On kernels from v2.6.18 to v2.6.37, buddy page is marked by the
PG_buddy flag.

  kernel version     | PG_buddy
  ------------------ +---------------------------------
  v2.6.17 to v2.6.26 | 19
  v2.6.27 to v2.6.37 | 19 if CONFIG_PAGEFLAGS_EXTEND=y
                     | 18 otherwise

We don't need to care about CONFIG_PAGEFLAGS_EXTEND because the
architectures specifying this as y are um and xtensa only. They are
not included in the supported architectures of makedumpfile.

Signed-off-by: HATAYAMA Daisuke <d.hatay...@jp.fujitsu.com>
---

 makedumpfile.c |   24 ++++++++++++++++++++----
 1 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index 7b13dca..4e5d4d3 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -3669,6 +3669,19 @@ exclude_free_page(void)
 }
 
 /*
+ * For the kernel versions from v2.6.17 to v2.6.37.
+ */
+static int
+page_is_buddy_v2(unsigned long flags, unsigned int _mapcount,
+                       unsigned long private, unsigned int _count)
+{
+       if (flags & (1UL << NUMBER(PG_buddy)))
+               return TRUE;
+
+       return FALSE;
+}
+
+/*
  * For v2.6.38 and later kernel versions.
  */
 static int
@@ -3690,10 +3703,13 @@ setup_page_is_buddy(void)
        if (OFFSET(page.private) == NOT_FOUND_STRUCTURE)
                goto out;
 
-       if (NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE) != NOT_FOUND_NUMBER) {
-               if (OFFSET(page._mapcount) != NOT_FOUND_STRUCTURE)
-                       info->page_is_buddy = page_is_buddy_v3;
-       }
+       if (NUMBER(PG_buddy) == NOT_FOUND_NUMBER) {
+               if (NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE) != NOT_FOUND_NUMBER) {
+                       if (OFFSET(page._mapcount) != NOT_FOUND_STRUCTURE)
+                               info->page_is_buddy = page_is_buddy_v3;
+               }
+       } else
+               info->page_is_buddy = page_is_buddy_v2;
 
 out:
        if (!info->page_is_buddy)


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