From nobody Wed Apr 29 09:34:31 2026 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 C62C2C43334 for ; Sat, 11 Jun 2022 02:14:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346873AbiFKCOA (ORCPT ); Fri, 10 Jun 2022 22:14:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55112 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229693AbiFKCN7 (ORCPT ); Fri, 10 Jun 2022 22:13:59 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 154A7240A9 for ; Fri, 10 Jun 2022 19:13:58 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4LKhBT220kzRhrQ; Sat, 11 Jun 2022 10:10:41 +0800 (CST) Received: from huawei.com (10.175.124.27) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Sat, 11 Jun 2022 10:13:49 +0800 From: Miaohe Lin To: CC: , , , Subject: [PATCH v2] mm/page_alloc: minor clean up for memmap_init_compound() Date: Sat, 11 Jun 2022 10:13:52 +0800 Message-ID: <20220611021352.13529-1-linmiaohe@huawei.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.175.124.27] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Since commit 5232c63f46fd ("mm: Make compound_pincount always available"), compound_pincount_ptr is stored at first tail page now. So we should call prep_compound_head() after the first tail page is initialized to take advantage of the likelihood of that tail struct page being cached given that we will read them right after in prep_compound_head(). Signed-off-by: Miaohe Lin Cc: Joao Martins --- v2: Don't move prep_compound_head() outside loop per Joao. --- mm/page_alloc.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 4c7d99ee58b4..048df5d78add 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6771,13 +6771,18 @@ static void __ref memmap_init_compound(struct page = *head, set_page_count(page, 0); =20 /* - * The first tail page stores compound_mapcount_ptr() and - * compound_order() and the second tail page stores - * compound_pincount_ptr(). Call prep_compound_head() after - * the first and second tail pages have been initialized to - * not have the data overwritten. + * The first tail page stores compound_mapcount_ptr(), + * compound_order() and compound_pincount_ptr(). Call + * prep_compound_head() after the first tail page have + * been initialized to not have the data overwritten. + * + * Note the idea to make this right after we initialize + * the offending tail pages is trying to take advantage + * of the likelihood of those tail struct pages being + * cached given that we will read them right after in + * prep_compound_head(). */ - if (pfn =3D=3D head_pfn + 2) + if (unlikely(pfn =3D=3D head_pfn + 1)) prep_compound_head(head, order); } } --=20 2.23.0