[PATCH AUTOSEL 6.1 32/57] s390/topology: honour nr_cpu_ids when adding CPUs

Sasha Levin
2023-05-25T18:43:09Z

From: Alexander Gordeev <agordeev@linux.ibm.com>

[ Upstream commit a33239be2d38ff5a44427db1707c08787508d34a ]

When SMT thread CPUs are added to CPU masks the nr_cpu_ids
limit is not checked and could be exceeded. This leads to
a warning for example if CONFIG_DEBUG_PER_CPU_MAPS is set
and the command line parameter nr_cpus is set to 1.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/kernel/topology.c | 32 +++++++++++++++++---------------
1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c
index c6eecd4a5302d..10b20aeb27d3b 100644
--- a/arch/s390/kernel/topology.c
+++ b/arch/s390/kernel/topology.c
@@ -95,7 +95,7 @@ static void cpu_group_map(cpumask_t *dst, struct mask_info *info, unsigned int c
static void cpu_thread_map(cpumask_t *dst, unsigned int cpu)
{
static cpumask_t mask;
- int i;
+ unsigned int max_cpu;

cpumask_clear(&mask);
if (!cpumask_test_cpu(cpu, &cpu_setup_mask))
@@ -104,9 +104,10 @@ static void cpu_thread_map(cpumask_t *dst, unsigned int cpu)
if (topology_mode != TOPOLOGY_MODE_HW)
goto out;
cpu -= cpu % (smp_cpu_mtid + 1);
- for (i = 0; i <= smp_cpu_mtid; i++) {
- if (cpumask_test_cpu(cpu + i, &cpu_setup_mask))
- cpumask_set_cpu(cpu + i, &mask);
+ max_cpu = min(cpu + smp_cpu_mtid, nr_cpu_ids - 1);
+ for (; cpu <= max_cpu; cpu++) {
+ if (cpumask_test_cpu(cpu, &cpu_setup_mask))
+ cpumask_set_cpu(cpu, &mask);
}
out:
cpumask_copy(dst, &mask);
@@ -123,25 +124,26 @@ static void add_cpus_to_mask(struct topology_core *tl_core,
unsigned int core;

for_each_set_bit(core, &tl_core->mask, TOPOLOGY_CORE_BITS) {
- unsigned int rcore;
- int lcpu, i;
+ unsigned int max_cpu, rcore;
+ int cpu;

rcore = TOPOLOGY_CORE_BITS - 1 - core + tl_core->origin;
- lcpu = smp_find_processor_id(rcore << smp_cpu_mt_shift);
- if (lcpu < 0)
+ cpu = smp_find_processor_id(rcore << smp_cpu_mt_shift);
+ if (cpu < 0)
continue;
- for (i = 0; i <= smp_cpu_mtid; i++) {
- topo = &cpu_topology[lcpu + i];
+ max_cpu = min(cpu + smp_cpu_mtid, nr_cpu_ids - 1);
+ for (; cpu <= max_cpu; cpu++) {
+ topo = &cpu_topology[cpu];
topo->drawer_id = drawer->id;
topo->book_id = book->id;
topo->socket_id = socket->id;
topo->core_id = rcore;
- topo->thread_id = lcpu + i;
+ topo->thread_id = cpu;
topo->dedicated = tl_core->d;
- cpumask_set_cpu(lcpu + i, &drawer->mask);
- cpumask_set_cpu(lcpu + i, &book->mask);
- cpumask_set_cpu(lcpu + i, &socket->mask);
- smp_cpu_set_polarization(lcpu + i, tl_core->pp);
+ cpumask_set_cpu(cpu, &drawer->mask);
+ cpumask_set_cpu(cpu, &book->mask);
+ cpumask_set_cpu(cpu, &socket->mask);
+ smp_cpu_set_polarization(cpu, tl_core->pp);
}
}
}
--
2.39.2