Re: [syzbot] [mm?] WARNING in folio_add_new_anon_rmap

[syzbot <syzbot+e24a2e34fad0efbac047@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in folio_add_new_anon_rmap

------------[ cut here ]------------
address < vma->vm_start || address + (nr << 12) > vma->vm_end
WARNING: mm/rmap.c:1682 at folio_add_new_anon_rmap+0x5fe/0x14b0 mm/rmap.c:1681, CPU#1: syz.0.32/6592
Modules linked in:
CPU: 1 UID: 0 PID: 6592 Comm: syz.0.32 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:folio_add_new_anon_rmap+0x5fe/0x14b0 mm/rmap.c:1681
Code: 89 f5 4d 8b 36 4c 89 e7 4c 89 f6 e8 0c aa a9 ff 4d 39 f4 73 1a e8 a2 a7 a9 ff 4c 8b 74 24 10 49 bc 00 00 00 00 00 fc ff df 90 <0f> 0b 90 eb 5a 44 89 f8 c1 e0 0c 48 98 49 01 c4 49 83 c5 08 4c 89
RSP: 0018:ffffc90003b175a0 EFLAGS: 00010293
RAX: ffffffff821d01ee RBX: ffffea0001c23500 RCX: ffff88802ebfdb80
RDX: 0000000000000000 RSI: 00002000004ca000 RDI: 00002000004cb000
RBP: 0000000000000000 R08: ffffea0001c23507 R09: 1ffffd40003846a0
R10: dffffc0000000000 R11: fffff940003846a1 R12: dffffc0000000000
R13: ffff888029014a08 R14: ffffea0001c23508 R15: 0000000000000001
FS:  00007f18a29856c0(0000) GS:ffff888125536000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff5a396d70 CR3: 000000007256a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 mfill_atomic_install_pte+0x578/0x870 mm/userfaultfd.c:390
 __mfill_atomic_pte+0x3c4/0x5f0 mm/userfaultfd.c:533
 mfill_atomic_pte_copy mm/userfaultfd.c:567 [inline]
 mfill_atomic_pte mm/userfaultfd.c:875 [inline]
 mfill_atomic mm/userfaultfd.c:933 [inline]
 mfill_atomic_copy+0x4d4/0x1420 mm/userfaultfd.c:960
 userfaultfd_copy fs/userfaultfd.c:1642 [inline]
 userfaultfd_ioctl+0x2bbe/0x4c70 fs/userfaultfd.c:2059
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 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: 0033:0x7f18a1b9c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f18a2985028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f18a1e15fa0 RCX: 00007f18a1b9c799
RDX: 0000200000000040 RSI: 00000000c028aa03 RDI: 0000000000000003
RBP: 00007f18a1c32c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f18a1e16038 R14: 00007f18a1e15fa0 R15: 00007ffca7001d38
 </TASK>


Tested on:

commit:         b84a0ebe Add linux-next specific files for 20260313
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15fc5602580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d079c776411aaf59
dashboard link: https://syzkaller.appspot.com/bug?extid=e24a2e34fad0efbac047
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=139c5602580000