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From: Shakeel Butt <shakeel.butt@linux.dev>
To: Klara Modin <klarasmodin@gmail.com>
Cc: "Tejun Heo" <tj@kernel.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Johannes Weiner" <hannes@cmpxchg.org>,
	"Michal Hocko" <mhocko@kernel.org>,
	"Roman Gushchin" <roman.gushchin@linux.dev>,
	"Muchun Song" <muchun.song@linux.dev>,
	"Yosry Ahmed" <yosry.ahmed@linux.dev>,
	"Michal Koutný" <mkoutny@suse.com>,
	"Vlastimil Babka" <vbabka@suse.cz>,
	"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>,
	"JP Kobryn" <inwardvessel@gmail.com>,
	bpf@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"Meta kernel team" <kernel-team@meta.com>
Subject: Re: [OFFLIST PATCH 2/2] cgroup: use subsystem-specific rstat locks to avoid contention
Date: Wed, 21 May 2025 16:23:44 -0700	[thread overview]
Message-ID: <a6le7a3gzao7acxzo4i2sfnoxffmz2vhd34gzlgsow4uy7lv6k@tigt33bel4fi> (raw)
In-Reply-To: <gzwa67k6i35jw5h3qfdajuzxa2zgm6ws2x5rjiisont4xiz4bp@kneusjz5bxwb>

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.



  parent reply	other threads:[~2025-05-21 23:23 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-29  6:12 [RFC PATCH 0/3] cgroup: nmi safe css_rstat_updated Shakeel Butt
2025-04-29  6:12 ` [RFC PATCH 1/3] llist: add list_add_iff_not_on_list() Shakeel Butt
2025-04-30 12:44   ` [RFC PATCH 1/3] llist: add list_add_iff_not_on_list()g Yosry Ahmed
2025-04-29  6:12 ` [RFC PATCH 2/3] cgroup: support to enable nmi-safe css_rstat_updated Shakeel Butt
2025-04-29  6:12 ` [RFC PATCH 3/3] cgroup: make css_rstat_updated nmi safe Shakeel Butt
2025-04-30 13:14   ` Yosry Ahmed
2025-05-01 22:10     ` Shakeel Butt
2025-05-06  9:41       ` Yosry Ahmed
2025-05-06 19:30         ` Shakeel Butt
2025-05-07  6:52           ` Yosry Ahmed
2025-04-29  6:12 ` [OFFLIST PATCH 1/2] cgroup: use separate rstat trees for each subsystem Shakeel Butt
2025-04-29  6:12   ` [OFFLIST PATCH 2/2] cgroup: use subsystem-specific rstat locks to avoid contention Shakeel Butt
2025-04-29  6:15     ` Shakeel Butt
2025-05-21 22:23       ` Klara Modin
2025-05-21 22:29         ` Tejun Heo
2025-05-21 23:23         ` Shakeel Butt [this message]
2025-05-21 23:33           ` Shakeel Butt
2025-05-21 23:47             ` JP Kobryn
2025-05-21 23:50               ` Shakeel Butt
2025-05-21 23:52                 ` JP Kobryn
2025-05-21 23:47             ` Shakeel Butt
2025-04-29  6:15   ` [OFFLIST PATCH 1/2] cgroup: use separate rstat trees for each subsystem Shakeel Butt

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