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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 7E66AC34056 for ; Wed, 19 Feb 2020 17:42:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 57ED02465D for ; Wed, 19 Feb 2020 17:42:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="cZiQCPVU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726725AbgBSRmc (ORCPT ); Wed, 19 Feb 2020 12:42:32 -0500 Received: from mail.skyhub.de ([5.9.137.197]:33670 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726518AbgBSRmc (ORCPT ); Wed, 19 Feb 2020 12:42:32 -0500 Received: from zn.tnic (p200300EC2F095500C57DC876B1A4488F.dip0.t-ipconnect.de [IPv6:2003:ec:2f09:5500:c57d:c876:b1a4:488f]) (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 9FFFF1EC0591; Wed, 19 Feb 2020 18:42:30 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1582134150; 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=DpvCtMjqcX25XbMiHHt7/X8aEcXXE9Ghl88YlkXaLKo=; b=cZiQCPVUp+LrsSX1QyqrebwJk24EqpWZK+j7W+aJxC8JJ1UoTV5ioerAUuCl7iI1p2CQ/k vQfI+wh/l37W+kADEV+CXvgpbnqMlhoNanR//2X50YNLOLzAiWRVfAYKjTDtCHAKBs3tis Hmrq69Zv7llUJmARUzJoTwtkd6FarZk= Date: Wed, 19 Feb 2020 18:42:23 +0100 From: Borislav Petkov To: Andy Lutomirski Cc: Peter Zijlstra , LKML , linux-arch , Steven Rostedt , Ingo Molnar , Joel Fernandes , Greg KH , gustavo@embeddedor.com, Thomas Gleixner , paulmck@kernel.org, Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Tony Luck , Frederic Weisbecker , Dan Carpenter , Masami Hiramatsu Subject: Re: [PATCH v3 02/22] x86,mce: Delete ist_begin_non_atomic() Message-ID: <20200219174223.GE30966@zn.tnic> References: <20200219144724.800607165@infradead.org> <20200219150744.488895196@infradead.org> <20200219171309.GC32346@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: 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 Wed, Feb 19, 2020 at 09:21:48AM -0800, Andy Lutomirski wrote: > Unless there is a signal pending and the signal setup code is about to > hit the same failed memory. I suppose we can just treat cases like > this as "oh well, time to kill the whole system". > > But we should genuinely agree that we're okay with deferring this handling. Good catch! static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags) { ... /* deal with pending signal delivery */ if (cached_flags & _TIF_SIGPENDING) do_signal(regs); if (cached_flags & _TIF_NOTIFY_RESUME) { clear_thread_flag(TIF_NOTIFY_RESUME); tracehook_notify_resume(regs); rseq_handle_notify_resume(NULL, regs); } Err, can we make task_work run before we handle signals? Or there's a reason it is run in this order? Comment over task_work_add() says: * This is like the signal handler which runs in kernel mode, but it doesn't * try to wake up the @task. which sounds to me like this should really run before the signal handlers... -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette