From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx123.postini.com [74.125.245.123]) by kanga.kvack.org (Postfix) with SMTP id 714B76B00A8 for ; Fri, 30 Nov 2012 08:31:40 -0500 (EST) From: Glauber Costa Subject: [PATCH 2/4] memcg: prevent changes to move_charge_at_immigrate during task attach Date: Fri, 30 Nov 2012 17:31:24 +0400 Message-Id: <1354282286-32278-3-git-send-email-glommer@parallels.com> In-Reply-To: <1354282286-32278-1-git-send-email-glommer@parallels.com> References: <1354282286-32278-1-git-send-email-glommer@parallels.com> Sender: owner-linux-mm@kvack.org List-ID: To: cgroups@vger.kernel.org Cc: linux-mm@kvack.org, Tejun Heo , kamezawa.hiroyu@jp.fujitsu.com, Johannes Weiner , Michal Hocko , Glauber Costa Currently, we rely on the cgroup_lock() to prevent changes to move_charge_at_immigrate during task migration. We can do something similar to what cpuset is doing, and flip a flag to tell us if task movement is taking place. In theory, we could busy loop waiting for that value to return to 0 - it will eventually. But I am judging that returning EAGAIN is not too much of a problem, since file writers already should be checking for error codes anyway. Signed-off-by: Glauber Costa --- mm/memcontrol.c | 64 +++++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 51 insertions(+), 13 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index feba87d..d80b6b5 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -311,7 +311,13 @@ struct mem_cgroup { * Should we move charges of a task when a task is moved into this * mem_cgroup ? And what type of charges should we move ? */ - unsigned long move_charge_at_immigrate; + unsigned long move_charge_at_immigrate; + /* + * Tasks are being attached to this memcg. Used mostly to prevent + * changes to move_charge_at_immigrate + */ + int attach_in_progress; + /* * set > 0 if pages under this cgroup are moving to other cgroup. */ @@ -4114,6 +4120,7 @@ static int mem_cgroup_move_charge_write(struct cgroup *cgrp, struct cftype *cft, u64 val) { struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp); + int ret = -EAGAIN; if (val >= (1 << NR_MOVE_TYPE)) return -EINVAL; @@ -4123,10 +4130,13 @@ static int mem_cgroup_move_charge_write(struct cgroup *cgrp, * inconsistent. */ cgroup_lock(); + if (memcg->attach_in_progress) + goto out; memcg->move_charge_at_immigrate = val; + ret = 0; +out: cgroup_unlock(); - - return 0; + return ret; } #else static int mem_cgroup_move_charge_write(struct cgroup *cgrp, @@ -5443,12 +5453,12 @@ static void mem_cgroup_clear_mc(void) mem_cgroup_end_move(from); } -static int mem_cgroup_can_attach(struct cgroup *cgroup, - struct cgroup_taskset *tset) + +static int __mem_cgroup_can_attach(struct mem_cgroup *memcg, + struct cgroup_taskset *tset) { struct task_struct *p = cgroup_taskset_first(tset); int ret = 0; - struct mem_cgroup *memcg = mem_cgroup_from_cont(cgroup); if (memcg->move_charge_at_immigrate) { struct mm_struct *mm; @@ -5482,8 +5492,8 @@ static int mem_cgroup_can_attach(struct cgroup *cgroup, return ret; } -static void mem_cgroup_cancel_attach(struct cgroup *cgroup, - struct cgroup_taskset *tset) +static void __mem_cgroup_cancel_attach(struct mem_cgroup *memcg, + struct cgroup_taskset *tset) { mem_cgroup_clear_mc(); } @@ -5630,8 +5640,8 @@ retry: up_read(&mm->mmap_sem); } -static void mem_cgroup_move_task(struct cgroup *cont, - struct cgroup_taskset *tset) +static void __mem_cgroup_move_task(struct mem_cgroup *memcg, + struct cgroup_taskset *tset) { struct task_struct *p = cgroup_taskset_first(tset); struct mm_struct *mm = get_task_mm(p); @@ -5645,20 +5655,48 @@ static void mem_cgroup_move_task(struct cgroup *cont, mem_cgroup_clear_mc(); } #else /* !CONFIG_MMU */ +static int __mem_cgroup_can_attach(struct mem_cgroup *memcg, + struct cgroup_taskset *tset) +{ + return 0; +} + +static void __mem_cgroup_cancel_attach(struct mem_cgroup *memcg, + struct cgroup_taskset *tset) +{ +} + +static void __mem_cgroup_move_task(struct mem_cgroup *memcg, + struct cgroup_taskset *tset) +{ +} +#endif static int mem_cgroup_can_attach(struct cgroup *cgroup, struct cgroup_taskset *tset) { - return 0; + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgroup); + + memcg->attach_in_progress++; + return __mem_cgroup_can_attach(memcg, tset); } + static void mem_cgroup_cancel_attach(struct cgroup *cgroup, struct cgroup_taskset *tset) { + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgroup); + + __mem_cgroup_cancel_attach(memcg, tset); + memcg->attach_in_progress--; } -static void mem_cgroup_move_task(struct cgroup *cont, + +static void mem_cgroup_move_task(struct cgroup *cgroup, struct cgroup_taskset *tset) { + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgroup); + + __mem_cgroup_move_task(memcg, tset); + memcg->attach_in_progress--; } -#endif struct cgroup_subsys mem_cgroup_subsys = { .name = "memory", -- 1.7.11.7 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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