diff mbox series

[v1,1/2] mm/memblock: expose only miminal interface to add/walk physmem

Message ID 20200630081730.6862-2-david@redhat.com (mailing list archive)
State New, archived
Headers show
Series s390/mm: don't set ARCH_KEEP_MEMBLOCK | expand

Commit Message

David Hildenbrand June 30, 2020, 8:17 a.m. UTC
"physmem" in the memblock allocator is somewhat weird: it's not actually
used for allocation, it's simply information collected during boot, which
describes the unmodified physical memory map at boot time, without any
standby/hotplugged memory. It's only used on s390x and is currently the
only reason s390x keeps using CONFIG_ARCH_KEEP_MEMBLOCK.

Physmem isn't numa aware and current users don't specify any flags. Let's
hide it from the user, exposing only for_each_physmem(), and simplify. The
interface for physmem is now really minimalistic:
- memblock_physmem_add() to add ranges
- for_each_physmem() / __next_physmem_range() to walk physmem ranges

Don't place it into an __init section and don't discard it without
CONFIG_ARCH_KEEP_MEMBLOCK. As we're reusing __next_mem_range(), remove
the __meminit notifier to avoid section mismatch warnings once
CONFIG_ARCH_KEEP_MEMBLOCK is no longer used with
CONFIG_HAVE_MEMBLOCK_PHYS_MAP.

We can stop setting CONFIG_HAVE_MEMBLOCK_PHYS_MAP for s390x next.

Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 arch/s390/kernel/crash_dump.c |  6 ++--
 include/linux/memblock.h      | 17 +++++++---
 mm/memblock.c                 | 63 +++++++++++++++++++----------------
 3 files changed, 50 insertions(+), 36 deletions(-)

Comments

David Hildenbrand June 30, 2020, 8:19 a.m. UTC | #1
On 30.06.20 10:17, David Hildenbrand wrote:
> "physmem" in the memblock allocator is somewhat weird: it's not actually
> used for allocation, it's simply information collected during boot, which
> describes the unmodified physical memory map at boot time, without any
> standby/hotplugged memory. It's only used on s390x and is currently the
> only reason s390x keeps using CONFIG_ARCH_KEEP_MEMBLOCK.
> 
> Physmem isn't numa aware and current users don't specify any flags. Let's
> hide it from the user, exposing only for_each_physmem(), and simplify. The
> interface for physmem is now really minimalistic:
> - memblock_physmem_add() to add ranges
> - for_each_physmem() / __next_physmem_range() to walk physmem ranges
> 
> Don't place it into an __init section and don't discard it without
> CONFIG_ARCH_KEEP_MEMBLOCK. As we're reusing __next_mem_range(), remove
> the __meminit notifier to avoid section mismatch warnings once
> CONFIG_ARCH_KEEP_MEMBLOCK is no longer used with
> CONFIG_HAVE_MEMBLOCK_PHYS_MAP.
> 
> We can stop setting CONFIG_HAVE_MEMBLOCK_PHYS_MAP for s390x next.

(how I hate to spot typos just after I send stuff :) )

s/CONFIG_HAVE_MEMBLOCK_PHYS_MAP/CONFIG_ARCH_KEEP_MEMBLOCK/
Mike Rapoport June 30, 2020, 4:29 p.m. UTC | #2
On Tue, Jun 30, 2020 at 10:17:29AM +0200, David Hildenbrand wrote:
> "physmem" in the memblock allocator is somewhat weird: it's not actually
> used for allocation, it's simply information collected during boot, which
> describes the unmodified physical memory map at boot time, without any
> standby/hotplugged memory. It's only used on s390x and is currently the
> only reason s390x keeps using CONFIG_ARCH_KEEP_MEMBLOCK.
> 
> Physmem isn't numa aware and current users don't specify any flags. Let's
> hide it from the user, exposing only for_each_physmem(), and simplify. The
> interface for physmem is now really minimalistic:
> - memblock_physmem_add() to add ranges
> - for_each_physmem() / __next_physmem_range() to walk physmem ranges

I actually hoped to move physmap to s390 next to oldmem_type someday :)

> Don't place it into an __init section and don't discard it without
> CONFIG_ARCH_KEEP_MEMBLOCK. As we're reusing __next_mem_range(), remove
> the __meminit notifier to avoid section mismatch warnings once
> CONFIG_ARCH_KEEP_MEMBLOCK is no longer used with
> CONFIG_HAVE_MEMBLOCK_PHYS_MAP.
> 
> We can stop setting CONFIG_HAVE_MEMBLOCK_PHYS_MAP for s390x next.
> 
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> Cc: Vasily Gorbik <gor@linux.ibm.com>
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> Cc: Mike Rapoport <rppt@linux.ibm.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  arch/s390/kernel/crash_dump.c |  6 ++--
>  include/linux/memblock.h      | 17 +++++++---
>  mm/memblock.c                 | 63 +++++++++++++++++++----------------
>  3 files changed, 50 insertions(+), 36 deletions(-)
> 
> diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
> index f96a5857bbfde..c42ce348103cc 100644
> --- a/arch/s390/kernel/crash_dump.c
> +++ b/arch/s390/kernel/crash_dump.c
> @@ -549,8 +549,7 @@ static int get_mem_chunk_cnt(void)
>  	int cnt = 0;
>  	u64 idx;
>  
> -	for_each_mem_range(idx, &memblock.physmem, &oldmem_type, NUMA_NO_NODE,
> -			   MEMBLOCK_NONE, NULL, NULL, NULL)
> +	for_each_physmem_range(idx, &oldmem_type, NULL, NULL)
>  		cnt++;
>  	return cnt;
>  }
> @@ -563,8 +562,7 @@ static void loads_init(Elf64_Phdr *phdr, u64 loads_offset)
>  	phys_addr_t start, end;
>  	u64 idx;
>  
> -	for_each_mem_range(idx, &memblock.physmem, &oldmem_type, NUMA_NO_NODE,
> -			   MEMBLOCK_NONE, &start, &end, NULL) {
> +	for_each_physmem_range(idx, &oldmem_type, &start, &end) {
>  		phdr->p_filesz = end - start;
>  		phdr->p_type = PT_LOAD;
>  		phdr->p_offset = start;
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index 017fae833d4ae..10d879eda1ff7 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -77,16 +77,12 @@ struct memblock_type {
>   * @current_limit: physical address of the current allocation limit
>   * @memory: usable memory regions
>   * @reserved: reserved memory regions
> - * @physmem: all physical memory
>   */
>  struct memblock {
>  	bool bottom_up;  /* is bottom up direction? */
>  	phys_addr_t current_limit;
>  	struct memblock_type memory;
>  	struct memblock_type reserved;
> -#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
> -	struct memblock_type physmem;
> -#endif
>  };
>  
>  extern struct memblock memblock;
> @@ -114,6 +110,19 @@ int memblock_remove(phys_addr_t base, phys_addr_t size);
>  int memblock_free(phys_addr_t base, phys_addr_t size);
>  int memblock_reserve(phys_addr_t base, phys_addr_t size);
>  #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
> +/**
> + * for_each_physmem_range - iterate through physmem areas not included in type.
> + * @i: u64 used as loop variable
> + * @type: ptr to memblock_type which excludes from the iteration, can be %NULL
> + * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
> + * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
> + */
> +#define for_each_physmem_range(i, type, p_start, p_end)			\
> +	for (i = 0, __next_physmem_range(&i, type, p_start, p_end);	\
> +	     i != (u64)ULLONG_MAX;					\
> +	     __next_physmem_range(&i, type, p_start, p_end))
> +void __next_physmem_range(u64 *idx, struct memblock_type *type,
> +			  phys_addr_t *out_start, phys_addr_t *out_end);

__next_physmem_range() is not really necessary, the
for_each_physmem_range() macro can use __next_mem_range() directly, but
I suspect it won't look nice :)

Can you please make __next_physmem_range() static inline if we are to
keep it?

>  int memblock_physmem_add(phys_addr_t base, phys_addr_t size);
>  #endif
>  void memblock_trim_memory(phys_addr_t align);
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 39aceafc57f66..5f6389af11895 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -44,19 +44,19 @@
>   *   in the system, for instance when the memory is restricted with
>   *   ``mem=`` command line parameter
>   * * ``reserved`` - describes the regions that were allocated
> - * * ``physmap`` - describes the actual physical memory regardless of
> - *   the possible restrictions; the ``physmap`` type is only available
> - *   on some architectures.
> + * * ``physmem`` - describes the actual physical memory available during
> + *   boot regardless of the possible restrictions and memory hot(un)plug;
> + *   the ``physmem`` type is only available on some architectures.
>   *
>   * Each region is represented by :c:type:`struct memblock_region` that
>   * defines the region extents, its attributes and NUMA node id on NUMA
>   * systems. Every memory type is described by the :c:type:`struct
>   * memblock_type` which contains an array of memory regions along with
> - * the allocator metadata. The memory types are nicely wrapped with
> - * :c:type:`struct memblock`. This structure is statically initialzed
> - * at build time. The region arrays for the "memory" and "reserved"
> - * types are initially sized to %INIT_MEMBLOCK_REGIONS and for the
> - * "physmap" type to %INIT_PHYSMEM_REGIONS.
> + * the allocator metadata. The memory types (except "physmem") are nicely
> + * wrapped with :c:type:`struct memblock`. This structure is statically
> + * initialized at build time. The region arrays for the "memory" and
> + * "reserved" types are initially sized to %INIT_MEMBLOCK_REGIONS.

I'd prefer

	... The "memory" and "reserved" types are nicely wrapped 
	with :c:type:`struct memblock`. This structure is statically
        initialized at build time. 

And while on this we can update the "reserved" size to match the code:

	The region arrays are initilily sized to %INIT_MEMBLOCK_REGIONS
 	for "memory" and %INIT_MEMBLOCK_RESERVED_REGIONS for "reserved".

> + * The "physmem" type is sized to %INIT_PHYSMEM_REGIONS.
>   * The memblock_allow_resize() enables automatic resizing of the region
>   * arrays during addition of new regions. This feature should be used
>   * with care so that memory allocated for the region array will not
> @@ -87,8 +87,8 @@
>   * function frees all the memory to the buddy page allocator.
>   *
>   * Unless an architecture enables %CONFIG_ARCH_KEEP_MEMBLOCK, the
> - * memblock data structures will be discarded after the system
> - * initialization completes.
> + * memblock data structures (except physmem) will be discarded after the
> + * system initialization completes.
>   */
>  
>  #ifndef CONFIG_NEED_MULTIPLE_NODES
> @@ -104,7 +104,7 @@ unsigned long long max_possible_pfn;
>  static struct memblock_region memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
>  static struct memblock_region memblock_reserved_init_regions[INIT_MEMBLOCK_RESERVED_REGIONS] __initdata_memblock;
>  #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
> -static struct memblock_region memblock_physmem_init_regions[INIT_PHYSMEM_REGIONS] __initdata_memblock;
> +static struct memblock_region memblock_physmem_init_regions[INIT_PHYSMEM_REGIONS];
>  #endif
>  
>  struct memblock memblock __initdata_memblock = {
> @@ -118,17 +118,19 @@ struct memblock memblock __initdata_memblock = {
>  	.reserved.max		= INIT_MEMBLOCK_RESERVED_REGIONS,
>  	.reserved.name		= "reserved",
>  
> -#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
> -	.physmem.regions	= memblock_physmem_init_regions,
> -	.physmem.cnt		= 1,	/* empty dummy entry */
> -	.physmem.max		= INIT_PHYSMEM_REGIONS,
> -	.physmem.name		= "physmem",
> -#endif
> -
>  	.bottom_up		= false,
>  	.current_limit		= MEMBLOCK_ALLOC_ANYWHERE,
>  };
>  
> +#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
> +struct memblock_type physmem = {
> +	.regions		= memblock_physmem_init_regions,
> +	.cnt			= 1,	/* empty dummy entry */
> +	.max			= INIT_PHYSMEM_REGIONS,
> +	.name			= "physmem",
> +};
> +#endif
> +
>  int memblock_debug __initdata_memblock;
>  static bool system_has_some_mirror __initdata_memblock = false;
>  static int memblock_can_resize __initdata_memblock;
> @@ -831,6 +833,13 @@ int __init_memblock memblock_reserve(phys_addr_t base, phys_addr_t size)
>  }
>  
>  #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
> +void __next_physmem_range(u64 *idx, struct memblock_type *type,
> +			  phys_addr_t *out_start, phys_addr_t *out_end)
> +{
> +	__next_mem_range(idx, NUMA_NO_NODE, MEMBLOCK_NONE, &physmem, type,
> +			 out_start, out_end, NULL);
> +}
> +
>  int __init_memblock memblock_physmem_add(phys_addr_t base, phys_addr_t size)
>  {
>  	phys_addr_t end = base + size - 1;
> @@ -838,7 +847,7 @@ int __init_memblock memblock_physmem_add(phys_addr_t base, phys_addr_t size)
>  	memblock_dbg("%s: [%pa-%pa] %pS\n", __func__,
>  		     &base, &end, (void *)_RET_IP_);
>  
> -	return memblock_add_range(&memblock.physmem, base, size, MAX_NUMNODES, 0);
> +	return memblock_add_range(&physmem, base, size, MAX_NUMNODES, 0);
>  }
>  #endif
>  
> @@ -1019,12 +1028,10 @@ static bool should_skip_region(struct memblock_region *m, int nid, int flags)
>   * As both region arrays are sorted, the function advances the two indices
>   * in lockstep and returns each intersection.
>   */
> -void __init_memblock __next_mem_range(u64 *idx, int nid,
> -				      enum memblock_flags flags,
> -				      struct memblock_type *type_a,
> -				      struct memblock_type *type_b,
> -				      phys_addr_t *out_start,
> -				      phys_addr_t *out_end, int *out_nid)
> +void __next_mem_range(u64 *idx, int nid, enum memblock_flags flags,
> +		      struct memblock_type *type_a,
> +		      struct memblock_type *type_b, phys_addr_t *out_start,
> +		      phys_addr_t *out_end, int *out_nid)
>  {
>  	int idx_a = *idx & 0xffffffff;
>  	int idx_b = *idx >> 32;
> @@ -1924,7 +1931,7 @@ void __init_memblock __memblock_dump_all(void)
>  	memblock_dump(&memblock.memory);
>  	memblock_dump(&memblock.reserved);
>  #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
> -	memblock_dump(&memblock.physmem);
> +	memblock_dump(&physmem);
>  #endif
>  }
>  
> @@ -2064,8 +2071,8 @@ static int __init memblock_init_debugfs(void)
>  	debugfs_create_file("reserved", 0444, root,
>  			    &memblock.reserved, &memblock_debug_fops);
>  #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
> -	debugfs_create_file("physmem", 0444, root,
> -			    &memblock.physmem, &memblock_debug_fops);
> +	debugfs_create_file("physmem", 0444, root, &physmem,
> +			    &memblock_debug_fops);
>  #endif
>  
>  	return 0;
> -- 
> 2.26.2
>
David Hildenbrand June 30, 2020, 4:58 p.m. UTC | #3
>>  extern struct memblock memblock;
>> @@ -114,6 +110,19 @@ int memblock_remove(phys_addr_t base, phys_addr_t size);
>>  int memblock_free(phys_addr_t base, phys_addr_t size);
>>  int memblock_reserve(phys_addr_t base, phys_addr_t size);
>>  #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
>> +/**
>> + * for_each_physmem_range - iterate through physmem areas not included in type.
>> + * @i: u64 used as loop variable
>> + * @type: ptr to memblock_type which excludes from the iteration, can be %NULL
>> + * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
>> + * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
>> + */
>> +#define for_each_physmem_range(i, type, p_start, p_end)			\
>> +	for (i = 0, __next_physmem_range(&i, type, p_start, p_end);	\
>> +	     i != (u64)ULLONG_MAX;					\
>> +	     __next_physmem_range(&i, type, p_start, p_end))
>> +void __next_physmem_range(u64 *idx, struct memblock_type *type,
>> +			  phys_addr_t *out_start, phys_addr_t *out_end);
> 
> __next_physmem_range() is not really necessary, the
> for_each_physmem_range() macro can use __next_mem_range() directly, but
> I suspect it won't look nice :)
> 
> Can you please make __next_physmem_range() static inline if we are to
> keep it?

The thing is, then I have to expose "physmem" to something outside
memblock.c. That's what I wanted to avoid here. (instead, have a minimal
interface that is sufficient enough for this special case of physmem -
add memory during boot, walk memory after boot. Performance is not an
issue).

[...]

>>   * Each region is represented by :c:type:`struct memblock_region` that
>>   * defines the region extents, its attributes and NUMA node id on NUMA
>>   * systems. Every memory type is described by the :c:type:`struct
>>   * memblock_type` which contains an array of memory regions along with
>> - * the allocator metadata. The memory types are nicely wrapped with
>> - * :c:type:`struct memblock`. This structure is statically initialzed
>> - * at build time. The region arrays for the "memory" and "reserved"
>> - * types are initially sized to %INIT_MEMBLOCK_REGIONS and for the
>> - * "physmap" type to %INIT_PHYSMEM_REGIONS.
>> + * the allocator metadata. The memory types (except "physmem") are nicely
>> + * wrapped with :c:type:`struct memblock`. This structure is statically
>> + * initialized at build time. The region arrays for the "memory" and
>> + * "reserved" types are initially sized to %INIT_MEMBLOCK_REGIONS.
> 
> I'd prefer
> 
> 	... The "memory" and "reserved" types are nicely wrapped 
> 	with :c:type:`struct memblock`. This structure is statically
>         initialized at build time. 
> 
> And while on this we can update the "reserved" size to match the code:
> 
> 	The region arrays are initilily sized to %INIT_MEMBLOCK_REGIONS
>  	for "memory" and %INIT_MEMBLOCK_RESERVED_REGIONS for "reserved".

Ack to both!
David Hildenbrand June 30, 2020, 5:11 p.m. UTC | #4
> Am 30.06.2020 um 18:58 schrieb David Hildenbrand <david@redhat.com>:
> 
> 
>> 
>>> extern struct memblock memblock;
>>> @@ -114,6 +110,19 @@ int memblock_remove(phys_addr_t base, phys_addr_t size);
>>> int memblock_free(phys_addr_t base, phys_addr_t size);
>>> int memblock_reserve(phys_addr_t base, phys_addr_t size);
>>> #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
>>> +/**
>>> + * for_each_physmem_range - iterate through physmem areas not included in type.
>>> + * @i: u64 used as loop variable
>>> + * @type: ptr to memblock_type which excludes from the iteration, can be %NULL
>>> + * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
>>> + * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
>>> + */
>>> +#define for_each_physmem_range(i, type, p_start, p_end)            \
>>> +    for (i = 0, __next_physmem_range(&i, type, p_start, p_end);    \
>>> +         i != (u64)ULLONG_MAX;                    \
>>> +         __next_physmem_range(&i, type, p_start, p_end))
>>> +void __next_physmem_range(u64 *idx, struct memblock_type *type,
>>> +              phys_addr_t *out_start, phys_addr_t *out_end);
>> 
>> __next_physmem_range() is not really necessary, the
>> for_each_physmem_range() macro can use __next_mem_range() directly, but
>> I suspect it won't look nice :)
>> 
>> Can you please make __next_physmem_range() static inline if we are to
>> keep it?
> 
> The thing is, then I have to expose "physmem" to something outside
> memblock.c. That's what I wanted to avoid here. (instead, have a minimal
> interface that is sufficient enough for this special case of physmem -
> add memory during boot, walk memory after boot. Performance is not an
> issue).

... but it might do with an extern declaration within the inline function. Will have a look tomorrow, thanks!
diff mbox series

Patch

diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index f96a5857bbfde..c42ce348103cc 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -549,8 +549,7 @@  static int get_mem_chunk_cnt(void)
 	int cnt = 0;
 	u64 idx;
 
-	for_each_mem_range(idx, &memblock.physmem, &oldmem_type, NUMA_NO_NODE,
-			   MEMBLOCK_NONE, NULL, NULL, NULL)
+	for_each_physmem_range(idx, &oldmem_type, NULL, NULL)
 		cnt++;
 	return cnt;
 }
@@ -563,8 +562,7 @@  static void loads_init(Elf64_Phdr *phdr, u64 loads_offset)
 	phys_addr_t start, end;
 	u64 idx;
 
-	for_each_mem_range(idx, &memblock.physmem, &oldmem_type, NUMA_NO_NODE,
-			   MEMBLOCK_NONE, &start, &end, NULL) {
+	for_each_physmem_range(idx, &oldmem_type, &start, &end) {
 		phdr->p_filesz = end - start;
 		phdr->p_type = PT_LOAD;
 		phdr->p_offset = start;
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 017fae833d4ae..10d879eda1ff7 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -77,16 +77,12 @@  struct memblock_type {
  * @current_limit: physical address of the current allocation limit
  * @memory: usable memory regions
  * @reserved: reserved memory regions
- * @physmem: all physical memory
  */
 struct memblock {
 	bool bottom_up;  /* is bottom up direction? */
 	phys_addr_t current_limit;
 	struct memblock_type memory;
 	struct memblock_type reserved;
-#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
-	struct memblock_type physmem;
-#endif
 };
 
 extern struct memblock memblock;
@@ -114,6 +110,19 @@  int memblock_remove(phys_addr_t base, phys_addr_t size);
 int memblock_free(phys_addr_t base, phys_addr_t size);
 int memblock_reserve(phys_addr_t base, phys_addr_t size);
 #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
+/**
+ * for_each_physmem_range - iterate through physmem areas not included in type.
+ * @i: u64 used as loop variable
+ * @type: ptr to memblock_type which excludes from the iteration, can be %NULL
+ * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
+ * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
+ */
+#define for_each_physmem_range(i, type, p_start, p_end)			\
+	for (i = 0, __next_physmem_range(&i, type, p_start, p_end);	\
+	     i != (u64)ULLONG_MAX;					\
+	     __next_physmem_range(&i, type, p_start, p_end))
+void __next_physmem_range(u64 *idx, struct memblock_type *type,
+			  phys_addr_t *out_start, phys_addr_t *out_end);
 int memblock_physmem_add(phys_addr_t base, phys_addr_t size);
 #endif
 void memblock_trim_memory(phys_addr_t align);
diff --git a/mm/memblock.c b/mm/memblock.c
index 39aceafc57f66..5f6389af11895 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -44,19 +44,19 @@ 
  *   in the system, for instance when the memory is restricted with
  *   ``mem=`` command line parameter
  * * ``reserved`` - describes the regions that were allocated
- * * ``physmap`` - describes the actual physical memory regardless of
- *   the possible restrictions; the ``physmap`` type is only available
- *   on some architectures.
+ * * ``physmem`` - describes the actual physical memory available during
+ *   boot regardless of the possible restrictions and memory hot(un)plug;
+ *   the ``physmem`` type is only available on some architectures.
  *
  * Each region is represented by :c:type:`struct memblock_region` that
  * defines the region extents, its attributes and NUMA node id on NUMA
  * systems. Every memory type is described by the :c:type:`struct
  * memblock_type` which contains an array of memory regions along with
- * the allocator metadata. The memory types are nicely wrapped with
- * :c:type:`struct memblock`. This structure is statically initialzed
- * at build time. The region arrays for the "memory" and "reserved"
- * types are initially sized to %INIT_MEMBLOCK_REGIONS and for the
- * "physmap" type to %INIT_PHYSMEM_REGIONS.
+ * the allocator metadata. The memory types (except "physmem") are nicely
+ * wrapped with :c:type:`struct memblock`. This structure is statically
+ * initialized at build time. The region arrays for the "memory" and
+ * "reserved" types are initially sized to %INIT_MEMBLOCK_REGIONS.
+ * The "physmem" type is sized to %INIT_PHYSMEM_REGIONS.
  * The memblock_allow_resize() enables automatic resizing of the region
  * arrays during addition of new regions. This feature should be used
  * with care so that memory allocated for the region array will not
@@ -87,8 +87,8 @@ 
  * function frees all the memory to the buddy page allocator.
  *
  * Unless an architecture enables %CONFIG_ARCH_KEEP_MEMBLOCK, the
- * memblock data structures will be discarded after the system
- * initialization completes.
+ * memblock data structures (except physmem) will be discarded after the
+ * system initialization completes.
  */
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
@@ -104,7 +104,7 @@  unsigned long long max_possible_pfn;
 static struct memblock_region memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
 static struct memblock_region memblock_reserved_init_regions[INIT_MEMBLOCK_RESERVED_REGIONS] __initdata_memblock;
 #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
-static struct memblock_region memblock_physmem_init_regions[INIT_PHYSMEM_REGIONS] __initdata_memblock;
+static struct memblock_region memblock_physmem_init_regions[INIT_PHYSMEM_REGIONS];
 #endif
 
 struct memblock memblock __initdata_memblock = {
@@ -118,17 +118,19 @@  struct memblock memblock __initdata_memblock = {
 	.reserved.max		= INIT_MEMBLOCK_RESERVED_REGIONS,
 	.reserved.name		= "reserved",
 
-#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
-	.physmem.regions	= memblock_physmem_init_regions,
-	.physmem.cnt		= 1,	/* empty dummy entry */
-	.physmem.max		= INIT_PHYSMEM_REGIONS,
-	.physmem.name		= "physmem",
-#endif
-
 	.bottom_up		= false,
 	.current_limit		= MEMBLOCK_ALLOC_ANYWHERE,
 };
 
+#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
+struct memblock_type physmem = {
+	.regions		= memblock_physmem_init_regions,
+	.cnt			= 1,	/* empty dummy entry */
+	.max			= INIT_PHYSMEM_REGIONS,
+	.name			= "physmem",
+};
+#endif
+
 int memblock_debug __initdata_memblock;
 static bool system_has_some_mirror __initdata_memblock = false;
 static int memblock_can_resize __initdata_memblock;
@@ -831,6 +833,13 @@  int __init_memblock memblock_reserve(phys_addr_t base, phys_addr_t size)
 }
 
 #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
+void __next_physmem_range(u64 *idx, struct memblock_type *type,
+			  phys_addr_t *out_start, phys_addr_t *out_end)
+{
+	__next_mem_range(idx, NUMA_NO_NODE, MEMBLOCK_NONE, &physmem, type,
+			 out_start, out_end, NULL);
+}
+
 int __init_memblock memblock_physmem_add(phys_addr_t base, phys_addr_t size)
 {
 	phys_addr_t end = base + size - 1;
@@ -838,7 +847,7 @@  int __init_memblock memblock_physmem_add(phys_addr_t base, phys_addr_t size)
 	memblock_dbg("%s: [%pa-%pa] %pS\n", __func__,
 		     &base, &end, (void *)_RET_IP_);
 
-	return memblock_add_range(&memblock.physmem, base, size, MAX_NUMNODES, 0);
+	return memblock_add_range(&physmem, base, size, MAX_NUMNODES, 0);
 }
 #endif
 
@@ -1019,12 +1028,10 @@  static bool should_skip_region(struct memblock_region *m, int nid, int flags)
  * As both region arrays are sorted, the function advances the two indices
  * in lockstep and returns each intersection.
  */
-void __init_memblock __next_mem_range(u64 *idx, int nid,
-				      enum memblock_flags flags,
-				      struct memblock_type *type_a,
-				      struct memblock_type *type_b,
-				      phys_addr_t *out_start,
-				      phys_addr_t *out_end, int *out_nid)
+void __next_mem_range(u64 *idx, int nid, enum memblock_flags flags,
+		      struct memblock_type *type_a,
+		      struct memblock_type *type_b, phys_addr_t *out_start,
+		      phys_addr_t *out_end, int *out_nid)
 {
 	int idx_a = *idx & 0xffffffff;
 	int idx_b = *idx >> 32;
@@ -1924,7 +1931,7 @@  void __init_memblock __memblock_dump_all(void)
 	memblock_dump(&memblock.memory);
 	memblock_dump(&memblock.reserved);
 #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
-	memblock_dump(&memblock.physmem);
+	memblock_dump(&physmem);
 #endif
 }
 
@@ -2064,8 +2071,8 @@  static int __init memblock_init_debugfs(void)
 	debugfs_create_file("reserved", 0444, root,
 			    &memblock.reserved, &memblock_debug_fops);
 #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
-	debugfs_create_file("physmem", 0444, root,
-			    &memblock.physmem, &memblock_debug_fops);
+	debugfs_create_file("physmem", 0444, root, &physmem,
+			    &memblock_debug_fops);
 #endif
 
 	return 0;