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[209.85.220.65]) by mx.google.com with SMTPS id 7sor4184680itl.35.2019.03.20.06.59.31 for (Google Transport Security); Wed, 20 Mar 2019 06:59:31 -0700 (PDT) Received-SPF: pass (google.com: domain of dvyukov@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=N342nwjK; spf=pass (google.com: domain of dvyukov@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dvyukov@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com 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=RmyQwrFyANnSrcI13I0okPnI4JkfyNY2bxu3oBrzm78=; b=N342nwjKC9kyYqwey8dFejLjpIkuXozr0myM+P8RkqmPaV7dCdfBDx2pJgzdacZXYh sdRgK9YZNmvOf0NM8s5KID3i1mF06uQS/AZ/mijuKM0nDEc39KKyK2nHX7eo0QhLu20N N0LtP3Ph+8fa3PcMZ+s3o8yZnOf03A0ZHVSy1XkYyvnsQLNhqCE7ue0fbROaiFJ4tEpM Zdqwkxs4WvURgbd+NdTmakQwU/g3XSnti2C1Vrz8RL1uoPz0qxBId4DyRRcyokopoAVY Lyy+dmy6ZHP7719ZexaUn+i9Lc3QUi+utZIWGGhoEPdPrb2usUFyYbs5oqgq3dFtokXz vkHA== X-Google-Smtp-Source: APXvYqzmn4bsPUjYN021O9lPARoRSqq2hf2Uw0i66O47FvP6bUygASSf2713Fh5nTZ9abgbg96YVy3cVWltNfiB6YZA= X-Received: by 2002:a24:3281:: with SMTP id j123mr1444952ita.166.1553090370724; Wed, 20 Mar 2019 06:59:30 -0700 (PDT) MIME-Version: 1.0 References: <000000000000db3d130584506672@google.com> <426293c3-bf63-88ad-06fb-83927ab0d7c0@I-love.SAKURA.ne.jp> In-Reply-To: From: Dmitry Vyukov Date: Wed, 20 Mar 2019 14:59:19 +0100 Message-ID: Subject: Re: kernel panic: corrupted stack end in wb_workfn To: Tetsuo Handa Cc: Andrey Ryabinin , syzbot , Andrew Morton , Qian Cai , David Miller , guro@fb.com, Johannes Weiner , Josef Bacik , Kirill Tkhai , LKML , Linux-MM , linux-sctp@vger.kernel.org, Mel Gorman , Michal Hocko , netdev , Neil Horman , Shakeel Butt , syzkaller-bugs , Al Viro , Vladislav Yasevich , Matthew Wilcox , Xin Long Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Mar 20, 2019 at 11:59 AM Tetsuo Handa wrote: > > On 2019/03/20 19:42, Dmitry Vyukov wrote: > >> I mean, yes, I agree, kernel bug bisection won't be perfect. But do > >> you see anything actionable here? > > Allow users to manually tell bisection range when > automatic bisection found a wrong commit. > > Also, allow users to specify reproducer program > when automatic bisection found a wrong commit. > > Yes, this is anti automation. But since automation can't become perfect, > I'm suggesting manual adjustment. Even if we involve manual adjustment, > the syzbot's plenty CPU resources for building/testing kernels is highly > appreciated (compared to doing manual bisection by building/testing kernels > on personal PC environments). FTR: provided an extended answer here: https://groups.google.com/d/msg/syzkaller-bugs/1BSkmb_fawo/DOcDxv_KAgAJ > > I see the larger long term bisection quality improvement (for syzbot > > and for everybody else) in doing some actual testing for each kernel > > commit before it's being merged into any kernel tree, so that we have > > less of these a single program triggers 3 different bugs, stray > > unrelated bugs, broken release boots, etc. I don't see how reliable > > bisection is possible without that. > > > > syzbot currently cannot test kernels with custom patches (unless "#syz test:" requests). > Are you saying that syzbot will become be able to test kernels with custom patches? I mean if we start improving kernel quality over time so that we have less of these a single program triggers 3 different bugs, stray unrelated bugs, broken release boots, etc, it will improve bisection quality for everybody (beside being hugely useful in itself).