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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A56DEC55178 for ; Mon, 2 Nov 2020 01:07:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D4962145D for ; Mon, 2 Nov 2020 01:07:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604279262; bh=KQyvInCeV8g8Ip77u4HjEJIrTODVwkoIzUOSzXtWyY4=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=bcSoMEaZT3Wfy9nh+K9wQFU6Bl4gKLmJxKaS/9HW9oiZWjyPa6y0cAwXfFrOTqiWZ ofYiLRjh2rmYLlGSh3Jr33AUT2EorAoE+tvDwYJK8cN/emyWNy35Q0nm2qV0wIbA52 g4IuH6brvCGsx/Yd20UxQ4XOXmYrQNNTNATVic48= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727471AbgKBBHm (ORCPT ); Sun, 1 Nov 2020 20:07:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:49072 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727335AbgKBBHl (ORCPT ); Sun, 1 Nov 2020 20:07:41 -0500 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 30A592224E; Mon, 2 Nov 2020 01:07:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604279261; bh=KQyvInCeV8g8Ip77u4HjEJIrTODVwkoIzUOSzXtWyY4=; h=Date:From:To:Subject:In-Reply-To:From; b=kR/xOWdwkhCqYSCjwEjElCcsdcEI0/JSSGemIaB3T10K2uK+Rz0g65f7DHmKNDq17 VLPKvc8FrY7ymsI8pYZTEgSMKYYQX2tx5KSTrZ5E7AovwEBKRfsDt5HF5I+Yf6iCbo y2EM8EZvY1HLol2ysyenciw/vdpJEw0zDUc/hUzA= Date: Sun, 01 Nov 2020 17:07:40 -0800 From: Andrew Morton To: akpm@linux-foundation.org, linfeilong@huawei.com, linmiaohe@huawei.com, linux-mm@kvack.org, luoshijie1@huawei.com, mhocko@suse.com, mm-commits@vger.kernel.org, osalvador@suse.de, stable@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 06/15] mm: mempolicy: fix potential pte_unmap_unlock pte error Message-ID: <20201102010740._TcS3al1I%akpm@linux-foundation.org> In-Reply-To: <20201101170656.48abbd5e88375219f868af5e@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Shijie Luo Subject: mm: mempolicy: fix potential pte_unmap_unlock pte error When flags in queue_pages_pte_range don't have MPOL_MF_MOVE or MPOL_MF_MOVE_ALL bits, code breaks and passing origin pte - 1 to pte_unmap_unlock seems like not a good idea. queue_pages_pte_range can run in MPOL_MF_MOVE_ALL mode which doesn't migrate misplaced pages but returns with EIO when encountering such a page. Since commit a7f40cfe3b7a ("mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified") and early break on the first pte in the range results in pte_unmap_unlock on an underflow pte. This can lead to lockups later on when somebody tries to lock the pte resp. page_table_lock again.. Link: https://lkml.kernel.org/r/20201019074853.50856-1-luoshijie1@huawei.com Fixes: a7f40cfe3b7a ("mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified") Signed-off-by: Shijie Luo Signed-off-by: Miaohe Lin Reviewed-by: Oscar Salvador Acked-by: Michal Hocko Cc: Miaohe Lin Cc: Feilong Lin Cc: Shijie Luo Cc: Signed-off-by: Andrew Morton --- mm/mempolicy.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/mm/mempolicy.c~mm-mempolicy-fix-potential-pte_unmap_unlock-pte-error +++ a/mm/mempolicy.c @@ -525,7 +525,7 @@ static int queue_pages_pte_range(pmd_t * unsigned long flags = qp->flags; int ret; bool has_unmovable = false; - pte_t *pte; + pte_t *pte, *mapped_pte; spinlock_t *ptl; ptl = pmd_trans_huge_lock(pmd, vma); @@ -539,7 +539,7 @@ static int queue_pages_pte_range(pmd_t * if (pmd_trans_unstable(pmd)) return 0; - pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); + mapped_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); for (; addr != end; pte++, addr += PAGE_SIZE) { if (!pte_present(*pte)) continue; @@ -571,7 +571,7 @@ static int queue_pages_pte_range(pmd_t * } else break; } - pte_unmap_unlock(pte - 1, ptl); + pte_unmap_unlock(mapped_pte, ptl); cond_resched(); if (has_unmovable) _