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 26FEFC433EF for ; Thu, 14 Jul 2022 04:35:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237594AbiGNEff (ORCPT ); Thu, 14 Jul 2022 00:35:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46648 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237622AbiGNEeW (ORCPT ); Thu, 14 Jul 2022 00:34:22 -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 734E43B94F; Wed, 13 Jul 2022 21:26:13 -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 C901061EB7; Thu, 14 Jul 2022 04:26:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B58FC34115; Thu, 14 Jul 2022 04:26:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657772772; bh=VZ/ySEKwch8hX9Yt/2DDVKTkE+/L3t9gTkYGiHmEYrA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZR/5s/dqmdmoH/bM1Vv68O3EeRJj+mNxqAR00HsOmjID/zTVCf4I7Vp0AhF5UnAki WS283CUyAUYvIQ8eLi6SY5EPpPYFOln5b0Vz4SXaXo880Rtvz7V+sGc11e7ojhydfB KfEYgMpPCtfPNhiLFoYtSVM57Z+hhvlmH9BOCoIrTNohhirWNJg+1fZr+x/Kr/HfUg buhWG1zBe2VNYTDuZsPdufj1QB6FgKy/UFAIt9+EjV9hsBWL721vGEFYJeK7V98JpV gtP4y+5EJYk3grl9if3pCnWcBl2V5z1OabPfhPU61T50Mh949xYtJqzubEc0YE4ZuS acWK1oYsctEKA== 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 5.10 15/15] signal handling: don't use BUG_ON() for debugging Date: Thu, 14 Jul 2022 00:25:40 -0400 Message-Id: <20220714042541.282175-15-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220714042541.282175-1-sashal@kernel.org> References: <20220714042541.282175-1-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 6bb2df4f6109..d05f783d5a5e 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1912,12 +1912,12 @@ 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