linux/mm/hugetlb.c

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/*
* 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 <asm/page.h>
#include <asm/pgtable.h>
#include <linux/hugetlb.h>
const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
static unsigned long nr_huge_pages, free_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 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 struct page *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 = (nid + 1) % num_online_nodes();
if (page) {
spin_lock(&hugetlb_lock);
nr_huge_pages++;
nr_huge_pages_node[page_to_nid(page)]++;
spin_unlock(&hugetlb_lock);
}
return page;
}
void free_huge_page(struct page *page)
{
BUG_ON(page_count(page));
INIT_LIST_HEAD(&page->lru);
[PATCH] compound page: use page[1].lru If a compound page has its own put_page_testzero destructor (the only current example is free_huge_page), that is noted in page[1].mapping of the compound page. But that's rather a poor place to keep it: functions which call set_page_dirty_lock after get_user_pages (e.g. Infiniband's __ib_umem_release) ought to be checking first, otherwise set_page_dirty is liable to crash on what's not the address of a struct address_space. And now I'm about to make that worse: it turns out that every compound page needs a destructor, so we can no longer rely on hugetlb pages going their own special way, to avoid further problems of page->mapping reuse. For example, not many people know that: on 50% of i386 -Os builds, the first tail page of a compound page purports to be PageAnon (when its destructor has an odd address), which surprises page_add_file_rmap. Keep the compound page destructor in page[1].lru.next instead. And to free up the common pairing of mapping and index, also move compound page order from index to lru.prev. Slab reuses page->lru too: but if we ever need slab to use compound pages, it can easily stack its use above this. (akpm: decoded version of the above: the tail pages of a compound page now have ->mapping==NULL, so there's no need for the set_page_dirty[_lock]() caller to check that they're not compund pages before doing the dirty). Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-14 21:52:58 +00:00
page[1].lru.next = NULL; /* reset dtor */
spin_lock(&hugetlb_lock);
enqueue_huge_page(page);
spin_unlock(&hugetlb_lock);
}
struct page *alloc_huge_page(struct vm_area_struct *vma, unsigned long addr)
{
struct page *page;
int i;
spin_lock(&hugetlb_lock);
page = dequeue_huge_page(vma, addr);
if (!page) {
spin_unlock(&hugetlb_lock);
return NULL;
}
spin_unlock(&hugetlb_lock);
set_page_count(page, 1);
[PATCH] compound page: use page[1].lru If a compound page has its own put_page_testzero destructor (the only current example is free_huge_page), that is noted in page[1].mapping of the compound page. But that's rather a poor place to keep it: functions which call set_page_dirty_lock after get_user_pages (e.g. Infiniband's __ib_umem_release) ought to be checking first, otherwise set_page_dirty is liable to crash on what's not the address of a struct address_space. And now I'm about to make that worse: it turns out that every compound page needs a destructor, so we can no longer rely on hugetlb pages going their own special way, to avoid further problems of page->mapping reuse. For example, not many people know that: on 50% of i386 -Os builds, the first tail page of a compound page purports to be PageAnon (when its destructor has an odd address), which surprises page_add_file_rmap. Keep the compound page destructor in page[1].lru.next instead. And to free up the common pairing of mapping and index, also move compound page order from index to lru.prev. Slab reuses page->lru too: but if we ever need slab to use compound pages, it can easily stack its use above this. (akpm: decoded version of the above: the tail pages of a compound page now have ->mapping==NULL, so there's no need for the set_page_dirty[_lock]() caller to check that they're not compund pages before doing the dirty). Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-14 21:52:58 +00:00
page[1].lru.next = (void *)free_huge_page; /* set dtor */
for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
clear_user_highpage(&page[i], addr);
return page;
}
static int __init hugetlb_init(void)
{
unsigned long i;
struct page *page;
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) {
page = alloc_fresh_huge_page();
if (!page)
break;
spin_lock(&hugetlb_lock);
enqueue_huge_page(page);
spin_unlock(&hugetlb_lock);
}
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);
set_page_count(&page[i], 0);
}
set_page_count(page, 1);
__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) {
struct page *page = alloc_fresh_huge_page();
if (!page)
return nr_huge_pages;
spin_lock(&hugetlb_lock);
enqueue_huge_page(page);
spin_unlock(&hugetlb_lock);
}
if (count >= nr_huge_pages)
return nr_huge_pages;
spin_lock(&hugetlb_lock);
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"
"Hugepagesize: %5lu kB\n",
nr_huge_pages,
free_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]);
}
int is_hugepage_mem_enough(size_t size)
{
return (size + ~HPAGE_MASK)/HPAGE_SIZE <= free_huge_pages;
}
/* 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);
[PATCH] mm: update_hiwaters just in time update_mem_hiwater has attracted various criticisms, in particular from those concerned with mm scalability. Originally it was called whenever rss or total_vm got raised. Then many of those callsites were replaced by a timer tick call from account_system_time. Now Frank van Maarseveen reports that to be found inadequate. How about this? Works for Frank. Replace update_mem_hiwater, a poor combination of two unrelated ops, by macros update_hiwater_rss and update_hiwater_vm. Don't attempt to keep mm->hiwater_rss up to date at timer tick, nor every time we raise rss (usually by 1): those are hot paths. Do the opposite, update only when about to lower rss (usually by many), or just before final accounting in do_exit. Handle mm->hiwater_vm in the same way, though it's much less of an issue. Demand that whoever collects these hiwater statistics do the work of taking the maximum with rss or total_vm. And there has been no collector of these hiwater statistics in the tree. The new convention needs an example, so match Frank's usage by adding a VmPeak line above VmSize to /proc/<pid>/status, and also a VmHWM line above VmRSS (High-Water-Mark or High-Water-Memory). There was a particular anomaly during mremap move, that hiwater_vm might be captured too high. A fleeting such anomaly remains, but it's quickly corrected now, whereas before it would stick. What locking? None: if the app is racy then these statistics will be racy, it's not worth any overhead to make them exact. But whenever it suits, hiwater_vm is updated under exclusive mmap_sem, and hiwater_rss under page_table_lock (for now) or with preemption disabled (later on): without going to any trouble, minimize the time between reading current values and updating, to minimize those occasions when a racing thread bumps a count up and back down in between. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 01:16:18 +00:00
/* 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 i, 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);
for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++)
copy_user_highpage(new_page + i, old_page + i,
address + i*PAGE_SIZE);
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;
}
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;
ptep = huge_pte_alloc(mm, address);
if (!ptep)
return VM_FAULT_OOM;
entry = *ptep;
if (pte_none(entry))
return hugetlb_no_page(mm, vma, address, ptep, write_access);
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);
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 vpfn, vaddr = *position;
int remainder = *length;
vpfn = vaddr/PAGE_SIZE;
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;
}
if (pages) {
page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
get_page(page);
pages[i] = page;
}
if (vmas)
vmas[i] = vma;
vaddr += PAGE_SIZE;
++vpfn;
--remainder;
++i;
}
spin_unlock(&mm->page_table_lock);
*length = remainder;
*position = vaddr;
return i;
}