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[83.90.141.187]) by smtp.gmail.com with ESMTPSA id x26-20020a1709060a5a00b00877f2b842fasm7129078ejf.67.2023.01.30.08.49.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Jan 2023 08:49:28 -0800 (PST) From: Jesper Dangaard Brouer X-Google-Original-From: Jesper Dangaard Brouer Message-ID: <4d2d1d1d-1dc8-60d7-8999-f5ea571107c4@redhat.com> Date: Mon, 30 Jan 2023 17:49:27 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Cc: brouer@redhat.com, nbd@nbd.name, davem@davemloft.net, edumazet@google.com, hawk@kernel.org, ilias.apalodimas@linaro.org, linux-kernel@vger.kernel.org, linyunsheng@huawei.com, lorenzo@kernel.org, netdev@vger.kernel.org, pabeni@redhat.com Subject: Re: [net PATCH] skb: Do mix page pool and page referenced frags in GRO Content-Language: en-US To: Jakub Kicinski , Alexander Duyck References: <04e27096-9ace-07eb-aa51-1663714a586d@nbd.name> <167475990764.1934330.11960904198087757911.stgit@localhost.localdomain> <20230126151317.73d67045@kernel.org> In-Reply-To: <20230126151317.73d67045@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 27/01/2023 00.13, Jakub Kicinski wrote: > On Thu, 26 Jan 2023 11:06:59 -0800 Alexander Duyck wrote: >> From: Alexander Duyck >> >> GSO should not merge page pool recycled frames with standard reference >> counted frames. Traditionally this didn't occur, at least not often. >> However as we start looking at adding support for wireless adapters there >> becomes the potential to mix the two due to A-MSDU repartitioning frames in >> the receive path. There are possibly other places where this may have >> occurred however I suspect they must be few and far between as we have not >> seen this issue until now. >> >> Fixes: 53e0961da1c7 ("page_pool: add frag page recycling support in page pool") >> Reported-by: Felix Fietkau >> Signed-off-by: Alexander Duyck > Exciting investigation! > Felix, out of curiosity - the impact of loosing GRO on performance is > not significant enough to care? We could possibly try to switch to > using the frag list if we can't merge into frags safely. Using the frag list sounds scary, because we recently learned that kfree_skb_list requires all SKBs on the list to have same refcnt (else the walking of the list can lead to other bugs). --Jesper