From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19F8DC433DF for ; Mon, 22 Jun 2020 08:26:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B634720706 for ; Mon, 22 Jun 2020 08:26:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B634720706 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EE88C6B0002; Mon, 22 Jun 2020 04:26:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E99416B0005; Mon, 22 Jun 2020 04:26:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D88DE6B0006; Mon, 22 Jun 2020 04:26:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0153.hostedemail.com [216.40.44.153]) by kanga.kvack.org (Postfix) with ESMTP id C12386B0002 for ; Mon, 22 Jun 2020 04:26:50 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 6DB4E180AD817 for ; Mon, 22 Jun 2020 08:26:50 +0000 (UTC) X-FDA: 76956166980.17.ducks11_0f0de4326e31 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin17.hostedemail.com (Postfix) with ESMTP id 4B672180D0184 for ; Mon, 22 Jun 2020 08:26:50 +0000 (UTC) X-HE-Tag: ducks11_0f0de4326e31 X-Filterd-Recvd-Size: 5294 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) by imf04.hostedemail.com (Postfix) with ESMTP for ; Mon, 22 Jun 2020 08:26:48 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=richard.weiyang@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0U0KirUE_1592814395; Received: from localhost(mailfrom:richard.weiyang@linux.alibaba.com fp:SMTPD_---0U0KirUE_1592814395) by smtp.aliyun-inc.com(127.0.0.1); Mon, 22 Jun 2020 16:26:36 +0800 Date: Mon, 22 Jun 2020 16:26:35 +0800 From: Wei Yang To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , stable@vger.kernel.org, Andrew Morton , Johannes Weiner , Minchan Kim , Huang Ying , Wei Yang , Mel Gorman Subject: Re: [PATCH v2 1/3] mm/shuffle: don't move pages between zones and don't read garbage memmaps Message-ID: <20200622082635.GA93552@L-31X9LVDL-1304.local> Reply-To: Wei Yang References: <20200619125923.22602-1-david@redhat.com> <20200619125923.22602-2-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200619125923.22602-2-david@redhat.com> X-Rspamd-Queue-Id: 4B672180D0184 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Jun 19, 2020 at 02:59:20PM +0200, David Hildenbrand wrote: >Especially with memory hotplug, we can have offline sections (with a >garbage memmap) and overlapping zones. We have to make sure to only >touch initialized memmaps (online sections managed by the buddy) and that >the zone matches, to not move pages between zones. > >To test if this can actually happen, I added a simple > BUG_ON(page_zone(page_i) != page_zone(page_j)); >right before the swap. When hotplugging a 256M DIMM to a 4G x86-64 VM and >onlining the first memory block "online_movable" and the second memory >block "online_kernel", it will trigger the BUG, as both zones (NORMAL >and MOVABLE) overlap. > >This might result in all kinds of weird situations (e.g., double >allocations, list corruptions, unmovable allocations ending up in the >movable zone). > >Fixes: e900a918b098 ("mm: shuffle initial free memory to improve memory-side-cache utilization") >Acked-by: Michal Hocko >Cc: stable@vger.kernel.org # v5.2+ >Cc: Andrew Morton >Cc: Johannes Weiner >Cc: Michal Hocko >Cc: Minchan Kim >Cc: Huang Ying >Cc: Wei Yang >Cc: Mel Gorman >Signed-off-by: David Hildenbrand >--- > mm/shuffle.c | 18 +++++++++--------- > 1 file changed, 9 insertions(+), 9 deletions(-) > >diff --git a/mm/shuffle.c b/mm/shuffle.c >index 44406d9977c77..dd13ab851b3ee 100644 >--- a/mm/shuffle.c >+++ b/mm/shuffle.c >@@ -58,25 +58,25 @@ module_param_call(shuffle, shuffle_store, shuffle_show, &shuffle_param, 0400); > * For two pages to be swapped in the shuffle, they must be free (on a > * 'free_area' lru), have the same order, and have the same migratetype. > */ >-static struct page * __meminit shuffle_valid_page(unsigned long pfn, int order) >+static struct page * __meminit shuffle_valid_page(struct zone *zone, >+ unsigned long pfn, int order) > { >- struct page *page; >+ struct page *page = pfn_to_online_page(pfn); Hi, David and Dan, One thing I want to confirm here is we won't have partially online section, right? We can add a sub-section to system, but we won't manage it by buddy. With this confirmed: Reviewed-by: Wei Yang > > /* > * Given we're dealing with randomly selected pfns in a zone we > * need to ask questions like... > */ > >- /* ...is the pfn even in the memmap? */ >- if (!pfn_valid_within(pfn)) >+ /* ... is the page managed by the buddy? */ >+ if (!page) > return NULL; > >- /* ...is the pfn in a present section or a hole? */ >- if (!pfn_in_present_section(pfn)) >+ /* ... is the page assigned to the same zone? */ >+ if (page_zone(page) != zone) > return NULL; > > /* ...is the page free and currently on a free_area list? */ >- page = pfn_to_page(pfn); > if (!PageBuddy(page)) > return NULL; > >@@ -123,7 +123,7 @@ void __meminit __shuffle_zone(struct zone *z) > * page_j randomly selected in the span @zone_start_pfn to > * @spanned_pages. > */ >- page_i = shuffle_valid_page(i, order); >+ page_i = shuffle_valid_page(z, i, order); > if (!page_i) > continue; > >@@ -137,7 +137,7 @@ void __meminit __shuffle_zone(struct zone *z) > j = z->zone_start_pfn + > ALIGN_DOWN(get_random_long() % z->spanned_pages, > order_pages); >- page_j = shuffle_valid_page(j, order); >+ page_j = shuffle_valid_page(z, j, order); > if (page_j && page_j != page_i) > break; > } >-- >2.26.2 -- Wei Yang Help you, Help me