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Tue, 10 Jun 2025 03:53:14 -0700 (PDT) Received: from blackdock.suse.cz ([193.86.92.181]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a532461211sm11767637f8f.86.2025.06.10.03.53.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Jun 2025 03:53:13 -0700 (PDT) Date: Tue, 10 Jun 2025 12:53:11 +0200 From: Michal =?utf-8?Q?Koutn=C3=BD?= To: Shakeel Butt Cc: Tejun Heo , Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Vlastimil Babka , Alexei Starovoitov , Sebastian Andrzej Siewior , Harry Yoo , Yosry Ahmed , bpf@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: Re: [PATCH 0/3] cgroup: nmi safe css_rstat_updated Message-ID: References: <20250609225611.3967338-1-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="wzf4dlmbab6bfzcb" Content-Disposition: inline In-Reply-To: <20250609225611.3967338-1-shakeel.butt@linux.dev> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: DD68A8000B X-Stat-Signature: f3zbmffzqb11n4p8w8smtfh64duw1jkf X-Rspam-User: X-HE-Tag: 1749552795-88169 X-HE-Meta: U2FsdGVkX181R9jK78FEZDjZiV8d0L6waqnNG1YvaSqsa/8whNzJtbcc5zD6bZvUW+y38YmcIZedQiBT1e5WtNf3Mis7GrznyusH8uxFPmo0dK/BW72E9kp1b4Z0C1Tmpd547yhmkhYH7i2z0ifdMKpRAW8e33yH8zz9lzQ8P5Pt+1I2g5ubIY44yjrKjJuXxlG1k+zNnQPF1biNKY/kwHdtDRI/NHC/0HvMObBCeysJsqCsB7oCmoicJl5UxVeZoiDzr/3L2b7Asd4NLnvuUp/fe9uie2M4SrAJ7i04tB2EYULkY+JvVRpEqICSEr22H4svX5Tssbncb8eEsyo/VPMfEkMZm1Ie+o9Eld5FkLPnh5SNpH2natVCLYoQbxv7lQjyTvrKR4MjQI176PpKYsACr3i/nQL3gwppxI13QCmWvahGf9eSSuDjrjeYFKfUtQU3E6pceTHs8QqJwAzDr5It8vacPMnSvHeRBKQsdL7az+yt8fauOXeXzlYm6TYqQtdfbfhvIqg8Y7pPn7gT8yGW87xpsJMIZXb7mLXIphxGb0b+xPE4isM+JgR1g1kY+Z+n8ywL3eAhefhkTq1qJdli3qj+PK+tEJgv4OMTOxU1RRM+eV56ocpxobs8tTpRPg3CS0CSDkYHpSHUy0/9wGVcX4QOCHIcsAHLw9bi+hp9fFsvR1hwiRHZ/AfP81/CXGAUPHyZpkrdu0QPyF0784acPZpil0baa2hghO9PTstpieVUMo5xK13QasvaKcqiDWomFvl63lVcAEJlGERrHk1pUfAfzusbvmqZqAoRW+8fnAnptDlIwnTQWGPfPOOMUVuWvtU9G7HleTUYC5DiWOjWF2R8oiN5uS8ASrYJSOs58DvT3QMGXYEIXtW6suSAngV5b/S8uIRQ3zGXzH6imlayri9R1BibMdlPtfogsl/xxO9yDP316i4CHk8MljElaYzG+9S+DUmgUuIgLfD JXs++ccU fCD5QDAY4COwaI2uivFgzdZCz/gn/gsEZo0dFfEmNbEoqBQcPb+dJNcECNAGFqyuqglsHX6WXRP7ycOVUNUa5e/iTtWfgiUyiaaDQaamJtjeBlXMnUC9gs8MO+WWCJ8axeDga 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: --wzf4dlmbab6bfzcb Content-Type: text/plain; protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH 0/3] cgroup: nmi safe css_rstat_updated MIME-Version: 1.0 On Mon, Jun 09, 2025 at 03:56:08PM -0700, Shakeel Butt wrote: > BPF programs can run in nmi context and may trigger memcg charged memory > allocation in such context. Recently linux added support to nmi safe > page allocation along with memcg charging of such allocations. However > the kmalloc/slab support and corresponding memcg charging is still > lacking, >=20 > To provide nmi safe support for memcg charging for kmalloc/slab > allocations, we need nmi safe memcg stats and for that we need nmi safe > css_rstat_updated() which adds the given cgroup state whose stats are > updated into the per-cpu per-ss update tree. This series took the aim to > make css_rstat_updated() nmi safe. memcg charging relies on page counters and per-cpu stocks. css_rstat_updated() is "only" for statistics (which has admiteddly some in-kernel consumers but those are already affected by batching and flushing errors). Have I missed some updates that make css_rstat_updated() calls critical for memcg charging? I'd find it useful to explain this aspect more in the cover letter. Thanks, Michal --wzf4dlmbab6bfzcb Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRCE24Fn/AcRjnLivR+PQLnlNv4CAUCaEgOigAKCRB+PQLnlNv4 CCyuAQDQlmXIUda/Zc5IPRULm+/1VBWxj2JIW9BfHZ2Iz/EeBwEAyJpChyqsQ9vH QuSlPcSnjJUVEQ52+dsLL5MHYOTnXQQ= =qmK3 -----END PGP SIGNATURE----- --wzf4dlmbab6bfzcb--