[syzbot] [mm?] general protection fault in zap_huge_pmd

[syzbot <syzbot+de14f7701c22477db718@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    b84a0ebe421c Add linux-next specific files for 20260313
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=119ddd52580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e7280ad1f68b2dce
dashboard link: https://syzkaller.appspot.com/bug?extid=de14f7701c22477db718
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=173b44da580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1537b8da580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/09145161a8a9/disk-b84a0ebe.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b64c254e474c/vmlinux-b84a0ebe.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a7c33f5f7f45/bzImage-b84a0ebe.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+de14f7701c22477db718@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
CPU: 1 UID: 0 PID: 5994 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:folio_test_anon include/linux/page-flags.h:718 [inline]
RIP: 0010:zap_huge_pmd+0x7b1/0x1030 mm/huge_memory.c:2463
Code: 08 00 00 e8 11 e0 92 ff 48 c7 44 24 10 00 00 00 00 4c 8b 3c 24 4c 8d 75 18 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 f1 43 fc ff 49 8b 1e 48 89 de 48 83
RSP: 0018:ffffc90003bb7550 EFLAGS: 00010206
RAX: 0000000000000003 RBX: f000000000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003
RBP: 0000000000000000 R08: ffff88807cc9802f R09: 1ffff1100f993005
R10: dffffc0000000000 R11: ffffed100f993006 R12: ffff88807cc98028
R13: fffffffffffffa00 R14: 0000000000000018 R15: ffffc90003bb7ac0
FS:  0000000000000000(0000) GS:ffff888124ee0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000000c0 CR3: 000000000e94a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 zap_pmd_range mm/memory.c:1990 [inline]
 zap_pud_range mm/memory.c:2032 [inline]
 zap_p4d_range mm/memory.c:2053 [inline]
 __zap_vma_range+0xa82/0x4bd0 mm/memory.c:2093
 unmap_vmas+0x379/0x530 mm/memory.c:2162
 exit_mmap+0x280/0xa10 mm/mmap.c:1302
 __mmput+0x118/0x430 kernel/fork.c:1180
 exit_mm+0x18e/0x250 kernel/exit.c:581
 do_exit+0x8b9/0x2490 kernel/exit.c:962
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1116
 __do_sys_exit_group kernel/exit.c:1127 [inline]
 __se_sys_exit_group kernel/exit.c:1125 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1125
 x64_sys_call+0x221a/0x2240 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdd0b39c799
Code: Unable to access opcode bytes at 0x7fdd0b39c76f.
RSP: 002b:00007fff630f1d78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdd0b39c799
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: 0000000000000000 R09: 00007fdd0b5e63e0
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdd0b5e63e0 R14: 0000000000000003 R15: 00007fff630f1e30
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:folio_test_anon include/linux/page-flags.h:718 [inline]
RIP: 0010:zap_huge_pmd+0x7b1/0x1030 mm/huge_memory.c:2463
Code: 08 00 00 e8 11 e0 92 ff 48 c7 44 24 10 00 00 00 00 4c 8b 3c 24 4c 8d 75 18 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 f1 43 fc ff 49 8b 1e 48 89 de 48 83
RSP: 0018:ffffc90003bb7550 EFLAGS: 00010206
RAX: 0000000000000003 RBX: f000000000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003
RBP: 0000000000000000 R08: ffff88807cc9802f R09: 1ffff1100f993005
R10: dffffc0000000000 R11: ffffed100f993006 R12: ffff88807cc98028
R13: fffffffffffffa00 R14: 0000000000000018 R15: ffffc90003bb7ac0
FS:  0000000000000000(0000) GS:ffff888124ee0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000000c0 CR3: 000000000e94a000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	08 00                	or     %al,(%rax)
   2:	00 e8                	add    %ch,%al
   4:	11 e0                	adc    %esp,%eax
   6:	92                   	xchg   %eax,%edx
   7:	ff 48 c7             	decl   -0x39(%rax)
   a:	44 24 10             	rex.R and $0x10,%al
   d:	00 00                	add    %al,(%rax)
   f:	00 00                	add    %al,(%rax)
  11:	4c 8b 3c 24          	mov    (%rsp),%r15
  15:	4c 8d 75 18          	lea    0x18(%rbp),%r14
  19:	4c 89 f0             	mov    %r14,%rax
  1c:	48 c1 e8 03          	shr    $0x3,%rax
  20:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  27:	fc ff df
* 2a:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	4c 89 f7             	mov    %r14,%rdi
  33:	e8 f1 43 fc ff       	call   0xfffc4429
  38:	49 8b 1e             	mov    (%r14),%rbx
  3b:	48 89 de             	mov    %rbx,%rsi
  3e:	48                   	rex.W
  3f:	83                   	.byte 0x83


---
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