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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1voQtR-00000005d1T-3eHV; Fri, 06 Feb 2026 18:49:25 +0000 Date: Fri, 6 Feb 2026 18:49:25 +0000 From: Matthew Wilcox To: "David Hildenbrand (Arm)" Cc: xu.xin16@zte.com.cn, akpm@linux-foundation.org, chengming.zhou@linux.dev, hughd@google.com, wang.yaxin@zte.com.cn, yang.yang29@zte.com.cn, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: ksm: initialize rmap values directly and make them const Message-ID: References: <202602061522548871ohgXN8z0qq87sTSX-yZc@zte.com.cn> <5a1cf097-5ab4-41d1-a707-a709de6210cf@kernel.org> <3192eca4-1c90-44ed-8386-bf635db357c4@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3192eca4-1c90-44ed-8386-bf635db357c4@kernel.org> X-Rspam-User: X-Rspamd-Queue-Id: 31C4A1C000B X-Rspamd-Server: rspam07 X-Stat-Signature: h9tokgi58ws5xa7gj1dhg5tr8zxsnqn6 X-HE-Tag: 1770403770-417800 X-HE-Meta: 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 0o1r+zyw Kkp6jWf6HMP+MuR4uEN4aFdRClgk3YMoAR5lhiq7XNz2lTgE4O1DiyreyWSLpJZzs68OBCocz7bsf8W2sh8c65Zo3hNPx5sZHU1/AkuGjmk7znuupNmbzSQYpCtnKdA6d4UfSRmw20RD+i2pMmE91B58Sauf51FbueFi/cWip/YNDYGSFgwJkXqgF6rCJK9JidFEwSfwczT0p/yvkKQ3fEAykhBlGvSwGer0CpSFmtIL0cSZcsgecBxTrH5OoI/1TIE4GxBgbDZ6Iq7UOwpoQN4oRdSonPFCOO0IsPpCJ0V0kSXQ= 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: List-Subscribe: List-Unsubscribe: On Fri, Feb 06, 2026 at 07:09:56PM +0100, David Hildenbrand (Arm) wrote: > On 2/6/26 18:34, David Hildenbrand (Arm) wrote: > > On 2/6/26 16:29, Matthew Wilcox wrote: > > > On Fri, Feb 06, 2026 at 03:22:54PM +0800, xu.xin16@zte.com.cn wrote: > > > > make them const to make code more robust. Besides, since KSM > > > > folios are always > > > > order-0, so folio_nr_pages(KSM folio) is always 1, so the line: > > > > > > > >     "pgoff_end = pgoff_start + folio_nr_pages(folio) - 1;" > > > > > > > > becomes directly: > > > > > > > >     "pgoff_end = pgoff_start;" > > > > > > How do you know KSM folios will always be order 0?  I don't.  NAK this > > > change. > > > > Once that changes we can revisit. ACK from me stands. > > And just to elaborate a bit: I don't see support for > 0 happening any time > soon, and it will require significant changes that I am not even sure we > would want to maintain upstream :) OK, you're the KSM maintainer. There doesn't seem to be anywhere else in the KSM code which handles large folios, so this is just removing code that was recently added?