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 CB8E0C28B2B for ; Fri, 19 Aug 2022 18:29:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ECB9C8D0003; Fri, 19 Aug 2022 14:29:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E79848D0002; Fri, 19 Aug 2022 14:29:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D416A8D0003; Fri, 19 Aug 2022 14:29:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id C0F0E8D0002 for ; Fri, 19 Aug 2022 14:29:40 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 8D47914032B for ; Fri, 19 Aug 2022 18:29:40 +0000 (UTC) X-FDA: 79817180520.10.7D6952B Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf08.hostedemail.com (Postfix) with ESMTP id 7FCE516000F for ; Fri, 19 Aug 2022 18:29:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=tRmulA9MYitS9V7mq6tp/E2s8wqbaq1BnhDYkrBdwQ8=; b=OnHpY95+82flCzCoLXpUuAH1cy GRKLwKV1XlKXIH8FUN0CWnVsrrBckCchGW/AJv/VXovgjAUSCQsRbcmucPufPJ/QAnt+021O9pvy0 zUG83HHWb3Zz4ViVYznQRrURlv6X5VrAqxUqR6SYPMl7VNtuAr1bCaYWa6Iw4tlAo4oAX2gQ1P/Xt 4UWELuu8U4e2j5Dg1ZG4QtTz03mJ+gzwyMYLuMt0Xx1A5q3qjv8C4WcQkHXkSc86EeFSx415RhfQ2 38iH/L5yg8dSNxuSC8DsjQidbY2r6dLl1YxRjYygCJIVI1BH3lR2b38VdzdKVvU9QyLyFNU0LlXmX f8uOBXyQ==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1oP6kN-00BT8E-Iy; Fri, 19 Aug 2022 18:29:31 +0000 Date: Fri, 19 Aug 2022 19:29:31 +0100 From: Matthew Wilcox To: "Fabio M. De Francesco" Cc: linux-fscrypt@vger.kernel.org, Eric Biggers , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] fs-verity: use kmap_local_page() instead of kmap() Message-ID: References: <20220818224010.43778-1-ebiggers@kernel.org> <44912540.fMDQidcC6G@opensuse> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <44912540.fMDQidcC6G@opensuse> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660933780; a=rsa-sha256; cv=none; b=6MniEmXZUTw5AScqe0MZHSuEpa6JfQitHUEixKvSQhMaix7za207eNMU+NHUSgDUiZ9cgw dGgjn1l6qO0uba5Ze4A+n5Kk+AENuDmKBHUA4rgI0MT89RzIwFRHaPGrBxZX1ZtFuPyi6r Y2pDKBZ5ZehOXepSHmekfnjpM3CcZxI= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=OnHpY95+; dmarc=none; spf=none (imf08.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660933780; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=tRmulA9MYitS9V7mq6tp/E2s8wqbaq1BnhDYkrBdwQ8=; b=dH49SN3z5Xp0TAFcDmBLl1kgj+mChcibD+EPIIfvIl9l0DyHWjMbTUvpeD4yZGTNut0Mku +6DGrtgg6qWrj/yAXJ8u6aBMvSQBp4303UwrGZ/2Im/g7LiFp1cB/fRouW0XRPokNtmeXJ OXXN+pNoBYx25WVZN0toK3kGTVE/xeY= X-Stat-Signature: f8856e49kb3kjqy779y59ypi3uh11tuq X-Rspamd-Queue-Id: 7FCE516000F X-Rspam-User: Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=OnHpY95+; dmarc=none; spf=none (imf08.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Rspamd-Server: rspam11 X-HE-Tag: 1660933778-427526 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 Fri, Aug 19, 2022 at 09:50:37AM +0200, Fabio M. De Francesco wrote: > On venerd́ 19 agosto 2022 00:40:10 CEST Eric Biggers wrote: > > From: Eric Biggers > > > > Convert the use of kmap() to its recommended replacement > > kmap_local_page(). This avoids the overhead of doing a non-local > > mapping, which is unnecessary in this case. > > > > Signed-off-by: Eric Biggers > > --- > > fs/verity/read_metadata.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > It looks good to me... > > > - virt = kmap(page); > > + virt = kmap_local_page(page); > > if (copy_to_user(buf, virt + offs_in_page, bytes_to_copy)) > { > > - kunmap(page); > > + kunmap_local(virt); > > put_page(page); > > err = -EFAULT; > > break; > > } > > - kunmap(page); > > + kunmap_local(virt); Is this a common pattern? eg do we want something like: static inline int copy_user_page(void __user *dst, struct page *page, size_t offset, size_t len) { char *src = kmap_local_page(page) + offset; int err = 0; VM_BUG_ON(offset + len > PAGE_SIZE); if (copy_to_user(dst, src, len)) err = -EFAULT; kunmap_local(src); return err; } in highmem.h?