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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 37D3EC43381 for ; Tue, 26 Feb 2019 11:54:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 07FF52184C for ; Tue, 26 Feb 2019 11:54:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="PVRV37hC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726677AbfBZLy4 (ORCPT ); Tue, 26 Feb 2019 06:54:56 -0500 Received: from merlin.infradead.org ([205.233.59.134]:50434 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726222AbfBZLy4 (ORCPT ); Tue, 26 Feb 2019 06:54:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=v1NghnbTc7nCBxsYLExPUSuTxF3czfiFYG6o86E+sBE=; b=PVRV37hC+ztimpKp5Np2GaihJ rq/e2LfehYfF+HY/5y11br2t8TWS0BAK/yh3NutRwaRn3MG/FZLgx/rrSA+2HdH88fnV5nTTtSBCC gItRF6omahT1GM5WWyj2jepRND+hglxuXSWG6/iPURwsq3J3C15EZ86bQFlJIzfdeIa5Z06HT9o5X 6OqP98p9hkHjWR1gy6ghIF3sU16moG7477A73kRwAy18K1QQu9ZPw3emsBfVeiTGki8nuFCwnChr1 9I4TLrcBbB6EMFz9INtIZpnX2DZtuOIn7a8DI75dSXHHIy7pyq8s4a51rUim0RxFgC1Dbu1tLm3k3 pYWmqEc7w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gybJt-0005Eb-5C; Tue, 26 Feb 2019 11:54:45 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id B1E6520269AFC; Tue, 26 Feb 2019 12:54:41 +0100 (CET) Date: Tue, 26 Feb 2019 12:54:41 +0100 From: Peter Zijlstra To: Olof Johansson Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , x86@kernel.org, Linux Kernel Mailing List Subject: Re: [PATCH] x86/nmi: ratelimit unknown nmi logs Message-ID: <20190226115441.GT32477@hirez.programming.kicks-ass.net> References: <20190220014836.20510-1-olof@lixom.net> <20190220085947.GA17969@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii 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 20, 2019 at 10:00:28AM -0800, Olof Johansson wrote: > On Wed, Feb 20, 2019 at 12:59 AM Peter Zijlstra wrote: > > > > On Tue, Feb 19, 2019 at 05:48:36PM -0800, Olof Johansson wrote: > > > Getting notified of unknown NMIs is obviously important, but getting > > > notified on every single one, especially on larger systems with slow > > > (serial) console causes more harm than good when it's a known noisy > > > non-relevant event. > > > > > > So, let's ratelimit to avoid locking up the system. > > > > What kind of bonghit broken crap system is that? Still interested to know what system and why this happens. > > That is; this _really_ should not happen, and this is a bandaid, not > > fixing the cause. > > Oh, I agree -- this shouldn't happen, and it's being debugged and fixed. > > So, I'm not looking at this as a bandaid to the real problem, but > there's also no reason to DoS the system with prink when it does > occur. If you want to configure the system to panic on unknown NMI > there are already hooks for it. > > I'm obviously happy to carry local patches for this, since it's a > temporary problem. But yet again, I don't see a reason to have the > kernel run off the rails for this condition. Fair enough I suppose. Personally I don't care either way; you could just boot without the slow serial in order to install a new kernel.