From b7812c86c7403283f8b3775ee11c6c01d457016c Mon Sep 17 00:00:00 2001 From: Qi Zheng Date: Thu, 19 Oct 2023 18:43:55 +0800 Subject: mm: memory_hotplug: drop memoryless node from fallback lists In offline_pages(), if a node becomes memoryless, we will clear its N_MEMORY state by calling node_states_clear_node(). But we do this after rebuilding the zonelists by calling build_all_zonelists(), which will cause this memoryless node to still be in the fallback nodes (node_order[]) of other nodes. To drop memoryless nodes from fallback nodes in this case, just call node_states_clear_node() before calling build_all_zonelists(). 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 the core MM as well. https://lore.kernel.org/all/20230212110305.93670-1-zhengqi.arch@bytedance.com/ [1] https://lore.kernel.org/all/20231017062215.171670-1-rppt@kernel.org/ [2] Link: https://lkml.kernel.org/r/9f1dbe7ee1301c7163b2770e32954ff5e3ecf2c4.1697711415.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng Acked-by: David Hildenbrand Acked-by: Ingo Molnar Cc: Aneesh Kumar K.V Cc: "Huang, Ying" Cc: Johannes Weiner Cc: Matthew Wilcox (Oracle) Cc: Mel Gorman Cc: Michal Hocko Cc: Mike Rapoport Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/memory_hotplug.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'mm/memory_hotplug.c') diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 3b301c4023ff..ab41a511e20a 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -2012,12 +2012,16 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages, /* reinitialise watermarks and update pcp limits */ init_per_zone_wmark_min(); + /* + * Make sure to mark the node as memory-less before rebuilding the zone + * list. Otherwise this node would still appear in the fallback lists. + */ + node_states_clear_node(node, &arg); if (!populated_zone(zone)) { zone_pcp_reset(zone); build_all_zonelists(NULL); } - node_states_clear_node(node, &arg); if (arg.status_change_nid >= 0) { kcompactd_stop(node); kswapd_stop(node); -- cgit v1.2.3