[014/156] mm/debug_vm_pgtable: avoid none pte in pte_clear_test

Commit Message

Andrew Morton Oct. 16, 2020, 2:41 a.m. UTC

From: "Aneesh Kumar K.V" <[e-mail]>
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.

[[e-mail]: avoid kernel crash with riscv]
  Link: https://lkml.kernel.org/r/[e-mail]
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Aneesh Kumar K.V <[e-mail]>
Reviewed-by: Anshuman Khandual <[e-mail]>
Cc: Christophe Leroy <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Nathan Chancellor <[e-mail]>
Cc: Guenter Roeck <[e-mail]>
Cc: Paul Walmsley <[e-mail]>
Cc: Albert Ou <[e-mail]>
Cc: Palmer Dabbelt <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/debug_vm_pgtable.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Patch

--- 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);