The patch titled Subject: mm: compaction: do not accidentally skip pageblocks in the migrate scanner has been removed from the -mm tree. Its filename was mm-compaction-do-not-accidentally-skip-pageblocks-in-the-migrate-scanner.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Mel Gorman <mgorman@xxxxxxx> Subject: mm: compaction: do not accidentally skip pageblocks in the migrate scanner Compaction uses the ALIGN macro incorrectly with the migrate scanner by adding pageblock_nr_pages to a PFN. It happened to work when initially implemented as the starting PFN was also aligned but with caching restarts and isolating in smaller chunks this is no longer always true. The impact is that the migrate scanner scans outside its current pageblock. As pfn_valid() is still checked properly it does not cause any failure and the impact of the bug is that in some cases it will scan more than necessary when it crosses a page boundary but by no more than COMPACT_CLUSTER_MAX. It is highly unlikely this is even measurable but it's still wrong so this patch addresses the problem. Signed-off-by: Mel Gorman <mgorman@xxxxxxx> Reviewed-by: Rik van Riel <riel@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/compaction.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff -puN mm/compaction.c~mm-compaction-do-not-accidentally-skip-pageblocks-in-the-migrate-scanner mm/compaction.c --- a/mm/compaction.c~mm-compaction-do-not-accidentally-skip-pageblocks-in-the-migrate-scanner +++ a/mm/compaction.c @@ -611,8 +611,7 @@ check_compact_cluster: continue; next_pageblock: - low_pfn += pageblock_nr_pages; - low_pfn = ALIGN(low_pfn, pageblock_nr_pages) - 1; + low_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages) - 1; last_pageblock_nr = pageblock_nr; } @@ -795,7 +794,7 @@ static isolate_migrate_t isolate_migrate low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn); /* Only scan within a pageblock boundary */ - end_pfn = ALIGN(low_pfn + pageblock_nr_pages, pageblock_nr_pages); + end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages); /* Do not cross the free scanner or scan within a memory hole */ if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) { _ Patches currently in -mm which might be from mgorman@xxxxxxx are origin.patch linux-next.patch revert-x86-mm-make-spurious_fault-check-explicitly-check-the-present-bit.patch pageattr-prevent-pse-and-gloabl-leftovers-to-confuse-pmd-pte_present-and-pmd_huge.patch mm-memmap_init_zone-performance-improvement.patch mm-accelerate-munlock-treatment-of-thp-pages.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html