Subject: Re: 2.6.28-rc9 panics with crashkernel=256M while booting

From: Chandru <[email-masked]>
Date: Tue, 20 Jan 2009 13:43:42 +0530

Chandru wrote:
> In case either physbase or reserve_size are not page aligned and in addition
> if the following condition is also true
>
> node_ar.end_pfn = node->node_end_pfn = PFN_DOWN(physbase+reserve_size).
>
> we may hit the BUG_ON(end > bdata->node_low_pfn) in mark_bootmem_node() in
> mm/bootmem.c Hence pass the pfn that the physbase is part of and align
> reserve_size before calling reserve_bootmem_node().
>
> Signed-off-by: Chandru S <[email-masked]>
> Cc: Dave Hansen <[email-masked]>
> ---
>  arch/powerpc/mm/numa.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> --- linux-2.6.29-rc2/arch/powerpc/mm/numa.c.orig	2009-01-19 16:14:49.000000000 +0530
> +++ linux-2.6.29-rc2/arch/powerpc/mm/numa.c	2009-01-19 16:36:38.000000000 +0530
> @@ -901,7 +901,8 @@ static void mark_reserved_regions_for_ni
>  		get_node_active_region(start_pfn, &node_ar);
>  		while (start_pfn < end_pfn &&
>  			node_ar.start_pfn < node_ar.end_pfn) {
> -			unsigned long reserve_size = size;
> +			unsigned long reserve_size = (size >> PAGE_SHIFT) <<
> +								PAGE_SHIFT;
>  			/*
>  			 * if reserved region extends past active region
>  			 * then trim size to active region
> @@ -917,7 +918,8 @@ static void mark_reserved_regions_for_ni
>  				dbg("reserve_bootmem %lx %lx nid=%d\n",
>  					physbase, reserve_size, node_ar.nid);
>  				reserve_bootmem_node(NODE_DATA(node_ar.nid),
> -						physbase, reserve_size,
> +						(start_pfn << PAGE_SHIFT),
> +						reserve_size,
>  						BOOTMEM_DEFAULT);
>  			}
>  			/*
>   
does this patch look good ?, do you concur with it ?

thanks,
Chandru