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Tue, 29 Jul 2025 16:53:36 -0700 (PDT) Message-ID: <378a7d41-5588-44af-ae78-6bfd43e9709a@gmail.com> Date: Tue, 29 Jul 2025 16:53:34 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/5 cgroup/for-6.16-fixes] harden css_create() for safe placement of call to css_rstat_init() To: =?UTF-8?Q?Michal_Koutn=C3=BD?= Cc: tj@kernel.org, shakeel.butt@linux.dev, yosryahmed@google.com, hannes@cmpxchg.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, kernel-team@meta.com References: <20250722014030.297537-1-inwardvessel@gmail.com> Content-Language: en-US From: JP Kobryn In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 7/29/25 2:42 AM, Michal Koutný wrote: > On Mon, Jul 28, 2025 at 11:04:56AM -0700, JP Kobryn wrote: >> I did consider adding an "initialized" flag to the css but since there can >> be multiple css's per >> cgroup it felt like it would be adding overhead. So I went the path of >> getting the call >> sequence right. I'm open to feedback on this, though. > > An implicit flag that builds upon the assumption that css_rstat_init() > must only succeed after it allocates ->rstat_cpu (didn't check gotchas > of this approach with !CONFIG_SMP) I think this can work. This can probably be the early fix and then the refactoring can follow.