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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6EC4CA0EC3 for ; Tue, 12 Sep 2023 12:17:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E35DC6B009B; Tue, 12 Sep 2023 08:17:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DDC486B009C; Tue, 12 Sep 2023 08:17:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C7CDF6B00A1; Tue, 12 Sep 2023 08:17:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id B55FB6B009B for ; Tue, 12 Sep 2023 08:17:58 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 779081A0CB3 for ; Tue, 12 Sep 2023 12:17:58 +0000 (UTC) X-FDA: 81227847036.10.22B01EE Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf11.hostedemail.com (Postfix) with ESMTP id 3DFCA40021 for ; Tue, 12 Sep 2023 12:17:54 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=P2fGgS+N; spf=none (imf11.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1694521076; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=8/SJd7uAeq+C6xNw7E5T8lhkAqYav/AoZkSdrJ8MoKw=; b=kJzP5Qv9NFmWqjMQp0K23gtPRFYh0nHXPP2mBejgyB8GVouQfu9f7WCM9iwmgaNfe4pCNv wwmWw32W5qkSXEcqKuIHjte6N+naR8Gt6uCxFK4M4m+cOkYveFNaHoKOoOpfwEN7d0LFnz pkF9O/BECsiLq8BdmouddG/SfQc+0io= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1694521076; a=rsa-sha256; cv=none; b=z9xb7MsfRKoZb8izrk0zUKqpB2F5HOAurMmEpa77cWUbMtOx8G3mSQnAkv2qsg9hPfdkiO zLyMFrLWITEoKgBpq747LJB7aPTh/JnR/f0yZ6BNiA70uzASYtoUbtPHycCZQmb8PRaFCT rOZVQWpNNVcZPunciZdh16OiRmnP/ic= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=P2fGgS+N; spf=none (imf11.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=8/SJd7uAeq+C6xNw7E5T8lhkAqYav/AoZkSdrJ8MoKw=; b=P2fGgS+NSCITBCYpab2tKiIUMc ua7MWnLjEr4edXKkTTXlW+/r+64NTQ2mv0lAr0AxtCloRxXCIBWGoQkkkD7eg0sqkmj91m4+fYsaz j9gIivwbqeZPQ8QmQuUCdoH1C6Mf9cW/05ZsqgYDmpSj219sVDycFJ2cVmCPeejRv24IPXPG62CFa XzlxwgjORqVcyIzzIOSZHMRHNWKSjl96Ct7tzW/lWZDsT2zoKtw55G2peEHFLQNvjgFtEfcI60D79 igRA0Q8j+oMlorXeDYXwfSVMa3LSrqIMNymA6ibgXQN3P42C3YLQpmftSvAlYYHOYoiyPyS4JWGQH OJfY3RDQ==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qg2Ki-007VF8-0o; Tue, 12 Sep 2023 12:17:32 +0000 Date: Tue, 12 Sep 2023 13:17:31 +0100 From: Matthew Wilcox To: "zhaoyang.huang" Cc: Russell King , Andrew Morton , Mike Rapoport , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Zhaoyang Huang , ke.wang@unisoc.com Subject: Re: [PATCH] arch: arm: remove redundant clear_page when CONFIG_INIT_ON_ALLOC_DEFAULT_ON is on Message-ID: References: <20230912103334.2074140-1-zhaoyang.huang@unisoc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230912103334.2074140-1-zhaoyang.huang@unisoc.com> X-Rspamd-Queue-Id: 3DFCA40021 X-Rspam-User: X-Stat-Signature: mykn9m6gt3k5f9hkh7bb7t4z7n9q8wro X-Rspamd-Server: rspam03 X-HE-Tag: 1694521074-287667 X-HE-Meta: U2FsdGVkX18z0KZFZvqWMHKjOmFfVzUxa6o3OBG6edqt592Ewv9icnhcpCPvg8xVbHAoPF6B05doTTTy9hTpffF55MP0BqI35eXcTzNe4u80f4EwATKsUae+p+o1Ak0IfuQPO4ZwFQck+SNLhBVhN5HleGpeDq88dmLBcePQM+t0R14t7tqAvKBtQKnHy9gU7AXWIQYwrjynyOM4EQctBz/XEdyNj0iUEZqBBlvNIubwSNk0vCqNPFah0y7T5OSNT5uuRTmFsmspu4WQhnQkz+hwKmI+7TuY71X3C8xUdtwDrmMLq96TAuBoSwOGkCkRZc57Xm/epc3C08qFZOgPzdcJYDyaDdVwkzqGU95s/XKptW1ByaSCiubHt/NYaSfsbQyCxNBD0F5z28ugndf7asGqJQhcbxJOOQ90SqiNrI0Hu/vbQZXEVwA7t10QvrnZ4QQyU5x0k1yOqDM2mQCjEztdbl2iBshvvcF/dF71H+n2MrWnKmbb1nB3mZl0eKRthssJa1NnucMjGRNbEYHTCe2+KGXqPGi7Go/qQpP+xW42V/FF3hi2CECS2x+TG3MJNm4zeAcSw6gKIq1J051hRG0Qs1RATyBCc4fuMRAwTm4zyBOx+VodsrFo3+9TKXpJuHPOjXWINPzWYepOgUb0VV189H4i/OSKVUnSpruNg/DPddsmJvASjfVl4j5VU1Pm/L2xndXBOtEwqlsfrCcQvm8e7LFkJ44ABM/W05MZ+mIoIlVnAdiaVtWIExj6euvdb9E6t/b/JgVE2T5b3nJszWBRB/wUb9Akq/IJzSOVTRytPeqHlIBVavr1tJ+bi3LkXxjuNTcT0n+C8i29kAI+A1YT91waAFudV2ylm/d1Cb/rQ9f9vFEXBNaL6VBE7W50uOODEPjFwrMvs4jhEaKCtIMZSTSHZ1YoCJy80UiKgU4IfAOqgPnWFrHlmdx1SJzu8QE9UcUsndj+DHVUKgv 2bNxVb0S dxWT1ytIGcpgIfskwkHOl9SG7sY5txyFzuOEm4DHkTRGpooZF5pYndlShFLuyOCFwvig8NI7agJdheatl7ZroNc45GzbNOo1feFbzcCfRETAflZd7Q1kvGiSWgus1g/bj1cUuKLZ+njA1ePlKqqHGzjeNH/DJh8UJHyeK+WVsITAfUqYpylDRrpbLYHrKRXGER4sCDk1aPjiI1oZQoJl6E+EeQ8xLJVbb6rmreL2szE0PSXJb6uhCZp9dkjIxcsYUs8BGAbIIW1DLfsbnnkCkZCcRIA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Sep 12, 2023 at 06:33:34PM +0800, zhaoyang.huang wrote: > 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==>alloc_page==>post_alloc_hook > folio = 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); This is, of course, not the only place which calls clear_user_highpage(). Please explain why this patch is safe for all the _other_ places which call clear_user_highpage(). > return folio; > } > > 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 > > #include > #include > @@ -45,6 +46,13 @@ static void v6_copy_user_highpage_nonaliasing(struct page *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 = kmap_atomic(page); > clear_page(kaddr); > kunmap_atomic(kaddr); > -- > 2.25.1 >