pagemap: export KPF_THP

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

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/page.c b/fs/proc/page.c
index 6d8e6a9e93aba59e471d32d4ee9dc59b2579d8c4..7fcd0d60a9680ae1eb4998633c51ea90e730209f 100644 (file)
--- a/fs/proc/page.c
+++ b/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;
+       else if (PageTransCompound(page))
+               u |= 1 << KPF_THP;
 
        /*
         * Caveats on high order pages: page->_count will only be set

diff --git a/include/linux/kernel-page-flags.h b/include/linux/kernel-page-flags.h
index bd92a89f4b0aa49cadcb6d320a8d2815ffd190c3..26a65711676f421dd1e287734ac4f781c713c8b0 100644 (file)
--- a/include/linux/kernel-page-flags.h
+++ b/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!