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Wed, 19 Aug 2026 14:14:44 -0400 (EDT) Date: Wed, 19 Aug 2026 19:14:42 +0100 From: Kiryl Shutsemau To: "David Hildenbrand (Arm)" , "Lorenzo Stoakes (ARM)" Cc: akpm@linux-foundation.org, nico.pache@linux.dev, baolin.wang@linux.alibaba.com, baohua@kernel.org, dev.jain@arm.com, hughd@google.com, lance.yang@linux.dev, liam@infradead.org, mhocko@suse.com, rppt@kernel.org, ryan.roberts@arm.com, shuah@kernel.org, surenb@google.com, usama.arif@linux.dev, vbabka@kernel.org, ziy@nvidia.com, usama.anjum@arm.com, agordeev@linux.ibm.com, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, jannh@google.com, willy@infradead.org, pfalcato@suse.de, rostedt@goodmis.org, mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [RFC PATCH 00/57] mm/collapse: rebuild collapse on migration primitives Message-ID: References: <20260816224609.308019-1-kirill@shutemov.name> <99138bda-55ba-4c58-9b79-b76e9daecdde@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <99138bda-55ba-4c58-9b79-b76e9daecdde@kernel.org> X-Rspam-User: X-Stat-Signature: esf8h4gnafpziwcex9hifd7kgb9guzbx X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 0BE3FA0008 X-HE-Tag: 1787163287-492701 X-HE-Meta: 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 vKrqM2fy pBMLXsRoPuQqi99dPC3z7nh5BvfVWcx2/neC/62cnEkR7EHNYQWpLbrhERl/xYCzn9FtQd7FwlO8Cc3ejMUQLzkm+xj+uBmVzjtmr2hjxTEaQ8kUZbDqw4jP048hdZT9uNVJ8FjZtM0VdUpxIevvIQ2gZy6JPy1HlnqECZqUyjpqqDiXXaVd9UZ3DQR1RRH5msvRR2iNxBf2p5WZ6YTuPO+7GvB7vOx1G7Ajg4qzJgYHtxpie8kZ9Htj/604soVaulDtkTTT8sgF4HbzFnt3u1+81pDyPCVAuhM9d8ESObHybpX/PuZoKh7PgObGm8S7O2LHGkVh+A8hZ17GabKQ/BBTEO26Agcf7yE8MxL2sXzn3blT7w9d/ssgdGF+i5+MvjoC1Lqs8OBAFt18wnAxwNOij/SZCbPyCUccEjZ2q4UiJl1LwFICScfnFOJWCcBRG6A4l Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Aug 18, 2026 at 04:15:27PM +0200, David Hildenbrand (Arm) wrote: > > David and I talked about this at LSF/MM. > > Ah, I missed the context in my other reply. Lorenzo already had some patches at > some point to split up mm/memory.c into better chunks that will also better help > our subcomponent maintenance model. Lorenzo, if you can dig those out, I would rather build on them than start over. Happy to do the legwork. > I think the challenge is how to handle huge_memory.c, because ideally, we'd not > have these stupid callbacks into huge_memory.c once we make PMDs just a > first-class citizen. Agreed on settling the target shape before moving anything. Splitting by operation answers most of huge_memory.c on its own, though. Its entry points are named after the operation they implement, and each has one destination: do_huge_pmd_anonymous_page(), do_huge_pmd_wp_page() and do_huge_pmd_numa_page() belong next to do_anonymous_page() in mm/fault.c. zap_huge_pmd() next to zap_pte_range(), copy_huge_pmd() next to copy_pte_range(). change_huge_pmd(), move_huge_pmd() and follow_huge_pmd() have their callers in the right file already -- mprotect.c, mremap.c, gup.c -- so they move to the caller. The callback goes away because the PMD case becomes a branch beside the PTE case instead of a call into another file. -- Kiryl Shutsemau / Kirill A. Shutemov