linux-kernel - Re: [syzbot] [kvm?] BUG: unable to handle kernel paging request in kvm_gmem_get

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Message-ID: <aWpYK83klokXFuds@google.com>
Date: Fri, 16 Jan 2026 07:24:27 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: syzbot <syzbot+6f16df7b5a49f0e01b18@...kaller.appspotmail.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, pbonzini@...hat.com, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [kvm?] BUG: unable to handle kernel paging request in kvm_gmem_get_folio

On Fri, Jan 16, 2026, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    9b7977f9e39b Add linux-next specific files for 20260115
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=10585522580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=9c0b39f55c418575
> dashboard link: https://syzkaller.appspot.com/bug?extid=6f16df7b5a49f0e01b18
> compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/32edced7b806/disk-9b7977f9.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/dec5450e284a/vmlinux-9b7977f9.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/65783c99fb65/bzImage-9b7977f9.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+6f16df7b5a49f0e01b18@...kaller.appspotmail.com
> 
> BUG: unable to handle page fault for address: fffffffffffffffc
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD e143067 P4D e143067 PUD e145067 PMD 0 
> Oops: Oops: 0000 [#1] SMP KASAN PTI
> CPU: 0 UID: 0 PID: 10212 Comm: syz.7.1148 Tainted: G             L      syzkaller #0 PREEMPT(full) 
> Tainted: [L]=SOFTLOCKUP
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
> RIP: 0010:const_folio_flags include/linux/page-flags.h:351 [inline]
> RIP: 0010:folio_test_head include/linux/page-flags.h:844 [inline]
> RIP: 0010:folio_test_large include/linux/page-flags.h:865 [inline]
> RIP: 0010:folio_order include/linux/mm.h:1248 [inline]
> RIP: 0010:kvm_gmem_get_folio+0x12e/0x240 virt/kvm/guest_memfd.c:147

Too slow, syzbot!  https://lore.kernel.org/all/aWk9PusYNW0iADuD@google.com

#syz invalid