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 800941E0086; Tue, 8 Oct 2024 13:26:44 +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=1728394004; cv=none; b=cuVEr0MN3TFLe8qXnrKDJEnAygumbpzpOlPkC94tONjf4zSHzdIhnSR2nRd2nlLWFQwGX6lANl65JmuUXjR2cYZ3PBbRci8myCUqsUwELLu2L28JqYCjGUBmiRcLtRNUcZbpZNNbJkNdSyvx5XFnNcazlZyp41bCbN8MxGHWSjo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728394004; c=relaxed/simple; bh=OzE9MZN3KGd+sRs8XRahXQnhKdOrTZ8KpkXYDM7qANg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EbZnJ4Udszd1KBrSCNk2PWfIxSGrP87stpJgmS9JQhsacLfUTAPj39XM+i1n6fHjxfRRMrzHkQr4xa/HOo00oZr59il6H0ELT3FlI8+umhXruUT/oITccCqHniq7Nl4U/ZkTSvuhRdRAzGCFTK6Mv/PlxU+cXyorAU3yEKepdNM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=DNVQsFIj; 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="DNVQsFIj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EDCAEC4CEC7; Tue, 8 Oct 2024 13:26:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728394004; bh=OzE9MZN3KGd+sRs8XRahXQnhKdOrTZ8KpkXYDM7qANg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DNVQsFIjgPI4I0CanxujB120awhi1EpWhaSXaUGnWV25OzTQML63MfkONwQHp685p r/xLMzwdqZERgoTzxEa9nEOwgmcyuhznawaMB8nujD9AiMJLvpsQDqGD1Omj6KCNSn qV4dDZI6/s+H58wMvLx4avJCtmGpZkqVE8BUVDBk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Masami Hiramatsu , Mathieu Desnoyers , Wei Li , "Steven Rostedt (Google)" Subject: [PATCH 6.6 318/386] tracing/timerlat: Drop interface_lock in stop_kthread() Date: Tue, 8 Oct 2024 14:09:23 +0200 Message-ID: <20241008115641.899347508@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241008115629.309157387@linuxfoundation.org> References: <20241008115629.309157387@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: Wei Li commit b484a02c9cedf8703eff8f0756f94618004bd165 upstream. stop_kthread() is the offline callback for "trace/osnoise:online", since commit 5bfbcd1ee57b ("tracing/timerlat: Add interface_lock around clearing of kthread in stop_kthread()"), the following ABBA deadlock scenario is introduced: T1 | T2 [BP] | T3 [AP] osnoise_hotplug_workfn() | work_for_cpu_fn() | cpuhp_thread_fun() | _cpu_down() | osnoise_cpu_die() mutex_lock(&interface_lock) | | stop_kthread() | cpus_write_lock() | mutex_lock(&interface_lock) cpus_read_lock() | cpuhp_kick_ap() | As the interface_lock here in just for protecting the "kthread" field of the osn_var, use xchg() instead to fix this issue. Also use for_each_online_cpu() back in stop_per_cpu_kthreads() as it can take cpu_read_lock() again. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Link: https://lore.kernel.org/20240924094515.3561410-3-liwei391@huawei.com Fixes: 5bfbcd1ee57b ("tracing/timerlat: Add interface_lock around clearing of kthread in stop_kthread()") Signed-off-by: Wei Li Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_osnoise.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index d1a539913a5f..e22567174dd3 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -1953,12 +1953,8 @@ static void stop_kthread(unsigned int cpu) { struct task_struct *kthread; - mutex_lock(&interface_lock); - kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread; + kthread = xchg_relaxed(&(per_cpu(per_cpu_osnoise_var, cpu).kthread), NULL); if (kthread) { - per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL; - mutex_unlock(&interface_lock); - if (cpumask_test_and_clear_cpu(cpu, &kthread_cpumask) && !WARN_ON(!test_bit(OSN_WORKLOAD, &osnoise_options))) { kthread_stop(kthread); @@ -1972,7 +1968,6 @@ static void stop_kthread(unsigned int cpu) put_task_struct(kthread); } } else { - mutex_unlock(&interface_lock); /* if no workload, just return */ if (!test_bit(OSN_WORKLOAD, &osnoise_options)) { /* @@ -1994,8 +1989,12 @@ static void stop_per_cpu_kthreads(void) { int cpu; - for_each_possible_cpu(cpu) + cpus_read_lock(); + + for_each_online_cpu(cpu) stop_kthread(cpu); + + cpus_read_unlock(); } /* -- 2.46.2