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=-5.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_2 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 18D31C433EA for ; Mon, 3 Aug 2020 15:42:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E510720678 for ; Mon, 3 Aug 2020 15:42:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="O9JK86Tc"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="s4K2YpwD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728060AbgHCPm4 (ORCPT ); Mon, 3 Aug 2020 11:42:56 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:37566 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728232AbgHCPmz (ORCPT ); Mon, 3 Aug 2020 11:42:55 -0400 Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 0C8748EE1DD; Mon, 3 Aug 2020 08:42:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1596469374; bh=Uum3YBzktKJNuHiR6OJu5HmfTF5qQnA5gi/i5G/rXrQ=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=O9JK86TcVP7gbxm2fb/8Q61ppK2NKKQTxTKNuHlV2ceyKu1aTztA5xAoiJrD2pxW/ Q+qv2hXr5mwEzJ3gdctVri6mhLMR5/CHlIiEsE/4/lI+JZDaI0KDvNumWeAJkyX13U OCGvKNLxJrKe8ou8wqztvVdP+b2dZwwO98fcCXtA= Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id EdiLDuzcATav; Mon, 3 Aug 2020 08:42:53 -0700 (PDT) Received: from [153.66.254.194] (unknown [50.35.76.230]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by bedivere.hansenpartnership.com (Postfix) with ESMTPSA id 81ED08EE14D; Mon, 3 Aug 2020 08:42:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1596469373; bh=Uum3YBzktKJNuHiR6OJu5HmfTF5qQnA5gi/i5G/rXrQ=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=s4K2YpwDLz+5kMilTgP8ZNMakkD9GePIXlmZcfIzJDFHwQHhqnSrKdXx2dgkvpwtr hAqE4Wy7TqMCx3r3hCV4Hpap0/QxwKCr2EbyGneLKFgGD6GJ8mv6m1pfA0xUdlMOoP UgLcD2xTWanH2eZI7HU/ES49TBMi0ZvSvbsfkml4= Message-ID: <1596469370.29091.13.camel@HansenPartnership.com> Subject: Re: [RFC PATCH 0/5] madvise MADV_DOEXEC From: James Bottomley To: "Eric W. Biederman" , Steven Sistare Cc: Matthew Wilcox , Anthony Yznaga , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, mhocko@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, arnd@arndb.de, keescook@chromium.org, gerg@linux-m68k.org, ktkhai@virtuozzo.com, christian.brauner@ubuntu.com, peterz@infradead.org, esyr@redhat.com, jgg@ziepe.ca, christian@kellner.me, areber@redhat.com, cyphar@cyphar.com Date: Mon, 03 Aug 2020 08:42:50 -0700 In-Reply-To: <877dufvje9.fsf@x220.int.ebiederm.org> References: <1595869887-23307-1-git-send-email-anthony.yznaga@oracle.com> <20200730152250.GG23808@casper.infradead.org> <20200730171251.GI23808@casper.infradead.org> <63a7404c-e4f6-a82e-257b-217585b0277f@oracle.com> <20200730174956.GK23808@casper.infradead.org> <87y2n03brx.fsf@x220.int.ebiederm.org> <689d6348-6029-5396-8de7-a26bc3c017e5@oracle.com> <877dufvje9.fsf@x220.int.ebiederm.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, 2020-08-03 at 10:28 -0500, Eric W. Biederman wrote: [...] > What is wrong with live migration between one qemu process and > another qemu process on the same machine not work for this use case? > > Just reusing live migration would seem to be the simplest path of > all, as the code is already implemented. Further if something goes > wrong with the live migration you can fallback to the existing > process. With exec there is no fallback if the new version does not > properly support the handoff protocol of the old version. Actually, could I ask this another way: the other patch set you sent to the KVM list was to snapshot the VM to a PKRAM capsule preserved across kexec using zero copy for extremely fast save/restore. The original idea was to use this as part of a CRIU based snapshot, kexec to new system, restore. However, why can't you do a local snapshot, restart qemu, restore using the PKRAM capsule to achieve exactly the same as MADV_DOEXEC does but using a system that's easy to reason about? It may be slightly slower, but I think we're still talking milliseconds. James