Re: [PATCH 1/6] powerpc/mm/32: Use pfn_valid to check if pointer is in RAM

From: Jonathan NeuschÃfer
Date: Wed Feb 21 2018 - 09:45:19 EST


On Wed, Feb 21, 2018 at 02:51:19PM +0100, Jonathan NeuschÃfer wrote:
[...]
> While looking through arch/powerpc/mm, I noticed that there's a
> page_is_ram function, which simply uses the memblocks directly, on
> PPC32.

Oops, I misread the code here. memblock is used on PPC64.

> It seems like a good candidate for the RAM check in
> __ioremap_caller, except that there's this code, which apparently
> trashes memblock 0 completely on non-CONFIG_NEED_MULTIPLE_NODES:
>
> https://elixir.bootlin.com/linux/v4.16-rc2/source/arch/powerpc/mm/mem.c#L223
>
>
> Thanks,
> Jonathan NeuschÃfer


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