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Subject[PATCH v3 1/5] mm,memory_hotplug: Introduce MHP_MEMMAP_ON_MEMORY
Date
This patch introduces MHP_MEMMAP_ON_MEMORY flag,
and prepares the callers that add memory to take a "flags" parameter.
This "flags" parameter will be evaluated later on in Patch#3
to init mhp_restrictions struct.

The callers are:

add_memory
__add_memory
add_memory_resource

Unfortunately, we do not have a single entry point to add memory, as depending
on the requisites of the caller, they want to hook up in different places,
(e.g: Xen reserve_additional_memory()), so we have to spread the parameter
in the three callers.

MHP_MEMMAP_ON_MEMORY flag parameter will specify to allocate memmaps
from the hot-added range.
If callers wants memmaps to be allocated per memory block, it will
have to call add_memory() variants in memory-block granularity
spanning the whole range, while if it wants to allocate memmaps
per whole memory range, just one call will do.

Want to add 384MB (3 sections, 3 memory-blocks)
e.g:

add_memory(0x1000, size_memory_block);
add_memory(0x2000, size_memory_block);
add_memory(0x3000, size_memory_block);

[memblock#0 ]
[0 - 511 pfns ] - vmemmaps for section#0
[512 - 32767 pfns ] - normal memory

[memblock#1 ]
[32768 - 33279 pfns] - vmemmaps for section#1
[33280 - 65535 pfns] - normal memory

[memblock#2 ]
[65536 - 66047 pfns] - vmemmap for section#2
[66048 - 98304 pfns] - normal memory

or
add_memory(0x1000, size_memory_block * 3);

[memblock #0 ]
[0 - 1533 pfns ] - vmemmap for section#{0-2}
[1534 - 98304 pfns] - normal memory

When using larger memory blocks (1GB or 2GB), the principle is the same.

Of course, per whole-range granularity is nicer when it comes to have a large
contigous area, while per memory-block granularity allows us to have flexibility
when removing the memory.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
---
drivers/acpi/acpi_memhotplug.c | 2 +-
drivers/base/memory.c | 2 +-
drivers/dax/kmem.c | 2 +-
drivers/hv/hv_balloon.c | 2 +-
drivers/s390/char/sclp_cmd.c | 2 +-
drivers/xen/balloon.c | 2 +-
include/linux/memory_hotplug.h | 25 ++++++++++++++++++++++---
mm/memory_hotplug.c | 10 +++++-----
8 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index e294f44a7850..d91b3584d4b2 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -207,7 +207,7 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
if (node < 0)
node = memory_add_physaddr_to_nid(info->start_addr);

- result = __add_memory(node, info->start_addr, info->length);
+ result = __add_memory(node, info->start_addr, info->length, 0);

/*
* If the memory block has been used by the kernel, add_memory()
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 154d5d4a0779..d30d0f6c8ad0 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -521,7 +521,7 @@ static ssize_t probe_store(struct device *dev, struct device_attribute *attr,

nid = memory_add_physaddr_to_nid(phys_addr);
ret = __add_memory(nid, phys_addr,
- MIN_MEMORY_BLOCK_SIZE * sections_per_block);
+ MIN_MEMORY_BLOCK_SIZE * sections_per_block, 0);

if (ret)
goto out;
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 3d0a7e702c94..e159184e0ba0 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -65,7 +65,7 @@ int dev_dax_kmem_probe(struct device *dev)
new_res->flags = IORESOURCE_SYSTEM_RAM;
new_res->name = dev_name(dev);

- rc = add_memory(numa_node, new_res->start, resource_size(new_res));
+ rc = add_memory(numa_node, new_res->start, resource_size(new_res), 0);
if (rc) {
release_resource(new_res);
kfree(new_res);
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 6fb4ea5f0304..beb92bc56186 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -731,7 +731,7 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size,

nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));
ret = add_memory(nid, PFN_PHYS((start_pfn)),
- (HA_CHUNK << PAGE_SHIFT));
+ (HA_CHUNK << PAGE_SHIFT), 0);

if (ret) {
pr_err("hot_add memory failed error is %d\n", ret);
diff --git a/drivers/s390/char/sclp_cmd.c b/drivers/s390/char/sclp_cmd.c
index 37d42de06079..f61026c7db7e 100644
--- a/drivers/s390/char/sclp_cmd.c
+++ b/drivers/s390/char/sclp_cmd.c
@@ -406,7 +406,7 @@ static void __init add_memory_merged(u16 rn)
if (!size)
goto skip_add;
for (addr = start; addr < start + size; addr += block_size)
- add_memory(numa_pfn_to_nid(PFN_DOWN(addr)), addr, block_size);
+ add_memory(numa_pfn_to_nid(PFN_DOWN(addr)), addr, block_size, 0);
skip_add:
first_rn = rn;
num = 1;
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 4e11de6cde81..e4934ce40478 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -349,7 +349,7 @@ static enum bp_state reserve_additional_memory(void)
mutex_unlock(&balloon_mutex);
/* add_memory_resource() requires the device_hotplug lock */
lock_device_hotplug();
- rc = add_memory_resource(nid, resource);
+ rc = add_memory_resource(nid, resource, 0);
unlock_device_hotplug();
mutex_lock(&balloon_mutex);

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index f46ea71b4ffd..45dece922d7c 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -54,6 +54,25 @@ enum {
};

/*
+ * We want memmap (struct page array) to be allocated from the hotadded range.
+ * To do so, there are two possible ways depending on what the caller wants.
+ * 1) Allocate memmap pages whole hot-added range.
+ * Here the caller will only call any add_memory() variant with the whole
+ * memory address.
+ * 2) Allocate memmap pages per memblock
+ * Here, the caller will call any add_memory() variant per memblock
+ * granularity.
+ * The former implies that we will use the beginning of the hot-added range
+ * to store the memmap pages of the whole range, while the latter implies
+ * that we will use the beginning of each memblock to store its own memmap
+ * pages.
+ *
+ * Please note that this is only a hint, not a guarantee. Only selected
+ * architectures support it with SPARSE_VMEMMAP.
+ */
+#define MHP_MEMMAP_ON_MEMORY (1UL<<1)
+
+/*
* Restrictions for the memory hotplug:
* flags: MHP_ flags
* altmap: alternative allocator for memmap array
@@ -340,9 +359,9 @@ static inline void __remove_memory(int nid, u64 start, u64 size) {}
#endif /* CONFIG_MEMORY_HOTREMOVE */

extern void __ref free_area_init_core_hotplug(int nid);
-extern int __add_memory(int nid, u64 start, u64 size);
-extern int add_memory(int nid, u64 start, u64 size);
-extern int add_memory_resource(int nid, struct resource *resource);
+extern int __add_memory(int nid, u64 start, u64 size, unsigned long flags);
+extern int add_memory(int nid, u64 start, u64 size, unsigned long flags);
+extern int add_memory_resource(int nid, struct resource *resource, unsigned long flags);
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);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9a82e12bd0e7..3d97c3711333 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1046,7 +1046,7 @@ static int online_memory_block(struct memory_block *mem, void *arg)
*
* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG
*/
-int __ref add_memory_resource(int nid, struct resource *res)
+int __ref add_memory_resource(int nid, struct resource *res, unsigned long flags)
{
struct mhp_restrictions restrictions = {};
u64 start, size;
@@ -1123,7 +1123,7 @@ int __ref add_memory_resource(int nid, struct resource *res)
}

/* requires device_hotplug_lock, see add_memory_resource() */
-int __ref __add_memory(int nid, u64 start, u64 size)
+int __ref __add_memory(int nid, u64 start, u64 size, unsigned long flags)
{
struct resource *res;
int ret;
@@ -1132,18 +1132,18 @@ int __ref __add_memory(int nid, u64 start, u64 size)
if (IS_ERR(res))
return PTR_ERR(res);

- ret = add_memory_resource(nid, res);
+ ret = add_memory_resource(nid, res, flags);
if (ret < 0)
release_memory_resource(res);
return ret;
}

-int add_memory(int nid, u64 start, u64 size)
+int add_memory(int nid, u64 start, u64 size, unsigned long flags)
{
int rc;

lock_device_hotplug();
- rc = __add_memory(nid, start, size);
+ rc = __add_memory(nid, start, size, flags);
unlock_device_hotplug();

return rc;
--
2.12.3
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