From 9ed20bafc85806ca6c97c9128cec46c3ef80ae86 Mon Sep 17 00:00:00 2001 From: Andrew Halaney Date: Fri, 3 Dec 2021 17:32:03 -0600 Subject: preempt/dynamic: Fix setup_preempt_mode() return value __setup() callbacks expect 1 for success and 0 for failure. Correct the usage here to reflect that. Fixes: 826bfeb37bb4 ("preempt/dynamic: Support dynamic preempt with preempt= boot option") Reported-by: Mark Rutland Signed-off-by: Andrew Halaney Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20211203233203.133581-1-ahalaney@redhat.com --- kernel/sched/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/sched/core.c') diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 76f9deeaa942..814c52d90c0f 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6617,11 +6617,11 @@ static int __init setup_preempt_mode(char *str) int mode = sched_dynamic_mode(str); if (mode < 0) { pr_warn("Dynamic Preempt: unsupported mode: %s\n", str); - return 1; + return 0; } sched_dynamic_update(mode); - return 0; + return 1; } __setup("preempt=", setup_preempt_mode); -- cgit v1.2.3 From 315c4f884800c45cb6bd8c90422fad554a8b9588 Mon Sep 17 00:00:00 2001 From: Qais Yousef Date: Thu, 2 Dec 2021 11:20:33 +0000 Subject: sched/uclamp: Fix rq->uclamp_max not set on first enqueue Commit d81ae8aac85c ("sched/uclamp: Fix initialization of struct uclamp_rq") introduced a bug where uclamp_max of the rq is not reset to match the woken up task's uclamp_max when the rq is idle. The code was relying on rq->uclamp_max initialized to zero, so on first enqueue static inline void uclamp_rq_inc_id(struct rq *rq, struct task_struct *p, enum uclamp_id clamp_id) { ... if (uc_se->value > READ_ONCE(uc_rq->value)) WRITE_ONCE(uc_rq->value, uc_se->value); } was actually resetting it. But since commit d81ae8aac85c changed the default to 1024, this no longer works. And since rq->uclamp_flags is also initialized to 0, neither above code path nor uclamp_idle_reset() update the rq->uclamp_max on first wake up from idle. This is only visible from first wake up(s) until the first dequeue to idle after enabling the static key. And it only matters if the uclamp_max of this task is < 1024 since only then its uclamp_max will be effectively ignored. Fix it by properly initializing rq->uclamp_flags = UCLAMP_FLAG_IDLE to ensure uclamp_idle_reset() is called which then will update the rq uclamp_max value as expected. Fixes: d81ae8aac85c ("sched/uclamp: Fix initialization of struct uclamp_rq") Signed-off-by: Qais Yousef Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Valentin Schneider Tested-by: Dietmar Eggemann Link: https://lkml.kernel.org/r/20211202112033.1705279-1-qais.yousef@arm.com --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/sched/core.c') diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 814c52d90c0f..77563109c0ea 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1918,7 +1918,7 @@ static void __init init_uclamp_rq(struct rq *rq) }; } - rq->uclamp_flags = 0; + rq->uclamp_flags = UCLAMP_FLAG_IDLE; } static void __init init_uclamp(void) -- cgit v1.2.3