Fix the error return value in kswapd_run().  The bug was introduced by
commit d5dc0ad9 ("mm/vmscan: fix error number for failed kthread").
Signed-off-by: NXishi Qiu <qiuxishi@huawei.com>
Reviewed-by: NWanpeng Li <liwanp@linux.vnet.ibm.com>
Reviewed-by: NRik van Riel <riel@redhat.com>
Reported-by: NWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>