===================================================================
@@ -20,8 +20,6 @@
static DEFINE_PER_CPU(struct cpu, cpu_devices);
-static int dualcores_found;
-
/*
* store_cpu_topology is called at boot when only one cpu is running
* and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
@@ -60,7 +58,6 @@ void store_cpu_topology(unsigned int cpu
if (p->cpu_loc) {
cpuid_topo->core_id++;
cpuid_topo->package_id = cpu_topology[cpu].package_id;
- dualcores_found = 1;
continue;
}
}
@@ -80,22 +77,11 @@ void store_cpu_topology(unsigned int cpu
cpu_topology[cpuid].package_id);
}
-static struct sched_domain_topology_level parisc_mc_topology[] = {
-#ifdef CONFIG_SCHED_MC
- { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
-#endif
-
- { cpu_cpu_mask, SD_INIT_NAME(DIE) },
- { NULL, },
-};
-
/*
* init_cpu_topology is called at boot when only one cpu is running
* which prevent simultaneous write access to cpu_topology array
*/
void __init init_cpu_topology(void)
{
- /* Set scheduler topology descriptor */
- if (dualcores_found)
- set_sched_topology(parisc_mc_topology);
+ reset_cpu_topology();
}
With the kernel 5.18, the system will hang on boot if it is compiled with CONFIG_SCHED_MC. The last printed message is "Brought up 1 node, 1 CPU". The crash happens in sd_init tl->mask (which is cpu_coregroup_mask) returns an empty mask. This happens because cpu_topology[0].core_sibling is empty. Consequently, sd_span is set to an empty mask sd_id = cpumask_first(sd_span) sets sd_id == NR_CPUS (because the mask is empty) sd->shared = *per_cpu_ptr(sdd->sds, sd_id); sets sd->shared to NULL because sd_id is out of range atomic_inc(&sd->shared->ref); crashes without printing anything We can fix it by calling reset_cpu_topology() from init_cpu_topology() - this will initialize the sibling masks on CPUs, so that they're not empty. This patch also removes the variable "dualcores_found", it is useless, because during boot, init_cpu_topology is called before store_cpu_topology. Thus, set_sched_topology(parisc_mc_topology) is never called. We don't need to call it at all because default_topology in kernel/sched/topology.c contains the same items as parisc_mc_topology. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org # v5.18 --- arch/parisc/kernel/topology.c | 16 +--------------- 1 file changed, 1 insertion(+), 15 deletions(-)