#include <linux/security.h>
#include <linux/memcontrol.h>
#include <linux/syscalls.h>
+#include <linux/hugetlb.h>
+#include <linux/gfp.h>
+
+#include <asm/tlbflush.h>
#include "internal.h"
/*
* migrate_prep() needs to be called before we start compiling a list of pages
- * to be migrated using isolate_lru_page().
+ * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
+ * undesirable, use migrate_prep_local()
*/
int migrate_prep(void)
{
return 0;
}
+/* Do the necessary work of migrate_prep but not if it involves other CPUs */
+int migrate_prep_local(void)
+{
+ lru_add_drain();
+
+ return 0;
+}
+
/*
* Add isolated pages on the list back to the LRU under page lock
* to avoid leaking evictable pages back onto unevictable list.
- *
- * returns the number of pages put back.
*/
-int putback_lru_pages(struct list_head *l)
+void putback_lru_pages(struct list_head *l)
{
struct page *page;
struct page *page2;
- int count = 0;
list_for_each_entry_safe(page, page2, l, lru) {
list_del(&page->lru);
dec_zone_page_state(page, NR_ISOLATED_ANON +
page_is_file_cache(page));
putback_lru_page(page);
- count++;
}
- return count;
}
/*
pte_t *ptep, pte;
spinlock_t *ptl;
- pgd = pgd_offset(mm, addr);
- if (!pgd_present(*pgd))
- goto out;
+ if (unlikely(PageHuge(new))) {
+ ptep = huge_pte_offset(mm, addr);
+ if (!ptep)
+ goto out;
+ ptl = &mm->page_table_lock;
+ } else {
+ pgd = pgd_offset(mm, addr);
+ if (!pgd_present(*pgd))
+ goto out;
- pud = pud_offset(pgd, addr);
- if (!pud_present(*pud))
- goto out;
+ pud = pud_offset(pgd, addr);
+ if (!pud_present(*pud))
+ goto out;
- pmd = pmd_offset(pud, addr);
- if (!pmd_present(*pmd))
- goto out;
+ pmd = pmd_offset(pud, addr);
+ if (pmd_trans_huge(*pmd))
+ goto out;
+ if (!pmd_present(*pmd))
+ goto out;
- ptep = pte_offset_map(pmd, addr);
+ ptep = pte_offset_map(pmd, addr);
- if (!is_swap_pte(*ptep)) {
- pte_unmap(ptep);
- goto out;
- }
+ if (!is_swap_pte(*ptep)) {
+ pte_unmap(ptep);
+ goto out;
+ }
+
+ ptl = pte_lockptr(mm, pmd);
+ }
- ptl = pte_lockptr(mm, pmd);
spin_lock(ptl);
pte = *ptep;
if (!is_swap_pte(pte))
pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
if (is_write_migration_entry(entry))
pte = pte_mkwrite(pte);
+#ifdef CONFIG_HUGETLB_PAGE
+ if (PageHuge(new))
+ pte = pte_mkhuge(pte);
+#endif
flush_cache_page(vma, addr, pte_pfn(pte));
set_pte_at(mm, addr, ptep, pte);
- if (PageAnon(new))
+ if (PageHuge(new)) {
+ if (PageAnon(new))
+ hugepage_add_anon_rmap(new, vma, addr);
+ else
+ page_dup_rmap(new);
+ } else if (PageAnon(new))
page_add_anon_rmap(new, vma, addr);
else
page_add_file_rmap(new);
expected_count = 2 + page_has_private(page);
if (page_count(page) != expected_count ||
- (struct page *)radix_tree_deref_slot(pslot) != page) {
+ radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
spin_unlock_irq(&mapping->tree_lock);
return -EAGAIN;
}
}
/*
+ * The expected number of remaining references is the same as that
+ * of migrate_page_move_mapping().
+ */
+int migrate_huge_page_move_mapping(struct address_space *mapping,
+ struct page *newpage, struct page *page)
+{
+ int expected_count;
+ void **pslot;
+
+ if (!mapping) {
+ if (page_count(page) != 1)
+ return -EAGAIN;
+ return 0;
+ }
+
+ spin_lock_irq(&mapping->tree_lock);
+
+ pslot = radix_tree_lookup_slot(&mapping->page_tree,
+ page_index(page));
+
+ expected_count = 2 + page_has_private(page);
+ if (page_count(page) != expected_count ||
+ radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
+ spin_unlock_irq(&mapping->tree_lock);
+ return -EAGAIN;
+ }
+
+ if (!page_freeze_refs(page, expected_count)) {
+ spin_unlock_irq(&mapping->tree_lock);
+ return -EAGAIN;
+ }
+
+ get_page(newpage);
+
+ radix_tree_replace_slot(pslot, newpage);
+
+ page_unfreeze_refs(page, expected_count);
+
+ __put_page(page);
+
+ spin_unlock_irq(&mapping->tree_lock);
+ return 0;
+}
+
+/*
* Copy the page to its new location
*/
-static void migrate_page_copy(struct page *newpage, struct page *page)
+void migrate_page_copy(struct page *newpage, struct page *page)
{
- copy_highpage(newpage, page);
+ if (PageHuge(page))
+ copy_huge_page(newpage, page);
+ else
+ copy_highpage(newpage, page);
if (PageError(page))
SetPageError(newpage);
.nr_to_write = 1,
.range_start = 0,
.range_end = LLONG_MAX,
- .nonblocking = 1,
.for_reclaim = 1
};
int rc;
* < 0 - error code
* == 0 - success
*/
-static int move_to_new_page(struct page *newpage, struct page *page)
+static int move_to_new_page(struct page *newpage, struct page *page,
+ int remap_swapcache)
{
struct address_space *mapping;
int rc;
else
rc = fallback_migrate_page(mapping, newpage, page);
- if (!rc)
- remove_migration_ptes(page, newpage);
- else
+ if (rc) {
newpage->mapping = NULL;
+ } else {
+ if (remap_swapcache)
+ remove_migration_ptes(page, newpage);
+ }
unlock_page(newpage);
* to the newly allocated page in newpage.
*/
static int unmap_and_move(new_page_t get_new_page, unsigned long private,
- struct page *page, int force, int offlining)
+ struct page *page, int force, bool offlining, bool sync)
{
int rc = 0;
int *result = NULL;
struct page *newpage = get_new_page(page, private, &result);
- int rcu_locked = 0;
+ int remap_swapcache = 1;
int charge = 0;
struct mem_cgroup *mem = NULL;
+ struct anon_vma *anon_vma = NULL;
if (!newpage)
return -ENOMEM;
/* page was freed from under us. So we are done. */
goto move_newpage;
}
+ if (unlikely(PageTransHuge(page)))
+ if (unlikely(split_huge_page(page)))
+ goto move_newpage;
/* prepare cgroup just returns 0 or -ENOMEM */
rc = -EAGAIN;
if (!trylock_page(page)) {
if (!force)
goto move_newpage;
+
+ /*
+ * It's not safe for direct compaction to call lock_page.
+ * For example, during page readahead pages are added locked
+ * to the LRU. Later, when the IO completes the pages are
+ * marked uptodate and unlocked. However, the queueing
+ * could be merging multiple pages for one bio (e.g.
+ * mpage_readpages). If an allocation happens for the
+ * second or third page, the process can end up locking
+ * the same page twice and deadlocking. Rather than
+ * trying to be clever about what pages can be locked,
+ * avoid the use of lock_page for direct compaction
+ * altogether.
+ */
+ if (current->flags & PF_MEMALLOC)
+ goto move_newpage;
+
lock_page(page);
}
}
/* charge against new page */
- charge = mem_cgroup_prepare_migration(page, &mem);
+ charge = mem_cgroup_prepare_migration(page, newpage, &mem);
if (charge == -ENOMEM) {
rc = -ENOMEM;
goto unlock;
BUG_ON(charge);
if (PageWriteback(page)) {
- if (!force)
+ if (!force || !sync)
goto uncharge;
wait_on_page_writeback(page);
}
/*
* By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
* we cannot notice that anon_vma is freed while we migrates a page.
- * This rcu_read_lock() delays freeing anon_vma pointer until the end
+ * This get_anon_vma() delays freeing anon_vma pointer until the end
* of migration. File cache pages are no problem because of page_lock()
* File Caches may use write_page() or lock_page() in migration, then,
* just care Anon page here.
*/
if (PageAnon(page)) {
- rcu_read_lock();
- rcu_locked = 1;
+ /*
+ * Only page_lock_anon_vma() understands the subtleties of
+ * getting a hold on an anon_vma from outside one of its mms.
+ */
+ anon_vma = page_lock_anon_vma(page);
+ if (anon_vma) {
+ /*
+ * Take a reference count on the anon_vma if the
+ * page is mapped so that it is guaranteed to
+ * exist when the page is remapped later
+ */
+ get_anon_vma(anon_vma);
+ page_unlock_anon_vma(anon_vma);
+ } else if (PageSwapCache(page)) {
+ /*
+ * We cannot be sure that the anon_vma of an unmapped
+ * swapcache page is safe to use because we don't
+ * know in advance if the VMA that this page belonged
+ * to still exists. If the VMA and others sharing the
+ * data have been freed, then the anon_vma could
+ * already be invalid.
+ *
+ * To avoid this possibility, swapcache pages get
+ * migrated but are not remapped when migration
+ * completes
+ */
+ remap_swapcache = 0;
+ } else {
+ goto uncharge;
+ }
}
/*
* free the metadata, so the page can be freed.
*/
if (!page->mapping) {
- if (!PageAnon(page) && page_has_private(page)) {
- /*
- * Go direct to try_to_free_buffers() here because
- * a) that's what try_to_release_page() would do anyway
- * b) we may be under rcu_read_lock() here, so we can't
- * use GFP_KERNEL which is what try_to_release_page()
- * needs to be effective.
- */
+ VM_BUG_ON(PageAnon(page));
+ if (page_has_private(page)) {
try_to_free_buffers(page);
- goto rcu_unlock;
+ goto uncharge;
}
goto skip_unmap;
}
skip_unmap:
if (!page_mapped(page))
- rc = move_to_new_page(newpage, page);
+ rc = move_to_new_page(newpage, page, remap_swapcache);
- if (rc)
+ if (rc && remap_swapcache)
remove_migration_ptes(page, page);
-rcu_unlock:
- if (rcu_locked)
- rcu_read_unlock();
+
+ /* Drop an anon_vma reference if we took one */
+ if (anon_vma)
+ drop_anon_vma(anon_vma);
+
uncharge:
if (!charge)
- mem_cgroup_end_migration(mem, page, newpage);
+ mem_cgroup_end_migration(mem, page, newpage, rc == 0);
unlock:
unlock_page(page);
+move_newpage:
if (rc != -EAGAIN) {
/*
* A page that has been migrated has all references
putback_lru_page(page);
}
-move_newpage:
-
/*
* Move the new page to the LRU. If migration was not successful
* then this will free the page.
}
/*
+ * Counterpart of unmap_and_move_page() for hugepage migration.
+ *
+ * This function doesn't wait the completion of hugepage I/O
+ * because there is no race between I/O and migration for hugepage.
+ * Note that currently hugepage I/O occurs only in direct I/O
+ * where no lock is held and PG_writeback is irrelevant,
+ * and writeback status of all subpages are counted in the reference
+ * count of the head page (i.e. if all subpages of a 2MB hugepage are
+ * under direct I/O, the reference of the head page is 512 and a bit more.)
+ * This means that when we try to migrate hugepage whose subpages are
+ * doing direct I/O, some references remain after try_to_unmap() and
+ * hugepage migration fails without data corruption.
+ *
+ * There is also no race when direct I/O is issued on the page under migration,
+ * because then pte is replaced with migration swap entry and direct I/O code
+ * will wait in the page fault for migration to complete.
+ */
+static int unmap_and_move_huge_page(new_page_t get_new_page,
+ unsigned long private, struct page *hpage,
+ int force, bool offlining, bool sync)
+{
+ int rc = 0;
+ int *result = NULL;
+ struct page *new_hpage = get_new_page(hpage, private, &result);
+ struct anon_vma *anon_vma = NULL;
+
+ if (!new_hpage)
+ return -ENOMEM;
+
+ rc = -EAGAIN;
+
+ if (!trylock_page(hpage)) {
+ if (!force || !sync)
+ goto out;
+ lock_page(hpage);
+ }
+
+ if (PageAnon(hpage)) {
+ anon_vma = page_lock_anon_vma(hpage);
+ if (anon_vma) {
+ get_anon_vma(anon_vma);
+ page_unlock_anon_vma(anon_vma);
+ }
+ }
+
+ try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
+
+ if (!page_mapped(hpage))
+ rc = move_to_new_page(new_hpage, hpage, 1);
+
+ if (rc)
+ remove_migration_ptes(hpage, hpage);
+
+ if (anon_vma)
+ drop_anon_vma(anon_vma);
+out:
+ unlock_page(hpage);
+
+ if (rc != -EAGAIN) {
+ list_del(&hpage->lru);
+ put_page(hpage);
+ }
+
+ put_page(new_hpage);
+
+ if (result) {
+ if (rc)
+ *result = rc;
+ else
+ *result = page_to_nid(new_hpage);
+ }
+ return rc;
+}
+
+/*
* migrate_pages
*
* The function takes one list of pages to migrate and a function
*
* The function returns after 10 attempts or if no pages
* are movable anymore because to has become empty
- * or no retryable pages exist anymore. All pages will be
- * returned to the LRU or freed.
+ * or no retryable pages exist anymore.
+ * Caller should call putback_lru_pages to return pages to the LRU
+ * or free list only if ret != 0.
*
* Return: Number of pages not migrated or error code.
*/
int migrate_pages(struct list_head *from,
- new_page_t get_new_page, unsigned long private, int offlining)
+ new_page_t get_new_page, unsigned long private, bool offlining,
+ bool sync)
{
int retry = 1;
int nr_failed = 0;
cond_resched();
rc = unmap_and_move(get_new_page, private,
- page, pass > 2, offlining);
+ page, pass > 2, offlining,
+ sync);
switch(rc) {
case -ENOMEM:
if (!swapwrite)
current->flags &= ~PF_SWAPWRITE;
- putback_lru_pages(from);
+ if (rc)
+ return rc;
+
+ return nr_failed + retry;
+}
+
+int migrate_huge_pages(struct list_head *from,
+ new_page_t get_new_page, unsigned long private, bool offlining,
+ bool sync)
+{
+ int retry = 1;
+ int nr_failed = 0;
+ int pass = 0;
+ struct page *page;
+ struct page *page2;
+ int rc;
+
+ for (pass = 0; pass < 10 && retry; pass++) {
+ retry = 0;
+ list_for_each_entry_safe(page, page2, from, lru) {
+ cond_resched();
+
+ rc = unmap_and_move_huge_page(get_new_page,
+ private, page, pass > 2, offlining,
+ sync);
+
+ switch(rc) {
+ case -ENOMEM:
+ goto out;
+ case -EAGAIN:
+ retry++;
+ break;
+ case 0:
+ break;
+ default:
+ /* Permanent failure */
+ nr_failed++;
+ break;
+ }
+ }
+ }
+ rc = 0;
+out:
if (rc)
return rc;
err = -EFAULT;
vma = find_vma(mm, pp->addr);
- if (!vma || !vma_migratable(vma))
+ if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma))
goto set_status;
- page = follow_page(vma, pp->addr, FOLL_GET);
+ page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT);
err = PTR_ERR(page);
if (IS_ERR(page))
}
err = 0;
- if (!list_empty(&pagelist))
+ if (!list_empty(&pagelist)) {
err = migrate_pages(&pagelist, new_page_node,
- (unsigned long)pm, 0);
+ (unsigned long)pm, 0, true);
+ if (err)
+ putback_lru_pages(&pagelist);
+ }
up_read(&mm->mmap_sem);
return err;
int err = -EFAULT;
vma = find_vma(mm, addr);
- if (!vma)
+ if (!vma || addr < vma->vm_start)
goto set_status;
page = follow_page(vma, addr, 0);
return -EPERM;
/* Find the mm_struct */
- read_lock(&tasklist_lock);
+ rcu_read_lock();
task = pid ? find_task_by_vpid(pid) : current;
if (!task) {
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return -ESRCH;
}
mm = get_task_mm(task);
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
if (!mm)
return -EINVAL;
projects / linux-flexiantxendom0-natty.git / blobdiff