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 X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B2252C43219 for ; Tue, 30 Apr 2019 09:11:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8DF6220652 for ; Tue, 30 Apr 2019 09:11:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726894AbfD3JK5 (ORCPT ); Tue, 30 Apr 2019 05:10:57 -0400 Received: from mx2.suse.de ([195.135.220.15]:36470 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726865AbfD3JKy (ORCPT ); Tue, 30 Apr 2019 05:10:54 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id A31BEAE5A; Tue, 30 Apr 2019 09:10:53 +0000 (UTC) From: Petr Mladek To: Jiri Kosina , Josh Poimboeuf , Miroslav Benes Cc: Joe Lawrence , Kamalesh Babulal , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, Petr Mladek Subject: [PATCH v2 1/2] livepatch: Remove duplicate warning about missing reliable stacktrace support Date: Tue, 30 Apr 2019 11:10:48 +0200 Message-Id: <20190430091049.30413-2-pmladek@suse.com> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20190430091049.30413-1-pmladek@suse.com> References: <20190430091049.30413-1-pmladek@suse.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org WARN_ON_ONCE() could not be called safely under rq lock because of console deadlock issues. Fortunately, there is another check for the reliable stacktrace support in klp_enable_patch(). Signed-off-by: Petr Mladek --- kernel/livepatch/transition.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c index 9c89ae8b337a..8e0274075e75 100644 --- a/kernel/livepatch/transition.c +++ b/kernel/livepatch/transition.c @@ -263,8 +263,15 @@ static int klp_check_stack(struct task_struct *task, char *err_buf) trace.nr_entries = 0; trace.max_entries = MAX_STACK_ENTRIES; trace.entries = entries; + ret = save_stack_trace_tsk_reliable(task, &trace); - WARN_ON_ONCE(ret == -ENOSYS); + /* + * pr_warn() under task rq lock might cause a deadlock. + * Fortunately, missing reliable stacktrace support has + * already been handled when the livepatch was enabled. + */ + if (ret == -ENOSYS) + return ret; if (ret) { snprintf(err_buf, STACK_ERR_BUF_SIZE, "%s: %s:%d has an unreliable stack\n", -- 2.16.4