[RESEND PATCH v3 kernel 3/7] mm: add a function to get the max pfn

From: Liang Li
Date: Fri Oct 21 2016 - 02:38:32 EST


Expose the function to get the max pfn, so it can be used in the
virtio-balloon device driver. Simply include the 'linux/bootmem.h'
is not enough, if the device driver is built to a module, directly
refer the max_pfn lead to build failed.

Signed-off-by: Liang Li <liang.z.li@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
Cc: Amit Shah <amit.shah@xxxxxxxxxx>
---
include/linux/mm.h | 1 +
mm/page_alloc.c | 10 ++++++++++
2 files changed, 11 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index ffbd729..2a89da0e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1776,6 +1776,7 @@ static inline spinlock_t *pmd_lock(struct mm_struct *mm, pmd_t *pmd)
extern void free_area_init_node(int nid, unsigned long * zones_size,
unsigned long zone_start_pfn, unsigned long *zholes_size);
extern void free_initmem(void);
+extern unsigned long get_max_pfn(void);

/*
* Free reserved pages within range [PAGE_ALIGN(start), end & PAGE_MASK)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2b3bf67..e5f63a9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4426,6 +4426,16 @@ void show_free_areas(unsigned int filter)
show_swap_cache_info();
}

+/*
+ * The max_pfn can change because of memory hot plug, so it's only good
+ * as a hint. e.g. for sizing data structures.
+ */
+unsigned long get_max_pfn(void)
+{
+ return max_pfn;
+}
+EXPORT_SYMBOL(get_max_pfn);
+
static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
{
zoneref->zone = zone;
--
1.8.3.1