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 <pbadari@us.ibm.com>
Acked-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Badari Pulavarty 2008-04-28 02:12:01 -07:00 committed by Linus Torvalds
parent 2a4e2b8780
commit ea01ea937d
3 changed files with 102 additions and 4 deletions

View File

@ -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 */

View File

@ -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)
{

View File

@ -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 @@ int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
}
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