crash-utility-bounces@redhat.com wrote on 11/16/2005 11:28:23 AM:

> Badari Pulavarty wrote:
> Hi Dave,
> I am playing with "crash" on my machine with it fails with
> CONFIG_SPARSE_MEM. It looks like "node_mem_map" doesn't
> exist for SPARSE_MEM :(
> crash: invalid structure member offset: pglist_data_node_mem_map
>        FILE: memory.c  LINE: 10053  FUNCTION: dump_memory_nodes()
> [./crash] error trace: 100afe98 => 100d12f4 => 100d01cc => 10142f64
>   10142f64: .OFFSET_verify+140
>   100d01cc: .dump_memory_nodes+520
>   100d12f4: .node_table_init+492
>   100afe98: .vm_init+7948
> Thanks,
> Badari
> typedef struct pglist_data {
>         struct zone node_zones[MAX_NR_ZONES];
>         struct zonelist node_zonelists[GFP_ZONETYPES];
>         int nr_zones;
> #ifdef CONFIG_FLAT_NODE_MEM_MAP
>         struct page *node_mem_map;
> #endif
>         struct bootmem_data *bdata;
>
> Hmmm,, it kind of looks like the global "mem_map" array should be
> used in that case, but if that were true, then there could never
> be multiple pglist_data structures in that case?
> Here's what I mean -- in vm_init() there's this:
>         if (VALID_STRUCT(pglist_data)) {
>                 vt->flags |= ZONES;
>                 if (symbol_exists("pgdat_list"))
>                         vt->flags |= NODES;
> And later on in dump_memory_nodes(), which gathers the memory-related
> information for each node, it looks at that "NODES" flag.
> - If the NODES flag is *not* set, then it presumes that there is
>   just one node, and uses the global "mem_map".
> - If the NODES flag is set, then starting at the pgdat_list list head,
>   it walks though each of the pglist_data structures (one per node),
>   and then collects all of the individual node_mem_map pointers
>   found in each node.
> In this hybrid case, I don't know how exactly the mem_map
> is found for each pglist_data node?  You could quickly try
> not setting the vt->flags NODES bit, and seeing what happens.
> But I get the feeling that there's going to more to be done
> than that -- presuming that you can have more than one pglist_data
> node.  In other words if the pglist_data list can have more
> than one node when CONFIG_FLAT_NODE_MEM_MAP is turned off,
> then we need to find out how to make the relationship between
> each sparse node and its associated mem_map array.
> Dave

As we know, recently, several config options (SPARSEMEM, FLAT_NODE_MEM_MAP, DISCONTIG ..) got introduced. Badari, is CONFIG_SPARSEMEM is enabled on your system (System.map should have the symbol called mem_section).  I think, we should also support mm_section.section_mem_map.

Thanks
Haren
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