0000000000000010 R11: 0000000000000010 R12: 0000000000000000
R13: ffff888106b4c228 R14: ffff888106b4c000 R15: ffffc900000d39f8
FS:  0000000000000000(0000) GS:ffff888237d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000016d1bc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 btree_path_down fs/bcachefs/btree_iter.c:926 [inline]
 bch2_btree_path_traverse_one+0xb1b/0xdd0 fs/bcachefs/btree_iter.c:1177
 bch2_btree_path_traverse fs/bcachefs/btree_iter.h:225 [inline]
 __bch2_btree_iter_peek fs/bcachefs/btree_iter.c:2059 [inline]
 bch2_btree_iter_peek_upto+0x35a/0xf40 fs/bcachefs/btree_iter.c:2158
 bch2_btree_iter_peek_upto_type fs/bcachefs/btree_iter.h:633 [inline]
 bch2_do_invalidates_work+0x30d/0xe80 fs/bcachefs/alloc_background.c:2014
 process_one_work kernel/workqueue.c:3254 [inline]
 process_scheduled_works+0x2a3/0x5b0 kernel/workqueue.c:3335
 worker_thread+0x23e/0x300 kernel/workqueue.c:3416
 kthread+0xea/0x100 kernel/kthread.c:388
 ret_from_fork+0x32/0x40 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:bch2_bkey_buf_realloc fs/bcachefs/bkey_buf.h:16 [inline]
RIP: 0010:bch2_bkey_buf_reassemble fs/bcachefs/bkey_buf.h:27 [inline]
RIP: 0010:btree_node_iter_and_journal_peek+0xc8/0x5d0 fs/bcachefs/btree_iter.c:898
Code: 00 00 4c 89 74 24 20 4c 89 f7 4c 89 e6 50 53 55 e8 0d 26 00 00 48 83 c4 18 4c 89 e7 e8 01 1f 00 00 49 89 c4 48 89 d5 49 8b 1f <80> 38 0d 72 33 49 8d 47 08 48 39 c3 75 2a 48 8b 44 24 08 48 8d b8
RSP: 0018:ffffc900000d37d8 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffffc900000d3a00 RCX: 578da58a1a59f400
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000000 R08: 000000000000000a R09: ffff88810d7caf10
R10: 0000000000000010 R11: 0000000000000010 R12: 0000000000000000
R13: ffff888106b4c228 R14: ffff888106b4c000 R15: ffffc900000d39f8
FS:  0000000000000000(0000) GS:ffff888237d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000016d1bc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	4c 89 74 24 20       	mov    %r14,0x20(%rsp)
   7:	4c 89 f7             	mov    %r14,%rdi
   a:	4c 89 e6             	mov    %r12,%rsi
   d:	50                   	push   %rax
   e:	53                   	push   %rbx
   f:	55                   	push   %rbp
  10:	e8 0d 26 00 00       	call   0x2622
  15:	48 83 c4 18          	add    $0x18,%rsp
  19:	4c 89 e7             	mov    %r12,%rdi
  1c:	e8 01 1f 00 00       	call   0x1f22
  21:	49 89 c4             	mov    %rax,%r12
  24:	48 89 d5             	mov    %rdx,%rbp
  27:	49 8b 1f             	mov    (%r15),%rbx
* 2a:	80 38 0d             	cmpb   $0xd,(%rax) <-- trapping instruction
  2d:	72 33                	jb     0x62
  2f:	49 8d 47 08          	lea    0x8(%r15),%rax
  33:	48 39 c3             	cmp    %rax,%rbx
  36:	75 2a                	jne    0x62
  38:	48 8b 44 24 08       	mov    0x8(%rsp),%rax
  3d:	48                   	rex.W
  3e:	8d                   	.byte 0x8d
  3f:	b8                   	.byte 0xb8