lkml.org 
[lkml]   [2019]   [Mar]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH AUTOSEL 4.19 152/192] powerpc/pseries: Perform full re-add of CPU for topology update post-migration
    Date
    From: Nathan Fontenot <nfont@linux.vnet.ibm.com>

    [ Upstream commit 81b61324922c67f73813d8a9c175f3c153f6a1c6 ]

    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 <nfont@linux.vnet.ibm.com>
    Signed-off-by: Michael W. Bringmann <mwb@linux.vnet.ibm.com>
    Tested-by: Michael W. Bringmann <mwb@linux.vnet.ibm.com>
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/powerpc/include/asm/topology.h | 2 ++
    arch/powerpc/mm/numa.c | 9 +--------
    arch/powerpc/platforms/pseries/hotplug-cpu.c | 19 +++++++++++++++++++
    3 files changed, 22 insertions(+), 8 deletions(-)

    diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
    index a4a718dbfec6..f85e2b01c3df 100644
    --- a/arch/powerpc/include/asm/topology.h
    +++ b/arch/powerpc/include/asm/topology.h
    @@ -132,6 +132,8 @@ static inline void shared_proc_topology_init(void) {}
    #define topology_sibling_cpumask(cpu) (per_cpu(cpu_sibling_map, cpu))
    #define topology_core_cpumask(cpu) (per_cpu(cpu_core_map, cpu))
    #define topology_core_id(cpu) (cpu_to_core_id(cpu))
    +
    +int dlpar_cpu_readd(int cpu);
    #endif
    #endif

    diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
    index 5500e4edabc6..10fb43efef50 100644
    --- a/arch/powerpc/mm/numa.c
    +++ b/arch/powerpc/mm/numa.c
    @@ -1461,13 +1461,6 @@ static void reset_topology_timer(void)

    #ifdef CONFIG_SMP

    -static void stage_topology_update(int core_id)
    -{
    - cpumask_or(&cpu_associativity_changes_mask,
    - &cpu_associativity_changes_mask, cpu_sibling_mask(core_id));
    - reset_topology_timer();
    -}
    -
    static int dt_update_callback(struct notifier_block *nb,
    unsigned long action, void *data)
    {
    @@ -1480,7 +1473,7 @@ static int dt_update_callback(struct notifier_block *nb,
    !of_prop_cmp(update->prop->name, "ibm,associativity")) {
    u32 core_id;
    of_property_read_u32(update->dn, "reg", &core_id);
    - stage_topology_update(core_id);
    + rc = dlpar_cpu_readd(core_id);
    rc = NOTIFY_OK;
    }
    break;
    diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
    index 6ef77caf7bcf..1d3f9313c02f 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;
    --
    2.19.1
    \
     
     \ /
      Last update: 2019-03-27 20:00    [W:4.484 / U:0.688 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site