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:
[ 2.262821] debug_vm_pgtable: [debug_vm_pgtable ]: Validating
architecture page table helpers
[ 2.276826] ------------[ cut here ]------------
[ 2.280426] kernel BUG at mm/page_table_check.c:162!
[ 2.284118] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[ 2.287787] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
5.16.0-11413-g2c271fe77d52 #3
[ 2.293226] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org
04/01/2014
...
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)
--
2.35.0.rc0.227.g00780c9af4-goog
