/*
* 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