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=-13.1 required=3.0 tests=BAYES_00,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=unavailable 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 448F4C433E2 for ; Mon, 31 Aug 2020 18:04:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 135F920EDD for ; Mon, 31 Aug 2020 18:04:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897085; bh=+eMk/MFGdcAHBuSZ4HbjsCXhiKaiNkxWmakPUc86lpI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=vXoYHgMz91rJPerzFqi8YtUJmJfYoVpOQPiP/0ZI/okbZduRTtsU56Dy+fkcRYKDY SIhM6YrRgYdVR6KrBIAhcRUnu+kZUtdo5yqb6NrGAb6Is0fuxA80WiGC/o6cf6B4Ik VE6AmoTaoVnYVhcEoIHnsH6ULfNoviDckrtYPtGk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729445AbgHaSEn (ORCPT ); Mon, 31 Aug 2020 14:04:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:44514 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728936AbgHaSEL (ORCPT ); Mon, 31 Aug 2020 14:04:11 -0400 Received: from paulmck-ThinkPad-P72.home (unknown [50.45.173.55]) (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 210D5216C4; Mon, 31 Aug 2020 18:04:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897051; bh=+eMk/MFGdcAHBuSZ4HbjsCXhiKaiNkxWmakPUc86lpI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h6KHWOWK60n4MYSUaAE5zsWz+HwSh9IUy2j6f++YHkDJd3tTunH6Z3T13JoZUVvGL 6LwwGKL2iERMhBO1YduptPYQAgmxFwBbRXB0wb29+ArxqkE1t8/joQfbgVp1xMYIhm 3AmNdZJr+pMKYk7j/51aQIl+bOaIYUtafWbzE8PE= 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 10/14] rcutorture: Properly synchronize with OOM notifier Date: Mon, 31 Aug 2020 11:04:02 -0700 Message-Id: <20200831180406.494-10-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200831180348.GA416@paulmck-ThinkPad-P72> References: <20200831180348.GA416@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" The current rcutorture forward-progress code assumes that it is the only cause of out-of-memory (OOM) events. For script-based rcutorture testing, this assumption is in fact correct. However, testing based on modprobe/rmmod might well encounter external OOM events, which could happen at any time. This commit therefore properly synchronizes the interaction between rcutorture's forward-progress testing and its OOM notifier by adding a global mutex. Signed-off-by: Paul E. McKenney --- kernel/rcu/rcutorture.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 7942be4..2b3f04e 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -1796,6 +1796,7 @@ struct rcu_fwd { unsigned long rcu_launder_gp_seq_start; }; +static DEFINE_MUTEX(rcu_fwd_mutex); static struct rcu_fwd *rcu_fwds; static bool rcu_fwd_emergency_stop; @@ -2062,8 +2063,14 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp) static int rcutorture_oom_notify(struct notifier_block *self, unsigned long notused, void *nfreed) { - struct rcu_fwd *rfp = rcu_fwds; + struct rcu_fwd *rfp; + mutex_lock(&rcu_fwd_mutex); + rfp = rcu_fwds; + if (!rfp) { + mutex_unlock(&rcu_fwd_mutex); + return NOTIFY_OK; + } WARN(1, "%s invoked upon OOM during forward-progress testing.\n", __func__); rcu_torture_fwd_cb_hist(rfp); @@ -2081,6 +2088,7 @@ static int rcutorture_oom_notify(struct notifier_block *self, smp_mb(); /* Frees before return to avoid redoing OOM. */ (*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */ pr_info("%s returning after OOM processing.\n", __func__); + mutex_unlock(&rcu_fwd_mutex); return NOTIFY_OK; } @@ -2148,7 +2156,9 @@ static int __init rcu_torture_fwd_prog_init(void) return -ENOMEM; spin_lock_init(&rfp->rcu_fwd_lock); rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head; + mutex_lock(&rcu_fwd_mutex); rcu_fwds = rfp; + mutex_unlock(&rcu_fwd_mutex); return torture_create_kthread(rcu_torture_fwd_prog, rfp, fwd_prog_task); } @@ -2158,7 +2168,9 @@ static void rcu_torture_fwd_prog_cleanup(void) torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task); rfp = rcu_fwds; + mutex_lock(&rcu_fwd_mutex); rcu_fwds = NULL; + mutex_unlock(&rcu_fwd_mutex); kfree(rfp); } -- 2.9.5