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From: Quanyang Wang <quanyang.wang@windriver.com>
To: "Ming Lei" <ming.lei@redhat.com>, "Michal Koutný" <mkoutny@suse.com>
Cc: Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>, Jens Axboe <axboe@kernel.dk>,
	Roman Gushchin <guro@fb.com>,
	cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [V2][PATCH] cgroup: fix memory leak caused by missing cgroup_bpf_offline
Date: Wed, 20 Oct 2021 13:22:06 +0800	[thread overview]
Message-ID: <7a21a20d-eb12-e491-4e69-4e043b3b6d8d@windriver.com> (raw)
In-Reply-To: <YW98RTBdzqin+9Ko@T590>

Hi Ming,

On 10/20/21 10:17 AM, Ming Lei wrote:
> On Tue, Oct 19, 2021 at 07:10:26PM +0200, Michal Koutný wrote:
>> Hi.
>>
>> On Tue, Oct 19, 2021 at 06:41:14PM +0800, Quanyang Wang <quanyang.wang@windriver.com> wrote:
>>> So I add 2 "Fixes tags" here to indicate that 2 commits introduce two
>>> different issues.
>>
>> AFAIU, both the changes are needed to cause the leak, a single patch
>> alone won't cause the issue. Is that correct? (Perhaps not as I realize,
>> see below.)
>>
>> But on second thought, the problem is the missing percpu_ref_exit() in
>> the (root) cgroup release path and percpu counter would allocate the
>> percpu_count_ptr anyway, so 4bfc0bb2c60e is only making the leak more
>> visible. Is this correct?
>>
>> I agree the commit 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of
>> percpu_ref in fast path") alone did nothing wrong.
> 
> If only precpu_ref data is leaked, it is fine to add "Fixes: 2b0d3d3e4fcf",
> I thought cgroup_bpf_release() needs to release more for root cgroup, but
> looks not true.
For now, I can only observe that precpu_ref data is leaked when running 
ltp testsuite.
Thanks,
Quanyang
> 
> 
> Thanks,
> Ming
> 

  reply	other threads:[~2021-10-20  5:22 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-18  7:56 [V2][PATCH] cgroup: fix memory leak caused by missing cgroup_bpf_offline quanyang.wang
2021-10-18  9:02 ` Ming Lei
2021-10-18 10:06   ` Quanyang Wang
     [not found]     ` <8fdcaded-474e-139b-a9bc-5ab6f91fbd4f-CWA4WttNNZF54TAoqtyWWQ@public.gmane.org>
2021-10-18 12:59       ` Ming Lei
2021-10-19 10:41         ` Quanyang Wang
2021-10-19 17:10           ` Michal Koutný
2021-10-20  2:17             ` Ming Lei
2021-10-20  5:22               ` Quanyang Wang [this message]
2021-10-20 17:28                 ` Michal Koutný
2021-10-22 11:03                   ` Quanyang Wang
2021-10-20  5:16             ` Quanyang Wang
2021-10-19 10:41         ` Quanyang Wang
     [not found] ` <20211018075623.26884-1-quanyang.wang-CWA4WttNNZF54TAoqtyWWQ@public.gmane.org>
2021-10-22  1:30   ` Roman Gushchin
2021-10-22 11:55     ` Quanyang Wang
     [not found]       ` <35e9e89f-d92f-06f9-b919-ef956d99d7df-CWA4WttNNZF54TAoqtyWWQ@public.gmane.org>
2021-10-22 21:29         ` Alexei Starovoitov

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