Commit 9ecea9ae authored by Yury Norov's avatar Yury Norov Committed by Ingo Molnar
Browse files

sched/topology: Handle NUMA_NO_NODE in sched_numa_find_nth_cpu() 



sched_numa_find_nth_cpu() doesn't handle NUMA_NO_NODE properly, and
may crash kernel if passed with it. On the other hand, the only user
of sched_numa_find_nth_cpu() has to check NUMA_NO_NODE case explicitly.

It would be easier for users if this logic will get moved into
sched_numa_find_nth_cpu().

Signed-off-by: default avatarYury Norov <yury.norov@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20230819141239.287290-6-yury.norov@gmail.com
parent 8ab63d41

kernel/sched/topology.c

+3 −0
Original line number Diff line number Diff line
@@ -2126,6 +2126,9 @@ int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node) 
	struct cpumask ***hop_masks;

	int hop, ret = nr_cpu_ids;



	if (node == NUMA_NO_NODE)

		return cpumask_nth_and(cpu, cpus, cpu_online_mask);



	rcu_read_lock();



	/* CPU-less node entries are uninitialized in sched_domains_numa_masks */

lib/cpumask.c

+1 −3
Original line number Diff line number Diff line
@@ -146,9 +146,7 @@ unsigned int cpumask_local_spread(unsigned int i, int node) 
	/* Wrap: we always want a cpu. */

	i %= num_online_cpus();



	cpu = (node == NUMA_NO_NODE) ?

		cpumask_nth(i, cpu_online_mask) :

		sched_numa_find_nth_cpu(cpu_online_mask, i, node);

	cpu = sched_numa_find_nth_cpu(cpu_online_mask, i, node);



	WARN_ON(cpu >= nr_cpu_ids);

	return cpu;