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

[syzbot <syzbot+012c6245eaea0e23f7f9@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    df5d6180169a Add linux-next specific files for 20250210
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=16d343f8580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2cd616b6e736ca7
dashboard link: https://syzkaller.appspot.com/bug?extid=012c6245eaea0e23f7f9
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=138972a4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11737b18580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/92495cf20271/disk-df5d6180.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4b3656161842/vmlinux-df5d6180.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7fbc4e7a0f5d/bzImage-df5d6180.xz

The issue was bisected to:

commit 19c067c8a0f18b62d4a4235b0b327624c86f2e40
Author: Zi Yan <ziy@nvidia.com>
Date:   Wed Feb 5 03:14:13 2025 +0000

    mm/huge_memory: add buddy allocator like folio_split()

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=102f9bdf980000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=122f9bdf980000
console output: https://syzkaller.appspot.com/x/log.txt?x=142f9bdf980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+012c6245eaea0e23f7f9@syzkaller.appspotmail.com
Fixes: 19c067c8a0f1 ("mm/huge_memory: add buddy allocator like folio_split()")

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000024: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000120-0x0000000000000127]
CPU: 1 UID: 0 PID: 5949 Comm: syz-executor163 Not tainted 6.14.0-rc2-next-20250210-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
RIP: 0010:shmem_mapping+0x25/0x50 mm/shmem.c:281
Code: 90 90 90 90 90 f3 0f 1e fa 53 48 89 fb e8 c3 3a bd ff 48 81 c3 20 01 00 00 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 dd 35 24 00 48 c7 c0 80 6c 14 8c 48
RSP: 0018:ffffc90004036dd8 EFLAGS: 00010006
RAX: 0000000000000024 RBX: 0000000000000120 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000600 RDI: 0000000000000000
RBP: 0000000000000600 R08: ffffffff822bcf18 R09: 1ffffd4000331008
R10: dffffc0000000000 R11: fffff94000331009 R12: ffffea0001988018
R13: ffffea0001988080 R14: ffffea0001988018 R15: ffffea0001988000
FS:  00007f5e045316c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5e0458dae0 CR3: 0000000023c78000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __split_unmapped_folio+0x238a/0x3e50 mm/huge_memory.c:3587
 __folio_split+0x1267/0x16d0 mm/huge_memory.c:3871
 try_folio_split include/linux/huge_mm.h:374 [inline]
 truncate_inode_partial_folio+0x55d/0xdc0 mm/truncate.c:230
 shmem_undo_range+0xab7/0x1820 mm/shmem.c:1144
 shmem_truncate_range mm/shmem.c:1224 [inline]
 shmem_fallocate+0x431/0xf20 mm/shmem.c:3674
 vfs_fallocate+0x623/0x7a0 fs/open.c:338
 madvise_remove mm/madvise.c:1034 [inline]
 madvise_vma_behavior mm/madvise.c:1269 [inline]
 madvise_walk_vmas mm/madvise.c:1511 [inline]
 madvise_do_behavior+0x1f29/0x3c00 mm/madvise.c:1646
 do_madvise mm/madvise.c:1744 [inline]
 __do_sys_madvise mm/madvise.c:1752 [inline]
 __se_sys_madvise mm/madvise.c:1750 [inline]
 __x64_sys_madvise+0x11b/0x140 mm/madvise.c:1750
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5e04576519
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5e04531218 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007f5e04600308 RCX: 00007f5e04576519
RDX: 0000000000000009 RSI: 0000000000600003 RDI: 0000400000000000
RBP: 00007f5e04600300 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f5e045cd074
R13: 0000400000000000 R14: 0000400000000140 R15: 0000400000000040
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:shmem_mapping+0x25/0x50 mm/shmem.c:281
Code: 90 90 90 90 90 f3 0f 1e fa 53 48 89 fb e8 c3 3a bd ff 48 81 c3 20 01 00 00 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 dd 35 24 00 48 c7 c0 80 6c 14 8c 48
RSP: 0018:ffffc90004036dd8 EFLAGS: 00010006
RAX: 0000000000000024 RBX: 0000000000000120 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000600 RDI: 0000000000000000
RBP: 0000000000000600 R08: ffffffff822bcf18 R09: 1ffffd4000331008
R10: dffffc0000000000 R11: fffff94000331009 R12: ffffea0001988018
R13: ffffea0001988080 R14: ffffea0001988018 R15: ffffea0001988000
FS:  00007f5e045316c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5e0458dae0 CR3: 0000000023c78000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	90                   	nop
   1:	90                   	nop
   2:	90                   	nop
   3:	90                   	nop
   4:	90                   	nop
   5:	f3 0f 1e fa          	endbr64
   9:	53                   	push   %rbx
   a:	48 89 fb             	mov    %rdi,%rbx
   d:	e8 c3 3a bd ff       	call   0xffbd3ad5
  12:	48 81 c3 20 01 00 00 	add    $0x120,%rbx
  19:	48 89 d8             	mov    %rbx,%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:	48 89 df             	mov    %rbx,%rdi
  33:	e8 dd 35 24 00       	call   0x243615
  38:	48 c7 c0 80 6c 14 8c 	mov    $0xffffffff8c146c80,%rax
  3f:	48                   	rex.W


---
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