linux-kernel - Re: [PATCH v2] arm/memremap: fix arch_memremap_can_ram

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Message-ID: <Z_-B5fAhZzShX34I@arm.com>
Date: Wed, 16 Apr 2025 11:09:41 +0100
From: Catalin Marinas <catalin.marinas@....com>
To: Ross Stutterheim <ross.stutterheim@...min.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Russell King <linux@...linux.org.uk>,
	Mike Rapoport <rppt@...ux.ibm.com>, ross.sweng@...il.com,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v2] arm/memremap: fix arch_memremap_can_ram_remap()

On Mon, Apr 14, 2025 at 09:21:40AM -0500, Ross Stutterheim wrote:
> commit 260364d112bc ("arm[64]/memremap: don't abuse pfn_valid() to ensure
> presence of linear map") added the definition of
> arch_memremap_can_ram_remap() for arm[64] specific filtering of what pages
> can be used from the linear mapping. memblock_is_map_memory() was called
> with the pfn of the address given to arch_memremap_can_ram_remap();
> however, memblock_is_map_memory() expects to be given an address for arm,
> not a pfn.
> 
> This results in calls to memremap() returning a newly mapped area when
> it should return an address in the existing linear mapping.
> 
> Fix this by removing the address to pfn translation and pass the
> address directly.
> 
> Fixes: 260364d112bc ("arm[64]/memremap: don't abuse pfn_valid() to ensure presence of linear map")
> Signed-off-by: Ross Stutterheim <ross.stutterheim@...min.com>

I think you could also add:

Cc: <stable@...r.kernel.org>

> ---
>  arch/arm/mm/ioremap.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
> index 748698e91a4b..27e64f782cb3 100644
> --- a/arch/arm/mm/ioremap.c
> +++ b/arch/arm/mm/ioremap.c
> @@ -515,7 +515,5 @@ void __init early_ioremap_init(void)
>  bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size,
>  				 unsigned long flags)
>  {
> -	unsigned long pfn = PHYS_PFN(offset);
> -
> -	return memblock_is_map_memory(pfn);
> +	return memblock_is_map_memory(offset);
>  }

Reviewed-by: Catalin Marinas <catalin.marinas@....com>

Not sure how Russell picks patches up these days (I used to send them to
the patch system -
https://www.arm.linux.org.uk/developer/patches/info.php).

It might be simpler with git send-email (that's the alias I had):

  git send-email --add-header="KernelVersion: $(git describe --abbrev=0)" --no-thread --suppress-cc=all --to="patches@...linux.org.uk"

-- 
Catalin