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Subject: Re: [PATCH RFC v2 4/4] mm/mempolicy: add nodes_empty check in
 SYSC_migrate_pages
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From: Yisheng Xie <xieyisheng1@huawei.com>
Message-ID: <a4f1212f-3903-abbc-772a-1ddee6f7f98b@huawei.com>
Date: Tue, 7 Nov 2017 19:23:52 +0800
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To: Christopher Lameter <cl@linux.com>, Vlastimil Babka <vbabka@suse.cz>
Cc: akpm@linux-foundation.org, mhocko@suse.com, mingo@kernel.org, rientjes@google.com, n-horiguchi@ah.jp.nec.com, salls@cs.ucsb.edu, linux-mm@kvack.org, linux-kernel@vger.kernel.org, tanxiaojun@huawei.com, linux-api@vger.kernel.org, Andi Kleen <ak@linux.intel.com>

hi Christopher and Vlastimil,

Thanks for your comment!
On 2017/11/6 23:29, Christopher Lameter wrote:
> On Mon, 6 Nov 2017, Vlastimil Babka wrote:
> 
>> I'm not sure what exactly is the EPERM intention. Should really the
>> capability of THIS process override the cpuset restriction of the TARGET
>> process? Maybe yes. Then, does "insufficient privilege (CAP_SYS_NICE) to
> 
> CAP_SYS_NICE never overrides cpuset restrictions. The cap can be used to
> migrate pages that are *also* mapped by other processes (and thus move
> pages of another process which may have different cpu set restrictions!).

So you means the specified nodes should be a subset of target cpu set, right?

Thanks
Yisheng Xie
> The cap should not allow migrating pages to nodes that are not allowed by
> the cpuset of the current process.
> 
> 
> 
> .
> 

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