[PATCH] update total_vm on non-MMU configurations

This patch fixes 3 problems with the nommu.c support code:

1. export mem_map and vmtruncate (to make them the same as MMU version)

2. update the total_vm usage in mmap routines
   Without this the OOM killer has no "badness" points to rate
   processes on...

   This patch was originally submitted by Giovanni Casoli
   <giovanni.casoli@atengineering.it> for a 2.4.26 kernel.
   I applied it to the 2.6.9 code.

3. provide stub for arch_get_unmapped_area
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

mm/nommu.c

@@ -33,9 +33,10 @@ unsigned long askedalloc, realalloc;
 atomic_t vm_committed_space = ATOMIC_INIT(0);
 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
 int sysctl_overcommit_ratio = 50; /* default is 50% */
-
 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
+
 EXPORT_SYMBOL(sysctl_max_map_count);
+EXPORT_SYMBOL(mem_map);
 
 /*
  * Handle all mappings that got truncated by a "truncate()"
@@ -75,6 +76,8 @@ int vmtruncate(struct inode *inode, loff_t offset)
 	return -EFBIG;
 }
 
+EXPORT_SYMBOL(vmtruncate);
+
 /*
  * Return the total memory allocated for this pointer, not
  * just what the caller asked for.
@@ -431,6 +434,7 @@ unsigned long do_mmap_pgoff(
 
 	tblock->next = current->mm->context.tblock.next;
 	current->mm->context.tblock.next = tblock;
+	current->mm->total_vm += len >> PAGE_SHIFT;
 
 #ifdef DEBUG
 	printk("do_mmap:\n");
@@ -484,6 +488,7 @@ int do_munmap(struct mm_struct * mm, unsigned long addr, size_t len)
 	realalloc -= kobjsize(tblock);
 	askedalloc -= sizeof(struct mm_tblock_struct);
 	kfree(tblock);
+	mm->total_vm -= len >> PAGE_SHIFT;
 
 #ifdef DEBUG
 	show_process_blocks();
@@ -496,6 +501,7 @@ int do_munmap(struct mm_struct * mm, unsigned long addr, size_t len)
 void exit_mmap(struct mm_struct * mm)
 {
 	struct mm_tblock_struct *tmp;
+	mm->total_vm = 0;
 
 	if (!mm)
 		return;
@@ -575,3 +581,14 @@ unsigned long get_unmapped_area(struct file *file, unsigned long addr,
 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
 {
 }
+
+unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
+	unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+	return -ENOMEM;
+}
+
+void arch_unmap_area(struct vm_area_struct *area)
+{
+}
+