[PATCHv6 08/36] khugepaged: ignore pmd tables with THP mapped with ptes

Kirill A. Shutemov
2015-06-03T17:16:32Z

Prepare khugepaged to see compound pages mapped with pte. For now we
won't collapse the pmd table with such pte.

khugepaged is subject for future rework wrt new refcounting.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
---
mm/huge_memory.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4ad975506c1b..a5423bee0109 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2680,6 +2680,11 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
page = vm_normal_page(vma, _address, pteval);
if (unlikely(!page))
goto out_unmap;
+
+ /* TODO: teach khugepaged to collapse THP mapped with pte */
+ if (PageCompound(page))
+ goto out_unmap;
+
/*
* Record which node the original page is from and save this
* information to khugepaged_node_load[].
@@ -2690,7 +2695,6 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
if (khugepaged_scan_abort(node))
goto out_unmap;
khugepaged_node_load[node]++;
- VM_BUG_ON_PAGE(PageCompound(page), page);
if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
goto out_unmap;
/*
--
2.1.4