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=-18.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL 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 3C139C433E0 for ; Thu, 18 Mar 2021 08:34:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F121064E0C for ; Thu, 18 Mar 2021 08:34:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229708AbhCRId3 (ORCPT ); Thu, 18 Mar 2021 04:33:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34086 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229512AbhCRIdE (ORCPT ); Thu, 18 Mar 2021 04:33:04 -0400 Received: from mail-qk1-x729.google.com (mail-qk1-x729.google.com [IPv6:2607:f8b0:4864:20::729]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF4EBC06174A for ; Thu, 18 Mar 2021 01:33:03 -0700 (PDT) Received: by mail-qk1-x729.google.com with SMTP id f124so1203074qkj.5 for ; Thu, 18 Mar 2021 01:33:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=iEev52rWGRb+H14tkihKM80QH51NH2IA18V5Wly4ffE=; b=GOZ4AHjvee8ebwihZyOxSoVyL1VXcoIY7SrqjQ3fGJ2psoj+OKQGpk2oGcMVpRoc/M m3kagdaoTzyKEkjESDCbIr6NxxVYvq2YMP0jQxxs4fDVZi2jOfYtUjD0E3dPb7t08gJu HUFxeBeu8iwUKOeJfZGW9z9gTckIxNyCNjtHhO9pdMEBpURzHafcyby/MBMPvMrnHHI/ dVLAK4t2AXYx7vM53A205RBi5Hz0MXYgHsXBmaKVIuTyASKbdUIBEbD1nv14ZTnkIfnB ncTXV2liC/A73r4oimNS466wHa0IfGmDuEisub7nXLEBri1s8Lo4fUl1b+knRd7HfgYj Zr3A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=iEev52rWGRb+H14tkihKM80QH51NH2IA18V5Wly4ffE=; b=ildbcEiBiCiO+tLds4vcmmsh0MBtIKPAlQBfaqxIGRv3VQaz8+4gRIFbEkzqp4mZou u3YT5ztJ7gbqT1mUgfzZozInoB5A8T6Fr9ba0V/M37uJto0Lrc4MQd2o2XaLb1+H+1I8 N0fIlY6bAkp+6TkwhZeyDue5v1ZvFIeT6iPO1mRjwnSlv+i+yuHKJHFQKph47s3l7HNx oE4WQ4YPJTY0R/P0l6wZNxv/ByntWdta0b6R9TVRkTkIMPL/psiAZ4g6hKR1n7UVcjg8 OhlcKj10WKtQgJtaCrDrA5aujXazQhVtGgr7mlj1nLyfeajdS0VY+XYtJnK6w95MtZtK ydgg== X-Gm-Message-State: AOAM532UY6OQWXhKGSDP/RzXYTrGPlh8b7q11naPM19fYR8PseYXbZYx 83mgA8WUm9jLx4JKU4WVNL3CUWMFKt+nZZXpdqqXdw== X-Google-Smtp-Source: ABdhPJyd/l1rc1ltx2W/w7dBCyPt70y35W4uD9UlIH5yNvw16G2OdFapDJ1ECXfO7EZfdXJ4nRKHYmnERa+cnUybbQ0= X-Received: by 2002:a05:620a:981:: with SMTP id x1mr3042928qkx.501.1616056382595; Thu, 18 Mar 2021 01:33:02 -0700 (PDT) MIME-Version: 1.0 References: <20210311123315.GF37303@C02TD0UTHF1T.local> <20210317184538.GB2508@C02TD0UTHF1T.local> In-Reply-To: <20210317184538.GB2508@C02TD0UTHF1T.local> From: Dmitry Vyukov Date: Thu, 18 Mar 2021 09:32:51 +0100 Message-ID: Subject: Re: arm64 syzbot instances To: Mark Rutland Cc: Marc Zyngier , Will Deacon , Ard Biesheuvel , Linux ARM , Arnd Bergmann , syzkaller , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 17, 2021 at 7:45 PM Mark Rutland wrote: > > On Thu, Mar 11, 2021 at 05:56:46PM +0100, Dmitry Vyukov wrote: > > On Thu, Mar 11, 2021 at 1:33 PM Mark Rutland wrote: > > > FWIW, I keep my fuzzing config fragment in my fuzzing/* branches on > > > git.kernel.org, and for comparison my fragment for v5.12-rc1 is: > > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/commit/?h=fuzzing/5.12-rc1&id=6d9f7f8a2514fe882823fadbe7478228f71d7ab1 > > > > > > ... I'm not sure whether there's anything in that which is novel to you. > > > > Hi Mark, > > > > I've learned about DEBUG_TIMEKEEPING which we had disabled. I am enabling it. > > We also have CONTEXT_TRACKING_FORCE disabled. I don't completely > > understand what it's doing. Is it also "more debug checks" type of > > config? > > Context tracking tracks user<->kernel transitions, and tries to disable > RCU when it is not needed (e.g. while a CPU is in usersspace), to avoid > the need to perturb that CPU with IPIs and so on. Normally this is not > enabled unless CPUs are set aside for NOHZ usage, as there's some > expense in doing this tracking. I haven't measured how expensive it is > in practice. > > CONTEXT_TRACKING_FORCE enables that tracking regardless of whether any > CPUs are set aside for NOHZ usage, and makes it easier to find bugs in > that tracking code, or where it is not being used correctly (e.g. missed > calls, or called in the wrong places). > > I added it to my debug fragment back when I fixed the arm64 entry code > accounting for lockdep, and I keep it around to make sure that we don't > accidentally regress any of that. Looks like a debug config we should enable on syzbot. I am enabling it in: https://github.com/google/syzkaller/pull/2500/commits/8ebea47133e458293e3c71e1189e18052286393d Thanks > > FWIW we have more debug configs: > > https://github.com/google/syzkaller/blob/master/dashboard/config/linux/bits/debug.yml > > https://github.com/google/syzkaller/blob/master/dashboard/config/linux/bits/base.yml > > https://github.com/google/syzkaller/blob/master/dashboard/config/linux/bits/kasan.yml > > https://github.com/google/syzkaller/blob/master/dashboard/config/linux/bits/kmemleak.yml