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[209.85.208.178]) by smtp.gmail.com with ESMTPSA id w6sm1431944lfu.44.2021.12.20.11.15.41 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Dec 2021 11:15:41 -0800 (PST) Received: by mail-lj1-f178.google.com with SMTP id z8so17569877ljz.9 for ; Mon, 20 Dec 2021 11:15:41 -0800 (PST) X-Received: by 2002:a5d:6211:: with SMTP id y17mr2491550wru.97.1640027730630; Mon, 20 Dec 2021 11:15:30 -0800 (PST) MIME-Version: 1.0 References: <20211218184233.GB1432915@nvidia.com> <5CA1D89F-9DDB-4F91-8929-FE29BB79A653@vmware.com> <4D97206A-3B32-4818-9980-8F24BC57E289@vmware.com> <5A7D771C-FF95-465E-95F6-CD249FE28381@vmware.com> In-Reply-To: From: Linus Torvalds Date: Mon, 20 Dec 2021 11:15:14 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v1 06/11] mm: support GUP-triggered unsharing via FAULT_FLAG_UNSHARE (!hugetlb) To: Matthew Wilcox Cc: David Hildenbrand , Nadav Amit , Jason Gunthorpe , Linux Kernel Mailing List , Andrew Morton , Hugh Dickins , David Rientjes , Shakeel Butt , John Hubbard , Mike Kravetz , Mike Rapoport , Yang Shi , "Kirill A . Shutemov" , Vlastimil Babka , Jann Horn , Michal Hocko , Rik van Riel , Roman Gushchin , Andrea Arcangeli , Peter Xu , Donald Dutile , Christoph Hellwig , Oleg Nesterov , Jan Kara , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , "open list:DOCUMENTATION" Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 447F31C0026 X-Stat-Signature: apgw6mscyacae31nk4qq7kskymwcuoaz Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=VFuYtAog; dmarc=none; spf=pass (imf20.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.208.176 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org X-HE-Tag: 1640027739-385648 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: On Mon, Dec 20, 2021 at 10:37 AM Matthew Wilcox wrote: > > This might be a step in the right direction? > > Subject: [PATCH] mm: reuse_swap_page() no longer needs to return map_swapcount Well, that patch seems to be a no-op removal of dead code, so absolutely yes. That said, I think it would be good to split it up. I looked at that patch and went "is that really a no-op" to the point of recreating it. I think it would be good to make it multiple patches that are each individally trivial. IOW, start with (1) remove second argument to reuse_swap_page() that is always NULL, without making any other changes (2) that now made 'total_mapcount' unused in reuse_swap_page(), remove it as an argument from page_trans_huge_map_swapcount() (3) that now made 'total_mapcount' unused in page_trans_huge_mapcount(), remove it as an argument there too. because as it stands, that patch of yours looks like it is changing a lot of things, and I think it would be clearer to remove one thign at a time as it becomes obviously not used. Hmm? Linus