[PATCH V5 0/3] mm/memblock: Excluded memory

[PATCH V5 0/3] mm/memblock: Excluded memory

[Philipp Hachtmann]

This all fits linux-next.

The first patch is a fix (not a replacement) to a patch that has already 
been put into linux-next. The original patch generates a warning for an
unused variable in case that CONFIG_ARCH_DISCARD_MEMBLOCK is not set.
It's now made the way Andrew suggested. 

The second patch adds support for exluded memory region handling in
memblock. This is needed by the current s390 development in conjunction
with kdump.
The patch is straightforward and adds some redundancy. This has been 
done to clarify that this patch does not intend to change any of
the current memblock API's behaviour.

The third patch does some cleanup and refactoring to memblock. It removes
the redundancies introduced by the patch before. It also is not intended
to change or break any behaviour or API of memblock.


Philipp Hachtmann (3):
  mm/nobootmem: Fix unused variable
  mm/memblock: Add support for excluded memory areas
  mm/memblock: Cleanup and refactoring after addition of nomap

 include/linux/memblock.h |  57 +++++++++---
 mm/Kconfig               |   3 +
 mm/memblock.c            | 233 +++++++++++++++++++++++++++++++++++------------
 mm/nobootmem.c           |  30 ++++--
 4 files changed, 243 insertions(+), 80 deletions(-)

-- 
1.8.4.5

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[PATCH V5 1/3] mm/nobootmem: Fix unused variable

[Philipp Hachtmann]

This fixes an unused variable warning in nobootmem.c

Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
---
 mm/nobootmem.c | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index e2906a5..0215c77 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -116,23 +116,29 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
 static unsigned long __init free_low_memory_core_early(void)
 {
 	unsigned long count = 0;
-	phys_addr_t start, end, size;
+	phys_addr_t start, end;
 	u64 i;
 
+#ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
+	phys_addr_t size;
+#endif
+
 	for_each_free_mem_range(i, NUMA_NO_NODE, &start, &end, NULL)
 		count += __free_memory_core(start, end);
 
 #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
-
-	/* Free memblock.reserved array if it was allocated */
-	size = get_allocated_memblock_reserved_regions_info(&start);
-	if (size)
-		count += __free_memory_core(start, start + size);
-
-	/* Free memblock.memory array if it was allocated */
-	size = get_allocated_memblock_memory_regions_info(&start);
-	if (size)
-		count += __free_memory_core(start, start + size);
+	{
+		phys_addr_t size;
+		/* Free memblock.reserved array if it was allocated */
+		size = get_allocated_memblock_reserved_regions_info(&start);
+		if (size)
+			count += __free_memory_core(start, start + size);
+		
+		/* Free memblock.memory array if it was allocated */
+		size = get_allocated_memblock_memory_regions_info(&start);
+		if (size)
+			count += __free_memory_core(start, start + size);
+	}
 #endif
 
 	return count;
-- 
1.8.4.5

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Re: [PATCH V5 1/3] mm/nobootmem: Fix unused variable

[Robin Holt]

On Mon, Jan 20, 2014 at 5:32 AM, Philipp Hachtmann
<phacht@linux.vnet.ibm.com> wrote:
> This fixes an unused variable warning in nobootmem.c
>
> Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
> ---
>  mm/nobootmem.c | 28 +++++++++++++++++-----------
>  1 file changed, 17 insertions(+), 11 deletions(-)
>
> diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> index e2906a5..0215c77 100644
> --- a/mm/nobootmem.c
> +++ b/mm/nobootmem.c
> @@ -116,23 +116,29 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
>  static unsigned long __init free_low_memory_core_early(void)
>  {
>         unsigned long count = 0;
> -       phys_addr_t start, end, size;
> +       phys_addr_t start, end;
>         u64 i;
>
> +#ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
> +       phys_addr_t size;
> +#endif
> +

Is this needed?  It looks like you declare size again inside the next
#ifdef chunk.

>         for_each_free_mem_range(i, NUMA_NO_NODE, &start, &end, NULL)
>                 count += __free_memory_core(start, end);
>
>  #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
> -
> -       /* Free memblock.reserved array if it was allocated */
> -       size = get_allocated_memblock_reserved_regions_info(&start);
> -       if (size)
> -               count += __free_memory_core(start, start + size);
> -
> -       /* Free memblock.memory array if it was allocated */
> -       size = get_allocated_memblock_memory_regions_info(&start);
> -       if (size)
> -               count += __free_memory_core(start, start + size);
> +       {
> +               phys_addr_t size;
> +               /* Free memblock.reserved array if it was allocated */
> +               size = get_allocated_memblock_reserved_regions_info(&start);
> +               if (size)
> +                       count += __free_memory_core(start, start + size);
> +
> +               /* Free memblock.memory array if it was allocated */
> +               size = get_allocated_memblock_memory_regions_info(&start);
> +               if (size)
> +                       count += __free_memory_core(start, start + size);
> +       }
>  #endif
>
>         return count;
> --
> 1.8.4.5
>

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Re: [PATCH V5 1/3] mm/nobootmem: Fix unused variable

[David Rientjes]

On Mon, 20 Jan 2014, Philipp Hachtmann wrote:

> diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> index e2906a5..0215c77 100644
> --- a/mm/nobootmem.c
> +++ b/mm/nobootmem.c
> @@ -116,23 +116,29 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
>  static unsigned long __init free_low_memory_core_early(void)
>  {
>  	unsigned long count = 0;
> -	phys_addr_t start, end, size;
> +	phys_addr_t start, end;
>  	u64 i;
>  
> +#ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
> +	phys_addr_t size;
> +#endif
> +
>  	for_each_free_mem_range(i, NUMA_NO_NODE, &start, &end, NULL)
>  		count += __free_memory_core(start, end);
>  
>  #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
> -
> -	/* Free memblock.reserved array if it was allocated */
> -	size = get_allocated_memblock_reserved_regions_info(&start);
> -	if (size)
> -		count += __free_memory_core(start, start + size);
> -
> -	/* Free memblock.memory array if it was allocated */
> -	size = get_allocated_memblock_memory_regions_info(&start);
> -	if (size)
> -		count += __free_memory_core(start, start + size);
> +	{
> +		phys_addr_t size;

I think you may have misunderstood Andrew's suggestion: "size" here is 
overloading the "size" you have already declared for this configuration.

Not sure why you don't just do a one line patch:

-	phys_addr_t size;
+	phys_addr_t size __maybe_unused;

to fix it.

> +		/* Free memblock.reserved array if it was allocated */
> +		size = get_allocated_memblock_reserved_regions_info(&start);
> +		if (size)
> +			count += __free_memory_core(start, start + size);
> +		
> +		/* Free memblock.memory array if it was allocated */
> +		size = get_allocated_memblock_memory_regions_info(&start);
> +		if (size)
> +			count += __free_memory_core(start, start + size);
> +	}
>  #endif
>  
>  	return count;

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Re: [PATCH V5 1/3] mm/nobootmem: Fix unused variable

[Philipp Hachtmann]

Am Mon, 20 Jan 2014 22:16:33 -0800 (PST)
schrieb David Rientjes <rientjes@google.com>:

> Not sure why you don't just do a one line patch:
> 
> -	phys_addr_t size;
> +	phys_addr_t size __maybe_unused;
> to fix it.

Just because I did not know that __maybe_unused thing.

Discussion of this fix seems to be obsolete because Andrew already took
the patch int the form he suggested: One #ifdef in the function with a
basic block declaring size once inside.

Regards

Philipp

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Re: [PATCH V5 1/3] mm/nobootmem: Fix unused variable

[David Rientjes]

On Tue, 21 Jan 2014, Philipp Hachtmann wrote:

> > Not sure why you don't just do a one line patch:
> > 
> > -	phys_addr_t size;
> > +	phys_addr_t size __maybe_unused;
> > to fix it.
> 
> Just because I did not know that __maybe_unused thing.
> 

-	phys_addr_t size;
+	phys_addr_t size = 0;

would have done the same thing.

The compiler generated code isn't going to change with either of these, so 
we're only talking about how the source code is structured.  If you and 
Andrew believe that adding block scope to something so trivial then that's 
your taste.  Looks ugly to me.

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[PATCH V5 2/3] mm/memblock: Add support for excluded memory areas

[Philipp Hachtmann]

Add a new memory state "nomap" to memblock. This can be used to truncate
the usable memory in the system without forgetting about what is really
installed.

Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
---
 include/linux/memblock.h |  25 +++++++
 mm/Kconfig               |   3 +
 mm/memblock.c            | 175 ++++++++++++++++++++++++++++++++++++++++++++++-
 mm/nobootmem.c           |   8 ++-
 4 files changed, 209 insertions(+), 2 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 1ef6636..be1c819 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -18,6 +18,7 @@
 #include <linux/mm.h>
 
 #define INIT_MEMBLOCK_REGIONS	128
+#define INIT_MEMBLOCK_NOMAP_REGIONS 4
 
 /* Definition of memblock flags. */
 #define MEMBLOCK_HOTPLUG	0x1	/* hotpluggable region */
@@ -43,6 +44,9 @@ struct memblock {
 	phys_addr_t current_limit;
 	struct memblock_type memory;
 	struct memblock_type reserved;
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+	struct memblock_type nomap;
+#endif
 };
 
 extern struct memblock memblock;
@@ -68,6 +72,10 @@ int memblock_add(phys_addr_t base, phys_addr_t size);
 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_ARCH_MEMBLOCK_NOMAP
+int memblock_nomap(phys_addr_t base, phys_addr_t size);
+int memblock_remap(phys_addr_t base, phys_addr_t size);
+#endif
 void memblock_trim_memory(phys_addr_t align);
 int memblock_mark_hotplug(phys_addr_t base, phys_addr_t size);
 int memblock_clear_hotplug(phys_addr_t base, phys_addr_t size);
@@ -133,6 +141,23 @@ void __next_free_mem_range(u64 *idx, int nid, phys_addr_t *out_start,
 	     i != (u64)ULLONG_MAX;					\
 	     __next_free_mem_range(&i, nid, p_start, p_end, p_nid))
 
+
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+#define for_each_mapped_mem_range(i, nid, p_start, p_end, p_nid)	\
+	for (i = 0,							\
+		     __next_mapped_mem_range(&i, nid, &memblock.memory,	\
+				      &memblock.nomap, p_start,		\
+				      p_end, p_nid);			\
+	     i != (u64)ULLONG_MAX;					\
+	     __next_mapped_mem_range(&i, nid, &memblock.memory,		\
+				     &memblock.nomap,			\
+				     p_start, p_end, p_nid))
+
+void __next_mapped_mem_range(u64 *idx, int nid, phys_addr_t *out_start,
+			     phys_addr_t *out_end, int *out_nid);
+
+#endif
+
 void __next_free_mem_range_rev(u64 *idx, int nid, phys_addr_t *out_start,
 			       phys_addr_t *out_end, int *out_nid);
 
diff --git a/mm/Kconfig b/mm/Kconfig
index 2d9f150..6907654 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -137,6 +137,9 @@ config HAVE_MEMBLOCK_NODE_MAP
 config ARCH_DISCARD_MEMBLOCK
 	boolean
 
+config ARCH_MEMBLOCK_NOMAP
+	boolean
+
 config NO_BOOTMEM
 	boolean
 
diff --git a/mm/memblock.c b/mm/memblock.c
index 9c0aeef..b36f5d3 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -28,6 +28,11 @@
 static struct memblock_region memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
 static struct memblock_region memblock_reserved_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
 
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+static struct memblock_region
+memblock_nomap_init_regions[INIT_MEMBLOCK_NOMAP_REGIONS] __initdata_memblock;
+#endif
+
 struct memblock memblock __initdata_memblock = {
 	.memory.regions		= memblock_memory_init_regions,
 	.memory.cnt		= 1,	/* empty dummy entry */
@@ -37,6 +42,11 @@ struct memblock memblock __initdata_memblock = {
 	.reserved.cnt		= 1,	/* empty dummy entry */
 	.reserved.max		= INIT_MEMBLOCK_REGIONS,
 
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+	.nomap.regions       = memblock_nomap_init_regions,
+	.nomap.cnt           = 1,	/* empty dummy entry */
+	.nomap.max           = INIT_MEMBLOCK_NOMAP_REGIONS,
+#endif
 	.bottom_up		= false,
 	.current_limit		= MEMBLOCK_ALLOC_ANYWHERE,
 };
@@ -292,6 +302,20 @@ phys_addr_t __init_memblock get_allocated_memblock_memory_regions_info(
 			  memblock.memory.max);
 }
 
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+phys_addr_t __init_memblock get_allocated_memblock_nomap_regions_info(
+					phys_addr_t *addr)
+{
+	if (memblock.memory.regions == memblock_memory_init_regions)
+		return 0;
+
+	*addr = __pa(memblock.memory.regions);
+
+	return PAGE_ALIGN(sizeof(struct memblock_region) *
+			  memblock.memory.max);
+}
+
+#endif /* CONFIG_ARCH_MEMBLOCK_NOMAP */
 #endif
 
 /**
@@ -757,6 +781,60 @@ int __init_memblock memblock_clear_hotplug(phys_addr_t base, phys_addr_t size)
 	return 0;
 }
 
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+/*
+ * memblock_nomap() - mark a memory range as completely unusable
+ *
+ * This can be used to exclude memory regions from every further treatment
+ * in the running system. Ranges which are added to the nomap list will
+ * also be marked as reserved. So they won't either be allocated by memblock
+ * nor freed to the page allocator.
+ *
+ * The usable (i.e. not in nomap list) memory can be iterated
+ * via for_each_mapped_mem_range().
+ *
+ * memblock_start_of_DRAM() and memblock_end_of_DRAM() still refer to the
+ * whole system memory.
+ */
+int __init_memblock memblock_nomap(phys_addr_t base, phys_addr_t size)
+{
+	int ret;
+	memblock_dbg("memblock_nomap: [%#016llx-%#016llx] %pF\n",
+		     (unsigned long long)base,
+		     (unsigned long long)base + size,
+		     (void *)_RET_IP_);
+
+	ret = memblock_add_region(&memblock.reserved, base,
+				  size, MAX_NUMNODES, 0);
+	if (ret)
+		return ret;
+
+	return memblock_add_region(&memblock.nomap, base,
+				   size, MAX_NUMNODES, 0);
+}
+
+/*
+ * memblock_remap() - remove a memory range from the nomap list
+ *
+ * This is the inverse function to memblock_nomap().
+ */
+int __init_memblock memblock_remap(phys_addr_t base, phys_addr_t size)
+{
+	int ret;
+	memblock_dbg("memblock_remap: [%#016llx-%#016llx] %pF\n",
+		     (unsigned long long)base,
+		     (unsigned long long)base + size,
+		     (void *)_RET_IP_);
+
+	ret = __memblock_remove(&memblock.reserved, base, size);
+	if (ret)
+		return ret;
+
+	return __memblock_remove(&memblock.nomap, base, size);
+}
+
+#endif
+
 /**
  * __next_free_mem_range - next function for for_each_free_mem_range()
  * @idx: pointer to u64 loop variable
@@ -836,6 +914,88 @@ void __init_memblock __next_free_mem_range(u64 *idx, int nid,
 	*idx = ULLONG_MAX;
 }
 
+#ifdef ARCH_MEMBLOCK_NOMAP
+/**
+ * __next_mapped_mem_range - next function for for_each_free_mem_range()
+ * @idx: pointer to u64 loop variable
+ * @nid: node selector, %NUMA_NO_NODE for all nodes
+ * @out_start: ptr to phys_addr_t for start address of the range, can be %NULL
+ * @out_end: ptr to phys_addr_t for end address of the range, can be %NULL
+ * @out_nid: ptr to int for nid of the range, can be %NULL
+ *
+ * Find the first free area from *@idx which matches @nid, fill the out
+ * parameters, and update *@idx for the next iteration.  The lower 32bit of
+ * *@idx contains index into memory region and the upper 32bit indexes the
+ * areas before each reserved region.  For example, if reserved regions
+ * look like the following,
+ *
+ *	0:[0-16), 1:[32-48), 2:[128-130)
+ *
+ * The upper 32bit indexes the following regions.
+ *
+ *	0:[0-0), 1:[16-32), 2:[48-128), 3:[130-MAX)
+ *
+ * As both region arrays are sorted, the function advances the two indices
+ * in lockstep and returns each intersection.
+ */
+void __init_memblock __next_mapped_mem_range(u64 *idx, int nid,
+					   phys_addr_t *out_start,
+					   phys_addr_t *out_end, int *out_nid)
+{
+	struct memblock_type *mem = &memblock.memory;
+	struct memblock_type *rsv = &memblock.nomap;
+	int mi = *idx & 0xffffffff;
+	int ri = *idx >> 32;
+
+	if (WARN_ONCE(nid == MAX_NUMNODES, "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
+		nid = NUMA_NO_NODE;
+
+	for (; mi < mem->cnt; mi++) {
+		struct memblock_region *m = &mem->regions[mi];
+		phys_addr_t m_start = m->base;
+		phys_addr_t m_end = m->base + m->size;
+
+		/* only memory regions are associated with nodes, check it */
+		if (nid != NUMA_NO_NODE && nid != memblock_get_region_node(m))
+			continue;
+
+		/* scan areas before each reservation for intersection */
+		for (; ri < rsv->cnt + 1; ri++) {
+			struct memblock_region *r = &rsv->regions[ri];
+			phys_addr_t r_start = ri ? r[-1].base + r[-1].size : 0;
+			phys_addr_t r_end = ri < rsv->cnt ?
+				r->base : ULLONG_MAX;
+
+			/* if ri advanced past mi, break out to advance mi */
+			if (r_start >= m_end)
+				break;
+			/* if the two regions intersect, we're done */
+			if (m_start < r_end) {
+				if (out_start)
+					*out_start = max(m_start, r_start);
+				if (out_end)
+					*out_end = min(m_end, r_end);
+				if (out_nid)
+					*out_nid = memblock_get_region_node(m);
+				/*
+				 * The region which ends first is advanced
+				 * for the next iteration.
+				 */
+				if (m_end <= r_end)
+					mi++;
+				else
+					ri++;
+				*idx = (u32)mi | (u64)ri << 32;
+				return;
+			}
+		}
+	}
+
+	/* signal end of iteration */
+	*idx = ULLONG_MAX;
+}
+#endif
+
 /**
  * __next_free_mem_range_rev - next function for for_each_free_mem_range_reverse()
  * @idx: pointer to u64 loop variable
@@ -1438,12 +1598,21 @@ static void __init_memblock memblock_dump(struct memblock_type *type, char *name
 void __init_memblock __memblock_dump_all(void)
 {
 	pr_info("MEMBLOCK configuration:\n");
+#ifndef CONFIG_ARCH_MEMBLOCK_NOMAP
 	pr_info(" memory size = %#llx reserved size = %#llx\n",
 		(unsigned long long)memblock.memory.total_size,
 		(unsigned long long)memblock.reserved.total_size);
-
+#else
+	pr_info(" memory size = %#llx reserved size = %#llx nomap size = %#llx\n",
+		(unsigned long long)memblock.memory.total_size,
+		(unsigned long long)memblock.reserved.total_size,
+		(unsigned long long)memblock.nomap.total_size);
+#endif
 	memblock_dump(&memblock.memory, "memory");
 	memblock_dump(&memblock.reserved, "reserved");
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+	memblock_dump(&memblock.nomap, "nomap");
+#endif
 }
 
 void __init memblock_allow_resize(void)
@@ -1502,6 +1671,10 @@ static int __init memblock_init_debugfs(void)
 		return -ENXIO;
 	debugfs_create_file("memory", S_IRUGO, root, &memblock.memory, &memblock_debug_fops);
 	debugfs_create_file("reserved", S_IRUGO, root, &memblock.reserved, &memblock_debug_fops);
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+	debugfs_create_file("nomap", S_IRUGO, root,
+			    &memblock.nomap, &memblock_debug_fops);
+#endif
 
 	return 0;
 }
diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index 0215c77..61966b6 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -138,9 +138,15 @@ static unsigned long __init free_low_memory_core_early(void)
 		size = get_allocated_memblock_memory_regions_info(&start);
 		if (size)
 			count += __free_memory_core(start, start + size);
+
+#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
+	/* Free memblock.nomap array if it was allocated */
+	size = get_allocated_memblock_memory_regions_info(&start);
+	if (size)
+		count += __free_memory_core(start, start + size);
+#endif
 	}
 #endif
-
 	return count;
 }
 
-- 
1.8.4.5

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Re: [PATCH V5 2/3] mm/memblock: Add support for excluded memory areas

[Philipp Hachtmann]

Hi again,

I'd like to remind that the s390 development relies on this patch
(and the next one, for cleanliness, of course) being added. It would be
very good to see it being added to the -mm tree resp. linux-next.

Kind regards

Philipp

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Re: [PATCH V5 2/3] mm/memblock: Add support for excluded memory areas

[Andrew Morton]

On Wed, 22 Jan 2014 12:18:21 +0100 Philipp Hachtmann <phacht@linux.vnet.ibm.com> wrote:

> Hi again,
> 
> I'd like to remind that the s390 development relies on this patch
> (and the next one, for cleanliness, of course) being added. It would be
> very good to see it being added to the -mm tree resp. linux-next.
> 

Once the patch has passed review (hopefully by yinghai, who reviews
very well) I'd ask you to include it in the s390 tree which actually
uses it.

Patch 2/3 would benefit from a more complete changelog.  Why does s390
need CONFIG_ARCH_MEMBLOCK_NOMAP?  How is it used and how does it work? 
Do we expect other architectures to use it?  If so, how?  etcetera.

btw, you have a "#ifdef ARCH_MEMBLOCK_NOMAP" in there which should be
CONFIG_ARCH_MEMBLOCK_NOMAP.  I don't see how the code could have
compiled as-is - __next_mapped_mem_range() will be omitted?

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Re: [PATCH V5 2/3] mm/memblock: Add support for excluded memory areas

[Robin Holt]

The reason I have not responded is I do not see the utility of this patch
and did not feel like I had been engaged enough in the design of whatever
is going to be using this to know if this is the right direction to
go.  As for the
code, it all looks like what I would have done assuming I really needed this.

I don't like the _nomap, because that indicates to too many people too many
different things.  That said, without knowing what this is going to be used
for, the only "better" term I could come up with is _reserved which is more
problematic.  Just as I was getting ready to send this email, I got the
flickering though that memblock_set_unusable()/memblock_set_usable()
might be a better pair of furnctions.

Sorry for coming across as difficult, I just don't feel comfortable with
my understanding of the context for this patch (and I am too lazy to
dig into it further).  I have looked at the prior discussions and I also
don't feel you have addressed the other concerns expressed in
those threads.  I, of course, reserve the right to be wrong.  I nearly
always am.

Thanks and sorry,
Robin Holt


On Mon, Jan 20, 2014 at 5:32 AM, Philipp Hachtmann
<phacht@linux.vnet.ibm.com> wrote:
> Add a new memory state "nomap" to memblock. This can be used to truncate
> the usable memory in the system without forgetting about what is really
> installed.
>
> Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
> ---
>  include/linux/memblock.h |  25 +++++++
>  mm/Kconfig               |   3 +
>  mm/memblock.c            | 175 ++++++++++++++++++++++++++++++++++++++++++++++-
>  mm/nobootmem.c           |   8 ++-
>  4 files changed, 209 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index 1ef6636..be1c819 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -18,6 +18,7 @@
>  #include <linux/mm.h>
>
>  #define INIT_MEMBLOCK_REGIONS  128
> +#define INIT_MEMBLOCK_NOMAP_REGIONS 4

That 4 seems rather arbitrary.  Care to comment on how 4 was determined?

I think SGI has a special purpose driver that might benefit from _nomap
regions.  I will drag Cliff Whickman in to comment on that if he feels
like it.

>  /* Definition of memblock flags. */
>  #define MEMBLOCK_HOTPLUG       0x1     /* hotpluggable region */
> @@ -43,6 +44,9 @@ struct memblock {
>         phys_addr_t current_limit;
>         struct memblock_type memory;
>         struct memblock_type reserved;
> +#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
> +       struct memblock_type nomap;
> +#endif
>  };
>
>  extern struct memblock memblock;
> @@ -68,6 +72,10 @@ int memblock_add(phys_addr_t base, phys_addr_t size);
>  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_ARCH_MEMBLOCK_NOMAP
> +int memblock_nomap(phys_addr_t base, phys_addr_t size);
> +int memblock_remap(phys_addr_t base, phys_addr_t size);

Here is why I dislike _nomap.  The function to reverse the effect becomes
even more misleading.

> +#endif
>  void memblock_trim_memory(phys_addr_t align);
>  int memblock_mark_hotplug(phys_addr_t base, phys_addr_t size);
>  int memblock_clear_hotplug(phys_addr_t base, phys_addr_t size);
> @@ -133,6 +141,23 @@ void __next_free_mem_range(u64 *idx, int nid, phys_addr_t *out_start,
>              i != (u64)ULLONG_MAX;                                      \
>              __next_free_mem_range(&i, nid, p_start, p_end, p_nid))
>
> +
> +#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
> +#define for_each_mapped_mem_range(i, nid, p_start, p_end, p_nid)       \

Again with the name.  To me, the _mapped_ implies there is a virtual to
physical translation or something like that which changes one address
into another, yet both resolve to the same physical memory.

> +       for (i = 0,                                                     \
> +                    __next_mapped_mem_range(&i, nid, &memblock.memory, \
> +                                     &memblock.nomap, p_start,         \
> +                                     p_end, p_nid);                    \
> +            i != (u64)ULLONG_MAX;                                      \
> +            __next_mapped_mem_range(&i, nid, &memblock.memory,         \
> +                                    &memblock.nomap,                   \
> +                                    p_start, p_end, p_nid))
> +
> +void __next_mapped_mem_range(u64 *idx, int nid, phys_addr_t *out_start,
> +                            phys_addr_t *out_end, int *out_nid);
> +
> +#endif
> +
>  void __next_free_mem_range_rev(u64 *idx, int nid, phys_addr_t *out_start,
>                                phys_addr_t *out_end, int *out_nid);
>
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 2d9f150..6907654 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -137,6 +137,9 @@ config HAVE_MEMBLOCK_NODE_MAP
>  config ARCH_DISCARD_MEMBLOCK
>         boolean
>
> +config ARCH_MEMBLOCK_NOMAP
> +       boolean
> +
>  config NO_BOOTMEM
>         boolean
>
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 9c0aeef..b36f5d3 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -28,6 +28,11 @@
>  static struct memblock_region memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
>  static struct memblock_region memblock_reserved_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock;
>
> +#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
> +static struct memblock_region
> +memblock_nomap_init_regions[INIT_MEMBLOCK_NOMAP_REGIONS] __initdata_memblock;
> +#endif
> +
>  struct memblock memblock __initdata_memblock = {
>         .memory.regions         = memblock_memory_init_regions,
>         .memory.cnt             = 1,    /* empty dummy entry */
> @@ -37,6 +42,11 @@ struct memblock memblock __initdata_memblock = {
>         .reserved.cnt           = 1,    /* empty dummy entry */
>         .reserved.max           = INIT_MEMBLOCK_REGIONS,
>
> +#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
> +       .nomap.regions       = memblock_nomap_init_regions,
> +       .nomap.cnt           = 1,       /* empty dummy entry */
> +       .nomap.max           = INIT_MEMBLOCK_NOMAP_REGIONS,
> +#endif
>         .bottom_up              = false,
>         .current_limit          = MEMBLOCK_ALLOC_ANYWHERE,
>  };
> @@ -292,6 +302,20 @@ phys_addr_t __init_memblock get_allocated_memblock_memory_regions_info(
>                           memblock.memory.max);
>  }
>
> +#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
> +phys_addr_t __init_memblock get_allocated_memblock_nomap_regions_info(
> +                                       phys_addr_t *addr)
> +{
> +       if (memblock.memory.regions == memblock_memory_init_regions)
> +               return 0;
> +
> +       *addr = __pa(memblock.memory.regions);
> +
> +       return PAGE_ALIGN(sizeof(struct memblock_region) *
> +                         memblock.memory.max);
> +}
> +
> +#endif /* CONFIG_ARCH_MEMBLOCK_NOMAP */
>  #endif
>
>  /**
> @@ -757,6 +781,60 @@ int __init_memblock memblock_clear_hotplug(phys_addr_t base, phys_addr_t size)
>         return 0;
>  }
>
> +#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
> +/*
> + * memblock_nomap() - mark a memory range as completely unusable
> + *
> + * This can be used to exclude memory regions from every further treatment
> + * in the running system. Ranges which are added to the nomap list will
> + * also be marked as reserved. So they won't either be allocated by memblock
> + * nor freed to the page allocator.
> + *
> + * The usable (i.e. not in nomap list) memory can be iterated
> + * via for_each_mapped_mem_range().
> + *
> + * memblock_start_of_DRAM() and memblock_end_of_DRAM() still refer to the
> + * whole system memory.
> + */
> +int __init_memblock memblock_nomap(phys_addr_t base, phys_addr_t size)
> +{
> +       int ret;
> +       memblock_dbg("memblock_nomap: [%#016llx-%#016llx] %pF\n",
> +                    (unsigned long long)base,
> +                    (unsigned long long)base + size,
> +                    (void *)_RET_IP_);

Personally, I never like using _RET_IP, but that might just be me.  Since it is
already used in equivalent functions, I would not try to argue against using
it here.

> +
> +       ret = memblock_add_region(&memblock.reserved, base,
> +                                 size, MAX_NUMNODES, 0);
> +       if (ret)
> +               return ret;
> +
> +       return memblock_add_region(&memblock.nomap, base,
> +                                  size, MAX_NUMNODES, 0);
> +}
> +
> +/*
> + * memblock_remap() - remove a memory range from the nomap list
> + *
> + * This is the inverse function to memblock_nomap().

Shouldn't this really be the "reverse" function?

> + */
> +int __init_memblock memblock_remap(phys_addr_t base, phys_addr_t size)
> +{
> +       int ret;
> +       memblock_dbg("memblock_remap: [%#016llx-%#016llx] %pF\n",
> +                    (unsigned long long)base,
> +                    (unsigned long long)base + size,
> +                    (void *)_RET_IP_);
> +
> +       ret = __memblock_remove(&memblock.reserved, base, size);
> +       if (ret)
> +               return ret;
> +
> +       return __memblock_remove(&memblock.nomap, base, size);
> +}
> +
> +#endif
> +
>  /**
>   * __next_free_mem_range - next function for for_each_free_mem_range()
>   * @idx: pointer to u64 loop variable
> @@ -836,6 +914,88 @@ void __init_memblock __next_free_mem_range(u64 *idx, int nid,
>         *idx = ULLONG_MAX;
>  }
>
> +#ifdef ARCH_MEMBLOCK_NOMAP
> +/**
> + * __next_mapped_mem_range - next function for for_each_free_mem_range()
> + * @idx: pointer to u64 loop variable
> + * @nid: node selector, %NUMA_NO_NODE for all nodes
> + * @out_start: ptr to phys_addr_t for start address of the range, can be %NULL
> + * @out_end: ptr to phys_addr_t for end address of the range, can be %NULL
> + * @out_nid: ptr to int for nid of the range, can be %NULL
> + *
> + * Find the first free area from *@idx which matches @nid, fill the out
> + * parameters, and update *@idx for the next iteration.  The lower 32bit of
> + * *@idx contains index into memory region and the upper 32bit indexes the
> + * areas before each reserved region.  For example, if reserved regions
> + * look like the following,
> + *
> + *     0:[0-16), 1:[32-48), 2:[128-130)
> + *
> + * The upper 32bit indexes the following regions.
> + *
> + *     0:[0-0), 1:[16-32), 2:[48-128), 3:[130-MAX)
> + *
> + * As both region arrays are sorted, the function advances the two indices
> + * in lockstep and returns each intersection.
> + */
> +void __init_memblock __next_mapped_mem_range(u64 *idx, int nid,
> +                                          phys_addr_t *out_start,
> +                                          phys_addr_t *out_end, int *out_nid)
> +{
> +       struct memblock_type *mem = &memblock.memory;
> +       struct memblock_type *rsv = &memblock.nomap;
> +       int mi = *idx & 0xffffffff;
> +       int ri = *idx >> 32;
> +
> +       if (WARN_ONCE(nid == MAX_NUMNODES, "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
> +               nid = NUMA_NO_NODE;
> +
> +       for (; mi < mem->cnt; mi++) {
> +               struct memblock_region *m = &mem->regions[mi];
> +               phys_addr_t m_start = m->base;
> +               phys_addr_t m_end = m->base + m->size;
> +
> +               /* only memory regions are associated with nodes, check it */
> +               if (nid != NUMA_NO_NODE && nid != memblock_get_region_node(m))
> +                       continue;
> +
> +               /* scan areas before each reservation for intersection */
> +               for (; ri < rsv->cnt + 1; ri++) {
> +                       struct memblock_region *r = &rsv->regions[ri];
> +                       phys_addr_t r_start = ri ? r[-1].base + r[-1].size : 0;
> +                       phys_addr_t r_end = ri < rsv->cnt ?
> +                               r->base : ULLONG_MAX;
> +
> +                       /* if ri advanced past mi, break out to advance mi */
> +                       if (r_start >= m_end)
> +                               break;
> +                       /* if the two regions intersect, we're done */
> +                       if (m_start < r_end) {
> +                               if (out_start)
> +                                       *out_start = max(m_start, r_start);
> +                               if (out_end)
> +                                       *out_end = min(m_end, r_end);
> +                               if (out_nid)
> +                                       *out_nid = memblock_get_region_node(m);
> +                               /*
> +                                * The region which ends first is advanced
> +                                * for the next iteration.
> +                                */
> +                               if (m_end <= r_end)
> +                                       mi++;
> +                               else
> +                                       ri++;
> +                               *idx = (u32)mi | (u64)ri << 32;
> +                               return;
> +                       }
> +               }
> +       }
> +
> +       /* signal end of iteration */
> +       *idx = ULLONG_MAX;
> +}
> +#endif
> +
>  /**
>   * __next_free_mem_range_rev - next function for for_each_free_mem_range_reverse()
>   * @idx: pointer to u64 loop variable
> @@ -1438,12 +1598,21 @@ static void __init_memblock memblock_dump(struct memblock_type *type, char *name
>  void __init_memblock __memblock_dump_all(void)
>  {
>         pr_info("MEMBLOCK configuration:\n");
> +#ifndef CONFIG_ARCH_MEMBLOCK_NOMAP
>         pr_info(" memory size = %#llx reserved size = %#llx\n",
>                 (unsigned long long)memblock.memory.total_size,
>                 (unsigned long long)memblock.reserved.total_size);
> -
> +#else
> +       pr_info(" memory size = %#llx reserved size = %#llx nomap size = %#llx\n",
> +               (unsigned long long)memblock.memory.total_size,
> +               (unsigned long long)memblock.reserved.total_size,
> +               (unsigned long long)memblock.nomap.total_size);
> +#endif
>         memblock_dump(&memblock.memory, "memory");
>         memblock_dump(&memblock.reserved, "reserved");
> +#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
> +       memblock_dump(&memblock.nomap, "nomap");
> +#endif
>  }
>
>  void __init memblock_allow_resize(void)
> @@ -1502,6 +1671,10 @@ static int __init memblock_init_debugfs(void)
>                 return -ENXIO;
>         debugfs_create_file("memory", S_IRUGO, root, &memblock.memory, &memblock_debug_fops);
>         debugfs_create_file("reserved", S_IRUGO, root, &memblock.reserved, &memblock_debug_fops);
> +#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
> +       debugfs_create_file("nomap", S_IRUGO, root,
> +                           &memblock.nomap, &memblock_debug_fops);
> +#endif
>
>         return 0;
>  }
> diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> index 0215c77..61966b6 100644
> --- a/mm/nobootmem.c
> +++ b/mm/nobootmem.c
> @@ -138,9 +138,15 @@ static unsigned long __init free_low_memory_core_early(void)
>                 size = get_allocated_memblock_memory_regions_info(&start);
>                 if (size)
>                         count += __free_memory_core(start, start + size);
> +
> +#ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
> +       /* Free memblock.nomap array if it was allocated */
> +       size = get_allocated_memblock_memory_regions_info(&start);
> +       if (size)
> +               count += __free_memory_core(start, start + size);
> +#endif
>         }
>  #endif
> -
>         return count;
>  }
>
> --
> 1.8.4.5
>

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[PATCH V5 3/3] mm/memblock: Cleanup and refactoring after addition of nomap

[Philipp Hachtmann]

Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
---
 include/linux/memblock.h |  50 ++++++-----
 mm/memblock.c            | 214 +++++++++++++++++------------------------------
 2 files changed, 107 insertions(+), 157 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index be1c819..ec2da3b 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -121,8 +121,9 @@ void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn,
 	     i >= 0; __next_mem_pfn_range(&i, nid, p_start, p_end, p_nid))
 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
 
-void __next_free_mem_range(u64 *idx, int nid, phys_addr_t *out_start,
-			   phys_addr_t *out_end, int *out_nid);
+void __next_mem_range(u64 *idx, int nid, struct memblock_type *type_a,
+		      struct memblock_type *type_b, phys_addr_t *out_start,
+		      phys_addr_t *out_end, int *out_nid);
 
 /**
  * for_each_free_mem_range - iterate through free memblock areas
@@ -137,29 +138,31 @@ void __next_free_mem_range(u64 *idx, int nid, phys_addr_t *out_start,
  */
 #define for_each_free_mem_range(i, nid, p_start, p_end, p_nid)		\
 	for (i = 0,							\
-	     __next_free_mem_range(&i, nid, p_start, p_end, p_nid);	\
+		     __next_mem_range(&i, nid, &memblock.memory,	\
+				      &memblock.reserved, p_start,	\
+				      p_end, p_nid);			\
 	     i != (u64)ULLONG_MAX;					\
-	     __next_free_mem_range(&i, nid, p_start, p_end, p_nid))
-
+	     __next_mem_range(&i, nid, &memblock.memory,		\
+			      &memblock.reserved,			\
+			      p_start, p_end, p_nid))
 
 #ifdef CONFIG_ARCH_MEMBLOCK_NOMAP
 #define for_each_mapped_mem_range(i, nid, p_start, p_end, p_nid)	\
 	for (i = 0,							\
-		     __next_mapped_mem_range(&i, nid, &memblock.memory,	\
+		     __next_mem_range(&i, nid, &memblock.memory,	\
 				      &memblock.nomap, p_start,		\
 				      p_end, p_nid);			\
 	     i != (u64)ULLONG_MAX;					\
-	     __next_mapped_mem_range(&i, nid, &memblock.memory,		\
-				     &memblock.nomap,			\
-				     p_start, p_end, p_nid))
-
-void __next_mapped_mem_range(u64 *idx, int nid, phys_addr_t *out_start,
-			     phys_addr_t *out_end, int *out_nid);
-
+	     __next_mem_range(&i, nid, &memblock.memory,		\
+			      &memblock.nomap,				\
+			      p_start, p_end, p_nid))
 #endif
 
-void __next_free_mem_range_rev(u64 *idx, int nid, phys_addr_t *out_start,
-			       phys_addr_t *out_end, int *out_nid);
+void __next_mem_range_rev(u64 *idx, int nid,
+					  struct memblock_type *type_a,
+					  struct memblock_type *type_b,
+					  phys_addr_t *out_start,
+					  phys_addr_t *out_end, int *out_nid);
 
 /**
  * for_each_free_mem_range_reverse - rev-iterate through free memblock areas
@@ -174,9 +177,15 @@ void __next_free_mem_range_rev(u64 *idx, int nid, phys_addr_t *out_start,
  */
 #define for_each_free_mem_range_reverse(i, nid, p_start, p_end, p_nid)	\
 	for (i = (u64)ULLONG_MAX,					\
-	     __next_free_mem_range_rev(&i, nid, p_start, p_end, p_nid);	\
+		     __next_mem_range_rev(&i, nid,			\
+					  &memblock.memory,		\
+					  &memblock.reserved,		\
+					  p_start, p_end, p_nid);	\
 	     i != (u64)ULLONG_MAX;					\
-	     __next_free_mem_range_rev(&i, nid, p_start, p_end, p_nid))
+	     __next_mem_range_rev(&i, nid,				\
+				  &memblock.memory,			\
+				  &memblock.reserved,			\
+				  p_start, p_end, p_nid))
 
 static inline void memblock_set_region_flags(struct memblock_region *r,
 					     unsigned long flags)
@@ -321,12 +330,11 @@ static inline unsigned long memblock_region_reserved_end_pfn(const struct memblo
 	return PFN_UP(reg->base + reg->size);
 }
 
-#define for_each_memblock(memblock_type, region)					\
-	for (region = memblock.memblock_type.regions;				\
-	     region < (memblock.memblock_type.regions + memblock.memblock_type.cnt);	\
+#define for_each_memblock(type_name, region)				\
+	for (region = memblock.type_name.regions;			\
+	     region < (memblock.type_name.regions + memblock.type_name.cnt); \
 	     region++)
 
-
 #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
 #define __init_memblock __meminit
 #define __initdata_memblock __meminitdata
diff --git a/mm/memblock.c b/mm/memblock.c
index b36f5d3..dd6fd6f 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -836,97 +836,23 @@ int __init_memblock memblock_remap(phys_addr_t base, phys_addr_t size)
 #endif
 
 /**
- * __next_free_mem_range - next function for for_each_free_mem_range()
- * @idx: pointer to u64 loop variable
- * @nid: node selector, %NUMA_NO_NODE for all nodes
- * @out_start: ptr to phys_addr_t for start address of the range, can be %NULL
- * @out_end: ptr to phys_addr_t for end address of the range, can be %NULL
- * @out_nid: ptr to int for nid of the range, can be %NULL
- *
- * Find the first free area from *@idx which matches @nid, fill the out
- * parameters, and update *@idx for the next iteration.  The lower 32bit of
- * *@idx contains index into memory region and the upper 32bit indexes the
- * areas before each reserved region.  For example, if reserved regions
- * look like the following,
- *
- *	0:[0-16), 1:[32-48), 2:[128-130)
+ * __next_mem_range - generic next function for for_each_*_range()
  *
- * The upper 32bit indexes the following regions.
+ * Finds the next range from type_a which is not marked as unsuitable
+ * in type_b.
  *
- *	0:[0-0), 1:[16-32), 2:[48-128), 3:[130-MAX)
- *
- * As both region arrays are sorted, the function advances the two indices
- * in lockstep and returns each intersection.
- */
-void __init_memblock __next_free_mem_range(u64 *idx, int nid,
-					   phys_addr_t *out_start,
-					   phys_addr_t *out_end, int *out_nid)
-{
-	struct memblock_type *mem = &memblock.memory;
-	struct memblock_type *rsv = &memblock.reserved;
-	int mi = *idx & 0xffffffff;
-	int ri = *idx >> 32;
-
-	if (WARN_ONCE(nid == MAX_NUMNODES, "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
-		nid = NUMA_NO_NODE;
-
-	for ( ; mi < mem->cnt; mi++) {
-		struct memblock_region *m = &mem->regions[mi];
-		phys_addr_t m_start = m->base;
-		phys_addr_t m_end = m->base + m->size;
-
-		/* only memory regions are associated with nodes, check it */
-		if (nid != NUMA_NO_NODE && nid != memblock_get_region_node(m))
-			continue;
-
-		/* scan areas before each reservation for intersection */
-		for ( ; ri < rsv->cnt + 1; ri++) {
-			struct memblock_region *r = &rsv->regions[ri];
-			phys_addr_t r_start = ri ? r[-1].base + r[-1].size : 0;
-			phys_addr_t r_end = ri < rsv->cnt ? r->base : ULLONG_MAX;
-
-			/* if ri advanced past mi, break out to advance mi */
-			if (r_start >= m_end)
-				break;
-			/* if the two regions intersect, we're done */
-			if (m_start < r_end) {
-				if (out_start)
-					*out_start = max(m_start, r_start);
-				if (out_end)
-					*out_end = min(m_end, r_end);
-				if (out_nid)
-					*out_nid = memblock_get_region_node(m);
-				/*
-				 * The region which ends first is advanced
-				 * for the next iteration.
-				 */
-				if (m_end <= r_end)
-					mi++;
-				else
-					ri++;
-				*idx = (u32)mi | (u64)ri << 32;
-				return;
-			}
-		}
-	}
-
-	/* signal end of iteration */
-	*idx = ULLONG_MAX;
-}
-
-#ifdef ARCH_MEMBLOCK_NOMAP
-/**
- * __next_mapped_mem_range - next function for for_each_free_mem_range()
  * @idx: pointer to u64 loop variable
  * @nid: node selector, %NUMA_NO_NODE for all nodes
+ * @type_a: pointer to memblock_type from where the range is taken
+ * @type_b: pointer to memblock_type which excludes memory from being taken
  * @out_start: ptr to phys_addr_t for start address of the range, can be %NULL
  * @out_end: ptr to phys_addr_t for end address of the range, can be %NULL
  * @out_nid: ptr to int for nid of the range, can be %NULL
  *
- * Find the first free area from *@idx which matches @nid, fill the out
+ * Find the first present area from *@idx which matches @nid, fill the out
  * parameters, and update *@idx for the next iteration.  The lower 32bit of
- * *@idx contains index into memory region and the upper 32bit indexes the
- * areas before each reserved region.  For example, if reserved regions
+ * *@idx contains index into type_a region and the upper 32bit indexes the
+ * areas before each type_b region.  For example, if type_a regions
  * look like the following,
  *
  *	0:[0-16), 1:[32-48), 2:[128-130)
@@ -938,98 +864,107 @@ void __init_memblock __next_free_mem_range(u64 *idx, int nid,
  * As both region arrays are sorted, the function advances the two indices
  * in lockstep and returns each intersection.
  */
-void __init_memblock __next_mapped_mem_range(u64 *idx, int nid,
-					   phys_addr_t *out_start,
-					   phys_addr_t *out_end, int *out_nid)
+void __init_memblock __next_mem_range(u64 *idx, int nid,
+				      struct memblock_type *type_a,
+				      struct memblock_type *type_b,
+				      phys_addr_t *out_start,
+				      phys_addr_t *out_end, int *out_nid)
 {
-	struct memblock_type *mem = &memblock.memory;
-	struct memblock_type *rsv = &memblock.nomap;
-	int mi = *idx & 0xffffffff;
-	int ri = *idx >> 32;
+	int idx_a = *idx & 0xffffffff;
+	int idx_b = *idx >> 32;
 
 	if (WARN_ONCE(nid == MAX_NUMNODES, "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
 		nid = NUMA_NO_NODE;
 
-	for (; mi < mem->cnt; mi++) {
-		struct memblock_region *m = &mem->regions[mi];
+	for (; idx_a < type_a->cnt; idx_a++) {
+		struct memblock_region *m = &type_a->regions[idx_a];
 		phys_addr_t m_start = m->base;
 		phys_addr_t m_end = m->base + m->size;
+		int         m_nid = memblock_get_region_node(m);
 
 		/* only memory regions are associated with nodes, check it */
 		if (nid != NUMA_NO_NODE && nid != memblock_get_region_node(m))
 			continue;
 
-		/* scan areas before each reservation for intersection */
-		for (; ri < rsv->cnt + 1; ri++) {
-			struct memblock_region *r = &rsv->regions[ri];
-			phys_addr_t r_start = ri ? r[-1].base + r[-1].size : 0;
-			phys_addr_t r_end = ri < rsv->cnt ?
+		/* scan areas before each reservation */
+		for (; idx_b < type_b->cnt + 1; idx_b++) {
+			struct memblock_region *r;
+			phys_addr_t r_start;
+			phys_addr_t r_end;
+
+			r = &type_b->regions[idx_b];
+			r_start = idx_b ? r[-1].base + r[-1].size : 0;
+			r_end = idx_b < type_b->cnt ?
 				r->base : ULLONG_MAX;
 
-			/* if ri advanced past mi, break out to advance mi */
+			/*
+			 *if idx_b advanced past idx_a,
+			 * break out to advance idx_a
+			 */
 			if (r_start >= m_end)
 				break;
 			/* if the two regions intersect, we're done */
 			if (m_start < r_end) {
 				if (out_start)
-					*out_start = max(m_start, r_start);
+					*out_start =
+						max(m_start, r_start);
 				if (out_end)
 					*out_end = min(m_end, r_end);
 				if (out_nid)
-					*out_nid = memblock_get_region_node(m);
+					*out_nid = m_nid;
+
 				/*
-				 * The region which ends first is advanced
-				 * for the next iteration.
+				 * The region which ends first is
+				 * advanced for the next iteration.
 				 */
 				if (m_end <= r_end)
-					mi++;
+					idx_a++;
 				else
-					ri++;
-				*idx = (u32)mi | (u64)ri << 32;
+					idx_b++;
+				*idx = (u32)idx_a | (u64)idx_b << 32;
 				return;
 			}
 		}
 	}
-
 	/* signal end of iteration */
 	*idx = ULLONG_MAX;
 }
-#endif
 
 /**
- * __next_free_mem_range_rev - next function for for_each_free_mem_range_reverse()
+ * __next_mem_range_rev - generic next function for for_each_*_range_rev()
+ *
+ * Finds the next range from type_a which is not marked as unsuitable
+ * in type_b.
+ *
  * @idx: pointer to u64 loop variable
  * @nid: nid: node selector, %NUMA_NO_NODE for all nodes
+ * @type_a: pointer to memblock_type from where the range is taken
+ * @type_b: pointer to memblock_type which excludes memory from being taken
  * @out_start: ptr to phys_addr_t for start address of the range, can be %NULL
  * @out_end: ptr to phys_addr_t for end address of the range, can be %NULL
  * @out_nid: ptr to int for nid of the range, can be %NULL
  *
- * Reverse of __next_free_mem_range().
- *
- * Linux kernel cannot migrate pages used by itself. Memory hotplug users won't
- * be able to hot-remove hotpluggable memory used by the kernel. So this
- * function skip hotpluggable regions if needed when allocating memory for the
- * kernel.
+ * Reverse of __next_mem_range().
  */
-void __init_memblock __next_free_mem_range_rev(u64 *idx, int nid,
-					   phys_addr_t *out_start,
-					   phys_addr_t *out_end, int *out_nid)
+void __init_memblock __next_mem_range_rev(u64 *idx, int nid,
+					  struct memblock_type *type_a,
+					  struct memblock_type *type_b,
+					  phys_addr_t *out_start,
+					  phys_addr_t *out_end, int *out_nid)
 {
-	struct memblock_type *mem = &memblock.memory;
-	struct memblock_type *rsv = &memblock.reserved;
-	int mi = *idx & 0xffffffff;
-	int ri = *idx >> 32;
+	int idx_a = *idx & 0xffffffff;
+	int idx_b = *idx >> 32;
 
 	if (WARN_ONCE(nid == MAX_NUMNODES, "Usage of MAX_NUMNODES is deprecated. Use NUMA_NO_NODE instead\n"))
 		nid = NUMA_NO_NODE;
 
 	if (*idx == (u64)ULLONG_MAX) {
-		mi = mem->cnt - 1;
-		ri = rsv->cnt;
+		idx_a = type_a->cnt - 1;
+		idx_b = type_b->cnt;
 	}
 
-	for ( ; mi >= 0; mi--) {
-		struct memblock_region *m = &mem->regions[mi];
+	for (; idx_a >= 0; idx_a--) {
+		struct memblock_region *m = &type_a->regions[idx_a];
 		phys_addr_t m_start = m->base;
 		phys_addr_t m_end = m->base + m->size;
 
@@ -1041,13 +976,21 @@ void __init_memblock __next_free_mem_range_rev(u64 *idx, int nid,
 		if (movable_node_is_enabled() && memblock_is_hotpluggable(m))
 			continue;
 
-		/* scan areas before each reservation for intersection */
-		for ( ; ri >= 0; ri--) {
-			struct memblock_region *r = &rsv->regions[ri];
-			phys_addr_t r_start = ri ? r[-1].base + r[-1].size : 0;
-			phys_addr_t r_end = ri < rsv->cnt ? r->base : ULLONG_MAX;
+		/* scan areas before each reservation */
+		for (; idx_b >= 0; idx_b--) {
+			struct memblock_region *r;
+			phys_addr_t r_start;
+			phys_addr_t r_end;
+			int m_nid = memblock_get_region_node(m);
 
-			/* if ri advanced past mi, break out to advance mi */
+			r = &type_b->regions[idx_b];
+			r_start = idx_b ? r[-1].base + r[-1].size : 0;
+			r_end = idx_b < type_b->cnt ?
+				r->base : ULLONG_MAX;
+			/*
+			 * if idx_b advanced past idx_a,
+			 * break out to advance idx_a
+			 */
 			if (r_end <= m_start)
 				break;
 			/* if the two regions intersect, we're done */
@@ -1057,18 +1000,17 @@ void __init_memblock __next_free_mem_range_rev(u64 *idx, int nid,
 				if (out_end)
 					*out_end = min(m_end, r_end);
 				if (out_nid)
-					*out_nid = memblock_get_region_node(m);
-
+					*out_nid = m_nid;
 				if (m_start >= r_start)
-					mi--;
+					idx_a--;
 				else
-					ri--;
-				*idx = (u32)mi | (u64)ri << 32;
+					idx_b--;
+				*idx = (u32)idx_a | (u64)idx_b << 32;
 				return;
 			}
 		}
 	}
-
+	/* signal end of iteration */
 	*idx = ULLONG_MAX;
 }
 
-- 
1.8.4.5

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