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 9EE5E22D4DC for ; Sun, 29 Mar 2026 07:19:08 +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=1774768748; cv=none; b=IUYYVnNy+xvk1XuO1lf5hqWaa4YnaXs1t/0t+Iv7+5NxnXG1FaRbp1u8HL4/E4D0HGXCi787fsuzRtSRMwql6sb6g4QDiJJ5U0jxOKQGYw/OUwSCLZpRYiOH4LlDGrYVgqwgjP+4n5IfUFXmccbzB0WLSFFeAgWMaIkUZLCBDwo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774768748; c=relaxed/simple; bh=udzKz5N/9NrXpiZUpAuPEYawJrPemkEgbcar5777UVE=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=ZvT0j+hPUmO8k0kFDUeKcsFk+pW5qtrY9U+6FPaW6vjz116EG6iufshSLfrf9U6HmurCZt3g6IciF7oURTVj2+AJeFh8FwVyOb/eZnIwwWedWP1og4lK9ulfotDWGBSSwjAJ9IqxIIe3A6EWoxneQDjk+vDMJxtg/UvIKGt1SpQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=snpAhVOS; 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="snpAhVOS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA09FC116C6; Sun, 29 Mar 2026 07:19:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774768748; bh=udzKz5N/9NrXpiZUpAuPEYawJrPemkEgbcar5777UVE=; h=Subject:To:Cc:From:Date:From; b=snpAhVOSEkzyOefX9/NMa0nWzBvUOEhXDxCDaXlkr0I65Q6ZMgmOFTIyjOmu7TMoc Y1SsyjZ4tNT41wNVh8PlfA3FtN3tqDqlr6O/1Xz89xAFSlNt+xUzwHoMrUHl/X0htM n/+J9bZl+jP6PFkDmKK1H+v737fQPNkY1S64Dj4Q= Subject: FAILED: patch "[PATCH] tracing: Fix potential deadlock in cpu hotplug with osnoise" failed to apply to 6.6-stable tree To: luo.haiyang@zte.com.cn,mathieu.desnoyers@efficios.com,mhiramat@kernel.org,ran.xiaokai@zte.com.cn,rostedt@goodmis.org,yang.tao172@zte.com.cn,zhang.run@zte.com.cn Cc: From: Date: Sun, 29 Mar 2026 09:18:53 +0200 Message-ID: <2026032953-garnet-dropout-ed0f@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 1f9885732248d22f788e4992c739a98c88ab8a55 # git commit -s git send-email --to '' --in-reply-to '2026032953-garnet-dropout-ed0f@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 1f9885732248d22f788e4992c739a98c88ab8a55 Mon Sep 17 00:00:00 2001 From: Luo Haiyang Date: Thu, 26 Mar 2026 14:19:53 +0800 Subject: [PATCH] tracing: Fix potential deadlock in cpu hotplug with osnoise 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) diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index dee610e465b9..be6cf0bb3c03 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -2073,8 +2073,8 @@ static void osnoise_hotplug_workfn(struct work_struct *dummy) 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(struct file *filp, const char __user *ubuf, 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(struct file *filp, const char __user *ubuf, 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, 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();