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 66266C43334 for ; Thu, 14 Jul 2022 04:32:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237539AbiGNEcz (ORCPT ); Thu, 14 Jul 2022 00:32:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36142 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237494AbiGNEb7 (ORCPT ); Thu, 14 Jul 2022 00:31:59 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E36B2A27C; Wed, 13 Jul 2022 21:25:41 -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 EF99D61E4E; Thu, 14 Jul 2022 04:25:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C71FC36AF3; Thu, 14 Jul 2022 04:25:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657772740; bh=fHBYmqcIiLMomw61JKDjJgzcDQQWoa5ofC83PhIIq4k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FcPpjw4GirVgmxpcQ62KqLVCOIj3o9sBr8chQbttcJ+LdxS7s0B6bBJK6QWiU4gRG URqQudDE7RsSpEpc47kjtpKnFPc3YCZJ/fAIX7A8QGyAPzjqIsHTV4lS6Hsqlm1QI4 y3p86oA41m7RgtC76T+cQeAXSfX9aVD+KjJy9xQTAMmXNsj7yQXVmNLkIcvUnG7+8h ag8UaPvLyYjK4ZF53vbmVtPsGlNffG/5ijU6rVrsilGWJcfytykWFF3embm/LSq/dw diCs1fjdUyp/X+mKFCZ6kwe4ubtuZFwVD8z42VMNUEhjg1ld0B6XCRLZ/0gXiMh+mW MDPtaHkRsPDAA== 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 5.15 28/28] signal handling: don't use BUG_ON() for debugging Date: Thu, 14 Jul 2022 00:24:29 -0400 Message-Id: <20220714042429.281816-28-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220714042429.281816-1-sashal@kernel.org> References: <20220714042429.281816-1-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 d831f0aec56e..c7dbb19219b9 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2027,12 +2027,12 @@ 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