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Subject[PATCH 1/3] mm/debug_vm_pgtable: remove pte entry from the page table
Date
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@soleen.com>
---
mm/debug_vm_pgtable.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index a7ac97c76762..f7c5970f1719 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -171,6 +171,7 @@ 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
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