Re: [PATCH v8 14/16] ARM: LPAE: mark memory banks with start >ULONG_MAX as highmem

From: Nicolas Pitre
Date: Wed Nov 09 2011 - 15:41:16 EST


On Mon, 7 Nov 2011, Catalin Marinas wrote:

> From: Will Deacon <will.deacon@xxxxxxx>
>
> 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@xxxxxxx>
> Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>

Acked-by: Nicolas Pitre <nico@xxxxxxxxxx>


> ---
> 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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