From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f71.google.com (mail-pl0-f71.google.com [209.85.160.71]) by kanga.kvack.org (Postfix) with ESMTP id 62EA16B002C for ; Mon, 19 Feb 2018 14:18:40 -0500 (EST) Received: by mail-pl0-f71.google.com with SMTP id z11so6667082plo.21 for ; Mon, 19 Feb 2018 11:18:40 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id n4-v6si4933860plp.199.2018.02.19.11.18.39 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 19 Feb 2018 11:18:39 -0800 (PST) Date: Mon, 19 Feb 2018 20:18:34 +0100 From: Michal Hocko Subject: Re: [PATCH] mm: Fix for PG_reserved page flag clearing Message-ID: <20180219191834.GS21134@dhcp22.suse.cz> References: <20180219171916.GR21134@dhcp22.suse.cz> 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 14:11:03, Masayoshi Mizuma wrote: > Hello Michal, > > Mon, 19 Feb 2018 18:19:16 +0100 Michal Hocko wrote: > > 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? > > I have confirmed the problem is fixed by your patch 9bb5a391f9a5. > (I had tested it in 4.15.2, so I did not notice your patch, sorry) I have posted the backport for the 4.15 stable tree just an hour ago so it should appear in the next stable release. Thanks for double checking. -- 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