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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id l31-20020a81ad5f000000b00545a0818483sm2636333ywk.19.2023.04.16.11.11.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 16 Apr 2023 11:11:58 -0700 (PDT) Date: Sun, 16 Apr 2023 11:11:49 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Andrew Morton cc: Zi Yan , Zi Yan , "Matthew Wilcox (Oracle)" , Yang Shi , Yu Zhao , linux-mm@kvack.org, "Kirill A . Shutemov" , Ryan Roberts , =?ISO-8859-15?Q?Michal_Koutn=FD?= , Roman Gushchin , Zach O'Keefe , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v3 0/7] Split a folio to any lower order folios In-Reply-To: <20230404144727.e613116684dbd65a4b4745c1@linux-foundation.org> Message-ID: <49ee481e-452f-61c7-2da5-28de2cf3de2@google.com> References: <20230403201839.4097845-1-zi.yan@sent.com> <20230404144727.e613116684dbd65a4b4745c1@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 4 Apr 2023, Andrew Morton wrote: > On Mon, 3 Apr 2023 16:18:32 -0400 Zi Yan wrote: > > > File folio supports any order and people would like to support flexible orders > > for anonymous folio[1] too. Currently, split_huge_page() only splits a huge > > page to order-0 pages, but splitting to orders higher than 0 is also useful. > > This patchset adds support for splitting a huge page to any lower order pages > > and uses it during file folio truncate operations. > > This series (and its v1 & v2) don't appear to have much in the way of > detailed review. As it's at v3 and has been fairly stable I'll queue > it up for some testing now, but I do ask that some reviewers go through > it please. Andrew, please don't let this series drift into 6.4-rc1. I've seen a bug or two (I'll point out in response to those patches), but overall I don't see what the justification for the series is: done because it could be done, it seems to me, but liable to add surprises. The cover letter says "splitting to orders higher than 0 is also useful", but it's not clear why; and the infrastructure provided seems unsuited to the one use provided - I'll say more on that truncation patch. Thanks, Hugh