From: ZhangXiaoxu zhangxiaoxu5@huawei.com
The upstram commit 65d8fc777f6d ("futex: Remove requirement for lock_page() in get_futex_key()") use variable 'page' as the page head, when merge it to stable branch, the variable `page_head` is page head.
In the stable branch, the variable `page` not means the page head, when lock the page head, we should lock 'page_head', rather than 'page'.
It maybe lead a hung task problem.
Signed-off-by: ZhangXiaoxu zhangxiaoxu5@huawei.com Cc: stable@vger.kernel.org Cc: Thomas Gleixner tglx@linutronix.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/futex.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/futex.c +++ b/kernel/futex.c @@ -593,8 +593,8 @@ again: * applies. If this is really a shmem page then the page lock * will prevent unexpected transitions. */ - lock_page(page); - shmem_swizzled = PageSwapCache(page) || page->mapping; + lock_page(page_head); + shmem_swizzled = PageSwapCache(page_head) || page_head->mapping; unlock_page(page_head); put_page(page_head);