mm: page_alloc: fix move_freepages_block() range error

When a block is partially outside the zone of the cursor page, the
function cuts the range to the pivot page instead of the zone start.  This
can leave large parts of the block behind, which encourages incompatible
page mixing down the line (ask for one type, get another), and thus
long-term fragmentation.

This triggers reliably on the first block in the DMA zone, whose start_pfn
is 1.  The block is stolen, but everything before the pivot page (which
was often hundreds of pages) is left on the old list.

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

0 files changed, 0 insertions, 0 deletions