+ if (mem_cgroup_disabled())
+ return 0;
+ if (PageCompound(page))
+ return 0;
+ /*
+ * Corner case handling. This is called from add_to_page_cache()
+ * in usual. But some FS (shmem) precharges this page before calling it
+ * and call add_to_page_cache() with GFP_NOWAIT.
+ *
+ * For GFP_NOWAIT case, the page may be pre-charged before calling
+ * add_to_page_cache(). (See shmem.c) check it here and avoid to call
+ * charge twice. (It works but has to pay a bit larger cost.)
+ * And when the page is SwapCache, it should take swap information
+ * into account. This is under lock_page() now.
+ */
+ if (!(gfp_mask & __GFP_WAIT)) {
+ struct page_cgroup *pc;
+
+
+ pc = lookup_page_cgroup(page);
+ if (!pc)
+ return 0;
+ lock_page_cgroup(pc);
+ if (PageCgroupUsed(pc)) {
+ unlock_page_cgroup(pc);
+ return 0;
+ }
+ unlock_page_cgroup(pc);
+ }
+
+ if (do_swap_account && PageSwapCache(page)) {
+ mem = try_get_mem_cgroup_from_swapcache(page);
+ if (mem)
+ mm = NULL;
+ else
+ mem = NULL;
+ /* SwapCache may be still linked to LRU now. */
+ mem_cgroup_lru_del_before_commit_swapcache(page);
+ }
+
+ if (unlikely(!mm && !mem))
+ mm = &init_mm;
+
+ if (page_is_file_cache(page))
+ return mem_cgroup_charge_common(page, mm, gfp_mask,
+ MEM_CGROUP_CHARGE_TYPE_CACHE, NULL);
+
+ ret = mem_cgroup_charge_common(page, mm, gfp_mask,
+ MEM_CGROUP_CHARGE_TYPE_SHMEM, mem);
+ if (mem)
+ css_put(&mem->css);
+ if (PageSwapCache(page))
+ mem_cgroup_lru_add_after_commit_swapcache(page);
+
+ if (do_swap_account && !ret && PageSwapCache(page)) {
+ swp_entry_t ent = {.val = page_private(page)};
+ /* avoid double counting */
+ mem = swap_cgroup_record(ent, NULL);
+ if (mem) {
+ res_counter_uncharge(&mem->memsw, PAGE_SIZE);
+ mem_cgroup_put(mem);
+ }
+ }
+ return ret;
+}
+
+/*
+ * While swap-in, try_charge -> commit or cancel, the page is locked.
+ * And when try_charge() successfully returns, one refcnt to memcg without
+ * struct page_cgroup is aquired. This refcnt will be cumsumed by
+ * "commit()" or removed by "cancel()"
+ */
+int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
+ struct page *page,
+ gfp_t mask, struct mem_cgroup **ptr)
+{
+ struct mem_cgroup *mem;
+ int ret;
+
+ if (mem_cgroup_disabled())
+ return 0;
+
+ if (!do_swap_account)
+ goto charge_cur_mm;
+ /*
+ * A racing thread's fault, or swapoff, may have already updated
+ * the pte, and even removed page from swap cache: return success
+ * to go on to do_swap_page()'s pte_same() test, which should fail.
+ */
+ if (!PageSwapCache(page))
+ return 0;
+ mem = try_get_mem_cgroup_from_swapcache(page);
+ if (!mem)
+ goto charge_cur_mm;
+ *ptr = mem;
+ ret = __mem_cgroup_try_charge(NULL, mask, ptr, true);
+ /* drop extra refcnt from tryget */
+ css_put(&mem->css);
+ return ret;
+charge_cur_mm:
+ if (unlikely(!mm))
+ mm = &init_mm;
+ return __mem_cgroup_try_charge(mm, mask, ptr, true);
+}
+
+void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
+{
+ struct page_cgroup *pc;
+
+ if (mem_cgroup_disabled())
+ return;
+ if (!ptr)
+ return;
+ pc = lookup_page_cgroup(page);
+ mem_cgroup_lru_del_before_commit_swapcache(page);
+ __mem_cgroup_commit_charge(ptr, pc, MEM_CGROUP_CHARGE_TYPE_MAPPED);
+ mem_cgroup_lru_add_after_commit_swapcache(page);
+ /*
+ * Now swap is on-memory. This means this page may be
+ * counted both as mem and swap....double count.
+ * Fix it by uncharging from memsw. Basically, this SwapCache is stable
+ * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
+ * may call delete_from_swap_cache() before reach here.
+ */
+ if (do_swap_account && PageSwapCache(page)) {
+ swp_entry_t ent = {.val = page_private(page)};
+ struct mem_cgroup *memcg;
+ memcg = swap_cgroup_record(ent, NULL);
+ if (memcg) {
+ res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
+ mem_cgroup_put(memcg);
+ }
+
+ }
+ /* add this page(page_cgroup) to the LRU we want. */
+
+}
+
+void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
+{
+ if (mem_cgroup_disabled())
+ return;
+ if (!mem)
+ return;
+ res_counter_uncharge(&mem->res, PAGE_SIZE);
+ if (do_swap_account)
+ res_counter_uncharge(&mem->memsw, PAGE_SIZE);
+ css_put(&mem->css);
+}
+
+
+/*
+ * uncharge if !page_mapped(page)
+ */
+static struct mem_cgroup *
+__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
+{
+ struct page_cgroup *pc;
+ struct mem_cgroup *mem = NULL;
+ struct mem_cgroup_per_zone *mz;
+
+ if (mem_cgroup_disabled())
+ return NULL;
+
+ if (PageSwapCache(page))
+ return NULL;
+
+ /*
+ * Check if our page_cgroup is valid
+ */
+ pc = lookup_page_cgroup(page);
+ if (unlikely(!pc || !PageCgroupUsed(pc)))
+ return NULL;
+
+ lock_page_cgroup(pc);
+
+ mem = pc->mem_cgroup;
+
+ if (!PageCgroupUsed(pc))
+ goto unlock_out;
+
+ switch (ctype) {
+ case MEM_CGROUP_CHARGE_TYPE_MAPPED:
+ if (page_mapped(page))
+ goto unlock_out;
+ break;
+ case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
+ if (!PageAnon(page)) { /* Shared memory */
+ if (page->mapping && !page_is_file_cache(page))
+ goto unlock_out;
+ } else if (page_mapped(page)) /* Anon */
+ goto unlock_out;
+ break;
+ default:
+ break;
+ }
+
+ res_counter_uncharge(&mem->res, PAGE_SIZE);
+ if (do_swap_account && (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT))
+ res_counter_uncharge(&mem->memsw, PAGE_SIZE);
+
+ mem_cgroup_charge_statistics(mem, pc, false);
+ ClearPageCgroupUsed(pc);
+ /*
+ * pc->mem_cgroup is not cleared here. It will be accessed when it's
+ * freed from LRU. This is safe because uncharged page is expected not
+ * to be reused (freed soon). Exception is SwapCache, it's handled by
+ * special functions.
+ */
+
+ mz = page_cgroup_zoneinfo(pc);
+ unlock_page_cgroup(pc);
+
+ /* at swapout, this memcg will be accessed to record to swap */
+ if (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
+ css_put(&mem->css);
+
+ return mem;
+
+unlock_out:
+ unlock_page_cgroup(pc);
+ return NULL;
+}
+
+void mem_cgroup_uncharge_page(struct page *page)
+{
+ /* early check. */
+ if (page_mapped(page))