The patch titled
Subject: mm: page_alloc: skip memoryless nodes entirely
has been added to the -mm mm-unstable branch. Its filename is
mm-page_alloc-skip-memoryless-nodes-entirely.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-skip-memoryless-nodes-entirely.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Subject: mm: page_alloc: skip memoryless nodes entirely
Date: Thu, 19 Oct 2023 18:43:54 +0800
Patch series "handle memoryless nodes more appropriately", v3.
Currently, in the process of initialization or offline memory, memoryless
nodes will still be built into the fallback list of itself or other nodes.
This is not what we expected, so this patch series removes memoryless
nodes from the fallback list entirely.
This patch (of 2):
In find_next_best_node(), we skipped the memoryless nodes when building
the zonelists of other normal nodes (N_NORMAL), but did not skip the
memoryless node itself when building the zonelist. This will cause it to
be traversed at runtime.
For example, say we have node0 and node1, node0 is memoryless
node, then the fallback order of node0 and node1 as follows:
[ 0.153005] Fallback order for Node 0: 0 1
[ 0.153564] Fallback order for Node 1: 1
After this patch, we skip memoryless node0 entirely, then
the fallback order of node0 and node1 as follows:
[ 0.155236] Fallback order for Node 0: 1
[ 0.155806] Fallback order for Node 1: 1
So it becomes completely invisible, which will reduce runtime
overhead.
And in this way, we will not try to allocate pages from memoryless node0,
then the panic mentioned in [1] will also be fixed. Even though this
problem has been solved by dropping the NODE_MIN_SIZE constrain in x86
[2], it would be better to fix it in core MM as well.
[1]. https://lore.kernel.org/all/20230212110305.93670-1-zhengqi.arch@xxxxxxxxxxxxx/
[2]. https://lore.kernel.org/all/20231017062215.171670-1-rppt@xxxxxxxxxx/
Link: https://lkml.kernel.org/r/cover.1697711415.git.zhengqi.arch@xxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/157013e978468241de4a4c05d5337a44638ecb0e.1697711415.git.zhengqi.arch@xxxxxxxxxxxxx
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/mm/page_alloc.c~mm-page_alloc-skip-memoryless-nodes-entirely
+++ a/mm/page_alloc.c
@@ -5052,8 +5052,11 @@ int find_next_best_node(int node, nodema
int min_val = INT_MAX;
int best_node = NUMA_NO_NODE;
- /* Use the local node if we haven't already */
- if (!node_isset(node, *used_node_mask)) {
+ /*
+ * Use the local node if we haven't already. But for memoryless local
+ * node, we should skip it and fallback to other nodes.
+ */
+ if (!node_isset(node, *used_node_mask) && node_state(node, N_MEMORY)) {
node_set(node, *used_node_mask);
return node;
}
_
Patches currently in -mm which might be from zhengqi.arch@xxxxxxxxxxxxx are
mm-page_alloc-skip-memoryless-nodes-entirely.patch
mm-memory_hotplug-drop-memoryless-node-from-fallback-lists.patch
