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 66F5AC433E2 for ; Mon, 31 Aug 2020 18:09:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47F322083E for ; Mon, 31 Aug 2020 18:09:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897367; bh=4XdryG1RiS9pScSJTZHEAUnlZQ1xRBaxkunLznXSh3k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=GS6iTcSTNatIYO6HDTyq5kqKigm5mGv/96ndXNuHvAygVaI4pLg1abPTsaP6TcMJm eCo/sJMgKHEG+EIOMzYVGC/7xEmvCGlOLnGFUqgyylxMsmPGAee/+/zKqI+rYZ552T tMp5BBox70xW4mB3wW7BITAK43GgiymPqeCO9lpM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729538AbgHaSJY (ORCPT ); Mon, 31 Aug 2020 14:09:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:55484 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729215AbgHaSHy (ORCPT ); Mon, 31 Aug 2020 14:07:54 -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 1EF3421582; 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=4XdryG1RiS9pScSJTZHEAUnlZQ1xRBaxkunLznXSh3k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fJaMfqeU/GjtBbGqlL6h5tZeBfk4frMJyYuK35tMvGizmlN6qs+aiF6wKSefTtf07 YchP8MbeLxv3mnXudWEveZ27BBPjFK+RtuU2z7Vvl5iSGYf2fFYCXsMEUT3yq+J+yz YOCmd7q3QPBAUrVih5Jd3j+RZn57mtiMjY6f03Hg= 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 07/19] scftorture: Add smp_call_function_single() memory-ordering checks Date: Mon, 31 Aug 2020 11:07:37 -0700 Message-Id: <20200831180749.843-7-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 smp_call_function_single() and also across returns in the case where the caller waits. Misordering results in a splat. [ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ] Signed-off-by: Paul E. McKenney --- kernel/scftorture.c | 56 +++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 48 insertions(+), 8 deletions(-) diff --git a/kernel/scftorture.c b/kernel/scftorture.c index 09a6242..9b42271 100644 --- a/kernel/scftorture.c +++ b/kernel/scftorture.c @@ -117,9 +117,20 @@ static struct scf_selector scf_sel_array[SCF_NPRIMS]; static int scf_sel_array_len; static unsigned long scf_sel_totweight; +// Communicate between caller and handler. +struct scf_check { + bool scfc_in; + bool scfc_out; + int scfc_cpu; // -1 for not _single(). + bool scfc_wait; +}; + // Use to wait for all threads to start. static atomic_t n_started; static atomic_t n_errs; +static atomic_t n_mb_in_errs; +static atomic_t n_mb_out_errs; +static atomic_t n_alloc_errs; static bool scfdone; DEFINE_TORTURE_RANDOM_PERCPU(scf_torture_rand); @@ -222,24 +233,27 @@ static struct scf_selector *scf_sel_rand(struct torture_random_state *trsp) // Update statistics and occasionally burn up mass quantities of CPU time, // if told to do so via scftorture.longwait. Otherwise, occasionally burn // a little bit. -static void scf_handler(void *unused) +static void scf_handler(void *scfc_in) { int i; int j; unsigned long r = torture_random(this_cpu_ptr(&scf_torture_rand)); + struct scf_check *scfcp = scfc_in; + if (likely(scfcp) && WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in)))) + atomic_inc(&n_mb_in_errs); this_cpu_inc(scf_invoked_count); if (longwait <= 0) { if (!(r & 0xffc0)) udelay(r & 0x3f); - return; + goto out; } if (r & 0xfff) - return; + goto out; r = (r >> 12); if (longwait <= 0) { udelay((r & 0xff) + 1); - return; + goto out; } r = r % longwait + 1; for (i = 0; i < r; i++) { @@ -248,14 +262,24 @@ static void scf_handler(void *unused) cpu_relax(); } } +out: + if (unlikely(!scfcp)) + return; + if (scfcp->scfc_wait) + WRITE_ONCE(scfcp->scfc_out, true); + else + kfree(scfcp); } // As above, but check for correct CPU. -static void scf_handler_1(void *me) +static void scf_handler_1(void *scfc_in) { - if (WARN_ON_ONCE(smp_processor_id() != (uintptr_t)me)) + struct scf_check *scfcp = scfc_in; + + if (likely(scfcp) && WARN_ONCE(smp_processor_id() != scfcp->scfc_cpu, "%s: Wanted CPU %d got CPU %d\n", __func__, scfcp->scfc_cpu, smp_processor_id())) { atomic_inc(&n_errs); - scf_handler(NULL); + } + scf_handler(scfcp); } // Randomly do an smp_call_function*() invocation. @@ -263,6 +287,7 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra { uintptr_t cpu; int ret; + struct scf_check *scfcp = NULL; struct scf_selector *scfsp = scf_sel_rand(trsp); if (use_cpus_read_lock) @@ -271,17 +296,32 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra preempt_disable(); switch (scfsp->scfs_prim) { case SCF_PRIM_SINGLE: + scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC); + if (WARN_ON_ONCE(!scfcp)) + atomic_inc(&n_alloc_errs); cpu = torture_random(trsp) % nr_cpu_ids; if (scfsp->scfs_wait) scfp->n_single_wait++; else scfp->n_single++; - ret = smp_call_function_single(cpu, scf_handler_1, (void *)cpu, scfsp->scfs_wait); + if (scfcp) { + scfcp->scfc_cpu = cpu; + scfcp->scfc_wait = scfsp->scfs_wait; + scfcp->scfc_out = false; + scfcp->scfc_in = true; + } + ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, scfsp->scfs_wait); if (ret) { if (scfsp->scfs_wait) scfp->n_single_wait_ofl++; else scfp->n_single_ofl++; + kfree(scfcp); + } else if (scfcp && scfsp->scfs_wait) { + if (WARN_ON_ONCE(!scfcp->scfc_out)) + atomic_inc(&n_mb_out_errs); // Leak rather than trash! + else + kfree(scfcp); } break; case SCF_PRIM_MANY: -- 2.9.5