Michal Hocko <mho...@kernel.org> writes:

> From: Michal Hocko <mho...@suse.com>
>
> Michael has noticed that the memory offline tries to migrate kernel code
> pages when doing
>  echo 0 > /sys/devices/system/memory/memory0/online
>
> The current implementation will fail the operation after several failed
> page migration attempts but we shouldn't even attempt to migrate
> that memory and fail right away because this memory is clearly not
> migrateable. This will become a real problem when we drop the retry loop
> counter resp. timeout.
>
> The real problem is in has_unmovable_pages in fact. We should fail if
> there are any non migrateable pages in the area. In orther to guarantee
> that remove the migrate type checks because MIGRATE_MOVABLE is not
> guaranteed to contain only migrateable pages. It is merely a heuristic.
> Similarly MIGRATE_CMA does guarantee that the page allocator doesn't
> allocate any non-migrateable pages from the block but CMA allocations
> themselves are unlikely to migrateable. Therefore remove both checks.
>
> Reported-by: Michael Ellerman <m...@ellerman.id.au>
> Signed-off-by: Michal Hocko <mho...@suse.com>

Thanks, that works for me.

Tested-by: Michael Ellerman <m...@ellerman.id.au>

cheers

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