Commit 851ae642 authored by Huang Ying's avatar Huang Ying Committed by Andrew Morton
Browse files

migrate_pages_batch: fix statistics for longterm pin retry 

In commit fd4a7ac3 ("mm: migrate: try again if THP split is failed due
to page refcnt"), if the THP splitting fails due to page reference count,
we will retry to improve migration successful rate.  But the failed
splitting is counted as migration failure and migration retry, which will
cause duplicated failure counting.  So, in this patch, this is fixed via
undoing the failure counting if we decide to retry.  The patch is tested
via failure injection.

Link: https://lkml.kernel.org/r/20230416235929.1040194-1-ying.huang@intel.com


Fixes: fd4a7ac3 ("mm: migrate: try again if THP split is failed due to page refcnt")
Signed-off-by: default avatar"Huang, Ying" <ying.huang@intel.com>
Reviewed-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 686ea6e6

mm/migrate.c

+3 −0
Original line number Diff line number Diff line
@@ -1710,6 +1710,9 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, 
							large_retry++;

							thp_retry += is_thp;

							nr_retry_pages += nr_pages;

							/* Undo duplicated failure counting. */

							nr_large_failed--;

							stats->nr_thp_failed -= is_thp;

							break;

						}

					}