null_blk: prevent crash from bad home_node value

At module load, if the selected home_node value is greater than
the available numa nodes, the system will crash in
__alloc_pages_nodemask() due to a bad paging request.  Prevent this
user error crash by detecting the bad value, logging an error, and
setting g_home_node back to the default of NUMA_NO_NODE.

Signed-off-by: John Pittman <jpittman@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
index 417a9f15c11631cae518a9924c0e480fd6b85fd2..d7ac09c092f2ac8a5caf8632dca569b38b9472a6 100644 (file)
--- a/drivers/block/null_blk_main.c
+++ b/drivers/block/null_blk_main.c
@@ -1748,6 +1748,11 @@ static int __init null_init(void)
                return -EINVAL;
        }
 
+       if (g_home_node != NUMA_NO_NODE && g_home_node >= nr_online_nodes) {
+               pr_err("null_blk: invalid home_node value\n");
+               g_home_node = NUMA_NO_NODE;
+       }
+
        if (g_queue_mode == NULL_Q_RQ) {
                pr_err("null_blk: legacy IO path no longer available\n");
                return -EINVAL;