Andrew Morton wrote:
...

quoted

+/*
+ * Mark an object as used in the cpu_alloc_map
+ *
+ * Must hold cpu_alloc_map_lock
+ */
+static void set_map(int start, int length)
+{
+	while (length-- > 0)
+		__set_bit(start++, cpu_alloc_map);
+}

bitmap_fill()?

quoted

+/*
+ * Mark an area as freed.
+ *
+ * Must hold cpu_alloc_map_lock
+ */
+static void clear_map(int start, int length)
+{
+	while (length-- > 0)
+		__clear_bit(start++, cpu_alloc_map);
+}

bitmap_zero()?

...

quoted

+void *cpu_alloc(unsigned long size, gfp_t gfpflags, unsigned long align)
+{
+	unsigned long start;
+	int units = size_to_units(size);
+	void *ptr;
+	int first;
+	unsigned long flags;
+
+	if (!size)
+		return ZERO_SIZE_PTR;

OK, so we reuse ZERO_SIZE_PTR from kmalloc.

quoted

+	spin_lock_irqsave(&cpu_alloc_map_lock, flags);
+
+	first = 1;
+	start = first_free;
+
+	for ( ; ; ) {
+
+		start = find_next_zero_bit(cpu_alloc_map, UNITS, start);
+		if (start >= UNITS)
+			goto out_of_memory;
+
+		if (first)
+			first_free = start;
+
+		/*
+		 * Check alignment and that there is enough space after
+		 * the starting unit.
+		 */
+		if (start % (align / UNIT_SIZE) == 0 &&
+			find_next_bit(cpu_alloc_map, UNITS, start + 1)
+							>= start + units)
+				break;
+		start++;
+		first = 0;
+	}

This is kinda bitmap_find_free_region(), only bitmap_find_free_region()
isn't quite strong enough.

Generally I think it would have been better if you had added new
primitives to the bitmap library (or enhanced existing ones) and used
them here, rather than implementing private functionality.

Hi Andrew,

I've sort of inherited this now...

So are you suggesting that we add new bitmap primitives to:

	bitmap_fill_offset(bitmap, start, nbits)   /* start at bitmap[start] */
	bitmap_zero_offset(bitmap, start, nbits)
	bitmap_find_free_area(bitmap, nbits, size, align)  /* size not order */

Thanks,
Mike