This is a note to let you know that I've just added the patch titled
kpageflags: fix wrong KPF_THP on non-huge compound pages
to the 3.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kpageflags-fix-wrong-kpf_thp-on-non-huge-compound-pages.patch
and it can be found in the queue-3.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 7a71932d5676b7410ab64d149bad8bde6b0d8632 Mon Sep 17 00:00:00 2001
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
From: Naoya Horiguchi <[email protected]>
commit 7a71932d5676b7410ab64d149bad8bde6b0d8632 upstream.
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]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/proc/page.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- 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;
/*
Patches currently in stable-queue which might be from [email protected]
are
queue-3.6/kpageflags-fix-wrong-kpf_thp-on-non-huge-compound-pages.patch
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