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    SubjectRe: [PATCH v5 1/5] mm,memory_hotplug: Allocate memmap from the added memory range
    On Wed 24-03-21 13:23:47, David Hildenbrand wrote:
    > On 24.03.21 13:10, Michal Hocko wrote:
    > > On Wed 24-03-21 13:03:29, Michal Hocko wrote:
    > > > On Wed 24-03-21 11:12:59, Oscar Salvador wrote:
    > > [...]
    > >
    > > an additional remark
    > >
    > > > > - online_pages()->move_pfn_range_to_zone(): Accounts for node/zone's spanned pages
    > > > > - online_pages()->zone->present_pages += nr_pages;
    > >
    > > I am pretty sure you shouldn't account vmmemmap pages to the target zone
    > > in some cases - e.g. vmemmap cannot be part of the movable zone, can it?
    > > So this would be yet another special casing. This patch has got it wrong
    > > unless I have missed some special casing.
    > >
    >
    > It's a bit unfortunate that we have to discuss the very basic design
    > decisions again.

    It would be great to have those basic design decisions layed out in the
    changelog.

    > @Oscar, maybe you can share the links where we discussed all this and add
    > some of it to the patch description.
    >
    > I think what we have right here is good enough for an initial version, from
    > where on we can improve things without having to modify calling code.

    I have to say I really dislike vmemmap proliferation into
    {on,off}lining. It just doesn't belong there from a layering POV. All
    this code should care about is to hand over pages to the allocator and
    make them visible.

    Is that a sufficient concern to nack the whole thing? No, I do not think
    so. But I do not see any particular rush to have this work needs to be
    merged ASAP.

    --
    Michal Hocko
    SUSE Labs

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