On Thursday 02 November 2006 23:24, Amul Shah wrote:

> 
> The ACPI tables and MP Tables reside higher in memory.  When reserving
> memory with reserve_bootmem_generic, the function has a BUG panic if the
> memory location to reserve is above the top of memory.  The MP table is
> above the top of memory in a user defined memory map.

I think it would be cleaner to add a check in reserve_bootmem_generic
that just returns when pfn >= end_pfn && pfn < end_pfn_mapped

How about this patch? Does it work?

-Andi

Handle reserve_bootmem_generic beyond end_pfn

This can happen on kexec kernels with some configurations, in particularly
on Unisys ES7000 systems.

Analysis by Amul Shah 

Cc: Amul Shah <[EMAIL PROTECTED]>

Signed-off-by: Andi Kleen <[EMAIL PROTECTED]>

Index: linux/arch/x86_64/mm/init.c
===================================================================
--- linux.orig/arch/x86_64/mm/init.c
+++ linux/arch/x86_64/mm/init.c
@@ -655,9 +655,22 @@ void free_initrd_mem(unsigned long start
 
 void __init reserve_bootmem_generic(unsigned long phys, unsigned len) 
 { 
-       /* Should check here against the e820 map to avoid double free */ 
 #ifdef CONFIG_NUMA
        int nid = phys_to_nid(phys);
+#endif
+       unsigned long pfn = phys >> PAGE_SHIFT;
+       if (pfn >= end_pfn) {
+               /* This can happen with kdump kernels when accessing firmware
+                  tables. */
+               if (pfn < end_pfn_map) 
+                       return;
+               printk(KERN_ERR "reserve_bootmem: illegal reserve %lx %u\n",
+                               phys, len);
+               return;
+       }
+
+       /* Should check here against the e820 map to avoid double free */ 
+#ifdef CONFIG_NUMA
        reserve_bootmem_node(NODE_DATA(nid), phys, len);
 #else                  
        reserve_bootmem(phys, len);    

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