Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751644Ab2KFKXr (ORCPT ); Tue, 6 Nov 2012 05:23:47 -0500 Received: from mail-lb0-f174.google.com ([209.85.217.174]:44770 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751394Ab2KFKXp (ORCPT ); Tue, 6 Nov 2012 05:23:45 -0500 Message-ID: <5098E52C.7080203@googlemail.com> Date: Tue, 06 Nov 2012 10:23:40 +0000 From: Chris Clayton User-Agent: Mozilla/5.0 (X11; Linux i686; rv:16.0) Gecko/20121030 Thunderbird/16.0.2 MIME-Version: 1.0 To: Jiang Liu CC: Andrew Morton , Maciej Rutecki , Jianguo Wu , "Rafael J. Wysocki" , Mel Gorman , Minchan Kim , KAMEZAWA Hiroyuki , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: fix a regression with HIGHMEM introduced by changeset 7f1290f2f2a4d References: <1352165517-9732-1-git-send-email-jiang.liu@huawei.com> In-Reply-To: <1352165517-9732-1-git-send-email-jiang.liu@huawei.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3094 Lines: 86 On 11/06/12 01:31, Jiang Liu wrote: > Changeset 7f1290f2f2 tries to fix a issue when calculating > zone->present_pages, but it causes a regression to 32bit systems with > HIGHMEM. With that changeset, function reset_zone_present_pages() > resets all zone->present_pages to zero, and fixup_zone_present_pages() > is called to recalculate zone->present_pages when boot allocator frees > core memory pages into buddy allocator. Because highmem pages are not > freed by bootmem allocator, all highmem zones' present_pages becomes > zero. > > Actually there's no need to recalculate present_pages for highmem zone > because bootmem allocator never allocates pages from them. So fix the > regression by skipping highmem in function reset_zone_present_pages() > and fixup_zone_present_pages(). > > Signed-off-by: Jiang Liu > Signed-off-by: Jianguo Wu > Reported-by: Maciej Rutecki > Tested-by: Maciej Rutecki > Cc: Chris Clayton > Cc: Rafael J. Wysocki > Cc: Andrew Morton > Cc: Mel Gorman > Cc: Minchan Kim > Cc: KAMEZAWA Hiroyuki > Cc: Michal Hocko > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > > --- > > Hi Maciej, > Thanks for reporting and bisecting. We have analyzed the regression > and worked out a patch for it. Could you please help to verify whether it > fix the regression? > Thanks! > Gerry > Thanks Gerry. I've applied this patch to 3.7.0-rc4 and can confirm that it fixes the problem I had with my laptop failing to resume after a suspend to disk. Tested-by: Chris Clayton > --- > mm/page_alloc.c | 8 +++++--- > 1 files changed, 5 insertions(+), 3 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 5b74de6..2311f15 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -6108,7 +6108,8 @@ void reset_zone_present_pages(void) > for_each_node_state(nid, N_HIGH_MEMORY) { > for (i = 0; i < MAX_NR_ZONES; i++) { > z = NODE_DATA(nid)->node_zones + i; > - z->present_pages = 0; > + if (!is_highmem(z)) > + z->present_pages = 0; > } > } > } > @@ -6123,10 +6124,11 @@ void fixup_zone_present_pages(int nid, unsigned long start_pfn, > > for (i = 0; i < MAX_NR_ZONES; i++) { > z = NODE_DATA(nid)->node_zones + i; > + if (is_highmem(z)) > + continue; > + > zone_start_pfn = z->zone_start_pfn; > zone_end_pfn = zone_start_pfn + z->spanned_pages; > - > - /* if the two regions intersect */ > if (!(zone_start_pfn >= end_pfn || zone_end_pfn <= start_pfn)) > z->present_pages += min(end_pfn, zone_end_pfn) - > max(start_pfn, zone_start_pfn); > -- 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/