linux-kernel - Re: [PATCH 1/5] workqueue: fix memory leak in wq_numa

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Message-ID: <548E70C6.8020202@cn.fujitsu.com>
Date:	Mon, 15 Dec 2014 13:25:26 +0800
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	Tejun Heo <tj@...nel.org>
CC:	<linux-kernel@...r.kernel.org>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	"Gu, Zheng" <guz.fnst@...fujitsu.com>,
	tangchen <tangchen@...fujitsu.com>,
	Hiroyuki KAMEZAWA <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [PATCH 1/5] workqueue: fix memory leak in wq_numa_init()

On 12/13/2014 01:12 AM, Tejun Heo wrote:
> On Fri, Dec 12, 2014 at 06:19:51PM +0800, Lai Jiangshan wrote:
>> wq_numa_init() will quit directly on some bonkers cases without freeing the
>> memory.  Add the missing cleanup code.
>>
>> Cc: Tejun Heo <tj@...nel.org>
>> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
>> Cc: "Gu, Zheng" <guz.fnst@...fujitsu.com>
>> Cc: tangchen <tangchen@...fujitsu.com>
>> Cc: Hiroyuki KAMEZAWA <kamezawa.hiroyu@...fujitsu.com>
>> Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
>> ---
>>  kernel/workqueue.c |    3 +++
>>  1 files changed, 3 insertions(+), 0 deletions(-)
>>
>> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
>> index 09b685d..a6fd2b8 100644
>> --- a/kernel/workqueue.c
>> +++ b/kernel/workqueue.c
>> @@ -4811,6 +4811,9 @@ static void __init wq_numa_init(void)
>>  		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 */
>> +			for_each_node(node)
>> +				free_cpumask_var(tbl[node]);
>> +			kfree(tbl);
> 
> The comment right up there says that this happens if and only if the
> arch code is seriously broken and it's consciously skipping exception
> handling.  That's a condition where we might as well trigger BUG_ON().
> Just leave it alone.


cpu_to_node() can return NUMA_NO_NODE after system booted (when node offline) currently.
so I don't think it is seriously broken if cpu_to_node() returns NUMA_NO_NODE
when booting.

See:

static void unmap_cpu_on_node(pg_data_t *pgdat)
{
#ifdef CONFIG_ACPI_NUMA
	int cpu;

	for_each_possible_cpu(cpu)
		if (cpu_to_node(cpu) == pgdat->node_id)
			numa_clear_node(cpu);
#endif
}

> 
> Thanks.
> 

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