On 07/26/2012 11:48 PM, Larry Woodman wrote:

Mel, did you see this???

Larry

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


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Reply via email to