From: Vincent Donnefort <vincent.donnefort@arm.com> stable inclusion from stable-v5.10.94 commit b77ef5b4ead6a17baa1728d98c1f6a4ba1dd44c8 bugzilla: https://gitee.com/openeuler/kernel/issues/I531X9 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 014ba44e8184e1acf93e0cbb7089ee847802f8f0 ] select_idle_sibling() has a special case for tasks woken up by a per-CPU kthread where the selected CPU is the previous one. For asymmetric CPU capacity systems, the assumption was that the wakee couldn't have a bigger utilization during task placement than it used to have during the last activation. That was not considering uclamp.min which can completely change between two task activations and as a consequence mandates the fitness criterion asym_fits_capacity(), even for the exit path described above. Fixes: b4c9c9f15649 ("sched/fair: Prefer prev cpu in asymmetric wakeup path") Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lkml.kernel.org/r/20211129173115.4006346-1-vincent.donnefort@arm.com Signed-off-by: Sasha Levin <sashal@kernel.org> Conflicts: kernel/sched/fair.c Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Acked-by: Cheng Jian <cj.chengjian@huawei.com> Acked-by: Xie XiuQi <xiexiuqi@huawei.com> --- kernel/sched/fair.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 9c59854d14e9..2e26e1b98589 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6409,7 +6409,8 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) if (is_per_cpu_kthread(current) && in_task() && prev == smp_processor_id() && - this_rq()->nr_running <= 1) { + this_rq()->nr_running <= 1 && + asym_fits_capacity(task_util, prev)) { SET_STAT(found_idle_cpu_easy); return prev; } -- 2.20.1