diff options
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 92 |
1 files changed, 28 insertions, 64 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d06cae2de783..42882c1e7fce 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -268,31 +268,6 @@ static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg) return (memcg == root_mem_cgroup); } -/* - * We restrict the id in the range of [1, 65535], so it can fit into - * an unsigned short. - */ -#define MEM_CGROUP_ID_MAX USHRT_MAX - -static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg) -{ - return memcg->css.id; -} - -/* - * A helper function to get mem_cgroup from ID. must be called under - * rcu_read_lock(). The caller is responsible for calling - * css_tryget_online() if the mem_cgroup is used for charging. (dropping - * refcnt from swap can be called against removed memcg.) - */ -static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id) -{ - struct cgroup_subsys_state *css; - - css = css_from_id(id, &memory_cgrp_subsys); - return mem_cgroup_from_css(css); -} - #ifndef CONFIG_SLOB /* * This will be the memcg's index in each cache's ->memcg_params.memcg_caches. @@ -1709,19 +1684,13 @@ cleanup: } /** - * mem_cgroup_begin_page_stat - begin a page state statistics transaction - * @page: page that is going to change accounted state - * - * This function must mark the beginning of an accounted page state - * change to prevent double accounting when the page is concurrently - * being moved to another memcg: + * lock_page_memcg - lock a page->mem_cgroup binding + * @page: the page * - * memcg = mem_cgroup_begin_page_stat(page); - * if (TestClearPageState(page)) - * mem_cgroup_update_page_stat(memcg, state, -1); - * mem_cgroup_end_page_stat(memcg); + * This function protects unlocked LRU pages from being moved to + * another cgroup and stabilizes their page->mem_cgroup binding. */ -struct mem_cgroup *mem_cgroup_begin_page_stat(struct page *page) +void lock_page_memcg(struct page *page) { struct mem_cgroup *memcg; unsigned long flags; @@ -1730,25 +1699,18 @@ struct mem_cgroup *mem_cgroup_begin_page_stat(struct page *page) * The RCU lock is held throughout the transaction. The fast * path can get away without acquiring the memcg->move_lock * because page moving starts with an RCU grace period. - * - * The RCU lock also protects the memcg from being freed when - * the page state that is going to change is the only thing - * preventing the page from being uncharged. - * E.g. end-writeback clearing PageWriteback(), which allows - * migration to go ahead and uncharge the page before the - * account transaction might be complete. */ rcu_read_lock(); if (mem_cgroup_disabled()) - return NULL; + return; again: memcg = page->mem_cgroup; if (unlikely(!memcg)) - return NULL; + return; if (atomic_read(&memcg->moving_account) <= 0) - return memcg; + return; spin_lock_irqsave(&memcg->move_lock, flags); if (memcg != page->mem_cgroup) { @@ -1759,21 +1721,23 @@ again: /* * When charge migration first begins, we can have locked and * unlocked page stat updates happening concurrently. Track - * the task who has the lock for mem_cgroup_end_page_stat(). + * the task who has the lock for unlock_page_memcg(). */ memcg->move_lock_task = current; memcg->move_lock_flags = flags; - return memcg; + return; } -EXPORT_SYMBOL(mem_cgroup_begin_page_stat); +EXPORT_SYMBOL(lock_page_memcg); /** - * mem_cgroup_end_page_stat - finish a page state statistics transaction - * @memcg: the memcg that was accounted against + * unlock_page_memcg - unlock a page->mem_cgroup binding + * @page: the page */ -void mem_cgroup_end_page_stat(struct mem_cgroup *memcg) +void unlock_page_memcg(struct page *page) { + struct mem_cgroup *memcg = page->mem_cgroup; + if (memcg && memcg->move_lock_task == current) { unsigned long flags = memcg->move_lock_flags; @@ -1785,7 +1749,7 @@ void mem_cgroup_end_page_stat(struct mem_cgroup *memcg) rcu_read_unlock(); } -EXPORT_SYMBOL(mem_cgroup_end_page_stat); +EXPORT_SYMBOL(unlock_page_memcg); /* * size of first charge trial. "32" comes from vmscan.c's magic value. @@ -4488,7 +4452,7 @@ static int mem_cgroup_move_account(struct page *page, VM_BUG_ON(compound && !PageTransHuge(page)); /* - * Prevent mem_cgroup_replace_page() from looking at + * Prevent mem_cgroup_migrate() from looking at * page->mem_cgroup of its source page while we change it. */ ret = -EBUSY; @@ -4923,9 +4887,9 @@ static void mem_cgroup_move_charge(struct mm_struct *mm) lru_add_drain_all(); /* - * Signal mem_cgroup_begin_page_stat() to take the memcg's - * move_lock while we're moving its pages to another memcg. - * Then wait for already started RCU-only updates to finish. + * Signal lock_page_memcg() to take the memcg's move_lock + * while we're moving its pages to another memcg. Then wait + * for already started RCU-only updates to finish. */ atomic_inc(&mc.from->moving_account); synchronize_rcu(); @@ -5517,16 +5481,16 @@ void mem_cgroup_uncharge_list(struct list_head *page_list) } /** - * mem_cgroup_replace_page - migrate a charge to another page - * @oldpage: currently charged page - * @newpage: page to transfer the charge to + * mem_cgroup_migrate - charge a page's replacement + * @oldpage: currently circulating page + * @newpage: replacement page * - * Migrate the charge from @oldpage to @newpage. + * Charge @newpage as a replacement page for @oldpage. @oldpage will + * be uncharged upon free. * * Both pages must be locked, @newpage->mapping must be set up. - * Either or both pages might be on the LRU already. */ -void mem_cgroup_replace_page(struct page *oldpage, struct page *newpage) +void mem_cgroup_migrate(struct page *oldpage, struct page *newpage) { struct mem_cgroup *memcg; unsigned int nr_pages; @@ -5559,7 +5523,7 @@ void mem_cgroup_replace_page(struct page *oldpage, struct page *newpage) page_counter_charge(&memcg->memsw, nr_pages); css_get_many(&memcg->css, nr_pages); - commit_charge(newpage, memcg, true); + commit_charge(newpage, memcg, false); local_irq_disable(); mem_cgroup_charge_statistics(memcg, newpage, compound, nr_pages); |