The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 2a3eb51e30b9ac66fe1b75877627a7e4aaeca24a Mon Sep 17 00:00:00 2001
From: Henry Willard henry.willard@oracle.com Date: Tue, 14 Aug 2018 17:01:02 -0700 Subject: [PATCH] cpufreq: governor: Avoid accessing invalid governor_data
If cppc_cpufreq.ko is deleted at the same time that tuned-adm is changing profiles, there is a small chance that a race can occur between cpufreq_dbs_governor_exit() and cpufreq_dbs_governor_limits() resulting in a system failure when the latter tries to use policy->governor_data that has been freed by the former.
This patch uses gov_dbs_data_mutex to synchronize access.
Fixes: e788892ba3cc (cpufreq: governor: Get rid of governor events) Signed-off-by: Henry Willard henry.willard@oracle.com [ rjw: Subject, minor white space adjustment ] Cc: 4.8+ stable@vger.kernel.org # 4.8+ Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c index 1d50e97d49f1..6d53f7d9fc7a 100644 --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -555,12 +555,20 @@ EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_stop);
void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy) { - struct policy_dbs_info *policy_dbs = policy->governor_data; + struct policy_dbs_info *policy_dbs; + + /* Protect gov->gdbs_data against cpufreq_dbs_governor_exit() */ + mutex_lock(&gov_dbs_data_mutex); + policy_dbs = policy->governor_data; + if (!policy_dbs) + goto out;
mutex_lock(&policy_dbs->update_mutex); cpufreq_policy_apply_limits(policy); gov_update_sample_delay(policy_dbs, 0); - mutex_unlock(&policy_dbs->update_mutex); + +out: + mutex_unlock(&gov_dbs_data_mutex); } EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_limits);