linux-kernel - Re: [PATCH v8 14/16] ARM: LPAE: mark memory banks with start > ULONG

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Message-id: <alpine.LFD.2.02.1111091540450.3307@xanadu.home>
Date:	Wed, 09 Nov 2011 15:41:13 -0500 (EST)
From:	Nicolas Pitre <nico@...xnic.net>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Will Deacon <will.deacon@....com>
Subject: Re: [PATCH v8 14/16] ARM: LPAE: mark memory banks with start >
 ULONG_MAX as highmem

On Mon, 7 Nov 2011, Catalin Marinas wrote:

> From: Will Deacon <will.deacon@....com>
> 
> Memory banks living outside of the 32-bit physical address
> space do not have a 1:1 pa <-> va mapping and therefore the
> __va macro may wrap.
> 
> This patch ensures that such banks are marked as highmem so
> that the Kernel doesn't try to split them up when it sees that
> the wrapped virtual address overlaps the vmalloc space.
> 
> Signed-off-by: Will Deacon <will.deacon@....com>
> Signed-off-by: Catalin Marinas <catalin.marinas@....com>

Acked-by: Nicolas Pitre <nico@...aro.org>


> ---
>  arch/arm/mm/mmu.c |   16 +++++++++++++++-
>  1 files changed, 15 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index 1935311..b836d6b 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -799,6 +799,9 @@ void __init sanity_check_meminfo(void)
>  		struct membank *bank = &meminfo.bank[j];
>  		*bank = meminfo.bank[i];
>  
> +		if (bank->start > ULONG_MAX)
> +			highmem = 1;
> +
>  #ifdef CONFIG_HIGHMEM
>  		if (__va(bank->start) >= vmalloc_min ||
>  		    __va(bank->start) < (void *)PAGE_OFFSET)
> @@ -810,7 +813,7 @@ void __init sanity_check_meminfo(void)
>  		 * Split those memory banks which are partially overlapping
>  		 * the vmalloc area greatly simplifying things later.
>  		 */
> -		if (__va(bank->start) < vmalloc_min &&
> +		if (!highmem && __va(bank->start) < vmalloc_min &&
>  		    bank->size > vmalloc_min - __va(bank->start)) {
>  			if (meminfo.nr_banks >= NR_BANKS) {
>  				printk(KERN_CRIT "NR_BANKS too low, "
> @@ -831,6 +834,17 @@ void __init sanity_check_meminfo(void)
>  		bank->highmem = highmem;
>  
>  		/*
> +		 * Highmem banks not allowed with !CONFIG_HIGHMEM.
> +		 */
> +		if (highmem) {
> +			printk(KERN_NOTICE "Ignoring RAM at %.8llx-%.8llx "
> +			       "(!CONFIG_HIGHMEM).\n",
> +			       (unsigned long long)bank->start,
> +			       (unsigned long long)bank->start + bank->size - 1);
> +			continue;
> +		}
> +
> +		/*
>  		 * Check whether this memory bank would entirely overlap
>  		 * the vmalloc area.
>  		 */
> 
> --
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