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SubjectRe: memblock and bootmem problems if start + size = 4GB
Tejun Heo wrote:
> Hello,
>
> On Thu, Dec 29, 2011 at 05:46:18PM +0100, Michal Simek wrote:
>> First of all I don't like to use your term "extend range coverages".
>> We don't want to extend any ranges - we just wanted to place memory to the end
>> of address space and be able to work with.
>
> It is, as long as we use address ranges. Either we can express length
> of zero or include the last address.
>
>> It is limitation which should be fixed somehow.
>> And I would expect that PFN_XX(base + size) will be in u32 range.
>>
>> Probably the best solution will be to use PFN macro in one place and
>> do not covert addresses in common code.
>>
>> + change parameters in bootmem code because some arch do
>> free_bootmem_node(..., PFN_PHYS(), ...)
>> and
>> reserve_bootmem_node(..., PFN_PHYS(), ...)
>
> So now we're talking about a lot of code just for ONE page and
> regardless of the representation in the memblock or other memory
> management code, I think trying to use that page is fundamentally a
> bad idea. There are a lot of places in the kernel where phys_addr_t
> is used.

I haven't said to replace phys_addr_t!
My point was something like this (just as example on parisc and free_bootmem_node).
The problematic part is kmemleak code which could be good reason not to change it.

Thanks,
Michal


diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c
index 82f364e..b83ee32 100644
--- a/arch/parisc/mm/init.c
+++ b/arch/parisc/mm/init.c
@@ -291,8 +291,8 @@ static void __init setup_bootmem(void)
start_pfn,
(start_pfn + npages) );
free_bootmem_node(NODE_DATA(i),
- (start_pfn << PAGE_SHIFT),
- (npages << PAGE_SHIFT) );
+ start_pfn,
+ npages);
bootmap_pfn += (bootmap_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
if ((start_pfn + npages) > max_pfn)
max_pfn = start_pfn + npages;


diff --git a/mm/bootmem.c b/mm/bootmem.c
index 45a691a..dfbfc47 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -363,17 +363,12 @@ static int __init mark_bootmem(unsigned long start, unsigned long end,
*
* The range must reside completely on the specified node.
*/
-void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
- unsigned long size)
+void __init free_bootmem_node(pg_data_t *pgdat, unsigned long startpfn,
+ unsigned long endpfn)
{
- unsigned long start, end;
-
- kmemleak_free_part(__va(physaddr), size);
+ kmemleak_free_part(__va(startpfn << PAGE_SHIFT), (endpfn - startpfn) << PAGE_SHIFT);

- start = PFN_UP(physaddr);
- end = PFN_DOWN((u64)physaddr + (u64)size);
-
- mark_bootmem_node(pgdat->bdata, start, end, 0, 0);
+ mark_bootmem_node(pgdat->bdata, startpfn, endpfn, 0, 0);
}



--
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian


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