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 C5D756FC9 for ; Sun, 17 Sep 2023 19:38:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 339FBC433C8; Sun, 17 Sep 2023 19:38:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1694979516; bh=LuXKwXSbLwWdOI8ZrzyXLYo1tMCI4+avI3yNJJfzFaA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zJ0MKHEHlAZMRIO/rgVKXLy1NcCBOapH5LA+eDTRJtl1FrK4k595eH7RLzkT6+Rc5 juR0uQBPhdH4jhzw+GuquhWLhA+Xu7hKapEtxP8tS/JIO63tn6YWSfdUTDGT7qhckF n/NKeEnSgB57Ly2F/sbWV36gkBkjsmFm41pXeuxY= 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 5.10 310/406] tracing: Zero the pipe cpumask on alloc to avoid spurious -EBUSY Date: Sun, 17 Sep 2023 21:12:44 +0200 Message-ID: <20230917191109.489562899@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230917191101.035638219@linuxfoundation.org> References: <20230917191101.035638219@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-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 @@ -8890,7 +8890,7 @@ 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; @@ -9736,7 +9736,7 @@ __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 */