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SubjectRe: [PATCH] workqueue: Fix possible memory leaks in wq_numa_init()
Please ignore my previous email which included/copied a wrong line of code.

On Thu, Jul 22, 2021 at 12:23 AM Tejun Heo <tj@kernel.org> wrote:
> Yeah, idk. It's not an actual bug tho. Maybe we should just add a comment.
> Which version do you like the best?

I hope Zhen Lei continues to refine his version. I think he is still
working on it.

On Mon, Jul 19, 2021 at 3:00 PM Zhen Lei <thunder.leizhen@huawei.com> wrote:
>
> In error handling branch "if (WARN_ON(node == NUMA_NO_NODE))", the
> previously allocated memories are not released. Doing this before
> allocating memory eliminates memory leaks.
>
> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> ---
> kernel/workqueue.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 50142fc08902..6aa0ba582d15 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -5896,6 +5896,14 @@ static void __init wq_numa_init(void)
> return;
> }
>
> + for_each_possible_cpu(cpu) {
> + if (WARN_ON(cpu_to_node(cpu) == NUMA_NO_NODE)) {
> + pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu);


> + /* happens iff arch is bonkers, let's just proceed */

I don't think this comment is still needed.

> + return;
> + }
> + }
> +
> wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs();
> BUG_ON(!wq_update_unbound_numa_attrs_buf);
>
> @@ -5907,18 +5915,11 @@ static void __init wq_numa_init(void)
> tbl = kcalloc(nr_node_ids, sizeof(tbl[0]), GFP_KERNEL);
> BUG_ON(!tbl);
>
> - for_each_node(node)
> + for_each_node(node) {
> BUG_ON(!zalloc_cpumask_var_node(&tbl[node], GFP_KERNEL,
> node_online(node) ? node : NUMA_NO_NODE));
>
> - for_each_possible_cpu(cpu) {
> - node = cpu_to_node(cpu);
> - if (WARN_ON(node == NUMA_NO_NODE)) {
> - pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu);
> - /* happens iff arch is bonkers, let's just proceed */
> - return;
> - }
> - cpumask_set_cpu(cpu, tbl[node]);
> + cpumask_copy(tbl[node], cpumask_of_node(node));

It is incorrect. cpumask_of_node(node) is the online cpumask of the node, not
the possible cpumask of the node that we are interested in.

If the NUMA subsystem provided something like cpumask_possible_of_node(node),
we wouldn't need wq_numa_possible_cpumask.

Please keep "for_each_possible_cpu(cpu)" loop and
"cpumask_set_cpu(cpu, tbl[node]);"

> }
>
> wq_numa_possible_cpumask = tbl;
> --
> 2.25.1
>

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