khugepaged: ignore pmd tables with THP mapped with ptes
authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Sat, 16 Jan 2016 00:52:39 +0000 (16:52 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 16 Jan 2016 01:56:32 +0000 (17:56 -0800)
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>
include/trace/events/huge_memory.h
mm/huge_memory.c

index 97d635cabac8d5e389cfaa331c39a92e1f23f0c6..0f803d2783e3834194cb3f5cd3dd4da5c017304c 100644 (file)
@@ -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")             \
index b3cc9f27a0ee6c535397676cd2d09c3ffa1ea0cc..f4da89cef2cd82595aa9bb2b2ed517aeb3c597e9 100644 (file)
@@ -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;