[syzbot] [fs?] kernel BUG in mpage_readahead

[syzbot <syzbot+fdba5cca73fee92c69d6@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    25fae0b93d1d Merge tag 'drm-fixes-2025-07-24' of https://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=152d70a2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=859f36d9ccbeaa3e
dashboard link: https://syzkaller.appspot.com/bug?extid=fdba5cca73fee92c69d6
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/dc00f98ff419/disk-25fae0b9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/05e43f05893a/vmlinux-25fae0b9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3b079c14e6b9/bzImage-25fae0b9.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fdba5cca73fee92c69d6@syzkaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at ./include/linux/pagemap.h:1379!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 10369 Comm: syz.3.1129 Not tainted 6.16.0-rc7-syzkaller-00034-g25fae0b93d1d #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:__readahead_folio include/linux/pagemap.h:1379 [inline]
RIP: 0010:readahead_folio include/linux/pagemap.h:1405 [inline]
RIP: 0010:mpage_readahead+0x637/0x650 fs/mpage.c:367
Code: c6 a0 d9 99 8b e8 69 13 c1 ff 90 0f 0b e8 b1 e6 7c ff 4c 89 ef 48 c7 c6 00 da 99 8b e8 52 13 c1 ff 90 0f 0b e8 9a e6 7c ff 90 <0f> 0b e8 92 e6 7c ff 90 0f 0b 66 66 66 66 66 66 2e 0f 1f 84 00 00
RSP: 0018:ffffc90003876f40 EFLAGS: 00010246
RAX: ffffffff82433f16 RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc90010f1f000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc90003877130 R08: ffffea00016fac07 R09: 1ffffd40002df580
R10: dffffc0000000000 R11: fffff940002df581 R12: dffffc0000000000
R13: ffffc900038773a8 R14: 0000000000000010 R15: ffffc900038773c0
FS:  00007f969af276c0(0000) GS:ffff888125c57000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe3f14b6fe0 CR3: 0000000030d80000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 read_pages+0x177/0x580 mm/readahead.c:160
 page_cache_ra_unbounded+0x346/0x7b0 mm/readahead.c:264
 do_sync_mmap_readahead+0x370/0x5f0 mm/filemap.c:3247
 filemap_fault+0x62a/0x1200 mm/filemap.c:3412
 __do_fault+0x135/0x390 mm/memory.c:5169
 do_read_fault mm/memory.c:5590 [inline]
 do_fault mm/memory.c:5724 [inline]
 do_pte_missing mm/memory.c:4251 [inline]
 handle_pte_fault mm/memory.c:6069 [inline]
 __handle_mm_fault+0x37ed/0x5620 mm/memory.c:6212
 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6381
 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0010:rep_movs_alternative+0x30/0x90 arch/x86/lib/copy_user_64.S:60
Code: 83 f9 08 73 25 85 c9 74 0f 8a 06 88 07 48 ff c7 48 ff c6 48 ff c9 75 f1 c3 cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 <48> 8b 06 48 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 db 83 f9 08
RSP: 0018:ffffc90003877a18 EFLAGS: 00050206
RAX: 00007ffffffff001 RBX: 0000000000000038 RCX: 0000000000000038
RDX: 0000000000000001 RSI: 0000200000391000 RDI: ffffc90003877aa0
RBP: ffffc90003877c30 R08: ffffc90003877ad7 R09: 1ffff9200070ef5a
R10: dffffc0000000000 R11: fffff5200070ef5b R12: 0000000000000002
R13: dffffc0000000000 R14: ffffc90003877aa0 R15: 0000200000391000
 copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:141 [inline]
 _inline_copy_from_user include/linux/uaccess.h:178 [inline]
 _copy_from_user+0x7a/0xb0 lib/usercopy.c:18
 copy_from_user include/linux/uaccess.h:212 [inline]
 copy_msghdr_from_user net/socket.c:2496 [inline]
 recvmsg_copy_msghdr net/socket.c:2752 [inline]
 ___sys_recvmsg+0x12e/0x510 net/socket.c:2824
 do_recvmmsg+0x307/0x770 net/socket.c:2923
 __sys_recvmmsg net/socket.c:2997 [inline]
 __do_sys_recvmmsg net/socket.c:3020 [inline]
 __se_sys_recvmmsg net/socket.c:3013 [inline]
 __x64_sys_recvmmsg+0x190/0x240 net/socket.c:3013
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f969a18e9a9
Code: ff ff c3 66 2e 0f 1f 84 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
RSP: 002b:00007f969af27038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f969a3b6080 RCX: 00007f969a18e9a9
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007f969a210d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f969a3b6080 R15: 00007ffd46031bf8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__readahead_folio include/linux/pagemap.h:1379 [inline]
RIP: 0010:readahead_folio include/linux/pagemap.h:1405 [inline]
RIP: 0010:mpage_readahead+0x637/0x650 fs/mpage.c:367
Code: c6 a0 d9 99 8b e8 69 13 c1 ff 90 0f 0b e8 b1 e6 7c ff 4c 89 ef 48 c7 c6 00 da 99 8b e8 52 13 c1 ff 90 0f 0b e8 9a e6 7c ff 90 <0f> 0b e8 92 e6 7c ff 90 0f 0b 66 66 66 66 66 66 2e 0f 1f 84 00 00
RSP: 0018:ffffc90003876f40 EFLAGS: 00010246
RAX: ffffffff82433f16 RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc90010f1f000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc90003877130 R08: ffffea00016fac07 R09: 1ffffd40002df580
R10: dffffc0000000000 R11: fffff940002df581 R12: dffffc0000000000
R13: ffffc900038773a8 R14: 0000000000000010 R15: ffffc900038773c0
FS:  00007f969af276c0(0000) GS:ffff888125d57000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe3f1497d58 CR3: 0000000030d80000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	83 f9 08             	cmp    $0x8,%ecx
   3:	73 25                	jae    0x2a
   5:	85 c9                	test   %ecx,%ecx
   7:	74 0f                	je     0x18
   9:	8a 06                	mov    (%rsi),%al
   b:	88 07                	mov    %al,(%rdi)
   d:	48 ff c7             	inc    %rdi
  10:	48 ff c6             	inc    %rsi
  13:	48 ff c9             	dec    %rcx
  16:	75 f1                	jne    0x9
  18:	c3                   	ret
  19:	cc                   	int3
  1a:	cc                   	int3
  1b:	cc                   	int3
  1c:	cc                   	int3
  1d:	66 2e 0f 1f 84 00 00 	cs nopw 0x0(%rax,%rax,1)
  24:	00 00 00
  27:	0f 1f 00             	nopl   (%rax)
* 2a:	48 8b 06             	mov    (%rsi),%rax <-- trapping instruction
  2d:	48 89 07             	mov    %rax,(%rdi)
  30:	48 83 c6 08          	add    $0x8,%rsi
  34:	48 83 c7 08          	add    $0x8,%rdi
  38:	83 e9 08             	sub    $0x8,%ecx
  3b:	74 db                	je     0x18
  3d:	83 f9 08             	cmp    $0x8,%ecx


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup