RE: 05e0caad3b7bd0d0fbeff980bca22f186241a501 breaks ia64 kdump

From: Zou, Nanhai <nanhai.zou_at_intel.com>
Date: 2006-11-03 11:28:31
Hi,
	This patch should fix the issue.

Thanks
Zou Nan hai

> -----Original Message-----
> From: Mel Gorman [mailto:mel@csn.ul.ie]
> Sent: 2006113 0:27
> To: Horms
> Cc: Andy Whitcroft; Zou, Nanhai; linux-ia64@vger.kernel.org; Bob Picco; Andrew
> Morton; Dave Hansen; Andi Kleen; Benjamin Herrenschmidt; Paul Mackerras; Keith
> Mannthey; Luck, Tony; KAMEZAWA Hiroyuki; Yasunori Goto; Khalid Aziz
> Subject: Re: 05e0caad3b7bd0d0fbeff980bca22f186241a501 breaks ia64 kdump
> 
> On Thu, 2 Nov 2006, Horms wrote:
> 
> > On Wed, Nov 01, 2006 at 09:38:38AM +0000, Mel Gorman wrote:
> >>
> >> Plan C
> >>
> >> Call add_active_ranges() for the the PFN ranges initmem reside in.
> >> Look at free_initmem() to see how to get the virtual address of the
> >> range is found and make the appropriate conversion. A variation is to
> >> call add_active_ranges() for the PFN range the whole kernel resides in
> >> if you have that information for the crash kernel.
> >
> > I've made a version of this approach that seems to work.
> > I had to update add_active_range so that it merges
> > ranges that are not overlapping, but do create a continous range.
> > Is this a correct thing to do?
> >
> 
> It's a bit unlikely it's the correct fix. As you can see, the
> add_active_range() is already able to merge contiguous ranges. If the
> calls imply there is a one page hole, then there is a one page hole. If
> the caller is wrong and there isn't a one-page hole, then fix the caller
> walking the map. Power for example currently merges large numbers of
> adjacent regions that are registered separetly.
> 
> 
> > --
> > Horms
> >  H: http://www.vergenet.net/~horms/
> >  W: http://www.valinux.co.jp/en/
> >
> > Index: linux-2.6/mm/page_alloc.c
> > ===================================================================
> > --- linux-2.6.orig/mm/page_alloc.c	2006-11-02 16:17:17.000000000 +0900
> > +++ linux-2.6/mm/page_alloc.c	2006-11-02 16:17:22.000000000 +0900
> > @@ -2407,7 +2407,7 @@
> > 			return;
> >
> > 		/* Merge forward if suitable */
> > -		if (start_pfn <= early_node_map[i].end_pfn &&
> > +		if (start_pfn <= early_node_map[i].end_pfn + 1 &&
> > 				end_pfn > early_node_map[i].end_pfn) {
> > 			early_node_map[i].end_pfn = end_pfn;
> > 			return;
> > @@ -2415,7 +2415,7 @@
> >
> > 		/* Merge backward if suitable */
> > 		if (start_pfn < early_node_map[i].end_pfn &&
> > -				end_pfn >= early_node_map[i].start_pfn) {
> > +				end_pfn + 1 >= early_node_map[i].start_pfn) {
> > 			early_node_map[i].start_pfn = start_pfn;
> > 			return;
> > 		}
> > Index: linux-2.6/arch/ia64/mm/discontig.c
> > ===================================================================
> > --- linux-2.6.orig/arch/ia64/mm/discontig.c	2006-11-02
> 16:17:59.000000000 +0900
> > +++ linux-2.6/arch/ia64/mm/discontig.c	2006-11-02 16:18:03.000000000
> +0900
> > @@ -689,6 +689,8 @@
> > 	arch_sparse_init();
> >
> > 	efi_memmap_walk(filter_rsvd_memory, count_node_pages);
> > +	add_active_range(0, ia64_tpa(_text) >> PAGE_SHIFT,
> > +	                 (ia64_tpa(_end) -1 ) >> PAGE_SHIFT);
> >
> > #ifdef CONFIG_VIRTUAL_MEM_MAP
> > 	vmalloc_end -= PAGE_ALIGN(ALIGN(max_low_pfn, MAX_ORDER_NR_PAGES) *
> >
> 
> --
> Mel Gorman
> Part-time Phd Student                          Linux Technology Center
> University of Limerick                         IBM Dublin Software Lab

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Received on Fri Nov 03 11:29:03 2006

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