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 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 68ECEC433E1 for ; Tue, 23 Jun 2020 13:03:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 37AC920768 for ; Tue, 23 Jun 2020 13:03:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 37AC920768 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 BC9196B0008; Tue, 23 Jun 2020 09:03:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B79586B000A; Tue, 23 Jun 2020 09:03:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A8EFB6B000C; Tue, 23 Jun 2020 09:03:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0173.hostedemail.com [216.40.44.173]) by kanga.kvack.org (Postfix) with ESMTP id 972716B0008 for ; Tue, 23 Jun 2020 09:03:30 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 20205801A98D for ; Tue, 23 Jun 2020 13:03:30 +0000 (UTC) X-FDA: 76960492980.06.feet60_550315226e3b Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin06.hostedemail.com (Postfix) with ESMTP id A14D610055028 for ; Tue, 23 Jun 2020 13:02:17 +0000 (UTC) X-HE-Tag: feet60_550315226e3b X-Filterd-Recvd-Size: 3378 Received: from out30-57.freemail.mail.aliyun.com (out30-57.freemail.mail.aliyun.com [115.124.30.57]) by imf27.hostedemail.com (Postfix) with ESMTP for ; Tue, 23 Jun 2020 13:02:16 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R331e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01422;MF=richard.weiyang@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0U0W2oo1_1592917329; Received: from localhost(mailfrom:richard.weiyang@linux.alibaba.com fp:SMTPD_---0U0W2oo1_1592917329) by smtp.aliyun-inc.com(127.0.0.1); Tue, 23 Jun 2020 21:02:10 +0800 Date: Tue, 23 Jun 2020 21:02:09 +0800 From: Wei Yang To: David Hildenbrand Cc: Wei Yang , akpm@linux-foundation.org, osalvador@suse.de, dan.j.williams@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/spase: never partially remove memmap for early section Message-ID: <20200623130209.GA8347@L-31X9LVDL-1304.local> Reply-To: Wei Yang References: <20200623094258.6705-1-richard.weiyang@linux.alibaba.com> <414b4cbf-02f5-0e90-df92-c0889e9ad65b@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <414b4cbf-02f5-0e90-df92-c0889e9ad65b@redhat.com> X-Rspamd-Queue-Id: A14D610055028 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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 Tue, Jun 23, 2020 at 02:44:02PM +0200, David Hildenbrand wrote: >On 23.06.20 11:42, Wei Yang wrote: >> For early sections, we assumes its memmap will never be partially >> removed. But current behavior breaks this. >> >> Let's correct it. >> >> Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") >> Signed-off-by: Wei Yang >> --- >> mm/sparse.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/mm/sparse.c b/mm/sparse.c >> index b2b9a3e34696..1a0069f492f5 100644 >> --- a/mm/sparse.c >> +++ b/mm/sparse.c >> @@ -825,10 +825,10 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, >> ms->section_mem_map &= ~SECTION_HAS_MEM_MAP; >> } >> >> - if (section_is_early && memmap) >> - free_map_bootmem(memmap); >> - else >> + if (!section_is_early) >> depopulate_section_memmap(pfn, nr_pages, altmap); >> + else if (memmap) >> + free_map_bootmem(memmap); >> >> if (empty) >> ms->section_mem_map = (unsigned long)NULL; >> > >Agreed, that's what pfn_valid() and section_activate() expect. > >"If we hot-add memory into such a section then we do not need to >populate the memmap and can simply reuse what is already there." - this >is the case when hot-adding sub-sections into partially populated early >sections, and has to be the case when re-hot-adding after hot-removing. > >Acked-by: David Hildenbrand > > >I am also not convinced that the complicated sparse_decode_mem_map() >handling in that function is required - ms->section_mem_map & >SECTION_MAP_MASK is sufficient for this use case of removing the memmap >of a full early section once empty. > You mean remove this line? memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr); Then what to passed to free_map_bootmem() ? >-- >Thanks, > >David / dhildenb -- Wei Yang Help you, Help me