khugepaged: ignore pmd tables with THP mapped with ptes

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 <[email protected]>
Tested-by: Sasha Levin <[email protected]>
Tested-by: Aneesh Kumar K.V <[email protected]>
Acked-by: Jerome Marchand <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Steve Capper <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h
index 97d635cabac8d5e389cfaa331c39a92e1f23f0c6..0f803d2783e3834194cb3f5cd3dd4da5c017304c 100644 (file)
--- a/include/trace/events/huge_memory.h
+++ b/include/trace/events/huge_memory.h
@@ -22,6 +22,7 @@
        EM( SCAN_PAGE_LRU,              "page_not_in_lru")              \
        EM( SCAN_PAGE_LOCK,             "page_locked")                  \
        EM( SCAN_PAGE_ANON,             "page_not_anon")                \
+       EM( SCAN_PAGE_COMPOUND,         "page_compound")                \
        EM( SCAN_ANY_PROCESS,           "no_process_for_page")          \
        EM( SCAN_VMA_NULL,              "vma_null")                     \
        EM( SCAN_VMA_CHECK,             "vma_check_failed")             \

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b3cc9f27a0ee6c535397676cd2d09c3ffa1ea0cc..f4da89cef2cd82595aa9bb2b2ed517aeb3c597e9 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -45,6 +45,7 @@ enum scan_result {
        SCAN_PAGE_LRU,
        SCAN_PAGE_LOCK,
        SCAN_PAGE_ANON,
+       SCAN_PAGE_COMPOUND,
        SCAN_ANY_PROCESS,
        SCAN_VMA_NULL,
        SCAN_VMA_CHECK,
@@ -2770,6 +2771,13 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
                        result = SCAN_PAGE_NULL;
                        goto out_unmap;
                }
+
+               /* TODO: teach khugepaged to collapse THP mapped with pte */
+               if (PageCompound(page)) {
+                       result = SCAN_PAGE_COMPOUND;
+                       goto out_unmap;
+               }
+
                /*
                 * Record which node the original page is from and save this
                 * information to khugepaged_node_load[].
@@ -2782,7 +2790,6 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
                        goto out_unmap;
                }
                khugepaged_node_load[node]++;
-               VM_BUG_ON_PAGE(PageCompound(page), page);
                if (!PageLRU(page)) {
                        result = SCAN_SCAN_ABORT;
                        goto out_unmap;