This is a note to let you know that I've just added the patch titled
sched/topology: Handle NUMA_NO_NODE in sched_numa_find_nth_cpu()
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sched-topology-handle-numa_no_node-in-sched_numa_fin.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 46461893a791e79387f73e61c9cacd8f250736aa
Author: Yury Norov <yury.norov@xxxxxxxxx>
Date: Sat Aug 19 07:12:37 2023 -0700
sched/topology: Handle NUMA_NO_NODE in sched_numa_find_nth_cpu()
[ Upstream commit 9ecea9ae4d3127a09fb5dfcea87f248937a39ff5 ]
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@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Link: https://lore.kernel.org/r/20230819141239.287290-6-yury.norov@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 8c1e183329d97..3a13cecf17740 100644
--- 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 a7fd02b5ae264..34335c1e72653 100644
--- 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;
