Subject: Re: [PATCH RFCv2 2/4] mm/memory_hotplug: Replace "bool want_memblock" by "int type"

From: Wei Yang <[email-masked]>
Date: Sat, 1 Dec 2018 01:50:24 +0000

On Fri, Nov 30, 2018 at 06:59:20PM +0100, David Hildenbrand wrote:
>Let's pass a memory block type instead. Pass "MEMORY_BLOCK_NONE" for device
>memory and for now "MEMORY_BLOCK_UNSPECIFIED" for anything else. No
>functional change.

I would suggest to put more words to this.

"
Function arch_add_memory()'s last parameter *want_memblock* is used to
determin whether it is necessary to create a corresponding memory block
device. After introducing the memory block type, this patch replaces the
bool type *want_memblock* with memory block type with following rules
for now:

  * Pass "MEMORY_BLOCK_NONE" for device memory
  * Pass "MEMORY_BLOCK_UNSPECIFIED" for anything else 

Since this parameter is passed deep to __add_section(), all its
descendents are effected. Below lists those descendents.

  arch_add_memory()
    add_pages()
      __add_pages()
        __add_section()

"

>
>Cc: Tony Luck <[email-masked]>
>Cc: Fenghua Yu <[email-masked]>
>Cc: Benjamin Herrenschmidt <[email-masked]>
>Cc: Paul Mackerras <[email-masked]>
>Cc: Michael Ellerman <[email-masked]>
>Cc: Martin Schwidefsky <[email-masked]>
>Cc: Heiko Carstens <[email-masked]>
>Cc: Yoshinori Sato <[email-masked]>
>Cc: Rich Felker <[email-masked]>
>Cc: Dave Hansen <[email-masked]>
>Cc: Andy Lutomirski <[email-masked]>
>Cc: Peter Zijlstra <[email-masked]>
>Cc: Thomas Gleixner <[email-masked]>
>Cc: Ingo Molnar <[email-masked]>
>Cc: Borislav Petkov <[email-masked]>
>Cc: "H. Peter Anvin" <[email-masked]>
>Cc: [email-masked]
>Cc: Greg Kroah-Hartman <[email-masked]>
>Cc: "Rafael J. Wysocki" <[email-masked]>
>Cc: Andrew Morton <[email-masked]>
>Cc: Mike Rapoport <[email-masked]>
>Cc: Michal Hocko <[email-masked]>
>Cc: Dan Williams <[email-masked]>
>Cc: "Kirill A. Shutemov" <[email-masked]>
>Cc: Oscar Salvador <[email-masked]>
>Cc: Nicholas Piggin <[email-masked]>
>Cc: Stephen Rothwell <[email-masked]>
>Cc: Christophe Leroy <[email-masked]>
>Cc: "Jonathan Neusch??fer" <[email-masked]>
>Cc: Mauricio Faria de Oliveira <[email-masked]>
>Cc: Vasily Gorbik <[email-masked]>
>Cc: Arun KS <[email-masked]>
>Cc: Rob Herring <[email-masked]>
>Cc: Pavel Tatashin <[email-masked]>
>Cc: "[email-masked]" <[email-masked]>
>Cc: Joonsoo Kim <[email-masked]>
>Cc: Wei Yang <[email-masked]>
>Cc: Logan Gunthorpe <[email-masked]>
>Cc: "J??r??me Glisse" <[email-masked]>
>Cc: "Jan H. Sch??nherr" <[email-masked]>
>Cc: Dave Jiang <[email-masked]>
>Cc: Matthew Wilcox <[email-masked]>
>Cc: Mathieu Malaterre <[email-masked]>
>Signed-off-by: David Hildenbrand <[email-masked]>
>---
> arch/ia64/mm/init.c            |  4 ++--
> arch/powerpc/mm/mem.c          |  4 ++--
> arch/s390/mm/init.c            |  4 ++--
> arch/sh/mm/init.c              |  4 ++--
> arch/x86/mm/init_32.c          |  4 ++--
> arch/x86/mm/init_64.c          |  8 ++++----
> drivers/base/memory.c          | 11 +++++++----
> include/linux/memory.h         |  2 +-
> include/linux/memory_hotplug.h | 12 ++++++------
> kernel/memremap.c              |  6 ++++--
> mm/memory_hotplug.c            | 16 ++++++++--------
> 11 files changed, 40 insertions(+), 35 deletions(-)
>
>diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
>index 904fe55e10fc..408635d2902f 100644
>--- a/arch/ia64/mm/init.c
>+++ b/arch/ia64/mm/init.c
>@@ -646,13 +646,13 @@ mem_init (void)
> 
> #ifdef CONFIG_MEMORY_HOTPLUG
> int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
>-		bool want_memblock)
>+		    int type)
> {
> 	unsigned long start_pfn = start >> PAGE_SHIFT;
> 	unsigned long nr_pages = size >> PAGE_SHIFT;
> 	int ret;
> 
>-	ret = __add_pages(nid, start_pfn, nr_pages, altmap, want_memblock);
>+	ret = __add_pages(nid, start_pfn, nr_pages, altmap, type);
> 	if (ret)
> 		printk("%s: Problem encountered in __add_pages() as ret=%d\n",
> 		       __func__,  ret);
>diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
>index b3c9ee5c4f78..e394637da270 100644
>--- a/arch/powerpc/mm/mem.c
>+++ b/arch/powerpc/mm/mem.c
>@@ -118,7 +118,7 @@ int __weak remove_section_mapping(unsigned long start, unsigned long end)
> }
> 
> int __meminit arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
>-		bool want_memblock)
>+			      int type)
> {
> 	unsigned long start_pfn = start >> PAGE_SHIFT;
> 	unsigned long nr_pages = size >> PAGE_SHIFT;
>@@ -135,7 +135,7 @@ int __meminit arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *
> 	}
> 	flush_inval_dcache_range(start, start + size);
> 
>-	return __add_pages(nid, start_pfn, nr_pages, altmap, want_memblock);
>+	return __add_pages(nid, start_pfn, nr_pages, altmap, type);
> }
> 
> #ifdef CONFIG_MEMORY_HOTREMOVE
>diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
>index 3e82f66d5c61..ba2c56328e6d 100644
>--- a/arch/s390/mm/init.c
>+++ b/arch/s390/mm/init.c
>@@ -225,7 +225,7 @@ device_initcall(s390_cma_mem_init);
> #endif /* CONFIG_CMA */
> 
> int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
>-		bool want_memblock)
>+		    int type)
> {
> 	unsigned long start_pfn = PFN_DOWN(start);
> 	unsigned long size_pages = PFN_DOWN(size);
>@@ -235,7 +235,7 @@ int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
> 	if (rc)
> 		return rc;
> 
>-	rc = __add_pages(nid, start_pfn, size_pages, altmap, want_memblock);
>+	rc = __add_pages(nid, start_pfn, size_pages, altmap, type);
> 	if (rc)
> 		vmem_remove_mapping(start, size);
> 	return rc;
>diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
>index 1a483a008872..5fbb8724e0f2 100644
>--- a/arch/sh/mm/init.c
>+++ b/arch/sh/mm/init.c
>@@ -419,14 +419,14 @@ void free_initrd_mem(unsigned long start, unsigned long end)
> 
> #ifdef CONFIG_MEMORY_HOTPLUG
> int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
>-		bool want_memblock)
>+		    int type)
> {
> 	unsigned long start_pfn = PFN_DOWN(start);
> 	unsigned long nr_pages = size >> PAGE_SHIFT;
> 	int ret;
> 
> 	/* We only have ZONE_NORMAL, so this is easy.. */
>-	ret = __add_pages(nid, start_pfn, nr_pages, altmap, want_memblock);
>+	ret = __add_pages(nid, start_pfn, nr_pages, altmap, type);
> 	if (unlikely(ret))
> 		printk("%s: Failed, __add_pages() == %d\n", __func__, ret);
> 
>diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
>index 0b8c7b0033d2..41e409b29d2b 100644
>--- a/arch/x86/mm/init_32.c
>+++ b/arch/x86/mm/init_32.c
>@@ -851,12 +851,12 @@ void __init mem_init(void)
> 
> #ifdef CONFIG_MEMORY_HOTPLUG
> int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
>-		bool want_memblock)
>+		    int type)
> {
> 	unsigned long start_pfn = start >> PAGE_SHIFT;
> 	unsigned long nr_pages = size >> PAGE_SHIFT;
> 
>-	return __add_pages(nid, start_pfn, nr_pages, altmap, want_memblock);
>+	return __add_pages(nid, start_pfn, nr_pages, altmap, type);
> }
> 
> #ifdef CONFIG_MEMORY_HOTREMOVE
>diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
>index f80d98381a97..5b4f3dcd44cf 100644
>--- a/arch/x86/mm/init_64.c
>+++ b/arch/x86/mm/init_64.c
>@@ -783,11 +783,11 @@ static void update_end_of_memory_vars(u64 start, u64 size)
> }
> 
> int add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages,
>-		struct vmem_altmap *altmap, bool want_memblock)
>+	      struct vmem_altmap *altmap, int type)
> {
> 	int ret;
> 
>-	ret = __add_pages(nid, start_pfn, nr_pages, altmap, want_memblock);
>+	ret = __add_pages(nid, start_pfn, nr_pages, altmap, type);
> 	WARN_ON_ONCE(ret);
> 
> 	/* update max_pfn, max_low_pfn and high_memory */
>@@ -798,14 +798,14 @@ int add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages,
> }
> 
> int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
>-		bool want_memblock)
>+		    int type)
> {
> 	unsigned long start_pfn = start >> PAGE_SHIFT;
> 	unsigned long nr_pages = size >> PAGE_SHIFT;
> 
> 	init_memory_mapping(start, start + size);
> 
>-	return add_pages(nid, start_pfn, nr_pages, altmap, want_memblock);
>+	return add_pages(nid, start_pfn, nr_pages, altmap, type);
> }
> 
> #define PAGE_INUSE 0xFD
>diff --git a/drivers/base/memory.c b/drivers/base/memory.c
>index 17f2985c07c5..c42300082c88 100644
>--- a/drivers/base/memory.c
>+++ b/drivers/base/memory.c
>@@ -741,7 +741,7 @@ static int add_memory_block(int base_section_nr)
>  * need an interface for the VM to add new memory regions,
>  * but without onlining it.
>  */
>-int hotplug_memory_register(int nid, struct mem_section *section)
>+int hotplug_memory_register(int nid, struct mem_section *section, int type)
> {
> 	int ret = 0;
> 	struct memory_block *mem;
>@@ -750,11 +750,14 @@ int hotplug_memory_register(int nid, struct mem_section *section)
> 
> 	mem = find_memory_block(section);
> 	if (mem) {
>-		mem->section_count++;
>+		/* make sure the type matches */
>+		if (mem->type == type)
>+			mem->section_count++;
>+		else
>+			ret = -EINVAL;
> 		put_device(&mem->dev);
> 	} else {
>-		ret = init_memory_block(&mem, section, MEM_OFFLINE,
>-					MEMORY_BLOCK_UNSPECIFIED);
>+		ret = init_memory_block(&mem, section, MEM_OFFLINE, type);
> 		if (ret)
> 			goto out;
> 		mem->section_count++;
>diff --git a/include/linux/memory.h b/include/linux/memory.h
>index 06268e96e0da..9f39ef41e6d2 100644
>--- a/include/linux/memory.h
>+++ b/include/linux/memory.h
>@@ -138,7 +138,7 @@ extern int register_memory_notifier(struct notifier_block *nb);
> extern void unregister_memory_notifier(struct notifier_block *nb);
> extern int register_memory_isolate_notifier(struct notifier_block *nb);
> extern void unregister_memory_isolate_notifier(struct notifier_block *nb);
>-int hotplug_memory_register(int nid, struct mem_section *section);
>+int hotplug_memory_register(int nid, struct mem_section *section, int type);
> #ifdef CONFIG_MEMORY_HOTREMOVE
> extern int unregister_memory_section(int nid, struct mem_section *);
> #endif
>diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
>index 5493d3fa0c7f..667a37aa9a3c 100644
>--- a/include/linux/memory_hotplug.h
>+++ b/include/linux/memory_hotplug.h
>@@ -117,18 +117,18 @@ extern void shrink_zone(struct zone *zone, unsigned long start_pfn,
> 
> /* reasonably generic interface to expand the physical pages */
> extern int __add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages,
>-		struct vmem_altmap *altmap, bool want_memblock);
>+		       struct vmem_altmap *altmap, int type);
> 
> #ifndef CONFIG_ARCH_HAS_ADD_PAGES
> static inline int add_pages(int nid, unsigned long start_pfn,
>-		unsigned long nr_pages, struct vmem_altmap *altmap,
>-		bool want_memblock)
>+			    unsigned long nr_pages, struct vmem_altmap *altmap,
>+			    int type)
> {
>-	return __add_pages(nid, start_pfn, nr_pages, altmap, want_memblock);
>+	return __add_pages(nid, start_pfn, nr_pages, altmap, type);
> }
> #else /* ARCH_HAS_ADD_PAGES */
> int add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages,
>-		struct vmem_altmap *altmap, bool want_memblock);
>+	      struct vmem_altmap *altmap, int type);
> #endif /* ARCH_HAS_ADD_PAGES */
> 
> #ifdef CONFIG_NUMA
>@@ -330,7 +330,7 @@ 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 arch_add_memory(int nid, u64 start, u64 size,
>-		struct vmem_altmap *altmap, bool want_memblock);
>+			   struct vmem_altmap *altmap, int type);
> extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
> 		unsigned long nr_pages, struct vmem_altmap *altmap);
> extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
>diff --git a/kernel/memremap.c b/kernel/memremap.c
>index 66cbf334203b..422e4e779208 100644
>--- a/kernel/memremap.c
>+++ b/kernel/memremap.c
>@@ -4,6 +4,7 @@
> #include <linux/io.h>
> #include <linux/kasan.h>
> #include <linux/memory_hotplug.h>
>+#include <linux/memory.h>
> #include <linux/mm.h>
> #include <linux/pfn_t.h>
> #include <linux/swap.h>
>@@ -215,7 +216,8 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
> 	 */
> 	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
> 		error = add_pages(nid, align_start >> PAGE_SHIFT,
>-				align_size >> PAGE_SHIFT, NULL, false);
>+				  align_size >> PAGE_SHIFT, NULL,
>+				  MEMORY_BLOCK_NONE);
> 	} else {
> 		error = kasan_add_zero_shadow(__va(align_start), align_size);
> 		if (error) {
>@@ -224,7 +226,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
> 		}
> 
> 		error = arch_add_memory(nid, align_start, align_size, altmap,
>-				false);
>+					MEMORY_BLOCK_NONE);

Ok, it is used here.

> 	}
> 
> 	if (!error) {
>diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>index 16c600771298..7246faa44488 100644
>--- a/mm/memory_hotplug.c
>+++ b/mm/memory_hotplug.c
>@@ -246,7 +246,7 @@ void __init register_page_bootmem_info_node(struct pglist_data *pgdat)
> #endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
> 
> static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
>-		struct vmem_altmap *altmap, bool want_memblock)
>+				   struct vmem_altmap *altmap, int type)
> {
> 	int ret;
> 
>@@ -257,10 +257,11 @@ static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
> 	if (ret < 0)
> 		return ret;
> 
>-	if (!want_memblock)
>+	if (type == MEMORY_BLOCK_NONE)
> 		return 0;
> 
>-	return hotplug_memory_register(nid, __pfn_to_section(phys_start_pfn));
>+	return hotplug_memory_register(nid, __pfn_to_section(phys_start_pfn),
>+				       type);
> }
> 
> /*
>@@ -270,8 +271,8 @@ static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
>  * add the new pages.
>  */
> int __ref __add_pages(int nid, unsigned long phys_start_pfn,
>-		unsigned long nr_pages, struct vmem_altmap *altmap,
>-		bool want_memblock)
>+		      unsigned long nr_pages, struct vmem_altmap *altmap,
>+		      int type)
> {
> 	unsigned long i;
> 	int err = 0;
>@@ -295,8 +296,7 @@ int __ref __add_pages(int nid, unsigned long phys_start_pfn,
> 	}
> 
> 	for (i = start_sec; i <= end_sec; i++) {
>-		err = __add_section(nid, section_nr_to_pfn(i), altmap,
>-				want_memblock);
>+		err = __add_section(nid, section_nr_to_pfn(i), altmap, type);
> 
> 		/*
> 		 * EEXIST is finally dealt with by ioresource collision
>@@ -1100,7 +1100,7 @@ int __ref add_memory_resource(int nid, struct resource *res)
> 	new_node = ret;
> 
> 	/* call arch's memory hotadd */
>-	ret = arch_add_memory(nid, start, size, NULL, true);
>+	ret = arch_add_memory(nid, start, size, NULL, MEMORY_TYPE_UNSPECIFIED);
> 	if (ret < 0)
> 		goto error;
> 
>-- 
>2.17.2

-- 
Wei Yang
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