Add PageZbud flag to page flags to distinguish pages allocated in zbud.
Currently these pages do not have any flags set.

Signed-off-by: Krzysztof Kozlowski <k.kozlow...@samsung.com>
---
 include/linux/page-flags.h |   12 ++++++++++++
 mm/page_alloc.c            |    3 +++
 mm/zbud.c                  |    4 ++++
 3 files changed, 19 insertions(+)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 6d53675..5b8b61a6 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -109,6 +109,12 @@ enum pageflags {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
        PG_compound_lock,
 #endif
+#ifdef CONFIG_ZBUD
+       /* Allocated by zbud. Flag is necessary to find zbud pages to unuse
+        * during migration/compaction.
+        */
+       PG_zbud,
+#endif
        __NR_PAGEFLAGS,
 
        /* Filesystems */
@@ -275,6 +281,12 @@ PAGEFLAG_FALSE(HWPoison)
 #define __PG_HWPOISON 0
 #endif
 
+#ifdef CONFIG_ZBUD
+PAGEFLAG(Zbud, zbud)
+#else
+PAGEFLAG_FALSE(Zbud)
+#endif
+
 u64 stable_page_flags(struct page *page);
 
 static inline int PageUptodate(struct page *page)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b100255..1a120fb 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6345,6 +6345,9 @@ static const struct trace_print_flags pageflag_names[] = {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
        {1UL << PG_compound_lock,       "compound_lock" },
 #endif
+#ifdef CONFIG_ZBUD
+       {1UL << PG_zbud,                "zbud"          },
+#endif
 };
 
 static void dump_page_flags(unsigned long flags)
diff --git a/mm/zbud.c b/mm/zbud.c
index a8e986f..a452949 100644
--- a/mm/zbud.c
+++ b/mm/zbud.c
@@ -230,7 +230,10 @@ static void get_zbud_page(struct zbud_header *zhdr)
 static int put_zbud_page(struct zbud_pool *pool, struct zbud_header *zhdr)
 {
        struct page *page = virt_to_page(zhdr);
+       BUG_ON(!PageZbud(page));
+
        if (put_page_testzero(page)) {
+               ClearPageZbud(page);
                free_hot_cold_page(page, 0);
                pool->pages_nr--;
                return 1;
@@ -341,6 +344,7 @@ int zbud_alloc(struct zbud_pool *pool, int size, gfp_t gfp,
         * don't increase the page count.
         */
        zhdr = init_zbud_page(page);
+       SetPageZbud(page);
        bud = FIRST;
 
 found:
-- 
1.7.9.5

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