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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2DF95C433EF for ; Tue, 19 Jul 2022 11:56:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235098AbiGSL4w (ORCPT ); Tue, 19 Jul 2022 07:56:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237405AbiGSL4Y (ORCPT ); Tue, 19 Jul 2022 07:56:24 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0E29742AF3; Tue, 19 Jul 2022 04:56:15 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6BC8760B27; Tue, 19 Jul 2022 11:56:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4EB58C341D2; Tue, 19 Jul 2022 11:56:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658231774; bh=GrpiY04TRssppqR1dIMePz1Wt0TmdIADoyIxY+yyqyI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cAcVb9qz1aJeFaE8igifywpdnewCWDZmY6VeShN+MQuExaY4yOY6IGRnkb8ENQjO9 PsaSQuxh38IvLyDGsAGwfoVrClpKIU/HVqJ+Cccn7MqLUPDFmf3k+O+AR2hc9iy80P 6WACz5+xm8S+f5xXmqJZfMkmrDCxDE2lbidRhssY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Linus Torvalds , Sasha Levin Subject: [PATCH 4.9 22/28] signal handling: dont use BUG_ON() for debugging Date: Tue, 19 Jul 2022 13:54:00 +0200 Message-Id: <20220719114458.196731769@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220719114455.701304968@linuxfoundation.org> References: <20220719114455.701304968@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Linus Torvalds [ Upstream commit a382f8fee42ca10c9bfce0d2352d4153f931f5dc ] These are indeed "should not happen" situations, but it turns out recent changes made the 'task_is_stopped_or_trace()' case trigger (fix for that exists, is pending more testing), and the BUG_ON() makes it unnecessarily hard to actually debug for no good reason. It's been that way for a long time, but let's make it clear: BUG_ON() is not good for debugging, and should never be used in situations where you could just say "this shouldn't happen, but we can continue". Use WARN_ON_ONCE() instead to make sure it gets logged, and then just continue running. Instead of making the system basically unusuable because you crashed the machine while potentially holding some very core locks (eg this function is commonly called while holding 'tasklist_lock' for writing). Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- kernel/signal.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index 2c26af848e68..670755212d35 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1647,12 +1647,12 @@ bool do_notify_parent(struct task_struct *tsk, int sig) bool autoreap = false; cputime_t utime, stime; - BUG_ON(sig == -1); + WARN_ON_ONCE(sig == -1); - /* do_notify_parent_cldstop should have been called instead. */ - BUG_ON(task_is_stopped_or_traced(tsk)); + /* do_notify_parent_cldstop should have been called instead. */ + WARN_ON_ONCE(task_is_stopped_or_traced(tsk)); - BUG_ON(!tsk->ptrace && + WARN_ON_ONCE(!tsk->ptrace && (tsk->group_leader != tsk || !thread_group_empty(tsk))); if (sig != SIGCHLD) { -- 2.35.1