[PATCH 10/25] mm/fbatch: remove several uses of mlock_drain_local()

Remove several uses of mlock_drain_local(): they were workarounds for
when that sequence of operations tended to leave folios in mlock_fbatch
with debilitating raised refcount (and no good if the task changed CPU).

Signed-off-by: Hugh Dickins <[email protected]>
---
 mm/huge_memory.c | 2 --
 mm/migrate.c     | 2 --
 mm/rmap.c        | 4 ----
 3 files changed, 8 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c7bd99592195..df6bf69a066b 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3568,8 +3568,6 @@ static bool __discard_anon_folio_pmd_locked(struct vm_area_struct *vma,
 	folio_remove_rmap_pmd(folio, pmd_page(orig_pmd), vma);
 	zap_deposited_table(mm, pmdp);
 	add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR);
-	if (vma->vm_flags & VM_LOCKED)
-		mlock_drain_local();
 	folio_put(folio);
 
 	return true;
diff --git a/mm/migrate.c b/mm/migrate.c
index 8aaafcea7bc1..6b71b2415d00 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -448,8 +448,6 @@ static bool remove_migration_pte(struct folio *folio,
 				folio_add_file_rmap_pte(folio, new, vma);
 			set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
 		}
-		if (READ_ONCE(vma->vm_flags) & VM_LOCKED)
-			mlock_drain_local();
 
 		trace_remove_migration_pte(pvmw.address, pte_val(pte),
 					   compound_order(new));
diff --git a/mm/rmap.c b/mm/rmap.c
index 1f72d279ba68..e76823ec4d5e 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -2390,8 +2390,6 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 		}
 finish_unmap:
 		folio_remove_rmap_ptes(folio, page, nr_pages, vma);
-		if (vma->vm_flags & VM_LOCKED)
-			mlock_drain_local();
 		folio_put_refs(folio, nr_pages);
 
 		/*
@@ -2765,8 +2763,6 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 			hugetlb_remove_rmap(folio);
 		else
 			folio_remove_rmap_pte(folio, subpage, vma);
-		if (vma->vm_flags & VM_LOCKED)
-			mlock_drain_local();
 		folio_put(folio);
 	}
 
-- 
2.51.0