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Revert "cpuset: Make cpuset hotplug synchronous"
This reverts commit a49e4629b5
("cpuset: Make cpuset hotplug synchronous") as
it may deadlock with cpu hotplug path.
Link: http://lkml.kernel.org/r/F0388D99-84D7-453B-9B6B-EEFF0E7BE4CC@lca.pw
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Qian Cai <cai@lca.pw>
Cc: Prateek Sood <prsood@codeaurora.org>
This commit is contained in:
parent
38aca3071c
commit
2b729fe7f3
3 changed files with 19 additions and 21 deletions
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@ -54,6 +54,7 @@ extern int cpuset_init(void);
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extern void cpuset_init_smp(void);
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extern void cpuset_force_rebuild(void);
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extern void cpuset_update_active_cpus(void);
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extern void cpuset_wait_for_hotplug(void);
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extern void cpuset_read_lock(void);
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extern void cpuset_read_unlock(void);
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extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
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@ -175,6 +176,8 @@ static inline void cpuset_update_active_cpus(void)
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partition_sched_domains(1, NULL, NULL);
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}
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static inline void cpuset_wait_for_hotplug(void) { }
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static inline void cpuset_read_lock(void) { }
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static inline void cpuset_read_unlock(void) { }
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@ -3101,7 +3101,7 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp)
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}
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/**
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* cpuset_hotplug - handle CPU/memory hotunplug for a cpuset
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* cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
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*
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* This function is called after either CPU or memory configuration has
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* changed and updates cpuset accordingly. The top_cpuset is always
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@ -3116,7 +3116,7 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp)
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* Note that CPU offlining during suspend is ignored. We don't modify
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* cpusets across suspend/resume cycles at all.
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*/
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static void cpuset_hotplug(bool use_cpu_hp_lock)
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static void cpuset_hotplug_workfn(struct work_struct *work)
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{
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static cpumask_t new_cpus;
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static nodemask_t new_mems;
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@ -3201,32 +3201,25 @@ static void cpuset_hotplug(bool use_cpu_hp_lock)
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/* rebuild sched domains if cpus_allowed has changed */
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if (cpus_updated || force_rebuild) {
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force_rebuild = false;
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if (use_cpu_hp_lock)
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rebuild_sched_domains();
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else {
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/* Acquiring cpu_hotplug_lock is not required.
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* When cpuset_hotplug() is called in hotplug path,
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* cpu_hotplug_lock is held by the hotplug context
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* which is waiting for cpuhp_thread_fun to indicate
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* completion of callback.
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*/
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percpu_down_write(&cpuset_rwsem);
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rebuild_sched_domains_locked();
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percpu_up_write(&cpuset_rwsem);
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}
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rebuild_sched_domains();
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}
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free_cpumasks(NULL, ptmp);
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}
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static void cpuset_hotplug_workfn(struct work_struct *work)
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{
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cpuset_hotplug(true);
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}
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void cpuset_update_active_cpus(void)
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{
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cpuset_hotplug(false);
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/*
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* We're inside cpu hotplug critical region which usually nests
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* inside cgroup synchronization. Bounce actual hotplug processing
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* to a work item to avoid reverse locking order.
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*/
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schedule_work(&cpuset_hotplug_work);
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}
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void cpuset_wait_for_hotplug(void)
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{
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flush_work(&cpuset_hotplug_work);
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}
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/*
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@ -204,6 +204,8 @@ void thaw_processes(void)
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__usermodehelper_set_disable_depth(UMH_FREEZING);
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thaw_workqueues();
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cpuset_wait_for_hotplug();
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read_lock(&tasklist_lock);
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for_each_process_thread(g, p) {
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/* No other threads should have PF_SUSPEND_TASK set */
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