linux-kernel - Re: [PATCH v2 14/23] mm: allow specifying custom oom constraint for BPF triggers

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Message-ID: <aRGw6sSyoJiyXb8i@tiehlicka>
Date: Mon, 10 Nov 2025 10:31:22 +0100
From: Michal Hocko <mhocko@...e.com>
To: Roman Gushchin <roman.gushchin@...ux.dev>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org,
	Alexei Starovoitov <ast@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Shakeel Butt <shakeel.butt@...ux.dev>,
	Johannes Weiner <hannes@...xchg.org>,
	Andrii Nakryiko <andrii@...nel.org>,
	JP Kobryn <inwardvessel@...il.com>, linux-mm@...ck.org,
	cgroups@...r.kernel.org, bpf@...r.kernel.org,
	Martin KaFai Lau <martin.lau@...nel.org>,
	Song Liu <song@...nel.org>,
	Kumar Kartikeya Dwivedi <memxor@...il.com>,
	Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH v2 14/23] mm: allow specifying custom oom constraint for
 BPF triggers

On Mon 27-10-25 16:21:57, Roman Gushchin wrote:
> Currently there is a hard-coded list of possible oom constraints:
> NONE, CPUSET, MEMORY_POLICY & MEMCG. Add a new one: CONSTRAINT_BPF.
> Also, add an ability to specify a custom constraint name
> when calling bpf_out_of_memory(). If an empty string is passed
> as an argument, CONSTRAINT_BPF is displayed.

Constrain is meant to define the scope of the oom handler but to me it
seems like you want to specify the oom handler and (ab)using scope for
that. In other words it still makes sense to distinguesh memcg, global,
mempolicy wide OOMs with global vs. bpf handler, right?

-- 
Michal Hocko
SUSE Labs