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 5A1B5C433E6 for ; Mon, 31 Aug 2020 18:08:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2761D2145D for ; Mon, 31 Aug 2020 18:08:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897285; bh=frSMGtcMvH8NIFdpMCUSxIIFLQvowDjR4Za2sBVsbEA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=vsytQdQ5coHzFKRZnvjrCnF+vF2mQIMG8KlRL99tZ9MIQPcfkm+olnkUd5gTYFNPy CqyRll6vLrVdc/XfwwPqMDrt/ncjRRjI7oaptZPUR7jvYMMz/vlV9eqG6rCOs8IL9z IUCCtyjWAOysfJrSm5yGzTrSdthet4pCeqC3F2qs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729377AbgHaSID (ORCPT ); Mon, 31 Aug 2020 14:08:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:55856 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729248AbgHaSH4 (ORCPT ); Mon, 31 Aug 2020 14:07:56 -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 840A521548; Mon, 31 Aug 2020 18:07:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897273; bh=frSMGtcMvH8NIFdpMCUSxIIFLQvowDjR4Za2sBVsbEA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fDZqoqZFwP0n+sLQdFEn11ekpLKvnFjm0BFaDw9OoFwLnWSKcKF4+nvzvhxl/2vSt w5kLCxGmX/nJtAR3vc8dzqhO1bO4sgjvNWoTCm0zQKFHg5llteoNK3937vUt37/UgT J1mmPr91WFrcVo5D73Iaywn85i4JVRCBPkGEEsBs= 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 09/19] scftorture: Add smp_call_function() memory-ordering checks Date: Mon, 31 Aug 2020 11:07:39 -0700 Message-Id: <20200831180749.843-9-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200831180731.GA582@paulmck-ThinkPad-P72> References: <20200831180731.GA582@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" This commit adds checks for memory misordering across calls to and returns from smp_call_function() in the case where the caller waits. Misordering results in a splat. Note that in contrast to smp_call_function_single(), this code does not test memory ordering into the handler in the no-wait case because none of the handlers would be able to free the scf_check structure without introducing heavy synchronization to work out which was last. [ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ] Signed-off-by: Paul E. McKenney --- kernel/scftorture.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) diff --git a/kernel/scftorture.c b/kernel/scftorture.c index 3519ad1..0d7299d 100644 --- a/kernel/scftorture.c +++ b/kernel/scftorture.c @@ -297,11 +297,13 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra cpus_read_lock(); else preempt_disable(); - switch (scfsp->scfs_prim) { - case SCF_PRIM_SINGLE: + if (scfsp->scfs_prim == SCF_PRIM_SINGLE || scfsp->scfs_wait) { scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC); if (WARN_ON_ONCE(!scfcp)) atomic_inc(&n_alloc_errs); + } + switch (scfsp->scfs_prim) { + case SCF_PRIM_SINGLE: cpu = torture_random(trsp) % nr_cpu_ids; if (scfsp->scfs_wait) scfp->n_single_wait++; @@ -328,11 +330,6 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra } break; case SCF_PRIM_MANY: - if (scfsp->scfs_wait) { - scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC); - if (WARN_ON_ONCE(!scfcp)) - atomic_inc(&n_alloc_errs); - } if (scfsp->scfs_wait) scfp->n_many_wait++; else @@ -356,7 +353,19 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra scfp->n_all_wait++; else scfp->n_all++; - smp_call_function(scf_handler, NULL, scfsp->scfs_wait); + if (scfcp) { + scfcp->scfc_cpu = -1; + scfcp->scfc_wait = true; + scfcp->scfc_out = false; + scfcp->scfc_in = true; + } + smp_call_function(scf_handler, scfcp, scfsp->scfs_wait); + if (scfcp) { + if (WARN_ON_ONCE(!scfcp->scfc_out)) + atomic_inc(&n_mb_out_errs); // Leak rather than trash! + else + kfree(scfcp); + } break; } if (use_cpus_read_lock) -- 2.9.5