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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5988BC433E0 for ; Tue, 23 Jun 2020 00:10:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 23631206C3 for ; Tue, 23 Jun 2020 00:10:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592871017; bh=uM60TInvRXu0eMKTDe77HJ7sHKmRkq4gHqQx5e+Uvlc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=fo7XC6Kulzl2K3Ttg7v3OrYpXO3PlsPGUbThuvjXINmA4oOaGt9iN79wfgywccKah g/nW6wblmHaxK1qTK3odPRtu509sAzV7bEx2604TzdI5VDr2m81nKh/W/D8gk2qtyA 9nRSDLUiv+VDpYVjkk3th+7b8wXy62vi4VJmZoUU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731583AbgFWAKO (ORCPT ); Mon, 22 Jun 2020 20:10:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:43714 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731509AbgFWAJw (ORCPT ); Mon, 22 Jun 2020 20:09:52 -0400 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 448A4208D5; Tue, 23 Jun 2020 00:09:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592870991; bh=uM60TInvRXu0eMKTDe77HJ7sHKmRkq4gHqQx5e+Uvlc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rstvupwShAsU/O3Oi1QFL6+CllrDQW6i5xe0TtGBSXkuKxan/hzR7QrSk5YrgBlee 5QNooCWEXQmTfxnCP7PQzVQd8iDNsFaPVx0hB8QN9tyVmvP1Yfhw50idxbcFKE3Bgd F7zp3aMe8SnnKbDGN8LtaxE28pVfZmn7w4jXY0Lo= From: paulmck@kernel.org To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 09/10] doc: Timer problems can cause RCU CPU stall warnings Date: Mon, 22 Jun 2020 17:09:46 -0700 Message-Id: <20200623000947.25222-9-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200623000923.GA25047@paulmck-ThinkPad-P72> References: <20200623000923.GA25047@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" Over the past few years, there have been several cases where timekeeping bugs have caused RCU CPU stall warnings, particularly during hardware bringup. This commit therefore adds such bugs to the list of things that can result in RCU CPU stall warnings. Signed-off-by: Paul E. McKenney --- Documentation/RCU/stallwarn.rst | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/Documentation/RCU/stallwarn.rst b/Documentation/RCU/stallwarn.rst index 08bc9ae..c9ab6af 100644 --- a/Documentation/RCU/stallwarn.rst +++ b/Documentation/RCU/stallwarn.rst @@ -87,6 +87,13 @@ warnings: problem really has happened, and seems to be most likely to result in RCU CPU stall warnings for CONFIG_NO_HZ_COMMON=n kernels. +- A hardware or software issue that prevents time-based wakeups + from occurring. These issues can range from misconfigured or + buggy timer hardware through bugs in the interrupt or exception + path (whether hardware, firmware, or software) through bugs + in Linux's timer subsystem through bugs in the scheduler, and, + yes, even including bugs in RCU itself. + - A bug in the RCU implementation. - A hardware failure. This is quite unlikely, but has occurred -- 2.9.5