linux-kernel - Re: [PATCH v2 2/9] mm: move __phys_to_pfn and __pfn_to_phys to asm/generic/memory

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Date:	Fri, 18 Sep 2015 16:42:16 -0700
From:	Tyler Baker <tyler.baker@...aro.org>
To:	Dan Williams <dan.j.williams@...el.com>
Cc:	linux-nvdimm@...ts.01.org, boaz@...xistor.com, david@...morbit.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	hch@....de, linux-mm@...ck.org, hpa@...or.com,
	ross.zwisler@...ux.intel.com, Ingo Molnar <mingo@...nel.org>,
	"Kevin's boot bot" <khilman@...nel.org>
Subject: Re: [PATCH v2 2/9] mm: move __phys_to_pfn and __pfn_to_phys to asm/generic/memory_model.h

Hi,

On 25 August 2015 at 18:27, Dan Williams <dan.j.williams@...el.com> wrote:
> From: Christoph Hellwig <hch@....de>
>
> Three architectures already define these, and we'll need them genericly
> soon.
>
> Signed-off-by: Christoph Hellwig <hch@....de>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
>  arch/arm/include/asm/memory.h       |    6 ------
>  arch/arm64/include/asm/memory.h     |    6 ------
>  arch/unicore32/include/asm/memory.h |    6 ------
>  include/asm-generic/memory_model.h  |    6 ++++++
>  4 files changed, 6 insertions(+), 18 deletions(-)
>
> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> index b7f6fb462ea0..98d58bb04ac5 100644
> --- a/arch/arm/include/asm/memory.h
> +++ b/arch/arm/include/asm/memory.h
> @@ -119,12 +119,6 @@
>  #endif
>
>  /*
> - * Convert a physical address to a Page Frame Number and back
> - */
> -#define        __phys_to_pfn(paddr)    ((unsigned long)((paddr) >> PAGE_SHIFT))
> -#define        __pfn_to_phys(pfn)      ((phys_addr_t)(pfn) << PAGE_SHIFT)
> -
> -/*
>   * Convert a page to/from a physical address
>   */
>  #define page_to_phys(page)     (__pfn_to_phys(page_to_pfn(page)))
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> index f800d45ea226..d808bb688751 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -81,12 +81,6 @@
>  #define __phys_to_virt(x)      ((unsigned long)((x) - PHYS_OFFSET + PAGE_OFFSET))
>
>  /*
> - * Convert a physical address to a Page Frame Number and back
> - */
> -#define        __phys_to_pfn(paddr)    ((unsigned long)((paddr) >> PAGE_SHIFT))
> -#define        __pfn_to_phys(pfn)      ((phys_addr_t)(pfn) << PAGE_SHIFT)
> -
> -/*
>   * Convert a page to/from a physical address
>   */
>  #define page_to_phys(page)     (__pfn_to_phys(page_to_pfn(page)))
> diff --git a/arch/unicore32/include/asm/memory.h b/arch/unicore32/include/asm/memory.h
> index debafc40200a..3bb0a29fd2d7 100644
> --- a/arch/unicore32/include/asm/memory.h
> +++ b/arch/unicore32/include/asm/memory.h
> @@ -61,12 +61,6 @@
>  #endif
>
>  /*
> - * Convert a physical address to a Page Frame Number and back
> - */
> -#define        __phys_to_pfn(paddr)    ((paddr) >> PAGE_SHIFT)
> -#define        __pfn_to_phys(pfn)      ((pfn) << PAGE_SHIFT)
> -
> -/*
>   * Convert a page to/from a physical address
>   */
>  #define page_to_phys(page)     (__pfn_to_phys(page_to_pfn(page)))
> diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
> index 14909b0b9cae..f20f407ce45d 100644
> --- a/include/asm-generic/memory_model.h
> +++ b/include/asm-generic/memory_model.h
> @@ -69,6 +69,12 @@
>  })
>  #endif /* CONFIG_FLATMEM/DISCONTIGMEM/SPARSEMEM */
>
> +/*
> + * Convert a physical address to a Page Frame Number and back
> + */
> +#define        __phys_to_pfn(paddr)    ((unsigned long)((paddr) >> PAGE_SHIFT))
> +#define        __pfn_to_phys(pfn)      ((pfn) << PAGE_SHIFT)

The kernelci.org bot has been reporting complete boot failures[1] on
ARM platforms with more than 4GB of memory and LPAE enabled. I've
bisected[2] the failures down to this commit, and reverting it on top
of the latest mainline resolves the boot issue. I took a closer look
at this patch and noticed the cast to phys_addr_t was dropped in the
generic function. Adding this to the new generic function solves the
boot issue I'm reporting.

diff --git a/include/asm-generic/memory_model.h
b/include/asm-generic/memory_model.h
index f20f407..db9f5c7 100644
--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -73,7 +73,7 @@
  * Convert a physical address to a Page Frame Number and back
  */
 #define        __phys_to_pfn(paddr)    ((unsigned long)((paddr) >> PAGE_SHIFT))
-#define        __pfn_to_phys(pfn)      ((pfn) << PAGE_SHIFT)
+#define        __pfn_to_phys(pfn)      ((phys_addr_t)(pfn) << PAGE_SHIFT)

 #define page_to_pfn __page_to_pfn
 #define pfn_to_page __pfn_to_page

If this fix is valid, I can send a formal patch or it can be squashed
into the original commit.

Cheers,

Tyler

[1] http://kernelci.org/boot/?d01&LPAE
[2] http://hastebin.com/tuhefudage.vhdl
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