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: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20230819141239.287290-6-yury.norov@gmail.com

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 423d08947962c8acd7ac304e6a7a995fb6a58d5f..a60ecf45360cbbb646eae6203c7aae6c23d7fe01 100644 (file)
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -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 */

diff --git a/lib/cpumask.c b/lib/cpumask.c
index a7fd02b5ae264ce1d8e58b949face2bbefc5fcb0..34335c1e72653dc97e55bab4c0fb9c9b260c315c 100644 (file)
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -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;