From: Yu Kuai <yukuai1@huaweicloud.com>
To: Tejun Heo <tj@kernel.org>, Yu Kuai <yukuai1@huaweicloud.com>
Cc: hch@infradead.org, josef@toxicpanda.com, axboe@kernel.dk,
cgroups@vger.kernel.org, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org, yi.zhang@huawei.com,
"yukuai (C)" <yukuai3@huawei.com>
Subject: Re: [PATCH v2 1/2] blk-iocost: add refcounting for iocg
Date: Fri, 13 Jan 2023 09:25:11 +0800 [thread overview]
Message-ID: <ac95dfb8-b1b6-8916-bde8-1edb573e7ca5@huaweicloud.com> (raw)
In-Reply-To: <Y8CwwghZ0adMsHFC@slm.duckdns.org>
Hi,
在 2023/01/13 9:15, Tejun Heo 写道:
> Hello,
>
> On Fri, Jan 13, 2023 at 09:10:25AM +0800, Yu Kuai wrote:
>>> only activate the policy when the controller is actually enabled. So, idk.
>>> What's wrong with synchronizing the two removal paths? blkcg policies are
>>> combinations of cgroups and block device configurations, so having exit
>>> paths from both sides is kinda natural.
>>
>> I still can't figure out how to synchronizing them will a mutex. Maybe
>> I'm being foolish...
>
> Hmm... can't you just use e.g. per-bdev mutex which is grabbed by both
> blkg_free_workfn() and blkcg_deactivate_policy()?
>
I think hold the lock in blkg_free_workfn() is too late, pd_free_fn()
for parent from blkcg_deactivate_policy() can be called first.
t1: remove cgroup t1/t2
blkcg_destroy_blkgs
blkg_destroy
percpu_ref_kill(&blkg->refcnt)
blkg_release
blkg_free
schedule_work(&blkg->free_work)
// t1 is done
t2: handle t1 from removing device
blkcg_deactivate_policy
pd_free_fn
// free parent
t3: from t1
blkg_free_workfn
pd_free_fn
// free child
Thanks,
Kuai
next prev parent reply other threads:[~2023-01-13 1:25 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-27 12:55 [PATCH v2 0/2] blk-iocost: add refcounting for iocg and ioc Yu Kuai
2022-12-27 12:55 ` [PATCH v2 1/2] blk-iocost: add refcounting for iocg Yu Kuai
2023-01-04 21:44 ` Tejun Heo
2023-01-05 1:14 ` Yu Kuai
2023-01-05 18:32 ` Tejun Heo
2023-01-06 1:08 ` Yu Kuai
2023-01-06 20:18 ` Tejun Heo
2023-01-09 1:32 ` Yu Kuai
2023-01-09 18:23 ` Tejun Heo
2023-01-10 1:39 ` Yu Kuai
2023-01-10 18:36 ` Tejun Heo
2023-01-11 1:36 ` Yu Kuai
2023-01-11 17:07 ` Tejun Heo
2023-01-12 6:18 ` Yu Kuai
2023-01-13 0:53 ` Tejun Heo
2023-01-13 1:10 ` Yu Kuai
2023-01-13 1:15 ` Tejun Heo
2023-01-13 1:25 ` Yu Kuai [this message]
2023-01-13 17:16 ` Tejun Heo
2023-01-16 3:25 ` Yu Kuai
2022-12-27 12:55 ` [PATCH v2 2/2] blk-iocost: add refcounting for ioc Yu Kuai
2023-01-04 21:45 ` Tejun Heo
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