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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,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 CCA3EC4320A for ; Sun, 15 Aug 2021 06:23:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AAD476103D for ; Sun, 15 Aug 2021 06:23:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231998AbhHOGXp (ORCPT ); Sun, 15 Aug 2021 02:23:45 -0400 Received: from out30-44.freemail.mail.aliyun.com ([115.124.30.44]:50583 "EHLO out30-44.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229633AbhHOGXo (ORCPT ); Sun, 15 Aug 2021 02:23:44 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0Uj0RWdi_1629008593; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Uj0RWdi_1629008593) by smtp.aliyun-inc.com(127.0.0.1); Sun, 15 Aug 2021 14:23:13 +0800 From: Baolin Wang To: akpm@linux-foundation.org Cc: apopple@nvidia.com, shy828301@gmail.com, willy@infradead.org, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/4] mm: migrate: Move the page count validation to the proper place Date: Sun, 15 Aug 2021 14:23:03 +0800 Message-Id: <644a666e1e177c57a39a4c37c6e2ca64052b9d7e.1629008158.git.baolin.wang@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: References: In-Reply-To: References: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We've got the expected count for anonymous page or file page by expected_page_refs() at the beginning of migrate_page_move_mapping(), thus we should move the page count validation a little forward to reduce duplicated code. Moreover the i_pages lock is not used to guarantee the page refcount safety in migrate_page_move_mapping(), so we can move the getting page count out of the i_pages lock. Since now the migration page has established a migration pte under the page lock now, with the page refcount freezing validation, to ensure that the page references meet the migration requirement. Signed-off-by: Baolin Wang --- mm/migrate.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index c6eb2a8..8e9282f 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -386,11 +386,10 @@ int folio_migrate_mapping(struct address_space *mapping, int expected_count = expected_page_refs(mapping, &folio->page) + extra_count; long nr = folio_nr_pages(folio); - if (!mapping) { - /* Anonymous page without mapping */ - if (folio_ref_count(folio) != expected_count) - return -EAGAIN; + if (folio_ref_count(folio) != expected_count) + return -EAGAIN; + if (!mapping) { /* No turning back from here */ newfolio->index = folio->index; newfolio->mapping = folio->mapping; @@ -404,8 +403,7 @@ int folio_migrate_mapping(struct address_space *mapping, newzone = folio_zone(newfolio); xas_lock_irq(&xas); - if (folio_ref_count(folio) != expected_count || - xas_load(&xas) != folio) { + if (xas_load(&xas) != folio) { xas_unlock_irq(&xas); return -EAGAIN; } -- 1.8.3.1