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Date:   Thu, 6 Dec 2018 08:23:57 +0100
From:   Michal Hocko <mhocko@kernel.org>
To:     Pingfan Liu <kernelfans@gmail.com>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Len Brown <lenb@kernel.org>, linux-acpi@vger.kernel.org
Subject: Re: [PATCH] mm/alloc: fallback to first node if the wanted node
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On Thu 06-12-18 11:34:30, Pingfan Liu wrote:
[...]
> > I suspect we are looking at two issues here. The first one, and a more
> > important one is that there is a NUMA affinity configured for the device
> > to a non-existing node. The second one is that nr_cpus affects
> > initialization of possible nodes.
> 
> The dev->numa_node info is extracted from acpi table, not depends on
> the instance of numa-node, which may be limited by nr_cpus. Hence the
> node is existing, just not instanced.

Hmm, binding to memory less node is quite dubious. But OK. I am not sure
how much sanitization can we do. We need to fallback anyway so we should
better make sure that all possible nodes are initialized regardless of
nr_cpus. I will look into that.

-- 
Michal Hocko
SUSE Labs