* collapse_shmem - collapse small tmpfs/shmem pages into huge one.
*
* Basic scheme is simple, details are more complex:
- * - allocate and freeze a new huge page;
+ * - allocate and lock a new huge page;
* - scan over radix tree replacing old pages the new one
* + swap in pages if necessary;
* + fill in gaps;
* - if replacing succeed:
* + copy data over;
* + free old pages;
- * + unfreeze huge page;
+ * + unlock huge page;
* - if replacing failed;
* + put all pages back and unfreeze them;
* + restore gaps in the radix-tree;
- * + free huge page;
+ * + unlock and free huge page;
*/
static void collapse_shmem(struct mm_struct *mm,
struct address_space *mapping, pgoff_t start,
__SetPageSwapBacked(new_page);
new_page->index = start;
new_page->mapping = mapping;
- BUG_ON(!page_ref_freeze(new_page, 1));
/*
- * At this point the new_page is 'frozen' (page_count() is zero), locked
- * and not up-to-date. It's safe to insert it into radix tree, because
- * nobody would be able to map it or use it in other way until we
- * unfreeze it.
+ * At this point the new_page is locked and not up-to-date.
+ * It's safe to insert it into the page cache, because nobody would
+ * be able to map it or use it in another way until we unlock it.
*/
index = start;
index++;
}
- /* Everything is ready, let's unfreeze the new_page */
SetPageUptodate(new_page);
- page_ref_unfreeze(new_page, HPAGE_PMD_NR);
+ page_ref_add(new_page, HPAGE_PMD_NR - 1);
set_page_dirty(new_page);
mem_cgroup_commit_charge(new_page, memcg, false, true);
lru_cache_add_anon(new_page);
VM_BUG_ON(nr_none);
spin_unlock_irq(&mapping->tree_lock);
- /* Unfreeze new_page, caller would take care about freeing it */
- page_ref_unfreeze(new_page, 1);
mem_cgroup_cancel_charge(new_page, memcg, true);
new_page->mapping = NULL;
}