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Mon, 8 Jun 2020 12:53:04 GMT Received: from b03ledav003.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 22CB26A058; Mon, 8 Jun 2020 12:53:04 +0000 (GMT) Received: from b03ledav003.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A66B96A047; Mon, 8 Jun 2020 12:53:01 +0000 (GMT) Received: from skywalker.ibmuc.com (unknown [9.85.88.17]) by b03ledav003.gho.boulder.ibm.com (Postfix) with ESMTP; Mon, 8 Jun 2020 12:53:01 +0000 (GMT) From: "Aneesh Kumar K.V" To: linux-mm@kvack.org, akpm@linux-foundation.org Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, "Aneesh Kumar K.V" , anshuman.khandual@arm.com Subject: [PATCH v2] mm/debug_vm_pgtable: Fix kernel crash by checking for THP support Date: Mon, 8 Jun 2020 18:22:52 +0530 Message-Id: <20200608125252.407659-1-aneesh.kumar@linux.ibm.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.687 definitions=2020-06-08_12:2020-06-08,2020-06-08 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 bulkscore=0 adultscore=0 phishscore=0 mlxlogscore=856 spamscore=0 cotscore=-2147483648 clxscore=1015 priorityscore=1501 lowpriorityscore=0 malwarescore=0 impostorscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006080094 X-Rspamd-Queue-Id: 3155B39659 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 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: Architectures can have CONFIG_TRANSPARENT_HUGEPAGE enabled but no THP support enabled based on platforms. For ex: with 4K PAGE_SIZE ppc64 supports THP only with radix translation. This results in below crash when running with hash translation and 4K PAGE_SIZE. kernel BUG at arch/powerpc/include/asm/book3s/64/hash-4k.h:140! cpu 0x61: Vector: 700 (Program Check) at [c000000ff948f860] pc: c0000000018810f8: debug_vm_pgtable+0x480/0x8b0 lr: c0000000018810ec: debug_vm_pgtable+0x474/0x8b0 ... [c000000ff948faf0] c000000001880fec debug_vm_pgtable+0x374/0x8b0 (unrelia= ble) [c000000ff948fbf0] c000000000011648 do_one_initcall+0x98/0x4f0 [c000000ff948fcd0] c000000001843928 kernel_init_freeable+0x330/0x3fc [c000000ff948fdb0] c0000000000122ac kernel_init+0x24/0x148 [c000000ff948fe20] c00000000000cc44 ret_from_kernel_thread+0x5c/0x78 Check for THP support correctly Cc: anshuman.khandual@arm.com Fixes: 399145f9eb6c ("mm/debug: add tests validating architecture page ta= ble helpers") Signed-off-by: Aneesh Kumar K.V --- mm/debug_vm_pgtable.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c index 188c18908964..df3a3a08f4f8 100644 --- a/mm/debug_vm_pgtable.c +++ b/mm/debug_vm_pgtable.c @@ -61,6 +61,9 @@ static void __init pmd_basic_tests(unsigned long pfn, p= gprot_t prot) { pmd_t pmd =3D pfn_pmd(pfn, prot); =20 + if (!has_transparent_hugepage()) + return; + WARN_ON(!pmd_same(pmd, pmd)); WARN_ON(!pmd_young(pmd_mkyoung(pmd_mkold(pmd)))); WARN_ON(!pmd_dirty(pmd_mkdirty(pmd_mkclean(pmd)))); @@ -80,6 +83,9 @@ static void __init pud_basic_tests(unsigned long pfn, p= gprot_t prot) { pud_t pud =3D pfn_pud(pfn, prot); =20 + if (!has_transparent_hugepage()) + return; + WARN_ON(!pud_same(pud, pud)); WARN_ON(!pud_young(pud_mkyoung(pud_mkold(pud)))); WARN_ON(!pud_write(pud_mkwrite(pud_wrprotect(pud)))); --=20 2.26.2