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From: "Michal Koutný" <mkoutny@suse.com>
To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: Tejun Heo <tj@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>,
	 cgroups@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	 linux-hardening@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
	 Chen Ridong <chenridong@huaweicloud.com>
Subject: Re: [RFC] cgroup: Avoid thousands of -Wflex-array-member-not-at-end warnings
Date: Tue, 2 Sep 2025 13:17:11 +0200	[thread overview]
Message-ID: <tl6b6chfawtykzrxlmysn6ev7mq7gm764rnlsag7pfme7vhpof@lbwqooaybqmr> (raw)
In-Reply-To: <92912540-23d2-4b18-9002-bac962682caf@embeddedor.com>

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On Tue, Sep 02, 2025 at 09:56:34AM +0200, "Gustavo A. R. Silva" <gustavo@embeddedor.com> wrote:
> If the increase in size is not a problem, then something like this
> works fine (unless there is a problem with moving those two members
> at the end of cgroup_root?):

Please don't forget to tackle cgroup_root allocators. IIUC, this move
towards the end shifts the burden to them.

There's only the rcu_head we care about.

(You seem to be well versed with flex arrays, I was wondering if
something like this could be rearranged to make it work (assuming the
union is at the end of its containers):

	union {
		struct cgroup *ancestors[];
		struct {
			struct cgroup *_root_ancestor;
			struct cgroup *_low_ancestors[];
		};
	};
)

Thanks,
Michal

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  reply	other threads:[~2025-09-02 11:17 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-30 13:30 [RFC] cgroup: Avoid thousands of -Wflex-array-member-not-at-end warnings Gustavo A. R. Silva
2025-09-01  1:29 ` Chen Ridong
2025-09-01  7:44   ` Gustavo A. R. Silva
2025-09-01 13:37 ` Michal Koutný
2025-09-01 15:21   ` Gustavo A. R. Silva
2025-09-01 15:44     ` Gustavo A. R. Silva
2025-09-01 18:04       ` Michal Koutný
2025-09-01 17:58     ` Michal Koutný
2025-09-02  7:56       ` Gustavo A. R. Silva
2025-09-02 11:17         ` Michal Koutný [this message]
2025-09-02 12:37           ` Gustavo A. R. Silva

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