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From: Matthew Wilcox <willy@infradead.org>
To: Nicolas Boichat <drinkcat@chromium.org>
Cc: Will Deacon <will.deacon@arm.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Joerg Roedel <joro@8bytes.org>, Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@suse.com>,
	Mel Gorman <mgorman@techsingularity.net>,
	Levin Alexander <Alexander.Levin@microsoft.com>,
	Huaisheng Ye <yehs1@lenovo.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	linux-arm-kernel@lists.infradead.org,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, Yong Wu <yong.wu@mediatek.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Tomasz Figa <tfiga@google.com>,
	yingjoe.chen@mediatek.com, hch@infradead.org
Subject: Re: [PATCH v5 2/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging
Date: Fri, 7 Dec 2018 00:05:51 -0800	[thread overview]
Message-ID: <20181207080551.GA15120@bombadil.infradead.org> (raw)
In-Reply-To: <20181207061620.107881-3-drinkcat@chromium.org>

On Fri, Dec 07, 2018 at 02:16:19PM +0800, Nicolas Boichat wrote:
> +#ifdef CONFIG_ZONE_DMA32
> +#define ARM_V7S_TABLE_GFP_DMA GFP_DMA32
> +#define ARM_V7S_TABLE_SLAB_CACHE SLAB_CACHE_DMA32

This name doesn't make any sense.  Why not ARM_V7S_TABLE_SLAB_FLAGS ?

> +#else
> +#define ARM_V7S_TABLE_GFP_DMA GFP_DMA
> +#define ARM_V7S_TABLE_SLAB_CACHE SLAB_CACHE_DMA

Can you remind me again why it is, on machines which don't support
ZONE_DMA32, why we have to allocate from ZONE_DMA?  My understanding
is that 64-bit machines have ZONE_DMA32 and 32-bit machines don't.
So shouldn't this rather be GFP_KERNEL?

Actually, maybe we could centralise this in gfp.h:

#ifdef CONFIG_64BIT
# ifdef CONFIG_ZONE_DMA32
#define GFP_32BIT	GFP_DMA32
# else
#define GFP_32BIT	GFP_DMA
#else /* 32-bit */
#define GFP_32BIT	GFP_KERNEL
#endif


  reply	other threads:[~2018-12-07  8:06 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-07  6:16 [PATCH v5 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables Nicolas Boichat
2018-12-07  6:16 ` [PATCH v5 1/3] mm: Add support for kmem caches in DMA32 zone Nicolas Boichat
2018-12-07  7:25   ` Vlastimil Babka
2018-12-07  6:16 ` [PATCH v5 2/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging Nicolas Boichat
2018-12-07  8:05   ` Matthew Wilcox [this message]
2018-12-07  8:48     ` Nicolas Boichat
2018-12-07 15:01   ` Vlastimil Babka
2018-12-07  6:16 ` [PATCH v5 3/3] mm: Add /sys/kernel/slab/cache/cache_dma32 Nicolas Boichat

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