Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758335AbcJ1KKq (ORCPT ); Fri, 28 Oct 2016 06:10:46 -0400 Received: from terminus.zytor.com ([198.137.202.10]:52892 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752497AbcJ1KKp (ORCPT ); Fri, 28 Oct 2016 06:10:45 -0400 Date: Fri, 28 Oct 2016 03:10:03 -0700 From: tip-bot for Jiri Olsa Message-ID: Cc: peterz@infradead.org, mingo@kernel.org, jolsa@redhat.com, kan.liang@intel.com, caiqian@redhat.com, gregkh@linuxfoundation.org, tglx@linutronix.de, robh@kernel.org, torvalds@linux-foundation.org, alexander.shishkin@linux.intel.com, acme@redhat.com, linux-kernel@vger.kernel.org, jolsa@kernel.org, hpa@zytor.com Reply-To: jolsa@redhat.com, mingo@kernel.org, peterz@infradead.org, gregkh@linuxfoundation.org, caiqian@redhat.com, kan.liang@intel.com, acme@redhat.com, torvalds@linux-foundation.org, alexander.shishkin@linux.intel.com, tglx@linutronix.de, robh@kernel.org, hpa@zytor.com, jolsa@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20161020111011.GA13361@krava> References: <20161020111011.GA13361@krava> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] perf/core: Protect PMU device removal with a 'pmu_bus_running' check, to fix CONFIG_DEBUG_TEST_DRIVER_REMOVE=y kernel panic Git-Commit-ID: 0933840acf7b65d6d30a5b6089d882afea57aca3 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2741 Lines: 74 Commit-ID: 0933840acf7b65d6d30a5b6089d882afea57aca3 Gitweb: http://git.kernel.org/tip/0933840acf7b65d6d30a5b6089d882afea57aca3 Author: Jiri Olsa AuthorDate: Thu, 20 Oct 2016 13:10:11 +0200 Committer: Ingo Molnar CommitDate: Fri, 28 Oct 2016 11:06:25 +0200 perf/core: Protect PMU device removal with a 'pmu_bus_running' check, to fix CONFIG_DEBUG_TEST_DRIVER_REMOVE=y kernel panic CAI Qian reported a crash in the PMU uncore device removal code, enabled by the CONFIG_DEBUG_TEST_DRIVER_REMOVE=y option: https://marc.info/?l=linux-kernel&m=147688837328451 The reason for the crash is that perf_pmu_unregister() tries to remove a PMU device which is not added at this point. We add PMU devices only after pmu_bus is registered, which happens in the perf_event_sysfs_init() call and sets the 'pmu_bus_running' flag. The fix is to get the 'pmu_bus_running' flag state at the point the PMU is taken out of the PMU list and remove the device later only if it's set. Reported-by: CAI Qian Tested-by: CAI Qian Signed-off-by: Jiri Olsa Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Greg Kroah-Hartman Cc: Jiri Olsa Cc: Kan Liang Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Rob Herring Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20161020111011.GA13361@krava Signed-off-by: Ingo Molnar --- kernel/events/core.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index c6e47e9..a5d2e62 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8855,7 +8855,10 @@ EXPORT_SYMBOL_GPL(perf_pmu_register); void perf_pmu_unregister(struct pmu *pmu) { + int remove_device; + mutex_lock(&pmus_lock); + remove_device = pmu_bus_running; list_del_rcu(&pmu->entry); mutex_unlock(&pmus_lock); @@ -8869,10 +8872,12 @@ void perf_pmu_unregister(struct pmu *pmu) free_percpu(pmu->pmu_disable_count); if (pmu->type >= PERF_TYPE_MAX) idr_remove(&pmu_idr, pmu->type); - if (pmu->nr_addr_filters) - device_remove_file(pmu->dev, &dev_attr_nr_addr_filters); - device_del(pmu->dev); - put_device(pmu->dev); + if (remove_device) { + if (pmu->nr_addr_filters) + device_remove_file(pmu->dev, &dev_attr_nr_addr_filters); + device_del(pmu->dev); + put_device(pmu->dev); + } free_pmu_context(pmu); } EXPORT_SYMBOL_GPL(perf_pmu_unregister);