From ae9a556165646942828021ec72492f6cc6684aa8 Mon Sep 17 00:00:00 2001 From: Naoya Horiguchi Date: Wed, 26 Sep 2012 11:32:55 +1000 Subject: [PATCH] pagemap: fix wrong KPF_THP on slab pages 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 Cc: Wu Fengguang Cc: Andi Kleen Acked-by: KOSAKI Motohiro Signed-off-by: Andrew Morton --- fs/proc/page.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/proc/page.c b/fs/proc/page.c index 7fcd0d60a968..f7cd2f6c0a58 100644 --- a/fs/proc/page.c +++ b/fs/proc/page.c @@ -115,7 +115,12 @@ u64 stable_page_flags(struct page *page) u |= 1 << KPF_COMPOUND_TAIL; if (PageHuge(page)) u |= 1 << KPF_HUGE; - else if (PageTransCompound(page)) + /* + * Since THP is relevant only for anonymous pages so far, we check it + * explicitly with PageAnon. Otherwise thp is confounded with non-huge + * compound pages like slab pages. + */ + else if (PageTransCompound(page) && PageAnon(page)) u |= 1 << KPF_THP; /* -- 2.39.5