Hi Mike,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on next-20211007]
[cannot apply to mst-vhost/linux-next vgupta-arc/for-next arm64/for-next/core uclinux-h8/h8300-next geert-m68k/for-next openrisc/for-next deller-parisc/for-next powerpc/next s390/features linus/master v5.15-rc4 v5.15-rc3 v5.15-rc2 v5.15-rc4]
[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/Use-copy_process-create_io_thread-in-vhost-layer/20211008-093610
base:    f8dc23b3dc0cc5b32dfd0c446e59377736d073a7
config: arc-randconfig-r043-20211007 (attached as .config)
compiler: arc-elf-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/19238ec927cb55bbd6fd6bdf64bac6a99f457b8c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Mike-Christie/Use-copy_process-create_io_thread-in-vhost-layer/20211008-093610
        git checkout 19238ec927cb55bbd6fd6bdf64bac6a99f457b8c
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=arc 

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

All warnings (new ones prefixed by >>):

   kernel/fork.c:161:13: warning: no previous prototype for 'arch_release_task_struct' [-Wmissing-prototypes]
     161 | void __weak arch_release_task_struct(struct task_struct *tsk)
         |             ^~~~~~~~~~~~~~~~~~~~~~~~
   kernel/fork.c:814:20: warning: no previous prototype for 'arch_task_cache_init' [-Wmissing-prototypes]
     814 | void __init __weak arch_task_cache_init(void) { }
         |                    ^~~~~~~~~~~~~~~~~~~~
   kernel/fork.c:909:12: warning: no previous prototype for 'arch_dup_task_struct' [-Wmissing-prototypes]
     909 | int __weak arch_dup_task_struct(struct task_struct *dst,
         |            ^~~~~~~~~~~~~~~~~~~~

quoted

kernel/fork.c:2581:21: warning: no previous prototype for 'create_io_thread' [-Wmissing-prototypes]

    2581 | struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
         |                     ^~~~~~~~~~~~~~~~
   In file included from include/linux/perf_event.h:25,
                    from include/linux/trace_events.h:10,
                    from include/trace/syscall.h:7,
                    from include/linux/syscalls.h:87,
                    from kernel/fork.c:54:
   arch/arc/include/asm/perf_event.h:126:27: warning: 'arc_pmu_cache_map' defined but not used [-Wunused-const-variable=]
     126 | static const unsigned int arc_pmu_cache_map[C(MAX)][C(OP_MAX)][C(RESULT_MAX)] = {
         |                           ^~~~~~~~~~~~~~~~~
   arch/arc/include/asm/perf_event.h:91:27: warning: 'arc_pmu_ev_hw_map' defined but not used [-Wunused-const-variable=]
      91 | static const char * const arc_pmu_ev_hw_map[] = {
         |                           ^~~~~~~~~~~~~~~~~


vim +/create_io_thread +2581 kernel/fork.c

13585fa0668c72 Nadav Amit    2019-04-25  2574  
cc440e8738e5c8 Jens Axboe    2021-03-04  2575  /*
cc440e8738e5c8 Jens Axboe    2021-03-04  2576   * This is like kernel_clone(), but shaved down and tailored to just
cc440e8738e5c8 Jens Axboe    2021-03-04  2577   * creating io_uring workers. It returns a created task, or an error pointer.
cc440e8738e5c8 Jens Axboe    2021-03-04  2578   * The returned task is inactive, and the caller must fire it up through
cc440e8738e5c8 Jens Axboe    2021-03-04  2579   * wake_up_new_task(p). All signals are blocked in the created task.
cc440e8738e5c8 Jens Axboe    2021-03-04  2580   */
cc440e8738e5c8 Jens Axboe    2021-03-04 @2581  struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
cc440e8738e5c8 Jens Axboe    2021-03-04  2582  {
cc440e8738e5c8 Jens Axboe    2021-03-04  2583  	unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
cc440e8738e5c8 Jens Axboe    2021-03-04  2584  				CLONE_IO;
cc440e8738e5c8 Jens Axboe    2021-03-04  2585  	struct kernel_clone_args args = {
cc440e8738e5c8 Jens Axboe    2021-03-04  2586  		.flags		= ((lower_32_bits(flags) | CLONE_VM |
cc440e8738e5c8 Jens Axboe    2021-03-04  2587  				    CLONE_UNTRACED) & ~CSIGNAL),
cc440e8738e5c8 Jens Axboe    2021-03-04  2588  		.exit_signal	= (lower_32_bits(flags) & CSIGNAL),
cc440e8738e5c8 Jens Axboe    2021-03-04  2589  		.stack		= (unsigned long)fn,
cc440e8738e5c8 Jens Axboe    2021-03-04  2590  		.stack_size	= (unsigned long)arg,
3f1f508b402889 Mike Christie 2021-10-07  2591  		.worker_flags	= KERN_WORKER_IO | KERN_WORKER_USER,
cc440e8738e5c8 Jens Axboe    2021-03-04  2592  	};
cc440e8738e5c8 Jens Axboe    2021-03-04  2593  
b16b3855d89fba Jens Axboe    2021-03-26  2594  	return copy_process(NULL, 0, node, &args);
cc440e8738e5c8 Jens Axboe    2021-03-04  2595  }
cc440e8738e5c8 Jens Axboe    2021-03-04  2596  

---
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