From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 7316E6B0055 for ; Thu, 24 Sep 2009 01:51:47 -0400 (EDT) Date: Thu, 24 Sep 2009 14:48:08 +0900 From: Daisuke Nishimura Subject: [RFC][PATCH 5/8] memcg: migrate charge of mapped page Message-Id: <20090924144808.6a0d5140.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20090924144214.508469d1.nishimura@mxp.nes.nec.co.jp> References: <20090917112304.6cd4e6f6.nishimura@mxp.nes.nec.co.jp> <20090917160103.1bcdddee.nishimura@mxp.nes.nec.co.jp> <20090924144214.508469d1.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: Balbir Singh , KAMEZAWA Hiroyuki , Paul Menage , Li Zefan , Daisuke Nishimura List-ID: This patch is the core part of this charge migration feature. It adds functions to migrate charge of pages mapped by the task. Implementation: - define struct migrate_charge and a valuable of it(mc) to remember the count of pre-charges and other information. - At can_attach(), parse the page table of the task and count the number of mapped pages which are charged to the source mem_cgroup, and call __mem_cgroup_try_charge() repeatedly and count up mc->precharge. - At attach(), parse the page table again, find a target page as we did in can_attach(), and call mem_cgroup_move_account() about the page. - Cancel all charges if mc->precharge > 0 on failure or at the end of charge migration. Signed-off-by: Daisuke Nishimura --- mm/memcontrol.c | 270 ++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 files changed, 268 insertions(+), 2 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 30499d9..fbcc195 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -21,6 +21,8 @@ #include #include #include +#include +#include #include #include #include @@ -274,6 +276,18 @@ enum charge_type { #define MEM_CGROUP_RECLAIM_SOFT_BIT 0x2 #define MEM_CGROUP_RECLAIM_SOFT (1 << MEM_CGROUP_RECLAIM_SOFT_BIT) +/* + * Variables for charge migration at task move. + * mc and its members are protected by cgroup_lock + */ +struct migrate_charge { + struct task_struct *tsk; + struct mem_cgroup *from; + struct mem_cgroup *to; + unsigned long precharge; +}; +static struct migrate_charge *mc; + static void mem_cgroup_get(struct mem_cgroup *mem); static void mem_cgroup_put(struct mem_cgroup *mem); static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem); @@ -1362,7 +1376,7 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, if (soft_fail_res) { mem_over_soft_limit = mem_cgroup_from_res_counter(soft_fail_res, res); - if (mem_cgroup_soft_limit_check(mem_over_soft_limit)) + if (page && mem_cgroup_soft_limit_check(mem_over_soft_limit)) mem_cgroup_update_tree(mem_over_soft_limit, page); } done: @@ -3197,10 +3211,167 @@ static int mem_cgroup_populate(struct cgroup_subsys *ss, return ret; } +/* Handlers for charge migration at task move. */ +/** + * is_target_pte_for_migration - check a pte whether it is target for migration + * @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) + * + * Returns + * 0(MIGRATION_TARGET_NONE): if the pte is not a target for charge migration. + * 1(MIGRATION_TARGET_PAGE): if the page corresponding to this pte is a target + * for charge migration. if @target is not NULL, the page is stored in + * target->page with extra refcnt got(Callers should handle it). + * + * Called with pte lock held. + */ +union migration_target { + struct page *page; +}; + +enum migration_target_type { + MIGRATION_TARGET_NONE, /* not used */ + MIGRATION_TARGET_PAGE, +}; + +static int is_target_pte_for_migration(struct vm_area_struct *vma, + unsigned long addr, pte_t ptent, union migration_target *target) +{ + struct page *page; + struct page_cgroup *pc; + int ret = 0; + + if (!pte_present(ptent)) + return 0; + + page = vm_normal_page(vma, addr, ptent); + if (!page || !page_mapped(page)) + return 0; + if (!get_page_unless_zero(page)) + return 0; + + pc = lookup_page_cgroup(page); + lock_page_cgroup(pc); + if (PageCgroupUsed(pc) && pc->mem_cgroup == mc->from) { + ret = MIGRATION_TARGET_PAGE; + if (target) + target->page = page; + } + unlock_page_cgroup(pc); + + if (!ret || !target) + put_page(page); + + return ret; +} + +static int migrate_charge_do_precharge(void) +{ + int ret = -ENOMEM; + struct mem_cgroup *mem = mc->to; + + ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false, NULL); + if (ret || !mem) + return -ENOMEM; + + mc->precharge++; + return ret; +} + +static int migrate_charge_prepare_pte_range(pmd_t *pmd, + unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + int ret = 0; + unsigned long count = 0; + struct vm_area_struct *vma = walk->private; + pte_t *pte; + spinlock_t *ptl; + + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + for (; addr != end; pte++, addr += PAGE_SIZE) + if (is_target_pte_for_migration(vma, addr, *pte, NULL)) + count++; + pte_unmap_unlock(pte - 1, ptl); + + while (count-- && !ret) + ret = migrate_charge_do_precharge(); + + return ret; +} + +static int migrate_charge_prepare(void) +{ + int ret = 0; + struct mm_struct *mm; + struct vm_area_struct *vma; + + mm = get_task_mm(mc->tsk); + if (!mm) + return 0; + + down_read(&mm->mmap_sem); + for (vma = mm->mmap; vma; vma = vma->vm_next) { + struct mm_walk migrate_charge_prepare_walk = { + .pmd_entry = migrate_charge_prepare_pte_range, + .mm = mm, + .private = vma, + }; + if (signal_pending(current)) { + ret = -EINTR; + break; + } + if (is_vm_hugetlb_page(vma)) + continue; + ret = walk_page_range(vma->vm_start, vma->vm_end, + &migrate_charge_prepare_walk); + if (ret) + break; + cond_resched(); + } + up_read(&mm->mmap_sem); + + mmput(mm); + return ret; +} + +static void mem_cgroup_clear_migrate_charge(void) +{ + VM_BUG_ON(!mc); + + while (mc->precharge--) + __mem_cgroup_cancel_charge(mc->to); + kfree(mc); + mc = NULL; +} + static int mem_cgroup_can_migrate_charge(struct mem_cgroup *mem, struct task_struct *p) { - return 0; + int ret; + struct mem_cgroup *from = mem_cgroup_from_task(p); + + VM_BUG_ON(mc); + + if (from == mem) + return 0; + + mc = kmalloc(sizeof(struct migrate_charge), GFP_KERNEL); + if (!mc) + return -ENOMEM; + + mc->tsk = p; + mc->from = from; + mc->to = mem; + mc->precharge = 0; + + ret = migrate_charge_prepare(); + + if (ret) + mem_cgroup_clear_migrate_charge(); + return ret; } static int mem_cgroup_can_attach(struct cgroup_subsys *ss, @@ -3220,10 +3391,105 @@ static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss, struct task_struct *p, bool threadgroup) { + if (mc) + mem_cgroup_clear_migrate_charge(); +} + +static int migrate_charge_pte_range(pmd_t *pmd, + unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + int ret = 0; + struct vm_area_struct *vma = walk->private; + pte_t *pte; + spinlock_t *ptl; + +retry: + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + for (; addr != end; addr += PAGE_SIZE) { + pte_t ptent = *(pte++); + union migration_target target; + int type; + struct page *page; + struct page_cgroup *pc; + + if (!mc->precharge) + break; + + type = is_target_pte_for_migration(vma, addr, ptent, &target); + switch (type) { + case MIGRATION_TARGET_PAGE: + page = target.page; + if (isolate_lru_page(page)) + goto put; + pc = lookup_page_cgroup(page); + if (!mem_cgroup_move_account(pc, mc->from, mc->to)) { + css_put(&mc->to->css); + mc->precharge--; + } + putback_lru_page(page); +put: /* is_target_pte_for_migration() gets the page */ + put_page(page); + break; + default: + continue; + } + } + pte_unmap_unlock(pte - 1, ptl); + + if (addr != end) { + /* + * We have consumed all precharges we got in can_attach(). + * We try precharge one by one, but don't do any additional + * precharges nor charge migration if we have failed in + * precharge once in attach() phase. + */ + ret = migrate_charge_do_precharge(); + if (!ret) + goto retry; + } + + return ret; } static void mem_cgroup_migrate_charge(void) { + struct mm_struct *mm; + struct vm_area_struct *vma; + + if (!mc) + return; + + mm = get_task_mm(mc->tsk); + if (!mm) + goto out; + + lru_add_drain_all(); + down_read(&mm->mmap_sem); + for (vma = mm->mmap; vma; vma = vma->vm_next) { + int ret; + struct mm_walk migrate_charge_walk = { + .pmd_entry = migrate_charge_pte_range, + .mm = mm, + .private = vma, + }; + if (is_vm_hugetlb_page(vma)) + continue; + ret = walk_page_range(vma->vm_start, vma->vm_end, + &migrate_charge_walk); + if (ret) + /* + * means we have consumed all precharges and failed in + * doing additional precharge. Just abandon here. + */ + break; + cond_resched(); + } + up_read(&mm->mmap_sem); + + mmput(mm); +out: + mem_cgroup_clear_migrate_charge(); } static void mem_cgroup_move_task(struct cgroup_subsys *ss, -- 1.5.6.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org