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Tue, 22 Sep 2026 06:19:11 +0000 X-Mizu-Trace-ID: 20087f601faff867 X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3864.700.51.1.1\)) Subject: Re: [PATCH 2/2] mm/memcg: migrate per-node hugetlb lruvec stat together with hugetlb folio From: Muchun Song In-Reply-To: <20260921-for-hugetlb_state-v1-2-8a6eec92661f@kylinos.cn> Date: Tue, 22 Sep 2026 14:18:51 +0800 Cc: Oscar Salvador , David Hildenbrand , Andrew Morton , Shakeel Butt , Michal Hocko , Roman Gushchin , Nhat Pham , Chris Down , Johannes Weiner , Michal Hocko , Joshua Hahn , linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Hongfu Li , stable@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <20260921-for-hugetlb_state-v1-0-8a6eec92661f@kylinos.cn> <20260921-for-hugetlb_state-v1-2-8a6eec92661f@kylinos.cn> To: Hongfu Li X-Mailer: Apple Mail (2.3864.700.51.1.1) X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 87E1B180002 X-Stat-Signature: u7g4yoahuwo5nuxnjdh433efpdugrju4 X-Rspam-User: X-HE-Tag: 1790057953-670875 X-HE-Meta: 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 Vwh/DdXX 9MzwWkdAng2nHBgE7grA/H5O4y60C4g5lJKW4X2XIkhyEFDLM+aPniNu4XFA3uQYqGHf/IODNoNVk5xqelk6rfFlgksmZCEo4ENbQrNpsuVaEiuLW37+QtP6dtDrfH9Yz/1I37xehAy7nUnYwXV67qzsiAyXBeZMxeh9TYqe9Qic/0RkM/ePMyyilWMNN0G3Pz3LSxO/tVD50/ynPfphPAuZW1k1jaCGarMPR7bx0cow6a0K5QdcYndoVzOOWkqRTvYfuCIANy8WisZf6knflMKYkmRQWD2hNuFIDH0CtW8Bu0O+5qUfbPiI+ShGn/YQdJJNHqUvDHt30Dl5IeWsUzJUOK5Wfb6akW0wV2vDlHXLnqaQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > On Sep 21, 2026, at 17:12, Hongfu Li wrote: >=20 > From: Hongfu Li >=20 > memory.numa_stat exposes per-node hugetlb counters from per-node = lruvec > stats. These stats are accounted against folio_nid(): incremented on > the folio's node when handed to a user, decremented when the folio is > returned to the pool. >=20 > During hugetlb folio migration, mem_cgroup_migrate() moves the charge > to the new folio and drops the memcg data of the old one, so the free > of the old folio right after the migration skips the memcg per-node > lruvec decrement. The hugetlb count stays attributed to the old node > for the rest of the life of the charge, while the target folio gets no > increment on the new node; its later free decrements a counter that > was never incremented. >=20 > Migrate the per-node lruvec accounting alongside migration. Global > memcg totals remain balanced because they track resource consumption, > not node placement. >=20 > Fixes: 05d4532b60e3 ("memcg/hugetlb: add hugeTLB counters to memcg") > Cc: stable@vger.kernel.org > Signed-off-by: Hongfu Li > --- > mm/memcontrol.c | 31 +++++++++++++++++++++++++++++++ > 1 file changed, 31 insertions(+) >=20 > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 1460cba53588..9c96ebd5436f 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -5598,6 +5598,34 @@ void mem_cgroup_replace_folio(struct folio = *old, struct folio *new) > rcu_read_unlock(); > } >=20 > +#ifdef CONFIG_HUGETLB_PAGE > +static void move_hugetlb_lruvec_stat(struct obj_cgroup *objcg, Actually, we don't need this objcg parameter since we could get it from = folio. And I'd like to move this function to hugetlb.c. > + struct folio *old, struct folio = *new) > +{ > + long nr_pages =3D folio_nr_pages(old); > + struct mem_cgroup *memcg; > + int old_nid =3D folio_nid(old); > + int new_nid =3D folio_nid(new); > + > + if (old_nid =3D=3D new_nid) > + return; > + > + rcu_read_lock(); Please use guard(rcu)() to simplify the code a little. Thanks. > + memcg =3D obj_cgroup_memcg(objcg); > + mod_memcg_lruvec_state(mem_cgroup_lruvec(memcg, = NODE_DATA(old_nid)), > + NR_HUGETLB, -nr_pages); > + mod_memcg_lruvec_state(mem_cgroup_lruvec(memcg, = NODE_DATA(new_nid)), > + NR_HUGETLB, nr_pages); > + rcu_read_unlock(); > +} > +#else /* CONFIG_HUGETLB_PAGE */ > +static inline void move_hugetlb_lruvec_stat(struct obj_cgroup *objcg, > + struct folio *old, > + struct folio *new) > +{ > +} > +#endif /* CONFIG_HUGETLB_PAGE */ > + > /** > * mem_cgroup_migrate - Transfer the memcg data from the old to the = new folio. > * @old: Currently circulating folio. > @@ -5635,6 +5663,9 @@ void mem_cgroup_migrate(struct folio *old, = struct folio *new) >=20 > new_objcg =3D get_migration_objcg(old, new); >=20 > + if (folio_test_hugetlb(old)) > + move_hugetlb_lruvec_stat(new_objcg, old, new); > + > /* > * @old was charged through a non-root objcg, so its charge is in the > * page counters. If the re-derivation walked up to the root objcg - >=20 > --=20 > 2.54.0 >=20