[PATCH v2 4/4] drivers: dma-coherent: use memset_io for DMA_MEMORY_IO mappings

[PATCH v2 0/4] Fix kernel panic in dma-coherent allocations · Brian Starkey <brian.starkey@arm.com> · 2016-02-29
[PATCH v2 1/4] memremap: don't modify flags · Brian Starkey <brian.starkey@arm.com> · 2016-02-29
[PATCH v2 2/4] memremap: add MEMREMAP_WC flag. · Brian Starkey <brian.starkey@arm.com> · 2016-02-29
[PATCH v2 3/4] drivers: dma-coherent: use MEMREMAP_WC for DMA_MEMORY_MAP · Brian Starkey <brian.starkey@arm.com> · 2016-02-29
[PATCH v2 4/4] drivers: dma-coherent: use memset_io for DMA_MEMORY_IO mappings · Brian Starkey <brian.starkey@arm.com> · 2016-02-29
Re: [PATCH v2 4/4] drivers: dma-coherent: use memset_io for DMA_MEMORY_IO mappings · Andrew Morton <akpm@linux-foundation.org> · 2016-02-29
Re: [PATCH v2 4/4] drivers: dma-coherent: use memset_io for DMA_MEMORY_IO mappings · Brian Starkey <brian.starkey@arm.com> · 2016-03-01

From: akpm@linux-foundation.org (Andrew Morton)
Date: 2016-02-29 23:17:52
Also in: lkml

On Mon, 29 Feb 2016 16:09:24 +0000 Brian Starkey [off-list ref] wrote:

Use memset_io() for DMA_MEMORY_IO mappings which are mapped as I/O
memory, and regular memset() for DMA_MEMORY_MAP mappings.

This fixes the below alignment fault on arm64 for DMA_MEMORY_IO
mappings, where memset() uses the DC ZVA instruction which is
invalid on device memory.

What's the urgency of this fix?  "Hair on fire needed in stable asap"
or "Nice to have in there for 4.6" or what?

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