Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Fri, 11 Aug 2023 01:12:38 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Richard Weinberger <richard@nod.at>
Cc:     Christoph Hellwig <hch@infradead.org>,
        linux-mtd <linux-mtd@lists.infradead.org>,
        Stephan Wurm <stephan.wurm@a-eberle.de>,
        stable <stable@vger.kernel.org>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Oliver Neukum <oliver@neukum.org>,
        Ali Akcaagac <aliakc@web.de>,
        Jamie Lenehan <lenehan@twibble.org>,
        James Bottomley <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux-scsi <linux-scsi@vger.kernel.org>
Subject: Re: [PATCH 1/7] ubi: block: Refactor sg list processing for highmem
Message-ID: <ZNXtdpUbhj7mVu11@infradead.org>
References: <20230810160019.16977-1-richard@nod.at>
 <20230810160019.16977-2-richard@nod.at>
 <ZNUK8nWnUYB6B4Kg@infradead.org>
 <298860961.5257332.1691684136772.JavaMail.zimbra@nod.at>
 <ZNUOjQVivR/5pFKE@infradead.org>
 <164102534.5258032.1691697286622.JavaMail.zimbra@nod.at>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <164102534.5258032.1691697286622.JavaMail.zimbra@nod.at>
Precedence: bulk

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.