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Commit 5d5a0800 authored by Kirill Tkhai's avatar Kirill Tkhai Committed by Paul E. McKenney
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rcu: Fix CONFIG_RCU_NOCB_CPU_ALL panic on machines with sparse CPU mask 



Some architectures have sparse cpu mask. UltraSparc's cpuinfo for example:

CPU0: online
CPU2: online

So, set only possible CPUs when CONFIG_RCU_NOCB_CPU_ALL is enabled.

Also, check that user passes right 'rcu_nocbs=' option.

Signed-off-by: default avatarKirill Tkhai <tkhai@yandex.ru>
CC: Dipankar Sarma <dipankar@in.ibm.com>
[ paulmck: Fix pr_info() issue noted by scripts/checkpatch.pl. ]
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 0d752924

kernel/rcutree_plugin.h

+6 −1
Original line number Diff line number Diff line
@@ -96,10 +96,15 @@ static void __init rcu_bootup_announce_oddness(void) 
#endif /* #ifdef CONFIG_RCU_NOCB_CPU_ZERO */

#ifdef CONFIG_RCU_NOCB_CPU_ALL

	pr_info("\tOffload RCU callbacks from all CPUs\n");

	cpumask_setall(rcu_nocb_mask);

	cpumask_copy(rcu_nocb_mask, cpu_possible_mask);

#endif /* #ifdef CONFIG_RCU_NOCB_CPU_ALL */

#endif /* #ifndef CONFIG_RCU_NOCB_CPU_NONE */

	if (have_rcu_nocb_mask) {

		if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {

			pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");

			cpumask_and(rcu_nocb_mask, cpu_possible_mask,

				    rcu_nocb_mask);

		}

		cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);

		pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);

		if (rcu_nocb_poll)