Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750991AbdIITV3 (ORCPT ); Sat, 9 Sep 2017 15:21:29 -0400 Received: from mail-io0-f181.google.com ([209.85.223.181]:37579 "EHLO mail-io0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750759AbdIITV1 (ORCPT ); Sat, 9 Sep 2017 15:21:27 -0400 X-Google-Smtp-Source: AOwi7QCdNRkBbwSvFb6FO/Fx+1bzZqSJJV9uARjSNrIE89Ni8FfrLY1HR6KKDguXNxRtfUlEadsTO+tmM0X6mx4xL/4= MIME-Version: 1.0 In-Reply-To: <20170909190948.xydyega7i2rjnlqt@pd.tnic> References: <20170909143335.ja2iwjsbeyfxz4ez@pd.tnic> <20170909144350.GA290@x4> <20170909163225.GA290@x4> <20170909170537.6xmxtzwripplhhwi@pd.tnic> <20170909172352.GA290@x4> <20170909173633.4ttfk7maooxkcwum@pd.tnic> <20170909181445.GA281@x4> <20170909182952.itqad4ryngjwrgqf@pd.tnic> <20170909190948.xydyega7i2rjnlqt@pd.tnic> From: Linus Torvalds Date: Sat, 9 Sep 2017 12:21:26 -0700 X-Google-Sender-Auth: A9NEu7JovsFVNKIJnEc7qJkVy9I Message-ID: Subject: Re: Current mainline git (24e700e291d52bd2) hangs when building e.g. perf To: Borislav Petkov Cc: Markus Trippelsdorf , Andy Lutomirski , Ingo Molnar , Thomas Gleixner , Peter Zijlstra , LKML , Ingo Molnar , Tom Lendacky Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 354 Lines: 11 On Sat, Sep 9, 2017 at 12:09 PM, Borislav Petkov wrote: > > Yeah, but we can't know what kind of speculative accesses happen between > the removal from the mask and the actual flushing. Indeed. The speculative kernel thread accesses while lazy could easily trigger this. And I guess those are pretty fundamental. So.. Linus