From b24028572fb69e9dd6de8c359eba2b2c66baa889 Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Wed, 21 Mar 2012 16:34:22 -0700 Subject: [PATCH] memcg: remove PCG_CACHE page_cgroup flag We record 'the page is cache' with the PCG_CACHE bit in page_cgroup. Here, "CACHE" means anonymous user pages (and SwapCache). This doesn't include shmem. Considering callers, at charge/uncharge, the caller should know what the page is and we don't need to record it by using one bit per page. This patch removes PCG_CACHE bit and make callers of mem_cgroup_charge_statistics() to specify what the page is. About page migration: Mapping of the used page is not touched during migra tion (see page_remove_rmap) so we can rely on it and push the correct charge type down to __mem_cgroup_uncharge_common from end_migration for unused page. The force flag was misleading was abused for skipping the needless page_mapped() / PageCgroupMigration() check, as we know the unused page is no longer mapped and cleared the migration flag just a few lines up. But doing the checks is no biggie and it's not worth adding another flag just to skip them. [akpm@linux-foundation.org: checkpatch fixes] [hughd@google.com: fix PageAnon uncharging] Signed-off-by: KAMEZAWA Hiroyuki Acked-by: Michal Hocko Acked-by: Johannes Weiner Cc: Hugh Dickins Cc: Ying Han Acked-by: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/page_cgroup.h | 8 +----- mm/memcontrol.c | 57 +++++++++++++++++++++---------------- 2 files changed, 33 insertions(+), 32 deletions(-) diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h index a2d11771c84..106029243ff 100644 --- a/include/linux/page_cgroup.h +++ b/include/linux/page_cgroup.h @@ -4,7 +4,6 @@ enum { /* flags for mem_cgroup */ PCG_LOCK, /* Lock for pc->mem_cgroup and following bits. */ - PCG_CACHE, /* charged as cache */ PCG_USED, /* this object is in use. */ PCG_MIGRATION, /* under page migration */ /* flags for mem_cgroup and file and I/O status */ @@ -64,11 +63,6 @@ static inline void ClearPageCgroup##uname(struct page_cgroup *pc) \ static inline int TestClearPageCgroup##uname(struct page_cgroup *pc) \ { return test_and_clear_bit(PCG_##lname, &pc->flags); } -/* Cache flag is set only once (at allocation) */ -TESTPCGFLAG(Cache, CACHE) -CLEARPCGFLAG(Cache, CACHE) -SETPCGFLAG(Cache, CACHE) - TESTPCGFLAG(Used, USED) CLEARPCGFLAG(Used, USED) SETPCGFLAG(Used, USED) @@ -85,7 +79,7 @@ static inline void lock_page_cgroup(struct page_cgroup *pc) { /* * Don't take this lock in IRQ context. - * This lock is for pc->mem_cgroup, USED, CACHE, MIGRATION + * This lock is for pc->mem_cgroup, USED, MIGRATION */ bit_spin_lock(PCG_LOCK, &pc->flags); } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 69af5d5801f..88113ee32ac 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -690,15 +690,19 @@ static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg, } static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg, - bool file, int nr_pages) + bool anon, int nr_pages) { preempt_disable(); - if (file) - __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE], + /* + * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is + * counted as CACHE even if it's on ANON LRU. + */ + if (anon) + __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS], nr_pages); else - __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS], + __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE], nr_pages); /* pagein of a big page is an event. So, ignore page size */ @@ -2442,6 +2446,7 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg, { struct zone *uninitialized_var(zone); bool was_on_lru = false; + bool anon; lock_page_cgroup(pc); if (unlikely(PageCgroupUsed(pc))) { @@ -2477,19 +2482,7 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg, * See mem_cgroup_add_lru_list(), etc. */ smp_wmb(); - switch (ctype) { - case MEM_CGROUP_CHARGE_TYPE_CACHE: - case MEM_CGROUP_CHARGE_TYPE_SHMEM: - SetPageCgroupCache(pc); - SetPageCgroupUsed(pc); - break; - case MEM_CGROUP_CHARGE_TYPE_MAPPED: - ClearPageCgroupCache(pc); - SetPageCgroupUsed(pc); - break; - default: - break; - } + SetPageCgroupUsed(pc); if (lrucare) { if (was_on_lru) { @@ -2500,7 +2493,12 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg, spin_unlock_irq(&zone->lru_lock); } - mem_cgroup_charge_statistics(memcg, PageCgroupCache(pc), nr_pages); + if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED) + anon = true; + else + anon = false; + + mem_cgroup_charge_statistics(memcg, anon, nr_pages); unlock_page_cgroup(pc); /* @@ -2565,6 +2563,7 @@ static int mem_cgroup_move_account(struct page *page, { unsigned long flags; int ret; + bool anon = PageAnon(page); VM_BUG_ON(from == to); VM_BUG_ON(PageLRU(page)); @@ -2593,14 +2592,14 @@ static int mem_cgroup_move_account(struct page *page, __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]); preempt_enable(); } - mem_cgroup_charge_statistics(from, PageCgroupCache(pc), -nr_pages); + mem_cgroup_charge_statistics(from, anon, -nr_pages); if (uncharge) /* This is not "cancel", but cancel_charge does all we need. */ __mem_cgroup_cancel_charge(from, nr_pages); /* caller should have done css_get */ pc->mem_cgroup = to; - mem_cgroup_charge_statistics(to, PageCgroupCache(pc), nr_pages); + mem_cgroup_charge_statistics(to, anon, nr_pages); /* * We charges against "to" which may not have any tasks. Then, "to" * can be under rmdir(). But in current implementation, caller of @@ -2921,6 +2920,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) struct mem_cgroup *memcg = NULL; unsigned int nr_pages = 1; struct page_cgroup *pc; + bool anon; if (mem_cgroup_disabled()) return NULL; @@ -2946,8 +2946,12 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) if (!PageCgroupUsed(pc)) goto unlock_out; + anon = PageAnon(page); + switch (ctype) { case MEM_CGROUP_CHARGE_TYPE_MAPPED: + anon = true; + /* fallthrough */ case MEM_CGROUP_CHARGE_TYPE_DROP: /* See mem_cgroup_prepare_migration() */ if (page_mapped(page) || PageCgroupMigration(pc)) @@ -2964,7 +2968,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) break; } - mem_cgroup_charge_statistics(memcg, PageCgroupCache(pc), -nr_pages); + mem_cgroup_charge_statistics(memcg, anon, -nr_pages); ClearPageCgroupUsed(pc); /* @@ -3271,6 +3275,7 @@ void mem_cgroup_end_migration(struct mem_cgroup *memcg, { struct page *used, *unused; struct page_cgroup *pc; + bool anon; if (!memcg) return; @@ -3292,8 +3297,10 @@ void mem_cgroup_end_migration(struct mem_cgroup *memcg, lock_page_cgroup(pc); ClearPageCgroupMigration(pc); unlock_page_cgroup(pc); - - __mem_cgroup_uncharge_common(unused, MEM_CGROUP_CHARGE_TYPE_FORCE); + anon = PageAnon(used); + __mem_cgroup_uncharge_common(unused, + anon ? MEM_CGROUP_CHARGE_TYPE_MAPPED + : MEM_CGROUP_CHARGE_TYPE_CACHE); /* * If a page is a file cache, radix-tree replacement is very atomic @@ -3303,7 +3310,7 @@ void mem_cgroup_end_migration(struct mem_cgroup *memcg, * and USED bit check in mem_cgroup_uncharge_page() will do enough * check. (see prepare_charge() also) */ - if (PageAnon(used)) + if (anon) mem_cgroup_uncharge_page(used); /* * At migration, we may charge account against cgroup which has no @@ -3333,7 +3340,7 @@ void mem_cgroup_replace_page_cache(struct page *oldpage, /* fix accounting on old pages */ lock_page_cgroup(pc); memcg = pc->mem_cgroup; - mem_cgroup_charge_statistics(memcg, PageCgroupCache(pc), -1); + mem_cgroup_charge_statistics(memcg, false, -1); ClearPageCgroupUsed(pc); unlock_page_cgroup(pc); -- 2.20.1