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 584C9C33CAF for ; Thu, 16 Jan 2020 03:35:00 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1B227206B7 for ; Thu, 16 Jan 2020 03:35:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="GNLnRQ19" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1B227206B7 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 A22268E002F; Wed, 15 Jan 2020 22:34:59 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9D2778E0026; Wed, 15 Jan 2020 22:34:59 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8E8178E002F; Wed, 15 Jan 2020 22:34:59 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0029.hostedemail.com [216.40.44.29]) by kanga.kvack.org (Postfix) with ESMTP id 770468E0026 for ; Wed, 15 Jan 2020 22:34:59 -0500 (EST) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 43FE140C7 for ; Thu, 16 Jan 2020 03:34:59 +0000 (UTC) X-FDA: 76382081118.07.blade76_65b41113b6559 X-HE-Tag: blade76_65b41113b6559 X-Filterd-Recvd-Size: 3618 Received: from mail-io1-f65.google.com (mail-io1-f65.google.com [209.85.166.65]) by imf07.hostedemail.com (Postfix) with ESMTP for ; Thu, 16 Jan 2020 03:34:58 +0000 (UTC) Received: by mail-io1-f65.google.com with SMTP id k24so20186534ioc.4 for ; Wed, 15 Jan 2020 19:34:58 -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=sLuizv+Yo7c4/ciCV32rFJEwH3aLXYnRe90Mjxc/HW4=; b=GNLnRQ19jfiu9H2kHzCcdvzioqwHvQ5h+dUb/RkpLXTG4nTTyFImnBD5w3joOMA72V LWh+vqcTdUi4v5u+yGCBB4z+iBvXawiyzsBVYVkrtfLLehps1Mr50mUZd+2t17mvHpaR rxfsdnqHda7aELz8CoyWfGnnb59dqaD10EfAx03FRQk7FHdGc4hu0qHBXDInVLa8vckH 9DAHWf6WhseVuIL2UWa6OFmwzB0/GiXXcAALDSiy9Qy96fZlJoXOQrDEvABl2CgyCRAS sgwF6YaAsAEX1L83d9D59aGJivoWXN1OEyGjXV1g9xwkSk7VRc1oQoqLBdnj9zFjz1o4 Rrew== 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=sLuizv+Yo7c4/ciCV32rFJEwH3aLXYnRe90Mjxc/HW4=; b=nkgDVFsH4mf2XjqpU8jOW7wcsBsVh9CXcg5dpMh9RBBAr+v1/bHItepEHseqHwj75n qgGQMZ5ytzOHDc2FqLLubC/+xzlzrL2QUnm2LqKhQ/kNTIOiYJeYdm1x+Zkl53mX6uce pbCtOYYre/vicd0g94YLJP46yof2kpdGzg7FYELf/MD5KGL0E32r2ESWAzItFyDw3Ngc rrUqUqF6AFfl2Md+8jmfBZ9grJQ47lU3J34op4c7wtvuXXDGF8x8ClG4lRxDgZdLTQjp wh1aGHpQqhYoiAnPMBnBTo17+A6HWnhWvSNSUSimgoEaOpHlgwmzVlsrVAIcLq+iKB42 HuKw== X-Gm-Message-State: APjAAAUt75T/ihs6tyaLXrSxhg0tlpz+rrMYxNIIE/zERy8eiR31rRKR QhH4pHh79qOkrQEkzdpzJmwBevaIwCa2GKCIvUg6 X-Google-Smtp-Source: APXvYqyEOJeMyBCkjz2z1kMp6gMGpLVTWlVegN8vz1yTBS4evIQREvRP/Bx9BcTBLAh14ZCVuZ2hgmSdM1zzMfV6kv0= X-Received: by 2002:a5d:970e:: with SMTP id h14mr17270374iol.201.1579145698125; Wed, 15 Jan 2020 19:34:58 -0800 (PST) MIME-Version: 1.0 References: <1579143668-27941-1-git-send-email-kernelfans@gmail.com> In-Reply-To: From: Pingfan Liu Date: Thu, 16 Jan 2020 11:34:47 +0800 Message-ID: Subject: Re: [PATCH] mm/sparse: reset section's mem_map when fully deactivated To: Qian Cai Cc: Linux-MM , Andrew Morton , David Hildenbrand , Dan Williams , Oscar Salvador , Michal Hocko , kexec@lists.infradead.org, Kazuhito Hagio Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.039759, 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 11:18 AM Qian Cai wrote: > > > > > On Jan 15, 2020, at 10:01 PM, 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. > > Well, tools like makedumpfile and the crash utility always has to copy with ^^^ cope ? > low kernel implementation details changes like this. Why is it different this time? Yeah, there are two direction. But as the first argument, it is meaningless to keep the value. Thanks, Pingfan