On Tuesday 30 December 2008 03:06:07 Dave Hansen wrote:
> On Fri, 2008-12-26 at 11:59 +1100, Paul Mackerras wrote:
> > > +     }
> > > +
> > > +     for_each_online_node(nid) {
> > >               /*
> > > -              * Be very careful about moving this around.  Future
> > > -              * calls to careful_allocation() depend on this getting
> > > -              * done correctly.
> > > +              * Be very careful about moving this around.
> > >                */
> > >               mark_reserved_regions_for_nid(nid);
> > >               sparse_memory_present_with_active_regions(nid);
>
> I think this reintroduces one of the bugs that I squashed.  You *have*
> to call mark_reserved_regions_for_nid() right after you do
> free_bootmem_with_active_regions().  Otherwise, someone else can
> bootmem_alloc() a reserved region from that node.

Thanks for the review comments Dave. With the 
commit:a4c74ddd5ea3db53fc73d29c222b22656a7d05be, I see this has been taken care 
in mark_reserved_regions_for_nid(). In that case we may only need the change 
made in reserve_bootmem_node(). 

Hello Andrew, 
Could you please consider the following patch instead of the original patch in 
this thread. 
Thanks, 


When booted with crashkernel=2...@32m or any memory size less than this, the 
system boots properly. The system comes up with two nodes (0-256M and 
256M-4GB). The crashkernel memory reservation spans across these two nodes. The 
mark_reserved_regions_for_nid() in arch/powerpc/numa.c resizes the reserved 
part of the memory within it as... 

         if (end_pfn > node_ar.end_pfn)
                reserve_size = (node_ar.end_pfn << PAGE_SHIFT)
                                - (start_pfn << PAGE_SHIFT);

but the reserve_bootmem_node() in mm/bootmem.c raises the pfn value of end

        end = PFN_UP(physaddr + size);

This causes end to get a value past the last page in the 0-256M node. The 
following change restricts the value of end if it exceeds the last pfn in a 
given node.

Signed-off-by: Chandru S <chan...@linux.vnet.ibm.com>
Cc: Dave Hansen <d...@linux.vnet.ibm.com>
---

 mm/bootmem.c |    4 ++++
 1 file changed, 4 insertions(+)


--- linux-2.6.28/mm/bootmem.c.orig      2009-01-05 20:42:12.000000000 +0530
+++ linux-2.6.28/mm/bootmem.c   2009-01-05 20:43:53.000000000 +0530
@@ -375,10 +375,14 @@ int __init reserve_bootmem_node(pg_data_
                                 unsigned long size, int flags)
 {
        unsigned long start, end;
+       bootmem_data_t *bdata = pgdat->bdata;
 
        start = PFN_DOWN(physaddr);
        end = PFN_UP(physaddr + size);
 
+       if (end > bdata->node_low_pfn)
+               end = bdata->node_low_pfn;
+
        return mark_bootmem_node(pgdat->bdata, start, end, 1, flags);
 }
 
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