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Mon, 02 Feb 2026 09:30:34 -0800 (PST) MIME-Version: 1.0 References: <20260127024421.494929-1-roman.gushchin@linux.dev> <20260127024421.494929-11-roman.gushchin@linux.dev> In-Reply-To: From: Alexei Starovoitov Date: Mon, 2 Feb 2026 09:30:23 -0800 X-Gm-Features: AZwV_QhcSxBOzKmir8YnJuWGB8mK-DNJ9JY3HMjEXt_lprjX8IPmESFpgJWBbyM Message-ID: Subject: Re: [PATCH bpf-next v3 10/17] mm: introduce bpf_task_is_oom_victim() kfunc To: Matt Bobrowski Cc: Roman Gushchin , bpf , Michal Hocko , Alexei Starovoitov , Shakeel Butt , JP Kobryn , LKML , linux-mm , Suren Baghdasaryan , Johannes Weiner , Andrew Morton Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: A5368A000E X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: ob53b11493x13msr1hfwacdrnfkitsqy X-HE-Tag: 1770053436-626730 X-HE-Meta: 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 1RHM6NtC 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 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 Sun, Feb 1, 2026 at 9:39=E2=80=AFPM Matt Bobrowski wrote: > > On Mon, Jan 26, 2026 at 06:44:13PM -0800, Roman Gushchin wrote: > > Export tsk_is_oom_victim() helper as a BPF kfunc. > > It's very useful to avoid redundant oom kills. > > > > Signed-off-by: Roman Gushchin > > Suggested-by: Michal Hocko > > --- > > mm/oom_kill.c | 14 ++++++++++++++ > > 1 file changed, 14 insertions(+) > > > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > > index 8f63a370b8f5..53f9f9674658 100644 > > --- a/mm/oom_kill.c > > +++ b/mm/oom_kill.c > > @@ -1381,10 +1381,24 @@ __bpf_kfunc int bpf_out_of_memory(struct mem_cg= roup *memcg__nullable, > > return ret; > > } > > > > +/** > > + * bpf_task_is_oom_victim - Check if the task has been marked as an OO= M victim > > + * @task: task to check > > + * > > + * Returns true if the task has been previously selected by the OOM ki= ller > > + * to be killed. It's expected that the task will be destroyed soon an= d some > > + * memory will be freed, so maybe no additional actions required. > > + */ > > +__bpf_kfunc bool bpf_task_is_oom_victim(struct task_struct *task) > > +{ > > + return tsk_is_oom_victim(task); > > +} > > Why not just do a direct memory read (i.e., task->signal->oom_mm) > within the BPF program? I'm not quite convinced that a BPF kfunc > wrapper for something like tsk_is_oom_victim() is warranted as you can > literally achieve the same semantics without one. +1 there is no need for this kfunc.