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t=1785739117; bh=pW7Og0qPxzuL6m6WFYbBCbPX3qINoEYxL05Tp/X8L/M=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=OW+F7WyOx6cgS/hdYImcNWyD/FWqnkb/95WncioGVZSrVnsUcNUvp92NfVhJ3mYoT NVCBG4M5JTgSZ6cBMNXMo8GzMtXYoXDo5FPb0iGBya4dkVax7s/1NM1vS2jAcXx8oa w9fv/ZwElNMPHpK3zjsi95HROpgQDJGKazTOGhKIAR1ZAYNbvid5sgaBMAa4Vc7Y3E c//cStuusvoomu2ZXRFS2Yf+xT1zDCawUD85QNiZnrMLeSWXhD6MoUsbnOls8eKL7C Mv39sE6fO10OJfecIzohY6qmDcbUlE4MMLvqytBlOjWE/o1rIJgKUVqrhXY2nWG600 4x8LLeg8D2MwA== Date: Mon, 3 Aug 2026 09:38:31 +0300 From: Mike Rapoport To: Muchun Song Cc: Muchun Song , Andrew Morton , Oscar Salvador , David Hildenbrand , Vlastimil Babka , Lorenzo Stoakes , Michal Hocko , David Laight , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 03/17] mm/mm_init: skip initializing shared vmemmap tail pages Message-ID: References: <20260720093127.540540-1-songmuchun@bytedance.com> <20260720093127.540540-4-songmuchun@bytedance.com> <5005C7D3-B3ED-4C62-B611-8465D2BC69FD@linux.dev> <178540851830.2154539.6359871825839331816.b4-reply@b4> <3FCC8989-95DB-450F-95C3-183787DF4D08@linux.dev> <89878C33-9BCD-4FD7-92A0-884CF682CBF3@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <89878C33-9BCD-4FD7-92A0-884CF682CBF3@linux.dev> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 7598C20006 X-Stat-Signature: 6659zzuzjozktfa13zyekii95zhdppsh X-Rspam-User: X-HE-Tag: 1785739118-767142 X-HE-Meta: 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 pLVJh/1G EgUOu6gvljObxirfRFEST61Z4kfFgFUAZA2+RPfxvdJ8oWJVOweqQeLbChAy6UDjFLiDAQ3RRbe4wcYyJNPE0k9P1sg0HKRjZyu/ntl9WFnbgYspt/am98BVWe49mm5gwL80foCPTDNaI7bbr6IM84jWrykIeHMnwFnRf5j1O9d1MKQQTapdbqB1e16etA9JqebOVOcrj/YGLi/BQZ1yEPV3Q3zljZBbWggVhz03QuPrT5aLK+i3ft7uPGEo8d1x0u26z3yFhMiOTLmf0pdM2VYH0fmsDnTj+xzo+VETeLaJnt+r8M96LRdnxy6Kp6x1GdbUT8YrpWdvevnk4zP3NtnhTvsTpjlq3iueYVsYiriex/oNdtY4MAU37/A81sKCoELjVBYLKbUpF9h11KoxU/7zmfndIlcjq4ikspKy8W3W93S4= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jul 31, 2026 at 10:13:43AM +0800, Muchun Song wrote: > > On Jul 30, 2026, at 22:32, Mike Rapoport wrote: > >> > >> Since we also use __pfn_to_section in the patch 14 in this series for > >> !SPARSEMEM, we need to make corresponding adjustments—specifically, by using > >> pfn_to_section_order to determine whether the vmemmap of a given section is > >> optimizable. This new helper will be called from several places, so I'm afraid > >> its introduction is unavoidable. > > > > Do you mean that section_vmemmap_optimizable() will receive pfn as a > > parameter and use pfn_to_section_order() internally? > > I was originally planning to go with the this approach, but now I've come across > something that feels a bit unusual to me: a function whose name starts with section > takes a pfn as its argument instead of a mem_section. > > So I started thinking about an alternative. How about we keep section_vmemmap_optimizable() > as it is, but introduce a new helper like this: > > static inline bool order_vmemmap_optimizable(unsigned int order) > { > return order >= OPTIMIZABLE_FOLIO_MIN_ORDER; > } Maybe name it vmemmap_optimizable_order() so it'll belong to vmemmap namespace, order_ can be really a lot of things. I think it makes sense. Let's see how it fits in the end in the new version :) -- Sincerely yours, Mike.