summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorOleg Nesterov <oleg@redhat.com>2014-01-21 15:49:04 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-21 16:19:43 -0800
commit5eaf1a9e233d61438377f57facb167f8208ba9fd (patch)
treec1455aa3d758ea5ebb5879f655b4e7ddf4079d94
parentc728852f5dd41ce34e7ce0a179cf28cd5f4dc301 (diff)
downloadlinux-stable-5eaf1a9e233d61438377f57facb167f8208ba9fd.tar.gz
linux-stable-5eaf1a9e233d61438377f57facb167f8208ba9fd.tar.bz2
linux-stable-5eaf1a9e233d61438377f57facb167f8208ba9fd.zip
mm: thp: turn compound_head() into BUG_ON(!PageTail) in get_huge_page_tail()
get_huge_page_tail()->compound_head() looks confusing. Every caller must check PageTail(page), otherwise atomic_inc(&page->_mapcount) is simply wrong if this page is compound-trans-head. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Dave Jones <davej@redhat.com> Cc: Darren Hart <dvhart@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Acked-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/mm.h7
1 files changed, 3 insertions, 4 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index f95c71b7c1fd..58202c26c559 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -445,13 +445,12 @@ static inline bool compound_tail_refcounted(struct page *page)
static inline void get_huge_page_tail(struct page *page)
{
/*
- * __split_huge_page_refcount() cannot run
- * from under us.
- * In turn no need of compound_trans_head here.
+ * __split_huge_page_refcount() cannot run from under us.
*/
+ VM_BUG_ON(!PageTail(page));
VM_BUG_ON(page_mapcount(page) < 0);
VM_BUG_ON(atomic_read(&page->_count) != 0);
- if (compound_tail_refcounted(compound_head(page)))
+ if (compound_tail_refcounted(page->first_page))
atomic_inc(&page->_mapcount);
}