• Hugh Dickins's avatar
    powerpc/mm: fix _PAGE_SWP_SOFT_DIRTY breaking swapoff · 2f10f1a7
    Hugh Dickins authored
    Swapoff after swapping hangs on the G5, when CONFIG_CHECKPOINT_RESTORE=y
    but CONFIG_MEM_SOFT_DIRTY is not set.  That's because the non-zero
    _PAGE_SWP_SOFT_DIRTY bit, added by CONFIG_HAVE_ARCH_SOFT_DIRTY=y, is not
    discounted when CONFIG_MEM_SOFT_DIRTY is not set: so swap ptes cannot be
    recognized.
    
    (I suspect that the peculiar dependence of HAVE_ARCH_SOFT_DIRTY on
    CHECKPOINT_RESTORE in arch/powerpc/Kconfig comes from an incomplete
    attempt to solve this problem.)
    
    It's true that the relationship between CONFIG_HAVE_ARCH_SOFT_DIRTY and
    and CONFIG_MEM_SOFT_DIRTY is too confusing, and it's true that swapoff
    should be made more robust; but nevertheless, fix up the powerpc ifdefs
    as x86_64 and s390 (which met the same problem) have them, defining the
    bits as 0 if CONFIG_MEM_SOFT_DIRTY is not set.
    
    Fixes: 7207f436 ("powerpc/mm: Add page soft dirty tracking")
    Signed-off-by: default avatarHugh Dickins <hughd@google.com>
    Reviewed-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
    Acked-by: default avatarLaurent Dufour <ldufour@linux.vnet.ibm.com>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    2f10f1a7
pgtable.h 9.06 KB