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From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, Michal Hocko <mhocko@suse.com>,
	Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Christopher Lameter <cl@linux.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Gautham R Shenoy <ego@linux.vnet.ibm.com>,
	Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>,
	David Hildenbrand <david@redhat.com>
Subject: [PATCH v5 1/3] powerpc/numa: Set numa_node for all possible cpus
Date: Wed, 24 Jun 2020 14:58:44 +0530
Message-ID: <20200624092846.9194-2-srikar@linux.vnet.ibm.com> (raw)
In-Reply-To: <20200624092846.9194-1-srikar@linux.vnet.ibm.com>

A Powerpc system with multiple possible nodes and with CONFIG_NUMA
enabled always used to have a node 0, even if node 0 does not any cpus
or memory attached to it. As per PAPR, node affinity of a cpu is only
available once its present / online. For all cpus that are possible but
not present, cpu_to_node() would point to node 0.

To ensure a cpuless, memoryless dummy node is not online, powerpc need
to make sure all possible but not present cpu_to_node are set to a
proper node.

Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Christopher Lameter <cl@linux.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com>
Cc: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---
Changelog v4:->v5:
- rebased to v5.8-rc2
link v4: http://lore.kernel.org/lkml/20200512132937.19295-1-srikar@linux.vnet.ibm.com/t/#u

Changelog v3:->v4:
- Resolved comments from Christopher.
Link v3: http://lore.kernel.org/lkml/20200501031128.19584-1-srikar@linux.vnet.ibm.com/t/#u

Changelog v1:->v2:
- Rebased to v5.7-rc3

 arch/powerpc/mm/numa.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 9fcf2d195830..5b7918c132f5 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -506,6 +506,11 @@ static int numa_setup_cpu(unsigned long lcpu)
 	int fcpu = cpu_first_thread_sibling(lcpu);
 	int nid = NUMA_NO_NODE;
 
+	if (!cpu_present(lcpu)) {
+		set_cpu_numa_node(lcpu, first_online_node);
+		return first_online_node;
+	}
+
 	/*
 	 * If a valid cpu-to-node mapping is already available, use it
 	 * directly instead of querying the firmware, since it represents
@@ -931,8 +936,17 @@ void __init mem_topology_setup(void)
 
 	reset_numa_cpu_lookup_table();
 
-	for_each_present_cpu(cpu)
+	for_each_possible_cpu(cpu) {
+		/*
+		 * Powerpc with CONFIG_NUMA always used to have a node 0,
+		 * even if it was memoryless or cpuless. For all cpus that
+		 * are possible but not present, cpu_to_node() would point
+		 * to node 0. To remove a cpuless, memoryless dummy node,
+		 * powerpc need to make sure all possible but not present
+		 * cpu_to_node are set to a proper node.
+		 */
 		numa_setup_cpu(cpu);
+	}
 }
 
 void __init initmem_init(void)
-- 
2.18.1



  reply index

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-24  9:28 [PATCH v5 0/3] Offline memoryless cpuless node 0 Srikar Dronamraju
2020-06-24  9:28 ` Srikar Dronamraju [this message]
2020-06-24  9:48   ` [PATCH v5 1/3] powerpc/numa: Set numa_node for all possible cpus Gautham R Shenoy
2020-06-24  9:28 ` [PATCH v5 2/3] powerpc/numa: Prefer node id queried from vphn Srikar Dronamraju
2020-06-24 10:29   ` Gautham R Shenoy
2020-06-24  9:28 ` [PATCH v5 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline Srikar Dronamraju
2020-06-29 14:58   ` Christopher Lameter
2020-06-30  4:01     ` Srikar Dronamraju
2020-07-01 12:23       ` Michal Hocko
2020-07-01  8:42   ` Michal Hocko
2020-07-01 10:04     ` Srikar Dronamraju
2020-07-01 10:15       ` David Hildenbrand
2020-07-01 11:01         ` Srikar Dronamraju
2020-07-01 11:06           ` David Hildenbrand
2020-07-01 11:30             ` David Hildenbrand
2020-07-01 12:21               ` Michal Hocko
2020-07-02  6:44                 ` Srikar Dronamraju
2020-07-02  8:41                   ` Michal Hocko
2020-07-02 14:32                     ` Srikar Dronamraju
2020-07-03  9:10                 ` Michal Suchánek
2020-07-03  9:24                   ` Michal Hocko
2020-07-03 10:59                     ` Michal Hocko
2020-07-03 11:32                       ` David Hildenbrand
2020-07-03 11:46                         ` Michal Hocko
2020-07-03 12:58                       ` Srikar Dronamraju
2020-08-07  4:32                         ` Andrew Morton
2020-08-07  6:58                           ` David Hildenbrand
2020-08-07 10:04                             ` Michal Suchánek
2020-07-06 16:08                     ` Andi Kleen

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