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 6EDD221B9E5; Mon, 23 Jun 2025 21:51:56 +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=1750715516; cv=none; b=lHd9OPCYIJTFLx1SZv8OrDqdqoix6Ic/qX5tvKAEL8Oe+DVhHL+dnlMgKbeRE1r2ks53o3BP/5nfT3RHG/uFuJ3iUKKzb2Zu/FbyJdfRnhORHxqkbRO8M6eptLX0rtTs2e5t/mS3RcXpL6fF8SsEU5tpeKW+oclGwCr3JNQujSg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750715516; c=relaxed/simple; bh=9wLy5/vU2QLyWPyeaOfpxCorWYHSTy9l6XCHlYdy2Ek=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FaVrZOgoMzylvVQ2COLmQiLJJoyWarw1ryL4/ojCon51BwZ+S6uktjJp12/C/CflbyAc/HA6xrnsEXV9oTpzJHKa0tT7t2qmcb0KcCPYzKtdVQiphwpFxsGndEGcZBKg6SnexpLunpCk09RWL0qjdscZ7BHsSmF8dew6KtwPruQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FEzjhgeM; 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="FEzjhgeM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1FCDC4CEEA; Mon, 23 Jun 2025 21:51:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1750715516; bh=9wLy5/vU2QLyWPyeaOfpxCorWYHSTy9l6XCHlYdy2Ek=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FEzjhgeMk7srY7MMpJWUGwSZRHreRjm8JCzhqZG2N1kj647wYRrL2HRjRBbjrEw+X RGa+xw4GP9NTCw1xg8qXBYYbCitgS3mbR4PQWzRnxnzvMnF0k5cdPgQ+yafQug17+4 8dH+FqJLsWom+OavOH5KZhfMQFHzGwFv+l/dzSWE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tejun Heo Subject: [PATCH 6.15 484/592] sched_ext, sched/core: Dont call scx_group_set_weight() prematurely from sched_create_group() Date: Mon, 23 Jun 2025 15:07:22 +0200 Message-ID: <20250623130711.945562064@linuxfoundation.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250623130700.210182694@linuxfoundation.org> References: <20250623130700.210182694@linuxfoundation.org> User-Agent: quilt/0.68 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 6.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tejun Heo commit 33796b91871ad4010c8188372dd1faf97cf0f1c0 upstream. During task_group creation, sched_create_group() calls scx_group_set_weight() with CGROUP_WEIGHT_DFL to initialize the sched_ext portion. This is premature and ends up calling ops.cgroup_set_weight() with an incorrect @cgrp before ops.cgroup_init() is called. sched_create_group() should just initialize SCX related fields in the new task_group. Fix it by factoring out scx_tg_init() from sched_init() and making sched_create_group() call that function instead of scx_group_set_weight(). v2: Retain CONFIG_EXT_GROUP_SCHED ifdef in sched_init() as removing it leads to build failures on !CONFIG_GROUP_SCHED configs. Signed-off-by: Tejun Heo Fixes: 819513666966 ("sched_ext: Add cgroup support") Cc: stable@vger.kernel.org # v6.12+ Signed-off-by: Greg Kroah-Hartman --- kernel/sched/core.c | 4 ++-- kernel/sched/ext.c | 5 +++++ kernel/sched/ext.h | 2 ++ 3 files changed, 9 insertions(+), 2 deletions(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8571,7 +8571,7 @@ void __init sched_init(void) init_cfs_bandwidth(&root_task_group.cfs_bandwidth, NULL); #endif /* CONFIG_FAIR_GROUP_SCHED */ #ifdef CONFIG_EXT_GROUP_SCHED - root_task_group.scx_weight = CGROUP_WEIGHT_DFL; + scx_tg_init(&root_task_group); #endif /* CONFIG_EXT_GROUP_SCHED */ #ifdef CONFIG_RT_GROUP_SCHED root_task_group.rt_se = (struct sched_rt_entity **)ptr; @@ -9011,7 +9011,7 @@ struct task_group *sched_create_group(st if (!alloc_rt_sched_group(tg, parent)) goto err; - scx_group_set_weight(tg, CGROUP_WEIGHT_DFL); + scx_tg_init(tg); alloc_uclamp_sched_group(tg, parent); return tg; --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -3936,6 +3936,11 @@ bool scx_can_stop_tick(struct rq *rq) DEFINE_STATIC_PERCPU_RWSEM(scx_cgroup_rwsem); static bool scx_cgroup_enabled; +void scx_tg_init(struct task_group *tg) +{ + tg->scx_weight = CGROUP_WEIGHT_DFL; +} + int scx_tg_online(struct task_group *tg) { int ret = 0; --- a/kernel/sched/ext.h +++ b/kernel/sched/ext.h @@ -80,6 +80,7 @@ static inline void scx_update_idle(struc #ifdef CONFIG_CGROUP_SCHED #ifdef CONFIG_EXT_GROUP_SCHED +void scx_tg_init(struct task_group *tg); int scx_tg_online(struct task_group *tg); void scx_tg_offline(struct task_group *tg); int scx_cgroup_can_attach(struct cgroup_taskset *tset); @@ -89,6 +90,7 @@ void scx_cgroup_cancel_attach(struct cgr void scx_group_set_weight(struct task_group *tg, unsigned long cgrp_weight); void scx_group_set_idle(struct task_group *tg, bool idle); #else /* CONFIG_EXT_GROUP_SCHED */ +static inline void scx_tg_init(struct task_group *tg) {} static inline int scx_tg_online(struct task_group *tg) { return 0; } static inline void scx_tg_offline(struct task_group *tg) {} static inline int scx_cgroup_can_attach(struct cgroup_taskset *tset) { return 0; }