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AKwUvBxCr+3eE525DvMA2zTB/TJYAiqJAaXJoOnjWtAgfm+Y0nrVpU62RtMSXghubzA/qfaRN2DyzF8A5JYQl2s=@vger.kernel.org X-Gm-Message-State: AFuF++lDpJR1Pj4E2FiFICNMh+WAvOI3l1KRIPcA4OwzzYPbej7HHkkf 4YPzDHW7NsKz7Z1LaYD5oZndlRmkntn+bJWxXZyvaJNDzpz2F7M+3V9c2lAiHAlfMigCc7LvaKM zzHqPAA== X-Received: from pgp20-n1.prod.google.com ([2002:a05:6a02:62d4:10b0:cc7:9e1d:7d45]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:1014:b0:3dd:a006:7b31 with SMTP id adf61e73a8af0-3e1247894f7mr1269961637.48.1791293852598; Tue, 06 Oct 2026 06:37:32 -0700 (PDT) Date: Tue, 6 Oct 2026 06:37:31 -0700 In-Reply-To: <6ac316c7.01314a6c.556a8.000d.GAE@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <6ac316c7.01314a6c.556a8.000d.GAE@google.com> Message-ID: Subject: Re: [syzbot] [kvm?] WARNING in kvm_vcpu_pre_fault_memory From: Sean Christopherson To: syzbot Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, pbonzini@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="us-ascii" On Sun, Oct 04, 2026, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: ce1e0223d8ad Merge tag 'devicetree-fixes-for-7.3-2' of git.. > git tree: upstream > console+strace: https://syzkaller.appspot.com/x/log.txt?x=1353dbf5580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=9d4242cb1c54cdf7 > dashboard link: https://syzkaller.appspot.com/bug?extid=db7bd0f41c2a7e82d4ba > compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14cdf6c9580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12cdf6c9580000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/217b0c1b14ee/disk-ce1e0223.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/335343cc5803/vmlinux-ce1e0223.xz > kernel image: https://storage.googleapis.com/syzbot-assets/760ef2f39df0/bzImage-ce1e0223.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+db7bd0f41c2a7e82d4ba@syzkaller.appspotmail.com > > ------------[ cut here ]------------ > r == 0 || r == -EIO > WARNING: arch/x86/kvm/../../../virt/kvm/kvm_main.c:4389 at kvm_vcpu_pre_fault_memory+0x45d/0x470 virt/kvm/kvm_main.c:4389, CPU#1: syz-executor267/8523 > Modules linked in: > CPU: 1 UID: 0 PID: 8523 Comm: syz-executor267 Not tainted syzkaller #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 > RIP: 0010:kvm_vcpu_pre_fault_memory+0x45d/0x470 virt/kvm/kvm_main.c:4389 > Code: fe ff ff e8 85 2e 88 00 90 0f 0b 90 e9 0d ff ff ff e8 77 2e 88 00 e8 42 85 f3 ff eb 8f e8 6b 2e 88 00 eb 05 e8 64 2e 88 00 90 <0f> 0b 90 e9 a7 fe ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 > RSP: 0018:ffffc900024dfc28 EFLAGS: 00010293 > RAX: ffffffff813fe025 RBX: ffffc900024dfe00 RCX: ffff88807fcc0000 > RDX: 0000000000000000 RSI: ffffffff8eaf6510 RDI: fffffffffffffffb > RBP: dffffc0000000000 R08: ffff88807fcc0000 R09: 0000000000000002 > R10: fffffffffffffffb R11: 0000000000000000 R12: ffffc900024dfe00 > R13: ffff88807fcc0000 R14: 1ffff1100ff98000 R15: fffffffffffffffb > FS: 00007f9c411186c0(0000) GS:ffff888124dc7000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f9c4116312d CR3: 0000000026a4a000 CR4: 00000000003526f0 > Call Trace: > > kvm_vcpu_ioctl+0x8a6/0xfd0 virt/kvm/kvm_main.c:4668 > 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:61 [inline] > do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f9c4118db49 > Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d0 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007f9c411181d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 00007f9c4123bb88 RCX: 00007f9c4118db49 > RDX: 0000200000000100 RSI: 00000000c040aed5 RDI: 0000000000000005 > RBP: 00007f9c4123bb80 R08: 38203a6b63617473 R09: 38203a6b63617473 > R10: 38203a6b63617473 R11: 0000000000000246 R12: 00007f9c4120b858 > R13: 0000200000000118 R14: 0000200000000100 R15: 0000200000000600 > #syz test diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 108d42c5c1d6..31aba0c6f883 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4386,10 +4386,7 @@ static int kvm_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu, } r = kvm_arch_vcpu_pre_fault_memory(vcpu, range); - if (WARN_ON_ONCE(r == 0 || r == -EIO)) - break; - - if (r < 0) + if (WARN_ON_ONCE(!r) || r < 0) break; range->size -= r;