From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F10013E714A; Mon, 18 May 2026 09:34:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779096855; cv=none; b=TV25xEH422VaYW/8a6Bwn0IRZoFJ+0MGbeEeneip4QFW2S2SsbmMvtX6Qd9NUtkkbpqlfnTxB8/XPdE3icc57rnL3AkSoxe9WTz6YtozlQ+UPP1Wi6GneOEPp2hjAzLkYUtRaE7x6dkwB5OvSlLECA7EhsTYhvOrx10417ff/GI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779096855; c=relaxed/simple; bh=GzBzHDjnj4M3YTbCmBceQUc3zfWmzR4wFD9lrvfEGjY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=G3y6CkFIMDDb/Bh1TkMkd6/Nz8YAUHfhOiEvPt+auTXbvgYNuybXeIrNi2TF0L75icYv9T/9HWgqUCK0AqsXz5YbOdoeZWkPLcsQKDa2H3GzX0EQurXW911tvHeATKrck95eHONIbsZOyFF0xninMMxDAMk33YAPbqDQRysYpio= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sZEb6K2Y; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sZEb6K2Y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00108C2BCB7; Mon, 18 May 2026 09:34:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1779096854; bh=GzBzHDjnj4M3YTbCmBceQUc3zfWmzR4wFD9lrvfEGjY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=sZEb6K2YedoHePpZc1igvCSBfZNBrGJBi8jQLbBUY2nThD+L/3S8D9jqg17V76XK6 FSM2oQQMeno2AKFYtifyrgLOfCZDthPUxHTWx8eZvyyDrqzkk2Hrec75AZN9qsVAwa UMG9lre442aR/vAZD6Xuug6/4fzcx9l4wR+eOhpIKLjS9h1nzotoIZ5QDBClDpEmcm LVGaHGK7CXXiOcgZKSicJhfNM2qk0bu+yhtViubdsNc8fyQu3Vsr3PFQPOiFZCJYIf RDiUHxvHBV8BpypAMXbUQDMjWAZkjHe6asgWo9C7IPUOV2FMkDgmseugS+orIIQZow AHur9V0RknTsA== Message-ID: <65d11b12-5696-4403-8062-3ae65ca9113e@kernel.org> Date: Mon, 18 May 2026 11:33:59 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] mm: introduce a new page type for page pool in page type To: Byungchul Park Cc: Dragos Tatulea , linux-mm@kvack.org, akpm@linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel_team@skhynix.com, harry.yoo@oracle.com, ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, kuba@kernel.org, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, saeedm@nvidia.com, leon@kernel.org, tariqt@nvidia.com, mbloch@nvidia.com, andrew+netdev@lunn.ch, edumazet@google.com, pabeni@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, horms@kernel.org, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, ilias.apalodimas@linaro.org, willy@infradead.org, brauner@kernel.org, kas@kernel.org, yuzhao@google.com, usamaarif642@gmail.com, baolin.wang@linux.alibaba.com, almasrymina@google.com, toke@redhat.com, asml.silence@gmail.com, bpf@vger.kernel.org, linux-rdma@vger.kernel.org, sfr@canb.auug.org.au, dw@davidwei.uk, ap420073@gmail.com References: <20260224051347.19621-1-byungchul@sk.com> <982b9bc1-0a0a-4fc5-8e3a-3672db2b29a1@nvidia.com> <20260513121805.GA22430@system.software.com> <8348d867-f8a1-432c-be2d-699ad96b2e93@kernel.org> <20260513123920.GA51788@system.software.com> <627bb280-be44-4648-8771-5a479cda988f@kernel.org> <20260513132636.GA75142@system.software.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/13/26 15:26, Byungchul Park wrote: > On Wed, May 13, 2026 at 03:02:43PM +0200, David Hildenbrand (Arm) wrote: >> On 5/13/26 14:39, Byungchul Park wrote: >>> On 5/13/26 14:18, Byungchul Park wrote: >>> >>> This is not final patch, but for sharing the rough idea *with code* - >>> maybe there are more points in code that should be adjusted by the >>> change. I just typed the draft patch quick just for sharing idea. >>> >>> If we should allow pp type pages to be used in mapping as well, then >>> we should allow a page to keep both its type and mapcount at the same >>> time. Am I missing something? >> >> We don't want code to accidentally overflow mapcounts into these bits and have >> them wrongly be detected as page types. >> >> This is just very fragile. > > Okay. Thanks for the explanation. Plus, the adjustment I mentioned > might not be as simple as I thought it'd be. > > So sorry about the noise. I'm a zombie now. I'll think about it after > some rest. It's a shame we didn't get reports earlier that we do have some vm_insert_page() users :( -- Cheers, David