[PATCH][ia64] Fix the difference between node_mem_map and node_start_pfn. (Re: makedumpfile fails on SGI machine)

[Ken'ichi Ohmichi]

Hi Bernhard, Jay,

Bernhard Walle wrote:
> Hi Ken'ichi Ohmichi,
> 
> * Jay Lan [2008-08-27 18:43]:
>> Thanks for your patch!
>>
>> I am wondering if the discontigmem kernel has a legitimate bug,
>> we probably should report it?
>>
>> I tested your patch on a machine that used to fail in executing
>> 'makedumpfile'. It now generated a dump file fine.
> 
> thanks for the patch, I can also report that with the patch and with
> vmlinux it works now.

Thank you for the report. It's a good news :-)


> However, shouldn't we add that vmem_map to VMCOREINFO of the kernel?

I think that we would rather fix the kernel bug than add vmem_map to
VMCOREINFO of the kernel. If fixing it, makedumpfile does not need
vmem_map.

The attached patch fixes the kernel bug, and makedumpfile can work without
'-x' option. I tested it on my ia64 none-NUMA machine, and it works fine.
Could you test the attached patch on your machine again ?


Thanks
Ken'ichi Ohmichi

---
[PATCH][ia64] Fix the difference between node_mem_map and node_start_pfn.

makedumpfile[1] cannot run on ia64 discontigmem kernel, because the member
node_mem_map of struct pgdat_list has invalid value. This patch fixes it.

node_start_pfn shows the start pfn of each node, and node_mem_map should
point 'struct page' of each node's node_start_pfn.
On my machine, node0's node_start_pfn shows 0x400 and its node_mem_map points
0xa0007fffbf000000. This address is the same as vmem_map, so the node_mem_map
points 'struct page' of pfn 0, even if its node_start_pfn shows 0x400.

The cause is due to the round down of min_pfn in count_node_pages().
This patch fixes it.


makedumpfile[1]: dump filtering command
https://sourceforge.net/projects/makedumpfile/

Signed-off-by: Ken'ichi Ohmichi <oomichi at mxs.nes.nec.co.jp>
---
--- a/arch/ia64/mm/discontig.c	2008-08-29 23:05:52.000000000 +0900
+++ b/arch/ia64/mm/discontig.c	2008-08-29 23:06:59.000000000 +0900
@@ -631,7 +631,6 @@ static __init int count_node_pages(unsig
 			(min(end, __pa(MAX_DMA_ADDRESS)) - start) >>PAGE_SHIFT;
 #endif
 	start = GRANULEROUNDDOWN(start);
-	start = ORDERROUNDDOWN(start);
 	end = GRANULEROUNDUP(end);
 	mem_data[node].max_pfn = max(mem_data[node].max_pfn,
 				     end >> PAGE_SHIFT);
--- a/include/asm-ia64/meminit.h	2008-08-29 23:06:36.000000000 +0900
+++ b/include/asm-ia64/meminit.h	2008-08-29 23:06:48.000000000 +0900
@@ -47,7 +47,6 @@ extern int reserve_elfcorehdr(unsigned l
  */
 #define GRANULEROUNDDOWN(n)	((n) & ~(IA64_GRANULE_SIZE-1))
 #define GRANULEROUNDUP(n)	(((n)+IA64_GRANULE_SIZE-1) & ~(IA64_GRANULE_SIZE-1))
-#define ORDERROUNDDOWN(n)	((n) & ~((PAGE_SIZE<<MAX_ORDER)-1))
 
 #ifdef CONFIG_NUMA
   extern void call_pernode_memory (unsigned long start, unsigned long len, void *func);
_