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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: David Rientjes <rientjes@google.com>
Cc: linux-mm@kvack.org, Jonathan Corbet <corbet@lwn.net>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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Subject: Re: [PATCH v4 1/2] memory-hotplug: add automatic onlining policy for the newly added memory
References: <1452617777-10598-1-git-send-email-vkuznets@redhat.com>
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	<87fuy168wa.fsf@vitty.brq.redhat.com>
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	<87pox44kbs.fsf@vitty.brq.redhat.com>
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Date: Fri, 15 Jan 2016 14:13:50 +0100
In-Reply-To: <alpine.DEB.2.10.1601141345430.16227@chino.kir.corp.google.com>
	(David Rientjes's message of "Thu, 14 Jan 2016 13:46:22 -0800 (PST)")
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David Rientjes <rientjes@google.com> writes:

> On Thu, 14 Jan 2016, Vitaly Kuznetsov wrote:
>
>> > My suggestion is to just simply document that auto-onlining can add the 
>> > memory but fail to online it and the failure is silent to userspace.  If 
>> > userspace cares, it can check the online status of the added memory blocks 
>> > itself.
>> 
>> The problem is not only that it's silent, but also that
>> /sys/devices/system/memory/*/state will lie as we create all memory
>> blocks in MEM_ONLINE state and from online_pages() error we can't figure
>> out which particular block failed. 'v5' which I sent yesterday is
>> supposed to fix the issue (blocks are onlined with
>> memory_block_change_state() which handles failures.
>> 
>
> Would you mind documenting that in the memory-hotplug.txt as an add-on 
> patch to your v5, which appears ready to go?

Sure,

I'll mention possible failures diring automatic onlining. It seems v5
wasn't picked by Andrew and I also have one nitpick in PATCH 2 to
address so I'll send v6.

Thanks,

-- 
  Vitaly