• Aneesh Kumar K.V's avatar
    powerpc/mm: Increase the max addressable memory to 2PB · 4ffe713b
    Aneesh Kumar K.V authored
    Currently we limit the max addressable memory to 128TB. This patch increase the
    limit to 2PB. We can have devices like nvdimm which adds memory above 512TB
    limit.
    
    We still don't support regular system ram above 512TB. One of the challenge with
    that is the percpu allocator, that allocates per node memory and use the max
    distance between them as the percpu offsets. This means with large gap in
    address space ( system ram above 1PB) we will run out of vmalloc space to map
    the percpu allocation.
    
    In order to support addressable memory above 512TB, kernel should be able to
    linear map this range. To do that with hash translation we now add 4 context
    to kernel linear map region. Our per context addressable range is 512TB. We
    still keep VMALLOC and VMEMMAP region to old size. SLB miss handlers is updated
    to validate these limit.
    
    We also limit this update to SPARSEMEM_VMEMMAP and SPARSEMEM_EXTREME
    Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    4ffe713b
slb.c 21.5 KB