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=-9.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 8E679C4727C for ; Wed, 30 Sep 2020 16:31:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 12BDE2072E for ; Wed, 30 Sep 2020 16:31:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="WbG9D0/S" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731103AbgI3QbZ (ORCPT ); Wed, 30 Sep 2020 12:31:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725355AbgI3QbY (ORCPT ); Wed, 30 Sep 2020 12:31:24 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 923CCC061755 for ; Wed, 30 Sep 2020 09:31:24 -0700 (PDT) Received: from zn.tnic (p200300ec2f092a00869c7b979af15d7f.dip0.t-ipconnect.de [IPv6:2003:ec:2f09:2a00:869c:7b97:9af1:5d7f]) (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 161D51EC0445; Wed, 30 Sep 2020 18:31:23 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1601483483; 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=Dx1aQOyK27/HcHW28nNDA9Vv+UI+LGYZbrAVg6hlBNU=; b=WbG9D0/S4P0UhShhqC9MRCNUOGYilohzf2HkpJ/Alj9K8N/LHWblgOtEluODfrBPQxbPda C5L6HMe1zsOGC0yzYL14TP5RvWT9j0kMZnbgAYgYFWzg7/r4sWuITBR/8gyoJZ2JKOIKqc lKe8uDPCSIFsNes3ukIwx4aaoRje+Co= Date: Wed, 30 Sep 2020 18:31:20 +0200 From: Borislav Petkov To: Dmitry Vyukov Cc: Alexander Potapenko , Marco Elver , syzbot , Arnaldo Carvalho de Melo , Alexander Shishkin , "H. Peter Anvin" , Jiri Olsa , LKML , Mark Rutland , Ingo Molnar , Namhyung Kim , Peter Zijlstra , syzkaller-bugs , Thomas Gleixner , the arch/x86 maintainers , clang-built-linux , syzkaller Subject: Re: general protection fault in perf_misc_flags Message-ID: <20200930163120.GJ6810@zn.tnic> References: <20200928083819.GD1685@zn.tnic> <20200928085401.GE1685@zn.tnic> <20200928202353.GI1685@zn.tnic> <20200929083336.GA21110@zn.tnic> <20200930161711.GH6810@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 30, 2020 at 06:23:44PM +0200, Dmitry Vyukov wrote: > Here is the answer: > https://github.com/google/syzkaller/blob/master/tools/create-gce-image.sh#L189 > > # rodata=n: mark_rodata_ro becomes very slow with KASAN (lots of PGDs) > > I have some vague memory that there was some debug double checking > that pages are indeed read-only and that debug check was slow, but it > was always executed without rodata=n. Sounds like debug_checkwx() which is disabled by turning off CONFIG_DEBUG_WX. You could either disable it in your .configs or, provided there's even such an option, disable KASAN checking around it until that one-time boot test completes and then reenable KASAN. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette