diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/filemap.c | 70 | ||||
| -rw-r--r-- | mm/memcontrol.c | 4 | ||||
| -rw-r--r-- | mm/migrate.c | 2 |
3 files changed, 73 insertions, 3 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index 312b6eb78430..c1459f2cdb5e 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -387,6 +387,76 @@ int filemap_write_and_wait_range(struct address_space *mapping, EXPORT_SYMBOL(filemap_write_and_wait_range); /** + * replace_page_cache_page - replace a pagecache page with a new one + * @old: page to be replaced + * @new: page to replace with + * @gfp_mask: allocation mode + * + * This function replaces a page in the pagecache with a new one. On + * success it acquires the pagecache reference for the new page and + * drops it for the old page. Both the old and new pages must be + * locked. This function does not add the new page to the LRU, the + * caller must do that. + * + * The remove + add is atomic. The only way this function can fail is + * memory allocation failure. + */ +int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask) +{ + int error; + struct mem_cgroup *memcg = NULL; + + VM_BUG_ON(!PageLocked(old)); + VM_BUG_ON(!PageLocked(new)); + VM_BUG_ON(new->mapping); + + /* + * This is not page migration, but prepare_migration and + * end_migration does enough work for charge replacement. + * + * In the longer term we probably want a specialized function + * for moving the charge from old to new in a more efficient + * manner. + */ + error = mem_cgroup_prepare_migration(old, new, &memcg, gfp_mask); + if (error) + return error; + + error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); + if (!error) { + struct address_space *mapping = old->mapping; + void (*freepage)(struct page *); + + pgoff_t offset = old->index; + freepage = mapping->a_ops->freepage; + + page_cache_get(new); + new->mapping = mapping; + new->index = offset; + + spin_lock_irq(&mapping->tree_lock); + __remove_from_page_cache(old); + error = radix_tree_insert(&mapping->page_tree, offset, new); + BUG_ON(error); + mapping->nrpages++; + __inc_zone_page_state(new, NR_FILE_PAGES); + if (PageSwapBacked(new)) + __inc_zone_page_state(new, NR_SHMEM); + spin_unlock_irq(&mapping->tree_lock); + radix_tree_preload_end(); + if (freepage) + freepage(old); + page_cache_release(old); + mem_cgroup_end_migration(memcg, old, new, true); + } else { + mem_cgroup_end_migration(memcg, old, new, false); + } + + return error; +} +EXPORT_SYMBOL_GPL(replace_page_cache_page); + +/** * add_to_page_cache_locked - add a locked page to the pagecache * @page: page to add * @mapping: the page's address_space diff --git a/mm/memcontrol.c b/mm/memcontrol.c index da53a252b259..6ef5c53dffcb 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2883,7 +2883,7 @@ static inline int mem_cgroup_move_swap_account(swp_entry_t entry, * page belongs to. */ int mem_cgroup_prepare_migration(struct page *page, - struct page *newpage, struct mem_cgroup **ptr) + struct page *newpage, struct mem_cgroup **ptr, gfp_t gfp_mask) { struct page_cgroup *pc; struct mem_cgroup *mem = NULL; @@ -2940,7 +2940,7 @@ int mem_cgroup_prepare_migration(struct page *page, return 0; *ptr = mem; - ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, ptr, false, PAGE_SIZE); + ret = __mem_cgroup_try_charge(NULL, gfp_mask, ptr, false, PAGE_SIZE); css_put(&mem->css);/* drop extra refcnt */ if (ret || *ptr == NULL) { if (PageAnon(page)) { diff --git a/mm/migrate.c b/mm/migrate.c index 352de555626c..8aacce3af8cd 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -678,7 +678,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, } /* charge against new page */ - charge = mem_cgroup_prepare_migration(page, newpage, &mem); + charge = mem_cgroup_prepare_migration(page, newpage, &mem, GFP_KERNEL); if (charge == -ENOMEM) { rc = -ENOMEM; goto unlock; |