Received: by 2002:a25:4158:0:0:0:0:0 with SMTP id o85csp4095259yba; Mon, 29 Apr 2019 13:39:51 -0700 (PDT) X-Google-Smtp-Source: APXvYqwd4AEpk2jsDzzcTI7oD3k6TEX1SvqB2VwayzXbE7pGsms0YNer3VML0D9JGVDnScbisOY/ X-Received: by 2002:a17:902:22f:: with SMTP id 44mr63590661plc.175.1556570391506; Mon, 29 Apr 2019 13:39:51 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1556570391; cv=none; d=google.com; s=arc-20160816; b=NTpOk+IgGNrci1lbGVx612w+ChzodE2cUsy84anJzsqPRpNJvppnS89jGpVmj26SDO 8lHqCii3MMIzd2xP1/NkF4yvTR1yn1sqmJYzdxZvP/AUkDSFU39qzWHB3nDWiKEbvhEc Lx7CkDSKU/A1115QhKCLGVdoUK4XQCX/QHpEkCO8DMT00uOmm+McE7oFfXwvXl+cioAN 0O9M2+T49UbPA7MyPPbAqbJODlj6rWL2HVsmNeqZ/mbEhAUQM+fUr54A83dU+8uNEsVq 9a9KLybygYsdnOoWYVOVjSzxCKv35lyB/qI4e6UazbHHL+Sg2JKuopy/qrbZNYfLpp4u 36PQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:mime-version:user-agent:message-id :in-reply-to:date:references:subject:cc:to:from; bh=aAK0pqiPlT6thvXJb6lYzSX6bLQrq30Rj5mS9JoK7l8=; b=wm3B+t7177IAAyzkPIoQN4ElBfkxQsYSa7EfngaHwCpf8EjKHld2oSVUGnUq+mReCP CPyQi50XfjSYVgaOwhLU5uxg/MjempWjLnwEkeUB1ZIBHkpqAd9TZgXCAINlambxXu71 CuEKls9VRbvZ9K5JwZngl8taFbHk5UBun4hw1UreyYAAMOdFnR/wjyunyi76oc2h5/XU Us/SKrVfekW4ACqB8nWs9/QMCpb/cMI2TlPXdEs3WDeOpSP9xWbzCxK8H1cUVTjUPQTg qhrGSh+ERmvOPdG+lMUrjBm6IcRhobVEiD+4UyJiqX1pXTUw9n0z2ZBBIdmsSCrjjanu DARA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id t136si33823691pgc.538.2019.04.29.13.39.33; Mon, 29 Apr 2019 13:39:51 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729372AbfD2UiR (ORCPT + 99 others); Mon, 29 Apr 2019 16:38:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36894 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729252AbfD2UiR (ORCPT ); Mon, 29 Apr 2019 16:38:17 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4B87F308626C; Mon, 29 Apr 2019 20:38:16 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-116-123.ams2.redhat.com [10.36.116.123]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C76F01001959; Mon, 29 Apr 2019 20:38:08 +0000 (UTC) From: Florian Weimer To: Linus Torvalds Cc: Jann Horn , Kevin Easton , Andy Lutomirski , Christian Brauner , Aleksa Sarai , "Enrico Weigelt\, metux IT consult" , Al Viro , David Howells , Linux API , LKML , "Serge E. Hallyn" , Arnd Bergmann , "Eric W. Biederman" , Kees Cook , Thomas Gleixner , Michael Kerrisk , Andrew Morton , Oleg Nesterov , Joel Fernandes , Daniel Colascione Subject: Re: RFC: on adding new CLONE_* flags [WAS Re: [PATCH 0/4] clone: add CLONE_PIDFD] References: <20190414201436.19502-1-christian@brauner.io> <20190415195911.z7b7miwsj67ha54y@yavin> <20190420071406.GA22257@ip-172-31-15-78> Date: Mon, 29 Apr 2019 22:38:06 +0200 In-Reply-To: (Linus Torvalds's message of "Mon, 29 Apr 2019 13:21:06 -0700") Message-ID: <87zho8bl8x.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Mon, 29 Apr 2019 20:38:16 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Linus Torvalds: > On Mon, Apr 29, 2019 at 12:55 PM Jann Horn wrote: >> >> ... I guess that already has a name, and it's called vfork(). (Well, >> except that the Linux vfork() isn't a real vfork().) > > What? > > Linux vfork() is very much a real vfork(). What do you mean? In Linux-as-the-ABI (as opposed to Linux-as-the-implementation), vfork is sometimes implemented as fork, so applications cannot rely on the vfork behavior regarding the stopped parent and the shared address space. In fact, it would be nice to have a flag we can check in the posix_spawn implementation, so that we can support vfork-as-fork without any run time cost to native Linux. Thanks, Florian