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Message-Id: <20080328111317.B0C1.E1E9C6FF@jp.fujitsu.com>
Date: Fri, 28 Mar 2008 11:26:00 +0900
From: Yasunori Goto <y-goto@...fujitsu.com>
To: Badari Pulavarty <pbadari@...ibm.com>
Cc: lkml <linux-kernel@...r.kernel.org>, linuxppc-dev@...abs.org,
paulus@...ba.org, Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/5] generic __remove_pages() support
Ok. Thanks.
Acked-by: Yasunori Goto <y-goto@...fujitsu.com>
> Generic helper function to remove section mappings and sysfs entries
> for the section of the memory we are removing. offline_pages() correctly
> adjusted zone and marked the pages reserved.
>
> TODO: Yasunori Goto is working on patches to freeup allocations from bootmem.
>
> Signed-off-by: Badari Pulavarty <pbadari@...ibm.com>
>
> ---
> include/linux/memory_hotplug.h | 6 +++-
> mm/memory_hotplug.c | 55 +++++++++++++++++++++++++++++++++++++++++
> mm/sparse.c | 45 +++++++++++++++++++++++++++++++--
> 3 files changed, 102 insertions(+), 4 deletions(-)
>
> Index: linux-2.6.25-rc5/mm/memory_hotplug.c
> ===================================================================
> --- linux-2.6.25-rc5.orig/mm/memory_hotplug.c 2008-03-21 07:00:37.000000000 -0800
> +++ linux-2.6.25-rc5/mm/memory_hotplug.c 2008-03-25 15:03:58.000000000 -0800
> @@ -102,6 +102,25 @@ static int __add_section(struct zone *zo
> return register_new_memory(__pfn_to_section(phys_start_pfn));
> }
>
> +static int __remove_section(struct zone *zone, struct mem_section *ms)
> +{
> + unsigned long flags;
> + struct pglist_data *pgdat = zone->zone_pgdat;
> + int ret = -EINVAL;
> +
> + if (!valid_section(ms))
> + return ret;
> +
> + ret = unregister_memory_section(ms);
> + if (ret)
> + return ret;
> +
> + pgdat_resize_lock(pgdat, &flags);
> + sparse_remove_one_section(zone, ms);
> + pgdat_resize_unlock(pgdat, &flags);
> + return 0;
> +}
> +
> /*
> * Reasonably generic function for adding memory. It is
> * expected that archs that support memory hotplug will
> @@ -135,6 +154,42 @@ int __add_pages(struct zone *zone, unsig
> }
> EXPORT_SYMBOL_GPL(__add_pages);
>
> +/**
> + * __remove_pages() - remove sections of pages from a zone
> + * @zone: zone from which pages need to be removed
> + * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
> + * @nr_pages: number of pages to remove (must be multiple of section size)
> + *
> + * Generic helper function to remove section mappings and sysfs entries
> + * for the section of the memory we are removing. Caller needs to make
> + * sure that pages are marked reserved and zones are adjust properly by
> + * calling offline_pages().
> + */
> +int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
> + unsigned long nr_pages)
> +{
> + unsigned long i, ret = 0;
> + int sections_to_remove;
> +
> + /*
> + * We can only remove entire sections
> + */
> + BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
> + BUG_ON(nr_pages % PAGES_PER_SECTION);
> +
> + release_mem_region(phys_start_pfn << PAGE_SHIFT, nr_pages * PAGE_SIZE);
> +
> + sections_to_remove = nr_pages / PAGES_PER_SECTION;
> + for (i = 0; i < sections_to_remove; i++) {
> + unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
> + ret = __remove_section(zone, __pfn_to_section(pfn));
> + if (ret)
> + break;
> + }
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(__remove_pages);
> +
> static void grow_zone_span(struct zone *zone,
> unsigned long start_pfn, unsigned long end_pfn)
> {
> Index: linux-2.6.25-rc5/mm/sparse.c
> ===================================================================
> --- linux-2.6.25-rc5.orig/mm/sparse.c 2008-03-21 07:00:37.000000000 -0800
> +++ linux-2.6.25-rc5/mm/sparse.c 2008-03-25 13:59:51.000000000 -0800
> @@ -198,12 +198,13 @@ static unsigned long sparse_encode_mem_m
> }
>
> /*
> - * We need this if we ever free the mem_maps. While not implemented yet,
> - * this function is included for parity with its sibling.
> + * Decode mem_map from the coded memmap
> */
> -static __attribute((unused))
> +static
> struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
> {
> + /* mask off the extra low bits of information */
> + coded_mem_map &= SECTION_MAP_MASK;
> return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
> }
>
> @@ -363,6 +364,28 @@ static void __kfree_section_memmap(struc
> }
> #endif /* CONFIG_SPARSEMEM_VMEMMAP */
>
> +static void free_section_usemap(struct page *memmap, unsigned long *usemap)
> +{
> + if (!usemap)
> + return;
> +
> + /*
> + * Check to see if allocation came from hot-plug-add
> + */
> + if (PageSlab(virt_to_page(usemap))) {
> + kfree(usemap);
> + if (memmap)
> + __kfree_section_memmap(memmap, PAGES_PER_SECTION);
> + return;
> + }
> +
> + /*
> + * TODO: Allocations came from bootmem - how do I free up ?
> + */
> + printk(KERN_WARNING "Not freeing up allocations from bootmem "
> + "- leaking memory\n");
> +}
> +
> /*
> * returns the number of sections whose mem_maps were properly
> * set. If this is <=0, then that means that the passed-in
> @@ -415,4 +438,20 @@ out:
> }
> return ret;
> }
> +
> +void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
> +{
> + struct page *memmap = NULL;
> + unsigned long *usemap = NULL;
> +
> + if (ms->section_mem_map) {
> + usemap = ms->pageblock_flags;
> + memmap = sparse_decode_mem_map(ms->section_mem_map,
> + __section_nr(ms));
> + ms->section_mem_map = 0;
> + ms->pageblock_flags = NULL;
> + }
> +
> + free_section_usemap(memmap, usemap);
> +}
> #endif
> Index: linux-2.6.25-rc5/include/linux/memory_hotplug.h
> ===================================================================
> --- linux-2.6.25-rc5.orig/include/linux/memory_hotplug.h 2008-03-21 07:00:36.000000000 -0800
> +++ linux-2.6.25-rc5/include/linux/memory_hotplug.h 2008-03-25 13:59:51.000000000 -0800
> @@ -8,6 +8,7 @@
> struct page;
> struct zone;
> struct pglist_data;
> +struct mem_section;
>
> #ifdef CONFIG_MEMORY_HOTPLUG
> /*
> @@ -64,9 +65,11 @@ extern int offline_pages(unsigned long,
> /* reasonably generic interface to expand the physical pages in a zone */
> extern int __add_pages(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);
>
> /*
> - * Walk thorugh all memory which is registered as resource.
> + * Walk through all memory which is registered as resource.
> * arg is (start_pfn, nr_pages, private_arg_pointer)
> */
> extern int walk_memory_resource(unsigned long start_pfn,
> @@ -188,5 +191,6 @@ extern int arch_add_memory(int nid, u64
> extern int remove_memory(u64 start, u64 size);
> extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
> int nr_pages);
> +extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms);
>
> #endif /* __LINUX_MEMORY_HOTPLUG_H */
>
>
--
Yasunori Goto
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