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 <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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;