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 913C418BBAE; Wed, 17 Sep 2025 12:36:56 +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=1758112616; cv=none; b=ihTW4N+BWn2muptvtCJobfzLwSJak+b+j+aYNsuN+nzte3ww+BP6GkcZduXLaY8MZIh1Q1jufNUeJR2tk5pnTiI8xhXHIAEm9LYRbuZgONHyhRmnsozMZRDFh3gdTizrX5Hh07nErNHte0YecNmlEylSzcByaNmooUxfOle01+k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758112616; c=relaxed/simple; bh=GpnjrNWy7ce3eADCDtq1zTRyh7oqj6Ml1uUOSl6dIUk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZRDfSHy1z2A750Cgqg5Ixa05KLvuWLQdMqasBsKwbWi3pQCcP3vpCr6B0gRs1XeYvii+kbzjM+cLCLtCuWc1F07f3ymPnT3CHa+mhCYDeCfRqVwL6xojXu3yLucaYsFN+y4hYpPO0kkmxKn/IR8z0+kBUeLUqP+Pi+9ZszFS6h0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rDoaQ6OD; 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="rDoaQ6OD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C94C8C4CEF0; Wed, 17 Sep 2025 12:36:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1758112616; bh=GpnjrNWy7ce3eADCDtq1zTRyh7oqj6Ml1uUOSl6dIUk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rDoaQ6OD0Pf68PFPwSQW9kzkkuFHt0g+iVqirXDtFToNEE16bOumdvPHMu/xMyz9r oQkEuk3JzNNtB65N5tfzviwEUWhzD0I6IGfMGDqYldzgbWXXjc5AI9HC5LCNpe6NI4 QVlrtqfdm7luEWK6SKWCNCA41CVFUDt02WKPU8Zs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Luo Gengkun , "Masami Hiramatsu (Google)" , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 6.16 025/189] tracing: Fix tracing_marker may trigger page fault during preempt_disable Date: Wed, 17 Sep 2025 14:32:15 +0200 Message-ID: <20250917123352.469213276@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250917123351.839989757@linuxfoundation.org> References: <20250917123351.839989757@linuxfoundation.org> User-Agent: quilt/0.68 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 6.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luo Gengkun [ Upstream commit 3d62ab32df065e4a7797204a918f6489ddb8a237 ] Both tracing_mark_write and tracing_mark_raw_write call __copy_from_user_inatomic during preempt_disable. But in some case, __copy_from_user_inatomic may trigger page fault, and will call schedule() subtly. And if a task is migrated to other cpu, the following warning will be trigger: if (RB_WARN_ON(cpu_buffer, !local_read(&cpu_buffer->committing))) An example can illustrate this issue: process flow CPU --------------------------------------------------------------------- tracing_mark_raw_write(): cpu:0 ... ring_buffer_lock_reserve(): cpu:0 ... cpu = raw_smp_processor_id() cpu:0 cpu_buffer = buffer->buffers[cpu] cpu:0 ... ... __copy_from_user_inatomic(): cpu:0 ... # page fault do_mem_abort(): cpu:0 ... # Call schedule schedule() cpu:0 ... # the task schedule to cpu1 __buffer_unlock_commit(): cpu:1 ... ring_buffer_unlock_commit(): cpu:1 ... cpu = raw_smp_processor_id() cpu:1 cpu_buffer = buffer->buffers[cpu] cpu:1 As shown above, the process will acquire cpuid twice and the return values are not the same. To fix this problem using copy_from_user_nofault instead of __copy_from_user_inatomic, as the former performs 'access_ok' before copying. Link: https://lore.kernel.org/20250819105152.2766363-1-luogengkun@huaweicloud.com Fixes: 656c7f0d2d2b ("tracing: Replace kmap with copy_from_user() in trace_marker writing") Signed-off-by: Luo Gengkun Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- kernel/trace/trace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b91fa02cc54a6..9329ac1667551 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -7264,7 +7264,7 @@ static ssize_t write_marker_to_buffer(struct trace_array *tr, const char __user entry = ring_buffer_event_data(event); entry->ip = ip; - len = __copy_from_user_inatomic(&entry->buf, ubuf, cnt); + len = copy_from_user_nofault(&entry->buf, ubuf, cnt); if (len) { memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE); cnt = FAULTED_SIZE; @@ -7361,7 +7361,7 @@ static ssize_t write_raw_marker_to_buffer(struct trace_array *tr, entry = ring_buffer_event_data(event); - len = __copy_from_user_inatomic(&entry->id, ubuf, cnt); + len = copy_from_user_nofault(&entry->id, ubuf, cnt); if (len) { entry->id = -1; memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE); -- 2.51.0