From 81b61324922c67f73813d8a9c175f3c153f6a1c6 Mon Sep 17 00:00:00 2001 From: Nathan Fontenot Date: Mon, 29 Oct 2018 13:43:36 -0500 Subject: powerpc/pseries: Perform full re-add of CPU for topology update post-migration On pseries systems, performing a partition migration can result in altering the nodes a CPU is assigned to on the destination system. For exampl, pre-migration on the source system CPUs are in node 1 and 3, post-migration on the destination system CPUs are in nodes 2 and 3. Handling the node change for a CPU can cause corruption in the slab cache if we hit a timing where a CPUs node is changed while cache_reap() is invoked. The corruption occurs because the slab cache code appears to rely on the CPU and slab cache pages being on the same node. The current dynamic updating of a CPUs node done in arch/powerpc/mm/numa.c does not prevent us from hitting this scenario. Changing the device tree property update notification handler that recognizes an affinity change for a CPU to do a full DLPAR remove and add of the CPU instead of dynamically changing its node resolves this issue. Signed-off-by: Nathan Fontenot Signed-off-by: Michael W. Bringmann Tested-by: Michael W. Bringmann Signed-off-by: Michael Ellerman --- arch/powerpc/platforms/pseries/hotplug-cpu.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'arch/powerpc/platforms') diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c index 2f8e62163602..97feb6e79f1a 100644 --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c @@ -802,6 +802,25 @@ static int dlpar_cpu_add_by_count(u32 cpus_to_add) return rc; } +int dlpar_cpu_readd(int cpu) +{ + struct device_node *dn; + struct device *dev; + u32 drc_index; + int rc; + + dev = get_cpu_device(cpu); + dn = dev->of_node; + + rc = of_property_read_u32(dn, "ibm,my-drc-index", &drc_index); + + rc = dlpar_cpu_remove_by_index(drc_index); + if (!rc) + rc = dlpar_cpu_add(drc_index); + + return rc; +} + int dlpar_cpu(struct pseries_hp_errorlog *hp_elog) { u32 count, drc_index; -- cgit v1.2.3-59-g8ed1b