The patch titled
Subject: kpageflags: fix wrong KPF_THP on non-huge compound pages
has been added to the -mm tree. Its filename is
kpageflags-fix-wrong-kpf_thp-on-non-huge-compound-pages.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Naoya Horiguchi <[email protected]>
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]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
fs/proc/page.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff -puN
fs/proc/page.c~kpageflags-fix-wrong-kpf_thp-on-non-huge-compound-pages
fs/proc/page.c
--- a/fs/proc/page.c~kpageflags-fix-wrong-kpf_thp-on-non-huge-compound-pages
+++ a/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 -mm which might be from [email protected] are
kpageflags-fix-wrong-kpf_thp-on-non-huge-compound-pages.patch
--
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
