quoted

This patch looks good to me.

Larry, does Hugh's patch survive your testing?

Like I said earlier, no.  However, I finally set up a reproducer that 
only takes a few seconds
on a large system and this totally fixes the problem:

------------------------------------------------------------------------------------------------------------------------- 

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index c36febb..cc023b8 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c

@@ -2151,7 +2151,7 @@ int copy_hugetlb_page_range(struct mm_struct 

*dst, struct mm_struct *src,
                        goto nomem;

                /* If the pagetables are shared don't copy or take 
references */
-               if (dst_pte == src_pte)
+               if (*(unsigned long *)dst_pte == *(unsigned long 
*)src_pte)
                        continue;

                spin_lock(&dst->page_table_lock);
--------------------------------------------------------------------------------------------------------------------------- 


When we compare what the src_pte & dst_pte point to instead of their 
addresses everything works,
I suspect there is a missing memory barrier somewhere ???

Larry