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  • Laurent Dufour's avatar
    powerpc/mm: Add page soft dirty tracking · 7207f436
    Laurent Dufour authored
    
    
    User space checkpoint and restart tool (CRIU) needs the page's change
    to be soft tracked. This allows to do a pre checkpoint and then dump
    only touched pages.
    
    This is done by using a newly assigned PTE bit (_PAGE_SOFT_DIRTY) when
    the page is backed in memory, and a new _PAGE_SWP_SOFT_DIRTY bit when
    the page is swapped out.
    
    To introduce a new PTE _PAGE_SOFT_DIRTY bit value common to hash 4k
    and hash 64k pte, the bits already defined in hash-*4k.h should be
    shifted left by one.
    
    The _PAGE_SWP_SOFT_DIRTY bit is dynamically put after the swap type in
    the swap pte. A check is added to ensure that the bit is not
    overwritten by _PAGE_HPTEFLAGS.
    
    Signed-off-by: default avatarLaurent Dufour <ldufour@linux.vnet.ibm.com>
    CC: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    7207f436