const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages;
+static unsigned long surplus_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];
+static unsigned int surplus_huge_pages_node[MAX_NUMNODES];
static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
unsigned long hugepages_treat_as_movable;
+unsigned long nr_overcommit_huge_pages;
+static int hugetlb_next_nid;
/*
* Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
list_del(&page->lru);
free_huge_pages--;
free_huge_pages_node[nid]--;
+ if (vma && vma->vm_flags & VM_MAYSHARE)
+ resv_huge_pages--;
break;
}
}
static void free_huge_page(struct page *page)
{
- BUG_ON(page_count(page));
+ int nid = page_to_nid(page);
+ struct address_space *mapping;
+ mapping = (struct address_space *) page_private(page);
+ BUG_ON(page_count(page));
INIT_LIST_HEAD(&page->lru);
spin_lock(&hugetlb_lock);
- enqueue_huge_page(page);
+ if (surplus_huge_pages_node[nid]) {
+ update_and_free_page(page);
+ surplus_huge_pages--;
+ surplus_huge_pages_node[nid]--;
+ } else {
+ enqueue_huge_page(page);
+ }
spin_unlock(&hugetlb_lock);
+ if (mapping)
+ hugetlb_put_quota(mapping, 1);
+ set_page_private(page, 0);
}
-static int alloc_fresh_huge_page(void)
+/*
+ * Increment or decrement surplus_huge_pages. Keep node-specific counters
+ * balanced by operating on them in a round-robin fashion.
+ * Returns 1 if an adjustment was made.
+ */
+static int adjust_pool_surplus(int delta)
{
static int prev_nid;
- struct page *page;
- int nid;
+ int nid = prev_nid;
+ int ret = 0;
+
+ VM_BUG_ON(delta != -1 && delta != 1);
+ do {
+ nid = next_node(nid, node_online_map);
+ if (nid == MAX_NUMNODES)
+ nid = first_node(node_online_map);
+
+ /* To shrink on this node, there must be a surplus page */
+ if (delta < 0 && !surplus_huge_pages_node[nid])
+ continue;
+ /* Surplus cannot exceed the total number of pages */
+ if (delta > 0 && surplus_huge_pages_node[nid] >=
+ nr_huge_pages_node[nid])
+ continue;
+
+ surplus_huge_pages += delta;
+ surplus_huge_pages_node[nid] += delta;
+ ret = 1;
+ break;
+ } while (nid != prev_nid);
- /*
- * Copy static prev_nid to local nid, work on that, then copy it
- * back to prev_nid afterwards: otherwise there's a window in which
- * a racer might pass invalid nid MAX_NUMNODES to alloc_pages_node.
- * But we don't need to use a spin_lock here: it really doesn't
- * matter if occasionally a racer chooses the same nid as we do.
- */
- nid = next_node(prev_nid, node_online_map);
- if (nid == MAX_NUMNODES)
- nid = first_node(node_online_map);
prev_nid = nid;
+ return ret;
+}
- page = alloc_pages_node(nid, htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN,
- HUGETLB_PAGE_ORDER);
+static struct page *alloc_fresh_huge_page_node(int nid)
+{
+ struct page *page;
+
+ page = alloc_pages_node(nid,
+ htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|__GFP_NOWARN,
+ HUGETLB_PAGE_ORDER);
if (page) {
set_compound_page_dtor(page, free_huge_page);
spin_lock(&hugetlb_lock);
nr_huge_pages++;
- nr_huge_pages_node[page_to_nid(page)]++;
+ nr_huge_pages_node[nid]++;
spin_unlock(&hugetlb_lock);
put_page(page); /* free it into the hugepage allocator */
- return 1;
}
- return 0;
+
+ return page;
}
-static struct page *alloc_huge_page(struct vm_area_struct *vma,
- unsigned long addr)
+static int alloc_fresh_huge_page(void)
+{
+ struct page *page;
+ int start_nid;
+ int next_nid;
+ int ret = 0;
+
+ start_nid = hugetlb_next_nid;
+
+ do {
+ page = alloc_fresh_huge_page_node(hugetlb_next_nid);
+ if (page)
+ ret = 1;
+ /*
+ * Use a helper variable to find the next node and then
+ * copy it back to hugetlb_next_nid afterwards:
+ * otherwise there's a window in which a racer might
+ * pass invalid nid MAX_NUMNODES to alloc_pages_node.
+ * But we don't need to use a spin_lock here: it really
+ * doesn't matter if occasionally a racer chooses the
+ * same nid as we do. Move nid forward in the mask even
+ * if we just successfully allocated a hugepage so that
+ * the next caller gets hugepages on the next node.
+ */
+ next_nid = next_node(hugetlb_next_nid, node_online_map);
+ if (next_nid == MAX_NUMNODES)
+ next_nid = first_node(node_online_map);
+ hugetlb_next_nid = next_nid;
+ } while (!page && hugetlb_next_nid != start_nid);
+
+ return ret;
+}
+
+static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma,
+ unsigned long address)
{
struct page *page;
+ unsigned int nid;
+ /*
+ * Assume we will successfully allocate the surplus page to
+ * prevent racing processes from causing the surplus to exceed
+ * overcommit
+ *
+ * This however introduces a different race, where a process B
+ * tries to grow the static hugepage pool while alloc_pages() is
+ * called by process A. B will only examine the per-node
+ * counters in determining if surplus huge pages can be
+ * converted to normal huge pages in adjust_pool_surplus(). A
+ * won't be able to increment the per-node counter, until the
+ * lock is dropped by B, but B doesn't drop hugetlb_lock until
+ * no more huge pages can be converted from surplus to normal
+ * state (and doesn't try to convert again). Thus, we have a
+ * case where a surplus huge page exists, the pool is grown, and
+ * the surplus huge page still exists after, even though it
+ * should just have been converted to a normal huge page. This
+ * does not leak memory, though, as the hugepage will be freed
+ * once it is out of use. It also does not allow the counters to
+ * go out of whack in adjust_pool_surplus() as we don't modify
+ * the node values until we've gotten the hugepage and only the
+ * per-node value is checked there.
+ */
spin_lock(&hugetlb_lock);
- if (vma->vm_flags & VM_MAYSHARE)
- resv_huge_pages--;
- else if (free_huge_pages <= resv_huge_pages)
- goto fail;
+ if (surplus_huge_pages >= nr_overcommit_huge_pages) {
+ spin_unlock(&hugetlb_lock);
+ return NULL;
+ } else {
+ nr_huge_pages++;
+ surplus_huge_pages++;
+ }
+ spin_unlock(&hugetlb_lock);
+
+ page = alloc_pages(htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN,
+ HUGETLB_PAGE_ORDER);
+
+ spin_lock(&hugetlb_lock);
+ if (page) {
+ nid = page_to_nid(page);
+ set_compound_page_dtor(page, free_huge_page);
+ /*
+ * We incremented the global counters already
+ */
+ nr_huge_pages_node[nid]++;
+ surplus_huge_pages_node[nid]++;
+ } else {
+ nr_huge_pages--;
+ surplus_huge_pages--;
+ }
+ spin_unlock(&hugetlb_lock);
+
+ return page;
+}
+
+/*
+ * Increase the hugetlb pool such that it can accomodate a reservation
+ * of size 'delta'.
+ */
+static int gather_surplus_pages(int delta)
+{
+ struct list_head surplus_list;
+ struct page *page, *tmp;
+ int ret, i;
+ int needed, allocated;
+
+ needed = (resv_huge_pages + delta) - free_huge_pages;
+ if (needed <= 0)
+ return 0;
+
+ allocated = 0;
+ INIT_LIST_HEAD(&surplus_list);
+
+ ret = -ENOMEM;
+retry:
+ spin_unlock(&hugetlb_lock);
+ for (i = 0; i < needed; i++) {
+ page = alloc_buddy_huge_page(NULL, 0);
+ if (!page) {
+ /*
+ * We were not able to allocate enough pages to
+ * satisfy the entire reservation so we free what
+ * we've allocated so far.
+ */
+ spin_lock(&hugetlb_lock);
+ needed = 0;
+ goto free;
+ }
+
+ list_add(&page->lru, &surplus_list);
+ }
+ allocated += needed;
+
+ /*
+ * After retaking hugetlb_lock, we need to recalculate 'needed'
+ * because either resv_huge_pages or free_huge_pages may have changed.
+ */
+ spin_lock(&hugetlb_lock);
+ needed = (resv_huge_pages + delta) - (free_huge_pages + allocated);
+ if (needed > 0)
+ goto retry;
+
+ /*
+ * The surplus_list now contains _at_least_ the number of extra pages
+ * needed to accomodate the reservation. Add the appropriate number
+ * of pages to the hugetlb pool and free the extras back to the buddy
+ * allocator.
+ */
+ needed += allocated;
+ ret = 0;
+free:
+ list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
+ list_del(&page->lru);
+ if ((--needed) >= 0)
+ enqueue_huge_page(page);
+ else {
+ /*
+ * Decrement the refcount and free the page using its
+ * destructor. This must be done with hugetlb_lock
+ * unlocked which is safe because free_huge_page takes
+ * hugetlb_lock before deciding how to free the page.
+ */
+ spin_unlock(&hugetlb_lock);
+ put_page(page);
+ spin_lock(&hugetlb_lock);
+ }
+ }
+
+ return ret;
+}
+
+/*
+ * When releasing a hugetlb pool reservation, any surplus pages that were
+ * allocated to satisfy the reservation must be explicitly freed if they were
+ * never used.
+ */
+static void return_unused_surplus_pages(unsigned long unused_resv_pages)
+{
+ static int nid = -1;
+ struct page *page;
+ unsigned long nr_pages;
+
+ nr_pages = min(unused_resv_pages, surplus_huge_pages);
+
+ while (nr_pages) {
+ nid = next_node(nid, node_online_map);
+ if (nid == MAX_NUMNODES)
+ nid = first_node(node_online_map);
+
+ if (!surplus_huge_pages_node[nid])
+ continue;
+
+ if (!list_empty(&hugepage_freelists[nid])) {
+ page = list_entry(hugepage_freelists[nid].next,
+ struct page, lru);
+ list_del(&page->lru);
+ update_and_free_page(page);
+ free_huge_pages--;
+ free_huge_pages_node[nid]--;
+ surplus_huge_pages--;
+ surplus_huge_pages_node[nid]--;
+ nr_pages--;
+ }
+ }
+}
+
+static struct page *alloc_huge_page_shared(struct vm_area_struct *vma,
+ unsigned long addr)
+{
+ struct page *page;
+
+ spin_lock(&hugetlb_lock);
page = dequeue_huge_page(vma, addr);
- if (!page)
- goto fail;
+ spin_unlock(&hugetlb_lock);
+ return page ? page : ERR_PTR(-VM_FAULT_OOM);
+}
+static struct page *alloc_huge_page_private(struct vm_area_struct *vma,
+ unsigned long addr)
+{
+ struct page *page = NULL;
+
+ if (hugetlb_get_quota(vma->vm_file->f_mapping, 1))
+ return ERR_PTR(-VM_FAULT_SIGBUS);
+
+ spin_lock(&hugetlb_lock);
+ if (free_huge_pages > resv_huge_pages)
+ page = dequeue_huge_page(vma, addr);
spin_unlock(&hugetlb_lock);
- set_page_refcounted(page);
+ if (!page) {
+ page = alloc_buddy_huge_page(vma, addr);
+ if (!page) {
+ hugetlb_put_quota(vma->vm_file->f_mapping, 1);
+ return ERR_PTR(-VM_FAULT_OOM);
+ }
+ }
return page;
+}
+
+static struct page *alloc_huge_page(struct vm_area_struct *vma,
+ unsigned long addr)
+{
+ struct page *page;
+ struct address_space *mapping = vma->vm_file->f_mapping;
-fail:
if (vma->vm_flags & VM_MAYSHARE)
- resv_huge_pages++;
- spin_unlock(&hugetlb_lock);
- return NULL;
+ page = alloc_huge_page_shared(vma, addr);
+ else
+ page = alloc_huge_page_private(vma, addr);
+
+ if (!IS_ERR(page)) {
+ set_page_refcounted(page);
+ set_page_private(page, (unsigned long) mapping);
+ }
+ return page;
}
static int __init hugetlb_init(void)
for (i = 0; i < MAX_NUMNODES; ++i)
INIT_LIST_HEAD(&hugepage_freelists[i]);
+ hugetlb_next_nid = first_node(node_online_map);
+
for (i = 0; i < max_huge_pages; ++i) {
if (!alloc_fresh_huge_page())
break;
for (i = 0; i < MAX_NUMNODES; ++i) {
struct page *page, *next;
list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
+ if (count >= nr_huge_pages)
+ return;
if (PageHighMem(page))
continue;
list_del(&page->lru);
update_and_free_page(page);
free_huge_pages--;
free_huge_pages_node[page_to_nid(page)]--;
- if (count >= nr_huge_pages)
- return;
}
}
}
}
#endif
+#define persistent_huge_pages (nr_huge_pages - surplus_huge_pages)
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;
+ unsigned long min_count, ret;
+ /*
+ * Increase the pool size
+ * First take pages out of surplus state. Then make up the
+ * remaining difference by allocating fresh huge pages.
+ *
+ * We might race with alloc_buddy_huge_page() here and be unable
+ * to convert a surplus huge page to a normal huge page. That is
+ * not critical, though, it just means the overall size of the
+ * pool might be one hugepage larger than it needs to be, but
+ * within all the constraints specified by the sysctls.
+ */
spin_lock(&hugetlb_lock);
- count = max(count, resv_huge_pages);
- try_to_free_low(count);
- while (count < nr_huge_pages) {
+ while (surplus_huge_pages && count > persistent_huge_pages) {
+ if (!adjust_pool_surplus(-1))
+ break;
+ }
+
+ while (count > persistent_huge_pages) {
+ int ret;
+ /*
+ * If this allocation races such that we no longer need the
+ * page, free_huge_page will handle it by freeing the page
+ * and reducing the surplus.
+ */
+ spin_unlock(&hugetlb_lock);
+ ret = alloc_fresh_huge_page();
+ spin_lock(&hugetlb_lock);
+ if (!ret)
+ goto out;
+
+ }
+
+ /*
+ * Decrease the pool size
+ * First return free pages to the buddy allocator (being careful
+ * to keep enough around to satisfy reservations). Then place
+ * pages into surplus state as needed so the pool will shrink
+ * to the desired size as pages become free.
+ *
+ * By placing pages into the surplus state independent of the
+ * overcommit value, we are allowing the surplus pool size to
+ * exceed overcommit. There are few sane options here. Since
+ * alloc_buddy_huge_page() is checking the global counter,
+ * though, we'll note that we're not allowed to exceed surplus
+ * and won't grow the pool anywhere else. Not until one of the
+ * sysctls are changed, or the surplus pages go out of use.
+ */
+ min_count = resv_huge_pages + nr_huge_pages - free_huge_pages;
+ min_count = max(count, min_count);
+ try_to_free_low(min_count);
+ while (min_count < persistent_huge_pages) {
struct page *page = dequeue_huge_page(NULL, 0);
if (!page)
break;
update_and_free_page(page);
}
+ while (count < persistent_huge_pages) {
+ if (!adjust_pool_surplus(1))
+ break;
+ }
+out:
+ ret = persistent_huge_pages;
spin_unlock(&hugetlb_lock);
- return nr_huge_pages;
+ return ret;
}
int hugetlb_sysctl_handler(struct ctl_table *table, int write,
"HugePages_Total: %5lu\n"
"HugePages_Free: %5lu\n"
"HugePages_Rsvd: %5lu\n"
+ "HugePages_Surp: %5lu\n"
"Hugepagesize: %5lu kB\n",
nr_huge_pages,
free_huge_pages,
resv_huge_pages,
+ surplus_huge_pages,
HPAGE_SIZE/1024);
}
dst_pte = huge_pte_alloc(dst, addr);
if (!dst_pte)
goto nomem;
+
+ /* If the pagetables are shared don't copy or take references */
+ if (dst_pte == src_pte)
+ continue;
+
spin_lock(&dst->page_table_lock);
spin_lock(&src->page_table_lock);
if (!pte_none(*src_pte)) {
page_cache_get(old_page);
new_page = alloc_huge_page(vma, address);
- if (!new_page) {
+ if (IS_ERR(new_page)) {
page_cache_release(old_page);
- return VM_FAULT_OOM;
+ return -PTR_ERR(new_page);
}
spin_unlock(&mm->page_table_lock);
size = i_size_read(mapping->host) >> HPAGE_SHIFT;
if (idx >= size)
goto out;
- if (hugetlb_get_quota(mapping))
- goto out;
page = alloc_huge_page(vma, address);
- if (!page) {
- hugetlb_put_quota(mapping);
- ret = VM_FAULT_OOM;
+ if (IS_ERR(page)) {
+ ret = -PTR_ERR(page);
goto out;
}
clear_huge_page(page, address);
if (vma->vm_flags & VM_SHARED) {
int err;
+ struct inode *inode = mapping->host;
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;
}
+
+ spin_lock(&inode->i_lock);
+ inode->i_blocks += BLOCKS_PER_HUGEPAGE;
+ spin_unlock(&inode->i_lock);
} else
lock_page(page);
}
backout:
spin_unlock(&mm->page_table_lock);
- hugetlb_put_quota(mapping);
unlock_page(page);
put_page(page);
goto out;
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 *position, int *length, int i,
+ int write)
{
unsigned long pfn_offset;
unsigned long vaddr = *position;
*/
pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
- if (!pte || pte_none(*pte)) {
+ if (!pte || pte_none(*pte) || (write && !pte_write(*pte))) {
int ret;
spin_unlock(&mm->page_table_lock);
- ret = hugetlb_fault(mm, vma, vaddr, 0);
+ ret = hugetlb_fault(mm, vma, vaddr, write);
spin_lock(&mm->page_table_lock);
if (!(ret & VM_FAULT_ERROR))
continue;
/* 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. */
+ * size such that we can guarantee to record the reservation. */
if (&rg->link == head || t < rg->from) {
nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
- if (nrg == 0)
+ if (!nrg)
return -ENOMEM;
nrg->from = f;
nrg->to = f;
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;
/*
* When cpuset is configured, it breaks the strict hugetlb page
* reservation as the accounting is done on a global variable. Such
* a best attempt and hopefully to minimize the impact of changing
* semantics that cpuset has.
*/
- if (chg > cpuset_mems_nr(free_huge_pages_node))
- return -ENOMEM;
+ if (delta > 0) {
+ if (gather_surplus_pages(delta) < 0)
+ goto out;
+
+ if (delta > cpuset_mems_nr(free_huge_pages_node))
+ goto out;
+ }
+
+ ret = 0;
+ resv_huge_pages += delta;
+ if (delta < 0)
+ return_unused_surplus_pages((unsigned long) -delta);
+
+out:
+ 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;
+
+ if (hugetlb_get_quota(inode->i_mapping, chg))
+ return -ENOSPC;
ret = hugetlb_acct_memory(chg);
- if (ret < 0)
+ if (ret < 0) {
+ hugetlb_put_quota(inode->i_mapping, chg);
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);
+
+ spin_lock(&inode->i_lock);
+ inode->i_blocks -= BLOCKS_PER_HUGEPAGE * freed;
+ spin_unlock(&inode->i_lock);
+
+ hugetlb_put_quota(inode->i_mapping, (chg - freed));
+ hugetlb_acct_memory(-(chg - freed));
}
git.openpandora.org / pandora-kernel.git / blobdiff