From: Viresh Kumar <viresh.kumar@linaro.org> mainline inclusion from mainline-v7.0-rc6 commit 6a28fb8cb28b9eb39a392e531d938a889eacafc5 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/8993 CVE: NA Reference: https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commi... ---------------------------------------------------------------------- A recently reported issue highlighted that the cached requested_freq is not guaranteed to stay in sync with policy->cur. If the platform changes the actual CPU frequency after the governor sets one (e.g. due to platform-specific frequency scaling) and a re-sync occurs later, policy->cur may diverge from requested_freq. This can lead to incorrect behavior in the conservative governor. For example, the governor may assume the CPU is already running at the maximum frequency and skip further increases even though there is still headroom. Avoid this by resetting the cached requested_freq to policy->cur on detecting a change in policy limits. Reported-by: Lifeng Zheng <zhenglifeng1@huawei.com> Tested-by: Lifeng Zheng <zhenglifeng1@huawei.com> Link: https://lore.kernel.org/all/20260210115458.3493646-1-zhenglifeng1@huawei.com... Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com> Cc: All applicable <stable@vger.kernel.org> Link: https://patch.msgid.link/d846a141a98ac0482f20560fcd7525c0f0ec2f30.1773999467... Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Lifeng Zheng <zhenglifeng1@huawei.com> Signed-off-by: Hongye Lin <linhongye@h-partners.com> --- drivers/cpufreq/cpufreq_conservative.c | 12 ++++++++++++ drivers/cpufreq/cpufreq_governor.c | 3 +++ drivers/cpufreq/cpufreq_governor.h | 1 + 3 files changed, 16 insertions(+) diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c index b6bd0ff35323..efdcc4ab4334 100644 --- a/drivers/cpufreq/cpufreq_conservative.c +++ b/drivers/cpufreq/cpufreq_conservative.c @@ -314,6 +314,17 @@ static void cs_start(struct cpufreq_policy *policy) dbs_info->requested_freq = policy->cur; } +static void cs_limits(struct cpufreq_policy *policy) +{ + struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data); + + /* + * The limits have changed, so may have the current frequency. Reset + * requested_freq to avoid any unintended outcomes due to the mismatch. + */ + dbs_info->requested_freq = policy->cur; +} + static struct dbs_governor cs_governor = { .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"), .kobj_type = { .default_groups = cs_groups }, @@ -323,6 +334,7 @@ static struct dbs_governor cs_governor = { .init = cs_init, .exit = cs_exit, .start = cs_start, + .limits = cs_limits, }; #define CPU_FREQ_GOV_CONSERVATIVE (cs_governor.gov) diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c index 1a7fcaf39cc9..8f5474612b31 100644 --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -563,6 +563,7 @@ EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_stop); void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy) { + struct dbs_governor *gov = dbs_governor_of(policy); struct policy_dbs_info *policy_dbs; /* Protect gov->gdbs_data against cpufreq_dbs_governor_exit() */ @@ -574,6 +575,8 @@ void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy) mutex_lock(&policy_dbs->update_mutex); cpufreq_policy_apply_limits(policy); gov_update_sample_delay(policy_dbs, 0); + if (gov->limits) + gov->limits(policy); mutex_unlock(&policy_dbs->update_mutex); out: diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h index 168c23fd7fca..1462d59277bd 100644 --- a/drivers/cpufreq/cpufreq_governor.h +++ b/drivers/cpufreq/cpufreq_governor.h @@ -138,6 +138,7 @@ struct dbs_governor { int (*init)(struct dbs_data *dbs_data); void (*exit)(struct dbs_data *dbs_data); void (*start)(struct cpufreq_policy *policy); + void (*limits)(struct cpufreq_policy *policy); }; static inline struct dbs_governor *dbs_governor_of(struct cpufreq_policy *policy) -- 2.33.0