Subject: [PATCH] ARM: mm: Fix the memblock allocation for LPAE machines

From: [email-masked] (Santosh Shilimkar)
Date: Wed, 5 Feb 2014 18:39:44 -0500

Russell,

On Saturday 01 February 2014 03:14 PM, Santosh Shilimkar wrote:
> Commit ad6492b8 added much needed memblock_virt_alloc_low() and further
> commit 07bacb3 {memblock, bootmem: restore goal for alloc_low} fixed the
> issue with low memory limit thansk to Yinghai. But even after all these fixes,
> there is still one case where the limit check done with ARCH_LOW_ADDRESS_LIMIT
> for low memory fails. Russell pointed out the issue with 32 bit LPAE machines
> in below thread.
> 	https://lkml.org/lkml/2014/1/28/364
> 
> Since on some LPAE machines where memory start address is beyond 4GB,
> the low memory marker in memblock will be set to default
> ARCH_LOW_ADDRESS_LIMIT which is wrong. We can fix this by letting
> architectures set the ARCH_LOW_ADDRESS_LIMIT using another export
> similar to memblock_set_current_limit() but am not sure whether
> its worth the trouble. Tell me if you think otherwise.
> 
> Rather am just trying to fix that one broken case using memblock_virt_alloc()
> in setup code since the memblock.current_limit is updated appropriately
> makes it work on all ARM 32 bit machines.
> 
> Cc: Yinghai Lu <[email-masked]>
> Cc: Russell King <[email-masked]>
> Cc: Strashko, Grygorii <[email-masked]>
> Cc: Andrew Morton <[email-masked]>
> Signed-off-by: Santosh Shilimkar <[email-masked]>
> ---
Whats you say here ? We should get the fix for the
issue. If you are ok, I can drop the patch in patch system.

>  arch/arm/kernel/setup.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index b0df976..1e8b030 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -731,7 +731,7 @@ static void __init request_standard_resources(const struct machine_desc *mdesc)
>  	kernel_data.end     = virt_to_phys(_end - 1);
>  
>  	for_each_memblock(memory, region) {
> -		res = memblock_virt_alloc_low(sizeof(*res), 0);
> +		res = memblock_virt_alloc(sizeof(*res), 0);
>  		res->name  = "System RAM";
>  		res->start = __pfn_to_phys(memblock_region_memory_base_pfn(region));
>  		res->end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;
>