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SubjectRe: [PATCH] null_blk: mem garbage on NUMA systems during init
From
Jens, ping?

Patch looks fine, and it looks completely bogus to set

null_mq_reg.nr_hw_queues

to 'nr_online_nodes', when we've potentially done "setup_queues()"
with just a single queue.

So I'm going to apply this as-is, I'm just wondering why I haven't
heard anything from you..

Linus


On Tue, Dec 10, 2013 at 7:50 AM, Matias Bjorling <m@bjorling.me> wrote:
> 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: Matias Bjorling <m@bjorling.me>
> ---
> drivers/block/null_blk.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
> index ea192ec..f370fc1 100644
> --- a/drivers/block/null_blk.c
> +++ b/drivers/block/null_blk.c
> @@ -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);
> --
> 1.8.3.2
>
> --
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