mm: compaction: update pageblock skip when first migration candidate is not at the start

isolate_migratepages_block should mark a pageblock as skip if scanning
started on an aligned pageblock boundary but it only updates the skip flag
if the first migration candidate is also aligned.  Tracing during a
compaction stress load (mmtests: workload-usemem-stress-numa-compact) that
many pageblocks are not marked skip causing excessive scanning of blocks
that had been recently checked.  Update pageblock skip based on
"valid_page" which is set if scanning started on a pageblock boundary.

[[email protected]: fix handling of skip bit]
  Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mel Gorman <[email protected]>
Tested-by: Raghavendra K T <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Chuyi Zhou <[email protected]>
Cc: Jiri Slaby <[email protected]>
Cc: Maxim Levitsky <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Pedro Falcato <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions