From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E81C1D0DE6; Wed, 2 Oct 2024 14:33:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727879611; cv=none; b=jCAO12lFD6ObfQq5TUM8zIDfBUKn+7yDaaGMTb2l+uaCTgx2IdvkNhpPQrTHHqZGMbPyV0Mno++4sn/dSN8/WWFYEg1bl286Jg1nfUC910kU/dagaX+C1Uh/HYn9iZEJLEjSPpIN0puZA3hgkDrRTaUIfZ+NmzjEH9gsNqhjCNA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727879611; c=relaxed/simple; bh=uCdy9OUnVxkUBseNU9QUBEli1q2X0DS/Ph09M/U8lZo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IePvYuxpFNJoU5GYvgP4sbXuo4waR2xag3+GRcA5vYZ2e4RzCqg4iTGT3EtQd4dMRf3td2ciL2GbzrEQm0sCW3wYOv4CAlp6mm1HjKNraIDg+aXXem6Eh0/e7Hj6fjIFygoycZN+6wZq7f/opAbf4i8T+//PJwwYOkxhAfaATRM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cIx+wXAJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="cIx+wXAJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F1AFC4CEC2; Wed, 2 Oct 2024 14:33:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1727879611; bh=uCdy9OUnVxkUBseNU9QUBEli1q2X0DS/Ph09M/U8lZo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cIx+wXAJ6SVP0FOD3scWzgS3qlqovSgrRcsQgHHcoMhqNyBhpBiU4x23xdsJ4gvKz Kp1sDeiaEXezxFOL3gknZiCdSjDYarx8wtZrmmUEsyu0XLWdfWX00EhK/TPuTlG2Oi 91hM9imn9oseLTH9qIkPbErmHWkUZ3TBQKlpYaX8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tianchen Ding , "Peter Zijlstra (Intel)" , Josh Don , Vincent Guittot , Sasha Levin Subject: [PATCH 6.6 179/538] sched/fair: Make SCHED_IDLE entity be preempted in strict hierarchy Date: Wed, 2 Oct 2024 14:56:58 +0200 Message-ID: <20241002125759.321708549@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241002125751.964700919@linuxfoundation.org> References: <20241002125751.964700919@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tianchen Ding [ Upstream commit faa42d29419def58d3c3e5b14ad4037f0af3b496 ] Consider the following cgroup: root | ------------------------ | | normal_cgroup idle_cgroup | | SCHED_IDLE task_A SCHED_NORMAL task_B According to the cgroup hierarchy, A should preempt B. But current check_preempt_wakeup_fair() treats cgroup se and task separately, so B will preempt A unexpectedly. Unify the wakeup logic by {c,p}se_is_idle only. This makes SCHED_IDLE of a task a relative policy that is effective only within its own cgroup, similar to the behavior of NICE. Also fix se_is_idle() definition when !CONFIG_FAIR_GROUP_SCHED. Fixes: 304000390f88 ("sched: Cgroup SCHED_IDLE support") Signed-off-by: Tianchen Ding Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Josh Don Reviewed-by: Vincent Guittot Link: https://lkml.kernel.org/r/20240626023505.1332596-1-dtcccc@linux.alibaba.com Signed-off-by: Sasha Levin --- kernel/sched/fair.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b2e1009e5706e..5fc0d9cc9d9d7 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -533,7 +533,7 @@ static int cfs_rq_is_idle(struct cfs_rq *cfs_rq) static int se_is_idle(struct sched_entity *se) { - return 0; + return task_has_idle_policy(task_of(se)); } #endif /* CONFIG_FAIR_GROUP_SCHED */ @@ -8209,16 +8209,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ if (test_tsk_need_resched(curr)) return; - /* Idle tasks are by definition preempted by non-idle tasks. */ - if (unlikely(task_has_idle_policy(curr)) && - likely(!task_has_idle_policy(p))) - goto preempt; - - /* - * Batch and idle tasks do not preempt non-idle tasks (their preemption - * is driven by the tick): - */ - if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION)) + if (!sched_feat(WAKEUP_PREEMPTION)) return; find_matching_se(&se, &pse); @@ -8228,7 +8219,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ pse_is_idle = se_is_idle(pse); /* - * Preempt an idle group in favor of a non-idle group (and don't preempt + * Preempt an idle entity in favor of a non-idle entity (and don't preempt * in the inverse case). */ if (cse_is_idle && !pse_is_idle) @@ -8236,9 +8227,14 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ if (cse_is_idle != pse_is_idle) return; + /* + * BATCH and IDLE tasks do not preempt others. + */ + if (unlikely(p->policy != SCHED_NORMAL)) + return; + cfs_rq = cfs_rq_of(se); update_curr(cfs_rq); - /* * XXX pick_eevdf(cfs_rq) != se ? */ -- 2.43.0