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But there are two edge cases. First, if the page we found is equal to cc->migrate_pfn, it is considered that we didn't found suitable pageblock. Second, if the loop was terminated because order is less than PAGE_ALLOC_COSTLY_ORDER, it could be considered that we found suitable one. Fixes: 70b44595eafe9 ("mm, compaction: use free lists to quickly locate a migration source") Signed-off-by: Wonhyuk Yang --- mm/compaction.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index e5acb9714436..46f49e6b7d1a 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1742,8 +1742,8 @@ static unsigned long fast_find_migrateblock(struct = compact_control *cc) distance >>=3D 2; high_pfn =3D pageblock_start_pfn(cc->migrate_pfn + distance); =20 - for (order =3D cc->order - 1; - order >=3D PAGE_ALLOC_COSTLY_ORDER && pfn =3D=3D cc->migrate_pfn &= & nr_scanned < limit; + for (order =3D cc->order - 1, pfn =3D high_pfn; + order >=3D PAGE_ALLOC_COSTLY_ORDER && pfn =3D=3D high_pfn && nr_sc= anned < limit; order--) { struct free_area *area =3D &cc->zone->free_area[order]; struct list_head *freelist; @@ -1785,7 +1785,6 @@ static unsigned long fast_find_migrateblock(struct = compact_control *cc) } =20 if (nr_scanned >=3D limit) { - cc->fast_search_fail++; move_freelist_tail(freelist, freepage); break; } @@ -1799,9 +1798,10 @@ static unsigned long fast_find_migrateblock(struct= compact_control *cc) * If fast scanning failed then use a cached entry for a page block * that had free pages as the basis for starting a linear scan. */ - if (pfn =3D=3D cc->migrate_pfn) + if (pfn =3D=3D high_pfn) { + cc->fast_search_fail++; pfn =3D reinit_migrate_pfn(cc); - + } return pfn; } =20 --=20 2.25.1