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Date: Wed, 10 Apr 2013 11:29:59 -0600
From: Toshi Kani <toshi.kani@...com>
To: David Rientjes <rientjes@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Wen Congyang <wency@...fujitsu.com>,
Tang Chen <tangchen@...fujitsu.com>,
Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-mm@...ck.org
Subject: Re: [patch] mm, hotplug: avoid compiling memory hotremove functions
when disabled
On Tue, 2013-04-09 at 23:07 -0700, David Rientjes wrote:
> __remove_pages() is only necessary for CONFIG_MEMORY_HOTREMOVE. PowerPC
> pseries will return -EOPNOTSUPP if unsupported.
>
> Adding an #ifdef causes several other functions it depends on to also
> become unnecessary, which saves in .text when disabled (it's disabled in
> most defconfigs besides powerpc, including x86). remove_memory_block()
> becomes static since it is not referenced outside of
> drivers/base/memory.c.
>
> Build tested on x86 and powerpc with CONFIG_MEMORY_HOTREMOVE both enabled
> and disabled.
>
> Signed-off-by: David Rientjes <rientjes@...gle.com>
Acked-by: Toshi Kani <toshi.kani@...com>
Thanks,
-Toshi
> ---
> arch/powerpc/platforms/pseries/hotplug-memory.c | 12 +++++
> drivers/base/memory.c | 44 +++++++--------
> include/linux/memory.h | 3 +-
> include/linux/memory_hotplug.h | 4 +-
> mm/memory_hotplug.c | 68 +++++++++++------------
> mm/sparse.c | 72 +++++++++++++------------
> 6 files changed, 113 insertions(+), 90 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
> --- a/arch/powerpc/platforms/pseries/hotplug-memory.c
> +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
> @@ -72,6 +72,7 @@ unsigned long memory_block_size_bytes(void)
> return get_memblock_size();
> }
>
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> static int pseries_remove_memblock(unsigned long base, unsigned int memblock_size)
> {
> unsigned long start, start_pfn;
> @@ -153,6 +154,17 @@ static int pseries_remove_memory(struct device_node *np)
> ret = pseries_remove_memblock(base, lmb_size);
> return ret;
> }
> +#else
> +static inline int pseries_remove_memblock(unsigned long base,
> + unsigned int memblock_size)
> +{
> + return -EOPNOTSUPP;
> +}
> +static inline int pseries_remove_memory(struct device_node *np)
> +{
> + return -EOPNOTSUPP;
> +}
> +#endif /* CONFIG_MEMORY_HOTREMOVE */
>
> static int pseries_add_memory(struct device_node *np)
> {
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -93,16 +93,6 @@ int register_memory(struct memory_block *memory)
> return error;
> }
>
> -static void
> -unregister_memory(struct memory_block *memory)
> -{
> - BUG_ON(memory->dev.bus != &memory_subsys);
> -
> - /* drop the ref. we got in remove_memory_block() */
> - kobject_put(&memory->dev.kobj);
> - device_unregister(&memory->dev);
> -}
> -
> unsigned long __weak memory_block_size_bytes(void)
> {
> return MIN_MEMORY_BLOCK_SIZE;
> @@ -637,8 +627,28 @@ static int add_memory_section(int nid, struct mem_section *section,
> return ret;
> }
>
> -int remove_memory_block(unsigned long node_id, struct mem_section *section,
> - int phys_device)
> +/*
> + * need an interface for the VM to add new memory regions,
> + * but without onlining it.
> + */
> +int register_new_memory(int nid, struct mem_section *section)
> +{
> + return add_memory_section(nid, section, NULL, MEM_OFFLINE, HOTPLUG);
> +}
> +
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> +static void
> +unregister_memory(struct memory_block *memory)
> +{
> + BUG_ON(memory->dev.bus != &memory_subsys);
> +
> + /* drop the ref. we got in remove_memory_block() */
> + kobject_put(&memory->dev.kobj);
> + device_unregister(&memory->dev);
> +}
> +
> +static int remove_memory_block(unsigned long node_id,
> + struct mem_section *section, int phys_device)
> {
> struct memory_block *mem;
>
> @@ -661,15 +671,6 @@ int remove_memory_block(unsigned long node_id, struct mem_section *section,
> return 0;
> }
>
> -/*
> - * need an interface for the VM to add new memory regions,
> - * but without onlining it.
> - */
> -int register_new_memory(int nid, struct mem_section *section)
> -{
> - return add_memory_section(nid, section, NULL, MEM_OFFLINE, HOTPLUG);
> -}
> -
> int unregister_memory_section(struct mem_section *section)
> {
> if (!present_section(section))
> @@ -677,6 +678,7 @@ int unregister_memory_section(struct mem_section *section)
>
> return remove_memory_block(0, section, 0);
> }
> +#endif /* CONFIG_MEMORY_HOTREMOVE */
>
> /*
> * offline one memory block. If the memory block has been offlined, do nothing.
> diff --git a/include/linux/memory.h b/include/linux/memory.h
> --- a/include/linux/memory.h
> +++ b/include/linux/memory.h
> @@ -114,9 +114,10 @@ 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);
> extern int register_new_memory(int, struct mem_section *);
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> extern int unregister_memory_section(struct mem_section *);
> +#endif
> extern int memory_dev_init(void);
> -extern int remove_memory_block(unsigned long, struct mem_section *, int);
> extern int memory_notify(unsigned long val, void *v);
> extern int memory_isolate_notify(unsigned long val, void *v);
> extern struct memory_block *find_memory_block_hinted(struct mem_section *,
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -97,13 +97,13 @@ extern void __online_page_free(struct page *page);
> #ifdef CONFIG_MEMORY_HOTREMOVE
> extern bool is_pageblock_removable_nolock(struct page *page);
> extern int arch_remove_memory(u64 start, u64 size);
> +extern int __remove_pages(struct zone *zone, unsigned long start_pfn,
> + unsigned long nr_pages);
> #endif /* CONFIG_MEMORY_HOTREMOVE */
>
> /* reasonably generic interface to expand the physical pages in a zone */
> extern int __add_pages(int nid, struct zone *zone, unsigned long start_pfn,
> unsigned long nr_pages);
> -extern int __remove_pages(struct zone *zone, unsigned long start_pfn,
> - unsigned long nr_pages);
>
> #ifdef CONFIG_NUMA
> extern int memory_add_physaddr_to_nid(u64 start);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -436,6 +436,40 @@ static int __meminit __add_section(int nid, struct zone *zone,
> return register_new_memory(nid, __pfn_to_section(phys_start_pfn));
> }
>
> +/*
> + * Reasonably generic function for adding memory. It is
> + * expected that archs that support memory hotplug will
> + * call this function after deciding the zone to which to
> + * add the new pages.
> + */
> +int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
> + unsigned long nr_pages)
> +{
> + unsigned long i;
> + int err = 0;
> + int start_sec, end_sec;
> + /* during initialize mem_map, align hot-added range to section */
> + start_sec = pfn_to_section_nr(phys_start_pfn);
> + end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
> +
> + for (i = start_sec; i <= end_sec; i++) {
> + err = __add_section(nid, zone, i << PFN_SECTION_SHIFT);
> +
> + /*
> + * EEXIST is finally dealt with by ioresource collision
> + * check. see add_memory() => register_memory_resource()
> + * Warning will be printed if there is collision.
> + */
> + if (err && (err != -EEXIST))
> + break;
> + err = 0;
> + }
> +
> + return err;
> +}
> +EXPORT_SYMBOL_GPL(__add_pages);
> +
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> /* find the smallest valid pfn in the range [start_pfn, end_pfn) */
> static int find_smallest_section_pfn(int nid, struct zone *zone,
> unsigned long start_pfn,
> @@ -658,39 +692,6 @@ static int __remove_section(struct zone *zone, struct mem_section *ms)
> return 0;
> }
>
> -/*
> - * Reasonably generic function for adding memory. It is
> - * expected that archs that support memory hotplug will
> - * call this function after deciding the zone to which to
> - * add the new pages.
> - */
> -int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
> - unsigned long nr_pages)
> -{
> - unsigned long i;
> - int err = 0;
> - int start_sec, end_sec;
> - /* during initialize mem_map, align hot-added range to section */
> - start_sec = pfn_to_section_nr(phys_start_pfn);
> - end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
> -
> - for (i = start_sec; i <= end_sec; i++) {
> - err = __add_section(nid, zone, i << PFN_SECTION_SHIFT);
> -
> - /*
> - * EEXIST is finally dealt with by ioresource collision
> - * check. see add_memory() => register_memory_resource()
> - * Warning will be printed if there is collision.
> - */
> - if (err && (err != -EEXIST))
> - break;
> - err = 0;
> - }
> -
> - return err;
> -}
> -EXPORT_SYMBOL_GPL(__add_pages);
> -
> /**
> * __remove_pages() - remove sections of pages from a zone
> * @zone: zone from which pages need to be removed
> @@ -726,6 +727,7 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
> return ret;
> }
> EXPORT_SYMBOL_GPL(__remove_pages);
> +#endif /* CONFIG_MEMORY_HOTREMOVE */
>
> int set_online_page_callback(online_page_callback_t callback)
> {
> diff --git a/mm/sparse.c b/mm/sparse.c
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -620,6 +620,7 @@ static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
>
> vmemmap_free(start, end);
> }
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> static void free_map_bootmem(struct page *memmap, unsigned long nr_pages)
> {
> unsigned long start = (unsigned long)memmap;
> @@ -627,6 +628,7 @@ static void free_map_bootmem(struct page *memmap, unsigned long nr_pages)
>
> vmemmap_free(start, end);
> }
> +#endif /* CONFIG_MEMORY_HOTREMOVE */
> #else
> static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
> {
> @@ -664,6 +666,7 @@ static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
> get_order(sizeof(struct page) * nr_pages));
> }
>
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> static void free_map_bootmem(struct page *memmap, unsigned long nr_pages)
> {
> unsigned long maps_section_nr, removing_section_nr, i;
> @@ -690,40 +693,9 @@ static void free_map_bootmem(struct page *memmap, unsigned long nr_pages)
> put_page_bootmem(page);
> }
> }
> +#endif /* CONFIG_MEMORY_HOTREMOVE */
> #endif /* CONFIG_SPARSEMEM_VMEMMAP */
>
> -static void free_section_usemap(struct page *memmap, unsigned long *usemap)
> -{
> - struct page *usemap_page;
> - unsigned long nr_pages;
> -
> - if (!usemap)
> - return;
> -
> - usemap_page = virt_to_page(usemap);
> - /*
> - * Check to see if allocation came from hot-plug-add
> - */
> - if (PageSlab(usemap_page) || PageCompound(usemap_page)) {
> - kfree(usemap);
> - if (memmap)
> - __kfree_section_memmap(memmap, PAGES_PER_SECTION);
> - return;
> - }
> -
> - /*
> - * The usemap came from bootmem. This is packed with other usemaps
> - * on the section which has pgdat at boot time. Just keep it as is now.
> - */
> -
> - if (memmap) {
> - nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
> - >> PAGE_SHIFT;
> -
> - free_map_bootmem(memmap, nr_pages);
> - }
> -}
> -
> /*
> * returns the number of sections whose mem_maps were properly
> * set. If this is <=0, then that means that the passed-in
> @@ -800,6 +772,39 @@ static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
> }
> #endif
>
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> +static void free_section_usemap(struct page *memmap, unsigned long *usemap)
> +{
> + struct page *usemap_page;
> + unsigned long nr_pages;
> +
> + if (!usemap)
> + return;
> +
> + usemap_page = virt_to_page(usemap);
> + /*
> + * Check to see if allocation came from hot-plug-add
> + */
> + if (PageSlab(usemap_page) || PageCompound(usemap_page)) {
> + kfree(usemap);
> + if (memmap)
> + __kfree_section_memmap(memmap, PAGES_PER_SECTION);
> + return;
> + }
> +
> + /*
> + * The usemap came from bootmem. This is packed with other usemaps
> + * on the section which has pgdat at boot time. Just keep it as is now.
> + */
> +
> + if (memmap) {
> + nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
> + >> PAGE_SHIFT;
> +
> + free_map_bootmem(memmap, nr_pages);
> + }
> +}
> +
> void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
> {
> struct page *memmap = NULL;
> @@ -819,4 +824,5 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
> clear_hwpoisoned_pages(memmap, PAGES_PER_SECTION);
> free_section_usemap(memmap, usemap);
> }
> -#endif
> +#endif /* CONFIG_MEMORY_HOTREMOVE */
> +#endif /* CONFIG_MEMORY_HOTPLUG */
--
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