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 50427CCA47B for ; Thu, 14 Jul 2022 04:38:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237693AbiGNEiE (ORCPT ); Thu, 14 Jul 2022 00:38:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44826 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237563AbiGNEhS (ORCPT ); Thu, 14 Jul 2022 00:37:18 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A545D3DBD5; Wed, 13 Jul 2022 21:26:56 -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 sin.source.kernel.org (Postfix) with ESMTPS id 42892CE253C; Thu, 14 Jul 2022 04:26:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96DC0C3411C; Thu, 14 Jul 2022 04:26:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657772812; bh=l1u1mqPWr6KkvTGe6RxTRSXt6DLJuiZb38yg1TUF2gA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Njv6U6b+6RnBrCtsfTs1R0YahqcjhOH7fAMFZ4as7EdB+jdMr5QkvPrjS+/aIjRjr n2BNiKKMIDeuC7rb2QUwSYAeUttxVX+HmLlN3/sCGZnNq1Y4JAIYYnZmLJUlqS4WMt 7KDUQZs0z/rHyiYoPOrEMKmg49HO4gGAKZSrKBtpLhExqH5aCSAkZ5vx7FVSn4PG/z vJ0G4Y2kY8kUjyUNk1k9AY+UMhQwlvIBYYFrqJ3qrcirzyZ0BXBdxc81GilftspU27 iFu8YGlbDjcl83k1vW/hh5EUK8s+XiZ2H5am2Ns+7aLVQB/nvgjz2tys4xPde/tNCl Q7npWQ6jojiZg== 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 4.19 6/6] signal handling: don't use BUG_ON() for debugging Date: Thu, 14 Jul 2022 00:26:36 -0400 Message-Id: <20220714042637.282511-6-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220714042637.282511-1-sashal@kernel.org> References: <20220714042637.282511-1-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 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