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 3CCB9C433EF for ; Tue, 19 Jul 2022 12:06:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238353AbiGSMGd (ORCPT ); Tue, 19 Jul 2022 08:06:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238486AbiGSMEn (ORCPT ); Tue, 19 Jul 2022 08:04:43 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1CEE4D4CD; Tue, 19 Jul 2022 05:00:39 -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 12A5A61655; Tue, 19 Jul 2022 12:00:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E59ABC341CF; Tue, 19 Jul 2022 12:00:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658232038; bh=l1u1mqPWr6KkvTGe6RxTRSXt6DLJuiZb38yg1TUF2gA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0hysTn1B4clQ3hZ1glUGjcFSDBj0FbiMkCfHs382x2sO+lfWxlAUcYfh6Z4/hCjgK YpllUlYn4yeWY/62NS87KklkJ3SLEYoW6v3BK2mmM0oa1H1pC/fko4ArVZJAXPB2P4 +/AjXFZlOd3FFEPhNUWn64T54D9EorDcHdnZyTpw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Linus Torvalds , Sasha Levin Subject: [PATCH 4.19 40/48] signal handling: dont use BUG_ON() for debugging Date: Tue, 19 Jul 2022 13:54:17 +0200 Message-Id: <20220719114523.368849978@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220719114518.915546280@linuxfoundation.org> References: <20220719114518.915546280@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 4cc3f3ba13a9..c79b87ac1041 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1825,12 +1825,12 @@ bool do_notify_parent(struct task_struct *tsk, int sig) bool autoreap = false; u64 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