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

[Kirill A. Shutemov]

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@xxxxxxxxxxxxxxx>
Tested-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
Acked-by: Jerome Marchand <jmarchan@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
---
 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

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