linux-kernel - [PATCH v2 1/3] mm/memory_hotplug: Export symbol mhp_supports_memmap_on

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Message-Id: <20230720-vv-kmem_memmap-v2-1-88bdaab34993@intel.com>
Date:   Thu, 20 Jul 2023 01:14:22 -0600
From:   Vishal Verma <vishal.l.verma@...el.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Oscar Salvador <osalvador@...e.de>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Jiang <dave.jiang@...el.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        nvdimm@...ts.linux.dev, linux-cxl@...r.kernel.org,
        Huang Ying <ying.huang@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Jeff Moyer <jmoyer@...hat.com>,
        Vishal Verma <vishal.l.verma@...el.com>
Subject: [PATCH v2 1/3] mm/memory_hotplug: Export symbol
 mhp_supports_memmap_on_memory()

In preparation for dax drivers, which can be built as modules,
to use this interface, export it with EXPORT_SYMBOL_GPL(). Add a #else
case for the symbol for builds without CONFIG_MEMORY_HOTPLUG.

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: David Hildenbrand <david@...hat.com>
Cc: Oscar Salvador <osalvador@...e.de>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Dave Jiang <dave.jiang@...el.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Huang Ying <ying.huang@...el.com>
Reviewed-by: David Hildenbrand <david@...hat.com>
Signed-off-by: Vishal Verma <vishal.l.verma@...el.com>
---
 include/linux/memory_hotplug.h | 5 +++++
 mm/memory_hotplug.c            | 1 +
 2 files changed, 6 insertions(+)

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 013c69753c91..fc5da07ad011 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -355,6 +355,11 @@ extern int arch_create_linear_mapping(int nid, u64 start, u64 size,
 				      struct mhp_params *params);
 void arch_remove_linear_mapping(u64 start, u64 size);
 extern bool mhp_supports_memmap_on_memory(unsigned long size);
+#else
+static inline bool mhp_supports_memmap_on_memory(unsigned long size)
+{
+	return false;
+}
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
 #endif /* __LINUX_MEMORY_HOTPLUG_H */
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 3f231cf1b410..e9bcacbcbae2 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1284,6 +1284,7 @@ bool mhp_supports_memmap_on_memory(unsigned long size)
 	       IS_ALIGNED(vmemmap_size, PMD_SIZE) &&
 	       IS_ALIGNED(remaining_size, (pageblock_nr_pages << PAGE_SHIFT));
 }
+EXPORT_SYMBOL_GPL(mhp_supports_memmap_on_memory);
 
 /*
  * NOTE: The caller must call lock_device_hotplug() to serialize hotplug

-- 
2.41.0