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

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  [RESEND PATCH v3 kernel 3/7] mm: add a function to get the max pfn Liang Li <liang.z.li@intel.com> - 2016-10-21 08:40 +0200
    Re: [RESEND PATCH v3 kernel 3/7] mm: add a function to get the max  pfn Dave Hansen <dave.hansen@intel.com> - 2016-10-24 19:00 +0200
      RE: [RESEND PATCH v3 kernel 3/7] mm: add a function to get the max  pfn "Li, Liang Z" <liang.z.li@intel.com> - 2016-10-25 03:30 +0200

#1505496 — [RESEND PATCH v3 kernel 3/7] mm: add a function to get the max pfn

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@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Amit Shah <amit.shah@redhat.com>
---
 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

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#1507459 — Re: [RESEND PATCH v3 kernel 3/7] mm: add a function to get the max pfn

On 10/20/2016 11:24 PM, Liang Li wrote:
> 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.

I'm not sure the rest of the set is worth reviewing.  I think a lot of
it will change pretty fundamentally once you have those improved data
structures in place.

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#1507908 — RE: [RESEND PATCH v3 kernel 3/7] mm: add a function to get the max pfn

> On 10/20/2016 11:24 PM, Liang Li wrote:
> > 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.
> 
> I'm not sure the rest of the set is worth reviewing.  I think a lot of it will
> change pretty fundamentally once you have those improved data structures
> in place.

That's true. I will send out the v4 as soon as possible.

Liang

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