[Crash-utility] One more change for crash

[Haren Myneni]

crash-utility-bounces at 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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