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[34.85.216.189]) by smtp.gmail.com with ESMTPSA id h9sm26226qkp.75.2022.01.26.10.36.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Jan 2022 10:36:40 -0800 (PST) From: Pasha Tatashin 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 v4 1/4] mm/debug_vm_pgtable: remove pte entry from the page table Date: Wed, 26 Jan 2022 18:36:34 +0000 Message-Id: <20220126183637.1840960-2-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.35.0.rc0.227.g00780c9af4-goog In-Reply-To: <20220126183637.1840960-1-pasha.tatashin@soleen.com> References: <20220126183637.1840960-1-pasha.tatashin@soleen.com> MIME-Version: 1.0 X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 416EB20030 X-Stat-Signature: 4zr8f1qtdbcyf3rh6cfsqay86556jtjo Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=soleen.com header.s=google header.b=QcWdQlJI; dmarc=none; spf=pass (imf31.hostedemail.com: domain of pasha.tatashin@soleen.com designates 209.85.219.48 as permitted sender) smtp.mailfrom=pasha.tatashin@soleen.com X-Rspam-User: nil X-HE-Tag: 1643222201-199967 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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=3Dy CONFIG_PAGE_TABLE_CHECK=3Dy CONFIG_PAGE_TABLE_CHECK_ENFORCED=3Dy 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") Cc: stable@vger.kernel.org # 5.9+ Signed-off-by: Pasha Tatashin Reviewed-by: Zi Yan Tested-by: Zi Yan Acked-by: David Rientjes --- 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 =3D ptep_get(args->ptep); WARN_ON(pte_young(pte)); + + ptep_get_and_clear_full(args->mm, args->vaddr, args->ptep, 1); } =20 static void __init pte_savedwrite_tests(struct pgtable_debug_args *args) --=20 2.35.0.rc0.227.g00780c9af4-goog