(struct sg_lb_stats).idle_cpus is of type 'unsigned int'. (local->idle_cpus - busiest->idle_cpus) can underflow to UINT_MAX for instance, and max_t(long, 0, UINT_MAX) will output UINT_MAX.

Use lsub_positive() instead of max_t().

Fixes: 16b0a7a1a0af ("sched/fair: Ensure tasks spreading in LLC during LB") cc: stable@vger.kernel.org Signed-off-by: Pierre Gondois pierre.gondois@arm.com Reviewed-by: Vincent Guittot vincent.guittot@linaro.org --- kernel/sched/fair.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 9057584ec06d..6d9124499f52 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10775,8 +10775,8 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s * idle CPUs. */ env->migration_type = migrate_task; - env->imbalance = max_t(long, 0, - (local->idle_cpus - busiest->idle_cpus)); + env->imbalance = local->idle_cpus; + lsub_positive(&env->imbalance, busiest->idle_cpus); }

#ifdef CONFIG_NUMA