• Nathan Fontenot's avatar
    powerpc/pseries: Perform full re-add of CPU for topology update post-migration · 81b61324
    Nathan Fontenot authored
    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: default avatarNathan Fontenot <nfont@linux.vnet.ibm.com>
    Signed-off-by: default avatarMichael W. Bringmann <mwb@linux.vnet.ibm.com>
    Tested-by: default avatarMichael W. Bringmann <mwb@linux.vnet.ibm.com>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    81b61324
hotplug-cpu.c 22 KB