[PATCH] arm: mm: Fix vmalloc overlap check for !HIGHMEM

[Nicolas Pitre]

On Fri, 17 Aug 2012, Jonathan Austin wrote:

> With !HIGHMEM, sanity_check_meminfo checks for banks that completely or
> partially overlap the vmalloc region. The test for partial overlap checks
> __va(bank->start + bank->size) > vmalloc_min. This is not appropriate if
> there is a non-linear translation between virtual and physical addresses,
> as bank->start + bank->size is actually in the bank following the one being
> interrogated.
> 
> In most cases, even when using SPARSEMEM, this is not problematic as the
> subsequent bank will start at a higher va than the one in question. However
> if the physical to virtual address conversion is not monotonic increasing,
> the incorrect test could result in a bank not being truncated when it
> should be.
> 
> This patch ensures we perform the va-pa conversion on memory from the
> bank we are interested in, not the following one.
> 
> Reported-by: 湛振波 (Steve) <zhanzhenbo at gmail.com>
> Signed-off-by: Jonathan Austin <jonathan.austin at arm.com>

Acked-by: Nicolas Pitre <nico at linaro.org>

> ---
> 
> This is modified based on Russell's feedback in the original
> discussion (Why the region area don't decrease 1 in function
> sanity_check_meminfo?)
> 
>  arch/arm/mm/mmu.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index 4c2d045..dbd9ff6 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -961,8 +961,8 @@ void __init sanity_check_meminfo(void)
>  		 * Check whether this memory bank would partially overlap
>  		 * the vmalloc area.
>  		 */
> -		if (__va(bank->start + bank->size) > vmalloc_min ||
> -		    __va(bank->start + bank->size) < __va(bank->start)) {
> +		if (__va(bank->start + bank->size - 1) >= vmalloc_min ||
> +		    __va(bank->start + bank->size - 1) <= __va(bank->start)) {
>  			unsigned long newsize = vmalloc_min - __va(bank->start);
>  			printk(KERN_NOTICE "Truncating RAM at %.8llx-%.8llx "
>  			       "to -%.8llx (vmalloc region overlap).\n",
> -- 
> 1.7.1
> 
> 
> 
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