[Crash-utility] vmlist initialize fix

[Kazuo Moriwaka]

Hi Dave,

Crash was stopped with following messages when I try to treat very small
dump image. 
It was caused in vmalloc_start initialise when vmalloc is not used
(vmlist == 0).  This patch return address 0 for this case. 

> <readmem: c02a99a8, KVADDR, "vmlist", 4, (FOE), afdae5f4>
> <readmem: 0, KVADDR, "first vmlist addr", 4, (ROE), afdae5f0>
> crash: invalid kernel virtual address: 0  type: "first vmlist addr"

regards,
-- 
Kazuo Moriwaka <moriwaka at valinux.co.jp>


--- crash-4.0-2.31.orig/memory.c	2006-06-27 23:15:32.000000000 +0900
+++ crash-4.0-2.31/memory.c	2006-07-10 18:24:54.000000000 +0900
@@ -11049,10 +11049,13 @@
         ulong vmlist, addr;
 
         get_symbol_data("vmlist", sizeof(void *), &vmlist);
-
-        if (!readmem(vmlist+OFFSET(vm_struct_addr), KVADDR, &addr, 
-	    sizeof(void *), "first vmlist addr", RETURN_ON_ERROR)) 
-		non_matching_kernel();
+        if (vmlist != 0x0) {
+            if (!readmem(vmlist+OFFSET(vm_struct_addr), KVADDR, &addr, 
+	        sizeof(void *), "first vmlist addr", RETURN_ON_ERROR)) 
+	       	    non_matching_kernel();
+        } else {
+            addr = 0;
+        }
 
         return addr;
 }