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    SubjectRe: [PATCH 1/2] mm, memory_hotplug: do not fail offlining too early
    On Wed 11-10-17 10:04:39, Vlastimil Babka wrote:
    > On 10/11/2017 08:51 AM, Michal Hocko wrote:
    [...]
    > > This is really strange! As you write in other email the page is
    > > reserved. That means that some of the earlier checks
    > > if (zone_idx(zone) == ZONE_MOVABLE)
    > > return false;
    > > mt = get_pageblock_migratetype(page);
    > > if (mt == MIGRATE_MOVABLE || is_migrate_cma(mt))
    >
    > The MIGRATE_MOVABLE check is indeed bogus, because that doesn't
    > guarantee there are no unmovable pages in the block (CMA block OTOH
    > should be a guarantee).

    OK, thanks for confirmation. I will remove the MIGRATE_MOVABLE check
    here. Do you think it is worth removing CMA check as well? This is
    merely an optimization AFAIU because we do not have to check the full
    pageblockworth of pfns.

    Anyway, let's way for Michael to confirm it really helps. If yes I will
    post a full patch and ask Andrew to add it as a prerequisite for this
    patch when sending to Linus to prevent the regression.
    --
    Michal Hocko
    SUSE Labs

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