linux/mm/hugetlb.c
Chen, Kenneth W a43a8c39bb [PATCH] tightening hugetlb strict accounting
Current hugetlb strict accounting for shared mapping always assume mapping
starts at zero file offset and reserves pages between zero and size of the
file.  This assumption often reserves (or lock down) a lot more pages then
necessary if application maps at none zero file offset.  libhugetlbfs is
one example that requires proper reservation on shared mapping starts at
none zero offset.

This patch extends the reservation and hugetlb strict accounting to support
any arbitrary pair of (offset, len), resulting a much more robust and
accurate scheme.  More importantly, it won't lock down any hugetlb pages
outside file mapping.

Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Acked-by: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 07:42:48 -07:00

798 lines
18 KiB
C

/*
* Generic hugetlb support.
* (C) William Irwin, April 2004
*/
#include <linux/gfp.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/sysctl.h>
#include <linux/highmem.h>
#include <linux/nodemask.h>
#include <linux/pagemap.h>
#include <linux/mempolicy.h>
#include <linux/cpuset.h>
#include <linux/mutex.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <linux/hugetlb.h>
#include "internal.h"
const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages;
unsigned long max_huge_pages;
static struct list_head hugepage_freelists[MAX_NUMNODES];
static unsigned int nr_huge_pages_node[MAX_NUMNODES];
static unsigned int free_huge_pages_node[MAX_NUMNODES];
/*
* Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
*/
static DEFINE_SPINLOCK(hugetlb_lock);
static void clear_huge_page(struct page *page, unsigned long addr)
{
int i;
might_sleep();
for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
cond_resched();
clear_user_highpage(page + i, addr);
}
}
static void copy_huge_page(struct page *dst, struct page *src,
unsigned long addr)
{
int i;
might_sleep();
for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) {
cond_resched();
copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE);
}
}
static void enqueue_huge_page(struct page *page)
{
int nid = page_to_nid(page);
list_add(&page->lru, &hugepage_freelists[nid]);
free_huge_pages++;
free_huge_pages_node[nid]++;
}
static struct page *dequeue_huge_page(struct vm_area_struct *vma,
unsigned long address)
{
int nid = numa_node_id();
struct page *page = NULL;
struct zonelist *zonelist = huge_zonelist(vma, address);
struct zone **z;
for (z = zonelist->zones; *z; z++) {
nid = (*z)->zone_pgdat->node_id;
if (cpuset_zone_allowed(*z, GFP_HIGHUSER) &&
!list_empty(&hugepage_freelists[nid]))
break;
}
if (*z) {
page = list_entry(hugepage_freelists[nid].next,
struct page, lru);
list_del(&page->lru);
free_huge_pages--;
free_huge_pages_node[nid]--;
}
return page;
}
static void free_huge_page(struct page *page)
{
BUG_ON(page_count(page));
INIT_LIST_HEAD(&page->lru);
spin_lock(&hugetlb_lock);
enqueue_huge_page(page);
spin_unlock(&hugetlb_lock);
}
static int alloc_fresh_huge_page(void)
{
static int nid = 0;
struct page *page;
page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
HUGETLB_PAGE_ORDER);
nid = next_node(nid, node_online_map);
if (nid == MAX_NUMNODES)
nid = first_node(node_online_map);
if (page) {
page[1].lru.next = (void *)free_huge_page; /* dtor */
spin_lock(&hugetlb_lock);
nr_huge_pages++;
nr_huge_pages_node[page_to_nid(page)]++;
spin_unlock(&hugetlb_lock);
put_page(page); /* free it into the hugepage allocator */
return 1;
}
return 0;
}
static struct page *alloc_huge_page(struct vm_area_struct *vma,
unsigned long addr)
{
struct page *page;
spin_lock(&hugetlb_lock);
if (vma->vm_flags & VM_MAYSHARE)
resv_huge_pages--;
else if (free_huge_pages <= resv_huge_pages)
goto fail;
page = dequeue_huge_page(vma, addr);
if (!page)
goto fail;
spin_unlock(&hugetlb_lock);
set_page_refcounted(page);
return page;
fail:
spin_unlock(&hugetlb_lock);
return NULL;
}
static int __init hugetlb_init(void)
{
unsigned long i;
if (HPAGE_SHIFT == 0)
return 0;
for (i = 0; i < MAX_NUMNODES; ++i)
INIT_LIST_HEAD(&hugepage_freelists[i]);
for (i = 0; i < max_huge_pages; ++i) {
if (!alloc_fresh_huge_page())
break;
}
max_huge_pages = free_huge_pages = nr_huge_pages = i;
printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
return 0;
}
module_init(hugetlb_init);
static int __init hugetlb_setup(char *s)
{
if (sscanf(s, "%lu", &max_huge_pages) <= 0)
max_huge_pages = 0;
return 1;
}
__setup("hugepages=", hugetlb_setup);
#ifdef CONFIG_SYSCTL
static void update_and_free_page(struct page *page)
{
int i;
nr_huge_pages--;
nr_huge_pages_node[page_zone(page)->zone_pgdat->node_id]--;
for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
1 << PG_private | 1<< PG_writeback);
}
page[1].lru.next = NULL;
set_page_refcounted(page);
__free_pages(page, HUGETLB_PAGE_ORDER);
}
#ifdef CONFIG_HIGHMEM
static void try_to_free_low(unsigned long count)
{
int i, nid;
for (i = 0; i < MAX_NUMNODES; ++i) {
struct page *page, *next;
list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
if (PageHighMem(page))
continue;
list_del(&page->lru);
update_and_free_page(page);
nid = page_zone(page)->zone_pgdat->node_id;
free_huge_pages--;
free_huge_pages_node[nid]--;
if (count >= nr_huge_pages)
return;
}
}
}
#else
static inline void try_to_free_low(unsigned long count)
{
}
#endif
static unsigned long set_max_huge_pages(unsigned long count)
{
while (count > nr_huge_pages) {
if (!alloc_fresh_huge_page())
return nr_huge_pages;
}
if (count >= nr_huge_pages)
return nr_huge_pages;
spin_lock(&hugetlb_lock);
count = max(count, resv_huge_pages);
try_to_free_low(count);
while (count < nr_huge_pages) {
struct page *page = dequeue_huge_page(NULL, 0);
if (!page)
break;
update_and_free_page(page);
}
spin_unlock(&hugetlb_lock);
return nr_huge_pages;
}
int hugetlb_sysctl_handler(struct ctl_table *table, int write,
struct file *file, void __user *buffer,
size_t *length, loff_t *ppos)
{
proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
max_huge_pages = set_max_huge_pages(max_huge_pages);
return 0;
}
#endif /* CONFIG_SYSCTL */
int hugetlb_report_meminfo(char *buf)
{
return sprintf(buf,
"HugePages_Total: %5lu\n"
"HugePages_Free: %5lu\n"
"HugePages_Rsvd: %5lu\n"
"Hugepagesize: %5lu kB\n",
nr_huge_pages,
free_huge_pages,
resv_huge_pages,
HPAGE_SIZE/1024);
}
int hugetlb_report_node_meminfo(int nid, char *buf)
{
return sprintf(buf,
"Node %d HugePages_Total: %5u\n"
"Node %d HugePages_Free: %5u\n",
nid, nr_huge_pages_node[nid],
nid, free_huge_pages_node[nid]);
}
/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
unsigned long hugetlb_total_pages(void)
{
return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
}
/*
* We cannot handle pagefaults against hugetlb pages at all. They cause
* handle_mm_fault() to try to instantiate regular-sized pages in the
* hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
* this far.
*/
static struct page *hugetlb_nopage(struct vm_area_struct *vma,
unsigned long address, int *unused)
{
BUG();
return NULL;
}
struct vm_operations_struct hugetlb_vm_ops = {
.nopage = hugetlb_nopage,
};
static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
int writable)
{
pte_t entry;
if (writable) {
entry =
pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
} else {
entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
}
entry = pte_mkyoung(entry);
entry = pte_mkhuge(entry);
return entry;
}
static void set_huge_ptep_writable(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep)
{
pte_t entry;
entry = pte_mkwrite(pte_mkdirty(*ptep));
ptep_set_access_flags(vma, address, ptep, entry, 1);
update_mmu_cache(vma, address, entry);
lazy_mmu_prot_update(entry);
}
int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
struct vm_area_struct *vma)
{
pte_t *src_pte, *dst_pte, entry;
struct page *ptepage;
unsigned long addr;
int cow;
cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
src_pte = huge_pte_offset(src, addr);
if (!src_pte)
continue;
dst_pte = huge_pte_alloc(dst, addr);
if (!dst_pte)
goto nomem;
spin_lock(&dst->page_table_lock);
spin_lock(&src->page_table_lock);
if (!pte_none(*src_pte)) {
if (cow)
ptep_set_wrprotect(src, addr, src_pte);
entry = *src_pte;
ptepage = pte_page(entry);
get_page(ptepage);
add_mm_counter(dst, file_rss, HPAGE_SIZE / PAGE_SIZE);
set_huge_pte_at(dst, addr, dst_pte, entry);
}
spin_unlock(&src->page_table_lock);
spin_unlock(&dst->page_table_lock);
}
return 0;
nomem:
return -ENOMEM;
}
void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
unsigned long end)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long address;
pte_t *ptep;
pte_t pte;
struct page *page;
WARN_ON(!is_vm_hugetlb_page(vma));
BUG_ON(start & ~HPAGE_MASK);
BUG_ON(end & ~HPAGE_MASK);
spin_lock(&mm->page_table_lock);
/* Update high watermark before we lower rss */
update_hiwater_rss(mm);
for (address = start; address < end; address += HPAGE_SIZE) {
ptep = huge_pte_offset(mm, address);
if (!ptep)
continue;
pte = huge_ptep_get_and_clear(mm, address, ptep);
if (pte_none(pte))
continue;
page = pte_page(pte);
put_page(page);
add_mm_counter(mm, file_rss, (int) -(HPAGE_SIZE / PAGE_SIZE));
}
spin_unlock(&mm->page_table_lock);
flush_tlb_range(vma, start, end);
}
static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, pte_t *ptep, pte_t pte)
{
struct page *old_page, *new_page;
int avoidcopy;
old_page = pte_page(pte);
/* If no-one else is actually using this page, avoid the copy
* and just make the page writable */
avoidcopy = (page_count(old_page) == 1);
if (avoidcopy) {
set_huge_ptep_writable(vma, address, ptep);
return VM_FAULT_MINOR;
}
page_cache_get(old_page);
new_page = alloc_huge_page(vma, address);
if (!new_page) {
page_cache_release(old_page);
return VM_FAULT_OOM;
}
spin_unlock(&mm->page_table_lock);
copy_huge_page(new_page, old_page, address);
spin_lock(&mm->page_table_lock);
ptep = huge_pte_offset(mm, address & HPAGE_MASK);
if (likely(pte_same(*ptep, pte))) {
/* Break COW */
set_huge_pte_at(mm, address, ptep,
make_huge_pte(vma, new_page, 1));
/* Make the old page be freed below */
new_page = old_page;
}
page_cache_release(new_page);
page_cache_release(old_page);
return VM_FAULT_MINOR;
}
int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, pte_t *ptep, int write_access)
{
int ret = VM_FAULT_SIGBUS;
unsigned long idx;
unsigned long size;
struct page *page;
struct address_space *mapping;
pte_t new_pte;
mapping = vma->vm_file->f_mapping;
idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
+ (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
/*
* Use page lock to guard against racing truncation
* before we get page_table_lock.
*/
retry:
page = find_lock_page(mapping, idx);
if (!page) {
if (hugetlb_get_quota(mapping))
goto out;
page = alloc_huge_page(vma, address);
if (!page) {
hugetlb_put_quota(mapping);
ret = VM_FAULT_OOM;
goto out;
}
clear_huge_page(page, address);
if (vma->vm_flags & VM_SHARED) {
int err;
err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
if (err) {
put_page(page);
hugetlb_put_quota(mapping);
if (err == -EEXIST)
goto retry;
goto out;
}
} else
lock_page(page);
}
spin_lock(&mm->page_table_lock);
size = i_size_read(mapping->host) >> HPAGE_SHIFT;
if (idx >= size)
goto backout;
ret = VM_FAULT_MINOR;
if (!pte_none(*ptep))
goto backout;
add_mm_counter(mm, file_rss, HPAGE_SIZE / PAGE_SIZE);
new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
&& (vma->vm_flags & VM_SHARED)));
set_huge_pte_at(mm, address, ptep, new_pte);
if (write_access && !(vma->vm_flags & VM_SHARED)) {
/* Optimization, do the COW without a second fault */
ret = hugetlb_cow(mm, vma, address, ptep, new_pte);
}
spin_unlock(&mm->page_table_lock);
unlock_page(page);
out:
return ret;
backout:
spin_unlock(&mm->page_table_lock);
hugetlb_put_quota(mapping);
unlock_page(page);
put_page(page);
goto out;
}
int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, int write_access)
{
pte_t *ptep;
pte_t entry;
int ret;
static DEFINE_MUTEX(hugetlb_instantiation_mutex);
ptep = huge_pte_alloc(mm, address);
if (!ptep)
return VM_FAULT_OOM;
/*
* Serialize hugepage allocation and instantiation, so that we don't
* get spurious allocation failures if two CPUs race to instantiate
* the same page in the page cache.
*/
mutex_lock(&hugetlb_instantiation_mutex);
entry = *ptep;
if (pte_none(entry)) {
ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
mutex_unlock(&hugetlb_instantiation_mutex);
return ret;
}
ret = VM_FAULT_MINOR;
spin_lock(&mm->page_table_lock);
/* Check for a racing update before calling hugetlb_cow */
if (likely(pte_same(entry, *ptep)))
if (write_access && !pte_write(entry))
ret = hugetlb_cow(mm, vma, address, ptep, entry);
spin_unlock(&mm->page_table_lock);
mutex_unlock(&hugetlb_instantiation_mutex);
return ret;
}
int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
struct page **pages, struct vm_area_struct **vmas,
unsigned long *position, int *length, int i)
{
unsigned long pfn_offset;
unsigned long vaddr = *position;
int remainder = *length;
spin_lock(&mm->page_table_lock);
while (vaddr < vma->vm_end && remainder) {
pte_t *pte;
struct page *page;
/*
* Some archs (sparc64, sh*) have multiple pte_ts to
* each hugepage. We have to make * sure we get the
* first, for the page indexing below to work.
*/
pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
if (!pte || pte_none(*pte)) {
int ret;
spin_unlock(&mm->page_table_lock);
ret = hugetlb_fault(mm, vma, vaddr, 0);
spin_lock(&mm->page_table_lock);
if (ret == VM_FAULT_MINOR)
continue;
remainder = 0;
if (!i)
i = -EFAULT;
break;
}
pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
page = pte_page(*pte);
same_page:
if (pages) {
get_page(page);
pages[i] = page + pfn_offset;
}
if (vmas)
vmas[i] = vma;
vaddr += PAGE_SIZE;
++pfn_offset;
--remainder;
++i;
if (vaddr < vma->vm_end && remainder &&
pfn_offset < HPAGE_SIZE/PAGE_SIZE) {
/*
* We use pfn_offset to avoid touching the pageframes
* of this compound page.
*/
goto same_page;
}
}
spin_unlock(&mm->page_table_lock);
*length = remainder;
*position = vaddr;
return i;
}
void hugetlb_change_protection(struct vm_area_struct *vma,
unsigned long address, unsigned long end, pgprot_t newprot)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long start = address;
pte_t *ptep;
pte_t pte;
BUG_ON(address >= end);
flush_cache_range(vma, address, end);
spin_lock(&mm->page_table_lock);
for (; address < end; address += HPAGE_SIZE) {
ptep = huge_pte_offset(mm, address);
if (!ptep)
continue;
if (!pte_none(*ptep)) {
pte = huge_ptep_get_and_clear(mm, address, ptep);
pte = pte_mkhuge(pte_modify(pte, newprot));
set_huge_pte_at(mm, address, ptep, pte);
lazy_mmu_prot_update(pte);
}
}
spin_unlock(&mm->page_table_lock);
flush_tlb_range(vma, start, end);
}
struct file_region {
struct list_head link;
long from;
long to;
};
static long region_add(struct list_head *head, long f, long t)
{
struct file_region *rg, *nrg, *trg;
/* Locate the region we are either in or before. */
list_for_each_entry(rg, head, link)
if (f <= rg->to)
break;
/* Round our left edge to the current segment if it encloses us. */
if (f > rg->from)
f = rg->from;
/* Check for and consume any regions we now overlap with. */
nrg = rg;
list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
if (&rg->link == head)
break;
if (rg->from > t)
break;
/* If this area reaches higher then extend our area to
* include it completely. If this is not the first area
* which we intend to reuse, free it. */
if (rg->to > t)
t = rg->to;
if (rg != nrg) {
list_del(&rg->link);
kfree(rg);
}
}
nrg->from = f;
nrg->to = t;
return 0;
}
static long region_chg(struct list_head *head, long f, long t)
{
struct file_region *rg, *nrg;
long chg = 0;
/* Locate the region we are before or in. */
list_for_each_entry(rg, head, link)
if (f <= rg->to)
break;
/* If we are below the current region then a new region is required.
* Subtle, allocate a new region at the position but make it zero
* size such that we can guarentee to record the reservation. */
if (&rg->link == head || t < rg->from) {
nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
if (nrg == 0)
return -ENOMEM;
nrg->from = f;
nrg->to = f;
INIT_LIST_HEAD(&nrg->link);
list_add(&nrg->link, rg->link.prev);
return t - f;
}
/* Round our left edge to the current segment if it encloses us. */
if (f > rg->from)
f = rg->from;
chg = t - f;
/* Check for and consume any regions we now overlap with. */
list_for_each_entry(rg, rg->link.prev, link) {
if (&rg->link == head)
break;
if (rg->from > t)
return chg;
/* We overlap with this area, if it extends futher than
* us then we must extend ourselves. Account for its
* existing reservation. */
if (rg->to > t) {
chg += rg->to - t;
t = rg->to;
}
chg -= rg->to - rg->from;
}
return chg;
}
static long region_truncate(struct list_head *head, long end)
{
struct file_region *rg, *trg;
long chg = 0;
/* Locate the region we are either in or before. */
list_for_each_entry(rg, head, link)
if (end <= rg->to)
break;
if (&rg->link == head)
return 0;
/* If we are in the middle of a region then adjust it. */
if (end > rg->from) {
chg = rg->to - end;
rg->to = end;
rg = list_entry(rg->link.next, typeof(*rg), link);
}
/* Drop any remaining regions. */
list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
if (&rg->link == head)
break;
chg += rg->to - rg->from;
list_del(&rg->link);
kfree(rg);
}
return chg;
}
static int hugetlb_acct_memory(long delta)
{
int ret = -ENOMEM;
spin_lock(&hugetlb_lock);
if ((delta + resv_huge_pages) <= free_huge_pages) {
resv_huge_pages += delta;
ret = 0;
}
spin_unlock(&hugetlb_lock);
return ret;
}
int hugetlb_reserve_pages(struct inode *inode, long from, long to)
{
long ret, chg;
chg = region_chg(&inode->i_mapping->private_list, from, to);
if (chg < 0)
return chg;
ret = hugetlb_acct_memory(chg);
if (ret < 0)
return ret;
region_add(&inode->i_mapping->private_list, from, to);
return 0;
}
void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
{
long chg = region_truncate(&inode->i_mapping->private_list, offset);
hugetlb_acct_memory(freed - chg);
}