From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 45F5D6B0062 for ; Fri, 6 Nov 2009 00:33:56 -0500 (EST) Date: Fri, 6 Nov 2009 14:16:04 +0900 From: Daisuke Nishimura Subject: [PATCH -mmotm 8/8] memcg: recharge charges of anonymous swap Message-Id: <20091106141604.ff80e40f.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20091106141011.3ded1551.nishimura@mxp.nes.nec.co.jp> References: <20091106141011.3ded1551.nishimura@mxp.nes.nec.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: linux-mm Cc: Andrew Morton , Balbir Singh , KAMEZAWA Hiroyuki , Li Zefan , Paul Menage , Daisuke Nishimura List-ID: This patch is another core part of this recharge-at-task-move feature. It enables recharge of anonymous swaps. To move the charge of swap, we need to exchange swap_cgroup's record. In current implementation, swap_cgroup's record is protected by: - page lock: if the entry is on swap cache. - swap_lock: if the entry is not on swap cache. This works well in usual swap-in/out activity. But this behavior make charge migration of swap check many conditions to exchange swap_cgroup's record safely. So I changed modification of swap_cgroup's recored(swap_cgroup_record()) to use xchg, and define a new function to cmpxchg swap_cgroup's record. This patch also enables recharge of non pte_present but not uncharged swap caches, which can be exist on swap-out path, by getting the target pages via find_get_page() as do_mincore() does. Signed-off-by: Daisuke Nishimura --- Documentation/cgroups/memory.txt | 5 +- include/linux/page_cgroup.h | 2 + include/linux/swap.h | 1 + mm/memcontrol.c | 140 ++++++++++++++++++++++++++++++-------- mm/page_cgroup.c | 35 +++++++++- mm/swapfile.c | 32 +++++++++ 6 files changed, 182 insertions(+), 33 deletions(-) diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt index 54281ff..2820626 100644 --- a/Documentation/cgroups/memory.txt +++ b/Documentation/cgroups/memory.txt @@ -441,8 +441,9 @@ And if you want disable it again We recharge a charge which meets the following conditions. a. It must be charged to the old cgroup. -b. A charge of an anonymous page used by the target task. The page must be used - only by the target task. +b. A charge of an anonymous page(or swap of it) used by the target task. + The page(or swap) must be used only by the target task. You must enable + Swap Extension(see 2.4) to enable recharge of swap. Note: More type of pages(e.g. file cache, shmem,) will be supported in future. diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h index b0e4eb1..30b0813 100644 --- a/include/linux/page_cgroup.h +++ b/include/linux/page_cgroup.h @@ -118,6 +118,8 @@ static inline void __init page_cgroup_init_flatmem(void) #include #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP +extern unsigned short swap_cgroup_cmpxchg(swp_entry_t ent, + unsigned short old, unsigned short new); extern unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id); extern unsigned short lookup_swap_cgroup(swp_entry_t ent); extern int swap_cgroup_swapon(int type, unsigned long max_pages); diff --git a/include/linux/swap.h b/include/linux/swap.h index 9f0ca32..2a3209e 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -355,6 +355,7 @@ static inline void disable_swap_token(void) #ifdef CONFIG_CGROUP_MEM_RES_CTLR extern void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout); +extern int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep); #else static inline void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 7e96f3b..50e28df 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -34,6 +34,7 @@ #include #include #include +#include #include #include #include @@ -2231,6 +2232,49 @@ void mem_cgroup_uncharge_swap(swp_entry_t ent) } rcu_read_unlock(); } + +/** + * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record. + * @entry: swap entry to be moved + * @from: mem_cgroup which the entry is moved from + * @to: mem_cgroup which the entry is moved to + * + * It successes only when the swap_cgroup's record for this entry is the same + * as the mem_cgroup's id of @from. + * + * Returns 0 on success, 1 on failure. + * + * The caller must have called __mem_cgroup_try_charge on @to. + */ +static int mem_cgroup_move_swap_account(swp_entry_t entry, + struct mem_cgroup *from, struct mem_cgroup *to) +{ + unsigned short old_id, new_id; + + old_id = css_id(&from->css); + new_id = css_id(&to->css); + + if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) { + if (!mem_cgroup_is_root(from)) + res_counter_uncharge(&from->memsw, PAGE_SIZE); + mem_cgroup_swap_statistics(from, false); + mem_cgroup_put(from); + + if (!mem_cgroup_is_root(to)) + res_counter_uncharge(&to->res, PAGE_SIZE); + mem_cgroup_swap_statistics(to, true); + mem_cgroup_get(to); + + return 0; + } + return 1; +} +#else +static inline int mem_cgroup_move_swap_account(swp_entry_t entry, + struct mem_cgroup *from, struct mem_cgroup *to) +{ + return 1; +} #endif /* @@ -3460,63 +3504,92 @@ static int mem_cgroup_populate(struct cgroup_subsys *ss, * @vma: the vma the pte to be checked belongs * @addr: the address corresponding to the pte to be checked * @ptent: the pte to be checked - * @target: the pointer the target page will be stored(can be NULL) + * @target: the pointer the target page or entry will be stored(can be NULL) * * Returns * 0(RECHARGE_TARGET_NONE): if the pte is not a target for recharge. * 1(RECHARGE_TARGET_PAGE): if the page corresponding to this pte is a target * for recharge. if @target is not NULL, the page is stored in target->page * with extra refcnt got(Callers should handle it). + * 2(MIGRATION_TARGET_SWAP): if the swap entry corresponding to this pte is a + * target for charge migration. if @target is not NULL, the entry is stored + * in target->ent. * * Called with pte lock held. */ -/* We add a new member later. */ union recharge_target { struct page *page; + swp_entry_t ent; }; -/* We add a new type later. */ enum recharge_target_type { RECHARGE_TARGET_NONE, /* not used */ RECHARGE_TARGET_PAGE, + RECHARGE_TARGET_SWAP, }; static int is_target_pte_for_recharge(struct vm_area_struct *vma, unsigned long addr, pte_t ptent, union recharge_target *target) { - struct page *page; + struct page *page = NULL; struct page_cgroup *pc; + swp_entry_t ent = { .val = 0 }; int ret = 0; + int user = 0; - if (!pte_present(ptent)) - return 0; - - page = vm_normal_page(vma, addr, ptent); - if (!page || !page_mapped(page)) - return 0; - /* TODO: We don't recharge file(including shmem/tmpfs) pages for now. */ - if (!PageAnon(page)) - return 0; - /* - * TODO: We don't recharge shared(used by multiple processes) pages - * for now. - */ - if (page_mapcount(page) > 1) - return 0; - if (!get_page_unless_zero(page)) + if (!pte_present(ptent)) { + /* TODO: handle swap of shmes/tmpfs */ + if (pte_none(ptent) || pte_file(ptent)) + return 0; + else if (is_swap_pte(ptent)) { + ent = pte_to_swp_entry(ptent); + if (non_swap_entry(ent)) + return 0; + user = mem_cgroup_count_swap_user(ent, &page); + } + } else { + page = vm_normal_page(vma, addr, ptent); + if (!page || !page_mapped(page)) + return 0; + /* + * TODO: We don't recharge file(including shmem/tmpfs) pages + * for now. + */ + if (!PageAnon(page)) + return 0; + if (!get_page_unless_zero(page)) + return 0; + user = page_mapcount(page); + } + if (user > 1) { + /* + * TODO: We don't recharge shared(used by multiple processes) + * pages for now. + */ + if (page) + put_page(page); return 0; + } - pc = lookup_page_cgroup(page); - lock_page_cgroup(pc); - if (PageCgroupUsed(pc) && pc->mem_cgroup == recharge.from) { - ret = RECHARGE_TARGET_PAGE; + if (page) { + pc = lookup_page_cgroup(page); + lock_page_cgroup(pc); + if (PageCgroupUsed(pc) && pc->mem_cgroup == recharge.from) { + ret = RECHARGE_TARGET_PAGE; + if (target) + target->page = page; + } + unlock_page_cgroup(pc); + if (!ret || !target) + put_page(page); + } + /* fall throught */ + if (ent.val && do_swap_account && !ret && + css_id(&recharge.from->css) == lookup_swap_cgroup(ent)) { + ret = RECHARGE_TARGET_SWAP; if (target) - target->page = page; + target->ent = ent; } - unlock_page_cgroup(pc); - - if (!ret || !target) - put_page(page); return ret; } @@ -3667,6 +3740,7 @@ retry: int type; struct page *page; struct page_cgroup *pc; + swp_entry_t ent; if (!recharge.precharge) break; @@ -3687,6 +3761,14 @@ retry: put: /* is_target_pte_for_recharge() gets the page */ put_page(page); break; + case RECHARGE_TARGET_SWAP: + ent = target.ent; + if (!mem_cgroup_move_swap_account(ent, + recharge.from, recharge.to)) { + css_put(&recharge.to->css); + recharge.precharge--; + } + break; default: continue; } diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c index 3d535d5..213b0ee 100644 --- a/mm/page_cgroup.c +++ b/mm/page_cgroup.c @@ -9,6 +9,7 @@ #include #include #include +#include static void __meminit __init_page_cgroup(struct page_cgroup *pc, unsigned long pfn) @@ -335,6 +336,37 @@ not_enough_page: } /** + * swap_cgroup_cmpxchg - cmpxchg mem_cgroup's id for this swp_entry. + * @end: swap entry to be cmpxchged + * @old: old id + * @new: new id + * + * Returns old id at success, 0 at failure. + * (There is no mem_cgroup useing 0 as its id) + */ +unsigned short swap_cgroup_cmpxchg(swp_entry_t ent, + unsigned short old, unsigned short new) +{ + int type = swp_type(ent); + unsigned long offset = swp_offset(ent); + unsigned long idx = offset / SC_PER_PAGE; + unsigned long pos = offset & SC_POS_MASK; + struct swap_cgroup_ctrl *ctrl; + struct page *mappage; + struct swap_cgroup *sc; + + ctrl = &swap_cgroup_ctrl[type]; + + mappage = ctrl->map[idx]; + sc = page_address(mappage); + sc += pos; + if (cmpxchg(&sc->id, old, new) == old) + return old; + else + return 0; +} + +/** * swap_cgroup_record - record mem_cgroup for this swp_entry. * @ent: swap entry to be recorded into * @mem: mem_cgroup to be recorded @@ -358,8 +390,7 @@ unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id) mappage = ctrl->map[idx]; sc = page_address(mappage); sc += pos; - old = sc->id; - sc->id = id; + old = xchg(&sc->id, id); return old; } diff --git a/mm/swapfile.c b/mm/swapfile.c index 93e71cf..28eef54 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -719,6 +719,38 @@ int free_swap_and_cache(swp_entry_t entry) return p != NULL; } +#ifdef CONFIG_CGROUP_MEM_RES_CTLR +/** + * mem_cgroup_count_swap_user - count the user of a swap entry + * @ent: the swap entry to be checked + * @pagep: the pointer for the swap cache page of the entry to be stored + * + * Returns the number of the user of the swap entry. + * If the entry is found on swap cache, the page is stored to pagep with + * refcount of it being incremented. + * + * This function can be used only for swaps for anonymous pages. + */ +int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep) +{ + struct page *page; + struct swap_info_struct *p; + int count = 0; + + page = find_get_page(&swapper_space, ent.val); + if (page) + count += page_mapcount(page); + p = swap_info_get(ent); + if (p) { + count += swap_count(p->swap_map[swp_offset(ent)]); + spin_unlock(&swap_lock); + } + + *pagep = page; + return count; +} +#endif + #ifdef CONFIG_HIBERNATION /* * Find the swap type that corresponds to given device (if any). -- 1.5.6.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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