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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 4EFB7C433B4 for ; Thu, 29 Apr 2021 13:27:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A05361419 for ; Thu, 29 Apr 2021 13:27:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237433AbhD2N2A (ORCPT ); Thu, 29 Apr 2021 09:28:00 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:17050 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237130AbhD2N14 (ORCPT ); Thu, 29 Apr 2021 09:27:56 -0400 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4FWGRf6T3qzPvbj; Thu, 29 Apr 2021 21:23:58 +0800 (CST) Received: from huawei.com (10.175.104.170) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.498.0; Thu, 29 Apr 2021 21:26:59 +0800 From: Miaohe Lin To: CC: , , , , , , , , , , , , , Subject: [PATCH v2 5/5] mm/huge_memory.c: don't discard hugepage if other processes are mapping it Date: Thu, 29 Apr 2021 21:26:48 +0800 Message-ID: <20210429132648.305447-6-linmiaohe@huawei.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20210429132648.305447-1-linmiaohe@huawei.com> References: <20210429132648.305447-1-linmiaohe@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.104.170] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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 --- 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 af30338ac49c..87b0241394f4 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1607,7 +1607,7 @@ 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)) -- 2.23.0