• Michal Hocko's avatar
    mm, hugetlb: remove hugepages_treat_as_movable sysctl · d6cb41cc
    Michal Hocko authored
    hugepages_treat_as_movable has been introduced by 396faf03 ("Allow
    huge page allocations to use GFP_HIGH_MOVABLE") to allow hugetlb
    allocations from ZONE_MOVABLE even when hugetlb pages were not
    migrateable.  The purpose of the movable zone was different at the time.
    It aimed at reducing memory fragmentation and hugetlb pages being long
    lived and large werre not contributing to the fragmentation so it was
    acceptable to use the zone back then.
    
    Things have changed though and the primary purpose of the zone became
    migratability guarantee.  If we allow non migrateable hugetlb pages to
    be in ZONE_MOVABLE memory hotplug might fail to offline the memory.
    
    Remove the knob and only rely on hugepage_migration_supported to allow
    movable zones.
    
    Mel said:
    
    : Primarily it was aimed at allowing the hugetlb pool to safely shrink with
    : the ability to grow it again.  The use case was for batched jobs, some of
    : which needed huge pages and others that did not but didn't want the memory
    : useless pinned in the huge pages pool.
    :
    : I suspect that more users rely on THP than hugetlbfs for flexible use of
    : huge pages with fallback options so I think that removing the option
    : should be ok.
    
    Link: http://lkml.kernel.org/r/20171003072619.8654-1-mhocko@kernel.org
    
    Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
    Reported-by: default avatarAlexandru Moise <00moses.alexander00@gmail.com>
    Acked-by: default avatarMel Gorman <mgorman@suse.de>
    Cc: Alexandru Moise <00moses.alexander00@gmail.com>
    Cc: Mike Kravetz <mike.kravetz@oracle.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    d6cb41cc
hugetlb.h 16.5 KB