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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 38A03C10F0B for ; Tue, 26 Feb 2019 19:19:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0482121872 for ; Tue, 26 Feb 2019 19:19:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lca.pw header.i=@lca.pw header.b="kOSEEN/m" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728879AbfBZTTq (ORCPT ); Tue, 26 Feb 2019 14:19:46 -0500 Received: from mail-qt1-f195.google.com ([209.85.160.195]:45084 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727981AbfBZTTp (ORCPT ); Tue, 26 Feb 2019 14:19:45 -0500 Received: by mail-qt1-f195.google.com with SMTP id d18so16209314qtg.12 for ; Tue, 26 Feb 2019 11:19:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lca.pw; s=google; h=message-id:subject:from:to:cc:date:in-reply-to:references :mime-version:content-transfer-encoding; bh=GK4SfxpHL1TW7COE/Vay6DFmtSQUb3SQpYp/sxEryuI=; b=kOSEEN/mQlVE842b2oxlZn98OH6UUr8fe9rGWUi2TQmmVz/w+xcm4mJWpjzwIVxSSG Z5ZMti6XgNY00hCkh14bfQCXqATzNYLmpoYrwh8gb4kbaRb2dcwl3kQiM+ssCIh1z5// b7jIiv2nwipNu6Txhp9IsEmnlYzNp5pAcz3rdl5hin83RLQdm55iFXKEej6OmSC6b0IV ZwT49L1caPXLToKrePIImY55Lx0DJQwWUOj3ylYLeKVGHvzxJuOFIXN2Utpuekd7I1aD Hz+C+6ALeqy7Rq8kjI3FQ4XjrtJmbIONtjDThoiUMe6xnvnVDYGSkNZLOUG7RA0tsMJA jZfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:mime-version:content-transfer-encoding; bh=GK4SfxpHL1TW7COE/Vay6DFmtSQUb3SQpYp/sxEryuI=; b=uV4EI+VCRr4bhT3mMHJsgzyA/rAWS4vbluP3QlLcE4FinUakZ7s73RYuqtpJZXtkvV fsDxpGAccdXhULNYjeSXLw430JGMNQoRSL+iphd4CJEaTAQEPrr1db/4uZj9JyizGtDx /C3Z92xgFjPTCxTUGrxPqGb5sUbWIB/Mxg6hO4sizSyC0zw+EuFz3r59LFbxJq2VDxNP CvCB5d5vwPVJPENHlhk3Jfmf14lQoxO+vug+0iL9QfyjlnozV5sWatmbPhQIKYppquPr h9z96WfP8Vaue0ZF0Am0oW+vhVFlL/HRyZiX538bj1nQ7/6jqRVL0F1ZzAkQs/N4PR1H zwxg== X-Gm-Message-State: AHQUAuau4lw3qZSVmD6GwjLJjCqs+Ne84Fe0aFuPzh9vhLkK1XERBuSO 4J2ESVllU7JMmh8GcFDqtIfiv19HTUk= X-Google-Smtp-Source: AHgI3IYkmMFLwdW/jIteTI8bQIBaUYBhG9HD5Lwb5XOogW2UFF2P/XIQ56UhBknstq64zReANdUOYQ== X-Received: by 2002:ac8:22b6:: with SMTP id f51mr19277552qta.182.1551208784518; Tue, 26 Feb 2019 11:19:44 -0800 (PST) Received: from dhcp-41-57.bos.redhat.com (nat-pool-bos-t.redhat.com. [66.187.233.206]) by smtp.gmail.com with ESMTPSA id t38sm11324314qtc.12.2019.02.26.11.19.43 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 26 Feb 2019 11:19:43 -0800 (PST) Message-ID: <1551208782.6911.51.camel@lca.pw> Subject: Re: [PATCH] mm/hotplug: fix an imbalance with DEBUG_PAGEALLOC From: Qian Cai To: Michal Hocko Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Tue, 26 Feb 2019 14:19:42 -0500 In-Reply-To: <20190226182007.GH10588@dhcp22.suse.cz> References: <20190225191710.48131-1-cai@lca.pw> <20190226123521.GZ10588@dhcp22.suse.cz> <4d4d3140-6d83-6d22-efdb-370351023aea@lca.pw> <20190226142352.GC10588@dhcp22.suse.cz> <1551203585.6911.47.camel@lca.pw> <20190226181648.GG10588@dhcp22.suse.cz> <20190226182007.GH10588@dhcp22.suse.cz> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6 (3.22.6-10.el7) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2019-02-26 at 19:20 +0100, Michal Hocko wrote: > Btw. what happens if the offlined pfn range is removed completely? Is > the range still mapped? What kind of consequences does this have? Well, the pages are still marked as reserved as well, so it is up to the physically memory hotplug handler to free kernel direct mapping pagetable, virtual memory mapping pages, and virtual memory mapping pagetable as by design, although I have no way to test it. > Also when does this tweak happens on a completely new hotplugged memory > range? I suppose it will call online_pages() which in-turn call kernel_unmap_linear_page() which may or may not have the same issue, but I have no way to test that path.