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b=vNSYdcVIlQppVl9XK6Hmux4x204Rz0Mjmv+zw+0fcgfwr2x5GT4uX2JIaJmKiL//X +aVu/bx794bAn1J5gyNKRxxVz0q+8aZp9uL5cv8EqLQOy8Lyt/hP6VcqQBR/FvyaY/ /QeBzY8X2r50hITutJxTZGLKOmj5UHqgcGJXQu1/XGEaqCUzqPwlFf7hYBuQgTOnvI 36PMZHtc6/ylag+OHYh+k+JFW56ct0PXqZZzkrq9q1+pn8B5JxaHI58umNFDsW2n2V wOBsUqUMv5PrXWZdrlXBAU1YQZC0UIRB+gnQWHO5sJEmr/2Sxzfw9OChifWcsUkMGI 9D4KgdYDIKG4Q== Date: Wed, 29 Oct 2025 12:53:24 -1000 From: Tejun Heo To: Alexei Starovoitov Cc: Roman Gushchin , Song Liu , Andrew Morton , LKML , Alexei Starovoitov , Suren Baghdasaryan , Michal Hocko , Shakeel Butt , Johannes Weiner , Andrii Nakryiko , JP Kobryn , linux-mm , "open list:CONTROL GROUP (CGROUP)" , bpf , Martin KaFai Lau , Kumar Kartikeya Dwivedi Subject: Re: [PATCH v2 02/23] bpf: initial support for attaching struct ops to cgroups Message-ID: References: <20251027231727.472628-1-roman.gushchin@linux.dev> <20251027231727.472628-3-roman.gushchin@linux.dev> <87ldkte9pr.fsf@linux.dev> <871pmle5ng.fsf@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 7kdwi9en18nimziojjmmzhhr8abuyr6h X-Rspamd-Queue-Id: 92677180015 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1761778406-47938 X-HE-Meta: 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 7+MoeMot 9ttQENiufAWpSB1bERb2mNTtTnbhe1NzhHTbEiaOSY0b+KuuEiiQ379jppHe2c2aHE8aLy/wTR0/4q4a9MztNFYTkNdkUUomXj0UktkW1mkOS8preuQOw7Ph47DwsQ8me9QHAy+eOQNVgG/ETN8xlurfMfO6UFWnSD6gh5U6ed0BS5H+HzOKnCtOUHXIMYlFHvvyBd84JkGMqg9l8wW3ihaLZHhfTHbpUQwMiK9CC+Xl2GHz5KHhrhLnGZ39Jb73/7Yd6/rPWjJnfVtKmuwGXMILxt8y4heTmvwSK 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: Hello, On Wed, Oct 29, 2025 at 03:43:39PM -0700, Alexei Starovoitov wrote: ... > I think the general bpf philosophy that load and attach are two > separate steps. For struct-ops it's almost there, but not quite. > struct-ops shouldn't be an exception. > The bpf infra should be able to load a set of progs (aka struct-ops) > and attach it with a link to different entities. Like cgroups. > I think sched-ext should do that too. Even if there is no use case > today for the same sched-ext in two different cgroups. I'm not sure it's just that there's no use case. - How would recursion work with private stacks? Aren't those attached to each BPF program? - Wouldn't that also complicate attributing kfunc calls to the handle instance? If there is one struct_ops per cgroup, the oom kill kfunc can look that up and then verify that the struct_ops has authority over the target process. Multiple attachments can work too but that'd require iterating all attachments, right? Thanks. -- tejun