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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2012-10-08 16:33:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-09 16:23:00 +0900
commit7a71932d5676b7410ab64d149bad8bde6b0d8632 (patch)
treebbe2b908dfcc7f5f8924e9cfc0fe0a49501d9a28
parentcd8ed2a45a401cb692d769e92de7d73aa42fabce (diff)
downloadop-kernel-dev-7a71932d5676b7410ab64d149bad8bde6b0d8632.zip
op-kernel-dev-7a71932d5676b7410ab64d149bad8bde6b0d8632.tar.gz
kpageflags: fix wrong KPF_THP on non-huge compound pages
KPF_THP can be set on non-huge compound pages (like slab pages or pages allocated by drivers with __GFP_COMP) because PageTransCompound only checks PG_head and PG_tail. Obviously this is a bug and breaks user space applications which look for thp via /proc/kpageflags. This patch rules out setting KPF_THP wrongly by additionally checking PageLRU on the head pages. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Fengguang Wu <fengguang.wu@intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/proc/page.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 7fcd0d6..b8730d9 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -115,7 +115,13 @@ u64 stable_page_flags(struct page *page)
u |= 1 << KPF_COMPOUND_TAIL;
if (PageHuge(page))
u |= 1 << KPF_HUGE;
- else if (PageTransCompound(page))
+ /*
+ * PageTransCompound can be true for non-huge compound pages (slab
+ * pages or pages allocated by drivers with __GFP_COMP) because it
+ * just checks PG_head/PG_tail, so we need to check PageLRU to make
+ * sure a given page is a thp, not a non-huge compound page.
+ */
+ else if (PageTransCompound(page) && PageLRU(compound_trans_head(page)))
u |= 1 << KPF_THP;
/*
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