From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 80449501F45; Thu, 15 Oct 2026 13:34:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792071244; cv=none; b=UXs9pijwp/XpKJEld24FpFmjWRT7Q2cKEB0d/uWcyADhskAC41p0oymmBx756Ozia/O608LafM0XsGJcGLcnV5cqitgrUPgtw4p79Rtb64AcCY3PvYwwsPD8okD1gtD/nRx8Z2ULSZQYF9PbmndZ6+NPp5jsVQlo1IBfrDi7GLw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792071244; c=relaxed/simple; bh=jLD8Q8vLrM7j+RAudcNQFp0ehpuTw0DH4ujxsu39hbM=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=oS71AaeSZdC2dMlEzEINX/oJ95caUJeL89xQtKerXsGkVRrnRn5GPGb8dL7Y2rzDDhcBE5vYMUFO48YjoRGIIP41I3/2gvf0BnUYEAiGXKqBw27RFXy5VDmJcvnTq4fLi604kF0pw/vAKMw+DjSJwxgehEvPMllrt6/k8T3XqB4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YjTgcBct; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YjTgcBct" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 64C8F1F000C6; Thu, 15 Oct 2026 13:34:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792071243; bh=c3urZcT2n2z0ASdXCwrMB8MFTndefwF+qlh8RJCW3ZI=; h=Date:From:To:Cc:Subject:References; b=YjTgcBctogsRK9B+HOKIkTZDMeObrsjrFyNMf80jmvWenp6MNt8dDOGTGiPNJH7DO Sya15STw1bm17LPddMfp0aLBXY0R6ny/OWqHvRPpKcAULkDibEcbefh1b595VyYUih C90jXbng/iEC1YW1vRoEqHwpIQRIpKDoeAOnsCHi0Vo1tNU3G7uM2f0MSMb727LKKv If0GCcYg29Dgm+Uu8taRg8k4z+q0l5aj70X4el/dt30odOAh1l4gcDVPwtK9QjihAz 2nLEPPKbsdIV8+jm3LUL20vTAzq9UQydRkf2ogsy0oQge/83N89BF0N/lRi1oQjKB2 I/6rUowaSMnEQ== Received: from rostedt by gandalf with local (Exim 4.100.1) (envelope-from ) id 1xHLas-00000000Mb3-2x6g; Thu, 15 Oct 2026 09:34:02 -0400 Message-ID: <20261015133402.510689146@kernel.org> User-Agent: quilt/0.69 Date: Thu, 15 Oct 2026 09:33:13 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , stable@vger.kernel.org, Sashiko , David Carlier Subject: [for-linus][PATCH 03/16] ring-buffer: Do not show buffer_meta for CPUs without a buffer References: <20261015133310.731003448@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: David Carlier The per_cpu/cpuN/buffer_meta files are created for every possible CPU, but buffer->buffers[cpu] is only allocated once that CPU comes online. Reading the file of a CPU that never came online dereferences a NULL cpu_buffer in rbm_start(). Fail the open with -ENODEV when the CPU has no buffer, as the other per CPU ring buffer interfaces do. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260914133506.4865-3-devnexen@gmail.com Fixes: 950032ffcee7 ("ring-buffer: Add output of ring buffer meta page") Reported-by: Sashiko Closes: https://lore.kernel.org/all/20260913134906.6E8A01F000FF@smtp.kernel.org/ Signed-off-by: David Carlier Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 04bb94c29f58..ce179619e655 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2380,6 +2380,9 @@ int ring_buffer_meta_seq_init(struct file *file, struct trace_buffer *buffer, in struct seq_file *m; int ret; + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + return -ENODEV; + ret = seq_open(file, &rb_meta_seq_ops); if (ret) return ret; -- 2.53.0