Hi Geert, On Thu, 6 Jul 2023, kernel test robot wrote:
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: c17414a273b81fe4e34e11d69fc30cc8b1431614 commit: e67b37c368b7cc24b8c0fe5ab6c44422312eab37 m68k: allow pte_offset_map[_lock]() to fail date: 2 weeks ago config: m68k-randconfig-m031-20230706 (https://download.01.org/0day-ci/archive/20230706/202307061849.rJKwVbXb-lkp@xxxxxxxxx/config) compiler: m68k-linux-gcc (GCC) 12.3.0 reproduce: (https://download.01.org/0day-ci/archive/20230706/202307061849.rJKwVbXb-lkp@xxxxxxxxx/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@xxxxxxxxx> | Closes: https://lore.kernel.org/oe-kbuild-all/202307061849.rJKwVbXb-lkp@xxxxxxxxx/ New smatch warnings: arch/m68k/include/asm/mmu_context.h:164 load_ksp_mmu() warn: unsigned 'mmuar' is never less than zero. Old smatch warnings: arch/m68k/include/asm/mmu_context.h:114 load_ksp_mmu() warn: always true condition '(mmuar >= (0)) => (0-u32max >= 0)' arch/m68k/include/asm/mmu_context.h:140 load_ksp_mmu() warn: always true condition '(mmuar >= (0)) => (0-u32max >= 0)' vim +/mmuar +164 arch/m68k/include/asm/mmu_context.h 92 93 static inline void load_ksp_mmu(struct task_struct *task) 94 { 95 unsigned long flags; 96 struct mm_struct *mm; 97 int asid; 98 pgd_t *pgd; 99 p4d_t *p4d; 100 pud_t *pud; 101 pmd_t *pmd; 102 pte_t *pte = NULL; 103 unsigned long mmuar; 104 105 local_irq_save(flags); 106 mmuar = task->thread.ksp; 107 108 /* Search for a valid TLB entry, if one is found, don't remap */ 109 mmu_write(MMUAR, mmuar); 110 mmu_write(MMUOR, MMUOR_STLB | MMUOR_ADR); 111 if (mmu_read(MMUSR) & MMUSR_HIT) 112 goto end; 113 114 if (mmuar >= PAGE_OFFSET) { 115 mm = &init_mm; 116 } else { 117 pr_info("load_ksp_mmu: non-kernel mm found: 0x%p\n", task->mm); 118 mm = task->mm; 119 } 120 121 if (!mm) 122 goto bug; 123 124 pgd = pgd_offset(mm, mmuar); 125 if (pgd_none(*pgd)) 126 goto bug; 127 128 p4d = p4d_offset(pgd, mmuar); 129 if (p4d_none(*p4d)) 130 goto bug; 131 132 pud = pud_offset(p4d, mmuar); 133 if (pud_none(*pud)) 134 goto bug; 135 136 pmd = pmd_offset(pud, mmuar); 137 if (pmd_none(*pmd)) 138 goto bug; 139 140 pte = (mmuar >= PAGE_OFFSET) ? pte_offset_kernel(pmd, mmuar) 141 : pte_offset_map(pmd, mmuar); 142 if (!pte || pte_none(*pte) || !pte_present(*pte)) 143 goto bug; 144 145 set_pte(pte, pte_mkyoung(*pte)); 146 asid = mm->context & 0xff; 147 if (!pte_dirty(*pte) && mmuar <= PAGE_OFFSET) 148 set_pte(pte, pte_wrprotect(*pte)); 149 150 mmu_write(MMUTR, (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | 151 (((int)(pte->pte) & (int)CF_PAGE_MMUTR_MASK) 152 >> CF_PAGE_MMUTR_SHIFT) | MMUTR_V); 153 154 mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) | 155 ((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X); 156 157 mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA); 158 159 goto end; 160 161 bug: 162 pr_info("ksp load failed: mm=0x%p ksp=0x08%lx\n", mm, mmuar); 163 end: > 164 if (pte && mmuar < PAGE_OFFSET) 165 pte_unmap(pte); 166 local_irq_restore(flags); 167 } 168 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
I'm sorry, it appears that I've increased the number of smatch warnings on m68k: but since it was already complaining about "mmuar >= PAGE_OFFSET"s there, I'm not going to feel very guilty about my "mmuar < PAGE_OFFSET"; and I've no idea of the significance of PAGE_OFFSET 0 on m68k. Over to you - but I expect ignoring this will continue to be the right answer :) Thanks, Hugh
