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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E77E1C001B0 for ; Fri, 11 Aug 2023 08:36:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231939AbjHKIg3 (ORCPT ); Fri, 11 Aug 2023 04:36:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53840 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229447AbjHKIg1 (ORCPT ); Fri, 11 Aug 2023 04:36:27 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 626142737; Fri, 11 Aug 2023 01:36:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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=cJocosMaFpZJVLW25SbAxt5T2sdLdDBAbE/g/2G0uCE=; b=e3PI9VlwzTl5znPWffVTncxIuc zxr/n6yEjgQC9DwP0iff+gDBqpHgpDYwRIVbmjQT4a+rTUD2hSdrBo+q60rGhqEhU5hAMnynrtb6X c27nSbBss1GPcfuWS0hA0ez2Ots+WbnKpfi2Sl6PFPJDBF1DscqMQJf8oiWbD9q7pbnDeykbMzXpJ 6Hx7KHz0lpC+QIN2NCyiZAsYVU42h4OX8I7O5W4Yn/XincK95Crs9eQV6FS9REIzBoc0uERxbv7C4 MZVyTw7AOq/OTMzZqDpgJOEjsVdV8XZqY9juKbz5sYP1xJZtlvqIQdA+7QLyLN2BcIqNhSlif5Tok vQT3j9ug==; Received: from hch by bombadil.infradead.org with local (Exim 4.96 #2 (Red Hat Linux)) id 1qUNd8-009rjw-26; Fri, 11 Aug 2023 08:36:22 +0000 Date: Fri, 11 Aug 2023 01:36:22 -0700 From: Christoph Hellwig To: Richard Weinberger Cc: Christoph Hellwig , linux-mtd , Stephan Wurm , stable , Miquel Raynal , Vignesh Raghavendra , Oliver Neukum , Ali Akcaagac , Jamie Lenehan , James Bottomley , "Martin K. Petersen" , Ezequiel Garcia , linux-kernel , linux-scsi Subject: Re: [PATCH 1/7] ubi: block: Refactor sg list processing for highmem Message-ID: References: <20230810160019.16977-1-richard@nod.at> <20230810160019.16977-2-richard@nod.at> <298860961.5257332.1691684136772.JavaMail.zimbra@nod.at> <164102534.5258032.1691697286622.JavaMail.zimbra@nod.at> <156807159.5281174.1691742892935.JavaMail.zimbra@nod.at> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <156807159.5281174.1691742892935.JavaMail.zimbra@nod.at> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On Fri, Aug 11, 2023 at 10:34:52AM +0200, Richard Weinberger wrote: > ----- Ursprüngliche Mail ----- > > Von: "Christoph Hellwig" > > On Thu, Aug 10, 2023 at 09:54:46PM +0200, Richard Weinberger wrote: > >> > But why add the bounce buffering first if you can avoid it from the > >> > very beginning by just using kmap_local instead of adding a new > >> > caller for the deprecate kmap_atomic? > >> > >> Because I want this fix also in all stable trees. kmap_local() is rather > >> new. When back porting patch 1/7, bounce buffers and kmap_atomic() > >> are needed anyway. > >> By doing this in patch 1/7 I avoid backport troubles and keep the > >> delta between upstream and stable trees minimal. > > > > Just use plain kmap for the historic backports. > > Hm, yes. For UBIblock kmap should be too expensive. ? kmap is a no-op for !highmem. And it will always be way cheaper than bounce buffering for the case where you are actually fed highmem pages.