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Date:   Thu, 10 Aug 2023 09:06:10 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Richard Weinberger <richard@nod.at>
Cc:     linux-mtd@lists.infradead.org,
        Christoph Hellwig <hch@infradead.org>,
        Stephan Wurm <stephan.wurm@a-eberle.de>,
        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 E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>,
        linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: [PATCH 1/7] ubi: block: Refactor sg list processing for highmem
Message-ID: <ZNUK8nWnUYB6B4Kg@infradead.org>
References: <20230810160019.16977-1-richard@nod.at>
 <20230810160019.16977-2-richard@nod.at>
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On Thu, Aug 10, 2023 at 06:00:12PM +0200, Richard Weinberger wrote:
> Currently sg_virt() is used while filling the sg list from LEB data.
> This approach cannot work with highmem.
> 
> Refactor ubi_eba_read_leb_sg() to use kmap_atomic() for sg list
> access.
> Since kmap_atomic() disables preempt a bounce buffer is needed.
> kmap_local_page() is not used to allow easy backporting of this patch
> to older kernels.
> 
> The followup patches in this series will switch to kmap_sg()
> and we can remove our own helper and the bounce buffer.

Please just use kmap_local and avoid the bounce buffering.