linux-kernel - Re: [syzbot] [mm?] WARNING in folio_remove_rmap

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Message-ID: <694a6a7b.050a0220.19928e.001d.GAE@google.com>
Date: Tue, 23 Dec 2025 02:10:03 -0800
From: syzbot <syzbot+b165fc2e11771c66d8ba@...kaller.appspotmail.com>
To: hdanton@...a.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] WARNING in folio_remove_rmap_ptes

Hello,

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

 arch_do_signal_or_restart+0x8f/0x7e0 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop+0x8c/0x540 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x4ee/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
------------[ cut here ]------------
WARNING: ./include/linux/rmap.h:462 at __folio_rmap_sanity_checks include/linux/rmap.h:462 [inline], CPU#2: syz.0.18/6397
WARNING: ./include/linux/rmap.h:462 at __folio_remove_rmap mm/rmap.c:1663 [inline], CPU#2: syz.0.18/6397
WARNING: ./include/linux/rmap.h:462 at folio_remove_rmap_ptes+0xc27/0xfb0 mm/rmap.c:1779, CPU#2: syz.0.18/6397
Modules linked in:
CPU: 2 UID: 0 PID: 6397 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:__folio_rmap_sanity_checks include/linux/rmap.h:462 [inline]
RIP: 0010:__folio_remove_rmap mm/rmap.c:1663 [inline]
RIP: 0010:folio_remove_rmap_ptes+0xc27/0xfb0 mm/rmap.c:1779
Code: 00 e9 49 f4 ff ff e8 98 2f aa ff e8 d3 4f 17 ff e9 98 fc ff ff e8 89 2f aa ff 48 c7 c6 40 b8 9c 8b 4c 89 e7 e8 7a 0c f5 ff 90 <0f> 0b 90 e9 5a f6 ff ff e8 6c 2f aa ff 48 8b 54 24 10 48 b8 00 00
RSP: 0018:ffffc90003d9f248 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffea0001468040 RCX: ffffc90003d9f12c
RDX: ffff888028758000 RSI: ffffffff8214b6f6 RDI: ffff888028758484
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffff888028758b30 R12: ffffea0001468040
R13: ffff88802af7d540 R14: 0000000000000000 R15: ffff888026a0e440
FS:  00007f7003d706c0(0000) GS:ffff8880d6af5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7003d6ff98 CR3: 0000000032cdb000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 zap_present_folio_ptes mm/memory.c:1650 [inline]
 zap_present_ptes mm/memory.c:1708 [inline]
 do_zap_pte_range mm/memory.c:1810 [inline]
 zap_pte_range mm/memory.c:1854 [inline]
 zap_pmd_range mm/memory.c:1946 [inline]
 zap_pud_range mm/memory.c:1975 [inline]
 zap_p4d_range mm/memory.c:1996 [inline]
 unmap_page_range+0x1b7d/0x43c0 mm/memory.c:2017
 unmap_single_vma+0x153/0x240 mm/memory.c:2059
 lock_unmap_vmas+0x30d/0x600 mm/memory.c:2126
 vms_clear_ptes+0x419/0x790 mm/vma.c:1231
 vms_complete_munmap_vmas+0x186/0x8f0 mm/vma.c:1278
 do_vmi_align_munmap+0x446/0x7e0 mm/vma.c:1537
 do_vmi_munmap+0x204/0x3e0 mm/vma.c:1585
 do_munmap+0xb6/0xf0 mm/mmap.c:1065
 mremap_to+0x236/0x450 mm/mremap.c:1378
 remap_move mm/mremap.c:1890 [inline]
 do_mremap+0x13a8/0x2020 mm/mremap.c:1933
 __do_sys_mremap+0x119/0x170 mm/mremap.c:1997
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7002f8f7c9
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:00007f7003d70038 EFLAGS: 00000246 ORIG_RAX: 0000000000000019
RAX: ffffffffffffffda RBX: 00007f70031e5fa0 RCX: 00007f7002f8f7c9
RDX: 0000000000004000 RSI: 0000000000004000 RDI: 0000200000ffc000
RBP: 00007f7003013f91 R08: 0000200000002000 R09: 0000000000000000
R10: 0000000000000007 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f70031e6038 R14: 00007f70031e5fa0 R15: 00007ffc9ec46fc8
 </TASK>


Tested on:

commit:         b9275466 Merge tag 'dma-mapping-6.19-2025-12-22' of gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1419fb58580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a11e0f726bfb6765
dashboard link: https://syzkaller.appspot.com/bug?extid=b165fc2e11771c66d8ba
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16508b92580000