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 A68EB248BB2; Wed, 15 Jan 2025 10:49:41 +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=1736938182; cv=none; b=hSjb1NqMQ6AwdCekk+Cp/Dn3br1NBRYbCNl+lxZcvpXP8mlZNUYMLMpNu/U1kNaoRKSU9rQKtLaHyhAzQb/3XX+jUfPu+kV/kAqo0p/elynCYen/r2rU8hJ2zu/fBWOt9+pMLhHlRrZu6dtN6BntVfwl3lm0HOHJW0Lc4hbeSnE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736938182; c=relaxed/simple; bh=agWNYXdCgOwv8MlnlzMBYWM/Sd3kJeDRRdhiJxEgBBQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mv9bD7zOJsVcp7QQxAZS+IVr1pokqCbHZ4TT06UpFw/PisHNTXQNWO2EqwcdRJJB6R9qjoGsaFKp+1KvGOrCONCjyg+YpzMi4Nm8ZO3YawtBIfuhiTZxTklximjROHDgElUgXvaJGDg6BoRNDC9yw48jPZjTMKQ2iHMHUfj5MoQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Ik0dwO4/; 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="Ik0dwO4/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D566DC4CEDF; Wed, 15 Jan 2025 10:49:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1736938181; bh=agWNYXdCgOwv8MlnlzMBYWM/Sd3kJeDRRdhiJxEgBBQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ik0dwO4//bl9jYJVsAY2qwNXsyte1KZMuF19wmMum4U2DmceVOcVgKgqULdZOnf6B UpBrtMrZpHiDIOJDh9Q+ZHJtV0H4OUxpN4oJiMU1N75K0iz6ZFexOdTLyBBnvPhP/2 XlFqq7UMn928IhZ2t1dcp7SDSBuPDDq40uKNFTAc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Changwoo Min , Andrea Righi , Tejun Heo , Sasha Levin Subject: [PATCH 6.12 108/189] sched_ext: Replace rq_lock() to raw_spin_rq_lock() in scx_ops_bypass() Date: Wed, 15 Jan 2025 11:36:44 +0100 Message-ID: <20250115103610.761184053@linuxfoundation.org> X-Mailer: git-send-email 2.48.0 In-Reply-To: <20250115103606.357764746@linuxfoundation.org> References: <20250115103606.357764746@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Changwoo Min [ Upstream commit 6268d5bc10354fc2ab8d44a0cd3b042d49a0417e ] scx_ops_bypass() iterates all CPUs to re-enqueue all the scx tasks. For each CPU, it acquires a lock using rq_lock() regardless of whether a CPU is offline or the CPU is currently running a task in a higher scheduler class (e.g., deadline). The rq_lock() is supposed to be used for online CPUs, and the use of rq_lock() may trigger an unnecessary warning in rq_pin_lock(). Therefore, replace rq_lock() to raw_spin_rq_lock() in scx_ops_bypass(). Without this change, we observe the following warning: ===== START ===== [ 6.615205] rq->balance_callback && rq->balance_callback != &balance_push_callback [ 6.615208] WARNING: CPU: 2 PID: 0 at kernel/sched/sched.h:1730 __schedule+0x1130/0x1c90 ===== END ===== Fixes: 0e7ffff1b811 ("scx: Fix raciness in scx_ops_bypass()") Signed-off-by: Changwoo Min Acked-by: Andrea Righi Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin --- kernel/sched/ext.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 40f915f893e2..81235942555a 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -4348,10 +4348,9 @@ static void scx_ops_bypass(bool bypass) */ for_each_possible_cpu(cpu) { struct rq *rq = cpu_rq(cpu); - struct rq_flags rf; struct task_struct *p, *n; - rq_lock(rq, &rf); + raw_spin_rq_lock(rq); if (bypass) { WARN_ON_ONCE(rq->scx.flags & SCX_RQ_BYPASSING); @@ -4367,7 +4366,7 @@ static void scx_ops_bypass(bool bypass) * sees scx_rq_bypassing() before moving tasks to SCX. */ if (!scx_enabled()) { - rq_unlock(rq, &rf); + raw_spin_rq_unlock(rq); continue; } @@ -4387,10 +4386,11 @@ static void scx_ops_bypass(bool bypass) sched_enq_and_set_task(&ctx); } - rq_unlock(rq, &rf); - /* resched to restore ticks and idle state */ - resched_cpu(cpu); + if (cpu_online(cpu) || cpu == smp_processor_id()) + resched_curr(rq); + + raw_spin_rq_unlock(rq); } unlock: raw_spin_unlock_irqrestore(&__scx_ops_bypass_lock, flags); -- 2.39.5