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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 859FCC433E1 for ; Tue, 23 Jun 2020 21:48:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 612442078A for ; Tue, 23 Jun 2020 21:48:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PEpjg0qA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387817AbgFWVsu (ORCPT ); Tue, 23 Jun 2020 17:48:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37668 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387455AbgFWVsu (ORCPT ); Tue, 23 Jun 2020 17:48:50 -0400 Received: from mail-ej1-x644.google.com (mail-ej1-x644.google.com [IPv6:2a00:1450:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F40FDC061573 for ; Tue, 23 Jun 2020 14:48:49 -0700 (PDT) Received: by mail-ej1-x644.google.com with SMTP id ga4so252846ejb.11 for ; Tue, 23 Jun 2020 14:48:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:reply-to:references:mime-version :content-disposition:in-reply-to:user-agent; bh=gLCkBZXPIIeY1g45tslFWO+PD0hc5lFZOqXooZUlWH8=; b=PEpjg0qAPuLDlm5VvuUC6vrEb+6MoF8l1ACkYkcY2HqZwuoRNJMD27wb3HnDkODjtD 7kFpHy0BcQB2/OzA0cK5kmQTwI7kcUCl0JmvygO04JK875rulDjnePGKwoj5JnrZnKb+ ZjBmoLLWlGIZk7e19y2EEYvnIAHeQytiV1c+mF86BQpgvi5Zof6n4b3a3XpWN1YujICF TxQIIVKpvF/ldA5iEaPNRYG2kc84ZaWkO30cR9AOQ6GJcJ18KVDxU/sG006d4RdkMT2n hxkuTMg9n5Xe+jCG6LDOJrK7mqgBbra0811UUw7LXPpYU1ESywqo+8/7QWdTOi9s07wT 5RJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:reply-to :references:mime-version:content-disposition:in-reply-to:user-agent; bh=gLCkBZXPIIeY1g45tslFWO+PD0hc5lFZOqXooZUlWH8=; b=tPzx4ks+zhTutBe/khrEl0q+C3ysy/INopNYNQXyjEcEGIKhq84EFKNzUP7ZeOZdhe 6oa98hf+rSW39afcAcaEqWmjY93iZZvcOYLvhY6jhgGcTmJfeo0IIVK6sYOJqXYZDNf/ MFkJ/+2ZdQlMgiaBofRcFnDnWuQ285fZpRtEX2Z/vMqxHgAPwPkW/vEtccWtmSnRmjz4 WxMioGr6Y9OSeklgVrG7TSVeWJDkkCf9k9umc57dTSnwkQWbq+nxMJ7ETp8Jb5dH+xjd mthkNLG1ItJQuMFdSnfKonAAtCT9ZIrgV0f8Cviv/vhsXPVW1vJEysPeMNwC4xXvLsea PEZA== X-Gm-Message-State: AOAM530tdn6mE12ztLjnpXGM//OC0aBcgWMMJ3B0hZ3k+E8WiDKOLbOq bDdfEdCegTx05oFL5xjAD/g= X-Google-Smtp-Source: ABdhPJw15qKPA9jiRqrXuvtFIf8OYknB0rJ/6/dEZugcibFXL/7u/an+N7nb53QagI73h87/pd0zIA== X-Received: by 2002:a17:906:4989:: with SMTP id p9mr23153743eju.417.1592948928712; Tue, 23 Jun 2020 14:48:48 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id j16sm15428301edp.35.2020.06.23.14.48.47 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Tue, 23 Jun 2020 14:48:47 -0700 (PDT) Date: Tue, 23 Jun 2020 21:48:47 +0000 From: Wei Yang To: Michal Hocko Cc: Wei Yang , akpm@linux-foundation.org, osalvador@suse.de, dan.j.williams@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, david@redhat.com Subject: Re: [PATCH] mm/spase: never partially remove memmap for early section Message-ID: <20200623214847.fggchont44kgmvs6@master> Reply-To: Wei Yang References: <20200623094258.6705-1-richard.weiyang@linux.alibaba.com> <20200623151828.GA31426@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200623151828.GA31426@dhcp22.suse.cz> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 23, 2020 at 05:18:28PM +0200, Michal Hocko wrote: >On Tue 23-06-20 17:42:58, 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 > >Can a user trigger this or is this a theoretical bug? > I don't expect to have a non-section aligned system, so this is a theoretical bug to me. >> --- >> 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) > >This begs a comment. > Like: /* Only depopulate sub-section memmap for non early section. */ Looks good to you? >> depopulate_section_memmap(pfn, nr_pages, altmap); >> + else if (memmap) >> + free_map_bootmem(memmap); >> >> if (empty) >> ms->section_mem_map = (unsigned long)NULL; >> -- >> 2.20.1 (Apple Git-117) >> > >-- >Michal Hocko >SUSE Labs -- Wei Yang Help you, Help me