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Mon, 29 Jun 2026 07:29:38 -0700 (PDT) Date: Mon, 29 Jun 2026 16:29:37 +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 v2 2/2] mm/vmpressure: split v1 userspace eventfd code into vmpressure-v1.c Message-ID: References: <20260629130042.2649505-1-usama.arif@linux.dev> <20260629130042.2649505-3-usama.arif@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="3at7itnpamxnmliu" Content-Disposition: inline In-Reply-To: --3at7itnpamxnmliu Content-Type: text/plain; protected-headers=v1; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH v2 2/2] mm/vmpressure: split v1 userspace eventfd code into vmpressure-v1.c MIME-Version: 1.0 On Mon, Jun 29, 2026 at 02:55:57PM +0100, Usama Arif = wrote: > On 29/06/2026 14:34, Michal Koutn=FD wrote: > > On Mon, Jun 29, 2026 at 05:59:37AM -0700, Usama Arif wrote: > >> This split is the first step toward eventually making vmpressure > >> CONFIG_MEMCG_V1 only. The v2 in-kernel socket pressure path > >> (tree=3Dfalse) cannot be removed today immediately: PSI is not an > >> exact replacement for vmpressure, and switching networking socket-buff= er > >> back-off to PSI > >=20 > > (Here I understand PSI is a different and differntly scope metric) but > > what does it mean when you write that tree=3Dfalse cannot be removed but > > the other patch bails out from vmpressure() (i.e. nothing is updated > > anyway)? > So the first patch bails out for cgroup v2 for tree =3D true only. > For tree =3D false, it doesn't bail out, and is still used for networking > socket-buffer back-off. I think that is a whole another scope of work > switching to PSI. Hope that makes sense? I've mixed mutliple things together, sorry. I wanted to actually ask about your response: | I realized when trying to swap the order that the splitting off v1 | commit will end up doing more that what I think it should do (just | splitting off v1 specific code), as the tree =3D true code will not get | compiled in at all for cgroup v2, and it then ends up changing more | behaviour. tree=3Dtrue won't get compiled but v2 doesn't care about it, so the effect of patch 2/2 should still be same (regardless whether it comes 1st or 2nd). Do you refer to the invocation of vmpressure_v1_account_tree() that is affected by this? Thanks, Michal --3at7itnpamxnmliu Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iJEEABYKADkWIQRCE24Fn/AcRjnLivR+PQLnlNv4CAUCakKBRBsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMiwyLDIACgkQfj0C55Tb+AjvmwEA4HemtO453cJ3O/cposVq krP9NyHjDTo6qEo6eD7jB80BAJyadNi2Vw4GfahS0jf6sOLJoNRwifr+4X5GH+L1 JjcD =aqwx -----END PGP SIGNATURE----- --3at7itnpamxnmliu--