From: Nicolin Chen <nicoleotsuka@gmail.com>
To: Christoph Hellwig <hch@lst.de>
Cc: robin.murphy@arm.com, vdumpa@nvidia.com, linux@armlinux.org.uk,
catalin.marinas@arm.com, will.deacon@arm.com, joro@8bytes.org,
m.szyprowski@samsung.com, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
tony@atomide.com
Subject: Re: [PATCH v2 RFC/RFT 1/5] ARM: dma-mapping: Add fallback normal page allocations
Date: Wed, 24 Apr 2019 11:33:11 -0700 [thread overview]
Message-ID: <20190424183310.GA6168@Asurada-Nvidia.nvidia.com> (raw)
In-Reply-To: <20190424150638.GA22191@lst.de>
Hi Christoph,
On Wed, Apr 24, 2019 at 05:06:38PM +0200, Christoph Hellwig wrote:
> On Tue, Mar 26, 2019 at 04:01:27PM -0700, Nicolin Chen wrote:
> > page = dma_alloc_from_contiguous(dev, count, order, gfp & __GFP_NOWARN);
> > + if (!page)
> > + page = alloc_pages(gfp, order);
>
> We have this fallback in most callers already. And with me adding
> it to the dma-iommu code in one series, and you to arm here I think
> we really need to take a step back and think of a better way
> to handle this, and the general mess that dma_alloc_from_contiguous.
>
> So what about:
Thanks for the suggestion!
> (1) change the dma_alloc_from_contiguous prototype to be:
>
> struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp);
>
> that is: calculate order and count internally, pass the full gfp_t
> and mask it internally, and drop the pointless from in the name.
> I'd also use the oppurtunity to forbid a NULL dev argument and
> opencode those uses.
>
> (2) handle the alloc_pages fallback internally. Note that we should
> use alloc_pages_node as we do in dma-direct.
I feel it's similar to my previous set, which did most of these
internally except the renaming part. But Catalin had a concern
that some platforms might have limits on CMA range [1]. Will it
be still okay to do the fallback internally?
[1: https://www.spinics.net/lists/arm-kernel/msg714295.html ]
next prev parent reply other threads:[~2019-04-24 18:33 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-26 23:01 [PATCH v2 RFC/RFT 0/5] Save single pages from CMA area Nicolin Chen
2019-03-26 23:01 ` [PATCH v2 RFC/RFT 1/5] ARM: dma-mapping: Add fallback normal page allocations Nicolin Chen
2019-04-24 15:06 ` Christoph Hellwig
2019-04-24 15:08 ` Christoph Hellwig
2019-04-24 18:33 ` Nicolin Chen [this message]
2019-04-24 19:26 ` Christoph Hellwig
2019-04-24 19:38 ` Nicolin Chen
2019-04-30 15:24 ` Catalin Marinas
2019-05-02 13:26 ` Christoph Hellwig
2019-04-26 20:21 ` Nicolin Chen
2019-04-26 20:25 ` Christoph Hellwig
2019-03-26 23:01 ` [PATCH v2 RFC/RFT 2/5] dma-remap: Run alloc_pages() on failure Nicolin Chen
2019-03-26 23:01 ` [PATCH v2 RFC/RFT 3/5] iommu: amd_iommu: Add fallback normal page allocations Nicolin Chen
2019-03-26 23:01 ` [PATCH v2 RFC/RFT 4/5] arm64: dma-mapping: " Nicolin Chen
2019-03-26 23:01 ` [PATCH v2 RFC/RFT 5/5] dma-contiguous: Do not allocate a single page from CMA area Nicolin Chen
2019-03-27 8:08 ` [PATCH v2 RFC/RFT 0/5] Save single pages " Christoph Hellwig
2019-03-27 18:42 ` Nicolin Chen
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