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 <davej@redhat.com>
Debugged-by: Hillf Danton <dhillf@gmail.com>
Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Kirill Shutemov <kirill@shutemov.name>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 49fb1cf0861..bb1369f7b9b 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);