From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7258CC4332F for ; Thu, 17 Nov 2022 07:56:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239380AbiKQH4r (ORCPT ); Thu, 17 Nov 2022 02:56:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46996 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231871AbiKQH4p (ORCPT ); Thu, 17 Nov 2022 02:56:45 -0500 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3740259871 for ; Wed, 16 Nov 2022 23:56:44 -0800 (PST) Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.53]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4NCXKv5GxJz15Mkr; Thu, 17 Nov 2022 15:56:19 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Thu, 17 Nov 2022 15:56:42 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Thu, 17 Nov 2022 15:56:41 +0800 Message-ID: <3ab1b3ee-4710-b598-c634-81c096ef0100@huawei.com> Date: Thu, 17 Nov 2022 15:56:41 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH v2 2/2] arm64/mm: fix incorrect file_map_count for invalid pmd/pud Content-Language: en-US To: Liu Shixin , Catalin Marinas , Will Deacon , Denys Vlasenko , Anshuman Khandual , "David Hildenbrand" , Rafael Aquini , "Pasha Tatashin" CC: , References: <20221117075602.2904324-1-liushixin2@huawei.com> <20221117075602.2904324-3-liushixin2@huawei.com> From: Kefeng Wang In-Reply-To: <20221117075602.2904324-3-liushixin2@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/11/17 15:56, Liu Shixin wrote: > The page table check trigger BUG_ON() unexpectedly when split hugepage: > > ------------[ cut here ]------------ > kernel BUG at mm/page_table_check.c:119! > Internal error: Oops - BUG: 00000000f2000800 [#1] SMP > Dumping ftrace buffer: > (ftrace buffer empty) > Modules linked in: > CPU: 7 PID: 210 Comm: transhuge-stres Not tainted 6.1.0-rc3+ #748 > Hardware name: linux,dummy-virt (DT) > pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) > pc : page_table_check_set.isra.0+0x398/0x468 > lr : page_table_check_set.isra.0+0x1c0/0x468 > [...] > Call trace: > page_table_check_set.isra.0+0x398/0x468 > __page_table_check_pte_set+0x160/0x1c0 > __split_huge_pmd_locked+0x900/0x1648 > __split_huge_pmd+0x28c/0x3b8 > unmap_page_range+0x428/0x858 > unmap_single_vma+0xf4/0x1c8 > zap_page_range+0x2b0/0x410 > madvise_vma_behavior+0xc44/0xe78 > do_madvise+0x280/0x698 > __arm64_sys_madvise+0x90/0xe8 > invoke_syscall.constprop.0+0xdc/0x1d8 > do_el0_svc+0xf4/0x3f8 > el0_svc+0x58/0x120 > el0t_64_sync_handler+0xb8/0xc0 > el0t_64_sync+0x19c/0x1a0 > [...] > > On arm64, pmd_leaf() will return true even if the pmd is invalid due to > pmd_present_invalid() check. So in pmdp_invalidate() the file_map_count > will not only decrease once but also increase once. Then in set_pte_at(), > the file_map_count increase again, and so trigger BUG_ON() unexpectedly. > > Fix this problem by adding pmd_valid() in pmd_user_accessible_page(). > Moreover, add pud_valid() for pud_user_accessible_page() too. > > Fixes: 42b2547137f5 ("arm64/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK") > Reported-by: Denys Vlasenko > Signed-off-by: Liu Shixin > Acked-by: Pasha Tatashin Reviewed-by: Kefeng Wang