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[147.75.199.223]) by mx.google.com with ESMTPS id j12-20020a05620a0a4c00b0078d751ce646si2303875qka.70.2024.04.11.14.28.38 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Apr 2024 14:28:38 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel+bounces-141630-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223; Authentication-Results: mx.google.com; dkim=pass header.i=@linux-foundation.org header.s=korg header.b=1rFSV6Wn; arc=pass (i=1 dkim=pass dkdomain=linux-foundation.org); spf=pass (google.com: domain of linux-kernel+bounces-141630-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) smtp.mailfrom="linux-kernel+bounces-141630-linux.lists.archive=gmail.com@vger.kernel.org" Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ny.mirrors.kernel.org (Postfix) with ESMTPS id 480761C22455 for ; Thu, 11 Apr 2024 21:28:38 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 7307939FFD; Thu, 11 Apr 2024 21:28:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="1rFSV6Wn" Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7EC723CF65; Thu, 11 Apr 2024 21:28:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712870909; cv=none; b=polrgxLsyRIBYeqLN3nxBGNtX8rKRvy14xM59kH7FW4sYaXRn7tcsrD2JPxPG7Fwnd28tREMqi9kLEU2pmKgZFKGvN2czpapbwZL0uIiqQg/v/6Aho5VrfrtVXkFq03w6NndUIgJL2Vw67IzSCsrr9q7MO28r6kYmfI5+JhAh0o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712870909; c=relaxed/simple; bh=qYZJAos8Y1VlhyFh0wodG8r9EP6fTB4gaPBhuU18hO8=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=dfdC0AyJ+z3hyl9vQa4bmV2t9IzQvqbWlDTacSGrXRKrWDRAOjm34Q7ZfV8apoMEWFkGObWuVaN6E/F0973OdUZH3W9X/FWrVBFv6KLKOP0nJs5MWLRI82/tdGQd9SR6Ey0FZMRLlyAYZ6IGpFASTlcvT9rGJaYPwbIMjDx/YLY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=1rFSV6Wn; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8DDE9C072AA; Thu, 11 Apr 2024 21:28:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1712870909; bh=qYZJAos8Y1VlhyFh0wodG8r9EP6fTB4gaPBhuU18hO8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=1rFSV6WnuiT57XyEfZi728PpeWo2haLruBtoEN/Awm7LEedlT6WNJf8F+xyZCGAbv A/fAldqTr7ZyeA4IjWWh5av3FodBpvp0cpkMq0+hvyjt0yt+ElWoSI0swMmZrBNU6n olojFA0RW078omUyeBn/qiSahZ9Hne+LuXx1HR/I= Date: Thu, 11 Apr 2024 14:28:27 -0700 From: Andrew Morton To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Peter Xu , Alexander Gordeev , Sven Schnelle , Gerald Schaefer , Andrea Arcangeli , kvm@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH v3 0/2] s390/mm: shared zeropage + KVM fixes Message-Id: <20240411142827.d5c3bc401c6536bb1315049a@linux-foundation.org> In-Reply-To: <20240411161441.910170-1-david@redhat.com> References: <20240411161441.910170-1-david@redhat.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 11 Apr 2024 18:14:39 +0200 David Hildenbrand wrote: > This series fixes one issue with uffd + shared zeropages on s390x and > fixes that "ordinary" KVM guests can make use of shared zeropages again. > > ... > > Without the shared zeropage, during (2), the VM would suddenly consume > 100 GiB on the migration source and destination. On the migration source, > where we don't excpect memory overcommit, we could easilt end up crashing > the VM during migration. > > Independent of that, memory handed back to the hypervisor using "free page > reporting" would end up consuming actual memory after the migration on the > destination, not getting freed up until reused+freed again. > Is a backport desirable? If so, the [1/2] Fixes dates back to 2015 and the [2/2] Fixes is from 2017. Is it appropriate that the patches be backported so far back, and into different kernel versions?