From: Pasha Tatashin <pasha.tatashin@soleen.com>
To: pasha.tatashin@soleen.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, akpm@linux-foundation.org,
rientjes@google.com, pjt@google.com, weixugc@google.com,
gthelen@google.com, mingo@redhat.com, will@kernel.org,
rppt@kernel.org, dave.hansen@linux.intel.com, hpa@zytor.com,
aneesh.kumar@linux.ibm.com, jirislaby@kernel.org,
songmuchun@bytedance.com, qydwhotmail@gmail.com,
hughd@google.com, ziy@nvidia.com, anshuman.khandual@arm.com
Subject: [PATCH v2 1/3] mm/debug_vm_pgtable: remove pte entry from the page table
Date: Thu, 20 Jan 2022 19:12:48 +0000 [thread overview]
Message-ID: <20220120191250.2671557-2-pasha.tatashin@soleen.com> (raw)
In-Reply-To: <20220120191250.2671557-1-pasha.tatashin@soleen.com>
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>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Tested-by: Zi Yan <ziy@nvidia.com>
---
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
next prev parent reply other threads:[~2022-01-20 19:12 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-20 19:12 [PATCH v2 0/3] page table check fixes and cleanups Pasha Tatashin
2022-01-20 19:12 ` Pasha Tatashin [this message]
2022-01-21 3:37 ` [PATCH v2 1/3] mm/debug_vm_pgtable: remove pte entry from the page table Anshuman Khandual
2022-01-21 14:03 ` Pasha Tatashin
2022-01-20 19:12 ` [PATCH v2 2/3] mm/page_table_check: check entries at pud and pmd levels Pasha Tatashin
2022-01-20 19:19 ` Wei Xu
2022-01-21 19:32 ` Pasha Tatashin
2022-01-20 19:12 ` [PATCH v2 3/3] mm/page_table_check: use unsigned long for page counters Pasha Tatashin
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