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SubjectRe: [PATCH v2 16/22] ARM: mm: cleanup checks for membank overlap with vmalloc area
On 8/12/2012 12:36 AM, Nicolas Pitre wrote:
> On Fri, 10 Aug 2012, Cyril Chemparathy wrote:
>
>> On Keystone platforms, physical memory is entirely outside the 32-bit
>> addressible range. Therefore, the (bank->start > ULONG_MAX) check below marks
>> the entire system memory as highmem, and this causes unpleasentness all over.
>>
>> This patch eliminates the extra bank start check (against ULONG_MAX) by
>> checking bank->start against the physical address corresponding to vmalloc_min
>> instead.
>>
>> In the process, this patch also cleans up parts of the highmem sanity check
>> code by removing what has now become a redundant check for banks that entirely
>> overlap with the vmalloc range.
>
> Are you sure of this? The code that you removed not only checks for
> banks that fall into the vmalloc area, but it also skipp them. This is
> now lost.
>

I almost missed out on this email...

The check is not quite lost, we still have the following in the
!CONFIG_HIGHMEM block:

if (highmem) {
printk(...);
continue;
}

The change is that highmem is now set outside the #ifdef when
(bank->start >= vmalloc_limit), and therefore the check is truly redundant.

>> Signed-off-by: Cyril Chemparathy <cyril@ti.com>
>> Signed-off-by: Vitaly Andrianov <vitalya@ti.com>
>> ---
>> arch/arm/mm/mmu.c | 19 +------------------
>> 1 file changed, 1 insertion(+), 18 deletions(-)
>>
>> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
>> index f764c03..3d685c6 100644
>> --- a/arch/arm/mm/mmu.c
>> +++ b/arch/arm/mm/mmu.c
>> @@ -901,15 +901,12 @@ 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 (bank->start >= vmalloc_limit)
>> highmem = 1;
>>
>> bank->highmem = highmem;
>>
>> +#ifdef CONFIG_HIGHMEM
>> /*
>> * Split those memory banks which are partially overlapping
>> * the vmalloc area greatly simplifying things later.
>> @@ -932,8 +929,6 @@ void __init sanity_check_meminfo(void)
>> bank->size = vmalloc_limit - bank->start;
>> }
>> #else
>> - bank->highmem = highmem;
>> -
>> /*
>> * Highmem banks not allowed with !CONFIG_HIGHMEM.
>> */
>> @@ -946,18 +941,6 @@ void __init sanity_check_meminfo(void)
>> }
>>
>> /*
>> - * Check whether this memory bank would entirely overlap
>> - * the vmalloc area.
>> - */
>> - if (bank->start >= vmalloc_limit) {
>> - printk(KERN_NOTICE "Ignoring RAM at %.8llx-%.8llx "
>> - "(vmalloc region overlap).\n",
>> - (unsigned long long)bank->start,
>> - (unsigned long long)bank->start + bank->size - 1);
>> - continue;
>> - }
>> -
>> - /*
>> * Check whether this memory bank would partially overlap
>> * the vmalloc area.
>> */
>> --
>> 1.7.9.5
>>

--
Thanks
- Cyril


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