From: Badari Pulavarty Date: Mon, 28 Apr 2008 09:12:01 +0000 (-0700) Subject: hotplug memory remove: generic __remove_pages() support X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=ea01ea937dcae2caa146dea1918cccf2f16ed3c4;p=openwrt%2Fstaging%2Fblogic.git hotplug memory remove: generic __remove_pages() support 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 free up allocations from bootmem. Signed-off-by: Badari Pulavarty Acked-by: Yasunori Goto Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 8fee7a45736b..aca9c65f8d08 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -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, unsigned long, 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, @@ -176,5 +179,6 @@ extern int arch_add_memory(int nid, u64 start, u64 size); 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 */ diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 0fb330271271..d5094929766d 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -101,6 +101,25 @@ static int __add_section(struct zone *zone, unsigned long phys_start_pfn) 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 @@ -134,6 +153,42 @@ int __add_pages(struct zone *zone, unsigned long phys_start_pfn, } 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) { diff --git a/mm/sparse.c b/mm/sparse.c index 7e9191381f86..186a85bf7912 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -208,12 +208,13 @@ static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long p } /* - * 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); } @@ -404,6 +405,28 @@ static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages) } #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 @@ -456,4 +479,20 @@ 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