[PATCH 3/4] pagemap: export KPF_THP

[Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>]

This flag shows that a given pages is a subpage of transparent hugepage.
It helps us debug and test kernel by showing physical address of thp.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Nacked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>

Changes since v1:
  - remove unnecessary ifdefs
  - fix confusing patch description
---
 fs/proc/page.c                    |    2 ++
 include/linux/kernel-page-flags.h |    1 +
 2 files changed, 3 insertions(+), 0 deletions(-)

diff --git 3.2-rc5.orig/fs/proc/page.c 3.2-rc5/fs/proc/page.c
index 6d8e6a9..cb2dcea 100644
--- 3.2-rc5.orig/fs/proc/page.c
+++ 3.2-rc5/fs/proc/page.c
@@ -115,6 +115,8 @@ u64 stable_page_flags(struct page *page)
 		u |= 1 << KPF_COMPOUND_TAIL;
 	if (PageHuge(page))
 		u |= 1 << KPF_HUGE;
+	if (PageTransCompound(page))
+		u |= 1 << KPF_THP;
 
 	/*
 	 * Caveats on high order pages: page->_count will only be set
diff --git 3.2-rc5.orig/include/linux/kernel-page-flags.h 3.2-rc5/include/linux/kernel-page-flags.h
index bd92a89..26a6571 100644
--- 3.2-rc5.orig/include/linux/kernel-page-flags.h
+++ 3.2-rc5/include/linux/kernel-page-flags.h
@@ -30,6 +30,7 @@
 #define KPF_NOPAGE		20
 
 #define KPF_KSM			21
+#define KPF_THP			22
 
 /* kernel hacking assistances
  * WARNING: subject to change, never rely on them!
-- 
1.7.7.3

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