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 0286FC148; Thu, 3 Jul 2025 13:27:26 +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=1751549247; cv=none; b=UwD+4dz+hnFQkVz/1qG+dtDy/Li4FiZztbzDLrMAXOtIsb72JoxgIM9evl2VN9g+pLcdZix/8GCwN09EwTvQLhSKiy849sLZB1tn6q0Se2mVdXGlEhUk3ATZxDTK2LN6pI8ECQqerGQ2ZN9Zg41Q8IZrWXXArt+2869vTiF4Rqs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751549247; c=relaxed/simple; bh=02Jt1Cymbs57OvvyqASB9yCoi82LcJgdykJmqeCnv8Y=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=mMkGZ4bLIybJdAc/rE7cFAOt1+viRYOvjhsZHVerbkf+0kBR4epz2h2HHE1i4xdb7LsWN9PJKBP3jioP9NXyByroOREV8SW1YLPqcI1PTrJjwcGbUEX5czJNGkNplOO1+SXsHc3bYYczv0SZ3GW3jZM3qiCalPD9ZlTFxmal0hk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cCmmqMiS; 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="cCmmqMiS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3D7ECC4CEE3; Thu, 3 Jul 2025 13:27:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751549246; bh=02Jt1Cymbs57OvvyqASB9yCoi82LcJgdykJmqeCnv8Y=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=cCmmqMiSMdW95nEPe1HJViQllZgFpmCY4isMnJBc6miFP3aSlDhfQg5wjWCPHBjUO jHIeWhmx8m/x5oTMYwK0pov1zIDGKIMVDEnEtNxEXKtts1KZ2e+bU816zmaE07OmaY vsGJqNigVBrmny+x/6apIvX4eGvR6RjhALEZ6hvMDFB4gVoeUWGD3HDIDGVEkoDAC0 Fg1ZBJkg7bp+v9NK8JyV2aTfdU6REn1Ex58+/5nr3A6gL2RPe1L6saJxdppQTUV8LE qk0RP9lsJzodZ4eLLvskzTzyRiXaqlBfL/8EMYRLQDZ2cgzGfZLwYoSk4cD4S5ia8M dKDsCjqTRS9qQ== Message-ID: <720df841-8300-490a-af77-8d20f833c042@kernel.org> Date: Thu, 3 Jul 2025 15:27:13 +0200 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v8 5/5] page_pool: make page_pool_get_dma_addr() just wrap page_pool_get_dma_addr_netmem() To: Byungchul Park , willy@infradead.org, netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel_team@skhynix.com, kuba@kernel.org, almasrymina@google.com, ilias.apalodimas@linaro.org, harry.yoo@oracle.com, akpm@linux-foundation.org, davem@davemloft.net, john.fastabend@gmail.com, andrew+netdev@lunn.ch, asml.silence@gmail.com, toke@redhat.com, tariqt@nvidia.com, edumazet@google.com, pabeni@redhat.com, saeedm@nvidia.com, leon@kernel.org, ast@kernel.org, daniel@iogearbox.net, 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, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, vishal.moola@gmail.com, hannes@cmpxchg.org, ziy@nvidia.com, jackmanb@google.com References: <20250702053256.4594-1-byungchul@sk.com> <20250702053256.4594-6-byungchul@sk.com> Content-Language: en-US From: Jesper Dangaard Brouer In-Reply-To: <20250702053256.4594-6-byungchul@sk.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 02/07/2025 07.32, Byungchul Park wrote: > The page pool members in struct page cannot be removed unless it's not > allowed to access any of them via struct page. > > Do not access 'page->dma_addr' directly in page_pool_get_dma_addr() but > just wrap page_pool_get_dma_addr_netmem() safely. > > Signed-off-by: Byungchul Park > Reviewed-by: Mina Almasry > Reviewed-by: Ilias Apalodimas > Reviewed-by: Toke Høiland-Jørgensen > Reviewed-by: Pavel Begunkov > --- > include/net/page_pool/helpers.h | 7 +------ > 1 file changed, 1 insertion(+), 6 deletions(-) > > diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h > index 773fc65780b5..db180626be06 100644 > --- a/include/net/page_pool/helpers.h > +++ b/include/net/page_pool/helpers.h > @@ -444,12 +444,7 @@ static inline dma_addr_t page_pool_get_dma_addr_netmem(netmem_ref netmem) > */ > static inline dma_addr_t page_pool_get_dma_addr(const struct page *page) > { > - dma_addr_t ret = page->dma_addr; > - > - if (PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA) > - ret <<= PAGE_SHIFT; > - > - return ret; > + return page_pool_get_dma_addr_netmem(page_to_netmem(page)); Wow - the amount of type casting shenanigans going on here make the code hard to follow. This code changes adds an extra "AND" operation, but we don't have a micro-benchmark that tests the performance of a DMA enabled page_pool, so I cannot tell if this add any overhead. My experience tells me that this extra AND-operation will not be measurable. I see a lot of reviewed-by from people I trust, so you also get my page_pool maintainer ack. Acked-by: Jesper Dangaard Brouer --Jesper