From nobody Wed Feb 11 20:04:01 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 35BD1CD4F3B for ; Fri, 22 Sep 2023 09:15:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232992AbjIVJP4 (ORCPT ); Fri, 22 Sep 2023 05:15:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53452 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232954AbjIVJPq (ORCPT ); Fri, 22 Sep 2023 05:15:46 -0400 Received: from SHSQR01.spreadtrum.com (unknown [222.66.158.135]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A08541B2 for ; Fri, 22 Sep 2023 02:15:32 -0700 (PDT) Received: from dlp.unisoc.com ([10.29.3.86]) by SHSQR01.spreadtrum.com with ESMTP id 38M9FBK6033971; Fri, 22 Sep 2023 17:15:11 +0800 (+08) (envelope-from zhaoyang.huang@unisoc.com) Received: from SHDLP.spreadtrum.com (bjmbx01.spreadtrum.com [10.0.64.7]) by dlp.unisoc.com (SkyGuard) with ESMTPS id 4RsRNP2mzdz2SdWY0; Fri, 22 Sep 2023 17:11:49 +0800 (CST) Received: from bj03382pcu01.spreadtrum.com (10.0.73.40) by BJMBX01.spreadtrum.com (10.0.64.7) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Fri, 22 Sep 2023 17:15:10 +0800 From: "zhaoyang.huang" To: Russell King , Andrew Morton , Mike Rapoport , Matthew Wilcox , , , , Zhaoyang Huang , , Subject: [Resend PATCH] arch: arm: remove redundant clear_page when CONFIG_INIT_ON_ALLOC_DEFAULT_ON is on Date: Fri, 22 Sep 2023 17:15:05 +0800 Message-ID: <20230922091505.2196197-1-zhaoyang.huang@unisoc.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.0.73.40] X-ClientProxiedBy: SHCAS03.spreadtrum.com (10.0.1.207) To BJMBX01.spreadtrum.com (10.0.64.7) X-MAIL: SHSQR01.spreadtrum.com 38M9FBK6033971 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Zhaoyang Huang Double times of clear_page observed in an arm SOC(A55) when CONFIG_INIT_ON_ALLOC_DEFAULT_ON is on, which introduced by vma_alloc_zeroed_movable_folio within do_anonymous_pages. Since there is no D-cache operation within v6's clear_user_highpage, I would like to suggest to remove the redundant clear_page. struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, unsigned long vaddr) { struct folio *folio; //first clear_page invoked by vma_alloc_folio=3D=3D>alloc_page=3D=3D>post_a= lloc_hook folio =3D vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr, false); if (folio) //second clear_page which is meaningless since it do nothing to D-cache in = armv6 clear_user_highpage(&folio->page, vaddr); return folio; } PS: Here are all positions called clear_user_highpage which are paired with alloc_pages. IMO, it is safe to skip the second clear_page under armv6. drivers/media/v4l2-core/videobuf-dma-sg.c:441: clear_user_highpage(page, vmf->address); fs/dax.c:1612: clear_user_highpage(vmf->cow_page, vmf->address); include/linux/highmem.h:231: clear_user_highpage(&folio->page, vaddr); mm/memory.c:5974: clear_user_highpage(p, addr + i * PAGE_SIZE); mm/memory.c:5982: clear_user_highpage(page + idx, addr); mm/shmem.c:2621: clear_user_highpage(&folio->page, dst_addr); mm/khugepaged.c:796: clear_user_highpage(page, _address); Signed-off-by: Zhaoyang Huang --- arch/arm/mm/copypage-v6.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/arm/mm/copypage-v6.c b/arch/arm/mm/copypage-v6.c index a1a71f36d850..6f8bee1b3203 100644 --- a/arch/arm/mm/copypage-v6.c +++ b/arch/arm/mm/copypage-v6.c @@ -9,6 +9,7 @@ #include #include #include +#include =20 #include #include @@ -45,6 +46,13 @@ static void v6_copy_user_highpage_nonaliasing(struct pag= e *to, */ static void v6_clear_user_highpage_nonaliasing(struct page *page, unsigned= long vaddr) { + /* + * This criteria only help bailing out when CONFIG_INIT_ON_ALLOC_DEFAULT_= ON + * is on. The page has been memset to zero when it allocated and the + * bellowing clear_page will do it again. + */ + if (want_init_on_alloc(GFP_HIGHUSER_MOVABLE)) + return; void *kaddr =3D kmap_atomic(page); clear_page(kaddr); kunmap_atomic(kaddr); --=20 2.25.1