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 9FB9E2FE042; Tue, 31 Mar 2026 17:04:17 +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=1774976657; cv=none; b=DGRCiT4rKrZk/xtoF07dT2ECX4idnrrTx1gDPxfiD4mTNo0UNCyLKR6ElTS07k1CdaLjni24knaWt3lQkVEGV7mveacnQgxA6vu9hxV4Op0NIchAg9AVQQ7xWI8uwaTooJ6ycOwosaJfijbwIwNr8vTVQlTcQcPhlaPDDNtErkY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774976657; c=relaxed/simple; bh=EYSShiSVo6SLntcp+/X6iQY0ObyWc89XPWp1JKayZjA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DvsAMvfzGevoip76NwPPu2O07K7onxDU2Ox1qRIGOEK76CtfkMQvYnN/cwlMlNqDNQpMkwxLdsrTSYd9ANSy49bUNg40gVA91pQepdlR5Uauke8ZTnxCxSo8GCrbBj+VKse5jAsVpNxir2K5xIrcNwfJJ6qLFStKOOYjZJts4W8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=zUY01rcB; 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="zUY01rcB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CC55DC19423; Tue, 31 Mar 2026 17:04:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774976657; bh=EYSShiSVo6SLntcp+/X6iQY0ObyWc89XPWp1JKayZjA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zUY01rcBFVgU+aYtPcv328+aG6k6uxFlfz/2cpbZ80P+ghrff9vIjbGBMAY8JAiPT 6ANWlDtfUlEWKKtHnSi9PmM/G6IykmAGtWHZXXILWdrezOZpo60//tgZdszO58KRHi +wyZphIhGp0xSVL1R8o9GGTqLZgiuI8L0DEtyHjU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, mathieu.desnoyers@efficios.com, zhang.run@zte.com.cn, yang.tao172@zte.com.cn, ran.xiaokai@zte.com.cn, "Masami Hiramatsu (Google)" , Luo Haiyang , "Steven Rostedt (Google)" Subject: [PATCH 6.18 178/309] tracing: Fix potential deadlock in cpu hotplug with osnoise Date: Tue, 31 Mar 2026 18:21:21 +0200 Message-ID: <20260331161800.016931002@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260331161753.468533260@linuxfoundation.org> References: <20260331161753.468533260@linuxfoundation.org> User-Agent: quilt/0.69 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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luo Haiyang commit 1f9885732248d22f788e4992c739a98c88ab8a55 upstream. 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) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_osnoise.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -2073,8 +2073,8 @@ static void osnoise_hotplug_workfn(struc if (!osnoise_has_registered_instances()) return; - guard(mutex)(&interface_lock); guard(cpus_read_lock)(); + guard(mutex)(&interface_lock); if (!cpu_online(cpu)) return; @@ -2237,11 +2237,11 @@ static ssize_t osnoise_options_write(str if (running) stop_per_cpu_kthreads(); - mutex_lock(&interface_lock); /* * avoid CPU hotplug operations that might read options. */ cpus_read_lock(); + mutex_lock(&interface_lock); retval = cnt; @@ -2257,8 +2257,8 @@ static ssize_t osnoise_options_write(str clear_bit(option, &osnoise_options); } - cpus_read_unlock(); mutex_unlock(&interface_lock); + cpus_read_unlock(); if (running) start_per_cpu_kthreads(); @@ -2345,16 +2345,16 @@ osnoise_cpus_write(struct file *filp, co 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();