[patch 191/262] x86: remove memory hotplug support on X86_32

Andrew Morton
2021-11-05T20:44:42Z

From: David Hildenbrand <david@redhat.com>
Subject: x86: remove memory hotplug support on X86_32

CONFIG_MEMORY_HOTPLUG was marked BROKEN over one year and we just
restricted it to 64 bit. Let's remove the unused x86 32bit implementation
and simplify the Kconfig.

Link: https://lkml.kernel.org/r/20210929143600.49379-7-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Alex Shi <alexs@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

arch/x86/Kconfig | 6 +++---
arch/x86/mm/init_32.c | 31 -------------------------------
2 files changed, 3 insertions(+), 34 deletions(-)

--- a/arch/x86/Kconfig~x86-remove-memory-hotplug-support-on-x86_32
+++ a/arch/x86/Kconfig
@@ -62,7 +62,7 @@ config X86
select ARCH_32BIT_OFF_T if X86_32
select ARCH_CLOCKSOURCE_INIT
select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
- select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 || (X86_32 && HIGHMEM)
+ select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
@@ -1614,7 +1614,7 @@ config ARCH_SELECT_MEMORY_MODEL

config ARCH_MEMORY_PROBE
bool "Enable sysfs memory/probe interface"
- depends on X86_64 && MEMORY_HOTPLUG
+ depends on MEMORY_HOTPLUG
help
This option enables a sysfs memory/probe interface for testing.
See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
@@ -2394,7 +2394,7 @@ endmenu

config ARCH_HAS_ADD_PAGES
def_bool y
- depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
+ depends on ARCH_ENABLE_MEMORY_HOTPLUG

config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
def_bool y
--- a/arch/x86/mm/init_32.c~x86-remove-memory-hotplug-support-on-x86_32
+++ a/arch/x86/mm/init_32.c
@@ -779,37 +779,6 @@ void __init mem_init(void)
test_wp_bit();
}

-#ifdef CONFIG_MEMORY_HOTPLUG
-int arch_add_memory(int nid, u64 start, u64 size,
- struct mhp_params *params)
-{
- unsigned long start_pfn = start >> PAGE_SHIFT;
- unsigned long nr_pages = size >> PAGE_SHIFT;
- int ret;
-
- /*
- * The page tables were already mapped at boot so if the caller
- * requests a different mapping type then we must change all the
- * pages with __set_memory_prot().
- */
- if (params->pgprot.pgprot != PAGE_KERNEL.pgprot) {
- ret = __set_memory_prot(start, nr_pages, params->pgprot);
- if (ret)
- return ret;
- }
-
- return __add_pages(nid, start_pfn, nr_pages, params);
-}
-
-void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
-{
- unsigned long start_pfn = start >> PAGE_SHIFT;
- unsigned long nr_pages = size >> PAGE_SHIFT;
-
- __remove_pages(start_pfn, nr_pages, altmap);
-}
-#endif
-
int kernel_set_to_readonly __read_mostly;

static void mark_nxdata_nx(void)
_