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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 2EA3DC433DF for ; Fri, 5 Jun 2020 14:06:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 029FA2074B for ; Fri, 5 Jun 2020 14:06:37 +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="24/s0S78" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727915AbgFEOGg (ORCPT ); Fri, 5 Jun 2020 10:06:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726553AbgFEOGd (ORCPT ); Fri, 5 Jun 2020 10:06:33 -0400 Received: from merlin.infradead.org (unknown [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8E6F8C08C5C2 for ; Fri, 5 Jun 2020 07:06:33 -0700 (PDT) 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; bh=3646+nLfQNB1TESO4RVGCLY9LYs5rMvIB3rw1pnYSU8=; b=24/s0S7879gySR/FmN/u7FND91 f1N7ToulvAIFplRet12L9lK1cliyd4euZm6tTDUazi8qkZrpHzjtya4OvCdBkYOY+K+I/IDb/WcLZ MY5l7iaVCUbtctX2cg59+ZfrRlI3xBYajFLmhMwG4m1y/iyMl/yL5Q4WrzcTjqOU69i/IMqex0b4A +icQc/XM37OL/4GshMXhxYflgQLSXEceptaBxryvYbmF98Pk70pWycXYAcbS43usFWbJkcXbTJJ+Q p6YfrhxfgMSPpCy4TC/Cp+pHIAzD6fqdcBeutmyfgDm2YYHk2IyN+1JQsH1r+sGgzKQcc1l3kk8jZ takv0BLQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jhCyN-0002yk-5a; Fri, 05 Jun 2020 14:05:27 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id F2F6D301ABC; Fri, 5 Jun 2020 16:05:21 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CCAA821A74B45; Fri, 5 Jun 2020 16:05:21 +0200 (CEST) Date: Fri, 5 Jun 2020 16:05:21 +0200 From: Peter Zijlstra To: Eric Dumazet Cc: kernel test robot , Yuqi Jin , "David S. Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , Jakub Kicinski , Jiri Pirko , Arvind Sankar , Jiong Wang , Shaokun Zhang , LKML , lkp@lists.01.org Subject: Re: [net] a6211caa63: dmesg.UBSAN:signed-integer-overflow_in_arch/x86/include/asm/atomic.h Message-ID: <20200605140521.GD4117@hirez.programming.kicks-ass.net> References: <20200605080929.GK12456@shao2-debian> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 05, 2020 at 06:17:51AM -0700, Eric Dumazet wrote: > On Fri, Jun 5, 2020 at 1:10 AM kernel test robot wrote: > There you go. > > We decided this was a bogus report, and that UBSAN requires sane compilers. > > Please read the fine comment that was added in this commit and update > your compiler or do not mess with compiler flags. > > + /* If UBSAN reports an error there, please make sure your compiler > + * supports -fno-strict-overflow before reporting it that was a bug > + * in UBSAN, and it has been fixed in GCC-8. > + */ > + return atomic_add_return(segs + delta, p_id) - segs; > > make HOSTCC=gcc-4.9 CC=gcc-4.9 ARCH=i386 olddefconfig prepare modules_prepare bzImage Rong, can you make sure to exclude gcc<8 for UBSAN reports ?