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Commit 0c56010c authored by Matias Bjorling's avatar Matias Bjorling Committed by Jens Axboe
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null_blk: mem garbage on NUMA systems during init 



For NUMA systems, initializing the blk-mq layer and using per node hctx.
We initialize submit queues to 1, while blk-mq nr_hw_queues is
initialized to the number of NUMA nodes.

This makes the null_init_hctx function overwrite memory outside of what
it allocated.  In my case it lead to writing garbage into struct
request_queue's mq_map.

Signed-off-by: default avatarMatias Bjorling <m@bjorling.me>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a26ba7fa

drivers/block/null_blk.c

+4 −4
Original line number Diff line number Diff line
@@ -495,23 +495,23 @@ static int null_add_dev(void) 


	spin_lock_init(&nullb->lock);



	if (queue_mode == NULL_Q_MQ && use_per_node_hctx)

		submit_queues = nr_online_nodes;



	if (setup_queues(nullb))

		goto err;



	if (queue_mode == NULL_Q_MQ) {

		null_mq_reg.numa_node = home_node;

		null_mq_reg.queue_depth = hw_queue_depth;

		null_mq_reg.nr_hw_queues = submit_queues;



		if (use_per_node_hctx) {

			null_mq_reg.ops->alloc_hctx = null_alloc_hctx;

			null_mq_reg.ops->free_hctx = null_free_hctx;



			null_mq_reg.nr_hw_queues = nr_online_nodes;

		} else {

			null_mq_reg.ops->alloc_hctx = blk_mq_alloc_single_hw_queue;

			null_mq_reg.ops->free_hctx = blk_mq_free_single_hw_queue;



			null_mq_reg.nr_hw_queues = submit_queues;

		}



		nullb->q = blk_mq_init_queue(&null_mq_reg, nullb);