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s390/topology: fix topology information when calling cpu hotplug notifiers

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The cpu hotplug notifiers are called without updating the core/thread
masks when a new CPU is added. This causes problems with code setting
up data structures in a cpu hotplug notifier, and relying on that later
in normal code.

This caused a crash in the new core scheduling code (SCHED_CORE),
where rq->core was set up in a notifier depending on cpu masks.

To fix this, add a cpu_setup_mask which is used in update_cpu_masks()
instead of the cpu_online_mask to determine whether the cpu masks should
be set for a certain cpu. Also move update_cpu_masks() to update the
masks before calling notify_cpu_starting() so that the notifiers are
seeing the updated masks.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Cc: <stable@vger.kernel.org>
[hca@linux.ibm.com: get rid of cpu_online_mask handling]
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Sven Schnelle
2021-08-27 20:21:05 +02:00
committed by Heiko Carstens
parent 88b604263f
commit a052096bdd
3 changed files with 15 additions and 8 deletions
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9
arch/s390/kernel/smp.c
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@@ -95,6 +95,7 @@ __vector128 __initdata boot_cpu_vector_save_area[__NUM_VXRS];
#endif
static unsigned int smp_max_threads __initdata = -1U;
cpumask_t cpu_setup_mask;
static int __init early_nosmt(char *s)
{
@@ -902,13 +903,14 @@ static void smp_start_secondary(void *cpuvoid)
vtime_init();
vdso_getcpu_init();
pfault_init();
cpumask_set_cpu(cpu, &cpu_setup_mask);
update_cpu_masks();
notify_cpu_starting(cpu);
if (topology_cpu_dedicated(cpu))
set_cpu_flag(CIF_DEDICATED_CPU);
else
clear_cpu_flag(CIF_DEDICATED_CPU);
set_cpu_online(cpu, true);
update_cpu_masks();
inc_irq_stat(CPU_RST);
local_irq_enable();
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
@@ -950,10 +952,13 @@ early_param("possible_cpus", _setup_possible_cpus);
int __cpu_disable(void)
{
unsigned long cregs[16];
int cpu;
/* Handle possible pending IPIs */
smp_handle_ext_call();
set_cpu_online(smp_processor_id(), false);
cpu = smp_processor_id();
set_cpu_online(cpu, false);
cpumask_clear_cpu(cpu, &cpu_setup_mask);
update_cpu_masks();
/* Disable pseudo page faults on this cpu. */
pfault_fini();