[to-be-updated] mm-migrate-do-not-migrate-hugetlb-page-whose-refcount-is-one.patch removed from -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: mm: migrate: do not migrate HugeTLB page whose refcount is one
has been removed from the -mm tree.  Its filename was
     mm-migrate-do-not-migrate-hugetlb-page-whose-refcount-is-one.patch

This patch was dropped because an updated version will be merged

------------------------------------------------------
From: Muchun Song <songmuchun@bytedance.com>
Subject: mm: migrate: do not migrate HugeTLB page whose refcount is one

All pages isolated for the migration have an elevated reference count
and therefore seeing a reference count equal to 1 means that the last
user of the page has dropped the reference and the page has became
unused and there doesn't make much sense to migrate it anymore.  This
has been done for regular pages and this patch does the same for
hugetlb pages.  Although the likelyhood of the race is rather small for
hugetlb pages it makes sense the two code paths in sync.

[mhocko@suse.com: new changelog]
Link: https://lkml.kernel.org/r/20210110124017.86750-2-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Yang Shi <shy828301@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/migrate.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/mm/migrate.c~mm-migrate-do-not-migrate-hugetlb-page-whose-refcount-is-one
+++ a/mm/migrate.c
@@ -1284,6 +1284,12 @@ static int unmap_and_move_huge_page(new_
 		return -ENOSYS;
 	}
 
+	if (page_count(hpage) == 1) {
+		/* page was freed from under us. So we are done. */
+		putback_active_hugepage(hpage);
+		return MIGRATEPAGE_SUCCESS;
+	}
+
 	new_hpage = get_new_page(hpage, private);
 	if (!new_hpage)
 		return -ENOMEM;
_

Patches currently in -mm which might be from songmuchun@bytedance.com are

mm-hugetlbfs-fix-cannot-migrate-the-fallocated-hugetlb-page.patch
mm-hugetlb-fix-a-race-between-freeing-and-dissolving-the-page.patch
mm-hugetlb-fix-a-race-between-isolating-and-freeing-page.patch
mm-hugetlb-remove-vm_bug_on_page-from-page_huge_active.patch
mm-memcontrol-optimize-per-lruvec-stats-counter-memory-usage.patch
mm-memcontrol-fix-nr_anon_thps-accounting-in-charge-moving.patch
mm-memcontrol-convert-nr_anon_thps-account-to-pages.patch
mm-memcontrol-convert-nr_file_thps-account-to-pages.patch
mm-memcontrol-convert-nr_shmem_thps-account-to-pages.patch
mm-memcontrol-convert-nr_shmem_pmdmapped-account-to-pages.patch
mm-memcontrol-convert-nr_file_pmdmapped-account-to-pages.patch
mm-memcontrol-make-the-slab-calculation-consistent.patch
mm-hugetlb-add-return-eagain-for-dissolve_free_huge_page.patch