From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx> Subject: mm/debug_vm_pgtable/pmd_clear: don't use pmd/pud_clear on pte entries pmd_clear() should not be used to clear pmd level pte entries. Link: https://lkml.kernel.org/r/20200902114222.181353-12-aneesh.kumar@xxxxxxxxxxxxx Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx> Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx> Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/debug_vm_pgtable.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/mm/debug_vm_pgtable.c~mm-debug_vm_pgtable-pmd_clear-dont-use-pmd-pud_clear-on-pte-entries +++ a/mm/debug_vm_pgtable.c @@ -196,6 +196,8 @@ static void __init pmd_advanced_tests(st pmd = READ_ONCE(*pmdp); WARN_ON(pmd_young(pmd)); + /* Clear the pte entries */ + pmdp_huge_get_and_clear(mm, vaddr, pmdp); pgtable = pgtable_trans_huge_withdraw(mm, pmdp); } @@ -319,6 +321,8 @@ static void __init pud_advanced_tests(st pudp_test_and_clear_young(vma, vaddr, pudp); pud = READ_ONCE(*pudp); WARN_ON(pud_young(pud)); + + pudp_huge_get_and_clear(mm, vaddr, pudp); } static void __init pud_leaf_tests(unsigned long pfn, pgprot_t prot) @@ -442,8 +446,6 @@ static void __init pud_populate_tests(st * This entry points to next level page table page. * Hence this must not qualify as pud_bad(). */ - pmd_clear(pmdp); - pud_clear(pudp); pud_populate(mm, pudp, pmdp); pud = READ_ONCE(*pudp); WARN_ON(pud_bad(pud)); @@ -575,7 +577,6 @@ static void __init pmd_populate_tests(st * This entry points to next level page table page. * Hence this must not qualify as pmd_bad(). */ - pmd_clear(pmdp); pmd_populate(mm, pmdp, pgtable); pmd = READ_ONCE(*pmdp); WARN_ON(pmd_bad(pmd)); _
