Re: [PATCH v3 07/26] mm: drop CONFIG_HAVE_ARCH_NODEDATA_EXTENSION
From: Jonathan Cameron <hidden>
Date: 2024-08-02 09:49:28
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linux-acpi, linux-arch, linux-arm-kernel, linux-cxl, linux-devicetree, linux-doc, linux-mips, linux-mm, linux-riscv, linux-s390, linux-sh, lkml, loongarch, nvdimm, sparclinux
On Thu, 1 Aug 2024 09:08:07 +0300 Mike Rapoport [off-list ref] wrote:
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org> There are no users of HAVE_ARCH_NODEDATA_EXTENSION left, so arch_alloc_nodedata() and arch_refresh_nodedata() are not needed anymore. Replace the call to arch_alloc_nodedata() in free_area_init() with memblock_alloc(), remove arch_refresh_nodedata() and cleanup include/linux/memory_hotplug.h from the associated ifdefery. Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Tested-by: Zi Yan <ziy@nvidia.com> # for x86_64 and arm64
Hi Mike, This has an accidental (I assume) functional change and if you have an initially offline node it all goes wrong.
quoted hunk ↗ jump to hunk
--- include/linux/memory_hotplug.h | 48 ---------------------------------- mm/mm_init.c | 3 +-- 2 files changed, 1 insertion(+), 50 deletions(-)diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index ebe876930e78..b27ddce5d324 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h@@ -16,54 +16,6 @@ struct resource; struct vmem_altmap; struct dev_pagemap; -#ifdef CONFIG_HAVE_ARCH_NODEDATA_EXTENSION -/* - * For supporting node-hotadd, we have to allocate a new pgdat. - * - * If an arch has generic style NODE_DATA(), - * node_data[nid] = kzalloc() works well. But it depends on the architecture. - * - * In general, generic_alloc_nodedata() is used. - * - */ -extern pg_data_t *arch_alloc_nodedata(int nid); -extern void arch_refresh_nodedata(int nid, pg_data_t *pgdat); - -#else /* CONFIG_HAVE_ARCH_NODEDATA_EXTENSION */ - -#define arch_alloc_nodedata(nid) generic_alloc_nodedata(nid) - -#ifdef CONFIG_NUMA -/* - * XXX: node aware allocation can't work well to get new node's memory at this time. - * Because, pgdat for the new node is not allocated/initialized yet itself. - * To use new node's memory, more consideration will be necessary. - */ -#define generic_alloc_nodedata(nid) \ -({ \ - memblock_alloc(sizeof(*pgdat), SMP_CACHE_BYTES); \ -}) - -extern pg_data_t *node_data[]; -static inline void arch_refresh_nodedata(int nid, pg_data_t *pgdat) -{ - node_data[nid] = pgdat; -} - -#else /* !CONFIG_NUMA */ - -/* never called */ -static inline pg_data_t *generic_alloc_nodedata(int nid) -{ - BUG(); - return NULL; -} -static inline void arch_refresh_nodedata(int nid, pg_data_t *pgdat) -{ -} -#endif /* CONFIG_NUMA */ -#endif /* CONFIG_HAVE_ARCH_NODEDATA_EXTENSION */ - #ifdef CONFIG_MEMORY_HOTPLUG struct page *pfn_to_online_page(unsigned long pfn);diff --git a/mm/mm_init.c b/mm/mm_init.c index 75c3bd42799b..bcc2f2dd8021 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c@@ -1838,11 +1838,10 @@ void __init free_area_init(unsigned long *max_zone_pfn) if (!node_online(nid)) { /* Allocator not initialized yet */ - pgdat = arch_alloc_nodedata(nid); + pgdat = memblock_alloc(sizeof(*pgdat), SMP_CACHE_BYTES); if (!pgdat) panic("Cannot allocate %zuB for node %d.\n", sizeof(*pgdat), nid); - arch_refresh_nodedata(nid, pgdat);
This allocates pgdat but never sets node_data[nid] to it and promptly leaks it on the line below. Just to sanity check this I spun up a qemu machine with no memory initially present on some nodes and it went boom as you'd expect. I tested with addition of NODE_DATA(nid) = pgdat; and it all seems to work as expected. Jonathan
} pgdat = NODE_DATA(nid);