memory cgroup enhancements: force_empty interface for dropping all account in empty cgroup (cc847582) · Commits · 戴 / test

mm/memcontrol.c

+103 −7

Original line number	Diff line number	Diff line
		@@ -471,6 +471,7 @@ void mem_cgroup_uncharge(struct page_cgroup *pc)
		page = pc->page;
		/*
		* get page->cgroup and clear it under lock.
		* force_empty can drop page->cgroup without checking refcnt.
		*/
		if (clear_page_cgroup(page, pc) == pc) {
		mem = pc->mem_cgroup;
		@@ -480,13 +481,6 @@ void mem_cgroup_uncharge(struct page_cgroup *pc)
		list_del_init(&pc->lru);
		spin_unlock_irqrestore(&mem->lru_lock, flags);
		kfree(pc);
		} else {
		/*
		* Note:This will be removed when force-empty patch is
		* applied. just show warning here.
		*/
		printk(KERN_ERR "Race in mem_cgroup_uncharge() ?");
		dump_stack();
		}
		}
		}
		@@ -534,6 +528,76 @@ retry:
		return;
		}

		/*
		* This routine traverse page_cgroup in given list and drop them all.
		* This routine ignores page_cgroup->ref_cnt.
		* And this routine doesn't reclaim page itself, just removes page_cgroup.
		*/
		#define FORCE_UNCHARGE_BATCH (128)
		static void
		mem_cgroup_force_empty_list(struct mem_cgroup mem, struct list_head list)
		{
		struct page_cgroup *pc;
		struct page *page;
		int count;
		unsigned long flags;

		retry:
		count = FORCE_UNCHARGE_BATCH;
		spin_lock_irqsave(&mem->lru_lock, flags);

		while (--count && !list_empty(list)) {
		pc = list_entry(list->prev, struct page_cgroup, lru);
		page = pc->page;
		/* Avoid race with charge */
		atomic_set(&pc->ref_cnt, 0);
		if (clear_page_cgroup(page, pc) == pc) {
		css_put(&mem->css);
		res_counter_uncharge(&mem->res, PAGE_SIZE);
		list_del_init(&pc->lru);
		kfree(pc);
		} else /* being uncharged ? ...do relax */
		break;
		}
		spin_unlock_irqrestore(&mem->lru_lock, flags);
		if (!list_empty(list)) {
		cond_resched();
		goto retry;
		}
		return;
		}

		/*
		* make mem_cgroup's charge to be 0 if there is no task.
		* This enables deleting this mem_cgroup.
		*/

		int mem_cgroup_force_empty(struct mem_cgroup *mem)
		{
		int ret = -EBUSY;
		css_get(&mem->css);
		/*
		* page reclaim code (kswapd etc..) will move pages between
		` * active_list <-> inactive_list while we don't take a lock.
		* So, we have to do loop here until all lists are empty.
		*/
		while (!(list_empty(&mem->active_list) &&
		list_empty(&mem->inactive_list))) {
		if (atomic_read(&mem->css.cgroup->count) > 0)
		goto out;
		/* drop all page_cgroup in active_list */
		mem_cgroup_force_empty_list(mem, &mem->active_list);
		/* drop all page_cgroup in inactive_list */
		mem_cgroup_force_empty_list(mem, &mem->inactive_list);
		}
		ret = 0;
		out:
		css_put(&mem->css);
		return ret;
		}



		int mem_cgroup_write_strategy(char buf, unsigned long long tmp)
		{
		*tmp = memparse(buf, &buf);
		@@ -619,6 +683,33 @@ static ssize_t mem_control_type_read(struct cgroup *cont,
		ppos, buf, s - buf);
		}


		static ssize_t mem_force_empty_write(struct cgroup *cont,
		struct cftype cft, struct file file,
		const char __user *userbuf,
		size_t nbytes, loff_t *ppos)
		{
		struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
		int ret;
		ret = mem_cgroup_force_empty(mem);
		if (!ret)
		ret = nbytes;
		return ret;
		}

		/*
		* Note: This should be removed if cgroup supports write-only file.
		*/

		static ssize_t mem_force_empty_read(struct cgroup *cont,
		struct cftype *cft,
		struct file file, char __user userbuf,
		size_t nbytes, loff_t *ppos)
		{
		return -EINVAL;
		}


		static struct cftype mem_cgroup_files[] = {
		{
		.name = "usage_in_bytes",
		@@ -641,6 +732,11 @@ static struct cftype mem_cgroup_files[] = {
		.write = mem_control_type_write,
		.read = mem_control_type_read,
		},
		{
		.name = "force_empty",
		.write = mem_force_empty_write,
		.read = mem_force_empty_read,
		},
		};

		static struct mem_cgroup init_mem_cgroup;

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