This patch adds follwoing functions. - clear_page_cgroup(page, pc) - page_cgroup_assign_new_page_group(page, pc) Mainly for cleaunp. A manner "check page->cgroup again after lock_page_cgroup()" is implemented in straight way. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> mm/memcontrol.c | 76 ++++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 49 insertions(+), 27 deletions(-) Index: devel-2.6.23-rc8-mm2/mm/memcontrol.c =================================================================== --- devel-2.6.23-rc8-mm2.orig/mm/memcontrol.c +++ devel-2.6.23-rc8-mm2/mm/memcontrol.c @@ -162,6 +162,35 @@ static void __always_inline unlock_page_ bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup); } +static inline int +page_cgroup_assign_new_page_cgroup(struct page *page, struct page_cgroup *pc) +{ + int ret = 0; + + lock_page_cgroup(page); + if (!page_get_page_cgroup(page)) + page_assign_page_cgroup(page, pc); + else + ret = 1; + unlock_page_cgroup(page); + return ret; +} + + +static inline struct page_cgroup * +clear_page_cgroup(struct page *page, struct page_cgroup *pc) +{ + struct page_cgroup *ret; + /* lock and clear */ + lock_page_cgroup(page); + ret = page_get_page_cgroup(page); + if (likely(ret == pc)) + page_assign_page_cgroup(page, NULL); + unlock_page_cgroup(page); + return ret; +} + + static void __mem_cgroup_move_lists(struct page_cgroup *pc, bool active) { if (active) @@ -260,7 +289,7 @@ int mem_cgroup_charge(struct page *page, gfp_t gfp_mask) { struct mem_cgroup *mem; - struct page_cgroup *pc, *race_pc; + struct page_cgroup *pc; unsigned long flags; unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES; @@ -353,24 +382,16 @@ noreclaim: goto free_pc; } - lock_page_cgroup(page); - /* - * Check if somebody else beat us to allocating the page_cgroup - */ - race_pc = page_get_page_cgroup(page); - if (race_pc) { - kfree(pc); - pc = race_pc; - atomic_inc(&pc->ref_cnt); - res_counter_uncharge(&mem->res, PAGE_SIZE); - css_put(&mem->css); - goto done; - } - atomic_set(&pc->ref_cnt, 1); pc->mem_cgroup = mem; pc->page = page; - page_assign_page_cgroup(page, pc); + if (page_cgroup_assign_new_page_cgroup(page, pc)) { + /* race ... undo and retry */ + res_counter_uncharge(&mem->res, PAGE_SIZE); + css_put(&mem->css); + kfree(pc); + goto retry; + } spin_lock_irqsave(&mem->lru_lock, flags); list_add(&pc->lru, &mem->active_list); @@ -421,17 +442,18 @@ void mem_cgroup_uncharge(struct page_cgr if (atomic_dec_and_test(&pc->ref_cnt)) { page = pc->page; - lock_page_cgroup(page); - mem = pc->mem_cgroup; - css_put(&mem->css); - page_assign_page_cgroup(page, NULL); - unlock_page_cgroup(page); - res_counter_uncharge(&mem->res, PAGE_SIZE); - - spin_lock_irqsave(&mem->lru_lock, flags); - list_del_init(&pc->lru); - spin_unlock_irqrestore(&mem->lru_lock, flags); - kfree(pc); + /* + * Obetaion page->cgroup and clear it under lock. + */ + if (clear_page_cgroup(page, pc) == pc) { + mem = pc->mem_cgroup; + css_put(&mem->css); + res_counter_uncharge(&mem->res, PAGE_SIZE); + spin_lock_irqsave(&mem->lru_lock, flags); + list_del_init(&pc->lru); + spin_unlock_irqrestore(&mem->lru_lock, flags); + kfree(pc); + } } } _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers