Message-ID: <2c790c6c-22e4-687f-6ecd-368683d781a3@redhat.com>
Date:   Wed, 8 Dec 2021 09:38:52 +0100
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Subject: Re: [PATCH v3] mm: fix panic in __alloc_pages
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To:     Michal Hocko <mhocko@suse.com>
Cc:     Alexey Makhalov <amakhalov@vmware.com>,
        Dennis Zhou <dennis@kernel.org>,
        Eric Dumazet <eric.dumazet@gmail.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Oscar Salvador <osalvador@suse.de>, Tejun Heo <tj@kernel.org>,
        Christoph Lameter <cl@linux.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
References: <Ya+EHUYgzo8GaCeq@dhcp22.suse.cz>
 <d01c20fe-86d2-1dc8-e56d-15c0da49afb3@redhat.com>
 <Ya+LbaD8mkvIdq+c@dhcp22.suse.cz> <Ya+Nq2fWrSgl79Bn@dhcp22.suse.cz>
 <2E174230-04F3-4798-86D5-1257859FFAD8@vmware.com>
 <21539fc8-15a8-1c8c-4a4f-8b85734d2a0e@redhat.com>
 <78E39A43-D094-4706-B4BD-18C0B18EB2C3@vmware.com>
 <f9786109-518f-38d4-0270-a3e87a13c4ef@redhat.com>
 <YbBo5uvV7wtgOYrj@dhcp22.suse.cz>
 <5a44c44a-141c-363d-c23e-558edc23b9b4@redhat.com>
 <YbBuHSkvd6fDdQ9d@dhcp22.suse.cz>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
In-Reply-To: <YbBuHSkvd6fDdQ9d@dhcp22.suse.cz>
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>>
>> I think we'll soon might see setups (again, CXL is an example, but als
>> owhen providing a dynamic amount of performance differentiated memory
>> via virtio-mem) where this will most probably matter. With performance
>> differentiated memory we'll see a lot more nodes getting used in
>> general, and a lot more nodes eventually getting hotplugged.
> 
> There are certainly machines with many nodes. E.g. SLES kernels are
> build with CONFIG_NODES_SHIFT=10 which is a lot of potential nodes.
> And I have seen really large machines with many nodes but those usually
> come with a lot of memory and they do not tend to have non populated
> nodes AFAIR.

Right, and is about to change as nodes are getting used to represent
memory with differing performance characteristics/individual devices,
not the traditional "this is a socket" setup: we'll see more and more
small (virtual) machines with multiple nodes and eventually many
possible nodes.

-- 
Thanks,

David / dhildenb