From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f199.google.com (mail-wr0-f199.google.com [209.85.128.199]) by kanga.kvack.org (Postfix) with ESMTP id 9D8046B0022 for ; Mon, 19 Feb 2018 12:19:20 -0500 (EST) Received: by mail-wr0-f199.google.com with SMTP id r29so888523wra.13 for ; Mon, 19 Feb 2018 09:19:20 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 12si9716283wmy.239.2018.02.19.09.19.18 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 19 Feb 2018 09:19:18 -0800 (PST) Date: Mon, 19 Feb 2018 18:19:16 +0100 From: Michal Hocko Subject: Re: [PATCH] mm: Fix for PG_reserved page flag clearing Message-ID: <20180219171916.GR21134@dhcp22.suse.cz> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Masayoshi Mizuma Cc: akpm@linux-foundation.org, mgorman@techsingularity.net, pasha.tatashin@oracle.com, linux-mm@kvack.org On Mon 19-02-18 12:06:14, Masayoshi Mizuma wrote: > From: Masayoshi Mizuma > > struct page is inizialized as zero in __init_single_page(). > If the page is offlined page, PG_reserved flag is set in early boot > time before __init_single_page(), so we should not clear the flag. > > The real problem is that we can not online the offlined page > through following sysfs operation because offlined page is > expected PG_reserved flag is set. > It is not needed the initialization, so remove it simply. > > Code: > > static int online_pages_range(unsigned long start_pfn, > ... > if (PageReserved(pfn_to_page(start_pfn))) <= HERE!! > for (i = 0; i < nr_pages; i++) { > page = pfn_to_page(start_pfn + i); > (*online_page_callback)(page); > onlined_pages++; > sysfs operation: > > # echo online > /sys/devices/system/node/node2/memory12288/online > # cat /sys/devices/system/node/node2/memory12288/online > 1 > # cat /sys/devices/system/node/node2/meminfo > Node 2 MemTotal: 0 kB Nack. The patch is simply wrong. We do need to zero page for the boot pages. I believe the fix you are looking for is 9bb5a391f9a5 ("mm, memory_hotplug: fix memmap initialization"). Or do you still see a problem with this patch applied? > Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap") > Signed-off-by: Masayoshi Mizuma > --- > mm/page_alloc.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 76c9688..3260cd2 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1179,7 +1179,6 @@ static void free_one_page(struct zone *zone, > static void __meminit __init_single_page(struct page *page, unsigned long pfn, > unsigned long zone, int nid) > { > - mm_zero_struct_page(page); > set_page_links(page, zone, nid, pfn); > init_page_count(page); > page_mapcount_reset(page); > -- > 2.16.1 > > - Masayoshi -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org