diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memcontrol.c | 74 | ||||
| -rw-r--r-- | mm/page_cgroup.c | 32 |
2 files changed, 76 insertions, 30 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 81b0ae8183d..55dea596846 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -991,10 +991,31 @@ nomem: return -ENOMEM; } + +/* + * A helper function to get mem_cgroup from ID. must be called under + * rcu_read_lock(). The caller must check css_is_removed() or some if + * it's concern. (dropping refcnt from swap can be called against removed + * memcg.) + */ +static struct mem_cgroup *mem_cgroup_lookup(unsigned short id) +{ + struct cgroup_subsys_state *css; + + /* ID 0 is unused ID */ + if (!id) + return NULL; + css = css_lookup(&mem_cgroup_subsys, id); + if (!css) + return NULL; + return container_of(css, struct mem_cgroup, css); +} + static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page) { struct mem_cgroup *mem; struct page_cgroup *pc; + unsigned short id; swp_entry_t ent; VM_BUG_ON(!PageLocked(page)); @@ -1006,16 +1027,19 @@ static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page) /* * Used bit of swapcache is solid under page lock. */ - if (PageCgroupUsed(pc)) + if (PageCgroupUsed(pc)) { mem = pc->mem_cgroup; - else { + if (mem && !css_tryget(&mem->css)) + mem = NULL; + } else { ent.val = page_private(page); - mem = lookup_swap_cgroup(ent); + id = lookup_swap_cgroup(ent); + rcu_read_lock(); + mem = mem_cgroup_lookup(id); + if (mem && !css_tryget(&mem->css)) + mem = NULL; + rcu_read_unlock(); } - if (!mem) - return NULL; - if (!css_tryget(&mem->css)) - return NULL; return mem; } @@ -1276,12 +1300,22 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm, if (do_swap_account && !ret && PageSwapCache(page)) { swp_entry_t ent = {.val = page_private(page)}; + unsigned short id; /* avoid double counting */ - mem = swap_cgroup_record(ent, NULL); + id = swap_cgroup_record(ent, 0); + rcu_read_lock(); + mem = mem_cgroup_lookup(id); if (mem) { + /* + * We did swap-in. Then, this entry is doubly counted + * both in mem and memsw. We uncharge it, here. + * Recorded ID can be obsolete. We avoid calling + * css_tryget() + */ res_counter_uncharge(&mem->memsw, PAGE_SIZE); mem_cgroup_put(mem); } + rcu_read_unlock(); } return ret; } @@ -1346,13 +1380,21 @@ void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr) */ if (do_swap_account && PageSwapCache(page)) { swp_entry_t ent = {.val = page_private(page)}; + unsigned short id; struct mem_cgroup *memcg; - memcg = swap_cgroup_record(ent, NULL); + + id = swap_cgroup_record(ent, 0); + rcu_read_lock(); + memcg = mem_cgroup_lookup(id); if (memcg) { + /* + * This recorded memcg can be obsolete one. So, avoid + * calling css_tryget + */ res_counter_uncharge(&memcg->memsw, PAGE_SIZE); mem_cgroup_put(memcg); } - + rcu_read_unlock(); } /* add this page(page_cgroup) to the LRU we want. */ @@ -1473,7 +1515,7 @@ void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent) MEM_CGROUP_CHARGE_TYPE_SWAPOUT); /* record memcg information */ if (do_swap_account && memcg) { - swap_cgroup_record(ent, memcg); + swap_cgroup_record(ent, css_id(&memcg->css)); mem_cgroup_get(memcg); } if (memcg) @@ -1488,15 +1530,23 @@ void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent) void mem_cgroup_uncharge_swap(swp_entry_t ent) { struct mem_cgroup *memcg; + unsigned short id; if (!do_swap_account) return; - memcg = swap_cgroup_record(ent, NULL); + id = swap_cgroup_record(ent, 0); + rcu_read_lock(); + memcg = mem_cgroup_lookup(id); if (memcg) { + /* + * We uncharge this because swap is freed. + * This memcg can be obsolete one. We avoid calling css_tryget + */ res_counter_uncharge(&memcg->memsw, PAGE_SIZE); mem_cgroup_put(memcg); } + rcu_read_unlock(); } #endif diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c index ceecfbb143f..ebf81074bed 100644 --- a/mm/page_cgroup.c +++ b/mm/page_cgroup.c @@ -285,12 +285,8 @@ struct swap_cgroup_ctrl { struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES]; -/* - * This 8bytes seems big..maybe we can reduce this when we can use "id" for - * cgroup rather than pointer. - */ struct swap_cgroup { - struct mem_cgroup *val; + unsigned short id; }; #define SC_PER_PAGE (PAGE_SIZE/sizeof(struct swap_cgroup)) #define SC_POS_MASK (SC_PER_PAGE - 1) @@ -342,10 +338,10 @@ not_enough_page: * @ent: swap entry to be recorded into * @mem: mem_cgroup to be recorded * - * Returns old value at success, NULL at failure. - * (Of course, old value can be NULL.) + * Returns old value at success, 0 at failure. + * (Of course, old value can be 0.) */ -struct mem_cgroup *swap_cgroup_record(swp_entry_t ent, struct mem_cgroup *mem) +unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id) { int type = swp_type(ent); unsigned long offset = swp_offset(ent); @@ -354,18 +350,18 @@ struct mem_cgroup *swap_cgroup_record(swp_entry_t ent, struct mem_cgroup *mem) struct swap_cgroup_ctrl *ctrl; struct page *mappage; struct swap_cgroup *sc; - struct mem_cgroup *old; + unsigned short old; if (!do_swap_account) - return NULL; + return 0; ctrl = &swap_cgroup_ctrl[type]; mappage = ctrl->map[idx]; sc = page_address(mappage); sc += pos; - old = sc->val; - sc->val = mem; + old = sc->id; + sc->id = id; return old; } @@ -374,9 +370,9 @@ struct mem_cgroup *swap_cgroup_record(swp_entry_t ent, struct mem_cgroup *mem) * lookup_swap_cgroup - lookup mem_cgroup tied to swap entry * @ent: swap entry to be looked up. * - * Returns pointer to mem_cgroup at success. NULL at failure. + * Returns CSS ID of mem_cgroup at success. 0 at failure. (0 is invalid ID) */ -struct mem_cgroup *lookup_swap_cgroup(swp_entry_t ent) +unsigned short lookup_swap_cgroup(swp_entry_t ent) { int type = swp_type(ent); unsigned long offset = swp_offset(ent); @@ -385,16 +381,16 @@ struct mem_cgroup *lookup_swap_cgroup(swp_entry_t ent) struct swap_cgroup_ctrl *ctrl; struct page *mappage; struct swap_cgroup *sc; - struct mem_cgroup *ret; + unsigned short ret; if (!do_swap_account) - return NULL; + return 0; ctrl = &swap_cgroup_ctrl[type]; mappage = ctrl->map[idx]; sc = page_address(mappage); sc += pos; - ret = sc->val; + ret = sc->id; return ret; } @@ -432,7 +428,7 @@ int swap_cgroup_swapon(int type, unsigned long max_pages) printk(KERN_INFO "swap_cgroup: uses %ld bytes of vmalloc for pointer array space" - " and %ld bytes to hold mem_cgroup pointers on swap\n", + " and %ld bytes to hold mem_cgroup information per swap ents\n", array_size, length * PAGE_SIZE); printk(KERN_INFO "swap_cgroup can be disabled by noswapaccount boot option.\n"); |