From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f71.google.com (mail-oi0-f71.google.com [209.85.218.71]) by kanga.kvack.org (Postfix) with ESMTP id 660966B0033 for ; Sun, 3 Dec 2017 19:50:08 -0500 (EST) Received: by mail-oi0-f71.google.com with SMTP id u126so7062972oia.19 for ; Sun, 03 Dec 2017 16:50:08 -0800 (PST) Received: from szxga05-in.huawei.com (szxga05-in.huawei.com. [45.249.212.191]) by mx.google.com with ESMTPS id h56si4218740otc.7.2017.12.03.16.50.04 for (version=TLS1 cipher=AES128-SHA bits=128/128); Sun, 03 Dec 2017 16:50:07 -0800 (PST) Subject: Re: [PATCH v4 3/3] mm/mempolicy: add nodes_empty check in SYSC_migrate_pages References: <1512122128-6220-1-git-send-email-xieyisheng1@huawei.com> <305e9b37-0e58-a53d-55b7-f0815c1ba64f@suse.cz> From: Yisheng Xie Message-ID: Date: Mon, 4 Dec 2017 08:49:08 +0800 MIME-Version: 1.0 In-Reply-To: <305e9b37-0e58-a53d-55b7-f0815c1ba64f@suse.cz> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka , akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Andi Kleen , Chris Salls , Christopher Lameter , David Rientjes , Ingo Molnar , Naoya Horiguchi , Tan Xiaojun Hi Vlastimil, On 2017/12/1 23:18, Vlastimil Babka wrote: > On 12/01/2017 10:55 AM, Yisheng Xie wrote: >> 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? > > Hi, I think we should stay with v3 after all. What I missed when > reviewing it, is that the EPERM check is for cpuset_mems_allowed(task) > and in v3 you add EINVAL check for cpuset_mems_allowed(current), which > may not be the same, and the intention of CAP_SYS_NICE is not whether we > can bypass our own cpuset, but whether we can bypass the target task's > cpuset. Sorry for the confusion. Ok, so please ignore this version. Thanks Yisheng Xie > > > . > -- 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