linux-kernel - Re: [PATCH v2] dma-pool: Fix too large DMA pools on medium systems

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Message-ID: <alpine.DEB.2.22.394.2006081403560.71460@chino.kir.corp.google.com>
Date:   Mon, 8 Jun 2020 14:04:16 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
cc:     Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] dma-pool: Fix too large DMA pools on medium systems

On Mon, 8 Jun 2020, Geert Uytterhoeven wrote:

> On systems with at least 32 MiB, but less than 32 GiB of RAM, the DMA
> memory pools are much larger than intended (e.g. 2 MiB instead of 128
> KiB on a 256 MiB system).
> 
> Fix this by correcting the calculation of the number of GiBs of RAM in
> the system.  Invert the order of the min/max operations, to keep on
> calculating in pages until the last step, which aids readability.
> 
> Fixes: 1d659236fb43c4d2 ("dma-pool: scale the default DMA coherent pool size with memory capacity")
> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>

This works as well and is much more readable.  Thanks Geert!

Acked-by: David Rientjes <rientjes@...gle.com>