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 ECB40C43334 for ; Thu, 14 Jul 2022 04:37:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237652AbiGNEhP (ORCPT ); Thu, 14 Jul 2022 00:37:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44436 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232671AbiGNEgU (ORCPT ); Thu, 14 Jul 2022 00:36:20 -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 E5A203D591; Wed, 13 Jul 2022 21:26:37 -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 17F1261E91; Thu, 14 Jul 2022 04:26:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61554C34114; Thu, 14 Jul 2022 04:26:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657772796; bh=oL3oDNe2y17tLOJuvr/IYi8IQy7QdCfHnwou0u2wIic=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VC0wvr/vhMwG2Ocmmc0KsZv1LXIUHUux74sIrPiW8ov8wDVUWodaXIUAro67aWbfp cwzIvABuJD3foGS29tU91oipi+x9jp73v4YafWrwg6OSMJ5beVqGMWNoIWBnRQfX/C mCn/c7Hqh9qXAadRineilKisFWDVuyAXvoRWmjCsulzWwhprVGTtD+QWHPZGjNyHLy bSnHs+NpRMeu540lZMdcS4W47mmBJIYFfENmI7MdadAbW7UQBwqfsE4vs3n1zd8ugO tZLZPSE8zJT9EJ1vV93CKOQzD8YeP35RJBgbPDnpwOSBCKGuKtA1LKFlb/IPyFzhfc r1UyttXQmjh4g== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Linus Torvalds , Sasha Levin , ebiederm@xmission.com, keescook@chromium.org, oleg@redhat.com, tglx@linutronix.de, peterz@infradead.org Subject: [PATCH AUTOSEL 5.4 10/10] signal handling: don't use BUG_ON() for debugging Date: Thu, 14 Jul 2022 00:26:12 -0400 Message-Id: <20220714042612.282378-10-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220714042612.282378-1-sashal@kernel.org> References: <20220714042612.282378-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 3f61367fd168..1f4293a107b4 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1916,12 +1916,12 @@ 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))); /* Wake up all pidfd waiters */ -- 2.35.1