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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 06E47C4332B for ; Fri, 26 Feb 2021 01:17:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BDC2764F24 for ; Fri, 26 Feb 2021 01:17:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229863AbhBZBRb (ORCPT ); Thu, 25 Feb 2021 20:17:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:48640 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229885AbhBZBRU (ORCPT ); Thu, 25 Feb 2021 20:17:20 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3AE2C64F22; Fri, 26 Feb 2021 01:17:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1614302222; bh=PQqIjvtNkkK1K4SHTu5a6m0IhLTSsEshyXekogPqoaY=; h=Date:From:To:Subject:In-Reply-To:From; b=LCihsm8r6WEHyxWDDrSfhr8++zfznnGAgqbfqmfT5YD7DrZIIhoJowmi6QgwgG3iN KxJt+LQ1wbQt7OAKyWYY3pq3ZKHTHSzTiZBE6mUDVCFvque4+AmBHGEsKR1VIAUJPg HAr/B1SGlI63DK2/2eZO9xKxR48HYSorn0mGcsiA= Date: Thu, 25 Feb 2021 17:17:01 -0800 From: Andrew Morton To: akpm@linux-foundation.org, cai@lca.pw, dan.j.williams@intel.com, david@redhat.com, linux-mm@kvack.org, mhocko@suse.com, mm-commits@vger.kernel.org, naoya.horiguchi@nec.com, osalvador@suse.de, torvalds@linux-foundation.org Subject: [patch 027/118] mm: teach pfn_to_online_page() to consider subsection validity Message-ID: <20210226011701.hYlY8joRB%akpm@linux-foundation.org> In-Reply-To: <20210225171452.713967e96554bb6a53e44a19@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Dan Williams Subject: mm: teach pfn_to_online_page() to consider subsection validity pfn_to_online_page is primarily used to filter out offline or fully uninitialized pages. pfn_valid resp. online_section_nr have a coarse per memory section granularity. If a section shared with a partially offline memory (e.g. part of ZONE_DEVICE) then pfn_to_online_page would lead to a false positive on some pfns. Fix this by adding pfn_section_valid check which is subsection aware. [mhocko@kernel.org: changelog rewrite] Link: https://lkml.kernel.org/r/161058500148.1840162.4365921007820501696.stgit@dwillia2-desk3.amr.corp.intel.com Fixes: b13bc35193d9 ("mm/hotplug: invalid PFNs from pfn_to_online_page()") Signed-off-by: Dan Williams Reported-by: David Hildenbrand Reviewed-by: David Hildenbrand Reviewed-by: Oscar Salvador Acked-by: Michal Hocko Cc: Qian Cai Cc: Oscar Salvador Cc: Naoya Horiguchi Signed-off-by: Andrew Morton --- mm/memory_hotplug.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) --- a/mm/memory_hotplug.c~mm-teach-pfn_to_online_page-to-consider-subsection-validity +++ a/mm/memory_hotplug.c @@ -308,11 +308,26 @@ static int check_hotplug_memory_addressa struct page *pfn_to_online_page(unsigned long pfn) { unsigned long nr = pfn_to_section_nr(pfn); + struct mem_section *ms; - if (nr < NR_MEM_SECTIONS && online_section_nr(nr) && - pfn_valid_within(pfn)) - return pfn_to_page(pfn); - return NULL; + if (nr >= NR_MEM_SECTIONS) + return NULL; + + ms = __nr_to_section(nr); + if (!online_section(ms)) + return NULL; + + /* + * Save some code text when online_section() + + * pfn_section_valid() are sufficient. + */ + if (IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID) && !pfn_valid(pfn)) + return NULL; + + if (!pfn_section_valid(ms, pfn)) + return NULL; + + return pfn_to_page(pfn); } EXPORT_SYMBOL_GPL(pfn_to_online_page); _