Date:   Fri, 27 Jan 2017 17:52:08 -0500
From:   Jérôme Glisse <jglisse@...hat.com>
To:     akpm@...ux-foundation.org, <linux-kernel@...r.kernel.org>,
        linux-mm@...ck.org
Cc:     John Hubbard <jhubbard@...dia.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        David Nellans <dnellans@...dia.com>,
        Jérôme Glisse <jglisse@...hat.com>,
        Russell King <linux@...linux.org.uk>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [HMM v17 01/14] mm/memory/hotplug: convert device bool to int to allow for more flags v2

When hotpluging memory we want more informations on the type of memory and
its properties. Replace the device boolean flag by an int and define a set
of flags.

New property for device memory is an opt-in flag to allow page migration
from and to a ZONE_DEVICE. Existing user of ZONE_DEVICE are not expecting
page migration to work for their pages. New changes to page migration i
changing that and we now need a flag to explicitly opt-in page migration.

Changes since v1:
  - Improved commit message
  - Improved define name
  - Improved comments
  - Typos

Signed-off-by: Jérôme Glisse <jglisse@...hat.com>
Cc: Russell King <linux@...linux.org.uk>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Yoshinori Sato <ysato@...rs.sourceforge.jp>
Cc: Rich Felker <dalias@...c.org>
Cc: Chris Metcalf <cmetcalf@...lanox.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
---
 arch/ia64/mm/init.c            | 23 ++++++++++++++++++++---
 arch/powerpc/mm/mem.c          | 22 +++++++++++++++++++---
 arch/s390/mm/init.c            | 10 ++++++++--
 arch/sh/mm/init.c              | 22 +++++++++++++++++++---
 arch/tile/mm/init.c            | 10 ++++++++--
 arch/x86/mm/init_32.c          | 23 ++++++++++++++++++++---
 arch/x86/mm/init_64.c          | 23 ++++++++++++++++++++---
 include/linux/memory_hotplug.h | 24 ++++++++++++++++++++++--
 include/linux/memremap.h       | 11 +++++++++++
 kernel/memremap.c              |  4 ++--
 mm/memory_hotplug.c            |  4 ++--
 11 files changed, 151 insertions(+), 25 deletions(-)

diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
index 1841ef6..303027e 100644
--- a/arch/ia64/mm/init.c
+++ b/arch/ia64/mm/init.c
@@ -645,18 +645,27 @@ mem_init (void)
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
-int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
+int arch_add_memory(int nid, u64 start, u64 size, int flags)
 {
+	const int supported_flags = MEMORY_DEVICE |
+				    MEMORY_DEVICE_ALLOW_MIGRATE;
 	pg_data_t *pgdat;
 	struct zone *zone;
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	int ret;
 
+	/* Each flag need special handling so error out on un-supported flag */
+	if (flags & (~supported_flags)) {
+		BUG();
+		return -EINVAL;
+	}
+
 	pgdat = NODE_DATA(nid);
 
 	zone = pgdat->node_zones +
-		zone_for_memory(nid, start, size, ZONE_NORMAL, for_device);
+		zone_for_memory(nid, start, size, ZONE_NORMAL,
+				flags & MEMORY_DEVICE);
 	ret = __add_pages(nid, zone, start_pfn, nr_pages);
 
 	if (ret)
@@ -667,13 +676,21 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-int arch_remove_memory(u64 start, u64 size)
+int arch_remove_memory(u64 start, u64 size, int flags)
 {
+	const int supported_flags = MEMORY_DEVICE |
+				    MEMORY_DEVICE_ALLOW_MIGRATE;
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	struct zone *zone;
 	int ret;
 
+	/* Each flag need special handling so error out on un-supported flag */
+	if (flags & (~supported_flags)) {
+		BUG();
+		return -EINVAL;
+	}
+
 	zone = page_zone(pfn_to_page(start_pfn));
 	ret = __remove_pages(zone, start_pfn, nr_pages);
 	if (ret)
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 5f84433..6e877d3 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -126,14 +126,22 @@ int __weak remove_section_mapping(unsigned long start, unsigned long end)
 	return -ENODEV;
 }
 
-int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
+int arch_add_memory(int nid, u64 start, u64 size, int flags)
 {
+	const int supported_flags = MEMORY_DEVICE |
+				    MEMORY_DEVICE_ALLOW_MIGRATE;
 	struct pglist_data *pgdata;
 	struct zone *zone;
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	int rc;
 
+	/* Each flag need special handling so error out on un-supported flag */
+	if (flags & (~supported_flags)) {
+		BUG();
+		return -EINVAL;
+	}
+
 	pgdata = NODE_DATA(nid);
 
 	start = (unsigned long)__va(start);
@@ -147,19 +155,27 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
 
 	/* this should work for most non-highmem platforms */
 	zone = pgdata->node_zones +
-		zone_for_memory(nid, start, size, 0, for_device);
+		zone_for_memory(nid, start, size, 0, flags & MEMORY_DEVICE);
 
 	return __add_pages(nid, zone, start_pfn, nr_pages);
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-int arch_remove_memory(u64 start, u64 size)
+int arch_remove_memory(u64 start, u64 size, int flags)
 {
+	const int supported_flags = MEMORY_DEVICE |
+				    MEMORY_DEVICE_ALLOW_MIGRATE;
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	struct zone *zone;
 	int ret;
 
+	/* Each flag need special handling so error out on un-supported flag */
+	if (flags & (~supported_flags)) {
+		BUG();
+		return -EINVAL;
+	}
+
 	zone = page_zone(pfn_to_page(start_pfn));
 	ret = __remove_pages(zone, start_pfn, nr_pages);
 	if (ret)
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index b3e9d18..e94b9e1 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -149,7 +149,7 @@ void __init free_initrd_mem(unsigned long start, unsigned long end)
 #endif
 
 #ifdef CONFIG_MEMORY_HOTPLUG
-int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
+int arch_add_memory(int nid, u64 start, u64 size, int flags)
 {
 	unsigned long zone_start_pfn, zone_end_pfn, nr_pages;
 	unsigned long start_pfn = PFN_DOWN(start);
@@ -158,6 +158,12 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
 	struct zone *zone;
 	int rc, i;
 
+	/* Each flag need special handling so error out on un-supported flag */
+	if (flags) {
+		BUG();
+		return -EINVAL;
+	}
+
 	rc = vmem_add_mapping(start, size);
 	if (rc)
 		return rc;
@@ -201,7 +207,7 @@ unsigned long memory_block_size_bytes(void)
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-int arch_remove_memory(u64 start, u64 size)
+int arch_remove_memory(u64 start, u64 size, int flags)
 {
 	/*
 	 * There is no hardware or firmware interface which could trigger a
diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
index 7549186..0ca69ac 100644
--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -485,19 +485,27 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 #endif
 
 #ifdef CONFIG_MEMORY_HOTPLUG
-int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
+int arch_add_memory(int nid, u64 start, u64 size, int flags)
 {
+	const int supported_flags = MEMORY_DEVICE |
+				    MEMORY_DEVICE_ALLOW_MIGRATE;
 	pg_data_t *pgdat;
 	unsigned long start_pfn = PFN_DOWN(start);
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	int ret;
 
+	/* Each flag need special handling so error out on un-supported flag */
+	if (flags & (~supported_flags)) {
+		BUG();
+		return -EINVAL;
+	}
+
 	pgdat = NODE_DATA(nid);
 
 	/* We only have ZONE_NORMAL, so this is easy.. */
 	ret = __add_pages(nid, pgdat->node_zones +
 			zone_for_memory(nid, start, size, ZONE_NORMAL,
-			for_device),
+					flags & MEMORY_DEVICE),
 			start_pfn, nr_pages);
 	if (unlikely(ret))
 		printk("%s: Failed, __add_pages() == %d\n", __func__, ret);
@@ -516,13 +524,21 @@ EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
 #endif
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-int arch_remove_memory(u64 start, u64 size)
+int arch_remove_memory(u64 start, u64 size, int flags)
 {
+	const int supported_flags = MEMORY_DEVICE |
+				    MEMORY_DEVICE_ALLOW_MIGRATE;
 	unsigned long start_pfn = PFN_DOWN(start);
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	struct zone *zone;
 	int ret;
 
+	/* Each flag need special handling so error out on un-supported flag */
+	if (flags & (~supported_flags)) {
+		BUG();
+		return -EINVAL;
+	}
+
 	zone = page_zone(pfn_to_page(start_pfn));
 	ret = __remove_pages(zone, start_pfn, nr_pages);
 	if (unlikely(ret))
diff --git a/arch/tile/mm/init.c b/arch/tile/mm/init.c
index adce254..ba001b1 100644
--- a/arch/tile/mm/init.c
+++ b/arch/tile/mm/init.c
@@ -863,13 +863,19 @@ void __init mem_init(void)
  * memory to the highmem for now.
  */
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-int arch_add_memory(u64 start, u64 size, bool for_device)
+int arch_add_memory(u64 start, u64 size, int flags)
 {
 	struct pglist_data *pgdata = &contig_page_data;
 	struct zone *zone = pgdata->node_zones + MAX_NR_ZONES-1;
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 
+	/* Each flag need special handling so error out on un-supported flag */
+	if (flags) {
+		BUG();
+		return -EINVAL;
+	}
+
 	return __add_pages(zone, start_pfn, nr_pages);
 }
 
@@ -879,7 +885,7 @@ int remove_memory(u64 start, u64 size)
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-int arch_remove_memory(u64 start, u64 size)
+int arch_remove_memory(u64 start, u64 size, int flags)
 {
 	/* TODO */
 	return -EBUSY;
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index cf80590..8287a4b 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -816,24 +816,41 @@ void __init mem_init(void)
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
-int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
+int arch_add_memory(int nid, u64 start, u64 size, int flags)
 {
+	const int supported_flags = MEMORY_DEVICE |
+				    MEMORY_DEVICE_ALLOW_MIGRATE;
 	struct pglist_data *pgdata = NODE_DATA(nid);
 	struct zone *zone = pgdata->node_zones +
-		zone_for_memory(nid, start, size, ZONE_HIGHMEM, for_device);
+		zone_for_memory(nid, start, size, ZONE_HIGHMEM,
+				flags & MEMORY_DEVICE);
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 
+	/* Each flag need special handling so error out on un-supported flag */
+	if (flags & (~supported_flags)) {
+		BUG();
+		return -EINVAL;
+	}
+
 	return __add_pages(nid, zone, start_pfn, nr_pages);
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-int arch_remove_memory(u64 start, u64 size)
+int arch_remove_memory(u64 start, u64 size, int flags)
 {
+	const int supported_flags = MEMORY_DEVICE |
+				    MEMORY_DEVICE_ALLOW_MIGRATE;
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	struct zone *zone;
 
+	/* Each flag need special handling so error out on un-supported flag */
+	if (flags & (~supported_flags)) {
+		BUG();
+		return -EINVAL;
+	}
+
 	zone = page_zone(pfn_to_page(start_pfn));
 	return __remove_pages(zone, start_pfn, nr_pages);
 }
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 14b9dd7..442ac86 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -651,15 +651,24 @@ static void  update_end_of_memory_vars(u64 start, u64 size)
  * Memory is added always to NORMAL zone. This means you will never get
  * additional DMA/DMA32 memory.
  */
-int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
+int arch_add_memory(int nid, u64 start, u64 size, int flags)
 {
+	const int supported_flags = MEMORY_DEVICE |
+				    MEMORY_DEVICE_ALLOW_MIGRATE;
 	struct pglist_data *pgdat = NODE_DATA(nid);
 	struct zone *zone = pgdat->node_zones +
-		zone_for_memory(nid, start, size, ZONE_NORMAL, for_device);
+		zone_for_memory(nid, start, size, ZONE_NORMAL,
+				flags & MEMORY_DEVICE);
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	int ret;
 
+	/* Each flag need special handling so error out on un-supported flag */
+	if (flags & (~supported_flags)) {
+		BUG();
+		return -EINVAL;
+	}
+
 	init_memory_mapping(start, start + size);
 
 	ret = __add_pages(nid, zone, start_pfn, nr_pages);
@@ -956,8 +965,10 @@ kernel_physical_mapping_remove(unsigned long start, unsigned long end)
 	remove_pagetable(start, end, true);
 }
 
-int __ref arch_remove_memory(u64 start, u64 size)
+int __ref arch_remove_memory(u64 start, u64 size, int flags)
 {
+	const int supported_flags = MEMORY_DEVICE |
+				    MEMORY_DEVICE_ALLOW_MIGRATE;
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	struct page *page = pfn_to_page(start_pfn);
@@ -965,6 +976,12 @@ int __ref arch_remove_memory(u64 start, u64 size)
 	struct zone *zone;
 	int ret;
 
+	/* Each flag need special handling so error out on un-supported flag */
+	if (flags & (~supported_flags)) {
+		BUG();
+		return -EINVAL;
+	}
+
 	/* With altmap the first mapped page is offset from @start */
 	altmap = to_vmem_altmap((unsigned long) page);
 	if (altmap)
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 01033fa..3f50eb8 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -103,7 +103,7 @@ extern bool memhp_auto_online;
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 extern bool is_pageblock_removable_nolock(struct page *page);
-extern int arch_remove_memory(u64 start, u64 size);
+extern int arch_remove_memory(u64 start, u64 size, int flags);
 extern int __remove_pages(struct zone *zone, unsigned long start_pfn,
 	unsigned long nr_pages);
 #endif /* CONFIG_MEMORY_HOTREMOVE */
@@ -275,7 +275,27 @@ extern int add_memory(int nid, u64 start, u64 size);
 extern int add_memory_resource(int nid, struct resource *resource, bool online);
 extern int zone_for_memory(int nid, u64 start, u64 size, int zone_default,
 		bool for_device);
-extern int arch_add_memory(int nid, u64 start, u64 size, bool for_device);
+
+/*
+ * When hotpluging memory with arch_add_memory() we want more informations on
+ * the type of memory and its properties. The flags parameter allow to provide
+ * more informations on the memory which is being addedd.
+ *
+ * Provide an opt-in flag for struct page migration. Persistent device memory
+ * never relied on struct page migration so far and new user of might also
+ * prefer avoiding struct page migration.
+ *
+ * New non device memory specific flags can be added if ever needed.
+ *
+ * MEMORY_REGULAR: regular system memory
+ * DEVICE_MEMORY: device memory create a ZONE_DEVICE zone for it
+ * DEVICE_MEMORY_ALLOW_MIGRATE: page in that device memory ca be migrated
+ */
+#define MEMORY_NORMAL 0
+#define MEMORY_DEVICE (1 << 0)
+#define MEMORY_DEVICE_ALLOW_MIGRATE (1 << 1)
+
+extern int arch_add_memory(int nid, u64 start, u64 size, int flags);
 extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
 extern bool is_memblock_offlined(struct memory_block *mem);
 extern void remove_memory(int nid, u64 start, u64 size);
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 9341619..f7e0609 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -53,6 +53,12 @@ struct dev_pagemap {
 void *devm_memremap_pages(struct device *dev, struct resource *res,
 		struct percpu_ref *ref, struct vmem_altmap *altmap);
 struct dev_pagemap *find_dev_pagemap(resource_size_t phys);
+
+static inline bool dev_page_allow_migrate(const struct page *page)
+{
+	return ((page_zonenum(page) == ZONE_DEVICE) &&
+		(page->pgmap->flags & MEMORY_DEVICE_ALLOW_MIGRATE));
+}
 #else
 static inline void *devm_memremap_pages(struct device *dev,
 		struct resource *res, struct percpu_ref *ref,
@@ -71,6 +77,11 @@ static inline struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
 {
 	return NULL;
 }
+
+static inline bool dev_page_allow_migrate(const struct page *page)
+{
+	return false;
+}
 #endif
 
 /**
diff --git a/kernel/memremap.c b/kernel/memremap.c
index b501e39..07665eb 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -246,7 +246,7 @@ static void devm_memremap_pages_release(struct device *dev, void *data)
 	/* pages are dead and unused, undo the arch mapping */
 	align_start = res->start & ~(SECTION_SIZE - 1);
 	align_size = ALIGN(resource_size(res), SECTION_SIZE);
-	arch_remove_memory(align_start, align_size);
+	arch_remove_memory(align_start, align_size, MEMORY_DEVICE);
 	untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
 	pgmap_radix_release(res);
 	dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
@@ -358,7 +358,7 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
 	if (error)
 		goto err_pfn_remap;
 
-	error = arch_add_memory(nid, align_start, align_size, true);
+	error = arch_add_memory(nid, align_start, align_size, MEMORY_DEVICE);
 	if (error)
 		goto err_add_memory;
 
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index e43142c1..096c651 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1372,7 +1372,7 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online)
 	}
 
 	/* call arch's memory hotadd */
-	ret = arch_add_memory(nid, start, size, false);
+	ret = arch_add_memory(nid, start, size, MEMORY_NORMAL);
 
 	if (ret < 0)
 		goto error;
@@ -2156,7 +2156,7 @@ void __ref remove_memory(int nid, u64 start, u64 size)
 	memblock_free(start, size);
 	memblock_remove(start, size);
 
-	arch_remove_memory(start, size);
+	arch_remove_memory(start, size, MEMORY_NORMAL);
 
 	try_offline_node(nid);
 
-- 
2.4.3

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