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>

diff --git a/mm/memory.c b/mm/memory.c
index 49fb1cf0861172b2860538e7c48afa0279087794..bb1369f7b9b4ba8af51d90a40de8f522aa2470dc 100644 (file)
--- 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);