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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 55DF8C352A4 for ; Mon, 10 Feb 2020 23:05:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1FF59206D6 for ; Mon, 10 Feb 2020 23:05:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1FF59206D6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9DEB16B018F; Mon, 10 Feb 2020 18:05:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 967DA6B0191; Mon, 10 Feb 2020 18:05:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 82F3E6B0192; Mon, 10 Feb 2020 18:05:24 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0215.hostedemail.com [216.40.44.215]) by kanga.kvack.org (Postfix) with ESMTP id 683066B018F for ; Mon, 10 Feb 2020 18:05:24 -0500 (EST) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 1558C249B for ; Mon, 10 Feb 2020 23:05:24 +0000 (UTC) X-FDA: 76475750568.23.trail93_865d17d4ff463 X-HE-Tag: trail93_865d17d4ff463 X-Filterd-Recvd-Size: 4740 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by imf07.hostedemail.com (Postfix) with ESMTP for ; Mon, 10 Feb 2020 23:05:23 +0000 (UTC) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Feb 2020 15:05:21 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,426,1574150400"; d="scan'208";a="433485952" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by fmsmga006.fm.intel.com with ESMTP; 10 Feb 2020 15:05:19 -0800 Date: Tue, 11 Feb 2020 07:05:37 +0800 From: Wei Yang To: Baoquan He Cc: Wei Yang , linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, dan.j.williams@intel.com, david@redhat.com Subject: Re: [PATCH 7/7] mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case Message-ID: <20200210230537.GA32495@richard> Reply-To: Wei Yang References: <20200209104826.3385-1-bhe@redhat.com> <20200209104826.3385-8-bhe@redhat.com> <20200209235202.GC8705@richard> <20200210034105.GA8965@MiWiFi-R3L-srv> <20200210060804.GF7326@richard> <20200210075406.GE8965@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200210075406.GE8965@MiWiFi-R3L-srv> User-Agent: Mutt/1.9.4 (2018-02-28) 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 Mon, Feb 10, 2020 at 03:54:06PM +0800, Baoquan He wrote: >On 02/10/20 at 02:08pm, Wei Yang wrote: >> On Mon, Feb 10, 2020 at 11:41:05AM +0800, Baoquan He wrote: >> >On 02/10/20 at 07:52am, Wei Yang wrote: >> >> >--- >> >> > mm/sparse.c | 4 +++- >> >> > 1 file changed, 3 insertions(+), 1 deletion(-) >> >> > >> >> >diff --git a/mm/sparse.c b/mm/sparse.c >> >> >index 623755e88255..345d065ef6ce 100644 >> >> >--- a/mm/sparse.c >> >> >+++ b/mm/sparse.c >> >> >@@ -854,13 +854,15 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, >> >> > ms->usage = NULL; >> >> > } >> >> > memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr); >> >> >- ms->section_mem_map = (unsigned long)NULL; >> >> > } >> >> > >> >> > if (section_is_early && memmap) >> >> > free_map_bootmem(memmap); >> >> > else >> >> > depopulate_section_memmap(pfn, nr_pages, altmap); >> >> >> >> The crash happens in depopulate_section_memmap() when trying to get memmap by >> >> pfn_to_page(). Can we pass memmap directly? >> > >> >Yes, that's also a good idea. While it needs to add a parameter for >> >depopulate_section_memmap(), the parameter is useless for VMEMMAP >> >though, I personally prefer the current fix which is a little simpler. >> > >> >> Not a new parameter, but replace pfn with memmap. >> >> Not sure why the parameter is useless for VMEMMAP? memmap will be assigned to >> start and finally pass to vmemmap_free(). > >In section_deactivate(), per the code comments from Dan, we can know >that: > > /* > * section which only contains bootmem will be handled by > * free_map_bootmem(), including a complete section, or partial > * section which only has memory starting from the begining. > */ > if (section_is_early && memmap) > free_map_bootmem(memmap); > else > /* > * section which contains region mixing bootmem with hot added > * sub-section region, only sub-section region, complete > * section. And in the mxied case, if hot remove the hot added > * sub-section aligned part, no memmap is got in the current > * code. So we still need pfn to calculate it for vmemmap case. > * To me, whenever we need, it looks better that we always use > * pfn to get its own memmap. > */ > depopulate_section_memmap(pfn, nr_pages, altmap); > >This is why I would like to keep the current logic as is,only one line >of code adjusting can fix the issue. Please let me know if I miss >anything. > You are right. I missed this point. > >> >> >Anyway, both is fine to me, I can update if you think passing memmap is >> >better. >> > >> >> >> >> >+ >> >> >+ if(!rc) >> >> >+ ms->section_mem_map = (unsigned long)NULL; >> >> > } >> >> > >> >> > static struct page * __meminit section_activate(int nid, unsigned long pfn, >> >> >-- >> >> >2.17.2 >> >> >> >> -- >> >> Wei Yang >> >> Help you, Help me >> >> >> >> -- >> Wei Yang >> Help you, Help me >> -- Wei Yang Help you, Help me