tree: git://git.infradead.org/users/hch/misc.git dma_alloc_pages head: ebfa77e612f8650cb120011030b7a9e951ebee56 commit: ebfa77e612f8650cb120011030b7a9e951ebee56 [17/17] dma-mapping: replace DMA_ATTR_NON_CONSISTENT with dma_{alloc,free}_pages config: powerpc-randconfig-r021-20200817 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project de71b46a519db014ce906a39f8a0e1b235ef1568) 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 # install powerpc cross compiling tool for clang build # apt-get install binutils-powerpc-linux-gnu git checkout ebfa77e612f8650cb120011030b7a9e951ebee56 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All error/warnings (new ones prefixed by >>): page = dma_alloc_contiguous(dev, size, gfp | __GFP_ZERO); ^ page = dma_alloc_contiguous(dev, size, gfp | __GFP_ZERO); ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ dma_free_contiguous(dev, page, size); ^ kernel/dma/mapping.c:518:3: note: did you mean 'dma_alloc_contiguous'? kernel/dma/mapping.c:512:9: note: 'dma_alloc_contiguous' declared here page = dma_alloc_contiguous(dev, size, gfp | __GFP_ZERO); ^ else if (ops->alloc_pages) ^~~~~~~~~~~~~~~~ kernel/dma/mapping.c:545:9: note: uninitialized use occurs here return vaddr; ^~~~~ kernel/dma/mapping.c:540:7: note: remove the 'if' if its condition is always true else if (ops->alloc_pages) ^~~~~~~~~~~~~~~~~~~~~ kernel/dma/mapping.c:529:13: note: initialize the variable 'vaddr' to silence this warning void *vaddr; ^ = NULL kernel/dma/mapping.c:554:2: error: implicit declaration of function 'dma_free_contiguous' [-Werror,-Wimplicit-function-declaration] dma_free_contiguous(dev, virt_to_page(vaddr), size); ^ 2 warnings and 3 errors generated. git remote add hch-misc git://git.infradead.org/users/hch/misc.git git fetch --no-tags hch-misc dma_alloc_pages git checkout ebfa77e612f8650cb120011030b7a9e951ebee56 vim +/dma_alloc_contiguous +512 kernel/dma/mapping.c 506 507 static void *dma_simple_alloc_pages(struct device *dev, size_t size, 508 dma_addr_t *dma_handle, gfp_t gfp) 509 { 510 struct page *page; 511 513 if (!page) 514 return NULL; 515 *dma_handle = dma_map_page_attrs(dev, page, 0, size, DMA_BIDIRECTIONAL, 516 DMA_ATTR_SKIP_CPU_SYNC); 517 if (dma_mapping_error(dev, *dma_handle)) { 519 return NULL; 520 } 521 522 return page_address(page); 523 } 524 525 void *dma_alloc_pages(struct device *dev, size_t size, dma_addr_t *dma_handle, 526 gfp_t gfp) 527 { 528 const struct dma_map_ops *ops = get_dma_ops(dev); 529 void *vaddr; 530 531 if (WARN_ON_ONCE(!dev->coherent_dma_mask)) 532 return NULL; 533 if (WARN_ON_ONCE(gfp & (__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM | 534 __GFP_COMP))) 535 return NULL; 536 537 size = PAGE_ALIGN(size); 538 if (dma_alloc_direct(dev, ops)) 539 vaddr = dma_direct_alloc_pages(dev, size, dma_handle, gfp); 541 vaddr = ops->alloc_pages(dev, size, dma_handle, gfp); 542 else 543 dma_simple_alloc_pages(dev, size, dma_handle, gfp); 544 545 return vaddr; 546 } 547 EXPORT_SYMBOL_GPL(dma_alloc_pages); 548 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org