coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping [PATCH v4 1/3]: Backporting of commit 04f5866e41fb70690e28397487d8bd8eea7d712a upstream. [PATCH v4 2/3]: Extension of commit 04f5866e41fb to fix the race condition between get_task_mm() and core dumping for IB->mlx4 and IB->mlx5 drivers. [PATCH v4 3/3] Backporting of commit 59ea6d06cfa9247b586a695c21f94afa7183af74 upstream. [diff from v3]: - added [PATCH v4 3/3]