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=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 2801BC433E6 for ; Fri, 15 Jan 2021 13:23:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EEBA923358 for ; Fri, 15 Jan 2021 13:23:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732511AbhAONWl (ORCPT ); Fri, 15 Jan 2021 08:22:41 -0500 Received: from mx2.suse.de ([195.135.220.15]:40810 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732113AbhAONWl (ORCPT ); Fri, 15 Jan 2021 08:22:41 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 606C5AD18; Fri, 15 Jan 2021 13:22:16 +0000 (UTC) Date: Fri, 15 Jan 2021 14:22:13 +0100 From: Oscar Salvador To: Muchun Song Cc: mike.kravetz@oracle.com, akpm@linux-foundation.org, n-horiguchi@ah.jp.nec.com, ak@linux.intel.com, mhocko@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v6 3/5] mm: hugetlb: fix a race between freeing and dissolving the page Message-ID: <20210115132209.GA10102@linux> References: <20210115124942.46403-1-songmuchun@bytedance.com> <20210115124942.46403-4-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210115124942.46403-4-songmuchun@bytedance.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Fri, Jan 15, 2021 at 08:49:40PM +0800, Muchun Song wrote: > There is a race condition between __free_huge_page() > and dissolve_free_huge_page(). > > CPU0: CPU1: > > // page_count(page) == 1 > put_page(page) > __free_huge_page(page) > dissolve_free_huge_page(page) > spin_lock(&hugetlb_lock) > // PageHuge(page) && !page_count(page) > update_and_free_page(page) > // page is freed to the buddy > spin_unlock(&hugetlb_lock) > spin_lock(&hugetlb_lock) > clear_page_huge_active(page) > enqueue_huge_page(page) > // It is wrong, the page is already freed > spin_unlock(&hugetlb_lock) > > The race windows is between put_page() and dissolve_free_huge_page(). > > We should make sure that the page is already on the free list > when it is dissolved. > > As a result __free_huge_page would corrupt page(s) already in the buddy > allocator. > > Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage") > Signed-off-by: Muchun Song > Reviewed-by: Mike Kravetz > Cc: stable@vger.kernel.org LGTM, Reviewed-by: Oscar Salvador -- Oscar Salvador SUSE L3