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=-8.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, 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 AEA88C43387 for ; Mon, 31 Dec 2018 08:24:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7F4AD20B1F for ; Mon, 31 Dec 2018 08:24:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="lL9PqDvS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727112AbeLaIYa (ORCPT ); Mon, 31 Dec 2018 03:24:30 -0500 Received: from mail-it1-f196.google.com ([209.85.166.196]:52003 "EHLO mail-it1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726033AbeLaIY3 (ORCPT ); Mon, 31 Dec 2018 03:24:29 -0500 Received: by mail-it1-f196.google.com with SMTP id w18so35213422ite.1 for ; Mon, 31 Dec 2018 00:24:28 -0800 (PST) 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=x/dJbjiOAY3ymU6pajADp9+hSys+HJ1L9NBPmb3INQs=; b=lL9PqDvSoOx02XKuKc4YXYvZEjuWMuahfKL9/Xlz+0U/k9gTkaDk+cOWtoH04IgSmI 6+tiQ+AC5KSIHUJhvxrLuW51jmhUH/fp2d6d2IdQqYmm7tzVKr+uUTGPjrm2BxV9mxgx U5XykdJaTfL4SbVPowXm1de5Add8k69pE+f1VJEf3jVHdF9CWVnkAhzrkL5S07Hk7qZS 0VKs3/9VHcOojv1drHai35XhpBT3rppyZakSOnZ16wmPCBPCw4S3J6YiJXoFP4nYoj3f izS9l3vG2opYLcvP8qVG/JCooLA5ZOCLL3mvAUeYr7rfOtsRodvRuqV8QHrc0vfnpbmI aUpw== 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=x/dJbjiOAY3ymU6pajADp9+hSys+HJ1L9NBPmb3INQs=; b=WFBQy87QaHvYhk2triAV3PJghegxjQw/9cSsGW+gasZERvxGH1vmg5DFtiaenPmQbo R25jDK968Or4wyarmbC3X/ROTubKvakcgXtZrB1SPoMJk2N5fcfrIQugZxk+SmBZ5ZMY wn0FveL2X0FJ08v1ydp3Ag8gHXS+vietzfeKR2omDu73YsdBeRWlPkiWdVkpDPnY3Rcs K/3BdAQN8EEHfZ8mpbirXYaokTXdQ7vcs4kjJprCZvxOB1SraCUMF3d1ajFq3232UEQq exOkpueMJsybtaOESZSOauLS+zCzi5vc+7JaHeIvrO2azgfnv5Y9Av7XHCgEUGK0QxUg 9xJQ== X-Gm-Message-State: AJcUukd63psQEvSNjL9K0CKtTfjdIZ+ZYQ5Ek/qjunSiY6JBSL599HBs vKEdYu5TAxZkT/Xp2q9QdrTFGGA3+tNfI24KZ/pGNQ== X-Google-Smtp-Source: AFSGD/WAXRR32TGOAsq8ckXtNG4WI9cS6EgN+hAJoP8QpGjd2i1aJD1h4MIBx0fPKKhWRr2JmBQqnyNtZYsKApO51K0= X-Received: by 2002:a05:660c:f94:: with SMTP id x20mr20595383itl.144.1546244667674; Mon, 31 Dec 2018 00:24:27 -0800 (PST) MIME-Version: 1.0 References: <0000000000007beca9057e4c8c14@google.com> In-Reply-To: From: Dmitry Vyukov Date: Mon, 31 Dec 2018 09:24:16 +0100 Message-ID: Subject: Re: INFO: rcu detected stall in ndisc_alloc_skb To: Tetsuo Handa Cc: syzbot , David Miller , Alexey Kuznetsov , LKML , netdev , syzkaller-bugs , Hideaki YOSHIFUJI , Linux-MM Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 31, 2018 at 9:17 AM Tetsuo Handa wrote: > > On 2018/12/31 16:49, Dmitry Vyukov wrote: > > On Mon, Dec 31, 2018 at 8:42 AM syzbot > > wrote: > >> > >> Hello, > >> > >> syzbot found the following crash on: > >> > >> HEAD commit: ef4ab8447aa2 selftests: bpf: install script with_addr.sh > >> git tree: bpf-next > >> console output: https://syzkaller.appspot.com/x/log.txt?x=14a28b6e400000 > >> kernel config: https://syzkaller.appspot.com/x/.config?x=7e7e2279c0020d5f > >> dashboard link: https://syzkaller.appspot.com/bug?extid=ea7d9cb314b4ab49a18a > >> compiler: gcc (GCC) 8.0.1 20180413 (experimental) > >> > >> Unfortunately, I don't have any reproducer for this crash yet. > >> > >> IMPORTANT: if you fix the bug, please add the following tag to the commit: > >> Reported-by: syzbot+ea7d9cb314b4ab49a18a@syzkaller.appspotmail.com > > > > Since this involves OOMs and looks like a one-off induced memory corruption: > > > > #syz dup: kernel panic: corrupted stack end in wb_workfn > > > > Why? > > RCU stall in this case is likely to be latency caused by flooding of printk(). Just a hypothesis. OOMs lead to arbitrary memory corruptions, so can cause stalls as well. But can be what you said too. I just thought that cleaner dashboard is more useful than a large assorted pile of crashes. If you think it's actionable in some way, feel free to undup. 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=-8.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,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 22CC8C43387 for ; Mon, 31 Dec 2018 08:24:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CBEF320B1F for ; Mon, 31 Dec 2018 08:24:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="lL9PqDvS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CBEF320B1F Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3A1D08E0087; Mon, 31 Dec 2018 03:24:29 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 350998E005B; Mon, 31 Dec 2018 03:24:29 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 23EAB8E0087; Mon, 31 Dec 2018 03:24:29 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from mail-io1-f72.google.com (mail-io1-f72.google.com [209.85.166.72]) by kanga.kvack.org (Postfix) with ESMTP id F07F78E005B for ; Mon, 31 Dec 2018 03:24:28 -0500 (EST) Received: by mail-io1-f72.google.com with SMTP id f24so31224488ioh.21 for ; Mon, 31 Dec 2018 00:24:28 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:mime-version:references :in-reply-to:from:date:message-id:subject:to:cc; bh=x/dJbjiOAY3ymU6pajADp9+hSys+HJ1L9NBPmb3INQs=; b=HtQBlXAX6pt0YzcWxU9BFOw8v+7Jpo/9z6MdlLWFjNcHIifM6ukj6yk61lZRAkTvo3 bVoI15+Q+6IXVotDk5gxUSQSgJKpyoIxm6Ytf02H/zEWA8W04MuIQ7DIw7OPWmvR9tL4 LkVn/QrXLT96QpexPpsjlQhy55wJ8zFj9eS9znACmsDnNmo/gRv4173NeEVL5BrLElYg qNK9/bIJl0BzEOSSDjmtzirxNZmR9MhBuAjyN1LTm2czHhsq4aw3oRoE+kINPzMhoNbI gqE4QME7nUiJ3qHdSv8d6g4zI7jjJRn3LHBaI61PcvawrThkTt3cuoVpnKqS9SfvPnqx 780Q== X-Gm-Message-State: AA+aEWYj/yg4422DKRQk+vD0Yy27ZkHPXP8Mgl2dtCVc4zeLKHe7jdqP tfKcwI+dJrvR9NJnHvr3LvPY8M8z5r8JaAOKTMgv2EbfpEpYw+Ipdir3Dx+2/3n5quyqTtHamEk 9YEcRwMW+IObFlxc0zw7i+OlDg6zBRldT71h/S8Kjcof2vNKABJ3SNcgBaBCgYccW/X7xXbg9R5 isXuYTSq153GF3ObRt2hvRXUyVZdIK530S3YHx/hF04EQkv+EaLcn4fsLvrCaKfzdQuXjgy9N0j vghcR2VybMAg7Q7DryuLW1NrjhRPSRmhXzoX4r5ttya2jHWS8ytP0uDMHoyGdCLcFCx/JnpKYSC YF0mjUBrqmJm5Alte7z1QRDn0ovRrzvxIjIg1QMic4hoKHrUFsTWncT8S1lDREenoAfeS7knbpv Y X-Received: by 2002:a02:590:: with SMTP id 16mr24578219jal.48.1546244668721; Mon, 31 Dec 2018 00:24:28 -0800 (PST) X-Received: by 2002:a02:590:: with SMTP id 16mr24578198jal.48.1546244668145; Mon, 31 Dec 2018 00:24:28 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1546244668; cv=none; d=google.com; s=arc-20160816; b=Ft8b+DlEq6GiQ6dIIuFstxjAqqu5xI0AnXwOo27i37swXtcxuCxjfDYLAZc+tZJ8q3 ZcMwSGNAuqCSFURql+yIgy5V3NQJoXjXIhYOzAaZcVss4N2viXoAa+H8+X4LuV2/LCi+ 9BzEJmQ4qTP4UZPFw4gSe5Un2J1310Zz9+9jISuRZT3yRtqelfJiH8K9rIiVbpvUK5qg qr5bbe58huJfQGYGI8pHLwwYFOJTJDhmDWc6AMnR7+MVseHYFGXCIpAYNfafI6NHbJXB s+WHRFwcj1AoMi7mgXZqRBWVeLfEWqJRFEc7zZtL2jwIaN6upsb9/dpGY78BWzucavoy r37g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:dkim-signature; bh=x/dJbjiOAY3ymU6pajADp9+hSys+HJ1L9NBPmb3INQs=; b=mSXenbRYmGKsAkNd5UgG/u5DgyUovOG1K5ZvIKTtG9P2Jab58TqORVWKen+g8FKpP5 4a73hcB13mU9L5QiJKzvpPtAOAVwKHJC/gWhcOTAJge1Ta1AjSrPS5x5477J/0NsBPKU zpYvvUR8h6r4SL8bQItBSPXdZJZyK1HD9DP0p6DhIKWEEj50mgv6MeaSweYCTbM8qQrX xz9yauKZJo2pEhmyz8F1EV9EhSYvOMluhulFz4gBkyV0xSMrZapwmuyKv8YYXCM7eYoU q+0snvPsxxABMnx2lxVjvHi/Jn5mC7Cereu3yzHIRmymJhNaSqwOJNxey1ULIkJF2Ytz IeKg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=lL9PqDvS; 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 Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id v20sor31247342ita.10.2018.12.31.00.24.28 for (Google Transport Security); Mon, 31 Dec 2018 00:24:28 -0800 (PST) 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=lL9PqDvS; 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=x/dJbjiOAY3ymU6pajADp9+hSys+HJ1L9NBPmb3INQs=; b=lL9PqDvSoOx02XKuKc4YXYvZEjuWMuahfKL9/Xlz+0U/k9gTkaDk+cOWtoH04IgSmI 6+tiQ+AC5KSIHUJhvxrLuW51jmhUH/fp2d6d2IdQqYmm7tzVKr+uUTGPjrm2BxV9mxgx U5XykdJaTfL4SbVPowXm1de5Add8k69pE+f1VJEf3jVHdF9CWVnkAhzrkL5S07Hk7qZS 0VKs3/9VHcOojv1drHai35XhpBT3rppyZakSOnZ16wmPCBPCw4S3J6YiJXoFP4nYoj3f izS9l3vG2opYLcvP8qVG/JCooLA5ZOCLL3mvAUeYr7rfOtsRodvRuqV8QHrc0vfnpbmI aUpw== X-Google-Smtp-Source: AFSGD/WAXRR32TGOAsq8ckXtNG4WI9cS6EgN+hAJoP8QpGjd2i1aJD1h4MIBx0fPKKhWRr2JmBQqnyNtZYsKApO51K0= X-Received: by 2002:a05:660c:f94:: with SMTP id x20mr20595383itl.144.1546244667674; Mon, 31 Dec 2018 00:24:27 -0800 (PST) MIME-Version: 1.0 References: <0000000000007beca9057e4c8c14@google.com> In-Reply-To: From: Dmitry Vyukov Date: Mon, 31 Dec 2018 09:24:16 +0100 Message-ID: Subject: Re: INFO: rcu detected stall in ndisc_alloc_skb To: Tetsuo Handa Cc: syzbot , David Miller , Alexey Kuznetsov , LKML , netdev , syzkaller-bugs , Hideaki YOSHIFUJI , Linux-MM 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: Message-ID: <20181231082416.OFiRcqdDYgTkO8JkiL6_Nda0anuTon6vZXWT5TvUeMo@z> On Mon, Dec 31, 2018 at 9:17 AM Tetsuo Handa wrote: > > On 2018/12/31 16:49, Dmitry Vyukov wrote: > > On Mon, Dec 31, 2018 at 8:42 AM syzbot > > wrote: > >> > >> Hello, > >> > >> syzbot found the following crash on: > >> > >> HEAD commit: ef4ab8447aa2 selftests: bpf: install script with_addr.sh > >> git tree: bpf-next > >> console output: https://syzkaller.appspot.com/x/log.txt?x=14a28b6e400000 > >> kernel config: https://syzkaller.appspot.com/x/.config?x=7e7e2279c0020d5f > >> dashboard link: https://syzkaller.appspot.com/bug?extid=ea7d9cb314b4ab49a18a > >> compiler: gcc (GCC) 8.0.1 20180413 (experimental) > >> > >> Unfortunately, I don't have any reproducer for this crash yet. > >> > >> IMPORTANT: if you fix the bug, please add the following tag to the commit: > >> Reported-by: syzbot+ea7d9cb314b4ab49a18a@syzkaller.appspotmail.com > > > > Since this involves OOMs and looks like a one-off induced memory corruption: > > > > #syz dup: kernel panic: corrupted stack end in wb_workfn > > > > Why? > > RCU stall in this case is likely to be latency caused by flooding of printk(). Just a hypothesis. OOMs lead to arbitrary memory corruptions, so can cause stalls as well. But can be what you said too. I just thought that cleaner dashboard is more useful than a large assorted pile of crashes. If you think it's actionable in some way, feel free to undup.