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From: Shakeel Butt To: Klara Modin Cc: Tejun Heo , Andrew Morton , Alexei Starovoitov , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Yosry Ahmed , Michal =?utf-8?Q?Koutn=C3=BD?= , Vlastimil Babka , Sebastian Andrzej Siewior , JP Kobryn , bpf@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: Re: [OFFLIST PATCH 2/2] cgroup: use subsystem-specific rstat locks to avoid contention Message-ID: References: <20250428174943.69803-1-inwardvessel@gmail.com> <20250428174943.69803-2-inwardvessel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 828C7180003 X-Stat-Signature: c8ywwrcmo648ejgc6yo96m7xtaeqca1m X-Rspam-User: X-HE-Tag: 1747869833-77470 X-HE-Meta: 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 GrrR59/y AouKSGBZ6vDdk0eAAL8Jck7e2QroIM8tnGYBo/rrAXh/MG5TLXDxPb/Yh2Y3UzvOlcu00LvDUbrZTFLft3QxiBdzutoi4lJTzfyUTO2g5mzNiaaf8QbhfN62xIn+lWOCMv7JsWOuUI3fqMD0Vi9bo8yeMxUqDbCsRAOimnfrdgWb9HBkADPkrjLQm2TSpHBxueyo9CNVzBIvN6wfgjYmVfh9BSuQx+UKXtJL+zCXiy0kJcS9hdd5GOWwLQA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, May 22, 2025 at 12:23:44AM +0200, Klara Modin wrote: > Hi, > > On 2025-04-28 23:15:58 -0700, Shakeel Butt wrote: > > Please ignore this patch as it was sent by mistake. > > This seems to have made it into next: > > 748922dcfabd ("cgroup: use subsystem-specific rstat locks to avoid contention") > > It causes a BUG and eventually a panic on my Raspberry Pi 1: > > WARNING: CPU: 0 PID: 0 at mm/percpu.c:1766 pcpu_alloc_noprof (mm/percpu.c:1766 (discriminator 2)) > illegal size (0) or align (4) for percpu allocation Ok this config is without CONFIG_SMP and on such configs we have: typedef struct { } arch_spinlock_t; So, we are doing ss->rstat_ss_cpu_lock = alloc_percpu(0). Hmm, let me think more on how to fix this.