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Subject[HMM-v25 06/19] mm/memory_hotplug: introduce add_pages
Date
From: Michal Hocko <mhocko@suse.com>

There are new users of memory hotplug emerging. Some of them require
different subset of arch_add_memory. There are some which only require
allocation of struct pages without mapping those pages to the kernel
address space. We currently have __add_pages for that purpose. But this
is rather lowlevel and not very suitable for the code outside of the
memory hotplug. E.g. x86_64 wants to update max_pfn which should be
done by the caller. Introduce add_pages() which should care about those
details if they are needed. Each architecture should define its
implementation and select CONFIG_ARCH_HAS_ADD_PAGES. All others use
the currently existing __add_pages.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
---
arch/x86/Kconfig | 4 ++++
arch/x86/mm/init_64.c | 22 +++++++++++++++-------
include/linux/memory_hotplug.h | 11 +++++++++++
3 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cf3012220d10..78492ac02779 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2319,6 +2319,10 @@ source "kernel/livepatch/Kconfig"

endmenu

+config ARCH_HAS_ADD_PAGES
+ def_bool y
+ depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
+
config ARCH_ENABLE_MEMORY_HOTPLUG
def_bool y
depends on X86_64 || (X86_32 && HIGHMEM)
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 136422d7d539..048fbe8fc274 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -761,7 +761,7 @@ void __init paging_init(void)
* After memory hotplug the variables max_pfn, max_low_pfn and high_memory need
* updating.
*/
-static void update_end_of_memory_vars(u64 start, u64 size)
+static void update_end_of_memory_vars(u64 start, u64 size)
{
unsigned long end_pfn = PFN_UP(start + size);

@@ -772,22 +772,30 @@ static void update_end_of_memory_vars(u64 start, u64 size)
}
}

-int arch_add_memory(int nid, u64 start, u64 size, bool want_memblock)
+int add_pages(int nid, unsigned long start_pfn,
+ unsigned long nr_pages, bool want_memblock)
{
- unsigned long start_pfn = start >> PAGE_SHIFT;
- unsigned long nr_pages = size >> PAGE_SHIFT;
int ret;

- init_memory_mapping(start, start + size);
-
ret = __add_pages(nid, start_pfn, nr_pages, want_memblock);
WARN_ON_ONCE(ret);

/* update max_pfn, max_low_pfn and high_memory */
- update_end_of_memory_vars(start, size);
+ update_end_of_memory_vars(start_pfn << PAGE_SHIFT,
+ nr_pages << PAGE_SHIFT);

return ret;
}
+
+int arch_add_memory(int nid, u64 start, u64 size, bool want_memblock)
+{
+ unsigned long start_pfn = start >> PAGE_SHIFT;
+ unsigned long nr_pages = size >> PAGE_SHIFT;
+
+ init_memory_mapping(start, start + size);
+
+ return add_pages(nid, start_pfn, nr_pages, want_memblock);
+}
EXPORT_SYMBOL_GPL(arch_add_memory);

#define PAGE_INUSE 0xFD
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 5e6e4cc36ff4..0995e1a2b458 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -133,6 +133,17 @@ extern int __remove_pages(struct zone *zone, unsigned long start_pfn,
extern int __add_pages(int nid, unsigned long start_pfn,
unsigned long nr_pages, bool want_memblock);

+#ifndef CONFIG_ARCH_HAS_ADD_PAGES
+static inline int add_pages(int nid, unsigned long start_pfn,
+ unsigned long nr_pages, bool want_memblock)
+{
+ return __add_pages(nid, start_pfn, nr_pages, want_memblock);
+}
+#else /* ARCH_HAS_ADD_PAGES */
+int add_pages(int nid, unsigned long start_pfn,
+ unsigned long nr_pages, bool want_memblock);
+#endif /* ARCH_HAS_ADD_PAGES */
+
#ifdef CONFIG_NUMA
extern int memory_add_physaddr_to_nid(u64 start);
#else
--
2.13.4
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