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Date: Thu, 14 Jan 2016 13:46:22 -0800 (PST)
From: David Rientjes <rientjes@google.com>
Subject: Re: [PATCH v4 1/2] memory-hotplug: add automatic onlining policy
 for the newly added memory
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References: <1452617777-10598-1-git-send-email-vkuznets@redhat.com> <1452617777-10598-2-git-send-email-vkuznets@redhat.com> <alpine.DEB.2.10.1601121535150.28831@chino.kir.corp.google.com> <87fuy168wa.fsf@vitty.brq.redhat.com>
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To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: linux-mm@kvack.org, Jonathan Corbet <corbet@lwn.net>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Daniel Kiper <daniel.kiper@oracle.com>, Dan Williams <dan.j.williams@intel.com>, Tang Chen <tangchen@cn.fujitsu.com>, David Vrabel <david.vrabel@citrix.com>, Andrew Morton <akpm@linux-foundation.org>, Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>, Xishi Qiu <qiuxishi@huawei.com>, Mel Gorman <mgorman@techsingularity.net>, "K. Y. Srinivasan" <kys@microsoft.com>, Igor Mammedov <imammedo@redhat.com>, Kay Sievers <kay@vrfy.org>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, Boris Ostrovsky <boris.ostrovsky@oracle.com>, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org

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?

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