• Aneesh Kumar K.V's avatar
    mm: update get_user_pages_longterm to migrate pages allocated from CMA region · 9a4e9f3b
    Aneesh Kumar K.V authored
    This patch updates get_user_pages_longterm to migrate pages allocated
    out of CMA region.  This makes sure that we don't keep non-movable pages
    (due to page reference count) in the CMA area.
    
    This will be used by ppc64 in a later patch to avoid pinning pages in
    the CMA region.  ppc64 uses CMA region for allocation of the hardware
    page table (hash page table) and not able to migrate pages out of CMA
    region results in page table allocation failures.
    
    One case where we hit this easy is when a guest using a VFIO passthrough
    device.  VFIO locks all the guest's memory and if the guest memory is
    backed by CMA region, it becomes unmovable resulting in fragmenting the
    CMA and possibly preventing other guests from allocation a large enough
    hash page table.
    
    NOTE: We allocate the new page without using __GFP_THISNODE
    
    Link: http://lkml.kernel.org/r/20190114095438.32470-3-aneesh.kumar@linux.ibm.com
    
    Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
    Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: David Gibson <david@gibson.dropbear.id.au>
    Cc: Michael Ellerman <mpe@ellerman.id.au>
    Cc: Michal Hocko <mhocko@kernel.org>
    Cc: Mel Gorman <mgorman@techsingularity.net>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    9a4e9f3b
hugetlb.h 19.2 KB