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AJvYcCVJ2SFJQ6TklkroXMV5uxzJlYTy5bapIhuqcrHVFfp/IW8qtseJjirum+GhIwJKZ+Yi1TyEIDPhRw==@kvack.org X-Gm-Message-State: AOJu0YxugDybS5mGPEVgzne+ykWVG7u+K3jen4iwQb88tmWpUhgW3ZIe 0XMJ82soMjZoC4Zu3kg1lhWGmHg1iM6QSl5itjYLvgWRn5mNv5/887JeslxBpL8wqIjCUcneUjy DrIlAaci36M7ilSXDPhWuF+WIhAeh1ko= X-Gm-Gg: ASbGncsjxAohaJ1+sQgkTUTSxZSW07scikiBJlkrCEqARRBy+VgeOwLknZEIz5zI/bh Qe5bxV/XG8b58KSPfvU6a2vENmgfHnWAedhDWBfyEmq6PeOQnYbnjmypLb/87Arf/7cYZ2sdzFs 4ukea9YLhcslBsKqqo+unAqtCQHAMAnuc9JUwzIIgN20YPsMmp23J1EERdvAjKUpGSa1HSOY0qc OI9e0D5ND6SfKJ18zw7F3Y= X-Google-Smtp-Source: AGHT+IFHSx6hZlZJjgmXEk+skdNc6NPbwOFgHFtM3QRF1Gu2C6CnQMdkH8gTqKiWNIYivCF3n/UdO95dBbR/N21HyZ8= X-Received: by 2002:a17:907:7f0e:b0:b04:74d1:a57c with SMTP id a640c23a62f3a-b0474d1ae30mr464217866b.58.1757003218864; Thu, 04 Sep 2025 09:26:58 -0700 (PDT) MIME-Version: 1.0 References: <20250818170136.209169-2-roman.gushchin@linux.dev> <87ms7tldwo.fsf@linux.dev> <1f2711b1-d809-4063-804b-7b2a3c8d933e@linux.dev> <87wm6rwd4d.fsf@linux.dev> <87iki0n4lm.fsf@linux.dev> <87qzwnxgfr.fsf@linux.dev> <87h5xi1e6p.fsf@linux.dev> In-Reply-To: <87h5xi1e6p.fsf@linux.dev> From: Alexei Starovoitov Date: Thu, 4 Sep 2025 09:26:45 -0700 X-Gm-Features: Ac12FXwS8NBvLhK0GXWhEwLEcG0BPLfgFRE5uUtzqIDYNw67JkiC3-IZJcrgDd4 Message-ID: Subject: Re: [PATCH v1 01/14] mm: introduce bpf struct ops for OOM handling To: Roman Gushchin Cc: Tejun Heo , Martin KaFai Lau , Kumar Kartikeya Dwivedi , linux-mm , bpf , Suren Baghdasaryan , Johannes Weiner , Michal Hocko , David Rientjes , Matt Bobrowski , Song Liu , Alexei Starovoitov , Andrew Morton , LKML Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: D067814000E X-Stat-Signature: qw99g4573369ebmjxe3awdecw7neec19 X-Rspam-User: X-HE-Tag: 1757003220-614786 X-HE-Meta: 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 juztVYVg +k9Jb2BGiSWHHfeExSfgBBgDDJNCIZ0dHuCgVeeFVUQrocD7/NZng/VQInoIEJuTIzVj76Zv0z/oa4LEw43jeADxZ04zFSX1Md/L4lU4hGBvsw0Sc6oYPxxjVG2pMDDy+VIXmchcZizuHZ813NH9hcDymd7ehST3qlezwJVGxbMkSUmi5LbJCnzT2Rh8rmOb+NJvrSgINaqXPWWqmxMmX7i7DaXezAOJzKEZaua9nMvAzZDfYxWnaD57rHp0s4GjVY5+XTF274GGlZKflSxpc00Y8Zumd8Zy2LNZrP/Qu3z+6mwUmGHQQHl1DitthYzSEZEDzkf3SNSjihIW+TkalLR/09+QlGjMRjjTuIQQRuQizQbBN6SqlbnKtLXpJ4V5ImOhwqsc/oIaB15utW4A3VnFUyw4HbvhWdM08 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, Sep 4, 2025 at 7:32=E2=80=AFAM Roman Gushchin wrote: > > Tejun Heo writes: > > > Hello, > > > > On Wed, Sep 03, 2025 at 04:30:16PM -0700, Roman Gushchin wrote: > > ... > >> > - I'm passing in cgroup_id as an optional field in struct_ops and th= en in > >> > enable path, look up the matching cgroup, verify it can attach the= re and > >> > insert and update data structures accordingly: > >> > > >> > https://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git/t= ree/kernel/sched/ext.c?h=3Dscx-hier-prototype#n5280 > >> > >> Yeah, we discussed this option with Martin up in this thread. It doesn= 't > >> look as the best possible solution, but maybe the best we have at the = moment. > >> > >> Ideally, I want something like this: > >> > >> void test_oom(void) > >> { > >> struct test_oom *skel; > >> int err, cgroup_fd; > >> > >> cgroup_fd =3D open(...); > >> if (cgroup_fd < 0) > >> goto cleanup; > >> > >> skel =3D test_oom__open_and_load(); > >> if (!skel) > >> goto cleanup; > >> > >> err =3D test_oom__attach_cgroup(skel, cgroup_fd); > >> if (CHECK_FAIL(err)) > >> goto cleanup; > > > > Yeah, that'd look better but are there practical differences? The only = one I > > can think of is fs based permission check but that can be done separate= ly > > too. > > The practical difference is that a single struct ops can be attached > to multiple cgroups. +1 Attaching the same scheduler to multiple cgroups also sounds useful. I feel sched-ext should use cgroup_fd too and do scx_sub_enable() at attach time instead of load time. Then scx_sub_disable() can happen at link detach. Looks more flexible from user pov.