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=-7.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 A43B2C433F5 for ; Wed, 22 Sep 2021 15:13:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8382B610A1 for ; Wed, 22 Sep 2021 15:13:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232148AbhIVPPS (ORCPT ); Wed, 22 Sep 2021 11:15:18 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:53032 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232285AbhIVPPR (ORCPT ); Wed, 22 Sep 2021 11:15:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632323627; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5EPOrsCXJCI2JISUvTnGCdXaDuxLEQ6pf0yprZLLbiA=; b=WMi2xnDsPCv/ltVsvQrP+iCsKtAiOxfWFPE5dHaUurdrDuCFh49Zu2prYgWX81jIn2OsD7 MFY3M9svf+yzf9JI54uK/JDdaxa1gzywSEDoCOh3S79VR6kxqFxvvhX1pAsp7ycDsWEiwb yrfwo9v85Rz8TMpmVIi5c/1xZ1q5siE= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-520-rk2rdeFdPJ63DmkbTYfuyA-1; Wed, 22 Sep 2021 11:13:45 -0400 X-MC-Unique: rk2rdeFdPJ63DmkbTYfuyA-1 Received: by mail-wr1-f72.google.com with SMTP id c2-20020adfa302000000b0015e4260febdso2432319wrb.20 for ; Wed, 22 Sep 2021 08:13:45 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:subject:from:to:date:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=5EPOrsCXJCI2JISUvTnGCdXaDuxLEQ6pf0yprZLLbiA=; b=06k3lNDrXjmPpiD8OU5BDKrEOAiZSZ0vwLjKrwQS2ca5zzatOWDeBUmbkTiuFkDFAJ w0k+1sIBodfu349ncvu7wz/hLYVLrcJjUR+sE6D2ziXys4sorg8RqX6F5tIfp7aNP4SK 4v6BfgRa3k6lXQSKW8left5b/VT5Z9wCnVUkXYZkfIK1gWD/Con10NTkgo4NjW7Ef4yw QaLOJbAKvndXvj+BVWmrcWHiCb8z1mHmVzCbIjjUoNgXLaYEpkjiIo2UuL+8/SrSRBH5 hBoSS3e6daQHqoQG7vAuIk5KKoF6vBw6E2dpPA6KhZ9TTrBSlvpwvt//QmOmw+p7OA1/ Ud9w== X-Gm-Message-State: AOAM5307P+X9C4WCa54xdWVGLC3kHatPYoTZm7INVEdXVOPp/5jjA4Ee XiJjk8naNoAxIma1g/dSKUG0W36Np8lmp2UIYLS6qEjI/sxbOVJQmDY3j3R+bssCOMCwvKNKxSE qN8CL9u16gJgGieTBlEUCjsEw X-Received: by 2002:a05:6000:1569:: with SMTP id 9mr26404wrz.337.1632323624391; Wed, 22 Sep 2021 08:13:44 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyvnvC1X46a60tAUJjRFUNeH9O76Z4tTvV4A0XH/5wYBwm8hZIYhzLdFFgPJ1WG9X83xkic8A== X-Received: by 2002:a05:6000:1569:: with SMTP id 9mr26378wrz.337.1632323624166; Wed, 22 Sep 2021 08:13:44 -0700 (PDT) Received: from gerbillo.redhat.com (146-241-102-46.dyn.eolo.it. [146.241.102.46]) by smtp.gmail.com with ESMTPSA id m4sm6559554wml.28.2021.09.22.08.13.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Sep 2021 08:13:43 -0700 (PDT) Message-ID: <89d72aca4e30335a03322612cf164420be11d8eb.camel@redhat.com> Subject: Re: [syzbot] INFO: rcu detected stall in sys_recvmmsg From: Paolo Abeni To: syzbot , axboe@kernel.dk, christian.brauner@ubuntu.com, davem@davemloft.net, dkadashev@gmail.com, kuba@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, mathew.j.martineau@linux.intel.com, matthieu.baerts@tessares.net, mptcp@lists.linux.dev, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk Date: Wed, 22 Sep 2021 17:13:42 +0200 In-Reply-To: <0000000000003216d705cc8a62d6@google.com> References: <0000000000003216d705cc8a62d6@google.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2021-09-21 at 17:13 -0700, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 1f77990c4b79 Add linux-next specific files for 20210920 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=1383891d300000 > kernel config: https://syzkaller.appspot.com/x/.config?x=ab1346371f2e6884 > dashboard link: https://syzkaller.appspot.com/bug?extid=3360da629681aa0d22fe > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1625f1ab300000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17eb1b3b300000 > > The issue was bisected to: > > commit 020250f31c4c75ac7687a673e29c00786582a5f4 > Author: Dmitry Kadashev > Date: Thu Jul 8 06:34:43 2021 +0000 > > namei: make do_linkat() take struct filename > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15f5ef77300000 > final oops: https://syzkaller.appspot.com/x/report.txt?x=17f5ef77300000 > console output: https://syzkaller.appspot.com/x/log.txt?x=13f5ef77300000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+3360da629681aa0d22fe@syzkaller.appspotmail.com > Fixes: 020250f31c4c ("namei: make do_linkat() take struct filename") I'm unsure why the bisection points to this commit. This looks like an MPTCP specific issue, due to bad handling of MSG_WAITALL recvmsg() flag. I'll test a fix with syzbot to confirm the above. Cheers, Paolo