kernel-fxtec-pro1x/mm/bootmem.c
Nick Piggin b5810039a5 [PATCH] core remove PageReserved
Remove PageReserved() calls from core code by tightening VM_RESERVED
handling in mm/ to cover PageReserved functionality.

PageReserved special casing is removed from get_page and put_page.

All setting and clearing of PageReserved is retained, and it is now flagged
in the page_alloc checks to help ensure we don't introduce any refcount
based freeing of Reserved pages.

MAP_PRIVATE, PROT_WRITE of VM_RESERVED regions is tentatively being
deprecated.  We never completely handled it correctly anyway, and is be
reintroduced in future if required (Hugh has a proof of concept).

Once PageReserved() calls are removed from kernel/power/swsusp.c, and all
arch/ and driver code, the Set and Clear calls, and the PG_reserved bit can
be trivially removed.

Last real user of PageReserved is swsusp, which uses PageReserved to
determine whether a struct page points to valid memory or not.  This still
needs to be addressed (a generic page_is_ram() should work).

A last caveat: the ZERO_PAGE is now refcounted and managed with rmap (and
thus mapcounted and count towards shared rss).  These writes to the struct
page could cause excessive cacheline bouncing on big systems.  There are a
number of ways this could be addressed if it is an issue.

Signed-off-by: Nick Piggin <npiggin@suse.de>

Refcount bug fix for filemap_xip.c

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 21:40:39 -07:00

425 lines
11 KiB
C

/*
* linux/mm/bootmem.c
*
* Copyright (C) 1999 Ingo Molnar
* Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
*
* simple boot-time physical memory area allocator and
* free memory collector. It's used to deal with reserved
* system memory and memory holes as well.
*/
#include <linux/mm.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/mmzone.h>
#include <linux/module.h>
#include <asm/dma.h>
#include <asm/io.h>
#include "internal.h"
/*
* Access to this subsystem has to be serialized externally. (this is
* true for the boot process anyway)
*/
unsigned long max_low_pfn;
unsigned long min_low_pfn;
unsigned long max_pfn;
EXPORT_SYMBOL(max_pfn); /* This is exported so
* dma_get_required_mask(), which uses
* it, can be an inline function */
#ifdef CONFIG_CRASH_DUMP
/*
* If we have booted due to a crash, max_pfn will be a very low value. We need
* to know the amount of memory that the previous kernel used.
*/
unsigned long saved_max_pfn;
#endif
/* return the number of _pages_ that will be allocated for the boot bitmap */
unsigned long __init bootmem_bootmap_pages (unsigned long pages)
{
unsigned long mapsize;
mapsize = (pages+7)/8;
mapsize = (mapsize + ~PAGE_MASK) & PAGE_MASK;
mapsize >>= PAGE_SHIFT;
return mapsize;
}
/*
* Called once to set up the allocator itself.
*/
static unsigned long __init init_bootmem_core (pg_data_t *pgdat,
unsigned long mapstart, unsigned long start, unsigned long end)
{
bootmem_data_t *bdata = pgdat->bdata;
unsigned long mapsize = ((end - start)+7)/8;
pgdat->pgdat_next = pgdat_list;
pgdat_list = pgdat;
mapsize = ALIGN(mapsize, sizeof(long));
bdata->node_bootmem_map = phys_to_virt(mapstart << PAGE_SHIFT);
bdata->node_boot_start = (start << PAGE_SHIFT);
bdata->node_low_pfn = end;
/*
* Initially all pages are reserved - setup_arch() has to
* register free RAM areas explicitly.
*/
memset(bdata->node_bootmem_map, 0xff, mapsize);
return mapsize;
}
/*
* Marks a particular physical memory range as unallocatable. Usable RAM
* might be used for boot-time allocations - or it might get added
* to the free page pool later on.
*/
static void __init reserve_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)
{
unsigned long i;
/*
* round up, partially reserved pages are considered
* fully reserved.
*/
unsigned long sidx = (addr - bdata->node_boot_start)/PAGE_SIZE;
unsigned long eidx = (addr + size - bdata->node_boot_start +
PAGE_SIZE-1)/PAGE_SIZE;
unsigned long end = (addr + size + PAGE_SIZE-1)/PAGE_SIZE;
BUG_ON(!size);
BUG_ON(sidx >= eidx);
BUG_ON((addr >> PAGE_SHIFT) >= bdata->node_low_pfn);
BUG_ON(end > bdata->node_low_pfn);
for (i = sidx; i < eidx; i++)
if (test_and_set_bit(i, bdata->node_bootmem_map)) {
#ifdef CONFIG_DEBUG_BOOTMEM
printk("hm, page %08lx reserved twice.\n", i*PAGE_SIZE);
#endif
}
}
static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)
{
unsigned long i;
unsigned long start;
/*
* round down end of usable mem, partially free pages are
* considered reserved.
*/
unsigned long sidx;
unsigned long eidx = (addr + size - bdata->node_boot_start)/PAGE_SIZE;
unsigned long end = (addr + size)/PAGE_SIZE;
BUG_ON(!size);
BUG_ON(end > bdata->node_low_pfn);
if (addr < bdata->last_success)
bdata->last_success = addr;
/*
* Round up the beginning of the address.
*/
start = (addr + PAGE_SIZE-1) / PAGE_SIZE;
sidx = start - (bdata->node_boot_start/PAGE_SIZE);
for (i = sidx; i < eidx; i++) {
if (unlikely(!test_and_clear_bit(i, bdata->node_bootmem_map)))
BUG();
}
}
/*
* We 'merge' subsequent allocations to save space. We might 'lose'
* some fraction of a page if allocations cannot be satisfied due to
* size constraints on boxes where there is physical RAM space
* fragmentation - in these cases (mostly large memory boxes) this
* is not a problem.
*
* On low memory boxes we get it right in 100% of the cases.
*
* alignment has to be a power of 2 value.
*
* NOTE: This function is _not_ reentrant.
*/
static void * __init
__alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size,
unsigned long align, unsigned long goal, unsigned long limit)
{
unsigned long offset, remaining_size, areasize, preferred;
unsigned long i, start = 0, incr, eidx, end_pfn = bdata->node_low_pfn;
void *ret;
if(!size) {
printk("__alloc_bootmem_core(): zero-sized request\n");
BUG();
}
BUG_ON(align & (align-1));
if (limit && bdata->node_boot_start >= limit)
return NULL;
limit >>=PAGE_SHIFT;
if (limit && end_pfn > limit)
end_pfn = limit;
eidx = end_pfn - (bdata->node_boot_start >> PAGE_SHIFT);
offset = 0;
if (align &&
(bdata->node_boot_start & (align - 1UL)) != 0)
offset = (align - (bdata->node_boot_start & (align - 1UL)));
offset >>= PAGE_SHIFT;
/*
* We try to allocate bootmem pages above 'goal'
* first, then we try to allocate lower pages.
*/
if (goal && (goal >= bdata->node_boot_start) &&
((goal >> PAGE_SHIFT) < end_pfn)) {
preferred = goal - bdata->node_boot_start;
if (bdata->last_success >= preferred)
if (!limit || (limit && limit > bdata->last_success))
preferred = bdata->last_success;
} else
preferred = 0;
preferred = ALIGN(preferred, align) >> PAGE_SHIFT;
preferred += offset;
areasize = (size+PAGE_SIZE-1)/PAGE_SIZE;
incr = align >> PAGE_SHIFT ? : 1;
restart_scan:
for (i = preferred; i < eidx; i += incr) {
unsigned long j;
i = find_next_zero_bit(bdata->node_bootmem_map, eidx, i);
i = ALIGN(i, incr);
if (test_bit(i, bdata->node_bootmem_map))
continue;
for (j = i + 1; j < i + areasize; ++j) {
if (j >= eidx)
goto fail_block;
if (test_bit (j, bdata->node_bootmem_map))
goto fail_block;
}
start = i;
goto found;
fail_block:
i = ALIGN(j, incr);
}
if (preferred > offset) {
preferred = offset;
goto restart_scan;
}
return NULL;
found:
bdata->last_success = start << PAGE_SHIFT;
BUG_ON(start >= eidx);
/*
* Is the next page of the previous allocation-end the start
* of this allocation's buffer? If yes then we can 'merge'
* the previous partial page with this allocation.
*/
if (align < PAGE_SIZE &&
bdata->last_offset && bdata->last_pos+1 == start) {
offset = ALIGN(bdata->last_offset, align);
BUG_ON(offset > PAGE_SIZE);
remaining_size = PAGE_SIZE-offset;
if (size < remaining_size) {
areasize = 0;
/* last_pos unchanged */
bdata->last_offset = offset+size;
ret = phys_to_virt(bdata->last_pos*PAGE_SIZE + offset +
bdata->node_boot_start);
} else {
remaining_size = size - remaining_size;
areasize = (remaining_size+PAGE_SIZE-1)/PAGE_SIZE;
ret = phys_to_virt(bdata->last_pos*PAGE_SIZE + offset +
bdata->node_boot_start);
bdata->last_pos = start+areasize-1;
bdata->last_offset = remaining_size;
}
bdata->last_offset &= ~PAGE_MASK;
} else {
bdata->last_pos = start + areasize - 1;
bdata->last_offset = size & ~PAGE_MASK;
ret = phys_to_virt(start * PAGE_SIZE + bdata->node_boot_start);
}
/*
* Reserve the area now:
*/
for (i = start; i < start+areasize; i++)
if (unlikely(test_and_set_bit(i, bdata->node_bootmem_map)))
BUG();
memset(ret, 0, size);
return ret;
}
static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
{
struct page *page;
unsigned long pfn;
bootmem_data_t *bdata = pgdat->bdata;
unsigned long i, count, total = 0;
unsigned long idx;
unsigned long *map;
int gofast = 0;
BUG_ON(!bdata->node_bootmem_map);
count = 0;
/* first extant page of the node */
pfn = bdata->node_boot_start >> PAGE_SHIFT;
idx = bdata->node_low_pfn - (bdata->node_boot_start >> PAGE_SHIFT);
map = bdata->node_bootmem_map;
/* Check physaddr is O(LOG2(BITS_PER_LONG)) page aligned */
if (bdata->node_boot_start == 0 ||
ffs(bdata->node_boot_start) - PAGE_SHIFT > ffs(BITS_PER_LONG))
gofast = 1;
for (i = 0; i < idx; ) {
unsigned long v = ~map[i / BITS_PER_LONG];
if (gofast && v == ~0UL) {
int j, order;
page = pfn_to_page(pfn);
count += BITS_PER_LONG;
__ClearPageReserved(page);
order = ffs(BITS_PER_LONG) - 1;
set_page_refs(page, order);
for (j = 1; j < BITS_PER_LONG; j++) {
if (j + 16 < BITS_PER_LONG)
prefetchw(page + j + 16);
__ClearPageReserved(page + j);
set_page_count(page + j, 0);
}
__free_pages(page, order);
i += BITS_PER_LONG;
page += BITS_PER_LONG;
} else if (v) {
unsigned long m;
page = pfn_to_page(pfn);
for (m = 1; m && i < idx; m<<=1, page++, i++) {
if (v & m) {
count++;
__ClearPageReserved(page);
set_page_refs(page, 0);
__free_page(page);
}
}
} else {
i+=BITS_PER_LONG;
}
pfn += BITS_PER_LONG;
}
total += count;
/*
* Now free the allocator bitmap itself, it's not
* needed anymore:
*/
page = virt_to_page(bdata->node_bootmem_map);
count = 0;
for (i = 0; i < ((bdata->node_low_pfn-(bdata->node_boot_start >> PAGE_SHIFT))/8 + PAGE_SIZE-1)/PAGE_SIZE; i++,page++) {
count++;
__ClearPageReserved(page);
set_page_count(page, 1);
__free_page(page);
}
total += count;
bdata->node_bootmem_map = NULL;
return total;
}
unsigned long __init init_bootmem_node (pg_data_t *pgdat, unsigned long freepfn, unsigned long startpfn, unsigned long endpfn)
{
return(init_bootmem_core(pgdat, freepfn, startpfn, endpfn));
}
void __init reserve_bootmem_node (pg_data_t *pgdat, unsigned long physaddr, unsigned long size)
{
reserve_bootmem_core(pgdat->bdata, physaddr, size);
}
void __init free_bootmem_node (pg_data_t *pgdat, unsigned long physaddr, unsigned long size)
{
free_bootmem_core(pgdat->bdata, physaddr, size);
}
unsigned long __init free_all_bootmem_node (pg_data_t *pgdat)
{
return(free_all_bootmem_core(pgdat));
}
unsigned long __init init_bootmem (unsigned long start, unsigned long pages)
{
max_low_pfn = pages;
min_low_pfn = start;
return(init_bootmem_core(NODE_DATA(0), start, 0, pages));
}
#ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
void __init reserve_bootmem (unsigned long addr, unsigned long size)
{
reserve_bootmem_core(NODE_DATA(0)->bdata, addr, size);
}
#endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */
void __init free_bootmem (unsigned long addr, unsigned long size)
{
free_bootmem_core(NODE_DATA(0)->bdata, addr, size);
}
unsigned long __init free_all_bootmem (void)
{
return(free_all_bootmem_core(NODE_DATA(0)));
}
void * __init __alloc_bootmem_limit (unsigned long size, unsigned long align, unsigned long goal,
unsigned long limit)
{
pg_data_t *pgdat = pgdat_list;
void *ptr;
for_each_pgdat(pgdat)
if ((ptr = __alloc_bootmem_core(pgdat->bdata, size,
align, goal, limit)))
return(ptr);
/*
* Whoops, we cannot satisfy the allocation request.
*/
printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
panic("Out of memory");
return NULL;
}
void * __init __alloc_bootmem_node_limit (pg_data_t *pgdat, unsigned long size, unsigned long align,
unsigned long goal, unsigned long limit)
{
void *ptr;
ptr = __alloc_bootmem_core(pgdat->bdata, size, align, goal, limit);
if (ptr)
return (ptr);
return __alloc_bootmem_limit(size, align, goal, limit);
}