[v10,08/13] mm/sparsemem: Prepare for sub-section ranges
diff mbox series

Message ID 156092353780.979959.9713046515562743194.stgit@dwillia2-desk3.amr.corp.intel.com
State New
Headers show
Series
  • mm: Sub-section memory hotplug support
Related show

Commit Message

Dan Williams June 19, 2019, 5:52 a.m. UTC
Prepare the memory hot-{add,remove} paths for handling sub-section
ranges by plumbing the starting page frame and number of pages being
handled through arch_{add,remove}_memory() to
sparse_{add,remove}_one_section().

This is simply plumbing, small cleanups, and some identifier renames. No
intended functional changes.

Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 include/linux/memory_hotplug.h |    5 +-
 mm/memory_hotplug.c            |  114 +++++++++++++++++++++++++---------------
 mm/sparse.c                    |   16 ++----
 3 files changed, 81 insertions(+), 54 deletions(-)

Comments

David Hildenbrand June 20, 2019, 10:31 a.m. UTC | #1
On 19.06.19 07:52, Dan Williams wrote:
> Prepare the memory hot-{add,remove} paths for handling sub-section
> ranges by plumbing the starting page frame and number of pages being
> handled through arch_{add,remove}_memory() to
> sparse_{add,remove}_one_section().
> 
> This is simply plumbing, small cleanups, and some identifier renames. No
> intended functional changes.
> 
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  include/linux/memory_hotplug.h |    5 +-
>  mm/memory_hotplug.c            |  114 +++++++++++++++++++++++++---------------
>  mm/sparse.c                    |   16 ++----
>  3 files changed, 81 insertions(+), 54 deletions(-)
> 
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 79e0add6a597..3ab0282b4fe5 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -348,9 +348,10 @@ extern int add_memory_resource(int nid, struct resource *resource);
>  extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
>  		unsigned long nr_pages, struct vmem_altmap *altmap);
>  extern bool is_memblock_offlined(struct memory_block *mem);
> -extern int sparse_add_one_section(int nid, unsigned long start_pfn,
> -				  struct vmem_altmap *altmap);
> +extern int sparse_add_section(int nid, unsigned long pfn,
> +		unsigned long nr_pages, struct vmem_altmap *altmap);
>  extern void sparse_remove_one_section(struct mem_section *ms,
> +		unsigned long pfn, unsigned long nr_pages,
>  		unsigned long map_offset, struct vmem_altmap *altmap);
>  extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
>  					  unsigned long pnum);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 4b882c57781a..399bf78bccc5 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -252,51 +252,84 @@ void __init register_page_bootmem_info_node(struct pglist_data *pgdat)
>  }
>  #endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
>  
> -static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
> -				   struct vmem_altmap *altmap)
> +static int __meminit __add_section(int nid, unsigned long pfn,
> +		unsigned long nr_pages,	struct vmem_altmap *altmap)
>  {
>  	int ret;
>  
> -	if (pfn_valid(phys_start_pfn))
> +	if (pfn_valid(pfn))
>  		return -EEXIST;
>  
> -	ret = sparse_add_one_section(nid, phys_start_pfn, altmap);
> +	ret = sparse_add_section(nid, pfn, nr_pages, altmap);
>  	return ret < 0 ? ret : 0;
>  }
>  
> +static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
> +		const char *reason)
> +{
> +	/*
> +	 * Disallow all operations smaller than a sub-section and only
> +	 * allow operations smaller than a section for
> +	 * SPARSEMEM_VMEMMAP. Note that check_hotplug_memory_range()
> +	 * enforces a larger memory_block_size_bytes() granularity for
> +	 * memory that will be marked online, so this check should only
> +	 * fire for direct arch_{add,remove}_memory() users outside of
> +	 * add_memory_resource().
> +	 */
> +	unsigned long min_align;
> +
> +	if (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP))
> +		min_align = PAGES_PER_SUBSECTION;
> +	else
> +		min_align = PAGES_PER_SECTION;
> +	if (!IS_ALIGNED(pfn, min_align)
> +			|| !IS_ALIGNED(nr_pages, min_align)) {
> +		WARN(1, "Misaligned __%s_pages start: %#lx end: #%lx\n",
> +				reason, pfn, pfn + nr_pages - 1);
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
>  /*
>   * Reasonably generic function for adding memory.  It is
>   * expected that archs that support memory hotplug will
>   * call this function after deciding the zone to which to
>   * add the new pages.
>   */
> -int __ref __add_pages(int nid, unsigned long phys_start_pfn,
> -		unsigned long nr_pages, struct mhp_restrictions *restrictions)
> +int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
> +		struct mhp_restrictions *restrictions)
>  {
>  	unsigned long i;
> -	int err = 0;
> -	int start_sec, end_sec;
> +	int start_sec, end_sec, err;
>  	struct vmem_altmap *altmap = restrictions->altmap;
>  
> -	/* during initialize mem_map, align hot-added range to section */
> -	start_sec = pfn_to_section_nr(phys_start_pfn);
> -	end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
> -
>  	if (altmap) {
>  		/*
>  		 * Validate altmap is within bounds of the total request
>  		 */
> -		if (altmap->base_pfn != phys_start_pfn
> +		if (altmap->base_pfn != pfn
>  				|| vmem_altmap_offset(altmap) > nr_pages) {
>  			pr_warn_once("memory add fail, invalid altmap\n");
> -			err = -EINVAL;
> -			goto out;
> +			return -EINVAL;
>  		}
>  		altmap->alloc = 0;
>  	}
>  
> +	err = check_pfn_span(pfn, nr_pages, "add");
> +	if (err)
> +		return err;
> +
> +	start_sec = pfn_to_section_nr(pfn);
> +	end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
>  	for (i = start_sec; i <= end_sec; i++) {
> -		err = __add_section(nid, section_nr_to_pfn(i), altmap);
> +		unsigned long pfns;
> +
> +		pfns = min(nr_pages, PAGES_PER_SECTION
> +				- (pfn & ~PAGE_SECTION_MASK));
> +		err = __add_section(nid, pfn, pfns, altmap);
> +		pfn += pfns;
> +		nr_pages -= pfns;
>  
>  		/*
>  		 * EEXIST is finally dealt with by ioresource collision
> @@ -309,7 +342,6 @@ int __ref __add_pages(int nid, unsigned long phys_start_pfn,
>  		cond_resched();
>  	}
>  	vmemmap_populate_print_last();
> -out:
>  	return err;
>  }
>  
> @@ -487,10 +519,10 @@ static void shrink_pgdat_span(struct pglist_data *pgdat,
>  	pgdat->node_spanned_pages = 0;
>  }
>  
> -static void __remove_zone(struct zone *zone, unsigned long start_pfn)
> +static void __remove_zone(struct zone *zone, unsigned long start_pfn,
> +		unsigned long nr_pages)
>  {
>  	struct pglist_data *pgdat = zone->zone_pgdat;
> -	int nr_pages = PAGES_PER_SECTION;
>  	unsigned long flags;
>  
>  	pgdat_resize_lock(zone->zone_pgdat, &flags);
> @@ -499,27 +531,23 @@ static void __remove_zone(struct zone *zone, unsigned long start_pfn)
>  	pgdat_resize_unlock(zone->zone_pgdat, &flags);
>  }
>  
> -static void __remove_section(struct zone *zone, struct mem_section *ms,
> -			     unsigned long map_offset,
> -			     struct vmem_altmap *altmap)
> +static void __remove_section(struct zone *zone, unsigned long pfn,
> +		unsigned long nr_pages, unsigned long map_offset,
> +		struct vmem_altmap *altmap)
>  {
> -	unsigned long start_pfn;
> -	int scn_nr;
> +	struct mem_section *ms = __nr_to_section(pfn_to_section_nr(pfn));
>  
>  	if (WARN_ON_ONCE(!valid_section(ms)))
>  		return;
>  
> -	scn_nr = __section_nr(ms);
> -	start_pfn = section_nr_to_pfn((unsigned long)scn_nr);
> -	__remove_zone(zone, start_pfn);
> -
> -	sparse_remove_one_section(ms, map_offset, altmap);
> +	__remove_zone(zone, pfn, nr_pages);
> +	sparse_remove_one_section(ms, pfn, nr_pages, map_offset, altmap);
>  }
>  
>  /**
>   * __remove_pages() - remove sections of pages from a zone
>   * @zone: zone from which pages need to be removed
> - * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
> + * @pfn: starting pageframe (must be aligned to start of a section)
>   * @nr_pages: number of pages to remove (must be multiple of section size)
>   * @altmap: alternative device page map or %NULL if default memmap is used
>   *
> @@ -528,31 +556,31 @@ static void __remove_section(struct zone *zone, struct mem_section *ms,
>   * sure that pages are marked reserved and zones are adjust properly by
>   * calling offline_pages().
>   */
> -void __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
> +void __remove_pages(struct zone *zone, unsigned long pfn,
>  		    unsigned long nr_pages, struct vmem_altmap *altmap)
>  {
> -	unsigned long i;
>  	unsigned long map_offset = 0;
> -	int sections_to_remove;
> +	int i, start_sec, end_sec;

As mentioned in v9, use "unsigned long" for start_sec and end_sec please.
Dan Williams June 20, 2019, 4:19 p.m. UTC | #2
On Thu, Jun 20, 2019 at 3:31 AM David Hildenbrand <david@redhat.com> wrote:
>
> On 19.06.19 07:52, Dan Williams wrote:
> > Prepare the memory hot-{add,remove} paths for handling sub-section
> > ranges by plumbing the starting page frame and number of pages being
> > handled through arch_{add,remove}_memory() to
> > sparse_{add,remove}_one_section().
> >
> > This is simply plumbing, small cleanups, and some identifier renames. No
> > intended functional changes.
> >
> > Cc: Michal Hocko <mhocko@suse.com>
> > Cc: Vlastimil Babka <vbabka@suse.cz>
> > Cc: Logan Gunthorpe <logang@deltatee.com>
> > Cc: Oscar Salvador <osalvador@suse.de>
> > Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> > ---
> >  include/linux/memory_hotplug.h |    5 +-
> >  mm/memory_hotplug.c            |  114 +++++++++++++++++++++++++---------------
> >  mm/sparse.c                    |   16 ++----
> >  3 files changed, 81 insertions(+), 54 deletions(-)
[..]
> > @@ -528,31 +556,31 @@ static void __remove_section(struct zone *zone, struct mem_section *ms,
> >   * sure that pages are marked reserved and zones are adjust properly by
> >   * calling offline_pages().
> >   */
> > -void __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
> > +void __remove_pages(struct zone *zone, unsigned long pfn,
> >                   unsigned long nr_pages, struct vmem_altmap *altmap)
> >  {
> > -     unsigned long i;
> >       unsigned long map_offset = 0;
> > -     int sections_to_remove;
> > +     int i, start_sec, end_sec;
>
> As mentioned in v9, use "unsigned long" for start_sec and end_sec please.

Honestly I saw you and Andrew going back and forth about "unsigned
long i" that I thought this would be handled by a follow on patchset
when that debate settled.
David Hildenbrand June 20, 2019, 4:35 p.m. UTC | #3
On 20.06.19 18:19, Dan Williams wrote:
> On Thu, Jun 20, 2019 at 3:31 AM David Hildenbrand <david@redhat.com> wrote:
>>
>> On 19.06.19 07:52, Dan Williams wrote:
>>> Prepare the memory hot-{add,remove} paths for handling sub-section
>>> ranges by plumbing the starting page frame and number of pages being
>>> handled through arch_{add,remove}_memory() to
>>> sparse_{add,remove}_one_section().
>>>
>>> This is simply plumbing, small cleanups, and some identifier renames. No
>>> intended functional changes.
>>>
>>> Cc: Michal Hocko <mhocko@suse.com>
>>> Cc: Vlastimil Babka <vbabka@suse.cz>
>>> Cc: Logan Gunthorpe <logang@deltatee.com>
>>> Cc: Oscar Salvador <osalvador@suse.de>
>>> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
>>> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
>>> ---
>>>  include/linux/memory_hotplug.h |    5 +-
>>>  mm/memory_hotplug.c            |  114 +++++++++++++++++++++++++---------------
>>>  mm/sparse.c                    |   16 ++----
>>>  3 files changed, 81 insertions(+), 54 deletions(-)
> [..]
>>> @@ -528,31 +556,31 @@ static void __remove_section(struct zone *zone, struct mem_section *ms,
>>>   * sure that pages are marked reserved and zones are adjust properly by
>>>   * calling offline_pages().
>>>   */
>>> -void __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
>>> +void __remove_pages(struct zone *zone, unsigned long pfn,
>>>                   unsigned long nr_pages, struct vmem_altmap *altmap)
>>>  {
>>> -     unsigned long i;
>>>       unsigned long map_offset = 0;
>>> -     int sections_to_remove;
>>> +     int i, start_sec, end_sec;
>>
>> As mentioned in v9, use "unsigned long" for start_sec and end_sec please.
> 
> Honestly I saw you and Andrew going back and forth about "unsigned
> long i" that I thought this would be handled by a follow on patchset
> when that debate settled.
> 

I'll send a fixup then, once this patch set is final - hoping I won't
forget about it (that's why I asked about using these types in the first
place).
Dan Williams June 20, 2019, 4:56 p.m. UTC | #4
On Thu, Jun 20, 2019 at 9:37 AM David Hildenbrand <david@redhat.com> wrote:
>
> On 20.06.19 18:19, Dan Williams wrote:
> > On Thu, Jun 20, 2019 at 3:31 AM David Hildenbrand <david@redhat.com> wrote:
> >>
> >> On 19.06.19 07:52, Dan Williams wrote:
> >>> Prepare the memory hot-{add,remove} paths for handling sub-section
> >>> ranges by plumbing the starting page frame and number of pages being
> >>> handled through arch_{add,remove}_memory() to
> >>> sparse_{add,remove}_one_section().
> >>>
> >>> This is simply plumbing, small cleanups, and some identifier renames. No
> >>> intended functional changes.
> >>>
> >>> Cc: Michal Hocko <mhocko@suse.com>
> >>> Cc: Vlastimil Babka <vbabka@suse.cz>
> >>> Cc: Logan Gunthorpe <logang@deltatee.com>
> >>> Cc: Oscar Salvador <osalvador@suse.de>
> >>> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
> >>> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> >>> ---
> >>>  include/linux/memory_hotplug.h |    5 +-
> >>>  mm/memory_hotplug.c            |  114 +++++++++++++++++++++++++---------------
> >>>  mm/sparse.c                    |   16 ++----
> >>>  3 files changed, 81 insertions(+), 54 deletions(-)
> > [..]
> >>> @@ -528,31 +556,31 @@ static void __remove_section(struct zone *zone, struct mem_section *ms,
> >>>   * sure that pages are marked reserved and zones are adjust properly by
> >>>   * calling offline_pages().
> >>>   */
> >>> -void __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
> >>> +void __remove_pages(struct zone *zone, unsigned long pfn,
> >>>                   unsigned long nr_pages, struct vmem_altmap *altmap)
> >>>  {
> >>> -     unsigned long i;
> >>>       unsigned long map_offset = 0;
> >>> -     int sections_to_remove;
> >>> +     int i, start_sec, end_sec;
> >>
> >> As mentioned in v9, use "unsigned long" for start_sec and end_sec please.
> >
> > Honestly I saw you and Andrew going back and forth about "unsigned
> > long i" that I thought this would be handled by a follow on patchset
> > when that debate settled.
> >
>
> I'll send a fixup then, once this patch set is final - hoping I won't
> forget about it (that's why I asked about using these types in the first
> place).

It's in Andrew's tree now, I'll send an incremental patch.
Oscar Salvador June 24, 2019, 6:05 p.m. UTC | #5
On Tue, 2019-06-18 at 22:52 -0700, Dan Williams wrote:
> Prepare the memory hot-{add,remove} paths for handling sub-section
> ranges by plumbing the starting page frame and number of pages being
> handled through arch_{add,remove}_memory() to
> sparse_{add,remove}_one_section().
> 
> This is simply plumbing, small cleanups, and some identifier renames.
> No
> intended functional changes.
> 
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Logan Gunthorpe <logang@deltatee.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

I already gave my Reviewed-by in the previous version:

Reviewed-by: Oscar Salvador <osalvador@suse.de>

Patch
diff mbox series

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 79e0add6a597..3ab0282b4fe5 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -348,9 +348,10 @@  extern int add_memory_resource(int nid, struct resource *resource);
 extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
 		unsigned long nr_pages, struct vmem_altmap *altmap);
 extern bool is_memblock_offlined(struct memory_block *mem);
-extern int sparse_add_one_section(int nid, unsigned long start_pfn,
-				  struct vmem_altmap *altmap);
+extern int sparse_add_section(int nid, unsigned long pfn,
+		unsigned long nr_pages, struct vmem_altmap *altmap);
 extern void sparse_remove_one_section(struct mem_section *ms,
+		unsigned long pfn, unsigned long nr_pages,
 		unsigned long map_offset, struct vmem_altmap *altmap);
 extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
 					  unsigned long pnum);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 4b882c57781a..399bf78bccc5 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -252,51 +252,84 @@  void __init register_page_bootmem_info_node(struct pglist_data *pgdat)
 }
 #endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
 
-static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
-				   struct vmem_altmap *altmap)
+static int __meminit __add_section(int nid, unsigned long pfn,
+		unsigned long nr_pages,	struct vmem_altmap *altmap)
 {
 	int ret;
 
-	if (pfn_valid(phys_start_pfn))
+	if (pfn_valid(pfn))
 		return -EEXIST;
 
-	ret = sparse_add_one_section(nid, phys_start_pfn, altmap);
+	ret = sparse_add_section(nid, pfn, nr_pages, altmap);
 	return ret < 0 ? ret : 0;
 }
 
+static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
+		const char *reason)
+{
+	/*
+	 * Disallow all operations smaller than a sub-section and only
+	 * allow operations smaller than a section for
+	 * SPARSEMEM_VMEMMAP. Note that check_hotplug_memory_range()
+	 * enforces a larger memory_block_size_bytes() granularity for
+	 * memory that will be marked online, so this check should only
+	 * fire for direct arch_{add,remove}_memory() users outside of
+	 * add_memory_resource().
+	 */
+	unsigned long min_align;
+
+	if (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP))
+		min_align = PAGES_PER_SUBSECTION;
+	else
+		min_align = PAGES_PER_SECTION;
+	if (!IS_ALIGNED(pfn, min_align)
+			|| !IS_ALIGNED(nr_pages, min_align)) {
+		WARN(1, "Misaligned __%s_pages start: %#lx end: #%lx\n",
+				reason, pfn, pfn + nr_pages - 1);
+		return -EINVAL;
+	}
+	return 0;
+}
+
 /*
  * Reasonably generic function for adding memory.  It is
  * expected that archs that support memory hotplug will
  * call this function after deciding the zone to which to
  * add the new pages.
  */
-int __ref __add_pages(int nid, unsigned long phys_start_pfn,
-		unsigned long nr_pages, struct mhp_restrictions *restrictions)
+int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
+		struct mhp_restrictions *restrictions)
 {
 	unsigned long i;
-	int err = 0;
-	int start_sec, end_sec;
+	int start_sec, end_sec, err;
 	struct vmem_altmap *altmap = restrictions->altmap;
 
-	/* during initialize mem_map, align hot-added range to section */
-	start_sec = pfn_to_section_nr(phys_start_pfn);
-	end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
-
 	if (altmap) {
 		/*
 		 * Validate altmap is within bounds of the total request
 		 */
-		if (altmap->base_pfn != phys_start_pfn
+		if (altmap->base_pfn != pfn
 				|| vmem_altmap_offset(altmap) > nr_pages) {
 			pr_warn_once("memory add fail, invalid altmap\n");
-			err = -EINVAL;
-			goto out;
+			return -EINVAL;
 		}
 		altmap->alloc = 0;
 	}
 
+	err = check_pfn_span(pfn, nr_pages, "add");
+	if (err)
+		return err;
+
+	start_sec = pfn_to_section_nr(pfn);
+	end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
 	for (i = start_sec; i <= end_sec; i++) {
-		err = __add_section(nid, section_nr_to_pfn(i), altmap);
+		unsigned long pfns;
+
+		pfns = min(nr_pages, PAGES_PER_SECTION
+				- (pfn & ~PAGE_SECTION_MASK));
+		err = __add_section(nid, pfn, pfns, altmap);
+		pfn += pfns;
+		nr_pages -= pfns;
 
 		/*
 		 * EEXIST is finally dealt with by ioresource collision
@@ -309,7 +342,6 @@  int __ref __add_pages(int nid, unsigned long phys_start_pfn,
 		cond_resched();
 	}
 	vmemmap_populate_print_last();
-out:
 	return err;
 }
 
@@ -487,10 +519,10 @@  static void shrink_pgdat_span(struct pglist_data *pgdat,
 	pgdat->node_spanned_pages = 0;
 }
 
-static void __remove_zone(struct zone *zone, unsigned long start_pfn)
+static void __remove_zone(struct zone *zone, unsigned long start_pfn,
+		unsigned long nr_pages)
 {
 	struct pglist_data *pgdat = zone->zone_pgdat;
-	int nr_pages = PAGES_PER_SECTION;
 	unsigned long flags;
 
 	pgdat_resize_lock(zone->zone_pgdat, &flags);
@@ -499,27 +531,23 @@  static void __remove_zone(struct zone *zone, unsigned long start_pfn)
 	pgdat_resize_unlock(zone->zone_pgdat, &flags);
 }
 
-static void __remove_section(struct zone *zone, struct mem_section *ms,
-			     unsigned long map_offset,
-			     struct vmem_altmap *altmap)
+static void __remove_section(struct zone *zone, unsigned long pfn,
+		unsigned long nr_pages, unsigned long map_offset,
+		struct vmem_altmap *altmap)
 {
-	unsigned long start_pfn;
-	int scn_nr;
+	struct mem_section *ms = __nr_to_section(pfn_to_section_nr(pfn));
 
 	if (WARN_ON_ONCE(!valid_section(ms)))
 		return;
 
-	scn_nr = __section_nr(ms);
-	start_pfn = section_nr_to_pfn((unsigned long)scn_nr);
-	__remove_zone(zone, start_pfn);
-
-	sparse_remove_one_section(ms, map_offset, altmap);
+	__remove_zone(zone, pfn, nr_pages);
+	sparse_remove_one_section(ms, pfn, nr_pages, map_offset, altmap);
 }
 
 /**
  * __remove_pages() - remove sections of pages from a zone
  * @zone: zone from which pages need to be removed
- * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
+ * @pfn: starting pageframe (must be aligned to start of a section)
  * @nr_pages: number of pages to remove (must be multiple of section size)
  * @altmap: alternative device page map or %NULL if default memmap is used
  *
@@ -528,31 +556,31 @@  static void __remove_section(struct zone *zone, struct mem_section *ms,
  * sure that pages are marked reserved and zones are adjust properly by
  * calling offline_pages().
  */
-void __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
+void __remove_pages(struct zone *zone, unsigned long pfn,
 		    unsigned long nr_pages, struct vmem_altmap *altmap)
 {
-	unsigned long i;
 	unsigned long map_offset = 0;
-	int sections_to_remove;
+	int i, start_sec, end_sec;
 
 	if (altmap)
 		map_offset = vmem_altmap_offset(altmap);
 
 	clear_zone_contiguous(zone);
 
-	/*
-	 * We can only remove entire sections
-	 */
-	BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
-	BUG_ON(nr_pages % PAGES_PER_SECTION);
+	if (check_pfn_span(pfn, nr_pages, "remove"))
+		return;
 
-	sections_to_remove = nr_pages / PAGES_PER_SECTION;
-	for (i = 0; i < sections_to_remove; i++) {
-		unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
+	start_sec = pfn_to_section_nr(pfn);
+	end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
+	for (i = start_sec; i <= end_sec; i++) {
+		unsigned long pfns;
 
 		cond_resched();
-		__remove_section(zone, __pfn_to_section(pfn), map_offset,
-				 altmap);
+		pfns = min(nr_pages, PAGES_PER_SECTION
+				- (pfn & ~PAGE_SECTION_MASK));
+		__remove_section(zone, pfn, pfns, map_offset, altmap);
+		pfn += pfns;
+		nr_pages -= pfns;
 		map_offset = 0;
 	}
 
diff --git a/mm/sparse.c b/mm/sparse.c
index 49f0c03d15a3..ad47e25c8f94 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -728,8 +728,8 @@  static void free_map_bootmem(struct page *memmap)
  * * -EEXIST	- Section has been present.
  * * -ENOMEM	- Out of memory.
  */
-int __meminit sparse_add_one_section(int nid, unsigned long start_pfn,
-				     struct vmem_altmap *altmap)
+int __meminit sparse_add_section(int nid, unsigned long start_pfn,
+		unsigned long nr_pages, struct vmem_altmap *altmap)
 {
 	unsigned long section_nr = pfn_to_section_nr(start_pfn);
 	struct mem_section_usage *usage;
@@ -834,8 +834,9 @@  static void free_section_usage(struct mem_section *ms, struct page *memmap,
 		free_map_bootmem(memmap);
 }
 
-void sparse_remove_one_section(struct mem_section *ms, unsigned long map_offset,
-			       struct vmem_altmap *altmap)
+void sparse_remove_one_section(struct mem_section *ms, unsigned long pfn,
+		unsigned long nr_pages, unsigned long map_offset,
+		struct vmem_altmap *altmap)
 {
 	struct page *memmap = NULL;
 	struct mem_section_usage *usage = NULL;
@@ -848,10 +849,7 @@  void sparse_remove_one_section(struct mem_section *ms, unsigned long map_offset,
 		ms->usage = NULL;
 	}
 
-	clear_hwpoisoned_pages(memmap + map_offset,
-			PAGES_PER_SECTION - map_offset);
-	free_section_usage(ms, memmap, usage,
-			section_nr_to_pfn(__section_nr(ms)),
-			PAGES_PER_SECTION, altmap);
+	clear_hwpoisoned_pages(memmap + map_offset, nr_pages - map_offset);
+	free_section_usage(ms, memmap, usage, pfn, nr_pages, altmap);
 }
 #endif /* CONFIG_MEMORY_HOTPLUG */