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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 D7110C43144 for ; Tue, 26 Jun 2018 05:07:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8BDF126509 for ; Tue, 26 Jun 2018 05:07:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="V2uFFtfY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8BDF126509 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751347AbeFZFHh (ORCPT ); Tue, 26 Jun 2018 01:07:37 -0400 Received: from mail-pl0-f67.google.com ([209.85.160.67]:39534 "EHLO mail-pl0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750960AbeFZFHf (ORCPT ); Tue, 26 Jun 2018 01:07:35 -0400 Received: by mail-pl0-f67.google.com with SMTP id s24-v6so7947383plq.6; Mon, 25 Jun 2018 22:07:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=l8jDJ2S/e0L7yGEIqe1TG2CV/lgShCWQVM1f2Gd7HYk=; b=V2uFFtfYLrbFQQGui8FSp9XARWJXwsbIlLYOyM5Y6PLzSTeya84E/5qfVLH/VI03O/ 3hyctq0/jdElvioFTqGbWdqWBqL8LF0aPhM6be2pQ0Qbk4RvRCSeAMgUuZlbbmtztWF/ exmaRIK8fNTjmvmUdtpj+DDFB753W+snDP9KlI7FyVAIeICWYEpaVWBYU+15IqZ0Mvdl bOSY7fsAnC/JbUpZOxPcGkvL53V/Bd0NbtrQpO/p+gHOgXqNESrwMhuh2Rtq9X98nIfK WGqWWwl6AEbPAJ0cEn7vdKdmWJ3zivqYXmPNA5Bb9MfinapTQPUEfpLun1AdO+XBKNHE ie2Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=l8jDJ2S/e0L7yGEIqe1TG2CV/lgShCWQVM1f2Gd7HYk=; b=aANdoIaRZX1Tk1TbFcvtormqaBEJK/jFOLhylrSkN/aGyzU2jGbwPxo7a5tqHswKGJ eb/z+1jinHcTcgjOmx0LBDK6sjKLyX4AUAoYpGKkIDj0ERojNTcp1jebXt4wSDn5HvIi M1NB9mjgdEeK5LH6sB1e4nk4rY5mp9lPUDayfe84O7gUgvgF9+fXV2NtFqKtCPVyg7H9 c0o7XU5t9mFKnWfbUkVQwKkN35c7P9xIMfBbiTxZK+y7omAqtiQLP13JauXOLZ5bxZN9 s3W77OX36vYiVmDK/MrJO+FiwMvVYV44b68qh3dnMqilGcbWfPvSrPCpkQSEUfhVVGRV gQLA== X-Gm-Message-State: APt69E3/Uc9C9kIFRJugddZcE96TWX7Pciy1zT/9rePb+cPVx/Zpl5d5 7ulsnnfkT+3TQrsOnm7szF0= X-Google-Smtp-Source: ADUXVKIkGiL6R9M29OYOrA/4cl6qmGVHROL9nDDp/GA0DIwOX2O2ub/uJJTvFqiZL/G8liPB9cFxGg== X-Received: by 2002:a17:902:4d:: with SMTP id 71-v6mr15207064pla.317.1529989655273; Mon, 25 Jun 2018 22:07:35 -0700 (PDT) Received: from localhost ([175.223.48.122]) by smtp.gmail.com with ESMTPSA id t23-v6sm1346420pfa.86.2018.06.25.22.07.33 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 25 Jun 2018 22:07:33 -0700 (PDT) Date: Tue, 26 Jun 2018 14:07:31 +0900 From: Sergey Senozhatsky To: Dmitry Vyukov Cc: Steven Rostedt , Sergey Senozhatsky , syzbot , LKML , Petr Mladek , Sergey Senozhatsky , syzkaller-bugs , Samuel Ortiz , "David S. Miller" , linux-wireless@vger.kernel.org, netdev Subject: Re: INFO: rcu detected stall in vprintk_emit Message-ID: <20180626050731.GB31439@jagdpanzerIV> References: <000000000000720530056f7f9b63@google.com> <20180626014924.GB11229@jagdpanzerIV> <20180625225937.43aee76c@vmware.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (06/26/18 07:03), Dmitry Vyukov wrote: > > I don't think this is a printk() issue per se, so I think Option B is > > the only option. You should not get stuck in an infinite loop if we run > > short on memory. Perhaps we could have an Option C which would exit > > this loop gracefully with some kind of error. But I haven't looked at > > the surrounding code to be sure if that is possible. > > I suspect this is not even OOM. Could be. But at the same time it stalls RCU, so OOM at some point becomes realistic. -ss