The pte entry that is used in pte_advanced_tests() is never removed from
the page table at the end of the test.
The issue is detected by page_table_check, to repro compile kernel with
the following configs:
CONFIG_DEBUG_VM_PGTABLE=y
CONFIG_PAGE_TABLE_CHECK=y
CONFIG_PAGE_TABLE_CHECK_ENFORCED=y
During the boot the following BUG is printed:
[ 7.483050][ T1] debug_vm_pgtable: [debug_vm_pgtable ]:
Validating architecture page tabs
[ 7.490930][ T1] ------------[ cut here ]------------
[ 7.494926][ T1] kernel BUG at mm/page_table_check.c:194!
[ 7.499172][ T1] invalid opcode: 0000 [#1] PREEMPT SMP KASAN
[ 7.503610][ T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.16.0+
[ 7.508600][ T1] Hardware name: QEMU Standard PC (i440FX + PIIX,
...
The entry should be properly removed from the page table before the page
is released to the free list.
Fixes: a5c3b9ffb0f4 ("mm/debug_vm_pgtable: add tests validating advanced arch page table helpers")
Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Tested-by: Zi Yan <ziy@xxxxxxxxxx>
---
mm/debug_vm_pgtable.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index a7ac97c76762..db2abd9e415b 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -171,6 +171,8 @@ static void __init pte_advanced_tests(struct pgtable_debug_args *args)
ptep_test_and_clear_young(args->vma, args->vaddr, args->ptep);
pte = ptep_get(args->ptep);
WARN_ON(pte_young(pte));
+
+ ptep_get_and_clear_full(args->mm, args->vaddr, args->ptep, 1);
}
static void __init pte_savedwrite_tests(struct pgtable_debug_args *args)
--
2.34.1.703.g22d0c6ccf7-goog
