[PATCH] Don't cacheline-align vm_area_struct

Some workloads (Oracle...) use a huge number of VMA's.  They are
currently a tidy 64 bytes in size, and padding them out to 128 on P4's
is not worthwhile.

include/linux/mm.h

@@ -41,6 +41,9 @@ extern int page_cluster;
  * per VM-area/task.  A VM area is any part of the process virtual memory
  * space that has a special rule for the page-fault handlers (ie a shared
  * library, the executable area etc).
+ *
+ * This structure is exactly 64 bytes on ia32.  Please think very, very hard
+ * before adding anything to it.
  */
 struct vm_area_struct {
 	struct mm_struct * vm_mm;	/* The address space we belong to. */

kernel/fork.c

@@ -1078,7 +1078,7 @@ void __init proc_caches_init(void)
  
 	vm_area_cachep = kmem_cache_create("vm_area_struct",
 			sizeof(struct vm_area_struct), 0,
-			SLAB_HWCACHE_ALIGN, NULL, NULL);
+			0, NULL, NULL);
 	if(!vm_area_cachep)
 		panic("vma_init: Cannot alloc vm_area_struct SLAB cache");