Subject: Re: [PATCH net-next v6] page_pool: disable dma mapping support for 32-bit arch with 64-bit DMA

From: Christoph Hellwig <[email-masked]>
Date: Mon, 15 Nov 2021 10:53:12 -0800

On Mon, Nov 15, 2021 at 08:48:30PM +0200, Ilias Apalodimas wrote:
> page_pool (the API in question), apart from allocating memory can manage
> the mappings for you.  However while doing so it stores some parts (incl
> the dma addr) in struct page.  The code in there could be simplified if 
> we skipped support of the 'mapping' feature for 32-bit architectures with 
> 64-bit DMA.  We thought no driver was using the mapping feature (on 32bits)
> and cleaned up that part, but apparently we missed 
> '32-bit -- LPAE -- page pool manages DMA mappings'

It is a very common configuration on various architectures, so I fear
you'll have to support it and undo the cleanup.