Re: [PATCH RFC 4/4] mm: guest_memfd: Add ability for mmap'ing pages

[kernel test robot <lkp@intel.com>]

Hi Elliot,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build warnings:

[auto build test WARNING on 8400291e289ee6b2bf9779ff1c83a291501f017b]

url:    https://github.com/intel-lab-lkp/linux/commits/Elliot-Berman/mm-Introduce-guest_memfd/20240806-024238
base:   8400291e289ee6b2bf9779ff1c83a291501f017b
patch link:    https://lore.kernel.org/r/20240805-guest-memfd-lib-v1-4-e5a29a4ff5d7%40quicinc.com
patch subject: [PATCH RFC 4/4] mm: guest_memfd: Add ability for mmap'ing pages
config: x86_64-rhel-8.3-rust (https://download.01.org/0day-ci/archive/20240808/202408081018.maLT93SE-lkp@intel.com/config)
compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240808/202408081018.maLT93SE-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/202408081018.maLT93SE-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> mm/guest_memfd.c:115:16: warning: unused variable 'i' [-Wunused-variable]
     115 |         unsigned long i;
         |                       ^
   1 warning generated.


vim +/i +115 mm/guest_memfd.c

   111	
   112	int guest_memfd_make_inaccessible(struct file *file, struct folio *folio)
   113	{
   114		unsigned long gmem_flags = (unsigned long)file->private_data;
 > 115		unsigned long i;
   116		int r;
   117	
   118		unmap_mapping_folio(folio);
   119	
   120		/**
   121		 * We can't use the refcount. It might be elevated due to
   122		 * guest/vcpu trying to access same folio as another vcpu
   123		 * or because userspace is trying to access folio for same reason
   124		 *
   125		 * folio_lock serializes the transitions between (in)accessible
   126		 */
   127		if (folio_maybe_dma_pinned(folio))
   128			return -EBUSY;
   129	
   130		if (gmem_flags & GUEST_MEMFD_FLAG_NO_DIRECT_MAP) {
   131			r = guest_memfd_folio_private(folio);
   132			if (r)
   133				return r;
   134		}
   135	
   136		return 0;
   137	}
   138	

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