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From: Michal Hocko <mhocko@suse.com>
To: Christopher Lameter <cl@linux.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, Mel Gorman <mgorman@suse.de>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Sachin Sant <sachinp@linux.vnet.ibm.com>,
	linuxppc-dev@lists.ozlabs.org,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Kirill Tkhai <ktkhai@virtuozzo.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Bharata B Rao <bharata@linux.ibm.com>,
	Nathan Lynch <nathanl@linux.ibm.com>
Subject: Re: [PATCH v2 3/4] mm: Implement reset_numa_mem
Date: Thu, 19 Mar 2020 08:44:36 +0100	[thread overview]
Message-ID: <20200319074436.GX21362@dhcp22.suse.cz> (raw)
In-Reply-To: <alpine.DEB.2.21.2003181919450.18605@www.lameter.com>

On Wed 18-03-20 19:20:41, Cristopher Lameter wrote:
> On Wed, 18 Mar 2020, Srikar Dronamraju wrote:
> 
> > For a memoryless or offline nodes, node_numa_mem refers to a N_MEMORY
> > fallback node. Currently kernel has an API set_numa_mem that sets
> > node_numa_mem for memoryless node. However this API cannot be used for
> > offline nodes. Hence all offline nodes will have their node_numa_mem set
> > to 0. However systems can themselves have node 0 as offline i.e
> 
> That is a significant change to the basic assumptions for memory less
> nodes. Node 0 needed to have memory and processors. Not sure what else
> may break.

This assumption is simply incorrect. There many examples but just
one from top of my head 3e8589963773 ("memcg: make it work on sparse
non-0-node systems"). We simply have to forget that some nodes are
special.
-- 
Michal Hocko
SUSE Labs


  reply	other threads:[~2020-03-19  7:44 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-18  7:28 [PATCH v2 0/4] Fix kmalloc_node on offline nodes Srikar Dronamraju
2020-03-18  7:28 ` [PATCH v2 1/4] mm: Check for node_online in node_present_pages Srikar Dronamraju
2020-03-18 10:02   ` Michal Hocko
2020-03-18 11:02     ` Srikar Dronamraju
2020-03-18 11:14       ` Michal Hocko
2020-03-18 11:53     ` Vlastimil Babka
2020-03-18 12:52       ` Michal Hocko
2020-03-19  0:32       ` Michael Ellerman
2020-03-19  1:11         ` Michael Ellerman
2020-03-19  9:38         ` Vlastimil Babka
2020-03-18  7:28 ` [PATCH v2 2/4] mm/slub: Use mem_node to allocate a new slab Srikar Dronamraju
2020-03-18  7:28 ` [PATCH v2 3/4] mm: Implement reset_numa_mem Srikar Dronamraju
2020-03-18 19:20   ` Christopher Lameter
2020-03-19  7:44     ` Michal Hocko [this message]
2020-03-18  7:28 ` [PATCH v2 4/4] powerpc/numa: Set fallback nodes for offline nodes Srikar Dronamraju
2020-03-18 14:28   ` kbuild test robot
2020-03-18 18:56   ` kbuild test robot

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