#include <linux/vmalloc.h>
#include <linux/security.h>
#include <linux/memcontrol.h>
+#include <linux/syscalls.h>
#include "internal.h"
page = migration_entry_to_page(entry);
- get_page(page);
+ /*
+ * Once radix-tree replacement of page migration started, page_count
+ * *must* be zero. And, we don't want to call wait_on_page_locked()
+ * against a page without get_page().
+ * So, we use get_page_unless_zero(), here. Even failed, page fault
+ * will occur again.
+ */
+ if (!get_page_unless_zero(page))
+ goto out;
pte_unmap_unlock(ptep, ptl);
wait_on_page_locked(page);
put_page(page);
static int migrate_page_move_mapping(struct address_space *mapping,
struct page *newpage, struct page *page)
{
+ int expected_count;
void **pslot;
if (!mapping) {
return 0;
}
- write_lock_irq(&mapping->tree_lock);
+ spin_lock_irq(&mapping->tree_lock);
pslot = radix_tree_lookup_slot(&mapping->page_tree,
page_index(page));
- if (page_count(page) != 2 + !!PagePrivate(page) ||
+ expected_count = 2 + !!PagePrivate(page);
+ if (page_count(page) != expected_count ||
(struct page *)radix_tree_deref_slot(pslot) != page) {
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);
+ return -EAGAIN;
+ }
+
+ if (!page_freeze_refs(page, expected_count)) {
+ spin_unlock_irq(&mapping->tree_lock);
return -EAGAIN;
}
radix_tree_replace_slot(pslot, newpage);
+ page_unfreeze_refs(page, expected_count);
/*
* Drop cache reference from old page.
* We know this isn't the last reference.
__dec_zone_page_state(page, NR_FILE_PAGES);
__inc_zone_page_state(newpage, NR_FILE_PAGES);
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);
+ if (!PageSwapCache(newpage))
+ mem_cgroup_uncharge_cache_page(page);
return 0;
}
rc = fallback_migrate_page(mapping, newpage, page);
if (!rc) {
- mem_cgroup_page_migration(page, newpage);
remove_migration_ptes(page, newpage);
} else
newpage->mapping = NULL;
/* page was freed from under us. So we are done. */
goto move_newpage;
+ charge = mem_cgroup_prepare_migration(page, newpage);
+ if (charge == -ENOMEM) {
+ rc = -ENOMEM;
+ goto move_newpage;
+ }
+ /* prepare cgroup just returns 0 or -ENOMEM */
+ BUG_ON(charge);
+
rc = -EAGAIN;
if (TestSetPageLocked(page)) {
if (!force)
goto rcu_unlock;
}
- charge = mem_cgroup_prepare_migration(page);
/* Establish migration ptes or remove ptes */
try_to_unmap(page, 1);
if (!page_mapped(page))
rc = move_to_new_page(newpage, page);
- if (rc) {
+ if (rc)
remove_migration_ptes(page, page);
- if (charge)
- mem_cgroup_end_migration(page);
- } else if (charge)
- mem_cgroup_end_migration(newpage);
rcu_unlock:
if (rcu_locked)
rcu_read_unlock();
}
move_newpage:
+ if (!charge)
+ mem_cgroup_end_migration(newpage);
/*
* Move the new page to the LRU. If migration was not successful
* then this will free the page.
mmput(mm);
return err;
}
-#endif
/*
* Call migration functions in the vma_ops that may prepare
}
return err;
}
+#endif