From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8FFC8C43387 for ; Fri, 11 Jan 2019 17:37:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 620E820870 for ; Fri, 11 Jan 2019 17:37:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="RblCAEjI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731304AbfAKRg7 (ORCPT ); Fri, 11 Jan 2019 12:36:59 -0500 Received: from mail.skyhub.de ([5.9.137.197]:50406 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725805AbfAKRg6 (ORCPT ); Fri, 11 Jan 2019 12:36:58 -0500 Received: from zn.tnic (p200300EC2BCAC5003956DFF8679C923C.dip0.t-ipconnect.de [IPv6:2003:ec:2bca:c500:3956:dff8:679c:923c]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 8C4101EC0432; Fri, 11 Jan 2019 18:36:57 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1547228217; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=+CCqKfeR1VAuRhQk8t21C6yoxZes1BsouZ93Be7mIDo=; b=RblCAEjIV05bLQEJHC1f4m1muAVxkkdRYGbowGCGbzPtRB/kwtDpdUS7XkYSGIqUTK2ohe GjKU0tSHh9/5sgod9HaWtx9rf7JBfopMkUudqzzK0urpvKWsW+8W1V44Zokh6hA0Yx9oO7 9LHGuRMR/320paSXcj6DAPDVUOB6XSI= Date: Fri, 11 Jan 2019 18:36:48 +0100 From: Borislav Petkov To: Peter Zijlstra Cc: Zhenzhong Duan , Waiman Long , LKML , SRINIVAS Subject: Re: Question about qspinlock nest Message-ID: <20190111173648.GH4729@zn.tnic> References: <910e9fb6-d0df-4711-fe2b-244b3c20eb82@redhat.com> <2eca6f60-3e8b-a389-27cb-8adbd9676607@oracle.com> <20190111091638.GK30894@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190111091638.GK30894@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 11, 2019 at 10:16:38AM +0100, Peter Zijlstra wrote: > > Not for debug exception, for MCE exception handler I found below two: > > > > do_machine_check->mce_report_event->schedule_work That has been the case at least since 2009. We probably never hit it or I've never seen a deadlock caused by it. > > do_machine_check->force_sig->force_sig_info This does: ist_begin_non_atomic(regs); local_irq_enable(); before forcing the signal. And there's blurb above ist_begin_non_atomic() why it is OK to schedule when the exception came from usermode. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.