Re: [PATCH 13/16] mm: update cramfs to use mmap_prepare, mmap_complete

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

Hi Lorenzo,

kernel test robot noticed the following build warnings:

[auto build test WARNING on akpm-mm/mm-everything]
[cannot apply to brauner-vfs/vfs.all char-misc/char-misc-testing char-misc/char-misc-next char-misc/char-misc-linus s390/features lwn/docs-next linus/master v6.17-rc5 next-20250909]
[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/Lorenzo-Stoakes/mm-shmem-update-shmem-to-use-mmap_prepare/20250908-191516
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/e2fb74b295b60bcb591aba5cc521cbe1b7901cd3.1757329751.git.lorenzo.stoakes%40oracle.com
patch subject: [PATCH 13/16] mm: update cramfs to use mmap_prepare, mmap_complete
config: arm64-randconfig-001-20250909 (https://download.01.org/0day-ci/archive/20250909/202509091758.mKPE6Hs0-lkp@intel.com/config)
compiler: clang version 16.0.6 (https://github.com/llvm/llvm-project 7cbf1a2591520c2491aa35339f227775f4d3adf6)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250909/202509091758.mKPE6Hs0-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/202509091758.mKPE6Hs0-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from fs/cramfs/inode.c:19:
   In file included from include/linux/pagemap.h:8:
   In file included from include/linux/mm.h:1096:
   include/linux/huge_mm.h:591:16: warning: unused variable 'folio' [-Wunused-variable]
           struct folio *folio = page_folio(page);
                         ^
   include/linux/huge_mm.h:598:16: warning: unused variable 'folio' [-Wunused-variable]
           struct folio *folio = page_folio(page);
                         ^
>> fs/cramfs/inode.c:358:38: warning: cast to smaller integer type 'enum cramfs_mmap_state' from 'const void *' [-Wvoid-pointer-to-enum-cast]
           enum cramfs_mmap_state mmap_state = (enum cramfs_mmap_state)context;
                                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   3 warnings generated.


vim +358 fs/cramfs/inode.c

   350	
   351	static int cramfs_physmem_mmap_complete(struct file *file, struct vm_area_struct *vma,
   352						const void *context)
   353	{
   354		struct inode *inode = file_inode(file);
   355		struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
   356		unsigned long address, pgoff = vma->vm_pgoff;
   357		unsigned int pages, offset;
 > 358		enum cramfs_mmap_state mmap_state = (enum cramfs_mmap_state)context;
   359		int ret = 0;
   360	
   361		if (mmap_state == NO_PREPOPULATE)
   362			return 0;
   363	
   364		offset = cramfs_get_block_range(inode, pgoff, &pages);
   365		address = sbi->linear_phys_addr + offset;
   366	
   367		/*
   368		 * Now try to pre-populate ptes for this vma with a direct
   369		 * mapping avoiding memory allocation when possible.
   370		 */
   371	
   372		if (mmap_state == PREPOPULATE_PFNMAP) {
   373			/*
   374			 * The entire vma is mappable. remap_pfn_range() will
   375			 * make it distinguishable from a non-direct mapping
   376			 * in /proc/<pid>/maps by substituting the file offset
   377			 * with the actual physical address.
   378			 */
   379			ret = remap_pfn_range_complete(vma, vma->vm_start, address >> PAGE_SHIFT,
   380					pages * PAGE_SIZE, vma->vm_page_prot);
   381		} else {
   382			/*
   383			 * Let's create a mixed map if we can't map it all.
   384			 * The normal paging machinery will take care of the
   385			 * unpopulated ptes via cramfs_read_folio().
   386			 */
   387			int i;
   388	
   389			for (i = 0; i < pages && !ret; i++) {
   390				vm_fault_t vmf;
   391				unsigned long off = i * PAGE_SIZE;
   392	
   393				vmf = vmf_insert_mixed(vma, vma->vm_start + off,
   394						address + off);
   395				if (vmf & VM_FAULT_ERROR)
   396					ret = vm_fault_to_errno(vmf, 0);
   397			}
   398		}
   399	
   400		if (!ret)
   401			pr_debug("mapped %pD[%lu] at 0x%08lx (%u/%lu pages) "
   402				 "to vma 0x%08lx, page_prot 0x%llx\n", file,
   403				 pgoff, address, pages, vma_pages(vma), vma->vm_start,
   404				 (unsigned long long)pgprot_val(vma->vm_page_prot));
   405		return ret;
   406	}
   407	

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