From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752425AbeDEWIp (ORCPT ); Thu, 5 Apr 2018 18:08:45 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:56288 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751443AbeDEWIo (ORCPT ); Thu, 5 Apr 2018 18:08:44 -0400 Date: Thu, 5 Apr 2018 15:08:42 -0700 From: Andrew Morton To: Baoquan He Cc: linux-kernel@vger.kernel.org, dave.hansen@intel.com, pagupta@redhat.com, linux-mm@kvack.org, kirill.shutemov@linux.intel.com Subject: Re: [PATCH v3 0/4] mm/sparse: Optimize memmap allocation during sparse_init() Message-Id: <20180405150842.350e4febc06a813138f00416@linux-foundation.org> In-Reply-To: <20180228032657.32385-1-bhe@redhat.com> References: <20180228032657.32385-1-bhe@redhat.com> X-Mailer: Sylpheed 3.5.1 (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 List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 28 Feb 2018 11:26:53 +0800 Baoquan He wrote: > This is v3 post. V1 can be found here: > https://www.spinics.net/lists/linux-mm/msg144486.html > > In sparse_init(), two temporary pointer arrays, usemap_map and map_map > are allocated with the size of NR_MEM_SECTIONS. They are used to store > each memory section's usemap and mem map if marked as present. In > 5-level paging mode, this will cost 512M memory though they will be > released at the end of sparse_init(). System with few memory, like > kdump kernel which usually only has about 256M, will fail to boot > because of allocation failure if CONFIG_X86_5LEVEL=y. > > In this patchset, optimize the memmap allocation code to only use > usemap_map and map_map with the size of nr_present_sections. This > makes kdump kernel boot up with normal crashkernel='' setting when > CONFIG_X86_5LEVEL=y. This patchset could do with some more review, please?