2023-07-20 08:01:13

by Verma, Vishal L

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 <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Huang Ying <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Signed-off-by: Vishal Verma <[email protected]>
---
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

2023-07-24 06:22:13

by Huang, Ying

Subject: Re: [PATCH v2 1/3] mm/memory_hotplug: Export symbol mhp_supports_memmap_on_memory()

Vishal Verma <[email protected]> writes:

> 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 <[email protected]>
> Cc: David Hildenbrand <[email protected]>
> Cc: Oscar Salvador <[email protected]>
> Cc: Dan Williams <[email protected]>
> Cc: Dave Jiang <[email protected]>
> Cc: Dave Hansen <[email protected]>
> Cc: Huang Ying <[email protected]>
> Reviewed-by: David Hildenbrand <[email protected]>
> Signed-off-by: Vishal Verma <[email protected]>
> ---
> 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 */

It appears that there is no user of mhp_supports_memmap_on_memory() that
may be compiled with !CONFIG_MEMORY_HOTPLUG?

--
Best Regards,
Huang, Ying

> #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