From e930d999715073a70d306fb59a394ea8b84d0b45 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Tue, 22 Mar 2022 14:46:51 -0700 Subject: mm, memory_hotplug: make arch_alloc_nodedata independent on CONFIG_MEMORY_HOTPLUG Patch series "mm, memory_hotplug: handle unitialized numa node gracefully". The core of the fix is patch 2 which also links existing bug reports. The high level goal is to have all possible numa nodes have their pgdat allocated and initialized so for_each_possible_node(nid) NODE_DATA(nid) will never return garbage. This has proven to be problem in several places when an offline numa node is used for an allocation just to realize that node_data and therefore allocation fallback zonelists are not initialized and such an allocation request blows up. There were attempts to address that by checking node_online in several places including the page allocator. This patchset approaches the problem from a different perspective and instead of special casing, which just adds a runtime overhead, it allocates pglist_data for each possible node. This can add some memory overhead for platforms with high number of possible nodes if they do not contain any memory. This should be a rather rare configuration though. How to test this? David has provided and excellent howto: http://lkml.kernel.org/r/6e5ebc19-890c-b6dd-1924-9f25c441010d@redhat.com Patches 1 and 3-6 are mostly cleanups. The patchset has been reviewed by Rafael (thanks!) and the core fix tested by Rafael and Alexey (thanks to both). David has tested as per instructions above and hasn't found any fallouts in the memory hotplug scenarios. This patch (of 6): This is a preparatory patch and it doesn't introduce any functional change. It merely pulls out arch_alloc_nodedata (and co) outside of CONFIG_MEMORY_HOTPLUG because the following patch will need to call this from the generic MM code. Link: https://lkml.kernel.org/r/20220127085305.20890-1-mhocko@kernel.org Link: https://lkml.kernel.org/r/20220127085305.20890-2-mhocko@kernel.org Signed-off-by: Michal Hocko Acked-by: Rafael Aquini Acked-by: David Hildenbrand Acked-by: Mike Rapoport Reviewed-by: Oscar Salvador Reviewed-by: Wei Yang Cc: Alexey Makhalov Cc: Christoph Lameter Cc: Dennis Zhou Cc: Eric Dumazet Cc: Nico Pache Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/ia64/mm/discontig.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'arch/ia64') diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c index 791d4176e4a6..8dc8a554f774 100644 --- a/arch/ia64/mm/discontig.c +++ b/arch/ia64/mm/discontig.c @@ -608,7 +608,6 @@ void __init paging_init(void) zero_page_memmap_ptr = virt_to_page(ia64_imva(empty_zero_page)); } -#ifdef CONFIG_MEMORY_HOTPLUG pg_data_t *arch_alloc_nodedata(int nid) { unsigned long size = compute_pernodesize(nid); @@ -626,7 +625,6 @@ void arch_refresh_nodedata(int update_node, pg_data_t *update_pgdat) pgdat_list[update_node] = update_pgdat; scatter_node_data(); } -#endif #ifdef CONFIG_SPARSEMEM_VMEMMAP int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, -- cgit v1.2.3