sched/core: Fix cpu.max vs. cpuhotplug deadlock
Tejun reported the following cpu-hotplug lock (percpu-rwsem) read recursion: tg_set_cfs_bandwidth() get_online_cpus() cpus_read_lock() cfs_bandwidth_usage_inc() static_key_slow_inc() cpus_read_lock() Reported-by: Tejun Heo <tj@kernel.org> Tested-by: Tejun Heo <tj@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20180122215328.GP3397@worktop Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -160,6 +160,8 @@ extern void arch_jump_label_transform_static(struct jump_entry *entry,
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extern int jump_label_text_reserved(void *start, void *end);
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extern void static_key_slow_inc(struct static_key *key);
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extern void static_key_slow_dec(struct static_key *key);
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extern void static_key_slow_inc_cpuslocked(struct static_key *key);
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extern void static_key_slow_dec_cpuslocked(struct static_key *key);
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extern void jump_label_apply_nops(struct module *mod);
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extern int static_key_count(struct static_key *key);
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extern void static_key_enable(struct static_key *key);
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@ -222,6 +224,9 @@ static inline void static_key_slow_dec(struct static_key *key)
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atomic_dec(&key->enabled);
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}
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#define static_key_slow_inc_cpuslocked(key) static_key_slow_inc(key)
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#define static_key_slow_dec_cpuslocked(key) static_key_slow_dec(key)
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static inline int jump_label_text_reserved(void *start, void *end)
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{
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return 0;
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@ -416,6 +421,8 @@ extern bool ____wrong_branch_error(void);
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#define static_branch_inc(x) static_key_slow_inc(&(x)->key)
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#define static_branch_dec(x) static_key_slow_dec(&(x)->key)
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#define static_branch_inc_cpuslocked(x) static_key_slow_inc_cpuslocked(&(x)->key)
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#define static_branch_dec_cpuslocked(x) static_key_slow_dec_cpuslocked(&(x)->key)
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/*
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* Normal usage; boolean enable/disable.
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@ -79,7 +79,7 @@ int static_key_count(struct static_key *key)
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}
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EXPORT_SYMBOL_GPL(static_key_count);
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static void static_key_slow_inc_cpuslocked(struct static_key *key)
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void static_key_slow_inc_cpuslocked(struct static_key *key)
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{
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int v, v1;
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@ -180,7 +180,7 @@ void static_key_disable(struct static_key *key)
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}
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EXPORT_SYMBOL_GPL(static_key_disable);
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static void static_key_slow_dec_cpuslocked(struct static_key *key,
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static void __static_key_slow_dec_cpuslocked(struct static_key *key,
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unsigned long rate_limit,
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struct delayed_work *work)
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{
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@ -211,7 +211,7 @@ static void __static_key_slow_dec(struct static_key *key,
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struct delayed_work *work)
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{
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cpus_read_lock();
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static_key_slow_dec_cpuslocked(key, rate_limit, work);
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__static_key_slow_dec_cpuslocked(key, rate_limit, work);
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cpus_read_unlock();
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}
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@ -229,6 +229,12 @@ void static_key_slow_dec(struct static_key *key)
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}
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EXPORT_SYMBOL_GPL(static_key_slow_dec);
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void static_key_slow_dec_cpuslocked(struct static_key *key)
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{
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STATIC_KEY_CHECK_USE(key);
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__static_key_slow_dec_cpuslocked(key, 0, NULL);
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}
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void static_key_slow_dec_deferred(struct static_key_deferred *key)
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{
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STATIC_KEY_CHECK_USE(key);
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@ -4365,12 +4365,12 @@ static inline bool cfs_bandwidth_used(void)
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void cfs_bandwidth_usage_inc(void)
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{
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static_key_slow_inc(&__cfs_bandwidth_used);
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static_key_slow_inc_cpuslocked(&__cfs_bandwidth_used);
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}
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void cfs_bandwidth_usage_dec(void)
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{
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static_key_slow_dec(&__cfs_bandwidth_used);
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static_key_slow_dec_cpuslocked(&__cfs_bandwidth_used);
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}
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#else /* HAVE_JUMP_LABEL */
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static bool cfs_bandwidth_used(void)
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