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Thu, 25 Jun 2026 02:04:17 -0700 (PDT) Received: from localhost.localdomain ([62.77.90.70]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-492660025a1sm29880925e9.0.2026.06.25.02.04.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Jun 2026 02:04:17 -0700 (PDT) Date: Thu, 25 Jun 2026 11:04:15 +0200 From: Michal =?utf-8?Q?Koutn=C3=BD?= To: Usama Arif Cc: Andrew Morton , david@kernel.org, linux-mm@kvack.org, hannes@cmpxchg.org, tj@kernel.org, shakeel.butt@linux.dev, roman.gushchin@linux.dev, liam@infradead.org, linux-kernel@vger.kernel.org, ljs@kernel.org, mhocko@suse.com, rppt@kernel.org, surenb@google.com, vbabka@kernel.org, kernel-team@meta.com Subject: Re: [PATCH 1/2] mm/vmpressure: skip tree=true accounting on cgroup v2 Message-ID: References: <20260606114158.3126210-1-usama.arif@linux.dev> <20260606114158.3126210-2-usama.arif@linux.dev> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="a3skirrhonq7dsal" Content-Disposition: inline In-Reply-To: <20260606114158.3126210-2-usama.arif@linux.dev> X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 748FB18000F X-Rspam-User: X-Stat-Signature: aforryjshprwtkr398zfxpjey1668eud X-HE-Tag: 1782378259-248643 X-HE-Meta: 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 G+TuOt0O JZzY50IW9BuoOJdvsBiofFsWam0KrVUvxvt5NLpy+ClTag2FbRdMuD/f28YKeX5+/PK2EVFnFoV0SA+yd6uOFrcpr9Kzwa6DFDZ28a8d1lUciCAengTMBuaU7DeCQ5C7wMxFSdMX2phWgRopw3+fHDYwVZ2IDMxWdQLPU8nkDmN+wa95liV6+PPBwMP1S+B4jlkj0MZLHgtbs0tg+JYesvZZpUwOq4d/cK5mCLIfXWaa6V1/VbAnP/ti3kI0NKcDp9pbIHv0a1Vj63fmgA2tKEnXpSiW9aABaLmfcu01zwq0T1oAWdWcCvphdt0SdfBsg/CA284FdSS6eIhI3LJJ4m32EDhlcrvdIYg9ERVBTmPWcBDr2ZMDQ7QGx5L4OM7cJNRT0i3O0MeCo+cEFnmtvI58Rcw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: --a3skirrhonq7dsal Content-Type: text/plain; protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH 1/2] mm/vmpressure: skip tree=true accounting on cgroup v2 MIME-Version: 1.0 Hello Usama. On Sat, Jun 06, 2026 at 04:41:33AM -0700, Usama Arif = wrote: > --- a/mm/vmpressure.c > +++ b/mm/vmpressure.c > @@ -246,11 +246,13 @@ void vmpressure(gfp_t gfp, int order, struct mem_cg= roup *memcg, bool tree, > return; > =20 > /* > - * The in-kernel users only care about the reclaim efficiency > - * for this @memcg rather than the whole subtree, and there > - * isn't and won't be any in-kernel user in a legacy cgroup. > + * Only two combinations have a consumer: > + * cgroup v2 + tree=3Dfalse -> in-kernel socket pressure > + * cgroup v1 + tree=3Dtrue -> userspace eventfds (memory.pressure_le= vel) > + * Skip the other two: nothing consumes the result. This is a good finding, I had some troubles convincing myself that the v2 has really only the memcg->socket_pressure. I think swapping the order of the patches would make it easier to comprehend. 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