mm/hugetlb.c: avoid double unlock_page() in hugetlb_fault()
Have hugetlb_fault() call unlock_page(page) only if it had previously
called lock_page(page).
Setting CONFIG_DEBUG_VM=y and then running the libhugetlbfs test suite,
resulted in the tripping of VM_BUG_ON(!PageLocked(page)) in
unlock_page() having been called by hugetlb_fault() when page ==
pagecache_page. This patch remedied the problem.
Signed-off-by: Dean Nelson <dnelson@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index c4a3558..8585524 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2738,7 +2738,8 @@
unlock_page(pagecache_page);
put_page(pagecache_page);
}
- unlock_page(page);
+ if (page != pagecache_page)
+ unlock_page(page);
out_mutex:
mutex_unlock(&hugetlb_instantiation_mutex);