slab: clarify and fix calculate_slab_order()
If we triggered the 'offslab_limit' test, we would return with
cachep->gfporder incremented once too many times.
This clarifies the logic somewhat, and fixes that bug.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/slab.c b/mm/slab.c
index 2b0b151..f2e92dc 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1628,36 +1628,36 @@
size_t size, size_t align, unsigned long flags)
{
size_t left_over = 0;
+ int gfporder;
- for (;; cachep->gfporder++) {
+ for (gfporder = 0 ; gfporder <= MAX_GFP_ORDER; gfporder++) {
unsigned int num;
size_t remainder;
- if (cachep->gfporder > MAX_GFP_ORDER) {
- cachep->num = 0;
- break;
- }
-
- cache_estimate(cachep->gfporder, size, align, flags,
- &remainder, &num);
+ cache_estimate(gfporder, size, align, flags, &remainder, &num);
if (!num)
continue;
+
/* More than offslab_limit objects will cause problems */
- if (flags & CFLGS_OFF_SLAB && cachep->num > offslab_limit)
+ if ((flags & CFLGS_OFF_SLAB) && num > offslab_limit)
break;
+ /* Found something acceptable - save it away */
cachep->num = num;
+ cachep->gfporder = gfporder;
left_over = remainder;
/*
* Large number of objects is good, but very large slabs are
* currently bad for the gfp()s.
*/
- if (cachep->gfporder >= slab_break_gfp_order)
+ if (gfporder >= slab_break_gfp_order)
break;
- if ((left_over * 8) <= (PAGE_SIZE << cachep->gfporder))
- /* Acceptable internal fragmentation */
+ /*
+ * Acceptable internal fragmentation?
+ */
+ if ((left_over * 8) <= (PAGE_SIZE << gfporder))
break;
}
return left_over;