blk-mq: move the kdump check to blk_mq_alloc_tag_set

We call blk_mq_alloc_tag_set() first then blk_mq_init_queue(). The requests are
allocated in the former function. So the kdump check should be moved to there
to really save memory.

Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 27a347fe8f5b97ba12013f0aa711c60d710ae6f7..4854e709aa34caaaeade014c18a2ed488c9ff78a 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1804,16 +1804,6 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
        if (!ctx)
                return ERR_PTR(-ENOMEM);
 
-       /*
-        * If a crashdump is active, then we are potentially in a very
-        * memory constrained environment. Limit us to 1 queue and
-        * 64 tags to prevent using too much memory.
-        */
-       if (is_kdump_kernel()) {
-               set->nr_hw_queues = 1;
-               set->queue_depth = min(64U, set->queue_depth);
-       }
-
        hctxs = kmalloc_node(set->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
                        set->numa_node);
 
@@ -2070,6 +2060,16 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
                set->queue_depth = BLK_MQ_MAX_DEPTH;
        }
 
+       /*
+        * If a crashdump is active, then we are potentially in a very
+        * memory constrained environment. Limit us to 1 queue and
+        * 64 tags to prevent using too much memory.
+        */
+       if (is_kdump_kernel()) {
+               set->nr_hw_queues = 1;
+               set->queue_depth = min(64U, set->queue_depth);
+       }
+
        set->tags = kmalloc_node(set->nr_hw_queues *
                                 sizeof(struct blk_mq_tags *),
                                 GFP_KERNEL, set->numa_node);