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Mercier" Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , android-mm@google.com, Minchan Kim , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm: memcg: Don't periodically flush stats when memcg is disabled Message-ID: References: <20240126211927.1171338-1-tjmercier@google.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="wxxx3wtjfattjixo" Content-Disposition: inline In-Reply-To: <20240126211927.1171338-1-tjmercier@google.com> X-Rspam-User: X-Stat-Signature: x6zhos7cunwypgdt3fsbuepwbyy3waqz X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 7FB7C1C0017 X-HE-Tag: 1706797575-240442 X-HE-Meta: U2FsdGVkX1/QdYjoFBXIOpkawJ/TqIrAgs4jS6Huj6+fGppMIORdhlwgjbb/a9FjjND6bIEIFKGzYtMYYYVhgD4hPYWWCqocNGaQJHiiqvCmDLZXPaHC2vYFc4V5rQJJxTR9Rvpie5arY6dd3uIQsxhz8SLMyGIfg/kj/YqzlHYNpELOlx8Hw6WcyD8ozHAqjMACmMiqSsTcD1Lh+rfTJ/ytbhZGxcbzaFmgWrabNCdGLVqDVFOq9pc1aqa4FHCLGAq0CTJlPfhuPrI5C/ztEEZj/QIQxm6DjlF4Db5o6IziaKJd9bSzaMbt8HrV4b9NMtsDfNLxKjkF66LLwvNgNasTI3/sfiIkA8QeJKEtfcrl3LHHBp7EeyiIb/GS1RIXPdqM4wH2X7DHTNdTGz2PXJ6EDFDeyJ9++zreQFCVYyuCC3bdgpSxs+3UNMPK8q0A+C4DXipncKfAaK1Mg3lVBlViY9q++GiwHKkGRQVlAHxj3P8CoeqUNM88y3OkC2VFf6epCEr/F88kwxo/NLhMft9ZpWj2Q9d6kMCyo8UwnS4xe4v0r9kd4EsC8r6a/8OHkkFZinXEGp3thOWx7dc/HrABRzi2GnQso8+nOSk134stgkLFBGVG4Vt89hUFAAxYqh6MRcF3UpVS3N9m56uVrRFpIKDJGMGlobHrQxxdPpqyoowkD3+THFjcrGIhu5BCJxCCHb83QZBWoDHL87y+Ck1hr8i0YcprPk30hPaKgIc+hjAkhcTAPMRTCVrRt1nX7L9/fHafGkoHtgche2ZuZQakbLsZH+qnZYaJMiREDcaohBfbSz8SDeAthP+8W0B5L6wfMj4IQxCfG4KZBJTPoL4/smvXvZHzd28Z7143f8FqceprL9bipTjq7D3ETwXHYiU9pNbdzidwa7UyOqxLe9ZLNZI0smW30xnIsDTsW9ev2pszdt9x+KW9BKNGM1+K3JdcKGcz997c9+8ocVk aktEVbRh y1Qns1l+IyXU0r4S2VWxsayWnCk2Rz6UgmwzjZCF0y3RYxxa6toR1tdqZPiQpxwuWWb9ImcOEv4NSNlY1uWGEVg3GhlJChcOJ90h5nSoUFsB0hyuzHu6pTBHIojpiKXs3vPLg71haIA61L3ize553uSgCYsY9yDTaqUopapXIj7TF+gAutVfwkrFM54rtj8RJ5XGHk3gI3zLDkK90obaFtg+EDvyZ3+12wZlwvMf//o1z9sPDyjJIMMP5CEcTYgTOMeyb72DCp2U9ctE0a5XUF3tfp4px/hIrFWMIetR0MZV1uT4= 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: --wxxx3wtjfattjixo Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Jan 26, 2024 at 09:19:25PM +0000, "T.J. Mercier" wrote: > The root memcg is onlined even when memcg is disabled. When it's onlined > a 2 second periodic stat flush is started, but no stat flushing is > required when memcg is disabled because there can be no child memcgs. > Most calls to flush memcg stats are avoided when memcg is disabled as a > result of the mem_cgroup_disabled check added in 7d7ef0a4686a > ("mm: memcg: restore subtree stats flushing"), but the periodic flushing > started in mem_cgroup_css_online is not. Skip it. Have you tried --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -6099,6 +6099,9 @@ int __init cgroup_init(void) cgroup_unlock(); for_each_subsys(ss, ssid) { + if (!cgroup_ssid_enabled(ssid)) + continue; + if (ss->early_init) { struct cgroup_subsys_state *css = init_css_set.subsys[ss->id]; @@ -6118,9 +6121,6 @@ int __init cgroup_init(void) * disabled flag and cftype registration needs kmalloc, * both of which aren't available during early_init. */ - if (!cgroup_ssid_enabled(ssid)) - continue; - if (cgroup1_ssid_disabled(ssid)) pr_info("Disabling %s control group subsystem in v1 mounts\n", ss->legacy_name); ? I'm asking about a try because I'm not sure whether this does not blow up due to something missing. But I think disabled controllers would not need to be (root-)onlined at all. Thanks, Michal --wxxx3wtjfattjixo Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQQpEWyjXuwGT2dDBqAGvrMr/1gcjgUCZbuqAgAKCRAGvrMr/1gc jrpxAQDyZRXNtpLF1OlwunwH7s4cGq9S3p4xavcyCbU73SNKTAEA8OT63KKFtzzZ uYtGruEFhY4GBP430nCIMahipGl+WAc= =gZrw -----END PGP SIGNATURE----- --wxxx3wtjfattjixo--