diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index fc897bb142bc..6e29b4dcf356 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -1881,15 +1881,21 @@ static void transfer_surpluses(struct list_head *surpluses, struct ioc_now *now)
 
 	/*
 	 * Calculate the global donation rate (gamma) - the rate to adjust
-	 * non-donating budgets by. No need to use 64bit multiplication here as
-	 * the first operand is guaranteed to be smaller than WEIGHT_ONE
-	 * (1<<16).
+	 * non-donating budgets by.
+	 *
+	 * No need to use 64bit multiplication here as the first operand is
+	 * guaranteed to be smaller than WEIGHT_ONE (1<<16).
+	 *
+	 * We know that there are beneficiary nodes and the sum of the donating
+	 * hweights can't be whole; however, due to the round-ups during hweight
+	 * calculations, root_iocg->hweight_donating might still end up equal to
+	 * or greater than whole. Limit the range when calculating the divider.
 	 *
 	 * gamma = (1 - t_r') / (1 - t_r)
 	 */
 	gamma = DIV_ROUND_UP(
 		(WEIGHT_ONE - root_iocg->hweight_after_donation) * WEIGHT_ONE,
-		WEIGHT_ONE - root_iocg->hweight_donating);
+		WEIGHT_ONE - min_t(u32, root_iocg->hweight_donating, WEIGHT_ONE - 1));
 
 	/*
 	 * Calculate adjusted hwi, child_adjusted_sum and inuse for the inner