linux-kernel - Re: [PATCH] workqueue: Fix rescuer task's name truncated

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Date: Mon, 13 May 2024 15:35:21 +0800
From: kernel test robot <lkp@...el.com>
To: Wenchao Hao <haowenchao2@...wei.com>, Tejun Heo <tj@...nel.org>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Aaron Tomlin <atomlin@...mlin.com>, linux-kernel@...r.kernel.org
Cc: oe-kbuild-all@...ts.linux.dev, Wenchao Hao <haowenchao22@...il.com>
Subject: Re: [PATCH] workqueue: Fix rescuer task's name truncated

Hi Wenchao,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tj-wq/for-next]
[also build test WARNING on linus/master v6.9 next-20240510]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Wenchao-Hao/workqueue-Fix-rescuer-task-s-name-truncated/20240513-110849
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git for-next
patch link:    https://lore.kernel.org/r/20240513030639.3772468-1-haowenchao2%40huawei.com
patch subject: [PATCH] workqueue: Fix rescuer task's name truncated
config: openrisc-allnoconfig (https://download.01.org/0day-ci/archive/20240513/202405131400.sEYZHYk2-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240513/202405131400.sEYZHYk2-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405131400.sEYZHYk2-lkp@intel.com/

All warnings (new ones prefixed by >>):

   kernel/workqueue.c: In function 'init_rescuer':
>> kernel/workqueue.c:5558:57: warning: '%s' directive output may be truncated writing up to 31 bytes into a region of size 24 [-Wformat-truncation=]
    5558 |         snprintf(rescuer->desc, sizeof(rescuer->desc), "%s", wq->name);
         |                                                         ^~
   kernel/workqueue.c:5558:9: note: 'snprintf' output between 1 and 32 bytes into a destination of size 24
    5558 |         snprintf(rescuer->desc, sizeof(rescuer->desc), "%s", wq->name);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +5558 kernel/workqueue.c

  5528	
  5529	/*
  5530	 * Workqueues which may be used during memory reclaim should have a rescuer
  5531	 * to guarantee forward progress.
  5532	 */
  5533	static int init_rescuer(struct workqueue_struct *wq)
  5534	{
  5535		struct worker *rescuer;
  5536		int ret;
  5537	
  5538		if (!(wq->flags & WQ_MEM_RECLAIM))
  5539			return 0;
  5540	
  5541		rescuer = alloc_worker(NUMA_NO_NODE);
  5542		if (!rescuer) {
  5543			pr_err("workqueue: Failed to allocate a rescuer for wq \"%s\"\n",
  5544			       wq->name);
  5545			return -ENOMEM;
  5546		}
  5547	
  5548		rescuer->rescue_wq = wq;
  5549		rescuer->task = kthread_create(rescuer_thread, rescuer, "kworker/R");
  5550		if (IS_ERR(rescuer->task)) {
  5551			ret = PTR_ERR(rescuer->task);
  5552			pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe",
  5553			       wq->name, ERR_PTR(ret));
  5554			kfree(rescuer);
  5555			return ret;
  5556		}
  5557	
> 5558		snprintf(rescuer->desc, sizeof(rescuer->desc), "%s", wq->name);
  5559	
  5560		wq->rescuer = rescuer;
  5561		if (wq->flags & WQ_UNBOUND)
  5562			kthread_bind_mask(rescuer->task, wq_unbound_cpumask);
  5563		else
  5564			kthread_bind_mask(rescuer->task, cpu_possible_mask);
  5565		wake_up_process(rescuer->task);
  5566	
  5567		return 0;
  5568	}
  5569	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki