From patchwork Mon Jul 10 21:29:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zheng Yejian X-Patchwork-Id: 13306573 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 B4911EB64D9 for ; Mon, 10 Jul 2023 09:32:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231917AbjGJJc3 (ORCPT ); Mon, 10 Jul 2023 05:32:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51004 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232797AbjGJJbz (ORCPT ); Mon, 10 Jul 2023 05:31:55 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0DF692D45; Mon, 10 Jul 2023 02:30:20 -0700 (PDT) Received: from dggpeml500012.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4QzzFR1QR2zTmRB; Mon, 10 Jul 2023 17:28:11 +0800 (CST) Received: from localhost.localdomain (10.67.175.61) by dggpeml500012.china.huawei.com (7.185.36.15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Mon, 10 Jul 2023 17:29:21 +0800 From: Zheng Yejian To: , CC: , , Subject: [PATCH] ftrace: Fix possible warning on checking all pages used in ftrace_process_locs() Date: Tue, 11 Jul 2023 05:29:58 +0800 Message-ID: <20230710212958.274126-1-zhengyejian1@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.67.175.61] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpeml500012.china.huawei.com (7.185.36.15) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org As comments in ftrace_process_locs(), there may be NULL pointers in mcount_loc section: > Some architecture linkers will pad between > the different mcount_loc sections of different > object files to satisfy alignments. > Skip any NULL pointers. After 20e5227e9f55 ("ftrace: allow NULL pointers in mcount_loc"), NULL pointers will be accounted when allocating ftrace pages but skipped before adding into ftrace pages, this may result in some pages not being used. Then after 706c81f87f84 ("ftrace: Remove extra helper functions"), warning may occur at: WARN_ON(pg->next); So we may need to skip NULL pointers before allocating ftrace pages. Fixes: 706c81f87f84 ("ftrace: Remove extra helper functions") Signed-off-by: Zheng Yejian --- kernel/trace/ftrace.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 3740aca79fe7..5b474165df31 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -6485,6 +6485,16 @@ static int ftrace_process_locs(struct module *mod, if (!count) return 0; + p = start; + while (p < end) { + /* + * Refer to conments below, there may be NULL pointers, + * skip them before allocating pages + */ + addr = ftrace_call_adjust(*p++); + if (!addr) + count--; + } /* * Sorting mcount in vmlinux at build time depend on * CONFIG_BUILDTIME_MCOUNT_SORT, while mcount loc in