mm: page_alloc: fix up block types when merging compatible blocks

The buddy allocator coalesces compatible blocks during freeing, but it
doesn't update the types of the subblocks to match.  When an allocation
later breaks the chunk down again, its pieces will be put on freelists of
the wrong type.  This encourages incompatible page mixing (ask for one
type, get another), and thus long-term fragmentation.

Update the subblocks when merging a larger chunk, such that a later
expand() will maintain freelist type hygiene.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Johannes Weiner <[email protected]>
Reviewed-by: Zi Yan <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Tested-by: "Huang, Ying" <[email protected]>
Tested-by: Baolin Wang <[email protected]>
Cc: David Hildenbrand <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions