Re: [PATCH] workqueue: Fix possible memory leaks in wq_numa_init()

From: Leizhen (ThunderTown)
Date: Thu Jul 22 2021 - 00:02:23 EST




On 2021/7/22 9:55, Lai Jiangshan wrote:
> On Mon, Jul 19, 2021 at 3:00 PM Zhen Lei <thunder.leizhen@xxxxxxxxxx> 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@xxxxxxxxxx>
>> ---
>> 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 */
>> + 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 "cpumask_copy(tbl[node], cpumask_of_node(node));" as before.

OK,thanks.

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