linux/mm/sparse.c
Mike Kravetz 12783b002d [PATCH] SPARSEMEM incorrectly calculates section number
A bad calculation/loop in __section_nr() could result in incorrect section
information being put into sysfs memory entries.  This primarily impacts
memory add operations as the sysfs information is used while onlining new
memory.

Fix suggested by Dave Hansen.

Note that the bug may not be obvious from the patch.  It actually occurs in
the function's return statement:

	return (root_nr * SECTIONS_PER_ROOT) + (ms - root);

In the existing code, root_nr has already been multiplied by
SECTIONS_PER_ROOT.

Signed-off-by: Mike Kravetz <kravetz@us.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-05-21 12:59:17 -07:00

290 lines
6.7 KiB
C

/*
* sparse memory mappings.
*/
#include <linux/config.h>
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/bootmem.h>
#include <linux/highmem.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
#include <asm/dma.h>
/*
* Permanent SPARSEMEM data:
*
* 1) mem_section - memory sections, mem_map's for valid memory
*/
#ifdef CONFIG_SPARSEMEM_EXTREME
struct mem_section *mem_section[NR_SECTION_ROOTS]
____cacheline_internodealigned_in_smp;
#else
struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
____cacheline_internodealigned_in_smp;
#endif
EXPORT_SYMBOL(mem_section);
#ifdef CONFIG_SPARSEMEM_EXTREME
static struct mem_section *sparse_index_alloc(int nid)
{
struct mem_section *section = NULL;
unsigned long array_size = SECTIONS_PER_ROOT *
sizeof(struct mem_section);
if (slab_is_available())
section = kmalloc_node(array_size, GFP_KERNEL, nid);
else
section = alloc_bootmem_node(NODE_DATA(nid), array_size);
if (section)
memset(section, 0, array_size);
return section;
}
static int sparse_index_init(unsigned long section_nr, int nid)
{
static spinlock_t index_init_lock = SPIN_LOCK_UNLOCKED;
unsigned long root = SECTION_NR_TO_ROOT(section_nr);
struct mem_section *section;
int ret = 0;
if (mem_section[root])
return -EEXIST;
section = sparse_index_alloc(nid);
/*
* This lock keeps two different sections from
* reallocating for the same index
*/
spin_lock(&index_init_lock);
if (mem_section[root]) {
ret = -EEXIST;
goto out;
}
mem_section[root] = section;
out:
spin_unlock(&index_init_lock);
return ret;
}
#else /* !SPARSEMEM_EXTREME */
static inline int sparse_index_init(unsigned long section_nr, int nid)
{
return 0;
}
#endif
/*
* Although written for the SPARSEMEM_EXTREME case, this happens
* to also work for the flat array case becase
* NR_SECTION_ROOTS==NR_MEM_SECTIONS.
*/
int __section_nr(struct mem_section* ms)
{
unsigned long root_nr;
struct mem_section* root;
for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
if (!root)
continue;
if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
break;
}
return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
}
/* Record a memory area against a node. */
void memory_present(int nid, unsigned long start, unsigned long end)
{
unsigned long pfn;
start &= PAGE_SECTION_MASK;
for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
unsigned long section = pfn_to_section_nr(pfn);
struct mem_section *ms;
sparse_index_init(section, nid);
ms = __nr_to_section(section);
if (!ms->section_mem_map)
ms->section_mem_map = SECTION_MARKED_PRESENT;
}
}
/*
* Only used by the i386 NUMA architecures, but relatively
* generic code.
*/
unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
unsigned long end_pfn)
{
unsigned long pfn;
unsigned long nr_pages = 0;
for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
if (nid != early_pfn_to_nid(pfn))
continue;
if (pfn_valid(pfn))
nr_pages += PAGES_PER_SECTION;
}
return nr_pages * sizeof(struct page);
}
/*
* Subtle, we encode the real pfn into the mem_map such that
* the identity pfn - section_mem_map will return the actual
* physical page frame number.
*/
static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
{
return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
}
/*
* We need this if we ever free the mem_maps. While not implemented yet,
* this function is included for parity with its sibling.
*/
static __attribute((unused))
struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
{
return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
}
static int sparse_init_one_section(struct mem_section *ms,
unsigned long pnum, struct page *mem_map)
{
if (!valid_section(ms))
return -EINVAL;
ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum);
return 1;
}
static struct page *sparse_early_mem_map_alloc(unsigned long pnum)
{
struct page *map;
int nid = early_pfn_to_nid(section_nr_to_pfn(pnum));
struct mem_section *ms = __nr_to_section(pnum);
map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
if (map)
return map;
map = alloc_bootmem_node(NODE_DATA(nid),
sizeof(struct page) * PAGES_PER_SECTION);
if (map)
return map;
printk(KERN_WARNING "%s: allocation failed\n", __FUNCTION__);
ms->section_mem_map = 0;
return NULL;
}
static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
{
struct page *page, *ret;
unsigned long memmap_size = sizeof(struct page) * nr_pages;
page = alloc_pages(GFP_KERNEL, get_order(memmap_size));
if (page)
goto got_map_page;
ret = vmalloc(memmap_size);
if (ret)
goto got_map_ptr;
return NULL;
got_map_page:
ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
got_map_ptr:
memset(ret, 0, memmap_size);
return ret;
}
static int vaddr_in_vmalloc_area(void *addr)
{
if (addr >= (void *)VMALLOC_START &&
addr < (void *)VMALLOC_END)
return 1;
return 0;
}
static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
{
if (vaddr_in_vmalloc_area(memmap))
vfree(memmap);
else
free_pages((unsigned long)memmap,
get_order(sizeof(struct page) * nr_pages));
}
/*
* Allocate the accumulated non-linear sections, allocate a mem_map
* for each and record the physical to section mapping.
*/
void sparse_init(void)
{
unsigned long pnum;
struct page *map;
for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
if (!valid_section_nr(pnum))
continue;
map = sparse_early_mem_map_alloc(pnum);
if (!map)
continue;
sparse_init_one_section(__nr_to_section(pnum), pnum, map);
}
}
/*
* returns the number of sections whose mem_maps were properly
* set. If this is <=0, then that means that the passed-in
* map was not consumed and must be freed.
*/
int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
int nr_pages)
{
unsigned long section_nr = pfn_to_section_nr(start_pfn);
struct pglist_data *pgdat = zone->zone_pgdat;
struct mem_section *ms;
struct page *memmap;
unsigned long flags;
int ret;
/*
* no locking for this, because it does its own
* plus, it does a kmalloc
*/
sparse_index_init(section_nr, pgdat->node_id);
memmap = __kmalloc_section_memmap(nr_pages);
pgdat_resize_lock(pgdat, &flags);
ms = __pfn_to_section(start_pfn);
if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
ret = -EEXIST;
goto out;
}
ms->section_mem_map |= SECTION_MARKED_PRESENT;
ret = sparse_init_one_section(ms, section_nr, memmap);
out:
pgdat_resize_unlock(pgdat, &flags);
if (ret <= 0)
__kfree_section_memmap(memmap, nr_pages);
return ret;
}