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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 192E8C433F5 for ; Wed, 1 Jun 2022 12:23:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231854AbiFAMXn (ORCPT ); Wed, 1 Jun 2022 08:23:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346708AbiFAMXb (ORCPT ); Wed, 1 Jun 2022 08:23:31 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2783A3B3E2 for ; Wed, 1 Jun 2022 05:23:28 -0700 (PDT) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4LCpDC2Bw4z1K9BD; Wed, 1 Jun 2022 20:21:47 +0800 (CST) Received: from dggpemm500002.china.huawei.com (7.185.36.229) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 1 Jun 2022 20:23:27 +0800 Received: from localhost.localdomain (10.175.112.125) by dggpemm500002.china.huawei.com (7.185.36.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 1 Jun 2022 20:23:26 +0800 From: Chen Wandun To: , , , CC: Subject: [PATCH 4/4] mm/shmem: rework calculation of inflated_addr in shmem_get_unmapped_area Date: Wed, 1 Jun 2022 20:44:17 +0800 Message-ID: <20220601124417.2872001-5-chenwandun@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220601124417.2872001-1-chenwandun@huawei.com> References: <20220601124417.2872001-1-chenwandun@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.112.125] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500002.china.huawei.com (7.185.36.229) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In function shmem_get_unmapped_area, inflated_offset and offset are unsigned long, it will result in underflow when offset below inflated_offset, a little confusing, no functional change. Signed-off-by: Chen Wandun --- mm/shmem.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index ca04f3975a8a..f12163bd0f69 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2201,9 +2201,12 @@ unsigned long shmem_get_unmapped_area(struct file *file, return addr; inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1); - inflated_addr += offset - inflated_offset; - if (inflated_offset > offset) + if (offset > inflated_offset) + inflated_addr += offset - inflated_offset; + else if (offset < inflated_offset) { + inflated_addr -= inflated_offset - offset; inflated_addr += HPAGE_PMD_SIZE; + } if (inflated_addr > TASK_SIZE - len) return addr; -- 2.25.1