commit: 7a71932d5676b7410ab64d149bad8bde6b0d8632 From: Naoya Horiguchi <[email protected]> Date: Mon, 8 Oct 2012 16:33:47 -0700 Subject: 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 <[email protected]> Acked-by: KOSAKI Motohiro <[email protected]> Acked-by: David Rientjes <[email protected]> Reviewed-by: Fengguang Wu <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> --- fs/proc/page.c | 8 +++++++- 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; /* -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
