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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 48434C33CB1 for ; Fri, 17 Jan 2020 06:22:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D9E8720748 for ; Fri, 17 Jan 2020 06:22:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="db8Rl4/d" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D9E8720748 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6F2216B031D; Fri, 17 Jan 2020 01:22:53 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6A1846B031E; Fri, 17 Jan 2020 01:22:53 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5B9A66B031F; Fri, 17 Jan 2020 01:22:53 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0180.hostedemail.com [216.40.44.180]) by kanga.kvack.org (Postfix) with ESMTP id 4629D6B031D for ; Fri, 17 Jan 2020 01:22:53 -0500 (EST) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 09CA52492 for ; Fri, 17 Jan 2020 06:22:53 +0000 (UTC) X-FDA: 76386133026.04.box67_192120af4f30a X-HE-Tag: box67_192120af4f30a X-Filterd-Recvd-Size: 3512 Received: from mail-io1-f66.google.com (mail-io1-f66.google.com [209.85.166.66]) by imf13.hostedemail.com (Postfix) with ESMTP for ; Fri, 17 Jan 2020 06:22:52 +0000 (UTC) Received: by mail-io1-f66.google.com with SMTP id i7so16362871ioo.5 for ; Thu, 16 Jan 2020 22:22:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=XwLUJZGxFkMSoVpNxliazlIIzbpsW2148sEpST8u+Yk=; b=db8Rl4/dF9XIar2AJhlo4Y8SUz8QaZYSlQXLPFAK0ndTMynmx9/6qk33QFuW4RAqxv 9wteW93xo9Fr4cNUry0rNeMqjKHsIhDcyyiDhIdFwxBOoWJiuvExgE3OdPQGdCRVHzn/ eWzGc0JlL0RjJnlaZgKQ12mIHPd7bWwzoBkjLOzotQr6RPOWfSHG3WQi02BJFmOEWxj7 IhwcUKfRKF8URn15u6avVmbzFmGzxTNC3YX+ycKfcHM9/DLFb4m3sTEUQFuClqAv43zu tDC0QoE3ogBebEXYCmsTs7l4FcibIsJ2I8QSyVBIqcALK7b2bOXBXb3hZChUHs3TJKJ8 HjFQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=XwLUJZGxFkMSoVpNxliazlIIzbpsW2148sEpST8u+Yk=; b=byyGWeAuw/UhTAOhKSmMVcNjoIUvQ1n8282CfNoH5KtuLgzJVAH8BIzciV4sQmTW0D LYQUPwR4fK8GntTRXqbmlKD4ZllQ8kAIIPhRuMb2ranshmhtt301YVzDbRi6fKIMd4hR 6t8eyNQqXBEPnluufUKZoNGakqyZG1moaGiHQ4yjlKyAmFnpMPj/mEntiy40WcNsMcez xG7ALYKujxpyMMa0LO6R9/YkaN6pfJ0sFhQwWN9PJ0T86Uf03H9heWlYYDDRURROvwM5 yFCiZaAieJMHJFEvRLFbyUfL84uz3XPDcpgdiVT9tBpTfmeWpOdRkWq/oNkYa8WCUhed vXCw== X-Gm-Message-State: APjAAAXpRzGiMT+CEehg6zPXS7/cGmTy4JEr9D0QpTo3XffbiEPjYR5n //nPdVzRHoX/fLjLdki/bB7zWdCTkdpKo7B7vQ== X-Google-Smtp-Source: APXvYqwB2S65jUQUahjtxfTs1C6+gwrTURfJ6hjcgwDNyR9N0FcCh3XNsdRfU+Xha+f3+zxuFusl7PZFkxVEy3OQCBk= X-Received: by 2002:a5e:c244:: with SMTP id w4mr25542273iop.161.1579242172072; Thu, 16 Jan 2020 22:22:52 -0800 (PST) MIME-Version: 1.0 References: <1579143668-27941-1-git-send-email-kernelfans@gmail.com> <20200116075000.GM19428@dhcp22.suse.cz> In-Reply-To: <20200116075000.GM19428@dhcp22.suse.cz> From: Pingfan Liu Date: Fri, 17 Jan 2020 14:22:40 +0800 Message-ID: Subject: Re: [PATCH] mm/sparse: reset section's mem_map when fully deactivated To: Michal Hocko Cc: Dan Williams , Linux-MM , Andrew Morton , David Hildenbrand , Oscar Salvador , kexec@lists.infradead.org, Kazuhito Hagio Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000015, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jan 16, 2020 at 3:50 PM Michal Hocko wrote: > > On Thu 16-01-20 11:01:08, Pingfan Liu wrote: > > When fully deactivated, it is meaningless to keep the value of a section's > > mem_map. And its mem_map will be reassigned during re-added. > > > > Beside this, it breaks the user space tool "makedumpfile", which makes > > assumption that a hot-removed section having mem_map as NULL. > > We used to do that before ba72b4c8cf60 ("mm/sparsemem: support > sub-section hotplug"). Dan was this an intentional change? I do not know the purpose of this. But the change just leave section start pfn in fully deactivated section_mem_map, and not used any more. Thanks, Pingfan