From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6CCC9CA0ECE for ; Mon, 11 Sep 2023 22:23:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376728AbjIKWUV (ORCPT ); Mon, 11 Sep 2023 18:20:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47896 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241077AbjIKPBU (ORCPT ); Mon, 11 Sep 2023 11:01:20 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A5E8E125 for ; Mon, 11 Sep 2023 08:01:16 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EBE8FC433C8; Mon, 11 Sep 2023 15:01:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1694444476; bh=+KexGC+tLL+ZC/2i4y6EM2xAX1YSutjawc5Tkv2dTkA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MWklLxJcrnoWajUw/zxTxJHneS5ukiolfSfqQN1aWtzfN0eEJvVqkrYT+8DgpNkFJ JBXcjy0In3fXMMXg2WwsVYJK344O5RIHttipkgx+JhZRRcQJGMeojYtJLfY6PWztcr vnRHHalbZadwe4bM6LF7ZaetKjZnmSJidePJSzhY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zheng Yejian , "Masami Hiramatsu (Google)" , Brian Foster , "Steven Rostedt (Google)" Subject: [PATCH 6.4 736/737] tracing: Zero the pipe cpumask on alloc to avoid spurious -EBUSY Date: Mon, 11 Sep 2023 15:49:55 +0200 Message-ID: <20230911134711.080313281@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230911134650.286315610@linuxfoundation.org> References: <20230911134650.286315610@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 6.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Brian Foster commit 3d07fa1dd19035eb0b13ae6697efd5caa9033e74 upstream. The pipe cpumask used to serialize opens between the main and percpu trace pipes is not zeroed or initialized. This can result in spurious -EBUSY returns if underlying memory is not fully zeroed. This has been observed by immediate failure to read the main trace_pipe file on an otherwise newly booted and idle system: # cat /sys/kernel/debug/tracing/trace_pipe cat: /sys/kernel/debug/tracing/trace_pipe: Device or resource busy Zero the allocation of pipe_cpumask to avoid the problem. Link: https://lore.kernel.org/linux-trace-kernel/20230831125500.986862-1-bfoster@redhat.com Cc: stable@vger.kernel.org Fixes: c2489bb7e6be ("tracing: Introduce pipe_cpumask to avoid race on trace_pipes") Reviewed-by: Zheng Yejian Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Brian Foster Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9465,7 +9465,7 @@ static struct trace_array *trace_array_c if (!alloc_cpumask_var(&tr->tracing_cpumask, GFP_KERNEL)) goto out_free_tr; - if (!alloc_cpumask_var(&tr->pipe_cpumask, GFP_KERNEL)) + if (!zalloc_cpumask_var(&tr->pipe_cpumask, GFP_KERNEL)) goto out_free_tr; tr->trace_flags = global_trace.trace_flags & ~ZEROED_TRACE_FLAGS; @@ -10410,7 +10410,7 @@ __init static int tracer_alloc_buffers(v if (trace_create_savedcmd() < 0) goto out_free_temp_buffer; - if (!alloc_cpumask_var(&global_trace.pipe_cpumask, GFP_KERNEL)) + if (!zalloc_cpumask_var(&global_trace.pipe_cpumask, GFP_KERNEL)) goto out_free_savedcmd; /* TODO: make the number of buffers hot pluggable with CPUS */