linux-kernel - Re: [syzbot] [kvm?] WARNING in kvm_gmem_fault_user

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Message-ID: <697f2bdf.050a0220.16b13.009e.GAE@google.com>
Date: Sun, 01 Feb 2026 02:33:03 -0800
From: syzbot <syzbot+33a04338019ac7e43a44@...kaller.appspotmail.com>
To: kartikey406@...il.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [kvm?] WARNING in kvm_gmem_fault_user_mapping

Hello,

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

------------[ cut here ]------------
!mapping_unevictable(inode->i_mapping)
WARNING: arch/x86/kvm/../../../virt/kvm/guest_memfd.c:601 at __kvm_gmem_create virt/kvm/guest_memfd.c:601 [inline], CPU#0: syz.0.17/6689
WARNING: arch/x86/kvm/../../../virt/kvm/guest_memfd.c:601 at kvm_gmem_create+0x389/0x780 virt/kvm/guest_memfd.c:644, CPU#0: syz.0.17/6689
Modules linked in:
CPU: 0 UID: 0 PID: 6689 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:__kvm_gmem_create virt/kvm/guest_memfd.c:601 [inline]
RIP: 0010:kvm_gmem_create+0x389/0x780 virt/kvm/guest_memfd.c:644
Code: 0f 85 88 03 00 00 4d 8b ad 28 01 00 00 31 ff 49 c1 ed 03 41 83 e5 01 44 89 ee e8 c2 ac 83 00 45 84 ed 75 09 e8 68 b2 83 00 90 <0f> 0b 90 e8 5f b2 83 00 49 8d bf 78 04 00 00 48 b8 00 00 00 00 00
RSP: 0018:ffffc90003f97990 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000005 RCX: ffffffff818348ee
RDX: ffff88801ebb24c0 RSI: ffffffff818348f8 RDI: ffff88801ebb24c0
RBP: ffff88805dae0000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff82711c34 R12: ffff88801ffd5d00
R13: 0000000000000000 R14: 0000000000000003 R15: ffff88806b738048
FS:  00007f124fe386c0(0000) GS:ffff8881245d9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b34963fff CR3: 000000002a3f2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 kvm_vm_ioctl+0x1109/0x4020 virt/kvm/kvm_main.c:5397
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f124ef9aeb9
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:00007f124fe38028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f124f215fa0 RCX: 00007f124ef9aeb9
RDX: 00002000000001c0 RSI: 00000000c040aed4 RDI: 0000000000000004
RBP: 00007f124f008c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f124f216038 R14: 00007f124f215fa0 R15: 00007ffc8cc39a38
 </TASK>


Tested on:

commit:         162b4244 Merge tag 'iommu-fixes-v6.19-rc7' of git://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1039bbfa580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f1fac0919970b671
dashboard link: https://syzkaller.appspot.com/bug?extid=33a04338019ac7e43a44
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch:          https://syzkaller.appspot.com/x/patch.diff?x=161ebbfa580000