THP migration can fail for a variety of reasons. Avoid flushing the TLB
to deal with THP migration races until the copy is ready to start.
Cc: sta...@vger.kernel.org
Signed-off-by: Mel Gorman <mgor...@suse.de>
---
mm/huge_memory.c | 7 -------
mm/migrate.c | 6 ++++++
2 files changed, 6 insertions(+), 7 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e3a5ee2..e3b6a75 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1377,13 +1377,6 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct
vm_area_struct *vma,
}
/*
- * The page_table_lock above provides a memory barrier
- * with change_protection_range.
- */
- if (tlb_flush_pending(mm))
- flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
-
- /*
* Migrate the THP to the requested node, returns with page unlocked
* and pmd_numa cleared.
*/
diff --git a/mm/migrate.c b/mm/migrate.c
index cfb4190..5372521 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1759,6 +1759,12 @@ int migrate_misplaced_transhuge_page(struct mm_struct
*mm,
goto out_fail;
}
+ /* PTL provides a memory barrier with change_protection_range */
+ ptl = pmd_lock(mm, pmd);
+ if (tlb_flush_pending(mm))
+ flush_tlb_range(vma, mmun_start, mmun_end);
+ spin_unlock(ptl);
+
/* Prepare a page as a migration target */
__set_page_locked(new_page);
SetPageSwapBacked(new_page);
--
1.8.4
--
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