From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (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 139FC279DA6; Tue, 19 Aug 2025 10:36:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755599812; cv=none; b=u/sxI7ZJxFbmWRfoc0eKTfDtmKNbT5ZgvGZ0qqTPWpvj/YD7OwWA7/FmlhJBenUGzmUIVCujm+2Q/grdjud6Y5Ui7UK9ZQXqSbYy4aTPcIG61/MIXqcGfzp3io5/2gTEhYksHxGKc8IJyog8YpqKGFz+keFGyoV86wT2S/SPYiA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755599812; c=relaxed/simple; bh=Z7kL+Z/mU5muHOMu+t9d0O8CwxLHDaEDx6Wa2Vl/xEA=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=fcAQIVMjmTOWiLssDyE8v0An3fMqvl1nbKk5ybt3ygS+iCS7UoRUUyib0B3jBBkjA9c9HFT5fKwPX9swT358PSJ5pA4bBN8G4JQe8bmWPVfxRRdxsruBbrvQrqjCW9BEfyBEM8Gu9tTUa1Qx5b8SzwoJr/lBkE6fFQ++dXHC/WM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4c5mGk6lTKzKHMy8; Tue, 19 Aug 2025 18:36:46 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 5C12B1A0EA4; Tue, 19 Aug 2025 18:36:46 +0800 (CST) Received: from huaweicloud.com (unknown [10.67.174.193]) by APP4 (Coremail) with SMTP id gCh0CgBXIBG8U6RoPMTREA--.2499S4; Tue, 19 Aug 2025 18:36:46 +0800 (CST) From: Luo Gengkun To: rostedt@goodmis.org Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, luogengkun@huaweicloud.com Subject: [PATCH] tracing: Fix tracing_marker may trigger page fault during preempt_disable Date: Tue, 19 Aug 2025 10:51:52 +0000 Message-Id: <20250819105152.2766363-1-luogengkun@huaweicloud.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:gCh0CgBXIBG8U6RoPMTREA--.2499S4 X-Coremail-Antispam: 1UD129KBjvJXoW7KryxCF4xAF1DZry5GFWfXwb_yoW8KFWUpF 1fK39rKr4kXFWjyasrX3W8X34rWrWDW34xKF4kWw1fXry2kr1DZryUt3ZaqFW5tFy7t34x tF4jyrZ8Ka4Yvw7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkG14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0 I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r 4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwCY1x0262kKe7AKxVWU AVWUtwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14 v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_JF0_Jw1lIxkG c2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI 0_Jr0_Gr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4U MIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUBVbkUUU UU= X-CM-SenderInfo: 5oxrwvpqjn3046kxt4xhlfz01xgou0bp/ 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. Fixes: 656c7f0d2d2b ("tracing: Replace kmap with copy_from_user() in trace_marker writing") Signed-off-by: Luo Gengkun --- 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 95ae7c4e5835..a41d1acf15a0 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -7271,7 +7271,7 @@ 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; @@ -7368,7 +7368,7 @@ 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); -- 2.34.1