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(p200300cbc7074900ccb0e8742bce973b.dip0.t-ipconnect.de. [2003:cb:c707:4900:ccb0:e874:2bce:973b]) by smtp.gmail.com with ESMTPSA id q17-20020adfc511000000b001edc0a8a8b6sm62431wrf.0.2022.02.24.09.41.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 24 Feb 2022 09:41:21 -0800 (PST) Message-ID: <064ba776-e6c6-a430-7d74-0b691123e2a9@redhat.com> Date: Thu, 24 Feb 2022 18:41:20 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH RFC 05/13] mm/rmap: remove do_page_add_anon_rmap() Content-Language: en-US To: Linus Torvalds Cc: Linux Kernel Mailing List , Andrew Morton , Hugh Dickins , David Rientjes , Shakeel Butt , John Hubbard , Jason Gunthorpe , Mike Kravetz , Mike Rapoport , Yang Shi , "Kirill A . Shutemov" , Matthew Wilcox , Vlastimil Babka , Jann Horn , Michal Hocko , Nadav Amit , Rik van Riel , Roman Gushchin , Andrea Arcangeli , Peter Xu , Donald Dutile , Christoph Hellwig , Oleg Nesterov , Jan Kara , Liang Zhang , Pedro Gomes , Oded Gabbay , Linux-MM References: <20220224122614.94921-1-david@redhat.com> <20220224122614.94921-6-david@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24.02.22 18:29, Linus Torvalds wrote: > On Thu, Feb 24, 2022 at 4:29 AM David Hildenbrand wrote: >> >> ... and instead convert page_add_anon_rmap() to accept flags. > > Can you fix the comment above the RMAP_xyz definitions? That one still says > > /* bitflags for do_page_add_anon_rmap() */ > > that tnow no longer exists. Oh, yes sure. > > Also, while this kind of code isn't unusual, I think it's still confusing: > >> + page_add_anon_rmap(page, vma, addr, 0); > > because when reading that, at least I go "what does 0 mean? Is it a > page offset, or what?" Yes, I agree. > > It might be a good idea to simply add a > > #define RMAP_PAGE 0x00 > > or something like that, just to have the callers all make it obvious > that we're talking about that RMAP_xyz bits - even if some of them may > be default. > > (Then using an enum of a special type is something we do if we want to > add extra clarity or sparse testing, I don't think there are enough > users for that to make sense) > Actually, I thought about doing it similarly to what I did in page_alloc.c with fpi_t: typedef int __bitwise fpi_t; #define FPI_NONE ((__force fpi_t)0) I can do something similar here. -- Thanks, David / dhildenb