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 EF7D73939BC for ; Mon, 30 Mar 2026 18:37:42 +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=1774895863; cv=none; b=oBykRb8bVFepVpxv3n4StFh7EuF6Mkx9sQI7p+MYx1+/UW/RULT5oIYJ7jkJbKuv1tZ/wWtgKeuGQRNM1XKNP6OSvwlRMfrPFCt00AO+Wnhs5T3PKLu0H7rOXUMTFvDcX0u7FQo0S6zSlamzX9ZEa2O4Wgu2Sl9a80LNGRiF2mQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774895863; c=relaxed/simple; bh=RJkQrMB7pQepheHQ0DQOJsBYT6CADPChA0Jy5HCWB8k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DfZFiEq7LipR1Z2ELX+yemus5xII3zXeGEUuD1JCVCPR/v4rH5gSg6JRQLoL54ztWzuLfQvxmepThsXWvp6BCCA+vQt8MP/R6jHLK6o492yXTOmLw07tLgo/7i01EgRX+0kiUEnuRQO6QIH0O5OFtmuNdIlumLpNMIxEnSxJWhk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=G2AqdBS9; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="G2AqdBS9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7D0ACC4CEF7; Mon, 30 Mar 2026 18:37:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774895862; bh=RJkQrMB7pQepheHQ0DQOJsBYT6CADPChA0Jy5HCWB8k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=G2AqdBS9vSH6aOLfJH8MgKYIQUFXcTeBNBA+Y5uApjLuxU2YnI08xKh8OyDkacIqP e/X9oFiC2xOAdvJaM7x07+5LLiXcEw3JpRAo01K6ROMY0ZkVEeadXdNIqkvIZdBv64 g8FaWVdjWo1lzeyS2nZ5rtQvIdJ3LFTwIsDSqt7OSlmStQAvk5VD6zFs84pJmaRWIy GXOGoHQIkQ2emJP1GYWBf3prjxtpTbvVYTn2Vh013n4ToaMf8cjtBeeezVDo9gaC3G h+5jwfZgMcwIF75FrT0Nh9GTNmWxLjPUM94NgFMm/Y4qZkiYqsU33ue7+B0kIdoMG5 F6zHwV22J+0hw== From: Sasha Levin To: stable@vger.kernel.org Cc: Luo Haiyang , mathieu.desnoyers@efficios.com, zhang.run@zte.com.cn, yang.tao172@zte.com.cn, ran.xiaokai@zte.com.cn, "Masami Hiramatsu (Google)" , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 6.1.y] tracing: Fix potential deadlock in cpu hotplug with osnoise Date: Mon, 30 Mar 2026 14:37:39 -0400 Message-ID: <20260330183739.934195-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026032953-disinfect-spinning-5c06@gregkh> References: <2026032953-disinfect-spinning-5c06@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Luo Haiyang [ Upstream commit 1f9885732248d22f788e4992c739a98c88ab8a55 ] The following sequence may leads deadlock in cpu hotplug: task1 task2 task3 ----- ----- ----- mutex_lock(&interface_lock) [CPU GOING OFFLINE] cpus_write_lock(); osnoise_cpu_die(); kthread_stop(task3); wait_for_completion(); osnoise_sleep(); mutex_lock(&interface_lock); cpus_read_lock(); [DEAD LOCK] Fix by swap the order of cpus_read_lock() and mutex_lock(&interface_lock). Cc: stable@vger.kernel.org Cc: Cc: Cc: Cc: Fixes: bce29ac9ce0bb ("trace: Add osnoise tracer") Link: https://patch.msgid.link/20260326141953414bVSj33dAYktqp9Oiyizq8@zte.com.cn Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Luo Haiyang Signed-off-by: Steven Rostedt (Google) [ adapted guard() macros to lock/unlock calls ] Signed-off-by: Sasha Levin --- kernel/trace/trace_osnoise.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index e5929cb3840f4..676d9a3e65cde 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -1809,8 +1809,8 @@ static void osnoise_hotplug_workfn(struct work_struct *dummy) if (!osnoise_has_registered_instances()) goto out_unlock_trace; - mutex_lock(&interface_lock); cpus_read_lock(); + mutex_lock(&interface_lock); if (!cpu_online(cpu)) goto out_unlock; @@ -1820,8 +1820,8 @@ static void osnoise_hotplug_workfn(struct work_struct *dummy) start_kthread(cpu); out_unlock: - cpus_read_unlock(); mutex_unlock(&interface_lock); + cpus_read_unlock(); out_unlock_trace: mutex_unlock(&trace_types_lock); } @@ -1950,16 +1950,16 @@ osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count, if (running) stop_per_cpu_kthreads(); - mutex_lock(&interface_lock); /* * osnoise_cpumask is read by CPU hotplug operations. */ cpus_read_lock(); + mutex_lock(&interface_lock); cpumask_copy(&osnoise_cpumask, osnoise_cpumask_new); - cpus_read_unlock(); mutex_unlock(&interface_lock); + cpus_read_unlock(); if (running) start_per_cpu_kthreads(); -- 2.53.0