From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 795E2C83F1D for ; Tue, 15 Jul 2025 10:36:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F2B428D0006; Tue, 15 Jul 2025 06:36:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EDB548D0001; Tue, 15 Jul 2025 06:36:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DC9E48D0006; Tue, 15 Jul 2025 06:36:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id C9B018D0001 for ; Tue, 15 Jul 2025 06:36:23 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 332B71DA0DF for ; Tue, 15 Jul 2025 10:36:23 +0000 (UTC) X-FDA: 83666144646.20.B0E15B1 Received: from mail-ed1-f44.google.com (mail-ed1-f44.google.com [209.85.208.44]) by imf25.hostedemail.com (Postfix) with ESMTP id EB1FEA000A for ; Tue, 15 Jul 2025 10:36:20 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=AEg4R7Pf; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf25.hostedemail.com: domain of asml.silence@gmail.com designates 209.85.208.44 as permitted sender) smtp.mailfrom=asml.silence@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1752575781; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=RwJj2XW0Xtg7vWbGRjw0IzVQ1p4FfGBNG+AO9cOWVHY=; b=HgiQqmTT/mP0sUxqRPo1gJ8S0+JTtmjKm9uqIy2BMtm51lttkKto15eIDQvztJpRk61h1Z oecuZuLFDG+vwGsiORnvbocEqyaTywzlP00M/O0dwsbinAE8hXhjbjFm3yweaV/YgQdKvP FE6yweFzHSQq+v4fYL4V3gQ4PhP5H80= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1752575781; a=rsa-sha256; cv=none; b=TzmYoG+hJGY0FOk/XwvI2yKHAwqy5rv3vEcYE16CyHxfZX0mhmbeF7elIyjjsZ0b1soB72 rO9ZtDxZR8ohJKOVKtWpaWfQPtSH8rijSUmDZXKIa/RwL7K3f0oiLUJoEQG5Y4JRWpyt00 I8f7hkkCyIGlPcPGADAfmnWzfwyk7EQ= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=AEg4R7Pf; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf25.hostedemail.com: domain of asml.silence@gmail.com designates 209.85.208.44 as permitted sender) smtp.mailfrom=asml.silence@gmail.com Received: by mail-ed1-f44.google.com with SMTP id 4fb4d7f45d1cf-607cc1a2bd8so8811122a12.2 for ; Tue, 15 Jul 2025 03:36:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1752575779; x=1753180579; darn=kvack.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=RwJj2XW0Xtg7vWbGRjw0IzVQ1p4FfGBNG+AO9cOWVHY=; b=AEg4R7PfaC9BHL8ZcgfekW02jDMumd+b3dIjaHSF4NSON3R35iRVpheR5Yp0r2weqC Q4QqDjA+9r36KjAIAx9duCPW3vqQEZ5N7QaVYj93VD9yJ17QMhL5XYKFqS3NNB3fqd6q Y+F/J9jKCPnuX1MDN2h0+4x+HvX9yjAiSo+3TAVxb32ma+CYS1n9KaebMpDKuB/6BUfm Es9cbG6YXQVtQELkjc4wZ5HmjAIJp+kETFX1LFGVSGnh9IBVaArj1IBu9K2d7qsmP8Yf dPR8GR70ADnUW7zmxGpebZgONrlkSXXHZbYfzdVVhnWpeKWjzd6UGLRTOg1O3p5v3qnK vYQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752575779; x=1753180579; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=RwJj2XW0Xtg7vWbGRjw0IzVQ1p4FfGBNG+AO9cOWVHY=; b=avTiijJcbEGqdapWmSSaZPBs+AOPvQofrSueWRQSoqR2FXy9cURvh0txgmicAtBlD8 MhXL9hZE7E5LHNOFqt0Y/ybp0SbAs8mumAs9uscacEzjj7ApoLc7euBlbwhpIyJdRDYi mA6AmVfvNVuCmpu02aKw5ttHUtpS8GuMLqDRhaKLotJqDvLtmNUFQD4usE8Y7PDmfO/N rt5+IUvHcnopA2rPH+wt6iQzVRU7mAa8idlgcXAM0qOeCZtYtqtIRlM59/HA4QyvAjtf wwS59kXoZFaNL2xY7ZlqkahUy4ckrtqlfu1PNV4EKhPqWB+8QUeXTXo3CcJcJZ1ioqAY 0E6w== X-Forwarded-Encrypted: i=1; AJvYcCXRBDh3lVP/YXrbXo85YtA6YBGwZryq7ePN9CZ0Q/w66WnUVmchV0sB1ZrAYcZMkC/P30NLnAIPUw==@kvack.org X-Gm-Message-State: AOJu0Yz/eg2EQ5RFQuRXNWGPPd7CCz8uw3D+t5rG/5FGh59Xatfr2FFm HnpsWsDLfNTKw3Zx3RcWE4wrbvmq3eCyG2brNtIPHCiiZPQYTebmfmBS X-Gm-Gg: ASbGncvtgj2JJqaEJqoA9Yo3Kr68QKLi6jwjj3vVV/FyCktlUUeDKklfHkDdJubSHb1 6sL3d7lHVC5fnjh4hZJlSFgJuPz9SR4+QBe+mNReL0SqYKfztvd7GCCW1MIhaslI24GshY8gtsq EyovsqS19MQkL2K3oL7OH0xVMUTGhB7bQE7NDmzMXcml00KyjtKhkOfVCIYrmx0LqLgiC8Rr04r kK78OD3epUoVfqLTZFApVfSBhxAWGl8g3bue9fPGdlOA6SsXfoP7jQXPlCcNaewGLUiRZzkrIkl OiiMU9LrhpAF719Wkvsw1f1mf/cogRseoCrETuJPYB43k8eMoIDMNZ/2W9jyEQTaw/2vgtGO8sO ZQth2ee9vuqNkWqBJy1pmHi+PD6ZwdWtTZ6RwKeFYxWxYQg== X-Google-Smtp-Source: AGHT+IGaK5G3wNkKd0FQXTFLEb3wcMNGQ8G+9vcipY4gHF5O0bM0XfRnvGt5TQBO6UmtOz1kGEnKVw== X-Received: by 2002:a17:907:930c:b0:ae6:a8c1:c633 with SMTP id a640c23a62f3a-ae6fc1fae79mr1633481566b.34.1752575779007; Tue, 15 Jul 2025 03:36:19 -0700 (PDT) Received: from ?IPV6:2620:10d:c096:325::1ac? ([2620:10d:c092:600::1:a4c1]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ae6e82dedd3sm976790966b.150.2025.07.15.03.36.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Jul 2025 03:36:18 -0700 (PDT) Message-ID: <9bed2f6e-6251-4d0c-ad1e-f1b8625a0a10@gmail.com> Date: Tue, 15 Jul 2025 11:37:45 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v10 02/12] netmem: use netmem_desc instead of page to access ->pp in __netmem_get_pp() To: Mina Almasry , Byungchul Park Cc: willy@infradead.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel_team@skhynix.com, ilias.apalodimas@linaro.org, harry.yoo@oracle.com, akpm@linux-foundation.org, andrew+netdev@lunn.ch, toke@redhat.com, david@redhat.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, vishal.moola@gmail.com, hannes@cmpxchg.org, ziy@nvidia.com, jackmanb@google.com, wei.fang@nxp.com, shenwei.wang@nxp.com, xiaoning.wang@nxp.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, anthony.l.nguyen@intel.com, przemyslaw.kitszel@intel.com, sgoutham@marvell.com, gakula@marvell.com, sbhatta@marvell.com, hkelam@marvell.com, bbhushan2@marvell.com, tariqt@nvidia.com, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, saeedm@nvidia.com, leon@kernel.org, mbloch@nvidia.com, danishanwar@ti.com, rogerq@kernel.org, nbd@nbd.name, lorenzo@kernel.org, ryder.lee@mediatek.com, shayne.chen@mediatek.com, sean.wang@mediatek.com, matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com, aleksander.lobakin@intel.com, horms@kernel.org, m-malladi@ti.com, krzysztof.kozlowski@linaro.org, matthias.schiffer@ew.tq-group.com, robh@kernel.org, imx@lists.linux.dev, intel-wired-lan@lists.osuosl.org, linux-arm-kernel@lists.infradead.org, linux-wireless@vger.kernel.org, linux-mediatek@lists.infradead.org References: <20250714120047.35901-1-byungchul@sk.com> <20250714120047.35901-3-byungchul@sk.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: fwr6cztxtstgd5cjc4efapn59m5p9rha X-Rspamd-Queue-Id: EB1FEA000A X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1752575780-380933 X-HE-Meta: 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 eIkrq7hA 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 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 7/14/25 20:37, Mina Almasry wrote: > On Mon, Jul 14, 2025 at 5:01 AM Byungchul Park wrote: ...>> +static inline struct netmem_desc *pp_page_to_nmdesc(struct page *page) >> +{ >> + DEBUG_NET_WARN_ON_ONCE(!page_pool_page_is_pp(page)); >> + >> + /* XXX: How to extract netmem_desc from page must be changed, >> + * once netmem_desc no longer overlays on page and will be >> + * allocated through slab. >> + */ >> + return (struct netmem_desc *)page; >> +} >> + > > Same thing. Do not create a generic looking pp_page_to_nmdesc helper > which does not check that the page is the correct type. The > DEBUG_NET... is not good enough. > > You don't need to add a generic helper here. There is only one call > site. Open code this in the callsite. The one callsite is marked as > unsafe, only called by code that knows that the netmem is specifically > a pp page. Open code this in the unsafe callsite, instead of creating > a generic looking unsafe helper and not even documenting it's unsafe. > >> /** >> * __netmem_get_pp - unsafely get pointer to the &page_pool backing @netmem >> * @netmem: netmem reference to get the pointer from >> @@ -280,7 +291,7 @@ static inline struct net_iov *__netmem_clear_lsb(netmem_ref netmem) >> */ >> static inline struct page_pool *__netmem_get_pp(netmem_ref netmem) >> { >> - return __netmem_to_page(netmem)->pp; >> + return pp_page_to_nmdesc(__netmem_to_page(netmem))->pp; >> } > > This makes me very sad. Casting from netmem -> page -> nmdesc... The function is not used, and I don't think the series adds any new users? It can be killed then. It's a horrible function anyway, would be much better to have a variant taking struct page * if necessary. > Instead, we should be able to go from netmem directly to nmdesc. I > would suggest rename __netmem_clear_lsb to netmem_to_nmdesc and have > it return netmem_desc instead of net_iov. Then use it here. Glad you liked the diff I suggested :) In either case, seems like it's not strictly necessary for this iteration as __netmem_get_pp() should be killed, and the rest of patches work directly with pages. > We could have an unsafe version of netmem_to_nmdesc which converts the > netmem to netmem_desc without clearing the lsb and mark it unsafe. > -- Pavel Begunkov