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 028FCC33CB1 for ; Fri, 17 Jan 2020 06:18:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B74332072B for ; Fri, 17 Jan 2020 06:18:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="uO+XXgKf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B74332072B 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 B3AEF6B0319; Fri, 17 Jan 2020 01:18:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id AEA836B031A; Fri, 17 Jan 2020 01:18:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A00C36B031B; Fri, 17 Jan 2020 01:18:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0154.hostedemail.com [216.40.44.154]) by kanga.kvack.org (Postfix) with ESMTP id 8523C6B0319 for ; Fri, 17 Jan 2020 01:18:52 -0500 (EST) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 346428248047 for ; Fri, 17 Jan 2020 06:18:52 +0000 (UTC) X-FDA: 76386122904.04.uncle78_879ab184b1223 X-HE-Tag: uncle78_879ab184b1223 X-Filterd-Recvd-Size: 4347 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 06:18:51 +0000 (UTC) Received: by mail-io1-f66.google.com with SMTP id n21so24753976ioo.10 for ; Thu, 16 Jan 2020 22:18:51 -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=+sWY+6H6Ge3PRBQAoLW7o/treDi43h4gtoyg3hrHzVo=; b=uO+XXgKfTX0JwNO7xbS+W8ikjyr5Yb4qw7ia0X6n8mANREZjh7TxPcy3W+3wjMk4BG B3gQWzef8MZvjtmx5+WZa/8wKbuPkuyYk6USe1sCo7Rn4GD1jMgVh/O1MVxOKJhUMdyT AhWZB3Y9hlOZuMJMufCzvo/SR+u15hf+gUUXxjBZEkHRM9EfGmwHlKh5W+/ycVOfeFOo AzHea2vWsZzbRDptajDPIw8j/ssaM+vEreURzkkP/efR48o2aa9X3c4Pvsljtar+It/a YOAW75rxGke2iSUaDZrL12FAk4vo7iiFx5cRbQKM68/YQa59UsyHQHrL+suMObbAzN9i 6SFA== 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=+sWY+6H6Ge3PRBQAoLW7o/treDi43h4gtoyg3hrHzVo=; b=b/fBCrQkSgSzOOgxbeAE6t8EywpUFssZUhIAExlyKDtgCcvqmT+qMXCZtVgNTdEPP7 feq7cx88gAEgIdqgHcG34SBUZo+rwzEeXHDL95AZ+uqt0LQgud3D+pVDGX9CQJrIrwZ+ 4b5D14oECjfzjRtrRUHU6hsv+D3/ZokvZAO7FWdPfAXycrOR9OFoFi5J/OAKUhAutvsk dGo3vDZEsynxbeF37iPDZxXkyzzvsWImP1Tl1vXwTy3EIfQiyJ77FnZRr8OeB2jNZPin XbmUrlb6IiGeotDccLtVqoPlaJXI9RXsacuZaPUpgXLJjTamQh4HBxm269thRi5QXm93 wIBw== X-Gm-Message-State: APjAAAVKki6qyDeiCQ+Ts6DDezElXqZZw4rtm2wS9PUQojx5gL6BPH8G 65/8U04n05z0N7fr+A+3ZvPHpG5hKHnsnO5FRw== X-Google-Smtp-Source: APXvYqxzbPfK+SOCUmaOe4Dusl/EvYz97eYGp2LEIDli1M4csp9A0UpImGieN24qOqqA1Swr32+ZtRMccDk4Yl10OOw= X-Received: by 2002:a6b:7e48:: with SMTP id k8mr26934888ioq.12.1579241931122; Thu, 16 Jan 2020 22:18:51 -0800 (PST) MIME-Version: 1.0 References: <1579143668-27941-1-git-send-email-kernelfans@gmail.com> <97ab281f-d038-d40c-648a-e0085a906dcf@redhat.com> In-Reply-To: <97ab281f-d038-d40c-648a-e0085a906dcf@redhat.com> From: Pingfan Liu Date: Fri, 17 Jan 2020 14:18:40 +0800 Message-ID: Subject: Re: [PATCH] mm/sparse: reset section's mem_map when fully deactivated To: David Hildenbrand Cc: Linux-MM , Andrew Morton , 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=0.000019, 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 4:06 PM David Hildenbrand wrote: > > On 16.01.20 04:01, 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. > > > > The bug can be reproduced on IBM POWERVM by "drmgr -c mem -r -q 5" , > > trigger a crash, and save vmcore by makedumpfile > > Are you using an up-to-date makedumfile and did kdump.service properly > get reloaded on the udev events? I remember that this works. I tried to get a machine and double-check it. The latest devel branch of makedumpfile can not work. > > makedumpfile will not dump memory sections that a) are not marked > offline (SECTION_IS_ONLINE) - after offlining b) are not part of an > iomem resource - after memory unplug. I think the current implementation of makedumpfile should improve the handling process. And my primary argument for this patch is a pattern like alloc/free. And when fully deactivated, it is meaningless to keep the section start pfn info > > > The current code makes sure that sparse_decode_mem_map() will return NULL. Do you mean the code in makedumpfile? If yes, it can. But makedumpfile related code has some bug, and should be improved to utilize this function. Thanks, Pingfan > > -- > Thanks, > > David / dhildenb >