Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751849AbbG3OqB (ORCPT ); Thu, 30 Jul 2015 10:46:01 -0400 Received: from mx2.suse.de ([195.135.220.15]:39083 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751148AbbG3OqA (ORCPT ); Thu, 30 Jul 2015 10:46:00 -0400 Date: Thu, 30 Jul 2015 15:45:54 +0100 From: Mel Gorman To: David Vrabel Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Robin Holt , Nathan Zimmer Subject: Re: [PATCHv1] mm: always initialize pages as reserved to fix memory hotplug Message-ID: <20150730144554.GS2561@suse.de> References: <1438265083-31208-1-git-send-email-david.vrabel@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1438265083-31208-1-git-send-email-david.vrabel@citrix.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1988 Lines: 52 On Thu, Jul 30, 2015 at 03:04:43PM +0100, David Vrabel wrote: > Commit 92923ca3aacef63c92dc297a75ad0c6dfe4eab37 (mm: meminit: only set > page reserved in the memblock region) breaks memory hotplug because pages > within newly added sections are not marked as reserved as required by > the memory hotplug driver. I don't have access to a large machine at the moment to verify and won't have until Monday at the earliest but I think that will bust deferred initialisation. Why not either SetPageReserved from mem hotplug driver? It might be neater to remove the PageReserved check from online_pages_range() but then care would have to be taken to ensure that invalid PFNs within section that have no memory backing them were properly reserved. This is an untested, uncompiled version of the first suggestion diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 26fbba7d888f..003dbe4b060d 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -446,7 +446,7 @@ static int __meminit __add_zone(struct zone *zone, unsigned long phys_start_pfn) int nr_pages = PAGES_PER_SECTION; int nid = pgdat->node_id; int zone_type; - unsigned long flags; + unsigned long flags, pfn; int ret; zone_type = zone - pgdat->node_zones; @@ -461,6 +461,14 @@ static int __meminit __add_zone(struct zone *zone, unsigned long phys_start_pfn) pgdat_resize_unlock(zone->zone_pgdat, &flags); memmap_init_zone(nr_pages, nid, zone_type, phys_start_pfn, MEMMAP_HOTPLUG); + + /* online_page_range is called later and expects pages reserved */ + for (pfn = phys_start_pfn; pfn < phys_start_pfn + nr_pages; pfn++) { + if (!pfn_valid(pfn)) + continue; + + SetPageReserved(pfn_to_page(pfn)); + } return 0; } -- Mel Gorman SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/