linux-kernel - Re: [PATCH] x86: avoid unnecessary low zone allocation in AMD IOMMU's alloc

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Date:	Wed, 10 Sep 2008 14:18:35 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Joerg Roedel <joerg.roedel@....com>
Cc:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: avoid unnecessary low zone allocation in AMD
	IOMMU's alloc_coherent


* Joerg Roedel <joerg.roedel@....com> wrote:

> > +	get_device_resources(dev, &iommu, &domain, &devid);
> > +
> > +	if (iommu && domain)
> > +		flag &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
> > +
> 
> These flags are already removed in the dma_alloc_coherent function 
> which calls this one. Further I think in the case of a remapping IOMMU 
> like this one we should avoid implementing any gfp hacks and just 
> trust the caller.

or add a WARN_ON_ONCE() instead, to document and enforce that 
assumption.

	Ingo
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