From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f69.google.com (mail-pl0-f69.google.com [209.85.160.69]) by kanga.kvack.org (Postfix) with ESMTP id 4B1AF6B0038 for ; Fri, 1 Dec 2017 05:04:27 -0500 (EST) Received: by mail-pl0-f69.google.com with SMTP id 97so4252636ple.5 for ; Fri, 01 Dec 2017 02:04:27 -0800 (PST) Received: from szxga04-in.huawei.com (szxga04-in.huawei.com. [45.249.212.190]) by mx.google.com with ESMTPS id l3si4574575pgs.302.2017.12.01.02.04.25 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 01 Dec 2017 02:04:25 -0800 (PST) From: Yisheng Xie Subject: [PATCH v4 3/3] mm/mempolicy: add nodes_empty check in SYSC_migrate_pages Date: Fri, 1 Dec 2017 17:55:28 +0800 Message-ID: <1512122128-6220-1-git-send-email-xieyisheng1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Yisheng Xie , Andi Kleen , Chris Salls , Christopher Lameter , David Rientjes , Ingo Molnar , Naoya Horiguchi , Tan Xiaojun , Vlastimil Babka As in manpage of migrate_pages, the errno should be set to EINVAL when none of the node IDs specified by new_nodes are on-line and allowed by the process's current cpuset context, or none of the specified nodes contain memory. However, when test by following case: new_nodes = 0; old_nodes = 0xf; ret = migrate_pages(pid, old_nodes, new_nodes, MAX); The ret will be 0 and no errno is set. As the new_nodes is empty, we should expect EINVAL as documented. To fix the case like above, this patch check whether target nodes AND current task_nodes is empty, and then check whether AND node_states[N_MEMORY] is empty. Meanwhile,this patch also remove the check of EPERM on CAP_SYS_NICE. The caller of migrate_pages should be able to migrate the target process pages anywhere the caller can allocate memory, if the caller can access the mm_struct. Signed-off-by: Yisheng Xie Cc: Andi Kleen Cc: Chris Salls Cc: Christopher Lameter Cc: David Rientjes Cc: Ingo Molnar Cc: Naoya Horiguchi Cc: Tan Xiaojun Cc: Vlastimil Babka --- v3: * check whether node is empty after AND current task node, and then nodes which have memory v4: * remove the check of EPERM on CAP_SYS_NICE. Hi Vlastimil and Christopher, Could you please help to review this version? Thanks Yisheng Xie mm/mempolicy.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 65df28d..4da74b6 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1426,17 +1426,14 @@ static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode, } rcu_read_unlock(); - task_nodes = cpuset_mems_allowed(task); - /* Is the user allowed to access the target nodes? */ - if (!nodes_subset(*new, task_nodes) && !capable(CAP_SYS_NICE)) { - err = -EPERM; + task_nodes = cpuset_mems_allowed(current); + nodes_and(*new, *new, task_nodes); + if (nodes_empty(*new)) goto out_put; - } - if (!nodes_subset(*new, node_states[N_MEMORY])) { - err = -EINVAL; + nodes_and(*new, *new, node_states[N_MEMORY]); + if (nodes_empty(*new)) goto out_put; - } err = security_task_movememory(task); if (err) -- 1.7.12.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org