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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 4D8CDC4CEC7 for ; Mon, 16 Sep 2019 01:41:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 14C712067B for ; Mon, 16 Sep 2019 01:41:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Io9gq4kx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727774AbfIPBlB (ORCPT ); Sun, 15 Sep 2019 21:41:01 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:45015 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726074AbfIPBlA (ORCPT ); Sun, 15 Sep 2019 21:41:00 -0400 Received: by mail-wr1-f66.google.com with SMTP id i18so6427036wru.11; Sun, 15 Sep 2019 18:40:58 -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=s5NlWgemAgRgAck5V/LT2mO8N9Ly1ozLQCAwpxW+qmQ=; b=Io9gq4kxX3/9yiKAj3stqnJrMuXjc0/Fv/uNXEN8rQ8qWJh9vjpX5WJOdkFb+OzVX3 kukd031wdu0fXYqw+lPw75A0y3wvKNkXQtBPoYy2BFDFoHyoGCRdVdqyyAeHY0SyhCzP jln4+j1+1DfUoJ807AMeDIwy5ZTgSUXw9MDDk/C/fTE2NZtRhXK+nVRzbSMWBbl/1UBD R8KS0ljobpqH447i45NN60s/2d2XQfjJFWQ6+zLuZ10bfjDNBSlz7KR+NPiCFVKItNSt LHWL8WJZZyfQHG6PT93H3UFRbwuGOAnEHIoM2A194wEq8+Jeo5YAj3mDaV/g/x74dpLR LJzw== 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=s5NlWgemAgRgAck5V/LT2mO8N9Ly1ozLQCAwpxW+qmQ=; b=fHy198bGx4SukQr2u9arnflxOKUAYO3d7zBFmz+QW0cOO4pA1SaF+c3TcY2hROnGkR nvCGR+U0fWQMZ9U3+cEMcMZiMju0bmXC2yC+y+yfjZwXIm+UWDOYKVF8/40FeN9TZy6z jjOzxgUE5qk1kiY9E1FqNHYjmoKkLgLeHgr6p/p0JKcn26bAUsozAkzdEKIX1QTEQLfF HgfEI63yWx9ATibCJ903VKLNpsB0Gz2QvkWqd2KZ2FX1pt16oNkeXTT4eNrZTmdbw7jQ WnEmVL82CCYNhAEIwNJiDZgo1Zr1Mi8emnNuBGNUUS/34Qp4hJXluTDSGl2m4SeKEDbb Wvxw== X-Gm-Message-State: APjAAAW2qkttallZF5XNHLN0+bzyLX+19ePx/YxGeZ2lPvlJ0vCtOKpE GUwP5TVidkAM4E7miHSR2h0= X-Google-Smtp-Source: APXvYqz6sCS29EwAmavddzyT7utN1acTq4CZlykL/oWxxNi/CQgskS/fJUcG222M03uXlt1coc57pg== X-Received: by 2002:a05:6000:10f:: with SMTP id o15mr9530373wrx.92.1568598057996; Sun, 15 Sep 2019 18:40:57 -0700 (PDT) Received: from darwi-home-pc (p200300D06F2D144910CD9D07D5336EC2.dip0.t-ipconnect.de. [2003:d0:6f2d:1449:10cd:9d07:d533:6ec2]) by smtp.gmail.com with ESMTPSA id b144sm11061016wmb.3.2019.09.15.18.40.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Sep 2019 18:40:57 -0700 (PDT) Date: Mon, 16 Sep 2019 03:40:50 +0200 From: "Ahmed S. Darwish" To: Linus Torvalds Cc: Lennart Poettering , "Theodore Y. Ts'o" , Andreas Dilger , Jan Kara , Ray Strode , William Jon McCann , "Alexander E. Patrakov" , zhangjs , linux-ext4@vger.kernel.org, lkml Subject: Re: Linux 5.3-rc8 Message-ID: <20190916014050.GA7002@darwi-home-pc> References: <20190911173624.GI2740@mit.edu> <20190912034421.GA2085@darwi-home-pc> <20190912082530.GA27365@mit.edu> <20190914150206.GA2270@darwi-home-pc> <20190915065142.GA29681@gardel-login> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 15, 2019 at 09:29:55AM -0700, Linus Torvalds wrote: > On Sat, Sep 14, 2019 at 11:51 PM Lennart Poettering > wrote: > > > > Oh man. Just spend 5min to understand the situation, before claiming > > this was garbage or that was garbage. The code above does not block > > boot. > > Yes it does. You clearly didn't read the thread. > > > It blocks startup of services that explicit order themselves > > after the code above. There's only a few services that should do that, > > and the main system boots up just fine without waiting for this. > > That's a nice theory, but it doesn't actually match reality. > > There are clearly broken setups that use this for things that it > really shouldn't be used for. Asking for true randomness at boot > before there is any indication that randomness exists, and then just > blocking with no further action that could actually _generate_ said > randomness. > > If your description was true that the system would come up and be > usable while the blocked thread is waiting for that to happen, things > would be fine. > A small note here, especially after I've just read the commit log of 72dbcf721566 ('Revert ext4: "make __ext4_get_inode_loc plug"'), which unfairly blames systemd there. Yes, the systemd-random-seed(8) process blocks, but this is an isolated process, and it's only there as a synchronization point and to load/restore random seeds from disk across reboots. The wisdom of having a sysnchronization service ("before/after urandom CRNG is inited") can be debated. That service though, and systemd in general, did _not_ block the overall system boot. What blocked the system boot was GDM/gnome-session implicitly calling getrandom() for the Xorg MIT cookie. This was shown in the strace log below: https://lkml.kernel.org/r/20190910173243.GA3992@darwi-home-pc thanks, -- darwi http://darwish.chasingpointers.com