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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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,USER_AGENT_GIT 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 E8141C11F67 for ; Mon, 12 Jul 2021 06:32:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0A8D610A6 for ; Mon, 12 Jul 2021 06:32:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237538AbhGLGef (ORCPT ); Mon, 12 Jul 2021 02:34:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:52730 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236884AbhGLGa1 (ORCPT ); Mon, 12 Jul 2021 02:30:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E7B8160238; Mon, 12 Jul 2021 06:27:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626071258; bh=r9rqWIfKeAJHTT195H5cZemXLxSuOIhMnoNetkkxI88=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Lzo0Qzt1h4rhSgFOR5ioNxhe1KZTgG7CySZKP8i5x/d3Rz/MZaIS5UuqfNbbnrohI H2gDHTnLC/ojRgvqzJTZZ4agnD5aVASCbvEqexvCAQVZckSuIvBHcGJvC1hLncZ7mS p41cMNK2WzaNOPMnHC6p1DzcNrtx/k/9zJRt7IhY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yang Shi , Miaohe Lin , Alexey Dobriyan , "Aneesh Kumar K . V" , Anshuman Khandual , David Hildenbrand , Hugh Dickins , Johannes Weiner , "Kirill A. Shutemov" , Matthew Wilcox , Minchan Kim , Ralph Campbell , Rik van Riel , Song Liu , William Kucharski , Zi Yan , Mike Kravetz , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 5.4 340/348] mm/huge_memory.c: dont discard hugepage if other processes are mapping it Date: Mon, 12 Jul 2021 08:12:04 +0200 Message-Id: <20210712060749.204853687@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060659.886176320@linuxfoundation.org> References: <20210712060659.886176320@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miaohe Lin [ Upstream commit babbbdd08af98a59089334eb3effbed5a7a0cf7f ] If other processes are mapping any other subpages of the hugepage, i.e. in pte-mapped thp case, page_mapcount() will return 1 incorrectly. Then we would discard the page while other processes are still mapping it. Fix it by using total_mapcount() which can tell whether other processes are still mapping it. Link: https://lkml.kernel.org/r/20210511134857.1581273-6-linmiaohe@huawei.com Fixes: b8d3c4c3009d ("mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called") Reviewed-by: Yang Shi Signed-off-by: Miaohe Lin Cc: Alexey Dobriyan Cc: "Aneesh Kumar K . V" Cc: Anshuman Khandual Cc: David Hildenbrand Cc: Hugh Dickins Cc: Johannes Weiner Cc: Kirill A. Shutemov Cc: Matthew Wilcox Cc: Minchan Kim Cc: Ralph Campbell Cc: Rik van Riel Cc: Song Liu Cc: William Kucharski Cc: Zi Yan Cc: Mike Kravetz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/huge_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 87a07aa61be0..e50799d7002e 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1723,7 +1723,7 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, * If other processes are mapping this page, we couldn't discard * the page unless they all do MADV_FREE so let's skip the page. */ - if (page_mapcount(page) != 1) + if (total_mapcount(page) != 1) goto out; if (!trylock_page(page)) -- 2.30.2