/proc/kpageflags: return KPF_BUDDY for "tail" buddy pages

Currently /proc/kpageflags returns nothing for "tail" buddy pages, which
is inconvenient when grasping how free pages are distributed.  This
patch sets KPF_BUDDY for such pages.

With this patch:

  $ grep MemFree /proc/meminfo ; tools/vm/page-types -b buddy
  MemFree:         3134992 kB
               flags      page-count       MB  symbolic-flags                     long-symbolic-flags
  0x0000000000000400          779272     3044  __________B_______________________________ buddy
  0x0000000000000c00            4385       17  __________BM______________________________ buddy,mmap
               total          783657     3061

783657 pages is 3134628 kB (roughly consistent with the global counter,)
so it's OK.

[akpm@linux-foundation.org: update comment, per Naoya]
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 0 insertions, 5 deletions

diff --git a/mm/internal.h b/mm/internal.h
index ad9400d759c8..b95952c2faec 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -148,9 +148,6 @@ extern int __isolate_free_page(struct page *page, unsigned int order);
 extern void __free_pages_bootmem(struct page *page, unsigned long pfn,
                                         unsigned int order);
 extern void prep_compound_page(struct page *page, unsigned int order);
-#ifdef CONFIG_MEMORY_FAILURE
-extern bool is_free_buddy_page(struct page *page);
-#endif
 extern int user_min_free_kbytes;
 
 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c46b75d14b6f..c7332a4bc8db 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7152,7 +7152,6 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 }
 #endif
 
-#ifdef CONFIG_MEMORY_FAILURE
 bool is_free_buddy_page(struct page *page)
 {
         struct zone *zone = page_zone(page);
@@ -7171,4 +7170,3 @@ bool is_free_buddy_page(struct page *page)
 
         return order < MAX_ORDER;
 }
-#endif