Oops: general protection fault, probably for non-canonical address 0xdffffc0000000084: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000420-0x0000000000000427]
CPU: 0 UID: 0 PID: 36 Comm: ksmd Not tainted 6.11.0-syzkaller-10622-gaa486552a110 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:scan_get_next_rmap_item mm/ksm.c:2529 [inline]
RIP: 0010:ksm_do_scan+0x823/0x6de0 mm/ksm.c:2651
Code: ff ff ff ff e8 2e f3 b6 09 48 89 c3 48 85 c0 4c 89 74 24 48 0f 84 ac 0b 00 00 48 89 5c 24 18 48 83 c3 20 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 9e 6b 01 00 48 8b 1b be 00 00 00
RSP: 0018:ffffc90000ac7a80 EFLAGS: 00010207
RAX: 0000000000000084 RBX: 0000000000000426 RCX: ffff8880206fbc00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000ac7d90 R08: ffffffff8bb09d21 R09: ffffffff8bb09ba7
R10: 0000000000000004 R11: ffff8880206fbc00 R12: ffffc90000ac7ce0
R13: ffffc90000ac7c70 R14: ffff8880325ed644 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc569b51780 CR3: 0000000021f9c000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ksm_scan_thread+0x110/0x490 mm/ksm.c:2676
 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>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:scan_get_next_rmap_item mm/ksm.c:2529 [inline]
RIP: 0010:ksm_do_scan+0x823/0x6de0 mm/ksm.c:2651
Code: ff ff ff ff e8 2e f3 b6 09 48 89 c3 48 85 c0 4c 89 74 24 48 0f 84 ac 0b 00 00 48 89 5c 24 18 48 83 c3 20 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 9e 6b 01 00 48 8b 1b be 00 00 00
RSP: 0018:ffffc90000ac7a80 EFLAGS: 00010207
RAX: 0000000000000084 RBX: 0000000000000426 RCX: ffff8880206fbc00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000ac7d90 R08: ffffffff8bb09d21 R09: ffffffff8bb09ba7
R10: 0000000000000004 R11: ffff8880206fbc00 R12: ffffc90000ac7ce0
R13: ffffc90000ac7c70 R14: ffff8880325ed644 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc569d37a8c CR3: 000000000e734000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 4 bytes skipped:
   0:	e8 2e f3 b6 09       	call   0x9b6f333
   5:	48 89 c3             	mov    %rax,%rbx
   8:	48 85 c0             	test   %rax,%rax
   b:	4c 89 74 24 48       	mov    %r14,0x48(%rsp)
  10:	0f 84 ac 0b 00 00    	je     0xbc2
  16:	48 89 5c 24 18       	mov    %rbx,0x18(%rsp)
  1b:	48 83 c3 20          	add    $0x20,%rbx
  1f:	48 89 d8             	mov    %rbx,%rax
  22:	48 c1 e8 03          	shr    $0x3,%rax
* 26:	42 80 3c 38 00       	cmpb   $0x0,(%rax,%r15,1) <-- trapping instruction
  2b:	74 08                	je     0x35
  2d:	48 89 df             	mov    %rbx,%rdi
  30:	e8 9e 6b 01 00       	call   0x16bd3
  35:	48 8b 1b             	mov    (%rbx),%rbx
  38:	be                   	.byte 0xbe
  39:	00 00                	add    %al,(%rax)