From patchwork Fri Sep 22 08:11:37 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: tip-bot2 for Thomas Gleixner X-Patchwork-Id: 143490 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:612c:172:b0:3f2:4152:657d with SMTP id h50csp5641022vqi; Fri, 22 Sep 2023 07:56:47 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFq0OMMbFWif0T/zPKw9UbptaWFmNANlSp/rtnDWuIjMGNxT9y66Z85Syzv8IluwSNwxHTH X-Received: by 2002:a05:6a20:6a0d:b0:15d:53ad:22fe with SMTP id p13-20020a056a206a0d00b0015d53ad22femr4115433pzk.3.1695394607615; Fri, 22 Sep 2023 07:56:47 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1695394607; cv=none; d=google.com; s=arc-20160816; b=Jonlg4eTwnRyNqqaIoNiayhKFIGGcD3nTEKEZhS9C7pjEENLRHa4h1tOtU6uErY2k5 /4b9Xq42Pc0c4xm3BRq+6p8kNHyIIZRwKZFSNx6OIVwDzxmg/evx+c87oQoHPPhlKol0 6UKBYmTE27RT7OwdqcfbAo/SB7ZREGM/KR7H02GKWsRqQDG8eA3bu2+J4VPZjRaK41P4 CPkQohPGhoys3MzBPthxJ61Cxc44ensMCOVtBwWVd6Walcd3lClQZtI9fqAbekQHUECs n8+ieE8iEg9S5EBoh1qtsFPc6UFgzAyWOabcY2n1w01DeBO5mx/5s9T5sGA5GphLbW6N 0TbA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:robot-unsubscribe :robot-id:message-id:mime-version:references:in-reply-to:cc:subject :to:reply-to:sender:from:dkim-signature:dkim-signature:date; bh=FZqsvjjlEWZGBL4cgJ2JxgAJVbdahw8bEqqnuOXhUxc=; fh=IECvZ5LDG1eNYiY0ZEkdAtu3yKdGBaMOXeHl+ptZ6Xg=; b=deqNnJGYlixYM297ZTndAt65H7t2629Qe0GsGJckckkSxF5lweU4/dUV/3zOVgBOwv Ej202kfLXL3KmH85uPG2GCaRK+r0t4J3esEmApTWrjhSIl0o2BXF7IaHzAE91g8ppnQk 9x8oe+L8ylKm3bdP5kWgFXyjtO1ya8u+QqHt/gIBxPAIiL8/fb/Q+3YwEWDuqveUFEIL /UgubzNRbzmkA/PyOwe+VvvSqxw+XW/u06/Ryj47Ub468OpsnNqOHc6HoKaulIBAbHNt wTSABy4FK6ZaFdpqZ1S9Bn6B8lG8kNkxt6sFiu6RQLWEmRpEsEEJCLPvajPl55h814Xx pqlw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linutronix.de header.s=2020 header.b=tb+Qqq9J; dkim=neutral (no key) header.i=@linutronix.de; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:6 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=linutronix.de Received: from pete.vger.email (pete.vger.email. [2620:137:e000::3:6]) by mx.google.com with ESMTPS id bx22-20020a056a02051600b00569da5e2e5esi4446605pgb.255.2023.09.22.07.56.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Sep 2023 07:56:47 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:6 as permitted sender) client-ip=2620:137:e000::3:6; Authentication-Results: mx.google.com; dkim=pass header.i=@linutronix.de header.s=2020 header.b=tb+Qqq9J; dkim=neutral (no key) header.i=@linutronix.de; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:6 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=linutronix.de Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by pete.vger.email (Postfix) with ESMTP id 42366835A6A5; Fri, 22 Sep 2023 01:12:43 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at pete.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232051AbjIVIMS (ORCPT + 30 others); Fri, 22 Sep 2023 04:12:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50938 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232482AbjIVILq (ORCPT ); Fri, 22 Sep 2023 04:11:46 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CA46BE4B; Fri, 22 Sep 2023 01:11:39 -0700 (PDT) Date: Fri, 22 Sep 2023 08:11:37 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1695370298; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=FZqsvjjlEWZGBL4cgJ2JxgAJVbdahw8bEqqnuOXhUxc=; b=tb+Qqq9JnLV863K0PuaWNgk7/nrLIQ4fTVxh8YzJOTAKznP4a+nfPHWz43NGLlnaCUhrjW zgsoyiSBlVDmKgJXmtYlOr5P/OdVDAfJYtmh5v+ng9lf5NqnDYcp4to79yloGraKqczZkg dMYLirHQn6cnDnrtqE6yI917N+7+lRnHljfCyFhu3OaLzap19r0MbO7XaHo7HkJT4L5v+p KJKSZ6AAJcMh3W2V3+JsmfgmcfO/YmUXdx6sCS3Vbjh0nXHJR0lWJ25Wt7aew95Lh1qcBP 5WI8YcDBqGikRvlUao3iwgyT7KqLmkpGe4cBTlzeBfEixcNoHiGwK0zcsIpGSQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1695370298; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=FZqsvjjlEWZGBL4cgJ2JxgAJVbdahw8bEqqnuOXhUxc=; b=hSUvho8pyGAJcA9ZiZns7v977eVto5De55HjK5ate/H+iZQ5khb/xso39TEdNZ4EGtkFq1 02EGbC28jJfgz4DQ== From: "tip-bot2 for John Stultz" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/core] locking/ww_mutex/test: Fix potential workqueue corruption Cc: John Stultz , Ingo Molnar , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20230922043616.19282-3-jstultz@google.com> References: <20230922043616.19282-3-jstultz@google.com> MIME-Version: 1.0 Message-ID: <169537029753.27769.15529645927257680234.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on pete.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (pete.vger.email [0.0.0.0]); Fri, 22 Sep 2023 01:12:44 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1777750095867474916 X-GMAIL-MSGID: 1777750095867474916 The following commit has been merged into the locking/core branch of tip: Commit-ID: bccdd808902f8c677317cec47c306e42b93b849e Gitweb: https://git.kernel.org/tip/bccdd808902f8c677317cec47c306e42b93b849e Author: John Stultz AuthorDate: Fri, 22 Sep 2023 04:36:00 Committer: Ingo Molnar CommitterDate: Fri, 22 Sep 2023 09:43:40 +02:00 locking/ww_mutex/test: Fix potential workqueue corruption In some cases running with the test-ww_mutex code, I was seeing odd behavior where sometimes it seemed flush_workqueue was returning before all the work threads were finished. Often this would cause strange crashes as the mutexes would be freed while they were being used. Looking at the code, there is a lifetime problem as the controlling thread that spawns the work allocates the "struct stress" structures that are passed to the workqueue threads. Then when the workqueue threads are finished, they free the stress struct that was passed to them. Unfortunately the workqueue work_struct node is in the stress struct. Which means the work_struct is freed before the work thread returns and while flush_workqueue is waiting. It seems like a better idea to have the controlling thread both allocate and free the stress structures, so that we can be sure we don't corrupt the workqueue by freeing the structure prematurely. So this patch reworks the test to do so, and with this change I no longer see the early flush_workqueue returns. Signed-off-by: John Stultz Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230922043616.19282-3-jstultz@google.com --- kernel/locking/test-ww_mutex.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/kernel/locking/test-ww_mutex.c b/kernel/locking/test-ww_mutex.c index 9bceba6..358d661 100644 --- a/kernel/locking/test-ww_mutex.c +++ b/kernel/locking/test-ww_mutex.c @@ -479,7 +479,6 @@ retry: } while (!time_after(jiffies, stress->timeout)); kfree(order); - kfree(stress); } struct reorder_lock { @@ -544,7 +543,6 @@ out: list_for_each_entry_safe(ll, ln, &locks, link) kfree(ll); kfree(order); - kfree(stress); } static void stress_one_work(struct work_struct *work) @@ -565,8 +563,6 @@ static void stress_one_work(struct work_struct *work) break; } } while (!time_after(jiffies, stress->timeout)); - - kfree(stress); } #define STRESS_INORDER BIT(0) @@ -577,15 +573,24 @@ static void stress_one_work(struct work_struct *work) static int stress(int nlocks, int nthreads, unsigned int flags) { struct ww_mutex *locks; - int n; + struct stress *stress_array; + int n, count; locks = kmalloc_array(nlocks, sizeof(*locks), GFP_KERNEL); if (!locks) return -ENOMEM; + stress_array = kmalloc_array(nthreads, sizeof(*stress_array), + GFP_KERNEL); + if (!stress_array) { + kfree(locks); + return -ENOMEM; + } + for (n = 0; n < nlocks; n++) ww_mutex_init(&locks[n], &ww_class); + count = 0; for (n = 0; nthreads; n++) { struct stress *stress; void (*fn)(struct work_struct *work); @@ -609,9 +614,7 @@ static int stress(int nlocks, int nthreads, unsigned int flags) if (!fn) continue; - stress = kmalloc(sizeof(*stress), GFP_KERNEL); - if (!stress) - break; + stress = &stress_array[count++]; INIT_WORK(&stress->work, fn); stress->locks = locks; @@ -626,6 +629,7 @@ static int stress(int nlocks, int nthreads, unsigned int flags) for (n = 0; n < nlocks; n++) ww_mutex_destroy(&locks[n]); + kfree(stress_array); kfree(locks); return 0; From patchwork Fri Sep 22 04:36:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Stultz X-Patchwork-Id: 143672 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:612c:172:b0:3f2:4152:657d with SMTP id h50csp5877635vqi; Fri, 22 Sep 2023 14:33:04 -0700 (PDT) X-Google-Smtp-Source: AGHT+IG6AWMoIICkY5BHRR30+H3agdkXNVS0T57xl//loT/OodXlPukmglN7Kiy7yVBf24hJ557Z X-Received: by 2002:a17:90a:d354:b0:273:f584:40ca with SMTP id i20-20020a17090ad35400b00273f58440camr915001pjx.16.1695418384131; Fri, 22 Sep 2023 14:33:04 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1695418384; cv=none; d=google.com; s=arc-20160816; b=DRPiX90PiOeEWC39SKK3Fe9OzEGfoz2GsU5QAwrWvmqETkA5MXaKF+9rh+1HZtRxzA XAS9ekyf4WMv4Ai1OZutrrNFpL0ACqQpF/vwyUB7FFJvmD/v7rDljZrC57jTqd+O+Zh7 7w5ZHOZWK84X1IaHPaidYFqeESJtEIoc6Z2sDKAcfy3zRD7/pIj6iLSsDpd9ZJFlopEg rwzP5hCi3MO0rLrbZOUk9MQ0FWGqqAzKxGn7YYQIMqEprPuna2gzwDNKe9Im5Lj01kIB egg86q/4WX9IpwrsL4+f52jYKf8sFeCRA/7oeqgDFf2T74qXtkQjlqnKQbsEOytiPazm CWCQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:dkim-signature; bh=FFCV0sch6yU/8LYuNDFjRf1SrTydnK4Yn1LXrMsCSk4=; fh=R8ns9WTVSoDBVhMO36SKdGHl9xjhJWDQEUfYP61UUR4=; b=e3/s8jU99BqzeDZyBPSdQCDPKhtZVX4Am1xowH5vgstBVCEhJwOsjWUEMhBM3rlLrH SsgCLP8W4vju4ab5eUWp0wlIXGcoP4KtFWcj5aN6YvIbJgbFtOa0MnghpbcVnsGbAweM ZfAnCUL61+odiL9K0MsMYRQPf9cf9W4WiQmg4depJWDFrrJfTOg6MBe4Yh+enHr1YFsM 9P0GHYtcWusacFGxCmnUcw7EeV/2LTF+tBYpMY7lFjVx9pyVgbnCUL8B6RWhC26QjGAN /oqqe/H82Zmz7zh7G9F/umoAw+oXw8yMabCQPfHpbQ5S21Io99I19GoiYk21zLUzbjkR +cPA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20230601 header.b=yXERfMhY; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.34 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from howler.vger.email (howler.vger.email. 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McKenney" , Joel Fernandes , Dietmar Eggemann , kernel-team@android.com X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (howler.vger.email [0.0.0.0]); Thu, 21 Sep 2023 21:36:48 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1777775027790675241 X-GMAIL-MSGID: 1777775027790675241 In some cases running with the test-ww_mutex code, I was seeing odd behavior where sometimes it seemed flush_workqueue was returning before all the work threads were finished. Often this would cause strange crashes as the mutexes would be freed while they were being used. Looking at the code, there is a lifetime problem as the controlling thread that spawns the work allocates the "struct stress" structures that are passed to the workqueue threads. Then when the workqueue threads are finished, they free the stress struct that was passed to them. Unfortunately the workqueue work_struct node is in the stress struct. Which means the work_struct is freed before the work thread returns and while flush_workqueue is waiting. It seems like a better idea to have the controlling thread both allocate and free the stress structures, so that we can be sure we don't corrupt the workqueue by freeing the structure prematurely. So this patch reworks the test to do so, and with this change I no longer see the early flush_workqueue returns. Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Will Deacon Cc: Waiman Long Cc: Boqun Feng Cc: "Paul E . McKenney" Cc: Joel Fernandes Cc: Dietmar Eggemann Cc: kernel-team@android.com Signed-off-by: John Stultz --- kernel/locking/test-ww_mutex.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/kernel/locking/test-ww_mutex.c b/kernel/locking/test-ww_mutex.c index 9bceba65858a..358d66150426 100644 --- a/kernel/locking/test-ww_mutex.c +++ b/kernel/locking/test-ww_mutex.c @@ -479,7 +479,6 @@ static void stress_inorder_work(struct work_struct *work) } while (!time_after(jiffies, stress->timeout)); kfree(order); - kfree(stress); } struct reorder_lock { @@ -544,7 +543,6 @@ static void stress_reorder_work(struct work_struct *work) list_for_each_entry_safe(ll, ln, &locks, link) kfree(ll); kfree(order); - kfree(stress); } static void stress_one_work(struct work_struct *work) @@ -565,8 +563,6 @@ static void stress_one_work(struct work_struct *work) break; } } while (!time_after(jiffies, stress->timeout)); - - kfree(stress); } #define STRESS_INORDER BIT(0) @@ -577,15 +573,24 @@ static void stress_one_work(struct work_struct *work) static int stress(int nlocks, int nthreads, unsigned int flags) { struct ww_mutex *locks; - int n; + struct stress *stress_array; + int n, count; locks = kmalloc_array(nlocks, sizeof(*locks), GFP_KERNEL); if (!locks) return -ENOMEM; + stress_array = kmalloc_array(nthreads, sizeof(*stress_array), + GFP_KERNEL); + if (!stress_array) { + kfree(locks); + return -ENOMEM; + } + for (n = 0; n < nlocks; n++) ww_mutex_init(&locks[n], &ww_class); + count = 0; for (n = 0; nthreads; n++) { struct stress *stress; void (*fn)(struct work_struct *work); @@ -609,9 +614,7 @@ static int stress(int nlocks, int nthreads, unsigned int flags) if (!fn) continue; - stress = kmalloc(sizeof(*stress), GFP_KERNEL); - if (!stress) - break; + stress = &stress_array[count++]; INIT_WORK(&stress->work, fn); stress->locks = locks; @@ -626,6 +629,7 @@ static int stress(int nlocks, int nthreads, unsigned int flags) for (n = 0; n < nlocks; n++) ww_mutex_destroy(&locks[n]); + kfree(stress_array); kfree(locks); return 0;