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 912AC28507B; Sat, 8 Nov 2025 02:37:15 +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=1762569435; cv=none; b=qpmS0flzEsJqquTpYozqwHFLCZxIcv4b5VKl7adu2eHLJJml9nQHGLjyxp3kUv9/kLE7FEt4xxaqywybyb7M1mnzs20uwv+lPqb243tjv7qmKfNYtdErxcQ1c7icFKku+b/EnNjkenc/UVPingKCAQb4E4sJDiAC6WFL2l055Zk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762569435; c=relaxed/simple; bh=Ou3u7Vf6165AwGz1NI7XrAGwfnZWVMEdqoH1Q7dBYYk=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=QqWJrqHeFSKRg5Yri/c5atqp+OF9UBbyryTzwyQh2GTPaFQnzUAG3MhXGjeeJJrb1i0sv67N/5OWKrLtNsISMZUvW0d4Strtb+olz8UHJGqmv289FhkL1+ZYtdu2NdB6aWsbyt6r/HMT/zZYtyWDplTn/vpsZrvuYsnD4y+3A2s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=u1eDVBuy; 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="u1eDVBuy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 07224C19422; Sat, 8 Nov 2025 02:37:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762569435; bh=Ou3u7Vf6165AwGz1NI7XrAGwfnZWVMEdqoH1Q7dBYYk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=u1eDVBuyluzoT6wpUlZ1bNsISDdrnxrud/MWHNRrWneUQUSr0tLuPmnvHaGQ4xM4N //QJVSvXi9HicgXpdx9lhmTzGfyQd1bxAmnkwgqJd4+HcNQjvlaqLETmjHzDwMocZG 8VBtwlLx06pOqPlDEr20kSSpYKH6ZdUF4BnNlcvHfDy2+SaerJT4o0RKUNtzkA3de2 RDvboLOVpWoce0ylhnS/eztY27WUcAML5hVi3DM2XGkcgXhW2UE1gkvicQXHNY4GoN dXUHNw5MJNUrRv6j79+MScwp6ZAzr0iGyf4P1L4ym85uTBntzQGq+IZTRkJHrnBc40 AZ06qf8B8xzzA== Date: Fri, 7 Nov 2025 18:37:12 -0800 From: Jakub Kicinski To: Byungchul Park Cc: linux-mm@kvack.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, 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, akpm@linux-foundation.org, david@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, dtatulea@nvidia.com Subject: Re: [RFC mm v5 1/2] page_pool: check nmdesc->pp to see its usage as page pool for net_iov not page-backed Message-ID: <20251107183712.36228f2a@kernel.org> In-Reply-To: <20251108022458.GA65163@system.software.com> References: <20251103075108.26437-1-byungchul@sk.com> <20251103075108.26437-2-byungchul@sk.com> <20251106173320.2f8e683a@kernel.org> <20251107015902.GA3021@system.software.com> <20251106180810.6b06f71a@kernel.org> <20251107044708.GA54407@system.software.com> <20251107174129.62a3f39c@kernel.org> <20251108022458.GA65163@system.software.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sat, 8 Nov 2025 11:24:58 +0900 Byungchul Park wrote: > On Fri, Nov 07, 2025 at 05:41:29PM -0800, Jakub Kicinski wrote: > > On Fri, 7 Nov 2025 13:47:08 +0900 Byungchul Park wrote: > > > The offset of page_type in struct page cannot be used in struct net_iov > > > for the same purpose, since the offset in struct net_iov is for storing > > > (struct net_iov_area *)owner. > > > > owner does not have to be at a fixed offset. Can we not move owner > > to _pp_mapping_pad ? Or reorder it with type, enum net_iov_type > > only has 2 values we can smoosh it with page_type easily. > > I'm still confused. I think you probably understand what this work is > for. (I've explained several times with related links.) Or am I > missing something from your questions? > > I've answered your question directly since you asked, but the point is > that, struct net_iov will no longer overlay on struct page. > > Instead, struct netmem_desc will be responsible for keeping the pp > fields while struct page will lay down the resonsibility, once the pp > fields will be removed from struct page like: I understand the end goal. I don't understand why patch 1 is a step in that direction, and you seem incapable of explaining it. So please either follow my suggestion on how to proceed with patch 2 without patch 1 in current form. Or come back when have the full conversion ready.