From: "Michal Koutný" <mkoutny@suse.com>
To: Cai Xinchen <caixinchen1@huawei.com>
Cc: songmuchun@bytedance.com, akpm@linux-foundation.org,
hannes@cmpxchg.org, longman@redhat.com, mhocko@kernel.org,
roman.gushchin@linux.dev, shakeelb@google.com,
cgroups@vger.kernel.org, duanxiongchun@bytedance.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
yosryahmed@google.com, mpenttil@redhat.com
Subject: Re: [PATCH 0/1] Fix vmstat_percpu incorrect subtraction after reparent
Date: Fri, 24 Mar 2023 18:14:11 +0100 [thread overview]
Message-ID: <20230324171411.t2romq3ydphoonu2@blackpad> (raw)
In-Reply-To: <20230320030648.50663-1-caixinchen1@huawei.com>
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On Mon, Mar 20, 2023 at 03:06:47AM +0000, Cai Xinchen <caixinchen1@huawei.com> wrote:
> There are two problems left:
>
> root
> / \
> A B
> / \ \
> C E D
>
> 1. In some case of reparent, some page cache may be used by other memcg
> D but it charges to the parent memcg A of dying memcg E. D is getting
> away with using the page for free while A is taxed.
Note that A is (effectively) taxed even before E is removed due to
hierarchical nature of charging. Then what you describe transforms into
"well-known" problem of shared charging (with not well-known solution
:-/).
HTH,
Michal
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prev parent reply other threads:[~2023-03-24 17:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-20 3:06 Cai Xinchen
2023-03-20 3:06 ` [PATCH 1/1] mm: memcontrol: fix vmstats_percpu state " Cai Xinchen
2023-03-24 17:11 ` Michal Koutný
2023-03-27 1:29 ` Cai Xinchen
2023-03-24 17:14 ` Michal Koutný [this message]
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