From: "Bob Picco" <bob.picco@hp.com>
Date: Sun, 10 Sep 2006 13:10:24 -0400
To: Andy Whitcroft <apw@shadowen.org>
Cc: Bob Picco <bob.picco@hp.com>, akpm@osdl.org, mel@csn.ul.ie,
       tony.luck@intel.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ia64 specific for Sizing zones and holes in an architecture independent
Message-ID: <20060910171024.GE3708@localhost>
References: <20060829101247.GF10680@localhost> <4503644D.9070307@shadowen.org>
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Andy Wihitcroft wrote:	[Sat Sep 09 2006, 09:03:09PM EDT]
> Bob Picco wrote:
> > Andrew,
> > 
> > Mel's latest V9 regressed slightly for ia64 FLATMEM+VIRTUAL_MEM_MAP. When 
> > the largest hole is greater than LARGE_GAP, vmem_map is allocated before 
> > free_area_init_nodes; resultant crash follows. Rather than complicate
> > alloc_node_mem_map just for this ia64 case, add an adjustment to node_mem_map
> > which is later negated by alloc_node_mem_map.
> > 
> > Previous to V9, the mem_map adjustment was done in the scope where allocation
> > is achieved in alloc_node_mem_map. The current code is more appropriate but
> > unfortunately caused an issue for ia64.
> > 
> > Please add this to the next -mm.
> > 
> > thanks,
> > 
> > bob
> > 
> > Acked-by: Mel Gorman <mel@csn.ul.ie>
> > Signed-off-by: Bob Picco <bob.picco@hp.com>
> > 
> >  arch/ia64/mm/contig.c |    7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > Index: linux-2.6.18-rc4-mm3/arch/ia64/mm/contig.c
> > ===================================================================
> > --- linux-2.6.18-rc4-mm3.orig/arch/ia64/mm/contig.c	2006-08-28 13:10:00.000000000 -0400
> > +++ linux-2.6.18-rc4-mm3/arch/ia64/mm/contig.c	2006-08-28 18:18:54.000000000 -0400
> > @@ -252,7 +252,12 @@ paging_init (void)
> >  		vmem_map = (struct page *) vmalloc_end;
> >  		efi_memmap_walk(create_mem_map_page_table, NULL);
> >  
> > -		NODE_DATA(0)->node_mem_map = vmem_map;
> > +		/*
> > +		 * alloc_node_mem_map makes an adjustment for mem_map
> > +		 * which isn't compatible with vmem_map.
> > +		 */
> 
> Bob, which adjustment is this that is incompatible?  Is it the one in
> the final stanza, the FLATMEM mem_map instantiation?  This one?
Andy, yes this is the one.
> 
> #ifdef CONFIG_ARCH_POPULATES_NODE_MAP
>                 if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
>                         mem_map -= pgdat->node_start_pfn;
> #endif /* CONFIG_ARCH_POPULATES_NODE_MAP */
> 
> -apw
bob
> 
> > +		NODE_DATA(0)->node_mem_map = vmem_map +
> > +			find_min_pfn_with_active_regions();
> >  		free_area_init_nodes(max_zone_pfns);
> >  
> >  		printk("Virtual mem_map starts at 0x%p\n", mem_map);
> > -
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> 
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