From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 08/25] mm/debug_vm_pgtable: fix kernel crash by checking for THP support Date: Wed, 10 Jun 2020 18:41:44 -0700 Message-ID: <20200611014144.9RP28D-oF%akpm@linux-foundation.org> References: <20200610184053.3fa7368ab80e23bfd44de71f@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:50486 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726163AbgFKBlq (ORCPT ); Wed, 10 Jun 2020 21:41:46 -0400 In-Reply-To: <20200610184053.3fa7368ab80e23bfd44de71f@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, aneesh.kumar@linux.ibm.com, anshuman.khandual@arm.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org From: "Aneesh Kumar K.V" Subject: mm/debug_vm_pgtable: fix kernel crash by checking for THP support 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 (unreliable) [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 Link: http://lkml.kernel.org/r/20200608125252.407659-1-aneesh.kumar@linux.ibm.com Fixes: 399145f9eb6c ("mm/debug: add tests validating architecture page table helpers") Signed-off-by: Aneesh Kumar K.V Reviewed-by: Anshuman Khandual Signed-off-by: Andrew Morton --- mm/debug_vm_pgtable.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/mm/debug_vm_pgtable.c~mm-debug_vm_pgtable-fix-kernel-crash-by-checking-for-thp-support +++ a/mm/debug_vm_pgtable.c @@ -60,6 +60,9 @@ static void __init pmd_basic_tests(unsig { pmd_t pmd = pfn_pmd(pfn, prot); + 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)))); @@ -79,6 +82,9 @@ static void __init pud_basic_tests(unsig { pud_t pud = pfn_pud(pfn, prot); + 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)))); _