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Shutemov" Cc: Matthew Wilcox , akpm@linux-foundation.org, alex.shi@linux.alibaba.com, vbabka@suse.cz, guro@fb.com, hannes@cmpxchg.org, hughd@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, vdavydov.dev@gmail.com Subject: Re: [PATCH v2 3/3] mm: use PF_ONLY_HEAD for PG_active and PG_unevictable Message-ID: References: <20210224084807.2179942-1-yuzhao@google.com> <20210226091718.2927291-1-yuzhao@google.com> <20210226091718.2927291-4-yuzhao@google.com> <20210226121314.GB2723601@casper.infradead.org> <20210301115007.mgw5vthgjoibnjf4@box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210301115007.mgw5vthgjoibnjf4@box> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: B0B2CE000460 X-Stat-Signature: qasq6jhgxue7bdkgeba69k9gqh9hbcjt Received-SPF: none (google.com>: No applicable sender policy available) receiver=imf05; identity=mailfrom; envelope-from=""; helo=mail-io1-f52.google.com; client-ip=209.85.166.52 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614628743-327439 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, Mar 01, 2021 at 02:50:07PM +0300, Kirill A. Shutemov wrote: > On Fri, Feb 26, 2021 at 12:13:14PM +0000, Matthew Wilcox wrote: > > On Fri, Feb 26, 2021 at 02:17:18AM -0700, Yu Zhao wrote: > > > All places but one test, set or clear PG_active and PG_unevictable on > > > small or head pages. Use compound_head() explicitly for that singleton > > > so the rest can rid of redundant compound_head(). > > > > How do you know it's only one place? I really wish you'd work with me > > on folios. They make the compiler prove that it's not a tail page. > > +1 to this. > > The problem with compound_head() is systemic and ad-hoc solution to few > page flags will only complicate the picture. Well, I call it an incremental improvement, and how exactly does it complicate the picture? I see your point: you prefer a complete replacement. But my point is not about the preference; it's about presenting an option: I'm not saying we have to go with this series; I'm saying if you don't want to wait, here is something quick but not perfect.