mm: reinstante dropped pmd_trans_splitting() check

The check for a pmd being in the process of being split was dropped by
mistake by commit d10e63f29488 ("mm: numa: Create basic numa page
hinting infrastructure"). Put it back.

Reported-by: Dave Jones <[email protected]>
Debugged-by: Hillf Danton <[email protected]>
Acked-by: Andrea Arcangeli <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Cc: Kirill Shutemov <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 8 insertions, 0 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 49fb1cf08611..bb1369f7b9b4 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3711,6 +3711,14 @@ retry:
 		if (pmd_trans_huge(orig_pmd)) {
 			unsigned int dirty = flags & FAULT_FLAG_WRITE;
 
+			/*
+			 * If the pmd is splitting, return and retry the
+			 * the fault.  Alternative: wait until the split
+			 * is done, and goto retry.
+			 */
+			if (pmd_trans_splitting(orig_pmd))
+				return 0;
+
 			if (pmd_numa(orig_pmd))
 				return do_huge_pmd_numa_page(mm, vma, address,
 							     orig_pmd, pmd);