Hi Krzysztof, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 625d3449788f85569096780592549d0340e9c0c7 commit: e93a1695d7fb551376b1c1220a267d032b6ad159 iommu: Enable compile testing for some of drivers date: 4 months ago config: i386-randconfig-r012-20200622 (attached as .config) compiler: gcc-9 (Debian 9.3.0-13) 9.3.0 reproduce (this is a W=1 build): git checkout e93a1695d7fb551376b1c1220a267d032b6ad159 # save the attached .config to linux build tree make W=1 ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): drivers/iommu/mtk_iommu.c: In function 'mtk_iommu_iova_to_phys': 438 | if (data->enable_4GB && pa >= MTK_IOMMU_4GB_MODE_REMAP_BASE) | ^~ vim +438 drivers/iommu/mtk_iommu.c 4d689b61944589 Robin Murphy 2017-09-28 429 0df4fabe208d95 Yong Wu 2016-02-23 430 static phys_addr_t mtk_iommu_iova_to_phys(struct iommu_domain *domain, 0df4fabe208d95 Yong Wu 2016-02-23 431 dma_addr_t iova) 0df4fabe208d95 Yong Wu 2016-02-23 432 { 0df4fabe208d95 Yong Wu 2016-02-23 433 struct mtk_iommu_domain *dom = to_mtk_domain(domain); 30e2fccf951238 Yong Wu 2017-08-21 434 struct mtk_iommu_data *data = mtk_iommu_get_m4u_data(); 0df4fabe208d95 Yong Wu 2016-02-23 435 phys_addr_t pa; 0df4fabe208d95 Yong Wu 2016-02-23 436 0df4fabe208d95 Yong Wu 2016-02-23 437 pa = dom->iop->iova_to_phys(dom->iop, iova); b4dad40e4f35bb Yong Wu 2019-08-24 @438 if (data->enable_4GB && pa >= MTK_IOMMU_4GB_MODE_REMAP_BASE) b4dad40e4f35bb Yong Wu 2019-08-24 439 pa &= ~BIT_ULL(32); 30e2fccf951238 Yong Wu 2017-08-21 440 0df4fabe208d95 Yong Wu 2016-02-23 441 return pa; 0df4fabe208d95 Yong Wu 2016-02-23 442 } 0df4fabe208d95 Yong Wu 2016-02-23 443 :::::: The code at line 438 was first introduced by commit :::::: b4dad40e4f35bbf2393f35f4492acf799eb8136d iommu/mediatek: Adjust the PA for the 4GB Mode :::::: TO: Yong Wu <yong.wu(a)mediatek.com&gt; :::::: CC: Joerg Roedel <jroedel(a)suse.de&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org