linux-kernel - Re: [PATCH 0/5] add STATIC_PMD_ZERO

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Message-ID: <30a3048f-efbe-4999-a051-d48056bafe0b@intel.com>
Date: Thu, 12 Jun 2025 06:50:07 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Pankaj Raghav <p.raghav@...sung.com>,
 Suren Baghdasaryan <surenb@...gle.com>, Ryan Roberts <ryan.roberts@....com>,
 Mike Rapoport <rppt@...nel.org>, Michal Hocko <mhocko@...e.com>,
 Thomas Gleixner <tglx@...utronix.de>, Nico Pache <npache@...hat.com>,
 Dev Jain <dev.jain@....com>, Baolin Wang <baolin.wang@...ux.alibaba.com>,
 Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...hat.com>,
 "H . Peter Anvin" <hpa@...or.com>, Vlastimil Babka <vbabka@...e.cz>,
 Zi Yan <ziy@...dia.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
 David Hildenbrand <david@...hat.com>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 "Liam R . Howlett" <Liam.Howlett@...cle.com>, Jens Axboe <axboe@...nel.dk>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, willy@...radead.org,
 x86@...nel.org, linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
 "Darrick J . Wong" <djwong@...nel.org>, mcgrof@...nel.org,
 gost.dev@...sung.com, kernel@...kajraghav.com, hch@....de
Subject: Re: [PATCH 0/5] add STATIC_PMD_ZERO_PAGE config option

On 6/12/25 03:50, Pankaj Raghav wrote:
> But to use huge_zero_folio, we need to pass a mm struct and the
> put_folio needs to be called in the destructor. This makes sense for
> systems that have memory constraints but for bigger servers, it does not
> matter if the PMD size is reasonable (like in x86).

So, what's the problem with calling a destructor?

In your last patch, surely bio_add_folio() can put the page/folio when
it's done. Is the real problem that you don't want to call zero page
specific code at bio teardown?