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Tue, 19 May 2026 05:42:00 +0000 Message-ID: <9d9788f8-77d4-450a-98f3-a0eee4c61f77@intel.com> Date: Tue, 19 May 2026 13:41:45 +0800 User-Agent: Mozilla Thunderbird Subject: Re: [Patch v4 12/16] sched/cache: Fix race condition during sched domain rebuild To: Peter Zijlstra , Tim Chen CC: Ingo Molnar , K Prateek Nayak , Vincent Guittot , Juri Lelli , Dietmar Eggemann , "Steven Rostedt" , Ben Segall , Mel Gorman , Valentin Schneider , "Madadi Vineeth Reddy" , Hillf Danton , "Shrikanth Hegde" , Jianyong Wu , "Yangyu Chen" , Tingyin Duan , Vern Hao , Vern Hao , Len Brown , Aubrey Li , Zhao Liu , Chen Yu , Adam Li , Aaron Lu , Tim Chen , Josh Don , Gavin Guo , Qais Yousef , Libo Chen , Luo Gengkun , References: <9afddf439687f04bb56b46625bd9f153eb8abad5.1778703694.git.tim.c.chen@linux.intel.com> <20260518143446.GV3102624@noisy.programming.kicks-ass.net> Content-Language: en-US From: "Chen, Yu C" In-Reply-To: <20260518143446.GV3102624@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset="UTF-8"; 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One case is that the _sched_cache_active_set() might be called via sched_init_smp() -> sched_init_domains() -> build_sched_domains() where only sched_domains_mutex was hold. But since it is during boot up thus system_state < SYSTEM_RUNNING and lockdep_assert_cpus_held() will not trigger the assert. thanks, Chenyu > --- a/kernel/sched/topology.c > +++ b/kernel/sched/topology.c > @@ -920,11 +920,12 @@ static bool alloc_sd_llc(const struct cp > /* > * Enable/disable cache aware scheduling according to > * user input and the presence of hardware support. > - * Expected to be protected by cpus_read_lock() and > - * sched_domains_mutex_lock() > */ > static void _sched_cache_active_set(void) > { > + lockdep_assert_cpus_held(); > + lockdep_assert_held(&sched_domains_mutex); > + > /* hardware does not support */ > if (!static_branch_likely(&sched_cache_present)) { > static_branch_disable_cpuslocked(&sched_cache_active);