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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 C2BC3C28EBD for ; Sun, 9 Jun 2019 09:16:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A1C6B20868 for ; Sun, 9 Jun 2019 09:16:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728007AbfFIJQa (ORCPT ); Sun, 9 Jun 2019 05:16:30 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:18117 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726686AbfFIJQa (ORCPT ); Sun, 9 Jun 2019 05:16:30 -0400 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 714EED491E95A3D71315; Sun, 9 Jun 2019 17:16:18 +0800 (CST) Received: from use12-sp2.huawei.com (10.67.188.190) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.439.0; Sun, 9 Jun 2019 17:16:08 +0800 From: ChenGang To: , , , , CC: , , , , , , ChenGang Subject: [PATCH] mm: align up min_free_kbytes to multipy of 4 Date: Sun, 9 Jun 2019 17:10:28 +0800 Message-ID: <1560071428-24267-1-git-send-email-cg.chen@huawei.com> X-Mailer: git-send-email 1.8.5.6 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.67.188.190] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Usually the value of min_free_kbytes is multiply of 4, and in this case ,the right shift is ok. But if it's not, the right-shifting operation will lose the low 2 bits, and this cause kernel don't reserve enough memory. So it's necessary to align the value of min_free_kbytes to multiply of 4. For example, if min_free_kbytes is 64, then should keep 16 pages, but if min_free_kbytes is 65 or 66, then should keep 17 pages. Signed-off-by: ChenGang --- mm/page_alloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d66bc8a..1baeeba 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7611,7 +7611,8 @@ static void setup_per_zone_lowmem_reserve(void) static void __setup_per_zone_wmarks(void) { - unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10); + unsigned long pages_min = + (PAGE_ALIGN(min_free_kbytes * 1024) / 1024) >> (PAGE_SHIFT - 10); unsigned long lowmem_pages = 0; struct zone *zone; unsigned long flags; -- 1.8.5.6