From patchwork Tue Apr 27 13:32:14 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miaohe Lin X-Patchwork-Id: 12226761 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=-16.8 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 3653CC433ED for ; Tue, 27 Apr 2021 13:32:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C06536113D for ; Tue, 27 Apr 2021 13:32:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C06536113D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 668826B0072; Tue, 27 Apr 2021 09:32:39 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 393F86B0075; Tue, 27 Apr 2021 09:32:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 172B56B0071; Tue, 27 Apr 2021 09:32:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0187.hostedemail.com [216.40.44.187]) by kanga.kvack.org (Postfix) with ESMTP id BA25D6B0073 for ; Tue, 27 Apr 2021 09:32:38 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 6FBB3824999B for ; Tue, 27 Apr 2021 13:32:38 +0000 (UTC) X-FDA: 78078236796.11.EA7346C Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) by imf30.hostedemail.com (Postfix) with ESMTP id 7EECBE0011CE for ; Tue, 27 Apr 2021 13:32:18 +0000 (UTC) Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4FV2fv5tX1zPtFQ; Tue, 27 Apr 2021 21:29:27 +0800 (CST) Received: from huawei.com (10.175.104.170) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.498.0; Tue, 27 Apr 2021 21:32:26 +0800 From: Miaohe Lin To: CC: , , , , , , , , , , , , , Subject: [PATCH 5/5] mm/huge_memory.c: don't discard hugepage if other processes are mapping it Date: Tue, 27 Apr 2021 21:32:14 +0800 Message-ID: <20210427133214.2270207-6-linmiaohe@huawei.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20210427133214.2270207-1-linmiaohe@huawei.com> References: <20210427133214.2270207-1-linmiaohe@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.104.170] X-CFilter-Loop: Reflected X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 7EECBE0011CE X-Stat-Signature: utj1esbojh64twe436q6mur1k6ir9y8h Received-SPF: none (huawei.com>: No applicable sender policy available) receiver=imf30; identity=mailfrom; envelope-from=""; helo=szxga05-in.huawei.com; client-ip=45.249.212.191 X-HE-DKIM-Result: none/none X-HE-Tag: 1619530338-524806 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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") Signed-off-by: Miaohe Lin Reviewed-by: Yang Shi --- 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 f652be6ecca3..d14fecb8cd00 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1604,7 +1604,7 @@ 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))