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Date: Mon, 4 Sep 2017 17:05:15 +0800
From: Xishi Qiu <qiuxishi@huawei.com>
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To: Michal Hocko <mhocko@kernel.org>
CC: Andrew Morton <akpm@linux-foundation.org>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Reza Arbab <arbab@linux.vnet.ibm.com>,
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        Vitaly Kuznetsov <vkuznets@redhat.com>, <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory
References: <20170904082148.23131-1-mhocko@kernel.org> <20170904082148.23131-3-mhocko@kernel.org> <59AD15B6.7080304@huawei.com> <20170904090114.mrjxipvucieadxa6@dhcp22.suse.cz>
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On 2017/9/4 17:01, Michal Hocko wrote:

> On Mon 04-09-17 16:58:30, Xishi Qiu wrote:
>> On 2017/9/4 16:21, Michal Hocko wrote:
>>
>>> From: Michal Hocko <mhocko@suse.com>
>>>
>>> We have a hardcoded 120s timeout after which the memory offline fails
>>> basically since the hot remove has been introduced. This is essentially
>>> a policy implemented in the kernel. Moreover there is no way to adjust
>>> the timeout and so we are sometimes facing memory offline failures if
>>> the system is under a heavy memory pressure or very intensive CPU
>>> workload on large machines.
>>>
>>> It is not very clear what purpose the timeout actually serves. The
>>> offline operation is interruptible by a signal so if userspace wants
>>
>> Hi Michal,
>>
>> If the user know what he should do if migration for a long time,
>> it is OK, but I don't think all the users know this operation
>> (e.g. ctrl + c) and the affect.
> 
> How is this operation any different from other potentially long
> interruptible syscalls?
> 

Hi Michal,

I means the user should stop it by himself if migration always retry in endless.

Thanks,
Xishi Qiu