Re: [PATCH 2/2] io_uring: introduce IORING_OP_MMAP

[Gabriel Krisman Bertazi <krisman@suse.de>]

kernel test robot <lkp@intel.com> writes:

> Hi Gabriel,
>
> kernel test robot noticed the following build warnings:
>
> [auto build test WARNING on v6.19-rc7]
> [also build test WARNING on linus/master]
> [cannot apply to axboe/for-next next-20260129]
> [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/Gabriel-Krisman-Bertazi/io_uring-Support-commands-with-optional-file-descriptors/20260130-061445
> base:   v6.19-rc7
> patch link:    https://lore.kernel.org/r/20260129221138.897715-3-krisman%40suse.de
> patch subject: [PATCH 2/2] io_uring: introduce IORING_OP_MMAP
> config: m68k-randconfig-r122-20260130 (https://download.01.org/0day-ci/archive/20260130/202601301341.PTetVieu-lkp@intel.com/config)
> compiler: m68k-linux-gcc (GCC) 8.5.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260130/202601301341.PTetVieu-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@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202601301341.PTetVieu-lkp@intel.com/
>
> sparse warnings: (new ones prefixed by >>)
>>> io_uring/mmap.c:116:36: sparse: sparse: incorrect type in assignment (different address spaces) @@     expected void [noderef] __user *addr @@     got void * @@
>    io_uring/mmap.c:116:36: sparse:     expected void [noderef] __user *addr
>    io_uring/mmap.c:116:36: sparse:     got void *
>    io_uring/mmap.c:125:44: sparse: sparse: incorrect type in assignment (different address spaces) @@     expected void [noderef] __user *addr @@     got void * @@
>    io_uring/mmap.c:125:44: sparse:     expected void [noderef] __user *addr
>    io_uring/mmap.c:125:44: sparse:     got void *
>    io_uring/mmap.c:130:28: sparse: sparse: incorrect type in assignment (different address spaces) @@     expected void [noderef] __user *addr @@     got void * @@
>    io_uring/mmap.c:130:28: sparse:     expected void [noderef] __user *addr
>    io_uring/mmap.c:130:28: sparse:     got void *

FWIW, for reviewers, these are false positives.  The issue is I'm using
"void* __user addr" to either return a pointer or the error code to
user.  It is properly copied back through copy_to_user, but sparse still
complains.  I'll look into silencing it.

-- 
Gabriel Krisman Bertazi