From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx> Subject: mm/debug_vm_pgtable: avoid none pte in pte_clear_test pte_clear_tests operate on an existing pte entry. Make sure that is not a none pte entry. [aneesh.kumar@xxxxxxxxxxxxx: avoid kernel crash with riscv] Link: https://lkml.kernel.org/r/20201015033206.140550-1-aneesh.kumar@xxxxxxxxxxxxx Link: https://lkml.kernel.org/r/20200902114222.181353-14-aneesh.kumar@xxxxxxxxxxxxx Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx> Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Cc: Nathan Chancellor <natechancellor@xxxxxxxxx> Cc: Guenter Roeck <linux@xxxxxxxxxxxx> Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx> Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx> Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/debug_vm_pgtable.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/mm/debug_vm_pgtable.c~mm-debug_vm_pgtable-avoid-none-pte-in-pte_clear_test +++ a/mm/debug_vm_pgtable.c @@ -542,12 +542,15 @@ static void __init pgd_populate_tests(st #endif /* PAGETABLE_P4D_FOLDED */ static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep, - unsigned long vaddr) + unsigned long pfn, unsigned long vaddr, + pgprot_t prot) { - pte_t pte = ptep_get(ptep); + pte_t pte = pfn_pte(pfn, prot); pr_debug("Validating PTE clear\n"); +#ifndef CONFIG_RISCV pte = __pte(pte_val(pte) | RANDOM_ORVALUE); +#endif set_pte_at(mm, vaddr, ptep, pte); barrier(); pte_clear(mm, vaddr, ptep); @@ -998,7 +1001,7 @@ static int __init debug_vm_pgtable(void) ptl = pte_lockptr(mm, pmdp); spin_lock(ptl); - pte_clear_tests(mm, ptep, vaddr); + pte_clear_tests(mm, ptep, pte_aligned, vaddr, prot); pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot); pte_unmap_unlock(ptep, ptl); _
