From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5D23D2566E2 for ; Tue, 26 Aug 2025 00:40:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756168816; cv=none; b=PUzCXNrdDGUPzasUuO7QQYnGcUTMkItbjg3gXCdzCvGOhiyKk3p95fSOmzvo5GgxRRBatJk8XZW5WMNXvdCvOiTLmkJLAkYXAt0RLfkTLLlKfMrGryfD7OZ2DHuRzQmV/iKfUa7sfr9BNOMDukHhqTTYyaqgXVJWSjolCo2uomA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756168816; c=relaxed/simple; bh=OGApnXhecwv65yclankWf5l5OEJW6iLLstfxLiQxT78=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=hkdr+JdWlRN513fc4mf7N/188AL9qO0lEtzqAHnznksaHN+ciKbViEhlj52Te7jFYbxOUtYgzfB9qOXhmLt8lXN0hF360vqh4Zxm3GDSoOGYKjgYgGRzgK0KwC6dIy86jRpjHu70k3GgPhBBJIyZTRKFB7t27XFJMObpDC3cJ9Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=wnA9yR0o; arc=none smtp.client-ip=209.85.216.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="wnA9yR0o" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-323766e64d5so5234799a91.0 for ; Mon, 25 Aug 2025 17:40:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1756168814; x=1756773614; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:reply-to:from:to:cc :subject:date:message-id:reply-to; bh=BGFfEAOpmCnYuTpD1Fkefs/dVeGZ0wTmpw3Bli3LbeI=; b=wnA9yR0o3Zao4cmij5KpH31jEUNmW3Z3vb6s1D/e57RQBf6J7qhRVeiYZtgRhrmBJX ptg07/T3KbOGlTbbSZttzE6qmKX6BRZGjwwV+my+bWtdSAnQQv8SofFczHW+u3MgYNEZ bul7mDBV1lkjM4wSTHFlJUjzFIGvoqDcjc38v6cnoH319TrzIAfeZ8oN7XmwpNwFcqZO Z5/Oa8S9cbAFJSMR9ByE+yjtBjUqnBBOVisGUzDbG0zgZLxXHu4HwfGxiWfUwQMEUyhF LOOXmrNH9/RK1eOGY8y5xBSbwl2RS8wypLV2EEj+EZvwslg0oIVNGQfv58zGR8JHPGTR FZQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1756168814; x=1756773614; h=cc:to:from:subject:message-id:mime-version:date:reply-to :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=BGFfEAOpmCnYuTpD1Fkefs/dVeGZ0wTmpw3Bli3LbeI=; b=Q7097fXS/SkPT/ohFwVNqq1HKuxkA7dEKVq5g3ywyzAJnJPxv/HSmsOD/FCYJ8Cfrt ZPKcziWwI0utnJM+ypbQ/Jam0fk5fWbDpwLM9drO0nh1Fmn9zdkQh5/gDYhjSdTUe3FP p+q7Jf6oP28HN4cTI5CoaUux6txH9JQMQdt0EEQ2v8fheWjsengsrEJA8qUW3WZJvMbj umwjCDDZ8pSJd6QTsIeKWQmhTELlw0Mlp8giN9wzFJTNSRQuBtW+xlpI7Enxit9tjsNJ b7gBT9DOnhYXH5njYhnR/2gMiskAxdHfeRAwsI1MOH6r2rls9+ozNgERp+0/a1VUKhfF 0OnQ== X-Forwarded-Encrypted: i=1; AJvYcCXmCzMKWPaGD6GpH8YpCT8YzBeLo3eX3F/FkePR8OinqVBl0JWjAheg+BMCo5iTIWjmnbThK4bj1nx4b+E=@vger.kernel.org X-Gm-Message-State: AOJu0Yyp6/vUWIdYMe+Z32Jm2LpIwDMEcOa2t4IrEGzKG8euup/Od0Y3 EBk+cLwiUZDiISbrpxZL7CXhY6qODS75DqzBYhAMeezhcmQopr6Kl3t+AsNSn+lpd9NcQxjd8wp lO6mDiw== X-Google-Smtp-Source: AGHT+IHK1NCtVV/uARgx2pzXRzDVXR83QkBAFqL6vl11EOqC5SFFLlVBCFYJmnq5S7TIzbHzRbowBd1bBwU= X-Received: from pjbqc3.prod.google.com ([2002:a17:90b:2883:b0:312:dbc:f731]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:2811:b0:323:7df8:6eec with SMTP id 98e67ed59e1d1-3274620a008mr515983a91.18.1756168814547; Mon, 25 Aug 2025 17:40:14 -0700 (PDT) Reply-To: Sean Christopherson Date: Mon, 25 Aug 2025 17:40:08 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.51.0.261.g7ce5a0a67e-goog Message-ID: <20250826004012.3835150-1-seanjc@google.com> Subject: [PATCH 0/3] vhost_task: KVM: Fix a race where KVM wakes an exited task From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini , "Michael S. Tsirkin" , Jason Wang Cc: kvm@vger.kernel.org, virtualization@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Sebastian Andrzej Siewior Content-Type: text/plain; charset="UTF-8" Fix a bug where KVM attempts to wake a vhost task that has already exited in response to a fatal signal, and tack on a few cleanups to harden against introducing similar bugs in the future. Somehow, this only started causing problems when commit 56180dd20c19 ("futex: Use RCU-based per-CPU reference counting instead of rcuref_t") landed. I have no idea why the futex changes exposed the bug, and I don't care all that much, as this is firmly a KVM bug. Sean Christopherson (3): vhost_task: KVM: Don't wake KVM x86's recovery thread if vhost task was killed vhost_task: Allow caller to omit handle_sigkill() callback KVM: x86/mmu: Don't register a sigkill callback for NX hugepage recovery tasks arch/x86/kvm/mmu/mmu.c | 9 ++---- include/linux/sched/vhost_task.h | 1 + kernel/vhost_task.c | 52 +++++++++++++++++++++++++++++--- 3 files changed, 51 insertions(+), 11 deletions(-) base-commit: 1b237f190eb3d36f52dffe07a40b5eb210280e00 -- 2.51.0.261.g7ce5a0a67e-goog