Re: [PATCH 3/3] vhost: pass kthread user to check RLIMIT_NPROC

[kernel test robot]

Hi Mike,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on vhost/linux-next]
[also build test WARNING on linux/master linus/master v5.13-rc7]
[cannot apply to next-20210623]
[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]

url:    https://github.com/0day-ci/linux/commits/Mike-Christie/kthread-pass-in-user-and-check-RLIMIT_NPROC/20210624-110925
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next
config: riscv-randconfig-s032-20210622 (attached as .config)
compiler: riscv64-linux-gcc (GCC) 9.3.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # apt-get install sparse
        # sparse version: v0.6.3-341-g8af24329-dirty
        # https://github.com/0day-ci/linux/commit/daae0f4bb5ef7264d67cab20da37192754f885b8
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Mike-Christie/kthread-pass-in-user-and-check-RLIMIT_NPROC/20210624-110925
        git checkout daae0f4bb5ef7264d67cab20da37192754f885b8
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' W=1 ARCH=riscv 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>


sparse warnings: (new ones prefixed by >>)
>> drivers/vhost/vhost.c:599:57: sparse: sparse: dereference of noderef expression

vim +599 drivers/vhost/vhost.c

   581	
   582	/* Caller should have device mutex */
   583	long vhost_dev_set_owner(struct vhost_dev *dev)
   584	{
   585		struct task_struct *worker;
   586		int err;
   587	
   588		/* Is there an owner already? */
   589		if (vhost_dev_has_owner(dev)) {
   590			err = -EBUSY;
   591			goto err_mm;
   592		}
   593	
   594		vhost_attach_mm(dev);
   595	
   596		dev->kcov_handle = kcov_common_handle();
   597		if (dev->use_worker) {
   598			worker = kthread_create_for_user(vhost_worker, dev,
 > 599							 current->real_cred->user,
   600							 "vhost-%d", current->pid);
   601			if (IS_ERR(worker)) {
   602				err = PTR_ERR(worker);
   603				goto err_worker;
   604			}
   605	
   606			dev->worker = worker;
   607			wake_up_process(worker); /* avoid contributing to loadavg */
   608	
   609			err = vhost_attach_cgroups(dev);
   610			if (err)
   611				goto err_cgroup;
   612		}
   613	
   614		err = vhost_dev_alloc_iovecs(dev);
   615		if (err)
   616			goto err_cgroup;
   617	
   618		return 0;
   619	err_cgroup:
   620		if (dev->worker) {
   621			kthread_stop(dev->worker);
   622			dev->worker = NULL;
   623		}
   624	err_worker:
   625		vhost_detach_mm(dev);
   626		dev->kcov_handle = 0;
   627	err_mm:
   628		return err;
   629	}
   630	EXPORT_SYMBOL_GPL(vhost_dev_set_owner);
   631	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

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