On Tue, 11 Dec 2018 18:48:48 +0000
Robin Murphy <robin.murphy@xxxxxxx> wrote:
> Wire up the basic support for hot-adding memory. Since memory hotplug
> is fairly tightly coupled to sparsemem, we tweak pfn_valid() to also
> cross-check the presence of a section in the manner of the generic
> implementation, before falling back to memblock to check for no-map
> regions within a present section as before. By having arch_add_memory(()
> create the linear mapping first, this then makes everything work in the
> way that __add_section() expects.
>
> We expect hotplug to be ACPI-driven, so the swapper_pg_dir updates
> should be safe from races by virtue of the global device hotplug lock.
>
> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
Hi Robin,
What tree is this against?
rodata_full doesn't seem be exist for me on 4.20-rc6.
With v1 I did the 'new node' test and it looked good except for an
old cgroups warning that has always been there (and has been on my list
to track down for a long time).
Jonathan
> ---
>
> v2: Handle page-mappings-only cases appropriately
>
> arch/arm64/Kconfig | 3 +++
> arch/arm64/mm/init.c | 8 ++++++++
> arch/arm64/mm/mmu.c | 17 +++++++++++++++++
> arch/arm64/mm/numa.c | 10 ++++++++++
> 4 files changed, 38 insertions(+)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 4dbef530cf58..be423fda5cec 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -261,6 +261,9 @@ config ZONE_DMA32
> config HAVE_GENERIC_GUP
> def_bool y
>
> +config ARCH_ENABLE_MEMORY_HOTPLUG
> + def_bool y
> +
> config SMP
> def_bool y
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 6cde00554e9b..4bfe0fc9edac 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -291,6 +291,14 @@ int pfn_valid(unsigned long pfn)
>
> if ((addr >> PAGE_SHIFT) != pfn)
> return 0;
> +
> +#ifdef CONFIG_SPARSEMEM
> + if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
> + return 0;
> +
> + if (!valid_section(__nr_to_section(pfn_to_section_nr(pfn))))
> + return 0;
> +#endif
> return memblock_is_map_memory(addr);
> }
> EXPORT_SYMBOL(pfn_valid);
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 674c409a8ce4..da513a1facf4 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1046,3 +1046,20 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
> pmd_free(NULL, table);
> return 1;
> }
> +
> +#ifdef CONFIG_MEMORY_HOTPLUG
> +int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
> + bool want_memblock)
> +{
> + int flags = 0;
> +
> + if (rodata_full || debug_pagealloc_enabled())
> + flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
> +
> + __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
> + size, PAGE_KERNEL, pgd_pgtable_alloc, flags);
> +
> + return __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT,
> + altmap, want_memblock);
> +}
> +#endif
> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
> index 27a31efd9e8e..ae34e3a1cef1 100644
> --- a/arch/arm64/mm/numa.c
> +++ b/arch/arm64/mm/numa.c
> @@ -466,3 +466,13 @@ void __init arm64_numa_init(void)
>
> numa_init(dummy_numa_init);
> }
> +
> +/*
> + * We hope that we will be hotplugging memory on nodes we already know about,
> + * such that acpi_get_node() succeeds and we never fall back to this...
> + */
> +int memory_add_physaddr_to_nid(u64 addr)
> +{
> + pr_warn("Unknown node for memory at 0x%llx, assuming node 0\n", addr);
> + return 0;
> +}
