linux-kernel - [PATCH v3 4/6] x86/mm: Introduce CONFIG_KEEP

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Date:   Mon, 20 Jan 2020 11:03:11 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     tglx@...utronix.de, mingo@...hat.com
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Michal Hocko <mhocko@...e.com>, vishal.l.verma@...el.com,
        hch@....de, linux-kernel@...r.kernel.org,
        linux-nvdimm@...ts.01.org, x86@...nel.org
Subject: [PATCH v3 4/6] x86/mm: Introduce CONFIG_KEEP_NUMA

Currently x86 numa_meminfo is marked __initdata in the
CONFIG_MEMORY_HOTPLUG=n case. In support of a new facility to allow
drivers to map reserved memory to a 'target_node'
(phys_to_target_node()), add support for removing the __initdata
designation for those users. Both memory hotplug and
phys_to_target_node() users select CONFIG_KEEP_NUMA to tell the arch to
maintain its physical address to numa mapping infrastructure post init.

Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: <x86@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: David Hildenbrand <david@...hat.com>
Cc: Michal Hocko <mhocko@...e.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 arch/x86/mm/numa.c   |    6 +-----
 include/linux/numa.h |    6 ++++++
 mm/Kconfig           |    5 +++++
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 99f7a68738f0..5289d9d6799a 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -25,11 +25,7 @@ nodemask_t numa_nodes_parsed __initdata;
 struct pglist_data *node_data[MAX_NUMNODES] __read_mostly;
 EXPORT_SYMBOL(node_data);
 
-static struct numa_meminfo numa_meminfo
-#ifndef CONFIG_MEMORY_HOTPLUG
-__initdata
-#endif
-;
+static struct numa_meminfo numa_meminfo __initdata_numa;
 
 static int numa_distance_cnt;
 static u8 *numa_distance;
diff --git a/include/linux/numa.h b/include/linux/numa.h
index 20f4e44b186c..c005ed6b807b 100644
--- a/include/linux/numa.h
+++ b/include/linux/numa.h
@@ -13,6 +13,12 @@
 
 #define	NUMA_NO_NODE	(-1)
 
+#ifdef CONFIG_KEEP_NUMA
+#define __initdata_numa
+#else
+#define __initdata_numa __initdata
+#endif
+
 #ifdef CONFIG_NUMA
 int numa_map_to_online_node(int node);
 #else
diff --git a/mm/Kconfig b/mm/Kconfig
index ab80933be65f..001f1185eadf 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -139,6 +139,10 @@ config HAVE_FAST_GUP
 config ARCH_KEEP_MEMBLOCK
 	bool
 
+# Keep arch numa mapping infrastructure post-init.
+config KEEP_NUMA
+	bool
+
 config MEMORY_ISOLATION
 	bool
 
@@ -154,6 +158,7 @@ config MEMORY_HOTPLUG
 	bool "Allow for memory hot-add"
 	depends on SPARSEMEM || X86_64_ACPI_NUMA
 	depends on ARCH_ENABLE_MEMORY_HOTPLUG
+	select KEEP_NUMA if NUMA
 
 config MEMORY_HOTPLUG_SPARSE
 	def_bool y