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powerpc/pseries: Fix cpu hotplug crash with memoryless nodes 

On powerpc systems with shared configurations of CPUs and memory and
memoryless nodes at boot, an event ordering problem was observed on a
SLES12 build platforms with the hot-add of CPUs to the memoryless
nodes.

* The most common error occurred when the memory SLAB driver attempted
  to reference the memoryless node to which a CPU was being added
  before the kernel had finished initializing all of the data
  structures for the CPU and exited 'device_online' under
  DLPAR/hot-add.

  Normally the memoryless node would be initialized through the call
  path device_online ... arch_update_cpu_topology ... find_cpu_nid ...
  try_online_node. This patch ensures that the powerpc node will be
  initialized as early as possible, even if it was memoryless and
  CPU-less at the point when we are trying to hot-add a new CPU to it.

Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Michael Bringmann 2017-11-28 16:58:43 -06:00 committed by Michael Ellerman
parent ea05ba7c55
commit e67e02a544
2 changed files with 6 additions and 1 deletions
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4
arch/powerpc/mm/numa.c
View File

@ -1198,7 +1198,7 @@ static long vphn_get_associativity(unsigned long cpu,
return rc;
}
static inline int find_and_online_cpu_nid(int cpu)
int find_and_online_cpu_nid(int cpu)
{
__be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};
int new_nid;
@ -1229,6 +1229,8 @@ static inline int find_and_online_cpu_nid(int cpu)
#endif
}
pr_debug("%s:%d cpu %d nid %d\n", __FUNCTION__, __LINE__,
cpu, new_nid);
return new_nid;
}

3
arch/powerpc/platforms/pseries/hotplug-cpu.c
View File

@ -340,6 +340,8 @@ static void pseries_remove_processor(struct device_node *np)
cpu_maps_update_done();
}
extern int find_and_online_cpu_nid(int cpu);
static int dlpar_online_cpu(struct device_node *dn)
{
int rc = 0;
@ -364,6 +366,7 @@ static int dlpar_online_cpu(struct device_node *dn)
!= CPU_STATE_OFFLINE);
cpu_maps_update_done();
timed_topology_update(1);
find_and_online_cpu_nid(cpu);
rc = device_online(get_cpu_device(cpu));
if (rc)
goto out;