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Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1tsl3e-00000000BHX-09mr; Thu, 13 Mar 2025 16:05:18 +0000 Date: Thu, 13 Mar 2025 16:05:17 +0000 From: Matthew Wilcox To: Johannes Weiner Cc: linux-mm@kvack.org, Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Zi Yan , David Hildenbrand Subject: Re: [PATCH 3/5] mm: Remove references to folio in split_page_memcg() Message-ID: References: <20250313145856.4118428-1-willy@infradead.org> <20250313145856.4118428-4-willy@infradead.org> <20250313160114.GD1252169@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250313160114.GD1252169@cmpxchg.org> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 1F587A0034 X-Stat-Signature: 6ppss4yfdkxat3r558sszipbu7todwa8 X-HE-Tag: 1741881919-332416 X-HE-Meta: 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 9fD5fP1C 1WSHNIdMDqp44zR/fNTsn/6eEbS19oXKJ18jtC2kPZlbP0j91mjq9T0RzvleYV0CnMa279g00Zg4tgRm5xG8jce/2thowmeXoCkr1xgx5t19aqolPGAH4J1mwXoowXl8WTDz/FeH9Lx26OEy11p4xlYBbhv3KqtPDJMoLodg94NNdQF+rbI06U9YJ0SZpnqR5todJ1pJZ9y3sRpLP80UTxN7aymXq6ufcrlquuv6gUzS0cnNJRrlMU50w1dUQHuQeDKuhVPpasKDYohtDmWrM2WBkcw== 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: On Thu, Mar 13, 2025 at 12:01:14PM -0400, Johannes Weiner wrote: > On Thu, Mar 13, 2025 at 02:58:52PM +0000, Matthew Wilcox (Oracle) wrote: > > @@ -2697,6 +2697,23 @@ static int obj_cgroup_charge_pages(struct obj_cgroup *objcg, gfp_t gfp, > > return ret; > > } > > > > +static struct obj_cgroup *page_objcg(const struct page *first) > > "first" is odd for that function. "page"? I'm trying to indicate that it's the first page of the allocation (head page is wrong because it's not a compound allocation). But I can just call it 'page'. We do that in enough places ... > > @@ -3091,16 +3107,16 @@ void __memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, > > */ > > void split_page_memcg(struct page *first, unsigned order) > > { > > - struct folio *folio = page_folio(first); > > + struct obj_cgroup *objcg = page_objcg(first); > > unsigned int i, nr = 1 << order; > > > > - if (mem_cgroup_disabled() || !folio_memcg_charged(folio)) > > + if (!objcg) > > return; > > mem_cgroup_disabled() is a jump label, so a bit cheaper than the > branch. Can you keep that and do page_objcg() after it? Sure, I can do that. I didn't think it was really worthwhile given how common splitting is (very rare) and we've already incurred the function call overhead.