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=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=unavailable 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 E5E05C282DD for ; Wed, 17 Apr 2019 22:03:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A9038217FA for ; Wed, 17 Apr 2019 22:03:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555538616; bh=JeL4gdAt0hsRIkQ6cxAgSOj/S1N63lLGqtpxClQsFVI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=xNwcpGd6OoOoyZNuLEaiaws6iWVAbyFDcU/WuXIGqArpEyRi3PtspDEMl+aUdluYS 3NVA4AsTj0payDutH7yRZ4RmcarYTYRmggwjHmfqQA20g8mpOMXL4dOtPLvhhQCQmf qZDh+qdifN2g76iSZZUh+ianLa58VefYb0GAfAis= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387563AbfDQWDg (ORCPT ); Wed, 17 Apr 2019 18:03:36 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55152 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725848AbfDQWDe (ORCPT ); Wed, 17 Apr 2019 18:03:34 -0400 Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id E04B4B3E; Wed, 17 Apr 2019 22:03:32 +0000 (UTC) Date: Wed, 17 Apr 2019 15:03:31 -0700 From: Andrew Morton To: Dan Williams Cc: David Hildenbrand , =?ISO-8859-1?Q?J=E9r=F4me?= Glisse , Logan Gunthorpe , Toshi Kani , Jeff Moyer , Michal Hocko , Vlastimil Babka , stable@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 00/12] mm: Sub-section memory hotplug support Message-Id: <20190417150331.90219ca42a1c0db8632d0fd5@linux-foundation.org> In-Reply-To: <155552633539.2015392.2477781120122237934.stgit@dwillia2-desk3.amr.corp.intel.com> References: <155552633539.2015392.2477781120122237934.stgit@dwillia2-desk3.amr.corp.intel.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 17 Apr 2019 11:38:55 -0700 Dan Williams wrote: > The memory hotplug section is an arbitrary / convenient unit for memory > hotplug. 'Section-size' units have bled into the user interface > ('memblock' sysfs) and can not be changed without breaking existing > userspace. The section-size constraint, while mostly benign for typical > memory hotplug, has and continues to wreak havoc with 'device-memory' > use cases, persistent memory (pmem) in particular. Recall that pmem uses > devm_memremap_pages(), and subsequently arch_add_memory(), to allocate a > 'struct page' memmap for pmem. However, it does not use the 'bottom > half' of memory hotplug, i.e. never marks pmem pages online and never > exposes the userspace memblock interface for pmem. This leaves an > opening to redress the section-size constraint. v6 and we're not showing any review activity. Who would be suitable people to help out here?