[PATCH] pagemap: fix wrong KPF_THP on slab pages

[Naoya Horiguchi]

KPF_THP can be set on non-huge compound pages like slab pages, because
PageTransCompound only sees PG_head and PG_tail. Obviously this is a bug
and breaks user space applications which look for thp via /proc/kpageflags.
Currently thp is constructed only on anonymous pages, so this patch makes
KPF_THP be set when both of PageAnon and PageTransCompound are true.

Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
---
 fs/proc/page.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git v3.6-rc6.orig/fs/proc/page.c v3.6-rc6/fs/proc/page.c
index 7fcd0d6..613102d 100644
--- v3.6-rc6.orig/fs/proc/page.c
+++ v3.6-rc6/fs/proc/page.c
@@ -115,7 +115,7 @@ u64 stable_page_flags(struct page *page)
 		u |= 1 << KPF_COMPOUND_TAIL;
 	if (PageHuge(page))
 		u |= 1 << KPF_HUGE;
-	else if (PageTransCompound(page))
+	else if (PageTransCompound(page) && PageAnon(page))
 		u |= 1 << KPF_THP;
 
 	/*
-- 
1.7.11.4

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