mm/migrate: correct failure handling if !hugepage_migration_support()

We should remove the page from the list if we fail with ENOSYS, since
migrate_pages() consider error cases except -ENOMEM and -EAGAIN as
permanent failure and it assumes that the page would be removed from the
list.  Without this patch, we could overcount number of failure.

In addition, we should put back the new hugepage if
!hugepage_migration_support().  If not, we would leak hugepage memory.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/migrate.c b/mm/migrate.c
index 626ca3c5d07b874428047d9555d4fee5c3435d51..13bedcc4656b32805c36c5e6b56c55067d2c964b 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1013,7 +1013,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 {
        int rc = 0;
        int *result = NULL;
-       struct page *new_hpage = get_new_page(hpage, private, &result);
+       struct page *new_hpage;
        struct anon_vma *anon_vma = NULL;
 
        /*
@@ -1023,9 +1023,12 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
         * tables or check whether the hugepage is pmd-based or not before
         * kicking migration.
         */
-       if (!hugepage_migration_support(page_hstate(hpage)))
+       if (!hugepage_migration_support(page_hstate(hpage))) {
+               putback_active_hugepage(hpage);
                return -ENOSYS;
+       }
 
+       new_hpage = get_new_page(hpage, private, &result);
        if (!new_hpage)
                return -ENOMEM;